Real-time measuring device for wafer film thicknessTechnical Field
The invention relates to the technical field of semiconductor equipment, in particular to a wafer film thickness real-time measuring device in semiconductor test equipment.
Background
In the manufacture of semiconductor integrated circuits, measurement equipment is an integral part of the semiconductor industry from initial wafer growth to later chip packaging.
Common thin films are Poly-Si, siN2, siO2, etc. and various metal films including AI, cu, etc. The Spectrum Reflectometer (SR) is used for determining the thickness and refractive index of dielectric, semiconductor and metal films by analyzing reflected light, is mainly used for measuring micron-sized film thickness materials, and can be applied to a wafer in special ways by adding some expansion functions. The interferometry film measurement technology is a method for calculating the thickness of a film by utilizing white light to be incident on the surface of the film and detecting light reflected by two surfaces of the film to form interference light signals, and has high measurement speed and high precision, and is widely focused for nondestructive measurement.
At present, most of spectral reflectometers in the market have single performance and function, are more in manual control, low in precision and slower in measurement speed, cannot be integrated or matched with other equipment for use, and are not suitable for being used in semiconductor integrated circuit manufacturing.
The technology is not much mastered in China, and most of core technologies and equipment are mastered in the hands of several equipment manufacturers abroad. Research on the technology is also an important link of the overall development of the semiconductor industry, and the mastering of the autonomous research and development technology is said to be indistinct.
Disclosure of Invention
The invention aims to provide a wafer film thickness real-time measuring device.
In order to achieve the above purpose, the invention provides a real-time measuring device for wafer film thickness, which comprises an optical measuring module, a transmission module and a data analysis module, wherein:
The optical measurement module includes:
A first light source and a second light source for providing light beams required for measurement and imaging, respectively;
The light splitting devices are arranged in a plurality and are used for splitting and combining light beams;
a plurality of reflection devices for guiding the light beam into the light path;
a tube mirror lens for adjusting focusing of the light beam for alignment and measurement compensation;
The objective lens is used for perpendicularly incident the light path on the surface of the wafer and forming a focusing light spot capable of moving on the surface of the wafer;
the image sensing unit is used for acquiring image signal information of the wafer reflected light beam so as to observe and align the light spot;
the spectrum detection unit is used for detecting the reflection spectrum information of the wafer reflection light beam;
The optical measurement module is configured to form a first light path after light beams emitted from a first light source and a second light source are combined through the light splitting device, wherein the first light path is guided to the objective lens through the tube lens and the reflecting device, the objective lens focuses the light beams on the surface of the wafer;
the transmission module includes:
An optical transmission unit configured to transmit at least a tube lens and an objective lens in the optical measurement module to perform alignment and measurement compensation together;
the wafer transmission unit is used for loading a wafer and driving the wafer to rotate or rotate and translate;
the data analysis module is used for acquiring the image signal information and the reflection spectrum information obtained from the optical measurement module so as to obtain the wafer surface film information after calculation processing.
Further description of the relevant matters of the invention is as follows:
By implementing the technical scheme, the device adopts the principle and structure of spectral reflection measurement, the measuring wave band covers ultraviolet to infrared, the multiplying power of an optical system is adjustable, the real-time monitoring of measurement and imaging can be realized at the same time, the functions of the device can be selected according to the requirements, the measuring requirements of various materials and different structures are met, the original transmission part for scanning all positions of a wafer acts on the wafer tray, namely, at least one rotating shaft and at least two translation shafts are arranged on one wafer transmission part, the mechanism is bulky and cannot be greatly adjusted and changed, the whole structure of the device is compact, the structure for realizing relative displacement between an objective lens and the wafer is arranged on an optical transmission unit and a wafer transmission unit, the integration level is high, the device can independently work and can also be integrated or compatible to other devices according to the requirements for use, the device mainly comprises three parts of optical measurement, transmission and data analysis, the system integration level is high, the measuring speed is high, and the accurate measurement of performance indexes such as film thickness, the surface microstructure, the whole curvature of the wafer and the like can cover the requirements of most semiconductor manufacturing on the wafer.
In the optical measurement module part in the technical scheme, the design wave band of the optical system covers ultraviolet to near infrared, and 190 nm-1500 nm can be compatible.
In the above technical scheme, the optical measurement module part and the light source can be replaced freely, and various independent light sources such as ultraviolet section, visible section, infrared section and the like can be selected according to requirements, and various light sources can be combined for use and coupled into the optical system.
In the above technical solution, in the optical measurement module portion, the light source may take light in a manner of optical fiber coupling or spatial direct coupling, and the light source may be selected according to the use condition.
In the above-described technical solution, in the optical measurement module portion, a light source such as a xenon lamp, a halogen lamp, a deuterium lamp, an LDLS, or the like may be used.
In the above technical solution, the objective lens of the optical measurement module part can be replaced independently, and 2 or more objective lenses can be installed for switching.
In the above technical solution, the objective lens can be switched to be suitable for objective lenses with different wave bands, and also can be switched to objective lenses with different multiplying powers. The objective lenses with different wave bands can be matched with a broadband spectrum for use, the objective lenses with different multiplying powers can adjust the size of a measuring light spot, and the imaging device can measure wafer patterns with different sizes and can meet the requirements of different imaging fields.
In the above technical solution, in the optical measurement module portion, optical elements such as a light splitting device and an objective lens used in the optical system may be applied to 190 nm-1500 nm, where the light splitting device uses a broadband film plating element and a point grid spectroscope, and especially the point grid spectroscope may adjust the size of the point grid according to the light splitting proportion, and the wavelength band may be applied to 190 nm-1500 nm.
In the above technical scheme, in the optical measurement module part, the receiving end adopts a mode of receiving measurement light and imaging light simultaneously, and the receiving end comprises an image sensing unit and a spectrum detection unit, so that the real-time observation function of a measurement area can be realized.
In the above technical scheme, the receiving end receives the measurement light by using an optical fiber or a direct coupling mode, and the optical fiber can divide the broad spectrum into corresponding receivers in a one-to-many mode for analysis, and collect and analyze data at one time.
In the above technical solution, the receiving end may receive and process the signal by using a spectrometer, a detector, a CMOS, a CCD or a diode detection array (PDA), a signal processing circuit, and the like.
In the above technical solution, in the optical measurement module part and the transmission module, the lens of the tube mirror may be used to move to adjust the focal length in the Z direction, or the lens of the objective lens may be used to adjust the Z direction, or the alignment and measurement compensation may be performed by moving at the same time. The tube lens and the objective lens use a one-dimensional translation mode, can be controlled by adopting a piezoelectric displacement table mode when the precision requirement is high, can realize nanoscale transmission, and greatly reduces the volume.
In the above technical scheme, in the optical measurement module part and the transmission module, the X-axis of the scanning axis is arranged on the objective lens side, the translation of the objective lens is utilized to finish the movement of the wafer in the X-axis direction, and meanwhile, the emergent end of the objective lens adopts parallel light design, so that imaging and measurement are not affected during the movement.
In the above technical solution, in the wafer transmission unit, the X axis of the scanning axis may be installed on the objective lens, the translation of the objective lens is used to complete the measurement movement of the wafer in the X axis direction, and the transmission part is matched with the uniaxial rotation of the θ axis, so that the measurement and observation of the surface position of the whole wafer may be realized.
In the above technical solution, in the transmission module, the two-axis measurement mode of the X and θ axes is that when the surface position of the wafer is measured, the X axis only needs to move the length of the radius of the measured wafer, and the position measurement of the entire wafer surface can be achieved through the rotation of the θ axis. The mode greatly shortens the movement distance, so that the measuring light path is more compact, and the space is saved.
In the above technical solution, when the X and θ axes are used in the wafer transmission unit, a Y axis may be coupled to the θ axis, and the length of the Y axis may be determined according to the actual wafer transmission distance and the equipment space. The X, theta and Y three axes can realize high-precision centering of the center centering of the wafer. The requirements of high-precision repeated measurement and high-precision positioning of the pattern piece are met.
In the above technical solution, in the transmission module, the distance and precision of the motion of the Y axis transmission assembly are adjustable as required. The Y-axis may be eliminated when high precision alignment and wafer Y-direction drive are not required. When high-precision center alignment is required to be realized, a Y-axis with shorter stroke and higher precision can be used for compensating the Y direction of the rotation center. When the distance between the upper opening position and the measuring position is longer, the long-stroke Y-axis can be adopted for carrying out wafer transmission.
In the above technical solution, in the transmission module, the wafer transmission unit includes a wafer tray capable of being compatible with 8-inch and 12-inch wafers.
In the above technical solution, in the wafer transmission unit, a macro defect scanning assembly may be installed at a wafer opening.
In the above technical solution, in the macro defect scanning assembly in the wafer transmission unit, the macro defect scanning assembly includes three parts of a camera, a light source and a lens. When the wafer is loaded on the manipulator or transported, the macroscopic defect on the surface of the wafer is detected by using the camera and the lens, so that the defects such as dust, scratches, particles and the like on the surface of the wafer can be detected instead of eyes, and when the wafer is loaded on the wafer and moved to a measuring area, the defects on the surface of the wafer are displayed in an image form.
In the above technical scheme, in the data analysis module part, the function of synchronous acquisition of multiple systems can be realized. The imaging light path and the measuring light path of the system can be synchronously acquired in real time, the two systems can simultaneously take the focal positions of the two systems, the focal positions are judged, the wafer measurement can save time, and the wafer measurement efficiency is improved.
In the above technical solution, in the data analysis module portion, the data analysis is performed using a common-path reference light. Different from the measurement mode with the reference piece, not only save time has promoted efficiency, and the error that different reference pieces brought that the common light path measurement mode also avoided has promoted measurement accuracy.
In the technical scheme, the common light path measurement mode adopted in the data analysis module part adopts a cut-in light splitting sheet in a parallel light path on one hand, and collects and couples a part of measurement light into a receiving device, and on the other hand, a double-channel spectrometer can be used, and the signal is directly divided in proportion in the receiving-end spectrometer and then is processed without splitting.
In the above technical solution, the common optical path measurement mode adopted in the data analysis module part fixes the reference sheet in the optical path, adopts the beam splitter, cuts the reference sheet into the optical path, performs calibration processing, and performs contrast processing after adding the measured object or signal, and then subtracts the reference signal.
In the above technical solution, in the data analysis module portion, a polarizing device is added at a parallel light position between the objective lens and the tube lens, and the polarizing device may move along the X direction along with the objective lens, or may be fixed at the parallel light position.
In the above technical solution, in the polarizing device of the data analysis module part, the polarizing device may be a fixed polarization state and angle birefringent device, or may be an elasto-optical modulator (PEM) capable of changing the polarization state by modulating the voltage.
In the present application, unless explicitly specified and limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally formed, mechanically connected, directly connected, indirectly connected via an intermediate medium, or in communication with each other between two elements or in interaction with each other, unless explicitly specified otherwise. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art according to the specific circumstances.
In the present application, the terms "center," "upper," "lower," "axial," "bottom," "inner," "outer," and the like refer to an azimuth or positional relationship based on the azimuth or positional assembly relationship shown in the drawings, for convenience of description and simplification of the description, and do not indicate or imply that the apparatus or element referred to must have a specific azimuth, be constructed and operated in a specific azimuth, and therefore should not be construed as limiting the application.
Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In the description of the present application, the meaning of "plurality" means at least two, for example, two, three, etc., unless specifically defined otherwise.
Due to the application of the scheme, compared with the prior art, the invention has the following advantages and effects:
By using the technical scheme of the invention, the measuring wave band for measuring the film thickness of the wafer in real time covers ultraviolet to infrared, the design wave band of the optical system covers ultraviolet to near infrared, the optical system can be compatible with 190 nm-1500 nm, the light source can be freely replaced, various independent light sources such as ultraviolet, visible, infrared and the like can be selected according to the requirement, and various light sources can be combined for use and simultaneously coupled into the optical system. The light source can take light in a mode of optical fiber coupling or space direct coupling, and light sources such as xenon lamps, halogen lamps, deuterium lamps, LDLS and the like can be used.
By using the technical scheme of the invention, the multiplying power of the optical system is adjustable, the measuring objective lens can be independently replaced, 2 or more objective lenses can be arranged for switching, the measuring objective lens can be suitable for objective lenses with different wave bands, the objective lenses with different multiplying power can be used by matching a broadband spectrum, the objective lenses with different multiplying power can adjust the measuring spot size, and the measuring spot size can be used for measuring wafer patterns with different sizes, and meanwhile, the imaging field of view can be satisfied.
By using the technical scheme of the invention, the real-time monitoring of measurement and imaging can be realized at the same time, the receiving end adopts a mode of receiving measurement light and imaging light at the same time, the real-time observation function of a measurement area can be realized, data can be collected and analyzed at one time, the function can be selected according to the requirement, and the measurement requirements of various materials and different structures can be met.
By using the technical scheme of the invention, the measuring requirements of various materials and different structures can be met, the original transmission part for scanning all positions of the wafer acts on the wafer tray, namely, at least one rotation shaft and at least two translation shafts are arranged on one wafer transmission part, the mechanism is bulky and cannot be greatly adjusted and changed, the whole structure of the device is compact, the integration level is high, the device can independently work, and the device can be integrated or compatible to other devices according to the requirements for use.
By using the technical scheme of the invention, the measuring speed is high, the performance indexes such as the film thickness of the wafer, the microstructure of the surface of the wafer, the overall bending degree and the like can be accurately measured, and the requirements of most semiconductor manufacturers on the wafer measurement can be met.
Drawings
FIG. 1 is a schematic view of the appearance of an embodiment of the present invention;
FIG. 2 is a schematic diagram of a system of optical measurement module portions according to an embodiment of the present invention;
fig. 3 is a schematic diagram of displacement of the second mirror, the objective lens, the wafer and the one-dimensional displacement device in the Z direction in the embodiment of the present invention, and fig. 4 is a schematic diagram of the structure of the wafer transmission unit in the embodiment of the present invention.
The parts of the above figures are shown as follows:
1. First light source
2. First small hole
3. First spectroscopic device
4. Second light-splitting device
5. Tube mirror lens
6. First reflecting mirror
7. Second reflecting mirror
8. Objective lens
9. Third spectroscopic device
10. Second small hole
11. Spectrum optical fiber
12. Spectrum detection unit
13. Second light source
14. Image sensing unit
15. First linear displacement device
16. Second linear displacement table
17. One-dimensional linear displacement table
18. One-dimensional displacement device
19. Reference sheet
20. Theta axis rotating assembly
21 Y-axis transmission assembly
22. Tablet feeding port
23. Electric control box
24. Optical measuring part
83. Wafer with a plurality of wafers
80. And (5) combining and driving the whole.
Detailed Description
In order that the above objects, features and advantages of the application will be readily understood, a more particular description of the application will be rendered by reference to the appended drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. The present application may be embodied in many other forms than described herein and similarly modified by those skilled in the art without departing from the spirit of the application, whereby the application is not limited to the specific embodiments disclosed below.
As shown in fig. 1 to fig. 4, the embodiment of the invention provides a real-time measuring device for the film thickness of a wafer, which comprises an optical measuring module, a transmission module and a data analysis module, wherein the device adopts the principle and structure of spectral reflection measurement, the measuring wave band covers ultraviolet to infrared, the multiplying power of an optical system is adjustable, the real-time monitoring of measurement and imaging can be realized at the same time, and the measuring requirements of various materials and different structures are met. The device has compact integral structure and high integration level, can work independently, and can be integrated or compatible to other devices for use according to requirements.
As shown in fig. 1, the device in the embodiment of the invention mainly comprises an upper half part and a lower half part, wherein the upper half part comprises an optical measurement part 24 and a transmission part, and the lower half part comprises an electric cabinet 23, an air channel and a support. By adopting the structure, the structure is compact, the integration level is high, the module is divided clearly, and the maintenance and repair are convenient.
The real-time wafer measuring device with wide wave band, multiple multiplying power and high precision mainly comprises an optical measuring module, a transmission module and a data analysis module.
In one embodiment, the measuring device comprises an optical measuring module, a transmission module and a data analysis module, wherein:
The optical measurement module includes:
A first light source and a second light source for providing light beams required for measurement and imaging, respectively;
The light splitting devices are arranged in a plurality and are used for splitting and combining light beams;
a plurality of reflection devices for guiding the light beam into the light path;
The objective lens is used for perpendicularly incident the light path on the surface of the wafer and forming a focusing light spot capable of moving on the surface of the wafer;
the receiving end is used for acquiring optical information excited and reflected from the surface of the wafer;
The optical measurement module is configured to form a first optical path after light beams emitted from the first light source and the second light source are combined through the light splitting device, wherein the first optical path is led to the objective lens through the reflecting device, and the objective lens focuses the light beams on the surface of the wafer;
the transmission module includes:
an optical transmission unit configured to transmit at least the objective lens in the optical measurement module;
the wafer transmission unit is used for loading a wafer and driving the wafer to rotate or rotate and translate;
the data analysis module is used for acquiring optical information obtained from the receiving end so as to obtain the wafer surface film information after calculation processing.
By implementing the above embodiments, unlike the prior art, the optical information that is perpendicularly incident and reflected by the common optical path is received and processed by the receiving end in different manners, and meanwhile, the structure of the transmission part is also significantly improved, so that the structure of the device can be more compact and can work independently, and can be integrated or compatible to other devices according to the requirement, and the requirement of most semiconductor manufacturers on wafer measurement can be covered.
In another embodiment, a real-time measuring device for wafer film thickness is provided, the measuring device comprises an optical measuring module, a transmission module and a data analysis module, wherein:
the measuring device comprises an optical measuring module, a transmission module and a data analysis module, wherein:
The optical measurement module includes:
A first light source and a second light source for providing light beams required for measurement and imaging, respectively;
The light splitting devices are arranged in a plurality and are used for splitting and combining light beams;
a plurality of reflection devices for guiding the light beam into the light path;
a tube mirror lens for adjusting focusing of the light beam for alignment and measurement compensation;
The objective lens is used for perpendicularly incident the light path on the surface of the wafer and forming a focusing light spot capable of moving on the surface of the wafer;
the image sensing unit is used for acquiring image signal information of the wafer reflected light beam so as to observe and align the light spot;
the spectrum detection unit is used for detecting the reflection spectrum information of the wafer reflection light beam;
The optical measurement module is configured to form a first light path after light beams emitted from a first light source and a second light source are combined through the light splitting device, wherein the first light path is guided to the objective lens through the tube lens and the reflecting device, the objective lens focuses the light beams on the surface of the wafer;
the transmission module includes:
An optical transmission unit configured to transmit at least a tube lens and an objective lens in the optical measurement module to perform alignment and measurement compensation together;
the wafer transmission unit is used for loading a wafer and driving the wafer to rotate or rotate and translate;
the data analysis module is used for acquiring the image signal information and the reflection spectrum information obtained from the optical measurement module so as to obtain the wafer surface film information after calculation processing.
Through implementation of the second embodiment, except that the first embodiment has the advantages that optical information vertically incident and reflected is received and processed by the receiving end in different manners, and meanwhile, the structure of the transmission part is also greatly improved, so that the structure of the device can be more compact and can work independently, and can also be integrated or compatible with other devices according to requirements, the device can cover the requirement of most semiconductor manufacturers on wafer measurement, besides the requirement that a tube lens can be used for moving and adjusting the focal length Z direction, an objective lens can be used for adjusting the focal length Z direction, and can also be used for simultaneously moving and compensating alignment and measurement, a one-dimensional translation manner can be used for controlling the tube lens and the objective lens in a manner of piezoelectric displacement table when the precision requirement is high, nanoscale transmission can be realized, the volume of a wafer film thickness real-time measurement device in the whole semiconductor test device is reduced, and because the flexibility of the device is reduced, the working efficiency and the working precision of the device can be increased, for example, the tube lens can be used for moving and adjusting the focal length Z direction, the lens can also be used for simultaneously adjusting the focal length Z direction, the focal length can be adjusted by adopting a lens can be simultaneously and a one-dimensional translation manner, and the focal length can be adjusted by different from the objective lens, and the requirement of the imaging lens can be simultaneously reduced, and the focal length can be different from being adjusted, and the imaging precision can be simultaneously, and the focal length can be adjusted by 83;
The optical measurement module comprises a first light source 1 and a second light source 13, which are respectively used for providing light beams required for measurement and imaging, a design wave band covering ultraviolet to near infrared, compatibility of 190nm to 1500nm, free replacement of the light sources, selection of various independent light sources such as ultraviolet, visible and infrared according to requirements, combination of various light sources, simultaneous coupling into an optical system, a plurality of light splitting devices for splitting and combining the light beams, a plurality of reflecting devices for guiding the light beams into a light path, a wide-band film coating device and a point grid spectroscope, wherein the wavelength band is applicable to 190nm to 1500nm, the point grid spectroscope is particularly applicable to 190nm to 1500nm according to the splitting proportion, the objective lens 8 is used for perpendicularly incidence of the light path on the surface of a wafer 83 and forming a focusing light spot capable of moving on the surface of the wafer 83, and a receiving end is used for obtaining optical information excited and reflected from the surface of the wafer 83.
The optical measurement module is configured to combine light beams emitted from the first light source 1 and the second light source 13 through the light splitting device to form a first light path, the first light path is led to the objective lens 8 through the reflecting device, the objective lens 8 focuses the light beams on the surface of the wafer 83, the first light path is excited and reflected by the surface of the wafer 83 back to the objective lens 8 to form a second light path, and the second light path is led to the receiving end through the reflecting device.
In the optical measurement module according to the embodiment of the invention, the receiving end comprises an image sensing unit 14 and/or a spectrum detection unit 12, the optical information comprises image signal information and/or reflection spectrum information, when the receiving end comprises the image sensing unit 14 or the spectrum detection unit 12, the second optical path is led to the image sensing unit 14 or the spectrum detection unit via a reflection device, when the receiving end comprises the image sensing unit 14 and the spectrum detection unit, the second optical path in the optical measurement module is led to a light splitting device, the light splitting device splits the second optical path into two beams, one beam is detected by the image sensing unit 14 and used for obtaining the image signal information, the other beam is led to the spectrum detection unit 12 via the reflection device and used for detecting the reflection spectrum information of the light beam reflected by the wafer 83.
The receiving end adopts a mode of receiving the measuring light and the imaging light simultaneously, so that the real-time observation function of the measuring area can be realized. At the receiving end, the spectrum optical fiber 11 or the direct coupling mode is used for receiving the measuring light, the spectrum optical fiber 11 can divide the broad spectrum into corresponding receivers in a one-to-many mode for analysis, and data are collected and analyzed at one time. The receiving end can receive and process signals in a spectrometer, a detector, a CMOS, a CCD or a diode detection array (PDA), a signal processing circuit and the like.
As shown in fig. 2, in the optical measurement module of the embodiment of the invention, the optical measurement module comprises a first optical splitter 3, a second optical splitter 4 and a third optical splitter 9, wherein the reflecting device comprises a first reflecting mirror 6 and a second reflecting mirror 7, and specifically comprises a first light source 1, a first small hole 2, a second light source 13, the first optical splitter 3, the second optical splitter 4, a tube lens 5, a first reflecting mirror 6, a second reflecting mirror 7, an objective lens 8, the third optical splitter 9, an image sensing unit 14, a second small hole 10, a spectrum optical fiber 11 and a spectrum detection unit 12;
The first light source 1 is used for coupling light sources with different spectrums on the first small hole 2 in an optical fiber or spectroscope mode to provide light beams required by measurement, the second light source 13 is used for providing light beams required by imaging in an optical fiber coupling or space direct coupling mode, the light beams emitted by the first light source 1 and the light beams emitted by the second light source 13 are combined through the first light splitting device 3 after passing through the first small hole 2, and the combined light forms a first light path after passing through the second light splitting device 4 and the tube lens 5, is reflected to the objective lens 8 by the first reflecting mirror 6 and the second reflecting mirror 7, and is focused on the surface of the wafer 83 by the combined light;
The combined beam light is excited by the surface of the wafer 83 and reflected back to the objective lens 8 to form a second light path, the second light path is reflected to the third light splitting device 9 by the second light splitting device 4 after passing through the second reflecting mirror 7, the first reflecting mirror 6 and the tube lens 5, the second light path is split into two beams by the third light splitting device 9, one beam is detected by the image sensing unit 14 and used for image observation and light spot alignment, the other beam is focused on the fiber core of the spectrum optical fiber 11 after passing through the second small hole 10, the spectrum optical fiber 11 conducts light to the spectrum detection unit 12 to obtain reflection spectrum information of the film, and the information of the film on the surface of the wafer 83 is obtained after calculation processing, and the optical transmission unit is configured to transmit at least the objective lens 8 and/or the tube lens 5 in the optical measurement module.
In the embodiment of the invention, the optical measurement module further comprises a reference sheet 19, the reference sheet 19 is used for emitting a reference beam, the reference beam is excited and reflected by the surface of the wafer 83 to form a second optical path or is directly coupled with the beam of the second optical path after being coupled with the beam of the first optical path, the optical transmission unit comprises a one-dimensional linear displacement table 17, the first reflecting mirror 6 is arranged on the one-dimensional linear displacement table 17, the one-dimensional linear displacement table 17 drives the first reflecting mirror 6 to displace in the direction perpendicular to the path of the first optical path through the second light splitting device 4 and the tube mirror lens 5, the first reflecting mirror 6 is a total reflecting mirror, the first reflecting mirror 6 is cut into the first optical path and the second optical path by using the one-dimensional linear displacement table 17 to measure the wafer 83, and the first reflecting mirror 6 is moved out of the first optical path and the second optical path by using the one-dimensional linear displacement table 17 to obtain the reference beam of the reference sheet 19.
Specifically, in the optical measurement module, the measurement objective lens 8 can be replaced independently, and 2 or more objective lenses 8 can be arranged for switching. The objective lens 8 can be switched and suitable for the objective lens 8 with different wave bands, and can also be switched for the objective lens 8 with different multiplying powers. The objective lenses 8 with different wave bands can be matched with a broadband spectrum for use, the objective lenses 8 with different multiplying powers can adjust the size of a measuring light spot, and the pattern measurement of wafers 83 with different sizes can be realized, and meanwhile, the use of different imaging fields can be met.
In the transmission module of the embodiment of the invention, the transmission module comprises an optical transmission unit and a wafer transmission unit, wherein the optical transmission unit is configured to transmit at least the objective lens 8 in the optical measurement module, and the wafer transmission unit is used for loading the wafer 83 and driving the wafer 83 to rotate or rotate and translate. The objective lens 8 is located above the wafer 83, and defines a Z direction as an up-down direction of the objective lens 8 and the wafer 83, an X direction perpendicular to the up-down direction, a Y direction perpendicular to the X, Z direction, and a θ axis as an axis of rotation about an axis of the Z direction.
The optical transmission unit comprises a one-dimensional linear displacement table 17, a second linear displacement table 16, a one-dimensional displacement device 18 and a first linear displacement device 15, wherein the one-dimensional linear displacement table 17 is used for cutting in or moving out the first reflecting mirror 6 into the first optical path and the second optical path, the second linear displacement table 16 is used for driving the objective lens 8 to translate in the X direction so as to realize the movement of the objective lens in the X direction when the wafer 83 is measured, the one-dimensional displacement device 18 is used for driving the objective lens 8 to move in the Z direction so as to realize the zooming of the objective lens 8, and the first linear displacement device 15 is used for driving the tube lens 5 to translate along the advancing direction of the first optical path. The one-dimensional displacement device 18 and the first linear displacement device 15 can be used for adjusting the focal length by moving the tube lens 5, adjusting the focal length Z direction by using the objective lens 8, and simultaneously moving the tube lens 5 and the objective lens 8 to perform alignment and measurement compensation, wherein the tube lens 5 and the objective lens 8 are controlled by adopting a one-dimensional translation mode, and a piezoelectric motor table can be used for controlling when the precision requirement is high, so that nano-scale transmission can be realized, and the volume is greatly reduced.
As shown in fig. 4, the wafer transmission unit includes a θ -axis rotation assembly 20 and a Y-axis transmission assembly 21, where the θ -axis rotation assembly 20 drives the wafer 83 to uniaxially rotate on the θ axis, and the Y-axis transmission assembly 21 drives the wafer 83 to translate in the Y direction.
The arrangement of the optical transmission unit and the wafer transmission unit can ensure that the X axis of the scanning axis is arranged on the side of the objective lens 8, the translation of the objective lens 8 is utilized to finish the measurement movement of the wafer 83 in the X axis direction, and the transmission part is matched with the uniaxial rotation of the theta axis, so that the measurement and observation of the surface position of the whole wafer 83 can be realized. When the surface position of the wafer 83 is measured by the two-axis measurement mode of the X axis and the theta axis, the X axis only needs to move the radius length of the measured wafer 83, and then the position measurement of the whole wafer 83 surface can be realized by the rotation of the theta axis. The mode greatly shortens the movement distance, so that the measuring light path is more compact, and the space is saved. When X and theta axes are used for transmission, a Y axis can be coupled to the theta axis, and the stroke length of the Y axis transmission assembly 21 can be determined according to the transmission distance of the actual wafer 83 and the equipment space. The X, theta and Y three axes can realize high-precision centering of the center centering of the wafer 83. The requirements of high-precision repeated measurement and high-precision positioning of the pattern piece are met. The distance and precision of the motion of the Y-axis can be adjusted according to the requirement, namely, the Y-axis can be canceled when high-precision alignment and transmission in the Y direction of the wafer 83 are not required, when high-precision center alignment is required to be realized, the Y-axis with shorter stroke and higher precision can be used for compensating the Y direction of the rotation center, and when the distance between the position of the upper wafer opening 22 and the measuring position is longer, the long-stroke Y-axis can be used for transmitting the wafer 83.
As shown in FIG. 1, the measuring device further comprises a wafer 83 upper opening 22, and a macroscopic defect scanning component can be installed at the wafer 83 upper opening 22 and mainly comprises a camera, a light source and a lens. When the robot arm mounts the wafer or in the process of transporting the wafer 83, the camera and the lens are used for detecting macroscopic defects on the surface of the wafer 83, so that defects such as dust, scratches, particles and the like on the surface of the wafer 83 can be detected instead of human eyes, and when the wafer 83 finishes the mounting movement to a measurement area, the defects on the surface of the wafer 83 are presented in an image form.
The data analysis module is configured to obtain optical information obtained from the receiving end, so as to obtain film information on the surface of the wafer 83 after calculation processing, where the optical information includes image signal information and/or reflection spectrum information, and an interferometry film measurement technique is used to process and calculate related data. The data analysis module can realize the function of synchronous acquisition of multiple systems. The imaging light path and the measuring light path of the system can be synchronously acquired in real time, and the two systems can simultaneously take the focal positions of the two systems. For the focus position judgment, the wafer 83 measurement can save time and improve the wafer measurement efficiency. The common-path reference light is used for data analysis, and is different from the measurement mode of the reference sheet 19, so that the time is saved, the efficiency is improved, errors caused by different reference sheets 19 are avoided in common-path measurement, and the measurement accuracy is improved. The common light path measuring mode may be to cut light splitting sheet into parallel light paths to collect and couple some measured light into the receiving device, or to use double channel spectrometer to divide the signal in proportion directly in the receiving end spectrometer without splitting. In the common-path measurement mode, the reference sheet 19 may be fixed in the optical path, and a beam splitter is used to cut the reference sheet 19 into the optical path, and the calibration processing is performed first, and after the measured object or signal is added, the reference signal is subtracted first and then the comparison processing is performed.
In a further embodiment of the invention, a polarizing device can be added at the parallel light between the objective lens 8 and the tube lens 5, the polarizing device can move along the X direction of the objective lens 8 or can be fixed at the parallel light, and the polarizing device can be a birefringent device with fixed polarization state and angle or can be an elasto-optical modulator (PEM) with the polarization state changed by modulating voltage.
In the embodiment of the present invention, taking the optical measurement module in fig. 2 as an example, the specific working mode of the optical measurement module is referred to as follows:
the light beam emitted by the first light source 11 passes through the first small hole 2 and then is combined with the light beam emitted by the second light source 13 through the first light splitting device 3 to form a first light path, then passes through the second light splitting device 4 and the tube lens 5 and then is reflected to the objective lens 8 by the first reflecting mirror 6 and the second reflecting mirror 7, the objective lens 8 focuses the light beam on the surface of the wafer 83, the light beam is reflected back to the objective lens 8 by the wafer 83 to form a second light path, passes through the second reflecting mirror 7, the first reflecting mirror 6 and the tube lens 5 and then is reflected to the third light splitting device 9 by the second light splitting device 4, one light beam is detected by the image sensing unit 14 and used for image observation and light spot alignment, the other light beam passes through the second small hole 10 and then is focused on the fiber core of the spectrum optical fiber 11, the spectrum optical fiber 11 conducts light to the spectrum detection unit to obtain reflection spectrum information of a film, and the information of the wafer surface film is obtained after calculation treatment;
The tube lens 5 can be connected with a first linear displacement device 15, the driving direction is shown as 1-1 in fig. 2, the movement range and the precision of the displacement device are obtained by converting the multiplying power relation between the tube lens 5 and the objective lens 8, for example, the movement range is shown as delta Z, beta and beta, if delta Z takes +/-100 um, beta=10×, the movement range of the linear displacement platform is +/-10 mm, the movement precision of the first linear displacement platform 15 is a, beta and beta=10×, and if a takes the value of 1um, the movement precision is 0.1mm;
the objective lens 8 and the second reflecting mirror 7 form a whole and can be connected with a one-dimensional displacement device 18, the driving direction is shown as 1-4 in fig. 2, the distance between the objective lens 8 and the wafer 83 is independently controlled, and the Z direction is adjusted to focus. According to the multiplying power of the objective lens 8 and the warping degree of the surface of the wafer 83 to be measured, the one-dimensional displacement device 18 can select piezoelectric displacement tables with different precision and different strokes, and the piezoelectric displacement tables have small volume and high precision if necessary;
The first linear displacement device 15 and the one-dimensional displacement device 18 can realize the function of measuring and focusing, and can be selected and used according to actual requirements. Meanwhile, a selection displacement table or a one-dimensional displacement table can be arranged at the position of the objective lens 8, so that the objective lenses 8 with different multiplying powers can be switched;
The objective lens 8 and the second reflecting mirror 7 form a combined transmission whole 80, and the combined transmission whole 80 is arranged on the second linear displacement table 16, the driving direction is shown as 1-3 in fig. 2, the movement of the objective lens in the X direction is realized when the wafer 83 is measured by moving in the direction, and the measurement and observation of the position of the whole surface of the wafer 83 are realized by matching with Y and theta axes of a transmission part of the wafer 83. However, the present invention is not limited thereto, and the transmission unit may be used to transmit the combined transmission unit 80 in the X direction and the Y direction so as to measure and observe the position of the surface of the whole wafer 83;
The first reflecting mirror 6 can be provided with a one-dimensional linear displacement table 17, the driving direction of which is shown as 1-2 in fig. 2, and in the reference sheet 19 of the embodiment of the invention, the first reflecting mirror 6 can be a total reflecting mirror or a light splitting reflecting mirror. When the first mirror 6 is a total reflection mirror, the one-dimensional linear displacement stage 17 is used to cut the first mirror 6 into the optical path for measurement of the wafer 83, and the one-dimensional linear displacement stage 17 is used to move the first mirror 6 out of the optical path to obtain the reference beam of the reference sheet 19. When the first reflecting mirror 6 is a light splitting reflecting mirror, the one-dimensional linear displacement stage 17 is not required, and the reference beam and the measuring beam are coupled in the optical path at the same time, and the signal beam of the wafer 83 is obtained and calculated according to the calibration of the reference beam preferentially.
In the embodiment of the invention, the first light source 1 can be directly coupled to the first small hole 2 by optical fiber introduction, the first light source 1 can couple light sources with different spectrums to the first small hole 2 by optical fiber or spectroscope mode, and couple a wide spectrum into a measuring light path, and meanwhile, the receiving end spectrum detection unit 12 can also introduce received signal light into the non-passing spectrum detection unit 12 by a plurality of spectrum optical fibers 11. Since the second light source 13 and the image sensing unit 14 are also fixed in the optical path, a synchronous focusing function of the image and the measuring beam can be achieved.
The wafer 83 is driven in a manner of referring to fig. 4, a combination of a θ axis and a Y axis is shown in fig. 4, the Y axis driving assembly 21 is at the bottom, the θ axis rotating assembly 20 is mounted on the Y axis driving assembly 21, and the stroke length of the Y axis driving assembly 21 can be determined according to the actual driving distance of the wafer 83 and the equipment space. The theta axis rotation assembly 20 may be connected to 8 inch, 12 inch or compatible wafer 83 tray chuck.
The above embodiments are provided to illustrate the technical concept and features of the present invention and are intended to enable those skilled in the art to understand the content of the present invention and implement the same, and are not intended to limit the scope of the present invention. All equivalent changes or modifications made in accordance with the spirit of the present invention should be construed to be included in the scope of the present invention.