For reference grating debugging device and the method for lithographic equipmentTechnical field
The present invention relates to a kind of IC manufacturing equipment manufacturing field, particularly relate to a kind of in the reference grating debugging device of semiconductor lithography equipment and method.
Background technology
Lithographic equipment is one of visual plant of large scale integrated circuit production.The figure be positioned on mask plate can be transferred on substrate by its projection objective by lithographic equipment by a certain percentage, and wherein all exposure object made a general reference by substrate, comprises substrate, plated film and photoresist etc.All specific device will be finally formed by the multi-layer graphical that exposes to the sun of the device region on substrate due to general, thus just need to ensure accurately to aim between different layers figure, alignment namely between our the normal different graphic said, alignment precision is one of three large important indicators of lithographic equipment, and the alignment function of lithographic equipment is completed under other subsystems (as work stage, complete machine control and focusing and leveling subsystem) coordinate by aligning subsystem.In existing alignment system, the alignment error with reference to grating strengthens causing total alignment error.
As shown in Figure 1, Fig. 1 is published with reference to grating debugging device in prior art.The light beam b sent by LASER Light Source 1, through vibrating mirror 2, then reflects through speculum 3 again, is irradiated on silicon chip 5 through set of lenses 4.The diffraction light b+1 produced by silicon chip 5, b-1, after set of lenses 4 converges, through the through hole on diaphragm 6, become a picture point p again after set of lenses 7 converges on focal plane 9.
The vibrated mirror control device 13 of vibrating mirror 2 controls to swing.When vibrating mirror 2 is in zero-bit, same vertical exit after the incident vibrating mirror of beam orthogonal and not deflecting.When vibrating mirror 2 starts to swing, vibrating mirror departs from zero-bit angle, incident beam also departs from original light path certain distance.Therefore, along with the left-right rotation of vibrating mirror, incident beam b also can swing.Light beam b as shown in Figure 11, b2it is the two-beam that the vibrated index glass impact of transmitted light beam departs from origin-location.By b1the diffraction light b produced1 ,+1, b1 ,-1imaging p on focal plane 91' overlap with p, by b2the diffraction light b produced2 ,+1, b2 ,-1imaging p on focal plane 92' overlap with p.Therefore, if be placed on focal plane 9 with reference to grating 8, then can not change along with swinging of vibrating mirror through the light intensity with reference to grating, thus through light intensity signal be a direct current signal.If be not on focal plane 9 with reference to grating 8, but depart from 9 ' of a Δ Z position, focal plane, then can change along with swinging of vibrating mirror through the light intensity signal with reference to grating, thus there is an AC signal value.Ideally, through the light intensity signal with reference to grating along with as follows with reference to the variation relation of stop position:
Wherein z0represent focal position, z represents that ω represents vibrating mirror angle of oscillation frequency, ω, x with reference to stop position0, αr, αmconstant respectively.When being positioned at focal position with reference to grating, i.e. z=z0time, shellfish match youngster functiontherefore AC signal composition F (t)=0.And when with reference to one, grating off-focal position a small amount of Δ z, F (t) ≠ 0.Therefore such principle is utilized can to adjust to focal position place with reference to grating.
In reality, swing in process due to vibrating mirror, different incident angle reflectivity is different, the transmittancy of the inner diverse location of vibrating mirror is different in addition, and the reason such as the fault of construction of vibrating mirror inside, cause vibrating mirror to change along with the change of pendulum angle for the transmissivity of incident beam b, thus cause having one to depart from finally through with reference to the light intensity signal of grating and ideal situation.In reality through the light intensity signal with reference to grating along with as follows with reference to the variation relation of stop position:
Section 2 in above-mentioned relation formula is distracter.Due to the existence of this distracter, the focal plane position found in actual focussing process and real focal plane position have one and offset.Therefore in the prior art, the debugging device of this reference grating can produce an actual error, and because the existence of this error causes total alignment error to strengthen.
Summary of the invention
For overcoming the defect existed in prior art, the present invention discloses a kind of reference grating debugging device for lithographic equipment and method, and the light intensity making the light beam through vibrating mirror keep constant, reduces the impact of grating being debug to precision.
For achieving the above object, a kind of reference grating debugging device for lithographic equipment, comprise successively according to the direction of beam propagation: LASER Light Source, vibrating mirror, speculum, the first set of lenses, diaphragm and the second set of lenses, for being adjusted to the focal plane place of described second lens with reference to grating, it is characterized in that: also comprise a light intensity adjustment unit, in order to adjust the light intensity of described LASER Light Source output beam.
Further, this light intensity adjustment unit comprises light intensity sensor, signal picker, vibrating mirror controller and LASER Light Source controller.
Further, this light intensity sensor is for detecting the light intensity signal of the light beam through described vibrating mirror.
Further, this signal picker is used for light intensity signal to be converted into data signal.
Further, this LASER Light Source controller is according to the light intensity of described Digital Signals LASER Light Source.
Further, this vibrating mirror controller is for controlling the vibration angle of described vibrating mirror.
The present invention provides a kind of reference grating Method of Adjustment for lithographic equipment simultaneously, the method comprise the light intensity adjustment stage with reference to grating debug the stage, light intensity adjustment phase detection is through the light intensity signal of vibrating mirror, and laser control device controls laser instrument adjustment output intensity according to described light intensity signal; Described with reference to grating debug the stage, laser control device according to the angle value of vibrating mirror control device, control laser instrument export suitable light intensity.
Further, this is stated the light intensity adjustment stage and specifically comprises:
S101: vibrating mirror departs from the angle of zero-bitrecord this angle
S102: laser control device exports control signal Cmlaser instrument output intensity;
S103: light intensity signal is converted into data signal;
S104: laser control device adjustment control signal Cm;
S105: (the N that whether judges light intensity signal0+ Δ N, N0-Δ N) in scope, if " NO " returns re-execute S102, if " YES ", then enter S106;
S106: record vibrating mirror departs from the angle of zero-bitwith corresponding control signal Cm;
S107: judge now whether M equals N, and N is natural number; If " NO " returns S101, if " YES ", then flow process terminates.
The stage of debuging of this reference grating specifically comprises:
S201: vibrating mirror departs from the angle of zero-bitrecord this angle
S202: according to the angle in S201, searches corresponding control signal Cm;
S203: judge now whether M equals N, and N is natural number; If " NO " returns S201, if " YES ", then flow process terminates.
For a light intensity calibration device for lithographic equipment, comprising: LASER Light Source, vibrating mirror, half-reflecting mirror, light intensity detector, signal picker, laser controller, and vibrating mirror controller, wherein,
Described LASER Light Source is used for Emission Lasers light beam,
Described vibrating mirror be used for through described in debug light beam and modulate,
Described half-reflecting mirror for allow segment beam through and caught by described light intensity detector,
Described light intensity signal for detecting the light intensity of the light beam through described vibrating mirror or described half-reflecting mirror, and is fed back to described signal picker by described light intensity detector,
Described signal picker is used for described light intensity signal to be converted to data signal,
Described laser controller is used for by described data signal, controls the light intensity value of described LASER Light Source output beam.
Described vibrating mirror controller for control vibrating mirror to through laser beam modulate.
Compared with prior art, the present invention has the following advantages: instant invention overcomes the focal plane position that finds in actual focussing process and real focal plane position has a technical problem offset, in grating debugging device, increase a light intensity calibration apparatus.This light intensity calibration apparatus, in order to adjust the output light intensity of LASER Light Source, ensures to keep constant through the light intensity of vibrating mirror, reduces because vibrating mirror swings the projection light intensity change that causes and causes reference grating alignment error.
Accompanying drawing explanation
Can be further understood by following detailed Description Of The Invention and institute's accompanying drawings about the advantages and spirit of the present invention.
Fig. 1 is the published structural representation with reference to grating debugging device in prior art;
Fig. 2 is the structural representation of light intensity calibration apparatus disclosed in this invention;
Fig. 3 is the structural representation with reference to grating debugging device disclosed in this invention;
Fig. 4 is the overall flow figure with reference to grating Method of Adjustment disclosed in this invention;
Fig. 5 is the flow chart in the light intensity adjustment stage with reference to grating Method of Adjustment disclosed in this invention;
Fig. 6 is the flow chart in the stage of debuging of the reference grating with reference to grating Method of Adjustment disclosed in this invention.
Detailed description of the invention
Specific embodiments of the invention are described in detail below in conjunction with accompanying drawing.
The present invention is in order to overcome in prior art, and the focal plane position found in actual focussing process and real focal plane position have a technical problem offset, in grating debugging device, increase a light intensity calibration apparatus.This light intensity calibration apparatus, in order to adjust the output light intensity of LASER Light Source, ensures to keep constant through the light intensity of vibrating mirror, reduces because vibrating mirror swings the projection light intensity change that causes and causes reference grating alignment error.
As shown in Figure 2, accompanying drawing 2 is structural representations of light intensity calibration apparatus disclosed in this invention.This light intensity calibration apparatus comprises light intensity sensor 10, for the optical signal through vibrating mirror 2 is converted to the signal of telecommunication, and is sent to signal picker 11.The light intensity analog signal of signal picker 11 to input is converted to data signal, and is sent to laser control device 12.Laser control device 12 accepts the light intensity data signal from signal picker 11, controls laser instrument 1 in real time and adjusts output intensity, makes the light beam through vibrating mirror 2 keep a certain constant light intensity I0.Simultaneously laser control device 12 accepts the vibrating mirror angle signal from vibrating mirror control device 13, for determine vibrating mirror angle and through vibrating mirror light intensity signal between relation.
Therefore, although in reality through the light intensity signal with reference to grating along with as follows with reference to the variation relation of stop position:
Whereinfor distracter, and offset because the existence of this distracter makes the focal plane position that finds in actual focussing process and real focal plane position have one, but by regulating the light intensity that laser instrument 1 exports, compensate for departing between the actual light intensity signal through reference grating and ideal situation, because this eliminating above-mentioned distracter, the light intensity making the light through vibrating mirror keep constant, reduces the impact of grating being debug to precision.
Fig. 3 is the structural representation with reference to grating debugging device disclosed in this invention.In the figure, typical for one disclosed in prior art to combine with light intensity calibration apparatus disclosed in this invention with reference to grating debugging device is used.Same, light intensity calibration apparatus disclosed in this invention can combine with the reference grating debugging device of other types and use.As shown in FIG., speculum 3 is the speculum of a part reflection, and the beam section be irradiated on speculum 3 is irradiated on grating after reflection, is irradiated on light intensity sensor 10 below after fractional transmission.Transmitted light intensity is converted to the signal of telecommunication by light intensity sensor 10, and is sent to signal picker 11.This signal of telecommunication is carried out analog-to-digital conversion by signal picker 11, and the data signal obtained is sent to laser control device 12.Laser control device 12 controls according to the feedback signal obtained the light intensity that laser instrument 1 exports suitable size.
Fig. 4 is the overall flow figure with reference to grating Method of Adjustment disclosed in this invention, as shown in Figure 4, is divided into two stages, first enters the light intensity adjustment stage 401 during these reference grating Method of Adjustment concrete operations, is secondly the stage of debuging 402 with reference to grating.In the light intensity adjustment stage 401, after optical signal through vibrating mirror is converted to data signal, laser control device adjusts output intensity according to this Digital Signals laser instrument 1, the light through vibrating mirror is made to keep a certain constant light intensity, simultaneously laser control device accepts the vibrating mirror angle signal from vibrating mirror control device, for determine vibrating mirror angle and through vibrating mirror light intensity signal between relation.In the stage of debuging 402 of reference grating, laser control device, according to the angle value from vibrating mirror control device, searches the laser control signal value corresponded, and controls laser instrument and exports suitable light intensity.
The specific operation process in detailed light intensity adjustment stage 401 as shown in Figure 5.
501, vibrating mirror departs from zero-bitrecord this angle.This step specifically comprises: vibrating mirror control device 13 controls vibrating mirror and departs from zero-bit certain angle(span of M is from 1 to natural number N), this angle value is sent to laser control device 12, this angle value is stored in internal storage by laser control device 12 simultaneously.
502, laser control device exports Cmlaser instrument output intensity.This step specifically comprises: laser control device 12 exports a control signal Cm(span of M is from 1 to natural number N) exports certain light intensity to control laser instrument.The light beam that laser instrument exports is irradiated on light intensity sensor 10 through vibrating mirror.
503, light intensity signal is converted into data signal.This step specifically comprises: the light intensity signal received is converted to the signal of telecommunication by light intensity sensor 10, and sends this signal of telecommunication to signal picker 11; The analog signal received is converted to data signal by signal picker 11, and this data signal is sent to laser controller 12.
504, laser control device adjustment Cm.This step specifically comprises: laser controller 12, according to the intensity signal received, adjusts control signal Cm(span of M is from 1 to natural number N).
505, (the N that whether judges light intensity signal0+ Δ N, N0-Δ N) in scope.This step specifically comprises: (the N that whether judges light intensity signal0+ Δ N, N0-Δ N) in scope, if " NO " returns re-execute 502, if " YES ", then enter 506, until the light intensity signal that laser controller 12 receives reaches certain predetermined N0certain field in (N0+ Δ N, N0-Δ N).N0for predefined light intensity constant amount, for comparing with the intensity signal received, and according to comparison information adjustment laser control device CM, make the intensity signal received close to N0.Δ N represents the intensity signal of reception and predefined light intensity constant amount N0acceptable degree of closeness, if receive intensity signal, at (N0+ Δ N, N0-Δ N) in scope, think the intensity signal and N that receive0approximately equal, if the intensity signal received, not at (N0+ Δ N, N0-Δ N) in scope, think the intensity signal and N that receive0unequal.
506, recordcm.This step specifically comprises: laser controller 12 is by control signal C now1be stored in internal storage, and with vibrating mirror angle now.
507, judge now whether M equals N.This step specifically comprises: judge now whether M equals N, if " NO ", then vibrating mirror control device 13 controls vibrating mirror and departs from certain angle respectivelyand return 501 respectively, wherein angle valuecover the one-period of vibrating mirror vibration; If " YES ", then flow process terminates.
After completing above step, light intensity adjustment completes.
Fig. 6 is the flow chart in the stage of debuging of the reference grating with reference to grating Method of Adjustment disclosed in this invention.
601, vibrating mirror departs from zero-bit(span of M is from 1 to natural number N), records this angle.This step specifically comprises: vibrating mirror control device 13 controls vibrating mirror offset from zero parallactic angle degreeand angle value is sent to laser control device 12.
602, basissearch Cm, control laser instrument and export suitable light intensity.This step specifically comprises: laser control device 12 is according to the angle value from vibrating mirror control device(span of M is from 1 to natural number N), searches the laser control signal value C correspondedm(span of M is from 1 to natural number N), controls laser instrument and exports suitable light intensity.
603, judge now whether M equals N.This step specifically comprises: judge now whether M equals N, if " NO ", then vibrating mirror control device 13 controls vibrating mirror and departs from certain angle respectivelyand return 601 respectively, wherein angle valuecover the one-period of vibrating mirror vibration; If " YES ", then flow process terminates.
Have employed the reference grating calibration apparatus of above-mentioned light intensity calibration apparatus, owing to keeping constant through the light intensity signal of vibrating mirror, eliminate because vibrating mirror departs from the distracter brought, what thus improve reference grating debugs precision.
Just preferred embodiment of the present invention described in this description, above embodiment is only in order to illustrate technical scheme of the present invention but not limitation of the present invention.All those skilled in the art, all should be within the scope of the present invention under this invention's idea by the available technical scheme of logical analysis, reasoning, or a limited experiment.