CN115939159B - Image sensor and method for manufacturing the same - Google Patents

Abstract

The invention provides an image sensor and a manufacturing method thereof, wherein the method comprises the following steps: providing a substrate, and forming a plurality of isolation structures in the substrate; etching the substrate between adjacent isolation structures to form grooves; and filling semiconductor material in the grooves to form the photodiode region. The manufacturing method of the image sensor provided by the invention does not need to form the photodiode region through ion implantation, thereby avoiding the damage to the substrate caused by ion implantation.

Description

Image sensor and method for manufacturing the same

Technical Field

The present invention relates to the field of semiconductor manufacturing technology, and in particular, to an image sensor and a method for manufacturing the same.

Background

An image sensor refers to a device that converts an optical image into a pixel signal output. Image sensors include Charge Coupled Devices (CCDs) and Complementary Metal Oxide Semiconductor (CMOS) image sensors. Compared with the traditional CCD image sensor, the CMOS image sensor has the characteristics of low power consumption, low cost, compatibility with the CMOS process and the like, and therefore, the CMOS image sensor is widely applied. CMOS image sensors are now used not only in consumer electronics, such as miniature digital-to-analog cameras (DSC), cell phone cameras, video cameras, digital single contrast (DSLR), etc., but also in automotive electronics, monitoring, biotechnology and medicine.

Existing CMOS image sensors are generally classified into front-illuminated (FSI) image sensors and back-illuminated (BSI) image sensors. The back-illuminated image sensor may allow light to enter through the back side and be detected by the photodiode as compared to the conventional front-illuminated image sensor, and may display higher sensitivity than the front-illuminated image sensor because light does not need to pass through the wiring layer.

However, in the advanced BSI CMOS process, a relatively deep ion implantation is required in the front-end process to form a photodiode (Photo diode) region to form a photosensitive region of the CIS, but high-energy ion implantation may cause serious damage to the substrate.

Disclosure of Invention

The invention aims to provide an image sensor and a manufacturing method thereof, which do not need ion implantation, thereby avoiding the damage of a substrate caused by ion implantation.

In order to solve the above technical problems, the present invention provides a method for manufacturing an image sensor, comprising the following steps:

providing a substrate, and forming a plurality of isolation structures in the substrate;

etching the substrate between adjacent isolation structures to form grooves; and

and filling semiconductor material in the grooves to form the photodiode region.

Optionally, the longitudinal section of the groove is square, rectangular, trapezoidal, semicircular or sigma-shaped.

Optionally, the method for forming the groove comprises the following steps: wet etching is carried out on the substrate by adopting a tetramethyl ammonium hydroxide solution; the longitudinal section of the formed groove is in a sigma shape.

Optionally, the method for filling semiconductor material in the groove to form the photodiode region comprises the following steps:

filling a first semiconductor material doped with a first element on the side wall and the bottom of the groove;

and filling a second semiconductor material doped with a second element in the groove, wherein the groove is filled with the second semiconductor material.

Optionally, the first element is phosphorus or arsenic, and the second element is arsenic or phosphorus.

Optionally, after filling the first semiconductor material, before filling the second semiconductor material, the method further comprises: and filling semiconductor materials doped with different elements on the side wall and the bottom of the groove in sequence.

Optionally, the method for filling semiconductor material in the groove to form the photodiode region comprises the following steps:

filling a third semiconductor material with a first doping concentration on the side wall and the bottom of the groove;

and filling a fourth semiconductor material with a second doping concentration in the groove, wherein the fourth semiconductor material fills the groove, the first doping concentration is different from the second doping concentration, and the third semiconductor material and the fourth semiconductor material are doped with the same element.

Optionally, after filling the third semiconductor material, before filling the fourth semiconductor material, the method further comprises: and filling semiconductor materials with different doping concentrations on the side wall and the bottom of the groove in sequence.

Optionally, after forming the isolation structure, before forming the groove, the manufacturing method further includes:

and etching the substrate so that the upper surface of the substrate is lower than the upper surface of the isolation structure.

Optionally, after forming the photodiode region, the manufacturing method further includes:

a top layer of semiconductor material is formed over the photodiode region, and the top layer of semiconductor material is in a raised structure.

Optionally, after forming the photodiode region, the manufacturing method further includes:

forming a protective layer on the substrate, wherein the protective layer covers the isolation structure and the photodiode region;

forming a high-k dielectric layer on the protective layer; and

a metal grid is formed on the high-k dielectric layer over the isolation structure and a color filter is formed on the high-k dielectric layer over the photodiode region.

Correspondingly, the invention also provides an image sensor which is manufactured by adopting the manufacturing method of the image sensor.

In summary, in the image sensor and the method for manufacturing the same, a plurality of isolation structures are formed in a substrate, then the substrate between adjacent isolation structures is etched to form a recess, and then a semiconductor material is filled in the recess to form a photodiode region. The invention does not need to form the photodiode region by ion implantation, thereby avoiding the damage to the substrate caused by ion implantation.

Further, TMAH solution is adopted to carry out wet etching on the substrate to form the groove, and the longitudinal section of the formed groove is in a sigma shape, so that the reflection and refraction of light are increased, and the photoelectric reaction efficiency of the photodiode area formed by the groove is improved.

Further, semiconductor materials doped with different elements are filled in the grooves, or semiconductor materials with different doping concentrations are filled in the grooves, so that photodiode regions with concentration gradients are formed in the grooves, reflection and refraction of light are increased, and photoelectric reaction efficiency of the photodiode regions is improved.

Further, after the photodiode region is formed, a top semiconductor material layer is further formed on the photodiode region, and the top semiconductor material layer is in a convex structure, so that the focusing performance of light is improved, and finally the performance of the image sensor is improved.

Drawings

Those of ordinary skill in the art will appreciate that the figures are provided for a better understanding of the present invention and do not constitute any limitation on the scope of the present invention. Wherein:

fig. 1 is a flowchart of a method for manufacturing an image sensor according to an embodiment of the invention.

Fig. 2 is a schematic structural diagram of an embodiment of the present invention after forming an isolation structure.

Fig. 3 is a schematic diagram of a structure after etching a substrate according to an embodiment of the present invention.

Fig. 4 is a schematic structural diagram of the present invention after forming the grooves.

Fig. 5 is a schematic diagram of a structure after filling semiconductor material according to an embodiment of the present invention.

Fig. 6 is a schematic diagram of a structure after forming a top semiconductor material layer according to an embodiment of the present invention.

Fig. 7 is a schematic diagram of a structure after forming a high-k dielectric layer according to an embodiment of the present invention.

Fig. 8 is a schematic view of a structure after forming microlenses according to an embodiment of the present invention.

In the accompanying drawings:

10-a substrate; 11-isolation structures; 12-grooves; 131-a first semiconductor material; 132-a second semiconductor material; 13-photodiode region; 14-a top layer of semiconductor material; 15-a protective layer; 16-a high-k dielectric layer; 17-a metal grid; 18-color filters; 19-micro-lenses.

Detailed Description

The invention will be described in further detail with reference to the drawings and the specific embodiments thereof in order to make the objects, advantages and features of the invention more apparent. It should be noted that the drawings are in a very simplified form and are not drawn to scale, merely for convenience and clarity in aiding in the description of embodiments of the invention. Furthermore, the structures shown in the drawings are often part of actual structures. In particular, the drawings are shown with different emphasis instead being placed upon illustrating the various embodiments.

As used in this disclosure, the singular forms "a," "an," and "the" include plural referents, the term "or" are generally used in the sense of comprising "and/or" and the term "several" are generally used in the sense of comprising "at least one," the term "at least two" are generally used in the sense of comprising "two or more," and the term "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying any relative importance or number of features indicated. Thus, a feature defining "first," "second," "third," or "third" may explicitly or implicitly include one or at least two such features, the term "proximal" typically being one end proximal to the operator, the term "distal" typically being one end proximal to the patient, "one end" and "other" and "proximal" and "distal" typically referring to corresponding two portions, including not only the endpoints, the terms "mounted," "connected," "coupled," or "coupled" are to be construed broadly, e.g., as either a fixed connection, a removable connection, or as one piece; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communicated with the inside of two elements or the interaction relationship of the two elements.

Furthermore, as used in this disclosure, an element disposed on another element generally only refers to a connection, coupling, cooperation or transmission between two elements, and the connection, coupling, cooperation or transmission between two elements may be direct or indirect through intermediate elements, and should not be construed as indicating or implying any spatial positional relationship between the two elements, i.e., an element may be in any orientation, such as inside, outside, above, below, or on one side, of the other element unless the context clearly indicates otherwise. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.

Fig. 1 is a flowchart of a method for manufacturing an image sensor according to an embodiment of the invention. As shown in fig. 1, the method for manufacturing the image sensor includes the following steps:

s1: providing a substrate, and forming a plurality of isolation structures in the substrate;

s2: etching the substrate between adjacent isolation structures to form grooves;

s3: and filling semiconductor material in the grooves to form the photodiode region.

Fig. 2 to 8 are schematic views illustrating steps of a method for manufacturing an image sensor according to an embodiment of the invention. Next, a method for manufacturing an image sensor according to an embodiment of the present invention will be described in detail with reference to fig. 1 and fig. 2 to 8.

In step S1, referring to fig. 2, asubstrate 10 is provided, and a plurality ofisolation structures 11 are formed in thesubstrate 10.

The material of thesubstrate 10 may be silicon, germanium, silicon carbide, gallium arsenide, indium gallium arsenide, or the like, or may be silicon on insulator, germanium on insulator; or may be other materials such as III-V compounds such as gallium arsenide. In this embodiment, the material of thesubstrate 10 is silicon, and preferably monocrystalline silicon.

A plurality ofisolation structures 11 are formed in thesubstrate 10, where theisolation structures 11 may be deep trench isolation structures, or isolation structures formed by combining deep trench isolation structures with shallow trench isolation structures, and theisolation structures 11 are used to isolate photodiode regions formed later.

Illustratively, a mask layer is first formed on thesubstrate 10, and the mask layer is subjected to patterning treatment to form a patterned mask layer; then, etching thesubstrate 10 by using the patterned mask layer as a mask, and forming a plurality of trenches in thesubstrate 10; then, removing the patterned mask layer; thereafter, an insulating material, such as silicon oxide, is filled in the trench, the insulating material filling the trench and covering thesubstrate 10; thereafter, the insulating layer is planarized to expose thesubstrate 10, thereby forming theisolation structures 11.

In step S2, as described with reference to fig. 4, thesubstrate 10 betweenadjacent isolation structures 11 is etched to formgrooves 12.

In this embodiment, as shown in fig. 3, before forming therecess 12, thesubstrate 10 may be etched so that the upper surface of thesubstrate 10 is lower than the upper surface of theisolation structure 11, so that a top semiconductor material layer is formed at the removed position of thesubstrate 10 in a subsequent step. Illustratively, a dry etch may be used to remove a portion of thesubstrate 10, and a selective etch may be used to remove a portion of the thickness of thesubstrate 10, while leaving theisolation structures 11 such that the upper surfaces of theisolation structures 11 are higher than the upper surface of thesubstrate 10. The etching etches the entire exposed upper surface of thesubstrate 10, so that the entire upper surface of thesubstrate 10 is lowered.

Next, thesubstrate 10 betweenadjacent isolation structures 11 is etched to formgrooves 12 in thesubstrate 10. The longitudinal section of thegroove 12 may be square, rectangular, trapezoidal, semicircular or sigma-shaped, and of course, thegroove 12 may be any polygonal shape, which is not limited in the present invention. In this embodiment, referring to fig. 4, the longitudinal section of thegroove 12 is preferably in a sigma shape, and the photodiode region formed in the sigma-shapedgroove 12 can increase the reflection and refraction of light, thereby improving the photoelectric reaction efficiency of the photodiode region. Thesubstrate 10 is wet etched using a tetramethylammonium hydroxide (TMAH) solution to form the sigma-shapedrecess 12, although other etching solutions or etching methods may be used, which is not limited in the present invention.

In step S3, referring to fig. 5, a semiconductor material is filled in therecess 12 to form aphotodiode region 13.

Therecess 12 is filled with a semiconductor material to form thephotodiode region 13, so that ion implantation is not required, thereby avoiding damage to thesubstrate 10 due to ion implantation.

In an embodiment of the present invention, semiconductor materials doped with different elements may be sequentially filled in therecess 12 to form thephotodiode region 13 having a concentration gradient in therecess 12. Referring to fig. 5, first, the sidewalls and the bottom of therecess 12 are filled with afirst semiconductor material 131 doped with a first element, and thefirst semiconductor material 131 conformally covers therecess 12; next, asecond semiconductor material 132 doped with a second element is filled in therecess 12, thesecond semiconductor material 132 filling therecess 12. Wherein the first element is different from the second element, the first element is phosphorus (P) or arsenic (As), and the second element is arsenic or phosphorus, i.e., when the first element is phosphorus, the second element is arsenic; when the first element is arsenic, the second element is phosphorus, but not limited thereto, and the first element and the second element may be any suitable element known to those skilled in the art.

Preferably, after the sidewalls and bottom of therecess 12 are filled with thefirst semiconductor material 131, and before therecess 12 is filled with thesecond semiconductor material 132, the method further includes: semiconductor materials doped with different elements are sequentially filled in the side walls and the bottom of thegroove 12, for example, semiconductor materials doped with antimony (Sb) are filled in the side walls and the bottom of thegroove 12. Of course, it is also possible to continue filling with semiconductor material doped with different elements. More preferably, doping elements of adjacent semiconductor materials filled in thegrooves 12 are different.

Thegrooves 12 are filled with semiconductor materials having different doping elements, so that thephotodiode regions 13 having a concentration gradient are formed in thegrooves 12, thereby increasing reflection and refraction of light and improving the photoelectric reaction efficiency of thephotodiode regions 13.

In another embodiment of the present invention, semiconductor materials having different doping concentrations and the same doping elements may be sequentially filled in therecess 12 to form thephotodiode region 13 having a concentration gradient in therecess 12. Illustratively, first, the sidewalls and bottom of therecess 12 are filled with a third semiconductor material having a first doping concentration, such as phosphorus, which conformally covers the interior of therecess 12; next, a fourth semiconductor material having a second doping concentration is filled in therecess 12, the fourth semiconductor material filling therecess 12. Wherein the first doping concentration is different from the second doping concentration, and the doping elements of the third semiconductor material and the fourth semiconductor material are the same. Doping elements include, but are not limited to, phosphorus, arsenic, or antimony.

Preferably, after the sidewalls and bottom of therecess 12 are filled with the third semiconductor material, and before therecess 12 is filled with the fourth semiconductor material, the method further includes: semiconductor materials with different doping concentrations are sequentially filled in the side walls and the bottom of thegroove 12. For example, the sidewalls and bottom of therecess 12 are filled with a semiconductor material having a third doping concentration. Alternatively, after filling the semiconductor material having the third doping concentration, the semiconductor material having the fourth doping concentration is continuously filled at the sidewall and the bottom of therecess 12. Of course, it is also possible to continue filling with semiconductor materials having different doping concentrations. More preferably, the doping concentration of the adjacent semiconductor materials filled in therecess 12 is different. It is understood that when only the semiconductor material of the first doping concentration and the second doping concentration is filled, the first doping concentration is different from the second doping concentration; when the semiconductor material with the first doping concentration, the third doping concentration and the second doping concentration is sequentially filled, the first doping concentration, the second doping concentration and the third doping concentration can be different from each other, or the first doping concentration is equal to the second doping concentration but not equal to the third doping concentration; when the semiconductor material having the first doping concentration, the third doping concentration, the fourth doping concentration, and the second doping concentration is sequentially filled, the first doping concentration, the second doping concentration, the third doping concentration, and the fourth doping concentration may be all different, or the first doping concentration may be equal to the third doping concentration, the second doping concentration may be equal to the fourth doping concentration, and the first doping concentration may not be equal to the second doping concentration, but is not limited thereto.

Thegrooves 12 are filled with semiconductor materials having different doping concentrations, so that thephotodiode regions 13 having a concentration gradient are formed in thegrooves 12, thereby increasing reflection and refraction of light and improving the photoelectric reaction efficiency of thephotodiode regions 13.

The number of layers of semiconductor materials doped with different elements is not limited, or the number of layers of semiconductor materials with different doping concentrations is filled in thegroove 12, and the more the number of layers of semiconductor materials is filled, the larger the concentration gradient is, so that the reflection and refraction of light can be increased, the photoelectric reaction efficiency of thephotodiode region 13 is improved, but the number of layers is increased, the manufacturing cost is correspondingly increased, and the number of layers of semiconductor materials can be determined according to actual requirements.

In the embodiment of the invention, the semiconductor materials doped with different elements are filled in thegroove 12, or the semiconductor materials doped with different concentration elements are filled in thegroove 12, so that a concentration gradient is formed in thegroove 12, the reflection and refraction of light are increased, and the photoelectric reaction efficiency of thephotodiode region 13 formed by the method is improved. In other embodiments of the present invention, semiconductor material having a concentration gradient may be formed in therecess 12 by other methods, which is not limited in the present invention. The semiconductor material is preferably silicon. By way of example, the semiconductor material of the different layers may be epitaxially grown.

Next, referring to fig. 6, after forming thephotodiode region 13, the manufacturing method further includes: a top layer ofsemiconductor material 14 is formed on thephotodiode region 13, and the top layer ofsemiconductor material 14 is in a raised structure. The topsemiconductor material layer 14 may be the same as thefirst semiconductor material 131, for example, a silicon layer doped with phosphorus.

The topsemiconductor material layer 14 has a convex structure, which can increase the focusing performance of light and finally improve the performance of the image sensor.

Referring to fig. 7, the manufacturing method further includes: forming aprotective layer 15 on thesubstrate 10, theprotective layer 15 covering theisolation structure 11 and thephotodiode region 13; next, a high-k dielectric layer 16 is formed on theprotective layer 15.

The material of theprotective layer 15 includes silicon oxide, silicon nitride, silicon oxynitride, or the like, and theprotective layer 15 may be formed by Chemical Vapor Deposition (CVD), physical Vapor Deposition (PVD), atomic Layer Deposition (ALD), or the like. Theprotective layer 15 is used to protect thephotodiode region 13 and the like in thesubstrate 10. The material of the high-k dielectric layer 16 comprises hafnium oxide (HfO₂ ) Titanium oxide (TiO) or lanthanum oxide (LaO) may also contain tantalum oxide (Ta₂ O₅ ) Strontium titanium oxide (SrTiO)₃ ) Hafnium silicon oxide (HfSiO) or zirconium oxide (ZrO₂ ) Etc., but is not limited thereto. The high-k dielectric layer 16 may be formed by one or more thin film deposition processes including, but not limited to, chemical vapor deposition, physical vapor deposition, atomic layer deposition, thermal oxidation, electroplating, electroless plating, or any combination thereof.

Next, referring to fig. 8, ametal grid 17 and acolor filter 18 are formed, wherein themetal grid 17 is located on the high-k dielectric layer 16 above theisolation structure 11, and thecolor filter 18 is located on the high-k dielectric layer 16 above thephotodiode region 13.

The material of themetal grid 17 comprises a metal or a metal alloy, wherein the metal may comprise tungsten, aluminum, copper or the like, and the metal alloy may comprise titanium nitride or the like. Thecolor filter 18 may include a resin or other organic material with color pigments. Amicrolens 19 is also formed on thecolor filter 18.

In the method for manufacturing the image sensor, a plurality ofisolation structures 11 are formed in asubstrate 10, then thesubstrate 10 betweenadjacent isolation structures 11 is etched to form agroove 12, and then a semiconductor material is filled in thegroove 12 to form aphotodiode region 13. The present invention does not require the formation of thephotodiode region 13 by ion implantation, thereby avoiding damage to thesubstrate 10 due to ion implantation.

Further, thesubstrate 10 is wet etched with TMAH solution to form thegrooves 12, and the longitudinal sections of thegrooves 12 are formed in a sigma shape, so as to increase reflection and refraction of light and improve the photoelectric reaction efficiency of thephotodiode region 13 formed thereby.

Further, semiconductor materials doped with different elements are filled in thegrooves 12, or semiconductor materials with different doping concentrations are filled in thegrooves 12, so that thephotodiode regions 13 with concentration gradients are formed in thegrooves 12, reflection and refraction of light are increased, and the photoelectric reaction efficiency of thephotodiode regions 13 is improved.

Further, after thephotodiode region 13 is formed, a topsemiconductor material layer 14 is further formed on thephotodiode region 13, and the topsemiconductor material layer 14 has a bump structure, so that the focusing performance of light is increased, and finally, the performance of the image sensor is improved.

Correspondingly, the invention also provides an image sensor which is manufactured by adopting the manufacturing method of the image sensor. Referring to fig. 8, the image sensor includes:

asubstrate 10;

a plurality ofisolation structures 11 located within thesubstrate 10;

arecess 12 in thesubstrate 10 betweenadjacent isolation structures 11;

aphotodiode region 13 is located within therecess 12.

According to the pattern sensor provided by the invention, thegroove 12 is formed in thesubstrate 10, thephotodiode region 13 is formed in thegroove 12 by filling the semiconductor material, and the photodiode region is not required to be formed by ion implantation, so that the damage to thesubstrate 10 caused by ion implantation is avoided.

Preferably, the longitudinal section of thegroove 12 has a sigma shape, that is, the longitudinal section of thephotodiode region 13 has a sigma shape, so that reflection and refraction of light can be increased, thereby improving the photoreaction efficiency of thephotodiode region 13.

Preferably, the sidewalls and the bottom of therecess 12 are filled with afirst semiconductor material 131 doped with a first element, asecond semiconductor material 132 doped with a second element is filled in therecess 12, thesecond semiconductor material 132 fills therecess 12, and thefirst semiconductor material 131 and thesecond semiconductor material 132 together form thephotodiode region 13. Wherein the first element is different from the second element, the first element is phosphorus (P) or arsenic (As), and the second element is arsenic or phosphorus, i.e., when the first element is phosphorus, the second element is arsenic; when the first element is arsenic, the second element is phosphorus, but not limited thereto, and the first element and the second element may be any element known to those skilled in the art.

More preferably, a semiconductor material doped with a different element is further formed between thefirst semiconductor material 131 and thesecond semiconductor material 132. For example: therecess 12 is filled with a first semiconductor material doped with phosphorus (for example, afirst semiconductor material 131 doped with a first element), a semiconductor material doped with antimony, and a second semiconductor material doped with arsenic (for example, asecond semiconductor material 132 doped with a second element) in this order. Of course, semiconductor materials doped with different elements may also be filled between the antimony-doped semiconductor material and the arsenic-doped second semiconductor material. Preferably, adjacent semiconductor material doped elements filled in therecess 12 are different.

Thegrooves 12 are filled with semiconductor materials having different doping elements, so that thephotodiode regions 13 having a concentration gradient are formed in thegrooves 12, thereby increasing reflection and refraction of light and improving the photoreaction efficiency of thephotodiode regions 13.

Preferably, the sidewalls and bottom of therecess 12 are filled with a third semiconductor material having a first doping concentration, a fourth semiconductor material having a second doping is filled in therecess 12, and thefourth semiconductor material 132 fills therecess 12. The third semiconductor material and the fourth semiconductor material together constitute thephotodiode region 13. Wherein the first doping concentration is different from the second doping concentration, the third semiconductor material is the same as the fourth semiconductor material doped element including, but not limited to, phosphorus, arsenic or antimony.

More preferably, semiconductor materials having different doping concentrations are further formed between the third semiconductor material and the fourth semiconductor material. For example: therecess 12 is filled with a third semiconductor material having a first doping concentration, a semiconductor material having a third doping concentration, and a fourth semiconductor material having a second doping concentration in order, where the first doping concentration, the second doping concentration, and the third doping concentration may be different from each other, or the first doping concentration may be equal to the second doping concentration but not equal to the third doping concentration. Of course, a semiconductor material having a fourth doping concentration may be filled between a semiconductor material having a third doping concentration and a fourth semiconductor material having a second doping concentration, and the first doping concentration, the second doping concentration, the third doping concentration, and the fourth doping concentration may all be different, or the first doping concentration may be equal to the third doping concentration, the second doping concentration may be equal to the fourth doping concentration, and the first doping concentration may not be equal to the second doping concentration. Preferably, the doping concentration of adjacent semiconductor materials filled in therecess 12 is different.

Thegrooves 12 are filled with semiconductor materials having different doping concentrations, so that thephotodiode regions 13 having a concentration gradient are formed in thegrooves 12, thereby increasing reflection and refraction of light and improving the photoreaction efficiency of thephotodiode regions 13.

Preferably, a topsemiconductor material layer 14 is further formed on thesubstrate 10 between theadjacent isolation structures 11, and the topsemiconductor material layer 14 is located above thephotodiode region 13 and has a convex structure, so as to increase the focusing of light, and finally improve the performance of the image sensor.

Preferably, the pattern sensor further comprises aprotective layer 15 and the high-k dielectric layer 16. Theprotective layer 15 is located on thesubstrate 10 and covers theisolation structure 11 and thephotodiode region 13. The high-k dielectric layer 16 is located on theguard vehicle 15.

Preferably, the pattern sensor further comprises ametal grid 17 and acolor filter 18, themetal grid 17 being located on the high-k dielectric layer 16 above theisolation structure 11, thecolor filter 18 being located on the high-k dielectric layer 16 above thephotodiode region 13.

Amicrolens 19 is also formed on thecolor filter 18.

The foregoing description is only illustrative of the preferred embodiments of the present invention, and is not intended to limit the scope of the claims, and any person skilled in the art may make any possible variations and modifications to the technical solution of the present invention using the method and technical content disclosed above without departing from the spirit and scope of the invention, so any simple modification, equivalent variation and modification made to the above embodiments according to the technical matter of the present invention fall within the scope of the technical solution of the present invention.

Claims (11)

1. A method for manufacturing an image sensor, comprising the steps of:

providing a substrate, and forming a plurality of isolation structures in the substrate;

etching the substrate so that the upper surface of the substrate is lower than the upper surface of the isolation structure;

etching the substrate between adjacent isolation structures to form grooves; and

and filling semiconductor material in the grooves to form the photodiode region.

2. The method of manufacturing an image sensor according to claim 1, wherein the longitudinal section of the recess is square, rectangular, trapezoidal, semicircular or sigma-shaped.

3. The method of manufacturing an image sensor according to claim 2, wherein the method of forming the recess comprises: wet etching is carried out on the substrate by adopting a tetramethyl ammonium hydroxide solution; the longitudinal section of the formed groove is in a sigma shape.

4. The method of fabricating an image sensor of claim 1, wherein the step of filling semiconductor material into the recess to form the photodiode region comprises:

filling a first semiconductor material doped with a first element on the side wall and the bottom of the groove;

and filling a second semiconductor material doped with a second element in the groove, wherein the groove is filled with the second semiconductor material.

5. The method of claim 4, wherein the first element is phosphorus or arsenic and the second element is arsenic or phosphorus.

6. The method of manufacturing an image sensor according to claim 4, further comprising, after filling the first semiconductor material, before filling the second semiconductor material: and filling semiconductor materials doped with different elements on the side wall and the bottom of the groove in sequence.

7. The method of fabricating an image sensor of claim 1, wherein the step of filling semiconductor material into the recess to form the photodiode region comprises:

filling a third semiconductor material with a first doping concentration on the side wall and the bottom of the groove;

and filling a fourth semiconductor material with a second doping concentration in the groove, wherein the fourth semiconductor material fills the groove, the first doping concentration is different from the second doping concentration, and the third semiconductor material and the fourth semiconductor material are doped with the same element.

8. The method of manufacturing an image sensor according to claim 7, further comprising, after filling the third semiconductor material, before filling the fourth semiconductor material: and filling semiconductor materials with different doping concentrations on the side wall and the bottom of the groove in sequence.

9. The method of manufacturing an image sensor according to claim 1, wherein after forming the photodiode region, the method further comprises:

a top layer of semiconductor material is formed over the photodiode region, and the top layer of semiconductor material is in a raised structure.

10. The method of manufacturing an image sensor according to claim 1, wherein after forming the photodiode region, the method further comprises:

forming a protective layer on the substrate, wherein the protective layer covers the isolation structure and the photodiode region;

forming a high-k dielectric layer on the protective layer; and

a metal grid is formed on the high-k dielectric layer over the isolation structure and a color filter is formed on the high-k dielectric layer over the photodiode region.

11. An image sensor manufactured by the method for manufacturing an image sensor according to any one of claims 1 to 10.

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