CN117096164A - Image sensor and method for manufacturing the same - Google Patents
Image sensor and method for manufacturing the same Download PDFInfo
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- CN117096164A CN117096164A CN202210524730.6A CN202210524730A CN117096164A CN 117096164 A CN117096164 A CN 117096164A CN 202210524730 A CN202210524730 A CN 202210524730A CN 117096164 A CN117096164 A CN 117096164A
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- 238000000034 method Methods 0.000 title claims description 51
- 238000004519 manufacturing process Methods 0.000 title claims description 18
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims abstract description 83
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims abstract description 80
- 229910052814 silicon oxide Inorganic materials 0.000 claims abstract description 80
- 239000000758 substrate Substances 0.000 claims abstract description 40
- 239000004065 semiconductor Substances 0.000 claims abstract description 38
- 238000005530 etching Methods 0.000 claims description 22
- 230000008569 process Effects 0.000 claims description 19
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 11
- 229910052710 silicon Inorganic materials 0.000 claims description 11
- 239000010703 silicon Substances 0.000 claims description 11
- 238000005240 physical vapour deposition Methods 0.000 claims description 7
- 229910044991 metal oxide Inorganic materials 0.000 claims description 6
- 150000004706 metal oxides Chemical class 0.000 claims description 6
- 229910052581 Si3N4 Inorganic materials 0.000 claims description 4
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 claims description 4
- 238000001312 dry etching Methods 0.000 claims description 3
- 238000007733 ion plating Methods 0.000 claims description 3
- 238000004544 sputter deposition Methods 0.000 claims description 3
- 238000001914 filtration Methods 0.000 claims 1
- 238000002310 reflectometry Methods 0.000 abstract description 10
- 238000002360 preparation method Methods 0.000 abstract description 9
- 238000002955 isolation Methods 0.000 abstract description 8
- 229910052751 metal Inorganic materials 0.000 description 12
- 239000002184 metal Substances 0.000 description 12
- 238000010586 diagram Methods 0.000 description 6
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 4
- 229910052721 tungsten Inorganic materials 0.000 description 4
- 239000010937 tungsten Substances 0.000 description 4
- 229910052782 aluminium Inorganic materials 0.000 description 3
- 238000005229 chemical vapour deposition Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 230000003287 optical effect Effects 0.000 description 3
- 238000000059 patterning Methods 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- 238000000231 atomic layer deposition Methods 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 238000001912 gas jet deposition Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 150000004767 nitrides Chemical class 0.000 description 2
- 238000001579 optical reflectometry Methods 0.000 description 2
- 230000009471 action Effects 0.000 description 1
- AZDRQVAHHNSJOQ-UHFFFAOYSA-N alumane Chemical group [AlH3] AZDRQVAHHNSJOQ-UHFFFAOYSA-N 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 238000003491 array Methods 0.000 description 1
- 239000000969 carrier Substances 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000003086 colorant Substances 0.000 description 1
- 230000005684 electric field Effects 0.000 description 1
- 229910052732 germanium Inorganic materials 0.000 description 1
- GNPVGFCGXDBREM-UHFFFAOYSA-N germanium atom Chemical compound [Ge] GNPVGFCGXDBREM-UHFFFAOYSA-N 0.000 description 1
- 238000005286 illumination Methods 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 description 1
- 229910010271 silicon carbide Inorganic materials 0.000 description 1
- 238000001039 wet etching Methods 0.000 description 1
Classifications
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
- H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
- H01L27/144—Devices controlled by radiation
- H01L27/146—Imager structures
- H01L27/14683—Processes or apparatus peculiar to the manufacture or treatment of these devices or parts thereof
- H01L27/14685—Process for coatings or optical elements
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
- H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
- H01L27/144—Devices controlled by radiation
- H01L27/146—Imager structures
- H01L27/14601—Structural or functional details thereof
- H01L27/1462—Coatings
- H01L27/14623—Optical shielding
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
- H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
- H01L27/144—Devices controlled by radiation
- H01L27/146—Imager structures
- H01L27/14601—Structural or functional details thereof
- H01L27/14625—Optical elements or arrangements associated with the device
- H01L27/14629—Reflectors
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- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Electromagnetism (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- General Physics & Mathematics (AREA)
- Computer Hardware Design (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Solid State Image Pick-Up Elements (AREA)
Abstract
The invention provides an image sensor and a preparation method thereof.A silicon oxide layer is formed on a semiconductor substrate with a pixel unit array, a groove which is arranged corresponding to the pixel unit array is formed in the silicon oxide layer so as to limit an opening of each pixel unit in the pixel unit array for receiving light, then an aluminum metal layer is formed on the surface of the silicon oxide layer, a SiAlxOy layer is formed between the formed aluminum metal layer and the silicon oxide layer, then the aluminum metal layer and the SiAlxOy layer which are positioned at the bottom of the groove are removed, and the aluminum metal layer positioned at the side wall of the groove is removed so as to expose the SiAlxOy layer positioned at the side wall of the groove, so that a grid structure is formed; the SiAlxOy layer can provide a grid structure with high light isolation performance, can effectively overcome the problem of poor integrity of an aluminum metal layer, and provides a high-reflectivity layer with good performance, so that crosstalk of adjacent pixel units can be effectively prevented, and the light receiving efficiency of an image sensor is improved.
Description
Technical Field
The invention relates to the technical field of sensors, in particular to an image sensor and a preparation method thereof.
Background
The image sensor is a functional device that converts an optical image on a photosensitive surface into an electrical signal in a corresponding proportional relationship with the optical image by using a photoelectric conversion function of the photoelectric device. Among them, there are two general types of image sensors, a charge coupled type image sensor (CCD) and a CMOS type image sensor (CIS). The CCD collects charges through photoelectric effect, and the charges of each row of pixels are sent to an analog shift register along with a clock signal and then converted into voltages in series. The CIS is a rapidly developing solid-state image sensor, and since the image sensor part and the control circuit part in the CMOS image sensor are integrated in the same chip, the CMOS image sensor has small volume, low power consumption and low price, and is more advantageous and popular than the conventional CCD image sensor.
The CMOS image sensor includes thereon a plurality of pixel arrays composed of pixel units, each of which senses the intensity of light in a certain area of an image, and the intensities of the light sensed by each of the pixel units are combined to obtain the image.
With the continued reduction of process nodes, it is important to avoid crosstalk caused by the escape of incident light between adjacent pixel units as much as possible, and to increase the number of photo-generated carriers generated by each pixel unit as much as possible.
Therefore, it is necessary to provide an image sensor and a method for manufacturing the same.
Disclosure of Invention
In view of the above-mentioned drawbacks of the prior art, an object of the present invention is to provide an image sensor and a method for manufacturing the same, which are used for solving the problems of crosstalk and low light receiving efficiency of adjacent pixel units in the prior art.
To achieve the above and other related objects, the present invention provides a method for manufacturing an image sensor, comprising the steps of:
providing a semiconductor substrate, wherein a pixel unit array is formed in the semiconductor substrate;
forming a silicon oxide layer on the semiconductor substrate;
etching the silicon oxide layer, and forming a groove in the silicon oxide layer, wherein the groove is arranged corresponding to the pixel unit array so as to limit an opening of each pixel unit in the pixel unit array for receiving light;
forming an aluminum metal layer on the surface of the silicon oxide layer, and forming a SiAlxOy layer between the formed aluminum metal layer and the silicon oxide layer;
etching is carried out, the aluminum metal layer and the SiAlxOy layer which are positioned at the bottom of the groove are removed, the aluminum metal layer positioned on the side wall of the groove is removed, the SiAlxOy layer positioned on the side wall of the groove is exposed, and a grid structure is formed.
Optionally, the method for forming the aluminum metal layer on the surface of the silicon oxide layer comprises a physical vapor deposition method; the etching step adopts a dry etching method.
Optionally, the physical vapor deposition method includes a sputtering method or an ion plating method, wherein a process temperature is 400 ℃ or less in the process of forming the aluminum metal layer on the surface of the silicon oxide layer.
Optionally, after the step of etching the aluminum metal layer, the silicon oxide layer has the aluminum metal layer on top.
Optionally, the thickness of the aluminum metal layer located at the top of the silicon oxide layer is larger than that of the aluminum metal layer located at the bottom of the groove and larger than that of the aluminum metal layer located at the side wall of the groove.
Optionally, a step of forming an intermediate layer between the semiconductor substrate and the silicon oxide layer is further included, the intermediate layer comprising one or a combination of a high-k dielectric layer, an oxide of silicon, a nitride of silicon, an oxynitride of silicon, and a transparent metal oxide.
Optionally, after the step of forming the grid structure, a step of forming a filter layer and a microlens in the groove is further included.
The present invention also provides an image sensor including:
a semiconductor substrate having a pixel cell array formed therein;
a grid structure, the grid structure comprising:
the silicon oxide layer is positioned on the semiconductor substrate, and is provided with a groove, and the groove is arranged corresponding to the pixel unit array so as to limit an opening for receiving light of each pixel unit in the pixel unit array;
and the SiAlxOy layer coats the silicon oxide layer and exposes the bottom of the groove.
Optionally, the surface of the SiAlxOy layer on top of the silicon oxide layer has an aluminum metal layer.
Optionally, an intermediate layer is further included between the semiconductor substrate and the silicon oxide layer, the intermediate layer including one or a combination of a high-k dielectric layer, an oxide of silicon, a nitride of silicon, an oxynitride of silicon, and a transparent metal oxide.
Optionally, the grooves are also provided with a filter layer and a micro lens.
As described above, the image sensor and the method for manufacturing the same according to the present invention form a silicon oxide layer on a semiconductor substrate having a pixel cell array, form a recess in the silicon oxide layer, the recess being disposed corresponding to the pixel cell array, to define an opening for receiving light of each pixel cell in the pixel cell array, then form an aluminum metal layer on a surface of the silicon oxide layer, and a SiAlxOy layer is formed between the formed aluminum metal layer and the silicon oxide layer, then remove the aluminum metal layer and the SiAlxOy layer at a bottom of the recess by an etching process, and remove the aluminum metal layer at a sidewall of the recess to expose the SiAlxOy layer at a sidewall of the recess, thereby forming a grid structure.
The image sensor provided by the invention can provide a grid structure with high light isolation performance through the SiAlxOy layer, can effectively overcome the problem of poor integrity of an aluminum metal layer, and provides a high-reflectivity layer with good performance, so that crosstalk of adjacent pixel units in the image sensor can be effectively prevented, and the light receiving efficiency of the image sensor is improved.
Drawings
Fig. 1 is a process flow diagram of preparing an image sensor in accordance with an embodiment of the present invention.
Fig. 2 is a schematic structural diagram of a semiconductor substrate according to an embodiment of the invention.
Fig. 3 is a schematic structural diagram of a silicon oxide layer formed according to an embodiment of the invention.
Fig. 4 is a schematic structural diagram of a silicon oxide layer after forming a recess in the silicon oxide layer according to an embodiment of the invention.
Fig. 5 is a schematic structural diagram of a silicon oxide layer with a SiAlxOy layer and an aluminum metal layer formed on the surface thereof according to an embodiment of the present invention.
Fig. 6 is a schematic structural diagram of an embodiment of the present invention after etching to remove the aluminum metal layer, the SiAlxOy layer, and the aluminum metal layer on the sidewall of the groove.
Description of element reference numerals
100. Semiconductor substrate
101. Semiconductor substrate
102. Metal wiring layer
103. Isolation structure
104. Pixel unit
200. Intermediate layer
300. Silicon oxide layer
301. Groove
400. Aluminum metal layer
500 SiAlxOy layer
Detailed Description
In the conventional backside illuminated (BSI, back-side Illumination) CMOS image sensor, as the process node is continuously reduced, tungsten metal is often used as a material of the metal mesh in the preparation of the metal mesh due to the compatibility of the process node and the fine pitch patterning process, however, the aluminum metal has better light reflectivity than the tungsten metal in terms of light reflectivity, but when the metal mesh is applied to a fine pitch product, the coverage integrity of the aluminum metal is poor compared with that of the tungsten metal, so that the tungsten metal mesh is difficult to satisfy the problem of good coverage integrity and reflectivity for the fine pitch BSI image sensor at present.
The embodiment combines the problems, provides an image sensor and a preparation method thereof, so as to effectively overcome the problem of poor integrity of an aluminum metal layer, and provides a high-reflectivity layer with good performance, so as to effectively prevent crosstalk of adjacent pixel units in the image sensor and improve the light receiving efficiency of the image sensor.
Other advantages and effects of the present invention will become apparent to those skilled in the art from the following disclosure, which describes the embodiments of the present invention with reference to specific examples. The invention may be practiced or carried out in other embodiments that depart from the specific details, and the details of the present description may be modified or varied from the spirit and scope of the present invention.
As described in detail in the embodiments of the present invention, the cross-sectional view of the device structure is not partially enlarged to a general scale for convenience of explanation, and the schematic drawings are only examples, which should not limit the scope of the present invention. In addition, the three-dimensional dimensions of length, width and depth should be included in actual fabrication.
For ease of description, spatially relative terms such as "under", "below", "beneath", "above", "upper" and the like may be used herein to describe one element or feature's relationship to another element or feature as illustrated in the figures. It will be understood that these spatially relative terms are intended to encompass other orientations of the device in use or operation in addition to the orientation depicted in the figures. Furthermore, when a layer is referred to as being "between" two layers, it can be the only layer between the two layers or one or more intervening layers may also be present. In this regard, when an element is referred to as being "mounted" or "disposed" on another element, it can be directly on the other element or be indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or be indirectly connected to the other element.
Such as "between … …" may be used herein, the expression including both end values, and such as "a plurality" may be used, the expression indicating two or more, unless specifically defined otherwise. 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 one or more such feature.
It should be noted that, the illustrations provided in the present embodiment merely illustrate the basic concept of the present invention by way of illustration, and only the components related to the present invention are shown in the drawings and are not drawn according to the number, shape and size of the components in actual implementation, and the form, number and proportion of each component in actual implementation may be changed at will, and the layout of the components may be more complex.
As shown in fig. 1, the present embodiment provides a method for manufacturing an image sensor, including the following steps:
s1: providing a semiconductor substrate, wherein a pixel unit array is formed in the semiconductor substrate;
s2: forming a silicon oxide layer on the semiconductor substrate;
s3: etching the silicon oxide layer, and forming a groove in the silicon oxide layer, wherein the groove is arranged corresponding to the pixel unit array so as to limit an opening of each pixel unit in the pixel unit array for receiving light;
s4: forming an aluminum metal layer on the surface of the silicon oxide layer, and forming a SiAlxOy layer between the formed aluminum metal layer and the silicon oxide layer;
s5: etching is carried out, the aluminum metal layer and the SiAlxOy layer which are positioned at the bottom of the groove are removed, the aluminum metal layer positioned on the side wall of the groove is removed, the SiAlxOy layer positioned on the side wall of the groove is exposed, and a grid structure is formed.
In the method for manufacturing the image sensor of this embodiment, the silicon oxide layer is formed on the semiconductor substrate having the pixel cell array, the grooves corresponding to the pixel cell array are formed in the silicon oxide layer to define openings for receiving light of the pixel cells in the pixel cell array, the aluminum metal layer is formed on the surface of the silicon oxide layer, the SiAlxOy layer is formed between the formed aluminum metal layer and the silicon oxide layer, then an etching process is performed to remove the aluminum metal layer and the SiAlxOy layer at the bottom of the grooves, and the aluminum metal layer at the side walls of the grooves is removed to expose the SiAlxOy layer at the side walls of the grooves, so that the grid structure is formed.
The image sensor prepared by the embodiment can provide the grid structure with high light isolation performance through the SiAlxOy layer, can effectively overcome the problem of poor integrity of the aluminum metal layer, and provides a high-reflectivity layer with good performance, so that crosstalk of adjacent pixel units in the image sensor can be effectively prevented, and the light receiving efficiency of the image sensor is improved.
The preparation of the image sensor according to this embodiment is further described below with reference to fig. 2 to fig. 6 of the specification, and specifically includes:
first, referring to fig. 2, step S1 is performed to provide a semiconductor substrate 100, wherein a pixel cell array is formed in the semiconductor substrate 100.
Specifically, the semiconductor substrate 101, the metal wiring layer 102 formed in the semiconductor substrate 101, the isolation structure 103, and the pixel unit 104 are included in the semiconductor base 100, where the semiconductor substrate 101 may include a silicon substrate, a germanium substrate, a silicon carbide substrate, and the like, and the specific type may be selected according to the need. In this embodiment, the incident light is incident from top to bottom, and the metal wiring layer 102 is located below the pixel unit 104, that is, the image sensor adopts a back-illuminated (BSI) image sensor to improve the radiation receiving of the image sensor to the light, but the type and structure of the image sensor are not limited to this, and a front-illuminated (FSI) image sensor may be adopted, which is not limited to this, but only the BSI image sensor is taken as an example in this embodiment, and the materials, structures, preparation, etc. of the metal wiring layer 102, the isolation structure 103, and the pixel unit 104 are not limited to this.
Next, referring to fig. 3, step S2 is performed to form a silicon oxide layer 300 on the semiconductor substrate 100.
Further, in this embodiment, before forming the silicon oxide layer 300, a step of forming an intermediate layer 200 on the semiconductor substrate 100 is further included, wherein the intermediate layer 200 may include one or a combination of a high-k dielectric layer, a silicon oxide, a silicon nitride, a silicon oxynitride and a transparent metal oxide, so as to protect the pixel unit 104 by the intermediate layer 200, and reduce or prevent reflection of incident light on the surface of the semiconductor substrate 100, and the kind of the intermediate layer 200 is not excessively limited herein.
Next, referring to fig. 4, step S3 is performed to etch the silicon oxide layer 200, and a groove 301 is formed in the silicon oxide layer 200, where the groove 301 is disposed corresponding to the pixel unit 104 array, so as to define an opening for receiving light of each pixel unit 104 in the pixel unit array. The method of forming the recess 301 may be performed by any suitable etching method known in the art, such as wet etching, dry etching, etc., to perform the patterning process.
Next, referring to fig. 5, step S4 is performed, wherein an aluminum metal layer 400 is formed on the surface of the silicon oxide layer 300, and a SiAlxOy layer 500 is formed between the formed aluminum metal layer 400 and the silicon oxide layer 300.
Specifically, the method for forming the aluminum metal layer 400 may include Physical Vapor Deposition (PVD), chemical Vapor Deposition (CVD), atomic Layer Deposition (ALD), metal Organic Chemical Vapor Deposition (MOCVD), jet Vapor Deposition (JVD), or the like, wherein aluminum is injected into the silicon oxide layer 300 after the aluminum metal layer 400 is formed, so that the SiAlxOy layer 500 having a good reflectivity is formed on the surface of the silicon oxide layer 300, thereby effectively preventing crosstalk between adjacent pixel units 104 in the image sensor and improving the light receiving efficiency of the image sensor.
Further, the physical vapor deposition method for forming the aluminum metal layer 400 includes a sputtering method or an ion plating method, for example, gas ionization is generated by using argon discharge, and positive ions of the gas bombard aluminum at a high speed under the action of an electric field to strike aluminum atoms and fly to the surface of the silicon oxide layer 300, so that silicon oxide and aluminum are mixed and finally deposited into a SiAlxOy film. The low temperature is important in the process of the present invention and is compatible with the BEOL level. Therefore, in the process of forming the aluminum metal layer 400 on the surface of the silicon oxide layer 300, the process temperature is required to be 400 ℃ or less.
As an example, the surface of the SiAlxOy layer 500 on top of the silicon oxide layer 300 has the aluminum metal layer 400, and the aluminum metal layer 400 is remained at a certain thickness on top of the silicon oxide layer 300, and the reflectivity of the image sensor can be improved by the aluminum metal layer 400 while being compatible with a fine pitch patterning process, since the aluminum metal layer 400 is suitable for optical isolation.
As an example, in the formed aluminum metal layer 400, the thickness of the aluminum metal layer 400 on top of the silicon oxide layer 300 is greater than the thickness of the aluminum metal layer 400 on the bottom of the recess 301 than the thickness of the aluminum metal layer 400 on the sidewall of the recess 301, so as to facilitate the subsequent etching process.
Of course, in other embodiments of the present invention, the technical effect of the present invention can be achieved without leaving the aluminum metal layer 400 on top of the silicon oxide layer 300 after the step of etching the aluminum metal layer 400.
Next, referring to fig. 6, step S5 is performed to etch, remove the aluminum metal layer 400 and the SiAlxOy layer 500 at the bottom of the recess 301, and remove the aluminum metal layer 400 at the sidewall of the recess 301 to expose the SiAlxOy layer 500 at the sidewall of the recess 301, so as to form a grid structure.
Specifically, since the etching rate of the aluminum metal layer 400 is greater than that of the SiAlxOy layer 500, and the aluminum metal layer 400 on the silicon oxide layer 300 has different thicknesses, when the etching process is performed, a method with high directivity and vertical etching may be used, so that the etching has directivity, that is, the etching amount in the vertical direction is greater than that in the lateral direction, to remove the aluminum metal layer 400 and the SiAlxOy layer 500 on the bottom of the recess 301, and remove the aluminum metal layer 400 on the sidewall of the recess 301 to expose the SiAlxOy layer 500 on the sidewall of the recess 301, so as to form the grid structure, thereby providing a high-reflectivity layer with good performance through the SiAlxOy layer 500, and effectively overcoming the problem of poor integrity of the aluminum metal layer 400, thereby effectively preventing the adjacent pixel units 104 in the image sensor from being cross-linked, and improving the receiving light efficiency of the image sensor.
Further, after the step of forming the grid structure, a step of forming a filter layer (not shown) and a microlens (not shown) in the groove 301 may be further included.
Specifically, the filter layer filled in the groove 301 may be used to filter the incident light entering the opening, thereby extracting the filtered wavelength. In general, the filter materials in adjacent pixel units 104 may correspond to, for example, R, G, B three colors, respectively, to form the image sensor in color, and the step of forming the microlenses on the filter layer may be further included to converge and collimate incident light.
Referring to fig. 6, the present embodiment further provides an image sensor, including:
a semiconductor substrate 100, in which a pixel cell array is formed in the semiconductor substrate 100;
a grid structure, the grid structure comprising:
a silicon oxide layer 300, wherein the silicon oxide layer 300 is located on the semiconductor substrate 100, and the silicon oxide layer 300 has a groove 301 therein, and the groove 301 is disposed corresponding to the pixel cell array, so as to define an opening for receiving light of each pixel cell 104 in the pixel cell array;
the SiAlxOy layer 500, the SiAlxOy layer 500 coats the silicon oxide layer 300 and exposes the bottom of the groove 301.
The preparation method of the image sensor may be referred to, but is not limited to, the image sensor in this embodiment is directly prepared by the preparation method, so that the preparation process of the image sensor is not repeated here,
as an example, the surface of the SiAlxOy layer 500 on top of the silicon oxide layer 300 has an aluminum metal layer 400 to increase the reflectivity of the image sensor through the aluminum metal layer 400.
As an example, the semiconductor substrate 100 and the silicon oxide layer 300 may further include an intermediate layer 200 therebetween, and the intermediate layer 200 may include one or a combination of a high-k dielectric layer, silicon oxide, silicon nitride, silicon oxynitride, and transparent metal oxide, so that the pixel unit 104 is protected by the intermediate layer 200 to reduce or prevent reflection of incident light at the surface of the semiconductor substrate 100, and the kind of the intermediate layer 200 is not excessively limited herein.
As an example, the groove 301 further has therein a filter layer (not shown) and a microlens (not shown) to provide the image sensor with a color through the filter layer, and to converge and collimate incident light through the microlens located on the filter layer.
In summary, in the image sensor and the method for manufacturing the same, a silicon oxide layer is formed on a semiconductor substrate having a pixel cell array, a recess corresponding to the pixel cell array is formed in the silicon oxide layer to define an opening for receiving light of each pixel cell in the pixel cell array, then an aluminum metal layer is formed on the surface of the silicon oxide layer, a SiAlxOy layer is formed between the formed aluminum metal layer and the silicon oxide layer, then an etching process is performed to remove the aluminum metal layer and the SiAlxOy layer at the bottom of the recess, and remove the aluminum metal layer at the sidewall of the recess to expose the SiAlxOy layer at the sidewall of the recess, thereby forming a grid structure.
The image sensor provided by the invention can provide a grid structure with high light isolation performance through the SiAlxOy layer, can effectively overcome the problem of poor integrity of an aluminum metal layer, and provides a high-reflectivity layer with good performance, so that crosstalk of adjacent pixel units in the image sensor can be effectively prevented, and the light receiving efficiency of the image sensor is improved.
The above embodiments are merely illustrative of the principles of the present invention and its effectiveness, and are not intended to limit the invention. Modifications and variations may be made to the above-described embodiments by those skilled in the art without departing from the spirit and scope of the invention. Accordingly, it is intended that all equivalent modifications and variations of the invention be covered by the claims, which are within the ordinary skill of the art, be within the spirit and scope of the present disclosure.
Claims (11)
1. A method for manufacturing an image sensor, comprising the steps of:
providing a semiconductor substrate, wherein a pixel unit array is formed in the semiconductor substrate;
forming a silicon oxide layer on the semiconductor substrate;
etching the silicon oxide layer, and forming a groove in the silicon oxide layer, wherein the groove is arranged corresponding to the pixel unit array so as to limit an opening of each pixel unit in the pixel unit array for receiving light;
forming an aluminum metal layer on the surface of the silicon oxide layer, and forming a SiAlxOy layer between the formed aluminum metal layer and the silicon oxide layer;
etching is carried out, the aluminum metal layer and the SiAlxOy layer which are positioned at the bottom of the groove are removed, the aluminum metal layer positioned on the side wall of the groove is removed, the SiAlxOy layer positioned on the side wall of the groove is exposed, and a grid structure is formed.
2. The method for manufacturing an image sensor according to claim 1, wherein: the method for forming the aluminum metal layer on the surface of the silicon oxide layer comprises a physical vapor deposition method; the etching step adopts a dry etching method.
3. The method for manufacturing an image sensor according to claim 2, wherein: the physical vapor deposition method comprises a sputtering method or an ion plating method, wherein the process temperature is less than or equal to 400 ℃ in the process of forming the aluminum metal layer on the surface of the silicon oxide layer.
4. The method for manufacturing an image sensor according to claim 1, wherein: after the step of etching the aluminum metal layer, the aluminum metal layer is arranged on top of the silicon oxide layer.
5. The method for manufacturing an image sensor according to claim 4, wherein: and the thickness of the aluminum metal layer positioned at the top of the silicon oxide layer is larger than that of the aluminum metal layer positioned at the bottom of the groove and larger than that of the aluminum metal layer positioned at the side wall of the groove.
6. The method for manufacturing an image sensor according to claim 1, wherein: the method further comprises the step of forming an intermediate layer between the semiconductor substrate and the silicon oxide layer, wherein the intermediate layer comprises one or a combination of a high-k dielectric layer, silicon oxide, silicon nitride, silicon oxynitride and transparent metal oxide.
7. The method for manufacturing an image sensor according to claim 1, wherein: after the step of forming the grid structure, the method further comprises the step of forming a filter layer and a micro lens in the groove.
8. An image sensor, the image sensor comprising:
a semiconductor substrate having a pixel cell array formed therein;
a grid structure, the grid structure comprising:
the silicon oxide layer is positioned on the semiconductor substrate, and is provided with a groove, and the groove is arranged corresponding to the pixel unit array so as to limit an opening for receiving light of each pixel unit in the pixel unit array;
and the SiAlxOy layer coats the silicon oxide layer and exposes the bottom of the groove.
9. The image sensor of claim 8, wherein: the surface of the SiAlxOy layer on top of the silicon oxide layer has an aluminum metal layer.
10. The image sensor of claim 8, wherein: an intermediate layer is further included between the semiconductor substrate and the silicon oxide layer, and the intermediate layer comprises one or a combination of a high-k dielectric layer, silicon oxide, silicon nitride, silicon oxynitride and transparent metal oxide.
11. The method for manufacturing an image sensor according to claim 8, wherein: the grooves are also provided with a light filtering layer and a micro lens.
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| CN117976686A (en) * | 2024-04-02 | 2024-05-03 | 合肥晶合集成电路股份有限公司 | Backside illuminated image sensor and manufacturing method thereof |
| CN117976686B (en) * | 2024-04-02 | 2024-06-11 | 合肥晶合集成电路股份有限公司 | Backside illuminated image sensor and manufacturing method thereof |
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