CN113823650A - Method of forming a CMOS image sensor - Google Patents
Method of forming a CMOS image sensor Download PDFInfo
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- CN113823650A CN113823650A CN202110959962.XA CN202110959962A CN113823650A CN 113823650 A CN113823650 A CN 113823650A CN 202110959962 A CN202110959962 A CN 202110959962A CN 113823650 A CN113823650 A CN 113823650A
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
- H10F39/00—Integrated devices, or assemblies of multiple devices, comprising at least one element covered by group H10F30/00, e.g. radiation detectors comprising photodiode arrays
- H10F39/011—Manufacture or treatment of image sensors covered by group H10F39/12
- H10F39/014—Manufacture or treatment of image sensors covered by group H10F39/12 of CMOS image sensors
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
- H10F39/00—Integrated devices, or assemblies of multiple devices, comprising at least one element covered by group H10F30/00, e.g. radiation detectors comprising photodiode arrays
- H10F39/10—Integrated devices
- H10F39/12—Image sensors
- H10F39/18—Complementary metal-oxide-semiconductor [CMOS] image sensors; Photodiode array image sensors
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
- H10F39/00—Integrated devices, or assemblies of multiple devices, comprising at least one element covered by group H10F30/00, e.g. radiation detectors comprising photodiode arrays
- H10F39/80—Constructional details of image sensors
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
- H10P30/00—Ion implantation into wafers, substrates or parts of devices
- H10P30/20—Ion implantation into wafers, substrates or parts of devices into semiconductor materials, e.g. for doping
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Abstract
本发明提供一种CMOS图像传感器的形成方法，通过对光电二极管区域的半导体衬底表面进行氮元素掺杂，掺杂的氮元素会在光电二极管区域的半导体衬底表面形成硅氮键，可以有效减少后续工艺带来的等离子体诱发损伤，减少暗电流和白色像素的产生，提高CIS的信噪比，提高产品良率和图像质量，改善图像传感器性能。此外，还可以在氮元素掺杂之后，再对光电二极管区域的半导体衬底表面进行氟元素掺杂，所形成的硅氟键可以进一步减少等离子体诱发损伤。
The invention provides a method for forming a CMOS image sensor. By doping the surface of the semiconductor substrate in the photodiode region with nitrogen element, the doped nitrogen element will form a silicon-nitrogen bond on the surface of the semiconductor substrate in the photodiode region, which can effectively Reduce the plasma-induced damage caused by the subsequent process, reduce the generation of dark current and white pixels, improve the signal-to-noise ratio of CIS, improve product yield and image quality, and improve image sensor performance. In addition, the surface of the semiconductor substrate in the photodiode region can be doped with fluorine element after nitrogen element doping, and the formed silicon-fluorine bond can further reduce plasma-induced damage.
Description
Technical Field
The invention relates to a method for forming a CMOS image sensor.
Background
A CMOS Image Sensor (CIS) is widely used in various new fields such as smart phones, tablet computers, automobiles, and medical care as a device unit for converting optical signals into digital electrical signals. Incident photons are converted into electrons by the pixel array, and when one integration period is completed, the collected electrons are converted into digital signals by the analog circuit and the digital circuit and are transmitted to the output terminal of the sensor.
As shown in fig. 1, in a current CMOS image sensor manufacturing process, a photodiode 101 is formed in a semiconductor substrate 100, and then a transfer transistor, a reset transistor, and other structures are formed, and then an Oxide layer 106, which is typically a Silicon Rich Oxide (SRO), is formed on the surface of the semiconductor substrate to serve as a Salicide Block (SAB) for protecting a region where a Salicide should not be formed in a subsequent process from being etched and opened.
However, during the formation of the salicide block layer or in the subsequent processes, plasma is often introduced to cause Plasma Induced Damage (PID), which causes a large number of dangling bonds to be formed on the silicon oxide surface, and the existence of these dangling bonds is easy to generate electrons in the dark field of the image sensor, and these electrons are collected by the photodiode, which generates dark current or White Pixel (WP) phenomenon, which affects the product yield and image quality.
Disclosure of Invention
The invention aims to provide a method for forming a CMOS image sensor, which reduces dark current and white pixels, improves the signal-to-noise ratio of a CIS, improves the product yield and image quality, and improves the performance of the image sensor.
Based on the above consideration, the present invention provides a method for forming a CMOS image sensor, including: providing a semiconductor substrate; forming a photodiode in the semiconductor substrate; forming an oxide layer on the surface of the semiconductor substrate to serve as a self-aligned silicide blocking layer; before, after or at the same time of forming the oxide layer, carrying out nitrogen element doping on the surface of the semiconductor substrate of the photodiode region so as to reduce plasma-induced damage of subsequent processes; subsequent processes are performed to form a CMOS image sensor.
Preferably, the nitrogen element doping is performed by injecting nitrogen by using decoupling plasma before or after the oxide layer is formed.
Preferably, the nitrogen doping is performed by adjusting the ratio and flux of a reaction gas including SiH while forming the oxide layer4And is selected from NH3、NO、N2O、N2At least one of (1).
Preferably, the method for forming a CMOS image sensor further includes: and after the nitrogen element doping, fluorine element doping is carried out on the surface of the semiconductor substrate of the photodiode region.
Preferably, decoupling plasma fluorine injection is used for fluorine element doping.
Preferably, the method for forming a CMOS image sensor further includes: and after the nitrogen element doping or the fluorine element doping, carrying out annealing treatment on the semiconductor substrate.
Preferably, the mode of forming the oxide layer on the surface of the semiconductor substrate is chemical vapor deposition, and the thickness of the oxide layer is 5nm-50 nm.
Preferably, the method for forming a CMOS image sensor further includes: before forming the oxide layer, forming a grid electrode positioned on the surface of the semiconductor substrate and a source drain electrode positioned in the semiconductor substrate, wherein the self-aligned silicide blocking layer covers the grid electrode and the source drain electrode.
Preferably, the method for forming a CMOS image sensor further includes: forming a pinning layer overlying the photodiode prior to forming an oxide layer, the salicide block layer overlying the pinning layer.
According to the method for forming the CMOS image sensor, nitrogen is doped on the surface of the semiconductor substrate in the photodiode region, the doped nitrogen can form a silicon-nitrogen bond on the surface of the semiconductor substrate in the photodiode region, the bonding force of the silicon-nitrogen bond is large, and the silicon-nitrogen bond is not easy to break in the subsequent plasma etching process, so that compared with a conventional silicon-hydrogen bond, the silicon-nitrogen bond can effectively reduce plasma induced damage brought by the subsequent process, reduce dark current and white pixels, improve the signal-to-noise ratio of the CIS, improve the product yield and image quality, and improve the performance of the image sensor. In addition, after the nitrogen element is doped, fluorine element doping can be carried out on the surface of the semiconductor substrate of the photodiode region, and the formed silicon-fluorine bond can further reduce plasma induced damage.
Drawings
Other features, objects and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments thereof, which proceeds with reference to the accompanying drawings.
FIG. 1 is a schematic diagram of a CMOS image sensor of the prior art;
FIG. 2 is a flow chart of a method of forming a CMOS image sensor of the present invention;
fig. 3-8 are process diagrams illustrating a method for forming a CMOS image sensor according to an embodiment of the present invention.
In the drawings, like or similar reference numbers indicate like or similar devices (modules) or steps throughout the different views.
Detailed Description
In order to solve the problems in the prior art, the invention provides a method for forming a CMOS image sensor, which reduces plasma-induced damage caused by subsequent processes, reduces dark current and white pixel generation, improves the signal-to-noise ratio of the CIS, improves the yield and image quality of products, and improves the performance of the image sensor.
In the following detailed description of the preferred embodiments, reference is made to the accompanying drawings which form a part hereof. The accompanying drawings illustrate, by way of example, specific embodiments in which the invention may be practiced. The illustrated embodiments are not intended to be exhaustive of all embodiments according to the invention. It is to be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present invention. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present invention is defined by the appended claims.
As shown in fig. 2, the method for forming a CMOS image sensor of the present invention includes: providing a semiconductor substrate; forming a photodiode in the semiconductor substrate; forming an oxide layer on the surface of the semiconductor substrate to serve as a self-aligned silicide blocking layer; before, after or at the same time of forming the oxide layer, carrying out nitrogen element doping on the surface of the semiconductor substrate of the photodiode region so as to reduce plasma-induced damage of subsequent processes; subsequent processes are performed to form a CMOS image sensor.
The following is a detailed description of specific embodiments.
Fig. 3 to 8 are process views illustrating a method of forming a CMOS image sensor according to a preferred embodiment of the present invention.
Referring to fig. 3, a semiconductor substrate 200 is provided, and a photodiode 201 is formed in the semiconductor substrate 200. In other preferred embodiments not shown, a pinning layer covering the photodiode 201 may be further formed, the pinning layer being mainly formed by doping at least one P-type element of boron, indium, and gallium for blocking electrons generated from the surface of the substrate from entering the photodiode 201.
Referring to fig. 4, a gate dielectric layer 203 and a gate 204 (including a gate sidewall spacer) are sequentially formed on the surface of a semiconductor substrate, and a source and drain 205 are formed in the semiconductor substrate, so as to form transistor structures such as a transfer transistor and a reset transistor.
Referring to fig. 5, a salicide block layer 206 is formed on the surface of the semiconductor substrate, for example, by chemical vapor deposition to form a 5nm-50nm thick oxide layer 206 as a salicide block layer on the surface of the semiconductor substrate, and the salicide block layer 206 covers the gate 204, the source and drain 205 (and the pinning layer if present) of the transistor, and is used to protect the salicide region from being etched open in the subsequent process.
Referring to fig. 6, after the oxide layer 206 is formed, nitrogen element doping is performed on the semiconductor substrate surface of the photodiode region. In other preferred embodiments not shown, the nitrogen doping may also be performed before the step of forming the oxide layer 206. For example, the nitrogen element doping is carried out by adopting a mode of decoupling plasma nitrogen injection (DPN), and the concentration range of the nitrogen element is 1E 13-1E 16 per square centimeter.
In addition, the oxide layer 206 may be formed while doping nitrogen by adjusting the ratio and flux of a reaction gas including SiH4And NH3、NO、N2O、N2At least one of (1).
The doped nitrogen element can form a silicon-nitrogen bond with strong binding force on the surface of the semiconductor substrate in the photodiode region, and in the subsequent plasma process, the silicon-nitrogen bond with strong binding force is not easy to break under the bombardment of plasma, so that the plasma induced damage brought by the subsequent process can be effectively reduced, the generation of dark current and white pixels is reduced, the signal-to-noise ratio of the CIS is improved, the product yield and the image quality are improved, and the performance of the image sensor is improved.
As shown in fig. 7 and 8, it is further preferable that the surface of the semiconductor substrate in the photodiode region is doped with fluorine after the nitrogen element is doped. For example, fluorine element doping is carried out by adopting a decoupling plasma fluorine injection (DPF) mode, the concentration range of the fluorine element is 1E 13-1E 16 per square centimeter, and similarly, the formed silicon-fluorine bond is not easy to break under the bombardment of plasma, so that the plasma-induced damage can be further reduced, and the performance of the image sensor is improved.
In addition, after the nitrogen element or the fluorine element is doped, annealing treatment can be carried out on the semiconductor substrate so as to activate the source and drain regions, meanwhile, the doped nitrogen element/fluorine element is promoted to fully react with silicon in the semiconductor substrate so as to form a silicon-nitrogen bond/silicon-fluorine bond with strong bonding force, and subsequent processes are carried out so as to form the complete CMOS image sensor.
In summary, according to the forming method of the image sensor of the present invention, the nitrogen element is doped on the surface of the semiconductor substrate in the photodiode region, and the doped nitrogen element forms a silicon-nitrogen bond on the surface of the semiconductor substrate in the photodiode region, so that plasma induced damage caused by a subsequent process can be effectively reduced, generation of dark current and white pixels can be reduced, a signal-to-noise ratio of the CIS can be improved, a yield of the product and image quality can be improved, and a performance of the image sensor can be improved. In addition, fluorine element doping can be carried out on the surface of the semiconductor substrate of the photodiode region after nitrogen element doping, and the formed silicon-fluorine bond can further reduce plasma induced damage.
It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive. Furthermore, it will be obvious that the word "comprising" does not exclude other elements or steps, and the word "a" or "an" does not exclude a plurality. Several elements recited in the apparatus claims may also be implemented by one element. The terms first, second, etc. are used to denote names, but not any particular order.
Claims (9)
1. A method of forming a CMOS image sensor, comprising:
providing a semiconductor substrate;
forming a photodiode in the semiconductor substrate;
forming an oxide layer on the surface of the semiconductor substrate to serve as a self-aligned silicide blocking layer;
before, after or at the same time of forming the oxide layer, carrying out nitrogen element doping on the surface of the semiconductor substrate of the photodiode region so as to reduce plasma-induced damage of subsequent processes;
subsequent processes are performed to form a CMOS image sensor.
2. The method of claim 1, wherein nitrogen doping is performed by decoupled plasma nitrogen implantation before or after the oxide layer is formed.
3. The method of claim 1, wherein the doping of nitrogen is performed while adjusting a ratio and a flux of a reaction gas including SiH to form an oxide layer4And is selected from NH3、NO、N2O、N2At least one of (1).
4. The method of forming a CMOS image sensor as claimed in claim 1, further comprising: and after the nitrogen element doping, fluorine element doping is carried out on the surface of the semiconductor substrate of the photodiode region.
5. The method of claim 4, wherein fluorine doping is performed using decoupled plasma fluorine implantation.
6. The method of forming a CMOS image sensor as claimed in claim 1 or 4, further comprising: and after the nitrogen element doping or the fluorine element doping, carrying out annealing treatment on the semiconductor substrate.
7. The method of claim 1, wherein the oxide layer is formed on the surface of the semiconductor substrate by chemical vapor deposition to a thickness of 5nm to 50 nm.
8. The method of forming a CMOS image sensor as claimed in claim 1, further comprising: before forming the oxide layer, forming a grid electrode positioned on the surface of the semiconductor substrate and a source drain electrode positioned in the semiconductor substrate, wherein the self-aligned silicide blocking layer covers the grid electrode and the source drain electrode.
9. The method of forming a CMOS image sensor as claimed in claim 1, further comprising: forming a pinning layer overlying the photodiode prior to forming an oxide layer, the salicide block layer overlying the pinning layer.
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| CN202110959962.XA CN113823650A (en) | 2021-08-20 | 2021-08-20 | Method of forming a CMOS image sensor |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115274725A (en) * | 2022-07-25 | 2022-11-01 | 华虹半导体(无锡)有限公司 | Image sensor and method for manufacturing the same |
| CN115312556A (en) * | 2022-08-17 | 2022-11-08 | 华虹半导体(无锡)有限公司 | CIS device manufacturing method |
| CN115528055A (en) * | 2022-10-12 | 2022-12-27 | 华虹半导体(无锡)有限公司 | CMOS image sensor and its preparation method |
| CN115911069A (en) * | 2022-11-25 | 2023-04-04 | 华虹半导体(无锡)有限公司 | A Method of Improving the Performance of CMOS Image Sensor |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20070037313A1 (en) * | 2005-08-10 | 2007-02-15 | Dongbu Electronics Co., Ltd. | CMOS image sensor and manufacturing method thereof |
| CN105514130A (en) * | 2014-10-14 | 2016-04-20 | 中芯国际集成电路制造(上海)有限公司 | Manufacturing method of CMOS image sensor |
| US20210218914A1 (en) * | 2020-01-09 | 2021-07-15 | Omnivision Technologies, Inc. | Selective nitrided gate-oxide for rts noise and white-pixel reduction |
-
2021
- 2021-08-20 CN CN202110959962.XA patent/CN113823650A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20070037313A1 (en) * | 2005-08-10 | 2007-02-15 | Dongbu Electronics Co., Ltd. | CMOS image sensor and manufacturing method thereof |
| CN105514130A (en) * | 2014-10-14 | 2016-04-20 | 中芯国际集成电路制造(上海)有限公司 | Manufacturing method of CMOS image sensor |
| US20210218914A1 (en) * | 2020-01-09 | 2021-07-15 | Omnivision Technologies, Inc. | Selective nitrided gate-oxide for rts noise and white-pixel reduction |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115274725A (en) * | 2022-07-25 | 2022-11-01 | 华虹半导体(无锡)有限公司 | Image sensor and method for manufacturing the same |
| CN115312556A (en) * | 2022-08-17 | 2022-11-08 | 华虹半导体(无锡)有限公司 | CIS device manufacturing method |
| CN115528055A (en) * | 2022-10-12 | 2022-12-27 | 华虹半导体(无锡)有限公司 | CMOS image sensor and its preparation method |
| CN115911069A (en) * | 2022-11-25 | 2023-04-04 | 华虹半导体(无锡)有限公司 | A Method of Improving the Performance of CMOS Image Sensor |
| CN115911069B (en) * | 2022-11-25 | 2026-03-31 | 华虹半导体(无锡)有限公司 | A method to improve the performance of CMOS image sensors |
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