Method for improving white noise of image sensor

Abstract

The invention provides a method for improving white noise of an image sensor, and the method comprises the steps: providing a substrate, forming a first epitaxial layer on the substrate, and forming a gettering factor layer for capturing metal impurities on the upper surface of the first epitaxial layer through ion implantation; forming a second epitaxial layer on the first epitaxial layer; an image sensor is formed on the second epitaxial layer. The gettering factor layer can capture metal impurities, and white pixel dead pixels are improved.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a method for improving white noise of an image sensor. Background Art

[0002] Image sensors are key components that convert light signals into electrical signals. Their performance and quality directly affect the quality of the acquired images. White pixels are an important indicator for evaluating the performance of CIS (front-illuminated image sensor) devices, which directly reflects the imaging quality of the device.

[0003] To address the white pixel problem of image sensors, on the one hand, a variety of algorithms and technologies can be developed in the post-image processing process to detect and repair white pixels. On the other hand, process improvements can be made (raw materials, metal ion control, annealing to repair damage, impurity removal, etc.).

[0004] In order to solve the above problems, it is necessary to propose a new method to improve the white noise of image sensors. Summary of the invention

[0005] In view of the above-mentioned shortcomings of the prior art, an object of the present invention is to provide a method for improving white noise of an image sensor, so as to solve the problem in the prior art that bad white pixels affect the quality of the image sensor.

[0006] To achieve the above object and other related objects, the present invention provides a method for improving white noise of an image sensor, comprising:

[0007] Step 1: providing a substrate, forming a first epitaxial layer on the substrate, and forming a gettering layer for capturing metal impurities on the upper surface of the first epitaxial layer by ion implantation;

[0008] Step 2: forming a second epitaxial layer on the first epitaxial layer;

[0009] Step three: forming an image sensor on the second epitaxial layer.

[0010] Preferably, the substrate in step one is a P-type substrate.

[0011] Preferably, the thickness of the first epitaxial layer in step one is 1 to 6 microns.

[0012] Preferably, the ion source for ion implantation in step 1 is element C.

[0013] Preferably, the metal impurities in step one include at least one of Fe / Cu / Ni.

[0014] Preferably, the thickness of the second epitaxial layer in step 2 is 1 to 6 microns.

[0015] Preferably, the image sensor in step three is a front-illuminated image sensor.

[0016] Preferably, a back sealing structure is provided on the back side of the substrate.

[0017] Preferably, the method for forming the graphic sensor in step three comprises: forming a photodiode array on the second epitaxial layer by multiple ion implantations; forming a metal wiring structure; forming an anti-reflection and anti-reflection film; forming a filter; and making a microlens.

[0018] As described above, the method for improving the white noise of an image sensor of the present invention has the following beneficial effects:

[0019] The gettering factor layer of the present invention can capture metal impurities and improve white pixel bad points. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Shown is a schematic diagram of the process flow of the present invention;

[0021] Figure 2 Shown is a schematic diagram of a substrate of the present invention;

[0022] Figure 3 It is a schematic diagram of forming a first epitaxial layer according to the present invention;

[0023] Figure 4 Shown is a schematic diagram of forming an impurity gettering factor layer according to the present invention;

[0024] Figure 5 It is a schematic diagram of forming a second epitaxial layer according to the present invention. DETAILED DESCRIPTION

[0025] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0026] See also Figure 1 The present invention provides a method for improving white noise of an image sensor, comprising:

[0027] Step 1: Please refer to Figure 2 , providing a substrate 101, forming a first epitaxial layer 103 on the substrate 101, forming Figure 3 The structure shown in FIG. 1 is formed by ion implantation on the upper surface of the first epitaxial layer 103 to form a gettering factor layer 104 for capturing metal impurities, forming a structure as shown in FIG. Figure 4 The structure shown;

[0028] In some embodiments, the substrate 101 in step 1 is a P-type substrate 101 .

[0029] In some embodiments, the thickness of the first epitaxial layer 103 in step 1 is 1 to 6 micrometers.

[0030] In some embodiments, the ion source for ion implantation in step 1 is element C. In other embodiments, the ion source may also be other elements that can be used to capture metal impurities.

[0031] In some embodiments, the metal impurities in step 1 include at least one of Fe / Cu / Ni.

[0032] Step 2: forming a second epitaxial layer 105 on the first epitaxial layer 103, as shown in FIG. Figure 5 The structure shown;

[0033] In some embodiments, the thickness of the second epitaxial layer 105 in step 2 is 1 to 6 micrometers.

[0034] Step 3: forming an image sensor on the second epitaxial layer 105. The gettering layer 104 can capture metal impurities. According to the yield feedback, the white pixel defect is improved by about 20%.

[0035] In some embodiments, the image sensor in step three is a front-illuminated image sensor.

[0036] In some embodiments, a backside sealing structure 102 is disposed on the backside of the substrate 101 , and the material of the backside sealing structure 102 may be an insulating material such as silicon dioxide.

[0037] In some embodiments, the method for forming the graphic sensor in step three includes: forming a photodiode array on the second epitaxial layer 105 by multiple ion implantation; forming a metal wiring structure; forming an anti-reflection and anti-reflection film; forming a filter; and making a microlens.

[0038] It should be noted that the illustrations provided in this embodiment are only used to illustrate the basic concept of the present invention in a schematic manner. Therefore, the drawings only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0039] In summary, the gettering factor layer of the present invention can capture metal impurities and improve white pixel bad points. Therefore, the present invention effectively overcomes various shortcomings of the prior art and has high industrial utilization value.

[0040] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A method for improving white noise of an image sensor, characterized in that: At least: Step 1: providing a substrate, forming a first epitaxial layer on the substrate, and forming a gettering layer for capturing metal impurities on the upper surface of the first epitaxial layer by ion implantation; Step 2: forming a second epitaxial layer on the first epitaxial layer; Step three: forming an image sensor on the second epitaxial layer.

2. The method for improving white noise of an image sensor according to claim 1, characterized in that: The substrate in step 1 is a P-type substrate.

3. The method for improving white noise of an image sensor according to claim 1, characterized in that: The thickness of the first epitaxial layer in step 1 is 1 to 6 microns.

4. The method for improving white noise of an image sensor according to claim 1, characterized in that: In step 1, the ion source for ion implantation is the C element.

5. The method for improving white noise of an image sensor according to claim 1, characterized in that: The metal impurities in step one include at least one of Fe / Cu / Ni.

6. The method for improving white noise of an image sensor according to claim 1, characterized in that: The thickness of the second epitaxial layer in step 2 is 1 to 6 microns.

7. The method for improving white noise of an image sensor according to claim 1, characterized in that: The image sensor in step three is a front-illuminated image sensor.

8. The method for improving white noise of an image sensor according to claim 7, characterized in that: A back sealing structure is arranged on the back side of the substrate.

9. The method for improving white noise of an image sensor according to claim 1, characterized in that: The method for forming the graphic sensor in step three includes: forming a photodiode array on the second epitaxial layer by multiple ion implantations; forming a metal wiring structure; forming an anti-reflection and anti-reflection film; forming a filter; and making a microlens.

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