Method for improving CIS imaging quality by air ring

A technology of imaging quality and air ring, applied in the field of CMOS image sensor technology, can solve the problems of reducing image quality, pixel "optical mutual interference, reducing sensors, etc., and achieve the effect of improving imaging quality, improving optical mutual interference, and improving conversion efficiency.

Inactive Publication Date: 2010-06-16
SHANGHAI HUA HONG NEC ELECTRONICS
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AI Technical Summary

Problems solved by technology

2. The height of the rear section that is too thick causes the incident light to go through a relatively long distance through the microlens to reach the surface of the photosensitive diode, which may cause "light mutual interference" between pixels and reduce the sensor's response angle to light. This reduces the quality of the image, especially as the size of the pixels shrinks, and this phenomenon becomes more and more serious (such as figure 2 shown)
As shown in Figure 3(a) and Figure 3(b), for the incident light at the same angle, when H1>H2, there must be D1>D2; disturb"

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  • Method for improving CIS imaging quality by air ring
  • Method for improving CIS imaging quality by air ring
  • Method for improving CIS imaging quality by air ring

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Embodiment Construction

[0015] The invention discloses a new CMOS image sensor back-end process. After completing all the traditional dielectric layer and metal layer processes (before the passivation layer), the process utilizes one photolithography and etching to remove the dielectric material around the pixel unit. The layer is etched away, and then the final passivation layer is deposited by non-uniform CVD (Chemical Vapor Deposition) to form an air ring surrounding the pixel, and the subsequent process is consistent with the traditional process. Since air with a refractive index of 1 is introduced into the pixel, the principle of total reflection of light is used: that is, when light is incident from an optically dense medium to an optically sparse medium, if the incident angle is greater than a fixed angle (depending on the refraction of the two media rate), then the incident light can be fully emitted.

[0016] Therefore, when the incident light is incident at a large angle (total reflection i...

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Abstract

The invention discloses a method for improving the CIS imaging quality by air ring, comprising the following steps of: 1, forming a first dielectric layer by a chemical vapor deposition manner and flattening the first dielectric layer; 2, forming a through hole and a metal layer; 3, repeating the steps 1 and 2 till the dielectric layer and the metal layer prior to a passivation layer are finished; 4, etching the dielectric layer around pixels to the surface of a photoelectric diode; and 5, depositing a passivation layer in a non-uniformity chemical vapor deposition manner to form an air ring surrounding the pixels. The invention can effectively solve optical interference between the pixels and improve the response angle of a sensor to the light so as to improve the image quality.

Description

technical field [0001] The invention relates to a CMOS image sensor technology, in particular to a method for improving the imaging quality of the CMOS image sensor. Background technique [0002] In the traditional CIS (CMOS image sensor) back-end process, there is generally only one dielectric layer. When the incident light is incident at a large angle, since the back-end dielectric layer and metal layer of CIS have a certain height and the height is difficult to reduce, Therefore, the incident light may be incident on adjacent CIS pixels, resulting in "optical mutual interference", thereby causing noise in adjacent CIS pixels; at the same time, this also indicates that for a specific pixel, the light The response angle cannot be too large, which greatly limits the light conversion efficiency and reduces the imaging quality of the image sensor. [0003] The traditional CIS back-end process such as figure 1 As shown, its post-stage process is as follows: 1. CVD deposition ...

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Application Information

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Patent Type & AuthorityApplications(China)
IPC IPC(8): H01L21/82H01L27/146H01L23/552
Inventor陈华伦熊涛陈瑜陈雄斌罗啸
OwnerSHANGHAI HUA HONG NEC ELECTRONICS