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'Gamma' ray radiation method for improving imageing quality of CDMA analog image sensor

A technology for imaging quality and simulating images, which is applied in the fields of image sensing and particle irradiation, and can solve problems such as the decrease of the signal-to-noise ratio of the output signal, the degradation of image quality, and the decrease of device yield

Inactive Publication Date: 2002-07-17
TSINGHUA UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the threshold value of the transistor amplifier in each pixel and the shared readout amplifier in each column has some differences. This discrete deviation of the amplifier, that is, non-uniformity, will cause fixed pattern noise and reduce the signal-to-noise ratio of the output signal, resulting in Captured image quality degrades, device yield drops

Method used

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  • 'Gamma' ray radiation method for improving imageing quality of CDMA analog image sensor
  • 'Gamma' ray radiation method for improving imageing quality of CDMA analog image sensor
  • 'Gamma' ray radiation method for improving imageing quality of CDMA analog image sensor

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Embodiment 1

[0041] See figure 1 . A black-and-white CMOS analog image sensor, when the gamma-ray dose rate is 1.25Krad(Si) / min, the output image clarity is better after cumulative irradiation of gamma-ray dose not greater than 80Krad(Si). The clarity of the output image is the best after the cumulative 40-60 Krad(Si) γ-ray dose is irradiated. When the radiation dose accumulated above 100 Krad(Si), the complete output image was not captured.

[0042] exist figure 2 In, the non-uniformity of the dark output image of the black-and-white CMOS analog image sensor is 10% when it is not irradiated. At a dose rate of 1.25Krad(Si) / min, the inhomogeneity of the dark output image of the device is slightly reduced after 20-60Krad(Si) γ-ray dose irradiation; the dark noise of the device is the smallest after 40Krad(Si) dose irradiation And the dynamic range is the largest, and this multi-imaging definition is also the best.

[0043] The dark output parameters of the black-and-white CMOS analog i...

Embodiment 2

[0054] When the 5 CMOS analog image sensors are irradiated with different γ-ray doses, the output image clarity is better when the γ-ray dose is less than 100Krad(Si), and the output image is clear when the 60-100Krad(Si) The best degree. After 140Krad (Si) γ-ray dose irradiation, the output image clarity becomes worse; at the same time, the brightness of the dark output image increases significantly, such as Figure 4 shown.

[0055] The output images of CMOS analog image sensors irradiated with less than 120Krad(Si) γ-ray dose and placed at room temperature for 10 days are better than those without irradiation. After 140Krad (Si) γ-ray dose irradiation and 10 days at room temperature, the output image definition is still not good, such as Figure 5 shown.

[0056] It can be seen that the gamma ray irradiation method proposed by the present invention can improve the imaging quality of the CMOS analog image sensor, and help to improve the yield rate and high-quality product...

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Abstract

The gamma-ray irradiation method for improving image quality of CMOS analog image sensor is characterized by that its irradiation temp. is room temp., its gamma-ray irradiation dose to the above-mentioned sensor is 20-120 Krad (si), after irradiation it make annealing treatment, annealing temp. is room temp. to 100 deg.C, annealing time is 40 min. to 15 days, the annealing time can be reduced with the rise of annealing temp. and its atmosphere is air. Its improvement effect is obvious, and can raise product yield.

Description

technical field [0001] A gamma ray irradiation method for improving the imaging quality of a CMOS analog image sensor belongs to the technical field of image sensing and particle irradiation. Background technique [0002] The current practical CMOS analog image sensor is usually an active pixel sensor, which integrates a photoelectric conversion unit and an image control circuit on a P-type Si epitaxial layer on a P-type Si substrate. Each pixel element has a photosensitive area, an n-type floating diffusion area and a transfer transistor. The structure of the photosensitive array is usually: MOS capacitor structure, below is the buried n-type region on the p-type Si epitaxial layer, with SiO in the middle 2 layer isolation. The photosensitive array generates photogenerated electrons after capturing photons. The transfer transistor senses the photogenerated electrons from the photosensitive area to the floating diffusion area. The floating diffusion stores and accumulate...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G21G1/12H01L21/324
Inventor 孟祥提康爱国
Owner TSINGHUA UNIV