Method of forming back-illuminated image sensor with deep trench isolation structure

Abstract

The present invention provides a method for forming a back-illuminated image sensor with a deep trench isolation structure. The method comprises the steps of S1 providing a device wafer with a first surface and a second surface, and forming a deep trench isolation structure at the first surface of a device wafer, S2 irradiating the surface of the deep trench isolation structure by using laser to raise semiconductor surface temperature so as to repair the damage of the deep trench isolation structure and forming an oxide layer through oxidation under the effect of photoionization and high temperature, wherein the temperature of the first surface is higher than that of the second surface in the laser irradiation process, S3 removing the oxide layer to repair the damage of the deep trench isolation structure. According to the method, laser-assisted oxidation is used, combined with a wet method oxide layer removal process, the lattice damage of the deep trench isolation structure is removed, an image sensor device and metal interconnection are not affected nearly, thus the pixel quality of the image sensor is improved, and thus the carrier migration efficiency is raised, dark current is prevented, and a signal to noise ratio is raised.

Description

technical field [0001] The invention relates to the field of image sensors, in particular to a method for forming a back-illuminated image sensor with a deep trench isolation structure. Background technique [0002] An image sensor is a semiconductor device that converts an optical signal into an electrical signal, and the image sensor has a photoelectric conversion element. [0003] Image sensors can be further divided into complementary metal oxide (CMOS) image sensors and charge-coupled device (CCD) image sensors. The advantage of the CCD image sensor is that it has high image sensitivity and low noise, but it is difficult to integrate the CCD image sensor with other devices, and the power consumption of the CCD image sensor is relatively high. In contrast, CMOS image sensors have the advantages of simple process, easy integration with other devices, small size, light weight, low power consumption, and low cost. Therefore, with the development of technology, CMOS image ...

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Problems solved by technology

[0005] The object of the present invention is to provide a method for forming a back-illuminated image sensor with a deep trench isolation structure, so as to solve the problem that the defects of the deep trench isolation structure are difficult to remove. 800 degrees Celsius will cause functional damage to image sensor devices and affect the quality of image sensor devices

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