Method for forming dual-depth trench

Abstract

The utility model relates to a method for forming a dual-depth trench, which includes the steps that: a semiconductor substrate, which sequentially consists of a silicon substrate, a buried oxide layer, a barrier layer and an oxide layer, is provided; the semiconductor substrate comprises a pixel area and a peripheral area; a photoresist pattern is formed on the oxide layer; with the photoresist pattern as a mask, the oxide layer is implanted with ions and annealed, so that an ion-implanted layer is formed in the oxide layer of the peripheral area; the oxide layer, the barrier layer, the buried oxide layer and the silicon substrate are etched, so that a first trench and a second trench are formed; and the depth of the first trench is smaller than the depth of the second trench. The invention can effectively increase the image quality of a CMOS image sensor.

Description

technical field [0001] The invention relates to the field of semiconductor manufacturing, in particular to a method for forming double-depth trenches. Background technique [0002] At present, the charge coupled device (CCD) is the main practical solid-state image sensing device, which has the advantages of low read noise, large dynamic range, and high response sensitivity. The disadvantage of Complementary-Metal-Oxide-Semiconductor (CMOS) technology compatibility is that it is difficult to achieve single-chip integration for image sensors based on charge-coupled devices. The CMOS image sensor (CMOS Imagesensor, CIS) can integrate the pixel array and peripheral circuits on the same chip because of the same CMOS technology. Compared with the charge-coupled device, the CMOS image sensor has small size, light weight, low power consumption Low cost, convenient programming, easy control and low average cost. [0003] In general, existing image sensor technology can be found in ...

AI Technical Summary

Problems solved by technology

Under the existing process basis, reducing the interval of the isolation region will lead to an increase in the aspect ratio of the trench (Aspect ratio, A / R) or a reduction in the depth of the trench, and increasing the aspect ratio of the trench will make the subsequent shallow trench isolation (Shallow trench isolation, STI) trench filling process has the problem of voids, and the device manufacturing yield is reduced; reducing the depth of the trench will affect the operation of peripheral circuits, resulting in device failure

Images