Shallow trench separation structure, formation method thereof and image sensor

Abstract

The invention discloses a shallow trench separation structure, a formation method thereof and an image sensor. The formation method comprises steps of providing a semiconductor substrate, and forminga grinding stopping layer on the semiconductor substrate; successively etching the grinding stopping layer and the semiconductor substrate, and shallow trenches in the grinding stopping layer and thesemiconductor substrate; forming oxide layers on the surface of the grinding stopping layer, side walls of the shallow trenches and the bottom; forming a fluorine-doped medium layer on the surface ofeach oxide layer; filling the interiors of the shallow trench with insulation media, wherein the insulation media fill the shallow trench and cover the fluorine-doped medium layer; and carrying out annealing technology. According to the invention, through the planarization technology, by removing the insulation media, the fluorine-doped medium layer and the oxide layers on the grinding stopping layer, a shallow trench separation structure is formed. Through the shallow trench separation structure, dark current of the image sensor can be reduced.

Description

technical field [0001] The invention relates to the manufacturing field of semiconductor devices, in particular to a shallow trench isolation structure and its forming method, and an image sensor. Background technique [0002] With the development trend of high-density integrated circuits, the devices that make up the circuit are placed more closely in the chip to fit the available space of the chip. Correspondingly, the density of active devices per unit area of ​​the semiconductor substrate continues to increase, so effective insulation between devices becomes more important. [0003] Shallow Trench Isolation (STI) technology has good isolation effects (such as process isolation effect and electrical isolation effect), shallow trench isolation technology also has the advantages of reducing the area occupied by the wafer surface and increasing the integration of devices, etc. advantage. Therefore, with the reduction of the size of integrated circuits, shallow trench isola...

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Problems solved by technology

[0004] However, when the shallow trench isolation structure is used to isolate light-receiving elements such as photodiodes, photoconductive elements, and photoelectric tubes, the shallow trench isolation structures formed in the prior art will generate dark current in the light-receiving elements and affect the performance of semiconductor devices.

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