Image sensor and forming method thereof

Abstract

The invention discloses an image sensor and a forming method thereof. The method comprises the following steps: providing a semiconductor substrate, wherein a hard mask layer is formed on the back ofthe semiconductor substrate, and a front structure is formed on the front of the semiconductor substrate; forming a graphical mask layer, and etching the hard mask layer according to the mask layer soas to form an etching groove, wherein the etching groove runs through the hard mask layer, the side wall of the etching groove comprises an upper side wall and a lower side wall which are connected vertically, and the included angle between the upper side wall and the surface of the hard mask layer is an obtuse angle; taking the mask layer as a mask, and etching the semiconductor substrate so that the etching groove runs through the semiconductor substrate; forming a dielectric layer, wherein the bottom and the side wall of the etching groove are covered with the dielectric layer, and the hard mask layer is covered with the dielectric layer. Through the scheme, the possibility of the cracking problem for the hard mask layer can be reduced.

Description

technical field [0001] The invention relates to the technical field of semiconductor manufacturing, in particular to an image sensor and a forming method thereof. Background technique [0002] In the existing semiconductor manufacturing process, there is a process of filling the dielectric layer in the trench. For example, in the manufacturing process of a CMOS image sensor (CMOS Image Sensors, CIS) device, it can be formed on the front side of the semiconductor substrate first. Logic devices, pixel devices, and metal interconnection structures, etc., are then bonded to the front side of the semiconductor substrate using a carrier wafer, and then on the back side of the semiconductor substrate to form through holes (Through Silicon Via, TSV), filter (Filter ) and other structures. [0003] Specifically, in the existing process of forming TSVs, a hard mask layer is usually formed on the surface of the semiconductor substrate, and then the hard mask layer is etched to form TS...

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Problems solved by technology

[0004] However, in the prior art, the hard mask layer is prone to cracking at the top opening of the etched trench, which affects subsequent processes and product quality, and the dielectric layer is prone to cracking at the top of the etched trench. Closure phenomenon, the formation of dielectric holes in the etching trench, will further affect the subsequent process and product quality

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