Preparation method of semiconductor device

Abstract

The invention discloses a preparation method of a semiconductor device. The preparation method of the semiconductor device comprises the following steps: firstly providing a semiconductor substrate, wherein the semiconductor substrate is provided with a shallow trench; then performing ion implantation on the bottom of the shallow trench; finally forming a liner oxide layer on the bottom and the side wall of the shallow trench. According to the preparation method of the semiconductor device, ion implantation is performed on the bottom of the shallow trench so as to form a doping region on the bottom of the trench shallow, and the growth speed of the liner oxide layer in the doping region is greater than that of the liner oxide layer on the side wall of the shallow trench, so that in the finally formed liner oxide layer, the bottom thickness of the liner oxide layer is obviously improved, further the uniformity of the bottom thickness and the sidewall thickness of liner oxides in shallow trench isolation is increased, current leakage of shallow trench isolation is prevented, and thus the electrical property of a shallow trench isolation device is improved.

Description

technical field [0001] The invention relates to the technical field of semiconductors, in particular to a method for preparing a semiconductor device. Background technique [0002] The rapid development of integrated circuit manufacturing process makes semiconductor devices increasingly integrated and miniaturized. With the integration of semiconductor devices, the size of the semiconductor components and the size of the isolation structure isolating the semiconductor components are also reduced. Therefore, in the semiconductor manufacturing process, it is very critical to form a good isolation structure. A common method of forming an isolation structure is to form a field oxide layer (Local Oxidation of Silicon, referred to as LOCOS) by means of local oxidation. However, this method is not suitable for semiconductor devices with high integration density, and bird's beak erosion will also occur. The problem (Bird's beak encroachment). Therefore, the shallow trench isolati...

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Problems solved by technology

[0004] Due to the uneven bottom thickness and sidewall thickness of the lining oxide, it will cause STI leakage

Especially after the lining oxide is formed, before the high-density plasma chemical vapor deposition (HDPCVD) process, the lining oxide will be subjected to a pull back process, which will further thin the shallow trench 110 bottom thickness, which is more likely to cause STI leakage

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