Manufacturing method of shallow trench isolation structure

Abstract

The invention discloses a manufacturing method of a shallow trench isolation structure. The manufacturing method comprises the following steps: step 1, forming a shallow trench on a semiconductor substrate; step 2, coating a polyazosilane layer; and step 3, performing the oxygen-nitrogen replacement process to convert the polyazosilane layer into a silicon dioxide layer and form a shallow trench isolation structure; wherein the oxygen-nitrogen replacement process includes more than two times of furnace tube water vapor process, and a thermal annealing process and a thinning process are included between the two times of furnace tube water vapor process. The PSZ can be applied to realize good filling of the shallow trench, the oxygen-nitrogen replacement effect of the PSZ and the compactnessof the converted silicon dioxide can be improved so as to improve the film quality of the silicon dioxide and reduce the thermal process of the active region.

Description

technical field [0001] The invention relates to a method for manufacturing a semiconductor integrated circuit, in particular to a method for manufacturing a shallow trench isolation (STI) structure. Background technique [0002] The aspect ratio of shallow trenches of STI in the 20nm NAND flash memory (Flash) process is greater than 13, and the old processes such as high-density plasma (HDP) and high aspect ratio process (HARP) can no longer meet the requirements of void-free filling. It is necessary to adopt a new process with stronger filling capacity; the current mainstream Flash manufacturers in the industry all use polysilyl nitrogen (PSZ) as the film layer for STI filling, and then use the furnace tube water vapor annealing (anneal) process to replace nitrogen with oxygen to form silicon dioxide to achieve silicon dioxide filling in shallow trenches; as figure 1 As shown, it is a schematic diagram of furnace tube water vapor annealing for converting PSZ to silicon dio...

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Problems solved by technology

[0004] First of all, the exhaustable gas generated during the replacement process of the PSZ at the bottom of the shallow trench cannot be effectively exhausted;

[0005] Secondly, the loose silicon dioxide film cannot effectively make the silicon dioxide dense at high temperature.

[0006] In the end, the film quality of the formed silicon dioxide will be poor. In the case of relatively poor film quality

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