Technique for forming gapless shallow channel insulation area by subatmospheric CVD method

Abstract

The invention discloses a trench insulation area process, firstly forming an isolation trench in a semiconductor substrate; making SACVD (selected area chemical vapor deposition) to deposit a silicon oxide layer on the semiconductor substrate and making the silicon oxide fill the isolation trench, where the silicon oxide layer forms a joint in the isolation trench; making a low-temperature vapor annealing process to eliminate the joint in hydrogen / oxygen gas; and finally making a high temperature annealing process to compact the silicon oxide layer in inert gas with a temperature higher than 900 deg.C.

Description

technical field [0001] The present invention relates to the manufacture of semiconductor integrated circuits, in particular to a process for forming a seamless shallow trench isolation region by using sub-atmospheric pressure chemical vapor deposition (SACVD) technology. Background technique [0002] In recent years, with the continuous shrinking of the design line width of the semiconductor process, the trench isolation or shallow trench isolation (STI) process, which is implemented on the surface of the semiconductor substrate and used to effectively isolate the device electrically, has become more and more important. It is an increasingly important topic, and how to effectively fill the increasingly narrow insulation trenches has become a major challenge in this technical field. [0003] The traditional shallow trench isolation process is to first use the chemical vapor deposition (chemical vapor deposition, CVD) method to fill the dielectric layer in the insulating trenc...

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Problems solved by technology

[0005] However, the aforementioned ozone-assisted subatmospheric pressure chemical vapor deposition technology still has many shortcomings in practical application and needs to be further overcome and improved.

The silicon-oxygen film deposited by the existing ozone-assisted sub-atmospheric pressure chemical vapor deposition technology itself will shrink at high temperature, for example, after 30 minutes at 1050 ° C, the shrinkage will be as high as about 7%, and the SACVD silicon-oxygen film Thin films also have poorer properties, e.g. faster wet etch rates

In addition, if figure 1 As shown, another more serious problem of the ozone-assisted sub-atmospheric pressure chemical vapor deposition technology is that the growth characteristic of the sub-atmospheric pressure chemical vapor deposition film is mainly from the sidewall 22 of the ditch 20 to the middle to fill the ditch, therefore, eventually will A tight seam (seam) 50 is formed in the middle of the trench 20 of the substrate 10, and the seam defect 50 cannot be removed by conventional nitrogen environment annealing, and is easily corroded by subsequent cleaning steps, resulting in the formation of communication trenches and Polysilicon line short circuit and other problems

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