Forming process of shallow channel

Abstract

The invention provides a method for forming a trench structure, at least comprising: forming a pad oxide layer on a substrate; forming a first polysilicon layer on the pad oxide layer; forming an oxide layer on the first polysilicon layer forming a second polysilicon layer on the oxide layer; removing part of the second polysilicon layer, the oxide layer, the first polysilicon layer and the pad oxide layer to expose part of the substrate; and etching the second polysilicon layer The silicon layer and part of the substrate form a trench structure in the substrate and expose the oxide layer. The etch depth of the trench structure is well controlled by the etched thickness of the second polysilicon layer.

Description

technical field [0001] The invention relates to a method for forming shallow trenches, in particular to a method for forming shallow trenches that can reduce micro-loading and corner recesses during shallow trench formation. Background technique [0002] The disadvantage of traditional area oxide isolation devices is that they are prone to defect formation due to the high stress generated in the narrow active region under the nitride layer during field oxidation; secondly, defects are also easily generated due to the Kooi effect. When the geometric size gradually shrinks, the bird’s beak encroachment occupies most of the oxygen surface area of ​​the field, which is more likely to lead to the formation of defects. Therefore, when isolating semiconductor elements below 0.35 microns, it is very important to overcome the shortcomings of traditional methods to form good isolation regions. [0003] It is a practice to use shallow-trench isolation techniques to isolate components ...

AI Technical Summary

Problems solved by technology

[0004] Unfortunately, for highly integrated circuits, when etching shallow trench structures, there will be microloading; such time-mode etching makes it difficult to control the depth of shallow trench structures

The problem of corner dishing can also lead to the degradation of STI after STI formation

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