Method for improving polycrystalline silicon cracks in SGT process

Abstract

The invention provides a method for improving polycrystalline silicon cracks in an SGT process. The method comprises gate polycrystalline silicon and first oxide layers located on the two sides of thegate polycrystalline silicon, wherein the upper surfaces of the first oxide layers are higher than the gate polycrystalline silicon. The method comprises the following steps of etching a first oxidelayer structure along the side wall of each first oxide layer till that the head of the gate polycrystalline silicon is exposed so that the opening of each first oxide layer is inverted trapezoidal; forming a second oxide layer covering the head of the gate gate polycrystalline silicon to enable the normal section of the head of the gate polycrystalline silicon to form a regular trapezoid; etchingthe first oxide layer and the second oxide layer till that the head of the gate polycrystalline silicon with the regular trapezoidal section structure is exposed; forming a gate oxide layer on the exposed head of the gate polycrystalline silicon, and then depositing a polycrystalline silicon layer covering the gate oxide layer; and etching back the polycrystalline silicon layer till that the gateoxide layer at the head of the gate polycrystalline silicon is exposed. According to the invention, the morphology of the sharp corner of the head of the gate polycrystalline silicon is improved by adding a thermal oxidation process so that the crack phenomenon caused by filling polycrystalline silicon between the gate polycrystalline silicon subsequently is eliminated, and the product yield is improved.

Description

technical field [0001] The invention relates to the technical field of semiconductors, in particular to a method for improving polysilicon cracks in the SGT process. Background technique [0002] In the screen gate trench process (SGT), due to the special shape of the polysilicon corner, the polysilicon filling is prematurely closed, forming an obvious seam (Seam), such as figure 1 as shown, figure 1 Electron microscope image showing cracks in polysilicon in a conventional SGT. The existence of such cracks leads to easy cracking in subsequent processes, which affects the yield and reliability of products. [0003] Therefore, it is necessary to propose a new method to solve the above problems. Contents of the invention [0004] In view of the shortcomings of the prior art described above, the purpose of the present invention is to provide a method for improving polysilicon cracks in the SGT process, which is used to solve the problem of cracks in polysilicon in the SGT p...

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Problems solved by technology

[0004] In view of the shortcomings of the prior art described above, the purpose of the present invention is to provide a method for improving polysilicon cracks in the SGT process, which is used to solve the problem of cracks in polysilicon in the SGT process in the prior art and thus affect product yield and reliability The problem

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