Polycrystalline silicon thin film forming method and semiconductor structure forming method

Abstract

The invention provides a polycrystalline silicon thin film forming method and a semiconductor structure forming method. The polycrystalline silicon thin film forming method is applied to the field ofsemiconductors. The method comprises the steps of providing a semiconductor substrate and forming a first polycrystalline silicon layer on the semiconductor substrate; and forming a carbon-doped second polycrystalline silicon layer on the first polycrystalline silicon layer, wherein the second polycrystalline silicon layer and the first polycrystalline silicon layer form a required polycrystallinesilicon thin film. According to the embodiment of the invention, on the basis of keeping the material structure of the polycrystalline silicon thin film in the semiconductor structure unchanged, thepolycrystalline silicon thin film is changed into a two-layer structure from a one-layer structure in the prior art, and the top layer is the doped polycrystalline silicon layer containing carbon ions. Due to the fact that the polycrystalline silicon layer doped with the carbon ions has inhibiting and refining effects on the surface of the polycrystalline silicon thin film, the abnormal surface nucleation of the polycrystalline silicon thin film is inhibited, and the probability that abnormally-growing large crystal grains are generated on the surface of the polycrystalline silicon thin film is reduced.

Description

technical field [0001] The invention relates to the technical field of semiconductor manufacturing, in particular to a method for forming a polysilicon thin film and a method for forming a semiconductor structure. Background technique [0002] FLASH (flash memory) devices are generally divided into two types according to their structures: stacked gate devices and split gate devices. A stacked gate device generally includes a floating gate and a control gate, wherein the floating gate is located between the control gate and the substrate and is in a floating state for storing data; the control gate is connected to a word line and is used for controlling the floating gate. [0003] A tunnel oxide layer is also included between the floating gate and the substrate, and an isolated inter-gate dielectric layer is also included between the floating gate layer (doped with phosphorus) and the control gate layer. Each flash memory cell is isolated by a shallow trench isolation (STI) ...

AI Technical Summary

Problems solved by technology

[0006] The purpose of the present invention is to provide a method for forming a polysilicon film to solve the problem of abnormal nucleation on the surface of a polysilicon film in the prior art, resulting in abnormally grown large crystal grains

Images