Silicon-germanium film deposition method by adopting LPCVD method

Abstract

The invention discloses a silicon-germanium film deposition method by adopting an LPCVD method. The silicon-germanium film deposition method comprises the following steps of cleaning a substrate firstly, and enabling a SiO<2> layer to be grown on the substrate; next, performing pre-deposition of a noncrystalline silicon seed layer on the SiO<2> layer at a high temperature (425-550 DEG C); and finally, depositing a silicon-germanium material on the noncrystalline silicon seed layer at a low temperature (380-420 DEG C) to form the silicon-germanium film. The silicon-germanium film prepared by the method has a smooth surface.

Description

technical field [0001] The invention relates to the field of semiconductor manufacturing, in particular to a method for depositing a silicon germanium film by LPCVD. Background technique [0002] Polycrystalline silicon germanium film (silicon germanium film for short) is a promising material in MEMS and CMOS device applications, mainly due to its relatively low thermal budget (compared to polysilicon) and good electrical and mechanical properties. [0003] For MEMS applications, there is an increasing tendency to use high specific gravity silicon germanium instead of silicon oxide as the sacrificial layer material (except for some applications that are used as protective layers in HF release processes). [0004] In addition to the application in the MEMS industry, at the same time, silicon germanium films are also widely used in the communication field, and silicon germanium can be seen in every mainstream production chip of telecommunications companies. Applications inclu...

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Problems solved by technology

However, the silicon germanium film deposited by LPCVD either does not deposit an amorphous silicon seed layer at low temperature, and the early deposition rate is very slow; or both the amorphous silicon seed layer and the silicon germanium film are deposited at the same higher temperature, and the grain size is large. very rough surface

[0006] directly on SiO by LPCVD 2 When the silicon germanium film is deposited on the substrate at low temperature, the silicon germanium is not easy to adhere to the SiO2 film at the initial stage. 2 On the substrate, the deposition rate is very low, which is not conducive to the rapid deposition of silicon germanium films in large quantities

However, if the deposition temperature is increased, the silicon germanium film grows rapidly, and the surface of the film is very rough, which forms a contradiction.

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