Insituellipsometry of thin‐film deposition: Implications for amorphous and microcrystalline Si growth
作者:
R. W. Collins,
B. Y. Yang,
期刊:
Journal of Vacuum Science&Technology B: Microelectronics Processing and Phenomena
(AIP Available online 1989)
卷期:
Volume 7,
issue 5
页码: 1155-1164
ISSN:0734-211X
年代: 1989
DOI:10.1116/1.584566
出版商: American Vacuum Society
关键词: SORPTIVE PROPERTIES;MICROSTRUCTURE;ELLIPSOMETRY;THIN FILMS;DEPOSITION;TIME DEPENDENCE;AMORPHOUS SEMICONDUCTORS;CRYSTALLINE STATE;SILICON;NUCLEATION;CHEMICAL VAPOR DEPOSITION;METALS;SILANES;SURFACE PROPERTIES;MOLYBDENUM;CHROMIUM;Si
数据来源: AIP
摘要:
Real‐time ellipsometric characterization of the nucleation of hydrogenated amorphous silicon (a‐Si:H) prepared by plasma‐enhanced chemical vapor deposition (PECVD) on smooth, dense metal, and crystalline Si substrates is reviewed. The experimental results for photoelectronic qualitya‐Si:H from pure SiH4on Mo and Cr are consistent with the Volmer–Weber nucleation mode, with a separation of 40–50 Å between nucleation centers. Forc‐Si substrates, a new interpretation suggests that nucleation occurs on the same scale, but the geometry in the first monolayer is disklike. A well‐defined lobe and cusp in the data can be ascribed to surface smoothening by diffusion that results upon coalescence of these structures. For films from a pure SiH4plasma, the rates of coalescence and relaxation of substrate‐induced surface roughness on thick films are consistent with a diffusion length of ∼80 Å for the adsorbed precursors. For films prepared from a SiH4‐depleted plasma, the average surface diffusion length is reduced by at least a factor of 2. New results for the growth of μc‐Si:H ona‐Si:H films reveal an induction period of several minutes for the nucleation of microcrystallites. During this period a structurally defective 40–80 Å amorphous layer is deposited. Such a layer is expected to influence the properties of photoelectronic devices and compositionally modulated materials that use thin μc‐Si:H.
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