Optimization of the Deposition Conditions for Epitaxial Silicon Films on Czochralski Sapphire in the Silane‐Hydrogen System

Abstract

The deposition of epitaxial silicon films on (1̅012) Czochralski sapphire from the silane/hydrogen system was investigated for growth temperatures from 880° to 980°C and for growth rates from 0.2 to 6.0 μm/min. The film quality was evaluated by optical absorption measurements. The temperature range, in which epitaxial film quality was obtained, shifts with increasing growth rates to higher deposition temperatures. This epitaxial temperature range is rather broad, e.g., 915°–965°C for 0.2–0.5 μm/min and 935°–985°C for 5.3–6.0 μm/min. A region for the optimum epitaxial deposition conditions, very suitable for MOS applications, is defined by the minimum values obtained from the optical absorption measurements. At temperatures below 915°C, decreasing crystalline quality was observed due to an increasing fraction of polycrystalline silicon. In addition the influence of the H2O content on the crystalline quality of the silicon films was investigated; for the production of a good epitaxial silicon film the H2O impurity fraction must be smaller than 1 ppm, especially in the low temperature region.

Electron Microscope Study Of Microtwins In Epitaxial Silicon Films On Sapphire

“…Contrast analysis of the microtwins shows that most of them are not 3N-layer twins but contain a stacking fault. EXPERIMENTAL Silicon on Sapphire (SOS) films grown by CVD (Chemical Vapour Deposition) of SiH4 in Hz at temperatures of 1273 K with a deposition rate of 3 p m min-l were investigated by TEM, to characterize the crystal defects present near the interface of the heteroepitaxial (OOl)~i/(T012)~,, (ZZO)si11(01i2)sa system (Cullen, 1971;Druminski, 1976). Ion beam thinning from the sapphire side was used to get transparent foils for a 200 kV electron microscope.…”