Low-temperature silicon homoepitaxy by ultrahigh vacuum electron cyclotron resonance chemical vapor deposition

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Abstract
High quality silicon homoepitaxial layers are successfully grown at 560 °C by ultrahigh vacuum electron cyclotron resonance chemical vapor deposition (UHV‐ECRCVD) using a SiH4/H2 plasma. The effects of substrate dc bias on the in situ hydrogen plasma clean and the subsequent silicon epitaxial growth are examined by the reflection high‐energy electron diffraction (RHEED), secondary ion mass spectroscopy (SIMS), and cross‐section transmission electron microscopy (XTEM). It is observed that the substrate dc bias plays a significant role in obtaining a damage‐free, clean Si substrate prior to epitaxial growth. Severe damage in the Si surface is observed by XTEM, though RHEED shows a streaky pattern, when the substrate is electrically floating, but the damage can be suppressed with +10 V dc bias to the substrate. Substrate dc bias during plasma deposition drastically changes the crystal structure from polycrystalline at −50 V to high quality epitaxial silicon at substrate biases greater than +50 V. Precise control of the ion energy during in situ cleaning and plasma deposition is very important in low‐temperature Si epitaxy by UHV‐ECRCVD and it is possible by proper control of the substrate dc bias.