Ultra Low-Temperature Epitaxial Growth of Strained Si Directly on Si Substrates

Abstract

We present a unique ultra low-temperature plasma enhanced chemical vapor deposition process that enables epitaxial growth of compressively strained silicon directly on silicon substrates. The epitaxial layers were structurally examined using high-resolution x-ray diffraction, transmission electron microscopy and secondary ion-mass spectroscopy. The results indicate that the compressive strain of the epitaxial layers stems from the hydrogen incorporation during the growth. In addition, we study the effect of phosphine gas flow on the phosphorus doping incorporation in the epitaxial films at low temperatures. Utilizing our epitaxial process, we demonstrate that heavily phosphorus-doped compressively strained Si films with an active doping concentration of ~2×10^20cm^-3 can be achieved at 150C.