Electron mobility enhancement in strained-Si n-MOSFETs fabricated on SiGe-on-insulator (SGOI) substrates

We demonstrate electron mobility enhancement in strained-Si n-MOSFETs fabricated on relaxed Si1-xGex-on-insulator (SGOI) substrates with a high Ge content of 25%, The substrates were fabricated by wafer bonding and etch-back utilizing a 20% Ge layer as an etch stop. Epitaxial regrowth was used to produce the upper portion of the Si0.75Ge0.25 and the surface strained Si layer. Large-area strained-Si n-MOSFETs were fabricated on this SGOI substrate. The measured electron mobility shows significant enhancement over both the universal mobility and that of co-processed bulk-Si MOSFETs. This SGOI process has a low thermal budget and thus is compatible with a wide range of Ge contents in Si1-xGex layer.