Inner spacer engineering to improve mechanical stability in channel-release process of nanosheet FETs

Abstract

Mechanical stress is demonstrated in the fabrication process of nanosheet FETs. In particular, unwanted mechanical instability stemming from gravity during channel-release is covered in detail by aid of 3-D simulations. The simulation results show the physical weakness of suspended nanosheets and the impact of nanosheet thickness. Inner spacer engineering based on geometry and elastic property are suggested for better mechanical stability. The formation of wide contact area between inner spacer and nanosheet, as well as applying rigid spacer dielectric material, are preferred.