Study of Inner Spacer Module Process for Gate All Around Field Effect Transistors

Gate-All-Around(GAA) transistor is the most competitive device for the replacement of Fin Field-Effect Transistor (FinFET). Integrating the inner spacer module into process flow of manufacturing GAA devices still faces significant challenges.In this study, dummy gates were included and the most critical processes for inner spacer, such as cavity etching, dielectric material conformal filling and precise etching back process were studied.The inner spacer cavity with a depth of 10.10 nm was achieved using isotropic etching, and dielectric filling was completed by low pressure chemical deposition (LPCVD). Finally, an inner spacer with 9.35 nm thickness is formed after precise etching the dielectric material. Furthermore,to verify the physical isolation of the inner spacer, a selective epitaxy was developed on the Source/Drain region, achieving better process results. This research will provide important references for the industry to manufacture GAA devices, especially inner spacers.