Atomic-layer selective deposition of silicon nitride on hydrogen-terminated Si surfaces

Atomic layer selective deposition of silicon nitride films on the hydrogen-terminated Si surface has been investigated. The film is deposited by alternate supply of SiH2Cl2, and NH3 dissociated by thermal catalytic reaction on a tungsten filament. Thin -4 nm.silicon nitride films can be selectively grown on a hydrogen-terminated Si surface. However, no film growth takes place on thermal chemically-vapor-deposited CVD.silicon nitride in the initial ;30 deposition cycles. The mechanism of the selective deposition is studied by means of Fourier transform infrared attenuated total reflection FT-IR-ATR.spectroscopy. It is shown that the film growth takes place only on the surface with Si–H xs1;3.bonds, x because the first nitridation by NH3 exposure occurs only at the surface with Si–Hxbonds. Once the surface N–Hy ys1 or 2. bonds are formed, the SiH2Cl2 molecules react with the N–Hy bonds and the film growth starts to take place. On the other hand, no film growth takes place on the thermal CVD silicon nitride since there are no Si–H and N–H bonds on the x y surface. By using the thermal catalytic method, the film quality is improved in comparison with films deposited by using NH3 plasma. q1998 Elsevier Science B.V. All rights reserved.