Boron doping effects on microcrystalline silicon film roughness studied by spectroscopic ellipsometry

•Real-time and ex-situ spectroscopic ellipsometry was used to characterize Si films.•Surface roughness of intrinsic and boron-doped Si thin films was investigated.•Boron-doped Si film growth process can’t be described by the KPZ model.•Boron doping changed the growth progress of the microcrystalline Si thin films.

Microcrystalline silicon thin films were prepared in the p-type chamber using radio frequency plasma enhanced chemical vapor deposition. The surface roughness evolution of microcrystalline silicon thin films was investigated with spectroscopic ellipsometry (SE). The differences between the real-time SE and ex-situ SE have been studied. The effects of boron doping on the surface roughness have been analyzed using real-time SE. For the intrinsic microcrystalline silicon thin films, with an increase in the deposition time, the surface roughness exhibited the following behavior: (a) quickly increased, (b) gradually increased, (c) slightly increased. In the case of boron-doped microcrystalline silicon thin films, the surface roughness showed different behavior: (a) slightly increased, (b) quickly increased, (c) rapidly dropped, (d) increased again. Based on the KPZ model, the intrinsic silicon thin film growth exponent β is about 0.4, corresponding to limited diffusion model. In contrast, boron-doped silicon thin films behavior cannot be described by the KPZ model. Boron catalysis effects promote the reaction radical BHx aggregation, and result in shadowing. Boron doping changed the film growth process.

Graphical abstractSurface roughness evolution of the microcrystalline silicon thin films before and after boron doping studied with real-time spectroscopic ellipsometry.Figure optionsDownload full-size imageDownload as PowerPoint slide