Solid-phase epitaxy of amorphous silicon films by in situ postannealing using RPCVD

Solid-phase epitaxy (SPE) of in situ As-doped amorphous Si (a-Si) deposited on SiO2/Si3N4 patterned Si (1 0 0) wafers by reduced pressure chemical vapour deposition (RPCVD) using a H2–Si2H6 gas system was investigated. The SPE was performed by applying in situ postannealing directly after deposition process. On the one hand, we studied the lateral SPE (L-SPE) length of As-doped Si on mask and their crystal quality by TEM/SEM characterisation for various postannealing temperatures (700–1000 °C for 60 s). We observed increase in L-SPE growth and decrease of dislocation density for higher postannealing temperatures. On the other hand, L-SPE length was also investigated for different postannealing times (0–120 min at 575 °C) and As concentrations. At these conditions the L-SPE length has increased with increasing postannealing time. For both, higher and lower annealing temperature region, crystallization has been inhibited for higher As concentrations. After modifying As-doping level, we were able to crystallize up to 500 nm of a-Si on mask to epi-Si by combination of 575 °C and 1000 °C postannealing.

Graphical abstractLateral length of crystallized epi-Si from amorphous Si on Si3N4/SiO2 mask by Solid-phase epitaxy (SPE) is investigated. 500 nm of crystallized epi-Si domain on the mask is formed by 575 °C postannealing. The defects in the crystallized epi-Si are reduced by following 1000°C annealing.Figure optionsDownload full-size imageDownload as PowerPoint slideResearch highlights► Solid-phase epitaxy (SPE) of amorphous Si on patterned Si(001) by RPCVD was studied. ► Lateral SPE length grew with increasing postannealing temperature. ► Lateral SPE length grew with increasing postannealing time and saturates after 1 h. ► ∼500 nm of amorphous Si on mask was crystallized to epitaxial Si (epi-Si) at 575°C. ► By 2nd postannealing at 1000°C, defects in crystalized epi-Si is drastically reduced.