Low Temperature Deposition of Polycrystalline Silicon Thin Films Prepared by Hot Wire Cell Method

Abstract

Hot wire (HW) cell method has been newly developed and successfully applied to grow polycrystalline silicon films at a low temperature with a relatively high growth rate. In the HWcell method, silane is decomposed by reaction with a heated tungsten wire placed near the substrate. It is found that polycrystalline silicon films can be obtained at substrate temperatures of 175-400°C without hydrogen dilution. The film crystallinity is changed from polycrystalline to amorphous with decreasing the total pressure. The X-ray analysis clearly showed that the films grown at the filament temperature of 1700°C have a very strong (220) preferential orientation. The films consist of large grains as well as small grains, and it was found from cross-sectional SEM that the films have columnar structure. These results suggested that the HW-cell method would be a promising candidate to grow device-grade polycrystalline silicon films for photovoltaic application.

Microcrystalline silicon by plasma enhanced chemical vapor deposition from silicon tetrafluoride

“…A few methods such as hot wire-CVD 42,43 and very high frequency VHF, 44 despite the high H 2 dilution, give deposition rates as high as 5-10 Å/s and 2-9 Å/s, respectively, in the SiH 4 system.…”

“…Here, the data from the present experiments ͑open symbol͒ are compared with many literature data obtained by a wide variety of methods and conditions. In particular, there are data from SiF 4 ͑͒, 21,45 SiH 4 ͑᭹͒, 15,25,43,46,47,48 and SiH 2 Cl 2 ͑᭡͒ 16 systems, which also refers to different techniques: PECVD, 25,46 IDECR-PECVD ͑integrated distributed electron cyclotron resonance͒, 47 ECR-PECVD, 48 LBL-PECVD, 15 and hot wire CVD. 43…”