Polysilicon thin film process
US4897360A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 9, 1987 |
| Grant date | Jan 30, 1990 |
| Priority date | — |
| Expiry date | Dec 9, 2007 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S438/977
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
Polycrystalline silicon is deposited in a film onto the surface of a substrate which has been carefully prepared to eliminate any defects or contaminants which could nucleate crystal growth on the substrate. The deposition is carried out by low pressure decomposition of silane at substantially 580.degree. C. to cause a film of fine grained crystals of polysilicon to be formed having grain sizes averaging less than about 300 Angstroms after annealing. Such a film is very uniform and smooth, having a surface roughness less than about 100 Angstroms RMS. Annealing of the film and substrate at a low temperature results in a compressive strain in the field that decreases over the annealing time, annealing at high temperatures (e.g., over 1050.degree. C.) yields substantially zero strain in the film, and annealing at intermediate temperatures (e.g., 650.degree. C. to 950.degree. C.) yields tensile strain at varying strain levels depending on the annealing temperature and time. Further processing of the polysilicon films and the substrate can yield isolated diaphragms of the polysilicon film which are supported only at edges by the substrate and which have substantial lateral dimensions, e…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.