Means for stabilizing polycrystalline semiconductor layers
US4755865A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 9, 1987 |
| Grant date | Jul 5, 1988 |
| Priority date | — |
| Expiry date | Apr 9, 2007 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01L21/32155
- WIPO fieldSemiconductors
- WIPO sectorElectrical engineering
Abstract
Implantation of oxygen or nitrogen in polysilicon layers to a dose above about 10.sup.15 ions/cm.sup.2 retards rapid grain boundary migration of conventional dopants such as B, P, As, Sb, and the like during dopant activation. Pre-annealing of the poly films to increase the grain size also decreases rapid grain boundary migration. The effects can be combined by first pre-annealing and then implanting oxygen or nitrogen before introducing the dopant. It is desirable to anneal the oxygen implant before introducing the dopant to allow for oxygen diffusion to the grain surfaces where it precipitates and blocks the grain boundaries. Vertical and lateral migration of the dopants can be inhibited by placing the implanted oxygen or nitrogen between the dopant and the location desired to be kept comparatively free of dopants. When very high dopant activation temperatures are used the blocking effect of the oxygen on the grain boundaries is overwhelmed by dopant diffusion through the grains.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.