Method of preventing hillock formation in polysilicon layer by oxygen implanation
US4740481A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 21, 1986 |
| Grant date | Apr 26, 1988 |
| Priority date | — |
| Expiry date | Jan 21, 2006 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S438/937
- WIPO fieldSemiconductors
- WIPO sectorElectrical engineering
Abstract
Hillock formation as a result of heating uncapped polycrystalline silicon layers can be avoided by first implanting the uncapped poly layers with silicon, oxygen, or nitrogen prior to heating. Equivalent mono-atomic oxygen or nitrogen doses in the range of about 10.sup.15 to about 5.times.10.sup.16 ions/cm.sup.2 at energies in the range 10-50 keV are useful with good results being obtained with equivalent oxygen doses of 2.times.10.sup.15 ions/cm.sup.2 at 30 keV. When polysilicon layers with this oxygen implant are heated to about 1150 degrees C., a temperature which would ordinarily produce pronounced hillock formation in un-capped, un-treated poly layers, it is found that hillock formation is suppressed. The implanted oxygen concentrations are far below what is required to produce a separate oxide layer or phase. Some effect on poly layer sheet resistance is observed for implanted oxygen but the implanted layers have sheet resistances within a factor of two of those without the oxygen implants.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.