Method of forming a collar using selective SiGe/Amorphous Si Etch
US6987042B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | May 30, 2003 |
| Grant date | Jan 17, 2006 |
| Priority date | — |
| Expiry date | Jun 6, 2023 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH10D1/665
- WIPO fieldSemiconductors
- WIPO sectorElectrical engineering
Abstract
A method of forming collar isolation for a trench storage memory cell structure is provided in which amorphous Si (a:Si) and silicon germanium (SiGe) are first formed into a trench structure. An etching process that is selective to a:Si as compared to SiGe is employed in defining the regions in which the collar isolation will be formed. The selective etching process employed in the present invention is a wet etch process that includes etching with HF, rinsing, etching with NH4OH, rinsing, and drying with a monohydric alcohol such as isopropanol. The sequence of NH4OH etching and rinsing may be repeated any number of times. The conditions used in the selective etching process of the present invention are capable of etching a:Si at a faster rate than SiGe.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.