Two step oxide removal for memory cells
US6174817A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 26, 1998 |
| Grant date | Jan 16, 2001 |
| Priority date | — |
| Expiry date | Aug 26, 2018 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH10B12/315
- WIPO fieldSemiconductors
- WIPO sectorElectrical engineering
Abstract
Hydrofluoric acid (HF) mixed with water and often buffered with ammonium fluoride is a standard silicon dioxide wet etchant which is followed by a rinse. An improved silicon dioxide etch is vapor HF which may be followed by a water vapor rinse. The invention discloses a further improved silicon dioxide etch. Following an initial exposure to vapor HF for oxide removal, a first insitu water rinse occurs. A second exposure to vapor HF then occurs and is followed by a second insitu water rinse. Water, rather than water vapor, aids in freeing particles from the wafer surface. During both the water rinses, the wafer may be rotated at increasing speeds to aid in sweeping particles from wafer surface. The process may be practiced in a commercially available reactor and is suitable for ULSI devices having complex topographies, such as, for example, 64 megabit DRAMs employing crown type memory cells.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.