Oxide etch barrier formed by nitridation
US6100160A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Feb 17, 1998 |
| Grant date | Aug 8, 2000 |
| Priority date | — |
| Expiry date | Feb 17, 2018 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01L21/76224
- WIPO fieldSemiconductors
- WIPO sectorElectrical engineering
Abstract
A structure and method for slowing down the etch rate of CVD oxide film 230 relative to the etch rate of thermal oxide 210 to prevent excessive removal of CVD oxide 230 during the stripping of the thermal oxide 210. Nitridation has been shown to be effective at retarding the etch rate of oxides. Therefore, nitridation of the CVD oxide 230 decreases the amount of oxide loss when thermal oxide 210 is etched. Nitridation of the wafer surface can be performed either before or after the nitride 200 removal step in standard process flows. In processes that use a densified CVD oxide 230, the densification of the CVD film 230 can be performed in an ambient that incorporates nitrogen in the film to significantly decrease the etch rate of the isolation oxide 230. Due to the porosity and the increased hydrogen content of the CVD oxide 230 as compared to the hydrogen content of thermal oxide 210, the nitrogen is incorporated more rapidly in the CVD oxide 230 than in the exposed thermal oxide 210. Therefore, the etch rate of the CVD 230 relative to the thermal oxide 210 (e.g. the selectivity) can approach one or even less than one.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.