Method for etching a trench having rounded top and bottom corners in a silicon substrate
US6235643A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 10, 1999 |
| Grant date | May 22, 2001 |
| Priority date | — |
| Expiry date | Aug 10, 2019 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01L21/3081
- WIPO fieldSemiconductors
- WIPO sectorElectrical engineering
Abstract
The present invention provides straight forward methods for plasma etching a trench having rounded top corners, or rounded bottom corners, or both in a silicon substrate. A first method for creating a rounded top corner on the etched silicon trench comprises etching both an overlying silicon oxide layer and an upper portion of the silicon substrate during a "break-through" step which immediately precedes the step in which the silicon trench is etched. The plasma feed gas for the break-through step comprises carbon and fluorine. In this method, the photoresist layer used to pattern the etch stack is preferably not removed prior to the break-through etching step. Subsequent to the break-through step, a trench is etched to a desired depth in the silicon substrate using a different plasma feed gas composition. A second method for creating a rounded top corner on the etched silicon trench comprises formation of a built-up extension on the sidewall of an overlying patterned silicon nitride hard mask during etch (break-through) of a silicon oxide adhesion layer which lies between the hard mask and a silicone substrate. The built-up extension upon the silicon nitride sidewall acts as a sac…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.