PHOTOSENSITIVE GAS PHASE ETCHING OF SEMICONDUCTORS BY SELECTIVE RADIATION
The equipment and process is described for selectively etching a diffusion resistant overlayer for leaving a diffusion-resistant mask of prescribed configuration suitable for monitoring a subsequent diffusion of impurities into a semiconductor substrate. The process is based on the discovery that a radiation pattern incident upon a surface disposed in a particular gaseous ambient including gases such as NF/sub 3/ and Br/sub 2/ can be made to stimulate etching only in the shadowed areas of the surface. In one specific application of the process NF/sub 3/ is bubbled through liquid bromine at room temperature and atmospheric pressure and the resulting gaseous mixture is introduced at normal operating temperatures to an inert enclosure equipped with a window that is transparent to radiation of suitable wavelengths. A silicon semiconductor wafer coated with an overlayer of thermally grown silicon dioxide is disposed in the enclosure and a mask is placed in contact with the wafer appropriately disposed with respect to a suitable radiation source so that the mask shadows the portion of the coating desired to be removed and thereafter the assembly is irradiated by the source. This results in selective etching only of the shadowed portions of the oxide coating. (P.C.H.)
- Research Organization:
- Originating Research Org. not identified
- NSA Number:
- NSA-17-029277
- Assignee:
- Bell Telephone Labs., Inc.
- Patent Number(s):
- US 3095341
- OSTI ID:
- 4712391
- Country of Publication:
- United States
- Language:
- English
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