Reduction of Sidewall Roughness During Dry Etching of SiO 2
- PDF / 2,445,883 Bytes
- 7 Pages / 420.48 x 639 pts Page_size
- 54 Downloads / 219 Views
Reduction of Sidewall Roughness During Dry Etching of SiO 2
F. Ren, S. J. Pearton, J. R. Lothian, C. R. Abernathy, and W. S. Hobson, AT&T Bell Laboratories, Murray Hill, NJ 07974
The appearance of striations on dry etched semiconductor laser mesas is a common feature of these structures. We describe a number of different methods of reducing the extent of this roughness, including the choice of dielectric etch chemistry, modification of the initial resist processing and deposition of a SiN sidewall to prevent additional roughening during the plasma etch step. SF 6 is found to be preferable to CF4 for dielectric etching because of an absence of polymer formation. This produces smoother SiO 2 sidewalls. Flood exposure of the initial photoresist mask and optimization of the postbake temperature also produces smoother sidewalls on the subsequently etched Si0 2 . The sidewall can also be protected from roughening that occurs during the dry etch step by coating it with a low temperature SiN layer. A combigation of all of these methods produces sidewalls with morphological variations of
Data Loading...
