ISSN:
0001-1541
Keywords:
Chemistry
;
Chemical Engineering
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Process Engineering, Biotechnology, Nutrition Technology
Notes:
Uniformity and predictability are the principal qualities sought for all wet chemical etches. The establishment of these qualities, however, is hindered by a number of factors, such as nonuniformities in the starting material and random fluctuations in the local temperature and reactant concentration, which can lead to variations in etch rate across the surface of a wafer. The effects of variations in the local etch rate on the morphological development of an etching surface and on the overall etch rate of the semiconductor are discussed. The system studied was an Al0.4Ga0.6As/GaAs heterostructure photodissolved in nitric acid using 730-nm laser light. Defects in the AlGaAs layer, which etched faster than the surrounding material, were responsible for variations in the etch rate. The defects also exhibited a degree of photosensitivity that has not been previously observed. It was also found that not all of the defects spanned the AlGaAs epilayer. A model for the overall etch rate was based on a system of noninteracting cylindrical defects with a distribution in depths.
Additional Material:
7 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/aic.690420816
