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Etching of GaAs (100) with gaseous H/CH 3 mixtures
Author(s) -
Meharg Paul F. A.,
Ogryzlo Elmer A.
Publication year - 1994
Publication title -
international journal of chemical kinetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.341
H-Index - 68
eISSN - 1097-4601
pISSN - 0538-8066
DOI - 10.1002/kin.550260113
Subject(s) - chemistry , radical , hydrogen , methyl radical , hydrogen atom , arrhenius equation , activation energy , analytical chemistry (journal) , etching (microfabrication) , isothermal process , substrate (aquarium) , methane , hydrogen atom abstraction , organic chemistry , thermodynamics , layer (electronics) , geology , alkyl , physics , oceanography
GaAs (100) wafers were etched in mixtures of hydrogen atoms and methyl radicals. The atoms were formed in a remote hydrogen plasma, and a fraction of these were converted into methyl radicals by introducing methane into the flow system upstream from the semiconductor surface. The flux of hydrogen atoms into the reaction chamber was determined by isothermal calorimetry. The methyl radical flux passing over the substrate was then calculated using previously determined rate parameters for the reaction between atomic hydrogen and methane, and a simple modeling program. The GaAs etch rates were about an order of magnitude faster when methyl radicals were present in the hydrogen atom stream, and were found to follow a first‐order dependence on the partial pressure of methyl radicals. Absolute rate constants were determined and an Arrhenius activation energy of 1.2 kcal mol −1 was calculated. The values of k and E a are consistent with a diffusion‐controlled process. SEM photographs of the surface revealed small crystallographic features that made the surface appear very rough. XPS analysis indicated that these surfaces were arsenic deficient. A mechanism is proposed for the etching of GaAs by a combination of methyl radicals and hydrogen atoms. © 1994 John Wiley & Sons, Inc.