AVS 46th International Symposium
    Electronic Materials and Processing Division Thursday Sessions
       Session EM2-ThM

Paper EM2-ThM8
Advanced Selective Dry Etching of GaAs/AlGaAs in High Density Inductively Coupled Plasmas

Thursday, October 28, 1999, 10:40 am, Room 612

Session: Dielectric Passivation/Oxides on Compound Semiconductors
Presenter: J.W. Lee, Plasma-Therm, Inc.
Authors: J.W. Lee, Plasma-Therm, Inc.
M.W. Devre, Plasma-Therm, Inc.
B.H. Reelfs, Plasma-Therm, Inc.
D.J. Johnson, Plasma-Therm, Inc.
J.N. Sasserath, Plasma-Therm, Inc.
F. Clayton, Motorola, Inc.
S.J. Pearton, University of Florida
Correspondent: Click to Email
We report a breakthrough for selective etching of GaAs over Al@sub X@Ga@sub 1-X@As, x = 0.2, etching with a high density plasma source. This results is particularly important for III-V devices such as HBTs or HEMTs. For example, fabrication of HBTs requires a process for selective etching of a GaAs contact layer while stopping on AlGaAs layer. Inductively coupled plasma (ICP) etching with BCl@sub 3@/SF@sub 6@/N@sub 2@/He chemistries showed extremely high selectivity of GaAs over AlGaAs (> 200 : 1) and a photoresist (> 10 : 1). This process also produced excellent sidewall passivation on GaAs with reasonablely high rate ( > 1500 Å/min.). Both SEM and AFM data showed AlGaAs etch stop layer was quite smooth after processing. We found that He played a key role in enhancing selectivity and obtaining smooth AlGaAs surfaces. When used with resist masks, addition of N@sub 2@ into BCl@sub 3@/SF@sub 6@ plasma helped formation of passivation on the sidewall and maintained high anisotropy. An optimized condition with BCl@sub 3@/SF@sub 6@/N@sub 2@/He ICP plasmas showed excellent pattern transfer into GaAs with high rate, anisotropy and selectivity.