Reactive ion etching of III-V compounds including InP, GaAs-InP and GaAlAs

DETAILED DESCRIPTION The following describes, in accordance with the present invention, a process for reactive ion etching of GaAs, InP and their derivative ternary and quartenary compounds, GaAlAs and the oxides of GaAs.
The etch gas used is CCl.
sub.
2 F.
sub.
2 alone or in combination with gases chosen from argon (Ar), oxygen (O.
sub.
2) and nitrogen (N.
sub.
2).
The ranges of relative flow rates of Ar, CCl.
sub.
2 F.
sub.
2, O.
sub.
2 and N.
sub.
2 which cover the process are: Ar (0-83%), CCl.
sub.
2 F.
sub.
2 (8-100%), O.
sub.
2 (0-50%), and N.
sub.
2 (0-60%).
We have found that CCl.
sub.
2 F.
sub.
2 supplies the chemically reactive etching species in the gas mixture.
The addition of oxygen promotes the rate of etching, probably by reacting with unsaturated halocarbons to prevent their recombination with the active etching species.
Generally, increasing the O.
sub.
2 content increases the etch rate, provided that the percentage of CCl.
sub.
2 F.
sub.
2 is not overly diluted.
The addition of argon appears to contribute in an active way to the etching process; use of the same amount of He, rather than Ar, all other parameters being equal, results in a reduced etch rate.
However, the etch rate does not appear to be a strong function of the percentage of Ar in the gas mixture.
Keeping the ratio of CCl.
sub.
2 F.
sub.
2 /O.
sub.
2 constant and changing only the relative abundance of that ratio to Ar, we have observed an increase in etch rate with increasing CCl.
sub.
2 F.
sub.
2, for the ratio of CCl.
sub.
2 F.
sub.
2 /Ar=0.
1 to CCl.
sub.
2 F.
sub.
2 /Ar=1.
This reactive ion etching process has been developed using two conventional diode sputtering systems with pyrex chambers.
The first (MRC) is a MRC Corp.
model SEM 8620 and the second (CV) is a Cooke Vacuum Corp.
model C 71-3.
Both systems have a conventional oil diffusion pump and a liquid nitrogen (LN.
sub.
2) cold trap.
In addition, the CV has an optically dense water cooled baffle, which baffle was used for all of the runs on that station.
In both systems, the plasma was generated by a 13