Dry etching of Hg1-xCdxTe using CH4/H-2/Ar/N-2 electron cyclotron resonance plasmas

An approach is presented which eliminates the problems caused by hydrocarbon polymer deposition during etching Hg1-xGdxTe with CH4/H-2 based plasmas. We find that the addition of N-2 to the plasma inhibits polymer deposition in the chamber and an the sample. We speculate that atomic nitrogen formed from N, in the plasma has several beneficial effects: the elimination of polymer precursors, the reduction of the atomic hydrogen concentration, and a potential increase of methyl radical concentration. Evidence for the reaction between the nitrogen and the polymer precursors is presented. It is also demonstrated that the addition of N-2 to CH4/H-2 based electron cyclotron resonance (ECR) plasmas used to etch HgCdTe eliminates the roughness normally formed during etching and results in a steadier etch rate.