HgCdTe Surface Cleanup and Etch Using a Remote Hydrogen Plasma

Dry passivation of HgCdTe with ZnS or CdTe using physical or chemical vapor deposition can be improved by incorporating an in situ plasma cleanup of the HgCdTe surface prior to the deposition. Contamination at the HgCdTe/ dielectric interface from ambient oxide and hydrocarbon residues may lead to fixed charge in capacitor or diode device structures. In addition, the oxides of HgCdTe are known to be thermally unstable. Removal of the surface contamination layer is advantageous for producing a consistent and electrically reliable interface. We describe the interaction of a remotely generated H2 or H2/Ar plasma (2.45 GHz, 600W) with HgCdTe, using ex-situ and in-situ ellipsometry, and atomic force microscopy. This work represents the first effort to characterize a low damage HgCdTe surface cleanup process which is compatible with vacuum in-situ passivation.