The high-density inductively coupled plasma (ICP) etching technique has been applied to HgCdTe. The HgCdTe etch rate was studied as a function of key process variables commonly used in high-density plasma etching: chamber pressure, direct current (DC) bias, and ICP-source power. Mesa profiles were characterized using scanning electron microscopy (SEM), and the profiles for the process conditions used were found to be compatible with fabrication procedures for HgCdTe infrared focal-plane arrays (FPAs). The etch uniformity was measured to be better than 5% over a diameter of 6-in.

Inductively coupled plasma (ICP) using hydrogen-based gas chemistry has been developed to meet requirements for deep HgCdTe mesa etching and shallow CdTe passivation etching in large format HgCdTe infrared focal plane array (FPA) fabrication. Large format 2048 ϫ 2048, 20-µm unit-cell short wavelength infrared (SWIR) and 2560 ϫ 512, 25-µm unit-cell midwavelength infrared (MWIR) double-layer heterojunction (DLHJ) p-on-n HgCdTe FPAs fabricated using ICP processing exhibit Ͼ99% pixel operability. The HgCdTe FPAs are grown by molecular beam epitaxy (MBE) on Si substrates with suitable buffer layers. Midwavelength infrared detectors fabricated from 4-in. MBE-grown HgCdTe/Si substrates using ICP for mesa delineation and CdTe passivation etching demonstrate measured spectral characteristics, RoA product, and quantum efficiency comparable to detectors fabricated using wet chemical processes. Mechanical samples prepared to examine physical characteristics of ICP reveal plasma with high energy and low ion angle distribution, which is necessary for fine definition, high-aspect ratio mesa etching with accurate replication of photolithographic mask dimensions.