NANOMETER FABRICATION IN MERCURY CADMIUM TELLURIDE BY ELECTRON-CYCLOTRON-RESONANCE MICROWAVE PLASMA REACTIVE ION ETCHING

It has been recently reported (J.R. Meyer, F.J. Bartoli, C.A. Hoffman, and L.R. Ram-Mohan, Phys. Rev. Lett. 64, 1963 [1990]) that novel electronic and optical effects are anticipated in nanometer scale features of narrow band gap semiconductors such as mercury cadmium telluride (MCT). These efforts could lead to the creation of non-linear optical switches, high efficiency infrared lasers, and unique nanoelectronic devices. This work reports on the first realization of MCT nanostructures through the application of e-beam lithography and reactive ion etching with an electron cyclotron resonance (ECR) microwave plasma source. It is shown that the low energy ions produced by an ECR system can etch MCT with good selectivity over an e-beam resist mask and with high resolution. Using these fabrication methods, 40-70 nm features with aspect ratios of 3-5:1 and sidewall angles greater than 88-degrees have been demonstrated. Qualitative investigations of some of the etch mechanisms of this technique are made, and results suggest a desorption limited process.