Fabrication of resonator–quantum well infrared photodetector focal plane array by inductively coupled plasma etching

Jason Sun,Kwong-Kit Choi

doi:10.1117/1.oe.55.2.026119

Abstract

Inductively coupled plasma (ICP) etching has distinct advantages over reactive ion etching in that the etching rates are considerably higher, the uniformity is much better, and the sidewalls of the etched material are highly anisotropic due to the higher plasma density and lower operating pressure. Therefore, ICP etching is a promising process for pattern transfer required during microelectronic and optoelectronic fabrication. Resonator-quantum well infrared photodetectors (R-QWIPs) are the next generation of QWIP detectors that use resonances to increase the quantum efficiency (QE). To fabricate R-QWIP focal plane arrays (FPAs), two optimized ICP etching processes are developed. Using these etching techniques, we have fabricated R-QWIP FPAs of several different formats and pixel sizes with the required dimensions and completely removed the substrates of the FPAs. Their QE spectra were tested to be 30 to 40%. The operability and spectral non- uniformity of the FPA is ∼99.5 and 3%, respectively. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI. (DOI: 10

Highlights

Coupled plasma (ICP) etching is a promising dry etching process. It is widely used in semiconductor manufacturing due to the high ion density and low operating pressure, which can yield high etching rates and better etching uniformity across the wafers
Ion density is controlled by Inductively coupled plasma (ICP) source power alone
Since an ICP system provides one more process parameter than a reactive ion etching system for plasma control, it is more flexible in etching processes optimization, such as selective versus nonselective etching; isotropic versus vertical etching; and low or no plasma damage etching processes.[1,2,3,4]

Summary

Introduction

Coupled plasma (ICP) etching is a promising dry etching process. It is widely used in semiconductor manufacturing due to the high ion density and low operating pressure, which can yield high etching rates and better etching uniformity across the wafers. We applied two optimized ICP etching processes (selective and nonselective) to fabricate test detectors and the first R-QWIP focal plane array (FPA).[9,10,11,12] The selective etching process could yield a very high selectivity of etching GaAs over Al0.4Ga0.6As We optimized the gases ratio, RF and ICP powers, and operating pressure to yield a highly anisotropic etching profile (88 deg), high etching rate (5400 Å∕ min), and ion damage free process.

Results

Conclusion