Comparison of optimised conditions for inductively coupled plasma‐reactive ion etching of quartz substrates and its optical applications

Abstract

A C4F8/He inductively coupled plasma-reactive ion etching (ICP-RIE) was studied to improve the etching conditions of quartz glass. The influences of C4F8 flow rate, He flow rate, chamber pressure, inductively coupled plasma (ICP) power, bias power and cooling temperature were investigated. A report is presented on an optimum etching condition for fabricating quartz-based optical components considering their application in diffractive optical element (DOE) devices. As per these etching results, the etched microstructure exhibited a depth of 44.2 μm and a vertical sidewall angle of 89° resulting from an ICP power of 3000 W, a bias power of 200 W, a chamber pressure of 2.5 mTorr and an etching time of 120 min in a mixture of C4F8 and He gases with 30 and 100 sccm flow rates, respectively. The successful fabrication of the DOE component by ICP-RIE is reported. This can be used to provide the uniform light intensity distribution for a DOE device.