Comparison of Dry and Wet Etch Processes for Patterning SiO[sub 2]/TiO[sub 2] Distributed Bragg Reflectors for Vertical-Cavity Surface-Emitting Lasers

A dry etch process for patterning distributed Bragg reflectors (DBRs) for vertical-cavity surface-emitting lasers was demonstrated. The etching was conducted using an inductively coupled plasma (ICP) system. Both and based etching chemistries were investigated. Very slow etch rates were obtained for when using a chemistry due to the low volatility of the etch products, Using an based chemistry, similar etch rates for and were obtained, which is desired for etching through the alternating and layers of the DBR. An average etch rate of 1200 Å/min was achieved at ICP and radio frequency (rf) powers of 500 and 250W, respectively. Wet chemical etch processing was also explored using a buffered oxide etchant (BOE) and diluted HF. Etch rates of ∼2050Å/min and ∼2.7 μm/min were obtained for BOE and (1:3), respectively. However, a significant etch-undercut of the DBR structure and delamination at the interfaces, due to internal stress created between these layers, were observed when these wet etchants were used. © 2001 The Electrochemical Society. All rights reserved.