I did SiO2 dry etching using CHF3 (100 W RIE power, 10 mT pressure, 20 sccm CHF3 flow) at 20C. After the etch process, I noticed cracks/peeling off in multiple places of my sample (image attached). The sample has GaSb on top and AlInAsSb and AlInSb on subsequent layers with varying percentage of Aluminum. If anybody experienced this or have some idea why this might happen, I will appreciate. Thanks
If you have an epitaxial layer system, there may be stress between the layers. If you give the system the option to relax, which heating and etching both can do, peeling and cracking are phenomena associated to that.
Either the sample quality needs to be improved by developing stress reduction, which can mean months or even years of work, or the etching process needs to get cooler and softer.
In my opinion you have corrosion of the SiO2 layer. Use 20 W RF power, 1 mTorr, 10 minutes etch time, then look at the sample with the (simple) metalographic microscope, then other 10 minutes etch time etc.
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