Effect of Inductively Coupled Electromagnetic Field on Bottom Oxide Etch in a High Aspect Ratio Trench

Abstract

CMOS optical sensors devices are becoming increasingly important and popular for many different applications. Some of these devices are fabricated starting from SOI (Silicon On Insulator) wafers and using semiconductor manufacturing techniques. A common feature of the CMOS sensors is the isolating trench that protects the device from electrical noise. We report on the multistep etch process development to fabricate trenches deeper than usual, in order to isolate the sensor also from stray light interference. We focus the attention on unexpected features that originated during the Buried Oxide (BOX) etch.