Wafer-grown heat flux sensor arrays for plasma etch processes

This work treats the design, fabrication, and testing of a wafer-grown thermal flux sensor for use in plasma etch processes. This sensor is capable of separately resolving the heating due to ion flux from that due to surface chemical reactions. The sensor is constructed using a modified Gardon gauge structure with an added antenna structure. This addition allows the exposed portion of the gauge to be formed from any plasma etchable material while still retaining the high sensitivity inherent in a Gargon-type heat flux sensor. The fabrication process for the sensor uses standard MEMS process steps, with an XeF₂ postprocess structure release. Bench-top experimental results showing the sensitivity (0.25 μV/W/m²) and repeatibility (8.3 W/m²) are presented and discussed, and preliminary efforts at in situ etch monitoring are discussed.