Silicon katarometer with the BSC-type contacts

Abstract

Thermal conductivity detector (TCD, katarometer) silicon chip was designed with the BSC type (Back Side Contact) electrical contacts, covered by the Cr/Au layer. Detector consists of the two elements - glass plate and silicon chip. There are two flow channels formed at the glass-silicon interface - one for detection and the other for reference. Two highly symmetrical groups of resistors were aligned with the channels and, in the last stage of the fabrication sequence, released from the silicon substrate. Some of these resistors act as the heaters, the other ones as the detectors (thermoresistors) to detect changes of the flowing gas temperature. Tubing - gas inlets and outlets - was positioned at the detector edge, in the Si-glass interface plane. BSC-type electrical contacts application enabled very convenient bonding pads location. The Contacts formation process was optimized and integrated with the other technological steps.