Elements of the silicon TCD design and technology

Abstract

Silicon TCD (Thermal Conductivity Detector, katarometer) chip analytical model, elements of the design and technology are presented. Detector was designed for the pTAS (Micro Total Analysis System) application to recognize the composition of the different gas mixtures. TCD consists of the two pieces : glass plate and silicon chip. Two parallel flow channels 15 000 pm long, 400 pm wide and 50 pm deep were etched in the silicon chip and milled in the glass plate. Some of resistors were designed to act as a heaters and the other ones as a thermo resistors. Composition changes of the mixture flowing throughout the channel cause the temperature distribution changes and thermo resistors electrical response. Distance between the heaters and thermo resistors is of the great importance to the TCD sensitivity. VLSI silicon technology was applied to reduce geometrical dimensions and micromechanical technology to over-hange resistors across the flow channels to reduce thermal capacity and heat loses to the bulk and environment.