Microhotplate temperature sensor calibration and BIST

• DOI: 10.6028/jres.116.025
• Publication Date: 2012-01-11T17:37:25Z
• Authors: M. Afridi; C. Montgomery; E. Cooper-Balis; S. Semancik; K.G. Kreider; J. Geist
• Keywords: Thermocouple; Resistance thermometer

In this paper we describe a novel long-term microhotplate temperature sensor calibration technique suitable for Built-In Self Test (BIST). The thermal resistance (thermal efficiency) and the voltage from an integrated platinum-rhodium thermocouple were calibrated against freshly four-wire polysilicon microhotplate-heater (heater) that is not stable over long periods of time when exposed to higher temperatures. To stress microhotplate, its was raised around 400 °C held there days. heater then recalibrated as sensor, measurements made based on fresh heater, first resistance, voltage. This procedure repeated 10 times period 80 results show drifted substantially during test while thermocouple-voltage remained within about plus or minus 1 same period. Therefore, combination heater-temperature either thin film can be used provide stable, calibrated, microhotplate-temperature three implementing BIST functionality. Alternatively, if available, such properly annealed platinum electrical will sufficient implement BIST. It also shown aluminum- polysilicon-based sensors, which are enough measuring high temperatures (>220 °C) without impractically frequent recalibration, measure silicon substrate never above 220 °C.