Effects of material and membrane structure on maximum temperature of microheater for gas sensor applications

The material selection for membrane is important in designing a microheater. A membrane is used as an insulator layer to prevent heat dissipation from the microheater to the substrate. At the same time, the thermal characteristic of the microheater is influenced by the insulator layer. A study on the effects of material and membrane structure on the maximum temperature of the microheater for gas sensor applications has been carried out using Heat Transfer Module of COMSOL 4.2. Three different membrane materials namely silicon nitride (Si₃N₄), silicon dioxide (SiO₂) and polyimide and two types of membrane structures namely full-membrane and bridgemembrane have been chosen for the study. Their effects on the microheater temperature are presented. The resistive meander type of microheater is used in this study. The heater material is platinum. The thickness and the area of the heater are 2 μm and 600 μm × 680 μm respectively. The thickness of each membrane is 5 μm. The area of the full-membrane and the bridgemembrane are 2500 μm × 2500 μm and 850 μm × 850 μm respectively.