Fabrication and Evaluation of TiN Micro-heater for MEMS Gas Sensor

Fabrication and evaluation of suspended Micro‐heater using TiN

“…Results obtained for TiN micro heaters developed so far are summed up in Table 1. Power dissipation of 70 mW for suspended structure in this study Si was the lowest as compared to 170 W for quartz‐glass design 6 and 820 mW for T‐shaped structure 7 . Heaters configured on a wafer are strongly affected by thermal conductivity of silicon 11 ; this study confirmed that suspended structure with floating filament contributes to power dissipation reduction.…”

“…The power in coil samples was nearly proportional to the filament length, that is, the difference was about two‐fold; in contrast, the difference was only about 1.4‐fold in comb samples, which can be explained as follows. Thermal deformation and disconnection were observed in photographs of comb samples after destructive tests 6 ; this suggests that heating concentrated in the central part so that powe3r dissipation did not depend on the filament length. However, this requires verifying through accurate measurement of temperature distribution by micro‐thermography.…”

“…Heating characteristics of suspended TiN micro heaters are shown in Figure 5. Heater temperature was determined using temperature coefficient of electrical resistivity 6 . This method is known as a simple and accurate measurement; since temperature dependence of resistivity in TiN is nonlinear, linear approximation from room temperature to 300°C was applied in this study.…”

“…All samples of the micro heaters considered in this study have heater area of 300 μm 2 and filament width of 20 μm. There are two types with different filament length of 2200 μm and 1100 μm, and two types with different heater shape – coil type and comb type 5 . In the suspended structure, a filament is supported by Si pillars at the corner parts where the filament is folded as shown in Figure 1.…”

“…We have studied filament structures offering low power consumption and simpler fabrication as compared to TiN heaters 4–7 . In a T‐shaped structure with silicon pillars left for reinforcement, power dissipation was high 7 ; in addition, hollow fabrication in a self‐supporting film using thermal oxide (SiO 2 ) was difficult because of film stress.…”