An improved TMAH Si-etching solution without attacking exposed aluminum

“…A dip of 150 seconds in BOE (Buffered Oxide Etch) was found to effectively remove the oxide layer. And then the MHP membrane was immediately released by bulk silicon etching without attacking the exposed aluminum using a 5 wt.% TMAH (Tetramethyl Ammonium Hydroxide) dual doped with 1.6 wt.% Si powder and 0.5 wt.% (NH 4 ) 2 S 2 O 8 at 85 • C, 20,21 as shown in Fig. 1(d) and Fig.…”

Section: B Post-cmos Processesmentioning

confidence: 99%

Design and fabrication of a CMOS-compatible MHP gas sensor

et al. 2014

AIP Advances

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A novel micro-hotplate (MHP) gas sensor is designed and fabricated with a standard CMOS technology followed by post-CMOS processes. The tungsten plugging between the first and the second metal layer in the CMOS processes is designed as zigzag resistor heaters embedded in the membrane. In the post-CMOS processes, the membrane is released by front-side bulk silicon etching, and excellent adiabatic performance of the sensor is obtained. Pt/Ti electrode films are prepared on the MHP before the coating of the SnO2 film, which are promising to present better contact stability compared with Al electrodes. Measurements show that at room temperature in atmosphere, the device has a low power consumption of ∼19 mW and a rapid thermal response of 8 ms for heating up to 300 °C. The tungsten heater exhibits good high temperature stability with a slight fluctuation (<0.3%) in the resistance at an operation temperature of 300 °C under constant heating mode for 336 h, and a satisfactory temperature coefficient of resistance of about 1.9‰/°C.

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“…Then, an anisotropic etching process was performed on the chip using TMAHW, following several formulations that increase the selectivity of the TMAH to avoid damage to the exposed aluminium on the chip caused by the etching solution (Fujitsuka et al, 2004;Sullivan et al, 2000;Yan et al, 2001). The next figures show the fabricated chip after a TMAHW etching process.…”

Section: Geometry and Optimization Of The Suspended Membranesmentioning

confidence: 99%