一种加热丝埋入式微热板的研制
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摘要
在传统"三明治"夹层结构的基础上,微热板将加热丝埋入到基底绝缘层中,通过周围绝缘层介质对加热丝的约束作用,减小了Pt加热丝与基底以及覆盖层热膨胀系数失配所产生的热应力对器件稳定性造成的影响,从而提高微热板在高温工作时的稳定性。主要加工工艺流程为:利用热氧化方法和LPCVD在4 in硅片两侧制备SiO2/Si3N4介质层,在待埋入加热丝的位置通过RIE制作出坑槽,然后利用剥离工艺制备出双曲螺旋形状Pt加热丝,在硅片的背部利用RIE干法刻蚀和湿法刻蚀加工出绝热槽,最后在加热丝的上方沉积一层SiO2绝缘层并在引线盘位置开窗。通过实验验证:该微热板在350℃内可以稳定工作,微热板在有效面积内(5 mm×5 mm)温度均匀性好,功率约为130 mW(350℃时)。
Based on traditional"sandwich"structure,heater-strip is embedded in the substrate insulting layer in MHP and due to constraint function of peripheric insulating layer,the effect of thermal stress caused by Pt heaterstrip and substrate and thermal expansion coefficient mismatch of baring layer on the device is reduced,thus improving the stability of the device.The MHP is fabricated by traditional MEMS processes,which began with preparing the 4-inch silicon wafer with SiO2/ Si3N4 insulting layers on both sides,through the method of thermal oxidation and LPCVD.The groove for micro heater is formed via RIE,and a layer of meander-shaped Pt micro heater is placed right in the groove by lift-off.An insulation pit is etched on the backside of the wafer through RIE and wet etching.After an insulting layer of SiO2 is sputtered onto the heater-strip,open window in position of lead disc.Experiment verifies that the MHP can work properly and steadily at 350 ℃ with good temperature uniformity within heating area(5 mm×5 mm),and the power is about 130 mW at 350 ℃.
Based on traditional"sandwich"structure,heater-strip is embedded in the substrate insulting layer in MHP and due to constraint function of peripheric insulating layer,the effect of thermal stress caused by Pt heaterstrip and substrate and thermal expansion coefficient mismatch of baring layer on the device is reduced,thus improving the stability of the device.The MHP is fabricated by traditional MEMS processes,which began with preparing the 4-inch silicon wafer with SiO2/ Si3N4 insulting layers on both sides,through the method of thermal oxidation and LPCVD.The groove for micro heater is formed via RIE,and a layer of meander-shaped Pt micro heater is placed right in the groove by lift-off.An insulation pit is etched on the backside of the wafer through RIE and wet etching.After an insulting layer of SiO2 is sputtered onto the heater-strip,open window in position of lead disc.Experiment verifies that the MHP can work properly and steadily at 350 ℃ with good temperature uniformity within heating area(5 mm×5 mm),and the power is about 130 mW at 350 ℃.
引文
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[3]Simon I,Barsan N,Bauer M,et al.Micromachined metal oxide gas sensors:Opportunities to improve sensor performance[J].Sensors and Actuators B,2001,73:1-26.
[4]任军强.微型固体电解质CO2气体传感器的研制[D].西安:西安交通大学,2011.
[5]Briand D,Beaudoin F,Courbat J,et al.Failure analysis of microheating elements suspended on thin membranes[J].Microelectronics Reliability,2005,45:1786-1789.
[6]Pike A,Gardner J W.Thermal modeling and characterization of micropower chemoresistive silicon sensors[J].Sensors and Actuators B,1997,45:19-26.
[7]Ali S Z,Udrea F,Milne W I,et al.Tungsten-based SOI microhotplates for smart gas sensors[J].Journal of Micro-electro-mechanical Systems,2008,17:1408-1417.
[8]Puigorbe J,Vogel D,Michel B,et al.Thermal and mechanical analysis of micromachined gas sensors[J].Journal of Micro-electro-mechanical Systems,2003,13:548-556.
[9]Courbat J,Barbieri M,Briand D,et al.Reliability of micro-hot plates on polyimide foil[C]∥Proceedings of the Transducers’11Conference,Beijing,China,2011:338-341.