CMOS兼容的干法刻蚀释放热电堆红外探测器
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摘要
作为传统的红外探测器,非制冷型的热电堆探测器由于其结构简单、尺寸较小、成本较低等特点而被广泛应用。采用微机械手段加工的MEMS热电堆探测器可以充分利用CMOS工艺实现与信号处理电路的单片集成,从而进一步提高性能降低成本。本文试图以热电堆红外探测器为例研究MEMS器件与CMOS电路的兼容性问题。
针对传统微机械热电堆器件使用背面腐蚀或者正面各项异性湿法腐蚀释放结构方面的问题,本文提出了一种采用XeF_2气体各项同性干法刻蚀单晶硅释放工艺的热电堆结构,并讨论了不同形状的刻蚀开口对释放结构的影响。
采用正交矩阵实验方法研究了器件制作过程中的两项关键工艺:PECVD淀积低应力Si_3N_4薄膜和XeF_2刻蚀硅工艺。实验结果显示,对于前者,低频脉冲持续时间对Si_3N_4薄膜应力影响最大,并且该时间越长,压应力越大。对于后者,实际器件释放工艺所用的优化参数为:20个刻蚀循环,每个循环的刻蚀时间为60s,XeF_2压力为4torr。
本文还提出了单片集成的热电堆红外探测系统原型,设计了系统框架和工艺制程。我们尝试制作了N-MOSFET,初步证明了实现单片集成系统的可行性,并为将来进一步集成高性能CMOS电路打下了基础。
As one kind of traditional infrared detectors,uncooled thermopile detector has developed various applications due to its simple structure,small size and low cost.By employing micromaching techniques,MEMS thermopile detector is able to make full use of CMOS process which will facilitate integration with signal processing circuits. By this means,we can further improve detector performance and reduce manufacturing cost.In this dissertation,thermopile infrared detector is chosen as a specific case to study the compatibility of MEMS devices and CMOS circuits. To solve the problems involved in traditional structure releasing techniques where back etching or front side etching with anisotropic wet etchants are used,this dissertation presents a structure released by etching bulk silicon isotropically with XeF_2 vapor.Also discussed is how the shapes of etching windows affect the releasing process and result.
Two critical process techniques are examined by orthogonal matrix experiments: PECVD deposition of Si_3N_4 films with low residual stress and etching silicon with XeF_2 vapor.Experimental results suggest that,for the former process,duty time of low frequency pulse is the primary factor influencing the stress of Si_3N_4 films. Besides,the compressive stress is larger when the duty time is longer.For the latter one,the optimized process parameters for our arrangement of thermopiles to be released are:20 etching cycles,etching time of 60s per cycle and the XeF_2 pressure is 4torr. This dissertation also proposes a prototype for monolithic integrating thermopile infrared detecting system as well as the system framework and process flow.We fabricate simple N-MOSFET and testify the feasibility of developing monolithic system which lay foundation for integrating thermopile detector with high performance CMOS circuits in the future.
针对传统微机械热电堆器件使用背面腐蚀或者正面各项异性湿法腐蚀释放结构方面的问题,本文提出了一种采用XeF_2气体各项同性干法刻蚀单晶硅释放工艺的热电堆结构,并讨论了不同形状的刻蚀开口对释放结构的影响。
采用正交矩阵实验方法研究了器件制作过程中的两项关键工艺:PECVD淀积低应力Si_3N_4薄膜和XeF_2刻蚀硅工艺。实验结果显示,对于前者,低频脉冲持续时间对Si_3N_4薄膜应力影响最大,并且该时间越长,压应力越大。对于后者,实际器件释放工艺所用的优化参数为:20个刻蚀循环,每个循环的刻蚀时间为60s,XeF_2压力为4torr。
本文还提出了单片集成的热电堆红外探测系统原型,设计了系统框架和工艺制程。我们尝试制作了N-MOSFET,初步证明了实现单片集成系统的可行性,并为将来进一步集成高性能CMOS电路打下了基础。
As one kind of traditional infrared detectors,uncooled thermopile detector has developed various applications due to its simple structure,small size and low cost.By employing micromaching techniques,MEMS thermopile detector is able to make full use of CMOS process which will facilitate integration with signal processing circuits. By this means,we can further improve detector performance and reduce manufacturing cost.In this dissertation,thermopile infrared detector is chosen as a specific case to study the compatibility of MEMS devices and CMOS circuits. To solve the problems involved in traditional structure releasing techniques where back etching or front side etching with anisotropic wet etchants are used,this dissertation presents a structure released by etching bulk silicon isotropically with XeF_2 vapor.Also discussed is how the shapes of etching windows affect the releasing process and result.
Two critical process techniques are examined by orthogonal matrix experiments: PECVD deposition of Si_3N_4 films with low residual stress and etching silicon with XeF_2 vapor.Experimental results suggest that,for the former process,duty time of low frequency pulse is the primary factor influencing the stress of Si_3N_4 films. Besides,the compressive stress is larger when the duty time is longer.For the latter one,the optimized process parameters for our arrangement of thermopiles to be released are:20 etching cycles,etching time of 60s per cycle and the XeF_2 pressure is 4torr. This dissertation also proposes a prototype for monolithic integrating thermopile infrared detecting system as well as the system framework and process flow.We fabricate simple N-MOSFET and testify the feasibility of developing monolithic system which lay foundation for integrating thermopile detector with high performance CMOS circuits in the future.
引文
1.(美)徐泰然,《MEMS和微系统--设计与制造》,王晓浩等译,机械工业出版社,2005
2.H.Batles,O.Brand,G.K.Fedder,C.Hierold,J.Korvink,O.Tabata,Advanced Micro& Nanosystems,Vol.2 CMOS-MEMS.Wiley-VCH Verlag GmbH & Co.KGaA,2005
3.Products Datasheets,Texas Instruments,http://www.ti.com/
4.Products Datasheets,Analog Devices,http://www.analog.com/
5.吴宗凡,柳美琳,张绍举等,《红外与微光技术》,国防工业出版社,1998
6.梅遂生,杨家德,《光电子技术一信息装备的新秀》,国防工业出版社,1999
7.A.Rogalski,Infrared Detectors at the Beginning of the Next Millennium,Sensors and Materials,2000(Vol.12,No.5):233-288
8.G.R.Lahiji and K.D.Wise,A Batch-Fabricated Silicon Thermopile lnfared Detector,IEEE Trans.ED,Vol.ED-29,No.I,Jan 1982:14-23
9.邵式平编著,《热释电效应及其应用》,兵器工业出版社,1994
10.J.Schieferdecker,R.Quad,E.Holzenkamper,M.Schulze,Infrared Thermopile Sensors with High Sensitivity and Very Low Temperature Coefficient,Sensors and Actuators A,1995(46-47):422-427
11.A.W.Van Herwaarden,D.C.Van Duyn,B.W.Van Oudheusden and P.M.Sarro,Integrated Thermopile Sensors,Sensors and Actuators A,1990(21-23):621-630
12.A.W.Van Herwaarden and P.M.San'o,Thermal Sensors based on The Seebeck Effect,Sensors and Actuators,1986(10):321-346
13.Liddiard K C.Thin-film Resistance Bolometer IR Detectors.Infrared Physics,1984(24):57-64
14.高敏,张景韶,(英)罗(D.M.Rowe)编著,《温差电转换及其应用》,兵器工业出版社,1996
15.G.R.Lahiji and K.D.Wise,A batch-fabricated silicon thermopile infrared detector,IEEE Trans.Electron Devices,ED-29(1982):14-22
16.F.Volklein and A.Wiegand.High Sensitivity and Detectivity Radiation Thermopiles Made by Multi-layer Technology.Sensors and Actuators A,1990(24):1-4
17.F.Volklein A.Wiegand and V.Baier,High-sensitivity Radiation Thermopile Made of Bi-Sb-Te Films.Sensors and Actuators A,1991(29):87-91
18.M.C.Foote,E.W.Jones and T.Caillat.Uncooled Thermopile Infrared Detector Linear Arrays with Detectivity Greater than 10~9 cmHz~(1/2)/W.IEEE Trans ED,Vol.45,No.9,Sep 1998:1896-1902
19.W.G.Baer,K.Najafi,K.D.Wise and R.S.Toth.A 32-Element Micromachined Thermal Imager With On-Chip Multiplexing.Sensors and Actuators A 1995(48):47-54
20.P.M.Sarro,H.Yashiro,A.W.v.herwaarden and S.Middelhoek.An Integrated Thermal Infrared Sensing Array.Sensors and Actuators A,1998(14):191-201
21.R.Lenggenhager,H.Baltes,J.Peer and M.Foster.Thermoelectric Infrared Sensors by CMOS Technology.IEEE Electron Device Letters,Vol.13,No.9,Sept,1992:454-456
22.R.Leggenhager,H.Baltes and T.Elbel.Thermoelectric Infrared Sensors in CMOS Technology.Sensors and Actuators A,1993(37-38):216-220
23.J.Schieferdecker,R.Quad,E.Holzenkamper,M.Schulze,Infrared Thermopile Sensors with High Sensitivity and Very Low Temperature Coefficient,Sensors and Actuators A 1995(46-47):422-427
24.E.Socher,O.Bochobza-Degani and Y.Nemirovsky,Optimal Performance of CMOS compatible IR Thermoelectric Sensors,Journal of Microelectromechanical Systems,Vol.9,No.1,March,2000:38-46
25.U.Münch,D.Jaeggi,K.Schneeberger,A.Schaufelbühl,O.Paul,H.Baltes and J.Jasper,Industrial Fabrication Technology for CMOS Infrared Sensors Array,1997International Conference on Solid-State Sensors and Actuators(Transducers'97),June 16-19,1997,Chicago,Illinois,USA,1d3.02
26.I.H.Choi and K.D.Wise,A Silicon-Thermopile-Based Infrared Sensing Array for Use in Automated Manufacturing,IEEE Trans ED,Vol.ED-33,No.1,Jan 1996:72-79
27.Andrew D.Oliver,Kensall D.Wise,A 1024-element bulk-micromachined thermopile infrared imaging array,Sensors and Actuators A,1999(73):222-231
28.Andri Schaufeibuhl,N.Schneeberger,U.Munch,Uncooled Low-Cost Thermal Imager Based on Micromachined CMOS Integrated Sensor Array,IEEE J.MEMS,vol.10,pp.503-510,2001
29.徐峥谊,微机械热电堆红外探测器,中国科学院博士学位论文,2002年5月
30.杨广立,微机械反射式光读出非制冷红外成像阵列器件,中国科学院博士学位论文,2007年5月
31.Products Datasheets,KDX Technology,http://kdxtech.com/
32.A.Tarraf,J.Dalelden,et.al.,Stress investigation of PECVD dielectric layers for advanced optical MEMS,J.Micromech.Microeng.2004(14):317-323
2.H.Batles,O.Brand,G.K.Fedder,C.Hierold,J.Korvink,O.Tabata,Advanced Micro& Nanosystems,Vol.2 CMOS-MEMS.Wiley-VCH Verlag GmbH & Co.KGaA,2005
3.Products Datasheets,Texas Instruments,http://www.ti.com/
4.Products Datasheets,Analog Devices,http://www.analog.com/
5.吴宗凡,柳美琳,张绍举等,《红外与微光技术》,国防工业出版社,1998
6.梅遂生,杨家德,《光电子技术一信息装备的新秀》,国防工业出版社,1999
7.A.Rogalski,Infrared Detectors at the Beginning of the Next Millennium,Sensors and Materials,2000(Vol.12,No.5):233-288
8.G.R.Lahiji and K.D.Wise,A Batch-Fabricated Silicon Thermopile lnfared Detector,IEEE Trans.ED,Vol.ED-29,No.I,Jan 1982:14-23
9.邵式平编著,《热释电效应及其应用》,兵器工业出版社,1994
10.J.Schieferdecker,R.Quad,E.Holzenkamper,M.Schulze,Infrared Thermopile Sensors with High Sensitivity and Very Low Temperature Coefficient,Sensors and Actuators A,1995(46-47):422-427
11.A.W.Van Herwaarden,D.C.Van Duyn,B.W.Van Oudheusden and P.M.Sarro,Integrated Thermopile Sensors,Sensors and Actuators A,1990(21-23):621-630
12.A.W.Van Herwaarden and P.M.San'o,Thermal Sensors based on The Seebeck Effect,Sensors and Actuators,1986(10):321-346
13.Liddiard K C.Thin-film Resistance Bolometer IR Detectors.Infrared Physics,1984(24):57-64
14.高敏,张景韶,(英)罗(D.M.Rowe)编著,《温差电转换及其应用》,兵器工业出版社,1996
15.G.R.Lahiji and K.D.Wise,A batch-fabricated silicon thermopile infrared detector,IEEE Trans.Electron Devices,ED-29(1982):14-22
16.F.Volklein and A.Wiegand.High Sensitivity and Detectivity Radiation Thermopiles Made by Multi-layer Technology.Sensors and Actuators A,1990(24):1-4
17.F.Volklein A.Wiegand and V.Baier,High-sensitivity Radiation Thermopile Made of Bi-Sb-Te Films.Sensors and Actuators A,1991(29):87-91
18.M.C.Foote,E.W.Jones and T.Caillat.Uncooled Thermopile Infrared Detector Linear Arrays with Detectivity Greater than 10~9 cmHz~(1/2)/W.IEEE Trans ED,Vol.45,No.9,Sep 1998:1896-1902
19.W.G.Baer,K.Najafi,K.D.Wise and R.S.Toth.A 32-Element Micromachined Thermal Imager With On-Chip Multiplexing.Sensors and Actuators A 1995(48):47-54
20.P.M.Sarro,H.Yashiro,A.W.v.herwaarden and S.Middelhoek.An Integrated Thermal Infrared Sensing Array.Sensors and Actuators A,1998(14):191-201
21.R.Lenggenhager,H.Baltes,J.Peer and M.Foster.Thermoelectric Infrared Sensors by CMOS Technology.IEEE Electron Device Letters,Vol.13,No.9,Sept,1992:454-456
22.R.Leggenhager,H.Baltes and T.Elbel.Thermoelectric Infrared Sensors in CMOS Technology.Sensors and Actuators A,1993(37-38):216-220
23.J.Schieferdecker,R.Quad,E.Holzenkamper,M.Schulze,Infrared Thermopile Sensors with High Sensitivity and Very Low Temperature Coefficient,Sensors and Actuators A 1995(46-47):422-427
24.E.Socher,O.Bochobza-Degani and Y.Nemirovsky,Optimal Performance of CMOS compatible IR Thermoelectric Sensors,Journal of Microelectromechanical Systems,Vol.9,No.1,March,2000:38-46
25.U.Münch,D.Jaeggi,K.Schneeberger,A.Schaufelbühl,O.Paul,H.Baltes and J.Jasper,Industrial Fabrication Technology for CMOS Infrared Sensors Array,1997International Conference on Solid-State Sensors and Actuators(Transducers'97),June 16-19,1997,Chicago,Illinois,USA,1d3.02
26.I.H.Choi and K.D.Wise,A Silicon-Thermopile-Based Infrared Sensing Array for Use in Automated Manufacturing,IEEE Trans ED,Vol.ED-33,No.1,Jan 1996:72-79
27.Andrew D.Oliver,Kensall D.Wise,A 1024-element bulk-micromachined thermopile infrared imaging array,Sensors and Actuators A,1999(73):222-231
28.Andri Schaufeibuhl,N.Schneeberger,U.Munch,Uncooled Low-Cost Thermal Imager Based on Micromachined CMOS Integrated Sensor Array,IEEE J.MEMS,vol.10,pp.503-510,2001
29.徐峥谊,微机械热电堆红外探测器,中国科学院博士学位论文,2002年5月
30.杨广立,微机械反射式光读出非制冷红外成像阵列器件,中国科学院博士学位论文,2007年5月
31.Products Datasheets,KDX Technology,http://kdxtech.com/
32.A.Tarraf,J.Dalelden,et.al.,Stress investigation of PECVD dielectric layers for advanced optical MEMS,J.Micromech.Microeng.2004(14):317-323