[1] Zhang ZiliYin ChenboTao ChunminZhu Bin,. Characteristics of suspended planar-type gas sensorbased on MEMS process [J]. Journal of Southeast University (English Edition), 2012, 28 (3): 315-320. [doi:10.3969/j.issn.1003-7985.2012.03.011]
Copy
Characteristics of suspended planar-type gas sensorbased on MEMS process(
)
基于MEMS工艺的悬臂共面式气体传感器性能分析
)Journal of Southeast University (English Edition)[ISSN:1003-7985/CN:32-1325/N]
- Volumn:
- 28
- Issue:
- 2012 3
- Page:
- 315-320
- Research Field:
- Automation
- Publishing date:
- 2012-09-30
Info
- Title:
- Characteristics of suspended planar-type gas sensorbased on MEMS process
- 基于MEMS工艺的悬臂共面式气体传感器性能分析
- Author(s):
- Zhang ZiliYin ChenboTao ChunminZhu Bin
- School of Mechanical and Power Engineering, Nanjing University of Technology, Nanjing 210009, China
- PACS:
- TP212.2
- DOI:
- 10.3969/j.issn.1003-7985.2012.03.011
- Abstract:
- In order to simplify the fabrication process, distribute the temperature uniformly and reduce the power consumption of the micro-hotplate(MHP)gas sensor, a planar-type gas sensor based on SnO2 thin film with suspended structure is designed through a MEMS process. Steady-state thermal analysis of the gas sensor and the closed membrane type sensor where the membrane overlaps the Si substrate is carried out with the finite element model, and it is shown that the suspended planar-type gas sensor has a more homogeneous temperature distribution and a lower power consumption. When the maximum temperature on the sensor reaches 383℃, the power consumption is only 7 mW, and the temperature gradient across the thin film is less than 14℃. To overcome the fragility of the suspended beams, a novel fabrication process in which the deposition of the gas sensing film occurs prior to the formation of suspended beams is proposed. The back side of the Si substrate is etched through deep reactive ion etching(DRIE)to avoid chemical pollution of the front side. The fabrication steps in which only four masks are used for the photolithography are described in detail. The Fe doped SnO2 thin film synthesized by sol-gel spin-coating is used as the gas sensing element. The device is tested on hydrogen and exhibits satisfactory sensing performance. The sensitivity increases with the rise of the concentration from 50×10-6 to 2000×10-6, and reaches about 30 at 2000×10-6.
- 为了简化制作工艺, 使温度分布均匀以及降低功耗, 设计了一种基于MEMS制造工艺的悬臂共面式SnO2气体传感器.使用有限元法对这种传感器及膜结构堆积于硅基底上的封闭膜式气体传感器进行了稳态热分析, 结果表明悬臂共面式传感器拥有更均匀的温度分布和更低的功耗.当最高温度为383℃时功耗仅为7mW, 敏感薄膜上的温差低于14℃.为解决悬臂易碎的问题, 提出了一种新的制造工艺, 该过程在正面刻蚀SiO2层形成悬臂结构前沉积SnO2敏感薄膜, 并采用深反应离子刻蚀的方法对硅基底进行体刻以避免湿法刻蚀对传感器表面的化学污染.整个过程总共需要4块掩模板.采用旋涂法溶胶凝胶法将掺有Fe离子的SnO2薄膜沉积于基底上作为敏感元件.该器件对氢气表现出了良好的气敏性能, 随着氢气浓度从50×10-6上升到2000×10-6, 灵敏度逐渐提高, 在2000×10-6时的灵敏度为30.
References:
[1] Choi K Y, Park J K, Park K M, et al. Low power micro-gas sensors using mixed SnO2 nanoparticles and MWCNTs to detect NO2, NH3, and xylene gases for ubiquitous sensor network applications[J]. Sensors and Actuators B: Chemical, 2010, 150(1): 65-72.
[2] Sharma A, Tomar M, Gupta T. SnO2 thin film sensor with enhanced response for NO2 gas at lower temperatures[J]. Sensors and Actuators B: Chemical, 2011, 156(2): 743-752.
[3] Hübner M, Simion C E, Haensch A, et al. CO sensing mechanism with WO3 based gas sensors[J]. Sensors and Actuators B: Chemical, 2010, 151(1): 103-106.
[4] Wang H C, Li Y, Yang M J. Fast response thin film SnO2 gas sensors operating at room temperature[J]. Sensors and Actuators B: Chemical, 2006, 119(2): 380-383.
[5] Korotcenkov G, Cho B K. Thin film SnO2-based gas sensors: film thickness influence[J]. Sensors and Actuators B: Chemical, 2009, 142(1): 321-330.
[6] Semancik S, Cavicchi R E, Wheeler M C, et al. Microhotplate platforms for chemical sensor research[J]. Sensors and Actuators B: Chemical, 2001, 77(1/2): 579-591.
[7] Rajinish K S, Chan P C H, Tang Z, et al. Investigation of stability and reliability of tin oxide thin-film for integrated micro-machined gas sensor devices[J]. Sensors and Actuators B: Chemical 2001, 81(1): 6-9.
[8] Fung S K H, Tang Z, Chan P C H, et al. Thermal analysis and design of a micro-hotplate for integrated gas-sensor applications[J]. Sensors and Actuators A: Physical, 1996, 54(1/2/3): 482-487.
[9] Sheng L Y, Tang Z, Wu J, et al. A low-power CMOS compatible integrated gas sensor using maskless tin oxide sputtering[J]. Sensors and Actuators B: Chemical, 1998, 49(1/2): 81-87.
[10] Hascik S, Hotovy I, Lalinsky T, et al. Preparation of thin GaAs suspended membranes for gas micro-sensors using plasma etching[J]. Vacuum, 2007, 29(2): 236-239.
[11] Chung G S, Jeong J M. Fabrication of micro heaters on polycrystalline 3C-SiC suspended membranes for gas sensors and their characteristics[J]. Microelectronic Engineering, 2010, 87(11): 2348-2352.
[12] Chung W Y, Lim J W, Lee D D, et al. Thermal and gas-sensing properties of planar-type micro gas sensor[J]. Sensors and Actuators B: Chemical, 2000, 64(1/2/3): 118-123.
[13] Tao Chunmin, Yin Chenbo, He Maoxian, et al. Thermal analysis and design of a micro-hotplate for Si-substrated micro-structural gas sensor[C]//3rd IEEE International Conference on Nano/Micro Engineered and Molecular Systems. Sanya, China, 2008: 284-287.
[14] Zhao Jie, Huo Lihua, Gao Shan, et al. Alcohols and acetone sensing properties of SnO2 thin films deposited by dip-coating[J]. Sensors and Actuators B: Chemical, 2006, 115(1): 460-464.
[15] Rani S, Roy S C, Bhatnagar M C. Effect of Fe doping on the gas sensing properties of nano-crystalline SnO2 thin films[J]. Sensors and Actuators B: Chemical, 2006, 122(1): 204-210.
[16] Vaishampayan M V, Deshmukh R G, Walke P, et al. Fe doped SnO2 nanomaterial: a low temperature hydrogen sulfide gas sensor[J]. Materials Chemistry and Physics, 2008, 109(2/3): 230-234.
[17] Zhu Bin, Yin Chenbo, Tao Chunmin, et al. Research on the micro gas sensor text system based on constant gas-distribution method[J]. Chinese Journal of Scientific Instrument, 2011, 32(12): 76-82.
Memo
- Memo:
-
Biographies: Zhang Zili(1984—), male, graduate; Yin Chenbo(corresponding author), male, doctor, professor, yinchenbo@njut.edu.cn.
Foundation items: The National Natural Science Foundation of China(No.58175122), the Natural Science Foundation of Jiangsu Province(No.BK2007185), the Natural Science Foundation of Higher Education Institutions of Jiangsu Province(No.07KJB460044), the Scientific Research Innovation Project for College Graduates in Jiangsu Province(No.CXZZ11_0340).
Citation: Zhang Zili, Yin Chenbo, Tao Chunmin, et al. Characteristics of suspended planar-type gas sensor based on MEMS process[J].Journal of Southeast University(English Edition), 2012, 28(3):315-320.[doi:10.3969/j.issn.1003-7985.2012.03.011]