LAS系统微晶玻璃的制备及阳极键合性能与工艺参数关系的研究
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摘要
近年来，随着科学技术的发展，微机电系统在越来越多的领域中得到了广泛的应用。但作为微机电系统封装的关键技术——半导体硅与玻璃的阳极键合技术，仍然存在着许多问题。目前国内外多采用Pyrex与SD-2玻璃作为与硅基片封装的阳极键合材料。这两种玻璃不但具有较低的蚀刻速率，而且随温度的变化其热膨胀系数与硅片不甚匹配，导致封装后残余应力较大，给封装工艺带来困难。与上述两种玻璃相比，微晶玻璃具有机械强度高、硬度大、耐磨性好；具有良好的化学稳定性和热稳定性；电绝缘性能优良、介电损耗小、介电常数稳定等优点。因此本课题采用微晶玻璃代替传统玻璃，以期在较低温度下(＜350℃)实现微晶玻璃与硅片的良好键合。
本课题选用Li_2O-Al_2O_3-SiO_2(LAS)系统微晶玻璃作为与硅片适配的阳极键合基片材料。用传统的熔体冷却法制得该系统基础玻璃，利用差热分析(DTA)确定基础玻璃的核化与晶化温度，然后采用不同的热处理制度对基础玻璃进行热处理。通过X射线衍射(XRD)、扫描电镜(SEM)分析了微晶玻璃的主晶相的种类、尺寸大小、含量与微观结构形貌，分析了热处理制度对微晶玻璃热学性能、力学性能、电阻率以及介电性能的影响。在温度为200～400℃，电压为400～600V的条件下，进行了微晶玻璃与硅片的阳极键合实验，研究了电压、温度、时间等工艺参数对阳极键合性能的影响。并通过对键合微观表面、界面的分析，进一步探讨了微晶玻璃与硅片阳极键合的机理。获得了以下研究成果：
1、随着核化与晶化时间的增加，微晶玻璃的主晶相均为β-锂辉石不变，其热膨胀系数增大，抗折强度先增大后减小，电阻率增大，介电常数与介电损耗均呈减小的趋势。
2、当热处理制度为670℃／3h、80℃／3h时，微晶玻璃的热膨胀系数为31．16×10~(-7)／℃(200～400℃)，抗折强度为186．64MPa，电阻率为1．02×10~(12)(?)·m (20℃)，介电常数为21．5(20℃)，适合与硅片进行阳极键合。
3、键合强度随电压、温度的增加而增大，电压、温度对键合性能影响较大，时间对键合性能影响较小。当电压为500V时，温度低于200℃时则不能实现键合。在电压为500V，温度为400℃时，键合强度最大为10．25 MPa。本研究得到国家自然科学基金(50472039)和湖北省自然科学基金(2005ABA011)的资助。
In recent years, Micro electronic mechanical system (MEMS) has been applied in more and more fields with the development of the science and technology. But as one of the packaging technology, anodic bonding of silicon-glass has many deficiencies. Pyrex glass and SD-2 glass are used as anodic bonding materials which are packaged with silicon, they not only have slow velocity of etch, but also have improper coefficient of thermal expansion(CTE) with silicon on different temperature and great residual stress which have bring difficulty to packaging technology. Compared with them, glass-ceramic has a lot of advantages such as high mechanical strength and rigidity, good chemical and thermal stability, good insulation, small dielectric loss, steady dielectric constant and so on. So glass-ceramic was chose to replace traditional glass to bond with silicon at the temperature under 35℃.
In this paper, Li_2O-Al_2O_3-SiO_2(LAS) system glass-ceramic was chose to as anodic bonding material which was matched to silicon. The basic glass was prepared by adopting conventional melt quenching technology and the temperature of nucleation and crystallization were determined by using DTA. And then the basic glass was heated according to different heat-treatment schedule. The main crystal phase and microstructure were researched by XRD and SEM. The effect of heat-treatment schedule on performance of CTE, mechanical strength, resistivity and dielectric constant had been studied. The experimental of anodic bonding was done at the temperature range from 200℃to 400℃, voltage from 400V to 600V. The effect of technical parameter of voltage, temperature and time on bonding performance was discussed. And the mechanism of anodic bonding of glass-ceramic and silicon was studied by analyzing the microstructure of bonding surface and interface. The results have been got as follows:
1. With the increase time of crystallization and nucleation, the main crystal phases of the glass-ceramics wereβ-spodumenes. The CTE and resistivity of glass-ceramic increased, mechanical strength increased first and then decreased, dielectric constant and dielectric loss decreased.
2. When the heat-treatment schedule was 670℃/3h、980℃/3h, the glass-ceramic of CTE 31.16×10~(-7)/℃(200～400℃), mechanical strength 186.64MPa, resistivity 1.02×10~(12)Ω·m(20℃), dielectric constant 21.5(20℃) which is matched silicon to anodic bonding.
3. The anodic bonding experimental results showed that the bonding strength had increased when temperature and voltage were increased, and the time had little influence on bonding strength. The anodic bonding could not realize at the voltage of 500V when the temperature was under 200℃. The bonding strength increased to the most at 10.25 MPa at the temperature of 400℃, voltage of 500V.
The project was supported by the National Natural Science Foundation of China (50472039) and the Hubei Provincial Natural Science Foundation of China (2005ABA011).
本课题选用Li_2O-Al_2O_3-SiO_2(LAS)系统微晶玻璃作为与硅片适配的阳极键合基片材料。用传统的熔体冷却法制得该系统基础玻璃，利用差热分析(DTA)确定基础玻璃的核化与晶化温度，然后采用不同的热处理制度对基础玻璃进行热处理。通过X射线衍射(XRD)、扫描电镜(SEM)分析了微晶玻璃的主晶相的种类、尺寸大小、含量与微观结构形貌，分析了热处理制度对微晶玻璃热学性能、力学性能、电阻率以及介电性能的影响。在温度为200～400℃，电压为400～600V的条件下，进行了微晶玻璃与硅片的阳极键合实验，研究了电压、温度、时间等工艺参数对阳极键合性能的影响。并通过对键合微观表面、界面的分析，进一步探讨了微晶玻璃与硅片阳极键合的机理。获得了以下研究成果：
1、随着核化与晶化时间的增加，微晶玻璃的主晶相均为β-锂辉石不变，其热膨胀系数增大，抗折强度先增大后减小，电阻率增大，介电常数与介电损耗均呈减小的趋势。
2、当热处理制度为670℃／3h、80℃／3h时，微晶玻璃的热膨胀系数为31．16×10~(-7)／℃(200～400℃)，抗折强度为186．64MPa，电阻率为1．02×10~(12)(?)·m (20℃)，介电常数为21．5(20℃)，适合与硅片进行阳极键合。
3、键合强度随电压、温度的增加而增大，电压、温度对键合性能影响较大，时间对键合性能影响较小。当电压为500V时，温度低于200℃时则不能实现键合。在电压为500V，温度为400℃时，键合强度最大为10．25 MPa。本研究得到国家自然科学基金(50472039)和湖北省自然科学基金(2005ABA011)的资助。
In recent years, Micro electronic mechanical system (MEMS) has been applied in more and more fields with the development of the science and technology. But as one of the packaging technology, anodic bonding of silicon-glass has many deficiencies. Pyrex glass and SD-2 glass are used as anodic bonding materials which are packaged with silicon, they not only have slow velocity of etch, but also have improper coefficient of thermal expansion(CTE) with silicon on different temperature and great residual stress which have bring difficulty to packaging technology. Compared with them, glass-ceramic has a lot of advantages such as high mechanical strength and rigidity, good chemical and thermal stability, good insulation, small dielectric loss, steady dielectric constant and so on. So glass-ceramic was chose to replace traditional glass to bond with silicon at the temperature under 35℃.
In this paper, Li_2O-Al_2O_3-SiO_2(LAS) system glass-ceramic was chose to as anodic bonding material which was matched to silicon. The basic glass was prepared by adopting conventional melt quenching technology and the temperature of nucleation and crystallization were determined by using DTA. And then the basic glass was heated according to different heat-treatment schedule. The main crystal phase and microstructure were researched by XRD and SEM. The effect of heat-treatment schedule on performance of CTE, mechanical strength, resistivity and dielectric constant had been studied. The experimental of anodic bonding was done at the temperature range from 200℃to 400℃, voltage from 400V to 600V. The effect of technical parameter of voltage, temperature and time on bonding performance was discussed. And the mechanism of anodic bonding of glass-ceramic and silicon was studied by analyzing the microstructure of bonding surface and interface. The results have been got as follows:
1. With the increase time of crystallization and nucleation, the main crystal phases of the glass-ceramics wereβ-spodumenes. The CTE and resistivity of glass-ceramic increased, mechanical strength increased first and then decreased, dielectric constant and dielectric loss decreased.
2. When the heat-treatment schedule was 670℃/3h、980℃/3h, the glass-ceramic of CTE 31.16×10~(-7)/℃(200～400℃), mechanical strength 186.64MPa, resistivity 1.02×10~(12)Ω·m(20℃), dielectric constant 21.5(20℃) which is matched silicon to anodic bonding.
3. The anodic bonding experimental results showed that the bonding strength had increased when temperature and voltage were increased, and the time had little influence on bonding strength. The anodic bonding could not realize at the voltage of 500V when the temperature was under 200℃. The bonding strength increased to the most at 10.25 MPa at the temperature of 400℃, voltage of 500V.
The project was supported by the National Natural Science Foundation of China (50472039) and the Hubei Provincial Natural Science Foundation of China (2005ABA011).
引文
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[21] 贺海燕．微晶玻璃的定向晶化．陶瓷工程，1999(1)：34-38
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[2] Gao Z.Y. , et al. Advance on micro machined inertial instruments. In Proceedings of theChina-Japan Joint Workshop on Micromachine/MEMs. Beijing,1997,9:84
[3] Esashi M., Nakano A., Shuiji S., et al. Low-temperature silicon-to-silicon anodic bonding withintermediate. Sensors and Actuators,1990,A 21-23:930
[4] Maszara W.P. Silicon on insulator by wafer bonding: renew. Electrochemsoc,1991, 138(1):341-347
[5] 王多笑，邬玉亭等．低温阳极键合技术研究．．传感器技术，2005，24(9)：37-39
[6] Tai-Ran Hsu．微机电系统封装．北京：清华大学出版社，2006
[7] Shuichi Shoji, Hiroto Kikuchi, Hirotaka Torigoe. Low-temperature anodic bonding usinglithium aluminosilicate-B-quartz glass ceramic. Sensors and actuators, A 64 (1998), pp:95-100
[8] M Mado. Fundamentals of Microfabrication. CRC Press, Boca Raton, 1997
[9] T R Hsu.MEMS & Microsytems Design and Manufacture. McGraw-Hill Boston:2002
[10] M G Pecht, L T Nguyen, E B Hakim. Plastic-Encapsulated Microelectronics, John Wile &Sons, Inc, New York:1995
[11] Tachimori M, Masui S, Nakajima T et al. Quality innovation of SIMOX wafers by low doseand high-temperature oxidation techniques. Electrochemical Society Proceedings,1996,96(3):53-62
[12] Maszara W P. Silicon on insulator by wafer bonding review. ElectrochemSoc, 1991,138(1):341-347
[13] Bruel M, Aspar, Andre-Jacques Auberton-Herve. Smart-cut: a new silicon on insulatormaterial technology based on hydrogen implantation and wafer bonding. Jap J Appl Phys,1997,36(3B):1636-1641
[14] Henmi H, Sboji S, Shoji Y, et al. Vacuum packaging for micro-sensors by glass-siliconanodic bonding. Sensors and Actuators, 1994,43:246-247
[15] Wilson R,Qninn C,McDonnell B. Bonded and trenched SOI with buried silicate layers. In:Proceedings of the Third International Symposium on Semiconductor Wafer Bonding:Physics and Applications. The Electrochemical Society Inc, USA, 1995, 95(7):535-545
[16] Ismail M. S., Bower R. W., Roberds B. E., et al. One step direct bonding process of lowtemperature technology. In: The 7~(th) International Conference on solid state sensors andActuators, Yokohama, Japan,1993,6:188-190
[17] Shuichi Shoji, Hiroto Kikuchi, Hirotaka Torigoe. Low-temperature anodic bonding usinglithium aluminosilicate-B-quartz glass ceramic. Sensors and actuators, A 64 (1998), pp:95-100
[18] 常鹰，卢安贤．静电键合用微晶玻璃的研究．中南工业大学学报(自然科学版)2003年05期
[19] [英]P．W．麦克米伦著．微晶玻璃．北京：中国建筑工业出版社，1988
[20] 廖永建，张建成，顾峰，沈悦，王华，焦凤华．TiO_2在纳米相微晶玻璃制备中的作用研究．上海大学学报(自然科学版)，2003(9)：5-12
[21] 贺海燕．微晶玻璃的定向晶化．陶瓷工程，1999(1)：34-38
[22] Yun-Mo Sung. Mechanical properties of a-cordierite and B-spodumene glass -ceramicsprepared by sintering and crystallization heat treatments Ceramics international.1997(23):401-407
[23] Kerker M. The Scattering of light. Academic Press, New York, 1969
[24] Andreev N S. Scattering of visible light by glasses undergoing phase separation andhomogenization. Non-Crystal. Sol. 1978,30:99-126
[25] Hoppper R W. Stochastic theory of scattering from idealized spindle structure Ⅱ. Scatteringin general and for the basic late stage model, F. Non-cryst. Solids. 1985,70:111-42
[26] LArnault, A.Riviere, B.Lucas. Relaxations in Li_2O-Al_2O_3-SiO_2 type glass andglass-ceramics studied by isothermal mechanical spectroscopy Journal of Non-CrystallineSolids 1997 (210):87-94
[27] P.Riello, P.Cunton, et al. Nucleation and crystallization behavior of glass-ceramic materials inthe Li_2O-Al_2O_3-SiO_2 system of interest for their transparency properties Journal ofNon-Crystalline Solids 288(2001):127-139
[28] George H. Beall, Linda R. Pinckney. Nano-phase Glass-ceramics Journal of the American ceramic Society. 1999, Vol.82(1):5-1
[29] 程金树，李宏等．微晶玻璃．化学工业出版社，2006年
[30] Scheidler H and Rodek E. Li_2O-Al_2O_3-SiO-2 glass ceramics. Ceram. Bull. 1989, 28:1926-1930
[31] 李磊，席淑珍．光热敏微晶玻璃的制备及其特性研究．光学精密工程．Vol．6，No．2April，1998．29-35
[32] M.Guedes, A.C.Ferro, J.M.F.Ferreira. Nucleation and crystal growth in commercial LAS composition. Journal of the European Ceramic Society 21(2001)1187-1194
[33] Katsumasa Yasukawa, Yoshitake Terashi. Crystallinity analysis of glass-ceramics by the Rietveld method Journal of the American ceramic Society. 1998 Vol. 81(11) 2978-2982
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