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Front. Inform. Technol. Electron. Eng.  2013, Vol. 14 Issue (4): 244-251    DOI: 10.1631/jzus.C12MNT02
    
Low temperature Si/Si wafer direct bonding using a plasma activated method
Dong-ling Li, Zheng-guo Shang, Sheng-qiang Wang, Zhi-yu Wen
National Key Laboratory of Fundamental Science of Novel Micro/Nano Device and System Technology, Chongqing University, Chongqing 400044, China; MOE Key Laboratory of Optoelectronic Technology & Systems, Chongqing University, Chongqing 400044, China; Microsystem Research Center, Chongqing University, Chongqing 400044, China
Low temperature Si/Si wafer direct bonding using a plasma activated method
Dong-ling Li, Zheng-guo Shang, Sheng-qiang Wang, Zhi-yu Wen
National Key Laboratory of Fundamental Science of Novel Micro/Nano Device and System Technology, Chongqing University, Chongqing 400044, China; MOE Key Laboratory of Optoelectronic Technology & Systems, Chongqing University, Chongqing 400044, China; Microsystem Research Center, Chongqing University, Chongqing 400044, China
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摘要： Manufacturing and integration of micro-electro-mechanical systems (MEMS) devices and integrated circuits (ICs) by wafer bonding often generate problems caused by thermal properties of materials. This paper presents a low temperature wafer direct bonding process assisted by O2 plasma. Silicon wafers were treated with wet chemical cleaning and subsequently activated by O2 plasma in the etch element of a sputtering system. Then, two wafers were brought into contact in the bonder followed by annealing in N2 atmosphere for several hours. An infrared imaging system was used to detect bonding defects and a razor blade test was carried out to determine surface energy. The bonding yield reaches 90%–95% and the achieved surface energy is 1.76 J/m2 when the bonded wafers are annealed at 350 °C in N2 atmosphere for 2 h. Void formation was systematically observed and elimination methods were proposed. The size and density of voids greatly depend on the annealing temperature. Short O2 plasma treatment for 60 s can alleviate void formation and enhance surface energy. A pulling test reveals that the bonding strength is more than 11.0 MPa. This low temperature wafer direct bonding process provides an efficient and reliable method for 3D integration, system on chip, and MEMS packaging.

 

关键词： Low temperature;  Wafer direct bonding;  O2 plasma activation;  Surface energy;  Void formation    
Abstract: Manufacturing and integration of micro-electro-mechanical systems (MEMS) devices and integrated circuits (ICs) by wafer bonding often generate problems caused by thermal properties of materials. This paper presents a low temperature wafer direct bonding process assisted by O2 plasma. Silicon wafers were treated with wet chemical cleaning and subsequently activated by O2 plasma in the etch element of a sputtering system. Then, two wafers were brought into contact in the bonder followed by annealing in N2 atmosphere for several hours. An infrared imaging system was used to detect bonding defects and a razor blade test was carried out to determine surface energy. The bonding yield reaches 90%–95% and the achieved surface energy is 1.76 J/m2 when the bonded wafers are annealed at 350 °C in N2 atmosphere for 2 h. Void formation was systematically observed and elimination methods were proposed. The size and density of voids greatly depend on the annealing temperature. Short O2 plasma treatment for 60 s can alleviate void formation and enhance surface energy. A pulling test reveals that the bonding strength is more than 11.0 MPa. This low temperature wafer direct bonding process provides an efficient and reliable method for 3D integration, system on chip, and MEMS packaging.
Key words: Low temperature    Wafer direct bonding    O2 plasma activation    Surface energy    Void formation
收稿日期: 2012-10-08 出版日期: 2013-04-03
CLC:  TN305.7  
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Dong-ling Li
Zheng-guo Shang
Sheng-qiang Wang
Zhi-yu Wen

引用本文:

Dong-ling Li, Zheng-guo Shang, Sheng-qiang Wang, Zhi-yu Wen. Low temperature Si/Si wafer direct bonding using a plasma activated method. Front. Inform. Technol. Electron. Eng., 2013, 14(4): 244-251.

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http://www.zjujournals.com/xueshu/fitee/CN/10.1631/jzus.C12MNT02    或    http://www.zjujournals.com/xueshu/fitee/CN/Y2013/V14/I4/244

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