A silicon wafer direct bonding with a thin SiO2 layer at the interface was investigated. An atomic force microscope （AFM） was employed to characterize the surface roughness and a shearing test was carried out to eva...A silicon wafer direct bonding with a thin SiO2 layer at the interface was investigated. An atomic force microscope （AFM） was employed to characterize the surface roughness and a shearing test was carried out to evaluate the bonding strength. Experiments were performed to analyze the relations of surface roughness and bonding strength with the thickness of SiO2 which was grown by thermal oxidation and plasma enhanced chemical vapor deposition （PECVD） respectively. The bonding strength can reach up to 18 MPa for thermal oxidation and 8 MPa for PECVD after a 2-h 400℃ annealing. Results indicate that the bonding strength is negatively correlated to the thickness of SiO2 at the interface, which is important in designing the MEMS-based devices and other devices built with wafer direct bonding.展开更多
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 present...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 02 plasma. Silicon wafers were treated with wet chemical cleaning and subsequently activated by 02 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 eli-mination 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.展开更多
基金Project supported by the Key Program of the National Natural Science Foundation of China(No.61334008)the National Natural Science Foundation of China(No.61376072)
文摘A silicon wafer direct bonding with a thin SiO2 layer at the interface was investigated. An atomic force microscope （AFM） was employed to characterize the surface roughness and a shearing test was carried out to evaluate the bonding strength. Experiments were performed to analyze the relations of surface roughness and bonding strength with the thickness of SiO2 which was grown by thermal oxidation and plasma enhanced chemical vapor deposition （PECVD） respectively. The bonding strength can reach up to 18 MPa for thermal oxidation and 8 MPa for PECVD after a 2-h 400℃ annealing. Results indicate that the bonding strength is negatively correlated to the thickness of SiO2 at the interface, which is important in designing the MEMS-based devices and other devices built with wafer direct bonding.
基金Project supported by the Foreign Cultural and Educational Experts Employing Plan,Ministry of Education,China (No. TS2010CQDX 056)the Fundamental Research Funds for the Central Universi-ties,China (No. CDJZR12135502)
文摘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 02 plasma. Silicon wafers were treated with wet chemical cleaning and subsequently activated by 02 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 eli-mination 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.
