Room temperature wafer level glass/glass bonding

Abstract The findings of this study report the bonding of glass/glass wafers by using the surface activated bonding (SAB) method at room temperature (RT) without heating. In order to bond, the glass wafers were activated by a sequential plasma activation process, in which the wafers were cleaned with reactive ion etching (RIE) oxygen radio frequency (rf) plasma and nitrogen radical microwave (MW) plasma one after another and then contacted under hand-applied pressure followed by cold rolling under 20 kg load in atmospheric air. High bonding strength for glass/glass was achieved. Paramount influence of N 2 radical MW plasma on the adhesion enhancement of silicon/silicon bonding motivated the investigation of the N 2 radical MW plasma relationship with the bonding strength of glass/glass. A considerable influence of N 2 pressure on the bonding strength was not observed except in N 2 gas pressure of 30 Pa, which might be due to the debonding between glue and fixture used for tensile pulling test. No significant effect of OH density of glass wafers on the bonding strength was found below 400 °C. The result was evident from 400 °C and it was about twofold higher at 600 °C than that of RT to 400 °C. This result indicated that the sequential process bonding mechanism was consisting of long bridges of hydrogen bonding by water molecules. Significant environmental influence on the bonding strength was found and which could be correlated with OH molecules of glass wafers.

[1]  U. Gösele,et al.  Low temperature wafer direct bonding , 1994 .

[2]  B. Roberds,et al.  Chemical Free Room Temperature Wafer To Wafer Direct Bonding , 1995 .

[3]  Ryutaro Maeda,et al.  Surface activated bonding of silicon wafers at room temperature , 1996 .

[4]  T. Suga,et al.  Low temperature direct bonding of silicon and silicon dioxide by the surface activation method , 1997, Proceedings of International Solid State Sensors and Actuators Conference (Transducers '97).

[5]  John L. Crassidis,et al.  Sensors and actuators , 2005, Conference on Electron Devices, 2005 Spanish.

[6]  Jean-Pierre Raskin,et al.  Low-temperature wafer bonding optimal O-2 plasma surface pretreatment time , 2004 .

[7]  J. Lasky.  Wafer bonding for silicon‐on‐insulator technologies , 1986 .

[8]  U. Gösele,et al.  Gas development at the interface of directly bonded silicon wafers: investigation on silicon-based pressure sensors , 1996 .

[9]  D. Resnik,et al.  Study of low-temperature direct bonding of (111) and (100) silicon wafers under various ambient and surface conditions , 2000 .

[10]  T. Suga,et al.  Combined process for wafer direct bonding by means of the surface activation method , 2004, 2004 Proceedings. 54th Electronic Components and Technology Conference (IEEE Cat. No.04CH37546).

[11]  Scott Blackstone.  Recent advances in wafer bonding of silicon and alternative materials , 1999 .

[12]  B. Muller,et al.  Tensile strength characterization of low-temperature fusion-bonded silicon wafers , 1991 .

[13]  Ryutaro Maeda,et al.  Low-temperature direct bonding of silicon and silicon dioxide by the surface activation method , 1998 .

[14]  Loke Chong Lee,et al.  Low temperature glass-to-glass wafer bonding , 2003 .