EXPERIMENTAL-ANALYSIS ON THE ANODIC BONDING WITH AN EVAPORATED GLASS LAYER

We performed a silicon-to-silicon anodic bonding process using a glass layer deposited by electron beam evaporation. Coming No 7740 Pyrex gl ass was used as the source material of electron evaporation. The effec ts on the bonding process were investigated as a function of the thick ness of the glass layer and the concentration of sodium ions in the gl ass layer. The surface roughness of the glass layer decreased with inc reasing thickness of the glass layer. It was observed that the deposit ed glass layers of more than 1.5 mu m thickness had very small surface roughness. The depth profile of sodium ions showed that the glass lay er deposited by electron beam evaporation contained many more sodium i ons than the glass layer deposited by sputtering. The silicon-to-silic on bonding process was performed at temperatures in the range of 135-2 40 degrees C with an electrostatic voltage in the range of 35-100 V-DC . A pull test revealed that the tensile strength of bonded specimens w as in the region of 1-8 MPa. The role of sodium ions in anodic bonding was studied by investigating the theoretical bonding mechanism and ex amining the results of secondary-ion mass spectroscopy (SIMS) analysis on the glass layer before and after the bonding process.