Katsujiro Tanzawa

Silicon‐to‐silicon direct bonding method

It was found that strong bonding takes place when a pair of clean, mirror‐polished silicon surfaces are contacted at room temperature after hydrophilic surface formation. Bonding strength reaches the fracture strength of silicon bulk after heating above 1000 °C. Electric resistivity at the interface is less than 10−6 Ω/cm2. Bonding p‐type silicon to n‐type silicon forms a diode. The reaction between silanol groups formed on the surface may cause the bonding force. Heating above 1000 °C was thought to diffuse oxygen to inside the silicon bulk, forming an epitaxial‐like lattice continuity at the interface.

Surface Charge Studies on Lead Borosilicate Glass Containing Trace Sodium

Surface charge studies of lead borosilicate glass containing from a few to about 100 ppm alkalis by C-V characteristic measurements of MGS capacitors, together with the stability test of glass-passivated diodes, show positive surface charge formation by alkali ions. The surface charge shifts under BT treatment of both bias polarities increase with alkali content increase. The shift by +BT is thought to be caused by alkali ion accumulation in the glass-to-silicon interface, while negative charges, formed by alkali ion additions, may be considered to migrate and accumulate by -BT. Reducing alkali ion impurities improves high temperature stability to the level of zinc borosilicate glass.

Surface-charge properties of fluorine-doped lead borosilicate glass

Surface-charge configurations, together with stability under bias-temperature (BT) stress, for F-doped and Na-doped lead borosilicate glass were investigated by using C-V and I-V measurements on metal-glass-silicon capacitors and on diodes passivated with the glass. The C-V characteristics showed an increase in negative charge for F doping and in positive charge for Na doping. Alkali impurities in the glass mainly controlled the surface-charge shift during BT, but additional changes, similar to those for Na doping but reversing the sign of the charge, took place by F doping. The leakage current decrease in the diode passivated with F-doped glass, which contradicts the results of C-V measurement, may be due to the education of the generation current by the interaction between the silicon surface and F/sup -/ ions. >