Jayant K. Bhagat

Bonding of silicon to silicon by solid-phase epitaxy

Using concepts of solid‐phase epitaxy, a sealed and structurally sound bond between two silicon wafers has been achieved with aluminum, platinum silicide, or germanium as the transport medium. Only in the case of aluminum did microprobe analysis show an interface clear of the bonding medium. The bond quality was tested by bonding wafers of different crystal orientation and then intentionally cleaving and fracturing the bonded wafers. A clean fracture was obtained without the wafers falling apart. Leak test of sealed cavities suggests that a hermetically sealed enclosure can be achieved with this technique.

Regenerative switching in V-groove metal oxide semiconductor field-effect transistor structure

Abstract Anomalous regenerative switching has been observed in a power V-groove MOSFET with the drain terminal of the MOSFET at the top surface of the chip. This switching phenomenon is attributed to a rectifying junction formed at the drain terminal due to a thin oxide between the drain metal and the n -type drain diffusion. Because of the regenerative switching, the device characteristic changes from the MOSFET I ( V ) characteristic to a turned-on thyristor characteristic as the gate voltage is increased to a critical voltage. The ON-resistance of the device in the thyristor mode is found to be one-tenth of that in the MOSFET mode. Based on the explanation of the experimental results, an insulated gate controlled thyristor structure with substrate as the cathode is proposed.