The accumulation channel driven bipolar transistor (ACBT): a new MOS-gated semiconductor power device

A new power device called the Accumulation Channel driven Bipolar Transistor (ACBT) which has no parasitic thyristor is described in this paper. Unlike previous MOS-gate devices without a P-base region, the potential barrier to the flow of electrons from N⁺ emitter into N-drift region in the ACBT is created using the built-in potential of a P-N junction formed along the sidewall and bottom of a shallow trench. The potential barrier height is sufficiently large even at high collector voltages to prevent the direct injection of electrons from N ⁺ emitter into the N-drift region. An accumulation layer formed along the deep trench sidewall (when the n-channel MOSFET in the ACBT is turned-on) is the only path for electrons to enter into the N-drift region. This results in high voltage current saturation with wide FBSOA for the ACBT. The ACBT has been successfully fabricated using a unique, self-aligned double trench process