Littelfuse, Inc.

Ixys Corporation

Frank Ettingshausen

Elmar Wisotzki

Thomas Spann

A die stack assembly includes first and second power semiconductor device dice. The first die has a P type peripheral edge separation structure that extends from the top planar semiconductor surface of the first die all the way to the bottom planar semiconductor surface of the die, and that is doped at least in part with aluminum. The backside of the first die is mounted to the backside of the second die. A metal feature that is not covered with passivation, and that can serve as a bonding pad, is disposed on part of the peripheral edge separation structure. A metal member (for example, a bond wire or metal clip) contacts the metal feature such that an electrical connection is established from the metal member, through the metal feature, through the peripheral edge separation structure of the first die, and to an electrode of the second die.

Die stack assembly using an edge separation structure for connectivity through a die of the stack

A packaged inverse diode device exhibits superior commutation robustness. The device includes a stack of inverse diodes disposed within a housing. Each adjacent pair of inverse diodes is bonded together by an intervening DMB (Direct Metal Bonded) substrate structure. At one end of the stack of diode dice and DMB substrate structures is attached a first metal terminal. A second metal terminal is attached to the other end of the stack. The two terminals serve as package terminals of the overall device. In a novel method, the device undergoes severe commutation. A large forward current is made to flow through the diode stack, followed by a rapid reversal of the voltage across the stack to a large reverse polarity voltage. Despite a substantial rate of change of the commutation current at the onset of the reverse voltage condition, the inverse diode device is not damaged.

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Darmstadt, Germany

Frank Ettingshausen