International Rectifier Corporation

Xerox Corporation

Iftikhar Ahmed

Igor Bol

Steven A Buhler

A termination structure and reduced mask process for its manufacture for either a FRED device or any power semiconductor device comprises at least two concentric diffusion guard rings and two spaced silicon dioxide rings used in the definition of the two guard rings. A first metal ring overlies and contacts the outermost diffusion. A second metal ring which acts as a field plate contacts the second diffusion and overlaps the outermost oxide ring. A third metal ring, which acts as a field plate, is a continuous portion of the active area top contact and overlaps the second oxide ring. The termination is useful for high voltage (of the order of 1200 volt) devices. The rings are segments of a common aluminum or Palladium contact layer.

Manufacturing process for fast recovery diode

A termination structure and reduced mask process for its manufacture for either a FRED device or any power semiconductor device comprises at least two concentric diffusion guard rings and two spaced silicon dioxide rings used in the definition of the two guard rings in an implant and drive system. A first metal ring overlies and contacts the outermost diffusion. A second metal ring which acts as a field plate contacts the second diffusion and overlaps the outermost oxide ring. A third metal ring, which acts as a field plate, is a continuous portion of the active area top contact and overlaps the second oxide ring. The termination is useful for high voltage (of the order of 1200 volt) devices. The rings are segments of a common aluminum or palladium contact layer. A thin high resistivity layer of amorphous silicon is deposited over the full upper surface of the wafer and is disposed between the wafer upper surface and all of the metal rings.

High voltage termination with amorphous silicon layer below the field plate

A FRED device having an ultralow I employs a contact layer which contacts spaced P diffusions in an N type silicon substrate and also contacts the silicon surface spanning between the P diffusions. The contact layer is formed of a contact having a lower barrier height than the conventional aluminum, and is palladium silicide with a top contact layer of aluminum.

Ultra low Irr  fast recovery diode

A three layer IGBT which cannot latch on is provided with a trench gate and a Schottky contact to the depletion region surrounding the trench gate. An emitter contact is connected to base diffusion regions which are diffused into the depletion region. The depletion region is formed atop an emitter region which emits carriers into the depletion region in response to the turn on of the gate and the injection of carriers from the Schottky gate.

Latch free IGBT with schottky gate

A single mask process for manufacture of a FRED employs a thick oxide layer over an N type silicon surface and a thin nitride layer over the oxide. A single mask defines FRED device spaced P diffusions. The oxide spanning the P diffusions is laterally etched away, under the nitride layer to expose the surface of adjacent P diffusions and the spanning N type silicon surface. All nitride is then removed and a top contact layer of aluminum is applied atop the silicon surface, contacting a P guard ring diffusion; the surface of the P diffusions defining PN junctions; and the top of the N silicon to define a Schottky diode contact.

Single mask process for manufacture of fast recovery diode

A high voltage switch in which an extended SCR is built in an insulated polysilicon layer for providing a single structure high voltage switch. The high voltage SCR is built by building unit SCRs comprising a cathode, a gate, an anode and a voltage sustaining area. The unit SCRs are built as horizontal linear devices. The unit SCRs can then be combined to form a large SCR by building each unit SCR so that the anode of one SCR is at least partially contiguous with the cathode of the next unit SCR.

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Bellflower, CA, United States of America

Iftikhar Ahmed