Motorola Corporation

John R Bender

Ali Salih

Peyman Hadizad

John David Moran

James R Washburn

A semiconductor structure (10) uses a clamp (16) disposed at an edge (27) of a dielectric structure (14) in a semiconductor device. The clamp substantially reduces the separation or peeling of the dielectric structure or layer away from the underlying semiconductor material (20,24). The clamp also provides the benefit of protecting the interface between the dielectric layer and the underlying semiconductor material from chemical or moisture attack, either during later processing or after final manufacture. Such chemical or moisture attack and internal film stress are factors leading to separation of the dielectric film from the underlying semiconductor material. The clamp is useful, for example, in preventing separation of silicon nitride or oxide passivation from gallium arsenide substrates in power rectifier diodes.

Clamp disposed at edge of a dielectric structure in a semiconductor

A GTO switch is provided in which the upper base layer (gate) is formed by a diffusion step. An epitaxial layer grown over the upper base layer contains cathode and gate diffusions which are separated by an undiffused gap. This 'buried base' technique provides precise control over the resistivity of the base. The cathode-gate gap provides increased reverse gate voltage capacity. Other features include a large anode short area and a double-layer-metal; contact structure on the cathode-gate surface.

Method of making gate turn off switch with anode short and buried base

An improved semiconductor device, particularly a gate controlled switch is provided by optimally fitting an involute spiral cathode-gate structure into a substantially square device. 4N cathode-gate branches radiate from a central gate portion and intersect the perimeter of the square device region at predetermined locations, N per side, where N is an integer. Four of the branches tangentially intercept the square perimeter at a distance R from a centerline where R is the radius of the central gate portion. The origin of the branches is angularly displaced from the line connecting the die center to the tangential intercept point by (L/R)- arctan (L/R) radians where L is half the edge length of the square device region. Improved thermal performance is obtained by thermally coupling the cathode heat spreader to the gate as well as cathode portions of the device.

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Mesa, AZ, United States of America

John R Bender