Low capacitance over-voltage protection thyristor device
OwnerGeorge Templeton, James Washburninventors
Life of this patent
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Abstract
An over-voltage protection thyristor has reduced junction capacitance making it suitable for use in high bandwidth applications. The reduced capacitance is achieved through the introduction of a deep base region. The deep base region has a graded doping concentration which reduces with depth into the substrate. The thyristor is useful for protecting sensitive electrical equipment from transient surges.
Claims26
An over-voltage protection thyristor device, comprising:
- a substrate semiconductor material of a first conductivity type, the substrate having a first outer surface and a second outer surface;
- a shallow base region of a second conductivity type extending from the first outer surface into the substrate;
- an emitter of the first conductivity type extending from the first outer surface into the shallow base region, the emitter having a depth that is less than the shallow base region;
- a deep base region of the second conductivity type extending into the substrate from the second outer surface, the deep base region having a graded concentration reducing into the substrate such that the capacitance between the deep base region and the substrate is reduced.
A method of fabricating an over-voltage protection thyristor device on a substrate semiconductor material of a first conductivity type, the substrate having a having a first outer surface and a second outer surface, the method comprising the steps of:
- forming a shallow base region of a second conductivity type extending from the first outer surface into the substrate;
- forming an emitter of the first conductivity type extending from the first outer surface into the shallow base region, the emitter having a depth that is less than the shallow base region;
- forming a deep base region of the second conductivity type extending into the substrate from the second outer surface, the deep base region having a graded concentration reducing into the substrate such that the capacitance between the deep base region and the substrate is reduced.
Dependencies are inferred from the claim text.