Bipolar transistor
AssigneeHitachi, Ltd.
InventorsMasao Kondo, Katsuya Oda, Katsuyoshi Washio
Life of this patent
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Abstract
A bipolar transistor using a B-doped Si and Ge alloy for a base in which a Ge content in an emitter-base depletion region and in a base-collector depletion region is greater than a Ge content in a base layer. Diffusion of B from the base layer can be suppressed by making the Ge content in the emitter-base depletion region and in a base-collector depletion region on both sides of the base layer greater than the Ge content in the base layer since the diffusion coefficient of B in the SiGe layer is lowered as the Ge contents increases.
Claims12
A bipolar transistor using a B-doped Si and Ge alloy for a base in which the maximum value of a Ge content in an emitter-base junction depletion region and a base-collector junction depletion region is greater than an average value in a base layer,
- wherein said Ge content is changed abruptly in a vicinity of said emitter-base junction depletion region and in a vicinity of said base-collector junction depletion region,
- wherein a grade of said Ge content in a first region in which the grade of Ge content increases from a vicinity of an edge of a base layer on a collector side to the collector is greater than the grade of said Ge content in a second region disposed in the base layer and adjacent to said first region.
A bipolar transistor using a B-doped Si and Ge alloy for a base in which the maximum value of a Ge content in a base-collector junction depletion region is greater than an average value in a base layer,
- wherein a grade of said Ge content in a first region in which the grade of Ge content increases from a vicinity of an edge of the base layer on a collector side to the collector is greater than a grade of said Ge content in a second region disposed in the base layer and adjacent to said first region.
A bipolar transistor using a B-doped Si and Ge alloy for a base in which the maximum value of a Ge content in a base-collector junction depletion region is greater than an average value in a base layer, wherein
- the transistor has a region of a constant Ge content in a region from the edge of the base layer on the side of an emitter to an emitter-base junction.
Dependencies are inferred from the claim text.