High-frequency bipolar transistor structure
First Claim
1. High-frequency bipolar transistor structure, comprising a base region of a first conductivity type formed in a silicon layer of a second conductivity type such that at least a portion of the base region is positioned lower in the structure than an upper surface of the silicon layer of the second conductivity type, said base region comprising an intrinsic base region having a first doping concentration surrounded by an extrinsic base region having a second doping concentration which is different than the first doping concentration, an emitter region of the second conductivity type formed inside said intrinsic base region, the extrinsic base region and the emitter region being contacted by a first polysilicon layer and by a second polysilicon layer, respectively, the first and second polysilicon layers being respectively contacted by a base metal electrode and by an emitter metal electrode, a silicide layer being provided between said extrinsic base region and said first polysilicon layer to reduce the extrinsic base resistance of the bipolar transistor, wherein said extrinsic base region is shallower than said intrinsic base region, and wherein at least a portion of said silicide layer is positioned lower in the structure than an upper surface of said intrinsic base region.
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Abstract
A high-frequency bipolar transistor structure includes a base region of a first conductivity type formed in a silicon layer of a second conductivity type, the base region comprising an intrinsic base region surrounded by an extrinsic base region, an emitter region of the second conductivity type formed inside the intrinsic base region, the extrinsic base region and the emitter region being contacted by a first polysilicon layer and a second polysilicon layer respectively. The first and the second polysilicon layers are respectively contacted by a base metal electrode and an emitter metal electrode. Between the extrinsic base region and the first polysilicon layer, a silicide layer is provided to reduce the extrinsic base resistance of the bipolar transistor.
19 Citations
16 Claims
- 1. High-frequency bipolar transistor structure, comprising a base region of a first conductivity type formed in a silicon layer of a second conductivity type such that at least a portion of the base region is positioned lower in the structure than an upper surface of the silicon layer of the second conductivity type, said base region comprising an intrinsic base region having a first doping concentration surrounded by an extrinsic base region having a second doping concentration which is different than the first doping concentration, an emitter region of the second conductivity type formed inside said intrinsic base region, the extrinsic base region and the emitter region being contacted by a first polysilicon layer and by a second polysilicon layer, respectively, the first and second polysilicon layers being respectively contacted by a base metal electrode and by an emitter metal electrode, a silicide layer being provided between said extrinsic base region and said first polysilicon layer to reduce the extrinsic base resistance of the bipolar transistor, wherein said extrinsic base region is shallower than said intrinsic base region, and wherein at least a portion of said silicide layer is positioned lower in the structure than an upper surface of said intrinsic base region.
- 7. Bipolar transistor structure, comprising a base region of a first conductivity type formed in a silicon layer of a second conductivity type such that at least a portion of the base region is positioned lower in the structure than an upper surface of the silicon layer of the second conductivity type, said base region comprising an intrinsic base region having a first doping concentration surrounded by an extrinsic base region having a second doping concentration which is different than the first doping concentration, an emitter region of the second conductivity type formed inside said intrinsic base region, the extrinsic base region and the emitter region being coupled to a first polysilicon layer and a second polysilicon layer, respectively, and a silicide layer being provided between said extrinsic base region and said first polysilicon layer, wherein at least a portion of said silicide layer is positioned lower in the structure than an upper surface of said intrinsic base region.
- 13. Semiconductor structure comprising a polysilicon layer, an epitaxial layer, an intrinsic base region formed in the epitaxial layer such that at least a portion of the intrinsic base region is positioned lower in the structure than an upper surface of the epitaxial layer, and a silicide layer, disposed between the polysilicon layer and the epitaxial layer so that dopants can diffuse from the polysilicon layer into the epitaxial layer via the silicide layer, wherein at least a portion of said silicide layer is positioned lower in the structure than an upper surface of said intrinsic base region.
Specification