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US 2013/0075741 A1Published application
Lateral PNP Bipolar Transistor Formed with Multiple Epitaxial Layers
AssigneeAlpha and Omega Semiconductor Incorporated
InventorsShekar Mallikarjunaswamy, François Hébert
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Abstract
A lateral bipolar transistor with deep emitter and deep collector regions is formed using multiple epitaxial layers of the same conductivity type. Deep emitter and deep collector regions are formed without the use of trenches. Vertically aligned diffusion regions are formed in each epitaxial layer so that the diffusion regions merged into a contiguous diffusion region after annealing to function as emitter or collector or isolation structures. In another embodiment, a lateral trench PNP bipolar transistor is formed using trench emitter and trench collector regions. In yet another embodiment, a lateral PNP bipolar transistor with a merged LDMOS transistor is formed to achieve high performance.
Claims15
A lateral bipolar transistor, comprising:
- a semiconductor substrate of a first conductivity type;
- a first buried layer of the first conductivity type and a second buried layer of the second conductivity type both formed on the substrate, the second conductivity type being opposite the first conductivity type;
- and
- two or more epitaxial layers of the second conductivity type formed successively on the substrate, each epitaxial layer including two or more diffusion regions formed therein, the diffusion regions formed in one epitaxial layer being in vertical alignment with the diffusion regions formed in an adjacent epitaxial layer,
- wherein a first set of diffusion regions in vertical alignment forms a contiguous diffusion region of the first conductivity type and functions as an emitter region, and a second set of diffusion regions in vertical alignment forms a contiguous diffusion region of the first conductivity type and functions as a collector region, a base region being formed in the one or more epitaxial layers between the emitter and collector regions.
2 more elements
A lateral bipolar transistor, comprising:
- a semiconductor substrate of a first conductivity type;
- a first buried layer of the first conductivity type and a second buried layer of the second conductivity type both formed on the substrate, the second conductivity type being opposite the first conductivity type;
- a first epitaxial layer of the second conductivity type formed on the substrate;
- third, fourth, and fifth buried layers of the first conductivity type formed in the first epitaxial, the third buried layer being formed in vertical alignment with the first buried layer, the fourth and fifth buried layers being formed above the second buried layer;
- a second epitaxial layer of the second conductivity type formed on the first epitaxial layer;
- and
- first, second and third sinker regions of the first conductivity type formed in the second epitaxial layer, the first sinker region being in vertical alignment with the third buried layer, the second sinker region being in vertical alignment with the fourth buried layer, and the third sinker region being in vertical alignment with the fifth buried layer,
- wherein the first buried layer, the third buried layer and the first sinker region form a contiguous diffusion region of the first conductivity type and function as an isolation structure, the fourth buried layer and the second sinker region form a contiguous diffusion region of the first conductivity type and function as an emitter region, the fifth buried layer and the third sinker region form a contiguous diffusion region of the first conductivity type and function as an collector region, a base region being formed in the first and second epitaxial layers between the emitter and collector regions.
5 more elements
A method for fabricating a lateral bipolar transistor, comprising:
- providing a semiconductor substrate of a first conductivity type;
- forming a first buried layer of the first conductivity type and a second buried layer of a second conductivity type in the substrate, the second conductivity type being opposite the first conductivity type;
- forming one or more epitaxial layer of the second conductivity type successively on the substrate;
- forming two or more diffusion regions in each epitaxial layer, the diffusion regions formed in one epitaxial layer being in vertical alignment with the diffusion regions formed in an adjacent epitaxial layer;
- and
- annealing the semiconductor substrate and the one or more epitaxial layer,
- wherein a first set of diffusion regions in vertical alignment forms a contiguous diffusion region of the first conductivity type and functions as an emitter region, and a second set of diffusion regions in vertical alignment forms a contiguous diffusion region of the first conductivity type and functions as a collector region, a base region being formed in the one or more epitaxial layers between the emitter and collector regions.
4 more elements
A lateral bipolar transistor, comprising:
- a semiconductor substrate of a first conductivity type;
- an epitaxial layer of a second conductivity type formed on the substrate, the second conductivity type being opposite the first conductivity type;
- a first buried layer of the second conductivity type formed between the substrate and the epitaxial layer;
- first and second trenches formed in the epitaxial layer, the trenches being filled with at least a polysilicon layer being doped with dopants of the first conductivity type;
- and first and second diffusion regions of the first conductivity type formed in the epitaxial layer surrounding sidewalls of respective first and second trenches, the polysilicon layer of each trench being in electrical contact with the respective diffusion region surrounding sidewalls of the respective trench;
- and
- a gate conductor layer formed over a gate dielectric formed over the epitaxial layer, the gate conductor layer being formed between the first and second trenches,
- wherein an emitter region is formed in the first trench and the first diffusion region, a collector region is formed in the second trench and the second diffusion region, the base region being formed in the epitaxial layer between the first and second diffusion regions associated with the first and second trenches.
5 more elements
A lateral bipolar transistor, comprising:
- a semiconductor substrate of a first conductivity type;
- an epitaxial layer of a second conductivity type formed on the substrate, the second conductivity type being opposite the first conductivity type;
- a first buried layer of the second conductivity type formed between the substrate and the epitaxial layer;
- a well region of first conductivity type formed in the epitaxial layer;
- a first trench formed in the epitaxial layer and a second trench formed in the well region of the epitaxial layer, the trenches being filled with at least a polysilicon layer being doped with dopants of the first conductivity type;
- and first and second diffusion regions of the first conductivity type formed in the epitaxial layer surrounding sidewalls of respective first and second trenches, the polysilicon layer of each trench being in electrical contact with the respective diffusion region surrounding sidewalls of the respective trench;
- a field oxide layer formed in the well region and adjacent the second trench;
- a gate conductor layer formed over a gate dielectric formed over the epitaxial layer and extends over the field oxide layer, the gate conductor layer being formed between the first and second trenches,
- wherein an emitter region is formed in the first trench and the first diffusion region, a collector region is formed in the second trench and the second diffusion region, the base region being formed in the epitaxial layer between the first diffusion region associated with the first trench and the well region.
6 more elements
Dependencies are inferred from the claim text.