Lateral bipolar transistors

1. A structure comprising:

an extrinsic base comprising at least one sidewall having a gradient concentration of semiconductor material, the extrinsic base comprising a stack of semiconductor material with a first semiconductor material, a second semiconductor material, a third semiconductor material, and an epitaxial semiconductor material comprising the at least one sidewall with the gradient concentration of the semiconductor material, the epitaxial semiconductor material extending along an entire sidewall of the first semiconductor material and the second semiconductor material, and a spacer aligned with and contacting the at least one sidewall comprising the epitaxial semiconductor material, above the second semiconductor material and surrounding the third semiconductor material of the stack of the semiconductor material, wherein the epitaxial semiconductor material comprises p-type material;

an emitter on a first side of the extrinsic base and comprising a single top sloped surface which at least partially extends above a top surface of shallow trench isolation structures and to a top surface of the epitaxial semiconductor material, the emitter directly contacts the epitaxial semiconductor material with a thickest portion of the emitter extending to and directly contacting the epitaxial semiconductor material; and

a collector on a second side of the extrinsic base and comprising a single top sloped surface which at least partially extends above the top surface of shallow trench isolation structures and to a top surface of the epitaxial semiconductor material, the collector directly contacts the epitaxial semiconductor material with a thickest portion of the collector extending to and directly contacting the epitaxial semiconductor material,

wherein the collector and emitter are bounded on a bottom surface by an underlying insulator layer, at a first side surface by the at least one sidewall having the gradient concentration of semiconductor material, at a second side surface by the shallow trench isolation structures and on a top surface by interlevel dielectric material, the interlevel dielectric material also contacts the at least one sidewall and is above the extrinsic base.

2. The structure of claim 1 , wherein the emitter is a raised emitter and the collector is a raised collector, and the emitter and the collector covering the at least one sidewall with a first height and extending to the shallow trench isolation structures with a second height that is lower than the first height.

3. The structure of claim 1 , wherein the emitter and the collector each comprise a first semiconductor material and the gradient concentration of semiconductor material comprises a different semiconductor material than the first semiconductor material, and emitter and the collector directly contact the at least one sidewall.

4. The structure of claim 3 , wherein the emitter and the collector comprise Si material and the semiconductor material comprises SiGe material with a gradient concentration of Ge.

5. The structure of claim 4 , wherein the Si material comprises N+Si material and the SiGe material comprises P+SiGe material.

6. The structure of claim 4 , wherein the gradient concentration of Ge ranges from about 0% to about 50%.

7. The structure of claim 1 , wherein the emitter is adjacent to the at least one sidewall and the stack of semiconductor material of the extrinsic base having a vertical sidewall.

8. The structure of claim 1 , wherein the at least one sidewall is a single sidewall comprises a width of about 2 nm to about 40 nm, and the stack of semiconductor material has a non-planar vertical sidewall profile.

9. The structure of claim 1 , wherein the third semiconductor material of the extrinsic base comprises SiGe material surrounded by sidewall spacers.

10. The structure of claim 1 , wherein the second semiconductor material comprises SiGe material and the first semiconductor material comprises Si material both of which include a recessed sidewall, and the gradient concentration of the semiconductor material is within the recessed sidewall.

11. The structure of claim 1 , wherein the at least one sidewall comprises opposing sidewalls each of which comprise the gradient concentration of semiconductor material which surrounds a core of non-gradient semiconductor material therebetween, and the third semiconductor material of the stack of semiconductor material comprising the gradient concentration, and remaining semiconductor material below the third semiconductor material not having a gradient concentration.

12. The structure of claim 1 , wherein the second semiconductor material comprises SiGe material and the first semiconductor material comprises Si material with a recess on opposing sides thereof, and the opposing sidewalls each of which comprise the gradient semiconductor material within the recess.

13. A structure comprising:

an extrinsic base comprising a first semiconductor material, a second semiconductor material and a third semiconductor material, and a sidewall of epitaxial semiconductor material extending along an entire sidewall of the first semiconductor material and the second semiconductor material, the sidewall of epitaxial semiconductor material comprising a gradient concentration of semiconductor material, the third semiconductor material comprising a gradient of concentration of semiconductor material different than the first semiconductor material, wherein the sidewall of epitaxial semiconductor material comprises p-type material;

a sidewall spacer above and aligned with the sidewall and surrounding the third semiconductor material above the second semiconductor material;

a raised emitter comprising the first semiconductor material on a first side of the extrinsic base and a single top sloped surface which at least partially extends above a top surface of shallow trench isolation structures and to a top surface of the epitaxial semiconductor material, the raised emitter covering the sidewall with a first height and extending to the shallow trench isolation structures with a second height that is lower than the first height, the raised emitter directly contacts the epitaxial semiconductor material with a thickest portion of the raised emitter extending to and directly contacting the epitaxial semiconductor material; and

a raised collector of the first semiconductor material on a second side of the extrinsic base and a single top sloped surface which at least partially extends above the top surface of shallow trench isolation structures and to a top surface of the epitaxial semiconductor material, the raised collector covering the sidewall with a first height and extending to the shallow trench isolation structures with a second height that is lower than the first height, the raised collector directly contacts the epitaxial semiconductor material with a thickest portion of the raised collector extending to and directly contacting the epitaxial semiconductor material,

wherein the raised collector and raised emitter are bounded on a bottom surface by an underlying insulator layer, at a first side surface by the at least one sidewall having the gradient concentration of semiconductor material, at a second side surface by the shallow trench isolation structures and on a top surface by interlevel dielectric material, the interlevel dielectric material also contacts the at least one sidewall and is above the extrinsic base.

14. The structure of claim 13 , wherein the first semiconductor material comprises Si material and the second semiconductor material comprises SiGe material, wherein the raised emitter and the raised collector directly contact the sidewall.

15. The structure of claim 14 , wherein the gradient concentration of the second semiconductor material comprises a gradient concentration of Ge material.

16. The structure of claim 15 , wherein the gradient concentration of the Ge material comprises about 0% to 50%.

17. The structure of claim 15 , further comprising a recess in the first semiconductor material and the second semiconductor material, and the sidewall with the gradient concentration is within the recess.

18. The structure of claim 13 , wherein the raised emitter and the raised collector directly contact the sidewall.

19. The structure of claim 13 , wherein the extrinsic base comprising opposing sidewalls with the gradient concentration of the second semiconductor material.

20. A method comprising:

forming an extrinsic base comprising at least one sidewall having a gradient concentration of semiconductor material, the extrinsic base comprising a stack of semiconductor material with a first semiconductor material, a second semiconductor material, a third semiconductor material, and an epitaxial semiconductor material comprising the at least one sidewall with the gradient concentration of the semiconductor material, the epitaxial semiconductor material extending along an entire sidewall of the first semiconductor material and the second semiconductor material, and a spacer aligned with and contacting the at least one sidewall comprising the epitaxial semiconductor material, above the second semiconductor material and surrounding the third semiconductor material of the stack of the semiconductor material, wherein the epitaxial semiconductor material comprises p-type material;

forming an emitter on a first side of the extrinsic base and a single top sloped surface which at least partially extends above a top surface of shallow trench isolation structures and to a top surface of the epitaxial semiconductor material, the emitter directly contacts the epitaxial semiconductor material with a thickest portion of the emitter extending to and directly contacting the epitaxial semiconductor material; and

forming a collector on a second side of the extrinsic base and a single top sloped surface which at least partially extends above the top surface of shallow trench isolation structures and to a top surface of the epitaxial semiconductor material, the collector directly contacts the epitaxial semiconductor material with a thickest portion of the collector extending to and directly contacting the epitaxial semiconductor material wherein the collector and emitter are bounded on a bottom surface by an underlying insulator layer, at a first side surface by the at least one sidewall having the gradient concentration of semiconductor material, at a second side surface by the shallow trench isolation structures and on a top surface by interlevel dielectric material, the interlevel dielectric material also contacts the at least one sidewall and is above the extrinsic base.