Lateral silicon-on-insulator bipolar junction transistor process and structure
Device structures, fabrication methods, and design structures for a bipolar junction transistor. A first terminal of the bipolar junction transistor is formed from a section of a device layer of a semiconductor-on-insulator wafer. An intrinsic base of the bipolar junction transistor is formed from an epitaxially-grown section of a first semiconductor layer, which is coextensive with a sidewall of the section of the device layer. A second terminal of the bipolar junction transistor is formed from a second semiconductor layer that is coextensive with the epitaxially-grown section of the first semiconductor layer. The epitaxially-grown section of a first semiconductor layer defines a first junction with the section of the device layer, and the second semiconductor layer defines a second junction with the epitaxially-grown section of the first semiconductor layer.
1. A device structure for a bipolar junction transistor fabricated using a device layer of a semiconductor-on-insulator wafer, the device structure comprising:
a first terminal comprised of a section of the device layer, the section of the device layer having a sidewall;
an intrinsic base coextensive with the sidewall of the section of the device layer, the intrinsic base comprised of a first section of a first semiconductor layer having an epitaxial relationship with the section of the device layer and defining a first junction with the section of the device layer;
a second terminal coextensive with the intrinsic base, the second terminal comprised of a second semiconductor layer defining a second junction with the first section of the first semiconductor layer;
a first dielectric layer on a top surface of the device layer; and
an extrinsic base comprised of a third semiconductor layer on the first dielectric layer, the extrinsic base isolated from the device layer by the first dielectric layer, and wherein the first semiconductor layer has a second section that is integral with the first section and the second section extends across the first dielectric layer to couple the first section of the first semiconductor layer with the third semiconductor layer.
2. The device structure of claim 1 wherein the second semiconductor layer includes a single crystal section that has an epitaxial relationship with the first section of the first semiconductor layer.
3. The device structure of claim 1 wherein the semiconductor-on-insulator wafer includes a buried insulator layer, and a portion of the first semiconductor layer extends below the section of the device layer toward a recessed top surface of the buried insulator layer.
4. The device structure of claim 1 wherein the first terminal is a collector and the second terminal is an emitter.
5. The device structure of claim 1 wherein the first terminal is an emitter and the second terminal is a collector.
6. The device structure of claim 1 further comprising:
a second dielectric layer on a top surface of the third semiconductor layer;
a first opening in the second dielectric layer that extends to the third semiconductor layer; and
a first contact inside the first opening, the first contact coupled by the extrinsic base with the intrinsic base.
7. The device structure of claim 6 further comprising:
a second opening in the third semiconductor layer and the first dielectric layer, the second opening aligned with the first opening and extending to the device layer; and
a second contact inside the second opening, the second contact coupled with the first terminal,
wherein the second opening is smaller than the first opening.
8. The device structure of claim 1 wherein the first semiconductor layer is comprised of a first semiconductor material, and the device layer or the second semiconductor layer is comprised of a second semiconductor material with a bandgap that differs from the first semiconductor material.
9. The device structure of claim 1 wherein the first junction and the second junction are vertically aligned relative to a top surface of the device layer.