Bipolar junction transistor with multiple emitter fingers
Device structures for a bipolar junction transistor and methods of fabricating a device structure for a bipolar junction transistor. A first semiconductor layer is formed on a substrate, and a second semiconductor layer is formed on the first semiconductor layer. The first semiconductor layer, the second semiconductor layer, and the substrate are etched to define first and second emitter fingers from the second semiconductor layer and trenches in the substrate that are laterally positioned between the first and second emitter fingers. The first semiconductor layer may function as a base layer in the device structure.
1. A device structure for a bipolar junction transistor formed using a substrate, the device structure comprising:
a base layer on the substrate;
a first emitter finger and a second emitter finger on the base layer; and
a plurality of first trenches in the substrate, the plurality of first trenches laterally positioned between the first emitter finger and the second emitter finger,
wherein the plurality of first trenches are arranged in a row parallel to the first emitter finger and parallel to the second emitter finger, and the base layer includes a section that is positioned between an adjacent pair of the plurality of first trenches in the row.
2. The device structure of claim 1 wherein the plurality of first trenches are filled with dielectric material to define a plurality of isolation regions.
3. The device structure of claim 1 further comprising:
a second trench in the substrate that is laterally separated from the plurality of first trenches in the substrate by a portion of the substrate defining a collector pedestal.
4. The device structure of claim 3 further comprising:
a contact region in the second trench, the contact region raised relative to respective bases of the plurality of first trenches and relative to a bottom surface of the second trench adjacent to the contact region.
5. The device structure of claim 4 further comprising:
a contact coupled with the contact region in the second trench,
wherein the contact region couples the contact in electrical contact with the collector pedestal.
6. The device structure of claim 1 further comprising:
a contact coupled with the section of the base layer.
7. The device structure of claim 1 further comprising:
a second trench in the substrate that is laterally separated from the plurality of first trenches in the substrate by a portion of the substrate defining a collector pedestal,
wherein the row including the plurality of first trenches and the second trench are aligned parallel to the first emitter finger and the second emitter finger.
8. The device structure of claim 1 wherein the plurality of first trenches extend through the base layer to define the section of the base layer.