Bipolar device having buried contacts
View Patent ↗This disclosure, in one aspect, provides a method of manufacturing a semiconductor device that includes forming a collector for a bipolar transistor within a semiconductor substrate, forming a base within the collector, forming a patterned isolation layer over the collector and base, forming an emitter layer over the patterned isolation layer, forming an isolation layer over the emitter layer, patterning the patterned isolation layer, the emitter layer and the isolation layer to form at least one emitter structure having an isolation region located on a sidewall thereof, and forming a buried contact in the collector to a depth sufficient to adequately contact the collector.
1. A method of manufacturing a semiconductor device, comprising:
forming a collector for a bipolar transistor within a semiconductor substrate, wherein the collector excludes a collector tub;
forming an isolation region under the collector;
forming a contact trench within the collector;
forming a diffusion buried contact region within the trench, at least a portion of the diffusion buried contact region located within the trench and extending along sidewalls of the trench, the diffusion buried contact region extending into the collector to a depth sufficient to contact and make electrical connection with the collector
forming a base within the collector;
forming at least first and second bipolar transistor emitter structures on a surface of the semiconductor substrate and over the base and the collector and having a common base contact region located in the base and between the at least first and second bipolar transistors;
and
forming a contact plug that extends into the collector to the depth to contact the diffusion buried contact region within the trench.
2. The method recited in claim 1 , wherein the diffusion buried contact region is formed subsequent to forming the at least first and second bipolar transistor emitter structures.
3. The method recited in claim 1 , wherein forming the diffusion buried contact region includes forming the trench within the collector to a depth of at least about 0.050 microns.
4. The method recited in claim 3 , wherein the trench is formed using an etch process that patterns the at least first and second bipolar transistor emitter structures over the collector.
5. The method recited in claim 1 , wherein the depth extends to a peak concentration region of the collector.
6. The method recited in claim 5 , wherein a depth of the peak concentration ranges from about 4 microns to about 9 microns from an upper surface of the semiconductor substrate.
7. The method recited in claim 1 , wherein the at least first and second bipolar transistor emitter structures form a portion of vertical bipolar transistors.
8. The method recited in claim 1 , wherein forming the buried contact includes forming an opening in an oxide layer located over the collector, the opening exposing a surface of the semiconductor substrate.
9. The method recited in claim 8 , wherein the buried contact is formed through an oxide isolation region located over the collector.
10. The method recited in claim 1 , further includes forming a plurality of bases and emitters for a plurality of bipolar transistors, wherein the bipolar transistors form a portion of an integrated circuit and the method further includes:
forming non-bipolar transistors over the semiconductor substrate;
forming dielectric layers over the non-bipolar transistors and bipolar transistors; and
forming interconnects in the dielectric layers that electrically connect the non-bipolar and bipolar transistors, wherein a portion of the interconnects forms a portion of each the buried contact associated with each of the plurality of bipolar transistors.