Carbide emitter mask etch stop
AssigneeTexas Instruments Incorporated
InventorsLeland S. Swanson, Gregory E. Howard
Life of this patent
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Abstract
Bipolar transistors and methods for fabricating bipolar transistors are disclosed wherein an emitter-base dielectric stack is formed between emitter and base structures, comprising a carbide layer situated between first and second oxide layers. The carbide layer provides an etch stop for etching the overlying oxide layer, and the underlying oxide layer provides an etch stop for etching the carbide layer to form an emitter-base contact opening.
Claims39
A method of forming an emitter in a bipolar transistor, comprising:
- forming a collector region in a substrate;
- forming a base layer over at least a portion of the collector region;
- forming a first oxide layer over the base layer;
- forming a carbide layer over the first oxide layer;
- forming a second oxide layer over the carbide layer;
- selectively etching portions of the first and second oxide layers and the carbide layer to expose a portion of the base layer;
- depositing a polysilicon emitter layer over the exposed portion of the base layer;
- and
- doping at least a portion of the polysilicon emitter layer.
A method of forming an emitter-base dielectric stack in a poly emitter bipolar transistor, comprising:
- forming a first oxide layer over a base layer;
- forming a carbide layer over the first oxide layer;
- forming a second oxide layer over the carbide layer;
- selectively etching portions of the first and second oxide layers and the carbide layer to expose a portion of the base layer;
- and
- forming a polysilicon emitter structure over the second oxide layer and the exposed portion of the base layer.
30 The method of claim 20, wherein forming the carbide layer comprises depositing one of silicon carbide and boron carbide over the first oxide layer.
A method of forming an emitter in a bipolar transistor, comprising:
- forming a collector region in a substrate;
- forming a base layer over at least a portion of the collector region;
- forming an oxide layer over the base layer;
- forming a carbide layer over the oxide layer;
- selectively etching portions of the oxide and carbide layers to expose a portion of the base layer;
- depositing a polysilicon emitter layer over the exposed portion of the base layer;
- and
- doping at least a portion of the polysilicon emitter layer.
A bipolar transistor, comprising:
- a collector region;
- a base region formed in a base layer overlying the collector region;
- an emitter-base dielectric stack overlying the base layer and having an opening therein exposing a portion of the base layer, the emitter-base dielectric stack comprising a carbide layer;
- and
- an emitter poly layer overlying the emitter-base dielectric stack and an exposed portion of the base layer.
Dependencies are inferred from the claim text.