Fabrication of a bipolar transistor using a sacrificial emitter
DCFirst Claim
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1. A method of fabricating a bipolar transistor, the method comprising:
- forming a sacrificial emitter over a base;
forming a first oxide layer over the sacrificial emitter;
forming a masking material over the first oxide layer;
planarizing the masking material to expose the first oxide layer;
etching a portion of the first oxide layer over the sacrificial emitter; and
removing the sacrificial emitter.
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Abstract
In one embodiment, a transistor is fabricated by forming a sacrificial emitter over a base, forming an oxide layer over the sacrificial emitter, removing a portion of the oxide layer, and then removing the sacrificial emitter. An emitter is later formed in the space formerly occupied by the sacrificial emitter. The sacrificial emitter allows a base implant step to be performed early in the process using a single masking step. The base may comprise epitaxial silicon-germanium or silicon.
19 Citations
17 Claims
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1. A method of fabricating a bipolar transistor, the method comprising:
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forming a sacrificial emitter over a base;
forming a first oxide layer over the sacrificial emitter;
forming a masking material over the first oxide layer;
planarizing the masking material to expose the first oxide layer;
etching a portion of the first oxide layer over the sacrificial emitter; and
removing the sacrificial emitter. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 12)
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10. A method of forming a bipolar transistor, the method comprising:
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implanting a dopant in a silicon-germanium (SiGe) layer that is under a sacrificial emitter;
depositing a first oxide layer over the sacrificial emitter;
forming a mask over the first oxide layer;
isotropically etching the first oxide layer to create an undercut under the mask and fully expose a top portion of the sacrificial emitter; and
replacing the sacrificial emitter with an emitter. - View Dependent Claims (11)
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13. A method of fabricating a bipolar transistor, the method comprising:
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forming a sacrificial emitter over a base;
forming a first oxide layer over the sacrificial emitter;
forming a masking material over the sacrificial emitter such that a portion of the first oxide layer is exposed;
isotropically etching the first oxide layer to create an undercut under the masking material and fully expose a top portion of the sacrificial emitter; and
removing the sacrificial emitter. - View Dependent Claims (14, 15, 16, 17)
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Specification