Methods of forming ohmic contacts on semiconductor devices with trench/mesa structures
AssigneeWolfspeed, Inc.
InventorsMadankumar Sampath, Sei-Hyung Ryu, Rahul R. Potera
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Abstract
A method of forming ohmic contacts on a semiconductor structure having a p-type region and an n-type region includes depositing a first metal on the n-type region, annealing the structure at a first contact anneal temperature to form a first ohmic contact on the n-type region, depositing a second metal on the first ohmic contact and on the p-type region, and annealing the structure at a second contact anneal temperature, less than the first contact anneal temperature, to form a second ohmic contact on the p-type region.
Claims30
A method of forming ohmic contacts on a semiconductor structure having a trench and a mesa adjacent the trench, the method comprising:
- forming (304) a dielectric layer in the trench;
- depositing (306) a first metal on a top surface of the mesa;
- removing (310) the dielectric layer from the trench;
- after removing the dielectric layer from the trench, annealing (312) the structure at a first contact anneal temperature to form a first ohmic contact the top surface of the mesa;
- depositing (314) a second metal on a bottom surface of the trench;
- and
- annealing (316) the structure at a second contact anneal temperature, less than the first contact anneal temperature to form a second ohmic contact to the bottom surface of the trench.
A method of forming ohmic contacts on a semiconductor structure having a trench and a mesa, the method comprising:
- forming (504) a mask on the top surface of the mesa;
- depositing (506) a first metal on the bottom surface of the trench;
- removing (510) the mask from the mesa;
- annealing (512) the structure at a first contact anneal temperature to form an ohmic contact on the bottom surface of the trench;
- depositing (514) a second metal on the top surface of the mesa;
- and
- annealing (516) the structure at a second contact anneal temperature that is less than the first contact anneal temperature to form a second ohmic contact to the top surface of the mesa.
A semiconductor device, comprising:
- a first silicon carbide region having a first conductivity type;
- a second silicon carbide region having a second conductivity type;
- a first ohmic contact to the first silicon carbide region, wherein the first ohmic contact comprises a first metal layer directly on the first silicon carbide region and a second metal layer on the first metal layer;
- and
- a second ohmic contact to the second silicon carbide region, wherein the second ohmic contact comprises the second metal layer directly on the second silicon carbide region.
A method of forming ohmic contacts on a semiconductor structure having a p-type region and an n-type region, the method comprising:
- depositing (204) a first metal on the n-type region;
- annealing (210) the structure at a first contact anneal temperature to form a first ohmic contact on the n-type region;
- depositing (212) a second metal on the first ohmic contact and on the p-type region;
- and
- annealing (214) the structure at a second contact anneal temperature, less than the first contact anneal temperature to form a second ohmic contact on the p-type region.
Dependencies are inferred from the claim text.