Single conductor alloy as diffusion barrier system and simulataneous OHMIC contact to N- and P-type silicon carbide
View Patent ↗Use of a single alloy conductor to form simultaneous ohmic contacts (SOC) to n- and p-type 4H-SiC. The single alloy conductor also is an effective diffusion barrier against gold (AU) and oxygen (O 2 ) at high temperatures (e.g., up to 800° C.). The innovation may also provide an effective interconnecting metallization in a multi-level metallization device scheme.
1. A method for forming simultaneous ohmic contacts comprising:
creating a single alloy conductor comprising co-sputtered PtTi by phase segregation annealing (PSA); and
applying the single alloy conductor to a substrate comprising 4H-SiC having a p-type portion and an n-type portion, wherein the single alloy conductor stablishes the simultaneous ohmic contacts.
2. The method of claim 1 , wherein the single alloy conductor forms a film.
3. The method of claim 1 , wherein the single alloy conductor comprises Pt80-Ti20.
4. The method of claim 1 , wherein the single alloy conductor comprises Pt70-Ti30.
5. The method of claim 1 , further comprising:
depositing and patterning a diffusion barrier comprising a layer of single alloy conductor, wherein the layer is about 200 nm thick; and
annealing in ambient argon.
6. The method of claim 5 , wherein annealing takes place at about 700° C. for about 30 minutes.
7. The method of claim 5 , wherein the patterning comprises using an aluminum layer as the contact mask for pattern etching.
8. The method of claim 1 wherein PSA is achieved by annealing the single alloy conductor by vacuum RTA.
9. The method of claim 8 , further comprising annealing another layer of the single alloy conductor in argon.
10. The method of claim 9 , further comprising adding a sputtered capping layer.
11. The method of claim 10 , wherein the capping layer comprises Au.