Compound finFET device including oxidized III-V fin isolator
View Patent ↗A semiconductor device includes a wafer having a bulk layer and a III-V buffer layer on an upper surface of the bulk layer. The semiconductor device further includes at least one semiconductor fin on the III-V buffer layer. The semiconductor fin includes a III-V channel portion. Either the wafer or the semiconductor fin includes an oxidized III-V portion interposed between the III-V channel portion and the III-V buffer layer to prevent current leakage to the bulk layer.
1. A method of fabricating a semiconductor device, the method comprising:
forming a III-V semiconductor stack on an upper surface of a wafer, the III-V semiconductor stack including an intermediate III-V layer interposed between an III-V channel layer and a III-V buffer layer formed on the wafer, the III-V buffer layer comprising indium (In) and extending continuously along the entire length of the wafer;
patterning the III-V channel layer to form at least one semiconductor fin on an upper surface of the intermediate III-V layer, the at least one semiconductor fin including a III-V channel portion comprising indium (In); and
oxidizing the intermediate III-V layer to form a III-V oxidation layer directly on an upper surface of the III-V buffer layer such that the III-V oxidation layer is interposed between the III-V channel portion and the III-V buffer layer such that the at least one semiconductor fin is isolated from the III-V buffer layer.
2. The method of claim 1 , further comprising removing thread dislocation located between the at least one semiconductor fin and the III-V buffer layer in response to oxidizing the intermediate III-V layer.
3. The method of claim 2 , wherein the III-V oxidation layer is configured to block current leakage between the at least one semiconductor fin and the III-V buffer layer.
4. The method of claim 3 , wherein the III-V channel layer comprises a first III-V material, the intermediate III-V layer comprises a second III-V material, and the III-V buffer layer comprises a third III-V material, the first, second, and third III-V materials each being different from one another.
5. The method of claim 4 , wherein the first III-V material comprises indium gallium arsenide (InGaAs) having a first concentration of In, the second III-V material comprises indium aluminum arsenide (InAlAs), and the third III-V material comprises InGaAs having a second concentration of indium different from the first concentration.
6. The method of claim 2 , wherein the III-V semiconductor stack further includes a III-V interface layer interposed between the III-V channel layer and the intermediate III-V layer, and
wherein patterning the III-V channel layer further includes transferring the pattern into the III-V interface such that the at least one semiconductor fin includes an interface portion on the intermediate III-V layer.
7. The method of claim 5 , wherein the III-V interface layer comprises indium phosphide (InP).
8. The method of claim 1 , wherein the III-V stack is epitaxially grown on the wafer, and the at least one fin is patterned after growing the III-V stack.
9. A method of fabricating a semiconductor device, the method comprising:
forming a III-V semiconductor stack on an upper surface of a wafer, the III-V semiconductor stack including an intermediate III-V layer interposed between an III-V channel layer and a III-V buffer layer formed on the wafer, the III-V buffer layer comprising indium (In) and extending continuously along the entire length of the wafer;
patterning the III-V channel layer to form at least one semiconductor fin including a buffer III-V portion interposed between an intermediate III-V portion and a remaining portion of the III-V buffer layer, the at least one semiconductor fin including a III-V channel portion comprising indium (In); and
selectively oxidizing the intermediate III-V portion to form a III-V oxidation layer that isolates the at least one semiconductor fin from the III-V buffer layer, the III-V oxidation layer formed directly on an upper surface of the III-V buffer layer such that the III-V oxidation layer is interposed between the III-V channel portion and the III-V buffer layer.
10. The method of claim 9 , further comprising removing thread dislocation located between the at least one semiconductor fin and the III-V buffer layer in response to oxidizing the intermediate III-V portion.
11. The method of claim 10 , wherein the oxidized intermediate III-V portion is configured to block current leakage between the at least one semiconductor fin and the III-V buffer layer.
12. The method of claim 3 , wherein the III-V channel layer comprises a first III-V material, the intermediate III-V layer comprises a second III-V material, and the III-V buffer layer comprises a third III-V material, the first, second, and third III-V materials each being different from one another.
13. The method of claim 12 , wherein forming the at least one semiconductor fin comprises:
performing a first etching process selective to the second III-V material to expose the intermediate III-V layer; and
performing a second timed etching process that etches through the intermediate III-V layer and partially recesses the III-V buffer layer to form the III-V buffer portion.
14. The method of claim 13 , wherein the first III-V material comprises indium gallium arsenide (InGaAs) having a first concentration of In, the second III-V material comprises indium aluminum arsenide (InAlAs), and the third III-V material comprises InGaAs having a second concentration of indium different from the first concentration.
15. The method of claim 1 , wherein the III-V stack is epitaxially grown on the wafer, and the at least one fin is patterned after growing the III-V stack.