Finishing method for a silicon on insulator substrate
View Patent ↗The invention relates to a finishing method for a silicon-on-insulator (SOI) substrate that includes an oxide layer buried between an active silicon layer and a support layer of silicon. The method includes applying the following steps in succession: a first rapid thermal annealing (RTA) of the SOI substrate; a sacrificial oxidation of the active silicon layer of the substrate conducted to remove a first oxide thickness; a second RTA of the substrate; and a second sacrificial oxidation of the active silicon layer conducted to remove a second oxide thickness that is thinner than the first oxide thickness.
1. A finishing method for a silicon-on-insulator (SOI) substrate to reduce flaking formation, the method comprising an oxide layer buried between an active silicon layer and a support layer comprising silicon, which comprises applying the following steps in succession:
a first rapid thermal annealing (RTA) of the SOI substrate;
a sacrificial oxidation of the active silicon layer of the substrate conducted to remove a first oxide thickness;
a second RTA of the substrate; and
a second sacrificial oxidation of the active silicon layer conducted to remove a second oxide thickness that is thinner than the first oxide thickness;
wherein at least one of the first and second RTA steps is conducted in a non-oxidizing atmosphere at a temperature of between 900° C. and 1300° C. for a time of less than three minutes.
2. The method according to claim 1 , wherein the finishing does not include any additional sacrificial oxidation step after the second sacrificial oxidation step.
3. The method according to claim 1 , wherein the first removed oxide thickness is more than 150 nm, and the second removed oxide thickness is less than 150 nm.
4. The method according to claim 1 , wherein the first removed oxide thickness is more than 200 nm.
5. The method according to claim 1 , wherein the first removed oxide thickness is more than 300 nm.
6. The method according to claim 1 , wherein the second removed oxide thickness is less than 130 nm.
7. The method according to claim 1 , wherein the second removed oxide thickness is close to 120 nm.
8. The method according to claim 1 , wherein the first or second sacrificial oxidation steps or both comprise thermal oxidation conducted at a temperature of between 700° C. and 1100° C.
9. The method according to claim 1 , wherein the first or second sacrificial oxidation steps or both comprise de-oxidation with acid.
10. A finishing method for reducing flaking formation in a silicon-on-insulator (SOI) substrate comprising an oxide layer buried between an active silicon layer and a support layer comprising silicon, which method comprises:
applying the following steps in succession:
a first rapid thermal annealing (RTA) of the SOI substrate conducted in a non-oxidizing atmosphere at a temperature of between 900° C. and 1300° C. for a time of less than three minutes;
a sacrificial oxidation of the active silicon layer of the substrate conducted to remove a first oxide thickness of more than 300 nm;
a second RTA of the substrate conducted in a non-oxidizing atmosphere at a temperature of between 900° C. and 1300° C. for a time of less than three minutes; and
a second sacrificial oxidation of the active silicon layer conducted to remove a second oxide thickness of less than 130 nm.
11. The method according to claim 10 , wherein the first or second sacrificial oxidation steps or both comprise thermal oxidation conducted at a temperature of between 700° C. and 1100° C.
12. The method according to claim 10 , wherein the first or second sacrificial oxidation steps or both comprise de-oxidation with acid.