Silicon oxide layer for oxidation resistance and method forming same
View Patent ↗An integrated circuit structure includes a bulk semiconductor region, a first semiconductor strip over and connected to the bulk semiconductor region, and a dielectric layer including silicon oxide therein. Carbon atoms are doped in the silicon oxide. The dielectric layer includes a horizontal portion over and contacting a top surface of the bulk semiconductor region, and a vertical portion connected to an end of the horizontal portion. The vertical portion contacts a sidewall of a lower portion of the first semiconductor strip. A top portion of the first semiconductor strip protrudes higher than a top surface of the vertical portion to form a semiconductor fin. The horizontal portion and the vertical portion have a same thickness. A gate stack extends on a sidewall and a top surface of the semiconductor fin.
1. A method comprising:
etching a semiconductor substrate to form a trench;
forming a first dielectric layer through an Atomic Layer Deposition (ALD) cycle, wherein the first dielectric layer extends into the trench, and wherein the ALD cycle comprises:
pulsing Hexachlorodisilane (HCD) to the semiconductor substrate;
purging the HCD;
after the purging the HCD, pulsing triethylamine to the semiconductor substrate; and
purging the triethylamine;
performing an anneal process on the first dielectric layer, wherein the anneal process comprises:
a low-temperature wet anneal process performed at a first temperature;
a high-temperature wet anneal process performed at a second temperature higher than the first temperature; and
a dry anneal process performed at a third temperature higher than the first temperature;
forming a second dielectric layer over the annealed first dielectric layer, wherein the forming the second dielectric layer is performed using a method different from a method for forming the first dielectric layer; and
performing a planarization process, wherein in the planarization process, both of the first dielectric layer and the second dielectric layer are polished, and wherein a remaining portion of the annealed first dielectric layer forms a portion of an isolation region.
2. The method of claim 1 , wherein the pulsing and purging HCD, and the pulsing and purging triethylamine collectively form a sub ALD cycle in the ALD cycle, wherein the ALD cycle comprises a plurality of sub ALD cycles, and wherein the ALD cycle further comprises, after the plurality of ALD cycles: pulsing oxygen (O 2 ) to the semiconductor substrate; and
purging the oxygen, wherein no pulsing oxygen is performed between the plurality of sub ALD cycles.
3. The method of claim 2 further comprising repeating the ALD cycle that comprises the pulsing oxygen.
4. The method of claim 3 , wherein the forming the second dielectric layer is performed using flowable chemical vapor deposition.
5. The method of claim 1 further comprising, before the first dielectric layer is deposited, depositing an isolation liner extending into the trench using a method different from a method for forming the first dielectric layer.
6. The method of claim 1 , wherein the first dielectric layer fills an entirety of the trench.
7. The method of claim 1 , further comprising, after the planarization process, recessing the first dielectric layer to form a recess, wherein both of a first sidewall of the semiconductor substrate and a second sidewall of the second dielectric layer are exposed to the recess.
8. The method of claim 1 , wherein the forming the second dielectric layer is performed using chemical vapor deposition.
9. A method comprising:
depositing a first dielectric layer on a sidewall and a top surface of a first semiconductor strip, wherein the depositing the first dielectric layer comprises a plurality of Atomic Layer Deposition (ALD) cycles, and wherein the first dielectric layer comprises SiOCN;
after the plurality of ALD cycles, performing an anneal process on the first dielectric layer, wherein the first dielectric layer is converted into a silicon oxide liner by the anneal process, and wherein the anneal process comprises:
a low-temperature wet anneal process performed at a first temperature;
a high-temperature wet anneal process performed at a second temperature higher than the first temperature; and
a dry anneal process performed at a third temperature;
after the anneal process, forming a second dielectric layer over the silicon oxide liner; and
performing a planarization process on the second dielectric layer and the silicon oxide liner to form a Shallow Trench Isolation (STI) region, wherein the STI region comprises a portion of the second dielectric layer and a portion of the silicon oxide liner.
10. The method of claim 9 , wherein each of the plurality of ALD cycles comprises:
pulsing Hexachlorodisilane (HCD);
purging the HCD;
after the purging the HCD, pulsing triethylamine; and
purging the triethylamine.
11. The method of claim 10 , wherein each of the plurality of ALD cycles further comprises:
after the triethylamine is purged, pulsing oxygen (O 2 ); and
purging the oxygen.
12. The method of claim 9 , wherein the third temperature is higher than the first temperature.
13. The method of claim 9 further comprising, before the first dielectric layer is formed, etching a semiconductor substrate to form the first semiconductor strip and a second semiconductor strip, with a trench formed between the first semiconductor strip and the second semiconductor strip, and the silicon oxide liner fills a portion of the trench.
14. The method of claim 9 , wherein the first dielectric layer has a thickness in a range between about 10 Å and about 25 Å.
15. A method comprising:
etching a semiconductor substrate to form a trench;
depositing a first dielectric layer extending into the trench using atomic layer deposition, wherein the first dielectric layer comprises SiOCN;
performing an anneal process to convert the SiOCN in the first dielectric layer into silicon oxide, wherein the anneal process comprises:
a low-temperature wet anneal process;
a high-temperature wet anneal process performed after the low-temperature wet anneal process; and
a dry anneal process performed after the high-temperature wet anneal process; and
forming a second dielectric layer over the first dielectric layer, wherein the second dielectric layer extends into the trench.
16. The method of claim 15 , wherein the first dielectric layer further comprises hydrogen.
17. The method of claim 15 , wherein the depositing the first dielectric layer comprises an Atomic Layer Deposition (ALD) cycle, and wherein the ALD cycle comprises:
pulsing Hexachlorodisilane (HCD) to the semiconductor substrate;
purging the HCD;
after the HCD is purged, pulsing triethylamine to the semiconductor substrate;
purging the triethylamine;
after the triethylamine is purged, pulsing oxygen (O 2 ); and
purging the oxygen.
18. The method of claim 15 , wherein the second dielectric layer is formed using flowable chemical vapor deposition.
19. The method of claim 15 further comprising performing a planarization process, wherein a remaining portion of the first dielectric layer forms a portion of an isolation region.
20. The method of claim 15 , wherein the first dielectric layer fills an entirety of the trench.