Mechanism of forming a trench structure
Embodiments of a mechanism for forming a shallow trench isolation (STI) structure filled with a flowable dielectric layer are provided. The mechanism involves using one or more low-temperature thermal anneal processes with oxygen sources and one or more microwave anneals to convert a flowable dielectric material to silicon oxide. The low-temperature thermal anneal processes with oxygen sources and the microwave anneals are performed at temperatures below the ranges that could cause significant dopant diffusion, which help dopant profile control for advanced manufacturing technologies. In some embodiments, an implant to generate passages in the upper portion of the flowable dielectric layer is also used in the mechanism.
1. A method of forming a shallow trench isolation (STI) structure, the method comprising:
lining a trench of a substrate;
depositing a flowable dielectric layer in the trench;
curing the flowable dielectric layer;
after the curing, performing a wet thermal anneal, the wet thermal anneal being a low temperature thermal anneal; and
performing a dry thermal anneal, the dry thermal anneal being a microwave anneal.
2. The method of claim 1 , wherein curing the flowable dielectric layer comprises using either O 3 or steam.
3. The method of claim 1 , further comprising, after curing the flowable dielectric layer and prior to performing the wet thermal anneal, creating channels in the flowable dielectric layer, wherein creating the channels is performed by an implant process, a plasma treatment process, or a laser beam process.
4. The method of claim 3 , wherein creating channels comprises implanting one of H atoms or He atoms.
5. The method of claim 1 , wherein an anneal temperature of the wet thermal anneal is in a range from about 200° C. to about 400° C.
6. The method of claim 1 , wherein the wet thermal anneal is performed with an oxygen source, and wherein the oxygen source is steam or H 2 O 2 .
7. The method of claim 1 , wherein the wet thermal anneal is a substantially isothermal process.
8. The method of claim 1 , wherein the wet thermal anneal is performed at a first temperature for a first time period and at a second temperature for a second time period, wherein the second temperature is higher than the first temperature.
9. The method of claim 1 , wherein during the dry thermal anneal, a temperature of the substrate is a first temperature and a temperature of the flowable dielectric layer is a second temperature, wherein the second temperature is about two times greater than the first temperature.
10. The method of claim 1 , wherein as deposited, the flowable dielectric layer includes an SiONH network, and wherein the wet thermal anneal and the dry thermal anneal convert the SiONH network into an SiO network.
11. The method of claim 1 , further comprising:
planarizing to remove the flowable dielectric layer outside the trench;
performing a second wet thermal anneal after the planarizing; and
performing a second dry thermal anneal after the second wet thermal anneal.
12. A method of forming a shallow trench isolation (STI) structure, the method comprising:
forming an as-formed flowable dielectric layer in a trench of a substrate, the as-formed flowable dielectric layer having an SiONH network;
curing the as-formed flowable dielectric layer with an oxygen source;
after the curing, creating passages in the as-formed flowable dielectric layer;
converting the SiONH network of the as-formed flowable dielectric layer into a SiOH+SiO network, thereby forming a first converted flowable dielectric layer, the converting the SiONH network comprising performing a low-temperature thermal anneal;
converting the SiOH+SiO network of the first converted flowable dielectric layer into an SiO network, thereby forming a second converted flowable dielectric layer, the converting the SiOH+SiO network comprising performing a microwave anneal; and
planarizing the substrate to remove portions of the second converted flowable dielectric layer outside the trench.
13. The method of claim 12 , wherein performing the low-temperature thermal anneal comprises using an oxygen source, wherein the oxygen source in the low-temperature thermal anneal penetrates the as-formed flowable dielectric layer through the passages created in the as-formed flowable dielectric layer.
14. The method of claim 12 , wherein the curing is performed in-situ with the forming the as-formed flowable dielectric layer.
15. The method of claim 12 , wherein an anneal temperature of the low-temperature thermal anneal is in a range from about 200° C. to about 400° C.
16. The method of claim 12 , wherein forming the as-formed flowable dielectric layer comprises a spin on dielectric formation process.
17. The method of claim 12 , wherein forming the as-formed flowable dielectric layer comprises a silicon-containing precursor and a radical precursor.
18. A method of forming a shallow trench isolation (STI) structure, the method comprising:
depositing a flowable dielectric layer in a trench of a substrate;
creating passages in the flowable dielectric layer, wherein creating the passages in the flowable dielectric layer comprises performing an implant process, a plasma treatment process, or a laser beam process;
performing a first thermal anneal;
performing a second thermal anneal; and
performing a planarization process to remove excess portions of the flowable dielectric layer outside the trench.
19. The method of claim 18 , further comprising curing the flowable dielectric layer using one of ozone or steam prior to creating passages in the flowable dielectric layer.
20. The method of claim 18 , wherein the second thermal anneal comprises a microwave anneal.