Seamless trench fill method utilizing sub-atmospheric pressure chemical vapor deposition technique
First Claim
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1. A method of forming a trench isolation region, comprising:
- providing a substrate having thereon a mask layer;
performing lithographic and etching processes to form an opening in said mask layer, said opening exposes a portion of said substrate;
etching said substrate through said opening, thereby forming a trench;
performing a sub-atmospheric pressure chemical vapor deposition (SACVD) process to deposit a silicon oxide layer in said trench, wherein said silicon oxide layer fills said trench and leaves a seam defect near its center;
performing a steam anneal in hydrogen/oxygen ambient and at a temperature of lower than 800°
C. to eliminate said seam defect;
wherein said steam anneal is carried out at a relatively higher hydrogen flowrate of 5–
20 L/min and oxygen flowrate of 5–
20 L/min with hydrogen-to-oxygen ratio (volumetric flowrate ratio) between 1;
2 and 3;
1; and
performing a densifying anneal process at a temperature of higher than 900°
C. to densify said silicon oxide layer.
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Abstract
A seamless trench fill method utilizing ozone-assisted sub-atmospheric pressure chemical vapor deposition (SACVD) technique is provided. After the deposition of a SACVD silicon oxide film, the substrate is subjected to a steam anneal that is performed under H2/O2 environment at a relatively lower temperature ranging between 500° C. and 800° C. for a time period of no less than 30 minutes. The seam defect in the trench is effectively eliminated by this low-temperature steam anneal. To densify the SACVD silicon oxide film, a subsequent N2 anneal is carried out at a higher temperature, for example, 1050° C.
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Citations
5 Claims
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1. A method of forming a trench isolation region, comprising:
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providing a substrate having thereon a mask layer; performing lithographic and etching processes to form an opening in said mask layer, said opening exposes a portion of said substrate; etching said substrate through said opening, thereby forming a trench; performing a sub-atmospheric pressure chemical vapor deposition (SACVD) process to deposit a silicon oxide layer in said trench, wherein said silicon oxide layer fills said trench and leaves a seam defect near its center; performing a steam anneal in hydrogen/oxygen ambient and at a temperature of lower than 800°
C. to eliminate said seam defect;
wherein said steam anneal is carried out at a relatively higher hydrogen flowrate of 5–
20 L/min and oxygen flowrate of 5–
20 L/min with hydrogen-to-oxygen ratio (volumetric flowrate ratio) between 1;
2 and 3;
1; andperforming a densifying anneal process at a temperature of higher than 900°
C. to densify said silicon oxide layer. - View Dependent Claims (2, 3, 4, 5)
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Specification