Seamless trench fill method utilizing sub-atmospheric pressure chemical vapor deposition technique

• US 7,238,586 B2
• Filed: 07/21/2005
• Issued: 07/03/2007
• Est. Priority Date: 07/21/2005
• Status: Active Grant

• Current Assignee: United Microelectronics Corporation
• Original Assignee: United Microelectronics Corporation
• Inventors: Chen, Neng-Kuo, Tsai, Teng-Chun, Hsu, Shao-Ta
• Primary Examiner(s): Kebede; Brook
• Assistant Examiner(s): Parker; John M
• Application Number:
  US11/161,074
• Publication Number:
  US 20070020875A1
• Time in Patent Office: 712 Days
• Field of Search: 438/424, 438/438, 438/FOR.277, 257/E21.546
• US Class Current: 438/424
• CPC Class Codes: H01L 21/76224 using trench refilling with dielectric materials trench filling with polycristalline silicon H01L21/763; together with vertical isolation, e.g. trench refilling in a SOI substrate H01L21/76264

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.

Claims

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.

2. The method of forming a trench isolation region according to claim 1 wherein said mask layer comprises a pad oxide layer and a silicon nitride pad layer.

3. The method of forming a trench isolation region according to claim 1 wherein said SACVD process is an ozone-assisted SACVD employing tetra-ethyl-ortho-silicate (TEOS) as a silicon source.

4. The method of forming a trench isolation region according to claim 1 wherein said steam anneal is performed for at least 30 minutes.

5. The method of forming a trench isolation region according to claim 1 wherein said steam anneal is performed at a temperature of 500–

800°

C.