Browse Prior Art Database

System Design for Maximizing Uniformity in Selective Epitaxial Refill Processes

IP.com Disclosure Number: IPCOM000038725D
Original Publication Date: 1987-Feb-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 2 page(s) / 43K

Publishing Venue

IBM

Related People

Phan, VT: AUTHOR [+2]

Abstract

A method has been developed for achieving uniform levels of refill over a wafer during the selective epitaxial refill process. This is accomplished by eliminating local turbulent gas flow across the surface of the wafer which had contributed to the non-uniformity of the wafer. When wafers 1 (Fig. 1) were examined, it was noted that higher refill levels were obtained within the cross-hatched area 2. This area, which might amount to 15% of the wafer's surface, was at the top edge of the wafer as it sat in the susceptor tool and was the portion of the wafer first contacted by the gas flow 3 across its surface. In the refill process, the wafer 1 (Fig. 2) sits in a recess 4 in the susceptor tool 5 with the gas 3 flowing downward across the wafer.

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System Design for Maximizing Uniformity in Selective Epitaxial Refill Processes

A method has been developed for achieving uniform levels of refill over a wafer during the selective epitaxial refill process. This is accomplished by eliminating local turbulent gas flow across the surface of the wafer which had contributed to the non-uniformity of the wafer. When wafers 1 (Fig. 1) were examined, it was noted that higher refill levels were obtained within the cross-hatched area 2. This area, which might amount to 15% of the wafer's surface, was at the top edge of the wafer as it sat in the susceptor tool and was the portion of the wafer first contacted by the gas flow 3 across its surface. In the refill process, the wafer 1 (Fig. 2) sits in a recess 4 in the susceptor tool 5 with the gas 3 flowing downward across the wafer. Because of the susceptor overhang 6, local turbulent flow 7 occurs near the top of the wafer. The lower region of the wafer 8 experiences laminar flow. It was determined that the turbulence was causing the non- uniformities to occur. In the proposed method, a dummy wafer 9 (Fig. 3) is first placed

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in the recess 4 of the susceptor tool 5. This spacer positions the wafer 1 being refilled so that it extends into the gas flow 3, thereby removing the cause of the turbulence. Only laminar flow 8 occurs across the body of the wafer, and uniform refill takes place.

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