Patent US5467220A successfully refreshed from Google Patents.
US5467220A
Expired / Lapsed
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Method and apparatus for improving semiconductor wafer surface temperature uniformity
Assignee: Applied Materials Inc
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Filing: 1994-02-18
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Granted: 1995-11-14
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Expires: 2014-02-18
Abstract
Abstract In a processing chamber that includes a wafer pedestal adapted to heat and cool a wafer during wafer processing, where the wafer is secured to the pedestal with a wafer clamp ring, a yoke having a surface in spaced facing relation with a wafer surface is positioned atop the clamp ring proximate to the wafer. The yoke surface includes a concave circumferential portion that is curved to provide a reflector, for example a parabolic or elliptical reflector, that is positioned having a focal point coincident with the wafer edge. Reflector positioning and spacing relative to the wafer surface encourage reflection of heat radiated from the edge portion of the wafer surface back to the wafer edge to mitigate thermal losses at the wafer edge and improve temperature uniformity across the surface of the wafer.
Inventors
- 👤 Zheng Xu
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 02:51
CPC Classifications
H; H10; H10P; H10P72/00; H10P72/04; H10P72/0431; H10P72/0432; C; C23; C23C; C23C16/00; C23C16/44; C23C16/458; C23C16/4582; C23C16/4583; C23C16/4585; C23C16/46; C30; C30B; C30B25/00; C30B25/02; C30B25/10; C30B25/12; C30B31/00; C30B31/06; C30B31/12; H10P72/70; H10P72/76; H10P72/7604; H10P72/7606; H10P72/7616
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
115 words
An apparatus for improving thermal uniformity across a semiconductor wafer surface during wafer heating, comprising: an annular yoke having a yoke surface positioned proximate to said wafer in spaced facing relation thereto; said yoke surface defining a concave circumferential reflector; said reflector positioned proximate to and coincident with said wafer surface, wherein said reflector is positioned relative to a wafer edge to reflect thermal energy radiated from said wafer edge back thereto, and wherein said yoke is placed atop a ring-like wafer clamping assembly, such that an innermost portion of the reflector surface overhangs, and extends below an upper surface of, said clamping assembly and thereby provides maximum reflection of heat to said wafer surface.
Claim 2
Independent Claim
115 words
An apparatus for improving thermal uniformity across a semiconductor wafer surface during wafer heating, comprising: an annular yoke having a yoke surface positioned proximate to said wafer in spaced facing relation thereto; said yoke surface defining a concave circumferential reflector; said reflector positioned proximate to and coincident with said wafer surface, wherein said reflector is positioned relative to a wafer edge to reflect thermal energy radiated from said wafer edge back thereto, and wherein said yoke is placed atop a ring-like wafer clamping assembly, such that an innermost portion of the reflector surface overhangs, and extends below an upper surface of, said clamping assembly and thereby provides maximum reflection of heat to said wafer surface.
Claim 3
Dependent Claim
12 words
The apparatus of claim 1, wherein said reflector is an infrared mirror.
Claim 4
Dependent Claim
19 words
The apparatus of claim 2, wherein said infrared mirror is formed of an optically stable, highly reflective, non-oxidizing material.
Claim 5
Dependent Claim
13 words
The apparatus of claim 3, wherein said infrared mirror is formed of nickel.
Claim 6
Dependent Claim
19 words
The apparatus of claim 1, wherein said reflector is sloped to project downward below a clamping assembly upper surface.
Claim 7
Dependent Claim
20 words
The apparatus of claim 1, wherein said reflector is a parabolic reflector having a focal point at said wafer edge.
Claim 8
Dependent Claim
20 words
The apparatus of claim 1, wherein said reflector is an elliptical reflector having a focal point at said wafer edge.
Claim 9
Independent Claim
139 words
A method for improving thermal uniformity across a semiconductor wafer surface during wafer heating, comprising the steps of: positioning an annular yoke having a yoke surface proximate to said wafer in spaced facing relation thereto; said yoke defining a concave circumferential reflector; said reflector positioned proximate to and coincident with said wafer surface; wherein said yoke is placed atop a ring-like wafer clamping assembly having an open inner portion, and wherein said yoke is configured such that an innermost portion of a reflector surface overhangs, and extends below an upper surface of, said clamping assembly and thereby provides maximum reflection of heat to said wafer surface; positioning said reflector relative to a wafer edge to reflect thermal energy radiated from said wafer edge back thereto; and reflecting thermal energy radiated from said wafer surface back thereto with said reflector.
Claim 10
Independent Claim
139 words
A method for improving thermal uniformity across a semiconductor wafer surface during wafer heating, comprising the steps of: positioning an annular yoke having a yoke surface proximate to said wafer in spaced facing relation thereto; said yoke defining a concave circumferential reflector; said reflector positioned proximate to and coincident with said wafer surface; wherein said yoke is placed atop a ring-like wafer clamping assembly having an open inner portion, and wherein said yoke is configured such that an innermost portion of a reflector surface overhangs, and extends below an upper surface of, said clamping assembly and thereby provides maximum reflection of heat to said wafer surface; positioning said reflector relative to a wafer edge to reflect thermal energy radiated from said wafer edge back thereto; and reflecting thermal energy radiated from said wafer surface back thereto with said reflector.
Claim 11
Dependent Claim
19 words
The method of claim 8, wherein said reflector is sloped to project downward below a clamping assembly upper surface.
Claim 12
Dependent Claim
12 words
The method of claim 8, wherein said reflector is a parabolic reflector.
Claim 13
Dependent Claim
12 words
The method of claim 8, wherein said reflector is an elliptical reflector.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1998-11-13 | 1999-05-15 | 1999-11-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-11-13 | 2003-05-15 | 2003-11-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-11-13 | 2007-05-15 | 2007-11-14 | $7700.00 | Window Closed / Lapsed |