Wafer support for measuring wafer geometry
A wafer measurement stage for supporting a semiconductor wafer for surface geometry measurements. The wafer measurement stage includes a support body having a planar surface configured to face a wafer which is supported by the wafer measurement stage, and a wafer contact structure provided on the planar surface. The wafer contact structure is configured to contact a portion of a wafer such that the wafer is supported in an elevated position relative to the planar surface and to control gravity effects at non-contact portions of the wafer.
1 . A wafer measurement stage for supporting a semiconductor wafer for surface geometry measurements, comprising:
a support body having a planar surface configured to face a wafer which is supported by the wafer measurement stage; and
a wafer contact structure provided on the planar surface, wherein the wafer contact structure is configured to contact a portion of a wafer such that the wafer is supported in an elevated position relative to the planar surface and to control gravity effects at non-contact portions of the wafer,
wherein the wafer contact structure comprises a line of support material which forms a closed shape structure, such as a ring contact structure on the planar surface.
2 . The wafer measurement stage of claim 1 , wherein the planar surface of the support body has a smaller area than a wafer to be supported on the wafer measurement stage.
3 . The wafer measurement stage of claim 1 , wherein the contact structure comprises a plurality of said ring contact structures provided in concentric arrangement on the planar surface.
4 . The wafer measurement stage of claim 1 , wherein the wafer contact structure comprises a plurality of lines of support material provided on the planar surface.
5 . The wafer measurement stage of claim 4 , wherein the plurality of lines of support material do not intersect one another.
6 . The wafer measurement stage of claim 4 , wherein the plurality of lines of support material comprise a plurality of parallel lines of support material.
7 . The wafer measurement stage of claim 5 , wherein the plurality of lines of support material intersect one another.
8 . The wafer measurement stage of claim 1 , wherein the wafer contact structure comprises silicone.
9 . The wafer measurement stage of claim 1 , wherein a cross section of the line of support material has a substantially circular shape.
10 . The wafer measurement stage of claim 1 , wherein a cross section of the line of support material has a substantially rectangular shape having a top support surface and opposing sidewalls which extend from the top support surface to the planar surface of the support body.
11 . The wafer measurement stage of claim 1 , wherein the wafer contact structure comprises a field of support material covering the planar surface.
12 . An apparatus for measuring geometry of a wafer, comprising:
a wafer measurement stage for supporting a semiconductor wafer, the wafer measurement stage comprising:
a support body having a planar surface configured to face a wafer which is supported by the wafer measurement stage, and
a wafer contact structure provided on the planar surface, wherein the wafer contact structure is configured to contact a portion of a wafer such that the wafer is supported in an elevated position relative to the planar surface and to control gravity effects at non-contact portions of the wafer,
wherein the wafer contact structure comprises a line of support material which forms a closed shape structure, such as a ring contact structure on the planar surface; and
a metrology tool configured to measure geometry of a wafer resting on the wafer measurement stage.
13 . The apparatus of claim 12 , wherein the metrology tool is configured to measure wafer geometry using at least one of optical, acoustic, and capacitive mechanisms to measure the z-height deviations across a surface of the wafer.
14 . The apparatus of claim 12 , further comprising a processing unit including a processor and a memory for storing software which, when executed by the processor, mathematically removes at least a portion of gravity effects from a measured geometry of a wafer resting on the wafer measurement stage.
15 . The apparatus of claim 14 , wherein the memory stores data correlated to gravity effects on said non-contact portions of the wafer for use in mathematically removing the gravity effects on said non-contact portions of the wafer resting on the wafer measurement stage.
16 . A method of measuring wafer geometry comprising:
providing a wafer on a measurement stage comprising:
a support body having a planar surface configured to face a wafer which is supported by the measurement stage, and
a wafer contact structure provided on the planar surface, wherein the wafer contact structure is configured to contact a portion of a wafer such that the wafer is supported in an elevated position relative to the planar surface and to control gravity effects at non-contact portions of the wafer,
wherein the wafer contact structure comprises a line of support material which forms a closed shape structure, such as a ring contact structure, on the planar surface; and
measuring a geometry of the wafer resting on the wafer measurement stage.
17 . The method of claim 16 , further comprising mathematically removing gravity effects from a geometry measurement obtained from said measuring a geometry.
18 . The method of claim 17 , wherein said mathematically removing comprises removing gravity effects on said non-contact portions of the wafer resting on the wafer measurement stage.