Wafer chuck apparatus with micro-channel regions
The wafer chuck apparatus has a chuck body that includes an interior and a top surface. A plurality of micro-channel regions is formed in the top surface. Each micro-channel region is defined by an array of micro-channel sections that are in pneumatic communication with each other. The micro-channel regions are pneumatically isolated from each other. One or more vacuum manifold regions are defined in the interior of the chuck body and are in pneumatic communication with corresponding micro-channel regions through respective vacuum holes. The configuration of the micro-channel regions makes the wafer chuck apparatus particularly useful in chucking wafers that have a substantial amount of warp.
1. A chuck apparatus for supporting a wafer, comprising: a chuck body having a center, an interior and a top side with a top surface; a plurality of micro-channel regions formed in the top surface, with each micro-channel region comprising an array of concentric arcuate micro-channel sections that are in direct pneumatic communication with one another, the micro-channel regions being pneumatically isolated from one another; and at least one vacuum manifold region defined in the interior of the chuck body and that is in pneumatic communication with ones of the plurality of micro-channel regions through respective vacuum holes; wherein the top side includes a plurality of radially defined segments that each include one or more of the plurality of micro-channel regions.
2. The chuck apparatus according to claim 1 , wherein the micro-channel sections within each micro-channel regions are defined by sidewalls having respective top surfaces that define the top surface of the chuck body.
3. The chuck apparatus according to claim 2 , wherein the top surface of the chuck body has a contact area A S , the top side of the chuck body has a total area A CT , and wherein a chuck contact-area ratio R CT =A S /A CT is in the range 0.20≤R CT ≤0.35.
4. The chuck apparatus according to claim 2 , wherein each micro-channel region has a total area A RT and a contact surface area A R , wherein a micro-channel region contact-area ratio R CR =A R /A RT is in the range 0.20≤R CR ≤0.35.
5. The chuck apparatus according to claim 2 , wherein a plurality of the sidewalls each include a transverse groove extending across the corresponding sidewall that provides the direct pneumatic communication between adjacent micro-channel sections.
6. The chuck apparatus according to claim 1 , further comprising a vacuum pump pneumatically connected to the at least one vacuum manifold region.
7. The chuck apparatus according to claim 1 , wherein the plurality of micro-channel regions is defined by between 25 and 250 micro-channel regions.
8. The chuck apparatus according to claim 1 , further comprising at least three through holes formed in the chuck body and each sized to pass a lift pin.