Bonding apparatus and method
A bonding apparatus and method holds first and second bodies peripherally, one above the other, on respective shelves. A lower heat-transfer body is configured to lift the first body from below and press the first and second bodies against an upper heat-transfer body to enable bonding between the first and second bodies.
1. A method of treating a first body having an upper surface, a lower surface, and a thickness and a second body having an upper surface and a lower surface, the method comprising:
configuring a lower shelf, having a vertical wall and a horizontal ledge, around a first interior space corresponding in lateral extent to the first body;
configuring an upper shelf, having a vertical wall and a horizontal ledge above the lower shelf and around a second interior space, corresponding in lateral extent to the second body, the second body being larger in lateral extent than the first body, so that the respective horizontal ledges of the upper and lower shelves are separated vertically by a distance greater than the thickness of the first body;
disposing a lower heat-transfer body, having an upper interface, under and spaced apart from the first interior space;
disposing an upper heat-transfer body, having a lower interface above and spaced apart from the second interior space;
disposing the lower surface of the first body on the horizontal ledge of the lower shelf;
disposing the lower surface of the second body on the horizontal ledge of the upper shelf; and
raising the lower heat-transfer body to lift the first body above the horizontal ledge of the lower shelf, the first body in turn lifting the second body from the upper shelf, and press the first and second bodies together against the upper heat-transfer body until the first and second bodies form a bonded pair.
2. The method of claim 1 wherein the upper heat-transfer body has an aperture at a right angle to the lower interface and further comprising:
configuring a plunger to reversibly descend through the aperture toward the second interior space; and
lowering the plunger to contact the second body, thereby forming a convexity in the lower surface of the second body, contact between the first body and the second body initiating at the convexity and spreading over substantially the entire upper surface of the first body as the second body approaches the upper heat-transfer body.
3. The method of claim 1 further comprising imposing a bias voltage across the first and second bodies pressed together between the upper and lower heat-transfer bodies to effect an anodic bond.
4. The method of claim 1 wherein one of the first and second bodies is a semiconductor wafer.
5. The method of claim 1 wherein at least one of the upper surface of the first body and the lower surface of the second body represents an applied material distinct in composition from respective interior compositions of the first and second bodies.
6. The method of claim 1 wherein the first body is a semiconductor wafer and contains hydrogen or helium implanted beneath the upper surface, defining a cleave plane.
7. The method of claim 6 wherein the second body is a receiver and further comprising annealing the bonded pair to effect exfoliation of a lamina from the first body, thereby rendering a bonded lamina-receiver assembly.
8. The method of claim 6 wherein the first body is of monocrystalline silicon.
9. The method of claim 6 wherein the defined cleave plane is at least 1 micron below the upper surface of the wafer, the receiver is of glass and the bonded lamina-receiver assembly is suitable for fabricating a photovoltaic device.
10. The method of claim 1 further comprising coupling electromagnetic energy to the lower and upper heat transfer bodies.