Apparatus and methods for micro-transfer-printing
In an aspect, a system and method for assembling a semiconductor device on a receiving surface of a destination substrate is disclosed. In another aspect, a system and method for assembling a semiconductor device on a destination substrate with topographic features is disclosed. In another aspect, a gravity-assisted separation system and method for printing semiconductor device is disclosed. In another aspect, various features of a transfer device for printing semiconductor devices are disclosed.
1. A conformable micro-transfer printing device for parallel micro-transfer printing of printable elements to a destination substrate, the micro-transfer printing device comprising:
a rigid planar support; and
an elastomer stamp, the elastomer stamp comprising:
a bulk volume having a first surface and a second surface opposite the first surface, the second surface in direct contact with the rigid planar support; and
a plurality of spatially separated posts disposed on the first surface of the bulk volume in a regular array, wherein:
each of the posts is a multi-tiered post comprising geometrically similar tiers with a successively smaller cross section on each successive tier of the post, and
the geometrically similar tiers of each of the posts comprise a base tier and a top tier, the base tier being in contact with the first surface of the bulk volume and the top tier having an exposed micro-transfer printing contact surface opposite the first surface of the bulk volume, wherein the micro-transfer printing contact surface exhibits rate-dependent adhesion to one of the printable elements during micro-transfer printing, and
the bulk volume, the base tier, and the top tier comprise a same material, the top tier and the base tier comprise a same material, or the bulk volume and the base tier comprise a same material.
2. The device of claim 1 , wherein the contact surfaces of the plurality of posts are substantially in a same plane.
3. The device of claim 1 , wherein a thickness of each of the posts ranges from 1 micron to 100 microns.
4. The device of claim 1 , wherein a thickness of the bulk volume is from 0.5 mm to 5 mm.
5. The device of claim 1 , wherein a ratio of a thickness of each of the posts to a thickness of the bulk volume is from 1:1 to 1:10.
6. The device of claim 1 , wherein the top tier has a first Young's modulus and the base tier has a second Young's modulus that is greater than the first Young's modulus.
7. The device claim 1 , wherein the bulk volume and the posts are formed from a single material.
8. The device of claim 1 , wherein the base tier and the top tier both have a polygonal cross section.
9. The device of claim 8 , wherein the cross section is rectangular.
10. The device of claim 1 , wherein (i) the top tier has a height that is greater than a width, (ii) the base tier has a height that is greater than a width, or (iii) both (i) and (ii).
11. The device of claim 1 , wherein each post of the plurality of posts has a surface extending away from the planar support that is orthogonal to the planar support.
12. The device of claim 1 , wherein a center of a cross-sectional area of the top tier lies on the contact surface and the cross-sectional area forms a simple closed curve.
13. The device of claim 1 , wherein each of the plurality of posts is substantially identical to each other of the plurality of posts.
14. The device of claim 1 , wherein the plurality of posts have a common height.
15. The device of claim 1 , wherein the bulk volume is cured on the rigid planar support.
16. The device of claim 1 , wherein the bulk volume and the posts are each formed from polydimethylsiloxane (PDMS).
17. The device of claim 1 , wherein the bulk volume has a Young's modulus from 1 GPa to 10 GPa.
18. The device of claim 1 , wherein the posts each have a Young's modulus from 1 MPa to 10 MPa.
19. The device of claim 1 , wherein the posts each have a Young's modulus that is greater than a Young's modulus of the bulk volume.
20. The device of claim 1 , wherein the bulk volume is formed from a polymer having a coefficient of thermal expansion less than or equal to 14.5 ppm.
21. The device of claim 1 , wherein a height-to-width aspect ratio of each of the plurality of posts is less than or equal to 4:1.
22. The device of claim 1 , where in the base tier and the top tier both have a circular cross section.
23. The device of claim 1 , comprising an elastomer mesa having a first mesa surface and a second mesa surface, the first mesa surface being in contact with the first surface of the bulk volume and each of the posts being disposed in contact with the second mesa surface.
24. The device of claim 23 , wherein the mesa has a smaller cross section in a plane parallel to the rigid planar support than a cross section of the bulk volume.
25. The device of claim 1 , wherein the rigid planar support is made of glass.
26. The device of claim 1 , wherein the base tier is a base post and the top tier is a micro-post and comprising an array of geometrically similar micro-posts disposed on the base post and the array of geometrically similar micro-posts comprises the micro-post that is the top tier.
27. The device of claim 1 , wherein the top tier is shorter and narrower than the bottom tier.
28. The device of claim 1 , wherein the top tier and the base tier have a common Young's modulus.
29. The device of claim 1 , wherein the base tier and the bulk volume have a common Young's modulus.
30. The device of claim 1 , wherein the top tier and the base tier have a different Young's modulus.
31. The device of claim 1 , wherein the bulk volume, the base tier, and the top tier all comprise a same material.
32. The device of claim 1 , wherein the top tier has a size matched to a transferred device.
33. The device of claim 1 , wherein the top tier has an aspect ratio matched to a transferred device.
34. The device of claim 1 , wherein the top tier is shorter and narrower than the base tier.
35. The device of claim 1 , wherein the top tier is a single contiguous structure.
36. The device of claim 1 , wherein a height-to-width ratio of the top tier of each post ranges from 2:1 to 4:1, a width from one to fifteen microns and a height from two to sixty microns.
37. The device of claim 36 , wherein a height-to-width ratio of the base tier of each post ranges from 2:1 to 4:1, a width from five to forty microns and a height from ten to 160 microns.