Method of fabricating an array of wafer scale polymeric caps

1. A method of fabricating an array of wafer scale polymeric caps, the method including:

forming, in a two part mold, a plurality of first hollow molded caps from a layer of thermoplastic material which is placed in the mold, the mold having first and second mold halves which are brought together to form the caps; and

separating the plurality of first hollow molded caps into an array of individual caps.

2. The method of claim 1 further comprising the step of:

applying, using one half, the caps to one side of a wafer.

3. The method of claim 1 , wherein the mold and the wafer are formed from the same semiconductor material.

4. The method of claim 1 , wherein the caps are separated from the array into individual caps by an etching process.

5. The method of claim 1 , wherein the method further comprises using a cooperating release wafer having eject pins.

6. The method of claim 5 , wherein the first mold half has openings for receiving the pins, the pins being longer than the openings.

7. The method of claim 5 , wherein there is a gap between the first mold half and the release wafer and using the release wafer further comprises applying a vacuum to the gap to draw the release wafer toward the first mold half.

8. The method of claim 1 , wherein the thermoplastic material is etchable by an oxygen plasma etch.

9. The method of claim 7 , wherein forming the cap comprises heating the thermoplastic material with infrared radiation, the mold being essentially transparent to the infrared radiation.

10. The method of claim 1 , wherein the first and second mold halves each have holes for receiving pins which are formed on adjacent release wafers.

11. The method of claim 1 , wherein the thermoplastic material has a thickness of 200–500 microns prior to being formed into caps.

12. The method of claim 1 , wherein when the mold is closed, there is a thin layer of the material from which the caps are formed joining the caps into an array and the thin layer is removed by mechanical action of the mold.

13. The method of claim 1 , wherein when the mold is opened, there is a thin layer of the material from which the caps are formed joining the caps into an array and the thin layer is removed by an oxygen plasma etch.

14. The method of claim 12 , wherein the array is removed from both mold halves by the action of eject pins which are carried in eject holes formed into both mold halves.

15. The method of claim 12 , wherein the first half has first portions which separate adjacent areas; the second half has second portions which separate adjacent grooves; the first and second portions coming together when the halves are brought together such that material is squeezed out from between the first and second portions, separating adjacent caps.

16. The method of claim 1 , wherein the first mold half has a lower surface into which is formed a series of recesses defined by lateral edges, the second mold half having an upper surface in which is formed a series of grooves, the grooves aligning with the edges, the recesses and grooves defining cavities having a repeat spacing that corresponds to a spacing on a wafer to which the caps will be applied.

17. The method of claim 15 , wherein the first and second portions of the molds have top surfaces that have not been etched.

18. The method of claim 1 , wherein:

the first half includes first holes formed through it;

there being provided a first half release wafer from which project pins;

the pins located in registry with the first holes;

the first half having a thickness in the area of the first holes, the pins being longer than the thickness;

the first half release wafer having a first position in which the pins are flush with interior ends of the first holes;

there being a gap between the first half and the first half release wafer when the first half release wafer is in the first position; and wherein

a vacuum is applied to the gap to eject the caps.

19. The method of claim 18 , wherein:

the second half includes second holes formed through it;

there being provided a second half release wafer from which project pins;

the pins located in registry with the second holes;

the second half having a thickness in the area of the second holes, the pins being longer than the thickness;

the second half release wafer having a first position in which the pins are flush with an interior end of the second holes;

there being a second gap between the second half and the second half release wafer when the second half release wafer is in the first position.

20. The method of claim 19 , wherein:

the holes are all formed by electron beam or X-ray lithography.