Wafer scale molding of protective caps

• US 20030092245A1
• Filed: 05/06/2002
• Published: 05/15/2003
• Est. Priority Date: 01/10/2001
• Status: Active Grant

• Current Assignee: Precision Mechatronics Pty Ltd
• Original Assignee: Silverbrook Research Pty Limited
• Inventors: Silverbrook, Kia
• Granted Patent: US 6,716,666 B2
• Time in Patent Office: Days
• US Class Current: 438/460
• CPC Class Codes: B29C 2035/0822 using IR radiation
• CPC Class Codes: B29C 2043/503 using ejector pins, rods
• CPC Class Codes: B29C 33/0022 Multi-cavity moulds B29C33/301 takes precedence
• CPC Class Codes: B29C 33/3842 Manufacturing moulds, e.g. shaping the mould surface by machining
• CPC Class Codes: B29C 43/36 Moulds for making articles of definite length, i.e. discrete articles
• CPC Class Codes: B81C 1/00333 Aspects relating to packaging of MEMS devices, not covered by groups B81C1/00269 - B81C1/00325
• CPC Class Codes: B81C 2203/0109 Bonding an individual cap on the substrate
• CPC Class Codes: B81C 2203/0127 Using a carrier for applying a plurality of packaging lids to the system wafer
• CPC Class Codes: H01L 21/50 Assembly of semiconductor devices using processes or apparatus not provided for in a single one of the subgroups H01L21/06 - H01L21/326, e.g. sealing of a cap to a base of a container
• CPC Class Codes: H01L 2224/48463 the connecting portion on the bonding area of the semiconductor or solid-state body being a ball bond
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/1461 MEMS
• CPC Class Codes: Y10S 257/924 with passive device, e.g. capacitor, or battery, as integral part of housing or housing element, e.g. cap

Abstract

The invention is a method of applying an array (134) of caps to a wafer (144) of semiconductor material which includes a plurality of microfabricated devices (146). The method includes applying the array (134) of first caps substantially simultaneously to one side of the wafer (144), bonding the array (134) of caps to the wafer(144) and then separating the wafer into individual packages (148).

Claims

1. A method of applying a plurality of caps to a plurality of microfabricated devices at the wafer stage, the method including:

a) providing a wafer having a plurality of microfabricated devices;

b) providing a plurality of first hollow molded caps, one cap for each of the devices or a predetermined group of devices, each cap having a central portion and a perimeter wall extending from the perimeter edge of the central portion;

c) applying the first caps substantially simultaneously to one side of the wafer with each cap overlying part or all of a device or a predetermined group of devices with the free edge of the perimeter wall contacting the wafer;

d) bonding the first caps to the wafer; and

e) separating the wafer into individual packages.

2. The method of claim 1 wherein the wafer is separated into individual packages by a deep plasma etch of the wafer.

4. The method of claim 1 wherein caps are applied to the top and bottom of the wafer and material between caps is removed by a deep plasma etch from the bottom of the wafer.

5. The method of claim 1 wherein the wafer has a first side and a second side and for each device or predetermined group of devices a first cap is applied on the first side and a second cap is applied on the second side.

6. The method of claim 1 wherein step d) includes gluing the caps to the wafer material.

7. The method of claim 1 wherein the material of the cap absorbs infrared radiation

8. The method of claim 1 wherein the material of the cap absorbs infrared radiation within the wavelength range of about 1000 nm to about 5000 nm.

9. The method of claim 1 wherein step d) includes heating the caps with infrared radiation.

10. The method of claim 1 wherein the cap is formed from a thermoplastic material.

11. The method of claim 1 wherein the step of separating the wafer into individual packages includes separating the wafer into packages each having a single cap attached to one side thereof.

12. The method of claim 1 wherein the caps are joined to each other by cap material and the wafer is separated into individual packages by removing both the cap material between adjacent caps and the wafer material.

13. The method of claim 1 wherein the caps are joined to each other by cap material and the cap material between adjacent caps and the wafer material is removed by mechanical or thermal means.

14. The method of claim 1 wherein the caps are joined to each other by cap material and the cap material between adjacent caps is removed by an oxygen plasma etch.

15. The method of claim 1 wherein the caps are joined to each other by cap material and the cap material between adjacent caps is removed prior to step c).

16. The method of claim 1 wherein the caps are joined to each other by cap material and the cap material between adjacent caps is removed at step e).

3. The method of claim I further including applying a plurality of second caps to a second side of the wafer, before or after step c) but before step e).

17. An array of hollow molded caps, each of the caps including:

a central portion having a peripheral edge or edges; and

a peripheral wall or walls extending away from the central portion with the free end or ends of the peripheral wall or walls generally lying in a plane remote from the central portion to define a mouth;

the array having the caps;

a) in a common orientation;

b) the mouths of the caps in a common plane; and

c) at a spacing to enable the array of caps to be placed on a wafer including a plurality of microfabricated devices with the mouths of the caps contacting the wafer and each cap overlying part or all of a device or a predetermined group of devices.

18. The array of claim 17 wherein the material of the cap absorbs infrared radiation

19. The array of claim 17 wherein the material of the cap absorbs infrared radiation within the wavelength range of about 1000 nm to about 5000 nm.

20. The array of claim 17 wherein each cap has at least one aperture in the central portion.

21. The array of claim 17 wherein each cap has at least one wall extending from the central portion for bonding with the wafer and/or the microfabricated device to define a corresponding channel therebetween.

22. The array of claim 21 wherein the or each channel aligns with a corresponding aperture extending through the thickness of the wafer.

23. The array of claim 21 wherein each cap has at least one aperture extending through the central portion to communicate a respective channel with the outside environment.

24. The array of claim 17 wherein the caps are formed from a thermoplastic material.

25. The array of claim 17 wherein the caps are joined to each other by cap material.

26. The array of claim 17 wherein the caps are formed of a material which will etch under an oxygen plasma etch but is substantially unaffected by an etch to remove wafer material.