Multilayer MEMS device and method of making same

• US 7,368,228 B2
• Filed: 12/19/2003
• Issued: 05/06/2008
• Est. Priority Date: 12/19/2003
• Status: Expired due to Fees

• Current Assignee: Palo Alto Research Center, Inc. (Xerox Holdings Corp.)
• Original Assignee: Palo Alto Research Center, Inc. (Xerox Holdings Corp.)
• Inventors: Weisberg, Michael C.
• Primary Examiner(s): Huff; Mark F.
• Assistant Examiner(s): Sullivan; Caleen O.
• Application Number:
  US10/742,276
• Publication Number:
  US 20050136359A1
• Time in Patent Office: 1,600 Days
• Field of Search: 430/311, 430/322, 430/320
• US Class Current: 430/320
• CPC Class Codes: B33Y 10/00 Processes of additive manufacturing
• CPC Class Codes: B81C 1/00492 Processes for surface micromachining not provided for in groups B81C1/0046 - B81C1/00484
• CPC Class Codes: B81C 2201/0159 Lithographic techniques not provided for in B81C2201/0157
• CPC Class Codes: B81C 2201/0197 Processes for making multi-layered devices not provided for in groups B81C2201/0176 - B81C2201/0192
• CPC Class Codes: G03F 7/00 Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor using photoresist structures for special production processes, see the relevant places, e.g. B44C, H01L, e.g. H01L21/00, H05K
• CPC Class Codes: G03F 7/0035 Multiple processes, e.g. applying a further resist layer on an already in a previously step, processed pattern or textured surface

Abstract

A method of creating a microelectromechanical systems (MEMS) device includes applying a layer of photoresist to a lower layer to create a multilayer MEMS device. The method includes transferring the layer of photoresist to the lower layer. The method can also include spincoating the photoresist onto a release layer, softbaking the spincoated photoresist to at least partially dry it, transferring the photoresist to form a layer of the multilayer MEMS device, and exposing the photoresist to light to crosslink it. The multilayer MEMS device includes a plurality of layers of photoresist.

Claims

1. A method of creating a microelectromechanical systems (MEMS) device having a substrate and a lower layer comprising:

creating a lower layer formed of a first material having spaced apart walls;

applying a layer of photoresist onto the lower layer, the layer of photoresist including a bridge bridging an open area in the lower layer extending between the spaced apart walls;

masking a portion of the photoresist leaving a portion of the photoresist unmasked;

exposing the unmasked portion of the photoresist to light to crosslink the unmasked portion; and

removing the masked portion of the photoresist to form a multilayer MEMS device having a layer of crosslinked photoresist on top of the lower layer with the bridge bridging the open area.

2. The method defined in claim 1, wherein the applying step comprises drying the photoresist.

3. The method defined in claim 2, wherein the applying step comprises dry roll transferring the layer of photoresist onto the lower layer.

4. The method defined in claim 1, wherein the applying step further comprises:

spincoating the photoresist onto a release layer;

softbaking the spincoated photoresist and transferring the layer of photoresist onto the lower layer from the release layer.

5. The method defined in claim 4, wherein the spincoating step includes spincoating the photoresist to a thickness of about 4 to about 100 microns thick.

6. The method defined in claim 4, wherein the applying step further comprises:

heating the lower layer to a transfer temperature;

transferring the photoresist onto the lower layer; and

removing the release layer.

7. The method defined in claim 6, wherein the heating step includes heating the lower layer to about 50 to 90 degrees Celsius.

8. The method defined in claim 1, further comprising:

repeating the steps of applying, masking, exposing, and removing to form multiple layers of photoresist.

9. The method defined in claim 1, wherein the layers of photoresist have different thicknesses.

10. The method defined in claim 1, wherein the layer of photoresist has a thickness variation of about +−

13%.

11. The method defined in claim 1, wherein the MEMS device has a total device thickness variation of about +−

2%.

12. The method defined in claim 1, wherein the lower layer is not a photoresist.

19. The method defined in claim 1, wherein the lower layer is a photoresist.

20. The method defined in claim 1, wherein the open area is at least 500 microns wide.

21. The method defined in claim 1, further comprising forming an open area in the bridge to create a passage between layers.

13. A method of creating a microelectromechanical systems (MEMS) device comprising:

applying a layer of photoresist comprising;

applying the photoresist wet onto a release layer, and

transferring the photoresist from the release layer onto a layer of crosslinked photoresist having spaced apart walls and an open area extending between the spaced apart walls, the transferred photoresist bridging the open area;

masking a portion of the photoresist leaving a portion of the photoresist unmasked;

exposing the unmasked portion of the photoresist to light to crosslink the unmasked portion;

removing the masked portion of the photoresist to create an open area in the layer; and

repeating the steps of applying, masking, exposing, and removing to form multiple layers of crosslinked photoresist on top of each other and bridging open areas.

23. The method defined in claim 13, wherein the open area is at least 500 microns wide.

14. A method of creating a microelectromechanical systems (MEMS) device having a substrate and a lower layer comprising:

applying a layer of photoresist onto a lower layer having spaced apart walls defining an open area extending between the spaced apart walls, the applied layer of photoresist having a bridge portion bridging the open area; and

crosslinking the layer of photoresist to form a multilayer MEMS device having a layer of crosslinked photoresist on top of the lower layer with the bridge portion bridging the open area.

15. The method defined in claim 14, wherein the applying step comprises dry roll transferring the layer of photoresist onto the lower layer.

16. The method defined in claim 14, wherein the applying step further comprises:

spincoating the photoresist onto a release layer;

softbaking the spincoated photoresist and transferring the layer of photoresist onto the lower layer from the release layer.

17. The method defined in claim 16, wherein the spincoating step includes spincoating the photoresist to a thickness of about 4 to about 100 microns thick.

18. The method defined in claim 16, wherein the applying step further comprises:

heating the lower layer to a transfer temperature of about 50 to 90 degrees Celsius;

transferring the photoresist onto the lower layer; and

removing the release layer.

22. The method defined in claim 14, further comprising forming an open area in the bridge portion to create a passage between layers.

24. The method defined in claim 14, wherein the open area is at least 500 microns wide.