Method of forming a MEMS topped integrated circuit with a stress relief layer

• US 8,048,704 B2
• Filed: 03/30/2010
• Issued: 11/01/2011
• Est. Priority Date: 04/09/2008
• Status: Active Grant

• Current Assignee: National Semiconductor Corporation (Texas Instruments, Inc.)
• Original Assignee: National Semiconductor Corporation (Texas Instruments, Inc.)
• Inventors: Smeys, Peter, Johnson, Peter
• Primary Examiner(s): Bryant; Kiesha
• Assistant Examiner(s): Perkins; Pamela E
• Application Number:
  US12/750,145
• Publication Number:
  US 20100190311A1
• Time in Patent Office: 581 Days
• Field of Search: None
• US Class Current: 438/51
• CPC Class Codes: B81B 2207/015 the micromechanical device and the control or processing electronics being integrated on the same substrate
• CPC Class Codes: B81B 3/0072 For controlling internal stress or strain in moving or flexible elements, e.g. stress compensating layers
• CPC Class Codes: H01F 17/0006 Printed inductances printed coils for dynamo-electric machines H02K3/26; printed circuits H05K
• CPC Class Codes: H01F 2017/0066 with a magnetic layer
• CPC Class Codes: H01F 2017/0086 on semiconductor substrate inductors for integrated circuits H01L28/10
• CPC Class Codes: H01F 41/046 structurally combined with ferromagnetic material
• CPC Class Codes: H01L 28/10 Inductors
• 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 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00

Abstract

The bow in a wafer that results from fabricating a large number of MEMS devices on the top surface of the passivation layer of the wafer so that a MEMS device is formed over each die region is reduced by forming a stress relief layer between the passivation layer and the MEMS devices.

Claims

1. A method of forming a semiconductor wafer comprising:

forming a stress relief layer that touches a top surface of a passivation layer, the stress relief layer having a first maximum bulk elongation, the passivation layer being non-conductive, touching a conductive region, and having a second maximum bulk elongation; and

forming a MEMS film that touches the stress relief layer, the MEMS film having a third maximum bulk elongation, the first maximum bulk elongation being substantially greater than the second maximum bulk elongation.

2. The method of claim 1 wherein the first maximum bulk elongation is substantially greater than the third maximum bulk elongation.

3. The method of claim 2 and further comprising forming an opening in the stress relief layer and the passivation layer, the opening exposing the conductive region.

4. The method of claim 3 wherein the opening is formed before the MEMS film is formed.

5. The method of claim 3 and further comprising forming a conductive member in the opening to touch the stress relief layer, the passivation layer, and the conductive region.

6. The method of claim 3 and further comprising forming a seed layer that touches the stress relief layer, the passivation layer, and the conductive region.

7. The method of claim 6 and further comprising forming a conductive member in the opening to touch the seed layer.

8. The method of claim 7 wherein the conductive member includes copper.

9. The method of claim 3 wherein the MEMS film is a non-conductive mold.

10. The method of claim 9 wherein the non-conductive mold exposes the conductive region.

11. The method of claim 10 and further comprising forming a seed layer on the non-conductive mold and the conductive region.

12. The method of claim 11 and further comprising forming a protective mask to cover the seed layer, the protective mask touching the conductive region.

13. The method of claim 12 and further comprising forming a conductive material in the mold to touch the seed layer.

14. The method of claim 13 wherein the conductive material is permalloy.

15. The method of claim 13 and further comprising forming a non-conductive member that touches a top surface of the mold and the conductive material.