Method of protecting micromechanical devices during wafer separation

• US 5,605,489 A
• Filed: 05/23/1995
• Issued: 02/25/1997
• Est. Priority Date: 06/24/1993
• Status: Expired due to Term

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Gale, Richard O., Mignardi, Michael A.
• Primary Examiner(s): Little, Willis
• Assistant Examiner(s): Morgan, Eileen P.
• Application Number:
  US08/448,205
• Time in Patent Office: 644 Days
• Field of Search: 451/28, 451/31, 451/41, 451/54, 451/57, 451/63, 451/388, 451/285, 451/287, 451/288, 269/21, 437/226, 148/DIG. 28
• US Class Current: 451/28
• CPC Class Codes: B25B 11/005 Vacuum work holders
• CPC Class Codes: B28D 5/0052 Means for supporting or holding work during breaking means for conveying work to or discharging work from the breaking machine B28D5/0058
• CPC Class Codes: B28D 5/0094 the supporting or holding device being of the vacuum type
• CPC Class Codes: B28D 5/022 by cutting with discs or wheels
• CPC Class Codes: B81C 1/00888 Multistep processes involving only mechanical separation, e.g. grooving followed by cleaving
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means
• CPC Class Codes: Y10S 148/028 Dicing
• CPC Class Codes: Y10T 225/12 With preliminary weakening

Abstract

A processing fixture and method of fabricating micromechanical devices, such as digital micromirror devices, that allows fragile structures on wafer 22 to be protected from debris during the saw operation and subsequent cleaning operations. The wafer 22 is attached to a vacuum fixture 26 after partially sawing the wafer 22 to create saw kerfs. The backside of the wafer 22 is then ground down to the saw kerfs 24 to separate the devices 32. Each device 32 is held on the fixture by a vacuum in the headspace above the device 32. In an alternate embodiment the devices are separated by sawing completely through the wafer while in the fixture.

Claims

1. A method of processing a wafer containing one or more micromechanical devices, said method comprising:

partially sawing between said devices on a first side;

placing a protective fixture over and in contact with said first side of said wafer, said protective fixture defining a headspace above each device;

evacuating said headspace to create a vacuum;

grinding the side of said wafer opposite said first side to separate said devices; and

removing said vacuum to release said devices from said fixture.

2. The method of claim 1 wherein said protective fixture is fabricated of a material selected from the group consisting of stainless steel, ceramic, and quartz.

3. The method of claim 1 wherein said protective fixture is a flexible protective fixture.

4. The method of claim 1 further comprising the step of cleaning debris created by said grinding step from said devices and said protective fixture.

5. The method of claim 1 further comprising the step of cleaning debris created by said further processing step from said devices and said protective fixture.

6. A method of processing a wafer containing one or more micromechanical devices, said method comprising:

placing a flexible protective fixture over and in contact with said wafer, said protective fixture defining a headspace above each device;

evacuating said headspace to create a vacuum;

breaking said wafer to separate said devices; and

removing said vacuum to release said devices from said fixture.

7. A method of processing a wafer containing one or more micromechanical devices, said method comprising:

placing a protective fixture over and in contact with a first side of said wafer, said protective fixture defining a headspace above each device;

evacuating said headspace to create a vacuum;

grinding the side of said wafer opposite said first side to separate said devices; and

removing said vacuum to release said devices from said fixture.

8. The method of claim 7 wherein said protective fixture is fabricated of a material selected from the group consisting of stainless steel, ceramic, and quartz.

9. The method of claim 7 wherein said protective fixture is a flexible protective fixture.

10. The method of claim 7 further comprising the step of cleaning debris created by said grinding step from said devices and said protective fixture.