Thinning of semiconductor wafers

• US 20040214432A1
• Filed: 04/24/2003
• Published: 10/28/2004
• Est. Priority Date: 04/24/2003
• Status: Abandoned Application

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Masumoto, Mutsumi
• Application Number:
  US10/422,290
• Publication Number:
  US 20040214432A1
• Time in Patent Office: Days
• US Class Current: 438/689
• CPC Class Codes: H01L 21/304 Mechanical treatment, e.g. grinding, polishing, cutting H01L21/30625 takes precedence
• CPC Class Codes: H01L 21/6835 using temporarily an auxiliary support
• CPC Class Codes: H01L 2221/6834 used to protect an active side of a device or wafer

Abstract

A method for thinning a semiconductor wafer (201) to less than about 100 μ thickness (208). The wafer has two flat surfaces (206, 207) of a first diameter and a rounded periphery (204a) between the flat surfaces. A generally circular support tape (202) for the wafer is selected having a second diameter. The second diameter is selected to be greater than the first diameter by an amount about twice the length (204a) of the peripheral wafer rounding, as obtained after the thinning step is completed and measured along a radial line. Flat wafer surface 206 is placed on the tape and the wafer is thinned to the intended thickness less than about 100 μ. Specifically, the length (204b) along a radial line may be about 1 mm, making the second diameter about 2 mm larger than the first diameter. Furthermore, the wafer thickness (208) after thinning may specifically be between 10 and 30 μ.

Claims

1. A method of thinning a semiconductor wafer having first and second flat surfaces of a first diameter and a rounded periphery between said flat surfaces, comprising the steps of:

selecting a generally circular support tape for said wafer, said tape having a second diameter;

selecting said second diameter to be greater than said first diameter by an amount about equal to the length of said peripheral wafer rounding as obtained in said wafer after said thinning step is completed;

placing said first flat wafer surface on said tape; and

removing semiconductor material from said second wafer surface until the intended thickness is achieved.

2. The method according to claim 1 wherein said length of peripheral wafer rounding is calculated along a radial line.

3. The method according to claim 2 wherein said length along a radial line is about 1 mm, making said second diameter about 2 mm larger than said first diameter.

4. The method according to claim 1 wherein said wafer thickness after thinning is less than approximately 100 μ

.

5. The method according to claim 1 wherein said wafer thickness after thinning is between 10 and 30 μ

.

6. The method according to claim 1 wherein said step of removing semiconductor material comprises mechanically grinding said semiconductor material.

7. The method according to claim 1 wherein said step of removing semiconductor material comprises chemically etching said semiconductor material.

8. The method according to claim 1 wherein said step of removing semiconductor material comprises chemical/mechanical wet polishing said semiconductor material.

9. The method according to claim 1 wherein said step of removing semiconductor material comprises plasma dry etching said semiconductor material.

10. The method according to claim 1 further comprising the step of leaving said support tape combined with said wafer after said completing said thinning steps in order to protect said wafer during subsequent handling and transporting.

11. A method of thinning a semiconductor wafer to a final thickness, said wafer having first and second flat surfaces of a first diameter and a rounded periphery between said flat surfaces, said method comprising the steps of:

placing said wafer on a generally circular support tape such that said first flat surface is adjacent to said tape, said tape having a second diameter wherein said second diameter is about equal to said first diameter plus a length measured along a radial line from the center of said wafer about equal to twice the length of said rounded periphery at said final thickness of said wafer; and

removing semiconductor material from said second surface of said wafer until said final thickness is achieved.

12. The method according to claim 11 wherein said step of placing said wafer on a generally circular support tape comprises placing said wafer on a tape having a diameter about 2 mm larger than said first diameter.

13. A method of thinning a semiconductor wafer having first and second flat surfaces of a first diameter, comprising the steps of:

selecting a generally circular support tape for said wafer, said tape having a second diameter;

selecting said second diameter about 2 mm greater than said first diameter;

placing said first flat wafer surface on said tape; and

removing semiconductor material from said second wafer surface until the intended thickness is achieved.

14. The method according to claim 13 wherein said wafer thickness after thinning is less than approximately 100 μ

.

15. The method according to claim 13 wherein said wafer has a rounded periphery.

16. A method of mechanically grinding a semiconductor wafer to a final thickness, said wafer having first and second flat surfaces of a first diameter and a rounded periphery between said flat surfaces, said method comprising the steps of:

placing said wafer on a generally circular support tape such that said first flat surface is adjacent to said tape, said tape having a second diameter wherein said second diameter is about equal to said first diameter plus a length measured along a radial line from the center of said wafer about equal to twice the length of said rounded periphery at said final thickness of said wafer;

bringing a grinding tool into contact with said second surface of said wafer; and

abrading said second surface of said wafer until said final thickness is achieved.

17. The method according to claim 16 wherein said step of placing said wafer on a generally circular support tape comprises placing said wafer on a tape having a diameter about 2 mm larger than said first diameter.

18. The method according to claim 16 wherein said step of abrading until said final thickness is achieved comprises abrading said wafer until the thickness of said wafer is less than approximately 100 μ

.

19. The method according to claim 16 further comprising the step of leaving said support tape combined with said wafer after completing the mechanically grinding step in order to protect said wafer during subsequent handling and transporting.

20. A method of mechanically grinding a semiconductor wafer to a final thickness of less than about 100 μ

, said wafer having first and second flat surfaces of a first diameter and a rounded periphery between said flat surfaces, said method comprising the steps of;

placing said wafer on a generally circular support tape such that said first flat surface is adjacent to said tape, said tape having a second diameter about 2 mm larger than said first diameter;

bringing a grinding tool into contact with said second surface of said wafer; and

abrading said second surface of said wafer until said final thickness is achieved.