Method using fluid pressure to remove back metal from semiconductor wafer scribe streets

• US 8,906,745 B1
• Filed: 05/09/2014
• Issued: 12/09/2014
• Est. Priority Date: 09/12/2013
• Status: Active Grant

• Current Assignee: Micro Processing Technology, Inc., Semiconductor Components Industries LLC (ON Semiconductor Corporation)
• Original Assignee: Micro Processing Technology, Inc.
• Inventors: Lindsey, Paul C. Jr., Foote, Darrell
• Primary Examiner(s): Taylor, Earl
• Application Number:
  US14/273,755
• Time in Patent Office: 214 Days
• Field of Search: 438/114, 438/462
• US Class Current: 438/114
• CPC Class Codes: H01L 21/78 with subsequent division of the substrate into plural individual devices cutting to change the surface-physical characteristics or shape of semiconductor bodies H01L21/304

Abstract

A method of dividing a semiconductor wafer in which a sheet of deformable material engaging the metal layer side of the wafer has pressurized fluid applied thereto to cause the metal layer to break at the locations of wafer scribe streets.

Claims

1. A method of dividing a semiconductor wafer having a first wafer side including a semiconductor material layer, a second wafer side including a metal layer, and etched scribe streets extending from said first wafer side through said semiconductor material layer to said metal layer between semiconductor material dies, said method comprising the steps of:

placing a sheet of deformable material into engagement with the second wafer side to cover said second wafer side;

positioning said semiconductor wafer with the first wafer side thereof in engagement with a support surface;

employing said support surface to support said semiconductor wafer; and

while said sheet of deformable sheet material is in engagement with said second wafer side, carrying out the step of pressurizing fluid contacting said sheet of deformable material to deform the sheet of deformable material and cause the metal layer to break at the locations of the scribe streets.

2. The method according to claim 1 wherein the fluid is a gaseous fluid.

3. The method according to claim 1 wherein the step of pressurizing said fluid includes initially applying the pressure statically and subsequently gradually increasing the pressure.

4. The method according to claim 1 wherein the step of pressurizing the fluid is carried out in an instantaneous pulse.

5. The method according to claim 2 wherein said gaseous fluid is filtered, dry compressed air or dry compressed nitrogen.

6. The method according to claim 2 wherein the gaseous fluid is pressurized to a pressure within the range of from about 10,000 psi to about 40,000 psi.

7. The method according to claim 1 wherein said sheet of deformable material is plastic film.

8. The method according to claim 1 wherein said step of pressurizing fluid is carried out within a pressure chamber accommodating said semiconductor wafer.

9. The method according to claim 1 wherein said support surface is a flat, rigid surface of said pressure chamber.

10. The method according to claim 9 wherein said flat, rigid surface is a chuck surface.

11. The method according to claim 9 including the additional step of positioning a plastic support film between said flat, rigid surface and said first wafer side.

12. The method according to claim 7 wherein said plastic film forms a fluid-tight seal with a pressure chamber accommodating said semiconductor wafer and the fluid being pressurized.

13. The method according to claim 1 wherein said deformable sheet material is pressed in the direction of said metal layer by said fluid during pressurizing of said fluid.

14. The method according to claim 13 wherein the pressure of said fluid is sufficient to cause portions of the deformable sheet material to press into said scribe streets when said metal layer is broken.

15. The method according to claim 14 wherein said deformable sheet material when portions thereof are pressed into said scribe streets is operable to cleave the metal layer along edges of said semiconductor dies.

16. The method according to claim 15 wherein said deformable sheet material is operable when pressurized to substantially simultaneously cleave the metal layer at all the scribe streets of the semiconductor wafer.

17. The method according to claim 16 wherein said deformable sheet material has outer and inner sides, said cleaving step taking place when differential pressure exists between the volume of pressurized fluid engaging the outer side of the deformable sheet material and the volume of a fluid engaging the inner side of the deformable sheet material.

18. The method according to claim 17 wherein the scribe streets of the semiconductor wafer form a continuous, crisscrossing pattern whereby fluid therein moves freely to maintain the fluid pressure in all the streets under the sheet of deformable material uniform.

19. A method of dividing a semiconductor wafer having a first wafer side including a semiconductor material layer, a second wafer side including a metal layer, and etched scribe streets extending from said first wafer side through said semiconductor material layer to said metal layer between semiconductor material dies, said method comprising the steps of:

placing a sheet of deformable material into engagement with the second wafer side to cover said second wafer side;

positioning said semiconductor wafer with the first wafer side thereof in engagement with a support surface;

employing said support surface to support said semiconductor wafer; and

while said sheet of deformable sheet material is in engagement with said second wafer side, establishing a fluid pressure differential between fluid contacting opposed sides of said sheet of deformable material to deform the sheet of deformable material and break the metal layer at the locations of the scribe streets.

20. The method according to claim 19 wherein the opposed sides of said sheet of deformable material comprise an outer sheet side and an inner sheet side, said inner sheet side engaging said second wafer side, and the pressure of fluid engaging said outer sheet side exceeding the pressure of fluid at the inner sheet side.