Method and apparatus for dicing semiconductor wafers

• US 5,904,546 A
• Filed: 02/12/1996
• Issued: 05/18/1999
• Est. Priority Date: 02/12/1996
• Status: Expired due to Term

• Current Assignee: Micron Technology, Inc.
• Original Assignee: Micron Technology, Inc.
• Inventors: Farnworth, Warren M., Wood, Alan G., Akram, Salman
• Primary Examiner(s): Picardat, Kevin M.
• Assistant Examiner(s): COLLINS, DEVEN M
• Application Number:
  US08/605,245
• Time in Patent Office: 1,191 Days
• Field of Search: 438/460, 438/462, 438/464
• US Class Current: 438/460
• 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 and apparatus for dicing semiconductor wafers is provided. The method comprises: forming an etch mask on the wafer, and then etching the wafer with a wet etchant, such as KOH, to form a peripheral groove around each die. Etching the wafer can be from the front side of the wafer, from the back side of the wafer or with partial etches from both sides. The etch process can be performed on a single wafer using a spray head apparatus or on batches of wafers using a recirculating dip tank apparatus.

Claims

1. A method for dicing a semiconductor wafer comprising a plurality of semiconductor dice, said method comprising:

forming a first mask on a front side of the wafer, the first mask comprising a first layer covering and protecting the dice;

forming a second mask on a back side of the wafer, second mask comprising a second layer having a pattern of etch openings to the back side; and

following forming of the first mask and the second mask, etching the wafer through the etch openings using a wet etchant to form a peripheral groove around each of the dice, the groove extending from the back side to the front side of the wafer and the first mask providing an etch stop and protecting the dice during the etching step.

2. The method of claim 1 wherein forming the first mask comprises blanket positing a layer of Si₃ N₄ on the wafer.

3. The method of claim 1 wherein the etching step comprises dipping the wafer in a tank containing the wet etchant.

4. The method of claim 1 wherein the etching step comprises spraying the wet etchant on the wafer.

5. The method of claim 1 wherein the etch openings have a criss cross pattern that matches a pattern of streets on the wafer.

6. The method of claim 1 wherein the second mask comprises a hard mask.

7. A method for dicing a semiconductor wafer comprising a plurality of semiconductor dice, said method comprising:

forming a protective mask on a first side of the wafer, the protective mask comprising a blanket deposited layer covering the dice;

forming an etch mask on a second side of the wafer, the etch mask including a pattern of etch openings to the second side;

etching the wafer through the etch openings to the protective mask to form a peripheral groove around each die extending from the second side to the first side of the wafer, with the protective mask providing an etch stop and a support structure for the dice during the etching step; and

stripping the etch mask and the protective mask to separate the dice.

8. The method of claim 7 wherein the protective mask comprises a hard mask.

9. The method of claim 7 wherein the etch openings are formed in a criss cross pattern corresponding to streets formed on the wafer.

10. The method of claim 7 further comprising supporting the wafer on a supporting substrate during the etching step.

11. The method of claim 7 wherein the etching step comprises an anisotropic etch performed with a wet etchant.

12. The method of claim 7 wherein the etching step comprises dipping the wafer in a tank containing the wet etchant.

13. The method of claim 7 wherein the etching step comprises spraying the wet etchant at the wafer.

14. A method for dicing a semiconductor wafer comprising a plurality of semiconductor dice, said method comprising:

forming a protective mask on a front side of the wafer, the protective mask comprising a blanket deposited layer covering the dice;

forming an etch mask on a back side of the wafer, the etch mask including a pattern of etch openings to the back side;

placing the front side of the wafer on a supporting substrate;

with the wafer on the supporting substrate, etching the wafer through the etch openings by spraying or dipping in a wet etchant to form a peripheral groove around each die extending from the back side to the front side of the wafer, the protective mask providing an etch stop and protecting the dice during the etching step;

removing the wafer from the supporting substrate with the protective mask supporting the dice;

stripping the etch mask and placing the back side of the wafer on a second supporting substrate; and

stripping the protective mask to separate the dice while the dice remain supported by the second supporting substrate.

15. The method of claim 14 further comprising controlling a size and shape of the grooves using the etch openings and selected etch parameters during the etching step.

16. The method of claim 14 wherein the wet etchant comprises KOH.

17. The method of claim 14 wherein the protective mask comprises a nitride.

18. The method of claim 14 wherein the protective mask comprises silicon nitride.

19. The method of claim 14 wherein the etching step comprises dipping a plurality of wafers into a tank containing the wet etchant.

20. The method of claim 14 wherein the supporting substrate and the second supporting substrate comprise an elastomeric material stretched over a film frame.

21. A method for dicing a semiconductor wafer comprising a plurality of semiconductor dice, said method comprising:

forming a first etch mask on a first side of the wafer, the first etch mask comprising a layer covering the dice and having a first pattern of etch openings;

forming a second etch mask on a second side of the wafer, the second etch mask comprising a second pattern of etch openings;

etching the wafer through the first pattern of etch openings to form a pattern of grooves extending partially through a thickness of the wafer;

following etching, removing the first etch mask and forming a protective layer on the first side of the wafer covering the dice;

following forming of the protective layer, attaching the first side of the wafer with the protective layer thereon to a supporting substrate;

following attaching, etching the wafer through the second pattern of etch openings to extend the pattern of grooves completely through the thickness of the wafer; and

stripping the first and the second etch mask to separate the dice.

22. The method of claim 21 wherein the first etch mask and the second etch mask comprise resist.

23. The method of claim 21 further comprising performing the attaching step using an adhesive layer.

24. The method of claim 21 wherein the etching steps comprise dipping the wafer in a wet etchant.

25. The method of claim 21 wherein the etching steps comprise spraying a wet etchant on the wafer.