Packaging die preparation

• US 6,162,703 A
• Filed: 02/23/1998
• Issued: 12/19/2000
• Est. Priority Date: 02/23/1998
• Status: Expired due to Term

• Current Assignee: Micron Technology, Inc.
• Original Assignee: Micron Technology, Inc.
• Inventors: Muntifering, Tom A., Heppler, Steven W., Ball, Michael B.
• Primary Examiner(s): Whitehead, Jr., Carl
• Assistant Examiner(s): VOCKRODT, JEFF B
• Application Number:
  US09/026,999
• Time in Patent Office: 1,030 Days
• Field of Search: 438/110, 438/113, 438/114, 438/459, 438/460, 438/464, 438/465
• US Class Current: 438/465
• CPC Class Codes: H01L 21/304 Mechanical treatment, e.g. grinding, polishing, cutting H01L21/30625 takes precedence
• CPC Class Codes: H01L 21/3043 Making grooves, e.g. cutting
• CPC Class Codes: H01L 21/6835 using temporarily an auxiliary support
• CPC Class Codes: H01L 21/6836 Wafer tapes, e.g. grinding or dicing support tapes adhesive tapes in general C09J7/20
• CPC Class Codes: H01L 2221/68327 used during dicing or grinding
• CPC Class Codes: H01L 2221/6834 used to protect an active side of a device or wafer

Abstract

The present invention relates to a process for preparing a wafer for chip packaging that minimizes stress and torque on wafer components during back grinding. The wafer has fabricated thereon a plurality of dies in a die side thereof opposite a back side thereof. A protective coating is spun on the die side to protect the dies. The wafer is separated into a plurality of connected pieces by scratching or cutting a recess into streets or scribe lines in the die side. The connected pieces of the wafer are secured to a surface with the back side thereof exposed. Material is removed from the back side of the wafer by chemical, mechanical, or chemical-mechanical methods until each piece is separated or disconnected from the other pieces. The protective coating is removed. The pieces can be situated upon a flexible surface that is stretched to increase the separation between pieces. Each die in the die side of each piece is then packaged into a die package.

Claims

1. A semiconductor structure fabrication method comprising:

providing a semiconductor substrate having a die side opposite a back side, said die side having a plurality of die formed therein, wherein the die side is situated upon a flexible plastic sheet, the flexible plastic sheet is situated upon a double-sided adhesive tape, and the double-sided adhesive tape is upon a table;

forming a recess in the die side of the semiconductor substrate, wherein;

a first portion of said semiconductor substrate having at least one die therein is on one side of said recess; and

a second portion of said semiconductor substrate having at least one die therein is on a side of said recess opposite that of said first portion of said semiconductor substrate;

removing material from said back side of said semiconductor substrate by an abrading operation sufficient to separate from contact the first portion of said semiconductor substrate from the second portion of said semiconductor substrate; and

stretching said flexible plastic sheet so as to increase the separation between said first and second portions of said semiconductor substrate.

2. The method as defined in claim 1, further comprising:

packaging at least one of the die into a die package.

3. The method as defined in claim 1, wherein providing said semiconductor substrate comprises:

providing a silicon wafer;

fabricating said plurality of dies in a die side of said silicon wafer.

4. The method as defined in claim 1, wherein forming said recess in the die side of the semiconductor substrate comprises:

cutting scribe lines in the die side of said semiconductor substrate.

5. The method as defined in claim 1, wherein removing material from said back side of said semiconductor substrate comprises:

grinding the back side of the first and second portions of the semiconductor substrate.

6. The method as defined in claim 1, further comprising, after forming said recess:

securing the die side of said semiconductor substrate to a surface such that the back side thereof is exposed.

7. The method as defined in claim 1, wherein said first and second portions of said semiconductor substrate each have a first thickness, and wherein removing material from said back side of said semiconductor substrate comprises:

mechanically removing material from said back side of said semiconductor substrate until said first and second portions of said semiconductor substrate each have a second predetermined thickness.

8. The method as defined in claim 1, wherein the recess in the die side of the semiconductor substrate is formed in a street or scribe line in the die side of the semiconductor substrate.

9. The method as defined in claim 1, wherein removing material from said back side of said semiconductor substrate changes the thickness of said first and second portions of said semiconductor substrate to be in a range from about 0.2 millimeters to about 0.762 millimeters.

10. A semiconductor structure fabrication method comprising:

providing a semiconductor substrate having a die side opposite a back side, said die side having a plurality of die formed therein, wherein the die side is situated upon a flexible plastic sheet, the flexible plastic sheet is situated upon a double-sided adhesive tape, and the double-sided adhesive tape is upon a table;

forming a recess in the die side of the semiconductor substrate, wherein said recess is defined by a first portion of said semiconductor substrate, a second portion of said semiconductor substrate, and third portion of the semiconductor substrate connecting the first and second portions of the semiconductor substrate;

removing material from said third portion of said semiconductor substrate at the back side thereof by an abrading operation until the first portion of said semiconductor substrate is unconnected to the second portion of said semiconductor substrate; and

stretching said flexible plastic sheet so as to increase the separation between said first and second portions of said semiconductor substrate.

11. The method as defined in claim 10, wherein forming said recess comprises:

cutting a scribe line in the die side of said semiconductor substrate.

12. The method as defined in claim 11, wherein cutting said scribe line comprises using a rotating saw blade to saw into the die side of the semiconductor substrate.

13. The method as defined in claim 11, wherein cutting said scribe line in the die side of said semiconductor substrate is a process selected from a group consisting of:

moving a scribe blade under force across the die side of the semiconductor substrate so as to form said recess; and

cutting into the die side of the semiconductor substrate using a rotating saw blade to form said recess.

14. A semiconductor structure fabrication method comprising:

providing a semiconductor substrate having a plurality of dies in a die side thereof opposite a back side, wherein the die side is situated upon a flexible plastic sheet, the flexible plastic sheet is situated upon a double-sided adhesive tape, and the double-sided adhesive tape is upon a table;

forming a plurality of recesses in the die side of said semiconductor substrate defining therebetween a plurality of pieces of said semiconductor substrate, each piece of said plurality of pieces having at least one die therein;

removing material from said back side of said semiconductor substrate by an abrading operation sufficient to separate said pieces; and

stretching said flexible plastic sheet so as to increase the separation between said first and second portions of said semiconductor substrate.

15. The method as defined in claim 14, wherein forming said plurality of recesses comprises:

cutting a plurality of parallel and perpendicular scribe lines in the die side of said semiconductor substrate.

16. The method as defined in claim 14, wherein removing material from said back side of said semiconductor substrate is a process selected from a group consisting of:

a mechanical planarization and a chemical-mechanical planarization.

17. A chip packaging method comprising:

providing a semiconductor substrate having a die side opposite a back side, said die side having a plurality of dies formed therein and a plurality of recesses formed therein separating the dies of said plurality of dies, wherein the die side is situated upon a flexible plastic sheet, the flexible plastic sheet is situated upon a double-sided adhesive tape, and the double-sided adhesive tape is upon a table;

dividing said semiconductor substrate into a plurality of pieces by an abrading operation, wherein;

each said piece has;

a predetermined thickness;

said back side opposite said die side;

one die of said plurality of dies formed in the die side thereof; and

said dividing of said semiconductor substrate comprises removing material from the back side of the semiconductor substrate;

packaging the dies in the die side of said plurality of pieces; and

stretching said flexible surface so as to increase the separation between said first and second portions of said semiconductor substrate.

18. A chip packaging method comprising:

providing a semiconductor wafer having a die side opposite a back side, said die side having a plurality of die thereon separated by a plurality of scratches cut into scribe lines on the die side;

forming a protective coating upon the die side, wherein the protective coating includes a flexible plastic sheet situated upon a double-sided adhesive tape that is upon a table;

grinding the back side to divide the semiconductor wafer into plurality of separated, unconnected die, each said die having said back side opposite said die side and having a thickness in a range between 0.762 millimeters to about 0.2 millimeters;

stretching said flexible plastic sheet so as to increase the separation between said first and second portions of said semiconductor substrate; and

performing a chip packaging process upon each die of said plurality of die to package each die of said plurality of dies in a die package.

19. A chip packaging method comprising:

providing a semiconductor wafer having integrated circuitry including a plurality of dies formed within a die side opposite a back side thereof;

cutting recesses into the die side, each recess having an opening at said die side and a closed end proximal said back side;

forming a protective covering over said die side, wherein the protective coating includes a flexible plastic sheet situated upon a double-sided adhesive tape that is upon a table;

positioning the protective covering upon a surface with the back side of the semiconductor substrate exposed;

thinning the thickness of the semiconductor wafer by grinding the back side thereof until the closed end of each of the recesses is breached, whereby the semiconductor wafer is separated into a plurality of unconnected pieces each having said die side and said back side and one die of said plurality of dies therein;

stretching said flexible plastic sheet so as to increase the separation between said first and second portions of said semiconductor substrate; and

forming a die package for each die of said plurality of dies.

20. A method as defined in claim 19, wherein said thinning is a process selected from a group consisting of:

a mechanical process and a chemical-mechanical process.

21. A method as defined in claim 19, wherein cutting recesses into the die side is a sawing operation using a saw blade that saws into but not through said semiconductor substrate.

22. A method as defined in claim 19, wherein cutting recesses into the die side

cuts into but not through the semiconductor wafer at scribe lines in the die side.

23. A method as defined in claim 19, wherein, during said thinning, said protective covering adheres said semiconductor substrate to said table with the back side of the semiconductor wafer exposed.

24. A chip packaging method comprising:

providing a silicon wafer;

fabricating a plurality of dies in a die side of said silicon wafer, said die side being opposite a back side of said silicon wafer;

forming a photoresist layer over said die side;

cutting into but not through said die side so as to define in said die side a plurality of pieces;

securing said semiconductor wafer to a grinding surface such that the back side thereof is exposed;

removing material from the back side of said semiconductor wafer by an abrading operation until each of said plurality of pieces is out of contact with other of said pieces, said material being removed by a process selected from a group consisting of mechanical planarization and chemical-mechanical planarization, wherein said silicon wafer is situated upon a flexible surface, each said piece having;

said back side opposite said die side; and

at least one die formed in the die side thereof;

stretching said flexible surface so as to increase the separation between said plurality of pieces;

performing a die packaging sequence comprising;

removing said photoresist layer from the die side of each said piece; and

packaging in a die package each said at least one die in the die side of each said piece of said plurality of pieces.