Grooved semiconductor die for flip-chip heat sink attachment

• US 6,225,695 B1
• Filed: 06/05/1997
• Issued: 05/01/2001
• Est. Priority Date: 06/05/1997
• Status: Expired due to Term

• Current Assignee: Bell Semiconductor, LLC (Hilco Inc. (d/b/a Hilco Global))
• Original Assignee: LSI Logic Corporation (Broadcom, Inc.)
• Inventors: Chia, Chok J., Alagaratnam, Maniam, Lim, Seng-Sooi
• Primary Examiner(s): Williams, Alexander O.
• Application Number:
  US08/869,796
• Time in Patent Office: 1,426 Days
• Field of Search: 257/712, 257/707, 257/710, 257/711, 257/713, 257/714, 257/717-722, 257/675, 257/686, 257/734, 257/737, 257/738, 257/706, 257/796, 257/778, 257/779, 257/782, 257/783
• US Class Current: 257/712
• CPC Class Codes: H01L 2224/16 of an individual bump connector
• CPC Class Codes: H01L 2224/16225 the item being non-metallic, e.g. insulating substrate with or without metallisation
• CPC Class Codes: H01L 2224/32225 the item being non-metallic, e.g. insulating substrate with or without metallisation
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48227 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/73204 the bump connector being embedded into the layer connector
• CPC Class Codes: H01L 2224/73253 Bump and layer connectors
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 2224/83138 the guiding structures being at least partially left in the finished device
• CPC Class Codes: H01L 29/0657 characterised by the shape of the body
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/10155 being other than a cuboid
• CPC Class Codes: H01L 2924/10158 at the passive surface
• CPC Class Codes: H01L 2924/10253 Silicon [Si]
• CPC Class Codes: H01L 2924/15311 being a ball array, e.g. BGA
• CPC Class Codes: H01L 2924/19041 being a capacitor

Abstract

One aspect of the invention relates to a flip-chip semiconductor package. In one version of the invention, the flip-chip semiconductor package includes a package substrate having an upper surface, a lower surface and a plurality of conductive traces, the upper surface having an upper plurality of electrical contacts coupled to the conductive traces, the lower surface having a lower plurality of electrical contacts coupled to the conductive traces, the lower plurality of electrical contacts being attachable to electrical contacts on a printed circuit board; a semiconductor die having an active surface and a non-active surface, the active surface having a plurality of circuit elements and a plurality of bond pads formed thereon, the bond pads being attached to the upper plurality of electrical contacts by solder bumps, the non-active surface having a plurality of grooves formed thereon; and a heat sink attached to the non-active surface of the semiconductor die.

Claims

1. A flip-chip semiconductor package comprising:

a package substrate having an upper surface, a lower surface and a plurality of conductive traces, the upper surface having an upper plurality of electrical contacts coupled to the conductive traces, the lower surface having a lower plurality of electrical contacts coupled to the conductive traces;

a semiconductor die having an active surface and a non-active surface, the active surface having a plurality of circuit elements and a plurality of bond pads formed thereon, the bond pads being attached to the upper plurality of electrical contacts by solder bumps, the non-active surface having a plurality of grooves formed thereon, the grooves increasing the surface area of the non-active surface of the semiconductor die;

a heat sink attached to the non-active surface of the semiconductor die with an adhesive, the adhesive filling the grooves between the heat sink and the semiconductor die, the grooves increasing the contact area of the adhesive to the semiconductor die thereby increasing the mechanical bond strength and thermal conductivity between the semiconductor die and the heat sink; and

wherein

at least a portion of one of the plurality of grooves is directly underneath a portion of the heat sink at a point where the portion of the heat sink is attached to the semiconductor die.

2. A semiconductor package as in claim 1 wherein the plurality of grooves are disposed in a cross-hatch pattern on the non-active surface.

3. A semiconductor package as in claim 1 wherein the plurality of grooves are disposed in parallel on the non-active surface.

4. A semiconductor package as in claim 1 wherein the plurality of grooves are formed with a depth of less than or equal to about one-half of the thickness of the semiconductor die.

5. A semiconductor package as in claim 1 wherein the plurality of grooves are formed with a width of between about one and about two times the depth of the grooves.

6. A semiconductor package as in claim 1 wherein the spacing between the plurality of grooves is between about one-half and about two times the width of the grooves.

7. A semiconductor package as in claim 1 wherein the bond pads are adhesively attached to the heat sink.

8. A method for attaching a semiconductor die to a heat sink in a flip-chip package, the semiconductor die having an active surface with a plurality of circuit elements and bond pads formed thereon and a non-active surface, the method comprising:

providing a semiconductor die with a plurality of grooves on the non-active surface, the grooves increasing the surface area of the non-active surface of the semiconductor die;

attaching the non-active surface to a surface of the heat sink with an adhesive, the adhesive filling the grooves between the heat sink and the semiconductor die, the grooves increasing the contact area of the adhesive to the semiconductor die thereby increasing the mechanical bond strength and thermal conductivity between the semiconductor die and the heat sink;

attaching the bond pads on the active surface on the semiconductor die to electrical contacts on a package substrate with solder bumps such that the active surface faces the package substrate; and

wherein

the step of attaching the non-active surface to a surface of the heat sink with an adhesive is performed such that at least a portion of one of the plurality of grooves is directly underneath a portion of the heat sink at a point where the portion of the heat sink is attached to the semiconductor die.

9. A method as in claim 8 wherein providing a semiconductor die with a plurality of grooves comprises providing a plurality of grooves in a cross-hatch pattern on the nonactive surface.

10. A method as in claim 8 wherein providing a semiconductor die with a plurality of grooves comprises providing a plurality of grooves in parallel on the non-active surface.

11. A method as in claim 8 wherein providing a semiconductor die with a plurality of grooves comprises providing a plurality of grooves formed with a depth of less than or equal to about one-half of the thickness of the semiconductor die.

12. A method as in claim 8 wherein providing a semiconductor die with a plurality of grooves comprises providing a plurality of grooves formed with a width of between about one and about two times the depth of the grooves.

13. A method as in claim 8 wherein providing a semiconductor die with a plurality of grooves comprises providing a plurality of grooves having a spacing of between about one-half and about two times the width of the grooves.

14. A method as in claim 8 wherein providing a semiconductor die with a plurality of grooves comprises sawing the grooves into the non-active surface.

15. A method as in claim 8 wherein providing a semiconductor die with a plurality of grooves comprises etching the grooves into the non-active surface.

16. A method as in claim 8 wherein attaching the non-active surface to a surface of the heat sink comprises disposing an adhesive between the non-active surface and the surface of the heat sink.