Texturing of a die pad surface for enhancing bonding strength in the surface attachment

• US 6,670,222 B1
• Filed: 01/29/2001
• Issued: 12/30/2003
• Est. Priority Date: 06/14/1997
• Status: Expired due to Term

• Current Assignee: Lumentum Operations, LLC (Lumentum Holdings Inc.)
• Original Assignee: Viavi Solutions, Inc. (Lumentum Holdings Inc.)
• Inventors: Brodsky, Mark A.
• Primary Examiner(s): Fahmy, Wael
• Assistant Examiner(s): Farahani, Dana
• Application Number:
  US09/772,436
• Time in Patent Office: 1,065 Days
• Field of Search: 438/613, 438/441, 438/461, 438/611, 438/612, 438/650, 438/686, 438/617, 438/610, 438/652, 438/118, 438/626, 257/622, 257/623, 257/684, 257/690, 257/711, 257/712, 257/714
• US Class Current: 438/118
• CPC Class Codes: H01L 21/4803 Insulating or insulated parts, e.g. mountings, containers, diamond heatsinks H01L21/4846 takes precedence; printed circuit boards H05K1/00
• CPC Class Codes: H01L 21/4821 Flat leads, e.g. lead frames with or without insulating supports
• CPC Class Codes: H01L 2224/05599 Material
• CPC Class Codes: H01L 2224/27013 for holding or confining the layer connector, e.g. solder flow barrier
• CPC Class Codes: H01L 2224/2919 with a principal constituent of the material being a polymer, e.g. polyester, phenolic based polymer, epoxy
• CPC Class Codes: H01L 2224/32057 in side view
• CPC Class Codes: H01L 2224/32225 the item being non-metallic, e.g. insulating substrate with or without metallisation
• CPC Class Codes: H01L 2224/45015 being circular
• CPC Class Codes: H01L 2224/45099 Material
• CPC Class Codes: H01L 2224/48227 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 2224/8314 Guiding structures outside the body
• CPC Class Codes: H01L 2224/8319 Arrangement of the layer connectors prior to mounting
• CPC Class Codes: H01L 2224/83385 Shape, e.g. interlocking features
• CPC Class Codes: H01L 2224/8385 using a polymer adhesive, e.g. an adhesive based on silicone, epoxy, polyimide, polyester
• CPC Class Codes: H01L 2224/85399 Material
• CPC Class Codes: H01L 23/13 characterised by the shape
• CPC Class Codes: H01L 23/49503 characterised by the die pad
• CPC Class Codes: H01L 23/49548 Cross section geometry H01L23/49562 takes precedence
• CPC Class Codes: H01L 24/32 of an individual layer connector
• CPC Class Codes: H01L 24/48 : of an individual wire connector
• CPC Class Codes: H01L 24/83 : using a layer connector
• 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 2924/01005 : Boron [B]
• CPC Class Codes: H01L 2924/01006 : Carbon [C]
• CPC Class Codes: H01L 2924/01013 : Aluminum [Al]
• CPC Class Codes: H01L 2924/01026 : Iron [Fe]
• CPC Class Codes: H01L 2924/01027 : Cobalt [Co]
• CPC Class Codes: H01L 2924/01028 : Nickel [Ni]
• CPC Class Codes: H01L 2924/01029 : Copper [Cu]
• CPC Class Codes: H01L 2924/01033 : Arsenic [As]
• CPC Class Codes: H01L 2924/01039 : Yttrium [Y]
• CPC Class Codes: H01L 2924/01047 : Silver [Ag]
• CPC Class Codes: H01L 2924/01049 : Indium [In]
• CPC Class Codes: H01L 2924/01068 : Erbium [Er]
• CPC Class Codes: H01L 2924/0107 : Ytterbium [Yb]
• CPC Class Codes: H01L 2924/01074 : Tungsten [W]
• CPC Class Codes: H01L 2924/01082 : Lead [Pb]
• CPC Class Codes: H01L 2924/01105 : Rare earth metals
• CPC Class Codes: H01L 2924/0132 : Binary Alloys
• CPC Class Codes: H01L 2924/014 : Solder alloys
• CPC Class Codes: H01L 2924/0665 : Epoxy resin
• CPC Class Codes: H01L 2924/07802 : not being an ohmic electrical conductor
• CPC Class Codes: H01L 2924/10253 : Silicon [Si]
• CPC Class Codes: H01L 2924/1204 : Optical Diode
• CPC Class Codes: H01L 2924/12043 : Photo diode
• CPC Class Codes: H01L 2924/14 : Integrated circuits
• CPC Class Codes: H01L 2924/15153 : the die mounting substrate comprising a recess for hosting the device
• CPC Class Codes: H01L 2924/15165 : Monolayer substrate
• CPC Class Codes: H01L 2924/181 : Encapsulation
• CPC Class Codes: H01L 2924/18301 : being an anchoring portion, i.e. mechanical interlocking between the encapsulation resin and another package part
• CPC Class Codes: H01L 2924/19041 : being a capacitor
• CPC Class Codes: H01L 2924/19043 : being a resistor
• CPC Class Codes: H01L 2924/207 : Diameter ranges

Abstract

Laser beam or pulsed output is provided for enhancing the bonding strength between surfaces that are secured together, such as by lamination process or an adhesive, by texturing with a plurality of indentations formed in at least one of the surfaces to be bonded. As an example of this texturing, a fiber gain medium texturing system having a modulated pump or seed semiconductor laser source may be employed for forming a plurality of indentations in the surface of a die attachment pad of a semiconductor die or IC chip carrier. The indentations may be in the form of dimples or grooves. The indentations enhance the bonding strength formed between the chip and the die attachment pad using a die attaching adhesive. Also, the indentations in the die attachment pad provide a way for containment of rapidly expanding gases that formed in the chip carrier package when the package is subjected to high temperatures such as during a solder reflow operation.

Claims

1. A method of bonding a semiconductor die to an attachment pad therefor comprising the steps of:

(a) directing a modulated laser output beam onto a plurality of surface regions of a surface portion of said attachment pad, so as to texture said surface portion of said attachment pad with a plurality of indentations; and

(b) attaching said semiconductor chip to said attachment pad, by an adhesive, which contacts each of a surface portion of said semiconductor chip directly facing said surface portion of said attachment pad and directly facing indentations that have been formed in said surface portion of said attachment pad in step (a).

2. The method according to claim 1, wherein step (a) comprises controlling a modulated laser output beam produced by a fiber gain medium with a modulated pump or seed semiconductor laser source for producing said modulated laser output beam.

3. The method of according to claim 2, wherein step (a) comprises controlling said modulated laser output beam, so as to texture said surface portion of said attachment pad with plural indentations having different characteristics.

4. The method of according to claim 3, wherein step (a) comprises controllably modulating a pulsed fiber amplifier based laser, so that a pulsed laser output beam thereof textures said bonding surface portion of said attachment pad with said plurality of indentations.

5. The method of according to claim 4, wherein step (a) comprises controllably modulating pump energy supplied to said pulsed fiber amplifier based laser.

6. The method of according to claim 5, wherein step (a) comprises controllably modulating at least one of the amount and duration of pump energy supplied to said pulsed fiber amplifier based laser.

7. A method of joining a first workpiece to a second workpiece comprising the steps of:

(a) directing a modulated laser output beam onto a plurality of surface regions of a bonding surface portion of said first workpiece, so as to texture said bonding surface portion of said first workpiece with a plurality of indentations;

(b) positioning said second workpiece so that a bonding surface portion thereof is directly facing indentations formed in said bonding surface portion of said first workpiece in step (a); and

(c) attaching said bonding surface portion of said second workpiece to said bonding surface portion of said first workpiece attachment pad, by an adhesive which bonds said bonding surface portion of said second workpiece with said indentations formed in said bonding surface portion of said first workpiece and directly facing said bonding surface portion of said second workpiece.

8. The method of according to claim 7, wherein step (a) comprises controlling said modulated laser output beam, so as to texture said bonding surface portion of said first workpiece with plural indentations having different characteristics.

9. The method of according to claim 7, wherein step (a) comprises controlling said modulated laser output beam, so as to texture said bonding surface portion of said first workpiece with plural indentations having different widths and depths.

10. The method of according to claim 7, wherein step (a) comprises controlling said modulated laser, output beam, so as to texture said bonding surface portion of said first workpiece with plural indentations having different shapes.

11. The method of according to claim 7, wherein second workpiece comprises a semiconductor chip and said first workpiece comprises an attachment pad for said semiconductor chip.

12. The method of according to claim 7, wherein step (a) comprises controllably modulating a pulsed fiber amplifier based laser, so that a pulsed laser output beam thereof textures said bonding surface portion of said first workpiece with said plurality of indentations.

13. The method of according to claim 12, wherein step (a) comprises controllably modulating pump energy supplied to said pulsed fiber amplifier based laser.

14. The method of according to claim 13, wherein step (a) comprises controllably modulating at least one of the amount and duration of pump energy supplied to said pulsed fiber amplifier based laser.