PACKAGING A SEMICONDUCTOR DEVICE HAVING WIRES WITH POLYMERIZED INSULATOR SKIN

• US 20150037938A1
• Filed: 10/22/2014
• Published: 02/05/2015
• Est. Priority Date: 04/18/2012
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Castro, Abram, Zhang, Rongwei
• Granted Patent: US 9,378,984 B2
• Time in Patent Office: Days
• US Class Current: 438/123
• CPC Class Codes: B29C 45/0001 characterised by the choice of material
• CPC Class Codes: B29C 45/0046 Details relating to the filling pattern or flow paths or flow characteristics of moulding material in the mould cavity
• CPC Class Codes: B29C 45/14655 connected to or mounted on a carrier, e.g. lead frame
• CPC Class Codes: B29C 45/14836 Preventing damage of inserts during injection, e.g. collapse of hollow inserts, breakage B29C45/14434 takes precedence
• CPC Class Codes: C08K 3/10 Metal compounds
• CPC Class Codes: C08K 3/36 Silica
• CPC Class Codes: C08K 7/14 Glass
• CPC Class Codes: H01B 3/40 epoxy resins
• CPC Class Codes: H01L 21/56 Encapsulations, e.g. encapsulation layers, coatings
• CPC Class Codes: H01L 21/565 Moulds
• CPC Class Codes: H01L 2224/04042 Bonding areas specifically adapted for wire connectors, e.g. wirebond pads
• CPC Class Codes: H01L 2224/05624 Aluminium [Al] as principal constituent
• CPC Class Codes: H01L 2224/05647 Copper [Cu] as principal constituent
• 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 2224/32225 the item being non-metallic, e.g. insulating substrate with or without metallisation
• CPC Class Codes: H01L 2224/32245 the item being metallic
• CPC Class Codes: H01L 2224/4382 Applying permanent coating, e.g. in-situ coating
• CPC Class Codes: H01L 2224/43848 Thermal treatments, e.g. annealing, controlled cooling
• CPC Class Codes: H01L 2224/45014 Ribbon connectors, e.g. rectangular cross-section
• CPC Class Codes: H01L 2224/45015 being circular
• CPC Class Codes: H01L 2224/45124 : Aluminium (Al) as principal constituent
• CPC Class Codes: H01L 2224/45144 : Gold (Au) as principal constituent
• CPC Class Codes: H01L 2224/45147 : Copper (Cu) as principal constituent
• CPC Class Codes: H01L 2224/48091 : Arched
• CPC Class Codes: H01L 2224/48221 : the body and the item being stacked
• CPC Class Codes: H01L 2224/48227 : connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/48247 : connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/48463 : the connecting portion on the bonding area of the semiconductor or solid-state body being a ball bond
• CPC Class Codes: H01L 2224/48465 : the other connecting portion not on the bonding area being a wedge bond, i.e. ball-to-wedge, regular stitch
• CPC Class Codes: H01L 2224/485 : Material
• CPC Class Codes: H01L 2224/48624 : Aluminium (Al) as principal constituent
• CPC Class Codes: H01L 2224/48647 : Copper (Cu) as principal constituent
• CPC Class Codes: H01L 2224/48724 : Aluminium (Al) as principal constituent
• CPC Class Codes: H01L 2224/48747 : Copper (Cu) as principal constituent
• CPC Class Codes: H01L 2224/48824 : Aluminium (Al) as principal constituent
• CPC Class Codes: H01L 2224/48847 : Copper (Cu) as principal constituent
• CPC Class Codes: H01L 2224/73265 : Layer and wire connectors
• CPC Class Codes: H01L 2224/8592 : Applying permanent coating, e.g. protective coating
• CPC Class Codes: H01L 2224/92247 : the second connecting process involving a wire connector
• CPC Class Codes: H01L 23/295 : containing a filler H01L23/296 takes precedence
• CPC Class Codes: H01L 23/4952 : the additional leads being a bump or a wire
• CPC Class Codes: H01L 24/05 : of an individual bonding area
• CPC Class Codes: H01L 24/29 : of an individual layer connector
• CPC Class Codes: H01L 24/32 : of an individual layer connector
• CPC Class Codes: H01L 24/43 : Manufacturing methods
• CPC Class Codes: H01L 24/45 : of an individual wire connector
• CPC Class Codes: H01L 24/48 : of an individual wire connector
• CPC Class Codes: H01L 24/85 : using a wire connector wire bonding in general B23K20/004
• 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 2924/00012 : Relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• 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 2924/0665 : Epoxy resin
• CPC Class Codes: H01L 2924/078 : Adhesive characteristics other than chemical
• CPC Class Codes: H01L 2924/10253 : Silicon [Si]
• CPC Class Codes: H01L 2924/10271 : Silicon-germanium [SiGe]
• CPC Class Codes: H01L 2924/1032 : III-V
• CPC Class Codes: H01L 2924/10329 : Gallium arsenide [GaAs]
• CPC Class Codes: H01L 2924/181 : Encapsulation
• CPC Class Codes: H01L 2924/206 : Length ranges
• CPC Class Codes: H01L 2924/20752 : larger or equal to 20 microns less than 30 microns
• CPC Class Codes: H01L 2924/3862 : Sweep

Abstract

A chip is attached to a substrate with wires spanning from the chip to the substrate is loaded in a heated cavity of a mold. The wire surfaces are coated with an adsorbed layer of molecules of a heterocyclic compound. A pressure chamber of the mold is loaded with a solid pellet of a packaging material including a polymerizable resin. The chamber is connected to the cavity. The vapor of resin molecules is allowed to spread from the chamber to the assembly inside the cavity during the time interval needed to heat the solid pellet for rendering it semi-liquid and to pressurize it through runners before filling the mold cavity, wherein the resin molecules arriving in the cavity are cross-linked by the adsorbed heterocyclic compound molecules into an electrically insulating at least one monolayer of polymeric structures on the wire surfaces.

Claims

1-6. -6. (canceled)

7. A method for fabricating a packaged semiconductor device comprising:

loading the heated cavity of a mold with an assembly including a semiconductor chip attached to a substrate and wires spanning from the chip to the substrate, the wire surfaces coated with an adsorbed layer of molecules of a heterocyclic compound;

loading the heated pressure chamber of the mold with a solid pellet of a packaging material including a polymerizable resin, the chamber being connected to the cavity; and

allowing the vapor of resin molecules to spread and be pushed from the chamber to the assembly inside the cavity during the time interval needed to heat the solid pellet for rendering it semi-liquid and to pressurize it through the mold runners before filling the mold cavity,

wherein the resin molecules arriving in the cavity are cross-linked by the adsorbed heterocyclic compound molecules into at least a monolayer of polymeric structure on the wire surfaces.

8. The method of claim 7 further including, prior to loading the cavity, dispensing a solution of a heterocyclic compound dissolved in ethanol onto the wires spanned from a semiconductor chip to the substrate, wherein a layer of molecules of the heterocyclic compound is adsorbed on the wire surfaces.

9. The method of claim 7 wherein the solution has a concentration of about 1 millimole per liter (mmol/L) heterocyclic compound in ethanol.

10. The method of claim 7 wherein the heterocyclic compound is selected from a group including pyrrole (C₄H₅N₁), pyrazole and imidazole (C₃H₄N₂), containing a five-membered di-unsaturated ring with two non-adjacent nitrogen atoms as part of the ring;

triazole (C₂H₃N₃), containing a five-membered ring with three nitrogen atoms as part of the ring;

pentazolde, thiazole, isothiazole, and their derivatives.

11. The method of claim 7 wherein the polymerizable resin is an epoxy resin selected from a group including bisphenol A and novalac.

12. The method of claim 11 wherein the liquefying temperature of the solid polymerizable resin is about 175°

C.

13. The method of claim 7 wherein the packaging material further includes a curing agent selected from a group including amines, acid anhydrates, and phenol novalac resins.

14. The method of claim 13 wherein the packaging material further includes inorganic fillers.

15. The method of claim 7 wherein the substrate is a metal leadframe having an assembly pad for attaching the chip and leads for attaching the wires.