Semiconductor Device and Method of Die Attach with Adhesive Layer Containing Graphene-Coated Core
20240194628 ยท 2024-06-13
Assignee
Inventors
Cpc classification
H01L25/162
ELECTRICITY
H01L25/0652
ELECTRICITY
H01L23/49816
ELECTRICITY
H01L2224/29493
ELECTRICITY
H01L2224/2929
ELECTRICITY
H01L23/49805
ELECTRICITY
H01L2224/48137
ELECTRICITY
H01L24/73
ELECTRICITY
International classification
H01L23/373
ELECTRICITY
H01L23/498
ELECTRICITY
H01L25/065
ELECTRICITY
Abstract
A semiconductor device has a substrate and an adhesive layer with a graphene core shell deposited over a surface of the substrate. An electrical component is affixed to the substrate with the adhesive layer. A bond wire is connected between the electrical component and substrate. The graphene core shell has a copper core and graphene coating over the copper core. The graphene coated core shell is embedded within a matrix. The graphene core shells within the adhesive layer to form a thermal path. The matrix can be a thermoset material or polymer or composite epoxy type matrix. The graphene core shell is embedded within the thermoset material or polymer or composite epoxy type matrix. The adhesive layer with graphene core shell is useful for die attachment. The graphene core adhesive layer provides exceptional heat dissipation, shock absorption, and vibration dampening.
Claims
1. A semiconductor device, comprising: a substrate; an adhesive layer including a graphene core shell deposited over a surface of the substrate; and an electrical component affixed to the substrate with the adhesive layer.
2. The semiconductor device of claim 1, wherein the graphene core shell includes a copper core.
3. The semiconductor device of claim 2, wherein the graphene core shell further includes a graphene coating formed over the copper core.
4. The semiconductor device of claim 1, wherein the adhesive layer further includes a matrix to embed the graphene core shell.
5. The semiconductor device of claim 1, wherein the adhesive layer includes a plurality of cores covered by graphene and the graphene is interconnected within the adhesive layer to form a thermal path.
6. The semiconductor device of claim 1, wherein the adhesive layer includes thermoset material or polymer or composite epoxy type matrix and the graphene core shell is embedded within the thermoset material or polymer or composite epoxy type matrix.
7. A semiconductor device, comprising: a substrate; a graphene core adhesive layer deposited on a surface of the substrate; and an electrical component affixed to the substrate with the graphene core adhesive layer.
8. The semiconductor device of claim 7, wherein the graphene core adhesive layer includes a copper core.
9. The semiconductor device of claim 8, wherein the graphene core adhesive layer further includes a graphene coating formed over the copper core.
10. The semiconductor device of claim 9, wherein the graphene core adhesive layer further includes a matrix to embed the graphene coated copper core.
11. The semiconductor device of claim 7, wherein the adhesive layer includes a plurality of cores covered by graphene and the graphene is interconnected within the adhesive layer to form a thermal path.
12. The semiconductor device of claim 7, wherein the adhesive layer includes thermoset material or polymer or composite epoxy type matrix and the graphene core shell is embedded within the thermoset material or polymer or composite epoxy type matrix.
13. The semiconductor device of claim 7, further including a bond wire connected between the electrical component and substrate.
14. A method of making a semiconductor device, comprising: providing a substrate; depositing an adhesive layer including a graphene core shell over a surface of the substrate; and affixing an electrical component to the substrate with the adhesive layer.
15. The method of claim 14, wherein the graphene core shell includes providing a copper core.
16. The method of claim 15, wherein the graphene core adhesive layer further includes forming a graphene coating over the copper core.
17. The method of claim 16, wherein the adhesive layer further includes embedding the graphene coated copper core in a matrix.
18. The method of claim 14, wherein the adhesive layer includes: providing a plurality of cores covered by graphene; and interconnecting the graphene within the adhesive layer to form a thermal path.
19. The method of claim 14, further including providing a bond wire connected between the electrical component and substrate.
20. A method of making a semiconductor device, comprising: providing a substrate; depositing a graphene core adhesive layer over a surface of the substrate; and affixing an electrical component to the substrate with the graphene core adhesive layer.
21. The method of claim 20, wherein the graphene core adhesive layer includes providing a copper core.
22. The method of claim 21, wherein the graphene core adhesive layer further includes forming a graphene coating over the copper core.
23. The method of claim 22, wherein the graphene core adhesive layer further includes embedding the graphene coated copper core in a matrix.
24. The method of claim 20, wherein the adhesive layer includes: providing a plurality of cores covered by graphene; and interconnecting the graphene within the adhesive layer to form a thermal path.
25. The method of claim 20, further including providing a bond wire connected between the electrical component and substrate.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
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DETAILED DESCRIPTION OF THE DRAWINGS
[0014] The present invention is described in one or more embodiments in the following description with reference to the figures, in which like numerals represent the same or similar elements. While the invention is described in terms of the best mode for achieving the invention's objectives, it will be appreciated by those skilled in the art that it is intended to cover alternatives, modifications, and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims and their equivalents as supported by the following disclosure and drawings. The features shown in the figures are not necessarily drawn to scale. Elements having a similar function are assigned the same reference number in the figures. The term semiconductor die as used herein refers to both the singular and plural form of the words, and accordingly, can refer to both a single semiconductor device and multiple semiconductor devices.
[0015] Semiconductor devices are generally manufactured using two complex manufacturing processes: front-end manufacturing and back-end manufacturing. Front-end manufacturing involves the formation of a plurality of die on the surface of a semiconductor wafer. Each die on the wafer contains active and passive electrical components, which are electrically connected to form functional electrical circuits. Active electrical components, such as transistors and diodes, have the ability to control the flow of electrical current. Passive electrical components, such as capacitors, inductors, and resistors, create a relationship between voltage and current necessary to perform electrical circuit functions.
[0016] Back-end manufacturing refers to cutting or singulating the finished wafer into the individual semiconductor die and packaging the semiconductor die for structural support, electrical interconnect, and environmental isolation. To singulate the semiconductor die, the wafer is scored and broken along non-functional regions of the wafer called saw streets or scribes. The wafer is singulated using a laser cutting tool or saw blade. After singulation, the individual semiconductor die are disposed on a package substrate that includes pins or contact pads for interconnection with other system components. Contact pads formed over the semiconductor die are then connected to contact pads within the package. The electrical connections can be made with conductive layers, bumps, stud bumps, conductive paste, or wirebonds. An encapsulant or other molding material is deposited over the package to provide physical support and electrical isolation. The finished package is then inserted into an electrical system and the functionality of the semiconductor device is made available to the other system components.
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[0019] An electrically conductive layer 112 is formed over active surface 110 using physical vapor deposition (PVD), chemical vapor deposition (CVD), electrolytic plating, electroless plating process, or other suitable metal deposition process. Conductive layer 112 can be one or more layers of aluminum (Al), copper (Cu), tin (Sn), nickel (Ni), gold (Au), silver (Ag), or other suitable electrically conductive material. Conductive layer 112 operates as contact pads electrically connected to the circuits on active surface 110.
[0020] In
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[0022] In
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[0024] In
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[0026] Support segments 129 are severed leaving pads 128 electrically isolated from each other. The combination of substrate 120, semiconductor die 104, and encapsulant 138 constitutes semiconductor package 139.
[0027]
[0028] In another embodiment,
[0029] Cores 140 are arranged within matrix 147 so that most if not all graphene coatings 142 covering the core contact at least one adjacent graphene coating to form a continuous and connecting path 149 of graphene coatings between top surface 124 of leadframe flag 122 and adhesive layer 148 at surface 108 of semiconductor die 104. Graphene coating 142 of each core 140 contacts the graphene coating of an adjacent core. A first graphene coating 142 contacts a second adjacent graphene coating, which in turn contacts a third adjacent graphene coating, and so on, to form continuous and connecting path 149. Cores 140 have sufficient density that most if not all the graphene coatings around the cores contact at least one graphene coating around an adjacent core, and typically contact graphene coating of multiple adjacent cores.
[0030]
[0031] Core 140 is PCM capable of phase change from solid to liquid phase or from liquid phase to solid phase within the operating temperature range of the semiconductor chip, e.g., 20-200? C. A first coating 154 is formed around PCM core 140, as shown in
[0032] The properties of graphene are summarized in Table 1, as follows:
TABLE-US-00001 TABLE 1 Properties of graphene Parameter Electronic mobility 2 ? 10.sup.5 cm.sup.2 V.sup.?1 s.sup.?1 Current density 10.sup.9 A cm.sup.?1 Velocity of fermion (electron) 10.sup.6 m s.sup.?1 Thermal conductivity 4000-5000 W m.sup.?1 K.sup.?1 Tensile strength 1.5 Tpa Breaking strength 42 N m.sup.?1 Transparency 97.7% Elastic limit 20% Surface area 2360 m.sup.2 g.sup.?1
[0033] Graphene 142 has ten times the electrical conductivity of Cu. Graphene 142 enables epoxy to exhibit electrical conductivity similar to Ag, while reducing or eliminating oxidation. Core shell 158 with Cu and graphene epoxy is low cost, as compared to sputtering. Graphene 142 has a low moisture permeability and a high thermal conductivity of 4000-5000 W m.sup.?1 K.sup.?1, 10 times higher than Cu at room temperature. Since carbon also has a good solderability and wettability of solder paste, adhesive layer 130 can be readily formed. Graphene 142 exhibits a high degree of flexibility and remains stable against warpage. Adhesive layer 130 with graphene Cu shells 158 improves die attach properties and electrical conductivity, while lowering manufacturing cost.
[0034] In another embodiment, semiconductor package 160 uses leadframe substrate 162 with flags 164a and 164 and pads 168a and 168b, similar to leadframe substrate 120 but with multiple flags for mounting multiple semiconductor die, as shown in
[0035] Semiconductor die 190 is affixed to adhesive layer 170 over flag 164b, similar to
[0036] An encapsulant or molding compound 196 is deposited over and around semiconductor die 170, 180, and 190 and leadframe substrate 162 using a paste printing, compressive molding, transfer molding, liquid encapsulant molding, vacuum lamination, spin coating, or other suitable applicator. Encapsulant 196 can be liquid or granular polymer composite material, such as epoxy resin with filler, epoxy acrylate with filler, or polymer with proper filler. Encapsulant 196 is non-conductive, provides structural support, and environmentally protects the semiconductor device from external elements and contaminants.
[0037] In another embodiment, semiconductor package 200 uses substrate 204 with a base substrate material, such as silicon, germanium, aluminum phosphide, aluminum arsenide, gallium arsenide, gallium nitride, indium phosphide, silicon carbide for structural support, as shown in
[0038] Electrical components 202a-202e are disposed on surface 206 of substrate 204. In particular, electrical components 202b and 202c are disposed on surface 206 using adhesive layer 208, similar to
[0039] Bond wires 210 electrically connect electrical components 202b and 202c to substrate 204. An encapsulant or molding compound 212 is deposited over and around electrical components 202a-202e and substrate 204 using a paste printing, compressive molding, transfer molding, liquid encapsulant molding, vacuum lamination, spin coating, or other suitable applicator. Encapsulant 212 can be liquid or granular polymer composite material, such as epoxy resin with filler, epoxy acrylate with filler, or polymer with proper filler. Encapsulant 212 is non-conductive, provides structural support, and environmentally protects the semiconductor device from external elements and contaminants.
[0040] In another embodiment, substrate 222 contains base substrate material 226, such as silicon, germanium, aluminum phosphide, aluminum arsenide, gallium arsenide, gallium nitride, indium phosphide, or silicon carbide for structural support, as shown in
[0041] In
[0042] An adhesive layer 246 is deposited over conductive layer 240. Adhesive layer 246 is made similar to adhesive layer 130, containing a matrix and core shells, as described in
[0043] Adhesive layers 246 and 250 with matrix and graphene core shells provide improved die attach properties for electrical components 244b and 244c and substrate 243, as described for adhesive layer 130 in
[0044] An adhesive layer like 130 with graphene core shells such as 158 distributed in matrix 144 are useful for die attachment. Same is true for adhesive layers 170, 208, 246, and 250. The graphene core adhesive layer provides exceptional heat dissipation, shock absorption, and vibration dampening. The graphene core adhesive layer can be used in power applications, such as automotive, to support physical stress, vibration, temperature variation, high voltage, high power, and high frequency operation.
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[0046] Electrical device 400 can be a stand-alone system that uses the semiconductor packages to perform one or more electrical functions. Alternatively, electrical device 400 can be a subcomponent of a larger system. For example, electrical device 400 can be part of a tablet, cellular phone, digital camera, communication system, or other electrical device. Alternatively, electrical device 400 can be a graphics card, network interface card, or other signal processing card that can be inserted into a computer. The semiconductor package can include microprocessors, memories, ASIC, logic circuits, analog circuits, RF circuits, discrete devices, or other semiconductor die or electrical components. Miniaturization and weight reduction are essential for the products to be accepted by the market. The distance between semiconductor devices may be decreased to achieve higher density.
[0047] In
[0048] In some embodiments, a semiconductor device has two packaging levels. First level packaging is a technique for mechanically and electrically attaching the semiconductor die to an intermediate substrate. Second level packaging involves mechanically and electrically attaching the intermediate substrate to the PCB. In other embodiments, a semiconductor device may only have the first level packaging where the die is mechanically and electrically disposed directly on the PCB. For the purpose of illustration, several types of first level packaging, including bond wire package 406 and flipchip 408, are shown on PCB 402. Additionally, several types of second level packaging, including ball grid array (BGA) 410, bump chip carrier (BCC) 412, land grid array (LGA) 416, multi-chip module (MCM) or SIP module 418, quad flat non-leaded package (QFN) 420, quad flat package 422, embedded wafer level ball grid array (eWLB) 424, and wafer level chip scale package (WLCSP) 426 are shown disposed on PCB 402. In one embodiment, eWLB 424 is a fan-out wafer level package (Fo-WLP) and WLCSP 426 is a fan-in wafer level package (Fi-WLP). Depending upon the system requirements, any combination of semiconductor packages, configured with any combination of first and second level packaging styles, as well as other electrical components, can be connected to PCB 402. In some embodiments, electrical device 400 includes a single attached semiconductor package, while other embodiments call for multiple interconnected packages. By combining one or more semiconductor packages over a single substrate, manufacturers can incorporate pre-made components into electrical devices and systems. Because the semiconductor packages include sophisticated functionality, electrical devices can be manufactured using less expensive components and a streamlined manufacturing process. The resulting devices are less likely to fail and less expensive to manufacture resulting in a lower cost for consumers.
[0049] While one or more embodiments of the present invention have been illustrated in detail, the skilled artisan will appreciate that modifications and adaptations to those embodiments may be made without departing from the scope of the present invention as set forth in the following claims.