Embodiments of the invention relate to the field of integrated circuit manufacturing; and more specifically, to the field of temporary bond de-bond processes for manufacturing assemblies.
The disclosure may best be understood by referring to the following description and accompanying drawings that are used to illustrate embodiments of the invention. In the drawings:
In some embodiments, a patternable TBDB for assembling complex 3D IC/optical assemblies are provided. A patternable TBDB adhesive may be formed using silicone based TBDB adhesives with incorporated photocatalysts to allow for patterning of the TBDB adhesive layer. Implementation of photoactive catalysts or initiators for TBDB adhesives allows for obtaining mm-based cavities within adhesive coatings on wafer such as with glass wafers. For example, negative type photo patterning may be employed. to attain TBDB adhesive patterns suitable for die level reconstitution. This can enable the assembly and HVM (high volume manufacturing) production of 3D IC/optical component assemblies with incompatible dimensions while avoiding adverse contact with the carrier surface.
Multi component assemblies such as with 3D silicon photonic packages are used for a wide variety of applications such as compute devices, telecommunications, and industrial machines. They can include several different types components such as integrated circuits (ICs), sensors, MEM (micro-electrical-mechanical) devices, optical structures, and the like. They can be challenging to manufacture, however, since they are commonly formed from different materials which may or may not have similar thermal characteristics, structural integrity, or resilience against environmental conditions such as pressure and chemical or electro-magnetic exposure. They can also have dimensions that are not suited for high volume manufacturing with each other. Accordingly, some embodiments provide a way to bond together differently dimensioned components without risking destructive impact from nearby obstructions.
Packaging such a 3D structure, however, poses unique challenges during die and component assembly. For example the optical coupler 120 is extremely fragile and may have different, e.g., thicker, dimensions than the EIC 110.
At 200A, a side view of the carrier wafer 255 and EIC 110 are depicted. The EIC 110, with its hybrid contacts facing upward, is depressed downward onto the adhesive surface, as shown at 200B. (Note that for ease of explanation, only one assembly is shown but in a typical high volume manufacturing, HVM, scenario, many assemblies would be present on the wafer and assembled together in parallel with one another.) Observe that the EIC displaces, or compresses, the adhesive beneath its underside surface. In contrast, the adhesive next to the EIC remains at its initial thickness, e.g. tens of microns or more above the EIC underside. In addition, it may be harder, fi cured, or otherwise set for the next step.
Next, as indicated at 200 C, the PIC (130)-OC (120) assembly is forced downward to mount the PIC with the upper surface of the EIC. As can be seen, the OC 120 is also brought downward and with its thicker dimension, makes contact with the adhesive. The mounted assembly is depicted at 200D. Also shown is a top view of the wafer 255 with rows of optical interconnect (OI) assemblies. Unfortunately, as is illustrate, cracking in the OC 130 can occur due to its impact with the adhesive. Catalyst raw materials for conventional TBDB adhesives typically allow only for thermal curing to form blanket coatings. The lack of catalyst variety makes it extremely difficult, if not prohibitive, to implement facile selective curing. Moreover, thinner reconstitution adhesives are not desirable because of increase die warpage and the adverse impact on coplanarity and die adhesion. Accordingly, a new approach for assembling modules using carriers with TBDB stabilization is desired.
With reference to
A photoresist (also known simply as a resist) is a light-sensitive material used in several processes, such as photolithography to form a patterned coating on a surface. In some embodiments, temporary bond de-bond (TBDB) adhesives that allow for photopatterning via UV induced crosslinking are provided. A patternable TBDB adhesive may maintain existing crosslinking approaches (e.g. thermal), but also provide additional material flexibility via negative, or positive, type photo-patterning. Radical or coordination-based chemistries may be leveraged to enable patternable adhesive by paring conventional TBDB adhesives (e.g., silicone-based adhesives) with a photo-initiator.
In some embodiments, patternable TBDB adhesives may be obtained by transforming a material suitable as a TBDB adhesive (e.g. hydrogenated amorphous silicon [a: Si—H], and/or various polymers such as polyelectrolyte [iCVD], polyglycidylmethacrylate (PGMA), and polydimethylglutarimide [PMGI]) into a photopolymer. Photopolymers can be formed from prepolymers, oligomers, monomers, or mixtures thereof (hereinafter referred to as Photopolymer precursor or PPP), combined with materials added that interact with the PPP upon exposure to light to produce the desired cross-linking, or cleaving, depending on whether the patternable TBDB is implementing a negative or positive photoresist process, respectively. (For simplicity, and ease of discussion, the disclosure will focus on negative patterning, but different embodiments may also encompass positive patterning.)
For patternable TBDB, there are at least two types of photo-polymerization systems: autonomous reactant systems and complementary reactant systems. With autonomous reactant systems, multifunctional (e.g., low molecular weight monomers or oligomers) possessing polymerizable functional groups, X, undergo a photoinitiated radical, cationic, or anionic chain polymerization on irradiation to yield cross-linked network polymers. A photo-initiator, PI, is typically required. On the other hand, with complementary reactant systems, a photopolymer system may include two-components with each component bearing complementary reactive functional groups, X and Y. The reaction between X and Y results from the excitation of one of the groups by light or alternatively, it may occur through the mediation of a photo-initiator. For example, thiolene and thiolyne photopolymers can undergo facile cross-linking polymerization on irradiation in the presence of a free radical photoinitiator.
In some embodiments, suitable precursor mixtures may be synthesized from raw starter components or from existing TBDB adhesive solutions or mixtures thereof, modified with additives such as reactants, PI, solvents, and/or catalyst in order to control desired network properties. UV curable mixtures, depending on the type of photo-reacting crosslinking, generally include one or more PPPs (photo-polymer precursors).
PPPs comprise prepolymers, oligomers, reactive small molecules, multifunctional oligomers, or mixtures thereof. For example, because of their polyfunctionality, multifunctional oligomers enable network formation and dictation of the degree of crosslinking. Silicone based PPPs may be well suited for many patternable TBDB adhesives. for example, silicones with functional vinyl and hydrides may be used. Functional silicones, e.g., vinyl end-blocked silicone fluids provide reactive sites for cross-linking by ultraviolet (UV) accelerated free radical cross-linking. Functional vinyl silicones include many suitable compounds such as VOS (Vinylolysiloxane silicone), VPS (vinyl polysiloxane silicone), and PDMS (polydimethylsiloxane). VOS and VPS are typically used as impression materials but may be suitable with appropriate modification as a PPP to attain a patternable TBDB material. PDMS is a silicone elastomer commonly used for TBDB adhesives and are well suited as PPPs for patternable TBDB adhesive formulations.
Any suitable chemistry systems may be used to generate a patternable TBDB from these PPPs, depending on various factors including desired patterned structural integrity, post photo exposure, adhesive integrity once assembly components are attached to a carrier, solvents/PIs/development parameters that are desired to be employed, etc. For example, if a coordination based crosslinking is desired, epoxy chemistries using purpose built catalysts such as a Pt (platinum) catalyst could be used. Alternatively, if radical based photopolymerization is employed, other chemistries such as acrylate, N-vinyl urethane, and/or thiolene system chemistries (also with the use of Pt catalysts) could be used. Acrylates with their double bonds can readily facilitate crosslinking reactions. Common acrylated reactants include: acrylic acrylates, polyester acrylates, epoxy acrylates, urethane acrylates, amine modified polyether acrylates, and polyether acrylates. Thiolene systems may also work well, e.g., with functional vinyl-containing silicones, to create suitable patternable TBDB materials.
IN this example, with a Pt catalyst (PI), a Thiolene chemistry is employed with the exemplary reaction shown in
Reactive diluents (e.g., monomers, multi-functional monomers, or oligomers), depending on the type of implemented photo-polymerization, can serve a reaction in one or some of various different ways. For example, a reactive diluent can act as a thinner to control the rheology of the liquid material and then react with the photoinitiator leading to the formation of the polymeric matrix and be used to modulate obtained thermomechanical and chemical performance of the obtained cross-linked network.
Photo-initiators are used to initiate the photopolymerization of PPPs and/or any associated reactants. The photoinitiator decomposes when it is activated by UV irradiation, thus leading to the formation of radical or cation/anion active species, which initiate the active monomers or oligomers in the reaction system. Thus, by exposing the polymeric mixture to a suitable UV light source (e.g., 365 nm, etc.) the liquid (e.g., viscous liquid) coating can be rapidly converted into a crosslinked coherent adhesive film that ins insoluble to a solvent used for pattern development for removing the unscanned resist.
For free radical initiation, Suitable photoinitiators (PIs) such as for Thiolene and acrylate curing may include but are not limited to Hydroxyketones (e.g., 1-Hydroxy-cyclohexyl-phenyl-ketone; 2-Hydroxy-2-methyl-1-phenyl-1-propanone); Phenylglyoxylates (e.g., Methylbenzoylformate, oxy-phenyl-acetic acid 2-[2 oxo-2, phenyl-acetoxy-ethoxy]-ethyl ester, oxy-phenyl-acetic 2[2-hydroxy-ethoxy]-ethyl ester); Aminoketones (e.g., 2-Benzyl-2-(dimethylamino)-1-[4-(4-morpholinyl)phenyl]-1-butanone, 2-Benzyl-2-(dimethylamino)-1-[4-(4-morpholinyl)phenyl]-1-butanone, 2-Methyl-1-[4-(methylthio)phenyl]-2-(4-morpholinyl)-1-propanone); Mono Acyl Phosphines (e.g., Diphenyl (2,4,6-trimethylbenzoyl)-phosphine oxide); and other groups such as Bis Acyl Phosphines; Phosphine oxides; Metallocene and Iodonium salts.
For photo acid generators, e.g., for epoxy and cationic polymerizations, suitable PIs may include sulfonium and iodonium salts such as Triphenylsulfonium Hexafluoroantimonate, sulfonium HexafluoroantimonateT4013Triphenylsulfonium HexafluorophosphateD5990Diphenyl[4-(phenylthio) phenyl]sulfonium HexafluorophosphateH1776 (4-Hydroxyphenyl)dimethylsulfonium Hexafluorophosphate, Triphenylsulfonium Hexafluoroantimonate, Diphenyl[4-(phenylthio) phenyl]sulfonium Hexafluoroantimonate, Triphenylsulfonium, Hexafluorophosphate, Diphenyl[4-(phenylthio)phenyl]sulfonium Hexafluorophosphate, (4-Hydroxyphenyl)dimethylsulfonium Hexafluorophosphate, [4-(Octyloxy)phenyl](phenyl) iodonium Hexafluoroantimonate, [4-[(2-Hydroxytetradecyl)oxy]phenyl]phenyliodonium Hexafluoroantimonate, Bis (4-tert-butylphenyl) iodonium HexafluoroantimonateI, and 4-Isopropyl-4′-methyldiphenyliodonium Tetrakis (pentafluorophenyl) borate.
Any suitable catalyst may be used. For example, with a silicone based adhesive precursor, a platinum based catalyst may be desired. For example, hydrosilylation reactions may be catalyzed by highly active platinum catalysts, such as the silicone-soluble Karstedt's catalyst. Suitable solvents may also be employed, e.g., to adjust solution viscosity for processability. It should be appreciated that for specific implementations, depending on utilized pre-polymer TBDB precursor materials and other considerations, prepolymer loading architectures and molecular weight facilities will likely be made. Along these lines, selection of particular photoinitiators will dictate the photon efficiency and the wavelength suitable for polymerization.
Next, at 300B (
This process results in partial (“soft”) curing of the TBDB adhesive, enough to adhere upon being developed but sufficiently malleable and adhering to secure assemblies until more rigidly fixed through a post-cure step. cutting edge UV sources and lithography materials are not required. For example, wavelengths of 365 nm, 405 nm, and 385 nm may be used. In one example, a 50 mW/cm2 projection at 365 nm was employed with a platinum UV active catalyst, which induced crosslinking of vinyl and hydride functionalized silicones in a silicone based TBDB adhesive. Whether laser or projector based light sources are employed, mm-dimension features, even with simple development solvents, may be achieved.
With respect to
At 300D (
From here, the carrier is baked to complete the remaining degree of cure in the adhesive material, mechanically locking the EIC units in place without voiding and shift during subsequent processes. For example, the carriers may be conveyed using adhesive rolls, nematic conveyors or other mechanisms. The hard cured adhesive serves to stabilize the EICs for subsequent assembly bonds, and it also protects the bump contacts on the EIC undersides.
Next, at 300E (
Illustrative examples of the technologies disclosed herein are provided below. An embodiment of the technologies may include any one or more, and any compatible combination of, the examples described below.
Example 1 is a fabrication process. The process includes applying a TBDB photopolymer adhesive to a carrier and exposing the TBDB photopolymer to a UV or electron beam pattern to create soft-cured adhesive portions and recess portions where adhesive has been removed. It also includes disposing first components onto the surfaces of the soft cured adhesive portions, and mounting a separate second component onto each first component, wherein each second component has an over-hanging portion that is disposed within a proximal recess portion without contacting a carrier surface when the second components are mounted to the first components.
Example 2 includes the subject matter of example 1, and wherein the first component is an integrated circuit (IC) package having first electrical contacts on an underside of the package and second electrical contacts on an upper side of the package, wherein the first contacts are disposed into the adhesive prior to a bonding, post-cure operation.
Example 3 includes the subject matter of any of examples 1-2, and wherein the second component is a photonic package having an attached optical coupler module that defines the overhanging portion, the photonic package having third electrical contacts connected to the second electrical contacts when the photonic package is mounted to the IC package, wherein the mounted together first and second packages constitute an optical interconnect module.
Example 4 includes the subject matter of any of examples 1-3, and wherein the second and third contacts are hybrid contacts.
Example 5 includes the subject matter of any of examples 1-4, and further comprising subjecting the carrier to a post-cure operation after disposing the one or more first components onto the surfaces of the soft cured adhesive portions to further secure them.
Example 6 includes the subject matter of any of examples 1-5, and wherein the post-cure operation comprises heating the carrier to a sufficient temperature for a sufficient time relative to the utilized TBDB photopolymer adhesive prior to mounting the second components onto the first components.
Example 7 includes the subject matter of any of examples 1-6, and further comprising de-bonding the mounted together assemblies formed from the first and second components, said de-bonding including at least one of thermal slide, wet chemical dissolution, mechanical peeling and laser ablation.
Example 8 includes the subject matter of any of examples 1-7, and wherein applying a TBDB photopolymer adhesive to a carrier includes applying the adhesive atop a release layer for assembly removal via laser ablation.
Example 9 includes the subject matter of any of examples 1-8, and wherein the TBDB photopolymer adhesive is formed from a silicone based adhesive having one or more photoinitiators.
Example 10 includes the subject matter of any of examples 1-9, and wherein the silicone based adhesive includes a platinum catalyst.
Example 11 includes the subject matter of any of examples 1-10, and wherein the photo-polymer adhesive uses a radical based photoinitiation system to create a soft-cured cross-linked network.
Example 12 includes the subject matter of any of examples 1-11, and wherein the radical based system employs a thiolene as a reactant.
Example 13 includes the subject matter of any of examples 1-12, and wherein the adhesive includes a coordination-based photo-catalyst to facilitate photo curing of functional silicones bearing vinyl and hydride units.
Example 14 is an apparatus that includes a carrier and a photo-polymeric adhesive surface. The carrier has a carrier surface. The patternable photopolymer adhesive layer is disposed atop the carrier surface according to a pattern. The adhesive layer includes a plurality of adhesive portions separated by a plurality of recess portions where adhesive has been removed.
Example 15 includes the subject matter of example 14, and wherein the carrier surface is a glass surface.
Example 16 includes the subject matter of any of examples 14-15, and wherein the carrier surface comprises a release layer of a temporary bond de-bond (TBDB) release material sandwiched between the carrier and the patternable photopolymer adhesive layer portions.
Example 17 includes the subject matter of any of examples 14-16, and wherein the release layer is releasable by being subjected to radiation that has a different wavelength from radiation used to cross-link the photopolymer adhesive.
Example 18 includes the subject matter of any of examples 14-17, and wherein at least some of the adhesive portions each accommodate a first optical interconnect assembly component that is to be mounted with a second optical assembly component having an overhang feature fitting within a recess portion that is next to the adhesive portion receiving the first optical assembly component.
Example 19 includes the subject matter of any of examples 14-18, and wherein the photopolymer adhesive includes a cross-linked polymeric network formed from a silicone based solution having a photoinitiator and a platinum based catalyst.
Example 20 includes the subject matter of any of examples 14-19, and wherein the adhesive portions are formed as strips separated by recess strips.
Example 21 includes the subject matter of any of examples 14-20, and wherein the adhesive portions are formed as rectangles separated by recess rectangles.
Example 22 includes the subject matter of any of examples 14-21, and wherein the adhesive portions are formed as rings separated by concentric recess rings.
Example 23 is a method to make an electrical assembly. The method includes applying a photopolymer adhesive to a carrier. It also includes exposing the TBDB photopolymer to a UV pattern an developing the adhesive to remove unexposed adhesive portions leaving adhesive regions having cross-linked polymeric networks and recess regions where adhesive was removed. A first component of the electrical assembly is disposed onto each of at least some of the adhesive regions, and the adhesive regions are post-cured to rigidly secure the first components. A separate second component of the electrical assembly is mounted onto each first component, wherein each second component has an over-hanging portion that is disposed within a proximal recess portion without contacting a surface portion when the second components are mounted to the first components.
Example 24 includes the subject matter of example 23, and wherein the overhang portion extends below the first component.
Example 25 includes the subject matter of any of examples 23-24, and wherein the overhang portion includes an optical coupler.
Example 26 includes the subject matter of any of examples 23-25, and wherein the electrical assembly is an optical interconnect assembly.
Example 27 includes the subject matter of any of examples 23-26, and wherein the first component is an electrical integrated circuit (IC).
Example 28 includes the subject matter of any of examples 23-27, and wherein the post-cure operation comprises heating the carrier to a sufficient temperature for a sufficient time relative to the utilized TBDB photopolymer adhesive prior to mounting the second components onto the first components.
Example 29 includes the subject matter of any of examples 23-28, and further comprising de-bonding the mounted together assemblies formed from the first and second components, said de-bonding including at least one of thermal slide, wet chemical dissolution, mechanical peeling and laser ablation.
Example 30 includes the subject matter of any of examples 23-29, and wherein applying the TBDB photopolymer adhesive to the carrier includes initially applying a release layer onto the carrier, the TBDB adhesive to be applied atop the release layer.
Example 31 includes the subject matter of any of examples 23-30, and wherein the TBDB photopolymer adhesive is formed from a silicone based adhesive having one or more photoinitiators.
Example 32 includes the subject matter of any of examples 23-31, and wherein the silicone based adhesive includes a platinum catalyst.
Example 33 includes the subject matter of any of examples 23-32, and wherein the photo-polymer adhesive uses a radical based photoinitiation system to create a soft-cured cross-linked network.
Example 34 includes the subject matter of any of examples 23-33, and wherein the radical based system employs a thiolene as a reactant.
Example 35 includes the subject matter of any of examples 23-34, and wherein the adhesive includes a coordination-based photo-catalyst to facilitate photo curing of functional silicones bearing vinyl and hydride units.
Reference in the specification to “an embodiment,” “one embodiment,” “some embodiments,” or “other embodiments” means that a particular feature, structure, or characteristic described in connection with the embodiments is included in at least some embodiments, but not necessarily all embodiments. The various appearances of “an embodiment,” “one embodiment,” or “some embodiments” are not necessarily all referring to the same embodiments. If the specification states a component, feature, structure, or characteristic “may,” “might,” or “could” be included, that particular component, feature, structure, or characteristic is not required to be included.
Throughout the specification, and in the claims, the term “connected” means a direct connection, such as electrical, mechanical, or magnetic connection between the things that are connected, without any intermediary devices.
The term “coupled” means a direct or indirect connection, such as a direct electrical, mechanical, or magnetic connection between the things that are connected or an indirect connection, through one or more passive or active intermediary devices.
The term “circuit” or “module” may refer to one or more passive and/or active components that are arranged to cooperate with one another to provide a desired function. It should be appreciated that different circuits or modules may consist of separate components, they may include both distinct and shared components, or they may consist of the same components. For example, A controller circuit may be a first circuit for performing a first function, and at the same time, it may be a second controller circuit for performing a second function, related or not related to the first function.
The meaning of “in” includes “in” and “on” unless expressly distinguished for a specific description.
The terms “substantially,” “close,” “approximately,” “near,” and “about,” unless otherwise indicated, generally refer to being within +/−10% of a target value.
Unless otherwise specified, the use of the ordinal adjectives “first,” “second,” and “third,” etc., to describe a common object, merely indicate that different instances of like objects are being referred to and are not intended to imply that the objects so described must be in a given sequence, either temporally, spatially, in ranking or in any other manner
For the purposes of the present disclosure, phrases “A and/or B” and “A or B” mean (A), (B), or (A and B). For the purposes of the present disclosure, the phrase “A, B, and/or C” means (A), (B), (C), (A and B), (A and C), (B and C), or (A, B and C).
It is pointed out that those elements of the figures having the same reference numbers (or names) as the elements of any other figure can operate or function in any manner similar to that described but are not limited to such.
As defined herein, the term “computer readable storage medium” means a storage medium that contains or stores program code for use by or in connection with an instruction execution system, apparatus, or device. As defined herein, a “computer readable storage medium” is not a transitory, propagating signal per se. A computer readable storage medium may be, but is not limited to, an electronic storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination of the foregoing. Memory elements, as described herein, are examples of a computer readable storage medium.
While the flow diagrams in the figures show a particular order of operations performed by certain embodiments of the invention, it should be understood that such order is exemplary (e.g., alternative embodiments may perform the operations in a different order, combine certain operations, overlap certain operations, etc.).