One-time use of multifunctional materials

Abstract

The disclosed materials and methods can be used in applications such as temporary bonding and debonding of semiconductor and display substrates. These materials have sufficiently low melt rheology to be used as adhesive layers and can be crosslinked / cured, allowing for reduced material flow over long periods of time. This class of materials also incorporates the ability to be used as a single-layer system for debonding purposes, typically using laser debonding as its release mechanism. These materials also allow for solvent cleanability using very mild acidic conditions instead of the typically harsh conditions used on curable layers.

Description

Technical Field

[0001] Background Related Applications This application claims the benefit of priority of U.S. Provisional Patent Application No. 63 / 015,897, filed on April 27, 2020, entitled MULTIFUNCTIONAL MATERIALS FOR TEMPORARY BONDING, the entire disclosure of which is incorporated herein by reference in its entirety.

[0002] Field The present disclosure relates to materials useful for temporary bonding.

[0003] Description of the Prior Art Temporary wafer bonding (「TWB」) generally refers to the process of attaching a device wafer or a microelectronic substrate to a carrier wafer or substrate by a polymeric adhesive material. After bonding, the device wafer is generally thinned to less than 50 μm, and then processing for creating through-silicon vias (「TSV」), redistribution layers, bonding pads, and other circuit configurations is performed on its back side. The carrier wafer supports the fragile device wafer during backside processing that necessarily involves strong mechanical forces such as those exerted during cycles repeated between ambient and high temperatures (>250 °C), mechanical shock due to wafer handling and transport processes, and wafer backgrinding used to thin the device wafer. When all of this processing is complete, the device wafer is typically attached to a film frame and subsequently separated or peeled from the carrier wafer and cleaned before further operations are performed.

[0004] Most TWB processes use one or two layers between the device wafer and the carrier wafer. In a two-layer system, the first layer is a polymerizable adhesive material. It can be thermoplastic, thermosetting, or essentially photocurable. The polymerizable adhesive layer is typically 10–120 μm thick, more commonly about 50–100 μm thick. The second layer is relatively thin, typically less than 2 μm, and exists to allow for easy separation of the bonded wafer pair after processing. The thin layer responds to radiation from a laser or other light source, which causes the layer itself or the adjacent polymerizable adhesive material to decompose, resulting in a loss of the integrity of the adhesion within the structure and allowing it to be separated without the application of mechanical force.

[0005] Currently, most temporary adhesive / release platforms on the market focus on multilayer structures, such as bilayer systems that include a temporary adhesive layer and a release layer. The multiple steps of coating and baking each layer result in increased ownership costs and reduced overall process capacity. In contrast, using a single material that functions as both the temporary adhesive layer and the laser release layer can achieve significant cost reductions and improved capacity.

[0006] Laser-guided demolition is becoming a common method of demolition, and materials that function at laser wavelengths ranging from ultraviolet (e.g., 248nm, 308nm, and 355nm) to near-infrared (e.g., 1064nm) are available. Laser demolition technology offers high processing capacity and low stress during the demolition process, effective handling of thin substrates, and ease of application, even for large panels. Laser demolition technology can be used in various applications in the packaging domain, such as temporary bonding, fan-out wafer-level packaging, lamination, 2.5D / 3D integration using through-silicon viables (TSVs), systems-in-packaging (SiP), package-on-package (PoP), and other heterogeneous integrated infrastructures. [Overview of the Initiative]

[0007] summary The present invention broadly relates to temporary bonding methods and structures formed by these methods. In one embodiment, the temporary bonding method includes preparing a stack comprising a first substrate, an adhesive layer, and a second substrate. The first substrate has a back surface and a front surface. The adhesive layer is adjacent to the front surface and contains polyazomethine. The second substrate has a first surface adjacent to the adhesive layer. The adhesive layer is exposed to laser energy to facilitate the separation of the first and second substrates.

[0008] In a further embodiment, the present invention provides a microelectronic structure comprising a first substrate having a back surface and a front surface. An adhesive layer adjacent to the front surface contains polyazomethine. A second substrate having the first surface is adjacent to the adhesive layer, and at least one of the front surface and the first surface is a device surface.

[0009] In another embodiment, polyazomethines comprising repeating monomers of dialdehydes, aromatic diamines, and aliphatic diamines are provided.

[0010] In yet another embodiment, a composition is provided comprising polyazomethine dispersed or dissolved in a solvent system. The polyazomethine comprises repeating monomers of dialdehydes, aromatic diamines, and aliphatic diamines. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 is a schematic cross-sectional view showing an exemplary temporary bonding process according to the present invention. [Figure 2] Figure 2 is a photograph of the wafer pair after bonding, as described in Example 2. [Figure 3] Figure 3 is a photograph of the silicon wafer after laser peeling, as described in Example 3. [Figure 4] Figure 4 is a photograph of the silicon wafer after laser peeling, as described in Example 4. [Figure 5] Figure 5 is a graph showing the n and k data for the material from Example 1. [Figure 6] Figure 6 is a graph showing the n and k data for the material from Example 6. [Figure 7] Figure 7 is a graph showing the n and k data for the materials from Example 8. [Figure 8] Figure 8 is a graph showing the n and k data for the materials from Example 10. [Figure 9] Figure 9 is a graph showing the n and k data for the materials from Example 12. [Figure 10] Figure 10 is a graph showing the n and k data for the materials from Example 14. [Figure 11] Figure 11 is a graph showing the n and k data for the materials from Example 16. [Figure 12] Figure 12 is a graph showing the n and k data for the materials from Example 18. [Modes for carrying out the invention]

[0012] Detailed explanation The present invention relates to novel compositions for use as temporary adhesive compositions, and to methods for using such compositions.

[0013] Temporary adhesive polymers and compositions 1. Polyazomethin The compositions for use in the present invention include polyazomethine, and preferably linear polyazomethine. The preferred polyazomethine may be a polymer, an oligomer, or both, and the polyazomethine comprises a first and a second monomer. The first monomer is selected from monomers containing an aldehyde and / or ketone group, while the second monomer comprises an amine monomer. The aldehyde and / or ketone monomer preferably contains two or more aldehyde and / or ketone groups, and the amine monomer preferably contains two or more amino groups. In a particularly preferred embodiment, the first monomer contains two or more aldehyde groups.

[0014] More specifically, the first monomer preferably comprises two or more aldehyde groups or ketone groups, or at least one aldehyde group and at least one ketone group. Aldehydes are particularly preferred, and dialdehydes are the most preferred first monomer. Preferred dialdehydes include terephthalaldehyde, 1,3-bis(4-formylphenoxy)-2-hydroxypropane["4EPIDA"], isophthalaldehyde, {4-[(p-formylbenzoyloxy)methyl]cyclohexyl}p-formylbenzoate methyl, 2-(p-formylbenzoyloxy)p-formylbenzoate ethyl, 2-[2-(p-formylbenzoyloxy)ethoxy]p-formylbenzoate ethyl, 2-{2-[2-( p-formylbenzoyloxy)ethoxy]ethoxy}p-formylbenzoate ethyl, 2-(2-{2-[2-(p-formylbenzoyloxy)ethoxy]ethoxy}ethoxy)p-formylbenzoate ethyl, 4-(p-formylbenzoyloxy)p-formylbenzoate cyclohexyl, 3-(p-formylbenzoyloxy)p-formylbenzoate cyclohexyl, {4-[(p-formylbenzoyloxy)methyl]tricyclo[5.2.1.0 2,6Methyl {deca-8-yl} p-formylbenzoate, p-{p-[p-(p-formylphenoxy)phenylsulfonyl]phenoxy}benzaldehyde, 4-{p-[p-(4-formyl-2-methoxyphenoxy)phenylsulfonyl]phenoxy}-3-anisaldehyde, (E)-5-(p-formylbenzoyloxy)-2-p-formylbenzoate pentenyl, 3-(allyloxy)-2-(p-formylbenzoyloxy)p-formylbenzoate propyl, 1,4-diacetylbenzene, (E)-5-(p-acetylbenzoyloxy)-2-p-acetylbenzoate pentenyl, 2-(p-acetylbenzoyloxy)-3-(allyloxy)p-acetylbenzoate propyl, 1-(4-{p-[p-(4-acetyl-2-methoxyphenoxy)phenylsulfonyl]phenoxy}-3-methoxyphenyl)-1-ethanone, 1-(p-{p-[p-(p-acetylphenoxy)phenylsulfonyl]phenoxy}phenyl)-1-ethanone, 3-(p-acetylbenzoyloxy)p-acetylbenzoate cyclohexyl, {4-[(p-acetylbenzoyloxy)methyl]tricyclo[5.2.1.0 2,6 Methyl {deca-8-yl} p-acetylbenzoate, ethyl 2-(2-{2-[2-(p-acetylbenzoyloxy)ethoxy]ethoxy}ethoxy)p-acetylbenzoate, ethyl 2-{2-[2-(p-acetylbenzoyloxy)ethoxy]ethoxy}p-acetylbenzoate, ethyl 2-[2-(p-acetylbenzoyloxy)ethoxy]p-acetylbenzoate, ethyl 2-(p-acetylbenzoyloxy)p-acetylbenzoate, methyl {4-[(p-acetylbenzoyloxy)methyl]cyclohexyl}p-acetylbenzoate, and combinations thereof. The first monomer is preferably present in the polymer at about 30 mol% to about 70 mol%, more preferably about 40 mol% to about 60 mol%, based on the polymer as 100 mol%.

[0015] The second monomer is selected from aliphatic amines, aromatic amines, and combinations thereof. In a preferred embodiment, the second monomer is a combination of at least one aliphatic amine monomer (more preferably an aliphatic diamine monomer) and at least one aromatic amine (more preferably an aromatic diamine monomer), which effectively means that the polyazomethine contains a third monomer (i.e., an aldehyde monomer, an aliphatic amine monomer, and an aromatic amine monomer, but most preferably a dialdehyde monomer, an aliphatic diamine monomer, and an aromatic diamine monomer).

[0016] Preferred aliphatic amines impart flexibility to the polymer chain to improve material processing, while preferred aromatic amines impart photosensitivity to the polymer. The ratio and type of aromatic and aliphatic amines are selected to optimize the absorbance, rheology, and solubility of the polymer.

[0017] Preferred aliphatic amines include those selected from 1,3-bis(aminopropyl)tetramethyldisiloxane, aminopropyl-terminated polydimethylsiloxane, 4,4'-methylenebis(2-methylcyclohexylamine), 2-methyl-1,5-diaminopentane, isophoronediamine, 1,12-diaminododecane, 1,7-diaminoheptane, 1,10-diaminodecane, 1,4-butanediol bis(3-aminopropyl)ether, 1,2-bis(2-aminoethoxy)ethane, diethylene glycol bis(3-aminopropyl)ether, 1,6-diaminohexane, 2,2-dimethyl-1,3-propanediamine, bis(aminomethyl)norbornane, 4,4'-methylenebis(cyclohexylamine), 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, 1,3-cyclohexanediamine, 1,4-cyclohexanediamine, and combinations thereof.

[0018] Preferred aromatic amines include 9,9-bis(4-aminophenyl)fluorene, 4,4'-methylenebis(2,6-diethylaniline), 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 4,4'-(1,3-phenylenediisopropylidene)bisaniline, 4-aminophenylsulfone, bis[4-(3-aminophenoxy)phenyl]sulfone, o-dianisidine, 1,5-diaminonaphthalene, m-xylylenediamine, p-xylylenediamine, 4,4'-diaminodiphenyl ether, and bis(3-aminophenyl). Sulfone, 1,3-phenylenediamine, 4,4'-diaminodiphenylmethane, 4,4'-methylenebis(2-chloroaniline), α,α'-bis(4-aminophenyl)-1,4-diisopropylbenzene, 1,4-phenylenediamine, 2,2-bis(4-aminophenyl)hexafluoropropane, 2,2'-bis(trifluoromethyl)benzidine, 2,7-diaminofluorene, 3,4'-diaminodiphenylmethane, 3,3',5,5'-tetramethylbenzidine, 9,9-bis(4-amino-3-methylphenyl)fluorene, bis (3-amino-4-hydroxyphenyl)sulfone, 3-aminobenzylamine, 1,4-bis(4-aminophenoxy)benzene, 1,3-bis(3-aminophenoxy)benzene, 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane, 4,4'-bis(4-aminophenoxy)biphenyl, 1,1-bis(4-aminophenyl)cyclohexane, 3,4'-diaminodiphenyl ether, 4,4'-ethylenedianiline, 2,3,5 ,6-tetramethyl-1,4-phenylenediamine, 2,2-bis(3-amino-4-hydroxyphenyl)propane, 1,4-bis(4-amino-2-trifluoromethylphenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, bis[4-(4-aminophenoxy)phenyl]sulfone, 4,4'-methylenebis(2-ethyl-6-methylaniline), m-tolidine, bis(4-aminophenyl)sulfide, o-tolidine, 4,4'-diamino-3,3'-dimethyldiphenylmethane, 4,4'-diaminobenzophenone, 3,Examples include 3'-diaminobenzophenone, 3,3'-diaminodiphenylmethane, 9,9-bis(4-amino-3-fluorophenyl)fluorene, 9,9-bis(4-amino-3-chlorophenyl)fluorene, 4,4'-diamino-2,2'-dimethylbibenzyl, and combinations thereof.

[0019] The second monomer (i.e., aromatic amine, aliphatic amine, or both) is preferably present in the polymer at a concentration of about 30 mol% to about 70 mol%, more preferably about 40 mol% to about 60 mol%, relative to 100 mol% of the polymer. When a combination of aromatic amine and aliphatic amine is used, the aliphatic amine is preferably present at a concentration of about 1 mol% to about 70 mol%, more preferably about 5 mol% to about 55 mol%, relative to 100 mol% of the polymer, and the aromatic amine is preferably present in the polymer at a concentration of about 1 mol% to about 70 mol%, more preferably about 5 mol% to about 55 mol%. When both aromatic amine monomers and aliphatic amine monomers are used, the molar ratio of aromatic amine to aliphatic amine is preferably about 1:4 to about 4:1, more preferably about 1:2 to about 2:1.

[0020] The molar ratio of total amine monomers to total dialdehyde monomers is preferably about 1:4 to about 4:1, more preferably about 1:2 to about 2:1, and even more preferably about 1:1.

[0021] Generally, reactions that form polyazomethines involve random reactions between amine monomers and aldehyde and / or ketone monomers, forming azomethine bonds and repeating polyazomethine structures. An example of one such reaction and a snapshot of the resulting polymer or oligomer is shown below.

[0022] [ka]

[0023] Polymer formation preferably occurs via Schiff base reactions of the amine and dialdehyde moieties present on each monomer. The reaction can be carried out in an organic solvent or mixture of organic solvents in the presence of any catalyst, at or near room temperature, or at high temperatures. The preferred reaction temperature is about 25°C to about 200°C, more preferably about 25°C to about 150°C. The preferred reaction time is about 1 hour to about 24 hours, more preferably about 4 hours to about 16 hours. It is not necessary to remove water from the reaction mixture to allow the reaction to complete, but it can be removed to increase efficiency. Additional solvents can be added to the reaction mixture after polymerization to maintain a manageable viscosity of the solution.

[0024] While monomers can be reacted in a single reaction, if two or more types of amine monomers are used, it is preferable to carry out the reaction in two steps. That is, the dialdehyde can be reacted with one of the amine monomers until the reaction is complete. In this reaction, since the dialdehyde is in excess, the reaction proceeds until the first amine monomer is used up, yielding an oligomer or a short (shorter) polymer chain of dialdehyde and the first amine monomer. After the first reaction, the second amine monomer is added to the reaction mixture and reacted to yield a polymer chain with heterogeneous repeating units. This preferred polymer structure further optimizes polymer rheological properties, absorbance properties, and solubility properties. A schematic diagram of the two-step reaction product is shown in Scheme A.

[0025] Scheme A [ka]

[0026] "X" and "Y" can be any number, determined by the amount and ratio of the selected starting monomers, and the preferred total weight percentage and total molar ratio in the polymer are described above. Furthermore, the bonds in the above scheme represent azomethine bonds.

[0027] Step (II) of Scheme A will be understood to form a random copolymer or oligomer. That is, the aldehyde to which the secondary amine reacts is uncontrolled. It can react with a free aldehyde monomer present in the reaction solution, an aldehyde previously reacted with the primary amine (i.e., step (I) of Scheme A), or both. Scheme B shows a general structure illustrating this modification.

[0028] Scheme B [ka]

[0029] Z can be any number, and is determined by the amount and ratio of the selected starting monomers, as well as the preferred overall weight percentage and overall molar ratio in the polymer, as described above. Furthermore, in scheme B, the first amine of the "Z" repeat can react with an available aldehyde-secondary amine structure, resulting in the addition of another "Y" repeat unit to the other end of the "Z" repeat unit.

[0030] Another example of a structure that can be formed according to any of the above reactions has the following structure.

[0031] [ka]

[0032] Again, "X" and "Y" can be any number, determined by the amount and ratio of the selected starting monomers, and preferred weight percentages and molar ratios are described above.

[0033] In some embodiments, one or more end-capping monomers can be used to further control the polymerization reaction and molecular weight of the polymer. In one such embodiment, a monomer having a single functional group, such as a monofunctional aromatic or aliphatic aldehyde monomer, or a monofunctional anhydride monomer, can be added to the reaction mixture to terminate the polymer chain. Examples of aldehyde monomers suitable for use as end-capping monomers include benzaldehyde, trans-2-pentenal, trans-2-octenal, trans-2-decenal, trans-2-heptenal, baleraldehyde, 5-methyl-2-phenyl-2-hexenal, and combinations thereof. Examples of anhydride monomers suitable for use as end-capping monomers include maleic anhydride, phthalic anhydride, succinic anhydride, 1,8-naphthalic anhydride, phenylacetylene-modified trimellitic anhydride (e.g., sold by Nexam Chemical under the name NEXIMID® 300), and combinations thereof. It will be understood that any of these or other suitable end-capping monomers can be added to the above structure to terminate the polymer or oligomer represented by the above structure.

[0034] Suitable polymerization solvents include those selected from gamma-butyrolactone ("GBL"), dimethyl sulfoxide ("DMSO"), n-methyl-2-pyrrolidone ("NMP"), dimethylacetamide ("DMAC"), propylene glycol methyl ether acetate ("PGMEA"), benzyl alcohol, propylene glycol methyl ether ("PGME"), anisole, acetylene, d-limonene, toluene, and mixtures thereof. Preferred solvents are immiscible with water. Ketone solvents are preferably avoided because they can cause chain degradation due to potential reactions with polymer chains. The solvent is present in the reaction solution at a concentration of preferably about 25 wt% to about 95 wt%, more preferably about 40 wt% to about 80 wt%, based on the total weight of solids in the reaction solution at 100 wt%.

[0035] Optionally, an acid catalyst may be used to accelerate the reaction. Suitable acid catalysts include butyric acid, acetic acid, sulfonic acid (such as p-toluenesulfonic acid ["pTSA"]), and sulfuric acid. The catalyst is present in the polymerization mixture at a level of preferably about 1 mol% to about 5 mol%, more preferably about 3 mol%, relative to the total amine monomers, which are 100 mol%.

[0036] After preparation, further polymer isolation is not required, and the product can be left in solution and used as is. Optionally, the polymer can be precipitated and / or purified and incorporated into the final formulation. In any case, the preferred polymer weight-average molecular weight is about 1,000 to about 200,000 daltons, more preferably about 5,000 to about 30,000 daltons. The final material exhibits high absorbance at wavelengths of about 200 nm to about 400 nm, preferably about 300 nm to about 380 nm.

[0037] 2. Polyazomethine composition The adhesive compositions used in the present invention are formed by simply dissolving polyazomethine in a solvent system. The compositions of the present invention are formed by mixing a polymer and any components with a solvent system. The resulting compositions are stable at room temperature and can be easily coated onto microelectronic substrates.

[0038] Suitable solvent systems include, but are not limited to, anisole, PGME, PGMEA, d-limonene, mesitylene, isoamyl acetate, propylene glycol-derived glycerides (such as those sold by BASF under the name PROGLYME), benzyl alcohol, dipropylene glycol dimethyl ether, NMP, dimethyl sulfoxide, and mixtures thereof. The solvent system is present in the material at approximately 20 wt% to 99 wt%, preferably about 40 wt% to 90 wt%, based on the total weight of the composition as 100% by weight. It will be understood that the amount or type of solvent added to the material may vary depending on the vapor deposition method used.

[0039] The polymer is present in the material at an amount of about 1 wt% to about 80 wt%, preferably about 10 wt% to about 60 wt%, relative to the total weight of the composition when considered as 100 wt%.

[0040] Optionally, other additives, including surfactants, catalysts, and mixtures thereof, may be added to the composition. These additives are selected according to the desired properties and intended use of the final composition, and must be soluble in the solvent system and compatible with the polymer in solution.

[0041] Suitable surfactants include nonionic fluorinated surfactants (R-30-N, FS-21, F-81, F556, FS3100, FS-4430, FS-4432, and FS-4434), nonionic nonfluorinated surfactants (such as those sold under trade names EFAK®, LANCO™, ECOSURF™, Saponin, TERGITOL™, Triton™, and MERPOL®), and ionic nonfluorinated surfactants (poly(ethylene glycol) 4-nonylphenyl 3-sulfopropyl ether potassium salt and sodium dodecylbenzenesulfonate), as well as mixtures thereof. If surfactants are present, they are present at a level of about 0.01 wt% to about 2 wt%, preferably about 0.05 wt% to about 0.5 wt%, and more preferably about 0.2 wt%, based on the total weight of the composition as 100 wt%.

[0042] Suitable catalysts include dicumyl peroxides, azobisisobutyronitriles, thermoacid generators, and mixtures thereof. Preferred thermoacid generators include block acids such as quaternary ammonium block trifluic acid, one example being the one sold by King Industries, Inc. under the name K-PURE® TAG-2689. If a catalyst is present, it is present at a level of about 0.01% to about 3% by weight, preferably about 0.05% to about 3% by weight, and more preferably about 0.5% by weight, based on 100% by weight of the total weight of the composition.

[0043] The Brookfield viscosity of the composition, when measured at 25°C, is preferably about 10 cP to about 2500 cP, more preferably about 100 cP to about 1200 cP.

[0044] In one embodiment, the composition consists essentially of, or is composed of, a polyazomethine and a solvent system.

[0045] In another embodiment, the composition essentially consists of, or comprises, one or both of, a polyazomethine, a solvent system, and a surfactant and / or a catalyst.

[0046] Method of using a temporary adhesive composition Advantageously, the polyazomethine adhesive composition described above can be used in a primary bonding process to bond a device substrate to a carrier substrate, functioning as both an adhesive layer and a laser release material. More specifically, and referring to Figure 1(a) (non-scale), a precursor structure 10 is depicted in a schematic cross-sectional view. Structure 10 includes a first substrate 12. The substrate 12 has a front or device surface 14, a back surface 16, and an outermost edge 18. The substrate 12 can be any shape, but is typically circular. A preferred first substrate 12 is a device wafer in which the device surface includes an array of devices (not shown) selected from the group consisting of integrated circuits, MEMS, microsensors, power semiconductors, light-emitting diodes, photonic circuits, interposers, embedded passive devices, and other microdevices fabricated on or from silicon, silicon-germanium, gallium arsenide, gallium nitride, aluminum gallium arsenide, aluminum indium gallium phosphide, and other semiconductor materials such as indium gallium phosphide. The surfaces of these devices generally include structures (also not shown) formed from one or more of the following materials: silicon, polysilicon, silicon dioxide, silicon (oxy)nitride, metals (e.g., copper, aluminum, gold, tungsten, tantalum), low-k dielectrics, polymer dielectrics, and various metal nitrides and metal silicides. The device surface 14 may also include solder bumps, metal posts, metal pillars, and at least one structure selected from the group consisting of silicon, polysilicon, silicon dioxide, silicon (oxy)nitride, metals, low-k dielectrics, polymer dielectrics, metal nitrides, and metal silicides.

[0047] As shown in Figure 1(a), the laser-release adhesive composition according to the present invention is applied to a first substrate 12 to form a laser-release adhesive layer 20 on the device surface 14. The adhesive layer 20 has an upper surface 21 far away from the first substrate 12, and preferably the adhesive layer 20 is formed directly on the device surface 14 (i.e., there is no intermediate layer between the adhesive layer 20 and the substrate 12). The adhesive composition can be applied by any known application method. One preferred method is to spin-coat the composition at a speed of about 100 rpm to about 3,000 rpm (preferably about 400 rpm to about 1,500 rpm) for about 10 seconds to about 180 seconds (preferably about 30 seconds to about 90 seconds).

[0048] After applying the composition, it is preferable to heat it to a temperature of about 50°C to about 300°C, more preferably about 100°C to about 200°C, for about 30 seconds to about 20 minutes (preferably about 60 seconds to about 6 minutes). In one embodiment, little or no crosslinking occurs during this heating. In other words, the resulting adhesive layer 20 is preferably thermoplastic.

[0049] In some embodiments, depending on the composition used, it is preferable to subject the adhesive layer 20 to a multi-step baking process. Also, in some examples, the coating and baking processes can be repeated with a further fixed amount of the composition, so that the adhesive layer 20 is "built" on the first substrate 12 in multiple steps.

[0050] In a further embodiment, the laser-release adhesive composition according to the present invention may be formed on a pre-formed dry film rather than being applied as a fluid composition. In this case, the composition is formed on an unsupported, self-supporting film that does not collapse or change shape despite being unsupported (without the application of force or energy). This film can then be attached to a first substrate 12 to form the laser-release adhesive composition 20 shown in Figure 1(a).

[0051] Regardless of how the adhesive layer 20 is formed, it should have an average thickness (measured at 5 locations) of approximately 1 μm to approximately 200 μm, more preferably approximately 5 μm to approximately 100 μm, and even more preferably approximately 10 μm to approximately 30 μm. The thickness used herein can be measured using any film thickness measuring tool, one preferred tool being an infrared interferometer, such as those sold by SUSS Microtec or Foothill.

[0052] The adhesive layer 20 should also have a low total thickness variation ("TTV"), meaning that the thickest and thinnest points of layer 20 do not differ significantly from each other. TTV is preferably calculated by measuring the thickness at several points or locations on the film, preferably at least about 50 points, more preferably at least about 100 points, and even more preferably at least 1,000 points. The difference between the highest and lowest thickness measurements obtained at these points is designated as the TTV measurement for that particular layer. In some TTV measurement examples, edge exclusion or outliers may be removed from the calculation. In such cases, the number of included measurements is indicated by a percentage; i.e., if TTV is given with 97% inclusion, 3% of the highest and lowest measurements are excluded, and the remaining 3% are equally divided between the highest and lowest (i.e., 1.5% each). Preferably, the above TTV range is achieved using about 95% to about 100% of the measured value, more preferably about 97% to about 100% of the measured value, and even more preferably about 100% of the measured value.

[0053] In addition to a low TTV in absolute terms (e.g., 5 μm), the TTV relative to the average thickness of the adhesive layer 20 should also be low. Therefore, the adhesive layer 20 should have a TTV on a blank substrate that is less than about 25% of the average thickness of the adhesive layer 20, preferably less than about 10% of the average thickness, and more preferably less than about 5% of the average thickness. For example, if the adhesive layer 20 has an average thickness of 50 μm, the maximum allowable TTV would be about 12.5 μm or less (less than about 25% of 50 μm), preferably about 5 μm or less (less than about 10% of 50 μm), and more preferably about 2.5 μm or less (less than about 5% of 50 μm).

[0054] Furthermore, the laser-release adhesive layer 20 will form a strong adhesive bond with the desired substrate. Any adhesive strength measured by ASTM D4541 / D7234 greater than about 50 psig, preferably about 80 psig to about 250 psig, and more preferably about 100 psig to about 150 psig, would be desirable for use as the adhesive layer 20.

[0055] The adhesive layer 20 will have a k value of at least about 0.05, preferably at least about 0.1, and more preferably about 0.12 to about 0.6 at wavelengths of about 300 nm to about 380 nm.

[0056] The adhesive layer 20 has a complex viscosity of preferably less than 3,000 Pa·s at 160°C, more preferably about 50 Pa·s to about 1,500 Pa·s at 160°C, and even more preferably about 100 to about 1,000 Pa·s at 160°C. The complex viscosity is preferably measured with a rheometer such as the AR-2000ex rheometer sold by TA Instruments.

[0057] In one embodiment, the adhesive composition, and by extension the resulting adhesive layer 20, is preferably non-photosensitive (i.e., about 1 J / cm²). 2(When exposed, it is not possible to define a pattern within the layer.) Therefore, the composition used to form the adhesive layer 20 and the resulting adhesive layer 20 are substantially free of photoacid generators (PAGs). "Substantially free" means that the composition and / or layer contain less than about 0.1 wt%, preferably less than about 0.05 wt%, and preferably about 0 wt%, of the total weight of the composition as 100 wt% PAG. It also substantially contains no other agents that can initiate polymerization or crosslinking upon exposure.

[0058] The second precursor structure 22 is also depicted in a schematic cross-sectional view in Figure 1(a). The second precursor structure 22 includes a second substrate 24. In this embodiment, the second substrate 24 is a carrier wafer. The second substrate 24 has a front or carrier surface 26, a back surface 28, and an outermost edge 30. The second substrate 24 can be any shape, but is usually circular and similar in size to the first substrate 12. Preferred second substrates 24 include transparent glass wafers or other transparent substrates (to the laser energy) that allow the laser energy to pass through the carrier substrate. Particularly preferred glass carrier wafers include Corning® EAGLE XG® glass, Gorilla® glass, and soda-lime glass.

[0059] Next, structures 10 and 22 are pressed together in a face-to-face relationship so that the upper surface 21 of the adhesive layer 20 comes into contact with the front surface or carrier surface 26 of the second substrate 24 (Figure 1(b)). During pressing, sufficient pressure and heat are applied for a sufficient amount of time to bring the two structures 10 and 22 together and cause adhesion, forming a bonded stack 34. The bonding parameters vary depending on the composition forming the adhesive layer 20, but the typical temperature during this process is in the range of about 60°C to about 300°C, preferably about 80°C to about 220°C, and the typical pressure is about 500N to about 10,000N, preferably about 750N to about 2,000N for about 30 seconds to about 10 minutes, preferably about 2 minutes to about 5 minutes.

[0060] Next, the bonded stack 34 is heated on a hot plate or in an oven environment to cure the adhesive layer 20. The heating is preferably carried out at a temperature of about 30 seconds to about 20 minutes, preferably about 1 minute to about 10 minutes, preferably about 120°C to about 300°C, more preferably about 120°C to about 180°C. In one embodiment, the "two-step curing process" is carried out by heating in two separate steps. In the first bake step, the heating is preferably carried out at a temperature of about 120°C to about 225°C, preferably about 150°C to about 200°C, for a time of about 30 seconds to about 20 minutes, more preferably about 2 minutes to about 20 minutes. In the second bake step, the heating is preferably carried out at a temperature of about 200°C to about 300°C, preferably about 225°C to about 275°C, for a time of about 30 seconds to about 20 minutes, more preferably about 2 minutes to about 20 minutes. In one embodiment, the adhesive layer 20 is a thermosetting layer because crosslinking occurs during this heating process.

[0061] The bonded stack 34 should have a TTV of less than approximately 10% of the total average thickness of the bonded stack 34, preferably less than approximately 5% of the total average thickness (measured at 5 locations across the stack 34), and more preferably less than approximately 3% of the total average thickness. That is, if the bonded stack 34 has an average thickness of 100 μm, a TTV of less than approximately 10% would be approximately 10 μm or less.

[0062] The first substrate 12 can now be handled safely and subjected to subsequent processing that might damage the first substrate 12 if it were not bonded to the second substrate 24. Thus, the structure can be safely subjected to back-side treatments such as back-side grinding, chemical mechanical polishing ("CMP"), etching, metal deposition (i.e., metallization), dielectric deposition, patterning (e.g., photolithography via etching), passivation, annealing, redistribution layer formation, and combinations thereof, without causing separation of substrates 12 and 24 and without any chemicals generated during these subsequent processing steps entering the substrate. The adhesive layer 20 can not only withstand these treatments but also withstand processing temperatures of about 325°C or less, preferably about 25°C to about 300°C, and more preferably about 80°C to about 280°C.

[0063] Once processing is complete, the substrates 12 and 24 can be separated by using a laser to decompose or ablate all or part of the laser-release adhesive layer 20. Suitable lasers include UV lasers with wavelengths of approximately 300 nm to 360 nm, more preferably 308 nm and / or 355 nm. To peel off the laser-release adhesive layer, the laser is scanned across the carrier wafer surface in a snake-like pattern to expose the entire wafer. Exemplary laser peeling tools include the SUSS Microtec Lambda STEEL 2000 laser peeler, the EVG® 850 DB automated peeling system, and the Kingyoup LD-Automatic 200 / 300 laser peeler. The wafer is preferably scanned by a laser spot with a field size of approximately 40 × 40 μm to 12.5 × 4 mm. A suitable fluence for substrate peeling is approximately 100 mJ / cm². 2 ~Approx. 1,300mJ / cm 2 Preferably about 150 mJ / cm² 2 ~about 800mJ / cm 2 The appropriate output for stripping the substrate is approximately 2W to 6W, preferably approximately 3W to 4W.

[0064] After laser exposure, the substrates 12 and 24 will easily separate. After separation, any remaining adhesive layer 20 can be removed by plasma etching or with a solvent capable of dissolving the adhesive layer 20. A preferred cleaning method involves the use of a weakly acidic solution. In this case, the peeled substrates 12 and / or 24 are immersed or spin-cleaned in the solution for about 30 seconds to about 20 minutes, preferably about 1 minute to 10 minutes. This cleaning solution preferably contains, is essentially, or consists of ketone solvents such as cyclopentanone, cyclohexanone, acetophenone, and mixtures thereof, but other water-miscible solvents are also acceptable. The solvent is preferably present in the cleaning solution at about 1 wt% to about 99 wt%, preferably about 70 wt% to about 95 wt%, based on the total weight of the cleaning solution as 100 wt%. When used, water is preferably present in the cleaning solution at a concentration of about 0.1 wt% to about 99 wt%, preferably about 1 wt% to about 20 wt%, relative to the total weight of the cleaning solution at 100 wt%. The cleaning solution also contains one or more acids, preferably weaker acids such as acetic acid, butyric acid, citric acid, phosphoric acid, benzoic acid, and mixtures thereof. The acid is preferably present in the cleaning solution at a concentration of about 0.1 wt% to about 30 wt%, preferably about 1 wt% to about 15 wt%, relative to the total weight of the cleaning solution at 100 wt%. It will be understood that stronger acids may be used at lower percentages, provided that the cleaning solution does not damage the mechanisms on the device wafer.

[0065] In the above embodiment, the laser-release adhesive layer 20 is shown on a first substrate 12, which is a device wafer. It will be understood that this substrate / layer arrangement can be reversed; that is, the adhesive layer 20 may be formed on a second substrate 24 (i.e., a carrier wafer). The same compositions and processing conditions as described above will apply to this embodiment.

[0066] In a particularly preferred embodiment, as shown in Figure 1, the adhesive layer 20 is the only layer between the substrates 12 and 24. However, in alternative embodiments, it will be understood that the adhesive layer 20 can be used in conjunction with additional adhesive materials, structural support layers, lamination support layers, linking layers (for initial adhesion to the substrate), contamination control layers, and cleaning layers. The preferred structure and coating method will inevitably be determined by the coating and process flow.

[0067] The additional advantages of various embodiments will be apparent to those skilled in the art upon consideration of the disclosures herein and the following examples. It will be understood that the various embodiments described herein are not necessarily mutually exclusive unless otherwise indicated herein. For example, features described or depicted in one embodiment may, but may not, be included in other embodiments. Thus, this disclosure encompasses various combinations and / or integrations of the specific embodiments described herein.

[0068] As used herein, the expression "and / or" means that when used to enumerate two or more items, any of the enumerated items may be used individually, or any combination of two or more of the enumerated items may be used. For example, if a composition is described as containing or excluding components A, B and / or C, the composition may contain or excluding A only, B only, C only, a combination of A and B, a combination of A and C, a combination of B and C, or a combination of A, B and C.

[0069] This description also uses numerical ranges to quantify certain parameters relating to various embodiments. It should be understood that, given a numerical range, such a range should be interpreted as providing precise support for claims that specify only the lower value within the range, and similarly, for claims that specify only the higher value within the range. For example, the disclosed numerical range of approximately 10 to approximately 100 provides precise support for claims that specify "greater than approximately 10" (no upper limit) and claims that specify "less than approximately 100" (no lower limit).

[0070] Examples The following embodiments illustrate methods in accordance with this disclosure. However, it should be understood that these embodiments are presented as examples and none should be considered as limiting the entire scope.

[0071] Example 1 Preparation of polyazomethin solution 1 In this example, 41.19 grams (10.91%) of terephthalaldehyde (TCI, Portland, Oregon), 0.85 grams (0.22%) of butyric acid (Sigma-Aldrich, St. Louis, Missouri), and 108.05 grams (36.32%) of PGMEA (Fujifilm, Suzhou, China) were added to a reaction vessel having a Dean-Stark trap and a condenser attached to the Dean-Stark trap. The trap was filled with PGMEA to create a separation between the water produced during the reaction and the PGMEA. Nitrogen was pumped into the reaction vessel to create an inert atmosphere. The reactants were heated to 120°C. After all the terephthalaldehyde had dissolved, 27.87 grams (7.38%) of 9,9-bis(4-aminophenyl)fluorene (JFE Chemical Corporation, Tokyo, Japan) was added, and the reaction was allowed to continue for 20-60 minutes until water production slowed down and stopped. Next, 62.78 grams (16.63%) of 1,3-bis(aminopropyl)tetramethyldisiloxane (Alfa Aesar, Ward Hill, Massachusetts) was added together with 136.84 grams (28.54%) of PGMEA through an addition funnel. The solution was heated to 150°C (the reflux temperature of PGMEA) and reacted for 6-8 hours. A medium-viscosity, orange-to-pink solution was obtained.

[0072] Example 2 Adhesion test The material from Example 1 was spin-coated onto an 8-inch glass wafer at a spin speed of 850 rpm for 45 seconds with a ramp of 500 rpm / s, and then baked on a hot plate at 120°C for 3 minutes, followed by 180°C for 5 minutes, to obtain a 20 μm film. The coated and baked wafer was then bonded to an 8-inch silicon wafer. The substrate was then bonded using an EVG 510 bonder with an adhesive force of 2200 N, an adhesive temperature of 145°C, and an adhesive time of 3 minutes. The bonded pair showed good adhesion quality with no voids after bonding. A photograph of the bonded pair is shown in Figure 2.

[0073] Example 3 Laser peeling test at 308nm As shown in Example 2, wafers were bonded together. Next, the bonded pair was separated using a 308nm laser delamination machine from SUSS Microtec in Corona, California. The wafers were subjected to a laser load of 275 mJ / cm². 2 The fluence required for delamination was minimal, and this was the minimum delamination force needed to separate the wafer pair. Figure 3 shows a photograph of the silicon wafer after delamination at 308 nm.

[0074] Example 4 Laser peeling test at 355nm The wafers were bonded as in Example 2 and then laser-exfoliated using a 355nm laser from Kingyoup in Taipei, Taiwan. Table 1 shows the exfoliation parameters. Figure 4 shows a photograph of the silicon wafer after exfoliation at 355nm.

[0075] Table 1: Kingyoup's 355nm laser peeling data [Table 1]

[0076] Example 5 Example 1: Measurement of n and k values ​​of the material The material from Example 1 was spin-coated onto a 4-inch silicon wafer at a spin speed of 1,500 rpm for 60 seconds with a ramp of 1,500 rpm / s, and then baked on a hot plate at 120°C for 3 minutes, followed by 180°C for 5 minutes, to obtain a 200 nm film. The optical parameters were then measured using a VASE M2000. The full n and k spectra at the target wavelength are shown in Figure 5.

[0077] Example 6 Preparation of polyazomethin solution 2 In this example, 20.12 grams (11.66%) of terephthalaldehyde, 70.59 grams (40.92%) of PGMEA, and 17.90 grams (10.37%) of 1,3-bis(aminopropyl)tetramethyldisiloxane (Alfa Aesar, Ward Hill, Massachusetts) were added to a reaction vessel having a Dean-Stark trap and a condenser attached to the Dean-Stark trap. The trap was filled with PGMEA to form a separation between the water produced during the reaction and the PGMEA. Nitrogen was pumped into the reaction vessel to create an inert atmosphere. The solution was reacted at 25°C for 15–20 minutes, and then the reactants were heated to 120°C and reacted for 1–2 hours, or until the production of water slowed down and stopped. After all the water had been removed, 22.36 grams (12.96%) of 4,4'-methylenebis(2,6-diethylaniline) (TCI, Portland, Oregon) and 41.53 grams (24.06%) of PGMEA were added to the solution. The solution was allowed to react at 120°C for 6–8 hours. The resulting solution was dark yellow-amber in color and had a moderate viscosity.

[0078] Example 7 Example 6: Measurement of n and k of materials The material from Example 6 was spin-coated onto a 4-inch silicon wafer at a spin speed of 1,500 rpm for 60 seconds with a ramp of 1,500 rpm / s, and then baked on a hot plate at 120°C for 3 minutes, followed by 180°C for 5 minutes, to obtain a 200 nm film. The optical parameters were then measured using a VASE M2000. The full n and k spectra at the target wavelength are shown in Figure 6.

[0079] Example 8 Preparation of polyazomethin solution 3 In this example, 16.91 grams (9.85%) of terephthalaldehyde, 74.98 grams (43.68%) of PGMEA, and 23.49 grams (13.69%) of 1,3-bis(aminopropyl)tetramethyldisiloxane (Alfa Aesar, Ward Hill, Massachusetts) were added to a reaction vessel having a Dean-Stark trap and a condenser attached to the Dean-Stark trap. The trap was filled with PGMEA to form a separation between the water produced during the reaction and the PGMEA. Nitrogen was pumped into the reaction vessel to create an inert atmosphere. The solution was reacted at 25°C for 15–20 minutes, and then the reactants were heated to 120°C and reacted for 1–2 hours, or until the production of water slowed down and stopped. After all the water had been removed, 19.68 grams (11.47%) of bis[4-(3-aminophenoxy)phenyl]sulfone (Alfa Aesar, Ward Hill, Massachusetts) and 36.57 grams (21.31%) of PGMEA were added to the solution. The solution was allowed to react at 120°C for 6–8 hours. The resulting solution was brown-amber in color and had a moderate viscosity.

[0080] Example 9 Example 8: Measurement of n and k of materials The material from Example 8 was spin-coated onto a 4-inch silicon wafer at a spin speed of 1,500 rpm for 60 seconds with a ramp of 1,500 rpm / s, and then baked on a hot plate at 120°C for 3 minutes, followed by 180°C for 5 minutes, to obtain a 200 nm film. The optical parameters were then measured using a VASE M2000. The full n and k spectra at the target wavelength are shown in Figure 7.

[0081] Example 10 Preparation of polyazomethin solution 4 In this example, 17.66 grams (6.51%) of terephthalaldehyde, 75.844 grams (27.92%) of anisole (Sigma-Aldrich, St. Louis, Missouri), and 23.49 grams (13.69%) of diethylene glycol bis(3-aminopropyl) ether (TCI, Portland, Oregon) were added to a reaction vessel having a Dean-Stark trap and a condenser attached to the Dean-Stark trap. The trap was filled with anisole to form a separation between the water produced during the reaction and the anisole. Nitrogen was pumped into the reaction vessel to create an inert atmosphere. The solution was reacted at 25°C for 15–20 minutes, and then the reactants were heated to 120°C and reacted for 1–2 hours, or until the production of water slowed down and stopped. After all the water had been removed, 12.192 grams (4.49%) of 9,9-bis(4-aminophenyl)fluorene and 22.615 grams (8.33%) of anisole were added to the solution. The solution was reacted at 120°C for 15–30 minutes. After the time had elapsed, 4.602 grams (1.70%) of Neximid 300 (Nexim Chemical, Sweden) and 8.541 grams (3.15%) of anisole were added to the solution. The solution was continued to react at 120°C for 4.5 hours. The resulting solution was reddish-brown and had a moderate viscosity.

[0082] Example 11 Example 10: Measurement of n and k of materials The material from Example 10 was spin-coated onto a 4-inch silicon wafer at a spin speed of 1,500 rpm for 60 seconds with a ramp of 1,500 rpm / s, and then baked on a hot plate at 120°C for 3 minutes, followed by 180°C for 5 minutes, to obtain a 200 nm film. The optical parameters were then measured using a VASE M2000. The full n and k spectra at the target wavelength are shown in Figure 8.

[0083] Example 12 Preparation of polyazomethin solution 5 In this example, 18.03 grams (12.24%) of terephthalaldehyde, 82.194 grams (55.8%) of anisole (Sigma-Aldrich, St. Louis, Missouri), and 26.22 grams (17.8%) of diethylene glycol bis(3-aminopropyl) ether (TCI, Portland, Oregon) were added to a reaction vessel having a Dean-Stark trap and a condenser attached to the Dean-Stark trap. The trap was filled with anisole to form a separation between the water produced during the reaction and the anisole. Nitrogen was pumped into the reaction vessel to create an inert atmosphere. The solution was reacted at 25°C for 15–20 minutes, and then the reactants were heated to 120°C and reacted for 1–2 hours, or until the production of water slowed down and stopped. After all the water had been removed, 7.32 grams (4.97%) of 9,9-bis(4-aminophenyl)fluorene and 13.56 grams (9.20%) of anisole were added to the solution. The solution was allowed to react at 120°C for 5–8 hours. The resulting solution was pale yellow and had a moderate viscosity.

[0084] Example 13 Example 12: Measurement of n and k of materials The material from Example 12 was spin-coated onto a 4-inch silicon wafer at a spin speed of 1,500 rpm for 60 seconds with a ramp of 1,500 rpm / s, and then baked on a hot plate at 120°C for 3 minutes, followed by 180°C for 5 minutes, to obtain a 200 nm film. The optical parameters were then measured using a VASE M2000. The full n and k spectra at the target wavelength are shown in Figure 9.

[0085] Example 14 Preparation of polyazomethin solution 6 In this example, 18.02 grams (11.82%) of terephthalaldehyde, 76.43 grams (50.13%) of anisole (Sigma-Aldrich, St. Louis, Missouri), and 23.13 grams (15.17%) of diethylene glycol bis(3-aminopropyl) ether (TCI, Portland, Oregon) were added to a reaction vessel having a Dean-Stark trap and a condenser attached to the Dean-Stark trap. The trap was filled with anisole to form a separation between the water produced during the reaction and the anisole. Nitrogen was pumped into the reaction vessel to create an inert atmosphere. The solution was reacted at 25°C for 15–20 minutes, and then the reactants were heated to 120°C and reacted for 1–2 hours, or until the production of water slowed down and stopped. After all the water had been removed, 12.19 grams (8.00%) of 9,9-bis(4-aminophenyl)fluorene and 22.68 grams (14.88%) of anisole were added to the solution. The solution was allowed to react at 120°C for 5–8 hours. The resulting solution was pale yellow and had a moderate viscosity.

[0086] Example 15 Example 14: Measurement of n and k values ​​of materials The material from Example 14 was spin-coated onto a 4-inch silicon wafer at a spin speed of 1,500 rpm for 60 seconds with a ramp of 1,500 rpm / s, and then baked on a hot plate at 120°C for 3 minutes, followed by 180°C for 5 minutes, to obtain a 200 nm film. The optical parameters were then measured using a VASE M2000. The full n and k spectra at the target wavelength are shown in Figure 10.

[0087] Example 16 Preparation of polyazomethin solution 7 In this example, 88.21 grams (11.44%) of terephthalaldehyde, 346.01 grams (44.87%) of anisole (Sigma-Aldrich, St. Louis, Missouri), and 98.04 grams (12.71%) of diethylene glycol bis(3-aminopropyl) ether (TCI, Portland, Oregon) were added to a reaction vessel having a Dean-Stark trap and a condenser attached to the Dean-Stark trap. The trap was filled with anisole to form a separation between the water produced during the reaction and the anisole. Nitrogen was pumped into the reaction vessel to create an inert atmosphere. The solution was reacted at 25°C for 15–20 minutes, and then the reactants were heated to 120°C and reacted for 1–2 hours, or until the production of water slowed down and stopped. After all the water had been removed, 83.52 grams (10.83%) of 9,9-bis(4-aminophenyl)fluorene and 155.30 grams (20.14%) of anisole were added to the solution. The solution was allowed to react at 120°C for 5–8 hours. The resulting solution was yellow and had a moderate viscosity.

[0088] Example 17 Example 16: Measurement of n and k of materials The material from Example 16 was spin-coated onto a 4-inch silicon wafer at a spin speed of 1,500 rpm for 60 seconds with a ramp of 1,500 rpm / s, and then baked on a hot plate at 120°C for 3 minutes, followed by 180°C for 5 minutes, to obtain a 200 nm film. The optical parameters were then measured using a VASE M2000. The full n and k spectra at the target wavelength are shown in Figure 11.

[0089] Example 18 Preparation of polyazomethin solution 8 In this example, 16.93 grams (10.30%) of terephthalaldehyde and 31.62 grams (19.24%) of anisole (Sigma-Aldrich, St. Louis, Missouri) were added to a reaction vessel having a Dean-Stark trap and a condenser attached to the Dean-Stark trap. The trap was filled with anisole to form a separation between the water produced during the reaction and the anisole. Nitrogen was pumped into the reaction vessel to create an inert atmosphere. 23.033 grams (14.02%) of diethylene glycol bis(3-aminopropyl) ether (TCI, Portland, Oregon) and 42.92 grams (26.12%) of anisole were mixed together, then drawn into a 60 mL syringe and attached to a syringe pump. The solution was heated to 120°C, and diethylene glycol bis(3-aminopropyl) ether anisole solution was added to the reactants via a syringe pump at a flow rate of 1 mL / min. The reaction was allowed to proceed for 1–2 hours, or until the formation of water slowed down and stopped. Once all the water had been removed, 5.24 grams (3.19%) of 5-methyl-2-phenyl-2-hexenal (Sigma-Aldrich, St. Louis, Missouri) was added, and the reaction was allowed to proceed for 20–30 minutes. Subsequently, 12.19 grams (7.42%) of 9,9-bis(4-aminophenyl)fluorene and 32.39 grams (19.71%) of anisole were added to the solution. The solution was allowed to continue reacting at 120°C for 10 hours. The resulting solution was amber yellow in color and had a moderate viscosity.

[0090] Example 19 Example 18: Measurement of n and k of materials The material from Example 18 was spin-coated onto a 4-inch silicon wafer at a spin speed of 1,500 rpm for 60 seconds with a ramp of 1,500 rpm / s, and then baked on a hot plate at 120°C for 3 minutes, followed by 180°C for 5 minutes, to obtain a 200 nm film. The optical parameters were then measured using a VASE M2000. The full n and k spectra at the target wavelength are shown in Figure 12.

[0091] Example 20 Preparation of polyazomethin solution 9 In this example, 14.172 grams (11.44%) of terephthalaldehyde, 57.81 grams (44.83%) of anisole (Sigma-Aldrich, St. Louis, Missouri), and 16.963 grams (13.15%) of diethylene glycol bis(3-aminopropyl) ether (TCI, Portland, Oregon) were added to a reaction vessel having a Dean-Stark trap and a condenser attached to the Dean-Stark trap. The trap was filled with anisole to form a separation between the water produced during the reaction and the anisole. Nitrogen was pumped into the reaction vessel to create an inert atmosphere. The solution was reacted at 25°C for 15–20 minutes, and then the reactants were heated to 120°C and reacted for 1–2 hours, or until the production of water slowed down and stopped. After all the water had been removed, 13.54 grams (10.50%) of 2,2-bis[4-(4-aminophenoxy)phenyl]propane (TCI, Portland, Oregon) and 26.03 grams (20.18%) of anisole were added to the solution. The solution was allowed to react at 120°C for 5 hours. After 5 hours, 0.464 grams (0.36%) of trans-2-pentenal (Sigma-Aldrich, St. Louis, Missouri) was added to the solution and allowed to react for 30 minutes. The resulting solution was red in color and had a moderate viscosity.

[0092] Example 21 Preparation of polyazomethin solution 10 In this example, 20.12 grams (11.37%) of terephthalaldehyde, 87.22 grams (49.31%) of PGMEA, and 26.85 grams (15.18%) of 1,3-bis(aminopropyl)tetramethyldisiloxane (Alfa Aesar, Ward Hill, Massachusetts) were added to a reaction vessel having a Dean-Stark trap and a condenser attached to the Dean-Stark trap. The trap was filled with PGMEA to form a separation between the water produced during the reaction and the PGMEA. Nitrogen was pumped into the reaction vessel to create an inert atmosphere. The solution was reacted at 25°C for 15–20 minutes, and then the reactants were heated to 120°C and reacted for 1–2 hours, or until the production of water slowed down and stopped. After all the water had been removed, 14.78 grams (8.35%) of 2,2-bis[4-(4-aminophenoxy)phenyl]propane (TCI, Portland, Oregon) and 27.94 grams (15.79%) of PGMEA were added to the solution. The solution was allowed to react at 120°C for 6–8 hours. The resulting solution was pinkish-yellow, but precipitated as a yellow powder upon cooling and had low solubility.

[0093] Example 22 Preparation of polyazomethin solution 11 In this example, 21.43 grams (12.61%) of terephthalaldehyde, 93.02 grams (54.72%) of PGMEA, and 28.63 grams (16.84%) of 1,3-bis(aminopropyl)tetramethyldisiloxane (Alfa Aesar, Ward Hill, Massachusetts) were added to a reaction vessel having a Dean-Stark trap and a condenser attached to the Dean-Stark trap. The trap was filled with PGMEA to form a separation between the water produced during the reaction and the PGMEA. Nitrogen was pumped into the reaction vessel to create an inert atmosphere. The solution was reacted at 25°C for 15–20 minutes, and then the reactants were heated to 120°C and reacted for 1–2 hours, or until the production of water slowed down and stopped. After all the water was removed, 9.42 grams (8.35%) of o-dianisidine (TCI, Portland, Oregon) and 17.47 grams (10.28%) of PGMEA were added to the solution. The solution was allowed to react at 120°C for 6–8 hours. The solution precipitated into a dark red, insoluble powder.

[0094] Example 23 Preparation of polyazomethin solution 12 In this example, 21.47 grams (11.83%) of terephthalaldehyde and 72.32 grams (39.85%) of PGMEA were added to a reaction vessel having a Dean-Stark trap and a condenser attached to the Dean-Stark trap. The trap was filled with PGMEA to create a separation between the water produced during the reaction and the PGMEA. Nitrogen was pumped into the reaction vessel to create an inert atmosphere. The reactants were heated to 120°C. Once all the terephthalaldehyde was dissolved, 13.22 grams (7.29%) of 4,4'-(1,3-phenylenediisopropylidene)bisaniline (Sigma-Aldrich, St. Louis, Missouri) was added, and the reaction was allowed to proceed for 20-60 minutes until water production slowed down and stopped. Next, 28.66 grams (15.80%) of 1,3-bis(aminopropyl)tetramethyldisiloxane (Alfa Aesar, Ward Hill, Massachusetts) was added along with 46.79 grams (25.23%) of PGMEA via an addition funnel. The solution was heated to 150°C (the reflux temperature of PGMEA) and reacted for 10–14 hours. During the reaction, the solution precipitated into a yellowish-green powder with low solubility.

Claims

1. The temporary bonding method is, A stack is prepared that includes a first substrate having a back and a front surface, an adhesive layer adjacent to the front surface containing polyazomethine, and a second substrate having a first surface adjacent to the adhesive layer. To facilitate the separation of the first and second substrates, the method includes exposing the adhesive layer to laser energy, The polyazomethine comprises a copolymer of a dialdehyde containing terephthalaldehyde and an aromatic diamine comprising at least one selected from 9,9-bis(4-aminophenyl)fluorene, 4,4'-methylenebis(2,6-diethylaniline), 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 4,4'-(1,3-phenylenediisopropylidene)bisaniline, bis[4-(3-aminophenoxy)phenyl]sulfone, or o-dianisidine and an aliphatic diamine comprising at least one selected from 1,3-bis(aminopropyl)tetramethyldisiloxane or diethylene glycol bis(3-aminopropyl) ether. A temporary bonding method wherein one of the first and second substrates is transparent to laser energy.

2. The aforementioned exposure is 100 mJ / cm² ２ ~1,300mJ / cm ２ The method according to claim 1, performed at a dose of [specified dose].

3. The method according to claim 1 or 2, wherein preparing the stack includes forming the adhesive layer on the front surface.

4. The method according to claim 3, wherein forming comprises applying a fluid adhesive composition to the surface, the fluid composition comprising polyazomethine dispersed or dissolved in a solvent system.

5. The method according to claim 4, further comprising heating the composition at a temperature of 50°C to 300°C for 30 seconds to 20 minutes to form the adhesive layer.

6. The method according to claim 3, wherein the formation includes attaching a self-supporting film containing polyazomethine to the front surface to form the adhesive layer.

7. One of the front surface and the first surface is (1) A device surface including an array of devices selected from the group consisting of integrated circuits, MEMS, microsensors, power semiconductors, light-emitting diodes, photonic circuits, interposers, embedded passive devices, and microdevices fabricated on or from silicon, silicon-germanium, gallium arsenide, and gallium nitride, (2) The method according to claims 1 to 6, selected from the group comprising a device surface comprising a solder bump, a metal post, a metal pillar, and a structure formed from a material selected from the group consisting of silicon, polysilicon, silicon dioxide, silicon (oxy)nitride, metal, low-k dielectric, polymer dielectric, metal nitride, and metal silicide.

8. The method according to any one of claims 1 to 7, wherein one of the first and second substrates includes glass.

9. The method according to any one of claims 1 to 8, further comprising subjecting the stack to a process selected from the group consisting of back grinding, chemical mechanical polishing, etching, metallizing, dielectric deposition, patterning, passivation, annealing, redistribution layer formation, and combinations thereof, before separating the first and second substrates.

10. The method according to any one of claims 1 to 9, wherein the adhesive layer is the only layer between the first and second substrates.

11. The method according to any one of claims 1 to 10, wherein the adhesive layer is non-photosensitive.

12. A first substrate having a back and a front, Adjacent to the aforementioned front surface is an adhesive layer containing polyazomethine, The adhesive layer includes a second substrate having a first surface adjacent to the adhesive layer, At least one of the front surface and the first surface is a device surface, The polyazomethine comprises a copolymer of a dialdehyde containing terephthalaldehyde and an aromatic diamine comprising at least one selected from 9,9-bis(4-aminophenyl)fluorene, 4,4'-methylenebis(2,6-diethylaniline), 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 4,4'-(1,3-phenylenediisopropylidene)bisaniline, bis[4-(3-aminophenoxy)phenyl]sulfone, or o-dianisidine and an aliphatic diamine comprising at least one selected from 1,3-bis(aminopropyl)tetramethyldisiloxane or diethylene glycol bis(3-aminopropyl) ether. A microelectronic structure in which one of the first and second substrates is transparent to laser energy.

13. The microelectronic structure according to claim 12, wherein the adhesive layer has an average thickness of 1 μm to 200 μm.

14. One of the front surface and the first surface is (1) A device surface including an array of devices selected from the group consisting of integrated circuits, MEMS, microsensors, power semiconductors, light-emitting diodes, photonic circuits, interposers, embedded passive devices, and microdevices fabricated on or from silicon, silicon-germanium, gallium arsenide, and gallium nitride, (2) A microelectronic structure according to claim 12 or 13, selected from the group comprising: a device surface comprising: solder bumps; metal posts; metal pillars; and at least one structure selected from the group comprising: a structure formed from a material selected from the group comprising: silicon, polysilicon, silicon dioxide, silicon (oxy)nitride, metal, low-k dielectric, polymer dielectric, metal nitride, and metal silicide.

15. The microelectronic structure according to any one of claims 12 to 14, wherein one of the first and second substrates includes glass.

16. The microelectronic structure according to any one of claims 12 to 15, wherein the adhesive layer is the only layer between the first and second substrates.

17. The microelectronic structure according to any one of claims 12 to 16, wherein the adhesive layer is non-photosensitive.

18. A polyazomethin comprising an aromatic diamine comprising at least one selected from terephthalaldehyde, 9,9-bis(4-aminophenyl)fluorene, 4,4'-methylenebis(2,6-diethylaniline), 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 4,4'-(1,3-phenylenediisopropylidene)bisaniline, bis[4-(3-aminophenoxy)phenyl]sulfone, or o-dianisidine, and a repeating monomer of an aliphatic diamine comprising at least one selected from 1,3-bis(aminopropyl)tetramethyldisiloxane or diethylene glycol bis(3-aminopropyl) ether.

19. The polyazomethin according to claim 18, wherein at least one of the following is true: a. The polyazomethine contains 30 mol% to 70 mol% of the dialdehyde relative to 100 mol% of the polymer; b. The polyazomethine contains a total of 30 mol% to 70 mol% aromatic diamines and aliphatic diamines relative to 100 mol% of the polymer; c. The polyazomethine contains 5 mol% to 55 mol% of an aliphatic diamine relative to 100 mol% of the polymer; d. The polyazomethine contains 5 mol% to 55 mol% of aromatic diamine relative to 100 mol% of the polymer; e. The molar ratio of aromatic diamines to aliphatic diamines is 1:4 to 4:1; or f. The molar ratio of total diamines to total dialdehydes is 1:4 to 4:

1.

20. A composition comprising the polyazomethine described in claim 18 or 19, dispersed or dissolved in a solvent system.

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