Photocurable composition

Abstract

A photocurable composition may contain a polymerizable material and a photoinitiator, wherein the polymerizable material may contain 10-40% by weight of a monofunctional monomer of formula (1), wherein R1 is H or C1-C6 alkyl, and R2 and R3 are C1-C 10 alkyl or one or more substitutions of alkyl-aryl, and R4, R5 are H or C1-C 10 alkyl. (Formula 1) The photocurable composition may have a viscosity of not more than 15 mPa·s, and if subjected to a high-temperature baking treatment, the photocured layer of the photocurable composition may have a low thermal shrinkage rate and a carbon content of at least 74%.

Description

Technical Field

[0001] The present disclosure relates to a photocurable composition, and particularly to a photocurable composition for inkjet adaptive planarization, which is suitable for forming a photocured layer having low thermal shrinkage during a subsequent baking treatment. Background Art

[0002] Inkjet adaptive planarization (IAP) is a process for planarizing a substrate surface (e.g., a wafer containing a circuit) by spraying droplets of a photocurable composition onto the substrate surface and bringing a flat superstrate into direct contact with the added liquid to form a flat liquid layer. The flat liquid layer is typically cured under ultraviolet light exposure, and after removing the superstrate, a flat polymer surface is obtained, which is subjected to subsequent processing steps such as baking, etching, and / or further deposition steps.

[0003] Subsequent baking of the formed photocured layer is typically carried out at a temperature above its glass transition temperature. Baking usually results in a denser packing of the polymer layer, which causes undesirable layer shrinkage and may be a further challenge to the planarization efficacy. Typically, the thermal shrinkage during baking is greater than the shrinkage during photocuring of the photocurable composition.

[0004] There is a need for improved IAP materials that result in a flat photocured layer with a low shrinkage rate during subsequent processing. Summary of the Invention

[0005] In one embodiment, the photocurable composition may comprise a photoinitiator and a polymerizable material, wherein the polymerizable material may comprise a monofunctional acrylate monomer having the structure of formula (1), wherein R1 is H or C1-C6 alkyl, and R2 and R3 are one or more substituents of C1-C 10 alkyl or alkyl-aryl, and R4, R5 are H or C1-C 10 alkyl,

[0006]

[0007] Based on the total weight of the polymerizable material, the amount of the acrylate monomer of formula (1) may be at least 10% by weight and not greater than 30% by weight; and the carbon content of the photocured layer of the photocurable composition may be at least 74%.

[0008] In one aspect, the polymeric material may further comprise at least one polyfunctional acrylate monomer. In a particular aspect, the at least one polyfunctional acrylate monomer may include a difunctional acrylate monomer, a trifunctional acrylate monomer, a tetrafunctional acrylate monomer, or any combination thereof. In a certain particular aspect, the at least one polyfunctional acrylate monomer may include bisphenol A dimethacrylate (BPADMA).

[0009] In another particular aspect of the photocurable composition, the amount of the polyfunctional acrylate monomer may be at least 10% by weight and not more than 30% by weight, based on the total weight of the polymeric material.

[0010] In a specific embodiment of the photocurable composition, the monofunctional acrylate monomer may have the structure of formula (2), wherein R1 is H or CH3:

[0011]

[0012] In one aspect, the amount of the monofunctional acrylate monomer of formula (2) may be not more than 25% by weight, based on the total weight of the polymeric material.

[0013] In another aspect, the amount of the monofunctional acrylate monomer of formula (2) may be not more than 15% by weight, based on the total weight of the polymeric material.

[0014] In yet another embodiment, the photocurable composition may be adjusted such that the photocured layer of the composition has a thermal shrinkage rate of not more than 7.5%, where the thermal shrinkage rate is the difference in the thickness of the photocured layer before and after baking at 250 °C for 2 minutes.

[0015] In another aspect, the viscosity of the photocurable composition may be not more than 15 mPa·s.

[0016] In yet another aspect, the photocurable composition may be adjusted such that the photocured layer of the composition has an Ohnishi number of not more than 2.9.

[0017] In one embodiment, the laminate may comprise a substrate and a photocured layer covering the substrate, wherein the photocured layer is formed from the above-described photocurable composition.

[0018] In one aspect of the laminate, the photocured layer may have a thermal shrinkage rate of not more than 7%, where the thermal shrinkage rate is the difference in the thickness of the photocured layer before and after baking at 250 °C for 2 minutes.

[0019] In another aspect of the laminate, the photocured layer may have an Ohnishi number greater than 2.9.

[0020] In yet another embodiment, a method of forming a photocurable layer on a substrate may include: applying a layer of a photocurable composition on the substrate, wherein the photocurable composition may comprise a photoinitiator and a polymerizable material. The polymerizable material may comprise 10 wt% to 30 wt% of a monofunctional acrylate monomer having the structure of formula (1), wherein R1 is H or C1-C6 alkyl; R2 and R3 are one or more substituents of C1-C 10 alkyl or alkyl-aryl; and R4, R5 are H or C1-C 10 alkyl,

[0021]

[0022] contacting the photocurable composition with a cover layer; irradiating the photocurable composition with light to form a photocurable layer; and removing the cover layer from the photocurable layer.

[0023] In one aspect of the method, the photocurable layer may have a thermal shrinkage rate of no more than 7.5%, which is the difference in the thickness of the photocurable layer before and after a baking treatment at 250 °C for 2 minutes.

[0024] In yet another aspect of the method, the viscosity of the photocurable composition may be no more than 15 mPa·s.

[0025] In certain aspects of the method, the photocurable composition may further comprise bisphenol A dimethacrylate (BPADMA) in an amount of 10 wt% to 30 wt% of the total weight of the polymerizable composition.

[0026] In another embodiment, a method of forming an article may include: applying a layer of a photocurable composition on a substrate, wherein the photocurable composition may comprise a photoinitiator and a polymerizable material, the polymerizable material comprising 10 wt% to 30 wt% of a monofunctional acrylate monomer having the structure of formula (1), wherein R1 is H or C1-C6 alkyl; R2 and R3 are C1-C 10 alkyl or alkyl-aryl with one or more substituents; and R4, R5 are H or C1-C 10 alkyl,

[0027]

[0028] contacting the photocurable composition with a cover layer; irradiating the photocurable composition with light to form a photocurable layer; removing the cover layer from the photocurable layer; forming a pattern on the substrate; treating the substrate on which the pattern has been formed in the forming; and manufacturing an article from the substrate treated in the treating.

[0029] Detailed Description

[0030] The following description is provided to assist in understanding the teachings disclosed herein, and the following description will focus on specific embodiments and implementations of the teachings. This focus is provided to assist in describing the teachings and should not be construed as a limitation on the scope or applicability of the teachings.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The materials, methods, and examples are illustrative only and not intended to be limiting. To the extent not described herein, many details regarding specific materials and processing operations are conventional and can be found in textbooks and other sources within the fields of imprinting and lithography.

[0032] As used herein, the terms "comprises," "comprising," "includes," "including," "has," "having," or any other variation thereof are intended to cover a non-exclusive inclusion. For example, a process, method, article, or apparatus that comprises a list of features is not necessarily limited to those features but may include other features not expressly listed or inherent to such process, method, article, or apparatus.

[0033] As used herein, and unless expressly stated to the contrary, "or" means inclusive-or rather than exclusive-or. For example, the condition A or B is satisfied by any one of the following: A is true (or present) and B is false (or absent), A is false (or absent) and B is true (or present), and both A and B are true (or present).

[0034] In addition, the articles "a" or "an" are used to describe the elements and components described herein. This is for convenience only and gives a general sense of the scope of the invention. This description should be read to include one or at least one, and the singular also includes the plural unless the meaning is clearly different.

[0035] The present disclosure relates to a photocurable composition comprising a photoinitiator and a polymerizable material, wherein the polymerizable material may include a monofunctional acrylate monomer having the structure of formula (1), wherein R1 is H or C1-C6 alkyl, and R2 and R3 are C1-C 10 alkyl or one or more substitutions of alkyl-aryl, and R4, R5 are H or C1-C 10 alkyl,

[0036]

[0037] In a particular aspect, the monofunctional acrylate monomer may have the structure of formula (2), where R1 is H or CH3,

[0038]

[0039] Surprisingly, it has been observed that certain combinations of the formula (1) monomer and polyfunctional acrylate monomers can result in a photocurable composition having a low thermal shrinkage rate after curing. In one aspect, the photocured layer formed from the photocurable composition may have a thermal shrinkage rate of no greater than 7.5%, such as no greater than 7.2%, no greater than 7.0%, no greater than 6.8%, no greater than 6.5%, no greater than 6.3%, or no greater than 6.0% when subjected to a baking treatment at 250 °C for 2 minutes. As used herein, the thermal shrinkage rate is calculated as the % difference in the height of the photocured layer before and after the baking treatment.

[0040] In one aspect, the polyfunctional acrylate monomer of the polymerizable material may be a difunctional acrylate monomer, a trifunctional acrylate monomer, a tetrafunctional acrylate monomer, or any combination thereof. Non-limiting examples of the polyfunctional acrylate monomer may be bisphenol A dimethacrylate, neopentyl glycol diacrylate, trimethylolpropane triacrylate, pentaerythritol tetraacrylate, or any combination thereof.

[0041] In a particular aspect, the polyfunctional acrylate monomer may be a difunctional acrylate monomer. In a certain particular aspect, the difunctional acrylate monomer may be bisphenol A dimethacrylate, which has the structure shown in formula (3):

[0042]

[0043] In one aspect, the amount of the monofunctional acrylate monomer of formula (1) may be at least 10% by weight, such as at least 15% by weight, or at least 20% by weight, based on the total weight of the polymerizable material. In another particular aspect, the amount of the formula (1) monomer may be no greater than 40% by weight, or no greater than 30% by weight, or no greater than 25% by weight, or no greater than 20% by weight, or no greater than 15% by weight, or no greater than 12% by weight, or no greater than 10% by weight, based on the total weight of the polymerizable material. The amount of the formula (1) monomer may be a value within the range between any of the above minimum and maximum values.

[0044] On the other hand, the amount of the polyfunctional acrylate monomer can be at least 10% by weight, or at least 15% by weight, or at least 20% by weight, or at least 25% by weight, based on the total weight of the polymerizable material. On the other hand, based on the total weight of the polymerizable material, the amount of the polyfunctional acrylate monomer can be not more than 50% by weight, such as not more than 40% by weight, not more than 30% by weight, not more than 25% by weight, or not more than 20% by weight. The amount of the polyfunctional acrylate monomer can be a value within the range between any of the above minimum and maximum values, such as 10% by weight to 50% by weight, 15% by weight to 40% by weight, or 10% by weight to 30% by weight.

[0045] In yet another aspect, the weight % ratio of the monofunctional monomer of formula (1) to the polyfunctional acrylate monomer can be from 1:5 to 5:1, such as from 1:3 to 3:1, or from 1:1 to 3:1.

[0046] What is important for the selection of the monomers is the following aspect: maintaining a low viscosity of the polymerizable composition before curing. In one embodiment, the viscosity of the curable composition can be not more than 30 mPa·s, such as not more than 25 mPa·s, not more than 20 mPa·s, not more than 15 mPa·s, or not more than 10 mPa·s. In other specific embodiments, the viscosity can be at least 3 mPa·s, such as at least 5 mPa·s, or at least 8 mPa·s. In a particularly preferred aspect, the photocurable composition can have a viscosity of not more than 15 mPa·s. As used herein, all viscosity values are related to the viscosity measured by the Brookfield method using a Brookfield viscometer at a temperature of 23°C.

[0047] Based on the total weight of the photocurable composition, the amount of the polymerizable material in the photocurable composition can be at least 75% by weight, such as at least 80% by weight, at least 85% by weight, at least 90% by weight, or at least 95% by weight. On the other hand, the amount of the polymerizable material can be not more than 99% by weight, such as not more than 98% by weight, or not more than 97% by weight, or not more than 95% by weight, based on the total weight of the photocurable composition. The amount of the polymerizable material can be a value between any of the above minimum and maximum values. In a specific aspect, the amount of the polymerizable material can be at least 85% by weight and not more than 98% by weight.

[0048] In another embodiment, in addition to the monofunctional acrylate monomer of formula (1) and at least one polyfunctional acrylate monomer, the polymerizable material of the photocurable composition can include a certain amount of polymerizable monomers, oligomers or polymers. Non-limiting examples of these polymerizable compounds can be: for example, benzyl acrylate, 1-naphthyl acrylate, divinylbenzene, maleimide monomers, vinyl ethers or styrene derivatives.

[0049] In one aspect, in addition to the monofunctional acrylate monomer and the polyfunctional acrylate monomer of formula (1), the polymerizable material may include at least one additional monofunctional acrylic monomer, such as at least two or three additional monofunctional acrylate monomers. In a particular aspect, based on the total weight of the polymerizable material, the amount of the at least one additional monofunctional acrylate monomer may be at least 30 wt%, or at least 40 wt%, or at least 50 wt%, or at least 60 wt%. In a certain particular aspect, the polymerizable material may contain benzyl acrylate as the additional monofunctional acrylate monomer in an amount of at least 40 wt%.

[0050] In yet another aspect, the curable composition of the present disclosure may be solvent-free.

[0051] To initiate the photocuring of the composition upon exposure to light, one or more photoinitiators may be included in the photocurable composition.

[0052] In one aspect, curing may also be carried out by a combination of photocuring and thermal curing.

[0053] The photocurable composition may further contain one or more optional additives. Non-limiting examples of optional additives may be stabilizers, dispersants, solvents, surfactants, inhibitors, or any combination thereof.

[0054] In one embodiment, the photocurable composition may be applied to a substrate to form a photocured layer. As used herein, the combination of the substrate and the photocured layer covering the substrate is referred to as a laminate.

[0055] The combination of the monomers of the polymerizable material may result in a high carbon content in the photocured layer. In one embodiment, the carbon content of the photocured layer may be at least 70%, such as at least 72%, at least 73%, at least 74%, at least 75%, at least 76%, or at least 77%. In a particular aspect, the carbon content may be at least 74%.

[0056] In another aspect, the photocured layer of the laminate may have a Nishii number of not more than 2.9, or not more than 2.8, or not more than 2.7, or not more than 2.6. In another aspect, the Nishii number may be at least 1.8, such as at least 1.9, at least 2.0, at least 2.1, at least 2.2, or at least 2.3.

[0057] In a particular embodiment, the photocured layer may have a carbon content of at least 74% and a Nishii number of not more than 2.9.

[0058] The present disclosure also relates to a method for forming a photocurable layer. The method may include applying a layer of the above-described photocurable composition over a substrate, bringing the photocurable composition into contact with a template or a covering layer; irradiating the photocurable composition with light to form a photocurable layer; and removing the template or the covering layer from the photocurable layer.

[0059] The substrate and the solidified layer may be subjected to additional processing, such as an etching process, to transfer an image into the substrate corresponding to the pattern in one or both of the solidified layer and / or a patterned layer beneath the solidified layer. The substrate may further be subjected to known steps and processes for device (article) fabrication, including, for example, curing, oxidation, layer formation, deposition, doping, planarization, etching, removal of formable materials, cutting, bonding, and encapsulation, among others.

[0060] The photocurable layer may further be used as an interlayer insulating film for semiconductor devices, such as LSI, system LSI, DRAM, SDRAM, RDRAM, or D-RDRAM, or as a resist film used in semiconductor manufacturing processes.

[0061] As further demonstrated in the examples, it has surprisingly been found that certain combinations of polymerizable monomers of the monofunctional acrylate monomer of formula (1) and at least one second monomer (including polyfunctional acrylate monomers) in the photocurable composition can have very suitable properties, particularly for IAP processing. The photocurable composition of the present disclosure may have a desired low viscosity of less than 15 mPa·s and is capable of forming a photocurable layer with a low thermal shrinkage rate if exposed to a high-temperature baking treatment. Examples

[0062] The following non-limiting examples illustrate the concepts described herein.

[0063] Example 1

[0064] Preparation of a photocurable IAP composition.

[0065] Five photocurable compositions (Samples S1 to S5) were prepared, and for each sample the following were combined: the monofunctional acrylate monomer 3-phenoxybenzyl acrylate (POBA) with the difunctional acrylate monomer bisphenol A dimethacrylate (BPADMA), and two additional monomers selected from benzyl acrylate (BA), 1-naphthyl acrylate (1-NA), and o-phenylphenol EO acrylate (Miramer M1142, obtained from Miyoshi Specialty Chemicals Co., Ltd.). The exact combination and amounts of the monomers of the polymerizable materials for each composition are summarized in Table 1 below.

[0066] In addition, two comparative photocurable compositions were prepared as follows: Bifunctional BPADMA was combined with BA and 1-NA (comparative composition C1), and BPADMA was combined with BA, 1-NA, and 1-adamantyl methacrylate (1-AMA) (comparative composition C2). The structure of 1-AMA is shown in formula (4).

[0067]

[0068] The polymeric materials of comparative compositions C1 and C2 are also summarized in Table 1. All the photocurable compositions also contained 1-5 wt% of Irgacure 819 as a photoinitiator and 0.1-3 wt% of C10GM2070 as a surfactant.

[0069] Table 1:

[0070] Sample POBA BPADMA BA 1-NA M1142 1-AMA Viscosity [cP] S1 20 20 50 10 8.69 S2 20 20 50 10 9.55 S3 10 20 50 20 8.90 S4 30 20 50 8.37 S5 40 20 40 10.98 C1 20 50 30 8.10 C2 20 50 15 15 8.29

[0071] The photocurable layer was prepared from the photocurable compositions summarized in Table 1 by applying a liquid film of the photocurable composition having a thickness of about 300 microns on a glass substrate and subjecting the liquid film to an ultraviolet light intensity of 4 mW / cm 2 for 600 seconds, which corresponds to a curing energy dose of 2.4 J / cm 2 . After photocuring, all the photocurable layers were solids.

[0072] Measurement of thermal shrinkage rate

[0073] To evaluate the thermal shrinkage rate, after photocuring, the photocurable layer was placed on a hot plate at a temperature of 250 °C for two minutes, which is also referred to as baking in this article. All baking treatments were carried out in air. The thermal shrinkage rate was obtained by measuring the change in the thickness of the test layer before and after the baking treatment using an ellipsometer and calculating the thermal shrinkage rate (St) according to the formula St = (T u – T b ) / T u , where T u is the layer thickness in the unbaked stage before baking, and T b is the layer thickness after baking.

[0074] Table 2 summarizes the thermal shrinkage rate test results of all the samples. Table 2 also contains the weight % of the calculated carbon content and the Ohm value of the layer. It can be seen that the thermal shrinkage rate of samples S1 to S5 is about 1% to 3% lower than that of comparative samples C1 and C2.

[0075] Table 2:

[0076] Sample Thermal shrinkage rate [%] during baking at 250 °C Carbon content [%] Onishi number S1 6.43 75.20 2.65 S2 6.68 74.89 2.72 S3 7.09 75.51 2.62 S4 6.02 74.89 2.67 S5 5.32 75.05 2.65 C1 8.09 75.82 2.59 C2 7.96 75.45 2.70

[0077] The viscosity of the sample was measured at 23 °C using a Brookfield viscometer LVDV-II+Pro at 200 rpm with spindle size #18. For the viscosity test, approximately 6 - 7 mL of the sample liquid was added to the sample chamber, sufficient to cover the spindle head. For all viscosity tests, at least three measurements were made and the average value was calculated.

[0078] The Oishi number (ON) is known as an empirical parameter and is calculated as the ratio of the total number of atoms (Nt) in the polymer repeating unit divided by the difference between the number of carbon atoms (Nc) and the number of oxygen atoms (No) in the unit, ON = Nt / (Nc - No). For the calculation of the Oishi number, it is assumed that the cured material contains 100 wt% of the polymer monomer units formed by addition polymerization (no atomic loss during polymerization).

[0079] The descriptions and explanations of the embodiments described herein are intended to provide a general understanding of the structures of the various embodiments. The descriptions and explanations are not intended to serve as an exhaustive and comprehensive description of all elements and features of the devices and systems using the structures or methods described herein. Different embodiments may also be provided combinatorially in a single embodiment, and conversely, the various features described in the context of a single embodiment for the sake of brevity may also be provided individually or in any sub-combination. Additionally, references to numerical values recited in ranges include each value and every individual value within that range. Many other embodiments will be apparent to those skilled in the art only after reading this specification. Other embodiments may be used and other embodiments may be derived from this disclosure, such that structural substitutions, logical substitutions, or other changes may be made without departing from the scope of this disclosure. Accordingly, this disclosure should be regarded as illustrative rather than restrictive.

Claims

1. A photocurable composition comprising a photoinitiator and a polymerizable material, wherein The polymeric material comprises a monofunctional acrylate monomer having the structure of formula (1), wherein R1 is H or a C1-C6 alkyl group, and R2 and R3 are one or more substituents of C1-C 10 alkyl or alkyl-aryl, and R4, R5 are H or C1-C 10 alkyl based on the total weight of the polymerizable material, the amount of the acrylate monomer of formula (1) is at least 10% by weight and not more than 40% by weight; and the carbon content of the photocured layer of the photocurable composition is at least 74%.

2. The photocurable composition according to claim 1, wherein the polymerizable material further comprises at least one polyfunctional acrylate monomer.

3. The photocurable composition according to claim 2, wherein the at least one polyfunctional acrylate monomer comprises a difunctional acrylate monomer, a trifunctional acrylate monomer, a tetrafunctional acrylate monomer, or any combination thereof.

4. The photocurable composition according to claim 3, wherein the at least one polyfunctional acrylate monomer comprises bisphenol A dimethacrylate.

5. The photocurable composition according to claim 3, wherein the amount of the polyfunctional acrylate monomer is at least 10% by weight and not more than 40% by weight, based on the total weight of the polymerizable material.

6. The photocurable composition according to claim 1, wherein the polymerizable material further comprises at least one monofunctional acrylate monomer different from the monofunctional acrylate monomer of formula 1.

7. The photocurable composition according to claim 1, wherein the photocurable composition is adjusted such that the photocured layer of the composition has a thermal shrinkage rate of not more than 7.5%, and the thermal shrinkage rate is the difference in the thickness of the photocured layer before and after baking treatment at 250 °C for 2 minutes.

8. The photocurable composition according to claim 1, wherein the viscosity of the photocurable composition is not more than 15 mPa·s.

9. The photocurable composition according to claim 1, wherein the photocurable composition is adjusted such that the photocured layer of the composition has a Denshi number of not more than 2.

9.

10. A laminate comprising a substrate and a photocured layer covering the substrate, wherein the photocured layer is formed from the photocurable composition according to claim 1.

11. A method of forming a photocured layer on a substrate, comprising: applying a layer of the photocurable composition according to claim 1 on the substrate; bringing the photocurable composition into contact with a covering layer; irradiating the photocurable composition with light to form a photocured layer; and removing the covering layer from the photocured layer.

12. A method of forming an article, the method comprising: applying a layer of the photocurable composition according to claim 1 on a substrate; bringing the photocurable composition into contact with a covering layer; irradiating the photocurable composition with light to form a photocured layer; removing the covering layer from the photocured layer; forming a pattern on the substrate; processing the substrate on which the pattern has been formed in the forming; and manufacturing an article from the substrate processed in the processing.

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