Method for manufacturing wiring structure

Abstract

Provided is a novel method for manufacturing a wiring structure, comprising a step for forming a conductor layer by two-stage electrolytic plating on a substrate having a main surface on which a first recess and a second recess are formed, the minimum width of the first bottom surface being larger than the minimum width of the second bottom surface. The method includes: a step of forming a temporary protective layer having a pattern including an opening exposing at least a portion of the first bottom surface; a step for forming a first metal plating layer on the first bottom surface; removing the temporary protective layer to expose the second recess; and forming a conductor layer including the first metal plating layer and the second metal plating layer by forming a second metal plating layer including a portion filling the second recess and a portion provided on the first metal plating layer.

Description

Technical Field

[0001] This invention relates to a method for manufacturing a wiring structure. Background Technology

[0002] In electronic component devices incorporating semiconductor elements, wiring structures are sometimes provided that include fine wiring such as rewiring layers connected to the semiconductor elements. These wiring structures are sometimes formed by an inlay method that includes forming an electroplated layer within an opening in an insulating layer (e.g., Patent Document 1).

[0003] Previous technical documents Patent documents Patent Document 1: International Publication No. 2018 / 056466 Summary of the Invention

[0004] The technical problem to be solved by the invention The growth rate of metal coatings formed by electroplating tends to be faster within openings with narrower widths. Therefore, when metal coatings are formed simultaneously within multiple openings of varying widths via electroplating, if the metal coating is formed by fully filling the wide openings, the amount of excess metal coating (overburden) extending beyond the narrower openings tends to increase. Consequently, the amount of overburden that needs to be removed after metal coating formation, for purposes such as planarization, can sometimes increase.

[0005] The present invention relates to a method for forming a wiring structure by electrolytic plating within a plurality of openings of different widths, which enables the suppression of the amount of cover layer that needs to be removed and the formation of a metal plating.

[0006] means for solving technical problems This invention includes the following: [1] A method for manufacturing a wiring structure includes the following steps: The step of preparing a substrate is a substrate having a main surface having a first recess and a second recess, wherein the first recess has a first bottom surface and a first wall surface, the second recess has a second bottom surface and a second wall surface, and the minimum width of the first bottom surface is greater than the minimum width of the second bottom surface. The step of forming a temporary protective layer on the main surface of the substrate, the temporary protective layer having a pattern including an opening that exposes at least a portion of the first bottom surface, and including a portion that blocks the second recess; The step of forming a first metal plating layer on the first bottom surface exposed within the opening; The step of removing the temporary protective layer to expose the second recess; The step of forming a conductor layer comprising the first metal plating layer and the second metal plating layer by forming a second metal plating layer, wherein the second metal plating layer comprises a portion filling the second recess and a portion disposed on the first metal plating layer; and The steps of forming a first conductor portion disposed within the first recess and including the first metal plating layer and the second metal plating layer, and a second conductor portion disposed within the second recess and including the second metal plating layer, by removing a portion of the conductor layer. The substrate includes a seed layer, the seed layer having a surface comprising the first bottom surface and the second bottom surface. The first metal coating and the second metal coating are formed by electroplating. [2] According to the method described in [1], wherein, The substrate further comprises an insulating layer having a pattern including an opening along the first wall and an opening along the second wall. [3] According to the method described in [1] or [2], wherein, The first metal coating is formed by creating a recess on the surface of the first metal coating that is opposite to the first bottom surface. [4] According to any one of [1] to [3], wherein, The steps for forming the temporary protective layer include: The step of forming a photosensitive resist layer on the main surface of the substrate; and The step of forming the temporary protective layer having the pattern by exposing and developing the photosensitive resist layer. [5] According to the method described in [4], wherein, The photosensitive resist layer comprises an adhesive polymer, a photopolymerizable compound having olefinic unsaturated bonds, and a photopolymerization initiator.

[0012] Invention Effects When a wiring structure is formed using a method that includes forming a metal plating layer by electrolytic plating within multiple openings of different widths, the amount of cover layer that needs to be removed can be suppressed, and a metal plating layer can be formed. Attached Figure Description

[0013] Figure 1 This is a process diagram illustrating an example of a method for manufacturing a wiring structure.

[0014] Figure 2 This is a process diagram illustrating an example of a method for manufacturing a wiring structure.

[0015] Figure 3 This is a process diagram illustrating an example of a method for manufacturing a wiring structure. Detailed Implementation

[0016] This invention is not limited to the following examples.

[0017] Figure 1 , Figure 2 and Figure 3 This is a process diagram illustrating an example of a method for manufacturing a wiring structure. Figures 1-3 The method shown includes the following steps: preparing a substrate 1, the substrate 1 having a main surface S1, the main surface S1 having a first recess 11 having a first bottom surface 11a and a second recess 12 having a second bottom surface 12a; forming a temporary protective layer 7 on the main surface S1 of the substrate 1, the temporary protective layer 7 having a pattern including an opening 7a that exposes at least a portion of the first bottom surface 11a, and including a portion that blocks the second recess 12; forming a first gold layer on the first bottom surface 11a exposed within the opening 7a. The steps include: forming a plating layer 51; removing a temporary protective layer 7 to expose the second recess 12; forming a conductor layer 5 comprising a first metal plating layer 51 and a second metal plating layer 52 by forming a second metal plating layer 52, wherein the second metal plating layer 52 includes a portion filling the second recess 12 and a portion disposed on the first metal plating layer 51; and forming a first conductor portion 5A disposed in the first recess 11 and a second conductor portion 5B disposed in the second recess 12 by removing a portion of the conductor layer 5. By this method, a wiring structure 50 comprising a circuit composed of the first conductor portion 5A and the second conductor portion 5B can be formed.

[0018] The first recess 11 formed on the main surface S1 of the substrate 1 has a first bottom surface 11a and a first wall surface 11b surrounding the first bottom surface 11a. The second recess 12 formed on the main surface S1 of the substrate 1 has a second bottom surface 12a and a second wall surface 12b surrounding the second bottom surface 12a. The minimum width W1 of the first bottom surface 11a is greater than the minimum width W2 of the second bottom surface 12a. The minimum width of the bottom surface having a long side direction can be the minimum value of the width in the direction perpendicular to its long side direction. Among the minimum widths of rectangular or approximately rectangular bottom surfaces, the length of its short side is considered the minimum width.

[0019] The ratio W1 / W2 of the minimum width of the first base surface 11a to the minimum width W2 of the second base surface 12a can be 3 or more and less than 100, 5 or more and less than 500, or 20 or more and less than 1000. The minimum width W1 of the first base surface 11a can be 10 μm or more and less than 200 μm, 50 μm or more and less than 500 μm, or 20 μm or more and less than 2000 μm. The minimum width W2 of the second base surface 12a can be 1 μm or more and less than 3 μm, 0.5 μm or more and less than 5 μm, or 0.3 μm or more and less than 10 μm.

[0020] The main surface S1 of substrate 1 can be formed with three or more recesses of different minimum widths. In this case, for these multiple recesses, using any minimum width as a reference value, a recess with a bottom surface having a minimum width greater than or equal to the reference value can be considered as a first recess, and a recess with a bottom surface having a minimum width less than the reference value can be considered as a second recess. The reference value for the minimum width is set, for example, in the range of 0.3 μm or more and 10 μm or less. In this case, the ratio W1 / W2 of the average value of the minimum width W1 to the average value of the minimum width W2 can be 3 or more and 100 or less, 5 or more and 500 or less, or 20 or more and 1000 or less.

[0021] The substrate 1 has a substrate body portion 2 and a seed layer 3 disposed on the main surface S1 side of the substrate body portion 2.

[0022] The substrate body 2 has a base 2A located closer to the inner side than the first bottom surface 11a and the second bottom surface 12a, and a plurality of substrate protrusions 2B disposed on the base 2A. A first recess 11 and a second recess 12 are formed between adjacent substrate protrusions 2B. The substrate protrusions 2B may be integrally formed with part or all of the base 2A, or the substrate protrusions 2B may be disposed separately from the base 2A.

[0023] The substrate body 2 or substrate 2A can be a temporary support for forming a wiring structure, or it can be a component containing circuitry connected to the wiring in the wiring structure. The substrate body 2 or substrate protrusion 2B can also be an insulating layer constituting the wiring structure. For example, the substrate 1 can be a component containing semiconductor elements, and the wiring structure can be a rewiring layer serving as a wiring structure connected to the semiconductor elements. In this case, the method according to the present invention can be used to manufacture, for example, a fan-out type semiconductor package having semiconductor elements and a rewiring layer. Furthermore, the method according to the present invention can also be used to manufacture an intermediary layer serving as a wiring structure connecting semiconductor elements to each other in so-called 2.5D, 2.3D, 2.1D, and other semiconductor packages.

[0024] The surface of the seed layer 3 opposite to the substrate body 2 includes a first bottom surface 11a and a second bottom surface 12a. Figure 1 In the example, the surface of seed layer 3 further includes a first wall surface 11b and a second wall surface 12b. In other words, seed layer 3 forms the entirety of main surface S1. Seed layer 3 is used to form a first metal plating layer 51 or a second metal plating layer 52 by electrolytic plating. Seed layer 3 may be a layer containing a metal such as copper. The thickness of seed layer 3 may be, for example, 50 nm or more and 500 nm or less. Seed layer 3 can be formed, for example, by sputtering. Seed layer 3 can also be formed by electroless plating.

[0025] like Figure 1 As shown in (b), a temporary protective layer 7 is formed on the main surface S1 of the substrate 1, including a portion that blocks the second recess 12. The temporary protective layer 7 has a pattern including an opening 7a that exposes at least a portion of the first bottom surface 11a. The temporary protective layer 7 may be configured to protrude at the end of the first recess 11. Figure 1 The temporary protective layer 7 shown in the example fills the second recess 12, but the temporary protective layer does not necessarily need to completely fill the second recess. It can also form a cavity between the temporary protective layer 7 and the seed layer 3 in the second recess.

[0026] The temporary protective layer 7 can be formed, for example, by a method including the steps of: providing a photosensitive resist layer on the main surface 1S of the substrate 1; and patterning the photosensitive resist layer by exposing and developing it to form a temporary protective layer 7 having a pattern including an opening 7a. Examples of resist materials (photosensitive resin compositions) used to form the photosensitive resist layer in this case will be described later.

[0027] like Figure 2 As shown in (c), a first metal plating layer 51 is formed on the first bottom surface 11a exposed within the opening 7a by electrolytic plating. The first metal plating layer 51 may be a copper-containing layer. The first metal plating layer 51 is formed in a manner that does not completely fill the first recess 11. For example, the ratio of the minimum thickness of the first metal plating layer 51 to the depth of the first recess 11 may be 0.2 or more and 0.9 or less. Here, thickness refers to the thickness in the direction perpendicular to the first bottom surface 11a. A recess may be formed on the surface of the first metal plating layer 51 opposite to the first bottom surface 11a. This recess typically has a shape such that the thickness of the first metal plating layer 51 is minimum at the central portion of the first bottom surface 11a.

[0028] After the first metal coating 51 is formed, as Figure 2 As shown in (d), the temporary protective layer 7 is removed. The second recess 12 is exposed by removing the temporary protective layer 7. The temporary protective layer 7 can be removed, for example, by dissolving it in a stripping solution.

[0029] Next, as Figure 3As shown in (e), the second metal plating layer 52 is formed by electrolytic plating. The first metal plating layer 51 may also be a layer containing copper. The second metal plating layer 52 includes a portion filling the second recess 12, a portion disposed within the first recess 11 on the first metal plating layer, and a portion protruding from the first recess 11 and the second recess 12 (cover layer). The conductor layer 5 is composed of the first metal plating layer 51 and the second metal plating layer 52. Because the first metal plating layer 51 is provided in advance, it is possible to avoid the formation of an excessive cover layer near the second recess 12, and a conductor layer 5 filling the first recess 11 and the second recess 12 is formed. As a result, as Figure 3 As shown in (f), the amount of conductor layer 5 that needs to be removed to form the wiring structure 50 having the first conductor portion 5A and the second conductor portion 5B can be suppressed. Furthermore, even if the amount of the cover layer is relatively small, the surface S2 of the conductor layer 5 (the second metal plating layer 52) opposite to the substrate 1 can easily become flat. For the conductor layer 5 to be effectively removed by methods such as chemical mechanical polishing, a flat surface of the conductor layer 5 is advantageous.

[0030] In the wiring structure 50 formed by removing a portion of the conductor layer 5, the first conductor portion 5A includes a first metal plating layer 51 and a second metal plating layer 52, and the second conductor portion 5B includes a second metal plating layer 52. Figure 3 In the example case, a portion of the seed layer 3 is also removed, forming a flat main surface S3 from the first conductor portion 5A, the second conductor portion 5B, and the substrate 1 (or substrate body portion 2). The first conductor portion 5A, having a wider width, can be, for example, a pad or a via. The second conductor portion 5B, having a narrower width, can be, for example, a wiring with a portion extending in a straight line. A wiring structure with a multilayer structure can be formed on the wiring layer including the first conductor portion 5A and the second conductor portion 5B by forming additional wiring layers.

[0031] The method of the present invention is not limited to the above examples and can be modified as needed. For example, the substrate 1 may have a base and a substrate protrusion, the base having a flat surface along a surface including a first bottom surface 11a and a second bottom surface 12a, the substrate protrusion being disposed on the flat surface side of the base, and the substrate protrusion being a resist layer. In this case, the resist layer (substrate protrusion 2B) has a pattern including an opening along the first wall surface 11b and an opening along the second wall surface 12b. After the first conductor portion 5A and the second conductor portion 5B are formed, the resist layer (substrate protrusion 2B) can be removed.

[0032] The photosensitive resist layer used to form the temporary protective layer 7 with a prescribed pattern can, for example, be a layer formed from a photosensitive resin composition comprising an adhesive polymer, a photopolymerizable compound having olefinic unsaturated bonds, and a photopolymerization initiator.

[0033] The adhesive polymer may be, for example, benzyl (meth)acrylate or its derivatives, styrene or styrene derivatives, alkyl (meth)acrylates, and copolymers containing (meth)acrylate as monomer units.

[0034] Specific examples of benzyl methacrylate derivatives constituting adhesive polymers include 4-methylbenzyl methacrylate, 4-ethylbenzyl methacrylate, 4-tert-butylbenzyl methacrylate, 4-methoxybenzyl methacrylate, 4-ethoxybenzyl methacrylate, 4-hydroxybenzyl methacrylate, and 4-chlorobenzyl methacrylate.

[0035] Specific examples of styrene derivatives that constitute adhesive polymers include vinyltoluene, p-methylstyrene, and p-chlorostyrene.

[0036] The alkyl (meth)acrylates constituting the adhesive polymer can be ester compounds formed from (meth)acrylic acid and aliphatic alcohols with 1 to 12 carbon atoms, either linear or branched. The aliphatic alcohols can have 1 to 8 or 1 to 4 carbon atoms. Specific examples of alkyl (meth)acrylates include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, tert-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate.

[0037] Based on the mass of the adhesive polymer, the proportion of monomer units derived from benzyl (meth)acrylate or its derivatives in the adhesive polymer can be 50–80% by mass, 50–75% by mass, 50–70% by mass, or 50–65% by mass. Based on the mass of the adhesive polymer, the proportion of monomer units derived from styrene or styrene derivatives in the adhesive polymer can be 5–40% by mass, or 5–35% by mass. Based on the mass of the adhesive polymer, the proportion of monomer units derived from alkyl (meth)acrylates in the adhesive polymer can be 1–20% by mass, 1–15% by mass, 1–10% by mass, or 1–5% by mass. Based on the mass of the adhesive polymer, the proportion of monomer units derived from (meth)acrylic acid in the adhesive polymer can be 5–30% by mass, 5–25% by mass, or 10–25% by mass.

[0038] The weight-average molecular weight (Mw) of the adhesive polymer can be 20,000–150,000, 30,000–100,000, 40,000–80,000, or 40,000–60,000. Here, the weight-average molecular weight refers to the standard polystyrene conversion value obtained by gel permeation chromatography (GPC).

[0039] The acid value (mgKOH / g) of the adhesive polymer can be 13–78, 39–65, or 52–62. Here, the acid value refers to the amount (mg) of potassium hydroxide required to neutralize 1g of the adhesive polymer.

[0040] Specific examples of photopolymerizable compounds having olefinically unsaturated bonds include bisphenol A-based (meth)acrylate compounds, hydrogenated bisphenol A-based (meth)acrylate compounds, polyalkylene glycol (meth)acrylates, urethane monomers, pentaerythritol (meth)acrylates, and trimethylolpropane (meth)acrylates. They can be used alone or in combination of two or more. Bisphenol A-based di(meth)acrylate compounds can be, for example, compounds represented by the following general formula (1).

[0041] In formula (1), R independently represents a hydrogen atom or a methyl group. EO and PO represent oxyethylene and oxypropylene groups, respectively. m1, m2, n1, and n2 independently represent 0–40, m1+m2 is 1–40, and n1+n2 is 0–20. Either EO or PO can be located on the phenolic hydroxyl side. m1, m2, n1, and n2 represent the quantity of EO or PO, respectively. Compounds with an average m1+m2 value of less than 5 and compounds with an average m1+m2 value of 6–40 can be combined.

[0042] Polyalkylene glycol (meth)acrylates can be compounds represented by the following formula (2). As photopolymerizable compounds with olefinic unsaturated bonds, bisphenol A-based di(meth)acrylate compounds and compounds represented by the following formula (2) can be combined.

[0043] In equation (2), R 14 and R 15 Each can be used independently to represent a hydrogen atom or a methyl group; EO and PO have the same meaning as described above. 1 Indicates 1 to 30, r 1 and r 2 Representing 0 to 30 respectively, r 1 +r 2 The values ​​range from 1 to 30. As an example of a commercially available product representing the compound indicated by formula (2), R can be cited. 14 and R 15 Methyl, r1 +r 2 =4 (average), s 1 =12 (average) vinyl compound (manufactured by HitachiKasei Kogyo Kabushiki Kaisha, product name: FA-023M).

[0044] Specific examples of photopolymerization initiators include benzophenone, N,N'-tetramethyl-4,4'-diaminobenzophenone (Mischel ketone), N,N'-tetraethyl-4,4'-diaminobenzophenone, 4-methoxy-4'-dimethylaminobenzophenone, 2-benzyl-2-dimethylamino-1-(4-morpholinylphenyl)-butanone-1, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinyl-acetone-1, and other aromatic ketones; quinones such as 2-ethylanthraquinone, phenanthrenequinone, 2-tert-butylanthraquinone, octamethylanthraquinone, 1,2-benzanthraquinone, 2,3-benzanthraquinone, 2-phenylanthraquinone, 2,3-diphenylanthraquinone, 1-chloroanthraquinone, 2-methylanthraquinone, 1,4-naphthoquinone, 9,10-phenanthrenequinone, 2-methyl1,4-naphthoquinone, and 2,3-dimethylanthraquinone. Classes include: benzoin ether compounds such as benzoin methyl ether, benzoin ethyl ether, and benzoin phenyl ether; benzoin compounds such as benzoin, methyl benzoin, and ethyl benzoin; benzyl derivatives such as benzyl dimethyl ketal; 2,4,5-triaryl imidazole dimers such as 2-(o-chlorophenyl)-4,5-diphenylimidazolium dimer, 2-(o-chlorophenyl)-4,5-di(methoxyphenyl)imidazolium dimer, 2-(o-fluorophenyl)-4,5-diphenylimidazolium dimer, 2-(o-methoxyphenyl)-4,5-diphenylimidazolium dimer, and 2,4,5-triarylimidazolium dimer; acridine derivatives such as 9-phenylacridinium and 1,7-bis(9,9'-acridyl)heptane; N-phenylglycine; N-phenylglycine derivatives; and coumarin compounds. These can be used alone or in combination of two or more. Photopolymerization initiators may contain 2,4,5-triarylimidazolium dimers, and more particularly may contain 2-(o-chlorophenyl)-4,5-diphenylimidazolium dimers.

[0045] Relative to 100 parts by weight of the adhesive polymer and photopolymerizable compound, the content of the adhesive polymer in the photosensitive resin composition may be 40-80 parts by weight, 45-75 parts by weight, or 50-70 parts by weight. Relative to 100 parts by weight of the adhesive polymer and photopolymerizable compound, the content of the photopolymerization initiator in the photosensitive resin composition may be 0.01-5 parts by weight, 0.1-4.5 parts by weight, or 1-4 parts by weight.

[0046] The photosensitive resin composition may include other components as needed. Examples of other components include photopolymerizable compounds with cationic polymerizable cyclic ether groups, cationic polymerization initiators, sensitizers, dyes such as malachite green, photochromic agents such as tribromomethylbenzene sulfone and colorless crystal violet, thermochromic inhibitors, plasticizers such as p-toluenesulfonamide, pigments, fillers, defoamers, flame retardants, stabilizers, adhesion promoters, leveling agents, peel accelerators, antioxidants, fragrances, imaging agents, and thermocrosslinking agents. The content of other components may be approximately 0.01 to 20 parts by weight, respectively, relative to 100 parts by weight of the adhesive polymer and the photopolymerizable compound.

[0047] The total content of the binder polymer, photopolymerizable compound and photopolymerization initiator in the photosensitive resin composition may be 90-100% by mass or 95-100% by mass relative to the total mass of the components other than the solvent in the photosensitive resin composition.

[0048] To form a photosensitive resist layer, a resist film containing a photosensitive resin composition can be laminated onto the main surface S1 of the substrate 1, or a photosensitive resin composition containing a solvent can be coated onto the main surface S1 of the substrate 1 and the solvent can be removed from the coating.

[0049] Symbol Explanation 1-Substrate, 2-Substrate body, 3-Seed layer, 5-Conductor layer, 5A-First conductor, 5B-Second conductor, 7-Temporary protective layer, 7a-Opening, 11-First recess, 11a-First bottom surface, 11b-First wall surface, 12-Second recess, 12a-Second bottom surface, 12b-Second wall surface, 50-Wiring structure, 51-First metal plating, 52-Second metal plating, W1-Minimum width of the first bottom surface, W2-Minimum width of the second bottom surface.

Claims

1. A method for manufacturing a wiring structure, comprising the following steps: The step of preparing a substrate, wherein the substrate is a substrate having a main surface having a first recess and a second recess formed thereon, wherein, The first recess has a first bottom surface and a first wall surface, and the second recess has a second bottom surface and a second wall surface. The minimum width of the first bottom surface is greater than the minimum width of the second bottom surface. The step of forming a temporary protective layer on the main surface of the substrate, the temporary protective layer having a pattern including an opening that exposes at least a portion of the first bottom surface, and including a portion that blocks the second recess; The step of forming a first metal plating layer on the first bottom surface exposed within the opening; The step of removing the temporary protective layer to expose the second recess; The step of forming a conductor layer comprising the first metal plating layer and the second metal plating layer by forming a second metal plating layer, wherein the second metal plating layer comprises a portion filling the second recess and a portion disposed on the first metal plating layer; and The steps of forming a first conductor portion disposed within the first recess and including the first metal plating layer and the second metal plating layer, and a second conductor portion disposed within the second recess and including the second metal plating layer, by removing a portion of the conductor layer. The substrate includes a seed layer, the seed layer having a surface comprising the first bottom surface and the second bottom surface. The first metal coating and the second metal coating are formed by electroplating.

2. The method according to claim 1, wherein, The substrate further comprises an insulating layer having a pattern including an opening along the first wall and an opening along the second wall.

3. The method according to claim 1, wherein, The first metal coating is formed by creating a recess on the surface of the first metal coating that is opposite to the first bottom surface.

4. The method according to claim 1, wherein, The steps for forming the temporary protective layer include: The step of forming a photosensitive resist layer on the main surface of the substrate; and The step of forming the temporary protective layer having the pattern by exposing and developing the photosensitive resist layer.

5. The method according to claim 4, wherein, The photosensitive resist layer comprises an adhesive polymer, a photopolymerizable compound having olefinic unsaturated bonds, and a photopolymerization initiator.

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