JP2011171528A - Manufacturing method of multilayer wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To firmly attach a plating metal layer on an insulating resin layer with a flat surface. <P>SOLUTION: The manufacturing method of multilayer wiring board includes (a) forming an insulating resin layer on a base structure equipped with base wiring, (b) arranging a particle which can form a hydroxyl group on an insulating resin layer surface and covering it with a protective resin film, (c) carrying out laser processing of a via hole penetrating through the protective resin film and insulating resin layer, and then reaching the base wiring, (d) removing smear by laser processing, (e) removing the protective resin film, (f) combining a coupling agent with a particle which can form the hydroxyl group, (g) carrying out electroless plating of a seed layer on the base wiring and insulating resin layer, and (h) carrying out electrolytic plating of a main wiring layer on the seed layer. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  Embodiments of the present invention relate to a method for manufacturing a multilayer wiring board in which wiring layers such as copper wiring and insulating resin layers such as epoxy resin are alternately laminated on a supporting substrate such as glass epoxy.

  In recent years, miniaturization of printed wiring boards, multilayering, and high-density mounting of electronic components have rapidly progressed, and a build-up multilayer wiring structure in which wiring layers are sequentially stacked has been actively studied.

  In the build-up multilayer wiring structure, an insulating layer is formed on the lower layer wiring, and a via hole which is a fine hole for connecting the lower layer wiring and the upper layer wiring is formed in the insulating layer. As a method for forming a via hole, a photosensitive resin (photoresist) layer is formed on an insulating layer, exposed and developed to form an opening corresponding to the via hole, and the insulating layer in the opening is etched. There is a method of forming a via hole by irradiating light. Since the photolithography technique using a photoresist is expensive, a method of forming a via hole using a laser beam is generally used.

  When the carbon dioxide laser is used, a via hole is formed in the insulating resin layer, and the exposed copper wiring can be left as it is without being cut. When a via hole is formed using laser light, a resin residue called smear remains at least at the bottom of the via hole. In order to remove smear, desmear treatment is performed using a permanganate solution such as potassium permanganate. Although smear may be formed on the insulating resin layer, when the desmear treatment is performed on the entire surface, the smear on the insulating resin layer is also removed together with the smear on the bottom surface of the via hole. The surface of the insulating resin layer can be sparse by the desmear treatment.

  As a method for forming patterned wiring, a metal layer is formed on the base, and unnecessary portions of the metal layer are removed by etching using a resist mask (subtract method). Forming a resist mask that covers the part, forming a wiring by electroless plating (additive method), forming a thin metal layer (seed layer) on the entire underlying surface, forming a resist mask that covers the unnecessary part, and electroplating A method (semi-additive method) is known in which after a wiring is formed, a resist mask is removed and a thin metal layer is removed by etching. A semi-additive method is suitable for fine wiring formation, and the resist mask is formed using a dry film resist.

  Copper having a low electrical resistivity and widely used as a wiring has extremely low adhesion to an epoxy resin generally used as an insulating resin. When fine irregularities are formed on the resin surface by desmear treatment, the copper wiring can be fixed to the resin surface by an anchoring force acting between the irregularities and the copper layer. When a filler such as silica is put in the resin, the surface roughness can be effectively obtained and the thermal expansion coefficient can be adjusted.

  The wiring width / interval is currently about 35 μm / 35 μm, but tends to be miniaturized, and wiring with a line / space (L / S) of 10 μm / 10 μm or less is also being studied. When a large roughness is formed on the surface of the resin layer by the desmear process, irregular reflection occurs during exposure of the resist layer for forming the wiring pattern, and fine wiring cannot be formed. In order to realize a wiring having a line / space (L / S) of 15 μm / 15 μm or less, it is desired to smooth the surface of the resin layer and increase the adhesion strength between the resin layer and the plated metal layer. It is conceivable that an adhesion layer having good adhesion to both the insulating resin layer and the plated metal layer is formed on the surface of the insulating resin layer having a flat surface, and the plated metal layer is formed on the adhesion layer.

  Japanese Patent Laid-Open No. 2003-273509 proposes that an adhesion film selected from a chromium oxide film, a mixed film containing chromium oxide, and a silane coupling agent film is interposed between an insulating layer and a wiring layer.

  Japanese Patent Laid-Open No. 2003-234573 discloses that a copper foil surface-treated with a coupling agent is hot-pressed on an insulating resin layer in a vacuum, and then the copper foil is etched away to transfer the coupling agent onto the insulating resin layer. Propose that.

  Japanese Patent No. 3277463 proposes treating an insulating surface before electroless plating with a silane coupling agent obtained by the reaction of an imidazole compound and an epoxy silane compound.

JP 2003-273509 A JP 2003-234573 A Japanese Patent No. 3277463

  A plated metal layer is firmly bonded onto an insulating resin layer having a flat surface.

According to one aspect of the present invention,
(A) forming an insulating resin layer on a base structure including a base wiring;
(B) Disposing particles capable of forming a hydroxyl group on the surface of the insulating resin layer and covering with a protective resin film;
(C) laser processing a via hole that penetrates the protective resin film and the insulating resin layer and reaches the base wiring;
(D) removing smear caused by the laser processing;
(E) removing the protective resin film;
(F) binding a coupling agent to the particles capable of forming the hydroxyl group,
(G) Electrolessly plating a seed layer on the underlying wiring and the insulating resin layer;
(H) electroplating a main wiring layer on the seed layer;
A method for manufacturing a multilayer wiring board is provided.

  The particles capable of forming a hydroxyl group firmly bond the coupling agent to the surface of the insulating resin layer.

When, 1A to 1L are cross-sectional views illustrating a method for manufacturing a multilayer wiring board according to Example 1, and FIG. 1M is a cross-sectional view illustrating the multilayer wiring board to be created. 2A-2B are cross-sectional views illustrating the method for manufacturing a multilayer wiring board according to the second embodiment.

  Silane coupling agents are often used to improve chemical adhesion between inorganic substances and organic resins. If the silane coupling agent can be bonded to the surface of the insulating resin layer, the plated metal layer may be firmly bonded to the insulating resin layer. However, it is not easy to effectively bond the silane coupling agent to the insulating resin layer.

  In order to bind the silane coupling agent to the insulating resin layer, the present inventors studied to bond particles capable of forming a hydroxyl group to the surface portion of the insulating resin layer. It can be expected that the hydroxyl group and the silane coupling agent are firmly bonded. Silica (silicon oxide) is well known as a substance capable of forming a hydroxyl group. Alumina (aluminum oxide) can also form a hydroxyl group. Furthermore, rubber particles capable of forming a hydroxyl group are also known.

  If particles containing these substances can be bound to the surface of the insulating resin layer, these particles will be able to bind the coupling agent strongly. In a desmear process or the like after forming a via hole with laser light, a protective resin layer may be disposed on the insulating resin layer so that the embedded particles are not removed. Via hole formation and desmear treatment using laser light are performed with the protective resin layer covering the insulating resin layer. Even after removing the protective resin layer, the hydroxyl group will remain on the surface of the insulating resin layer. For example, if particles are embedded in the surface of the insulating resin layer in a semi-cured state (so-called B stage) before curing (curing) and then the insulating resin layer is cured, the embedded particles and the insulating resin layer are strongly strengthened. It would be possible to combine.

  1A to 1L are cross-sectional views of a multilayer wiring board illustrating a wiring forming process according to the first embodiment.

  As shown in FIG. 1A, a thermosetting epoxy resin layer 13p in a semi-cured state (B stage) is laminated on the base structure 11 on which the wiring 12 is formed. The foundation structure 11 is a glass epoxy substrate, for example. In addition, it is good also considering the structure which forms a copper wiring and an insulating layer alternately on a glass epoxy board | substrate, and has wiring on the outermost surface as a base structure. In an actually experimented example, the wiring 12 is, for example, a copper wiring having a line / space of 10 μm / 10 μm, and the epoxy resin layer 13p in a thermosetting state is, for example, a trade name ABF- available from Ajinomoto Fine Techno Co., Ltd. GX-13 was an epoxy resin sheet having a thickness of 40 μm.

  As shown in FIG. 1B, a suspension 15 of silica particles is prepared, and the thermosetting epoxy resin layer 13p is immersed in the suspension 15. Silica particles 16 adhere to the surface of the thermosetting epoxy resin layer 13p. Silica particles are particles capable of forming hydroxyl groups on the surface. In the example, for example, silica particles having a trade name of Admafine SO-C3 and a particle size of 0.9 μm, which are available from Shin-Etsu Quartz, were used. The particle diameter of the particles capable of forming a hydroxyl group is preferably 1 μm or less in order to maintain the surface flatness of the epoxy resin layer.

  As shown in FIG. 1C, a polyethylene terephthalate (PET) film 17 is pressed and laminated as a protective resin layer on the thermosetting epoxy resin layer to which the silica particles 16 are adhered. It is considered that silica particles having a particle diameter of 1 μm are easily pushed into the semi-cured epoxy resin layer 13p. The thermosetting epoxy resin layer is cured by heating at 180 ° C. for 1 hour. The cured epoxy resin layer is indicated by 13.

  In the example, a Teijin Tetron film made by Teijin DuPont and having a thickness of 25 μm was used as the PET film. The heat treatment was performed by heating at 180 ° C. for 1 hour using a clean oven (Yamato Chemical Co., DT-41). The total thickness of the epoxy resin layer 13 and the PET film 17 is 65 μm when the sum is simply taken.

  As shown in FIG. 1D, a carbon dioxide laser beam L is irradiated to form a via hole 18 that penetrates the PET film 17 and the epoxy resin layer 13 and exposes the copper wiring 12. A via hole formed by a carbon dioxide laser forms a taper whose diameter decreases with depth. A smear 19 is generated at the bottom of the via hole 18. When a via hole is formed using a carbon dioxide laser, smear is a component equivalent to the resin in the via hole portion. Although mixing of epoxy and PET can occur, it is believed that almost no alteration occurs. The desmear process is a process capable of removing two types of resins.

  In the example, a via hole with an upper end diameter of 70 μm was formed in order to form a contact hole that penetrates a resin layer with a thickness of 40 μm and a PET film with a thickness of 25 μm and reaches a wiring with a width of 10 μm.

As shown in FIG. 1E, a desmear process such as the bottom surface of the via hole is performed by plasma P1 using a mixed gas of oxygen: CF ₄ = 95: 5. Incidentally, instead of the CF _4, or in addition to CF _4, it may be used SF _6. It is also possible to perform wet desmear treatment using a permanganate solution such as potassium permanganate.

  As shown in FIG. 1F, the laminated structure is heated to 150 ° C., and the PET film 17 is peeled off.

  As shown in FIG. 1G, surface treatment (light etching) of the epoxy resin layer 13 is performed by plasma P2 using oxygen gas, and particles 16 capable of forming hydroxyl groups are reliably exposed. When the particles 16 are covered with the epoxy resin 13, the epoxy resin 13 on the surface of the particles 16 is removed so that the particles 16 are exposed.

  It has been described that the particles capable of forming a hydroxyl group preferably have a diameter of 1 μm or less. However, when particles having a large particle diameter are used, the surface roughness of the surface of the insulating resin layer is increased in the light etching step shown in FIG. 1G. Resulting in.

  As shown in FIG. 1H, the laminated structure in which the particles 16 are exposed is immersed in a silane coupling agent 19 and surface-treated. The silane coupling agent 20 is bonded to the surface of the epoxy resin layer 13 through the particles 16 capable of forming a hydroxyl group. In the example, a 1 wt% aqueous solution of an amino silane coupling agent was used. For example, trade name KBM-903 available from Shin-Etsu Chemical Co., Ltd. was used.

  As shown in FIG. 1I, the laminated structure is immersed in an electroless copper plating solution 21, and a copper layer 22 as a seed layer is electrolessly plated on the epoxy resin layer 13 via a silane coupling agent. In the figure, the thickness is exaggerated. In the example, for example, an electroless copper plating solution available from Rohm and Haas was used as the electroless plating solution, and a 0.3 μm thick copper seed layer was electrolessly plated.

  As shown in FIG. 1J, a resist mask 23 is formed on the seed layer 22 using a dry film resist. After forming the resist mask, it is immersed in an electrolytic copper plating solution 24, and a current is passed between the counter electrode and the copper layer 25, which is the main wiring layer, is electroplated. In the example, a dry film resist having a trade name of RY3215 and a thickness of 15 μm available from Hitachi Chemical Co., Ltd. was used as the dry film resist, and the resist mask had a pattern of line / space = 10 μm / 10 μm. In addition, a copper sulfate plating solution in which copper sulfate, sulfuric acid, a brightener and the like were mixed as an electrolytic plating solution was used, and a copper layer having a thickness of 15 μm was electrolytically plated.

  As shown in FIG. 1K, the resist mask 23 of the dry film resist that defines the contour of the electroplating layer that is the main wiring layer is removed.

  As shown in FIG. 1L, the exposed electroless copper plating seed layer 22 is removed by wet etching using a (sulfuric acid + hydrogen peroxide) solution. Although the main wiring layer 25 formed of the same copper is also etched, since the seed layer is etched with a thickness of 0.3 μm, the reduction in the thickness of the main wiring layer can be suppressed within an allowable range. In this manner, an insulating resin layer having a via hole and a copper wiring layer having a desired pattern connected to the lower layer wiring are formed on the lower layer wiring.

  In the example, a copper wiring having a thickness of 15 μm and a line / space = 10 μm / 10 μm could be formed. Note that the seed layer can be etched dry.

  For comparison, a semi-cured epoxy resin layer was laminated on the base structure under the same conditions as in Example 1, no silica particle addition treatment was performed, no protective film was laminated, epoxy resin was cured, and laser light was used. Via hole formation and desmear treatment were performed. The surface roughness of the insulating resin layer after the desmear treatment was about 2 μm. Electroless plating, resist mask formation, and electrolytic plating processes were performed on this epoxy resin layer, but wiring with a line / space = 10 μm / 10 μm could not be formed.

  As shown in FIG. 1M, a multilayer wiring board is formed by stacking a plurality of wiring layers. In the figure, on a glass epoxy substrate 10, a first copper wiring layer W1, a first insulating resin layer R1, a second copper wiring layer W2, a second insulating resin layer R2, a third copper wiring layer W3, a third insulating resin. A layer R3, a fourth copper wiring layer W4, a fourth insulating resin layer R4, and a fifth copper wiring layer W5 are laminated. The upper layer wirings W2-W5 can be created according to the first embodiment. The number of stacked layers can be arbitrarily selected.

  In Example 1, particles capable of forming a hydroxyl group were adhered to the surface of the insulating resin layer, covered with a protective resin film, and pushed into the insulating resin layer. Particles capable of forming a hydroxyl group can be attached to the protective resin film, pressed against the insulating resin layer, and the particles capable of forming a hydroxyl group while being covered with the protective resin film can be pushed into the insulating resin layer.

  2A and 2B are cross-sectional views of the multilayer wiring board showing the wiring forming process according to the second embodiment.

  As shown in FIG. 2A, a PET film 14 that is a protective resin film is immersed in a silica particle suspension 15 to disperse the silica particles 16 on the surface, thereby forming a PET film having silica particles attached thereto. In the example, first, the surface of a PET film 14 having a thickness of 25 μm (cured) is supplied with oxygen gas to a Nikketsu plasma device (model number NVC-103) and subjected to plasma surface treatment at a power of 500 W for 3 minutes. It was. The PET film 14 whose surface was cleaned and activated by plasma treatment was immersed in the silica particle suspension 15 to attach the silica particles 16 to the surface. The PET film, the silica particle suspension, and the like are the same as in Example 1.

  As shown in FIG. 2B, a semi-cured thermosetting epoxy resin layer 13p is laminated on the base structure 11 on which the electrode 12 is formed. The PET film 14 with the silica particles 16 attached is pressed onto the epoxy resin layer 13p and laminated. The laminated structure is heated to cure the epoxy resin layer 13p. Then, the same process as the process shown in Example 1 and FIGS. 1D-1L is performed.

  In the example, the epoxy resin was cured by heating at 180 ° C. for 1 hour. A line / space = 10 μm / 10 mμm and a thickness of 15 μm could be formed.

  According to the above embodiment, it is possible to form a wiring with a wiring width and a wiring interval of 15 μm or less with high accuracy. The bottom surface of the wiring can be made flat.

  As the insulating resin layer, a semi-cured polyphenyl ether (PPE) resin layer (trade name: Megtron 6) available from Panasonic Electric Works could be used in place of the epoxy resin layer. In the example, a PPE resin layer in a semi-cured state and a PET film treated with silica particles are superposed on the base structure, and hot-pressed in vacuum at 200 ° C. for 1 hour under a pressure of 1.5 MPa to obtain silica particles. The PPE resin layer was pressed to cure the PPE resin. Thereafter, the same process as that shown in Example 1 and FIGS. 1D to 1L was performed, whereby a line / space = 10 μm / 10 mμm and a thickness of 15 μm could be formed.

  In addition, although epoxy and polyphenyl ether were used as the insulating (organic) resin, the insulating resin may be any insulating resin that can be laser processed, and is not limited thereto. In consideration of insulating properties, epoxy, polyimide, polyphenyl ether, Teflon and the like are preferable.

  The particles that can form a hydroxyl group can be expected not only to be silica particles but also to alumina particles to achieve the same effect. There is also the possibility of using rubber particles. Depending on the combination with the insulating resin layer, there is a possibility that particles capable of forming a hydroxyl group can be bonded after the insulating resin layer is cured.

  The protective resin film is removed and does not remain in the product. Although the case where the protective resin film is formed of PET has been described, any film that can be laser-processed and can withstand desmear treatment may be used. In the said Example, since the heat processing which hardens an insulating resin layer are performed after laminating | stacking a protective resin film, the heat resistance of heating temperature is required. In the case where particles capable of forming a hydroxyl group are bonded after the insulating resin layer is cured, the heat resistance requirement is relaxed. The protective resin layer may be a non-reactive film such as a PET film or a Teflon film, or may be a reactive film such as a dry film resist.

  As the coupling agent, an amino silane coupling agent having an amino group in the molecule is used, but other coupling agents can also be used. It is preferable to use a silane coupling agent containing at least one of amino group, mercapto group, epoxy group, imidazole group, vinyl group, dialkylamino group and pyridine group in the molecule.

  The wiring is preferably a copper wiring for low electrical resistance, but the electroless plating layer that serves as a seed layer for the electrolytic plating layer can be made thin and has little effect on the electrical resistance. Is possible. For example, nickel (Ni) or nickel-copper (Ni-Cu) alloy can also be used. The thickness of the seed layer is preferably 0.5 μm or less, and the thickness of the main wiring layer is preferably 10 μm or more.

The laser for processing the via hole can be other than a carbon dioxide laser such as a YAG laser. However, a carbon dioxide laser is preferable from the viewpoint of not damaging the copper wiring. When the desmear process is performed dry, it is preferable to perform dry etching using a gas containing at least one of CF ₄ and SF ₆ . After the protective film is peeled off, the treatment for surface-treating the insulating resin layer to expose the particles capable of forming a hydroxyl group is light etching, and is preferably performed by dry etching or ultraviolet irradiation.

  Although the present invention has been described with reference to the embodiments, the present invention is not limited thereto. It will be apparent to those skilled in the art that various modifications, substitutions, combinations, improvements, and the like can be made.

  The features of the present invention will be described below.

(Appendix 1)
(A) forming an insulating resin layer on a base structure including a base wiring;
(B) Disposing particles capable of forming a hydroxyl group on the surface of the insulating resin layer and covering with a protective resin film;
(C) laser processing a via hole that penetrates the protective resin film and the insulating resin layer and reaches the base wiring;
(D) removing smear caused by the laser processing;
(E) removing the protective resin film;
(F) binding a coupling agent to the particles capable of forming the hydroxyl group,
(G) Electrolessly plating a seed layer on the underlying wiring and the insulating resin layer;
(H) electroplating a main wiring layer on the seed layer;
A method for manufacturing a multilayer wiring board.

(Appendix 2)
The method for producing a multilayer wiring board according to appendix 1, wherein the insulating resin layer includes any one of epoxy resin, polyimide, and polyphenyl ether.

(Appendix 3)
(B) immersing the insulating resin layer in a semi-cured state in a suspension of the particles, pressing the protective resin layer on the insulating resin layer, and performing a thermosetting treatment of the insulating resin layer; A method for manufacturing a multilayer wiring board according to appendix 1 or 2.

(Appendix 4)
Supplement (1) or (2), wherein (b) immerses the protective resin layer in a suspension of the particles, presses the protective resin layer on the insulating resin layer, and performs a thermosetting treatment on the insulating resin layer. The manufacturing method of the multilayer wiring board as described.

(Appendix 5)
The manufacturing method of the multilayer wiring board of Additional remark 4 which said (b) immerses in the suspension liquid of the said particle | grain after carrying out plasma processing of the said protective resin layer.

(Appendix 6)
The method for producing a multilayer wiring board according to any one of appendices 1 to 5, wherein the protective resin layer is a material that does not change in the thermosetting treatment.

(Appendix 7)
Additional notes 1 to 6, wherein (c) includes carbon dioxide laser light, and (d) includes dry etching using at least one of CF ₄ and SF ₆ and oxygen, or wet etching using permanganate. The manufacturing method of the multilayer wiring board of any one of these.

(Appendix 8)
The multilayer wiring according to any one of appendices 1 to 7, wherein (f) performs light etching on the insulating resin layer by dry etching or ultraviolet irradiation, and then immerses the insulating resin layer in a coupling agent solution. A method for manufacturing a substrate.

(Appendix 9)
The particles capable of forming a hydroxyl group are any one of silica particles, alumina particles, and rubber particles having an average diameter of 1 μm or less, and the coupling agent is a silane coupling agent. A method for producing a multilayer wiring board according to claim 1.

(Appendix 10)
(G) is plated with a copper, nickel, or nickel alloy layer having a thickness of 0.5 μm or less as a seed layer, and (h) is a step of forming a resist mask on the seed layer. The method for producing a multilayer wiring board according to any one of appendices 1 to 9, wherein the main wiring layer of copper having a thickness of 10 μm or more is electrolytically plated.

11 Groundwork structure,
12 Wiring,
13 Insulating resin layer,
15 suspension,
16 particles capable of forming hydroxyl groups,
17 Protective resin film,
19 coupling agent solution,
20 coupling agent layer,
21 Electroless plating solution,
22 seed (electroless plating) layer,
24 Electrolytic plating solution,
25 Main wiring (electrolytic plating) layer,
L laser light,
P Plasma.

Claims (5)

(A) forming an insulating resin layer on a base structure including a base wiring;
(B) Disposing particles capable of forming a hydroxyl group on the surface of the insulating resin layer and covering with a protective resin film;
(C) laser processing a via hole that penetrates the protective resin film and the insulating resin layer and reaches the base wiring;
(D) removing smear caused by the laser processing;
(E) removing the protective resin film;
(F) binding a coupling agent to the particles capable of forming the hydroxyl group,
(G) Electrolessly plating a seed layer on the underlying wiring and the insulating resin layer;
(H) electroplating a main wiring layer on the seed layer;
A method for manufacturing a multilayer wiring board.   (B) immersing the insulating resin layer in a semi-cured state in a suspension of the particles, pressing the protective resin layer on the insulating resin layer, and performing a thermosetting treatment of the insulating resin layer; The manufacturing method of the multilayer wiring board of Claim 1.   The said (b) immerses the said protective resin layer in the suspension liquid of the said particle, presses the said protective resin layer on the said insulating resin layer, and performs the thermosetting process of the said insulating resin layer. Manufacturing method of multilayer wiring board. The (c) includes carbon dioxide laser light, and (d) includes dry etching using at least one of CF ₄ and SF ₆ and oxygen, or wet etching using permanganate. 4. The method for producing a multilayer wiring board according to any one of 3 above.   The particle capable of forming the hydroxyl group is any one of silica particles, alumina particles, and rubber particles having an average diameter of 1 µm or less, and the coupling agent is a silane coupling agent. A method for producing a multilayer wiring board according to claim 1.

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