JP2017157598A - Wiring board and manufacturing method for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique of suppressing the separation of a metal oxide layer or a metal wiring layer from a substrate.SOLUTION: A wiring board includes a substrate formed of glass or ceramic, a metal oxide layer formed on the substrate, and a metal wiring layer formed on the metal oxide layer. When the wiring board is viewed along a cross section, the metal oxide layer is formed to be narrower than the metal wiring layer, and a glass layer formed between the substrate and the metal wiring layer in contact with a side surface of the metal oxide layer is provided.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a wiring board and a manufacturing method thereof.

  Conventionally, as a wiring substrate used for an IC package substrate, an interposer, or the like, a wiring substrate including a metal oxide layer and a metal wiring layer in this order on the substrate is known (for example, Patent Document 1). Patent Document 1 discloses a method in which after a metal oxide layer is patterned, a metal wiring layer is formed on the metal oxide layer by electroless copper plating.

JP 2003-213436 A

  However, in the metal wiring layer forming method described in Patent Document 1, the dimensional accuracy of the metal wiring layer is low. Therefore, in order to increase the dimensional accuracy of the metal wiring layer, it is preferable to perform patterning by wet etching after laminating the metal wiring layer on the metal oxide layer.

  When wet etching is performed after the metal wiring layer is stacked on the metal oxide layer, the metal oxide layer having an etching rate higher than that of the metal wiring layer is preferentially etched. As a result, there is a possibility that a gap is generated between the metal wiring layer and the substrate. Then, due to this gap, the adhesion area between the substrate and the metal oxide layer and the adhesion area between the metal oxide layer and the metal wiring layer are reduced, and the metal wiring layer and the metal oxide layer may be peeled off from the substrate. In particular, when liquid or gas enters the gap and receives heat in that state, the intruded liquid or gas expands, which may cause the metal wiring layer or metal oxide layer to peel off from the substrate.

  The present invention has been made to solve the above-described problems, and can be realized as the following forms.

(1) According to one aspect of the present invention, a wiring board is provided. This wiring board is a wiring board comprising a substrate formed of glass or ceramic, a metal oxide layer formed on the substrate, and a metal wiring layer formed on the metal oxide layer. When the wiring board is viewed in cross-section, the metal oxide layer is narrower than the metal wiring layer and is formed between the substrate and the metal wiring layer, and the metal oxide layer It is characterized by comprising a glass layer in contact with the side surface of. According to the wiring board of this form, by providing the glass layer, it is possible to prevent the metal oxide layer and the metal wiring layer from being peeled from the board.

(2) In the wiring board of the above aspect, the glass layer may be in contact with at least a part of the side surface of the metal wiring layer. According to the wiring board of this form, the adhesion between the board and the metal wiring layer can be improved.

(3) In the wiring board of the above aspect, the metal wiring layer may include at least one selected from the group consisting of copper, nickel, and silver. According to the wiring board of this form, the conductivity can be improved.

(4) In the wiring board of the above aspect, the metal oxide layer may be an oxide layer including at least one selected from the group consisting of zinc, titanium, tin, and chromium. According to this form of the wiring substrate, the adhesion between the substrate and the metal oxide layer can be improved.

(5) According to the other form of this invention, the manufacturing method of a wiring board is provided. This method for manufacturing a wiring board includes a substrate formed of glass or ceramic, a metal oxide layer formed on the substrate, and a metal wiring layer formed on the metal oxide layer, When viewed, a preparation step of preparing a core substrate in which the metal oxide layer is narrower than the metal wiring layer, and between the substrate and the metal wiring layer, and the metal oxide A glass layer forming step of forming a glass layer so as to be in contact with the side surface of the layer. According to the method for manufacturing a wiring board of this aspect, by providing the glass layer, it is possible to prevent the metal oxide layer and the metal wiring layer from being peeled from the board.

  In addition, this invention is not restricted to the form as a wiring board and the manufacturing method of a wiring board mentioned above, It is realizable in various forms. The present invention can be realized, for example, in the form of an electric device including a wiring board.

Explanatory drawing of the wiring board of this embodiment. Process drawing which shows the manufacturing method of a wiring board. The figure explaining a preparatory process. The figure explaining a glass layer formation process. The figure for demonstrating the case where a glass layer formation process is performed after a roughening process.

A. Embodiment:
A1. Wiring board configuration:
FIG. 1 is an explanatory diagram of the wiring board 10 of the present embodiment. The wiring board 10 of this embodiment is used as an IC package board or an interposer, for example. As shown in FIG. 1, the wiring substrate 10 includes a substrate 100, a metal oxide layer 110, a metal wiring layer 120, a plating layer 130, and a glass layer 140. FIG. 1 shows a part of the wiring board 10.

  In the present embodiment, the substrate 100 is made of alkali-free glass having a 300 mm square and a thickness of 0.3 mm. In the present embodiment, the substrate 100 is not formed with a through hole, but the substrate 100 may be formed with a through hole. In the present embodiment, the substrate 100 is made of glass, but the substrate 100 may be made of ceramic.

  The metal oxide layer 110 is a layer formed of a metal oxide and is formed on the substrate 100. The metal oxide layer 110 is preferably made of a material having high adhesion to the substrate 100. For example, at least one selected from the group consisting of zinc (Zn), titanium (Ti), tin (Sn), and chromium (Cr). It is preferable that the oxide layer contains two. In the present embodiment, the metal oxide layer 110 is formed of zinc oxide (ZnO). In the present embodiment, the thickness of the metal oxide layer 110 is about 100 nm.

  The metal wiring layer 120 is a layer formed of metal and is used for wiring. The metal wiring layer 120 is formed on the metal oxide layer 110. The metal wiring layer 120 includes a seed layer 122 and a plating layer 125 in order from the layer in contact with the metal oxide layer 110. The metal wiring layer 120 is preferably formed of a highly conductive metal, and preferably includes at least one selected from the group consisting of copper (Cu), nickel (Ni), and silver (Ag), for example. . In the present embodiment, the metal wiring layer 120 is formed of copper (Cu).

  When the wiring substrate 10 is viewed in cross-section by etching in a preparatory step (step P100) described later, that is, in a cross section perpendicular to the direction in which the metal wiring layer 120 extends on the substrate 100, the metal oxide layer 110 is better. The width is narrower than the metal wiring layer 120. As a result, a gap is generated between the substrate 100 and the metal wiring layer 120. Note that “when the wiring substrate 10 is viewed in cross section” indicates a case where the wiring substrate 10 is viewed on a cross section perpendicular to the direction in which the metal wiring layer 120 extends on the substrate 100. The “width” indicates a dimension in a direction perpendicular to the direction in which the metal oxide layer 110 is stacked on the metal wiring layer 120 when viewed in cross section.

  The plating layer 130 is a layer formed of metal and is used for wiring. The plating layer 130 covers the metal wiring layer 120. In the present embodiment, the plating layer 130 is formed of a layer formed of nickel (Ni), a layer formed of palladium (Pd), and gold (Au) in order from the layer in contact with the metal wiring layer 120. And a layer.

  The glass layer 140 is formed between the substrate 100 and the metal wiring layer 120 and is in contact with the side surface of the metal oxide layer 110. Here, that the glass layer 140 is in contact with the side surface of the metal oxide layer 110 indicates that at least a part of the glass layer 140 is in contact with the side surface of the metal oxide layer 110. In the present embodiment, the glass layer 140 is also in contact with a part of the side surface of the metal wiring layer 120.

  The glass layer 140 is made of glass. In the present embodiment, the glass layer 140 is made of polysilazane. In this embodiment, the thermal expansion coefficient of the glass layer 140 is about 3 ppm / ° C. to about 6 ppm / ° C.

A2. Manufacturing method of wiring substrate 10:
FIG. 2 is a process diagram showing a method for manufacturing the wiring board 10. The manufacturer of the wiring substrate 10 first prepares the core substrate 10A including the metal oxide layer 110 and the metal wiring layer 120 on the substrate 100 in the process P100. Process P100 is also called a preparation process.

  In the present embodiment, in the preparation process, the manufacturer forms the metal oxide layer 110 and the metal wiring layer 120 on the substrate 100. Examples of a method for forming the metal oxide layer 110 and the metal wiring layer 120 include a subtractive method and a semi-additive method. In the present embodiment, a subtractive method is used as a method for forming the metal oxide layer 110 and the metal wiring layer 120.

  FIG. 3 is a diagram illustrating the preparation process (process P100). Specifically, the manufacturer first forms a zinc oxide (ZnO) layer 110A to be the metal oxide layer 110 on the substrate 100, and then seeds the layer 110A by electroless copper plating. A layer 122A to be the layer 122 is formed (see FIG. 3A). Examples of the method for forming the layer 110A include a MOD (Metal Organic Decomposition) method, a sol-gel method, a CVD (Chemical Vapor Deposition) method, a sputtering method, and a screen printing method. . In the present embodiment, the MOD method is used as a method for forming the layer 110A.

  Next, the manufacturer forms a layer 125A to be the plated layer 125 on the layer 122A by electrolytic copper plating (see FIG. 3B). Thereafter, the manufacturer forms a pattern 160 using a dry film resist on the layer 125A, and performs wet etching. FIG. 3C shows a state where the layer 125A is etched by wet etching. After removing unnecessary layers 110A, 122A, and 125A whose upper portions are not covered with the pattern 160 by wet etching, the manufacturer removes the pattern 160, thereby allowing the manufacturer to remove the substrate 100, the metal oxide layer 110, and the metal wiring. A core substrate 10A including the layer 120 is obtained (see FIG. 3D).

  As shown in FIG. 3D, the core substrate 10 </ b> A is narrower in the metal oxide layer 110 than in the metal wiring layer 120 when viewed in cross section. The reason for this is that the metal oxide layer 110 is preferentially etched over the metal wiring layer 120 because the metal oxide layer 110 has a higher etching rate than the metal wiring layer 120 due to the above-described wet etching. A point is mentioned.

  Thus, the preparation process (process P100) is completed. In the present embodiment, the core substrate 10A is manufactured, but a core substrate 10A manufactured in advance may be used.

  After the preparatory process (process P100) (see FIG. 2), the manufacturer uses glass so as to be in contact with the side surface of the metal oxide layer 110 between the substrate 100 and the metal wiring layer 120 in process P110. Layer 140 is formed. Process P110 is also called a glass layer forming process.

  FIG. 4 is a diagram for explaining the glass layer forming step (step P110). In the glass layer forming process (process P110), the manufacturer first applies a coating material 140A containing polysilazane to the surface of the core substrate 10A including the metal wiring layer 120. Next, the manufacturer bakes the coating material 140A onto the core substrate 10A by performing heat treatment. FIG. 4A shows a state in which the coating material 140A is baked on the core substrate 10A.

  Thereafter, the manufacturer removes unnecessary coating material 140A existing on the metal wiring layer 120 by performing reactive ion etching. Thus, the glass layer forming process (process P110) is completed. FIG.4 (b) shows the state of the glass layer 140 after a glass layer formation process (process P110). In this step, instead of using reactive ion etching, wet etching with hydrofluoric acid (HF) may be used, or a laser may be used.

  The adhesion amount of the coating material 140A below the side surface of the metal wiring layer 120 is thicker than the adhesion amount on the surface of the substrate 100 due to the surface tension of the coating material 140A. Therefore, even after the reactive ion etching described above, the metal wiring layer 120. A part of the glass layer 140 below the side surface remains.

  When the coating material 140A is applied, the coating material 140A enters the gap between the substrate 100 and the metal wiring layer 120 and contacts the side surface of the metal oxide layer 110. From the viewpoint of efficiently infiltrating the coating material 140A through the gap between the substrate 100 and the metal wiring layer 120, the coating material 140A is preferably a liquid type.

  Further, when the coating material 140 </ b> A is applied, the coating material 140 </ b> A adheres also on the lower side of the side surface of the metal wiring layer 120 due to the surface tension of the coating material 140 </ b> A. For this reason, as shown in FIG. 4, the glass layer 140 is also in contact with part of the metal wiring layer 120.

  After the glass layer forming process (process P110) (see FIG. 2), the manufacturer performs a roughening process on the surface of the metal wiring layer 120 in process P120. In the present embodiment, wet etching is used as the roughening method. Through this step, the surface of the metal wiring layer 120 becomes rough, and the adhesion between the metal wiring layer 120 and the plating layer 130 formed in the next step can be improved.

  After the surface roughening process (process P120) of the metal wiring layer 120, the manufacturer forms a plating layer 130 that covers the metal wiring layer 120 in process P130. Process P130 is also referred to as a plating layer forming process. Through these steps, the wiring board 10 is completed.

  The wiring substrate 10 of this embodiment includes a glass layer 140 that is formed between the substrate 100 and the metal wiring layer 120 and that contacts the side surface of the metal oxide layer 110. For this reason, according to the wiring board 10 of this embodiment, the clearance gap between the board | substrate 100 and the metal wiring layer 120 can be filled. As a result, gas or liquid can be prevented from entering the gap. In addition, since the glass layer 140 is in close contact with the metal wiring layer 120, the metal wiring layer 120 and the metal oxide layer 110 can be prevented from being peeled from the substrate 100. As a result, the yield of the wiring board 10 can be improved.

  Further, in the wiring substrate 10 of the present embodiment, the glass layer 140 is also in contact with part of the side surface of the metal wiring layer 120. For this reason, compared with the case where the glass layer 140 does not contact the side surface of the metal wiring layer 120, the adhesiveness between the glass layer 140 and the metal wiring layer 120 is improved. As a result, it is possible to effectively suppress the metal wiring layer 120 and the metal oxide layer 110 from being peeled off from the substrate 100.

  In the manufacturing method of the wiring board 10 of this embodiment, a glass layer formation process (process P110) is performed before a roughening process (process P120). On the other hand, when the glass layer forming step is performed after the roughening treatment, the following may occur.

  FIG. 5 is a diagram for explaining a case where a glass layer forming step is performed after the roughening treatment. FIG. 5A shows the core substrate 10A before the roughening process. When the core substrate 10A undergoes the roughening process, the metal oxide layer 110 and the seed layer 122 are scraped as shown in FIG. Therefore, the width of the metal oxide layer 110 after the roughening treatment shown in FIG. 5B is further narrower than the width of the metal oxide layer 110 before the roughening treatment shown in FIG. . As a result, the metal wiring layer 120 may be peeled off from the substrate 100 as shown in FIG.

  For this reason, according to the manufacturing method of the wiring board 10 of this embodiment, compared with the case where a glass layer formation process is performed after a roughening process, the glass layer 140 covers the circumference | surroundings of the metal oxide layer 110, It is possible to suppress the metal oxide layer 110 from being scraped by the roughening treatment.

  In the wiring board 10 of this embodiment, the thermal expansion coefficient of the glass layer 140 is about 3 ppm / ° C. to about 6 ppm / ° C. Therefore, the difference in thermal expansion between the glass layer 140 and the substrate 100 is small as compared with an epoxy resin having a high coefficient of thermal expansion. As a result, it is possible to prevent the substrate 100 from being peeled off from the metal wiring layer 120 when a thermal shock is applied to the wiring substrate 10 due to the difference in thermal expansion.

  In the preparation process (process P110), the metal used for the metal oxide layer 110 and the metal wiring layer 120 may remain unintentionally on the surface of the substrate 100. However, in the method for manufacturing the wiring substrate 10 of the present embodiment, the glass layer 140 covers the surface of the substrate 100 in the glass layer forming step (step P110). For this reason, it is possible to suppress the occurrence of a leakage current due to the deposition of the metal on the surface of the substrate 100 unintentionally remaining in the plating layer forming step (step P130), and the short circuit of the wiring substrate 10. .

  The metal oxide layer 110 of the wiring board 10 of this embodiment is an oxide layer including at least one selected from the group consisting of zinc (Zn), titanium (Ti), tin (Sn), and chromium (Cr). . For this reason, the adhesiveness of the board | substrate 100 and the metal oxide layer 110 can be improved. In addition, the metal wiring layer 120 of the wiring board 10 includes at least one selected from the group consisting of copper (Cu), nickel (Ni), and silver (Ag). For this reason, the conductivity of the wiring board 10 can be improved. In addition, the wiring board 10 includes a glass layer 140. Therefore, as a result of combining the metal oxide layer 110 and the metal wiring layer 120 listed above, even if a gap between the substrate 100 and the metal wiring layer 120 caused by wet etching is likely to occur, the metal wiring layer It is possible to effectively prevent the 120 and the metal oxide layer 110 from being peeled off from the substrate 100.

B. Variations:
B1. Modification 1:
In the above-described embodiment, a subtractive method is used as a method for forming the metal oxide layer 110 and the metal wiring layer 120. However, it is not limited to this. As a method for forming the metal oxide layer 110 and the metal wiring layer 120, a semi-additive method may be used. Note that the subtractive method is preferable because the wiring substrate 10 having good adhesion between the metal oxide layer 110 and the metal wiring layer 120 can be formed as compared with the semi-additive method.

  Further, as the seed layer 122, a copper sputtered film using titanium (Ti), chromium (Cr), or nickel (Ni) as an adhesion layer may be used instead of electroless copper plating. In this case, since it is necessary to use an etchant different from the etchant used for wet etching of copper for removing the adhesion layer, a gap tends to be easily formed between the substrate 100 and the metal wiring layer 120. However, since the wiring substrate 10 of the present embodiment includes the glass layer 140, the metal wiring layer 120 and the metal oxide layer 110 can be prevented from being peeled off from the substrate 100.

B2. Modification 2:
In the above-described embodiment, the wiring board 10 includes the metal oxide layer 110 and the metal wiring layer 120 one by one. However, the present invention is not limited to this. The wiring substrate 10 may include a plurality of metal oxide layers 110 and metal wiring layers 120 on the substrate 100, for example.

B3. Modification 3:
In the above-described embodiment, the glass layer 140 is made of polysilazane. However, the present invention is not limited to this. The glass layer 140 may be formed of, for example, polysiloxane or polysilane.

B4. Modification 4:
In the above-described embodiment, the plating layer 130 is formed of a layer formed from nickel (Ni), a layer formed from palladium (Pd), and gold (Au) in order from the layer in contact with the metal wiring layer 120. A layer. However, the present invention is not limited to this. The plated layer 130 may include, for example, a layer formed from nickel (Ni) and a layer formed from gold (Au) in order from the layer in contact with the metal wiring layer 120.

B5. Modification 5:
In the above-described embodiment, the glass layer 140 is in contact with a part of the side surface of the metal wiring layer 120. However, the present invention is not limited to this. The glass layer 140 may be in contact with the entire side surface of the metal wiring layer 120 or may not be in contact with the side surface of the metal wiring layer 120.

B6. Modification 6:
In the above-described embodiment, the glass layer 140 is formed by baking after the coating material 140A is applied. However, the present invention is not limited to this. The glass layer 140 may be formed by CVD.

  The present invention is not limited to the above-described embodiments and modifications, and can be realized with various configurations without departing from the spirit thereof. For example, the technical features in the embodiments and the modifications corresponding to the technical features in each form described in the summary section of the invention are to solve some or all of the above-described problems, or In order to achieve part or all of the effects, replacement or combination can be performed as appropriate. Further, if the technical feature is not described as essential in the present specification, it can be deleted as appropriate.

DESCRIPTION OF SYMBOLS 10 ... Wiring board 10A ... Core board 100 ... Board 110 ... Metal oxide layer 110A ... Layer 120 ... Metal wiring layer 122 ... Seed layer 122A ... Layer 125 ... Plating layer 125A ... Layer 130 ... Plating layer 140 ... Glass layer 140A ... Coat Material 160 ... Pattern

Claims (5)

A substrate made of glass or ceramic;
A metal oxide layer formed on the substrate;
A wiring board comprising a metal wiring layer formed on the metal oxide layer,
When the wiring board is viewed in cross section, the metal oxide layer is narrower than the metal wiring layer,
A wiring substrate comprising a glass layer formed between the substrate and the metal wiring layer and in contact with a side surface of the metal oxide layer. The wiring board according to claim 1,
The wiring substrate according to claim 1, wherein the glass layer is in contact with at least a part of a side surface of the metal wiring layer. The wiring board according to claim 1 or 2,
The wiring board according to claim 1, wherein the metal wiring layer includes at least one selected from the group consisting of copper, nickel, and silver. The wiring board according to any one of claims 1 to 3, wherein
The wiring board according to claim 1, wherein the metal oxide layer is an oxide layer including at least one selected from the group consisting of zinc, titanium, tin, and chromium. A method for manufacturing a wiring board, comprising:
A substrate formed of glass or ceramic; a metal oxide layer formed on the substrate; and a metal wiring layer formed on the metal oxide layer. A preparation step of preparing a core substrate having a narrower width than the metal wiring layer,
And a glass layer forming step of forming a glass layer between the substrate and the metal wiring layer and in contact with a side surface of the metal oxide layer. Method.

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