Method for forming a through-via metal wiring

Abstract

To provide a method for forming through-via metal wiring with excellent plating quality without an expensive sputtering process.SOLUTION: A method for forming through-via metal wiring is disclosed. According to the method, the through-via metal wiring can be formed with excellent plating quality without an expensive sputtering process by bonding a metal foil to one side of a substrate having a through-via formed therein and using the foil as a metal seed layer.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a method for forming a through-via metal wiring, and more particularly, to a method for forming a through-via metal wiring with excellent plating quality without performing an expensive sputtering process.

Background Art

[0002] Glass is a substance widely used in various electronic devices such as displays, interposers, and sensors. These electronic devices can include vias that extend through the glass substrate in the thickness direction in order to transmit electrical signals from one main surface of the glass substrate to the other main surface of the glass substrate. The via can be filled with metal to form a through-glass via (TGV) metal wiring on the glass substrate. Such a through-glass via metal wiring can transfer electrical signals and power between a circuit network located on one surface of the glass substrate and a circuit network located on the other surface of the glass substrate.

[0003] A glass substrate having a through-glass via metal wiring is widely used, for example, as an interposer required for LSI (Large-Scale Integration) mounting technology. An interposer is a type of electronic component that forms vias in a substrate to connect chips to each other or to connect a chip and a printed circuit board (PCB) in order to mount or implement chips on the substrate. Conventionally, silicon has been used as the material for the interposer substrate, but recently, it is being replaced by glass, which has the advantages of being electrically non-conductive and inexpensive.

[0004] Conventional methods for forming through-via metal wiring on a glass substrate are as follows. As shown in FIG. 1, titanium (Ti) sputtering is performed on both sides of the glass substrate 10 to form a titanium metal layer 20 on both sides of the glass substrate and the side walls of the via hole 40. Then, copper (Cu) sputtering is performed on both sides of the glass substrate to form a copper seed layer 30 on the titanium metal layer. After that, the via hole is filled by electrolytic or electroless plating to form the through-via metal wiring 50.

[0005] However, such a method for forming through-via metal wiring has disadvantages in that it requires an expensive sputtering process and the process is complex. In addition, voids and seams are formed in the via hole due to the aspect ratio, hole size, and composition of the plating solution of the via hole, which causes problems such as deterioration of electrical characteristics or reliability of the device package.

[0006] Therefore, there is a need to develop a method that can form through-via metal wiring with excellent plating quality without performing an expensive sputtering process.

Summary of the Invention

Problems to be Solved by the Invention

[0007] An object of the present invention is to provide a method for forming through-via metal wiring with excellent plating quality without performing an expensive sputtering process.

Means for Solving the Problems

[0008] On the other hand, the present invention provides (i) a step of bonding a metal foil to one surface of a substrate having a through-via via an adhesive layer; (ii) a step of performing plasma treatment on the hole formed by the through-via and the metal foil to remove the adhesive layer located inside the hole; (iii) a step of filling the inside of the hole with metal by a plating process; and Provide a method for forming a through-via metal wiring, including the step of removing the metal foil and the adhesive layer with an etching solution.

[0009] The method for forming a through-via metal wiring according to an embodiment of the present invention may further include, after the step (iv), a step (v) of cleaning the substrate.

[0010] In one embodiment of the present invention, the substrate may be a glass substrate, a silicon substrate, or a ceramic substrate.

[0011] In one embodiment of the present invention, the metal foil may be a copper foil.

[0012] In one embodiment of the present invention, the metal foil may have a thickness of 3 to 1,000 μm.

[0013] In one embodiment of the present invention, the adhesive layer may be formed of one or more selected from the group consisting of an acrylic adhesive, a silicon adhesive, a polyurethane adhesive, and a rubber adhesive.

[0014] In one embodiment of the present invention, in the step (ii), the plasma treatment may be performed using O2, CF4, Ar, N2, He, SF4, NF3, or a mixed gas thereof.

[0015] In one embodiment of the present invention, in the step (iii), the plating process may be an electrolytic plating process performed by a bottom-up filling mechanism.

[0016] In one embodiment of the present invention, in the step (iii), the metal filled inside the hole may be copper (Cu).

[0017] In one embodiment of the present invention, in the step (iv), the etching solution may include one or more selected from the group consisting of copper chloride, iron chloride, hydrochloric acid, nitric acid, sulfuric acid, persulfate compounds, and hydrogen peroxide solution.

Advantages of the Invention

[0018] According to the method for forming a through-via metal wiring of the present invention, a through-via metal wiring can be formed with excellent plating quality by a bottom-up filling mechanism without performing an expensive sputtering process.

Brief Description of the Drawings

[0019]

Figure 1

Figure 2

Figure 3a

Figure 3b

Embodiments for Carrying Out the Invention

[0020] Hereinafter, the present invention will be described in more detail.

[0021] One embodiment of the present invention relates to a method for forming a through-via metal wiring.

[0022] A method for forming a through-via metal wiring according to an embodiment of the present invention is (i) a step of bonding a metal foil via an adhesive layer to one surface of a substrate on which a through via is formed; (ii) a step of performing plasma treatment on the hole formed by the through via and the metal foil to remove the adhesive layer located inside the hole; (iii) a step of filling the inside of the hole with metal by a plating process; and (iv) removing the metal foil and the adhesive layer with an etching solution.

[0023] The method for forming a through-via metal wiring according to an embodiment of the present invention can form a through-via metal wiring with excellent plating quality by a bottom-up filling mechanism without performing an expensive sputtering process.

[0024] Specifically explaining the method for forming a through-via metal wiring according to the present invention is as follows.

[0025] FIG. 2 is a cross-sectional view of the process of the method for forming a through-via metal wiring according to an embodiment of the present invention.

[0026] As shown in FIG. 2(a), the step (i) is a step of bonding a metal foil 3 to one surface of a substrate 1 in which a through-via is formed via an adhesive layer 2 to form a hole 4.

[0027] The substrate 1 may be a glass substrate, a silicon substrate, a ceramic substrate, etc., and particularly may be a glass substrate.

[0028] The substrate in which the through-via is formed may be manufactured by a method known in the art and used, or a commercially available product may be obtained and used.

[0029] For example, a glass substrate in which a glass through-via is formed may be formed by irradiating a glass substrate with UV or a carbon dioxide laser, or by forming fine holes in a photosensitive glass substrate and then etching with hydrofluoric acid, or by drilling the glass substrate with a pair of upper and lower core drills facing each other.

[0030] The glass substrate may be made of quartz glass, borosilicate glass, aluminosilicate glass, soda lime glass, titanium-containing silicate glass, or alkali-free glass.

[0031] In one embodiment of the present invention, the inner diameter of the through hole may be 2 to 300 μm. Through-hole metal wiring can be formed with excellent plating quality within the range of the inner diameter.

[0032] In one embodiment of the present invention, the thickness of the substrate may be appropriately selected according to the application, and for example, it may be 100 to 1,000 μm.

[0033] The metal foil serves as a seed metal layer for the plating process, and by using this, the sputtering process for forming another seed metal layer can be omitted.

[0034] The metal foil may contain one or more selected from the group consisting of copper (Cu), titanium (Ti), iron (Fe), chromium (Cr), aluminum (Al), nickel (Ni), and alloys thereof, and preferably may be a copper foil.

[0035] The metal foil may have a thickness of 3 to 1,000 μm, preferably 5 to 100 μm. When the thickness of the metal foil is less than 3 μm, workability may deteriorate in the application of the adhesive or the bonding process with the substrate, and when it exceeds 1,000 μm, uniform bonding with the substrate may become difficult.

[0036] The adhesive layer may be formed from one or more selected from the group consisting of acrylic adhesives, silicone adhesives, polyurethane adhesives, and rubber adhesives.

[0037] The adhesive layer may be formed by applying the adhesive to one surface of the metal foil and curing it.

[0038] The method of applying the adhesive is not particularly limited, and examples thereof include spray coating, bar coating, gravure coating, knife coating, air knife coating, curtain coating, die coater, and the like.

[0039] The adhesive may be cured by heat or light, and a suitable curing method may be selected according to the type of the adhesive.

[0040] When the adhesive is thermosetting, for example, heat curing may be performed by heating and drying at 40 to 200 °C, preferably 50 to 180 °C, more preferably 70 to 170 °C.

[0041] When the adhesive is photocurable, for example, it may be photocured by irradiating ultraviolet rays and / or visible light with a short wavelength with an integrated light amount of about 100 to 5000 mJ / cm2. At this time, as the light source, an LED light source, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a metal halide lamp, a xenon lamp, etc. are preferably used.

[0042] The adhesive layer may have a thickness of 100 μm or less, preferably 50 μm or less, for example, 1 to 100 μm, particularly 1 to 50 μm. When the thickness of the adhesive layer exceeds 100 μm, it may be difficult to remove with plasma and may take a long time.

[0043] As shown in FIG. 2(b), in the step (ii), in order to smoothly proceed with the plating process described later, the through hole and the hole 4 formed by the metal foil are subjected to plasma treatment to remove the adhesive layer, which is an organic substance located inside the hole 4.

[0044] In the step (ii), the plasma treatment may be performed using O2, CF4, Ar, N2, He, SF4, NF3, or a mixed gas thereof.

[0045] As shown in FIG. 2(c), in the step (iii), the inside of the hole 4 is filled with metal in a plating process.

[0046] In the step (iii), the plating process may be an electrolytic plating process performed by a bottom-up filling mechanism.

[0047] The electrolytic plating process may be performed by applying a current within a current density range of 0.5 ASD to 30 ASD (Ampere per Square Decimetre), preferably 0.5 ASD to 10 ASD. At this time, the applied current density may be applied in a specific waveform.

[0048] In the step (iii), the metal filled inside the hole 4 may be copper (Cu), gold (Au), silver (Ag), titanium (Ti), nickel (Ni), tin (Sn), cobalt (Co), iron (Fe), or an alloy containing at least any one of these components, and preferably may be copper (Cu).

[0049] The plating composition used in the electrolytic plating process may include a metal salt, a strong acid, and a halogen ion source.

[0050] The metal salt is a metal ion source that dissociates in the composition to supply metal ions, and may be filled inside the hole by being reduced and deposited by an electrochemical reaction.

[0051] The metal salt may be appropriately selected according to the type of metal filled in the hole. For example, inorganic acid salts, organic acid salts, oxides, chlorides, etc. of copper (Cu), gold (Au), silver (Ag), titanium (Ti), nickel (Ni), tin (Sn), cobalt (Co), iron (Fe), or an alloy containing at least one of these components may be mentioned. When the metal filled in the hole is copper (Cu), copper sulfate, copper nitrate, copper acetate, copper oxide, copper chloride, etc. may be used as the metal salt.

[0052] The concentration of the metal salt is not particularly limited, but may be, for example, 100 to 300 g / L, and preferably may be 200 to 250 g / L.

[0053] The strong acid serves as an electrolyte while adjusting the pH, and usually, known substances may be used. Specifically, the strong acid may be one or more selected from the group consisting of sulfuric acid, hydrochloric acid, methanesulfonic acid, ethanesulfonic acid, propanesulfonic acid, trifluoromethanesulfonic acid, sulfonic acid, hydrobromic acid, and fluoroboric acid.

[0054] The concentration of the strong acid is not particularly limited, but when considering the pH of the plating composition, etc., it may be 50 to 150 g / L, and specifically, it may be 90 to 110 g / L.

[0055] The halogen ion source supplies halogen ions in the composition, and usually, known substances may be used. Specifically, the halogen ion source may be a chlorine ion source, for example, hydrochloric acid (HCl).

[0056] The concentration of the halogen ion source is not particularly limited, but for example, it may be 30 to 300 mg / L, and preferably 40 to 200 mg / L.

[0057] Further, the plating composition may further contain one or more of a brightener and a carrier.

[0058] The brightener increases the reduction rate of metal ions to promote plating, and usually, known substances may be used. Specifically, the brightener may be one or more selected from the group consisting of bis-(3-sulfopropyl)disulfide, sodium salt, 3-mercapto-1-propanesulfonic acid, sodium salt, 3-amino-1-propanesulfonic acid, O-ethyl-S-(3-sulphopropyl)dithiocarbonate, sodium salt, 3-(2-benzthiazolyl-1-thio)-1-propanesulfonic acid, sodium salt, and N,N-dimethyldithiocarbamic acid-(3-sulfopropyl)ester, sodium salt.

[0059] The concentration of the brightener is not particularly limited, but when considering the plating rate, etc., it may be 0.5 to 15 ml / L, specifically, it may be 1 to 8 ml / L.

[0060] The carrier is for enhancing the surface flatness of the wiring by suppressing the movement of metal ions and adjusting the metal reduction rate, and usually, known substances may be used. For example, as the carrier, polyethylene glycol, polypropylene glycol, or a copolymer thereof may be used.

[0061] The concentration of the carrier is not particularly limited, but for example, it may be 1 to 15 ml / L, preferably 3 to 12 ml / L.

[0062] The plating composition may contain the remaining amount of water. The water may be deionized water.

[0063] As shown in FIG. 2(d), the step (iv) is a step of removing the metal foil and the adhesive layer with an etching solution.

[0064] In the step (iv), the components of the etching solution may be appropriately selected according to the components of the metal foil. For example, when the metal foil is a copper foil, a normal copper-based metal film etching solution may be used as the etching solution.

[0065] Specifically, in the step (iv), the etching solution may contain one or more selected from the group consisting of copper chloride, iron chloride, hydrochloric acid, nitric acid, sulfuric acid, persulfate compounds, and hydrogen peroxide water.

[0066] The etching solution may contain water corresponding to the remaining amount.

[0067] The method for forming a through-via metal wiring according to an embodiment of the present invention may further include, after the step (iv), a step (v) of cleaning the substrate.

[0068] The cleaning may be performed using deionized water.

[0069] According to the forming method according to an embodiment of the present invention, as shown in FIG. 2(e), a substrate on which a through-via metal wiring 5 is formed with excellent plating quality can be obtained without performing an expensive sputtering process.

[0070] Hereinafter, the present invention will be described more specifically based on examples, comparative examples, and experimental examples. It should be noted that these examples, comparative examples, and experimental examples are merely for explaining the present invention, and it is obvious to those skilled in the art that the scope of the present invention is not limited thereto.

[0071] 〔Example 1: Formation of Through-Via Metal Wiring〕 A copper foil with a thickness of 30 μm was bonded to one surface of a glass substrate with a thickness of 130 μm having a through-hole with an inner diameter of 80 μm via an acrylic adhesive layer (ATL-30, manufactured by SAM WON) with a thickness of 2 μm.

[0072] The other surface of the glass substrate was subjected to plasma treatment using O2 gas to remove the adhesive layer located inside the glass hole.

[0073] An electrolytic plating process was performed using a plating composition containing 230 g / L of copper sulfate, 105.7 g / L of sulfuric acid, 176 mg / L of hydrochloric acid, 6 ml / L of sodium bis-(3-sulfopropyl) disulfide, 4 ml / L of polyethylene glycol, and the balance of deionized water to fill the inside of the glass hole.

[0074] An etching solution containing 5 wt% of sulfuric acid, 10 wt% of hydrogen peroxide solution, and the balance of deionized water was sprayed on the copper foil surface of the glass substrate after the plating process to remove the copper foil and the adhesive layer, and a glass substrate with through-hole metal wiring formed thereon was obtained.

[0075] 〔Experimental Example 1: Cross-sectional analysis of through-hole metal wiring〕 The cross-section of the glass substrate with through-hole metal wiring formed in Example 1 was measured by a field emission scanning electron microscope (FE-SEM) measurement method to confirm the quality of the plating.

[0076] The results are shown in FIGS. 3a and 3b. At this time, FIG. 3a shows the measurement results at a magnification of 100, and FIG. 3b shows the measurement results at a magnification of 500.

[0077] From FIGS. 3a and 3b, it can be confirmed that according to the method for forming through-hole metal wiring of the present invention, through-hole metal wiring can be formed with excellent plating quality without generating voids or seams.

[0078] Although the specific parts of the present invention have been described in detail above, it is obvious that such specific descriptions are merely preferred embodiments for those with ordinary knowledge in the technical field to which the present invention pertains, and the scope of the present invention is not limited thereby. Those with ordinary knowledge in the technical field to which the present invention pertains will be able to make various applications and modifications within the scope of the present invention based on the above content.

[0079] Therefore, it can be said that the substantial scope of the present invention is defined by the claims and their equivalents.

Explanation of Reference Numerals

[0080] 1 Substrate 2 Adhesive layer 3 Metal foil 4 Hole 5 Through-via metal wiring

Claims

1. (i) A step of laminating a metal foil on one surface of a substrate having through vias formed thereon via an adhesive layer; (ii) A step of treating the holes formed by the through vias and the metal foil to remove the adhesive layer located inside the holes; (iii) A step of filling the inside of the holes with metal by an electroplating process; and (iv) A step of removing the metal foil and the adhesive layer, wherein the adhesive layer is formed of an acrylic-based adhesive, in the step (ii), the treatment is a plasma treatment, in the step (iv), it is removed with an etching solution containing one or more selected from the group consisting of copper chloride, iron chloride, hydrochloric acid, nitric acid, sulfuric acid, persulfate compounds, and hydrogen peroxide water. A method for forming through-via metal wiring.

2. After the step (iv), the method for forming through-via metal wiring according to claim 1, further comprising (v) a step of cleaning the substrate.

3. The substrate is a glass substrate, a silicon substrate, or a ceramic substrate. The method for forming through-via metal wiring according to claim 1.

4. The metal foil is a copper foil. The method for forming through-via metal wiring according to claim 1.

5. The metal foil has a thickness of 3 to 1,000 μm. The method for forming through-via metal wiring according to claim 1.

6. In the step (ii), the plasma treatment is performed using O2, CF4, Ar, N2, He, SF4, NF3, or a mixed gas thereof. The method for forming through-via metal wiring according to claim 1.

7. In the step (iii), the electroplating process is an electroplating process performed by a bottom-up filling mechanism. The method for forming through-via metal wiring according to claim 1.

8. In the step (iii), the metal filled inside the holes is copper (Cu). The method for forming through-via metal wiring according to claim 1.

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