KR20100031915A - Adhesion method using nanowire and nanotube - Google Patents

Abstract

PURPOSE: An adhesion method using a nanowire and a nanotube is provided to facilitate a conductive/non-conductive adhesion selectively, and to obtain environment-friendly property. CONSTITUTION: An adhesion method using a nanowire and a nanotube uses a physical contact between one adhesion surface attached with the nanotube(110) or the nanowire, and the other adhesion surface attached with the nanotube(210) or the nanowire to mechanically tangle the nanowires or the nanotubes. An adhesion method comprises the following steps: (a)forming multiple nanowires or nanotubes on one adhesion surface and forming multiple nanowires or nanotubes on the other adhesion surface; (b)contacting the multiple nanowires or nanotubes of each adhesion surface together.

Description

Adhesion Method Using Nanowire and Nanotube

The present invention relates to a method of adhesion using mechanical entanglement of nanowires or nanotubes, and to an adhesion method capable of adhesion and detachment and capable of selective adhesion of conductive / non-conductive materials.

The connection between the silicon chip and the PCB (Printed Circuit Board) board, the connection between the PCB board, etc., is becoming a trend of miniaturization and miniaturization of electronic products, such as smart cards, LCDs, PDP displays, computers, mobile phones, communication It is widely used in the field of a system.

The conventional technology used for the connection between the semiconductor chip and the substrate and the connection between the substrates may be classified into a technique using solder / solder bumps and a non-solder technique using no solder.

Solder technology has difficulty in production of fine solder, complex soldering process such as solder flux application, alignment, solder bump reflow, flux removal, underfill filling and hardening, which leads to problems in production cost.

The non-solder technology is typically a technique using an anisotropic conductive paste, anisotropic conductive film, conductive paste, conductive film, non-conductive paste or non-conductive film. Specifically, a process of applying a paste or temporarily attaching a film on a substrate, aligning the chip and the substrate, and finally applying heat and pressure to complete the connection. However, this process has a long process time that requires the formation of a film or the application or provisional bonding of adhesive material on each substrate.

First of all, the conventional connection (adhesion) technology can not be used again and again once the connection is possible, the rework process is practically impossible. In addition, in order to bond only the desired specific area between the two elements attached, it is difficult to select a material constituting the adhesive, such as a polymer resin, a curing agent, an organic solvent, and conductive particles, and the content thereof should be optimized for each connection object. There is a disadvantage that unwanted current movement paths are easily formed after bonding.

An object of the present invention for solving the above problems is that the adhesion and detachment, can perform a repeatable adhesion, the conductive / non-conductive adhesion can be easily made selectively, the connection method between the conventional electronic elements Flip-chip connection, non-conductive adhesive (NCA) using anisotropic conductive adhesives (ACA) with solder balls, ball grid array (BGA) or chip size package (CSP) connections, and non-solder connections between substrates using solder bumps; It can replace flip chip connection using non-conductive adhesives, and provide eco-friendly adhesive method that does not generate lead, flux, etc.

According to the present invention, the bonding method includes one adhesive surface having nanowires or nanotubes fixed to a predetermined region; and another adhesive surface having nanowires or nanotubes fixed to a predetermined region; The two adhesive surfaces are bonded by mechanical entanglement between the formed nanowires, between nanowires and nanotubes, or between nanotubes.

In detail, the bonding method includes the steps of: a) forming a plurality of nanowires or nanotubes in a predetermined region of one adhesive surface, and forming a plurality of nanowires or nanotubes in a predetermined region of another adhesive surface; And b) physically contacting the nanowires or the nanotubes formed in the predetermined areas of the one adhesive surface and the other adhesive surface, respectively, in the predetermined regions of the two adhesive surfaces by the physical contact. Mechanical entanglement occurs between the formed nanowires, between nanowires and nanotubes, or between nanotubes, thereby bonding the two adhesive surfaces.

In order to induce stronger mechanical entanglement, it is preferable that one end of the nanowire adhered to a predetermined region of the adhesive surface is bent.

In order to induce stronger mechanical entanglement, it is preferable that a plurality of nanowires or nanotubes are fixed in a network on a certain region of the adhesive surface.

When conductive adhesion is required, the nanowires and the nanotubes are conductive materials, and are characterized by being electrically energized between the two adhesion surfaces by the mechanical entanglement. When the non-conductive adhesion is required, the nanowires or the nanotubes are required. Is characterized by being a non-conductive material.

The nanowires are formed using chemical vapor deposition, physical vapor deposition, electroplating, or electroless plating using nano templates, and have one end of the nano wires bent by growing the nano wires out of the nano templates. The nanowires have a diameter of 5 to 100 nm and a length of 10 to 10 ⁵ nm.

After forming a nanowire or a composite of a nanotube and a metal in a predetermined region of the adhesive surface, by removing the metal is characterized in that the nanowire or nanotube entangled in a network.

In the adhesion method of the present invention, the adhesion may be adhesion between heterogeneous substrates; Adhesion between a silicon chip and a printed circuit board (PCB) substrate; Adhesion between homogeneous substrates; Adhesion between PCB substrates, adhesion between silicon chips; Adhesion between silicon substrates; Or flip chip bonding, wherein the region to be bonded comprises one region of the PCB or silicon substrate surface; One region of the surface of the silicon chip; Or a region of a metal wiring formed on a substrate surface or a silicon chip surface.

The adhesion method according to the present invention is capable of adhesion and detachment, and can perform semipermanently repeatable adhesion away from the conventional one-time adhesion, and as the nanowire or nanotube material is composed of a conductive material or a nonconductive material, Non-conductive bonding can be easily done selectively, and anisotropic with solder ball, board grid (BGA) or chip size package (CSP) connection and non-solder connection between solder balls and solder bumps. It can replace flip chip connection using anisotropic conductive adhesives (ACA) and flip chip connection using non-conductive adhesives (NCA), and it is an environmentally friendly adhesive that does not generate lead or flux. It has the advantage of being a method.

Hereinafter, the bonding method of the present invention will be described in detail with reference to the accompanying drawings. The drawings introduced below are provided by way of example so that the spirit of the invention to those skilled in the art can fully convey. Accordingly, the present invention is not limited to the drawings presented below and may be embodied in other forms. Also, like reference numerals denote like elements throughout the specification.

At this time, if there is no other definition in the technical terms and scientific terms used, it has a meaning commonly understood by those of ordinary skill in the art to which the present invention belongs, the gist of the present invention in the following description and the accompanying drawings Descriptions of well-known functions and configurations that may be unnecessarily blurred are omitted.

1 is a conceptual diagram illustrating a bonding method according to the present invention. In detail, the adhesion method according to the present invention is a nanowire or nanotube 110 fixed to a predetermined region of the adhesive surface (P1) of one adhesive object 100; and the adhesive surface (P2) of the other adhesive object 200 Nanowires or nanotubes 210 fixed to a predetermined region of the nanowires 110 and 210, between the nanowires 110 and 210, between the nanowires 110 or 210 and nanotubes 210 or 110, and between nanotubes ( The two adhesive surfaces P1 and P2 are bonded by the mechanical and physical entanglement of the 110 and 210.

Although FIG. 1 illustrates a case where nanowires or nanotubes are formed in the entire region of the adhesive surface P1 or P2, the nanowires or nanotubes may be formed only in a portion of the adhesive surface as necessary. .

The adhesive method of the present invention is similar to the adhesive principle of the locking tape made of nylon from Velcro, which is well known under the trade name Velcro, and in the present invention, the conductive metal nanowire, non-conductive metal oxide nanowire, and carbon nano are not nylon. One-dimensional nanowires, such as tubes, are used to perform mechanical bonding and electrical bonding as necessary.

As shown in FIG. 1, the bonding method according to the present invention is a method of attaching two bonding surfaces by heterogeneous or homogeneous mechanical interlocking consisting of a combination of nanowires and nanotubes.

The nanowires (nanotubes) formed in a predetermined region of the contact surface are rooted at a base (a material constituting the contact surface on which the nanowires or nanotubes are formed), and the direction of the long axis of the nanowires (nanotubes) is directed to the base. It is preferable that they are a plurality of nanowires (nanotubes) having a certain amount of vertical components or meshed nanowires (nanotubes) that form networking in an irregular entanglement with each other.

More preferably, as shown in FIG. 1, the one contact surface P1 includes a plurality of nanowires (nanotubes) 110 in which the long axis direction of the nanowires (nanotubes) has a predetermined amount perpendicular to the matrix. The other contact surface P2 is provided with a mesh-shaped nanowire (nanotube) that forms a network irregularly entangled with each other. This is because the nanowires or nanotubes are entangled with each other in a state in which the nanowires or nanotubes protrude out of the surfaces of the contact surfaces P1 and P2, and thus adhesion is performed.

In addition, a plurality of nanowires 110 having a certain amount of perpendicular components in the direction of the long axis of the nanowires are fixed to a predetermined region of the adhesive surface to induce stronger mechanical entanglement as shown in FIG. 1. It is preferable that one end (protruded end) of the nanowire is bent.

Preferably, the portions protruding out of the surface in a mesh shape (net) with the roots of the nanowires or nanotubes embedded in the annular shape physically contact with the annular nanowires so that the meshes and the annular nanowires (nanotubes) Mechanically tangled together and glued together.

In the bonding method of the present invention, the two bonding objects are different substrates; Silicon (semiconductor) chips and printed circuit board (PCB) substrates; Homogeneous substrates; Two PCB substrates; Two silicon (semiconductor) chips; Or two silicon substrates (including a silicon substrate having a passivation film of a silicon oxide film or a nitride film formed on its surface), and the bonding method of the present invention includes a flip chip bonding form.

In addition, the adhesive region (R1, R2 of Figure 1) is a region of the PCB or silicon substrate surface; One region of the surface of the silicon chip; Or a region of a metal wiring formed on a substrate surface or a silicon chip surface. For example, a semiconductor, an oxide / nitride film, a metal, or a polymer may be an adhesive region material.

As the nanowire, a metal nanowire or a nanotube having a very small bending curvature, which is mainly ductile and easy to grow in a ring shape, is preferably used.

In this case, when the metal nanowires and the conductive carbon nanotubes are provided on the adhesive surface, the physical adhesion and the electrical conduction between the adhesion targets are performed. It is provided with a nanowire formed to prevent energization and achieve physical adhesion.

The adhesion by the nanowires (nanotubes) is a small adhesion, but the adhesion of a very large number of nanowires to show a large adhesion. At the same time, when the nanowires are detached from each other, very large stresses are required, but when the nanowires are detached gradually from one direction as shown by the arrow of FIG.

Figure 2 is another conceptual diagram of the bonding method according to the present invention, showing an example of a flip chip connection between the silicon chip and the PCB substrate.

As shown in FIG. 2, one object to be bonded is a silicon chip 100 manufactured through a conventional semiconductor device process to form a metal interconnection 101 for electrical connection, and the other object to be bonded is a silicon chip 100. The PCB 200 is formed with a metal wire 201 for electrical connection.

As shown in FIG. 2, in the bonding method of the present invention, a plurality of nanowires or nanowires are formed on one region of the bonding surfaces P1 and P2 of the object 100 and 200, that is, each of the metal wiring regions R1 and R2. Form a tube.

In detail, the silicon chip 100 masks 310 a surface other than a region to form nanowires or nanotubes, and then chemical vapor deposition, physical vapor deposition, electroplating, or electroless deposition using nano templates. After forming the nanowires 110 fixed to the metal wires 101 using gold, the masking 310 is removed, and the plurality of nanowires fixed to the metal wires 101 of the semiconductor chip 100 are formed. 110.

In this case, the silicon chip 100 may be an individual chip sawed (sawing), it may be a silicon chip 100 of the wafer state before sawing.

Similarly to the silicon chip 100, a plurality of nanowires or nanotubes 210 are fixed to the metal wire 201 of the PCB substrate 200 using the masking 320.

As shown in the example of FIG. 2, when the silicon chip 100 is provided with a plurality of nanowires 110 having a vertical component in the direction of the long axis of the nanowires, the PCB substrate 200 may be irregular with each other. It is preferable that a mesh-shaped nanowire (nanotube) 210 is formed to entangle networking.

The physical properties of the nanowires have a size effect. As the diameter of the nanowires decreases, the melting point decreases and the critical curvature value increases. The size-dependent physical properties of these nanowires enable the nanowires to have properties such as ductility, elasticity, and small bending curvature radius required for adhesion. To this end, the nanowire diameter is 5 to 100nm, the length is preferably 10 to 10 ⁵ nm.

The nanowires are metal nanowires, preferably Cu, Sn, In, Fe, Bi, Ni, Co, Au or Ag nanowires, as shown in FIG. One metal nanowire is a nanowire containing oxides of Cu, Sn, In, Fe, Bi, Ni, Co, Au, or Ag.

In order to include the nanowires in the adhesive region, various known nanowire manufacturing methods may be used. For example, chemical vapor deposition using a nano template, physical vapor deposition, electroplating or electroless plating may be used. can do.

In addition, as shown in FIG. 2, the nanowires 110 formed on the silicon chip 100 may be nanowires having one end (a protruding end) bent by overgrowing the nanowires out of the nano template. Do.

The shape of the nanowire having one end cyclic may be formed using various methods, but it is preferable to form the cyclic nanowire by overgrowing the nanowire length out of the template. In this case, the degree of overgrowth (the length of the overgrown nanowires) is preferably about 1 to 10 times the diameter of the nanowires so as to have the annular shape and the independent nanowires by overgrowth.

In order to manufacture the mesh-shaped nanowires (nanotubes) 210 that form a network irregularly tangled with each other on the PCB substrate 200, various conventionally known nanowires (nanotubes) manufacturing methods may be used. After forming a composite of a nanowire or a nanotube and a metal in a predetermined region of the adhesive surface, it is possible to form a nanowire or nanotube entangled into a network by removing the metal. More preferably, after dispersing the nanotubes (nanowires) in an electrolytic cell containing a metal ion or a metal precursor, the voltage is reduced to form a composite of the nanotubes (nanowires) and a metal base in the adhesive region. By etching and removing the metal, mesh-shaped nanotubes (nanowires) that are entangled with one another and form a network can be manufactured.

At this time, by adjusting the density of the nanotubes (nanowires) in the metal base, it is possible to produce surface protruding nanotubes (nanowires) or mesh nanotubes (nanowires) that are tangled with each other irregularly.

In the bonding shown in FIG. 2, the annular nanowire 110 provided in the bonding region R1 of the silicon chip 100 and the mesh-shaped nanotubes provided in the bonding region R2 of the PCB substrate 200 (b. When the line 210 is brought into contact with each other, an appropriate shaking is performed in a direction parallel to and perpendicular to the contact surfaces P1 and P2 to induce entanglement of the mesh nanotubes 210 and the annular nanowires 110. Of course it can.

Figure 3 is a scanning electron micrograph of the cyclic nanowires prepared in Preparation Example 1, Figure 4 is a scanning electron microscope photograph of the protruding carbon nanotubes prepared in Preparation Example 2.

5 is a cross-sectional scanning electron micrograph of the carbon nanotubes and the metal complex formed on the substrate in Preparation Example 3, Figure 6 is a surface of the mesh carbon nanotubes formed after electrolytic etching to remove the metal in the composite in Preparation Example 3 It is a scanning electron micrograph, Figure 6 (b) is a high magnification scanning electron micrograph that can confirm that the carbon nanotubes are intertwined in a disordered network. Figure 7 is a side scanning electron micrograph that can be confirmed that the mesh-shaped carbon nanotubes prepared in Preparation Example 3 formed on a metal base. FIG. 8 is a cross-sectional scanning electron micrograph of an adhesive portion which can confirm that mechanical entanglement between copper nanowires of two substrates is effectively generated and bonded in an embodiment in which two nanowire bundles prepared in Preparation Example 1 are actually contacted and bonded.

(Production Example 1)

(Adhesion target with ring-shaped nanowire)

Al foil with a purity of 99.99% or more is immersed in an anodizing solution (0.3 M oxalic acid solution), and an anode voltage of 40 V at 1 ° C. is applied for 1 hour. aluminum oxide template, AAO) was prepared on Al foil. Afterwards, it was necessary to reduce the thickness of the barrier layer under the channel of aluminum anodized template for copper nanowire deposition (RC Furneaux, WR Rigby, and AP Davidson, Nature, 337 (1989). p.147). That is, in the same oxalic acid solution, the anodization voltage is sequentially lowered from 40 V, which is anodization voltage, to 5 V at a specific ratio, and finally, the thickness of the barrier layer is reduced to about 5 nm, which is the native oxide level, to enable electroplating. It was. For electroplating Cu nanowires, a solution of 1.25 M copper sulfate pentahydrate (CuSO ₄ -5H ₂ O) and 2.3 M boric acid (H ₃ BO ₃ ) solution was used, and the pH was set to 2.0. The plating method was a two-cell method using anodized aluminum template as a working electrode and Pt foil as a counter electrode. The potential applied to the working electrode was pulse reverse plating with periodic changes of + 6 V and-8 V. The frequency was 100 Hz. The deposition rate of Cu nanowires was about 1 μm / min and was deposited for about 80 seconds considering the height of the template to form nanowires exposed out of AAO. After depositing the nanowires entirely on the aluminum anodized template, photolithography was performed for patterning the nanowires. A negative type AZ52144E PR was used for lithography. Lithography conditions were soft baked at 100 ° C. for 90 seconds after PR application at 3000 rpm, and then masked and exposed for 1.7 seconds using an I-line beam. Subsequently, post baking was performed at 120 ° C. for 120 seconds, followed by an additional 30 seconds of exposure. And through developing, PR patterns were formed only on the desired area. Next, in order to remove the nanowires and AAO in the remaining portions except for the pattern region, the AAO was removed by immersion for about 2 hours in an aqueous NaOH solution at pH 14 for about 2 hours. Subsequently, PR remaining in the nanowire pattern was removed using a PR remover to obtain a patterned cyclic Cu nanowire as a final product.

FIG. 3 shows the results of Preparation Example 1 in which about 30 nm diameter and 2 μm long nanowires formed about 200 nm ring length on the template.

(Manufacture example 2)

(Adhesion target on which protruding nanotubes are formed)

The carbon nanotubes were heat treated at 350 ° C. for 40 minutes to remove foreign substances such as amorphous carbon. Carbon nanotubes were added to the diluted hydrochloric acid solution and stirred to purify the carbon nanotubes. After acid treatment, the acid solution was filtered with a filter, and the filtered carbon nanotubes were washed with purified water.

Dispersion of 6 g / l of previously purified carbon nanotubes and carbon nanotubes in a copper plating solution containing 28 g / l of copper sulfate, 50 g / l of ammonium sulfate and 5 g / l of citric acid as a metal chelating agent to help form nanocrystals And 1 g / l of polyacrylic acid (molecular weight 5000) and 4 g / l of sodium dodecyl sulfate as an additive to enhance adsorption to prepare a copper-carbon nanotube mixed plating solution.

Into the mixed plating solution, a copper rod is placed as an anode, a silicon wafer on which copper is deposited is installed as a cathode, and a current is applied to a current corresponding to a voltage of 10 V using pulse plating to make metal nanocrystals. A dense thin film-type nanocrystalline copper / carbon nanotube nanocomposite film was formed on the cathode by giving 0.2 ms of dwell time and 19.8 ms of dwell time.

FIG. 4 shows that carbon nanotubes protrude from the surface of the nanocrystalline copper / carbon nanotube nanocomposite membrane prepared in Preparation Example 2. FIG. 5 shows that the surface of the nanocrystalline copper / carbon nanotube nanocomposite film thus formed is epoxy and then the carbon nanotubes are uniformly distributed in the thickness direction as a side photograph after mechanical / electrolytic polishing.

(Production Example 3)

(Adhesion target with mesh-network nanotubes formed)

After forming the nanocrystalline copper / carbon nanotube nanocomposite film prepared in Preparation Example 2, the nanocrystalline copper base was removed by a predetermined thickness by electrolytic etching to form a mesh carbon nanotube on the surface.

6 is a (a) low magnification and (b) high magnification scanning electron micrograph of a carbon nanotube network prepared in Preparation Example 3 (a network of carbon nanotubes on a nanocrystalline copper / carbon nanotube nanocomposite film on a silicon substrate) 6, it can be seen that carbon nanotubes are manufactured in a mesh tangled with each other irregularly.

A scanning electron microscope photograph of the side surface of the carbon nanotube network structure prepared in Preparation Example 3 is shown in FIG. 7. It can be seen from FIG. 7 that the carbon nanotube network remaining after the nanocrystalline copper substrate is electroetched to a certain thickness is formed very densely and high density is maintained even in a large area.

(Example)

Copper nanowires formed of the cyclic nanowires prepared in Preparation Example 1 were physically contacted with each other to bond the two nanowire bundles. In order to visually observe the adhesion of the two nanowire bundles, the nanowire bundles prepared in FIG. 3 were peeled off the substrate and then piled up and contacted with each other.

In the present invention as described above has been described by specific matters, such as a specific method of manufacturing a nanowire and limited embodiments and drawings, which is provided only to help a more general understanding of the present invention, the present invention is limited to the above embodiments Various modifications and variations can be made by those skilled in the art to which the present invention pertains.

Therefore, the spirit of the present invention should not be limited to the described embodiments, and all of the equivalents or equivalents of the claims as well as the claims to be described later will belong to the scope of the present invention. .

1 is a conceptual diagram illustrating a bonding method according to the present invention,

2 is a conceptual diagram in which a bonding method according to the present invention is introduced into a flip chip connection;

Figure 3 is a scanning electron micrograph of the cyclic nanowires prepared in Preparation Example 1 of the present invention,

Figure 4 is a scanning electron microscope photograph of the protruding carbon nanotubes prepared in Preparation Example 2 of the present invention,

5 is a cross-sectional scanning electron micrograph of the step of forming a carbon nanotube and a metal composite on a substrate in Preparation Example 3 of the present invention,

6 is a scanning electron micrograph (a: low magnification, b: high magnification) of a surface of a carbon nanotube formed after removing a metal in the composite by electrolytic etching to a certain thickness in Preparation Example 3 of the present invention.

7 is a side scanning electron micrograph showing that the carbon nanotubes prepared in Preparation Example 3 of the present invention are formed on a metal base.

FIG. 8 is a cross-sectional scanning electron micrograph of an adhesive portion which can confirm that mechanical entanglement between copper nanowires of two substrates effectively occurs and adheres in an embodiment of the present invention.

Claims (10)

Physically contacting one adhesive surface to which nanowires or nanotubes are fixed to a certain area; and the other adhesive surface to which nanowires or nanotubes are fixed to a certain area; Bonding method characterized in that the two bonding surfaces are bonded by mechanical entanglement between the nanowires, nanowires and nanotubes or between the nanotubes formed on each of the two adhesion surfaces. The method of claim 1, The adhesion method a) forming a plurality of nanowires or nanotubes in a predetermined region of one adhesive surface, and forming a plurality of nanowires or nanotubes in a predetermined region of another adhesive surface; And b) physically contacting the nanowires or nanotubes formed on a predetermined region of the one adhesive surface and the other adhesive surface, respectively; Bonding method characterized in that it is carried out including. The method of claim 1, Bonding method characterized in that one end of the nanowire is fixed to a predetermined region of the adhesive surface is bent. The method of claim 3, wherein Bonding method characterized in that a plurality of nanowires or nanotubes are fixed in a network on a predetermined region of the adhesive surface. The method of claim 4, wherein And the nanowires and the nanotubes are conductive materials and are electrically energized between the two bonding surfaces by the mechanical entanglement. The method of claim 4, wherein And the nanowires or nanotubes are nonconductive materials. The method of claim 3, wherein The nanowires are formed by using chemical vapor deposition, physical vapor deposition, electroplating, or electroless plating using nano templates, and by adhering nanowires out of nano templates, one end of the nanowires is bent. Way. The method of claim 7, wherein The nanowires have a diameter of 5 to 100 nm and a length of 10 to 10 ⁵ nm. The method of claim 4, wherein Forming a nanowire or a composite of a nanotube and a metal in a predetermined region of the adhesive surface, and then removing the metal to form a nanowire or nanotube entangled in a network. The method according to any one of claims 1 to 9, The adhesion is adhesion between dissimilar substrates; Adhesion between a silicon chip and a printed circuit board (PCB) substrate; Adhesion between homogeneous substrates; Adhesion between PCB substrates; Adhesion between silicon chips; Adhesion between silicon substrates; Or flip chip adhesion; The region to be bonded may comprise one region of the PCB or silicon substrate surface; One region of the surface of the silicon chip; Or one region of a metal wiring formed on a substrate surface or a silicon chip surface.

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