CN1558270A - Structure for increasing reliability of metal connection - Google Patents

Abstract

A structure for increasing the reliability of metal connection line is composed of multiple metal bumps on a substrate, and multiple recesses on another surface of each metal bump adjacent to the substrate. The metal bumps with the lattice structure are formed on the chip to increase the grabbing probability of the conductive particles of the ACF, and the contact area between the adhesive material of the ACF and the metal bumps in the grooves of the metal bumps with the lattice structure is increased to improve the tensile strength of the combination of the chip and the metal pads of the glass substrate.

Description

A structure that increases the reliability of metal connections

technical field

The present invention relates to a structure for increasing the reliability of metal wiring, in particular to the construction technology of integrated circuits, in particular to a construction technology applied between integrated circuits and displays.

Background technique

In some existing electronic devices, the connection between the components and the main circuit is performed through a conductive film (such as anisotropic conductive glue, referred to as ACF). Anisotropic conductive adhesive ACF is made by mixing non-conductive synthetic resin and conductive particles. As shown in the cross-sectional view of Figure 1A, the conductive particle 1 has a diameter of about 3-5 μm, and its central part 1a is Polymer, and covered with a metal conductor 1b, such as gold, nickel, tin, etc. on the outside.

ACF is often used in the manufacture of liquid crystal displays, and some are used to directly package the driver chip of the panel on the glass substrate (commonly known in the industry as COG, that is, chip on glass), or bond the driver chip to a flexible circuit board. (COF, that is, chip on Film), and then bonded to the substrate method. In addition, ACF is also suitable for the process of bonding chips to general printed circuit boards (COB, chip onboard).

As shown in FIG. 1B , the substrate 4 represents the aforementioned glass substrate, flexible circuit board, printed circuit board or other circuit board components. During manufacture, a metal pad (pad) 4a is formed on the substrate 4 for transmission of various signals and energy. On the other hand, thick conductive bumps 3a are formed on the leads of the chip 3 . Put the anisotropic conductive glue (ACF) 5 between the driver chip 3 and the substrate 4, then heat to change the viscosity of the anisotropic conductive glue (ACF) 5, and then press the driver chip 3 and the substrate 4, and the corresponding The metal pads 4a and the conductive bumps 3a must be aligned with each other.

Since the conductive bump 3a has a certain thickness, the conductive particles 1 will be squeezed between the conductive bump 3a and the metal pad 4a. The extruded conductive particles 1 form an electrical connection between the conductive bumps 3a and the metal pads 4a by virtue of the metal layer 1b coated on their outer peripheral surfaces. The ACF is used for chip packaging, and the action of bonding the driving chip 3 and coupling the circuit can be completed at the same time.

When using ACF for chip packaging, a common problem is improper migration of conductive particles. Since the viscosity of the resin part in the ACF decreases after heating, when the conductive bump 3 a and the metal pad 4 a are pressed together, the conductive particles 1 therebetween are easy to diffuse and migrate to the surrounding. One of the problems, as shown in FIG. 1C , is that the number of conductive particles 1 between the conductive bump 3 a and the metal pad 4 a is too small, which increases the coupling resistance. Furthermore, another problem as shown in FIG. 1D is that too many conductive particles 1 are concentrated between adjacent conductive bumps 3a, thereby generating lateral electrical connections, that is, adjacent conductive bumps 3a and adjacent The metal pad 4a causes a short circuit. As chip functions increase day by day and the number of pins per unit area increases accordingly, the problem of short circuit will become more and more likely to occur. As the area of gold bumps shrinks, the phenomenon of insufficient capture rate of conductive particles is also likely to occur.

Contents of the invention

In view of this, in order to solve the above-mentioned problems, the object of the present invention is to provide a structure that increases the reliability of the metal connection, by forming metal bumps with a lattice structure on the chip, to increase the grasping of the conductive particles of the ACF The probability is taken, and the contact area between the ACF glue and the metal bumps in the grooves of the metal bumps in the lattice structure is increased, so as to improve the tensile strength of the chip and the metal pad of the glass substrate.

To achieve the above object, the present invention provides a structure for increasing the reliability of metal wiring, which includes a plurality of metal bumps located on a substrate, and each metal bump has a plurality of grooves on the other surface adjacent to the substrate .

In order to make the above and other objects, features, and advantages of the present invention more comprehensible, a preferred embodiment will be described in detail below together with the accompanying drawings.

Description of drawings

Figure 1A shows a typical conductive particle structure;

Figure 1B shows a schematic diagram of the ACF bonding method between the driver chip and the glass substrate;

Figures 1C and 1D show the common problems of the traditional ACF bonding method;

Fig. 2 depicts a plan view of a preferred embodiment of the structure of the present invention to increase the reliability of metal wiring;

Fig. 3 is a sectional view along 3-3' of Fig. 2;

Fig. 4 depicts a plan view of another preferred embodiment of the structure of the present invention to increase the reliability of metal wiring;

Fig. 5 depicts a plan view of another preferred embodiment of the structure of the present invention to increase the reliability of metal wiring;

FIG. 6 is a schematic diagram illustrating another preferred forming method of the structure for increasing the reliability of the metal connection according to the present invention.

Explanation of reference signs

current technology

1 Conductive Particles 1b Metal Layer

3 chip 3a conductive bump

4 Substrate 4a Metal Pad

5 ACF

The technology of the present invention

202, 602 Metal bumps 204 First substrate

206, 402, 502 Groove

208 Conductive Particles 210 Second Substrate

212 metal pad 604 resin lattice structure

606 Surface of metal bumps

Detailed ways

Example

Please refer to FIG. 2 and FIG. 3 at the same time. FIG. 2 shows a plan view of a preferred embodiment of the structure for increasing the reliability of the metal connection according to the present invention. Fig. 3 is a sectional view along line 3-3' of Fig. 2 . A plurality of metal bumps 202 are located on a first substrate 204 such as a semiconductor substrate. In this preferred embodiment, the semiconductor substrate 204 is a silicon chip, and the metal bumps 202 are preferably made of gold, which is formed on silicon Metal electrodes (not shown) of the chip are connected to the chip 204 , and the metal bump 202 has a plurality of grooves 206 on the other surface adjacent to the first substrate 204 . The grooves 206 are preferably rectangular or square, and arranged in a matrix to form a grid-like metal bump 202 . It should be noted that the shortest side of the rectangular groove 206 needs to be longer than the diameter of the conductive particles 208 of the anisotropic conductive glue (ACF), so that the metal bumps 202 of the lattice structure can effectively grab the conductive particles 208 . The diameter of the conductive particles is about 3-5 μm, the central part is polymer, and the outside is covered with metal conductors, such as gold, nickel, tin, etc.

Thereafter, when the metal bump 202 on the first substrate 204 and the metal pad 212 on the second substrate 210, such as a glass substrate or a resin substrate, are bonded together, the ACF between the two substrates 204, 210 is performed. During heating and high-pressure bonding, the conductive particles 208 of the ACF are not easy to diffuse and migrate around because of the lattice structure 206 , so the conductive particles 208 can be effectively captured in the groove 206 to increase the probability of capturing the conductive particles 208 . In addition, the metal bumps with a lattice structure can also have four matrix-arranged grooves 402 as shown in FIG. 4, and two parallel grooves 502 as shown in FIG. chance of crawling.

form

A preferred method of forming the metal bumps 202 in a lattice structure is to pattern the metal bumps into a lattice structure with a plurality of grooves 206 by photolithography and etching after the metal bumps are formed. In addition, another preferred formation method, as shown in FIG. 6, is to form a lattice structure 604 made of resin on the area where the metal bump 602 is to be formed before the metal bump 602 on the chip is formed, and then When the metal bumps 602 are formed by electroplating, the metal bumps form a lattice structure on the surface 606 due to the influence of the height difference.

Features and advantages of the invention

The feature of the present invention is to provide a structure that increases the reliability of metal wiring, by forming grid-shaped metal bumps with multiple grooves on the chip to increase the probability of grasping the conductive particles of ACF, so the present invention An advantage of the invention is that when the first substrate and the second substrate are pressed together, the problem of insufficient number of conductive particles of the metal bumps and metal pads which increases the coupling resistance can be solved, thereby increasing the stability of the product. In addition, there is a larger contact area between the metal bump and the rubber material in the groove structure, which can increase its tensile strength. And because the groove structure can increase the conduction contact area between the conductive particles and the metal bumps, the present invention also has the advantage of reducing the coupling resistance.

Although the present invention has been disclosed above in conjunction with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art may make some changes and modifications without departing from the spirit and scope of the present invention. Therefore The scope of protection of the present invention is defined by the appended claims.

Claims (15)

1. A structure for increasing the reliability of metal connections, comprising: a plurality of metal bumps on a substrate; and Each metal bump has a plurality of grooves on the other surface adjacent to the substrate. 2. The structure for increasing the reliability of metal connection as claimed in claim 1, wherein the substrate is a semiconductor substrate. 3. The structure for increasing the reliability of metal connection as claimed in claim 1, wherein the metal bumps are composed of gold. 4. The structure for increasing the reliability of metal wiring as claimed in claim 1, wherein the grooves are rectangular or square. 5. The structure for increasing the reliability of metal wiring as claimed in claim 4, wherein the rectangular or square grooves are arranged in a matrix. 6. A structure for increasing the reliability of metal connections, comprising: Two opposing first substrates and a second substrate; A plurality of metal bumps are located on the first substrate, wherein each metal bump has a plurality of grooves on a surface opposite to the second substrate; a plurality of metal pads are located on the second substrate, wherein the metal pads are opposite to the metal bumps; and An anisotropic conductive adhesive is located between the first substrate and the second substrate to bond the first substrate and the second substrate, wherein the anisotropic conductive adhesive has a plurality of conductive particles, and each metal bump contains at least A conductive particle is located in at least one of the grooves of the metal bump, so that the metal bump is coupled to the corresponding metal pad. 7. The structure for increasing the reliability of metal connection as claimed in claim 6, wherein the first substrate is a semiconductor substrate. 8. The structure for increasing the reliability of metal connection as claimed in claim 6, wherein the second substrate is a glass substrate. 9. The structure for increasing the reliability of metal connection as claimed in claim 6, wherein the second substrate is a resin substrate. 10. The structure for increasing the reliability of metal connection as claimed in claim 6, wherein the metal bumps are composed of gold. 11. The structure for increasing the reliability of metal connection as claimed in claim 6, wherein the grooves are rectangular or square. 12. The structure for increasing the reliability of metal connection as claimed in claim 11, wherein the short side of the rectangle is larger than the diameter of the conductive particles. 13. The structure for increasing the reliability of metal wirings as claimed in claim 11, wherein the rectangular or square grooves are arranged in a matrix. 14. The structure for increasing the reliability of metal connection as claimed in claim 6, wherein the center of the conductive particles is a polymer and the outer periphery is covered with a metal conductor. 15. The structure for increasing the reliability of metal connection as claimed in claim 14, wherein the metal conductor is gold, nickel or tin.

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