KR100614564B1 - A junction method of a chip bump and a substrate pad using underfill resin and supersonic - Google Patents

Abstract

The present invention relates to the ultrasonic bonding method using the application and curing of the underfill resin to improve the bonding strength and electrical properties in the bonding method of the metal bump of the display driving chip and the semiconductor chip and the pad of the substrate. will be.

Bonding method of the chip bump and the substrate pad using the underfill resin and the ultrasonic wave according to the present invention includes (a) a plasma treatment step for cleaning the conductive pad formed on the substrate; (b) applying an underfill resin to a pad of the substrate being cleaned using a dispenser; (c) aligning the substrate on which the underfill resin is applied and the chip on which stud bumps or flat bumps are formed by using an ultrasonic head; (d) applying a horizontal and vertical load through the ultrasonic head to the top of the chip after the alignment to induce deformation between the bump and the pad to induce direct bonding; And (e) curing the underfill resin using ultrasonic energy simultaneously with the direct bonding of the bumps and the pads.

According to the present invention, it is possible to bond not only the existing Au-Au bonding but also heterometal bonding such as Au-Cr, Au-Al, and conductive inorganic materials such as Au-ITO by the bonding method using ultrasonic wave and underfill resin, Joining is possible.

Description

A junction method of a chip bump and a substrate pad using underfill resin and supersonic}

Figure 1 shows an embodiment for bonding the chip bump and the substrate pad using the underfill resin and ultrasonic waves according to the present invention.

2 illustrates an embodiment of applying an underfill resin to a substrate.

Figure 3 shows the bonding process by deformation of the stud bump of the substrate pad and chip.

4 illustrates another embodiment of applying an underfill resin to a substrate.

Figure 5 shows another embodiment for the bonding of the chip bump and the substrate pad using the underfill resin and ultrasonic waves according to the present invention.

6A and 6B illustrate another embodiment of the bonding between the chip pad and the substrate pad using the underfill resin and the ultrasonic wave according to the present invention.

The present invention relates to an ultrasonic bonding method of a semiconductor, in particular, an underfill resin for improving bonding strength and electrical properties during bonding between homogeneous or dissimilar materials in a bonding method of a metal bump of a display driving chip and an LSI semiconductor chip and a pad of a substrate. The ultrasonic bonding method using the coating and curing of the.

The flip chip mounting method using the metal bump of the conventional semiconductor chip is largely used in three ways.

First, the thermosetting insulating resin is applied to the insulating substrate on which the pad is formed, and the position of the insulating substrate and the semiconductor element are aligned and matched. Then, a load is applied to contact the electrodes or bumps of the semiconductor element with the conductor wiring of the insulating substrate to make electrical contact. There is a mounting method to realize the bonding strength by curing the insulating resin after the signal can be applied.

Secondly, the pads of the substrate and the bumps of the semiconductor chip are aligned using the conductive particle anisotropic conductive adhesive having conductive particles inserted into the insulating resin sheet, and then anisotropic conductive adhesive tape is inserted between the bumps and the pads. The resin part of the anisotropic conductive resin, which is tape-shaped, is bonded by heat and is bonded to the bumps formed on the chip by applying pressure to the chip while heating. When placed between the bump and the pad of the chip, the conductive particles deform simultaneously with the contact between the two electrodes due to the vertical pressure, thereby electrically connecting the bump of the chip and the pad of the substrate.

Third, there is a mounting method in which the metal precious metal constituting the bumps formed on the chip and the pad portion of the substrate is directly connected by metal-metal bonding while applying horizontal and vertical loads of ultrasonic waves. In this case, direct bonding is performed by mutual deformation between metals and mutual diffusion of metal particles (atoms), thereby implementing electrical signals and bonding forces. In this case, after the direct ultrasonic bonding, the underfill resin may be applied by using a side fill method using a capillary phenomenon between the substrate and the chip, thereby improving bonding strength and reliability.

In the case of the bonding method using the insulating resin, which is the first method, it is impossible to raise the heating temperature due to the heat resistance of the resin used as the underfill resin, and in practice, the bonding between the semiconductor bump and the substrate pad is forced by the vertical load between the interfaces. There is a disadvantage that the contact resistance is very high in the state that only the bay is made.

In addition, the metal-metal contact cannot be made perfectly by the simple vertical pressure while the underfill resin is previously applied while completely removing the resin present between the bumps of the chip and the electrode pad. In this case, there may be a problem in the normal operation of the circuit of the chip, and the power consumption increases due to the resistance of the contact portion.

In addition, when the thermal shock and durability temperature tests are performed, there is a high possibility of a problem in reliability due to the influence of the resin on the bumps of the chip and the electrode pad.

In the case of using an anisotropic conductive resin, which is the second method, the principle of the mounting is to enable electrical signal transmission between the bumps of the semiconductor chip and the substrate pads by the conductive particles contained in the resin. Since it is proportional to the size and amount of the particles, if the size and amount of particles existing between the bump and the pad are not sufficient, the contact area between the actual bump and the pad decreases and the contact resistance increases.

In addition, the pitch of chip bumps has been reduced to 20 micro areas due to the recent enhancement of the functionality of semiconductor chips, reducing the probability of the presence of conductive particles evenly between the bumps and the pads. Failure to do so increases the likelihood of unstable electrical characteristics in the overall mounting process.

In addition, the mounting method using a chip bonding method using a double insulating resin and an anisotropic conductive resin has a problem in that deterioration is remarkable in various reliability tests after being exposed to a high humidity environment, resulting in poor reliability.

In the case of the method of directly bonding bumps and pads by using ultrasonic waves, which is the third method, since the bumps and pads are directly bonded to each other, the bonding state is maintained in the best state, but in the general process, the side peel method is performed after the bonding process to improve reliability. The method of filling resin using is used. In this method, when the size of the chip is large or when the gap between the chip and the substrate is reduced, the inflow of the resin is not uniform and the air layer remains, which increases the possibility of void defects.

These void defects are also very likely to lead to mounting failure because they cause a poor reliability in high temperature, high humidity environment and temperature cycle tests. When the gap between the chip and the substrate is extremely reduced, it may occur that the inflow of the resin between the chip and the substrate becomes impossible depending on the viscosity state of the resin. In addition, in the case of the bonding process using the ultrasonic method, the bump and pad materials applicable to this process are very limited. Currently, only the Au-Au bonding method is known as a practical method. In addition, it is known that a bonding method between dissimilar metals such as Au-Al and Au-Cr or metal-conductive inorganic materials such as Au-ITO is impossible.

The technical problem to be achieved by the present invention is to first apply the underfill resin to the substrate, and then directly bonded the substrate and the pad by using the horizontal and vertical load of the bumps and the pad of the semiconductor chip using ultrasonic horizontal and electrical signals through a low contact resistance It is to provide a bonding method comprising a step of securing the bonding strength and at the same time to secure the bonding strength and reliability by curing the underfill resin.

According to an aspect of the present invention, there is provided a method of bonding chip bumps and substrate pads using underfill resin and ultrasonic waves, the method including: (a) a plasma treatment step for cleaning conductive pads formed on a substrate; (b) applying an underfill resin to a pad of the substrate being cleaned using a dispenser; (c) aligning the substrate on which the underfill resin is applied and the chip on which stud bumps or flat bumps are formed by using an ultrasonic head; (d) applying a horizontal and vertical load through the ultrasonic head to the top of the chip after the alignment to induce deformation between the bump and the pad to induce direct bonding; And (e) curing the underfill resin using ultrasonic energy simultaneously with the direct bonding of the bumps and the pads.

According to an aspect of the present invention, there is provided a method of bonding chip bumps and substrate pads using underfill resin and ultrasonic waves, the method including: (a) a plasma treatment step for cleaning conductive pads formed on a substrate; (b) aligning the chip on which the substrate and the stud bump or flat bump are formed by using an ultrasonic head; (c) applying the underfill resin after the alignment according to step (b) using a dispenser; (d) inducing deformation between the bump and the pad by applying horizontal and vertical loads through the ultrasonic head to induce direct bonding; And (e) curing the underfill resin using ultrasonic energy simultaneously with the direct bonding of the bumps and the pads.

In addition, the substrate pad is characterized in that composed of at least one material of Au, Cr, Al, Sn.

In addition, the stud bump is characterized in that composed of at least one material of Au, Cr, Al, Sn.

In addition, the flat bump is characterized in that composed of at least one material of Au, Cr, Al, Sn.

In addition, the substrate is characterized in that any one of ceramic, hard PCB, flexible substrate, glass.

In addition, the pad formed on the glass substrate is characterized in that formed of at least one material of ITO, Cr.

In addition, the underfill resin is characterized in that the curing temperature of the resin is 50-160 ℃.

In addition, the application of the underfill resin is characterized in that using any one method of dispenser, screen printing.

In addition, the ultrasonic head is characterized in that the ultrasonic frequency applied to the chip maintains a 50 to 150 KHz region.

In addition, the curing method of the underfill resin in the step (e) is characterized by using a method of artificially applying thermal energy to the substrate during the bonding process to induce the curing of the resin at the same time bonding.

In addition, the curing method of the underfill resin in the step (e) is characterized by using a method of inducing the curing of the resin by applying heat after completion of the bonding operation of the bump and the pad.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

1 shows an embodiment of the bonding of the chip bump and the substrate pad using the underfill resin and ultrasonic waves according to the present invention, the substrate (1), the substrate pad (2), the underfill resin (3), display driving and It consists of a semiconductor LSI chip 5, a chip pad (electrode) 6, a chip bump 7 and an ultrasonic head 8.

FIG. 1 illustrates an embodiment of an ultrasonic bonding method using an application and curing of an underfill resin for improving bonding strength and electrical properties of bonding between homogeneous or heterogeneous materials. First, a conductive pad 2 formed on a substrate 1 is illustrated. Plasma treatment for cleaning the substrate, and the underfill resin 3 is applied to the cleaned substrate pad 2 using a dispenser.

The pad 2 of the substrate is composed of Au, Cr, Al, and Sn.

The substrate 1 on which the underfill resin 3 is applied is aligned with the chips 5 on which the stud bumps or the flat bumps 7 are formed, using the ultrasonic head 8, and the upper ends of the aligned chips 5. Horizontal and vertical loads are applied through the ultrasonic head 8 to induce deformation between the chip bumps 7 and the substrate pads 2 to induce direct bonding.

The stud bump is composed of Au, Cr, Al, Sn and the like, the flat bump is composed of Au, Cr, Al, Sn and the like.

In order to bond the substrate 1 coated with the underfill resin 3 to the chip 5, the chip bumps 7 and the substrate pads 2 are aligned, and the chip electrode 6 is formed using the ultrasonic head 8. The chip bumps 7 formed thereon and the substrate pad 2 are bonded to each other.

In this case, the bumps 7 formed on the chip are deformed and bonded at the same time by the ultrasonic horizontal vibration and the vertical load. In addition, the thermal energy corresponding to the energy is applied to the substrate by the ultrasonic energy applied to the bonding, so that the temperature of the substrate is raised, and the underfill resin 3 is cured at the same time as the bonding.

The shape of the chip bumps 7 used at this time is irrespective of the shape of the stud bumps or the flat bumps. The material of the bonding of the chip bumps 7 and the substrate pad 2 includes metals and conductive inorganic materials. Representative metals may be Au-Au or Au-Cr, Au-ITO, Au-Al and the like.

In the present invention, the material of the substrate includes all substrates such as ceramic substrates, hard PCBs, flexible PCBs, and glass. In order to maximize the method at the time of bonding may be carried out by the ultrasonic method while applying thermal energy to the substrate (1). Moreover, according to the method, ultrasonic bonding may be performed first and heat may be applied as a post treatment to cure the underfill resin 3.

As another method of curing the underfill resin 3, thermal energy is artificially applied to the substrate 1 during the bonding process to induce curing of the underfill resin 3 at the same time as the bonding, or the chip bump 7 and the substrate. The method of inducing hardening of the underfill resin 3 by using heat after completion | finish of the bonding operation | work of the pad 2 is also used.

2 illustrates an embodiment of applying an underfill resin to a substrate.

First, the top end of the substrate pad 2 is cleaned in order to secure the ease of ultrasonic bonding. The cleaning operation removes the organic material and the oxide film present in the pad portion through argon or nitrogen plasma treatment.

Then, the underfill resin 3 is applied to the substrate pad 2 using the dispenser 4.

3 shows a bonding process by deformation of the substrate pad 2 and the stud bump 7 of the chip.

As shown in FIG. 3, the shape of the bump is changed by the horizontal and vertical loads of the ultrasonic waves, and the direct bonding with the pad is made, and the underfill resin 3 already exists between the bump 7 and the pad 2 by deformation. Is physically pushed out as the bonding area of the bump 7 and the pad 2 becomes wider. Under this principle, since the underfill resin 3 does not exist at the junction of the bump 7 and the pad 2, the bonding between the hetero pads having a low contact resistance is possible.

4 illustrates another embodiment of applying an underfill resin to a substrate.

As shown in FIG. 4, the plasma pad is cleaned on the substrate pad 2 to form bumps 7 having irregularities or plates, and then the underfill resin 3 is applied using the dispenser 4.

Figure 5 shows another embodiment for the bonding of the chip bump and the substrate pad using the underfill resin and ultrasonic waves according to the present invention.

FIG. 5 is an embodiment bonded using the underfill resin coating method of FIG. 4. As illustrated in FIG. 5, bumps 7 formed on the substrate pad 2 and bumps are not formed on the chip pads 6. Bonding of the chip pad 6 is performed using the ultrasonic head 8. At this time, by using the ultrasonic head 8, the ultrasonic horizontal and vertical loads are applied to the upper end of the chip, and bonding is performed by deformation of the bump 7 formed on the pad 2 of the substrate.

At this time, the underfill resin 3 present between the bump 7 and the substrate pad 2 has no residual resin at the joint due to bump deformation due to ultrasonic horizontal and vertical loads, and resin curing is performed by ultrasonic energy. .

For the effect of the invention, the thermal energy may be separately applied to the substrate during ultrasonic bonding, and after the ultrasonic bonding, heat treatment may be performed for curing the resin.

6A and 6B illustrate another embodiment of the bonding between the chip pad and the substrate pad using the underfill resin and the ultrasonic wave according to the present invention.

As shown in FIG. 6A, the substrate pad 2 and the chip bump 7 are first aligned at intervals of several tens of microns.

Then, as shown in FIG. 6B, the underfill resin 3 is filled by the side peel method, and then the bump and the pad are bonded using the ultrasonic bonding method.

Therefore, the resin filled between the pads is pushed out by the horizontal and vertical load of the ultrasonic head, so that there is no resin between the pads. At this time, the deformation of the bump occurs due to the vertical and horizontal vibration of the ultrasonic wave. Is done. In the bonding process, curing by ultrasonic waves may occur, and the substrate may be heated or bonded to cure the resin, and then, if necessary, heat treatment may be performed for curing the underfill resin.

As described above, the present invention has been described with reference to the embodiments illustrated in the drawings, which are merely exemplary, and it should be understood by those skilled in the art that various modifications and equivalent other embodiments are possible. will be. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

According to the present invention, it is possible to bond not only the existing Au-Au bonding but also heterometal bonding such as Au-Cr, Au-Al, and conductive inorganic materials such as Au-ITO by the bonding method using ultrasonic wave and underfill resin, Joining is possible.

In addition, since there is no possibility of underfill resin remaining due to ultrasonic vibration in the vertical / horizontal direction at the bonding interface, it is possible to secure low contact resistance between the board and the chip, which greatly improves the electrical properties and hardens the resin at the same time as bonding. As a result, reliability also has an improved effect.

Claims (12)

Bonding method of curing the underfill resin by applying epoxy resin on the substrate and aligning the pads formed on the resin pad and the bumps formed on the display driving LSI and the semiconductor chip. To (a) plasma processing for cleaning conductive pads formed on the substrate; (b) applying an underfill resin having a curing temperature of 50 ° C. to 160 ° C. to a pad of the substrate to be cleaned using a dispenser; (c) aligning the substrate on which the underfill resin is applied and the chip on which the flat bump is formed by using an ultrasonic head; (d) applying a horizontal and vertical load through the ultrasonic head to the top of the chip after the alignment to induce deformation between the bump and the pad to induce direct bonding; And (e) a step of hardening the underfill resin using ultrasonic energy at the same time as the direct bonding of the bump and the pad; bonding method of the chip bump and the substrate pad using the underfill resin and ultrasonic waves. Bonding method of curing the underfill resin by applying epoxy resin on the substrate and aligning the pads formed on the resin pad and the bumps formed on the display driving LSI and the semiconductor chip. To (a) plasma processing for cleaning conductive pads formed on the substrate; (b) aligning the chip on which the substrate and the flat bump are formed by using an ultrasonic head; (c) applying an underfill resin having a curing temperature of 50 ° C. to 160 ° C. after the alignment by the step (b) using a dispenser; (d) inducing deformation between the bump and the pad by applying horizontal and vertical loads through the ultrasonic head to induce direct bonding; And (e) a step of hardening the underfill resin using ultrasonic energy at the same time as the direct bonding of the bump and the pad; bonding method of the chip bump and the substrate pad using the underfill resin and ultrasonic waves. The method of claim 1, wherein the substrate pad A method of bonding chip bumps and substrate pads using an underfill resin and ultrasonic waves comprising at least one of Au, Cr, Al, and Sn. delete The flat bump of claim 1 or 2, wherein the flat bump A method of bonding chip bumps and substrate pads using an underfill resin and ultrasonic waves comprising at least one of Au, Cr, Al, and Sn. The method of claim 1 or 2, wherein the substrate A method of bonding chip bumps and substrate pads using underfill resin and ultrasonic waves, characterized in that any one of ceramic, hard PCB, flexible substrate, and glass. The pad of claim 6, wherein the pad is formed on the glass substrate. A method of bonding chip bumps and substrate pads using an underfill resin and ultrasonic waves, wherein the underfill resin is formed of at least one of ITO and Cr. delete The method of claim 1 or 2, wherein the application of the underfill resin is A method for bonding chip bumps and substrate pads using an underfill resin and ultrasonic waves, wherein any one of dispensers and screen printing is used. The method of claim 1, wherein the ultrasonic head is A method for bonding chip bumps and substrate pads using underfill resin and ultrasonic waves, characterized in that the ultrasonic frequency applied to the chip is maintained at 50 to 150 KHz. According to claim 1 or 2, wherein the curing method of the underfill resin in the step (e) A method for bonding chip bumps and substrate pads using an underfill resin and ultrasonic waves, wherein a method of artificially applying thermal energy to a substrate during the bonding process to induce curing of the resin at the same time as bonding. According to claim 1 or 2, wherein the curing method of the underfill resin in the step (e) A method for bonding chip bumps and substrate pads using an underfill resin and ultrasonic waves, wherein a method of inducing hardening of the resin is applied by applying heat after completion of bonding of the bumps and the pads.

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