JP2762813B2 - Connection method of semiconductor chip - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of connecting a semiconductor chip using a connecting member used for electrically connecting opposing electrodes via conductive particles and for bonding and fixing the electrodes.

[0002]

2. Description of the Related Art A method of directly connecting electrodes of a semiconductor chip such as an IC, an LSI, and a chip capacitor to a substrate circuit formed by forming a predetermined circuit on a surface of a substrate made of glass, synthetic resin, metal or the like, or As a method of connecting so-called high-density electrodes, such as connection between substrate circuits, there is known a method of connecting between these opposing electrodes (or circuits) via a connecting member mainly composed of an adhesive.
As the connection member, an anisotropic conductive adhesive in which conductive particles such as carbon, nickel, solder and plastic particles having a conductive layer formed on the surface are mixed in an insulating adhesive is used. Typically, electrical connection is obtained. In this case, in the connection method using an adhesive using conductive particles, when the number of particles on an electrode is increased in order to improve the reliability of electrical connection, particles are present at a high density between adjacent electrodes. As a result, the insulating property becomes insufficient, and a problem occurs in maintaining the insulating property such as a leak or a short circuit. Conversely, when the number of particles is reduced, the number of particles on the electrode becomes insufficient and connection reliability is reduced. This contradictory tendency is further promoted by the phenomenon that the conductive particles flow out of the electrode together with the adhesive due to heating and pressurizing at the time of connection, and it is difficult to cope with a high-density connection such as a pitch of 90 μm or less. It has become. For the purpose of breaking the road in the adhesive method, for example, Japanese Patent Laid-Open Publication No.
As disclosed in Japanese Unexamined Patent Publication No. 6237 and Japanese Unexamined Patent Publication No. Sho 63-289824, an attempt is made to form a conductive adhesive only on the protruding electrode and connect it to the substrate circuit, or to conduct conductive only on a portion to be provided with conductivity. Attempts have been made with conductive particle uneven distribution type anisotropic conductive adhesive films in which particles are arranged.

[0003]

Problems to be Solved by the Invention
Also in the methods of JP-A-37-287 and JP-A-63-289824, if the thickness of the adhesive layer is too large, the flow rate of the adhesive increases, so that the conductive particles flow out of the electrodes and cause poor conduction. Easy to wake up. Even when the thickness is small, the connection thickness of the electrode portion becomes the smallest after connection, so that the flow of the adhesive in the connection process is the largest in this portion, and a part of the conductive particles arranged in the electrode portion is around the portion. There was a danger that a short circuit would occur due to the conductive particles that were extruded and retained between the electrodes. An object of the present invention is to provide a method for connecting a semiconductor chip using a conductive particle unevenly distributed anisotropic conductive adhesive film, which is capable of connecting a high-density electrode excellent in reliability of micro-area connection and inter-electrode insulation. To offer.

[0004]

SUMMARY OF THE INVENTION The present invention relates to a semiconductor chip connection system in which conductive particles which are deformable under pressure are interposed between a protruding electrode of a semiconductor chip and a substrate circuit. Between the forming surface and the substrate circuit, the thickness is equal to or less than the sum of the average height of the protruding electrode, the average particle size of the conductive particles, and the height of the circuit electrode, and the average height of each of the protruding electrode, the conductive particles, and the circuit electrode after connection. The semiconductor chip and the substrate circuit are heated and pressed with an insulating adhesive having a thickness equal to or greater than the sum of the thickness, and the conductive particles existing around the protruding electrode portion are pushed to the periphery of the semiconductor chip, and the insulating property between adjacent electrodes is It is characterized by holding.

[0005] The pressure-deformable particles used in the present invention are particles that can be deformed under pressure or under heat and pressure. For example, particles obtained by forming a metal layer on the surface of plastic particles such as polystyrene or solder. Heat-fusible metal particles can be applied to the above. Further, as the insulating adhesive, for example, a thermoplastic material used for an adhesive sheet or the like and a material which is curable by heat or light can be widely applied. The use of a curable material is preferred because of its excellent heat resistance and moisture resistance after connection. Among them, epoxy adhesives can be more preferably applied because they can be cured in a short time, have good connection workability, and have excellent adhesiveness in terms of molecular structure.

An example of connection between a semiconductor chip and a circuit board using a conductive particle uneven distribution type anisotropic conductive adhesive film will be described below with reference to the drawings. 1, 2 and 3 show the state of each stage of the connection. At each stage, a top view with the semiconductor chip side as the top face and cross-sectional views along XX ', YY' and ZZ 'in each top view are shown. Each top view is drawn through the semiconductor chip so that the appearance of the protruding electrodes and the conductive particles of the semiconductor chip can be seen. FIG. 1 shows a state in which the protruding electrode and the circuit electrode are aligned with each other via the conductive particles and the insulating adhesive layer. At this time, the conductive particles are preliminarily bonded and fixed to the protruding electrode surface or the circuit electrode surface, or are unevenly distributed only between the protruding electrode and the circuit electrode by a method such as disposing the particles at the electrode contact portion of the adhesive layer. Keep it. FIG.
These figures show a state where the protruding electrode and the circuit electrode are electrically connected via conductive particles by pressurizing them. At that time, the adhesive compressed by the protruding electrode and the circuit electrode flows to the periphery thereof, and accordingly, a part of the conductive particles is also dispersed to the periphery of the electrode. The conductive particles remaining on the electrode portion connect the circuit by being sandwiched between the protruding electrode and the circuit electrode. However, the conductive particles dispersed in the surrounding area may cause short-circuiting due to contact between the particles.
FIG. 3 shows a state where the state of FIG. 2 is further pressurized. The pressure-deformable conductive particles sandwiched between the protruding electrode and the circuit electrode are crushed by pressure, thereby further reducing the gap between the semiconductor chip and the circuit, and the adhesive is compressed by the entire surface of the circuit board and the back surface of the semiconductor chip. You. Then, a flow of the adhesive is generated from the central portion of the semiconductor chip to the peripheral portion, and the excessive conductive particles remaining between the protruding electrodes are wiped out to the outside, and as a result, a short circuit of the circuit is prevented. By performing heating or light irradiation in this state and curing and fixing the adhesive, highly reliable connection can be achieved.

In the present invention, first, it is necessary to use conductive particles which are deformable under pressure, and secondly, it is necessary to make the adhesive layer before connection have an appropriate thickness. That is, when the adhesive layer is thicker than the appropriate thickness, the adhesive flows before the particles are fixed in the step of FIG. 1 and the process proceeds to the step of removing the conductive particles in the step of FIG. Almost no particles remain. Circuits connected in such a state are likely to be open. In order to fix the conductive particles to the electrodes, it is necessary that the thickness of the adhesive layer is smaller than the sum of the height of the protruding electrodes of the semiconductor chip, the diameter of the conductive particles, and the height of the circuit electrodes. On the other hand, if the adhesive layer is too thin, the connection is terminated at the stage of FIG. 2 without causing the adhesive layer to flow, and there is a high risk of short-circuiting between the protruding electrodes. In order to perform the conductive particle elimination process of FIG. 3, the thickness of the adhesive layer needs to be greater than the sum of the height of the protruding electrode, the thickness of the crushed conductive particles, and the height of the circuit electrode.

As described above, by setting the thickness of the adhesive layer to a common part of the above two conditions, a highly reliable connection can be easily performed. By the way, FIG.
The step of further applying pressure causes the adhesive to flow from the central portion of the semiconductor chip toward the peripheral portion. The fact that the conductive particles are deformable under pressure makes this possible. Therefore, the flow rate of the adhesive is determined by the particle size of the conductive particles and the degree of deformation thereof. To increase the flow, it is necessary to take measures such as increasing the particle size and increasing the degree of deformation of the particles by heating or the like. However, it is impossible to increase the particle size when performing connection at a fine pitch. Therefore, it is more preferable that the conductive particles that are deformable under pressure are used, and the protruding electrodes of the semiconductor chip are also deformable under pressure. As for the protruding electrodes, the height is desirably larger than the diameter of the conductive particles so that particles can be removed smoothly, and the arrangement is preferably arranged around the semiconductor chip. The insulating property after connection between adjacent electrodes of the present invention may be such that the function of the semiconductor chip is normally exhibited, but is preferably 10 ⁵ Ω or more.

[0009]

According to the present invention, the conductive particles are deformed and held between the protruding electrodes and the circuit electrodes by heating and pressurizing at the time of connection by using the deformable conductive particles. An effective electrical connection is obtained with little outflow to the device. At this time, by optimizing the thickness of the adhesive, the conductive particles existing outside the protruding electrode portion can be heated and pressurized at the time of connection so that the adhesive flows outward from the center point of the semiconductor chip toward the outer periphery of the chip. Move to section. Since the peripheral portion of the chip has a larger area than that between the adjacent electrodes, it is possible to maintain insulation between the adjacent electrodes. As described above, the present invention keeps the conductive particles involved in the electrical connection of the circuit in the necessary portions and removes the excess conductive particles to the outside. The connection reliability of the electrodes can be improved. The conductive particle removing step is performed at the same time as the circuit connecting step. At this time, no special equipment or device is required in addition to the existing connecting device, so that it is a very simple and effective method for connecting a fine circuit.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the sectional view of FIG. 1, the protruding electrodes of the semiconductor chip have a tip area of 100 μm square, a height of 25 μm and a spacing of 3
0 μm, the height of the circuit electrode is 0.2 μm, the particle diameter of the conductive particles is 10 μm, the thickness of the crushed conductive particles after circuit connection in the sectional view of FIG. 3 is 2 μm, and the height of the protruding electrode is 22 μm.
An example of circuit connection when the particle uneven distribution type anisotropic conductive adhesive film having the thickness shown in Table 1 is used when the circuit electrode height is 0.2 μm and the circuit electrode height is 0.2 μm. The protruding electrodes of the semiconductor chip are made of gold, the conductive particles are made of gold plating on the surface of the polystyrene nucleus, and the circuit board is made of glass, and the circuits and the electrodes are plated with gold. An epoxy adhesive containing a latent curing agent was used for the insulating adhesive layer.

[0011]

[Table 1]

The connection method will be described. First, the electrodes of the circuit board are aligned with the group of conductive particles unevenly distributed in the adhesive film (approximately 70 conductive particles are present in the portion corresponding to the electrode) in which the conductive particles are unevenly distributed according to the arrangement of the protruding electrodes of the semiconductor chip. And paste the adhesive film on the circuit board. Since the adhesive film is formed on a release substrate such as Teflon, the adhesive film is heated and pressed at 80 ° C. and 10 kg / cm ² for 5 seconds to peel the substrate, and the substrate is peeled. Next, as shown in FIG. 1, the protruding electrodes of the semiconductor chip are aligned with the circuit electrodes, and one electrode is pressed while the pressure is adjusted to 50 gf per electrode.
The semiconductor chip is bonded and fixed by heating at 90 ° C. for 20 seconds. The average value of the connection resistance when the circuits were connected using the adhesive films having the thicknesses shown in Examples 1 to 3 in Table 1 was 10
～12Omu, insulation resistance between adjacent electrodes is at least 10 ⁹ Omega, the connection resistance average value after 85 ° C. -85% RH2000 hours was slightly elevated and 15～22Omu, insulation resistance 10 ⁹
Ω or more. Therefore, it was found that highly reliable circuit connection was possible with the adhesive films of Examples 1 to 3.
After the connection in Examples 1 to 3, the number of particles on the electrode was 5
There were zero or more.

On the other hand, when the circuit is connected using the adhesive film having the thickness shown in Comparative Example 1, the connection resistance average value is good, increasing only 4Ω before and after the high-temperature and high-humidity test. The resistance is 10 ² Ω and there is no insulation. The reason is that the protruding electrode height of the semiconductor chip after connection is 22 μm,
The sum of the circuit electrode height 0.2 μm and the thickness 2 μm of the conductive particles crushed between the connection electrodes by circuit connection is 24.2 μm.
m, but the thickness of the adhesive film used is 18
3 μm, it was impossible to pressurize the adhesive layer other than the protruding electrode portion of the semiconductor chip, and excess conductive particles accompanying the outflow of the adhesive as shown in FIG. 3 were not eliminated. It is in. Therefore, extra particles that do not participate in circuit connection remain between adjacent electrodes so that they can come into contact with each other,
It is considered that insulation between adjacent electrodes is significantly impaired.
In addition, when circuit connection was performed using the adhesive film having the thickness shown in Comparative Example 2, the insulation resistance was as good as 10 ⁹ Ω or more, but the connection resistance was as large as 10 ³ Ω and the high temperature and high humidity test was performed. Later, the connection resistance value increased significantly and became an open state. This is the height of the projecting electrode 25 μm, the height of the circuit electrode 0.2
The sum of 3 μm and the conductive particle diameter of 10 μm was 35.2 μm, whereas the thickness of the adhesive film used was 41 μm, so the conductive particles were fixed between the protruding electrodes and the circuit electrodes. It is probable that the circuit could not be sufficiently connected because the adhesive flowed out to the outside and the conductive particles in the electrode part were also removed to the outside. As a matter of fact, the number of particles on the electrode was 0 to 5 and was significantly smaller than that of the example.

[0014]

According to the present invention, a highly reliable connection can be made in a system in which conductive particles are localized only in connection electrodes. In addition, since it is possible to connect a system in which conductive particles are arranged not only in the electrode portion but also in a wide area around the electrode portion, the positioning between the adhesive film and the electrode can be performed extremely easily.

[Brief description of the drawings]

FIGS. 1A and 1B are a transparent top view and a cross-sectional view showing a connection state according to the present invention.

FIGS. 2A and 2B are a transparent top view and a cross-sectional view showing a state during connection according to the present invention.

FIGS. 3A and 3B are a transparent top view and a cross-sectional view showing a state after connection according to the present invention. FIGS.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Semiconductor chip 2 Protruding electrode 3 Conductive particle 4 Insulating adhesive 5 Circuit electrode 6 Circuit board

──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Kyohisa Ota 1500 Oji Ogawa, Shimodate City, Ibaraki Pref.Hitachi Chemical Industry Co., Ltd. (58) Field surveyed (Int.Cl. ⁶ , DB name) H01L 21/60 311

Claims (1)

(57) [Claims] In a semiconductor chip connection method in which conductive particles that are deformable under pressure are interposed between a protruding electrode of a semiconductor chip and a substrate circuit, the semiconductor chip is connected between a protruding electrode formation surface of the semiconductor chip and the substrate circuit. The thickness is not more than the sum of the average height of the protruding electrode, the average particle size of the conductive particles, and the height of the circuit electrode,
The semiconductor chip and the substrate circuit are heated and pressurized by interposing an insulating adhesive having a thickness equal to or greater than the average height of each of the protruding electrode, the conductive particles, and the circuit electrode after the connection, thereby maintaining the insulation between the adjacent electrodes. A method for connecting a semiconductor chip, characterized in that: