JPH11135530A - Semiconductor chip and semiconductor device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the connection strength of an end part electrode bump by making the rigidity of the end part electrode bump to be larger than that of a central electrode bump in an anisotropic conductive film method for placing resin containing conductive particles between a glass substrate and a semiconductor chip and pressing it with a heated pressing head so as to connect them. SOLUTION: The yield stress of the material of the end part electrode bumps 3 is set to be larger than that of the other electrode bump 2 by changing plating fluid for forming the electrode bumps. The difference between the elastic deformation quantity of the glass substrate 6 by the load of the pressing head 6 between the center of the semiconductor chip 1 and end parts becomes small. Thus, the crush quantities of the electrodes 2 and 3 become almost similar and a recessed part is eliminated by the restoration of the elastic deformation of the glass substrate 4 in a state where the pressing head 6 is removed. Since tensile stress does not occur in the end part electrode bumps 3, the connection reliability of the end part electrode bumps is prevented from deteriorating.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor chip and a semiconductor device using the semiconductor chip.

[0002]

2. Description of the Related Art There is a method for connecting an electrode bump on a semiconductor chip to an electrode on a wiring substrate such as a glass substrate by using a resin containing conductive particles. This method is called an anisotropic conductive film method or the like. Hereinafter, this method will be described by the Hybrid Microelectronics Association, published by the Industrial Research Institute, pages 83 to 84 of the Basic Course of Electronics Packaging Technology, and published by the Technical Information Association, bare chip packaging centering on COB and TOB packaging-latest technology development and reliability Countermeasures-Chapter 2, 4
Knot, connection technology using conductive adhesive (pages 77-85)
And Chapter 8, Section 4, LCD Panel Mounting and Reliability Technology (327
To page 335).

FIGS. 2A and 2B show an example of this semiconductor chip.
Shown in FIG. 2A is a front view, and FIG. 2B is a plan view of the lower side. A large number of gold electrode bumps 2, 2a, 2b are formed on the surface of the semiconductor chip 1 on which elements are formed (element surface 7). I have. FIGS. 3A and 3B show a method of connecting the semiconductor chip 1 to the glass substrate 4. In FIG. 3, the dimension of the semiconductor chip 1 in the direction perpendicular to the element surface 7 is drawn in comparison with FIGS. 2A and 2B in order to facilitate understanding of the problem.

A resin 5 containing conductive particles is placed between a glass substrate 4 and a semiconductor chip 1 placed on a table 9, and a back surface 8 of the semiconductor chip 1 is pressed by a heated pressure bonding head 6. The resin 5 is liquefied by heating and moves around the electrode bumps 2, 2a, 2b, and the conductive particles between the electrode 10 on the glass substrate and the electrode bumps 2, 2a, 2b on the semiconductor chip 1 are removed from the electrode 10 and the electrode bumps. The electrical connection between the two is made by digging into 2, 2a and 2b. The resin 5 hardens after being liquefied, and mechanically joins the glass substrate 4 and the semiconductor chip 1. FIG. 4 is a diagram showing this connection state.

[0005]

The state of the prior art will be described below by analyzing in detail the deformation state of each member in the connecting step. Actually, the electrode bumps 2, 2a, 2b are crushed by the load of the pressure bonding head 6, and the height is reduced. FIG.
FIG. 4 is a diagram showing a state in which the pressure bonding head 6 is under load. FIG.
At this time, the load of the pressure bonding head 6 is transmitted to the glass substrate 4 by the electrode bumps 2, 2a, 2b at this time, and the glass substrate 4 is also slightly dented by elastic deformation. This concave shape is deep in the center of the semiconductor chip 1,
Since the end portions are shallow, the shape of the electrode bumps 2 after deformation is different depending on where the center electrode bumps 2 are high and the end electrode bumps 2 are low.

FIG. 6 shows a state where the pressure bonding head 6 is removed after the resin 5 is cured. When the elastic deformation of the glass substrate 4 returns to its original state, the dent disappears, and the surface of the glass substrate 4 becomes substantially flat. At this time, the return amount of the elastic deformation of the glass substrate 4 is large in the central electrode bump 2a and small in the end electrode bump 2b. A compressive stress and a tensile stress are generated in the end electrode bump 2b. This tensile stress may cause the end electrode bumps 2b to separate from the electrodes 10 of the glass substrate 4. As described above, the conventional semiconductor chips and semiconductor devices have a problem in that the connection reliability of the electrode bumps is poor, and particularly the connection strength of the end electrode bumps is low.

[0007]

The above problem is caused by the fact that the load of the pressure bonding head 6 causes a depression due to the elastic deformation of the glass substrate 4 and the depth of the depression varies depending on the position of the electrode bump 2. . The depth of this recess is electrode bump 2
The stress exceeds the yield stress due to the stress-strain relationship of gold of the material of the electrode bump shown in FIG. 7 and shows an example shown in FIG. In comparison, it can be seen that the stress takes an almost constant value with no large difference depending on the strain. Therefore, it can be seen that the stress of the electrode bumps 2, 2a, 2b is almost the same regardless of the position.

In order to quantitatively understand the concave shape due to the elastic deformation of the glass substrate 4, a case where a uniform stress q is applied to a circular region having a radius a on the surface of a semi-infinite body having a Young's modulus E and a Poisson's ratio ν. The results of analyzing the displacement distribution in the direction perpendicular to the surface are quoted from Timoshenko and Goodia, Kiyoshi Kaneda, Elasticity, 4th edition, page 419 (issued by Corona), and are shown in FIG. In the figure, r represents the distance from the center of the circular load area, and V ₀ represents the displacement expressed by the equation (1) at the edge of the circular load area.

[0009]

V ₀ = 4 (1−ν ² ) qa / (πE) (1) The shape of the actual semiconductor chip is not a circle but a rectangular parallelepiped. Although not exactly the same, the tendency of deformation is similar to the result of this analysis even in the case of an actual semiconductor chip, and when the stress is a constant value,
It is expected that the displacement is small at the end of the stress load region and large at the center.

From the above analysis, in order to improve the connection reliability of the end electrode bumps 2b, the amount of depression due to the elastic deformation of the glass substrate 4 due to the load of the pressure bonding head 6 is reduced by the center electrode bumps 2a and the end electrode bumps 2b. It can be seen that it is necessary to be almost the same in 2b.

The uniform dent distribution is caused by the end electrode bump 2b.
Is greater than the rigidity of the center electrode bump 2a. Specific means for changing the rigidity of the electrode bumps include a method of using a material having a different hardness as an electrode bump material, a method of changing a plating solution as shown in the example below, and a method of changing the electrode bump area. There is.

[0012]

1A and 1B show an example of a semiconductor chip according to the present invention. The electrode bumps are formed by electroplating, but by changing the plating solution, the yield stress of the material of the end electrode bumps 3 is reduced by the other electrode bumps 2.
Is larger than the yield stress. FIG. 9 shows how the semiconductor chip of the present invention is connected to the glass substrate 4. Since the yield stress of the material of the end electrode bump 3 is higher than that of the other electrode bumps 2, the difference in the amount of elastic deformation of the glass substrate 4 due to the load of the pressure bonding head 6 between the center of the semiconductor chip 1 and the end is small.

For this reason, the crushing amounts of the electrode bumps 2 and 3 are almost the same. FIG. 10 shows a state where the pressure bonding head 6 is removed after the resin 5 is cured. The dent disappears due to the recovery of the elastic deformation of the glass substrate 4, but no tensile stress is generated in the end electrode bumps 3.

FIGS. 11A and 11B show a second example of the semiconductor chip of the present invention. The distance from the center of the semiconductor chip to the electrode bump has the largest area of the end electrode bump. Even when this semiconductor chip is used, since the rigidity of the end electrode bumps 3 is higher than the rigidity of the other electrode bumps 2, the difference in the amount of elastic deformation of the glass substrate 4 between the center of the semiconductor chip 1 and the end is small. Become.

[0015]

According to the semiconductor chip and the semiconductor device of the present invention, the rigidity is increased by the electrode bump having a large distance from the center of the semiconductor chip to the electrode bump. Since the difference due to the position of the dent due to the elastic deformation occurring in the semiconductor device can be reduced, it is possible to provide a semiconductor chip and a semiconductor device in which the connection reliability of the end electrode bump is not particularly reduced.

[Brief description of the drawings]

FIG. 1A is a front view of an embodiment of a semiconductor chip of the present invention.
b is a plan view of FIG. 1a.

FIG. 2A is a front view of an embodiment of a conventional semiconductor chip, and FIG.
2A is a plan view of FIG. 2A.

FIG. 3 is a diagram showing a conventional method for connecting a semiconductor chip to a glass substrate.

FIG. 4 is a diagram showing a semiconductor device formed by connecting a conventional semiconductor chip to a glass substrate.

FIG. 5 is a view showing a deformation caused by a load of a pressure bonding head when a conventional semiconductor chip is connected to a glass substrate.

FIG. 6 is a diagram showing a modification of a conventional semiconductor device formed by connecting a semiconductor chip to a glass substrate when the semiconductor device is completed.

FIG. 7 is a characteristic diagram showing a stress-strain relationship of gold as a material for an electrode bump.

FIG. 8 is a characteristic diagram showing a result of analyzing a surface displacement distribution when a uniform stress is applied to a part of the surface of the semi-infinite body.

FIG. 9 is a view showing a method for connecting a semiconductor chip of the present invention to a glass substrate.

FIG. 10 is a diagram showing a semiconductor device manufactured by connecting a semiconductor chip of the present invention to a glass substrate.

FIG. 11A is a front view of an embodiment of the second semiconductor chip of the present invention. b is a plan view of FIG. 11a.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Semiconductor chip, 2 ... Electrode bump, 2a ... Center electrode bump, 2b, 3 ... End electrode bump, 4 ... Glass substrate,
5: Resin, 6: Pressure bonding head, 7: Element surface of semiconductor chip, 8: Back surface of semiconductor chip, 9: Stand, 10: Electrode.

Claims (1)

[Claims] 1. A semiconductor chip having a plurality of electrode bumps on a surface on which elements are formed, wherein an electrode bump having a large distance from the center of the semiconductor chip to the electrode bump has a small rigidity. And a semiconductor device using the semiconductor chip.