JPH0758112A - Semiconductor device - Google Patents

Abstract

PURPOSE:To form a bump electrode for reducing the occurrence of thermal stresses by forming a bump electrode on an electrode pad by dividing it into a plurality of segments. CONSTITUTION:A metal layer is vapor-deposited on an insulation film 3 where an opening 2 is formed, the metal layer is etching-removed leaving the region covering the opening 2 by using a resist film thereby forming an electrode pad 4. Next, a resist film 7 having the opening which divides the electrode pad 4 into four pieces is pattern-formed, and a bump electrode is grown by plating at four places on the electrode pad 4, and a bump electrode 5 divided into four is formed. And after removing the resist film 7, a rear electrode 6 is formed by spattering on the lower surface of a semiconductor substrate 1. By doing this, thermal stresses acting to the portion between the semiconductor substrate and bump electrode can be relaxed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device, and more particularly to a semiconductor device having bump electrodes.

[0002]

2. Description of the Related Art Conventionally, a semiconductor device of this type, for example, FIG.
In the diode element 21 as shown in FIG. 3, an insulating film 23 of silicon oxide or the like is formed as an opening on a semiconductor substrate 22 on which the element is formed and an opening is formed. , The electrode pad 24 made of a metal layer such as titanium is formed, and the bump electrode 25 made of silver, solder or the like is formed on the electrode pad 24, while the lower surface of the semiconductor substrate 22 is made of silver, gold, nickel or the like. The back electrode 26 is formed.

For example, as shown in FIG. 6, the diode element 21 as described above is sandwiched between a pair of lead terminals 27a and 27b for external extraction via solder layers 28a and 28b, and the lead terminals 27a and 27b. , 27b except the outer ends thereof, which are resin-molded and assembled. That is,
The bump electrode 25 and the back surface electrode 26 of the diode element 21.
Are connected to the lead terminals 27a and 27b via the solder layers 28a and 28b, respectively.

The diode element 21 is connected to the lead terminal 27.
As a method of connecting to the a and 27b, generally, a solder paste is first applied to a predetermined position of the lead terminal 27b, and the diode element 21 is placed on the solder paste and the back electrode 26 thereof.
Die-bonding, and then the lead terminal 2
This is performed by applying a solder paste to a predetermined position of 7a, stacking it from the upper surface of the semiconductor substrate 21 and stacking the solder paste and the bump electrode 25, and then curing and fixing the solder paste. .

[0005]

However, the bump electrode 25 and the electrode pad 2 for the semiconductor substrate 22 are not provided.
In proportion to the increase in the formation area (contact area) of the electrode layer of No. 4, the thermal stress due to the difference in the coefficient of thermal expansion between the electrode layer and the semiconductor substrate 22 increases. Actually, the layer thickness of the electrode pad 24 is very thin and much smaller than the thickness of the bump electrode 25, so that the formation area of the bump electrode 25 is substantially increased in proportion to the temperature cycle test and When the diode element 21 is subjected to excessive thermal stress during use at high temperatures, thermal stress is generated due to the difference in coefficient of thermal expansion between the bump electrode 25 and the semiconductor substrate 22, and the bump electrode 25 and the semiconductor substrate 22. There is a problem that there is a high risk that a position where the bump electrode 25 is formed or a crack is generated at the contact interface with 22.

On the other hand, when the bump electrode 25 is connected to the lead terminal 27a through the solder layer 28a as described above, in the assembly process such as contact between the bump electrode 25 and the solder paste, curing of the solder paste, etc. However, the following problems occur. On the insulating film 23 exposed on the periphery of the bump electrode 25 of the diode element 21, for example, the electrode pad 2 is formed when the electrode pad 24 is formed.
The metal as the material of No. 4 adheres, or the chips of the back surface electrode 26 adhere when dividing the semiconductor wafer having a plurality of diode elements 21 into individual diode elements 21 by dicing. There is a risk of foreign matter from the system. When the metal-based foreign matter is present on the insulating film 23, the foreign matter on the insulating film 23, which is an unnecessary portion, is connected when the bump electrode 25 of the diode element 21 is connected to the lead terminal 27a by using a solder paste. If the solder adheres to the side surface of the diode element 21 and a short circuit occurs, there is a risk of causing a short circuit defect.

Therefore, in order to reduce the above problem, the bump electrode 25 is formed high to increase the distance between the insulating film 23 and the solder layer 28a to reduce the adhesion of solder to the insulating film 23. It is possible to do it.

However, when the bump electrode 25 is formed high, the bump electrode 25 and the semiconductor substrate 2 as described above are formed.
The thermal stress generated due to the difference in the coefficient of thermal expansion from that of No. 2 is further increased, and the risk of the displacement or crack of the bump electrode formation position at the contact interface between the bump electrode 25 and the semiconductor substrate 22 is further increased. The bump electrode 25 cannot be made high enough to solve the above problem.

An object of the present invention is to provide a bump electrode forming technique capable of reducing the occurrence of thermal stress on a semiconductor substrate.

[0010]

As a result of intensive studies to achieve the above object, the present inventor has made a plurality of bump electrodes in a semiconductor device on a single electrode pad formed on a semiconductor substrate. It was found that the thermal stress acting between the electrode layer and the semiconductor substrate can be effectively relaxed when the electrodes are divided and formed, and the defects due to the thermal stress can be further reduced during the temperature cycle test or the operation.

That is, according to the present invention, in a semiconductor device having a bump electrode on an electrode pad formed on a semiconductor substrate, the bump electrode on the electrode pad is divided into a plurality of parts. The present invention relates to a semiconductor device.

[0012]

Since the bump electrode formed by dividing into a plurality of pieces is used as one electrode, the contact area of the bump electrode divided into a plurality of pieces with each semiconductor substrate becomes small. Therefore, while maintaining an area sufficient for connection with an external terminal, wiring, etc. as an electrode, the thermal stress acting between the bump electrode and the semiconductor substrate when a thermal stress is applied is dispersed to the plurality of bump electrodes, As a result, the thermal stress acting on each bump electrode can be made small enough to be absorbed by each bump electrode.

[0013]

EXAMPLES The features of the present invention will be described in more detail below with reference to examples.

FIGS. 1 and 2 show an embodiment in which the bump electrode in the diode element is divided into four and formed. As shown in these figures, the diode element of the present embodiment includes a semiconductor substrate 1 on which the element is formed, and the semiconductor substrate 1
An insulating film 3 made of silicon oxide or the like having an opening 2 corresponding to a region where a bump electrode is to be formed, and silver as a base of the bump electrode formed so as to cover the opening 2 of the insulating film 3. Electrode pads 4 made of a metal layer of gold, titanium, nickel, etc., four bump electrodes 5 formed on the electrode pads 4, and silver, gold, nickel formed on the lower surface of the semiconductor substrate 1. And a back electrode 6 made of a metal such as.

The above diode element can be manufactured, for example, as follows. As shown in FIG.
An insulating film 3 is formed on the semiconductor substrate 1 by thermal oxidation or a CVD method.
Is formed, a resist film having a predetermined pattern is formed on the insulating film 3, the insulating film 3 is etched to form the opening 2, and the resist film is removed.

Next, as shown in FIG. 3B, a metal layer is vapor-deposited on the insulating film 3 in which the opening 2 is formed, and the opening 2 is formed by using the metal layer with a resist film. The electrode pad 4 is formed by etching away the region to cover.

Next, as shown in FIG. 3 (c), a resist film 7 (see FIG. 4) having an opening for dividing the electrode pad 4 into four is patterned, and as shown in FIG. 3 (d). ,
Bump electrodes are plated and grown at four locations on the electrode pad 4 to form four divided bump electrodes 5. Then, after removing the resist film 7, the back surface electrode 6 is formed on the lower surface of the semiconductor substrate 1 by sputtering or the like.

In the above embodiment, the bump electrode is divided into four, but the number of divisions of the bump electrode may be appropriately selected depending on the area and height of the bump electrode. Also,
Although the case where the present invention is applied to a diode element has been described above, the present invention is not limited to this, and an IC, a hybrid I
It can be applied to all semiconductor devices such as C and transistors.

[0019]

According to the present invention, since the thermal stress acting between the semiconductor substrate and the bump electrode can be relaxed, when the semiconductor device is subjected to the thermal stress, the bump electrode is formed between the bump electrode and the semiconductor substrate. It is possible to extremely reduce the occurrence of misalignment and cracks.

Further, since the contact area of each divided bump electrode with the semiconductor substrate can be reduced and the thermal stress can be dispersed, the height of the bump electrode can be made higher than in the prior art.

Furthermore, since the bump electrodes are formed separately, when connecting the bump electrodes to an external terminal or the like by using solder or the like, solder or the like flows between the bump electrodes to improve the connection strength and to ensure a stable connection. It can be carried out.

As described above, the semiconductor device of the present invention is structurally extremely excellent in heat resistance and capable of withstanding the thermal stress by raising the bump electrode.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a diode element of an example.

FIG. 2 is a top view of FIG.

FIG. 3 is a cross-sectional view illustrating a manufacturing process of the diode element of FIG.

FIG. 4 is a plan view of a bump electrode forming resist pattern used in an example.

FIG. 5 is a cross-sectional view of a conventional diode element.

FIG. 6 is a cross-sectional view showing a state in which a conventional diode element is connected to a lead terminal.

[Explanation of symbols]

 1 Semiconductor Substrate 2 Opening 3 Insulating Film 4 Electrode Pad 5 Bump Electrode 6 Backside Electrode 7 Resist Film

Claims (1)

[Claims] 1. A semiconductor device having a bump electrode on an electrode pad formed on a semiconductor substrate, wherein the bump electrode on the electrode pad is divided into a plurality of parts and formed.