JPS621249A - Semiconductor device - Google Patents

Abstract

PURPOSE:To prevent the generation of cracks by constituting openings, which are formed to a protective insulating film and from which an aluminum pad as a foundation is exposed, of a plurality of small openings arranged in a plane and shaping a projecting electrode onto the protective insulating film through the openings. CONSTITUTION:An aluminum pad 13 is each exposed in several opening 14a, a barrier metal layer 15 having multilayer structure is formed onto a protective insulating film 14 containing these openings 14a, and a projecting electrode 16 thickly coated with a gold material is shaped onto the layer 15. The projecting electrode 16 is shaped through plating extending over a region containing a plurality of the openings 14a, but the upper surface of plating is formed flatly as a whole though extremely small recessed sections 20 corresponding to the openings 14a are shaped to the upper surface of plating because the openings 14a are small to the thickness of plating, and the upper surface of the projecting electrode 16 is also flattened. Accordingly, even when an inner lead 17 is connected through a thermocompression bonding method, the inner lead 17 is brought into contact uniformly with the projecting electrode 16, thus preventing the deviation or concentration of thermal stress, then obviating the cracks of an insulating film 12 as a foundation and a semiconductor substrate 11.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a semiconductor device, and more particularly to a semiconductor device using a protruding electrode structure for external connection electrodes of a semiconductor chip.

[Conventional technology]

Conventionally, a semiconductor device having a protruding electrode called a bump has a structure in which the protruding electrode is formed of a metal material such as gold on an aluminum pad of a wiring layer on a semiconductor chip.
An adhesive layer or barrier layer is interposed between the protruding electrodes and the aluminum pads in order to enhance their adhesion and prevent diffusion between them. For example, FIGS. 3 and 4 are examples of this, in which an aluminum pad 3 is formed on the insulating film 2 on the main surface of the semiconductor substrate l, a protective insulating film 4 is deposited on it, and a part of it is opened. and Ti--Pt as an adhesive layer and a barrier layer on the exposed aluminum pad 3.
A barrier metal layer 5 having a multilayer structure such as Cr--Cu or the like is formed, and a protruding electrode 6 made of a thick film composite material is formed thereon.

Usually, the protective insulating film 4 is the aluminum pad 3.
This is to utilize the fact that the aluminum pad 3 acts as a stopper during etching when opening the protective insulating film 41, and the protruding electrode 6 is shaped so as to overlap the protective insulating film 4. The structure is such that the periphery of the insulating film 4 overlaps the periphery of the insulating film 4. This is because the etching solution is applied to the aluminum pad 3 from around the protruding electrode 6 serving as a mask when etching the underlying barrier metal layer 5.
This is to prevent the aluminum pad 3 from being damaged by penetrating into the aluminum pad 3.

[Problem that the invention seeks to solve]

In the conventional protruding electrode structure described above, since the protective insulating film 4 and the protruding electrode 6 overlap in their respective peripheral portions, a step is generated around the opening 4a of the protective insulating film 4, and this step is removed by the plating method. It appears on the upper surface of the protruding electrode 6 formed by etching, etc., and has a shape in which the peripheral portion 6a is higher than the central portion.

Therefore, when the inner lead (copper tin-plated lead or gold lead) 7 is connected to the protruding electrode 6 by thermocompression bonding, the peripheral part 6a of the protruding electrode 6 protrudes more than the central part. Thermal stress in the portion 6a is particularly stronger than in other portions, and this stress is directly applied to the protective insulating film 4, etc. directly below, causing cranking to the protective insulating film 4, the insulating film 2 under the aluminum pad 3, and the semiconductor substrate l. generate. The crank under this protruding electrode 6 is the protruding electrode 6
This causes a phenomenon in which the leads 7 are peeled off, so that there is almost no tensile strength, resulting in a problem that the semiconductor device becomes defective before the reliability can be evaluated.

[Means for solving problems]

The semiconductor device of the present invention flattens the upper surface of the protruding electrode to prevent the occurrence of cracks under the protruding electrode, and improves the reliability of the protruding electrode as well as the semiconductor device. The opening exposing the underlying aluminum pad is composed of a plurality of small openings arranged in a plane, and the projecting electrode is formed on the protective insulating film through the opening.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

1 and 2 show an embodiment of the present invention, in which FIG. 1 is a plan view of the protruding electrode 16, and FIG. 2 is an AA view thereof.
FIG. An insulating film 12 is formed on the main surface of a semiconductor substrate 11 made of silicon or the like, and an aluminum pad 13 is formed on it.
is formed in a predetermined pattern, and a protective insulating film 14 is deposited on the aluminum pad 13 so as to cover it. In this protective insulating film 14, a plurality of small openings 14a are arranged in a plane at locations where protruding electrodes are to be formed, and the aluminum pads 13 are exposed in each opening 14a. A barrier metal layer 15 having a multilayer structure such as Ti-Pt or Cr-Cu is formed on the protective insulating film 14 including these openings 14a, and a protruding electrode 16 is formed on the barrier metal layer 15 with a thick layer of composite material. is formed.

In addition, when forming the protruding electrode 16, after coating the entire surface with the barrier metal 15 layer, this is used as a plating electrode, and a thick layer of gold is plated thereon, and this gold is coated with photolithography using a photoresist (not shown). The method of creating patterns using technology is the same as before. Further, using this protruding electrode 16 as a mask, the barrier metal layer 15 is
The same goes for etching. Furthermore, the opening 1
4a is also formed by photolithography technology, but it is important that the size and area of each opening 14a be small compared to the thickness of the protruding electrode 16, and that the periphery of the opening be as tapered as possible. It is preferable to form.

According to the above configuration, the protruding electrode 16 has a plurality of openings 1
Although plating is formed over the area including 4a, the opening 14
Since a is small relative to the plating thickness, a very small recess 20 corresponding to the opening 14a is formed on the top surface of the plating, but the entire surface is flat, and therefore the top surface of the completed bump electrode 16 is also flat. . As a result, even when the inner leads 17 are connected by thermocompression bonding, the inner leads 17 are brought into uniform contact with the protruding electrodes 16, thereby preventing thermal stress from being uneven or concentrated. This prevents cracks in the semiconductor substrate 11 and the protruding electrode 1 from occurring.
By improving the strength of No. 6, it is possible to improve the reliability of the semiconductor device.

Here, the number and planar shape of the openings 14a are not limited to those in the embodiment, and various changes are possible.

〔Effect of the invention〕

As explained above, in the present invention, the opening formed in the protective insulating film provided on the aluminum barrier is formed by a plurality of small openings arranged in a plane, and the projecting electrode is formed on the area including these openings. This makes it possible to flatten the upper surface of the protruding electrode to be plated, and to equalize thermal stress when connecting with the inner lead, preventing cranking under the protruding electrode and increasing the strength of the protruding electrode. This has the effect of improving the reliability of the semiconductor device.

[Brief explanation of drawings]

FIG. 1 is a plan view of an embodiment of the present invention, FIG. 2 is a sectional view taken along line AA in FIG. 1, FIG. 3 is a plan view of a conventional structure, and FIG.
The figure is a cross section taken along line BB in FIG. 1.11... Semiconductor substrate, 2.12... Insulating film, 3
゜13... Aluminum pad, 4.14... Protective insulating film, 4a, 14a... Opening, 5.15... Barrier metal layer, 6.16... Protruding electrode, 7.17...・
Inner lead, 20... recess. Figure 1

Claims (1)

[Claims] 1. A protective insulating film is deposited to cover the metal pad formed on the semiconductor substrate, the metal pad is exposed through an opening provided in the protective insulating film, and a barrier metal layer and a barrier metal layer are formed on the area including the metal pad. A semiconductor device in which a protruding electrode is formed, characterized in that the opening formed in the protective insulating film is smaller than the thickness of the protruding electrode, and a plurality of openings are arranged in a plane over the area where the protruding electrode is formed. Semiconductor equipment.