JP2020031081A - Semiconductor device - Google Patents

Abstract

To provide a semiconductor device that does not increase manufacturing costs and does not break when a junction is formed.SOLUTION: A reinforcing layer 7 including an opening at the center is provided between an electrode pad 2 and a bump electrode 3 to securely connect the electrode pad and the bump electrode within the opening, and at the same time, an ultrasonic energy applied to the bump electrode, or a load is transmitted to the electrode pad via the reinforcing layer to prevent the electrode pad from being damaged.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a semiconductor device, and more particularly, to a semiconductor device having a bump electrode on an electrode pad.

  A bump electrode of a general semiconductor device has a structure as shown in FIG. 4, for example. An electrode pad 2 connected to a wiring (not shown) is formed on a substrate 1 on which a semiconductor element and the like are formed. The bump electrode 3 is formed on the pad 2.

  The bump electrode 3 having the structure shown in FIG. 4 is formed, for example, by forming a metal ball on the tip of a metal wire using a capillary for bump production, and pressing the metal ball while applying ultrasonic waves to the electrode pad 2 or thermocompression bonding. Can be formed.

  At this time, if the passivation film 4 is disposed close to the region where the bump electrode 3 is formed, the passivation film 4 contacts the passivation film 4 in the step of forming the bump electrode 3 and cracks are generated in the passivation film 4, which is not preferable. . Therefore, as shown in FIG. 4, the passivation film 4 is formed so as to greatly open a region where the bump electrode 3 is formed.

  As shown in FIG. 5, the bump electrodes having such a structure are joined by pressure bonding while applying ultrasonic waves to the mounting substrate electrodes 6 on the mounting substrate 5.

  When the electrode pad 2 is formed of aluminum (Al) and the bump electrode 3 is formed of gold (Au), when the bump electrode 3 is formed, or when the bump electrode 3 is bonded to the mounting substrate 5, the electrode pad 2 There is a problem that the substrate 1 below the electrode pad 2 is damaged.

  This is because, when the bump electrode 3 is formed, Al constituting the electrode pad 2 and Au constituting the bump electrode 3 react with each other to promote alloying, thereby reducing the energy of ultrasonic waves and reducing the load of thermocompression bonding. It is considered that the soft aluminum layer to be relaxed disappears.

  In order to solve this kind of problem, there has been proposed a method of forming a reinforcing layer 7 made of a nickel (Ni) -gold plating layer on the electrode pad 2 as shown in FIG. 6 (Patent Document 1, FIG. 8). ). However, a step of forming the reinforcing layer 7 is added, and the manufacturing cost increases.

JP 2007-35918 A

  In the conventionally proposed semiconductor device, it is necessary to add a manufacturing process for forming the reinforcing material, and there is a problem that the manufacturing cost increases. SUMMARY OF THE INVENTION It is an object of the present invention to solve such a problem and to provide a semiconductor device which does not increase manufacturing cost and is not damaged when forming a junction.

  In order to achieve the above object, the invention according to claim 1 of the present application is directed to a semiconductor device having a bump electrode on an electrode pad whose surface is partially protected by an insulating film, wherein the semiconductor device is provided between the electrode pad and the bump electrode. A reinforcing layer made of an insulating material, the reinforcing layer exposing a surface of the electrode pad between the insulating layer and the insulating film, and a central portion having an opening exposing a surface of the electrode pad; Has a structure in which the electrode is connected to the electrode pad in the opening and laminated on the reinforcing layer.

  The invention according to claim 2 of the present application is the semiconductor device according to claim 1, wherein the electrode pad includes aluminum, and the bump electrode includes gold.

  Further, according to a third aspect of the present invention, in the semiconductor device according to any one of the first and second aspects, the reinforcing layer is made of the same insulating material as the insulating film for protecting a part of the surface of the electrode pad. It is characterized by having.

  According to the semiconductor device of the present invention, by providing a reinforcing layer having an opening in the center between the electrode pad and the bump electrode, the electrode pad and the bump electrode are securely connected in the opening, and the voltage is applied to the bump electrode. The applied ultrasonic energy or load propagates to the electrode pad via the reinforcing layer, so that damage to the electrode pad can be prevented. In particular, when ultrasonic energy is applied, the doughnut-shaped reinforcing film functions to limit vibration in a direction parallel to the surface of the electrode pad, thereby preventing damage to the electrode pad.

  Since the reinforcing layer of the present invention is formed separately from the insulating film that protects the surface of the semiconductor device, even if damage such as a crack occurs due to ultrasonic energy or a load applied to the bump electrode, the semiconductor device is not damaged. Since the damage does not propagate to the insulating film for protecting the surface of the semiconductor device, the moisture resistance of the semiconductor device is not reduced.

  Further, when the electrode pad contains aluminum and the bump electrode contains gold, even when alloying of aluminum and gold proceeds at the joint, according to the semiconductor device of the present invention, the area to be alloyed is a narrow area. Since the ultrasonic energy or the load is limited and propagates to the reinforcing layer and the aluminum layer which remains thereunder without being alloyed, it is possible to effectively prevent the electrode pad from being damaged.

  The reinforcing layer of the present invention can be made of the same insulating material as the insulating film formed for protecting the surface of the semiconductor device, and can be patterned at the same time, so that the manufacturing cost can be reduced.

  Further, by providing the reinforcing layer, the deformation of the bump electrode in the horizontal direction is suppressed, and the height of the bump electrode can be maintained.

FIG. 3 is an explanatory diagram of a semiconductor device of the present invention. FIG. 4 is a diagram illustrating a method for manufacturing a semiconductor device according to the present invention. FIG. 3 is a diagram illustrating a mounting structure of the semiconductor device of the present invention on a mounting substrate. FIG. 11 is an explanatory diagram of a conventional semiconductor device. It is an explanatory view of a mounting structure of a conventional semiconductor device. FIG. 11 is an explanatory diagram of another conventional semiconductor device.

  The semiconductor device of the present invention has a configuration in which an electrode pad and a bump electrode are joined via a reinforcing layer having an opening in the center, separated from an insulating film (passivation film) for protecting the surface. With this configuration, the ultrasonic energy or the load applied to the bump electrode is applied to the electrode pad via the reinforcing layer and the aluminum remaining without being alloyed under the reinforcing layer. Can be prevented. Further, since the reinforcing layer is separated from the insulating film for protecting the surface, even if damage (cracks) is caused by ultrasonic energy applied to the bump electrode, the damage propagates to the insulating film for protecting the surface. This does not cause a decrease in the moisture resistance of the semiconductor device. Hereinafter, embodiments of the present invention will be described in detail.

  A first embodiment of the present invention will be described. FIG. 1 shows a semiconductor device according to a first embodiment of the present invention. The difference from the conventional semiconductor device shown in FIG. 4 is that a reinforcing layer 7 is provided. Unlike the conventional reinforcing layer 7 shown in FIG. 6, the reinforcing layer 7 is made of an insulating film and is arranged on the electrode pad 2 without contacting the passivation film 4. Further, an opening is provided at the center to expose the surface of the electrode pad 2, and the bump electrode 3 is in contact with the electrode pad 2 in this opening. Further, the structure is such that the bump electrodes 3 are stacked on the reinforcing film 7.

  Such a reinforcing layer 7 can be formed as follows. First, an electrode pad 2 connected to a desired wiring is formed on a substrate 1 according to a normal semiconductor device manufacturing process (FIG. 2A).

  To protect the surface, the entire surface is covered with a passivation film made of an insulating film. As the passivation film, an insulating film used in a manufacturing process of a semiconductor device may be appropriately selected. After that, the surface of the electrode pad 2 is exposed. At this time, the reinforcement film 7 is formed in the opening of the passivation film 4 at the same time. The reinforcing film 7 is separated from the passivation film 4 and has a structure including an opening 8 that opens a central portion of a region where the bump electrode is to be formed of the electrode pad 2 (FIG. 2B). The size of the opening 8 may be appropriately set so that sufficient bonding strength with the bump electrode 3 described later can be maintained.

  After that, the bump electrode 3 is formed by a wire bonding method using a normal metal wire (FIG. 2C). Specifically, a metal ball is formed at the tip of a metal wire, and the metal ball is pressed while applying ultrasonic waves to the electrode pad 2. As a result, the tip of the metal ball is deformed, enters the opening 8, and joins the electrode pad 2. Part of the metal ball has a structure of being laminated on the reinforcing film 7.

  When the electrode pad 2 is made of aluminum or a material containing aluminum as a main component, and the metal wire is made of gold or a material containing gold as a main component, aluminum and gold are alloyed. However, in the present invention, since the electrode pad 2 made of aluminum that does not alloy with the reinforcing layer 7 exists under the bump electrode 3, the electrode pad 2 and the substrate 1 may be damaged even when a bond is formed by applying ultrasonic waves. Will not lead.

  Similarly, when bonding is performed by applying pressure while applying ultrasonic waves to the mounting substrate electrode 6 of the mounting substrate 5, the electrode pad 2 made of aluminum that does not alloy with the reinforcing layer 7 from the bump electrode 3 exists. Thus, the electrode pad 2 and the substrate 1 are not damaged.

  Although the embodiments of the present invention have been described above, it goes without saying that the present invention is not limited to the above embodiments. For example, in the above-described embodiment, the prevention of damage to the electrode pad in the case of forming a bond while applying ultrasonic waves was described. However, the application of ultrasonic waves also prevents the damage of the electrode pad in the case of bonding by thermocompression bonding. be able to.

1: substrate, 2: electrode pad, 3: bump electrode, 4: passivation film, 5: mounting substrate, 6: mounting substrate electrode, 7: reinforcing layer, 8: opening

Claims (3)

In a semiconductor device having a bump electrode on an electrode pad partially protected by an insulating film,
A reinforcing layer made of an insulating material is provided between the electrode pad and the bump electrode,
The reinforcing layer exposes a surface of the electrode pad between the insulating layer and the insulating film, and has an opening exposing a surface of the electrode pad in a central portion,
The semiconductor device according to claim 1, wherein the bump electrode is connected to the electrode pad in the opening and stacked on the reinforcing layer.   2. The semiconductor device according to claim 1, wherein said electrode pad includes aluminum, and said bump electrode includes gold.   3. The semiconductor device according to claim 1, wherein the reinforcing layer is made of the same insulating material as the insulating film that protects a part of the surface of the electrode pad.

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