JPH0793311B2 - Method for forming protruding electrode of semiconductor element - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of forming bump electrodes (bumps) on electrodes of semiconductor elements such as IC (integrated circuit) and LSI (large scale integrated circuit) chips. It can be used in the field of connection technology between a semiconductor element on which various protruding electrodes are formed and a conductive pattern on a mounting substrate.

2. Description of the Related Art In the field of electronic devices and electronic equipment, there is a social demand for miniaturization of light books, and in order to meet this demand, many functional components such as ICs can be mounted on a board of a limited area with high density. It is necessary to implement in. In particular, it can be seen in those developed for devices such as hybrid ICs, card-shaped devices, and LCD TVs.

In order to realize such high-density mounting, a bare chip is very advantageous over a semiconductor mounted on a substrate in the form of a packaged product. Furthermore, compared to a connection method by so-called wire bonding, in which a wire such as gold or aluminum is welded to an electrode of a semiconductor element and a conductive pattern on a substrate to connect them, a wire is not used, and a semiconductor element Wireless bonding, in which a large number of electrodes and conductive patterns on the substrate are collectively connected, is extremely effective.

As the wireless bonding, there are a flip chip method, a film carrier method, and the like.

The flip chip method is a method in which a protruding electrode is formed on a semiconductor element electrode and the protruding electrode and the conductive pattern on the substrate are joined by soldering.

The film carrier method electrically and mechanically connects the inner end of the conductive finger for external connection carried on the film and the electrode of the semiconductor element, but avoids the edge of the semiconductor element from contacting the finger. The projection electrodes are formed on the electrodes of the semiconductor element or on the fingers and are connected to each other through the projection electrodes.

Problems to be Solved by the Invention All of the protruding electrodes in the above method are formed of a metal such as Au, Ag, Ni, solder or a metal compound. These metal-based protruding electrodes have a high temperature at the time of joining and the joint is firmly fixed by an alloy or the like, so that the thermal stress due to the difference in thermal expansion coefficient between the semiconductor element base material and the wiring board and the external When pressure due to mechanical or thermal shock is applied, the wiring board or the like may be deformed or the joint may be peeled off.

Further, the metal-based protruding electrode is usually formed by an electrolytic plating method or the like, but since a short circuit occurs between the element electrodes due to excess plating liquid or the like, it is necessary to narrow the electrode interval or perform fine processing. It is difficult.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a method for forming a novel protruding electrode for a semiconductor element, which solves the above-described inconveniences of the metallic protruding electrode. And

Means for Solving the Problems According to the present invention, a resin selected from modified acrylate-based, phenol novolac-based, and epoxy-based is used as a base material, and a photocuring initiator and an electrically conductive substance are added to the base material. A semiconductor device characterized by kneading to generate a protruding electrode forming material, applying the protruding electrode forming material to the surface of the semiconductor device on which the electrode is present, and forming the protruding electrode on the electrode of the semiconductor device by a photolithography technique. There is provided a method for forming a bump electrode.

Action In the method for forming a bump electrode according to the present invention, a resin-based bump electrode containing an electrically conductive substance is hardened and formed on a semiconductor element electrode by the action of a photo-curing initiator by a photolithography technique. When joined to the conductive pattern, it fulfills both functions of electrical connection and mechanical joining.

Example Hereinafter, a method for forming a protruding electrode of a semiconductor device according to the present invention will be described in detail.

The material for forming the bump electrode formed by the present invention is based on a modified acrylate-based, phenol novolac-based, or epoxy-based resin as a base material, and a photo-curing initiator corresponding to the resin of each system as a photosensitive component. And an inorganic or organic substance such as Ag or Ni as an electrically conductive component, and kneaded to produce a thermoplastic resin or rosin as a heat-adhesive component. Further, if necessary, an appropriate catalyst can be added to adjust various characteristics of the material for forming the protruding electrodes.

The protruding electrode forming material is applied to the surface of the semiconductor element on which the electrodes are provided by an appropriate means such as spin coating or roll coating. At that time, the protruding electrode forming material may have its viscosity adjusted by a reactive diluent or an organic solvent.

After that, the protruding electrodes are formed by the usual photolithography technique. That is, after drying the applied protruding electrode forming material, only the corresponding portion of the semiconductor element electrode is exposed by, for example, UV (ultraviolet) light through a pattern mask, and the protruding electrode forming material is cured by the action of the photo-curing initiator. To be done.

Then, an uncured portion of the protruding electrode forming material is removed with an organic solvent such as ethyl acetate or methyl ethyl ketone to form a resin-based protruding electrode attached on the electrode of the semiconductor element.

When mounting on a wiring board, align the formed protruding electrodes with the conductive patterns of the wiring board corresponding to these,
The semiconductor element is pressurized and heated from the side. Applied pressure at this time is 10 to 200 / cm ² the heating temperature is adjusted so that the temperature of the bump electrode is 100 to 200 ° C. by the heat transfer or ultrasonic heating through the semiconductor element from the pressurizing tool The pressure bonding time is about 5 seconds to 5 minutes.

The same operation can be performed when the semiconductor element with the protruding electrodes is attached to the resin film of the film carrier. That is, the semiconductor element is inserted into the hole formed in the resin film, the ends of the fingers of the copper foil for external connection extending into the hole are aligned with the protruding electrodes, and then both are pressed and heated. To obtain electrical connection and mechanical connection.

Effect of the Invention According to the present invention, the following effects can be achieved.

(1) Since the protruding electrode is a polymer material having a Young's modulus smaller than that of a metal such as solder, thermal stress generated by external mechanical shock or vibration, or environmental temperature change around the connection part, etc. It can be absorbed and relaxed by the protruding electrode,
Unlike the conventional metal-based protruding electrode, the wiring substrate is not deformed or the joint is not peeled off, and a highly reliable protruding electrode having an adhesive function can be obtained.

(2) Since the protruding electrodes are present only on the electrodes of the semiconductor element, there is no danger of a short circuit occurring between the electrodes of the semiconductor element as compared with the conventional method of forming a metal-based protruding electrode. Can also be applied.

(3) Since the bump electrode contains a heat-adhesive component, a conductive pattern material that is hard to form an alloy on the wiring board or a conductive pattern that is difficult to process, such as ITO (indium tin oxide), for bonding with the conductive pattern. It is possible to easily obtain an electrical connection even with a material such as).

(4) If a defective semiconductor element is found during the device characteristic check after mounting, it was necessary to heat the semiconductor element at a high temperature of 300 ° C or more to separate the semiconductor element in the conventional soldering connection. The semiconductor element can be removed from the bump electrode according to the present invention by applying a low temperature of, for example, 200 ° C. or lower, or by melting it with an organic solvent, and the repair of the semiconductor element is very easy.

Claims (1)

[Claims] 1. A base material is a resin selected from a modified acrylate type, a phenol novolac type and an epoxy type.
A photocuring initiator and an electrically conductive substance are kneaded on this base material to generate a protruding electrode forming material, and the protruding electrode forming material is applied to the surface of the semiconductor element on which the electrode is present. A method for forming a protruding electrode for a semiconductor device, comprising forming a protruding electrode on the electrode.