JPH0613384A - Formation method for electrode of ic chip - Google Patents

Abstract

PURPOSE:To form a permanent resist for protecting the surfaces of IC chips used for various kinds of electronic equipment, and joining electrodes capable of maintaining the narrow distance between the electrodes simultaneously. CONSTITUTION:Using a negative-type photosensitive polyimide 2a, permanent resist 2 is formed on an IC chip 1 excluding the parts of the aluminum electrodes 4 of the IC chip 1. Following this, gold plating 7 processing of the aluminum electrodes 4 are performed, after temporary resist 5 is formed on the permanent resist 2 using positive-type photosensitive resist 5a. Then the temporary resist 5 is removed, and joining electrodes in the shape of a rectangular parallelopiped are formed. This method prevents the generation of surface flaws of the IC chip 1, and increases the reliability. In addition, it becomes possible to maintain the narrow distance between the electrodes and reduce the size of the IC chip 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an IC for forming rectangular parallelepiped bonding electrodes on an IC chip used in various electronic devices.
The present invention relates to a chip electrode forming method.

[0002]

2. Description of the Related Art In recent years, electronic parts have been developed aiming at further downsizing and weight reduction. As part of that, TA
B. In the bare IC chip mounting method, electrodes for bonding are formed on the IC chip.

A conventional method for forming electrodes of an IC chip will be described below. As shown in FIG. 2A, after a temporary resist 8 is formed on the IC chip 1 having the aluminum electrode 4 by using a photosensitive resist of several microns, a gold electrode 9 is formed on the aluminum electrode 4. And remove the temporary resist 8
As shown in FIG. 2B, there is a method of forming a gold electrode 9 for bonding on the aluminum electrode 4.

Further, as shown in FIG. 3, a permanent resist 10 for protecting the surface of the IC chip 1 is formed by using a photosensitive polyimide of several microns, and then a gold electrode 9 for bonding is formed on the aluminum electrode 4. There is a method of forming.

In both of these, since the gold electrode 9 protrudes above the aluminum electrode 4, it is not possible to maintain a predetermined narrow interelectrode distance of the aluminum electrode 4.

As a countermeasure against this, as shown in FIG. 4 (a), a thick photosensitive resist 12 is applied to a portion other than the aluminum electrode 4 of the IC chip 1, and then a gold electrode 11 is formed on the aluminum electrode 4 in a rectangular parallelepiped shape. Then, after forming, a photosensitive resist 1
There is a method of removing 2 to form a rectangular parallelepiped gold electrode 11 for bonding as shown in FIG.

[0007]

However, in the above-mentioned conventional method, a permanent resist for protecting the surface of the IC chip 1 and an electrode for bonding which maintains a predetermined narrow electrode distance are simultaneously formed. It had a problem that it could not.

The present invention solves the above-mentioned problems of the prior art by simultaneously forming a permanent resist for protecting the surface of an IC chip and a bonding electrode for maintaining a narrow inter-electrode distance.
An object of the present invention is to provide a method for forming an electrode for a C chip.

[0009]

In order to achieve this object, an electrode forming method of an IC chip according to the present invention uses a negative photosensitive polyimide on the IC chip to form an aluminum electrode portion on the IC chip. Except for this, a permanent resist is formed, and then a positive photosensitive resist is used to form a temporary resist on the permanent resist.The aluminum electrode is then plated with gold, and then the temporary resist is removed to form a rectangular parallelepiped shape. This is a method of forming an electrode for bonding of.

[0010]

In this method, the permanent resist for protecting the surface of the IC chip and the bonding electrode for maintaining a predetermined narrow distance between the electrodes are simultaneously formed.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

As shown in FIG. 1A, an IC chip having an aluminum electrode 4 is coated with a negative photosensitive polyimide 2a, and an exposure mask 3 is aligned with the aluminum electrode 4 for exposure.
After development, as shown in FIG. 1B, the photosensitive polyimide 2a on the aluminum electrode 4 on the IC chip 1 is removed to form the permanent resist 2.

Then, as shown in FIG. 1C, a positive type photosensitive resist 5a is applied, and an exposure mask 6 is exposed and developed in accordance with the permanent resist 2, and as shown in FIG. 1D. Then, the permanent resist 2 and the temporary resist 5 are formed in two steps on the IC chip 1 with the aluminum electrode 4 portion opened.

Then, as shown in FIG. 1 (e), the aluminum electrode 4 is plated with gold, and then the temporary resist 5 is removed. As shown in FIG. 1 (f), a permanent resist 2 and a predetermined narrow space are formed. An electrode for bonding plated with gold 7 is formed on an aluminum electrode 4 having a rectangular parallelepiped shape in which the distance between the electrodes is maintained.

As described above, according to this embodiment, the permanent resist, which cannot be formed simultaneously by the conventional method, and the rectangular parallelepiped bonding electrode which maintains a predetermined narrow interelectrode distance, can be formed at the same time. The surface damage of the chip 1 can be prevented and reliability can be improved, and the IC chip 1 can be miniaturized by insulating a narrow inter-electrode distance.

[0016]

As is apparent from the above description of the embodiments, the present invention uses a negative photosensitive polyimide on an IC chip to form a permanent resist except the aluminum electrode portion on the IC chip. Then, using a positive-type photosensitive resist, a temporary resist is formed on the permanent resist, and then the aluminum electrode is gold-plated and the temporary resist is removed to form a rectangular parallelepiped-shaped bonding electrode. By this method, it is possible to realize an excellent electrode forming method for an IC chip, which can simultaneously form a permanent resist for protecting the surface of the IC chip and an electrode for bonding which maintains a narrow inter-electrode distance.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing the concept of an electrode forming method for an IC chip according to an embodiment of the present invention in the order of steps.

FIG. 2 is a schematic cross-sectional view showing the concept of forming electrodes using a photosensitive resist in the conventional method for forming electrodes of IC chips.

FIG. 3 is a schematic sectional view showing an electrode formed by using a permanent resist in the electrode forming method of the IC chip.

FIG. 4 is a schematic cross-sectional view showing the concept of forming a rectangular parallelepiped-shaped electrode in the electrode forming method of the same IC chip.

[Explanation of symbols]

 1 IC Chip 2 Permanent Resist 2a Photosensitive Polyimide 4 Aluminum Electrode 5 Temporary Resist 5a Photosensitive Resist 7 Gold Plating

Claims (1)

[Claims] 1. A negative photosensitive polyimide is applied on an IC chip, exposed and developed to form a permanent resist except the aluminum electrode portion of the IC chip, and then a positive photosensitive resin. After applying a resist, it is exposed and developed to form a temporary resist on the permanent resist, and then gold plating is performed on the aluminum electrode, and the temporary resist is removed to form a rectangular parallelepiped bonding electrode. A method for forming an electrode of an IC chip for forming a substrate.