JPH0590269A - Structure and forming method of protrudent electrode - Google Patents

Abstract

PURPOSE:To enable a protrudent electrode formed on an electronic element or a board to be improved in characteristics and enhanced in connection reliability when the electronic element is bonded facing downward. CONSTITUTION:A resin 6 which contains metal particles 7 is formed on the Al electrode 2 of a semiconductor element 1. The semiconductor element 1 is dipped into a plating bath, the metal particles 7 protruding from the resin 6 serve as nucleuses to enable a metal film 8 to grow, whereby the metal film 8 is formed both on the resin 6 and on the AE electrode 2, and a protrudent electrode provided with a resin layer 6 is formed on the Al electrode 2. Therefore, bumps can be formed at a very small pitch. Furthermore, the metal particles 7 are contained in the resin 6, whereby the metal film 8 can be easily formed, and the metal film 8 is enhanced in adhesion to the resin 6 owing to the anchor effect of the mental particles 7, and in result a semiconductor of high reliability can be provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure and method of forming a protruding electrode formed on an electric element or a substrate,
More specifically, it relates to improvement of the characteristics of the bump electrodes.

[0002]

2. Description of the Related Art As a method of forming a bump electrode, a bump electrode of a metal block has been formed by an electroplating method.

FIG. 4 is a sectional view of a semiconductor device having a protruding electrode formed by electroplating. In the figure, 1
01 is a semiconductor element, 102 is an Al electrode provided on the semiconductor element 101, 103 is a passivation film, 104
Is a barrier metal formed of a metal such as Ni, Cr, Pt, or the like on the Al electrode 102, and 105 is a metal bump that functions as a protruding electrode formed on the barrier metal 104 by an electrolytic plating method.

Next, a method of forming a metal bump will be described. First, a metal such as Ni, Cr, Pt, etc. is formed on the semiconductor element 101 by a sputtering method in a vacuum chamber by vapor deposition. By coating a polyimide-based resist on the formed metal film, overlaying a mask and irradiating with ultraviolet rays, the Al electrode 102
The resist except the top is cured, the uncured resist is removed by the solvent, and the opening is provided only on the Al electrode. Next, the semiconductor element 101 having the resist layer formed thereon is placed in an Au plating bath, and a voltage is applied to the metal film. Au grows only on the metal film exposed in the opening of the resist, and the Au bump 105 is formed. After the Au bumps 105 are formed, the resist layer is removed with a solvent, and the metal film is dry-etched using the bumps 105 as a mask to form the barrier metal 10.
4 is formed.

[0005]

The above-described method of forming the protruding electrode has the following problems. In other words, the number of steps is very complicated and many costly steps such as vacuum deposition are included, which increases the manufacturing unit price, and the plating metal also grows in the surface direction of the semiconductor element, which causes a short circuit between adjacent terminals. However, it is difficult to form protruding electrodes with a fine pitch. Further, in the method of mounting a semiconductor element called chip-on-glass on the substrate in a face-down manner, it is difficult to evenly arrange the heights of the above-mentioned protruding electrodes, and the connection reliability is significantly reduced. .. Further, since the above-mentioned protruding electrode, which is a metal lump, is difficult to deform, it is difficult to cope with a solid and smooth substrate.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a protruding electrode which is easily deformed on the electrode and which corresponds to a fine pitch.

[0007]

The structure of the bump electrode according to the present invention is such that metal particles are dispersed so as to cover at least a part of the electrode in a bump electrode having a shape protruding from an electrode on an electric element or a substrate. A layer of the resin thus formed is formed, and a metal coating is formed only on the resin containing the metal particles and the electrode.

[0008]

Function: A resin containing metal particles is formed on the electrode. This is immersed in a metal plating bath, and a metal film is formed on the resin by growing metal particles with the metal particles protruding from the resin as nuclei. At the same time, a metal film is also formed on the electrode and A bump electrode including a layer is formed.

[0009]

EXAMPLE An example according to the present invention will be described below.

FIG. 1 is a sectional view of a semiconductor device having a protruding electrode according to the present invention, and FIG. 2 is an enlarged sectional view showing a main part of the protruding electrode according to the present invention. Reference numeral 1 is a semiconductor element, 2 is an Al electrode provided on the semiconductor element 1 for inputting / outputting an electric signal, 3 is a passivation film provided for protecting an active surface of the semiconductor element 1, and 6 is A.
1 is a resin formed on the electrode, 7 is metal particles dispersed in the resin, and 8 is a metal film formed so as to cover the resin 6 and the Al electrode 2.

3 (a) to 3 (d) are sectional views showing a process of forming the bump electrode according to the present invention shown in FIGS. 1 and 2, 9 is a mask, and 10 is ultraviolet ray irradiation. An arrow indicating the direction, 11 is a region where the resin 6 is cured by ultraviolet rays, and 12 is a palladium film. The method of forming the bump electrode according to the present invention is as follows.

First, an appropriate amount of resin 6 in which metal particles 7 are uniformly dispersed is dropped on the active surface of the semiconductor element 1 using a dispenser or the like. In order to uniformly spread the dropped resin 6 on the semiconductor element 1, the semiconductor element 1 is rotated at high speed at about 3,000 rpm for 10 seconds, and the resin 6 is spin-coated to a thickness of about 20 μm. The resin 6 used at this time is a liquid ultraviolet curing type polyimide resin, and Ag-Pd having a particle size of 0.1 to 1 μm as the metal particles 7 is used.
The powder is contained in the resin 6 in an amount of 5 to 20%. The reason why the ultraviolet curable polyimide resin is used as the resin 6 is that the pattern can be easily formed and the chemical resistance is excellent, and if the resin is not attacked by the electroless plating solution, it is a film-like resin. Alternatively, a non-photosensitive resin may be used. Resin 6
The semiconductor element 1 spin-coated with is dried at 80 ° C. for about 1 hour to obtain the structure of FIG. Next, FIG. 3 (b)
3A, the mask 9 having an opening at a position corresponding to the Al electrode 2 of the semiconductor element 1 is provided in the semiconductor element 1 of FIG.
The resin 6 is aligned and placed on the top, and ultraviolet rays are irradiated in the direction of the arrow 10 to cure the resin 6 only in the region 11. By making the opening of the mask 9 smaller than the Al electrode 2, the cured region 11 of the resin 6 is designed to be smaller than the Al electrode 2.

In order to remove the uncured portion of the resin 6, the semiconductor element 1 is immersed in the developing solution of the resin 6 for about 2 minutes,
The structure of (c) is obtained. At this time, the cured region 11 of the resin 6
Since part of it is also etched, the thickness of the resin 6 is as shown in FIG.
It is 20 to 30% less than the state shown in (a). Therefore, the metal particles 7 are projected from the resin 6 as shown in FIG.

As a pretreatment for plating the Al electrode 2 as well, the semiconductor element 1 is dipped in a tin (II) chloride solution and a palladium chloride solution, and the Al electrode 2 is placed on the Al electrode 2 as shown in FIG. 3 (d). The activated palladium film 12 is formed.

Finally, the semiconductor element 1 is immersed in an electroless Ni plating bath to form the metal film 8. Since the palladium film 12 is present on the Al electrode 2, Ni in the electroless plating bath is replaced with the palladium film 12 to form Al.
It is deposited on the electrode 2. Also, on the resin 6, the resin 6
The Ni film grows with the metal particles 7 protruding from the surface of the as a nucleus. Thus, the Ni film grown on the resin 6 and the Ni film grown on the Al electrode 2 by using the metal particles 7 as nuclei
The metal film 8 is bonded to the film, and a metal film 8 is formed so as to cover the Al electrode 2 and the resin 6 as shown in FIG. 2 to form a protruding electrode. As the metal particles 7, Ag-Pd powder was used for N
This is for facilitating the attachment of the i-plated film, and other metal materials such as Fe, Ni and Cu can be sufficiently substituted as long as the metal can be electrolessly plated. Further, since the metal particles 7 dig into the resin 6, the adhesion of the metal film 8 to the resin 6 is improved by the anchor effect.

The height of the protruding electrode thus formed can be set arbitrarily from submicron depending on the type of resin 6 and the coating method, and the pitch can be handled up to the submicron unit, which is a size capable of being etched. Become. Furthermore, since the bump electrode includes the resin 6 layer, the bump electrode is easily deformed as compared with the conventional metal bump 105 that is a metal block.
In the mounting method called chip-on-glass described above, a reliable connection can be established by pressing the protruding electrodes on a smooth substrate. As an example, a semiconductor element having a protruding electrode (FIG. 4) formed by a conventional technique,
The semiconductor element having the protruding electrodes according to the present invention is formed into a chip.
As a result of mounting on-glass and comparing, in the conventional technology, the connection failure was 26/100 per 100 semiconductor elements mounted.
However, in the bump electrode according to the present invention, no connection failure occurred per 100 semiconductor devices.

[0017]

As described above, according to the present invention, a bump is formed at a fine pitch by forming a resin layer containing metal particles on an electrode and forming a metal film on the electrode and the resin. This is possible, and since the deformation can be easily performed, reliable connection can be achieved even when mounting on a smooth substrate. Further, by containing metal particles in the resin, the formation of the metal film is facilitated, and the anchoring effect of the metal particles improves the adhesion of the metal film to the resin, thereby providing the semiconductor device with high reliability.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment according to the present invention.

FIG. 2 is an enlarged sectional view showing a main part of one embodiment according to the present invention.

FIG. 3 is a cross-sectional view showing a manufacturing process of an embodiment according to the present invention.

FIG. 4 is a cross-sectional view showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 semiconductor element 2 Al electrode 3 passivation film 6 resin 7 metal particles 8 metal film 9 mask 10 arrow which shows the irradiation direction of ultraviolet rays 11 hardened area 12 palladium film 101 semiconductor element 102 Al electrode 103 passivation film 104 barrier metal 105 metal bump

Claims (4)

[Claims] 1. A bump electrode having a shape protruding from an electrode on an electric element or a substrate is formed with a resin layer in which metal particles are dispersed so as to cover at least a part of the electrode, A structure of a protruding electrode, characterized in that a metal coating is formed only on the resin containing and the electrode. 2. A step of forming a resin layer in which metal particles are dispersed so as to cover a part of an electrode on an electric element or a substrate, and the electric element or the substrate is immersed in an electroless plating bath, And a step of forming a metal film only on the resin layer containing the electrodes and the metal particles. 3. The metal coating comprises Ni, Co, Cu,
The structure of the protruding electrode according to claim 1, wherein an electroless plating film of Au or the like is applied. 4. As the metal particles, Au, Ni, Co,
The structure of the bump electrode according to claim 1, wherein particles containing a metal capable of electroless plating such as Pd, Cu, Zn, Sn and Ag are used.