JPH0410543A - Formation of bump electrode of semiconductor device - Google Patents

Abstract

PURPOSE:To contrive to prevent a metal from flowing out to the side of an inner lead or the corner part of each semiconductor element by a method wherein each one part of resist films over an electrode having an opening part is opened, the thicknesses of the resist films are formed in such a way that the outside resist film becomes thicker than the inside resist film and a bump electrode, whose bump top is formed in a state eccentric to the inside of each semiconductor element, is formed between the resist films. CONSTITUTION:A second resist film 27 is formed on the outside, the side of the so-called outer peripheral side, of an electrode 23 arranged and formed on the outer peripheral side of each unit element on a semiconductor substrate 21, a first resist film 26 only is formed on the inside, which is situated to the electrode, of each unit element formed on the main surface of the substrate 21 and the resist films are formed. After that, the electrode is put in a bump plating solution or is brought into contact to the bump plating solution, is made to conduct, a bump is formed, the resist films are removed and a bump 30 of a form is obtained. The form of the bump 30 is formed into a form that a bump top 32 is shifted on the inside of each semiconductor element on the substrate 21 to a center line 31 of the electrode 23. As the form of the bump is formed in such a way that the thicknesses of the resist films are thin on the inside of each unit element and are thick on the outside of each unit element, the reservoir part of a flowed-out metal is formed between an inner lead 40 and the bump 30.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention is directed to TAB (Tape Autos+ated
The present invention relates to the shape of bump electrodes in the bonding technology and the technology of inner lead connection parts.

(Prior art) Conventionally, as a technology in this field, for example,
There was one described in No. 1-53853.

FIG. 2 is a sectional view of the vicinity of the connection between the lead wire and the electrode of such a conventional semiconductor device.

As shown in this figure, a recess 7 is formed in the lead wire 3 extending through the opening provided in the tape-shaped resin film near the first lead edge of the electrode 2 of the semiconductor element l to be connected. ing. The recess 7 is easily formed by a conventional selective etching method using a photoresist as a mask.

The lead wire 3 is further tin-plated, but in order to prevent the heat treatment from the next process from having an adverse effect on the solder wettability.
A tin plating layer 3' is provided. The lead wire 3 is connected to the semiconductor element electrode 2 made of gold, for example, by forming a gold-tin eutectic alloy. At this time, the metal 5 that has been melted or softened by the heat generated during connection flows out, but is pulled into the recess 7 of the lead wire 3 due to surface tension, causing metal particles to be short-circuited between the semiconductor element 1 and the lead wire 3. It disappears.

FIG. 3 is a sectional view of the vicinity of the connection between the lead wire and the electrode of the semiconductor element, showing another example of the arrangement of recesses near the connection of the lead wire in the related art.

As shown in this figure, a recess I7 is formed near the side of the electrode 12 of the semiconductor element 11, and the recess 17 is melted or softened by the heat generated when the IJ-wire 13 and the element electrode 12 are connected. The metal 15 flowing out is attracted by surface tension.

(Problem to be Solved by the Invention) However, in the method for connecting the electrodes and lead wires of the semiconductor device with the above configuration, etching the tip of the inner lead is difficult to achieve with a material that is only several tens of μm thick. Therefore, there was a problem that the mechanical strength of the tip part deteriorated, and precision was required in positioning the facing and upper and lower surfaces of the inner lead connecting part, and it was difficult to align the concave part and the hump at the tip of the inner lead. Furthermore, the occurrence of deformation of the tip of the inner lead during handling increases, which is a problem.

Another problem when connecting is that the top of the bump is almost flat, so when the inner lead is heated with a bonding tool, the molten metal is welded to the surface-treated metal on the inner lead and the bump on the outside of the bump. There was a problem in that it protruded as a bump (outside the semiconductor element).

According to the present invention, by forming a recess on the connection part side of the inner lead to prevent the gold-tin eutectic alloy, etc. that flows out at the time of connection from flowing out toward the inner lead support part, as described above,
This eliminates the problem of deterioration of the mechanical strength of the inner lead, and forms a pool of outflowing metal between the inner lead and the hump. It is possible to prevent the outflow of

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a method for forming protruding electrodes of a semiconductor device, in which protruding electrodes are formed on a plurality of electrode portions formed on the main surface of a semiconductor element. The thickness of the resist film with a part of the electrode having an opening is the inner resist film thickness and the outer resist film thickness of the electrode,
The outer resist film is formed to be thicker than the inner resist film, and a bump electrode is formed between these resist films so that the top of the bump is eccentrically formed inside the semiconductor element.

(Function) According to the present invention, the top of the height of the bump was conventionally located approximately at the center of the electrode, but according to the present invention, as described above, the top of the bump is placed toward the center of the semiconductor element of the electrode. The thickness of a partially opened resist film of the electrode having an opening is equal to the inner resist film thickness of the electrode and the outer resist film Wj! Since the outer resist film is formed to be thicker than the inner resist film and the bumps are formed at eccentric positions, a pool of flowing metal is formed between the inner lead and the bumps.

Therefore, it is possible to prevent metal from flowing out to the inner lead side or the corner portion of the semiconductor element.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a sectional view showing a process of forming a protruding electrode of a semiconductor device according to an embodiment of the present invention.

First, as shown in FIG. 1(a), on a semiconductor substrate 21 made of silicon, a phosphorus oxide film (SiO
An insulating film 22 made of a silicon nitride film (S+3N4) or the like and an electrode 23 made of aluminum or an aluminum alloy are formed by a method such as vapor deposition.
It is locally formed on the main surface of the semiconductor substrate 21 by a method such as etching. A connection metal film 24 and a barrier metal film 25 are respectively formed on the electrode 23, the connection metal film 24 is made of a metal such as Pt, Ti, Cr, etc., and the barrier metal film 25 is a metal film made of Cu, Ni, etc. be. These materials are not limited. Further, it can be selected depending on various uses and conditions.

A first resist film 26 is formed on the electrode made of the various materials mentioned above.
is formed, the electrode section 28 is energized, and the bump 30 is plated and grown. The conductive film formed on the entire surface and through which a current for bump plating is passed is not shown.

Furthermore, a first resist film 26 is formed on the main surface of the semiconductor substrate 21 by a method such as spin coating, and a resist opening 29 is formed by a method such as development or etching.

Thereafter, a second resist film 27 is formed, and the second resist film 27 having a predetermined shape is formed by the same method as the first resist film 26, such as development or etching. The first resist film 26 and the second resist film 27 may be formed under the same conditions, or by different methods.
Resist openings are formed by using a photosensitive resist that forms openings by exposure and development, or by masking and etching.

The resist openings 29 may be formed when the first resist film 26 is formed, or the second resist film 27 may be formed and then the two resist films may be opened at the same time. You can also do this. Mainly, a second resist #2 is applied on the outer side of the electrode 23 formed around the outer periphery of each unit element of the semiconductor substrate 21, that is, on the so-called outer periphery side.
7 is formed, and only the first resist film 26 is formed inside the electrode of each unit element formed on the main surface of the semiconductor substrate 21, thereby forming the resist film shown in FIG. Thereafter, it is placed in or brought into contact with a bump plating solution to conduct electricity to form a bump, and the resist is removed to obtain a bump 30 having the shape shown in FIG. 1(b). The shape of the bump 30 is such that the top portion 32 of the bump is shifted to the inside of each semiconductor element of the semiconductor substrate 21 with respect to the center line 31 of the electrode 23 .

As shown in FIG. 1(c), the amount of deviation d depends on the thickness of the inner lead 40 used for inner lead connection in the TAB mounting technique and the bonding tool used to connect (bond) the bump and the inner lead (not shown). size, load, temperature,
Various deviation amounts d are adjusted to the optimum value depending on the inner lead surface treatment metals and their thicknesses, the amount of molten metal 41 when the bumps 30 are heated, and the like. The same applies to the height of the bump.

The shape of the bump shown in Figure 1(b) is such that the resist film is thinner on the inside of each unit element and thicker on the outside, so that the plating solution can be applied well to the inside during the bump plating process. Because it flows, plating grows quickly and takes on an eccentric shape. Therefore, various deformed shapes can be obtained depending on the flow rate, temperature, etc. of the plating liquid during bump plating.

Note that the present invention is not limited to the above embodiments,
Various modifications are possible based on the spirit of the present invention, and these are not excluded from the scope of the present invention.

(Effects of the Invention) As described above in detail, according to the present invention, the top of the bump is formed so as to be shifted to the inside of the semiconductor element with respect to the center line of the electrode, so that the inner lead is bonded to the bump. This prevents the molten metal from flowing out and causing lumps at the bottom of the inner lead.

Further, since the joint portion (contact portion) is located on the inside, the area for holding the molten metal between the bump and the inner lead becomes large, and even if there is a large amount of molten metal flowing out, it can be held effectively.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of the process of forming protruding electrodes of a semiconductor device showing an embodiment of the present invention, FIG. 2 is a cross-sectional view of the vicinity of the connection between a lead wire and an electrode of a conventional semiconductor device, and FIG. 3 is a cross-sectional view of a conventional lead FIG. 7 is a cross-sectional view of the vicinity of the connection between the lead wire and the electrode of the semiconductor element, showing another example of the arrangement of recesses near the connection of the wire; 21... Semiconductor substrate, 22... Insulating film, 23...
Electrode, 24... Connection metal film, 25... Barrier metal film, 26... First resist film, 27... Second resist film, 28... Electrode portion, 29... Resist Opening, 30... Bump, 31... Center line of electrode, 32.
...Bump top, 40...Inner lead, 41...
molten metal. Patent Applicant Oki Electric Industry Co., Ltd. Agent Patent Attorney Mamoru Shimizu (1 other person) Revised 8 cases of 441 (Book y Waka!'s Project A ≧ My 1 Plan n Takashi Tomo J Takasei) Figure 1 Year t15D Ki 41 Dan Otsu Rit Hitsugi Junhi no Shika Danon p Memu Gakut Pamii Figure 2 Figure

Claims (1)

[Scope of Claims] A method for forming a protruding electrode of a semiconductor device in which protruding electrodes are formed on a plurality of electrode portions formed on a main surface of a semiconductor element, comprising: a resist film in which a portion of the electrode having an opening is opened; is formed such that the outer resist film is thicker than the inner resist film between the inner resist film thickness and the outer resist film thickness of the electrode, and the bump top is eccentrically formed inside the semiconductor element between these resist films. A method for forming a protruding electrode of a semiconductor device.