JPH01135046A - Formation of external electrode in electronic part - Google Patents

Abstract

PURPOSE:To form the title electrode with a fine pitch and hence with high accuracy by bringing a photomask into close contact with a photoresist film via an anti-sticking agent, exposing and developing the photomask, and forming an opening through the photoresist film facing a connecting electrode. CONSTITUTION:A connecting electrode 4 and an insulating film 5 are formed on a silicon wafer 1, and the connecting electrode 4 is exposed through an opening 5a formed through the insulating film 5. And, an intermediate connecting film 6 and a gold thin film 7 are formed on the upper surface of the connecting electrode 4. Further, a highly viscous photoresist solution 9a is dropped on the the upper surface of the gold thin film 7, and spread out into a predetermined thickness by spinning the silicon wafer 1. Thereafter, an anti-sticking agent 11 is dropped onto the photoresist film 9b for coverage of the latter, and a photomask 12 is placed on the photoresist film 9b via the anti-sticking agent. Hereby, accurate exposure can be assured in a close contact relation between the photoresist film and the photomask, and a good accuracy plating opening can be formed. Thus, a protruding gold bump 10 can be formed on the connecting electrode 4 with high accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application 1] This invention relates to a method for forming external electrodes in electronic components.

[Prior Art] Conventionally, when interconnecting electronic components, the electrodes of one electronic component are formed to protrude, and this protruding electrode
For example, so-called TAB (↑ape Automate), which bonds the finger leads of a tape carrier and an IC pellet,
An example of this is the d Bonding method. This T
In the A B method, protruding external electrodes called bump electrodes are usually formed on the IC pellet.

This external electrode is 20 to 301L in order to separate the connection leads such as finger leads from the surrounding area and prevent short circuits.
It is necessary to have a height of about 1.5 m, and it is attached by plating to a connecting electrode, which is usually called a pad, provided on the IC pellet. During this plating, a photoresist film is placed on one surface of the IC pellet, this photoresist film is exposed and developed, openings are formed at predetermined locations in the photoresist film, and plating is performed through these openings.

[Problems to be Solved by the Invention] In the method for forming external electrodes as described above, regardless of whether a wet or dry method is used for the photoresist film, the film becomes thick, so the amount of exposure of the upper and lower layers is different. There will be a difference between the two, making it difficult to develop the lower layer side. Therefore, the thickness has conventionally been several #Lm. Therefore, since the external electrode is thicker than the photoresist film, it will be attached so as to protrude above the photoresist [. The widened part will be wider. The amount of this width is naturally proportional to the amount by which the external electrode protrudes from the photoresist, and there is a problem in that the wider the width, the more difficult it is to achieve fine pitch.

This invention was made in view of the above-mentioned 19 circumstances, and its purpose is to use a photoresist that can be thickened, reduce the amount of wide external electrodes, and achieve fine pitch. Provided is a method for forming an external electrode in an electronic component, in which the external electrode can be formed with high precision, and a photomask placed on a photoresist can be easily and efficiently installed and removed. It's about doing.

[Means for Solving the Problems] In order to achieve the above-mentioned purpose, this invention involves dropping a relatively high viscosity photoresist liquid onto the connection electrode forming surface of an electronic component, and then spinning the electronic component. Then, a photoresist solution is spread to a uniform predetermined thickness to form a photoresist film, this photoresist film is pre-dried, and the entire surface of the photoresist pattern 1 is coated with an anti-sticking agent, After that, a photomask is closely attached to the photoresist film via the anti-sticking agent, and the photoresist film is exposed and developed to form an opening facing the connection electrode in the photoresist film. Then, a protruding external electrode is formed by plating on the connecting electrode of the electronic component through this opening.

[Function 1] According to the present invention, a relatively high viscosity photoresist liquid is dropped onto the connecting electrode forming surface of an electronic component, and then the electronic component is spun to coat the photoresist liquid to a uniform predetermined thickness. By spreading the photoresist film, the thickness of the photoresist film can be made thicker than the external electrode. Moreover, after pre-drying the photoresist film, the entire upper surface was coated with an anti-sticking agent, so the photoresist H
When the photomask is placed on the tl, the photomask does not bite into the photoresist film and can be placed well, and the photomask can be easily and well peeled off after the prescribed processing. can. Furthermore, a photomask is brought into close contact with the photoresist film to
By exposing and developing the portion facing the connection electrode in this state, an opening is formed in the photoresist film, so the opening can be formed with high precision. A protruding external electrode can be formed with high precision by plating on the connecting electrode of an electronic component through the opening, and since the external electrode does not protrude above the photoresist, the width of the external electrode can be minimized. keep it to a minimum,
It is possible to achieve fine pea two-chi.

[Embodiment] Hereinafter, an embodiment in which the present invention is applied to a semiconductor device will be described with reference to FIGS. 1 to 4.

FIGS. 1 and 2 show the steps of forming external electrodes of a semiconductor device. A method for forming external electrodes will be described with reference to these figures. First, as shown in FIG. 1(A), a 7-layer photoresist solution 9a is dropped onto a silicon wafer l.

In this case, as shown in FIG. 2(A), the silicon wafer l has an internal electrode 2 such as a gate and an insulating film 3 made of silicon oxide formed thereon in advance, and the internal electrode 2 is formed on this insulating film 3. I! made of aluminum or aluminum alloy connected to In addition to forming the common electrode 4, an insulating film 5 made of silicon nitride is formed on the connecting electrode 4 and the insulating film 3, and the connecting electrode 4 is formed on the insulating layer 5.
An opening 5a corresponding to the opening 5a is formed by etching except for the peripheral edge thereof, and a connection electrode 4J is exposed from this opening 5a:
By sequentially vapor-depositing or sputtering a titanium-tungsten alloy and gold, an intermediate connecting film 6 made of a titanium-tungsten alloy and a thin gold film 7 made of gold are formed, each with a thickness of several thousand λ, on the connection electrode 4 and insulating film. It has a structure in which layers are formed over the entire film 5. In this state, as shown in FIG. 1(A), a photoresist solution 9a is dripped onto the gold wire pattern 7 located at the top using a dispenser 8. This photoresist solution 9a
The photoresist used has a viscosity of several hundred to several thousand cps (centivoids), which is several times to several tens of times higher than a normal photoresist (for example, BMR-1000 manufactured by Tokyo Ohka Kogyo Co., Ltd.).

Thereafter, the silicon wafer l was rotated and one drop of the photoresist solution 9a was applied by spin coating, as shown in FIG.
As shown in R) and FIG. 2(B), a photoresist pattern 9b is formed on the surface of the gold thin film 7 on the silicon wafer 1. In this case, the rotation speed is several hundred rpm at the beginning, several hundred rpm in the middle, and several hundred rpm at the end, which is almost the same as the beginning.
It is controlled in three stages. In this embodiment, the rotation speed is selected in three stages so that the thickness of the photoresist film 9b is about 30 μm, which is thicker than the height of the gold bumps 10, which will be described later.

After the photoresist 11Q9b has been formed to a predetermined thickness (approximately 30 JLm) in this way, the photoresist film 9b is pre-dried, the anti-sticking agent 11 is dropped onto its surface, and the silicon wafer 1 is removed again. Spread it by rotating at high speed (several thousand rpm) and
As shown in Figure (C), the anti-sticking agent 11 is formed into a uniform film having a thickness of about 1000λ. This anti-sticking agent 11 prevents the photomask 12 from sticking to the photoresist film 9b, and also prevents the photomask 12 from sticking to the photoresist film 9b after a predetermined process described later. An organic solvent (for example, A-9 manufactured by Tokyo Ohka Kogyo Co., Ltd.) whose main components are aliphatic hydrocarbons and aromatic hydrocarbons is used to facilitate A-polishing.

Thereafter, after drying the photoresist v9b and the anti-sticking agent 11, as shown in FIG. 1(D) and FIG. In this case, since the photoresist film 9b is thick, it takes time to completely dry it, but by performing the above-mentioned sticking prevention treatment, the photomask 12 is Alignment can be performed in a series of automated steps. Then, the photoresist film 9a is exposed through the photomask 12,
This exposed photoresist film 9b is developed. In this case, since the photomask 12 is in close contact with the photoresist film 9b, accurate exposure can be performed. Thereby, the exposed portion, that is, the portion of the photoresist film 9b shown by the dotted line in FIG. 2(D) is removed by a development process to form an opening for plating. After plating gold (Au) on the gold thin film 7 through the opening thus formed and forming gold bumps lO as shown in FIG.
Then, the intermediate connecting film 6 is etched to remove unnecessary parts, that is, parts of the thin gold W27 and the intermediate connecting film 6 that do not correspond to the gold bumps IO. As a result, the gold thin film 7 is placed on the connection electrode 4 of the silicon wafer l via the intermediate connection W26.
An external electrode 13 is formed of the gold bump 10 and the gold bump 10 .

Therefore, according to the method for forming the external electrode 13 as described in L, the connection electrode 4 and the insulating film 5 are formed on the silicon wafer l, and the connection electrode 4 is exposed through the opening 5a of the insulating film 5. An intermediate connection film 6 and a thin gold film 7 are formed on the upper surface of the thin gold film 7, and a highly viscous photoresist liquid 9a is dropped onto the upper surface of the thin gold film 7.The silicon wafer l is then spun to coat the photoresist liquid 9a in a uniform predetermined area. Since the photoresist film 9b is spread to a thickness of , the thickness of the photoresist film 9b can be uniform and thicker than the gold bumps 10. After that, the anti-sticking agent 11 is dropped onto the photoresist 1199b to coat it, and the anti-sticking agent 11 is coated on the photoresist 1199b.
1g of photoresist through 1! Since the photomask 12 is placed on the photoresist IIQ9b, the photomask 12 does not bite into the photoresist IIQ9b, and can be placed in close contact with the photoresist IIQ9b. 12 photoresist 1199
b It can be easily and well peeled off from above. Moreover, the photomask 12 is replaced by a photoresist Il! Since exposure is carried out in close contact with I9b, accurate exposure is possible, and by developing the exposed area,
Openings for plating can be formed with high precision. As a result, the protruding gold bumps 10 can be formed with high precision on the connection electrodes 4 through the plating openings by plating. In this case, the gold bumps 10 are connected to the photoresist film 9.
Since the gold bumps 10 do not protrude upward, the wide IM of the gold bumps 1O can be minimized and a fine pitch can be achieved.

Next, with reference to FIGS. 4 and 5, a case will be described in which finger leads are connected to the external electrodes of the semiconductor device configured as described above. In this case, first, the silicon wafer 1 is cut by a die sink and separated into a plurality of semiconductor pellets 20 . A large number of the above-mentioned external electrodes 13 . . . are arranged on the separated semiconductor pellet 20 . In addition, the finger leads 21... have a copper foil 21b plated with solder 21a on the surface thereof, which is laminated onto the tape carrier 22, and patterned into a predetermined shape by etching, and each end on the center side is attached to the tape. A square hole 22a formed in the center of the carrier 22
The semiconductor pellet 20
are arranged in correspondence with the respective external electrodes 13 . When connecting the finger leads 21 to each of the external electrodes 13 of the semiconductor pellet 20, the finger leads 21 are made to correspond to each of the external electrodes 13 and bonded by thermocompression. As a result, a gold-tin eutectic is formed between the gold bump 10 of the external electrode 13 and the solder 21a on the surface of the finger lead 21, resulting in a good connection. Thereafter, a protective resin 23 is potted onto the semiconductor pellet 20 to cover and protect the semiconductor pellet 20, and the semiconductor pellet 20 is cut at the portion shown by the chain line in FIG. As a result, a semiconductor pellet 20 in which the figure lead 21 is connected to the external electrode 13 is obtained.

In addition, in the embodiment described above, the connection electrode 4 and the external electrode 13
Although a titanium-tungsten alloy is used for the intermediate connection film 6 formed between the
)-chromium (Or) alloy, tungsten (w)-titanium (Ti) alloy, platinum (pt)-titanium (Ti) alloy, palladium (Pd)-titanium (Ti) alloy, etc. may be used.

Effects of IJI from E] As described in detail above, according to the present invention, a relatively high viscosity photoresist liquid is dropped onto the connection electrode forming surface of an electronic component, and then the electronic component is spun. The photoresist solution is spread to a uniform predetermined thickness to form a photoresist film, the photoresist film is pre-dried, the entire upper surface is coated with an anti-sticking agent, and then the photoresist is By exposing a photomask to the film through an anti-sticking agent and developing it, an opening is formed in the photoresist film facing the connection electrode, and an electronic component is connected through this opening. Since a protruding external electrode is formed by plating on the external electrode, by using a photoresist that can be made thick, the amount of wide external electrode can be reduced.
Not only can a fine pitch be achieved, the external electrodes can be formed with high precision, and the anti-sticking agent not only prevents the photomask from biting into the photoresist film, but also makes it possible to easily and easily form the external electrodes after prescribed processing. It can be peeled off well.

[Brief explanation of the drawing]

1 to 5 show an embodiment of the present invention, and FIGS. 1(A) to 5(D) are side views showing the manufacturing process of the external electrode,
Figures 2 (A) to (1)) are enlarged sectional views showing the main parts, Figure 3 is an enlarged sectional view showing the completed state, and Figure 4 is an enlarged view of the state in which the finger leads are connected to the external electrodes. cross section,
FIG. 5 is a plan view of a tape carrier with semiconductor pellets mounted thereon. ■...Silicon wafer, 4...Connection electrode, 9a...Photoresist solution, 9b...
... Photoresist film, 10 ... Gold bump,
11... Swelling part, 12... Photomask. Figure 1 fS Haku
ω 1-no 4th
Figure 5

Claims (1)

[Scope of Claims] A method for forming an external electrode in an electronic component, in which a protruding external electrode is formed on a connecting electrode of an electronic component by plating through an opening formed in a photoresist film, comprising: A relatively high viscosity photoresist solution is dropped onto the electrode formation surface, and the electronic component is spun to spread the photoresist solution to a uniform predetermined thickness to form a photoresist film. After pre-drying the film, the entire surface of the photoresist film is coated with an anti-sticking agent, and then a photomask is brought into close contact with the photoresist film via the anti-sticking agent, and the photoresist film is exposed to light. ,
A method for forming an external electrode in an electronic component, comprising forming an opening in the photoresist film that faces the connection electrode by developing the photoresist film.