JPH04208532A - Forming method of bump electrode - Google Patents

Abstract

PURPOSE:To form a bump electrode easily by mixing and blending a bump electrode composition and metallic powder into a resist, exposing and developing a mixture and forming the bump electrode having the conductivity of a desired composition in specified height onto an aluminum electrode. CONSTITUTION:The outermost surface of a substrate 11 is coated with a resist 15, in which a metal (solder or Cu, Pb, Sn, In) or powder having conductivity is mixed and blended into a sensitizer (a resist). Exposure is conducted through a mask so that the resist 15 is left on one part on an aluminum electrode 13, developing is performed, and a bump electrode 16 is formed onto the aluminum electrode 13. Accordingly, the bump electrode can be formed simply by exposure and developing, and positive metallic melt-connection with a connecting terminal can be conducted.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention is based on T A B (Tape Automate
The present invention relates to a method for forming bump electrodes used in d bonding.

(Prior Art) Conventionally, as technologies in this field, there have been the following, for example.

FIG. 2 is a sectional view showing the process of forming such a conventional bump electrode.

First, as shown in FIG. 2(a), an aluminum electrode pad 2 is placed on a semiconductor chip (hereinafter simply referred to as Sennobu)
A protective layer 3 is formed except for the electrode portion.

Next, as shown in FIG. 2(b), a conductive paint 4 made of a photocurable resin and conductive powder is applied. The conductive paint 4 may be one that exhibits sufficient isotropic conductivity and has photosensitivity, such as Evoquin acrylate oligomer, acrylate monomer, or acrylated polyimide resin. . Furthermore, although it is possible to use noble metal powder as the conductive powder, metal oxide powder such as tin oxide, indium oxide powder, etc. is preferable from the viewpoint of stability of characteristics after mounting. These fine powders are uniformly dispersed in the resin to form a paint, which is uniformly coated on the entire surface of the wafer on which the chimps 1 are formed using a spinner, a roll coater, or the like. The thickness at this time needs to be such that the final thickness is 5 to 50 μm. After coating, the temperature is maintained at a temperature of 8
Pre-dry at 0-100'C). After drying, see Figure 2 (
As shown in c), after exposure through the mask 5 corresponding to the aluminum electrode pad 2 portion of the chip 1, the second
As shown in Figure (d), the unexposed areas are developed with a developer and removed. The isotropic conductive layer formed on the aluminum electrode pad 2 is post-cured and sufficiently oxidized. Next, the second
As shown in Figure (e), an adhesive sheet 6 formed into a sheet by adding and dispersing conductive powder to a synthetic resin is laminated onto the above-mentioned wafer or is made into a paint and coated by printing.

The purpose of forming this second layer is to provide electrical connection and adhesive fixation of the chip to the required circuit board. Therefore,
The negative conductive layer and the electrodes of the circuit board must be electrically connected. The second layer adhesive sheet 6 also needs to be insulative in the horizontal direction (film direction) and conductive in the vertical direction. Therefore, it is sufficient to add a small amount of the conductive powder 7 to the adhesive sheet 6, and it is necessary that the conductive powder 7 be added to an extent that does not cause contact between the powder particles when formed into a film. The resin may be thermoplastic, thermosetting, or a mixture. Typical thermoplastic resins include saturated polyester, polyethylene, polypropylene, and polyamide resins, and thermosetting resins include phenolic resins, ring-formalin, formalin, and oxidized resins. As the conductive powder 7,
- Metal oxides, carbon dioxide, graphite, or powdered products of these may be used.

The -th isotropic conductive layer was mixed with the following materials using a ball mill, defoamed, and made into a paint.

In other words, the best photonic resin is Photonice #310.
0.100 parts by weight as the conductive powder, 300 parts by weight of Mitsubishi Metals ■Tin oxide powder T-1, as the solvent, 10 parts by weight of Kanto Chemical ■N-methyl-2-pyrrolidone, as the second adhesive layer: The ingredients are mixed into a paint using a ball mill,
It is formed into a notebook shape with a thickness of 30 μm using a flow coater on the base film coated with the release side. The polyester resin was Toyobo's Byron GK-103, 100 parts by weight, the conductive powder was Electrochemical Acetylene Blank, 13 parts by weight, and the solvent was Kanto Kagaku's MEK, 40 parts by weight.
- 2cc of isotropic conductive layer paint on a 4 inch wafer
After dropping, 500 rpm for 5 seconds, 3000 rpm
Spin control was performed for 20 seconds. Then 80°C
After pre-drying for 60 minutes, the mask was placed in close contact with the mask, irradiated with violet light (light intensity: 4 mW/cd) for 60 seconds, and a developer solution (N-methyl 2-pyrrolidone, dimethylformamide-50: 50
) was developed. Furthermore, 300°C30 minutes, 400°C3
It was cured for 0 minutes to form an isotropic conductive layer. The height of the bump at this time was 15 μm. Next, the second layer of adhesive sheet was laminated at a roll surface temperature of 70 DEG C., and the entire surface of the wafer was laminated. This wafer was diced into a predetermined 1,000-knob size using a dicing saw to obtain a 1,000-knob finished product with bumps formed thereon. After aligning this chip with a circuit board (a circuit board with a transparent electrode film formed on glass), it was pressed from the back side of the chip at a pressure of 30 kg/c4 using a heat-pressing tool at 150'C. After that, we cooled it down, connected the necessary terminals such as electrical signals and power supply, and confirmed that normal output could be obtained.

(Problem to be Solved by the Invention) However, in the method for forming bump electrodes described above, a paint (isotropically conductive) consisting of a photocurable resin and conductive powder is applied, and the conductive powder is formed by exposure, development, complete curing, etc. Form a resin bump containing
The external terminal is adhesively connected to the external terminal using a thermoplastic resin, but the adhesive strength of the thermoplastic resin containing conductive powder deteriorates over time due to volume shrinkage after softening and adhesion, resulting in reliability problems.

The present invention eliminates the above-mentioned problems and provides for connection of bumps made of photocurable resin formed on electrodes with external terminals.
By heat-treating the bump formed from the material mixed with the photocurable resin and conductive metal powder, the organic matter is carbonized, a conductive solidified bump containing the conductive metal powder is formed, and the bump is connected to an external terminal. An object of the present invention is to provide a method for forming a bump electrode with excellent reliability, which enables connection with a terminal by metal fusion connection.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a method for forming a bump electrode in which a bump electrode is formed by scraping the aluminum of a semiconductor substrate having an aluminum electrode formed on the main surface. , a step of forming a resist layer by mixing and blending a conductive material into a resist on the main surface of the semiconductor substrate; a step of selectively heating and carbonizing the renost layer on the aluminum electrode; and a step of carbonizing the renost layer on the aluminum electrode. Bump electrodes are formed by removing the other portions, leaving only the treated portions.

(Function) According to the present invention, as described above, in the method for forming a bump N-electrode, a photosensitive agent in which a conductive powder is mixed and blended into a photosensitive agent and a resist 1 (photocurable resin) is applied to a semiconductor substrate. The photosensitive agent is coated on top of the aluminum electrode, exposed and developed so that the photosensitive agent remains on a portion of the aluminum electrode, and bumps made of the photosensitive agent are formed on the aluminum electrode.

Therefore, bump electrodes can be easily formed by exposure and development, and moreover, reliable metal fusion connection with connection terminals can be achieved.

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

FIG. 1 is a cross-sectional view showing the process of forming a bump electrode according to an embodiment of the present invention.

First, as shown in FIG. 1(a), an insulating film 12 is formed on the main surface of a substrate 11 made of silicon or the like by a method such as thermal oxidation.
form. On this insulating film 12, an aluminum electrode 13, which is an external lead electrode, is formed at a predetermined portion by etching or the like. Then, a protective film 14 such as a panonhesion film with a part of the aluminum electrode 13 opened is formed, and the protective film I
4 protects the semiconductor circuit etc. from external moisture, external mechanical force, etc.

On the outermost surface of the substrate 11 having such a surface structure, metal (
A resist 15 containing solder (C, U, Pb, Sn, In) or conductive powder is applied.

Next, as shown in FIG. 1(b), exposure is performed through a mask (not shown) so that the resist 15 remains on a portion of the aluminum electrode 13.

Next, development is performed and the image shown in FIG. 1(c) is placed on the aluminum electrode 13.
Bump electrodes 16 are formed as shown in FIG.

Regarding the conductivity of the bump electrode 16, if it is the resist pattern 5 that has been given conductivity from the beginning, it may be left as it is, but as a method to improve the conductivity, after forming the bump electrode 16, Heat treatment is performed to about °C to carbonize the organic matter and form bumps. When increasing electrical conductivity, the metal powder (filler) mixed and blended to impart electrical conductivity and as a solid maintenance agent is preferably a material that does not oxidize the surface of the powder when heated. For example, gold powder, platinum powder,
N1 powder etc. Further, the atmosphere is not limited to this as long as it can prevent surface oxidation of the metal. The shape of the powder may be granular or monofilamentous, and the shape is not limited.

The method of applying the resist 1- may also be spin coating, botting, or the like. Further, in forming the resist film, it may be a single layer or may be formed of any number of layers.

Regarding carbonization treatment, temperature, and carbonization atmosphere, N2
The atmosphere can be selected depending on various conditions.

Furthermore, the thickness of the resist can be set depending on the desired bump height.

Furthermore, it is also possible to form another type of resist film on the resist film of the present invention to improve the resolution during development.

As described above, the metal-containing carbide bump enables connection to the connection terminal by metal melting.

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, bump electrode composition and metal powder are mixed and blended into renost, exposed and developed, and a predetermined height is formed on the aluminum electrode. As a result, a bump electrode having a desired composition and conductivity can be formed, so that a bump electrode can be formed by simple heating, and a reliable and easy metal fusion connection with a connecting terminal can be made. . Moreover, an inexpensive bump electrode can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing a process for forming a bump electrode according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view showing a process for forming a conventional bump electrode. DESCRIPTION OF SYMBOLS 11... Substrate, 12... Insulating film, 13... Aluminum electrode, 14... Protective film, 15... Resist, 16...
...Bump electrode. Patent applicant Oki Electric Industry Co., Ltd. Agent Patent attorney Mamoru Shimizu (2 others) 15 Lens I- (7 compliments 1 J Nozomi) /3 /;i back plate i3 /'/ //Otsu Hai ) Buden Libun 73 Tsunomoto Moxibustion Ha7a Raimaki no Kataku*L'a'6 Phase 4 Figure 1

Claims (1)

[Scope of Claims] A method for forming a bump electrode in which a bump electrode is formed on the aluminum electrode of a semiconductor substrate having an aluminum electrode formed on the main surface, comprising: (a) a conductive layer formed in a resist on the main surface of the semiconductor substrate; (b) selectively heating and carbonizing the resist layer on the aluminum electrode; (c) leaving the carbonized portion and forming a resist layer; A method for forming a bump electrode by removing a portion and forming a bump electrode.