JPH04225234A - Bump forming method and bump tape used therefor - Google Patents

Abstract

PURPOSE:To improve economy and workability in forming a bump in highly integrated semiconductor element having many terminals by forming a bump- composition metal layer on a tape substrate, compressing the layer to an electrode, separating and peeling the bump-composition metal from the tape substrate by the emission of light from an optical system, transferring the metal on the electrode, and forming the bump. CONSTITUTION:An acryl-based bonding agent 12 is coated on the partial surface of a tape substrate 10. A bump-composition metal layer 13 is formed on the coating. A bonding metal 14 is formed by a method such as pressure welding and vapor deposition, and a band tape 15 is formed. Meanwhile, an aluminum electrode 18 which is an external electric lead-out electrode is formed on an insulating film 17 on the surface of a semiconductor substrate 18. The bump tape 15 is pushed and stuck to a part of the aluminum electrode 18 of the semiconductor substrate 16. An adhesive material 12 is solidified with ultraviolet ray or laser 20 so as to decrease adhesive strength. The bump-composition metal layer 13 is peeled from a tape substrate 10 and transferred to a part of the exposed surface of the aluminum electrode 18. Thus, the transferred bump 11 is formed.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] This invention applies to TAB (Tape
The present invention relates to a method for forming bumps on electrodes of a semiconductor element in automated bonding (Automated Bonding) mounting technology, and a bump tape used in the method.

0002

[Prior art] As shown in FIGS. 4 and 5, for example,
2-2-211937 will be described.

In FIG. 4, the capillary 3 is lowered,
The metal ball 5 is thermocompressed onto the electrode 2 of the semiconductor chip 1 by bonding. Next, with the clamper 8 opened and the metal wire 4 released, the capillary 3 is raised by a predetermined amount. When the capillary 3 has finished rising, the clamper 8 is closed to hold the metal wire 4, and the capillary 3
is reciprocated parallel to the element surface of the semiconductor chip 1.

[0004] Due to the reciprocating movement of the capillary 3,
A notch or metal fatigue occurs at the boundary between the metal wire 4 and the metal ball 5 due to stress concentration, and then the clamper 8 is moved upward to apply a tensile force to the metal wire 4 in an upward direction (in the Z-axis direction). . Then, the metal ball 5 and the metal wire 4 are separated from each other due to the influence of the notch generated at the boundary, and a bump 7 is formed.

In FIG. 5, in order to form a metal ball 5 on the electrode 2, a bonding load is applied to the capillary 3 (double-dashed line in the figure), and when the bonding load is removed (solid line in the figure), the capillary It is designed to perform 3 reciprocating movements. Therefore, capillary 3
The vertical momentum of the capillary 3 decreases, and due to the reciprocating movement, the boundary between the metal wire 4 and the metal ball 5 collides with the inner surface of the hole in the capillary 3 through which the metal wire 4 is conducted, so that the stress at the boundary decreases. The metal ball 5 and the metal wire 4 can be separated more quickly since diameter reduction and notches are likely to occur due to concentration.

[0006]

[Problems to be Solved by the Invention] However, in the method with the above structure, stress is concentrated at the boundary between the wire and the metal ball using the reciprocating motion of the capillary, an ultrasonic generator, etc., and a tensile force is applied upward to the metal wire. In this bump formation method, a metal ball and a metal wire are separated to form a bump, but since the time required per unit bump is relatively long, it is difficult to use a highly integrated multifunctional multi-terminal semiconductor. In the case of devices, the number of electrodes ranges from hundreds to thousands, which poses operational and economical problems.

In order to eliminate the above-mentioned problem that the unit bump formation time is relatively long, the present invention shortens the formation time per unit bump and improves the bump formation of highly integrated and multi-terminal semiconductor devices. The purpose of the present invention is to provide a bump forming method that is economical and has excellent workability.

[0008]

[Means and effects for solving the problem] This invention is based on TA
In forming a bump electrode provided on a semiconductor element electrode used as a connection means in B-mounting technology, a bump composition metal layer is formed on a tape base, a predetermined pressure is applied to the electrode, and the bump composition metal layer is applied to the tape base. The adhesive adhering the tape is irradiated with ultraviolet rays, lasers, etc. through the tape base to reduce the adhesive strength, and bumps are formed on the electrodes by transferring only the bump composition metal layer only to the portions that are in pressure contact with the electrodes. It was designed to do so.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 and 2 are schematic cross-sectional views for explaining the present invention.

In FIG. 1, a tape base 10 is a tape made of resin such as polyvinyl chloride or ethylene-acrylic acid copolymer. The thickness is approximately 30 to 60 μm, but various selections can be made depending on various conditions. Tape base 1
0 is coated with an acrylic adhesive (adhesive) 12, and the film thickness may be about 5 to 20 μm. Furthermore, a bump composition metal layer 13 is formed thereon to a thickness necessary to obtain the bump height. For example, solder grains are made into a clay-like form using pine tar or the like and formed on the tape base 10 by silk printing or a roller. Furthermore, a foil of a low melting point metal such as indium is formed as the adhesive metal 14 by a method such as pressure bonding or vapor deposition to form the bump tape 15.

On the surface of the semiconductor substrate 16 on which semiconductor elements are integrated, a silicon oxide film is formed as an insulating film 17, and an aluminum electrode 18 is formed as an external electrical lead electrode.
is formed. Furthermore, a passivation film is generally used in which a surface protection film 19 is formed with a portion of the aluminum electrode 18 opened.

The bump tape 15 is set in a predetermined manner on the aluminum electrode 18 of a semiconductor substrate having a general cross-sectional structure, and a second part is attached to a part of the aluminum electrode using a pressure welding jig (not shown). The bump tape 15 is pressed and adhered in the cross-sectional shape shown in the figure. After that, the adhesive 12 is solidified with ultraviolet rays or a laser 20 to reduce its adhesive strength,
The bump composition metal layer 13 is peeled off from the tape base 10 and transferred onto a part of the exposed surface of the aluminum electrode 18 to form a transfer bump 11.

FIG. 3 is a schematic cross-sectional view of transfer bumps 11 formed on aluminum electrodes. Even if the transfer bump 11 is then heated and processed to form a cone or a sphere, this is not excluded from the technical scope of the present invention.

Furthermore, due to the heat treatment, the adhesive metal 14 melts and becomes the same as the solder composition. The heat treatment dissolves the bump metal over the entire exposed surface of the aluminum electrode 18 and covers the entire surface, which is preferable because it protects the aluminum electrode from external moisture, aluminum corrosive ions, and the like.

The composition of the transfer bump 11 is solder,
Alternatively, it is sufficient to mix a conductive filler into the resin to maintain electrical conductivity, and the material is not limited to metals, conductive resins, or the like.

[0016]

As explained above, according to the present invention, a bump composition metal layer necessary for forming a predetermined bump is formed on a tape base in advance to a predetermined thickness, and is bonded to an electrode by pressure.
Bump formation is economical by irradiating optical systems such as ultraviolet rays and lasers through the tape base, separating and peeling the bump composition metal layer from the tape base and transferring it onto the electrode. In addition, we can expect a significant improvement in the workability of highly integrated, multi-functional, multi-terminal semiconductor devices.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of an embodiment of the present invention.

FIG. 2 is a cross-sectional view of each embodiment of the present invention.

FIG. 3 is a cross-sectional view of each embodiment of the present invention.

FIG. 4 is a diagram showing a conventional bump formation technique.

FIG. 5 is a diagram showing a conventional bump forming technique.

[Explanation of symbols]

10 Tape base 11 Bump 12 Adhesive 13 Metal layer 14 Adhesive metal 15 Bump tape

Claims (3)

[Claims] 1. A bump in which a bump tape is placed on an external lead-out electrode provided on the main surface of a semiconductor element, and is pressed against the external lead-out electrode to transfer a part of the bump composition metal layer to the external lead-out electrode to form a bump. Formation method. [Claim 2] The transfer bump is formed into a circular cone shape by a method such as heating.
Alternatively, the bump forming method according to item 1, characterized in that a spheroidization process is performed. 3. A bump tape in which a bump composition metal layer is formed on a tape base, and a metal layer adhesive to an external lead-out electrode is formed on the bump composition metal layer.