JP2006045651A - Method for producing copper post - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problems that, in the conventional method, a sufficient production can not be obtained, further, the bubbles of the air are left in a long and slender mask made of a resist, thus, in the case of a narrow product as a copper post with a size of ≤ϕ50 μm and a height of ≥50 μm, the time where satisfactory operation can not be performed has been generated, and further, equipment therefor uses a high mechanism, and is expensive in many cases. <P>SOLUTION: In this invention, the wettability of a chemical is secured by dry cleaning with plasma, and also, a copper post can be produced without the leaving of bubbles by using a rotary fixture. Further, the resist mask of the copper post is not formed at a time, but resist platemaking and copper post formation are repeated in portions, thus the production of the copper post at a high speed and with high precision is made possible. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

    The present invention relates to surface treatment.

  Until now, semiconductors have been mounted on metal frames called lead frames or glass epoxy substrates containing glass fibers. In recent years, products that are directly mounted on a substrate called a flip chip have come out, but the strength of the product is weak, and it has become a problem that not only mounting but also inspection work is difficult.

Recently, a wafer level chip size package has been developed to increase the strength but solve the problem, but the chip size is almost the same as the chip.
In order to increase the strength of the package, a copper post is used to relieve the stress caused by the difference in thermal expansion between the substrate and the chip due to the heat generated during mounting.

Japanese Patent Application 2000-361832 Japanese Patent Application 2002-207632

  As a method of manufacturing posts at any position with high accuracy at high speed using electrolytic copper sulfate plating as a mask, conventionally, the plating solution was sprayed by the paddle method or jet injection method, or negative pressure and positive pressure were alternately repeated. The copper post is manufactured by a method of changing.

  However, in the conventional method, not only the manufacturing speed of about 0.8 μm / min can be obtained, but the air is contained in an elongated mask made of a resist having a copper post diameter of φ50 μm or less and a height of 50 μm or more. Bubbles remain, and good work cannot be done. Moreover, many of the facilities use sophisticated mechanisms, and many of them are expensive in price.

  In the present invention, not only the remaining foam and the production speed are increased, but this problem is solved only with a simple rotating mechanism for the equipment.

  According to the present invention, the dryness of the plasma ensures the wettability of the chemical solution, and a copper post can be produced without bubbles by using a rotary jig.

  Also, instead of forming a resist mask for copper posts at once, by repeating resist plate making and copper post formation in several steps, the copper plating average current density is 5 A / dm 2 and the deposition rate is 1.0 μm / min or more. In addition, it has become possible to manufacture copper posts with a high accuracy of ± 5 μm at a height of 100 μm with an 8-inch wafer.

  Since sufficient hydrophilicity can be imparted to the resist surface by plasma cleaning, the chemical solution can easily enter the narrow resist opening.

  In addition, it is technically difficult to develop a resist with a thickness of 100 μm or more at a time, and there is a problem in accuracy. However, in the present invention, the resist plate is divided into several times to produce the most efficient. It becomes possible to form a resist having a good diameter and height, and a copper post can be manufactured at high speed and with high accuracy.

  In addition to spraying chemicals on the product by nozzle injection, the manufacturing equipment improves the foaming that occurs during production by rotating the entire surface to a negative pressure, and the chemicals are supplied sufficiently. Good production was possible even when the copper post diameter was about 30 μm.

  A thick film resist is applied to the copper wiring formed on the wafer, and after exposure with a mask of any shape, development is performed. In this case, the resist thickness is 0.5 to 1.0 times the copper post diameter and a maximum of 100 μm.

  The resist-made wafer is imparted hydrophilicity by plasma cleaning. The reaction gas uses oxygen, argon, CF4, etc. according to the situation.

  After cleaning, set the product on a jig and perform copper sulfate plating for post formation.

  In order to remove bubbles, the product is initially rotated at about 60 rpm / min, the surface of the product is made negative by centrifugal force, and then post formation is performed at about 20 rpm.

  In the case where the formation of the copper post is stopped approximately at the same level as the resist and the height of the copper post is further increased, the product is sufficiently washed and dried, and resist coating and plating are repeated on the resist plate.

  The relationship between the post diameter and resist thickness is 0.1 to 1.5 times the post diameter.

  The post formation process is shown in FIGS. Depending on the specifications of the diameter and height of the post, the case of skipping from step 5 (FIG. 5) to step 9 (FIG. 9), and step 6 (FIG. 6) to step 9 (FIG. 9) are repeated.

  Obtain a wafer with a redistributed seed layer formed (FIG. 1). If necessary, copper plating is performed on the entire surface of the wafer.

  A photosensitive plating resist is applied to the wafer of FIG. 1 using a spin coater or the like. (Fig. 2) THB-151N manufactured by JSR is used as the photosensitive resist. The wafer coated with the photosensitive plating resist is cured and sent to the next process.

  A wafer having the photosensitive plating resist shown in FIG. 2 coated on the entire surface is put on a mask corresponding to a pattern for forming a post and irradiated with ultraviolet rays. Then, it is immersed in a developing solution and the part which forms a post is opened. (Fig. 3) Use PD523 manufactured by JSR as the developer.

  The wafer (FIG. 3) in which the plating portion of the plating resist is opened is hydrophilized by plasma treatment. As conditions, oxygen ashing is performed for about 300 w 1 to 5 min. (Fig. 4)

  The wafer (FIG. 4) in which the post-growth portion is hydrophilized is copper-plated. (FIG. 5).

A photosensitive plating resist is again applied to the wafer of FIG. 5 and prebaked. (Fig. 6)
As in step 3, development is performed after irradiation with ultraviolet rays. (Fig. 7)

  In the same manner as in step 4, the portion to be post-plated and grown is made hydrophilic by plasma treatment. (Fig. 8)

  Copper plating is performed in the same manner as in step 5. (Fig. 9)

  The plating resist on the copper plated wafer (FIG. 9) is removed. (Fig. 10)

In the present invention, the foam in the resist cannot be removed conventionally when the thickness is 50 μm or less, but can be removed even when the thickness is 30 μm or less.

The seed layer of the wafer (FIG. 10) from which the plating resist has been removed is etched with a hydrofluoric acid diluted solution. (Fig. 11)
When copper plating is performed on the seed layer, copper is etched with an etching solution such as ammonium persulfate + sulfuric acid.

Redistributed seed layered wafer Resist coating Resist development Plasma cleaning Copper post forming copper plating Resist re-application Resist redevelopment Re-plasma cleaning Copper post forming re-copper plating Resist stripping Seed layer etching Copper plating unit diagram

Explanation of symbols

(1) Wafer (2) Seed layer (3) Plating resist (4) Copper post copper plating (5) Pump (6) Filter (7) Copper plating solution management tank (8) Rotating plating jig (9) Belt (10 ) Motor (11) Copper plating main tank (12) Liquid discharge groove (13) Liquid spray nozzle

Claims (4)

  Manufacturing method of performing copper post plating after plasma cleaning of wafer masked with resist and making resist surface and seed metal surface hydrophilic   A method of manufacturing a post of 30φμm to 300φμm by repeating a resist method of plating a copper post at a rate of 1 μm to 2 μm per minute several times   In order to increase the speed of copper plating, the liquid flow is generated by a nozzle, the liquid is exchanged, and the product mounted on the jig is rotated to eject the sprayed liquid to the outside. And plating equipment that can prevent foam biting Semiconductor wafer processed using the method of claims 1 to 3

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