JPH09223696A - Method and device for forming bump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a high quality bump with good operativity by removing an oxide film on the pad surface of semiconductor chip. SOLUTION: In a vacuum chamber 1, the first and second electrodes 2 and 3 and a metal melting furnace 12 are provided. And in the vacuum chamber 1, a plasma generation gas supply means 16 for providing argon gas is provided. With a chuck 4 provided at the second electrode 3, a semiconductor chip 5 is chucked, and under the condition, the first electrode 2 is applied with high frequency voltage for generating plasma. The oxide film an the surface of a pad 6 is removed by etching with plasma molecule or ion. Then, the semiconductor chip 5 is moved to above the melting furnace 12, and the pad 6 is submerged in a molten metal 15 in the melting furnace 12 so that a bump is formed on the surface of the pad 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bump forming apparatus and a bump forming method for forming bumps on pads of a semiconductor chip.

[0002]

2. Description of the Related Art As a bump forming method for forming a bump (protruding electrode) on a pad of a semiconductor chip, a plating method, a wire bump method, a molten metal adhering method and the like are known. The plating method is a method in which a metal is attached to the surface of the pad by a plating means to form bumps. The wire bump method is an application of a wire bonding technique, and is a method of forming a bump by bonding a wire to the surface of a pad. The molten metal deposition method is a method of immersing a pad in molten metal melted in a melting furnace to form bumps.

[0003]

However, in the plating method, when an oxide film is formed on the pad surface, bumps cannot be formed firmly, so it is necessary to form a barrier for preventing oxidation on the pad surface. However, there is a problem that productivity is low due to the necessity of the process. Incidentally, although aluminum is often used as the material of the pad, aluminum is extremely susceptible to oxidation when exposed to air.

The wire bump method is low in productivity because bumps must be formed one by one on the pad.
Further, there is a problem that the shape and dimensions of the bumps are likely to vary.

Further, in the molten metal deposition method, the quality of the bumps is apt to be deteriorated because the molten metal at a high temperature is easily exposed to the air and oxidized, and in order to remove the oxide film on the pad surface, an ultrasonic vibrator is installed in the melting furnace. There is a problem that ultrasonic vibration must be applied to the pad during immersion to remove the oxide film on the surface of the pad, for example.

Therefore, an object of the present invention is to provide a bump forming apparatus and a bump forming method capable of removing an oxide film on a pad surface of a semiconductor chip to form a high quality bump with good workability.

[0007]

To this end, the present invention provides a vacuum chamber, a metal melting furnace provided inside the vacuum chamber, a plasma generating means, and a semiconductor chip transfer means, and a plasma in the vacuum chamber. A bump forming device is configured from a gas supply unit that supplies a gas for generation,
After cleaning the surface of the pad of the semiconductor chip with the plasma generated by the plasma generating means, the semiconductor chip is transferred to above the melting furnace by the transfer means,
The pads on the lower surface are immersed in molten metal in a melting furnace to form bumps.

Plasma molecules and ions are generated in the vacuum chamber by plasma generating means, and the surface of the pad of the semiconductor chip in the vacuum chamber is cleaned by the plasma molecules and ions, and then the semiconductor chip is melted in a melting furnace. Of the semiconductor chip, the pad on the lower surface of the semiconductor chip is immersed in the molten metal in the melting furnace, and then the pad is lifted from the molten metal to form bumps, and then the semiconductor chip is removed from the vacuum chamber. I took it out.

[0009]

According to the present invention, a bump can be formed by removing an oxide film on a pad surface of a semiconductor chip with plasma molecules or ions and then immersing the pad in a molten metal of a melting furnace in a vacuum. .

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a bump forming apparatus according to an embodiment of the present invention. 1 is a vacuum chamber,
The interior thereof is partitioned into a left first chamber A and a right second chamber B. The first chamber A is provided with the elements described below. Reference numeral 2 denotes a plate-shaped first electrode, which is arranged on the left side of the first chamber A. A plate-shaped second electrode 3 is provided above the first electrode 2. A chuck 4 is provided on the lower surface of the second electrode 3. The chuck 4 chucks the semiconductor chip 5. A large number of pads 6 are formed on the lower surface of the semiconductor chip 5. The first electrode 2 is connected to a high frequency power source 7, and the second electrode 3 is grounded. The first electrode 2 and the second electrode 3 are plasma generating means.

The second electrode 3 is connected to a rod 9 extending from the vertical movement mechanism section 8. The vertical movement mechanism portion 8 is connected to the slider 10. Further, the slider 10 is fitted to a guide rail 11 arranged on the ceiling surface of the first chamber A, and is driven by a driving unit (not shown) to move laterally along the guide rail 11. That is, the slider 10 and the guide rail 11 serve as a transfer means for the semiconductor chip 5.

A metal melting furnace 12 is provided on the side of the first electrode 2. Reference numeral 13 is a heating wire, and 14 is its power source. When the heating wire 13 generates heat, the metal in the melting furnace 12 is melted and becomes the molten metal 15. The molten metal 15 is
For example, an alloy of tin and lead. Reference numeral 16 is a gas supply means for supplying a plasma generating gas, and supplies argon gas or the like to the first chamber A through a pipe 17. Reference numeral 18 denotes a vacuum pump that sucks the inside of the first chamber A under vacuum through a pipe 19.

The first chamber A and the second chamber B are partitioned by a first gate valve 21. A table 22 is provided in the second chamber B. Reference numeral 23 is a nitrogen gas supply means for supplying nitrogen gas to the second chamber B through the pipe 24. The second chamber B is also vacuumed by the pipe 25 and the vacuum pump 26. A second gate valve 27 is provided on the side of the second chamber B. A guide rail 28 is provided on the table 22.
Reference numeral 30 denotes a table, which is slidably mounted on the guide rail 28 via a slider 29. Driven by a driving unit (not shown), the table 30 slides on the guide rail 28 and moves between the first chamber A and the second chamber B. Reference numeral 31 is a transfer head for picking up the semiconductor chip 5 and taking it out of the second chamber B.

The bump forming apparatus is configured as described above, and a method of forming bumps will be described next. With the chuck 4 chucking the semiconductor chip 5, a high frequency voltage is applied to the first electrode 2. Then, the argon gas supplied from the plasma generating gas supply means 16 to the first chamber A enters a plasma state, and the plasma molecules and ions collide with the surface of the pad 6 to etch and remove the oxide film on the pad surface.

When the removal of the oxide film is completed, the semiconductor chip 5 is moved above the melting furnace 12 as indicated by the chain line, and the vertical movement mechanism 8 is driven there to lower the semiconductor chip 5 and the pad 6 Is immersed in the molten metal 15, and then the semiconductor chip 5 is raised. Then, the molten metal 15 adheres to the lower surface of the pad 6, and the molten metal 15 is naturally cooled and solidified to form bumps on the surface of the pad 6.

Next, the first gate valve 21 is opened and the table 30 is moved to the first chamber A as shown by the chain line. Next, the chucked state of the semiconductor chip 5 by the chuck 4 is released, and the semiconductor chip 5 is placed on the table 30. When the first gate valve 21 is opened, the vacuum pump 26 is driven to vacuum the inside of the second chamber B,
The pressure difference with the first chamber A is eliminated, and nitrogen gas is supplied from the nitrogen gas supply means 23. The nitrogen gas prevents the bumps formed on the pads 6 from being exposed to air and being oxidized.

Next, the table 30 is moved from the first chamber A to the second chamber B to transfer the semiconductor chip 5 to the second chamber B. 15 'is a bump formed on the pad 6 by the molten metal 15 as described above. Next, the second gate valve 27 is opened and the transfer head 31 is moved to the second position.
It is moved into the chamber B, and the semiconductor chip 5 on the table 30 is picked up and taken out from the second chamber B.
When the series of operations is completed as described above, the first gate valve 21 and the second gate valve 27 are closed, and the above operation is repeated.

[0018]

According to the present invention, after the oxide film on the pad of the semiconductor chip is removed by plasma in the vacuum chamber, the pad is bumped by immersing the pad in the molten metal in the melting furnace in the vacuum chamber. Since it is formed, the oxide film on the pad can be reliably removed, and the pad does not come into contact with air to form an oxide film again between the removal of the oxide film and the formation of the bump. Since the molten metal in the metal furnace does not come into contact with air and oxidize, extremely high quality bumps can be formed with high productivity.

[Brief description of drawings]

FIG. 1 is a sectional view of a bump forming apparatus according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vacuum chamber 2 1st electrode 3 2nd electrode 4 Chuck 5 Semiconductor chip 6 Pad 10 Slider 11 Guide rail 12 Melting furnace 15 Molten metal 15 'Bump 16 Plasma generating gas supply means

Claims (2)

[Claims] 1. A vacuum chamber, a metal melting furnace provided inside the vacuum chamber, a plasma generation means and a semiconductor chip transfer means, and a gas supply means for supplying a plasma generation gas to the vacuum chamber. After cleaning the surface of the pad of the semiconductor chip with plasma molecules or ions generated by the plasma generating means, the semiconductor chip is transferred to above the melting furnace by the transferring means, and the pad on the lower surface of the semiconductor chip is transferred to the inside of the melting furnace. A bump forming apparatus characterized by immersing in a molten metal to form bumps. 2. Inside the vacuum chamber, plasma molecules and ions are generated by plasma generating means, the surface of the pad of the semiconductor chip in the vacuum chamber is cleaned by the plasma molecules and ions, and then the semiconductor chip is melted. Transferred to the upper part of the furnace, where the pad on the lower surface of the semiconductor chip is immersed in the molten metal in the melting furnace, and then the pad is lifted from the molten metal to form bumps,
Then, the semiconductor chip is taken out of the vacuum chamber.