JP2002270565A - Mounting substrate surface treatment method and equipment - Google Patents

Abstract

(57) [Problem] To provide a mounting substrate surface treatment method and apparatus capable of performing processing in a short time without corroding electrodes even after exposing the mounting substrate to the atmosphere after processing. SOLUTION: A reaction gas is introduced while exhausting a reaction chamber 1, and a high-frequency power is applied between a high-frequency electrode 5 in the reaction chamber 1 and a counter electrode 6 opposed thereto to generate plasma,
In the mounting substrate surface treatment method in which the mounting substrate 10 is mounted on the high-frequency electrode 5 and subjected to plasma processing, first, argon gas is introduced and plasma processing is performed, and then oxygen gas is introduced for a short time to perform plasma processing and redeposition. The Br was removed to prevent electrode corrosion. In addition, an oxygen gas is first introduced to perform a plasma treatment, and oils and organic substances adhering to a mounting substrate are removed in advance, and then an argon gas is introduced to perform a plasma treatment, so that the treatment can be performed in a short time. .

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for treating a surface of a mounting substrate, wherein the surface of the mounting substrate is cleaned or modified by plasma.

[0002]

2. Description of the Related Art In the field of mounting technology, high-density mounting is required as electronic devices become smaller and more sophisticated. Therefore, the connection of the element to the mounting board is miniaturized,
There is a need for a more reliable implementation.

[0003] As one of methods for ensuring reliability, a method of modifying the surface of a mounting substrate by plasma is known. For example, by removing organic contaminants attached to the surface by plasma treatment, the bonding strength of wire bonding can be improved, and the adhesion between the substrate and the sealing resin can be improved by improving the wettability. .

Further, wire bonding is performed by removing inorganic substances such as nickel hydroxide deposited on the electrode surface composed of three layers of copper, nickel, and gold (bonding bonding surface) on a printed circuit board by sputtering using argon plasma. In this case, the bonding strength with the gold electrode can be improved.

An example of a conventional plasma process using an argon gas will be described with reference to FIG. In FIG. 4, 2
Reference numeral 1 denotes a reaction chamber, which has a vacuum exhaust port 22 and a reaction gas inlet 23 and is grounded. In the reaction chamber 21, a high-frequency electrode 25 is provided between the reaction chamber 21 and the reaction chamber 21 via an insulating ring 24, and is configured to mount a mounting board 29 thereon. Further, a counter electrode 26 which is opposed to the high-frequency electrode 25 and grounded is provided in the reaction chamber 21. The high-frequency electrode 25 has a matching tuner (not shown),
The high-frequency power supply 27 applies high-frequency power through a high-frequency power supply unit. An O-ring (not shown) is interposed between the high-frequency electrode 25, the insulating ring 24, and the reaction chamber 21, so that the vacuum of the reaction chamber 21 is maintained, and the O-ring is not heated to 200 ° C. or more. A cooling groove 28 through which cooling water flows is provided.

[0006] A method for treating the surface of a mounting board with the above configuration will be described. While introducing 50 sccm of argon gas from the reaction gas inlet 23, 200 W was applied to the high-frequency electrode 25 while maintaining the degree of vacuum in the reaction chamber 21 at 30 Pa.
When high-frequency power is applied, plasma is generated. The surface of the mounting substrate 29 exposed to the plasma is irradiated with argon ions present in the plasma. The material of the mounting substrate 29 is glass epoxy, and as shown in FIG. 5, the electrodes 30 on the surface are made of copper 31 (thickness 35 μm), nickel 32
(Thickness: 3 μm) and gold 33 (thickness: 0.05 μm), and the underlying nickel 32 is transferred to the surface of the gold 33 by a heat process, etc. Etc. are precipitated. This nickel hydroxide is removed by sputtering with irradiation of argon ions, and the surface of the gold 33 is cleaned.

[0007]

However, when the plasma treatment is performed by the above method, the mounting substrate 29 is also sputtered simultaneously with argon ions. Therefore, when the material of the mounting substrate 29 is a glass epoxy substrate, The contained Br (bromine) adheres again to the surface of the electrode 30. When Br adheres to the electrode 30 on the mounting board 29, when exposed to the atmosphere, the Br reacts with the moisture in the air to produce H.
OBr and HBr occur, which causes a problem of corrosion of the electrode 30.

When the solder-printed mounting board 29 passes through a heat process, the flux contained in the solder deposits on the electrodes 30 of the mounting board 29. When oil or organic matter is deposited on the electrode 30, the oil or organic matter must be removed before nickel hydroxide is removed. But,
There was a problem that the removal rate of the polymer by argon sputtering was slow and the removal time was long.

The present invention has been made in view of the above-described conventional problems, and does not corrode electrodes even when a mounted substrate is exposed to the air after processing.
It is another object of the present invention to provide a method and an apparatus for treating the surface of a mounting substrate which can be processed in a short time.

[0010]

According to the method of the present invention, a reactive gas is introduced into a reaction chamber while exhausting the reaction chamber, and high-frequency power is applied between a high-frequency electrode in the reaction chamber and a counter electrode opposed thereto. In the mounting substrate surface treatment method in which a plasma is generated by placing a mounting substrate on a high-frequency electrode, plasma treatment is performed by first introducing argon gas, and then introducing oxygen gas for a short time. To be processed.

As described above, by spattering the surface of the mounting substrate with argon gas, inorganic substances such as nickel hydroxide on the surface of the mounting substrate can be removed. By performing the treatment for a short time, the substrate is exposed to oxygen plasma, and Br reacts with oxygen radicals to form Br ₂ O, BrO _{2 and the} like, which are discharged together with the exhaust gas from the reaction chamber. Thus, even if the mounting substrate is exposed to the atmosphere, the electrodes on the mounting substrate surface are not corroded.

In addition, when an oxygen gas is first introduced and plasma treatment is performed, and then an argon gas is introduced and plasma treatment is performed, when oil and organic substances are deposited on the mounting substrate,
Oil and organic matter are converted to CO ₂ , CO, H ₂ by oxygen radicals.
It is decomposed into O and the like, and can be removed at a higher speed than the removal rate by argon sputtering. Thereafter, by removing with argon sputtering, the processing time can be shortened.

Further, when plasma treatment is performed by introducing an oxygen gas for a short time after the plasma treatment by introducing an argon gas, it is possible to remove Br which has been released by the argon sputtering and adhered again as described above. The electrodes are not corroded.

Also, the mounting substrate surface treatment apparatus of the present invention is
A reaction chamber having a vacuum exhaust port and a reaction gas introduction port, a high-frequency electrode disposed in the reaction chamber so as to mount the mounting substrate, a counter electrode disposed opposite to the high-frequency electrode and grounded; A high-frequency power supply for applying high-frequency power between the electrode and the counter electrode, and a gas supply means for selectively supplying an argon gas and an oxygen gas to a reaction gas inlet, and performing the surface treatment method. The effect can be obtained.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of a method and an apparatus for treating a surface of a mounting board according to the present invention will be described below with reference to FIGS.

In FIG. 1, reference numeral 1 denotes a reaction chamber, which is provided with a vacuum exhaust port 2 and a reaction gas inlet 3 and is grounded.
A high-frequency electrode 5 is provided in the reaction chamber 1 between the reaction chamber 1 and the reaction chamber 1 via an insulating ring 4 so that the mounting substrate 10 is placed thereon. In the reaction chamber 1, a high-frequency electrode 5 is provided.
And a grounded counter electrode 6 is provided. The high-frequency electrode 5 is configured to apply high-frequency power from a high-frequency power supply 7 through a matching tuner (not shown) and a high-frequency power supply unit. High frequency electrode 5
An O-ring (not shown) is interposed between the insulating ring 4 and the reaction chamber 1 to maintain a vacuum in the reaction chamber 1 and to supply cooling water so that the O-ring is not heated to 200 ° C. or more. A cooling groove 8 for flowing is provided.

Reference numeral 11 denotes gas supply means for supplying a reaction gas to the reaction gas inlet 3. The argon gas supply line 15 includes an argon gas source 12, a mass flow controller 13, and a switching valve 14, an oxygen gas source 16 and a mass flow controller. An oxygen gas supply line 19 comprising a switching valve 17 and a switching valve 18 and an on-off valve 20 are provided so as to selectively supply a predetermined flow rate of argon gas and oxygen gas.

Next, the surface treatment operation of the mounting substrate having the above configuration will be described with reference to FIGS. While introducing 50 sccm of argon gas from the reaction gas inlet 3,
While maintaining the degree of vacuum in the reaction chamber 1 at 30 Pa, high-frequency power of 200 W is applied to the high-frequency electrode 5 to generate plasma and perform processing for 20 seconds. Argon ions in the plasma are irradiated on the surface of the mounting substrate 10 exposed to the plasma, and nickel hydroxide and the like deposited on gold on the electrodes of the mounting substrate 10 through a heat process and the like are converted to argon ions. Irradiation removes the surface of the gold by sputtering, and the surface of the gold is cleaned.

At this time, since the substrate 10 is also sputtered at the same time, if the material of the substrate 10 is glass epoxy,
Br (bromine) contained in the substrate 10 is reattached.

Then, after the argon plasma treatment, the high-frequency electrode 5 was supplied with 200 W while maintaining the degree of vacuum in the reaction chamber 1 at 90 Pa while introducing 50 sccm of oxygen gas.
Is applied to generate plasma, and the mounting substrate 10 is exposed to oxygen plasma for 5 seconds. By exposure to oxygen plasma, Br reacts with oxygen radicals to form Br ₂ O, BrO _{2 and the} like. Since the reaction chamber 1 is evacuated, these substances are discharged together with the evacuation. Thus, even if the mounting substrate 10 is exposed to the atmosphere, the electrodes on the mounting substrate surface will not be corroded.

As described above, according to the present embodiment, after the mounting substrate 10 is subjected to argon plasma sputtering and then exposed to oxygen plasma for a short time, Br contained in the mounting substrate is mounted by the sputtering action of argon. Even if it is re-adhered on the surface electrode of the substrate 10, it reacts with oxygen radicals in the oxygen plasma to form Br ₂ O, BrO _2, etc., and can be easily exhausted together with evacuation. as a result,
Since HBr and HOBr are not formed even when the mounting substrate 10 is exposed to the atmosphere, the electrodes on the substrate do not corrode.

Next, a second embodiment of a method for treating the surface of a mounting substrate will be described with reference to FIGS. The configuration of the apparatus is the same as that of the first embodiment described with reference to FIG. 1, and thus the description thereof will be omitted, and the processing operation will be described.

First, oxygen gas is supplied from the gas inlet 3 for 50 seconds.
While introducing ccm, the degree of vacuum in the reaction chamber 1 was kept at 90 Pa to increase the reactivity (generally, the pressure was increased to increase the reactivity, and the pressure was decreased to increase the sputterability). In this state, high-frequency power of 200 W is applied to the high-frequency electrode 5 to generate plasma, and the mounting substrate 10 is exposed to oxygen plasma for 5 seconds. Oil and organic substances on the surface of the mounting substrate 10 are removed by this oxygen plasma treatment.

Next, 5 argon gas is supplied from the gas inlet 3.
While introducing 0 sccm, the degree of vacuum in the reaction chamber 1 is set to 30P.
In the state maintained at a, high-frequency power of 200 W is applied to the high-frequency electrode 5 to generate plasma and process for 5 seconds. Argon ions in the plasma are irradiated onto the surface of the mounting substrate 10 exposed to the argon plasma, and nickel hydroxide or the like deposited on gold on the electrodes of the mounting substrate 10 through a heat process or the like is irradiated with argon ions. Irradiation removes the surface of the gold by sputtering, and the surface of the gold is cleaned. as a result,
For example, the bonding strength when wire bonding is performed is improved.

In practice, the argon plasma treatment alone is used for 20 times.
When the bonding strength is compared by wire bonding between the mounting substrate 10 that has been processed for 5 seconds and the mounting substrate 10 that has been subjected to oxygen plasma processing for 5 seconds and then argon plasma processing for 5 seconds, the same strength is obtained. Was able to be shortened.

As described above, the oil and organic substances adhering to the surface of the mounting substrate 10 are first removed by oxygen plasma, and then the inorganic substances such as nickel hydroxide are removed by sputtering with argon plasma, thereby shortening the processing time. Can be planned.

Further, if necessary, 5 g of oxygen gas is then added.
While introducing 0 sccm, the degree of vacuum in the reaction chamber 1 was increased to 90P.
In the state maintained at a, high-frequency power of 200 W is applied to the high-frequency electrode 5 to generate plasma, and the mounting substrate 10 is exposed to oxygen plasma for 5 seconds. By exposure to oxygen plasma in this manner, Br reacts with oxygen radicals to form Br ₂ O, BrO _{2, and the} like, and these substances are discharged together with the exhaust gas. Thus, even if the mounting substrate 10 is exposed to the atmosphere, the electrodes on the mounting substrate surface will not be corroded.

In the first and second embodiments, the mounting substrate 10 is subjected to oxygen plasma treatment for 5 seconds. However, the amount of Br adhering to the electrode depends on the sputtering time by the argon plasma, so that the time is not particularly limited. However, short-time processing is also effective.

In the second embodiment, the first oxygen plasma treatment is performed for 5 seconds. However, the treatment time must be changed according to the amount of oil and organic substances deposited on the mounting board 10, and the treatment time is not particularly limited. .

Although the grounded counter electrode 6 is provided in the above embodiment, the grounded reaction chamber 1 may be provided in some cases.
The reaction chamber 1 is made to function as a counter electrode,
It may be.

[0031]

According to the method and apparatus for treating the surface of a mounting substrate according to the present invention, as described above, after the plasma treatment is performed by first introducing argon gas, the plasma treatment is performed by introducing oxygen gas for a short time. Inorganic substances such as nickel hydroxide on the surface of the mounting substrate can be removed by sputtering the surface of the mounting substrate with a gas, and then treated with oxygen gas for a short time to react the Br attached again by argon sputtering with oxygen radicals and gasify it. As a result, the electrodes on the surface of the mounting substrate are not corroded even when the mounting substrate is exposed to the air.

Further, when plasma treatment is performed by first introducing oxygen gas and then performing plasma treatment by introducing argon gas, when oil and organic substances are deposited on the mounting substrate,
Oils and organic substances are decomposed into gas by oxygen radicals, and can be removed at a higher speed than the removal rate by argon sputtering. Then, by removing inorganic substances by argon sputtering, the processing time can be shortened.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a mounting substrate surface treatment apparatus according to a first embodiment of the present invention.

FIG. 2 is a processing step diagram of the embodiment.

FIG. 3 is a process diagram of a method for treating a surface of a mounting board according to a second embodiment of the present invention.

FIG. 4 is a schematic configuration diagram of a conventional mounting substrate surface treatment apparatus.

FIG. 5 is a longitudinal sectional view schematically showing a configuration of a mounting board.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reaction chamber 2 Vacuum exhaust port 3 Reaction gas inlet 5 High frequency electrode 6 Counter electrode 7 High frequency power supply 11 Gas supply means

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hitoshi Nishida 1006 Kadoma, Kazuma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. F-term (reference) 5F004 AA14 BA04 DA23 DA26 DB00 5F044 EE13

Claims (4)

[Claims] 1. A reaction gas is introduced while exhausting a reaction chamber, a high-frequency power is applied between a high-frequency electrode in the reaction chamber and a counter electrode facing the reaction gas to generate plasma, and a mounting substrate is mounted on the high-frequency electrode. A mounting substrate surface treatment method for mounting and performing a plasma treatment, wherein plasma treatment is performed by first introducing an argon gas and then performing a plasma treatment by introducing an oxygen gas for a short time. 2. A reaction gas is introduced while evacuating the reaction chamber, and a high-frequency power is applied between a high-frequency electrode in the reaction chamber and a counter electrode facing the high-frequency electrode to generate plasma, and a mounting substrate is placed on the high-frequency electrode A mounting substrate surface treatment method for mounting and performing a plasma treatment, comprising first introducing an oxygen gas to perform a plasma treatment, and then introducing an argon gas to perform a plasma treatment. 3. The method according to claim 2, wherein the plasma treatment is performed by introducing an argon gas for a short time after the plasma treatment is performed by introducing an argon gas. 4. A reaction chamber having a vacuum exhaust port and a reaction gas introduction port, a high-frequency electrode disposed in the reaction chamber so as to mount a mounting substrate, and a high-frequency electrode opposed to the high-frequency electrode and grounded. A mounting substrate, comprising: a counter electrode; a high-frequency power source for applying high-frequency power between the high-frequency electrode and the counter electrode; and gas supply means for selectively supplying argon gas and oxygen gas to a reaction gas inlet. Surface treatment equipment.