Cooling block forming electrode

Abstract

The present invention is a cooling block that forms an electrode for generating a plasma for use in a plasma process, and includes a channel for a cooling liquid, the cooling block comprising: a first base material and a second base material respectively made of aluminum, at least one of the first and second base materials having a recess for forming a channel for a cooling liquid; and a diffusion bonding layer, in which zinc is diffused in aluminum, and an anti-corrosion layer of a zinc oxide film, the layers being formed by interposing zinc between the first and second base materials, and by bonding the first and second base materials with zinc interposed therebetween in a heating atmosphere containing oxygen.

Description

FIELD OF THE INVENTION [0001] The present invention relates to a cooling block forming an electrode for generating a plasma for use in a plasma process, and to a plasma processing apparatus using the cooling block. BACKGROUND ART [0002] In a process for manufacturing semiconductor devices or the like, a plasma process using a plasma is frequently performed. As shown in FIG. 9, a plasma processing apparatus for the plasma process includes, for example, a process vessel 10 of a vacuum chamber, and a stage 11 disposed in the process vessel 10 for supporting thereon a semiconductor wafer (hereafter referred to as “wafer”) as a substrate. The stage 11 also serves as a lower electrode. A showerhead 12 having a number of gas supply holes 12a is arranged above the stage 11. An upper electrode 13 is disposed on a lower surface of the showerhead 12. The upper electrode 13 is formed of an electrode plate 13a and a cooling block 13b. [0003] A radio-frequency for generating plasma is applied bet...

AI Technical Summary

Benefits of technology

[0014] According to the present invention, since both the first and second base materials are made of aluminum, any function required for an electrode can be fully satisfied. On the other hand, by interposing zinc between the first and second base materials to form a diffusion bonding layer of zinc to aluminum and an anti-corrosion layer of a zinc oxide film, it is easy to form the anti-corrosion layer on an inner peripheral surface of the channel through which a cooling liquid flows. Thus, it is possible to eliminate the above-described difficulties which may arise when the surface treatment is performed before brazing, and the difficulties which may arise when the surface treatment is performed after brazing. Further, the anti-corrosion layer of the zinc oxide film can be easily formed all over the channel even if it is complicated, and there is no possibility that the film is cracked. Furthermore, since bonding of the base materials and forming of the anti-corrosion layer can be carried out at the same time, the manufacturing process can be significantly simplified.

[0015] The anti-corrosion layer (zinc oxide film) serves as a sacrifice for a corrosive action of the cooling liquid to protect the aluminum base material against corrosion. Thus, the service life of the cooling block can be elongated. Since the frequency for changing the cooling block can be decreased, a maintenance operation of the cooling block can be simplified. Besides, since the anti-corrosion layer (zinc oxide film) is substantially identical to the base material (aluminum) in electric conductivity and thermal conductivity, the anti-corrosion layer does not interfere with an electric property and thermal property which ought to be provided by the cooling block forming an electrode.

[0020] According to the present invention, it is easy to form the channel for a cooling liquid out of stainless (SUS). The stainless channel is resistive to a corrosion by a cooing liquid, and does not interfere with an electric property and thermal property required for an electrode.

Problems solved by technology

However, when aluminum is used, since an aluminum solid surface is exposed to the cooling liquid channel 14 which is in contact with a cooling liquid, there is a possibility that an inner peripheral surface of the channel 14 is corroded by the cooling liquid circulating therethrough.

The corrosion of the inner peripheral surface of the channel 14 may then result in a blockage of the cooling liquid in the channel 14.

However, in joining the metal plates whose surfaces have been subjected to an alumite coating process before brazing, there is concern that an alumite coating film is cracked if the alumite coating film cannot resist a brazing temperature.

The cracked alumite coating film cannot fully achieve an anti-corrosion function.

However, also in this method, since it is necessary to pour the resin into the channel 14, the complicated structure of the channel 14 may inhibit the pouring of the resin.

In addition, it is uncertain whether such cooling block 13b provides a sufficient thermal conductivity.

However, it is significantly difficult to intricately bend a pipe.

Further, the pipe will not withstand a brazing temperature (about 600° C.) at a brazing step.

Thus, this method cannot be adopted.

However, it is often the case that the method is obliged to be abandoned, in terms of costs and spaces.

However, there is no suggestion for a suitable structure and manufacturing method of a cooling block which forms an electrode for generating plasma for use in a plasma process.

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