Cooling unit, processing chamber, part in the processing chamber, and cooling method

Abstract

A cooling unit for cooling a target object to a target temperature includes a decompression chamber thermally connected to the target object; a spraying part which sprays a liquid heat medium having a temperature equal to or lower than the target temperature to an inner surface of the decompression chamber; and an electric field generator which generates an electric field such that the heat medium sprayed from the spraying part is attached to the inner surface of the decompression chamber. The cooling unit further includes an exhaust part which evacuates the decompression chamber such that a pressure in the decompression chamber is equal to or lower than a saturated vapor pressure of the heat medium at the target temperature.

Description

FIELD OF THE INVENTION[0001]The present invention relates to a cooling unit and a cooling method for controlling a temperature of a target object to be cooled to and be maintained at a target temperature, and a processing chamber and a part in the processing chamber forming the cooling unit.BACKGROUND OF THE INVENTION[0002]In a semiconductor manufacturing apparatus, a plasma is frequently used to perform a processing such as an etching on a semiconductor wafer as a target object to be processed. However, the semiconductor wafer or the wall of a processing chamber may be unnecessarily heated by the plasma to a high temperature. Further, although there is a semiconductor manufacturing apparatus in which the semiconductor wafer needs to be processed at a high temperature, cooling is required after the processing for transferring and for another processing even in such apparatus. Accordingly, the semiconductor manufacturing apparatus includes a cooling unit for cooling the semiconductor...

AI Technical Summary

Benefits of technology

[0007]In view of the above, the present invention provides a cooling unit and cooling method capable reducing an amount of heat medium required for vacuum vaporization cooling, and cooling a target object with high efficiency, by using an electric field which attracts the heat medium sprayed into a decompression chamber thermally connected to the target object to an inner surface of the decompression chamber, and further provides a processing chamber and a part in the processing chamber forming the cooling unit.

[0023]During the phase transition, the heat medium absorbs the latent heat needed to be vaporized from the target object, thereby cooling the target object. Further, the heat medium can be effectively attached to the inner surface of the decompression chamber by a Coulomb force. Accordingly, it is possible to reduce an amount of the heat medium required for vacuum vaporization cooling compared to that needed in a configuration of simply spraying the heat medium. Further, since there is no need to spray an extra heat medium contrary to a case in a configuration of simply spraying the heat medium, it is possible to sufficiently reduce the pressure in the decompression chamber and effectively cool the target object. Further, since it is possible to reduce the amount of the heat medium delivered, it is possible to reduce energy consumption of a pump for delivering the heat medium.

[0025]In the present invention, the heat medium is electrically charged by friction between the nozzle of the spraying part and the heat medium. Atomized and charged particles of the misty heat medium repel each other by a Coulomb force. Accordingly, the heat medium is attracted and attached, in fine particles, to the inner surface of the decompression chamber. That is, in a case where the sprayed heat medium is not electrically charged, particles of the heat medium are aggregated by surface tension, and it is difficult for the heat medium to reach the inner surface of the decompression chamber. However, in a case where the heat medium is electrically charged, it is possible to prevent particles of the heat medium from being aggregated. Accordingly, it is possible to effectively attach the heat medium to the inner surface of the decompression chamber.

[0027]In the present invention, the decompression chamber is formed in the target object. Accordingly, it is possible to effectively cool the target object. Further, it is possible to reduce the size of the cooling unit.

[0028]In the present invention, the decompression chamber is provided outside the target object and is thermally connected to the target object by contact between the decompression chamber and the target object. Accordingly, it is possible to cool a target object in which the decompression chamber cannot be formed.

Problems solved by technology

However, the semiconductor wafer or the wall of a processing chamber may be unnecessarily heated by the plasma to a high temperature.

However, in cooling through the forced convection heat transfer method, since there are certain limitations on the heat transfer characteristics of the flow path, it is difficult to uniformly cool the semiconductor wafer or the like, and responsiveness to temperature control is poor.

However, since the heat transfer characteristics of the flow path is inversely related to the pressure loss, if the heat transfer characteristics of the flow path are increased, the pressure loss in the flow path becomes large, thereby increasing energy consumption of a pump for delivering the heat medium.

On the other hand, if the pressure loss is reduced in order to promote energy saving, a difference between a temperature at the inlet and that at the outlet of the heat medium becomes large, and the heat transfer characteristics of the flow path are degraded, thereby making it difficult to uniformly cool the semiconductor wafer.

However, from results of experiments, in a configuration in which the heat medium is simply sprayed to the inner surface of the decompression chamber at a low pressure, since there is no component for actively attracting the heat medium to the inner surface of the decompression chamber, the heat medium is expected to be randomly attached to the inner surface of the decompression chamber.

Accordingly, it is difficult for the liquid heat medium to be attached to the inner surface.

Therefore, it causes a new problem that it is required to supply into the decompression chamber a larger amount of heat medium than that of heat medium needed theoretically.

Further, if the amount of heat medium is increased, although the liquid heat medium may be attached to the inner surface of the decompression chamber, the heat medium supplied into the decompression chamber may not be sufficiently evacuated.

In this case, the heat medium attached to the inner surface of the decompression chamber is less likely to undergo a phase change, thereby causing a problem that it is difficult to effectively cool the mounting table.

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