Electric lamp and discharge devices: systems – Discharge device load with fluent material supply to the... – Plasma generating
Reexamination Certificate
1999-11-30
2001-11-06
Wong, Don (Department: 2821)
Electric lamp and discharge devices: systems
Discharge device load with fluent material supply to the...
Plasma generating
C315S360000
Reexamination Certificate
active
06313583
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a plasma processing apparatus and method in which a plasma processing is performed for an object of processing such as a substrate.
A plasma processing apparatus is known as an apparatus for performing a processing for cleaning of a substrate surface on which electronic parts are to be mounted. In this plasma processing apparatus, a plasma discharge is generated in an evacuated vacuum chamber by applying a high-frequency voltage to a discharging electrode in the vacuum chamber after the introduction of a plasma generating gas into the vacuum chamber. A plasma processing for an object of processing placed on the discharging electrode is performed by the action of ions, electrons or the like generated by the plasma discharge.
In order to obtain an adequate processing effect by this plasma processing, it is necessary that a plasma processing condition such as the value of a high-frequency voltage applied to the discharging electrode should be set adequately in accordance with the object of processing. Hitherto, the setting of the plasma processing condition has been made on the basis of the result of a condition determining work performed for determining the optimum processing condition for each object of processing.
However, an effective electric power representing the action of the plasma discharge for plasma generation exerted on the object of processing differs depending upon the size, thickness and material of the object of processing. Therefore, in the case where a plasma processing is performed under the same condition, it is not possible to avoid the variations in quality of the plasma processing even in the case of similar objects of processing.
Also, at the time of operation of the plasma processing apparatus, removed substances attach to the inner wall of the vacuum chamber due to reverse sputtering so that a deposited layer is gradually formed on the inner wall of the vacuum chamber with the lapse of the operating time. This deposited layer causes a change in impedance of a plasma discharging circuit. Therefore, the effective electric power for the object of processing has a time dependent change even if a power supply output condition is kept constant. Accordingly, no adequate plasma processing condition is ensured resulting in that the variations in quality of the plasma processing are generated. Thus, the conventional plasma processing has a problem that owing to the difference between objects of processing and the time dependent change in internal state of the vacuum chamber, it is difficult to keep the adequate plasma processing condition.
SUMMARY OF THE INVENTION
Therefore, an object of the present invention is to provide a plasma processing apparatus and method in which an adequate plasma processing condition can be kept always.
According to a first aspect of the present invention, there is provided a plasma processing apparatus in which a plasma generating gas is introduced into an evacuated vacuum chamber and a high-frequency voltage is applied to a discharging electrode provided in the vacuum chamber to generate a plasma in the vacuum chamber, thereby performing a plasma processing for an object of processing placed on the discharging electrode, the apparatus comprising a high-frequency power supply unit for applying the high-frequency voltage to the discharging electrode, a matching unit for taking the matching in impedance between the high-frequency power supply unit and a discharging circuit which produces a plasma discharge, detection means for detecting a voltage and/or current of the discharging circuit by virtue of a resistor inserted in a circuit which connects the matching unit and the discharging electrode, and control means for controlling the high-frequency power supply unit on the basis of the result of detection by the detection means.
According to a second aspect of the present invention, there is provided a plasma processing apparatus in which a plasma generating gas is introduced into an evacuated vacuum chamber and a high-frequency voltage is applied to a discharging electrode provided in the vacuum chamber to generate a plasma in the vacuum chamber, thereby performing a plasma processing for an object of processing placed on the discharging electrode, the apparatus comprising a high-frequency power supply unit for applying the high-frequency voltage to the discharging electrode, a matching unit for taking the matching in impedance between the high-frequency power supply unit and a discharging circuit which produces a plasma discharge, detection means for detecting a voltage and/or current of the discharging circuit by virtue of a resistor inserted in a circuit which connects the matching unit and the discharging electrode, and judgement means for judging a time dependent change in internal state of the vacuum chamber through the comparison of the result of detection by the detection means with a preset reference value to give predetermined notice.
According to a third aspect of the present invention, there is provided a plasma processing method in which a plasma generating gas is introduced into a vacuum chamber after the evacuation thereof and a high-frequency voltage is applied by a high-frequency power supply unit to a discharging electrode provided in the vacuum chamber to generate a plasma in the vacuum chamber, thereby performing a plasma processing for an object of processing placed on the discharging electrode, the method comprising a step of detecting a voltage and/or current of a discharging circuit which produces a plasma discharge, the detection being made by virtue of a resistor inserted in a circuit connecting the discharging electrode and a matching unit which takes the matching in impedance between the high-frequency power supply unit and the discharging circuit, and a step of controlling the high-frequency power supply unit on the basis of the result of detection.
According to a fourth aspect of the present invention, there is provided a plasma processing method in which a plasma generating gas is introduced into a vacuum chamber after the evacuation thereof and a high-frequency voltage is applied by a high-frequency power supply unit to a discharging electrode provided in the vacuum chamber to generate a plasma in the vacuum chamber, thereby performing a plasma processing for an object of processing placed on the discharging electrode, the method comprising a step of detecting a voltage and/or current of a discharging circuit which produces a plasma discharge, the detection being made by virtue of a resistor inserted in a circuit connecting the discharging electrode and a matching unit which takes the matching in impedance between the high-frequency power supply unit and the discharging circuit, and a step of judging a time dependent change in internal state of the vacuum chamber through the comparison of the result of detection with a preset reference value to give predetermined notice.
With the apparatus and method according to the first and third aspects, it is possible to perform the setting of an adequate power supply output always by detecting the voltage and/or current of the discharging circuit by virtue of the resistor inserted in the circuit connecting the matching unit and the discharging electrode and controlling the high-frequency power supply unit on the basis of the result of detection.
With the apparatus and method according to the second and fourth aspects, it is possible to judge the time dependent change in internal state of the vacuum chamber by comparing there result of detection with the preset reference value.
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patent: 992491 (1997-04-01), None
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Arita Kiyoshi
Haji Hiroshi
Morisako Isam
Matsushita Electric - Industrial Co., Ltd.
Stevens Davis Miller & Mosher LLP
Tran Thuy Vinh
Wong Don
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