Chemistry: electrical and wave energy – Apparatus – Coating – forming or etching by sputtering
Reexamination Certificate
1999-07-28
2002-07-09
McDonald, Rodney G. (Department: 1753)
Chemistry: electrical and wave energy
Apparatus
Coating, forming or etching by sputtering
C204S298030, C204S192130
Reexamination Certificate
active
06416638
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a power supply device for a sputtering apparatus for forming a thin film on an electronic component, semiconductor, optical disk, etc.
BACKGROUND ART
The technique for forming a thin film on a semiconductor, electronic component, decorated component, etc., by means of a sputtering apparatus using a sputtering source arranged with a magnet placed at a rear surface of a target has been extensively used. In such a sputtering apparatus, an inert gas, such as Ar, is introduced as a discharge gas in a vacuum chamber with a sputtering source placed therein and, by applying a negative voltage to the sputtering source, a magnetron discharge is generated, causing the ionization of the discharge gas introduced in the vacuum container, the acceleration of positive ions of ionized argon and the subsequent collision of these against the target surface of the sputtering source, so that the target surface is evaporated through the sputtering. The sputtering particles are deposited on a substrate and a thin film is formed which is made up of the target material. This is called a sputtering.
In the course of the sputtering, there is sometimes the case that the magnetron discharge is changed to an arc discharge. If, in this case, the magnetron discharge is changed to the arc discharge, it is not possible to effect such sputtering.
Therefore, such a reverse voltage pulse as to maintain the above-mentioned sputtering source somewhat briefly at a positive potential is applied immediately after the generation of the arc discharge, thus suppressing the generation of the arc discharge.
In this prior art case, the time interval in which this reverse voltage pulse was applied was 30 &mgr;s or more.
Incidentally, the time interval in which the reverse voltage pulse was applied was required to have a time interval of a given value because a problem arises such as to protect a switching element from being destroyed due to a power loss involved.
As set out above, even if a reverse voltage pulse is applied in a time interval of 30 &mgr;s or more, there sometimes occurs a subsequently immediate continuous arc discharge. There was a problem with a high probability of the occurrence of a continuous arc discharge.
Further, in the case where the reverse voltage pulse is applied, a positive voltage may be applied to the sputtering source and there also occurs on arc discharge in a reverse direction, for example, from a substrate, etc. When a continuous arc discharge has been produced due to a reverse arc discharge, there was a problem of causing damage to the substrate.
Disclosure of Invention
The present invention is achieved with the above-mentioned points in view and its object is to provide a power supply device for a sputtering apparatus which, in order to prevent the generation of a continuous arc discharge, sets a time interval of the application of a reverse voltage pulse to be within 1 to 10 &mgr;s in the case where the generation of the arc discharge is detected and can positively prevent the generation of a reverse arc discharge resulting from the reverse voltage pulse.
According to one embodiment of the present invention there is provided a power supply device for a sputtering apparatus introducing an inert gas into a grounded vacuum container, applying a negative voltage to a sputtering source located in the vacuum container and effecting sputtering, the power supply device being characterized by comprising a DC current power supply for applying a DC voltage to the sputtering source; reverse voltage generating means for applying a reverse voltage to the sputtering source so as to stop generation of an arc discharge in the sputtering, switching means for enabling the reverse voltage which is generated at the reverse voltage generating means to be applied to the sputtering source; arc discharge detecting means for detecting the generation of the arc discharge in the vacuum container; reverse voltage applying means for, when the generation of the arc discharge is detected by the arc discharge detecting means, turning the switching means ON for a set time and for enabling a reverse voltage generated from the voltage generating means to be applied to the sputtering source; and reverse voltage application control means for, when the generation of the arc discharge is detected by the arc discharge detecting means, applying the reverse voltage generated by the reverse voltage generating means to the sputtering source for a set time and, when generation of an arc discharge is again detected by the arc discharge detecting means after that application, applying the reverse voltage which is generated by the reverse voltage generating means to be applied to the sputtering source in a range of 1 to 10 &mgr;s.
Since the interval at which the reverse voltage pulse is applied is set to be below 1 to 10 &mgr;s, it is possible to extremely lower the generation probability of a continuous arc discharge.
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US 5,863,392, 01/1999, Drummmond et al. (withdrawn)
Fujii Takashi
Kawamata Yoshio
Kuriyama Noboru
Yatsu Yutaka
McDonald Rodney G.
Shibaura Mechatronics Corporation
Volpe and Koenig P.C.
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