There are conventionally-known apparatuses configured to produce a plasma used for conducting thin film formation process or etching process. Types of plasma apparatuses include an electric field-coupling plasma generation apparatus and an inductive-coupling plasma generation apparatus. The former apparatus utilizing electric field coupling applies a high-frequency electric field to the material gas contained in a chamber via electrodes for producing a plasma of the material gas. The other type of apparatus, utilizing inductive coupling, generates a high-frequency magnetic field by a high-frequency current flowing in an induction coil, and the resulting magnetic field in turn generates a high-frequency electric field in the chamber for producing a plasma.
Japanese Patent No. 4070152 discloses an inductive-coupling plasma generation apparatus for a toroidal plasma, while also disclosing methods of supplying energy needed to produce a plasma (i.e., ignite a plasma), such as utilizing ultraviolet irradiation to generate free electric charges, or applying high-voltage electric pulses directly to an inductive coil, or applying high-voltage electric pulses to electrodes provided in a chamber.
The above-noted methods using ultraviolet irradiation or using electrodes in the chamber, however, require designing a new chamber (or modifying the existing chamber) for implementing the particular method. Thus, these methods tend to result in a longer development period. In addition, these methods are not cost-effective because they need a special structure used only for a very short period of time, i.e., at the time of igniting a plasma. In contrast, the method of applying high-voltage pulses to the existing inductive coil does not require any addition of components. However, generating a high-frequency electric field requires high electric power. Unfavorably, a high current flowing through a high-frequency power source circuit to provide the required power may damage the conventional power source circuit.
USPTO Backgrounds
USPTO Backgrounds