Plasma process apparatus and plasma process method

A plasma process method using a plasma process apparatus comprising a reaction vessel having a space a pressure of which can be reduced, substrate holding means and a cathode electrode disposed in said reaction vessel, and a transmission line for supplying high-frequency power generated by a high-frequency power supply through a matching circuit to said cathode electrode, said plasma process apparatus generating a plasma between a substrate held by said substrate holding means and said cathode electrode to effect a plasma process on the substrate,

• 1) wherein an oscillation frequency of a wave oscillated from said high-frequency power supply comprises at least the range of 30 to 600 MHz,
• 2) wherein said matching circuit and said cathode electrode are connected through the transmission line and said high-frequency power is transmitted through said transmission line,
• 3) wherein said cathode electrode has an electrically conductive structure of a rod shape and wherein at a connection part between said cathode electrode and an inner conductor of said transmission line an external shape of a cross section of the cathode electrode is the same as an external shape of a cross section of the inner conductor, and
• 4) wherein at least the connection part between said cathode electrode and the inner conductor of said transmission line is covered by a dielectric member having the same external shape as an external shape of a transmission medium in the cross section of the transmission line, said plasma process method comprising:
• reducing the pressure in said reaction vessel and introducing a gas used for the plasma process thereinto;
• applying a high-frequency wave between said cathode and said substrate to generate a plasma;
• and
• effecting the plasma process on a surface of the substrate by said plasma.

A plasma process apparatus comprising a reaction vessel having a space a pressure of which can be reduced, substrate holding means and a cathode electrode disposed in said reaction vessel, and a transmission line for supplying high-frequency power generated by a high-frequency power supply through a matching circuit to said cathode electrode, said plasma process apparatus generating a plasma between a substrate held by said substrate holding means and said cathode electrode to effect a plasma process on the substrate,

• 1) wherein an oscillation frequency of wave oscillated from said high-frequency power supply comprises at least the range of 30 to 600 MHz,
• 2) wherein the matching circuit and the cathode electrode are connected to each other through the transmission line;
• the transmission line is a coaxial transmission line formed of a columnar or cylindrical inner conductor with an outer diameter A1, a cylindrical outer conductor with a bore diameter B1 and a cylindrical dielectric member with a dielectric constant .epsilon.1;
• and the high-frequency power is transmitted through the transmission line,
• 3) wherein the cathode electrode is a columnar or cylindrical, conductive structure with an outer diameter A2 and is covered with a cylindrical dielectric member with a dielectric constant .epsilon.2 and an outer diameter B2, and
• 4) wherein the dimensions and dielectric constants of the members which form the transmission fins and the cathode electrode portion satisfy the relation expressed by Equation (1) ##EQU6##