Plasma processing apparatus
A plasma processing apparatus includes an antenna configured to generate plasma of a processing gas in a chamber. The antenna includes: an inner coil provided around the gas supply unit to surround a gas supply unit; and an outer coil provided around the gas supply unit and the inner coil to surround them. The outer coil is configured such that both ends of a wire forming the outer coil are opened; power is supplied from a power supply unit to a central point of the wire; the vicinity of the central point of the wire is grounded; and the outer coil resonates at a wavelength that is a half of a wavelength of the high frequency power. The inner coil is configured such that both ends of a wire forming the inner coil are connected through a capacitor and the inner coil is inductively coupled with the inner coil.
1. A plasma processing apparatus comprising:
a chamber configured to accommodate a target substrate;
a dielectric window forming an upper portion of the chamber;
a gas supplier configured to supply a processing gas from an upper portion of the chamber into the chamber;
an antenna provided above the chamber to surround the gas supplier and configured to generate plasma of the processing gas in the chamber by supplying a high frequency power into the chamber; and
a power supplier configured to supply a high frequency power to the antenna,
wherein the antenna includes:
an inner coil provided around the gas supplier to surround the gas supplier; and
an outer coil formed from a wire having first and second ends provided at an outer side of the inner coil such that the outer coil is provided around the gas supplier and the inner coil to surround the gas supplier and the inner coil, the first end provided closer to the inner coil than the second end, the outer coil having a first radius, from a central axis of the gas supplier to the first end, that is larger than a second radius from the central axis to the inner coil,
wherein the outer coil is configured such that the first and second ends of the wire forming the outer coil are opened, power is supplied from the power supplier to a central point along the wire, the wire is grounded near the central point and the outer coil resonates at a wavelength that is a half of a wavelength of the high frequency power supplied from the power supplier, and
the inner coil is configured such that both ends of a wire forming the inner coil are connected through a capacitor and the inner coil is inductively coupled with the outer coil.
2. The plasma processing apparatus of claim 1 , wherein the outer coil is wound two or more turns in a substantially circular spiral shape,
the inner coil is formed in a substantially circular ring shape, and
the outer coil and the inner coil are arranged such that an outer shape of the outer coil and an outer shape of the inner coil form concentric circles.
3. The plasma processing apparatus of claim 2 , wherein the gas supplier has a substantially cylindrical shape, and the outer coil and the inner coil are arranged such that a center of the outer shape of the outer coil and a center of the outer shape of the inner coil are positioned on the central axis of the gas supplier.
4. The plasma processing apparatus of claim 1 , wherein the outer coil and the inner coil are arranged inside the dielectric window or above the dielectric window, and
a distance between a plane including the outer coil and a lower surface of the dielectric window is different from a distance between a plane including the inner coil and the lower surface of the dielectric window.
5. The plasma processing apparatus of claim 4 , wherein
the distance between the plane including the inner coil and the lower surface of the dielectric window is shorter than the distance between the plane including the outer coil and the lower surface of the dielectric window.
6. The plasma processing apparatus of claim 1 , wherein the power supplier allows a frequency of the high frequency power supplied to the antenna to be variable.
7. The plasma processing apparatus of claim 1 , wherein the capacitor provided at the inner coil is a variable capacitance capacitor.
8. The plasma processing apparatus of claim 1 , wherein a flow path through which the processing gas supplied to the chamber flows is formed in the gas supplier, and
a pressure in the flow path is higher than a pressure in the chamber.
9. The plasma processing apparatus of claim 1 , wherein the gas supplier includes:
a protruding part that is a lower part of the gas supplier and protrudes into the chamber from the lower surface of the dielectric window;
a first injection port provided at the protruding part and configured to inject the processing gas in a downward direction, and
a second injection port provided at the protruding part and configured to inject the processing gas in a horizontal direction or in an obliquely downward direction.
10. The plasma processing apparatus of claim 9 , wherein a conductive shielding member is provided at the gas supplier to surround a space through which the processing gas passes.
11. The plasma processing apparatus of claim 10 , wherein a lower end of the shielding member is positioned below the lower surface of the dielectric window.
12. The plasma processing apparatus of claim 10 , wherein the shielding member is formed in a plate shape.
13. The plasma processing apparatus of claim 10 , wherein the shielding member is a metal film formed on an outer wall of the gas supplier or a sidewall of a space in the gas supplier through which the processing gas flows.
14. The plasma processing apparatus of claim 10 , wherein the shielding member is formed in a rod shape.
15. The plasma processing apparatus of claim 9 , wherein at least a part of the space in the gas supplier through which the processing gas flows is bent to prevent formation of a linear path extending from the first injection port and the second injection port to an upper end of the gas supplier.