An antenna conductor is cooled to stably generate plasma, and unexpected fluctuation in the electrostatic capacity of a variable capacitor connected to the antenna conductor is suppressed while cooling the variable capacitor. A plasma processing device which generates plasma in a vacuum container and processes a substrate by using the plasma is provided. The plasma processing device includes: an antenna conductor through which a high-frequency current is caused to flow to generate plasma, and a variable capacitor which is electrically connected to the antenna conductor. The antenna conductor has a flow path in which a cooling liquid flows. A dielectric of the variable capacitor is constituted of the cooling liquid flowing through the antenna conductor.

An antenna includes a first conductor plate and a second conductor plate, the second conductor plate being disposed in the first conductor plate so as to be apart from the first conductor plate with a distance between both plates; wherein the first conductor plate includes a first U-shaped portion, the first U-shaped portion being formed in a U-shape so as to include a first side portion, a second side portion opposed to the first side portion, and a first front portion connected between the first side portion and the second side portion; wherein the second conductor plate includes a second U-shaped portion, the second U-shaped portion being formed in a U-shape so as to include a third side portion, a fourth side portion opposed to the third side portion, and a second front portion connected between the third side portion and the fourth side portion.

An antenna includes a first conductor plate and a second conductor plate, the second conductor plate being disposed in the first conductor plate so as to be apart from the first conductor plate with a distance between both plates; wherein the first conductor plate includes a first U-shaped portion, the first U-shaped portion being formed in a U-shape so as to include a first side portion, a second side portion opposed to the first side portion, and a first front portion connected between the first side portion and the second side portion; wherein the second conductor plate includes a second U-shaped portion, the second U-shaped portion being formed in a U-shape so as to include a third side portion, a fourth side portion opposed to the third side portion, and a second front portion connected between the third side portion and the fourth side portion.

According to an embodiment, a multi-layer antenna structure comprises a printed circuit board including an IC for processing an RF signal, a feeding line connected to the IC, and a feeding pad connected to the feeding line, a conductive lower layer tightly contacting the printed circuit board and including a feeding hole in an area connected with the feeding pad and vertically open and a waveguide connected to the feeding hole and disposed on an upper surface thereof, and a conductive upper layer tightly contacting the conductive lower layer and including an antenna slot pattern in an area corresponding to the waveguide and vertically open. The waveguide may include a bottom surface positioned lower than an upper surface thereof, a side surface extending from each of two opposite ends of the bottom surface to the upper surface, and a protrusion protruding upward from a center portion of the bottom surface.

According to an embodiment, a multi-layer antenna structure comprises a printed circuit board including an IC for processing an RF signal, a feeding line connected to the IC, and a feeding pad connected to the feeding line, a conductive lower layer tightly contacting the printed circuit board and including a feeding hole in an area connected with the feeding pad and vertically open and a waveguide connected to the feeding hole and disposed on an upper surface thereof, and a conductive upper layer tightly contacting the conductive lower layer and including an antenna slot pattern in an area corresponding to the waveguide and vertically open. The waveguide may include a bottom surface positioned lower than an upper surface thereof, a side surface extending from each of two opposite ends of the bottom surface to the upper surface, and a protrusion protruding upward from a center portion of the bottom surface.

An electromagnetic wave radiator may include: a first metal layer; a plurality of metal side walls vertically protruding along an edge of the first metal layer; and a second metal layer suspended over the first metal layer. The second metal layer includes a plurality of ports radially extending from edges of the second metal layer and a plurality of slots penetrating the second metal layer in a radial direction.

An electromagnetic wave radiator may include: a first metal layer; a plurality of metal side walls vertically protruding along an edge of the first metal layer; and a second metal layer suspended over the first metal layer. The second metal layer includes a plurality of ports radially extending from edges of the second metal layer and a plurality of slots penetrating the second metal layer in a radial direction.

An electromagnetic wave radiator may include: a first metal layer; a plurality of metal side walls vertically protruding along an edge of the first metal layer; and a second metal layer suspended over the first metal layer. The second metal layer includes a plurality of ports radially extending from edges of the second metal layer and a plurality of slots penetrating the second metal layer in a radial direction.

An electromagnetic wave radiator may include: a first metal layer; a plurality of metal side walls vertically protruding along an edge of the first metal layer; and a second metal layer suspended over the first metal layer. The second metal layer includes a plurality of ports radially extending from edges of the second metal layer and a plurality of slots penetrating the second metal layer in a radial direction.

A geodesic antenna includes an outer cone. The geodesic antenna also includes an inner cone positioned partially within the outer cone and, together with the outer cone, defining an electromagnetic waveguide. The geodesic antenna further includes multiple driven elements configured to generate electromagnetic waves in a space between the outer and inner cones. In addition, the geodesic antenna includes a ground plane configured to reflect first electromagnetic waves of the generated electromagnetic waves back into the space between the outer and inner cones. The ground plane has a geometric design that prevents at least some second electromagnetic waves of the generated electromagnetic waves from being reflected from the ground plane and forming an interferometer pattern.