Abstract: A printed wiring device includes an insulation layer, a base layer, i.e. grounding layer or power supply layer, disposed on the insulation layer, and a signal line disposed on the insulation layer at the opposite side of the base layer. A plurality of holes is formed in the base layer opposite to the signal line, so that an average capacitance value between the signal line and the base layer is decreased. Thus, even if the insulation layer is thinned without narrowing the width of the signal line, characteristic impedance of the signal line can be controlled at a desired value.

Abstract: The arrangement comprises an antenna coil disposed close to a cover 4 for a Plasma forming chamber 3 and having one side surface opposed to the chamber space of said plasma forming chamber, a magnetically permeable core 7 of ferromagnetic material whose lower surface opposed to said chamber space is formed with a groove 7a in which the conductor of said antenna coil is received, and a susceptor 16 disposed in the lower region of said chamber space for placing an object to be treated 19 thereon.

Abstract: The invention provides an impedance matching and power control system not resorting to mechanical control for a device for high frequency plasma treatment. An impedance matching unit 14 inserted in the terminal end of a power feed line 3 extending from a high frequency power oscillator 1 to a plasma chamber 2 comprises phase detecting means 17, a load-associated detector 19 having the function of detecting voltage, current, and phase angle, and an arithmetic and output section 21, whereby the impedance matching unit delivers a frequency control signal corresponding to the detected phase and a power signal representing the consumed power of the plasma chamber as calculated from the voltage, current and phase angle.