Abstract: An inductively coupled plasma generator having a lower aspect ratio reaction gas, comprising a chamber having a gas inlet through which a reaction gas is supplied, a vacuum pump for maintaining the inside of the chamber vacuum and a gas outlet for exhausting the reaction gas after completion of the reaction, a chuck for mounting a target material to be processed inside the chamber, and an antenna to which high-frequency power is applied, the antenna provided at the upper and lateral portions of the chamber, wherein the antenna has parallel antenna elements in which a discharge of a high frequency can be allowed and impedance is low to ensure a low electron temperature, the antenna is disposed such that a powered end of each of the antenna elements and a ground end of each of the antenna elements opposite to the powered end are symmetrical in view of the center of an imaginary circle formed by the antenna to establish rotation symmetry of plasma density profiles, the antenna elements are twisted in a helical m

Abstract: An antenna structure for an inductively coupled plasma generator suitable for processing large-diameter wafers or large, flat-panel display devices by making a plasma density distribution uniform and symmetrical with respect to a rotating direction inside a circular or rectangular chamber in which a wafer is processed. In the antenna structure having a powered end to which RF power is applied and a ground end connected to the ground, at least two loop antenna elements are disposed electrically in parallel with each other, the powered ends and ground ends of the respective antennas are disposed symmetrically with respect to the center of the antennas, and the antennas crossing each other such that the powered ends and ground ends thereof are disposed at a part far from a chamber and central parts thereof are disposed at a part close to the chamber.