Patent ID: 7405415

Claim:
An ion source to be used in optical thin film deposition by IAD process, comprising: a discharge chamber for containing an ionizable gas and a plasma resulting from the ionized gas; a gas source for supplying the ionizable gas; an actuator for generating a high-frequency electromagnetic alternating field to ionize the ionizable gas and thus produce a plasma in the discharge chamber; a grid assembly for extracting and accelerating the ions in the form of an ion beam, the grid assembly comprising a screen grid kept at anode potential and disposed near the plasma in the discharge chamber, an accelerator grid kept at cathode potential and spaced from the screen grid, and a decelerator grid being equal to the ground and disposed beyond the accelerator grid, each grid having a curved portion with a plurality of apertures defined therethrough, the apertures of the three grids being aligned with each other to form extraction channels for the ion beam; wherein the screen grid, the accelerator grid and the decelerator grid are assembled into the grid assembly via a screw-nut engagement therebetween, the three grids being spaced and insulated from one another, and wherein, when disposing the grid assembly at the discharge chamber, the curved portions of the three grids of the grid assembly are arranged in an inwardly curved manner toward the interior of the discharge chamber, and thus the ion beam is extracted from the grid assembly in a converged manner to have a sequentially reduced cross-sectional area; and an outer shell surrounding the discharge chamber and the actuator.