Ion source with particular grid assembly

An ion source with a grid assembly to be used in thin film deposition on a substrate, comprising:

• a discharge chamber for containing an ionizable gas and a plasma resulting from the ionized gas;
• and
• a grid assembly disposed at the discharge chamber, the grid assembly comprising a screen grid kept at anode potential and disposed near the plasma, 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 peripheral portion connected to a sidewall of the discharge chamber and a central portion defining a plurality of apertures, the apertures of the three grids being mutually aligned with each other to form extraction channels for focusing and accelerating the ions in the form of an ion beam;
• wherein
• the grids are stacked with each other and assembled into the grid assembly via a screw-nut engagement at peripheral portions thereof, the grids being spaced and electrically insulated from one another, and wherein the central portions of the grids 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.

A method for applying an ion source in thin film deposition by IAD process, comprising the following steps:

• a) providing a deposition chamber;
• b) disposing a discharge chamber in the deposition chamber, the discharge chamber being adapted for containing an ionizable gas and a plasma resulting from the ionized gas, the discharge chamber defining an open end for a plasma and a gas inlet for allowing passage of the ionizable gas thereinto;
• c) providing a gas source for supplying the ionizable gas into the discharge chamber via the gas inlet;
• d) disposing an actuator in the deposition chamber, the actuator being adapted for ionizing the ionizable gas in the discharge chamber and thus producing the plasma;
• e) disposing an ion beam extraction device at the open end of the discharge chamber, the ion beam extraction device comprising a screen grid kept at anode potential and disposed near the plasma, 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, the screen grid, the accelerator grid and the decelerator grid being assembled into the ion beam extraction device via a screw-nut engagement therebetween, the three grids being spaced and insulated from one another and defining a plurality of apertures mutually aligned with each other to form extraction channels for the ion beam, each grid having an inwardly curved configuration toward the interior of the discharge chamber, so as to extract a converged ion beam with a sequentially reduced cross-sectional area;
• and
• f) disposing a substrate in the deposition chamber for being bombarded by the ion beam to obtain the thin film.