The present invention provides a method of ceramic shadow-mask in process flow, which replaces the conventional photomask and applies to the procedures of IC manufacturing to achieve the same efficiency as photomask. Using control registers to select an individual bit of a multi-bit counter, a timing interval pulse is provided for prompting signal generation that is otherwise subject to a minimum count requirement. The overcoat layer 215 has apertures 215a directly above the corresponding apertures 212a. Methods for milling a tube are also described.