METHODS AND CONTROLLERS FOR CONTROLLING FOCUS OF ULTRAVIOLET LIGHT FROM A LITHOGRAPHIC IMAGING SYSTEM, AND APPARATUSES FOR FORMING AN INTEGRATED CIRCUIT EMPLOYING THE SAME

Methods and controllers for controlling focus of ultraviolet light produced by a lithographic imaging system, and apparatuses for forming an integrated circuit employing the same are provided. In an embodiment, a method includes providing a wafer having a resist film disposed thereon. The resist film is patterned through illumination of a lithography mask with ultraviolet light at an off-normal incidence angle with a first test pattern formed at a first pitch and a second test pattern formed at a second pitch different from the first pitch. Non-telecentricity induced shift of the first and second test patterns is measured to produce relative shift data using a measurement device. Focus of the ultraviolet light is adjusted based upon comparison of the relative shift data to a pre-determined correlation between the non-telecentricity induced shift of the first and second test patterns as a function of focus error.