Abstract: A method for performing a lithographic process over a semiconductor wafer is provided. The method includes coating a photoresist layer over a material layer which is formed on the semiconductor wafer in a track apparatus. The method further includes transferring the semiconductor wafer from the track apparatus to an exposure apparatus. The method also includes measuring a height of the photoresist layer before the removal of the semiconductor wafer from the track apparatus. In addition, the method includes measuring height of the material layer in the exposure apparatus. The method also includes determining a focal length for exposing the semiconductor wafer according to the height of the photoresist layer and the height of the material layer.