Provided are an exposure system and methods of performing exposing and patterning processes using the same. The exposure system may include a data processing part that forms an exposure layout; and an exposure part that irradiates an electron beam at a photoresist layer according to the exposure layout. The data processing part is constructed and arranged to generate a control parameter for driving the exposure part without a pattern position error and a beam drift error and to prevent a discrepancy between the exposure layout and a mask layout to be formed in the photoresist layer. The exposure system further includes a controlling part that controls the exposure part according to the control parameter.