Methods for measuring mean-to-target (mtt) based on pattern area measurements and methods of correcting photomasks using the same

Abstract

Methods of measuring a mean-to-target (MTT) based on pattern area measurements are provided including providing a design pattern. A plurality of design pattern measurements are measured for calculating an area of the design pattern based on a shape of the design pattern. A series of calculation measurements are calculated by continuously substituting a same variation into the design pattern measurements, and calculating a series of calculation areas corresponding respectively to the calculation measurements to generate a database including the calculation measurements and the calculation areas. An actual pattern is formed using the design pattern and an area of the actual pattern is measured. A calculation area corresponding to the area of the actual pattern is selected from the database and calculation measurements corresponding to the calculation area are selected. A difference between the design pattern measurements and the calculation measurements is calculated and the difference is set as an MTT. Related methods of correcting a photomask are also provided herein.