text: In manufacturing and inspection processes of functional device products, such as a semiconductor device and a thin film magnetic head, that are manufactured by micro processing of their surfaces, the scanning electron microscope is widely used for measurement (hereinafter called “length measurement”) and appearance inspection of a pattern that is processed. The scanning electron microscope is an apparatus for performing the measurement by scanning a beam having an arrival energy of a few hundreds electron volts on a pattern that is a measurement object. However, for example, a photoresist (ArF resist) responsive to an argon fluoride excimer laser beam decreases (shrinks) in volume by irradiation of an electron beam although it is suitable for formation of a minute circuit pattern. Therefore, it is difficult for the scanning electron microscope to measure exact dimensions before the volume decrease.
  Against such a problem, the patent literatures 1, 2 propose a technique of estimating a dimension value before the volume decrease by plotting a relationship between measurement times and the amount of volume decrease and fitting a curve representing the relationship with an approximate function. That is, estimating the dimensions before volume decrease using extrapolation is proposed.
  On the other hand, responding to a request of further minute fabrication of the semiconductor device, a pattern formation method called self-aligned double patterning (SADP) has become adopted. The SADP is a technology of creating patterns arranged with a very narrow pitch equal to or less than an exposure limit that the conventional aligner can reach. Subjecting the pattern formed by such a pattern formation method to a measurement object of the SEM is disclosed, for example, in Patent Literature 3.