Method for acquiring settling time

A method for acquiring a settling time, comprising:

• writing a plurality of first patterns, arranged in positions apart from each other by a deflection movement amount, by deflecting a charged particle beam onto a target object by a deflector configured to deflect the charged particle beam based on a deflection signal from a DAC (digital/analog converter) amplifier in which a settling time of the DAC amplifier is set to a first time to be a sufficient settling time for the deflection movement amount to evaluate the settling time of the DAC amplifier;
• writing a plurality of second patterns, in a manner where each corresponding second pattern of the plurality of second patterns corresponding to each of the plurality of first patterns is in a position adjacent to a corresponding one of the plurality of first patterns, by deflecting a charged particle beam onto the target object respectively by the deflector for each second time of a plurality of different second times set as variable while setting the settling time of the DAC amplifier as variable using the plurality of different second times containing the sufficient settling time for the deflection movement amount;
• measuring a width dimension of each of a plurality of combined patterns after adjacent ones of the plurality of first patterns and the plurality of second patterns are combined for the each second time set as variable;
• and
• acquiring the settling time of the DAC amplifier needed for deflection by the deflection movement amount, using the width dimension of each of the plurality of the combined patterns measured.