Pattern critical dimension measurement equipment and method for measuring pattern critical dimension

A pattern critical dimension measurement equipment comprising:

• an electron source configured to generate a primary electron beam;
• a deflector configured to deflect the primary electron beam emitted from the electron source;
• a focusing lens configured to focus the primary electron beam deflected by the deflector;
• a decelerator configured to decelerate the primary electron beam that irradiates a sample;
• a reflector located between the electron source and the focusing lens, the reflector being impinged upon by electrons generated from the sample upon irradiation of the sample with the primary electron beam;
• a first detector configured to detect electrons generated by the reflector;
• a first electrode located between the reflector and the first detector;
• a second electrode located on a side opposite to the first electrode with an optical axis of the primary electron beam interposed therebetween;
• and
• a controller configured to control levels of respective voltages applied to the first electrode and the second electrode, thereby controlling a detection rate of electrons generated by the reflector.

A method for measuring a critical dimension of a pattern formed on a sample using a pattern critical dimension measurement equipment, wherein the pattern critical dimension measurement equipment includes an electron source configured to generate a primary electron beam, a deflector configured to deflect the primary electron beam emitted from the electron source, a focusing lens configured to focus the primary electron beam deflected by the deflector, a decelerator configured to decelerate the primary electron beam that irradiates the sample, a first detector located between the electron source and the focusing lens, the first detector being configured to detect electrons at part of azimuths of electrons generated from the sample upon irradiation of the sample with the primary electron beam, a second detector located between the electron source and the first detector, the second detector being configured to detect electrons at substantially all azimuths of the electrons generated from the sample, and an image processor configured to execute a process of measuring a dimension of the pattern, the method comprising the following processes performed by the image processor:

• a process of determining brightness of edges of a pattern formed on the sample on the basis of a first image obtained with the first detector;
• a process of discriminating a projection and a recess of the pattern on the basis of a change in brightness level between adjacent edges;
• and
• a process of measuring a size of the projection or the recess from a second image obtained with the second detector.