The present invention provides SEM systems, SEM calibration standards, and SEM calibration methods that improved accuracy in critical dimension measurements. The calibration standards have features formed with an amorphous material such as amorphous silicon. Amorphous materials lack the crystal grain structure of materials such as polysilicon and are capable of providing sharper edged features and higher accuracy patterns than grained materials. The amorphous material can be bound to a silicon wafer substrate through an intermediate layer of material, such as silicon dioxide. Where the intermediate layer is insulating material, as is silicon dioxide, the intermediate layer may be patterned with gaps to provide for electrical communication between the amorphous silicon and the silicon wafer. Charges imparted to the amorphous silicon during electron beam scanning may thereby drain to the silicon wafer rather than accumulating to a level where they would distort the electron beam.