A 100 kV electron gun for the X-ray mask writer, EB-X2

A 100-kV thermal-emission electron gun was developed for the X-ray mask writer EB-X2, which employs a variable-shaped electron beam with a beam edge resolution of 20 nm. The optimized design of the EB-X2 electron optical system requires that the electron gun has crossover diameters of 50 mu m and an optical length of less than 100 mm. So the crossover diameters of the gun were accurately calculated with an electron ray tracing program, and a gun with the required crossover diameters and optical length was designed. The gun was constructed, and the crossover diameters were measured. The measured values agree well with the calculated ones, and this confirms that the gun is suitable for use in the EB-X2 electron optical system.