A 100-kV, 100-A/cm2 Electron Optical System for the EB-X3 X-Ray Mask Writer
In order to increase the throughput of the EB-X3 variably shaped electron beam writing system, a method of increasing the current density with a zoom lens was introduced into the electron optical system. The electron optical characteristics were measured at current densities of 50 and 100 A/cm2 under various zoom-lens conditions, and the results show that this method can increase the current density to 100 A/cm2 without any change in the major electron optical characteristics. At this current density, the patterning resolution was estimated to be 55 nm, and no melting of the first shaping aperture and no microdischarges in the 100-kV electron gun were observed. This confirms that the current density of the EB-X3 can in fact be extended to 100 A/cm2 for the fabrication of X-ray masks with a minimum feature size of 100 nm and below.
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 µ 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.
Performance enhancements on IBM’s EL‐4 electron‐beam lithography system
IBM’s latest electron‐beam mask maker, EL‐4, is installed at IBM’s Advanced Mask Facility in Essex Junction, Vermont. The EL‐4 system is a 75 kV variable‐shaped‐beam lithography system designed to produce 1X or NX masks for 0.25 μm lithography ground rules, extendable to 0.13 μm. It is currently producing NIST‐style x‐ray membrane masks with pattern sizes up to 50×50 mm2. After a brief description of the EL‐4 tool and its operating features, the article describes the recently implemented new writing subsystem, provides an overview of the tool software structure, and presents measurement data from masks recently produced on the tool.