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.
EB-X3: New electron-beam x-ray mask writer
The EB-X3 is an electron-beam mask writer designed to pattern x-ray masks with minimum feature sizes of 100 nm and below with good beam placement accuracy. The target patterning resolution is 50 nm, and a beam acceleration voltage of 100 kV is used to achieve it. This resolution has already been demonstrated using the previous version of the writer, the EB-X2 (developed last year), which also employs an acceleration voltage of 100 kV. On the other hand, the target placement accuracy for the EB-X3 is less than 10 nm, which is more than three times smaller than that for the EB-X2. To improve the placement accuracy, the resolution of the laser measurement system was changed from λ/128 (=5 nm) to λ/1024 (=0.6 nm), and the address unit was set to 1 nm, which yields a reproducibility of mark detection of 4 nm (3σ) and a calibration accuracy for deflection distortion of 5 nm(|mean|+3σ). In addition, the laser measurement system monitors five axes (X, Y, yaw, and pitch [X,Y]) and the results are fed back to posit...
X‐ray mask distortion correction technology using pattern displacement simulator
A new method to correct x‐ray mask distortion was developed. This method uses the correction method of previous analysis of distortion and transformation of coordinates (PAT) and a simulator to calculate pattern displacement caused during backetching. The key advantages of using PAT with a simulator are that no extra time, substrates, or labor are required to fabricate send‐ahead masks. Using this correction method, it was confirmed that the 3σ value of the pattern placement error was reduced to below 76 nm. This indicated that PAT with a pattern displacement simulator was as useful for improving the pattern placement accuracy of x‐ray masks as PAT with send‐ahead masks. In addition, analysis of the remaining error made it clear that the correction error was mainly caused by the lack of e‐beam writing accuracy.