Shinichi Hamaguchi

Multicolumn cell: Evaluation of the proof of concept system

The beam performance of the electron optics proof of concept (POC) multicolumn-cell (MCC) system has been evaluated. The two beams at the near center of a 4×4 layout with 25 mm pitch show good uniformity and low interference. The MCC system is imaged with a variable-shaped beam and character projection electron optical system having a vector scan beam deflection and a “write-on-the-fly” stage motion control. Cost performance analysis gives the most effective number of column cells in the MCC system.

Development of electromagnetic lenses for multielectron beam lithography system

High-throughput electron-beam (EB) lithography systems require high current. However, beam blur increases because of the individual Coulomb interaction among the electron beams. Isolating the electron beam into 4–16 perfectly independent beamlets is effective. As for the electromagnetic lens, many openings in the parallel flat plates can form the compound eye lens. This lens is called the lotus root lens (LRL). Simulations and experiments with the LRL were carried out. In the case of LRL of 4×4 openings with a 22 mm pitch, the uniformity of magnetic field along the axis was within 0.2%. The basic lens function between two openings separated by 44 mm in the LRL with 21 openings in the conventional column qualitatively evaluated. The LRL should be a potential platform for a multicolumn cell system that provides a multibeam direct-writing system that utilizes variable-shaped beam or character projection as unit-column optics.

Next generation electron beam lithography system F7000 for wide range applications

For multi-purpose applications such as advanced LSIs, photonics, MEMS, and other nano- fabrications, it is important for electron beam (EB) writers that handle the various substrates with their own single mechanical platform. We have been developing the adjusting pallet function both 200mm and 300mm bases to satisfy this requirement. By analyzing actual examples of adjusting pallets we proved their effectiveness to their applications. The combination of adjusting pallet function, 1Xnm resolution column and character projection technologies will enable the next generation EB writer “F7000” to fit from Fab to Lab applications.

High‐precision reticle making by electron‐beam lithography

We have developed an electron‐beam (e‐beam) lithography system named ‘‘NOWEL’’ which utilizes very accurate pattern writing method and high‐speed data processing. Accordingly NOWEL makes it possible to manufacture reticles for 16‐Mbit dynamic random access memories (DRAM’s) or more densely integrated very large scale integrated circuits (VLSI’s). The NOWEL system has three key features: (1) Vertical landing deflection system. This consists of three yokes in series and one short‐working‐distance lens (M=0.86). The landing angle at the corner of the 5‐mm2 main field is <0.0025 rad. Therefore the butting error arising from a 10‐μ height variation of the substrate is <0.05 μ. Deflection aberration is about 0.2 μ. (2) Double exposure method called ‘‘A/B mode.’’ We adopted a variable shaped beam. The first exposure is made by serial writing with constant‐size rectangular spots, and the second one is made on the previously exposed area by shifting the beam position and reshaping the beam spots. One‐half dosage i...