US6429443(Applied Materials, Inc; Background)

"Lithography systems are used for creating patterns, such as features（形状、特徴） of an electronic circuit, on a semiconductor substrate. In one type of suggested electron beam lithography system, a light beam from a light source is demagnified（縮小）and focused on a photocathode, which then converts the light beam into an electron beam (see, for example, U.S. Pat. No. 4,820,927 to Langner et al.). By modulating the light source and by scanning（スキャン）the electron beam using an electron optics（単数）, a desired pattern can be written（描画）on a mask blank (for later photolithography) or directly on a semiconductor substrate (direct-write lithography). In this disclosure, the term "writing plane" includes semiconductor substrates, lithography mask blanks, and like（同様の）workpieces.

A multiple beam electron beam lithography system ("multi-beam system") works（動作）similarly as described above except that multiple（複数の）light sources are employed (see, for example, U.S. Pat. No. 5,039,862 to Smith et al. and U.S. Pat. No. 5,684,360 to Baum et al.). The light sources are typically arranged in an array（アレイ状に）and individually modulated to create the pattern. The placement（配置）of the light sources relative to one another in the array is critical in a multi-beam system because a light source placement error directly translates to（反映される、つながる）an electron beam writing error. In the fabrication（作製）of 0.1 micrometer devices, for example, electron beam writing errors less than 10 nm are required. Further, the rate at which the light sources are modulated to create the pattern affects the throughput of the multi-beam system. It is desirable to increase the modulation rate of the light sources to achieve a corresponding increase in the number of writing planes that can be processed.

The photocathode and electron optics of a multi-beam system are typically contained in an evacuated（減圧、排気、真空）electron beam column. It is desirable to（＊望まれ、必要）shorten the length of the column to reduce interaction between electrons ("electron-electron interaction") in an electron beam. Electron-electron interaction blurs the electron beam, thereby degrading（悪化、低下）the resolution of the pattern written on the writing plane. It is also desirable to shorten the length of the column to simplify its design.(US6429443)