Hitachi, Ltd.

Nobuo Hamamto

Kazuo Ichino

Shigeru Moriya

Kanji Ozawa

In electron-beam lithography, and similar operations, to achieve good drawing accuracy on a sample, it is necessary to detect the position of a mark on the sample with high accuracy. To accomplish this, a mark signal amplifier is provided including a first circuit for taking maximum and minimum values out of a mark signal detected by causing an electron beam to scan a mark area provided on a sample. A second circuit determines a peak-to-peak value of an amplitude of the detected mark signal in accordance with the maximum and minimum values, and a third circuit produces an output signal of a constant amplitude level as an input to a binary-coding circuit in accordance with the peak-to-peak value. The output signal of the third circuit remains constant in spite of fluctuations of the detected mark signal, so that a higher accuracy is obtained in detecting the mark for positioning. An alternative arrangement adds the maximum and minimum values, and establishes a mean value of the maximum and minimum values from the resultant sum.

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Tokyo, Japan

Nobuo Hamamto