Communications: electrical – Digital comparator systems
Patent
1979-12-26
1981-10-27
Boudreau, Leo H.
Communications: electrical
Digital comparator systems
307351, 3401463H, 364490, G06K 932
Patent
active
042976766
ABSTRACT:
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.
REFERENCES:
patent: 3159815 (1964-12-01), Groce
patent: 3225213 (1965-12-01), Hinrichs et al.
patent: 3415950 (1968-12-01), Bartz et al.
patent: 3599148 (1969-04-01), Stern
patent: 3599151 (1971-08-01), Harr
patent: 3869698 (1975-03-01), Trost et al.
patent: 3909594 (1975-09-01), Allais et al.
Hamamto Nobuo
Ichino Kazuo
Moriya Shigeru
Ozawa Kanji
Boudreau Leo H.
Hitachi , Ltd.
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