Title:
MEASURING INSTRUMENT FOR SUPERPOSITION ACCURACY
Document Type and Number:
Japanese Patent JPS63169505
Kind Code:
A
Abstract:
PURPOSE:To accurately measure superposition accuracy by calculating the superposition of a series of sectional waveforms of a group of an odd number of marks with constant line width which are arranged in a specific direction at constant pitch from a coefficient of mutual correlation. CONSTITUTION:Picked-up images of mark groups A and B on a sample 1 are converted 10 photoelectrically and stored in a video memory 11. A pattern deciding device 12 generates graphs showing the features of the mark groups A and B from the memory 11 and a pattern generator 13 generates section signals (e) and (f) of the mark groups A and B with position information (o) on the graphs and a video signal (n) from the memory 111. Further, pattern reproducing devices 14 and 15 reproduce section patterns e' and f'. A mutual correlator 16 offsets data f' from the data e' and f' by a set offset value (i) and calculates the coefficient (g) of mutual correlation. The coefficient (g) is supplied to a peak detector 17, which calculates such a deviation quantity (h) that the coefficient (g) is maximum. The periods (j) and (k) of the data e' and f' are found by a period calculator 18 in surface element units. Arithmetic operation based on those values (i), (h), (j), and (k) is carried out to detect the quantities of deviation of the mark groups A and B by a deviation quantity detector 19.
Inventors:
KINOSHITA TAKESHI
Application Number:
JP130187A
Publication Date:
July 13, 1988
Filing Date:
January 06, 1987
Export Citation:
Assignee:
NEC CORP
International Classes:
H01L21/66; G01B11/00; G01N21/27; G01N21/47; G01N21/84; G01N21/88; H01L21/027; H01L21/30; H01L21/68; (IPC1-7): G01B11/00; G01N21/27; G01N21/47; G01N21/84; H01L21/30; H01L21/66; H01L21/68
Attorney, Agent or Firm:
Uchihara Shin