×

Method and apparatus for the alignment of a substrate

  • US 5,493,403 A
  • Filed: 02/15/1995
  • Issued: 02/20/1996
  • Est. Priority Date: 07/05/1990
  • Status: Expired due to Term
First Claim
Patent Images

1. A method of aligning a substrate wherein an alignment mark formed on the substrate is irradiated with light and the position of the substrate is determined by detecting the position of the alignment mark with respect to a predetermined direction on the basis of light information from the alignment mark, said method comprising:

  • a process for obtaining a photoelectric signal having a waveform with a pair of extremal values corresponding to a pair of mark edge portions which define the width in said predetermined direction of said alignment mark, said photoelectric signal being obtained by detecting said light information from said alignment mark photoelectrically and said photoelectric signal changing its intensity in time-series with respect to said predetermined direction;

    a first determination process for determining the position of said alignment mark on the basis of a pair of slope portions existing inside said pair of extremal values of said photoelectric signal waveform;

    a second determination process for determining the position of said alignment mark on the basis of a pair of slope portions existing outside said pair of extremal values of said photoelectric signal waveform;

    a third determination process for determining the position of said alignment mark on the basis of both a pair of slope portions existing inside said pair of extremal values of said photoelectric signal waveform and a pair of slope portions existing outside;

    a process for selecting any one of said first determination process, second determination process, or third determination process in accordance with the objective alignment accuracy of said substrate; and

    ,a process for moving said substrate relative to a predetermined reference position in accordance with the alignment mark position determined by the selected determination process.

View all claims
  • 0 Assignments
Timeline View
Assignment View
    ×
    ×