Back to results
US 5,333,050 AGranted
Measuring method and apparatus for meausring the positional relationship of first and second gratings
AssigneeCanon Kabushiki Kaisha
InventorsNoriyuki Nose, Kenji Saitoh, Koichi Sentoku, Minoru Yoshii
Life of this patent
Estimating the term…
Abstract
Disclosed is a method and apparatus for measuring a relative positional deviation between a first pattern and a second pattern, printed on an article such as a semiconductor wafer at different moments, the measurement being based on detection of interference of diffraction lights from at least one of the first and second printed patterns.
Claims16
An apparatus for measuring positional relationship between first and second diffraction gratings, said apparatus comprising:
- light producing means for producing first and second light beams;
- a light projecting optical system for projecting a first portion of the first light beam to the first diffraction grating and for projecting a first portion of the second light beam to the second diffraction grating;
- a light receiving optical system for causing a first diffraction light beam, diffracted by the first diffraction grating, and a second portion of the second light beam to interfere with each other to produce a first interference light beam, and also for causing a second diffraction light beam, diffracted by the second diffraction grating, and a second portion of the first light beam to interfere with each other to produce a second interference light beam, said light receiving optical system comprising a light separating element for deflecting at least one of the first and second interference light beams, at a position substantially optically conjugate with at least one of the first and second diffraction gratings, to separate the one of the first and second interference light beams from the other;
- a first light receiving element for detecting the first interference light beam and for producing a first output signal;
- a second light receiving element for detecting the second interference light beam and for producing a second output signal;
- and
- signal processing means for detecting a phase difference between the first and second output signals to determine the positional relationship between the first and second diffraction gratings.
4 more elements
A method of measuring positional relationship between first and second diffraction gratings, said method comprising the steps of:
- producing first and second light beams;
- projecting a first portion of the first light beam to the first diffraction grating and projecting a first portion of the second light beam to the second diffraction grating;
- causing a first diffraction light beam, diffracted by the first diffraction grating, and a second portion of the second light beam to interfere with each other to produce a first interference light beam, and causing a second diffraction light beam, diffracted by the second diffracting grating, and a second portion of the first light beam to interfere with each other to produce a second interference light beam, said causing steps comprising deflecting at least one of the first and second interference light beams at a position substantially optically conjugate with at least one of the first and second diffraction gratings, to separate the one of the first and second interference light beams from the other;
- detecting the first and second interference light beams to produce corresponding first and second signals;
- and
- detecting a phase difference between the first and second signals to determine the positional relationship between the first and second diffraction gratings.
3 more elements
An apparatus for measuring positional relationship between first and second diffraction gratings, said apparatus comprising:
- light producing means for producing first and second light beams;
- a light projecting optical system for projecting the first light beam to the first diffraction grating and for projecting the second light beam to the second diffraction grating;
- a light receiving optical system for causing a first diffraction light beam diffracted by the first diffraction grating and a second diffraction light beam diffracted by the second diffraction grating to interfere with other to produce an interference light beam, said light receiving optical system comprising a wave combining element for shifting the first and second diffraction light beams each in a direction perpendicular to their direction of advancement and for wave-combining the first and second diffraction light beams;
- a light receiving element for detecting the interference light beam and for producing an output signal;
- and
- signal processing means for detecting a phase of the output signal of said light receiving element to determine the positional relationship between the first and second diffraction gratings.
3 more elements
A method of measuring positional relationship between first and second diffraction gratings, said method comprising the steps of:
- producing first and second light beams;
- projecting the first light beam to the first diffraction grating and projecting the second light beam to the second diffraction grating;
- causing a first diffraction light beam diffracted by the first diffraction grating and a second diffraction light beam diffracted by the second diffraction grating to interfere with each other to produce an interference light beam, said causing step comprising combining the first and second diffraction light beams by shifting, through a wave combining element, the first and second diffraction light beams each in a direction perpendicular to their direction of advancement;
- detecting the interference light beam with a light receiving element and producing an output signal;
- and
- detecting a phase of the output signal of the light receiving element to determine the positional relationship between the first and second diffraction gratings.
3 more elements
An apparatus for measuring positional relationship between first and second diffraction gratings, said apparatus comprising:
- light producing means for producing a light beam;
- a light projecting optical system for projecting a first portion of the light beam to the first and second diffraction gratings;
- an interference optical system for causing a first diffraction light beam, diffracted by the first diffraction grating and a second portion of the light beam to interfere with each other to produce a first interference light beam, and also for causing a second diffraction light beam, diffracted by the second diffraction grating, and the second portion of the light beam to interfere with each other to produce a second interference light beam, said interference optical system comprising optical path length changing means for changing an optical path length of at least one of the first and second diffraction beams and the second portion of the light beam;
- light receiving means for detecting the first and second interference light beams;
- and
- signal processing means for detecting a change in at least one of the first and second interference light beams due to a corresponding change in path length of at least one of the first and second diffraction light beams and the second portion of the light beam, changed by said optical path length changing means, to determine the positional relationship between the first and second diffraction gratings.
3 more elements
A method of measuring positional relationship between first and second diffraction gratings, said method comprising:
- producing a light beam;
- projecting a first portion of the light beam to the first and second diffraction gratings;
- causing a first diffraction light beam, diffracted by the first diffraction grating and a second portion of the light beam to interfere with each other to produce a first interference light beam, and causing a second diffraction light beam, diffracted by the second diffraction grating and the second portion of the light beam to interfere with each other to produce a second interference light beam, said causing steps comprising changing an optical path length of at least one of the first and second diffraction light beams and the second portion of the light beam;
- detecting the first and second interference light beams;
- and
- detecting a change in at least one of the first and second interference light beams, resulting from said optical path length changing, to determine the positional relationship between the first and second diffraction gratings.
3 more elements
An exposure apparatus comprising:
- exposing means for lithographically transferring a pattern onto a workpiece;
- an illumination system for illuminating first and second diffraction gratings, formed on the same plane of the workpiece by said exposure means;
- a detecting system for detecting interference light produced from light beams respectively diffracted by the first and second diffraction gratings;
- and
- signal processing means for detecting the positional relationship between the first and second diffraction gratings on the basis of the detection by said detecting system.
2 more elements
Dependencies are inferred from the claim text.