Exposure apparatus with a function for controlling alignment by use of latent images

• US 5,140,366 A
• Filed: 08/08/1991
• Issued: 08/18/1992
• Est. Priority Date: 05/29/1987
• Status: Expired due to Term

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Kanda, Tsuneo, Shiozawa, Takahisa, Suzuki, Akiyoshi
• Primary Examiner(s): Hayes, Monroe H.
• Application Number:
  US07/742,535
• Time in Patent Office: 376 Days
• Field of Search: 355/53, 355/54, 355/77
• US Class Current: 355/53
• CPC Class Codes: G03F 9/70 for microlithography measuring printed patterns for monitoring overlay G03F7/70633 or focus G03F7/70641; projection system adjustment G03F7/70258; position control G03F7/70775

Abstract

Disclosed is an exposure apparatus for printing a pattern of a reticle on different shot areas of the wafer in a step-and-repeat manner. In the disclosed apparatus, an image of an alignment mark of the reticle is printed, by use of a projection lens system, on each of some shot areas of the wafer which are selected as the subject of detection. By this, a latent image of the reticle mark is formed on each of the selected shot areas. The latent image of the reticle mark is detected by a microscope which may be a phase contrast microscope and, from the results of detection concerning all the latent images of the reticle mark, a reference (correction) grid representing the coordinate positions of all the shot areas of the wafer is prepared and stored. In accordance with the stored reference grid, the stepwise movement of the wafer is controlled at the time of the step-and-repeat exposures of the wafer. This assures improved throughput of the apparatus. Further, use of the phase contrast microscope for the detection of the latent image of the reticle mark ensures further improvement in the alignment accuracy.

Claims

1. An exposure apparatus, comprising:

exposing means for printing, on a workpiece, a pattern formed on an original;

latent image forming means for printing, on the workpiece, an image of a mark provided on the original so as to form on the workpiece a latent image of the mark;

moving means for moving the workpiece so that the pattern of the original is printed on different portions of the workpiece by said exposing means;

latent image detecting means for detecting each of the latent images of the mark, formed by said latent image forming means in relation to those portions of the workpiece of a number smaller than the number of all the portions of the workpiece, said latent image detecting means producing signals corresponding to the detected latent images; and

controlling means operable to calculate the state of array of all the portions of the workpiece, on the basis of the signals produced from said latent image detecting means, said controlling means also being operable to control the movement of the workpiece by said moving means for step-and-repeat exposures of the workpiece in accordance with the result of calculation.

2. An apparatus according to claim 1, wherein said latent image forming means uses a light having substantially the same wavelength as that of the light used by said exposing means.

3. An apparatus according to claim 1, wherein said latent image detecting means is operable to detect, at the same time, latent images of the mark as having been formed in relation to adjacent portions of the workpiece.

4. An exposure method, comprising the steps of:

repeatedly printing on a workpiece an image of a mark of a pattern provided on an original while moving the workpiece, so that latent images of the mark are formed in relation to different portions of the workpiece;

detecting each of the latent images of the mark, formed on the workpiece, to obtain signals related to the latent images of the mark; and

effecting a desired calculation by use of the obtained signals and controlling, in accordance with the result of the calculation, the movement of the workpiece for step-and-repeat exposures of the different portions of the workpiece to the pattern formed on the original.

5. An exposure apparatus, comprising:

exposing means for printing a pattern of an original on a workpiece;

latent image forming means for printing on the workpiece an image of a mark provided on the original to form a latent image of the mark on the workpiece;

latent image detecting means having a phase contrast microscope, for detecting a latent image of the mark formed on the workpiece by said latent image forming means; and

controlling means operable, at the time of printing of the pattern of the original upon the workpiece by said exposing means, to control the position of the workpiece relative to the original in accordance with a signal produced by said latent image detecting means.

6. An apparatus according to claim 5, wherein said exposing means and said latent image forming means include a common projection optical system for printing the pattern and the mark on the workpiece, respectively, and said exposing means and said latent image forming means use substantially the same wavelength of light for the printing.

7. An apparatus according to claim 5, wherein said latent image detecting means includes at least one of a bright-field microscope and a dark-field microscope, which is interchangeably used with said phase contrast microscope.

8. An exposure apparatus comprising:

exposing means for printing, on a workpiece, a pattern formed on an original;

image forming means for printing on the workpiece, a mark provided on the original by forming a latent image of the mark on a photosensitive layer of the workpiece;

moving means for moving the workpiece so that the pattern of the original is printed on different portions of the workpiece by said exposing means;

image detecting means for detecting each of the latent images of the mark formed by said image forming means in a reference array, the latent images formed in the reference array being less than the total images formed on the workpiece, said image detecting means producing signals corresponding to the detected latent images; and

controlling means operable to calculate the state of array of all of the portions of the workpiece, on the basis of the signals produced by said image detecting means, said controlling means also operable to control the movement of the workpiece by said moving means for step-and-repeat exposures of the workpiece in accordance with the results of the calculation.

9. An exposure method, comprising the steps of:

repeatedly forming on a photosensitive layer of a workpiece, a mark of a pattern provided on an original while moving the workpiece, for piecing latent images of the mark in relation to different portions of the workpiece;

detecting each of the latent images of the mark formed on the photosensitive layer of the workpiece to obtain signals related to the latent images of the mark; and

effecting a desired calculation by use of the obtained signals and controlling, in accordance with the result of the calculation, the movement of the workpiece for step-and-repeat exposures of the different portions of the workpiece to the pattern formed on the original.

10. An exposure method, in the manufacture of semiconductor devices, for printing a device pattern of a mask on different zones of a semiconductor wafer in sequence, said method comprising the steps of:

selecting particular ones of the different zones of the wafer as measurement sample zones;

printing an alignment mark of the mask on the measurement sample zones in sequence while moving a wafer stage carrying the wafer;

detecting the printed alignment marks of the measurement sample zones through an alignment optical system while moving the wafer stage, and producing detection signals corresponding tot he results of the detection;

determining data related to disposition of the different zones of the wafer, in accordance with the detection signals produced and by calculation; and

printing the device pattern of the mask on the different zones of the wafer in sequence, while controlling movement of the wafer stage in accordance with the determined data.

11. A method according to claim 10, wherein said printing step comprises printing the device pattern of the mask on the wafer by projection through a projection optical system, and said detecting step comprises detecting each alignment mark printed on the wafer through the alignment optical system free from intervention of the projection optical system.

12. An exposure method, in the manufacture of semiconductor devices, for printing a device pattern of a mask on different zones of a semiconductor wafer in sequence, said method comprising the steps of:

selecting particular ones of the different zones of the wafer as measurement sample zones;

printing an alignment mark of the mask on each measurement sample zone, and detecting the printed alignment mark through an alignment optical system for producing detection signals corresponding to the printed alignment marks said printing step and said detecting step being performed while moving a wafer stage which carries the wafer;

determining data related to disposition of the different zones of the wafer, in accordance with the detection signals produced and by calculation; and

printing the device pattern of the mask on the different zones of the wafer in sequence, while controlling movement of the wafer stage in accordance with the determined data.

13. A method according to claim 12, wherein said printing step comprises printing the device pattern of the mask on the wafer by projection through a projection optical system, an said detecting step comprises detecting each alignment mark printed on the wafer through the alignment optical system free from intervention of the projection optical system.

14. A method, in the manufacture of semiconductor devices, for exposing different zones of a semiconductor wafer with exposure light in sequence, said method comprising the steps of:

selecting particular ones of the different zones of the wafer as measurement sample zones;

irradiating each measurement sample zone with light substantially the same as the exposure light, and detecting the irradiated measurement sample zone through a detection optical system for producing a corresponding detection signal, said irradiating step and said detecting step being performed while moving a wafer stage which carried the wafer;

determining data related to disposition of the different zones of the wafer, in accordance with the detection signals produced and by calculation; and

exposing the different zones of the wafer with the exposure light in sequence, while controlling movement of the wafer stage in accordance with the determined data.

15. A method according to claim 14, further comprising alternately effecting said irradiating step and said detecting step with respect to the measurement sample zones.

16. A method according to claim 14, further comprising beginning said detecting step after all the measurement sample zones have been irradiated with the light in said irradiating step.

17. An exposure method, in the manufacture of semiconductor devices, for exposing different zones of a semiconductor wafer with exposure light in sequence, said method comprising the steps of:

placing the wafer on a wafer stage;

irradiating predetermined ones of the different zones of the wafer with first light from a first light source, and detecting the irradiated zones of the wafer through a detection optical system by irradiating the zones with second light from a second light source for producing corresponding detection signals, said irradiating step and said detecting step being performed while moving the wafer stage;

determining data related to disposition of the different zones of the wafer in accordance with the detection signals produced, by calculation; and

exposing the different zones of the wafer with the exposure light in sequence, while controlling movement of the wafer stage in accordance with the determined data.

18. A method according to claim 17, further comprising alternately effecting said irradiating step and said detecting step with respect to the predetermined zones of the wafer.

19. A method according to claim 17, further comprising beginning said detecting step after all the predetermined zones have been irradiated with the first light in said irradiating step.

20. A semiconductor device manufacturing method comprising the steps of:

holding on a reticle holder a reticle having an alignment mark and a pattern;

holding on a substrate holder a substrate having a photosensitive layer and a plurality of shot areas including selectable areas;

exposing the selectable areas to the alignment mark of the reticle through an exposure optical system, while moving the substrate holder, to permit a detection optical system to detect positional information for the selectable areas;

obtaining grid information indicative of positions of the shot areas using the positional information of the selectable areas; and

moving the substrate holder on the basis of the grid information when the substrate is exposed to the pattern of the reticle through the exposure optical system.

21. A method according to claim 20, further comprising effecting said exposing step and the detection by the detection optical system for each of the selectable areas.

22. A method according to claim 20, further comprising effecting the detection by the detection optical system after effecting said exposing step for all of the selectable areas.