Aligning method utilizing reliability weighting coefficients

• US 5,543,921 A
• Filed: 06/05/1995
• Issued: 08/06/1996
• Est. Priority Date: 05/08/1989
• Status: Expired due to Term

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Tanaka, Hiroshi, Imaizumi, Masaaki, Uzawa, Shigeyuki, Kaneko, Yoshio, Takakura, Noburu, Nakai, Akiya
• Primary Examiner(s): Evans, F. L.
• Assistant Examiner(s): KIM, ROBERT H
• Application Number:
  US08/465,098
• Time in Patent Office: 428 Days
• Field of Search: 356/399, 356/400, 356/401, 250/548
• US Class Current: 356/401
• CPC Class Codes: G03F 9/7003 Alignment type or strategy, e.g. leveling, global alignment
• CPC Class Codes: G03F 9/7088 Alignment mark detection, e.g. TTR, TTL, off-axis detection, array detector, video detection
• CPC Class Codes: G03F 9/7092 Signal processing

Abstract

An aligning method suitably usable in a semiconductor device manufacturing exposure apparatus of step-and-repeat type, for sequentially positioning regions on a wafer to an exposure position. In one preferred form, the marks provided on selected regions of the wafer are detected to obtain corresponding mark signals and then respective positional data related to the positions or positional errors of the selected regions are measured, on the basis of the mark signals. Then, the reliability of each measured positional data of a corresponding selected region is detected, on the basis of the state of a corresponding mark signal or the state of that measured positional data and by using fuzzy reasoning, for example. Corrected positional data related to the disposition of all the regions on the wafer is then prepared by using the measured positional data of the selected regions, wherein, for preparation of the corrected positional data, each measured positional data is weighted in accordance with the detected reliability thereof such that measured positional data having higher reliability is more influential to determine the corrected positional data.

Claims

1. An aligning method for sequentially positioning different regions on a workpiece to a predetermined site, said method comprising the steps of:

detecting marks provided on selected regions on the workpiece to obtain corresponding mark signals and then measuring respective positional data related to the positions or positional errors of said selected regions, on the basis of the mark signals;

detecting the reliability of each measured positional data of a corresponding selected region, on the basis of the state of a corresponding mark signal or the state of that measured positional data;

preparing corrected position data related to the disposition of all the regions on the workpiece by using the measured positional data of the selected regions and design positional data of the selected regions, wherein, for preparation of the corrected positional data, each measured position data is weighted in accordance with the detected reliability thereof such that a measured positional data having high reliability is more influential to determine the corrected positional data; and

controlling movement of the workpiece, for sequential positioning of the different regions on the workpiece to the predetermined site, on the basis of the prepared corrected positional data, wherein a plurality of conditional propositions for evaluation of the mark signals or the respective states of the measured positional data of the selected regions, are prepared by use of fuzzy sets, and, on the basis of the result of fuzzy reasoning, the reliability of each measured positional data is detected.

2. An aligning method for sequentially positioning different regions on a workpiece to a predetermined site, said method comprising the steps of:

detecting marks provided on selected regions on the workpiece to obtain corresponding mark signals and then measuring respective positional data related to the positions or positional errors of said selected regions, on the basis of the mark signals;

detecting the reliability of each measured positional data of a corresponding selected region, on the basis of the state of a corresponding mark signal or the state of that measured positional data;

preparing corrected position data related to the disposition of all the regions on the workpiece by using the measured positional data of the selected regions and design positional data of the selected regions, wherein, for preparation of the corrected positional data, each measured position data is weighted in accordance with the detected reliability thereof such that a measured positional data having high reliability is more influential to determine the corrected positional data; and

controlling movement of the workpiece, for sequential positioning of the different regions on the workpiece to the predetermined site, on the basis of the prepared corrected positional data, wherein a remainder between the measured positional data and the corrected positional data of the i-th region of the selected regions, in the X and Y directions, is denoted by R_ix and R_iy and when the weighting value corresponding to the reliability of the measured position data of the i-th region with respect to the X and Y directions is denoted by W_ix and W_iy, an operational form related to the corrected positional data is determined so as to make a value V minimum, where

space="preserve" listing-type="equation">V∝

Σ

[W.sub.ix ×

(R.sub.ix).sup.2 +W.sub.iy ×

(R.sub.iy).sup.2 ].

3. An aligning method for sequentially positioning different regions on a workpiece to a predetermined site, said method comprising the steps of:

detecting marks provided on selected regions on the workpiece to obtain corresponding mark signals and then measuring respective positional data related to the positions or positional errors of said selected regions, on the basis of the mark signals;

detecting the reliability of each measured positional data of a corresponding selected region, on the basis of the state of a corresponding mark signal or the state of that measured positional data;

preparing corrected position data related to the disposition of all the regions on the workpiece by using the measured positional data of the selected regions and design positional data of the selected regions, wherein, for preparation of the corrected positional data, each measured position data is weighted in accordance with the detected reliability thereof such that a measured positional data having high reliability is more influential to determine the corrected positional data; and

controlling movement of the workpiece, for sequential positioning of the different regions on the workpiece to the predetermined site, on the basis of the prepared corrected positional data, wherein, when the remainder between the measured positional data and the corrected positional data of the i-th region of the selected regions, with respect to the X and Y directions, is denoted by R_ix and R_iy and when the weighting value corresponding to the reliability of the measured positional data of the i-th region with respect to the X and Y directions is denoted by W_ix and W_iy, an operational form related to the corrected positional data is determined so as to make a value V minimum, where

space="preserve" listing-type="equation">V∝

Σ

[W.sub.ix ×

|R.sub.ix |+W.sub.iy ×

|R.sub.iy |].

4. An aligning method for sequentially positioning different regions on a workpiece to a predetermined site, said method comprising the steps of:

detecting marks provided on selected regions on the workpiece to obtain corresponding mark signals and then measuring respective positional data related to the positions or positional errors of said selected regions, on the basis of the mark signals;

detecting the reliability of each measured positional data of a corresponding selected region, on the basis of the state of a corresponding mark signal or the state of that measured positional data;

determining weighting values for the respective measured positional data of the selected regions, on the basis of the detected reliabilities of the respective measured positional data;

preparing corrected positional data related to the disposition of all the regions on the workpiece by using the measured positional data of the selected regions, design positional data of the selected regions and the determined weighting values; and

controlling movement of the workpiece, for sequential positioning of the different regions on the workpiece to the predetermined site, on the basis of the prepared corrected positional data, wherein each weighting value is selected out of a predetermined numerical range including zero and is set to be equal to zero when the reliability of the measured positional data is lower than a predetermined value.

5. An aligning method for sequentially positioning different regions on a workpiece to a predetermined site, said method comprising the steps of:

detecting marks provided on selected regions on the workpiece to obtain corresponding mark signals, and then measuring respective positional data related to the positions or positional errors of the selected regions on the basis of the mark signals;

determining weighting values for the respective measured positional data of the selected regions, on the basis of the respective states of the mark signals or of the respective states of the measured positional data of the selected regions, in accordance with fuzzy reasoning;

preparing corrected positional data related to the disposition of all the regions on the workpiece by using the measured positional data of the selected regions and the determined weighting values; and

controlling movement of the workpiece, for sequential positioning of the different regions on the workpiece to the predetermined site, on the basis of the prepared corrected positional data.

6. An aligning method for sequentially positioning different regions on a workpiece to a predetermined site, said method comprising the steps of:

detecting images of marks provided on selected regions on the workpiece through image pickup means having windows to obtain corresponding image signals from the windows, and then measuring respective positional data related to the positions or positional errors of the selected regions on the basis of the image signals;

determining weighting values indicative of reliability for the respective measured positional data of the selected regions, on the basis of the respective states of the image signals or of the respective states of the measured positional data of the selected regions;

preparing corrected positional data related to the disposition of all the regions on the workpiece by using the measured positional data of the selected regions, design positional data of the selected regions and the determined weighting values; and

controlling movement of the workpiece, for sequential positioning of the different regions on the workpiece to the predetermined site, on the basis of the prepared corrected positional data, wherein the image signals are processed by template matching and the determination of the weighting values of the measured positional data uses a peak match degree obtainable by the template matching.

7. An aligning method for sequentially positioning different regions on a workpiece to a predetermined site, said method comprising the steps of:

detecting images of marks provided on selected regions on the workpiece through image pickup means having windows to obtain corresponding image signals from the windows, and then measuring respective positional data related to the positions or positional errors of the selected regions on the basis of the image signals;

determining weighting values indicative of reliability for the respective measured positional data of the selected regions, on the basis of the respective states of the image signals or of the respective states of the measured positional data of the selected regions;

preparing corrected positional data related to the disposition of all the regions on the workpiece by using the measured positional data of the selected regions, design positional data of the selected regions and the determined weighting values; and

controlling movement of the workpiece, for sequential positioning of the different regions on the workpiece to the predetermined site, on the basis of the prepared corrected positional data, wherein the determination of the weighting values of the measured positional data uses a value related to the shape of a mark in each region detectable on the basis of the image signal.

8. An aligning method for sequentially positioning different regions on a workpiece to a predetermined site, said method comprising the steps of:

detecting images of marks provided on selected regions on the workpiece through image pickup means having windows to obtain corresponding image signals from the windows, and then measuring respective positional data related to the positions or positional errors of the selected regions on the basis of the image signals;

determining weighting values indicative of reliability for the respective measured positional data of the selected regions, on the basis of the respective states of the image signals or of the respective states of the measured positional data of the selected regions;

preparing corrected positional data related to the disposition of all the regions on the workpiece by using the measured positional data of the selected regions, design positional data of the selected regions and the determined weighting values; and

controlling movement of the workpiece, for sequential positioning of the different regions on the workpiece to the predetermined site, on the basis of the prepared corrected positional data, wherein the determination of the weighting values of the measured positional data uses a value related to an error in a rotational direction of each region detectable on the basis of the image signal.

9. An aligning method for sequentially positioning different regions on a workpiece to a predetermined site, said method comprising the steps of:

detecting images of marks provided on selected regions on the workpiece through image pickup means having windows to obtain corresponding image signals from the windows, and then measuring respective positional data related to the positions or positional errors of the selected regions on the basis of the image signals;

determining weighting values indicative of reliability for the respective measured positional data of the selected regions, on the basis of the respective states of the image signals or of the respective states of the measured positional data of the selected regions;

preparing corrected positional data related to the disposition of all the regions on the workpiece by using the measured positional data of the selected regions, design positional data of the selected regions and the determined weighting values; and

controlling movement of the workpiece, for sequential positioning of the different regions on the workpiece to the predetermined site, on the basis of the prepared corrected positional data, wherein a pattern form on an original is projected at a predetermined magnification to each of all the regions on the workpiece and the determination of the weighting values of the measured positional data uses a value related to a magnification error for each region detectable on the basis of the image signal.

10. An aligning method for sequentially positioning different regions on a workpiece to a predetermined site, said method comprising the steps of:

detecting marks provided on selected regions on the workpiece through a projection lens, for projecting a pattern of an original to each region on the workpiece, to obtain corresponding mark signals and then measuring respective positional data related to the positions or positional error of the selected regions, on the basis of the mark signals;

determining weighting values indicative of reliability for the respective measured positional data of the selected regions, on the basis of the respective states of the mark signals or of the respective states of the measured positional data of the selected regions;

preparing corrected positional data related to the disposition of all the regions on the workpiece by using the measured positional data of the selected regions, design positional data of the selected regions and the determined weighting values; and

controlling movement of the workpiece, for sequential positioning of the different regions on the workpiece to the predetermined site, on the basis of the prepared corrected positional data, wherein a plurality of conditional propositions for evaluation of the mark signals or the respective states of the measured positional data of the selected regions, are prepared by use of fuzzy sets, and, on the basis of the result of fuzzy reasoning, the reliability of each measured positional data is detected.

11. An aligning method for sequentially positioning different regions on a workpiece to a predetermined site, said method comprising the steps of:

detecting marks provided on selected regions on the workpiece through a projection lens, for protecting a pattern of an original to each region on the workpiece, to obtain corresponding mark signals and then measuring respective positional data related to the positions or positional error of the selected regions, on the basis of the mark signals;

determining weighting values indicative of reliability for the respective measured positional data of the selected regions, on the basis of the respective states of the mark signals or of thee respective states of the measured positional data of the selected regions;

preparing corrected positional data related to the disposition of all the regions on the workpiece by using the measured positional data of the selected regions, design positional data of the selected regions and the determined weighting values; and

controlling movement of the workpiece, for sequential positioning of the different regions on the workpiece to the predetermined site, on the basis of the prepared corrected positional data, wherein a remainder between the measured positional data and the corrected positional data of the i-th region of the selected regions, in the X and Y directions, is denoted by R_ix and R_iy and when the weighting value corresponding to the reliability of the measured positional data of the i-th region with respect to the X and Y directions is denoted by W_ix and W_iy, an operational form related to the corrected positional data is determined so as to make a value V minimum, where

space="preserve" listing-type="equation">V∝

Σ

[W.sub.ix ×

(R.sub.ix).sup.2 +W.sub.iy ×

(R.sub.iy).sup.2 ].

12. An aligning method for sequentially positioning different regions on a workpiece to a predetermined site, said method comprising the steps of:

detecting marks provided on selected regions on the workpiece through a projection lens, for protecting a pattern of an original to each region of the workpiece, to obtain corresponding mark signals and then measuring respective positional data related to the positions or positional error of the selected regions, on the basis of the mark signals;

determining weighting values indicative of reliability for the respective measured positional data of the selected regions, on the basis of the respective states of the mark signals or of the respective states of the measured positional data of the selected regions;

preparing corrected positional data related to the disposition of all the regions on the workpiece by using the measured positional data of the selected regions, design positional data of the selected regions and the determined weighting values; and

controlling movement of the workpiece, for sequential positioning of the different regions on the workpiece to the predetermined site, on the basis of the prepared corrected positional data, wherein, when the remainder between the measured positional data and the corrected positional data of the i-th region of the selected regions, with respect to the X and Y directions, is denoted by R_ix and R_iy and when the weighting value corresponding to the reliability of the measured positional data of the i-th region with respect to the X and Y directions is denoted by W_ix and W_iy, an operational form related to the corrected positional data is determined so as to make a value V minimum, where

space="preserve" listing-type="equation">V∝

Σ

[W.sub.ix ×

|R.sub.ix |+W.sub.iy ×

|R.sub.iy |].

13.

13. An aligning method for sequentially positioning different regions on a workpiece to a predetermined site, said method comprising the steps of:

detecting marks provided on selected regions on the workpiece through a projection lens, for projecting a pattern of an original to each region on the workpiece, to obtain corresponding mark signals and then measuring respective positional data related to the positions or positional errors of the selected regions, on the basis of the mark signals;

determining weighting values for the respective measured position data of the selected regions, on the basis of the respective states of the mark signals or of the respective states of the measured position data of the selected regions, in accordance with fuzzy reasoning, wherein each weighting value is zero or any other than zero; and

preparing corrected positional data related to the disposition of all the regions on the workpiece by using the measured positional data of the selected regions and the determined weighting values; and

controlling movement of the workpiece, for sequential positioning of the different regions on the workpiece to the predetermined site, on the basis of the prepared corrected positional data.