Measuring method and exposure apparatus

• US 5,666,205 A
• Filed: 11/27/1995
• Issued: 09/09/1997
• Est. Priority Date: 12/03/1990
• Status: Expired due to Fees

• Current Assignee: Nikon Corporation
• Original Assignee: Nikon Corporation
• Inventors: Imai, Yuji, Kaise, Koji, Suwa, Kyoichi, Tateno, Hiroki
• Primary Examiner(s): Hantis, K.
• Application Number:
  US08/562,784
• Time in Patent Office: 652 Days
• Field of Search: 356/399-401, 356/124, 355/53, 355/77
• US Class Current: 356/401
• CPC Class Codes: G03F 7/70591 Testing optical components
• CPC Class Codes: G03F 7/70633 Overlay, i.e. relative alignment between patterns printed by separate exposures in different layers, or in the same layer in multiple exposures or stitching
• CPC Class Codes: G03F 7/70883 of optical system

Abstract

A measuring method comprises a first step to expose by the irradiation of a predetermined energy ray onto the resist layer of a photosensitive board a first mask pattern having at least two linear pattern portions arranged substantially in axial symmetry with respect to a straight line in a predetermined first direction and inclined at a predetermined angle to the straight line in the first direction, a second step to overlap with the first mask pattern image exposed on the resist layer a second mask pattern formed by the linear patterns which extend in a second direction substantially perpendicular to the first direction by relatively driving the second mask pattern in a predetermined amount in the first direction for exposure, and a third step to measure an interval in the second direction between at least two wedge-shaped resist images formed by the overlapped portions of the first mask pattern and the second mask pattern. The difference between the measured value and a predetermined standard value of the interval in the second direction may be obtained to determined a positional deviation.

Claims

1. A projection exposure apparatus for transferring a pattern at a predetermined position onto a substrate surface via a projection optical system, comprising:

a member having a surface disposed at said predetermined position and a test pattern formed on that surface, said test pattern including a pair of line segments which are arranged obliquely with respect to a predetermined measuring direction and which are not parallel to each other;

light-receiving means extending in a second direction substantially perpendicular to said measuring direction, and having a light-receiving surface arranged at or nearly at the same position along an optical axis of said projection optical system as said substrate surface, for detecting an interval in said second direction between parts of an image of said test pattern projected by said projection optical system that correspond to said line segments; and

arithmetic means for calculating an image deviation in said measurement direction based on the detected interval.

2. An apparatus according to claim 1, wherein said arithmetic means calculates said deviation by comparing the detected interval and a reference value.

3. An apparatus according to claim 1, wherein said arithmetic means is calculates a magnification error or a distortion of said projection optical system based on said deviation.

4. An apparatus according to claim 1, wherein said test pattern includes a pattern portion having a predetermined width, said light-receiving means detects a width of an image of said pattern portion, and said arithmetic means calculates a focal point position of said projection optical system based on the detected width.

5. A measuring method for an exposure apparatus which has a light source for emitting illumination light, an illumination optical system for illuminating a mask with said illumination light, a projection optical system for projecting an image of a pattern of the mask on a resist layer of a photosensitive substrate, a stage for holding said substrate and being movable along a first direction and a second direction substantially perpendicular to said first direction, said method comprising the steps of:

providing as said mask, a mask having a first mark pattern including at least two linear pattern portions which are non-parallel with respect to each other and obliquely oriented with respect to said first direction, and a second mark pattern displaced from said first mark pattern by a predetermined distance in said first direction and having at least one linear pattern portion oriented in said second direction;

projecting an image of said first mark pattern on said resist layer of said photosensitive substrate;

moving said stage in said first direction by a distance corresponding to said predetermined distance and projecting an image of said second mark pattern on said resist layer of said photosensitive substrate so as to form at least one pair of wedge-shaped resist images by overlapping parts of a resist image of said pattern portions of said first mark pattern with parts of a resist image of said pattern portion of said second mark pattern;

measuring an interval in said second direction between said pair of wedge-shaped resist images; and

obtaining a difference between said measured interval and a predetermined standard value of the interval.

6. A measuring method according to claim 5, further comprising a step of calculating, based on said difference and an intersecting angle of the resist images of said second mark pattern and said first mark pattern, an amount of a positional deviation generated when said parts of said resist images are overlapped.

7. A measuring method according to claim 6, wherein a direction of said positional deviation is substantially perpendicular to the direction in which said stage is moved.

8. A measuring method for an exposure apparatus which has a light source for emitting illumination light, an illumination optical system for illuminating a mask with said illumination light, a projection optical system for projecting an image of a pattern of the mask on a resist layer of a photosensitive substrate, a stage for holding said substrate and being movable along a first direction and a second direction substantially perpendicular to said first direction, said method comprising the steps of:

providing, as said mask, a mask having a first mark pattern including first and second pairs of linear pattern portions, the pattern portions of each pair being non-parallel with respect to each other and being arranged obliquely and substantially symmetrically with respect to a straight line in said first direction, and a second mark pattern displaced from said first mark pattern by a predetermined distance in said first direction and including a pair of substantially parallel linear pattern portions oriented in said second direction, said first and second pairs of pattern portions of said first mark pattern being substantially symmetrically disposed with respect to a straight line in said second direction;

projecting an image of said first mark pattern on said resist layer of the photosensitive substrate;

moving said stage in said first direction by a distance corresponding to said predetermined distance and projecting an image of said second mark pattern on said resist layer so as to form at least two pairs of wedge-shaped resist images by overlapping parts of a resist image of said pattern portions of said first mark pattern with parts of a resist image of said pattern portions of said second mark pattern;

measuring respective intervals in said second direction between the wedge-shaped resist images of each said pair of resist images; and

obtaining a difference between the measured intervals.

9. A measuring method according to claim 8, further comprising the step of calculating, based on said difference and an intersecting angle of the resist images of said second mark pattern and said first mark pattern, an mount of a positional deviation generated when said parts of said resist images are overlapped.

10. A measuring method for an exposure apparatus which has a light source for emitting illumination light, an illumination optical system for illuminating a mask with said illumination light, a projection optical system for projecting an image of a pattern of the mask on a resist layer of a photosensitive substrate, a stage for holding said substrate and being movable along a first direction and a second direction substantially perpendicular to said first direction, said method comprising the steps of:

providing, as said mask, a mask having a first mark pattern includes first, second and third linear pattern portions, with said first and second pattern portions being arranged obliquely and substantially symmetrically with respect to a first straight line in said first direction and said second and third pattern portions being arranged obliquely and substantially symmetrically with respect to a second straight line in said first direction, and a second mark pattern displaced from said first mark pattern by a predetermined distance in said first direction and having linear pattern portions corresponding to said pattern portions of said first mark pattern and disposed at a predetermined angle relative to the corresponding pattern portions;

projecting an image of said first mark pattern on said resist layer of the photosensitive substrate moving said stage in said first direction by a distance corresponding to said predetermined distance and projecting an image of said second mark pattern on said resist layer so as to form three wedge-shaped resist images by overlapping parts of a resist image of said pattern portions of said first mark pattern with parts of a resist image of the corresponding pattern portions of said second mark pattern;

measuring intervals in said second direction between adjacent pairs of said wedge-shaped resist images; and

obtaining a difference between the measured intervals.

11. A measuring method according to claim 10, further comprising the step of calculating, based on said difference and an intersecting angle of the resist images of said second mark pattern and said first mark pattern, an amount of positional deviation generated when said parts of said resist images are overlapped.

12. A measuring method according to claim 11, wherein said linear pattern portions of said second mark pattern constitute parts of a linear pattern element extended in said second direction.

13. A measuring method according to claim 11, wherein the corresponding pattern portions of said first and second mark patterns are arranged obliquely and substantially symmetrically with respect to a straight line in said second direction.

14. A measuring method according to claim 10, wherein said mask includes plural sets of mark patterns arranged in series in said first direction, each set including a said first mark pattern and a said second mark pattern.

15. A measuring method for an exposure apparatus which has a light source for emitting illumination light, an illumination optical system for illuminating a mask with said illumination light, a projection optical system for projecting an image of a pattern of the mask on a resist layer of a photosensitive substrate, a stage for holding said substrate and being movable along a first direction and a second direction substantially perpendicular to said first direction, said method comprising the steps of:

providing, as said mask, a mask having a first mark pattern including first and second linear pattern portions which are arranged obliquely and substantially symmetrically with respect to a straight line in said first direction and a third linear pattern portion arranged obliquely and substantially symmetrically with one of said first and second pattern portions with respect to a straight line in said second direction, and a second mark pattern including a first linear pattern portion extended in said first direction and a second linear pattern portion extended in said second direction;

projecting an image of said first mark pattern on said resist layer of said photosensitive substrate;

moving said stage in a predetermined manner and projecting an image of said second mark pattern on said resist layer of said photosensitive substrate so as to form a first pair of wedge-shaped resist images by overlapping parts of a resist image of said first and second pattern portions of said first mark pattern with parts of a resist image of said second pattern portion of said second mark pattern, and a second pair of wedge-shaped resist images by overlapping parts of a resist image of said second and third pattern portions of said first mark pattern with parts of a resist image of said first pattern portion of said second mark pattern;

measuring an interval in said second direction between said first pair of wedge-shaped resist images;

measuring an interval in said first direction between said second pair of wedge-shaped resist images; and

determining amounts of positional deviation based on the measured intervals.