INTERFERENCE EXPOSURE DEVICE AND METHOD

• US 20140176925A1
• Filed: 08/16/2012
• Published: 06/26/2014
• Est. Priority Date: 08/22/2011
• Status: Active Grant

• Current Assignee: Shanghai Micro Electronics Equipment Company Limited
• Original Assignee: Shanghai Micro Electronics Equipment Company Limited
• Inventors: Wang, Fan, Xu, Qixin
• Granted Patent: US 9,195,146 B2
• Time in Patent Office: Days
• US Class Current: 355/53
• CPC Class Codes: G01B 11/14 for measuring distance or clearance between spaced objects or spaced apertures G01B11/26 takes precedence; rangefinders G01C3/00
• CPC Class Codes: G01B 11/26 for measuring angles or tapers; for testing the alignment of axes
• CPC Class Codes: G03F 7/70208 Multiple illumination paths, e.g. radiation distribution devices, microlens illumination systems, multiplexers or demultiplexers for single or multiple projection systems
• CPC Class Codes: G03F 7/70408 Interferometric lithography; Holographic lithography; Self-imaging lithography, e.g. utilizing the Talbot effect
• CPC Class Codes: G03F 7/70775 Position control, e.g. interferometers or encoders for determining the stage position
• CPC Class Codes: G03F 9/7007 Alignment other than original with workpiece

Abstract

An interference exposure device, including: a light source (100) for providing an exposure light beam; a light homogenizer-collimator (200) for homogenizing and collimating the exposure light beam; an interference unit (300) including at least two gratings (303) for converting the exposure light beam into at least two coherent light beams and making the coherent light beams converge on a substrate surface to form thereon an interference exposure pattern, the gratings (303) each having a period and being distributed in correspondence with a desired exposure pattern; a driving and supporting means (406) for supporting and carrying the substrate to move with at least three degrees of freedom; and a measuring element (500) for measuring an angle between coordinate systems of the interference unit (300) and the means (406) to adjust an exposure position of the means (406) based on a measurement result of the measuring element (500) before exposing the substrate.

Claims

1. An interference exposure apparatus, comprising:

a light source for providing an exposure light beam;

a light homogenizer-collimator for homogenizing and collimating the exposure light beam emanating from the light source;

an interference unit including at least two gratings for converting the exposure light beam into at least two coherent light beams, the interference unit being movable in a vertical direction to make the at least two coherent light beams converge on a surface of a substrate to form an interference exposure pattern, the at least two gratings each having a period in correspondence with a period of a desired exposure pattern and being distributed in correspondence with a distribution characteristic of the desired exposure pattern;

a driving and supporting means for supporting the substrate and carrying the substrate to move with at least three degrees of freedom; and

a measuring means for measuring an angle between a coordinate system of the interference unit and a coordinate system of the driving and supporting means so as to adjust an exposure position of the driving and supporting means based on a measurement result of the measuring means before exposing the substrate.

2. The interference exposure apparatus of claim 1, wherein the interference unit includes three gratings each in a shape of a regular hexagon and having grating-lines inclined at an angle of 120 degrees with respect to grating-lines of any of the other two gratings, and wherein the interference exposure pattern formed on the substrate is an array of closely-spaced dots arranged in a regular hexagon.

3. The interference exposure apparatus of claim 1, wherein the interference unit includes two parallelly arranged rectangular gratings each having grating-lines in parallel with grating-lines of the other grating, and wherein the interference exposure pattern formed on the substrate is an array of closely-spaced lines.

4. The interference exposure apparatus of claim 1, wherein the driving and supporting means includes an alignment mark.

5. The interference exposure apparatus of claim 1, further comprising a diaphragm disposed between the driving and supporting means and the substrate.

6. The interference exposure apparatus of claim 1, wherein the interference unit is replaceable.

7. The interference exposure apparatus of claim 1, wherein each grating has a shape in correspondence with a shape of an exposure field.

8. An interference exposure method using the interference exposure apparatus according to claim 1, comprising:

loading an interference unit and loading a substrate on a driving and supporting means;

measuring an angle between a coordinate system of the interference unit and a coordinate system of the driving and supporting means with a measuring means;

resetting an exposure position of the driving and supporting means according to the measured angle and a predetermined position of an exposure field;

moving the driving and supporting means to the reset exposure position; and

making at least two coherent light beams converted, by the interference unit, from an exposure light beam emanating from a light source to converge on a surface of the substrate and exposing the substrate in a field-by-field manner.

9. The interference exposure method of claim 8, wherein the exposure position

10. The interference exposure apparatus of claim 1, further comprising an alignment means including at least two measuring elements disposed over the interference unit, wherein the interference unit further comprises at least two identification marks and the driving and supporting means comprises an alignment mark, and wherein the alignment means detects, through adjusting an imaging focal length thereof, the at least two identification marks on the interference unit and the alignment mark on the driving and supporting means.

11. An interference exposure and alignment method for large-area periodic patterning of a substrate, the method using the interference exposure apparatus according to claim 10 with the alignment means including a first measuring element and a second measuring element and the interference unit including a first identification mark and a second identification mark, the method comprising the steps of:

a) performing an off-line calibration to determine conversion relations between coordinate systems of the first and second measuring elements and a zero coordinate system of the driving and supporting means, as well as a non-orthogonality and a distortion of each of the coordinate systems of the first and second measuring elements;

b) moving the alignment mark of the driving and supporting means successively to reference positions respectively corresponding to aim positions in the coordinate systems of the first and second measuring elements, determining pixel positions of the alignment mark in the first and second measuring elements, and taking the determined pixel positions as updated aim positions;

c) obtaining positions of the first and second identification marks of the interference unit, which are known parameters determined during the fabrication of the interference unit;

d) determining pixel positions of the first and second identification marks in the first and second measuring elements, respectively;

e) calculating offsets of the determined pixel positions of the first and second identification marks with respect to the updated aim positions;

f) calculating a conversion factor from the coordinate system of the first measuring element to the zero coordinate system of the driving and supporting means and a conversion factor from the coordinate system of the second measuring element to the zero coordinate system of the driving and supporting means;

g) converting the calculated offsets between the determined pixel positions with respect to the updated aim positions into offsets in the zero coordinate system of the driving and supporting means;

h) determining reference alignment positions of the first and second identification marks in the zero coordinate system of the driving and supporting means;

i) calculating actual positions of the first and second identification marks in the zero coordinate system of the driving and supporting means;

j) solving an alignment model to obtain a rotation amount RR^WZCS of the interference unit with respect to the zero coordinate system of the driving and supporting means; and

k) calculating a target predetermined position