MASKLESS EXPOSURE APPARATUS AND METHOD TO DETERMINE EXPOSURE START POSITION AND ORIENTATION IN MASKLESS LITHOGRAPHY

• US 20120081682A1
• Filed: 07/19/2011
• Published: 04/05/2012
• Est. Priority Date: 10/01/2010
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: AHN, Sung Min, JANG, Sang Don, SON, Tae Kyu
• Granted Patent: US 8,755,034 B2
• Time in Patent Office: Days
• US Class Current: 355/67
• CPC Class Codes: G03B 27/521 Arrangements for applying a supplementary information onto the sensitive material, e.g. coding producing marks on the film in cameras G03B17/24
• CPC Class Codes: G03B 27/53 Automatic registration or positioning of originals with respect to each other or the photosensitive layer
• CPC Class Codes: G03F 7/70291 Addressable masks, e.g. spatial light modulators [SLMs], digital micro-mirror devices [DMDs] or liquid crystal display [LCD] patterning devices
• 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 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
• CPC Class Codes: G03F 9/7011 Pre-exposure scan; original with original holder alignment; Prealignment, i.e. workpiece with workpiece holder
• CPC Class Codes: G03F 9/7015 Reference, i.e. alignment of original or workpiece with respect to a reference not on the original or workpiece

Abstract

According to an example embodiment, a method to determine an exposure start position and orientation includes loading a substrate on a moving table. The substrate includes at least one alignment mark of a first set of alignment marks of a first pattern layer patterned thereon. At least one alignment mark of a second set of alignment marks of a second pattern layer is exposed on the substrate using maskless lithography. A position of the at least one alignment mark of the first set of alignment marks and a position of the at least one alignment mark of the second set of alignment marks on the substrate is measured. A relative orientation difference between a desired exposure start orientation and an obtained exposure start orientation is acquired using the measured positions of the at least one alignment mark of the first set of alignment marks and the at least one alignment mark of the second set of alignment marks. A relative position difference between a desired exposure start position and an obtained start position is acquired using the measured positions of the at least one alignment mark of the first set of alignment marks and the at least one alignment mark of the second set of alignment marks. An exposure start position and orientation compensated using the relative position difference and the relative orientation difference is determined.

Claims

1. A method to determine an exposure start position and orientation comprising:

loading a substrate, on which is patterned at least one alignment mark of a first set of alignment marks of a first pattern layer, on a moving table;

exposing at least one alignment mark of a second set of alignment marks of a second pattern layer using maskless lithography;

measuring a position of the at least one alignment mark of the first set of alignment marks and a position of the at least one alignment mark of the second set of alignment marks on the substrate;

acquiring a relative orientation difference between a desired exposure start orientation and an obtained exposure start orientation using the measured positions of the at least one alignment mark of the first set of alignment marks and the at least one alignment mark of the second set of alignment marks;

acquiring a relative position difference between a desired exposure start position and an obtained start position using the measured positions of the at least one alignment mark of the first set of alignment marks and the at least one alignment mark of the second set of alignment marks; and

determining an exposure start position and orientation compensated using the relative position difference and the relative orientation difference.

2. The method according to claim 1, further comprising:

providing as the substrate at least one of a reference substrate having the first pattern layer thereon, and a substrate exposed to the first pattern layer in a separate exposure apparatus for Multi Machine Overlay (MMO).

3. The method according to claim 2, further comprising:

providing the first pattern layer including information required to locate the exposure start position and orientation.

4. The method according to claim 1, wherein the acquiring the relative orientation difference between the desired exposure start orientation and the obtained exposure start orientation using the measured positions of the at least one alignment mark of the first set of alignment marks and the at least one alignment mark of the second set of alignment marks includes,

acquiring a difference between the desired exposure start orientation and the obtained exposure start orientation after assembly of exposure equipment based on the equation

Δ

θ

=−

[arg(^MSr₁₂−

^MSr₁₁)−

arg(^MSr₂₂−

^MSr₂₁)]w.r.tΣ

₀

wherein,

“

^MSr₁₂”

is a position of a first alignment mark of the first set of alignment marks of the first pattern layer, the position of the first alignment mark of the first set of alignment marks being measured based on a measurement coordinate system,

“

^MSr₁₁”

is a position of a second alignment mark of the first set of alignment marks of the first pattern layer, the position of the second alignment mark of first set of alignment marks being measured based on the measurement coordinate system,

“

^MSr₂₂”

is a position of a first alignment mark of the second set of alignment marks of the second pattern layer, the position of the first alignment mark of the second set of alignment marks being measured based on the measurement coordinate system, and

“

^MSr₁₁”

is a position of a second alignment mark of the second set of alignment marks of the second pattern layer, the position of the second alignment mark of the second set of alignment marks being measured based on the measurement coordinate system.

5. The method according to claim 1, further comprising:

compensating for the exposure start orientation of the substrate using the relative orientation difference;

repeatedly loading and exposing the substrate after compensating for the exposure start orientation of the substrate; and

measuring a position of the at least one alignment mark of the first set of alignment marks and a position of the at least one alignment mark of the second set of alignment marks on the substrate after completion of the repeated exposure of the substrate.

6. The method according to claim 5, wherein the acquiring the relative position difference between the desired exposure start position and the obtained start position using the measured positions of the at least one alignment mark of the first set of alignment marks and the at least one alignment mark of the second set of alignment marks includes,

acquiring a difference between the desired exposure start position and the obtained exposure start position after assembly of equipment based on the kinematic relationship between the repeatedly measured positions of the at least one alignment mark of the first set of alignment marks and the at least one alignment mark of the second set of alignment marks.

7. The method according to claim 6, further comprising:

compensating for a difference between the desired exposure start position and orientation and the obtained exposure start position and orientation after assembly of the exposure equipment, and after exposing the at least one alignment mark of the first set of alignment marks on the first pattern layer.

8. The method according to claim 7, further comprising:

compensating for the difference between the desired exposure start position and orientation and the obtained exposure start position and orientation after assembly of the exposure equipment and after exposing a pattern layer on another substrate on which an alignment mark is not formed.

9. The method according to claim 6, wherein the determining the exposure start position and orientation compensated using the relative position difference and the relative orientation difference includes,

acquiring a compensation command value with respect to the obtained exposure start position and orientation using the following equations by compensating for a desired command value with respect to the obtained start position and orientation using the relative position and orientation differences:

10. A maskless exposure apparatus, comprising:

a stage configured to receive a substrate on a moving table thereof and move the substrate in X-, Y- and θ

-directions, the substrate including a pattern layer;

a light modulation element configured to expose the pattern on the substrate using a beam spot array of exposure beams;

a measurement system configured to measure a position of an alignment mark previously patterned on the substrate and a position of an alignment mark of the pattern exposed on the substrate; and

a control unit configured to acquire a relative orientation difference between a desired exposure start orientation and an obtained orientation using the measured positions of the alignment marks and a relative position difference between a desired exposure start position and an obtained position using the measured positions of the alignment marks, and determine an exposure start position and orientation compensated using the relative orientation difference and the relative position difference.

11. The apparatus according to claim 10, wherein the substrate includes at least one of a reference substrate having the pattern layer and a substrate exposed to the first pattern layer in a separate exposure apparatus for Multi Machine Overlay (MMO).

12. The apparatus according to claim 11, wherein the substrate having the pattern layer includes pattern information required to locate the exposure start position and orientation.

13. The apparatus according to claim 10, wherein the measurement system includes at least one of a non-contact Coordinate Measuring Machine (CMM) and an Alignment Scope Unit (ASU).