Method of controlling a patterning device in a lithographic apparatus, device manufacturing method and lithographic apparatus

Patent metadata

Field	Value
Publication number	US-9482963-B2
Application number	US-201113885066-A
Country	US
Kind code	B2
Filing date	Dec 2, 2011
Priority date	Dec 20, 2010
Publication date	Nov 1, 2016
Grant date	Nov 1, 2016

Abstract

A system for controlling a patterning device in a lithographic apparatus using a patterning device having individually controllable elements that may only be set to two states. The method includes converting a representation of a pattern to be formed on the substrate into a plurality of area intensity signals, each corresponding to a radiation intensity level required to be set in a respective area of the patterning device in order to provide the desired pattern on the substrate and a separate step of converting each of the area intensity signals into control signals for a plurality of individually controllable elements that each correspond to the area of the patterning device.

First claim

The invention claimed is:

1. A method comprising:
converting a representation of a pattern desired to be formed on a substrate into a plurality of area intensity signals, each corresponding to a radiation intensity level to be set in a respective area of a patterning device in a lithographic apparatus such that the effect at the substrate of the respective radiation intensity levels being set in each area of the patterning device is the desired pattern, the patterning device comprising a plurality of individually controllable elements that each may be set to either a first state, in which radiation is directed to a corresponding portion of the substrate, or a second state, in which radiation is not directed to a corresponding portion of the substrate;
converting each of the area intensity signals into a plurality of control signals for a respective plurality of individually controllable elements corresponding to the area of the patterning device such-that the individually controllable elements are set to appropriate states in order that the combined effect of setting all of the individually controllable elements in the area to the states in use is to provide the radiation intensity level for the area specified in the area intensity signal; and
setting each of the individually controllable elements according to its associated control signal.

2. The method according to claim 1 , further comprising:
inspecting the substrate in order to determine at least one selected from: a distortion of the substrate from a nominal geometry or a position error of the substrate; and
determining the pattern desired to be formed on the substrate by modifying a nominal pattern desired to be formed on the substrate according to the distortion and/or position error of the substrate.

3. The method according to claim 2 , wherein converting the representation of the pattern desired to be formed on the substrate into the plurality of area intensity signals includes modifying a nominal pattern desired to be formed on the substrate according to the distortion and/or position error of the substrate.

4. The method according to claim 1 , wherein converting the representation of the pattern desired to be formed on the substrate into the plurality of area intensity signals uses a representation of the distribution of radiation intensity across the substrate derived from each area of the patterning device and determines the radiation intensity levels for each area of the patterning device such that, at each point on the substrate, the sum of the radiation received from each of the areas of the patterning device equals the respective radiation intensity for the point on the substrate in the pattern desired to be formed on the substrate.

5. The method according to claim 4 , wherein the distribution of radiation intensity across the substrate derived from each area of the patterning device that is used is limited to a portion of the substrate surrounding a point on the substrate that corresponds to the center of the area of the patterning device.

6. The method according to claim 1 , wherein converting the area intensity signals into the plurality of control signals takes into account known states of individually controllable elements that are non-responsive to control signals.

7. The method according to claim 1 , wherein converting the area intensity signals into the plurality of control signals comprises selecting from a look-up table for each area intensity signal a corresponding set of control signals for the individually controllable elements in an area of the patterning device.

8. The method according to claim 1 , wherein converting the area intensity signals into the plurality of control signals comprises:
determining for each area of the patterning device, the number of individually controllable elements of the area to be set to the first state in order to provide the desired total radiation intensity at the corresponding portion on the substrate; and
determining the control signals for the individually controllable elements of the area of the patterning device such that the number of individually controllable elements set to the first state are distributed across the area.

9. The method according to claim 8 , wherein the individually controllable elements set to the first state are distributed across the area randomly, pseudo-randomly or evenly.

10. The method of claim 1 , further:
using the patterning device to impart a pattern to a beam of radiation; and
projecting the beam of radiation onto the substrate.

11. A lithographic apparatus, comprising:
a patterning device comprising a plurality of individually controllable elements used to impart a pattern to a beam of radiation;
a projection system, configured to project the beam of radiation onto a substrate; and
a controller, configured to:
convert a representation of a pattern desired to be formed on a substrate into a plurality of area intensity signals, each corresponding to a radiation intensity level to be set in a respective area of the patterning device such that the effect at the substrate of the respective radiation intensity levels being set in each area of the patterning device is the desired pattern;
convert each of the area intensity signals into a plurality of control signals for a respective plurality of individually controllable elements corresponding to the area of the patterning device such that the individually controllable elements are set to appropriate states in order that the combined effect of setting all of the individually controllable elements in the area to the states in use is to provide the radiation intensity level for the area; and
provide the control signals to the individually controllable elements to set the state of each of the individually controllable elements.

12. The lithographic apparatus according to claim 11 , further comprising a sensor configured to inspect the substrate in order to determine distortion of the substrate from a nominal geometry; and
the controller is further configured to determine the pattern desired to be formed on the substrate by modifying a nominal pattern desired to be formed on the substrate according to the distortion of the substrate determined from the sensor.

13. The lithographic apparatus according to claim 11 , wherein the controller is configured such that, when converting a representation of a pattern desired to be formed on a substrate into a plurality of area intensity signals, it uses a representation of the distribution of radiation intensity across the substrate derived from each area of the patterning device and determines the radiation intensity levels for each area of the patterning device such that, at each point on the substrate, the sum of the radiation received from each of the areas of the patterning device equals the respective radiation intensity for the point on the substrate in the pattern desired to be formed on the substrate.

14. The lithographic apparatus according to claim 13 , wherein the distribution of radiation intensity across the substrate derived from each area of the patterning device that is used is limited to a portion of the substrate surrounding a point on the substrate that corresponds to the center of the area of the patterning device.

15. The lithographic apparatus according to claim 11 , wherein the controller is configured to convert the area intensity signals into a plurality of control signals for a respective plurality of individually controllable elements taking into account known states of individually controllable elements that are non-responsive to control signals.

Assignees

• Mulckhuyse Wouter Frans Willem
• De Jager Pieter Willem Herman
• Van Zwet Erwin John
• Asml Netherlands Bv

Inventors

• Mulckhuyse Wouter Frans Willem
• De Jager Pieter Willem Herman
• Van Zwet Erwin John

Classifications

• G03F7/70291

  Addressable masks, e.g. spatial light modulators [SLMs], digital micro-mirror devices [DMDs] or liquid crystal display [LCD] patterning devices · CPC title

• G03F7/70433

  Layout for increasing efficiency or for compensating imaging errors, e.g. layout of exposure fields for reducing focus errors; Use of mask features for increasing efficiency or for compensating imaging errors · CPC title

• G03F7/7055

  Exposure light control in all parts of the microlithographic apparatus, e.g. pulse length control or light interruption · CPC title

• G03F7/70558

  Dose control, i.e. achievement of a desired dose · CPC title

• G03F7/70508 Primary

  Data handling in all parts of the microlithographic apparatus, e.g. handling pattern data for addressable masks or data transfer to or from different components within the exposure apparatus · CPC title