Lithographic apparatus and device manufacturing method

• US 20060119815A1
• Filed: 12/07/2004
• Published: 06/08/2006
• Est. Priority Date: 12/07/2004
• Status: Active Grant

• Current Assignee: ASML Netherlands BV (ASML Holding NV)
• Original Assignee: ASML Netherlands BV (ASML Holding NV)
• Inventors: Franken, Dominicus Jacobus Petrus Adrianus, Troost, Kars Zeger, Hoeks, Martinus Hendricus Hendricus, Tegenbosch, Henricus Gerardus, Box, Wilhelmus Josephus, Kessels, Lambertus Gerardus Maria, Bleeker, Arno Jano
• Granted Patent: US 7,362,415 B2
• Time in Patent Office: Days
• US Class Current: 355/53
• 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 7/70875 Temperature, e.g. temperature control of masks or workpieces via control of stage temperature

Abstract

A system and method are used to allow for compensation of a thermal output of an array of individually controllable elements. This can be done by inputting control signals to the array when it is not being used to pattern a projection beam in order to maintain the temperature of the array. A heating element can be provided to maintain the temperature of the array. A thermal reservoir can be provided to maintain the temperature of the array or a cooling element can be provided to reduce the temperature of the array during use.

Claims

1. A lithographic apparatus comprising:

an illumination system that conditions a beam of radiation;

an array of individually controllable elements that patterns the beam;

a controller that provides pattern control signals to the array of individually controllable elements to impart the pattern; and

a projection system that projects the patterned beam onto a target portion of a substrate,

wherein the controller sends ancillary control signals to at least part of the array of individually controllable elements when no pattern is required to be set on the at least part of the array of individually controllable elements.

2. The apparatus of claim 1, wherein the ancillary control signals are sent to the array of individually controllable elements when no beam of radiation is to be patterned by the array of individually controllable elements.

3. The apparatus of claim 1, wherein:

the pattern control signal includes a pattern signal representing the pattern to be set and an actuate command signal that instructs the array of individually controllable elements to set each of the elements to a required state; and

the ancillary control signals include only the pattern signal.

4. The apparatus of claim 1, further comprising:

a temperature sensor that monitors the temperature of at least part of the array of individually controllable elements, wherein the ancillary control signals are sent to the array of individually controllable elements if the monitored temperature is below a predetermined threshold.

5. A lithographic apparatus, comprising:

an illumination system that conditions a beam of radiation;

an array of individually controllable elements that pattern the beam;

a projection system that projects the patterned beam onto a target portion of a substrate;

a heating element in thermal contact with the array of individually controllable elements; and

a heating controller that controls the heating element.

6. The apparatus of claim 5, wherein the heating controller maintains substantially constant a sum of heat generated by the operation of the array of individually controllable elements and heat generated by the heating element.

7. The apparatus of claim 5, wherein the heating controller determines an amount of heat required to be generated by the heating element by determining heat generated by the array of individually controllable elements from the pattern being generated.

8. The apparatus of claim 5, further comprising:

a temperature sensor that monitors a temperature of at least a part of the array of individually controllable elements, wherein the heating controller controls the heating element, such that the heating element generates heat if the monitored temperature is below a predetermined threshold.

9. The apparatus of claim 5, wherein:

the heating element has a plurality of independently controlled regions in thermal contact with corresponding regions of the array of individually controllable elements; and

the heating controller controls the independently controlled regions of the heating element, such that a sum of heat generated in the independently controlled region of the heating element and heat generated by the corresponding region of the array of individually controllable elements is substantially constant for the regions.

10. The apparatus of claim 5, wherein when the array of individually controllable elements is in operation for a first predetermined time, the heating controller switches off the heating element until a second predetermined time, which is an intended operation duration of the array of the individually controllable elements.

11. A lithographic apparatus comprising:

an illumination system that conditions a beam of radiation;

an array of individually controllable elements that patterns the beam;

a heat reservoir coupled to the array of individually controllable elements; and

a projection system that projects the patterned beam onto a target portion of a substrate, such that

when the array of individually controllable elements generates more heat than an average heat generation in operation, heat is transferred to the thermal reservoir preventing a temperature of the array of individually controllable elements from rising above a first predetermined level and,

when the array of individually controllable elements generates less heat that an average heat generation in operation, heat is transferred from the thermal reservoir to the array of individually controllable elements preventing the temperature of the array of individually controllable elements from falling below a second predetermined level.

12. The apparatus of claim 11, wherein the thermal reservoir is bonded to an opposite side of the array of individually controllable elements than a side on which the beam is incident, such that each part of the array of individually controllable elements that supports an individually controllable element is directly bonded to the thermal reservoir.

13. The apparatus of claim 11, wherein the thermal reservoir comprises a plate made from at least one of aluminum and a low expansion material.

14. The apparatus of claim 11, wherein the low expansion material comprises one of INVAR™

, ZERODUR™

, and ULE™

.

15. The apparatus of claim 11, wherein the thermal reservoir comprises a chamber substantially filled with fluid.

16. The apparatus of claim 11, wherein the thermal reservoir is thermally coupled to at least one of:

a temperature controlled heating element that is activated if the temperature of the thermal reservoir falls below a third predetermined level; and

a temperature controlled cooling element that is activated if the temperature of the thermal reservoir exceeds a fourth predetermined level.

17. A lithographic apparatus, comprising:

an illumination system that conditions a beam of radiation;

an array of individually controllable elements that pattern the beam;

a projection system that projects the patterned beam onto a target portion of a substrate;

a cooling element that is in thermal contact with the array of individually controllable elements; and

a cooling controller that controls the cooling element.

18. The apparatus of claim 17, wherein the cooling controller determines heat generated by the array of individually controllable elements from the pattern being generated and controls the cooling element to absorb a corresponding amount of heat from the array of individually controllable elements.

19. The apparatus of claim 17, further comprising:

a temperature sensor that monitors the temperature of the array of individually controllable elements, wherein the cooling controller determines an amount of heat to be absorbed from the array of individually controllable elements by the cooling element based on the monitored temperature and controls the cooling element to absorb the heat.

20. The apparatus of claim 17, wherein the cooling element provides independent control of the heat absorbed from a plurality of regions of the array of individually controllable elements.

21. The apparatus of claim 17, wherein the cooling element comprises:

at least one conduit in thermal contact with the array of individually controllable elements through which a fluid can flow; and

a fluid cooling unit connected to the at least one conduit that cools the fluid.

22. The apparatus of claim 21, wherein the cooling element comprises:

a first one of the conduits arranged such that, along the length of the first conduit in the direction of the fluid flow in the first conduit, the first conduit is sequentially in thermal contact with at least one of a plurality of regions of the array of individually controllable elements and a plurality of independent arrays of individually controllable elements in a first order; and

a second one of the conduits arranged such that, along the length of the second conduit in the direction of the fluid flow in the second conduit, the second conduit is sequentially in thermal contact with at least one of a plurality of regions of the array of individually controllable elements and a plurality of independent arrays of individually controllable elements in a second order, different from the first order.

25. The apparatus of claim 21, wherein the cooling element comprises:

a plurality of the fluid-containing conduits, each connected to an independently-controlled fluid cooling unit.

26. The apparatus of claim 21, wherein the cooling element comprises:

at least one of the cooling conduits, such that along the length of the conduit in the direction of the fluid flow, the conduit is in thermal contact with at least one of a plurality of regions of the array of individually controllable elements a plurality of independent arrays of individually controllable elements initially in a first order and then, again, in a second order, different from the first order.

27. The apparatus of claim 26, wherein the second order is the reverse of the first order.

23. The apparatus of claim 23, wherein the plurality of regions of the array of individually controllable elements and the plurality of independent arrays of individually controllable elements to which the first conduit is attached is the same as the plurality of regions of the array of individually controllable elements and the plurality of independent arrays of individually controllable elements to which the second conduit is attached.

24. The apparatus of claim 23, wherein the second order is reverse of the first order.

28. A device manufacturing method, comprising:

providing pattern control signals to an array of individually controllable elements to set the elements to pattern a beam of radiation;

providing ancillary control signals to at least part of the array of individually controllable elements to which no pattern is being; and

projecting the patterned beam of radiation onto a target portion of a substrate.

29. A device manufacturing method, comprising:

using an array of individually controllable elements to pattern a beam of radiation;

projecting the patterned beam of radiation onto a target portion of a substrate; and

providing heat to the array of individually controllable elements using a heating element in thermal contact with the array of individually controllable elements and controlled by an associated heating controller.

30. A device manufacturing method, comprising:

using an array of individually controllable elements to pattern a beam of radiation;

projecting the patterned beam of radiation onto a target portion of the substrate;

thermally coupling the array of individually controllable elements to a thermal reservoir having a heat capacity selected such that,

when the array of individually controllable elements generates more heat than an average heat generation in operation, heat is transferred to the thermal reservoir preventing a temperature of the array of individually controllable elements from rising above a first predetermined level and,

when the array of individually controllable elements generates less heat that an average heat generation in operation, heat is transferred from the thermal reservoir to the array of individually controllable elements preventing the temperature of the array of individually controllable elements from falling below a second predetermined level.

31. A device manufacturing method, comprising:

using an array of individually controllable elements to pattern a beam of radiation;

projecting the patterned beam of radiation onto a target portion of a substrate; and

absorbing heat from the array of individually controllable elements using a cooling element in thermal contact with the array of individually controllable elements and controlled by an associated cooling controller.