Method and device for determining the heating state of a mirror in an optical system
AssigneeCarl Zeiss SMT GmbH
InventorsWillem Michiel De Rapper, Toralf Gruner
Life of this patent
Estimating the term…
Abstract
The disclosure provides a method and to an apparatus for determining the heating state of a mirror in an optical system, in particular in a microlithographic projection exposure apparatus. A method for determining the heating state of an optical element includes: measuring values of a first temperature that the optical element has at a first position using a temperature sensor; and estimating a second temperature that the optical element has at a second position, which is located at a distance from the first position, on the basis of the measured values, wherein estimating the second temperature is accomplished while taking into account a temporal change in the previously measured values.
Claims20
A method of estimating a temperature of an incidence surface of an optical element in a microlithographic projection exposure apparatus, the optical element comprising a substrate supporting the incidence surface, the optical element having a channel extending into the substrate from a side of the optical element facing away from the incidence surface, the channel having a channel surface located a distance from the incidence surface, the method comprising:
- a) using a temperature sensor to measure values of a temperature of the channel surface, the temperature sensor being in direct contact with the channel surface;
- and
- b) based on the values measured in a) and taking into account a temporal change in the values measured in a), estimating the temperature of the incidence surface,
- wherein during use of the optical element, electromagnetic radiation impinges on the incidence surface, and
- wherein estimating the temperature of the incidence surface comprises using an equation which comprises the term
- p
-
- (
- ∂
- T
- Sensor
- ∂
- t
- )
- q
- ,
- and wherein Tsensor is a temperature value measured by the temperature sensor, t is time, and p and q are fit parameters.
A method of estimating a temperature of an incidence surface of an optical element in a microlithographic projection exposure apparatus, the optical element comprising a substrate supporting the incidence surface, the optical element having a channel extending into the substrate from a side of the optical element facing away from the incidence surface, the channel having a channel surface located a distance from the incidence surface, the method comprising:
- a) using a temperature sensor to measure values of a temperature of the channel surface, the temperature sensor being in direct contact with the channel surface;
- and
- b) based on the values measured in a) and taking into account a temporal change in the values measured in a), estimating the temperature of the incidence surface,
- wherein during use of the optical element, electromagnetic radiation impinges on the incidence surface), and
- wherein estimating the temperature of the incidence surface comprises using an equation which comprises the term
- p
-
- ∫
- -
- ∞
- t
-
- d
-
-
- τ
-
- (
- ∂
- T
- Sensor
- ∂
- t
- )
- q
-
- e
- -
- ∞
-
- (
- t
- -
- τ
- )
- ,
- and wherein Tsensor is a temperature value measured by the temperature sensor, t is time, τ is a point in time, α represents a decay constant, and p and q are fit parameters.
Dependencies are inferred from the claim text.