DE102020204722A1 - OPTICAL SYSTEM, LITHOGRAPHY SYSTEM AND METHOD FOR OPERATING AN OPTICAL SYSTEM - Google Patents

Abstract

An optical system (200, 200 ') for a lithography system (100A, 100B) is disclosed, comprising:
an optical element (201);
a plurality of temperature sensors (203) each suitable for detecting a temperature of a region of the optical element (201);
a plurality of Peltier elements (204) which are arranged on the optical element (201), each Peltier element (204) being suitable for being controlled using a respective control signal and the optical element (201) locally as a function of the respective control signal to heat and / or cool;
a control unit (205) for generating the respective control signals as a function of the temperatures detected by the temperature sensors (203); and
a heating / cooling system (207) for dissipating heat to the Peltier elements (204) and / or for dissipating heat from the Peltier elements (204).

Description

The present invention relates to an optical system, a lithography system with such an optical system and a method for operating such an optical system.

Microlithography is used to manufacture microstructured components, such as integrated circuits. The microlithography process is carried out with a lithography system which has an illumination system and a projection system. The image of a mask (reticle) illuminated by means of the illumination system is projected by means of the projection system onto a substrate, for example a silicon wafer, coated with a light-sensitive layer (photoresist) and arranged in the image plane of the projection system, in order to create the mask structure on the light-sensitive coating of the substrate transferred to.

Particularly during the exposure of the wafer, a non-rotationally symmetrical, light-induced heating of an optical element (mirror or lens) of the projection exposure system (also called “projection system”) can occur. This local heating can result in a corresponding, non-rotationally symmetrical expansion of the optical element, as a result of which the imaging quality of the optical element is reduced.

In the case of high demands on the image quality, such as exist in particular in the case of projection exposure methods in microlithography, the heating-based, in particular light-induced, image errors described cannot be tolerated.

One possibility for reducing the aberrations described is to heat and / or cool the optical element in such a way that the temperature and / or the temperature distribution of the optical element remains constant.

In the document DE 10 2010 061 950 A1 the average temperature of a mirror is measured with a measuring beam that is passed through the mirror. Appropriate corrective measures are initiated depending on the average temperature. For this purpose, Peltier elements are used, for example, which are arranged at a distance from the mirror and heat or cool the mirror as a function of the measured average temperature.

Against this background, it is an object of the present invention to provide an improved optical element for a lithography system.

• ein optisches Element;
• mehrere Temperatursensoren, die jeweils geeignet sind, eine Temperatur eines Bereichs des optischen Elements zu erfassen;
• mehrere Peltier-Elemente, die an dem optischen Element angeordnet sind, wobei jedes Peltier-Element geeignet ist, anhand eines jeweiligen Steuersignals angesteuert zu werden und in Abhängigkeit des jeweiligen Steuersignals das optische Element lokal zu erwärmen und/oder zu kühlen;
• eine Steuereinheit zum Erzeugen der jeweiligen Steuersignale in Abhängigkeit der durch die Temperatursensoren erfassten Temperaturen; und
• ein Wärme-/Kühlsystem zur Wärmeabgabe an die Peltier-Elemente und/oder zur Wärmeabfuhr von den Peltier-Elementen.

According to a first aspect, an optical system for a lithography system is proposed. The optical system includes:

• an optical element;
• a plurality of temperature sensors each suitable for detecting a temperature of a region of the optical element;
• a plurality of Peltier elements which are arranged on the optical element, each Peltier element being suitable for being controlled on the basis of a respective control signal and for locally heating and / or cooling the optical element as a function of the respective control signal;
• a control unit for generating the respective control signals as a function of the temperatures detected by the temperature sensors; and
• a heating / cooling system for dissipating heat to the Peltier elements and / or for dissipating heat from the Peltier elements.

Because the Peltier elements are controlled individually by their respective control signals, the Peltier elements can heat and / or cool the optical element independently of one another. The Peltier elements heat and / or cool, in particular, different local areas of the optical element, whereby a local temperature adjustment of the optical element can take place. The temperature of the optical element can thus be regulated in such a way that a constant and / or predetermined temperature distribution is achieved. In particular, deformations of the optical element that arise due to the absorption of the incident light can be compensated.

The optical element can be a mirror or a lens. In particular, the optical element is an optical element for a projection exposure system of a lithography system, for example an EUV (“extreme ultraviolet”) or a DUV (“deep ultraviolet”) lithography system. During the operation of the lithography system, for example during the exposure of the wafer, different amounts of light can be incident on different areas of the optical surface of the optical element and lead to the deformations and undesired optical aberrations already described above.

The temperature sensors can be arranged inside the optical element in order to detect a local internal temperature of the optical element. Each temperature sensor can have one Be assigned area of the optical element and detect a temperature of this area. The individual temperature sensors can be arranged in the vicinity of the respective Peltier elements. For example, a temperature sensor is assigned to each Peltier element. Associated Peltier elements and temperature sensors can be arranged next to one another. The number of Peltier elements can correspond to the number of temperature sensors. However, more Peltier elements than temperature sensors or vice versa can also be provided. A more precise temperature image of the optical element can be recorded with the aid of the multiple temperature sensors. This in turn increases the accuracy with which the control signals can be generated. Overall, the temperature correction can be improved by the Peltier elements.

The temperature sensors and / or the Peltier elements can be arranged distributed over the surface of the mirror at regular intervals. However, they can also be arranged unevenly, for example in order to meet certain technical requirements and / or a certain cooling requirement.

Each of the Peltier elements is an electrothermal transducer which, based on the Peltier effect, generates a temperature difference when a current flows through it. The respective Peltier elements can be used both for cooling and - if the current direction is reversed - for heating. In the present case, heating is used synonymously with warming and in particular denotes a supply of heat. Cooling, on the other hand, means dissipating heat. It is conceivable to control all Peltier elements in such a way that they all heat or all cool. Alternatively, part of the Peltier elements can be controlled for cooling and another part for heating. Furthermore, some Peltier elements can be activated (in particular not activated) in such a way that they neither heat nor cool.

The multiple Peltier elements can also be viewed as a network of Peltier elements. The number of Peltier elements used and the size of the zones assigned to the Peltier elements can take into account the increasing power increase of the light source.

The individual Peltier elements can be controlled individually using the respective control signals and heat and / or cool accordingly. Each Peltier element contains its own control signal. The control signals can be electrical current signals. For example, the Peltier elements can be controlled by being supplied with different amounts of current.

To generate the control signals, the control unit can take into account temperature values recorded by the temperature sensors and / or pre-stored temperature distribution models. The temperature distribution models indicate, for example, the temperature distribution in the optical element if a certain temperature is detected at a certain point (for example in a certain area) in the optical element (or at several points in the optical element). The control signals are generated in particular in such a way that they can control the Peltier elements in such a way that they keep the temperature of the optical element constant in terms of space (based on dimensions of the optical element) and / or time, and / or that they keep the temperature of the Adjust the optical element in spatial (based on dimensions of the optical element) and / or in terms of time to a predetermined temperature profile. The predetermined temperature profile can be a temperature profile that compensates for the imaging error generated by heating on one or more optical elements. The optical system described can compensate for aberrations of several optical elements which are arranged one after the other. It is also conceivable to arrange several optical systems one behind the other in a lithography system.

The heating / cooling system (that is to say heating and / or cooling system) serves in particular to take into account the restricted temperature range within which the Peltier elements can set and maintain a certain temperature. The heating / cooling system can be used to lower the temperature when using the Peltier elements as cooling elements (heat dissipation function of the heating / cooling system). Conversely, the heating / cooling system can be used to increase the temperature (heat addition function of the heating / cooling system). The heating / cooling system is arranged in particular on a rear side of the Peltier elements, that is to say on a side that faces away from the optical element. A single heating / cooling system can be provided for all Peltier elements.

According to one embodiment, the Peltier elements are fastened, in particular glued, on a rear side of the optical element and / or embedded in the rear side of the optical element.

The Peltier elements can be arranged on the optical element in such a way that they are in direct contact with the optical element. Suitable recesses and / or bores, into which the Peltier elements are glued, can be provided in the rear side for insertion into the rear side of the optical element. The The back of the optical element is in particular an optically inactive surface on which no work light falls during the operation of the lithography system. As a rule, it is also sufficient to glue the Peltier elements to the back of the optical element. Instead of being glued on, the Peltier elements can be attached to the optical element, for example by wringing them on.

According to a further embodiment, at least one of the temperature sensors is fastened, in particular glued on, to a rear side of the optical element and / or is arranged within the optical element. Glued-on temperature sensors are, in particular, easier to attach, but detect the temperature within the optical element with less accuracy.

According to a further embodiment, the heating / cooling system comprises a cooling line, in particular a water-cooled line, which runs along a rear side of the Peltier elements, and a cooling capacity of the heating / cooling system along the rear side of the Peltier elements corresponding to a heating / cooling system gradient varies.

The cooling line runs in particular within a base plate and thus cools the rear of the Peltier elements. The back of the Peltier elements is in particular the side that faces away from the optical element. The temperature along the cooling line can vary because the coolant is heated by the dissipation of heat from the Peltier elements (i.e. cold supply to the Peltier elements). The coolant can thus heat up in the direction of flow, which creates a heating / cooling system gradient.

According to a further embodiment, the control unit takes the heating / cooling system gradient into account when generating the control signals. As a result, the correction effect can be improved because the heating and / or cooling by the Peltier elements can take place with increased accuracy.

According to a further embodiment, the control unit generates the control signals such that the Peltier elements locally heat and / or cool the optical element in such a way that a temperature is constant over the entire optical element and / or corresponds to a predetermined temperature profile.

According to a second aspect, a lithography system with an optical system according to the first aspect and / or according to an embodiment of the first aspect is proposed.

• Erfassen einer Temperatur eines optischen Elements mit mehreren Temperatursensoren;
• Erzeugen von Steuersignalen in Abhängigkeit der erfassten Temperaturen;
• Ansteuern von mehreren Peltier-Elementen, die an dem optischen Element angeordnet sind, wobei jedes der Peltier-Elemente anhand eines individuellen Steuersignals angesteuert wird und in Abhängigkeit des Steuersignals das optische Element lokal erwärmt und/oder kühlt; und
• Abgeben von Wärme an die Peltier-Elemente mit einem Wärme-/Kühlsystem und/oder Abführen von Wärme von den Peltier-Elementen mit dem Wärme-/Kühlsystem.

According to a third aspect, a method for operating an optical system for a lithography system, in particular for operating an optical system according to the first aspect and / or according to an embodiment of the first aspect, is proposed. The procedure includes:

• Detecting a temperature of an optical element with a plurality of temperature sensors;
• Generating control signals as a function of the recorded temperatures;
• Controlling a plurality of Peltier elements which are arranged on the optical element, each of the Peltier elements being controlled using an individual control signal and locally heating and / or cooling the optical element as a function of the control signal; and
• Transferring heat to the Peltier elements with a heating / cooling system and / or dissipating heat from the Peltier elements with the heating / cooling system.

• beim Hochfahren der Lithographieanlage, Erwärmen des optischen Elements anhand der Peltier-Elemente derart, dass eine Arbeitstemperatur des optischen Elements erreicht wird; und/oder
• während des Betriebs (insbesondere Produktivbetrieb) der Lithographieanlage, Kühlen und/oder Heizen des optischen Elements anhand der Peltier-Elemente derart, dass Temperaturunterschiede im optischen Element aufgrund der Lichteinstrahlung reduziert werden.

According to one embodiment, the method further comprises:

• when starting up the lithography system, heating the optical element using the Peltier elements in such a way that a working temperature of the optical element is reached; and or
• during operation (in particular productive operation) of the lithography system, cooling and / or heating of the optical element using the Peltier elements in such a way that temperature differences in the optical element due to the light irradiation are reduced.

When the lithography system is started up, the Peltier elements can be used in a warm-up phase for the targeted warm-up of the optical elements. This means that additional heating elements can be omitted. “Startup” means the period immediately preceding productive operation (especially chip manufacture) in which the system is set up accordingly.

The embodiments and features described for the optical system apply accordingly to the proposed lithography system and to the proposed method, and vice versa.

In the present case, “a” is not necessarily to be understood as restricting to exactly one element. Rather, several elements, such as two, three or more, can also be provided. Any other counting word used here is not to be understood as implying a restriction to precisely the specified number of elements given is. Rather, numerical deviations upwards and downwards are possible, unless otherwise stated.

Further possible implementations of the invention also include combinations, not explicitly mentioned, of features or embodiments described above or below with regard to the exemplary embodiments. The person skilled in the art will also add individual aspects as improvements or additions to the respective basic form of the invention.

• 1A zeigt eine schematische Ansicht einer Ausführungsform einer EUV-Lithographieanlage;
• 1B zeigt eine schematische Ansicht einer Ausführungsform einer DUV-Lithographieanlage;
• 2 zeigt ein optisches System für eine Lithographieanlage;
• 3 zeigt eine Draufsicht einer Rückseite eines optischen Elements des optischen Systems gemäß 2;
• 4 zeigt eine Schnittansicht des Wärme-/Kühlsystems; und
• 5 zeigt eine alternative Ausführungsform eines optischen Systems für eine Lithographieanlage.

Further advantageous configurations and aspects of the invention are the subject matter of the subclaims and the exemplary embodiments of the invention described below. In the following, the invention is explained in more detail on the basis of preferred embodiments with reference to the attached figures.

• 1A shows a schematic view of an embodiment of an EUV lithography system;
• 1B shows a schematic view of an embodiment of a DUV lithography system;
• 2 shows an optical system for a lithography system;
• 3 FIG. 13 shows a plan view of a rear side of an optical element of the optical system according to FIG 2 ;
• 4th Figure 3 shows a sectional view of the heating / cooling system; and
• 5 shows an alternative embodiment of an optical system for a lithography system.

In the figures, elements that are the same or have the same function have been provided with the same reference symbols, unless otherwise indicated. It should also be noted that the representations in the figures are not necessarily to scale.

1A shows a schematic view of an EUV lithography system 100A , which is a beam shaping and lighting system 102 and a projection system 104 includes. EUV stands for "extreme ultraviolet" (English: extreme ultraviolet, EUV) and designates a wavelength of work light between 0.1 nm and 30 nm. The beam shaping and lighting system 102 and the projection system 104 are each provided in a vacuum housing, not shown, with each vacuum housing being evacuated with the aid of an evacuation device, not shown. The vacuum housings are surrounded by a machine room, not shown, in which drive devices are provided for mechanically moving or adjusting optical elements. Furthermore, electrical controls and the like can also be provided in this machine room.

The EUV lithography system 100A has an EUV light source 106A on. As an EUV light source 106A For example, a plasma source (or a synchrotron) can be provided, which radiation 108A in the EUV range (extreme ultraviolet range), for example in the wavelength range from 5 nm to 20 nm. In the beam shaping and lighting system 102 becomes the EUV radiation 108A bundled and the desired operating wavelength from the EUV radiation 108A filtered out. The one from the EUV light source 106A generated EUV radiation 108A has a relatively low transmissivity through air, which is why the beam guidance spaces in the beam shaping and lighting system 102 and in the projection system 104 are evacuated.

This in 1A beam shaping and lighting system shown 102 has five mirrors 110 , 112 , 114 , 116 , 118 on. After going through the beam shaping and lighting system 102 becomes the EUV radiation 108A guided onto a photomask (Engl .: reticle) 120. The photo mask 120 is also designed as a reflective optical element and can be used outside of the systems 102 , 104 be arranged. The EUV radiation can continue 108A by means of a mirror 122 on the photo mask 120 be steered. The photo mask 120 has a structure which by means of the projection system 104 scaled down to a wafer 124 or the like is mapped.

The projection system 104 (also known as a projection lens) has six mirrors M1 to M6 for imaging the photomask 120 on the wafer 124 on. Individual mirrors can be used M1 to M6 of the projection system 104 symmetrical about an optical axis 126 of the projection system 104 be arranged. It should be noted that the number of mirrors M1 to M6 the EUV lithography system 100A is not limited to the number shown. There can also be more or less mirrors M1 to M6 be provided. Furthermore are the mirrors M1 to M6 usually curved on their front side to shape the beam.

1B shows a schematic view of a DUV lithography system 100B , which is a beam shaping and lighting system 102 and a projection system 104 includes. DUV stands for "deep ultraviolet" (Engl .: deep ultraviolet, DUV) and designates a wavelength of work light between 30 nm and 250 nm Lighting system 102 and the projection system 104 can - as already with reference to 1A described - be arranged in a vacuum housing and / or surrounded by a machine room with appropriate drive devices.

The DUV lithography system 100B has a DUV light source 106B on. As a DUV light source 106B For example, an ArF excimer laser can be provided, which radiation 108B emitted in the DUV range at 193 nm, for example.

This in 1B beam shaping and lighting system shown 102 directs the DUV radiation 108B on a photo mask 120 . The photo mask 120 is designed as a transmissive optical element and can be used outside of the systems 102 , 104 be arranged. The photo mask 120 has a structure which by means of the projection system 104 scaled down to a wafer 124 or the like is mapped.

The projection system 104 has multiple lenses 128 and / or mirror 130 for imaging the photomask 120 on the wafer 124 on. Individual lenses 128 and / or mirror 130 of the projection system 104 symmetrical about an optical axis 126 of the projection system 104 be arranged. It should be noted that the number of lenses 128 and mirror 130 the DUV lithography system 100B is not limited to the number shown. There can also be more or fewer lenses 128 and / or mirror 130 be provided. Furthermore are the mirrors 130 usually curved on their front side to shape the beam.

An air gap between the last lens 128 and the wafer 124 can through a liquid medium 132 be replaced, which has a refractive index> 1. The liquid medium 132 can for example be ultrapure water. Such a structure is also referred to as immersion lithography and has an increased photolithographic resolution. The medium 132 can also be referred to as immersion liquid.

The 2 shows an optical system 200 for a lithography system 100A , 100B . The optical system 200 includes an optical element 201 . The optical element is, for example, one of those in connection with 1A described mirror 110 , 112 , 114 , 116 , 118 or M1 - M6 the EUV lithography system 100A . Alternatively, however, it can also be a mirror 130 act in a DUV lithography system 100B Applies.

Like in the 2 shown, the mirror points 201 an optically active surface 202 on, on the operation of the lithography system 100A Work light comes in. On a back 209 of the mirror 201 there is an adhesive layer 210 , in the temperature sensors 203 and Peltier elements 204 are embedded. The adhesive layer 210 is formed in particular from a non-electrically conductive, temperature-resistant adhesive.

The 3 shows how the temperature sensors 203 and the Peltier elements 204 are arranged to each other. The temperature sensors 203 and the Peltier elements 204 are each equally spaced across the surface of the mirror 201 arranged distributed across. The temperature sensors 203 are between the Peltier elements 204 arranged.

The Peltier elements 204 are like that in the layer 210 arranged that a top surface 204A a respective Peltier element 204 flat on the back 209 of the mirror 201 is applied. The temperature sensors 203 are also in contact with the back 209 of the mirror 201 .

A lower surface 204B (Back) of the Peltier elements 204 stands with a heating / cooling system 207 in connection. The heating / cooling system 207 includes a water-cooled cooling line 208 that are serpentine beneath the Peltier elements 204 runs. Alternatively, there is also a meandering cooling line 208 conceivable. A sectional view AA of the heating / cooling system 207 is in the 4th shown. A direction of flow of the water (coolant) in the pipe 208 is in the 4th indicated by arrows. An initial temperature of the water in the pipe 208 amounts T ₀ and is a final temperature or exit temperature T _E . A "superimposition" of the 3 and 4th indicates where the line 208 in relation to the Peltier elements 204 and the temperature sensors 203 run away.

The heating / cooling system 207 is used for cooling by the Peltier elements 204 on the back 204B the Peltier elements 204 dissipate transported heat. When heating by the Peltier elements 204 is used by the heating / cooling system 207 also, heat on the back 204B the Peltier elements 204 to provide.

The respective Peltier elements 204 are over lines 206 with a control unit 205 connected to the Peltier elements 204 individually energized. The control unit 205 calculates a control signal as a function of the recorded temperature values and then sends a corresponding power (for example analog or as a pulse duration modulation signal) to the Peltier elements 204 . The control unit 205 controls the Peltier elements 204 individually by using the Peltier elements 204 energized with an adequate current strength as a control signal. The respective Peltier elements 204 heat and / or cool the mirror 201 locally depending on the received control signal. Made by a Peltier element 204 Delivered heat is proportional to the current that the Peltier element 204 flows through.

In the 2 is the interconnection of the control unit 205 , the Peltier elements 204 and the temperature sensors 203 only indicated schematically and is not complete. In particular, the course of the lines 206 in the adhesive layer 210 Not shown. Rather, every temperature sensor is 203 separately with the control unit 205 connected and provides you with the recorded temperature value. In addition, the control unit 205 suitable, depending on the temperature values obtained, the respective control signals for activating the respective Peltier elements 204 to determine. The control unit determines 205 which amount of current to which Peltier element 204 should be delivered to correct the temperature differences.

When determining the control signals by the control unit 205 In addition to the received temperature values, this also takes into account a pre-stored temperature distribution model. The temperature distribution model indicates what temperature the mirror 201 at what point has when a certain temperature through the sensors 203 is captured. Also take into account the control unit 205 the temperature gradient between the initial temperature when determining the control signals T ₀ and the final temperature T _E the line 208 . Either the temperature sensors described above are used for this 203 used, or along the heating / cooling system 207 further temperature sensors arranged.

Current sources supply the control unit in accordance with the specific control signals 205 with the respective Peltier elements 204 are electrically connected to the respective Peltier elements 204 the amount of current required for temperature correction. The Peltier elements 204 heat and / or cool the back 209 of the mirror 201 and thus the entire mirror 201 . This reduces and / or prevents optical aberrations.

The 5 Figure 3 shows an alternative embodiment of an optical system 200 ' for a lithography system 100A , 100B . Instead of the temperature sensors 203 in the adhesive layer 210 the temperature sensors are to be provided 203 here in the mirror 201 embedded. In addition, a more precise temperature detection is made possible. Furthermore, the Peltier elements 204 in recesses 211 on the back side 209 of the mirror 201 intended. As a result, the mirror is heated and / or cooled 201 through the Peltier elements 204 of efficiency.

In the embodiments of 2 to 5 is during the operation of the lithography system 100A , 100B , especially in chip production, with the Peltier elements 204 usually locally cooled in order to heat the mirror 201 to compensate by incident light. By reversing the direction of the current, the Peltier elements 204 However, they can also be heated, for example in the warm-up phase of the lithography system 100A , 100B when starting up the lithography system 100A , 100B is particularly useful.

Although the present invention has been described on the basis of exemplary embodiments, it can be modified in many ways. Instead of the multiple temperature sensors 203 for example, only a single temperature sensor on the optical element 201 be provided.

List of reference symbols

100A

EUV lithography system

100B

DUV lithography system

102

Beam shaping and lighting system

104

Projection system

106A

EUV light source

106B

DUV light source

108A

EUV radiation

108B

DUV radiation

110

mirror

112

mirror

114

mirror

116

mirror

118

mirror

120

Photomask

122

mirror

124

Wafer

126

optical axis

128

lens

130

mirror

132

medium

200

optical system

200 '

optical system

201

optical element

202

optical surface

203

Temperature sensor

204

Peltier element

204A

upper surface

204B

lower surface

205

Control unit

206

management

207

Heating / cooling system

208

Cooling pipe

209

back

210

Adhesive layer

211

Recess

M1

mirror

M2

mirror

M3

mirror

M4

mirror

M5

mirror

M6

mirror

T ₀

Initial temperature

T _E

Final temperature

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• DE 102010061950 A1 [0006]

Claims (9)

Optical system (200, 200 ') for a lithography system (100A, 100B), comprising: an optical element (201); a plurality of temperature sensors (203) each suitable for detecting a temperature of a region of the optical element (201); a plurality of Peltier elements (204) which are arranged on the optical element (201), each Peltier element (204) being suitable for being controlled using a respective control signal and the optical element (201) locally as a function of the respective control signal to heat and / or cool; a control unit (205) for generating the respective control signals as a function of the temperatures detected by the temperature sensors (203); and a heating / cooling system (207) for dissipating heat to the Peltier elements (204) and / or for dissipating heat from the Peltier elements (204). Optical system according to Claim 1 wherein the Peltier elements (204) are fastened, in particular glued, on a rear side (209) of the optical element (201) and / or are embedded in the rear side (209) of the optical element (201). Optical system according to Claim 1 or 2 wherein at least one of the temperature sensors (203) is fastened, in particular glued, on a rear side (209) of the optical element (201) and / or is arranged within the optical element (201). Optical system according to one of the Claims 1 to 3 , wherein the heating / cooling system (207) comprises a cooling line (208), in particular a water-cooled line, which runs along a rear side (204B) of the Peltier elements (204), and wherein a cooling capacity of the heating / cooling system (207 ) varies along the rear side (204B) of the Peltier elements (204) according to a heating / cooling system gradient. Optical system according to Claim 4 , wherein the control unit (205) takes into account the heating / cooling system gradient when generating the control signals. Optical system according to one of the Claims 1 to 5 , wherein the control unit (205) generates the control signals in such a way that the Peltier elements (204) locally heat and / or cool the optical element (201) such that a temperature is constant over the entire optical element (201) and / or corresponds to a predetermined temperature profile. Lithography system (100A, 100B) with an optical system (200, 200 ') according to one of the Claims 1 to 6th . Method for operating an optical system (200, 200 ') for a lithography system (100A, 100B), in particular for operating an optical system (200, 200') according to one of the Claims 1 to 6th comprising: detecting temperatures of regions of an optical element (201) with a plurality of temperature sensors (203); Generating control signals as a function of the recorded temperatures; Controlling a plurality of Peltier elements (204) which are arranged on the optical element (201), each of the Peltier elements (204) being controlled using an individual control signal and locally heating and controlling the optical element (201) as a function of the control signal / or cools; and releasing heat to the Peltier elements (204) with a heating / cooling system (207) and / or removing heat from the Peltier elements (204) with the heating / cooling system (207). Procedure according to Claim 8 , further comprising: when starting up the lithography system, heating the optical element (201) using the Peltier elements (204) in such a way that a working temperature of the optical element is reached; and / or during operation of the lithography system, cooling and / or heating the optical element (201) using the Peltier elements (204) in such a way that temperature differences in the optical element (201) due to the light irradiation are reduced.

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