DE102009045171A1 - Thermally stressed elements tempering device for e.g. illumination system of extreme UV-projection exposure apparatus, has gas chamber provided between thermally stressed and tempering elements, where heat flow takes place between elements - Google Patents

Abstract

The device has tempering elements (10) spatially separated by thermally stressed elements (8) e.g. mechatronic elements, and spaced apart from the thermally stressed elements. A gas chamber (11) is provided between the thermally stressed and tempering elements. The chamber is filled with gas with an adjustable pressure (P). Heat flow takes place between the thermally stressed and tempering elements via the gas by conduction, where the gas has a higher thermal conductivity than air.

Description

The The invention relates to a device for at least approximately contactless or mechanically decoupled cooling of a thermally loaded element. The invention further relates a projection lens and a lighting system, in particular a projection exposure system for microlithography for the manufacture of semiconductor devices in the EUV sector.

at High-performance lenses, such as lighting systems or projection objectives for microlithography Production of semiconductor devices, in particular in the EUV sector, are used, subject to the optical elements used there such as mirror elements and the like, high thermal Loads from the incident light. By a possible Heating of the optical element can its optical properties are changed, so that the imaging properties Overall, the lens generally negatively affected become.

Of Furthermore, as thermally loaded elements also so-called micromechanical Elements, in particular flexible or pivotable micromirrors are known, which in particular in a variety in a field (Multi Mirror Array / MMA) can be arranged. In general, will be the micromechanical elements by a cooling device cooled to reflect changes in the mirror elements to avoid by the heat input.

Out the practice are known cooling systems, which in the direct Contact with the above-mentioned thermally stressed Elements are arranged. These are over in their efficiency the contact pressure and the heat transfer Are defined. The disadvantage here is that unwanted mechanical vibrations can be transferred to the thermally loaded element. Furthermore, especially at different Thermal expansion coefficient (CTE) between cooling element and thermally loaded element set bimetallic effects, which on the thermally stressed, in particular optical, to be cooled Element stresses, drift and surface deformations can contribute. Due to the thermal expansion coefficient to be adjusted stands for the cooling element accordingly only a limited or limited number of materials to disposal. Furthermore, the shape of the cooling element often to the thermally stressed to be cooled Element, which is also not ideal.

About that In addition, cooling systems are known from the prior art, which cooling media, in particular fluids for cooling introduce to the thermally stressed elements or, in particular by means of microchannels via laminar or turbulent flows through the thermally loaded Pass elements through. But you can do that as well unwanted vibration excitations arise.

In the EP 1 376 185 A2 a minimization of thermal impairments of an EUV level is described. In this case, channels are introduced into the main body of a mirror, which are provided with coolant lines.

Furthermore, from the DE 100 50 125 A1 , or from the corresponding US 6,768,600 B2 a device for temperature compensation for thermally stressed bodies of materials of low specific thermal conductivity, in particular for carrier-reflecting layers or substrates in optics, such as in projection lenses for semiconductor lithography, known in which a heat distribution device with one or more heat distribution bodies so on surfaces of the thermal loaded body remains that remains between the thermally stressed body and the heat distribution body, a gap which is filled for the purpose of thermal coupling of thermally stressed body and heat distribution body with simultaneous mechanical decoupling with a fluid.

From the WO 03/086955 A1 Furthermore, a method and a device for operating a micromechanical element is known, wherein the micromechanical element may comprise pivotable micromirrors on a chip. The micromechanical element is cooled by a cooling device, which comprises, for example, a Peltier element, in order to avoid changes in the mirror elements due to the heat input. In order to additionally avoid condensation of moisture from the environment taking place when cooled below a temperature of 10 ° C., the chip with the mirror elements and the Peltier element used for cooling can be enclosed in an airtight housing which is evacuated or is attacked with a dry gas.

The present invention has for its object to provide a device of the type mentioned, which is a transmission of vibrations, excitations or voltages to be cooled thermally loaded element avoids, in addition, an independent in terms of shape and coefficients of thermal expansion optimum material selection for the cooling element is to be made possible.

According to the invention this task by a device temperature, z. B. cooling, a thermally loaded element of an EUV projection exposure system solved, wherein at least one of the thermally loaded Element spatially separated and spaced therefrom, the annealing element, z. B. a cooling element is provided, wherein between the thermally loaded element and the Tempereierelement, z. B. the Cooling element, a gas space is provided, wherein the gas space a gas having an adjustable pressure, and wherein the heat flow between the thermally loaded element and the tempering element, z. B. the cooling element, via the gas by means of conduction he follows.

By the measures according to the invention are on the thermally loaded element transmitted mechanical Vibrations or suggestions, as well as voltages via bimetallic effects by cooling the thermally stressed element required cooling system avoided in an advantageous manner. There is a mechanically decoupled, d. H. (except for the gas) contactless temperature control of the thermally loaded element. It results thus z. B. a decoupled in at least two degrees of freedom Gas cooling system for thermally highly stressed components. Likewise, a corresponding results in two degrees of freedom decoupled gas heating system for thermally highly stressed components. Systems in which the tempering, the tempering, both for heating as well as used for cooling are also possible. Furthermore, one of the coefficients of thermal expansion independent optimal choice of material for the cooler, or the cooling element possible, or for the tempering device. Sonach can be a unit cooler, or a standard cooler can be used, the high Flexibility due not to the geometry of the too Cooling thermally charged element mold to be adapted allowed. The cooling effect takes place within the gas space between thermally loaded element and the cooling element Pressure, d. H. an adjustable, in particular controllable or controllable Partial pressure, creating an uncritical flow rate of the gas flow can be adjusted. Therefore, none occurs Excitation of the thermally loaded element by the gas flow. The Heat transfer takes place by conduction, whereby the smallest possible mass flow is present. One in conventional Solutions existing heat dissipation through Convection is in the present invention Solution not relevant because the mass flow only for generating the required adjustable pressure, or partial pressure is necessary. Partial pressure is understood to mean a pressure in a gas mixture, such as air, a certain Gas can be assigned. It corresponds to the total pressure, the component of the gas mixture when only filling the entire volume. Under conduction is the heat conduction or the heat flow in one Continuum, such as B. in a substantially static gas in a row understood by temperature differences, wherein the heat flow no effective particle flow or mass flow occurs.

Very It is advantageous if the gas is a gas mixture which at least comprises two gases whose respective partial pressures are for Add pressure (P). Furthermore, so that the strength of the heat flow or the cooling capacity over the adjustable partial pressure the gases are regulated.

Of the self-adjusting gas pressure determines the heat transfer and is thus adjustable and can the application or thermal load be adjusted. The gas cooling capacity or the discharged Heat output can be adjusted depending on pressure. The partially controllable cooling capacity can be in an advantageous For example, depending on the aperture or load-dependent to get voted.

According to the invention be provided that the partial pressure and / or the mass flow of the gas via a gas nozzle are adjustable.

Advantageous it is, if as gas a gas with a higher thermal conductivity or with a higher coefficient of thermal conductivity is used as air, in particular helium. Instead of the usual Existing air can be used with a higher gas Thermal conductivity coefficients in particular as air. In addition to helium or hydrogen, of course also other media or gases into consideration.

The thermally loaded element may be an optical element. When optical elements come reflective optical elements such as mirrors or mirror arrays or multi-mirror arrays with a large number smaller adjustable or flexible micromirror into consideration. Of course may also be other optical elements such as apertures or the like be cooled.

The optical element can also be exchangeable and / or interchangeable be.

The inventive decoupled cooling system is especially for regulated and moving components suitable because no contact between the cooling element and consists of the thermally loaded element or the optical element. Changeable, thermally highly stressed components, which are particularly in the Vacuum operated, the cooling circuit during of the change process does not have to be opened, in particular in turret systems, Blendwechslern or the like also with the inventions to the invention cooling system be cooled.

The thermally loaded element can also be a mechatronic element be.

One Projection objective or a lighting system, in particular one Projection exposure machine for microlithography for the production of semiconductor devices in the EUV sector, are in the claims 9 and 10 specified.

advantageous Refinements and developments of the invention will become apparent the dependent claims. Below are based on the drawing in principle embodiments of the Invention specified.

It shows:

1 a basic structure of an EUV projection exposure system with a light source, a lighting system and a projection lens;

2 a schematic representation of a first embodiment of the device according to the invention;

3 a scheme to illustrate the heat conduction in the device according to the invention;

4 a diagram describing the pressure dependence of the hydrogen thermal conductivity;

5 another simplified diagram showing the dependence of the effective thermal conductivity of the pressure;

6 a simplified representation of a second embodiment of a device according to the invention;

7 a simplified representation of a third embodiment of a device according to the invention; and

8th a simplified representation of a fourth embodiment of a device according to the invention.

In 1 is an EUV projection exposure system 1 with a light source 2 , an EUV lighting system 3 for illuminating a field in an object plane 4 in which a structure-carrying mask is arranged, and a projection lens 5 with a housing 6 and a beam path for imaging the structure-bearing mask in the object plane 4 on a photosensitive substrate 7 for the production of semiconductor devices shown. The projection lens 5 indicates beam shaping as a mirror 8th trained optical elements. Also the lighting system 3 has such optical elements for beam shaping or beam line. These are however in 1 not shown in detail.

In 2 is a device according to the invention 9 for contactless cooling of a thermally loaded mirror 8th formed optical element, one of the mirror 8th separated, and spaced from this temperature control element, such. B. a cooling element 10 , is provided, wherein between the thermally loaded mirror 8th and the tempering (the cooling element 10 ) a gas space 11 is provided. In this case, the gas space is designed so that the tempering (cooling element 10 ) spaced from the thermally stressed element (here the mirror 8th ), so that a mechanically approximately contactless, ie mechanically almost decoupled temperature of the element 8th is possible. A possible mechanical coupling of element 8th and tempering element 10 only takes place via a gas within the gas space 11 , Simplified is the distance between thermally loaded element 8th and tempering 10 L (see 3 ), the gas space 11 a gas with an adjustable pressure P has. A between the thermally loaded element 8th (here the mirror 8th ) and the tempering 10 (here the cooling element 10 ) at different temperatures resulting heat flow via the gas invention according to by conduction. In 2 is exemplified as a tempering a cooling element 10 shown, whose temperature is generally lower than the temperature of the mirror 8th , Generally, however, the tempering may also have a temperature which is higher than the temperature of the mirror 8th (of the thermally loaded element), so that then the tempering acts as a heating element. In this case, too, according to the invention, the heat flow between the thermally loaded element and the tempering element at different temperatures is to take place via the gas via conduction.

The one in the gas room 11 adjustable pressure and the distance of the Tempereierelements 10 from the thermally loaded element 8th within limits influence the heat flow. Furthermore, instead of a gas with a pressure P, a gas mixture of at least two gases in the gas space 11 be used. The sum of the partial pressures P _i of the respective gases can result in the pressure P i.

Since, in the case of heat conduction or conduction by means of gases, the occurrence of temperature gradients in the gas often also entails heat by means of convection, the devices according to the present invention are designed such that the heat flow between the thermally stressed element (mirror 8th ) and the tempering (cooling element 10 ) over the gas ( 16 ) by convection and conduction, the convective contribution being less than 0.25 of the contribution of the conduction. The lower the contribution of the heat flow via convection, the lower is the associated mass transport of the gas in the direction from the tempering element to the thermally loaded element or vice versa. As a result, the thermally loaded element is advantageously subjected to only the slightest mechanical influences by any gas flows occurring with the convection. This is especially true for optical elements, such as mirrors 8th in an EUV projection lens 5 an EUV projection exposure system 1 Of particular importance, since there even the smallest forces acting on the mirror, as z. B. may occur due to pressure variations in Konvetion, causing interference in the imaging quality of the projection lens. On the one hand, this is due to the extreme requirements of the mirror shape of often better than 0.5 nm over a mirror diameter of 300 mm and more, so that even small variations in the gas surrounding the mirror in terms of pressure and flow behavior can contribute to the fact that this accuracy can not be achieved is. Likewise, the mirrors must be aligned very precisely relative to each other, with the positioning accuracy in the same range of better than 1 nm. Due to these accuracy requirements, in particular any uncontrolled flows of the gas in the gas space 11 and thus also minimizes the heat flow through convection. Ideally, in the gas room 11 set a pressure P, being dispensed with any gas flow. However, since the mirrors of an EUV projection exposure apparatus are in a vacuum, it is necessary to produce an equilibrium pressure between the pumping of gas and any gaseous impurities and a defined gas inlet of a gas of defined composition, as much as possible during operation of the EUV projection exposure apparatus should be kept constant. This results in a departure from the gas space described as ideal 11 a mass flow of the gas in this gas space, which is adjustable via controllable or controllable gas nozzles, so that the desired gas pressure is established at the lowest possible flow velocities. Preferably, it is adjusted mass flow, that this heat flow between the thermally loaded element 8th and the tempering 10 less than 0.1 of the heat flow through conduction contributes.

The cooling device or device 9 is inside the case 6 of the projection lens 5 arranged (this is in 2 shown schematically). Furthermore, it may also be inside a housing (not shown) of an EUV lighting system 3 be arranged. The strength of the heat flow or the cooling capacity of the cooling element 10 is adjustable via the adjustable pressure P of the gas. If a gas mixture of several gases is used, the partial pressures of the respective gases can be controlled so that they give a total pressure P, but the composition of the gas mixture can vary. Due to the variation of the gas composition, regardless of the pressure P of the gas mixture and the distance L between the thermally loaded element 8th and tempering 10 the heat flow between thermally loaded element and Tempereierele be set ment when z. B. gases are measured with very different thermal conductivity, such. As hydrogen and / or helium with nitrogen. The partial pressure P must also be controlled or regulated for this purpose. By the pressure P of the gas mixture and / or the partial pressures P _i is thus an uncritical flow rate of the gas adjustable, whereby no mechanical stimuli of the mirror 8th and no mirror deformations are caused. The pressure or the partial pressures P, P _i or the mass flow of the gas or of the gas components of the gas mixture is or are via a gas nozzle 12 or adjustable via several gas nozzles. In the present embodiment is used as gas z. B. helium used. However, it is still a variety of other gases or gas mixtures used. Because in the projection lens 5 for operation of the projection exposure apparatus 1 At least approximately a vacuum should be present, the gas or helium must be sucked off again, creating a corresponding circuit. This is in the present embodiment a Device for suction 13 intended. The gas inlet and / or the gas outlet can also z. B. via a labyrinth or the like, so that the mirror 8th not directly exposed to the incoming and / or outflowing gas stream. Basically, it is not a closed room 11 required. The cooling element 10 is z. B. designed as a water cooler and has appropriate water pipes 10a on. How farther 2 can be seen, the cooling element 10 projections 14 on which in returns 15 of the mirror 8th intervene, but always a gas space 11 between mirrors 8th and cooling element 10 remains (simplified). The heat flow between the mirror 8th and the cooling element 10 by conduction through the gas space 11 is indicated by double arrows. The flow of the gas approximately perpendicular to the double arrows is thereby reduced so far that the conditions specified above are satisfied with regard to the convection contribution to the heat flow. Frequently, flow velocities of less than 1 m / s are used. The flow velocity of the gas or the gas mixture is also determined by the length of the flow, or the flow channel, in 2 through the projections and recesses 14 and 15 is formed, and the temperature difference between the thermally stressed element (the mirror 8th ) and the Temperierele element (the radiator 10 ). Flow velocities in the range of 0.01 m / s to 2 m / s are possible, whereby with increasing flow velocity the convection component of the heat flux between mirror 8th and coolers 10 increases, in particular, when an approximately meandering flow channel between mirror 8th (thermally loaded element) and radiator 10 (Temperierelement) is formed, as shown in 2 schematically by the formation of the projections and recesses 14 . 15 is shown.

L

die Länge der Gasspalte

A

die Fläche, durch die die Wärme strömt (L und A sind sogenannte geometrische Parameter) und

K

die effektive Wärmeleitfähigkeit [W/mK] des Gases ist.

3 should clarify the physical principle of the conduction Q or heat conduction as a heat transfer mechanism. The effective thermal conductivity K of the gas or a thermal resistance R (P) between thermally loaded element 8th and cooling element 10 is pressure dependent. The thermal resistance R (P) of the gas column 11 is defined as follows: R (P) = L K (P) · A . in which:

L

the length of the gas column

A

the area through which the heat flows (L and A are so-called geometric parameters) and

K

the effective thermal conductivity [W / mK] of the gas is.

there It is assumed that the mean free path of the Gas molecules and / or gas atoms is greater as the length of the gas column. This is at the low Press in an EUV projection exposure equipment usually given.

The modeling of the gas atmosphere via the gas parameters maximum or to be lowered temperature T _max , cooler temperature T _min , length of the gas column and the pressure P of the gas, or the partial pressures P _{i of} the gases i of the gas mixture.

How farther 3 can be seen, the heat transfer takes place via heat conduction or conduction Q of the mirror 8th with the temperature T _max to the cooling element 10 with the corresponding radiator temperature T _min . The gas space 11 has a distance L.

Gas molecules are greatly simplified 16 shown. In this simplified illustration of the 3 is due to a flow of gas with velocity components in the direction parallel to the surface of the mirror 8th (of the thermally loaded element) and / or omitted perpendicular to the surface of the mirror. The latter can z. B. occur by free convection, first by free and / or forced convection. According to the invention, these speed components are kept in the above-mentioned speed range of 0.01 m / s to 2 m / s or less.

4 shows very schematically the relationship between the thermal conductivity K of hydrogen or for a hydrogen atmosphere and the pressure P. In this case, the thermal conductivity K and on the horizontal axis of the pressure P is plotted on the vertical axis. Gases with a higher thermal conductivity than air are to be preferred. Under atmospheric conditions, hydrogen has a thermal conductivity K of 0.173 W / mK and helium of 0.142 W / mK, while air has only 0.024 W / mK. More quantitatively, the thermal conductivity is a function of the pressure for hydrogen in 5 shown in a double logarithmic representation.

Furthermore, for example, the following gases and any mixtures come into consideration, the bezüg their respective reactions are mixed so that the respective mixture outside their respective reaction limits at the respective temperatures and pressures are: ethane, chloroform, carbon tetrachloride, ethyl alcohol (ethanol), propane, methyl alcohol (methanol), ethylene, nitrous oxide, sulfur dioxide, water, Carbon dioxide, ammonia, methane, nitrogen dioxide, bromine, chlorine, nitrogen monoxide, benzene, fluorine, oxygen, nitrogen, hydrogen, hydrogen chloride, hydrogen bromide, neon, helium, xenon, argon, M-xylene, 1,3-butadiene, good, aniline, Butylene oxide, chlorobenzene, chloroprene, cumene, cyclobutane, cyclohexane, cyclopentane, cyclopropane, ethylbenzene, ethylene oxide, hydrazine, hydrogen fluoride, hydrogen iodide, hydrogen peroxide, iodine, isobutylene, isoprene, methyl chloride, methylene chloride, naphthalene, n-butanol, o-xylene, phenol, Propanol-n, propylene, propylene oxide, p-xylene, styrene, sulfur trioxide and toluene.

How out 4 As can be seen, the relationship between thermal conductivity K and pressure P has been subdivided into three dependency ranges, namely a high-pressure region H, a transition region U and a low-pressure region N, in order to examine the gas as a heat transfer medium. In the low-pressure region N and in the transition region U, the effective thermal conductivity K is proportional to the pressure P, the transition region U being a mixture of low-pressure region N and high-pressure region H with an increase in the viscosity η. A possible operating point in the transition region U is indicated by the square mark M in FIG 5 indicated. This operating point may vary according to the design. The more gas molecules 16 to be added, the greater the effective thermal conductivity K of the gas between the warm and cold surfaces. Thus applies to the dissipated heat output or cooling capacity _N in the low pressure region N and partly in the transition region U: cooling capacity N = P · a · K · (T Max - T min ) A L . where a is the heat transfer between gas and surface (Accommodation Factor).

In the high pressure region H, the thermal conductivity K is a constant value. This is no longer limited by the pressure P, but by the viscosity η. The movement of the gas molecules 16 is due to collisions with neighboring gas molecules 16 prevents, therefore, the thermal conductivity K is not increased by a further increase in pressure. The following applies to the dissipated heat output or cooling capacity _H in the high-pressure region H: cooling capacity H = C · η · C ν * (T Max - T min ) A L where C and C _{ν represent} material constants. In this area, the mean free path of the gas atoms and / or Gasmolekü le is greater than z. B. the length L of the gas column 3 ,

In the transition region U, the conductivity of the gas phase is a combination of the processes in the ranges N and H and is calculated by adding the parallel occurring thermal resistances in the ranges N and H:

6 shows a second embodiment of a device according to the invention 9 ' , These are mirror facets 17 in a mirror version 18 arranged, which in turn in a structure 6 ' is arranged, which is a housing 6 a projection lens 5 or a housing of an EUV lighting system 3 can be. The dash-dotted line 19 indicates a possible but not necessary symmetry axis of the arrangement. The dotted arrows 20 indicate the incident energy radiation. Dashed arrows indicate radiant heat. The solid arrows indicate a thermally conductive compound via hydrogen (H ₂ ) by means of conduction. Between an aperture disc 21 as a thermally loaded element and an aperture frame 22 As a cooling element there is a heat discharge via conduction Q or heat conduction. The structure 6 ' of the bezel frame 22 and the mirror version 18 can for example have a temperature of 23 ° C, wherein the mirror facets 17 and the aperture disc 21 may have a temperature of 45 ° C. Thus, a corresponding heat dissipation can take place.

7 shows a third embodiment of a device according to the invention 9 '' , A structure is denoted by the reference numeral 6 '' provided, which also has a housing 6 a projection lens 5 or a housing of an EUV lighting system 3 can be. Interchangeable or exchangeable orifice plates 21 ' are as thermally loaded elements via bezel frames 22 ' in a removable frame 23 arranged. Between the aperture plate 21 ' and the bezel 22 ' Heat is transferred via Konduk tion Q. The dashed and solid double arrows again show as in 6 the corresponding compounds (in 7 only for the middle elements 21 ' . 22 ' shown). Likewise marked the dot-dashed line 19 the axis of symmetry.

It can also mechatronic components by the invention Device to be cooled.

Of course The cooling elements can also thermally loaded Be elements by means of other cooling elements the device of the invention cooled become.

8th shows a third embodiment of a device according to the invention 9 as a thermally loaded element, a flexible micromirror 24 (Agility by dashes right in 8th indicated) is provided. Furthermore, a cooling element 25 with a gas nozzle 12 ' and a suction device 13 ' intended. The heat transport takes place via the gas molecules 16 , where the unshaded gas molecules 16 a low temperature and the hatched gas molecules 16 according to a through the flexible micromirror 24 have elevated temperature. The heat flow is indicated by a dashed arrow. The solid arrows show greatly simplified the direction of movement of the gas molecules 16 at. The resulting heat flow through convection and conduction is chosen so that the contribution of the convection is less than 0.25 of the contribution of the conduction. This is done by sizing the distance of the gas nozzles to the mirror surface, the gas pressure and the pressure gradient between the gas inlet nozzle 12 ' and the gas suction nozzle 13 ' reached.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - EP 1376185 A2 [0006]
• DE 10050125 A1 [0007]
• - US 6768600 B2 [0007]
• - WO 03/086955 A1 [0008]

Claims (13)

Contraption ( 9 . 9 ' . 9 '' . 9 '' ) for controlling the temperature of a thermally stressed element ( 8th . 21 . 21 ' . 24 ) of an EUV projection exposure apparatus ( 1 ), wherein at least one of the thermally stressed element ( 8th . 21 . 21 ' . 24 ) spatially separated and spaced therefrom tempering ( 10 . 22 . 22 ' . 25 ) is provided, wherein between the thermally loaded element ( 8th . 21 . 21 ' . 24 ) and the tempering element ( 10 . 22 . 22 ' . 25 ) a gas space ( 11 ) is provided, wherein the gas space ( 11 ) a gas ( 16 ) with an adjustable pressure (P), and wherein the heat flow between the thermally stressed element ( 8th . 21 . 21 ' . 24 ) and the tempering element ( 10 . 22 . 22 ' . 25 ) over the gas ( 16 ) by means of conduction (Q). Device according to claim 1, characterized in that that the gas is a gas mixture comprising at least two gases, their respective partial pressures add up to the pressure (P). Apparatus according to claim 1 or 2, characterized in that the heat flow between the thermally loaded element ( 8th . 21 . 21 ' . 24 ) and the tempering element ( 10 . 22 . 22 ' . 25 ) over the gas ( 16 ) by convection and conduction, the convective contribution being less than 0.25 of the contribution of the conduction. Device according to one of claims 1 to 3, characterized in that the heat flow by means of a control or regulating device on the adjustable pressure (P) of the gas ( 16 ) and / or controllable or controllable via at least a partial pressure of a gas of the gas mixture. Device according to one of claims 1 to 4, characterized in that the gas in the gas space has a mass flow through a gas nozzle ( 12 . 12 ' ) is adjustable. Apparatus according to claim 5, characterized in that the mass flow for heat flow between the thermally loaded element ( 8th . 21 . 21 ' . 24 ) and the tempering element ( 10 . 22 . 22 ' . 25 ) contributes less than 0.25 of the heat flux through conduction. Device according to one of claims 1 to 6, characterized in that the gas ( 16 ) has a higher thermal conductivity (K) than air. Device according to one of claims 1 to 7, characterized in that the thermally stressed element is an optical element ( 8th . 21 . 21 ' . 24 ). Device according to Claim 8, characterized in that the optical element has an at least one angle to a radiation beam of adjustable micromirrors (FIG. 24 ). Device according to claim 8 or 9, characterized in that the optical element ( 21 ' ) is interchangeable and / or replaceable. Device according to one of claims 1 to 10, characterized in that thermally stressed element is a mechatronic element ( 21 ' ). Projection lens ( 5 ), an EUV projection exposure machine ( 1 ) for microlithography for the production of semiconductor devices, with several in one housing ( 6 ) arranged optical elements ( 8th ) and with at least one device ( 9 ) for controlling the temperature of a thermally stressed element according to one of claims 1 to 11, by means of which at least one of the optical elements ( 8th ) is heatable and / or coolable as a thermally loaded element. Lighting system ( 3 ) of an EUV projection exposure apparatus ( 1 ) for microlithography for the production of semiconductor devices, with a light source ( 2 ), with several optical elements ( 8th ), for beam shaping of the radiation emitted by the light source and with at least one device for tempering a thermally loaded element according to one of claims 1 to 11, by means of which at least one of the optical elements as a thermally loaded element is heated and / or cooled.