DE102023205525B3 - Method for tempering an optical element, projection exposure system and method for determining an optimized temperature profile of an optical element - Google Patents

Abstract

Shown and described is a method for tempering an optical element (10) for microlithography, comprising the following steps: 1a) providing at least one temperable optical element (10) for microlithography, wherein the optical element (10) has a plurality of temperable zones (12), wherein a portion of the temperable zones (12) is arranged in an optically used region (OGB) of the optical element (10), and wherein a portion of the temperable zones (12) is arranged in an optically unused region (OUB) of the optical element, 2a) tempering the optical element (10), wherein at least a portion of the temperable zones (12) is tempered in the optically used region (OGB), in a first section (OUB1) of the optically unused region (OUB) and/or in a second section (OUB2) of the optically unused region (OUB). In order to achieve a more extensive and/or more energy-efficient influence on the radiation, it is proposed that in step 2a) in the second section (OUB2) of the optically unused area (OUB) at least some of the temperature-controlled zones (12) do not have the same temperature as at least another part of the temperature-controlled zones (12) in the second section (OUB2) of the optically unused area (OUB) and/or as at least some of the temperature-controlled zones (12) in the first section (OUB1) of the optically unused area (OUB).

Description

The present invention relates to a method for tempering an optical element for microlithography, comprising the following steps: 1a) providing at least one temperable optical element for microlithography, wherein the optical element has a plurality of temperable zones, wherein some of the temperable zones are arranged in an optically used region of the optical element, and wherein some of the temperable zones are arranged in an optically unused region of the optical element, 2a) tempering the optical element, wherein at least some of the temperable zones are tempered in the optically used region, in a first section of the optically unused region and/or in a second section of the optically unused region.

The present invention further relates to a projection exposure system.

The present invention further relates to a method for determining an optimized temperature profile of an optical element for microlithography, comprising the following steps: 1b) Providing an initial temperature profile of an optical element for microlithography, wherein the optical element has a plurality of temperature-controlled zones, wherein a portion of the temperature-controlled zones is arranged in an optically used region of the optical element, wherein a portion of the temperature-controlled zones is arranged in an optically unused region of the optical element, wherein the initial temperature profile for at least a portion of the temperature-controlled zones comprises a respective initial target temperature, and wherein an initial temperature control power is required in order to set the initial temperature profile, 2b) Determining an optimized temperature profile of the optical element based on the initial temperature profile by means of an optimization method, wherein the optimized temperature profile for at least a portion of the temperature-controlled zones comprises a respective optimized target temperature, wherein an optimized temperature control power is required in order to set the optimized temperature profile, wherein for at least a portion of the temperature-controlled zones in the optically used area, the respective target temperature for the optimized temperature profile remains unchanged compared to the respective target temperature of the initial temperature profile, wherein for at least some of the temperature-controlled zones in the optically unused area, the respective target temperature for the optimized temperature profile is changed compared to the respective target temperature of the initial temperature profile.

The present invention further relates to a device for data processing.

The present invention further relates to a computer program.

The present invention further relates to a computer-readable medium.

Microlithography is used to produce microstructured components, such as integrated circuits. The microlithography process is carried out, for example, with a projection exposure system which, among other things, has an illumination system, in particular illumination optics, and/or a projection system, in particular projection optics. The structure of a mask (reticle) exposed by means of the illumination optics is projected by means of the projection optics onto a substrate coated with a light-sensitive layer (photoresist) and arranged in the image plane of the projection optics, for example a wafer, in particular a silicon wafer, in order to transfer the mask structure onto the light-sensitive coating of the substrate.

One of the goals in the development of projection exposure systems is to lithographically produce structures with increasingly smaller dimensions on the substrate, for example in order to achieve higher integration densities in semiconductor components. One approach is to work with shorter wavelengths of electromagnetic radiation. For example, optical systems have been developed that use electromagnetic radiation from the so-called "deep ultraviolet" range (DUV), in particular with working wavelengths in the range between 150 nm and 400 nm, in particular 365 nm, 248 nm or 193 nm, or from the extreme ultraviolet range (EUV), in particular with working wavelengths in the range between 5 nm and 30 nm, in particular at 13.5 nm.

In order to influence the radiation during the microlithography process, for example to correct imaging errors, it is known to manipulate optical elements of the projection exposure system. The manipulation of the optical elements can be carried out, for example, by tempering, i.e. heating and/or cooling, the respective optical element. The tempering can then lead to a change in the refractive index and to a deformation of the optical element, whereby the change in the refractive index and the deformation of the optical element influence the radiation and thus in turn lead to a certain optical effect. The tempering can take place in and/or by means of a large number of temperable zones.

In such manipulation, it has previously been common practice to set a temperature profile in which a reference temperature is essentially kept constant in the optically unused area, in particular in order not to influence adjacent components of the projection exposure system. In the optically used area, temperatures deviating from the reference temperature were set at least in sections in order to achieve the desired influence on the radiation. This often resulted in a clear and strict demarcation in the respective prevailing temperatures between the optically used area and the optically unused area.

However, the disadvantage is that such a clear and strict demarcation of the prevailing temperatures in the transition between the optically used area and the optically unused area requires a high temperature control power. If, for example, the optically used area adjacent to the optically unused area is heated up to a high degree, the adjacent optically unused area must be cooled accordingly due to heat transfer, in particular heat conduction, between the individual temperature-controlled zones in order to maintain the reference temperature in the optically unused area. On the one hand, this is not optimal in terms of energy or power efficiency, since large amounts of energy or power are required for temperature control according to the previously usual temperature profiles. On the other hand, such a temperature profile means that the optically unused area must always have sufficient temperature control power available to keep the reference temperature constant, whereby this temperature control power cannot then be made available to the optically used area for manipulating the optical element and thus influencing the radiation. With such a limited temperature profile, more extensive manipulation is often only possible by adjusting the optical element and/or the projection exposure system.

The state of the art is the EN 10 2019 202 531 A1 which discloses an optical correction element, a projection exposure system for semiconductor lithography with a correction element and a method for designing a correction element.

Furthermore, the state of the art shows that EN 10 2019 217 185 A1 which discloses a projection exposure system for semiconductor lithography.

In addition, the state of the art EN 10 2011 005 778 A1 which discloses an optical element.

In addition, the state of the art US 2003/ 0 169 520 A1 which discloses a mirror assembly with thermal contour control.

Against this background, the present invention is based on the object of designing and developing a method for tempering an optical element for microlithography, a projection exposure system, a method for determining an optimized temperature profile of an optical element for microlithography, a device for data processing, a computer program and a computer-readable medium in such a way that a more extensive and/or more energy-efficient influence on the radiation can take place.

The above-mentioned object is achieved in the method for tempering an optical element for microlithography in that in step 2a) in the second section of the optically unused region at least some of the temperable zones do not have the same temperature as at least another part of the temperable zones in the second section of the optically unused region and/or as at least some of the temperable zones in the first section of the optically unused region.

The method for tempering an optical element for microlithography initially comprises the following step: 1a) Providing at least one temperable optical element for microlithography. The optical element is intended for use in a projection exposure system, in particular to influence the radiation used when exposing a substrate. The optical element can comprise at least one lens and/or at least one mirror, in particular be designed as a lens and/or mirror. The optical element can alternatively or additionally be a plane-parallel and/or at least partially transparent plate. The optical element can be tempered by a tempering device. The optical element can comprise a tempering device for this purpose and/or interact with a tempering device. The tempering device can comprise at least one tempering element, for example a heating element and/or a cooling element. The tempering element can be connected to the optical element at least in sections and/or embedded in the optical element at least in sections.

The term “tempering” in the present disclosure means heating and/or cooling. A temperable optical Element can therefore be heated and/or cooled.

Furthermore, it is provided that the optical element has a plurality of temperature-controlled zones. The provision of temperature-controlled zones makes it easier to specifically adjust the temperature at different points on the optical element. It is advantageously provided that the temperature-controlled zones can each be individually and/or independently of one another. The temperature-controlled zones can be arranged at least along one surface of the optical element. It can be provided that at least some of the, in particular essentially all, temperature-controlled zones are in contact with and/or connected to the temperature control device. Alternatively or additionally, it can be provided that at least some of the temperature control device is embedded in at least some of the, in particular essentially all, temperature-controlled zones.

In addition, it is provided that some of the temperature-controlled zones are arranged in an optically used area of the optical element. The radiation intended for exposure can be influenced by appropriately arranged temperature-controlled zones. In particular, imaging errors that occur during exposure in a projection exposure system can be corrected by influencing the radiation. The optically used area is often also referred to as the optically free area and describes in particular the area to and/or through which the radiation intended for exposure is directed when the optical element is used in a projection exposure system, preferably during exposure of a substrate.

It is also provided that some of the temperature-controlled zones are arranged in an optically unused area of the optical element. The optically unused area describes in particular the area to and/or through which the radiation intended for exposure is not guided when the optical element is used in a projection exposure system, preferably during exposure of a substrate. The optically unused area and the optically used area are preferably arranged at least in sections in the same plane and/or at least in sections on the same side of the optical element.

By means of appropriately arranged temperature-controlled zones, it is possible to prevent or at least counteract the fact that components of a projection exposure system adjacent to the optical element are influenced by the temperature control of the optically used area. This is preferably achieved by at least partially controlling the temperature-controlled zones in the optically unused area to a reference temperature.

The method for tempering an optical element for microlithography also includes the following step: 2a) Tempering the optical element. Tempering achieves the effects that were already explained for the temperable zones in the optically used area and the optically unused area.

It is further provided that at least some of the temperature-controlled zones in the optically used area, in a first section of the optically unused area and/or in a second section of the optically unused area are temperature-controlled. By temperature-controlling the optically used area, influencing the radiation intended for exposure is made easier. By temperature-controlling the optically unused area, the temperature outside the optically used area can be set to desired temperatures, which will be discussed below. The optically unused area can have further sections in addition to the first section and the second section. Preferably, however, it is provided that the optically unused area consists only of the first section and the second section.

According to the method, it is also provided that in step 2a) in the second section of the optically unused area at least some of the temperature-controlled zones do not have the same temperature as at least another part of the temperature-controlled zones in the second section of the optically unused area and/or as at least some of the temperature-controlled zones in the first section of the optically unused area. As a result, the same, preferably essentially constant, temperature, for example reference temperature, is no longer present everywhere in the optically unused area. This in turn ensures that the demarcation between the optically used area and the optically unused area is less clear and strict, at least with regard to the prevailing temperatures, and instead there is preferably a more fluid transition. In the optically unused area adjacent to the optically used area, strong counter-temperature control as was previously usual is therefore no longer necessary, so that the required temperature control power of the entire optical element is reduced. More energy-efficient use is therefore possible. In addition, temperature profiles can be implemented that require more temperature control in the optically used area than previously possible. This can also be used to simplify the manufacture of the optical element. Due to the tempering power that can now additionally be made available to the optically used area, the radiation intended for exposure can be influenced to an extent that could not previously be achieved or could only be achieved with an adapted structural design of the optical element. Advantageously, it can be provided that in step 2a) in the second section of the optically unused area at least some of the temperable zones are not tempered to the same temperature as at least another part of the temperable zones in the second section of the optically unused area and/or as at least some of the temperable zones in the first section of the optically unused area. Appropriate tempering further simplifies the fact that there is a more fluid transition between the optically used area and the optically unused area.

A "temperature profile" in the present disclosure preferably comprises a respective target temperature for at least some, in particular essentially all, temperature-controlled zones. The respective target temperature is the temperature to which the respective temperature-controlled zone is to be tempered. The target temperature can, for example, indicate an absolute temperature or the difference to a comparison temperature, preferably the reference temperature.

In the present disclosure, the term "temperature control power" is preferably understood to mean the power used for temperature control, in particular of the respective temperature-controlled zones, preferably in order to achieve one or more specific target temperatures and/or a specific temperature profile. The temperature control power can be, for example, heating power and/or cooling power.

In one embodiment of the method for tempering an optical element for microlithography, it is provided that in step 2a) in the first section of the optically unused region at least some of the temperable zones are tempered to a reference temperature, that in step 2a) in the second section of the optically unused region at least some of the temperable zones do not have the reference temperature, that in step 2a) in the second section of the optically unused region at least some of the temperable zones are tempered to at least one temperature deviating from the reference temperature and/or to different temperatures and/or that in step 2a) in the optically used region at least some of the temperable zones are tempered to at least one temperature deviating from the reference temperature and/or to different temperatures.

By appropriately controlling the temperature of the first section of the optically unused area, it is made easier for components of a projection exposure system adjacent to the optical element to not be influenced, or at least only to a small extent, by the temperature control of the optically used area and/or the second section of the optically unused area. It is therefore advisable to arrange the first section of the optically unused area in particular where the optical element can come into contact with other components, in particular where it can be connected to other components. For example, the first section of the optically unused area can be arranged adjacent to sensors connected to the optical element in order not to influence the function of the sensors. It can advantageously be provided that in the first section of the optically unused area, essentially all temperature-controlled zones are tempered to the reference temperature. This makes it easier for other components not to be influenced by the temperature control of the optically used area. The reference temperature is in particular a substantially constant and/or predetermined temperature.

Appropriate temperature control in the second section of the optically unused area simplifies the demarcation between the optically used area and the optically unused area, at least with regard to the prevailing temperatures, so that a more fluid transition is preferably present. Temperature control makes it easier to reach and maintain the appropriate temperature. In the second section of the optically unused area, essentially all temperature-controlled zones cannot have the reference temperature. However, there may be temperature profiles in which it is sensible for some zones in the second section of the optically unused area to also have a reference temperature. It can be provided that in the second section of the optically unused area, at least some of the temperature-controlled zones are each individually temperature-controlled to at least one temperature deviating from the reference temperature and/or to different temperatures from one another. Alternatively or additionally, it can be provided, for example, to temperature-control essentially all temperature-controlled zones in the second section of the optically unused area to at least one temperature deviating from the reference temperature. However, there may be temperature profiles where it is useful to also to temper some zones in the second section to reference temperature. By appropriately tempering the optically used area, the desired influence on the radiation intended for exposure is simplified.

In one embodiment of the method for tempering an optical element for microlithography, it is provided that in step 2a) the optical element is tempered in such a way that the temperature deviation from the reference temperature averaged over at least some, preferably essentially all, temperable zones is below a predetermined threshold value. This makes it easy to limit the energy input into the optical element, in particular the entire system. This in turn makes it easier for components of a projection exposure system adjacent to the optical element to not be influenced, or at least only to a small extent, by the tempering of the optically used area.

In one embodiment of the method for tempering an optical element for microlithography, it is provided that the optically unused region is arranged at least in sections on the edge of the optical element, in particular at least in sections along the edge of the optical element, and/or that the first section of the optically unused region is arranged at least in sections on the edge of the optical element, in particular at least in sections along the edge of the optical element. This prevents or at least counteracts components adjacent to the optical element from being influenced by the tempering of the optically used region. The optically unused region and/or the first section of the optically unused region can advantageously be arranged essentially completely along the edge of the optical element. This further enhances the aforementioned effect.

In one embodiment of the method for tempering an optical element for microlithography, it is provided that the second section of the optically unused region is arranged at least in sections between the first section of the optically unused region and the optically used region and/or the optically used region is arranged at least in sections in the middle of the optical element. By arranging the second section of the optically unused region between the first section of the optically unused region and the optically used region, it is further simplified that the demarcation between the optically used region and the optically unused region is less clear and strict, at least with regard to the prevailing temperatures, but rather there is preferably a more fluid transition. The arrangement of the optically used region in the middle of the optical element in turn simplifies the arrangement of the optical element, in particular the optically used region, in a projection exposure system. On the other hand, it is simplified that adjacent components of the projection exposure system are not influenced by the temperature control, since with a central arrangement there is sufficient space at the edges of the optical element for the optically unused area, in particular the first section of the optically unused area. Advantageously, it can be provided that the optically used area is surrounded by the first section of the optically unused area and/or the second section of the optically unused area at least in sections, in particular essentially completely. This further simplifies a more fluid transition between the different areas, at least with regard to the prevailing temperatures.

The aforementioned object is further achieved by a projection exposure system for microlithography comprising: at least one temperature-controlled optical element, and a controller, wherein the optical element and/or the controller is set up to carry out the method according to one of claims 1 to 5. The projection exposure system can also comprise a radiation source, an illumination system, in particular comprising illumination optics, a projection system, in particular comprising projection optics, and/or a substrate holder, also called a wafer holder. The temperature-controlled zones can preferably be arranged distributed over a cross-section of the beam path of the projection exposure system, in particular the projection optics.

The aforementioned object is further achieved by the method for determining an optimized temperature profile of an optical element for microlithography.

The statements on the method for tempering an optical element for microlithography and on the projection exposure system can be transferred to the method for determining an optimized temperature profile of an optical element for microlithography and vice versa.

The method for determining an optimized temperature profile of an optical element for microlithography initially comprises the following step: 1b) Providing an initial temperature profile of an optical element for microlithography. Temperature profiles may already be known for tempering a corresponding optical element. However, these temperature profiles are usually designed for a clear and strict demarcation in the prevailing temperatures between the optically used area and the optically unused area. The initial temperature profile can represent such a temperature profile.

It is further provided that the optical element has a plurality of temperature-controlled zones, that some of the temperature-controlled zones are arranged in an optically used region of the optical element and that some of the temperature-controlled zones are arranged in an optically unused region of the optical element. With regard to these features, reference is made to the corresponding statements on the method for temperature control of an optical element for microlithography, whereby these statements can be transferred here accordingly. It is also provided that the initial temperature profile for at least some of the temperature-controlled zones includes a respective initial target temperature. The respective initial target temperature is the respective target temperature of the initial temperature profile. The initial temperature profile can preferably include a respective initial target temperature for essentially all temperature-controlled zones. This simplifies targeted and comprehensive temperature control of the optical element.

It is also intended that an initial tempering power is required to set the initial temperature profile. The initial temperature profile is set in particular on the optical element by tempering the optical element, in particular by means of the initial tempering power.

The method for determining an optimized temperature profile of an optical element for microlithography also includes the following step: 2b) Determining an optimized temperature profile of the optical element based on the initial temperature profile using an optimization method. This achieves a more comprehensive and energy-efficient influence on the radiation. The optimized temperature profile is determined based on the initial temperature profile and retains some of the properties of the initial temperature profile, in particular in the optically used area, as will be explained below.

It is also provided that the optimized temperature profile includes a respective optimized target temperature for at least some of the temperature-controlled zones. The respective optimized target temperature is the respective target temperature of the optimized temperature profile. The optimized temperature profile can preferably include a respective optimized target temperature for essentially all temperature-controlled zones. This simplifies targeted and comprehensive temperature control of the optical element. Alternatively or additionally, the initial temperature profile and/or the optimized temperature profile can include a corresponding target temperature for at least some of the same, in particular the same, temperature-controlled zones.

It is also intended that an optimized temperature control performance is required in order to set the optimized temperature profile. The optimized temperature profile is set in particular on the optical element by tempering the optical element, in particular by means of the optimized temperature control performance.

It is further provided that for at least some of the temperature-controlled zones in the optically used area, the respective target temperature for the optimized temperature profile remains unchanged compared to the respective target temperature of the initial temperature profile. This ensures that the influence of the radiation intended for exposure by the optimized temperature profile is not changed or only slightly changed. It is advantageously provided that for essentially all temperature-controlled zones in the optically used area, the respective target temperature for the optimized temperature profile remains unchanged compared to the respective target temperature of the initial temperature profile.

It is also intended that for at least some of the temperature-controlled zones in the optically unused area, the respective target temperature for the optimized temperature profile is changed compared to the respective target temperature of the initial temperature profile. This is intended to determine a temperature profile with a rather smooth transition between the different areas, at least with regard to the prevailing temperatures.

After carrying out step 2b), the target temperature of the optimized temperature profile is thus unchanged compared to the respective target temperature of the initial temperature profile for at least some of the temperature-controlled zones in the optically used area, and the respective target temperature of the optimized temperature profile is unchanged compared to the respective set temperature of the initial temperature profile.

1. a) Für wenigstens einen Teil der temperierbaren Zonen, insbesondere alle temperierbaren Zonen, in dem optisch genutzten Bereich bleibt die jeweilige Solltemperatur für das optimierte Temperaturprofil gegenüber der jeweiligen Solltemperatur des initialen Temperaturprofils unverändert,
2. b) für wenigstens einen Teil der temperierbaren Zonen, insbesondere alle temperierbaren Zonen, in einem ersten Abschnitt des optisch ungenutzten Bereichs entspricht die jeweilige Solltemperatur für das optimierte Temperaturprofil der Referenztemperatur und/oder bleibt die jeweilige Solltemperatur für das optimierte Temperaturprofil gegenüber der Referenztemperatur unverändert, und/oder
3. c) die über wenigstens einen Teil der temperierbaren Zonen, insbesondere im Wesentlichen alle temperierbaren Zonen, gemittelte Temperaturabweichung zur Referenztemperatur unterhalb eines vorgegebenen Schwellwerts liegt.

The optimization method can be a mathematical optimization. The optimization method can include determining a model (M), wherein the model (M) describes the relationship between the temperature control of the temperature-controlled zones and the thermal behavior of the optical element. The model (M) calculates the temperature control performance, in particular the cooling performance and/or heating performance, of at least a portion of the, in particular essentially all, temperature-controlled zones that is required to achieve a temperature profile (x), in particular using at least one thermal property, such as the thermal conductivity, of the material used for the temperature-controlled zones and/or the optical element. The temperature or temperatures of the respective temperature profile can be specified absolutely, as a difference from the reference temperature, as an average value, as several average values and/or as a function. The model (M) can, for example, comprise a matrix (A) or consist of a matrix (A). For a temperature profile (x), the temperature control performance can be determined by a matrix-vector multiplication (M(x) = A*x). The optimized temperature profile can be calculated by solving the optimization problem min f(M(x)), in particular under the following constraints a) to c). The target functional f calculates a total temperature control performance from the temperature control performance, in particular the cooling performance and/or the heating performance, of at least a part of the, in particular essentially all, temperature-controlled zones. A typical example of the target functional f is the squared Euclidean norm f(y) = ∥y∥ ² . The optimization problem can be expressed as follows f(M(x)) = ∥A*x∥ ² . The previously described constraints a) to c) are also as follows:

1. a) For at least some of the temperature-controlled zones, in particular all temperature-controlled zones, in the optically used area, the respective target temperature for the optimized temperature profile remains unchanged compared to the respective target temperature of the initial temperature profile,
2. b) for at least some of the temperature-controlled zones, in particular all temperature-controlled zones, in a first section of the optically unused area, the respective target temperature for the optimized temperature profile corresponds to the reference temperature and/or the respective target temperature for the optimized temperature profile remains unchanged compared to the reference temperature, and/or
3. c) the temperature deviation from the reference temperature averaged over at least some of the temperature-controlled zones, in particular substantially all of the temperature-controlled zones, is below a predetermined threshold value.

The reference temperature is in particular an essentially constant and/or predetermined temperature.

The method for determining an optimized temperature profile of an optical element for microlithography can preferably be a computer-implemented method. The optical element and/or the temperature-controlled zones can therefore advantageously be a model, in particular a virtual one.

In one embodiment of the method for determining an optimized temperature profile of an optical element for microlithography, it is provided that in step 2b) for at least some of the temperature-controlled zones in the optically unused area, the respective target temperature for the optimized temperature profile is changed compared to the respective target temperature of the initial temperature profile in such a way that the optimized temperature control performance is lower than the initial temperature control performance. This means in particular that the optimized temperature control performance for essentially all temperature-controlled zones and/or essentially the entire optical element is lower than the initial temperature control performance for essentially all temperature-controlled zones and/or essentially the entire optical element. This simplifies a more energy-efficient influence on the radiation.

Alternatively or additionally, it can be provided that in step 2b) for at least some of the temperature-controlled zones in the optically unused area, the respective target temperature for the optimized temperature profile is changed compared to the respective target temperature of the initial temperature profile in such a way that the optimized temperature control performance is below a predetermined threshold value. This also simplifies a more energy-efficient influence on the radiation.

In one embodiment of the method for determining an optimized temperature profile of an optical element for microlithography, it is provided that in step 1b) for at least some of the temperature-controlled zones in a first section and/or a second section of the optically unused area, the respective target temperature of the initial temperature profile corresponds to a reference temperature. The reference temperature is in particular a substantially constant and/or predetermined temperature.

In one embodiment of the method for determining an optimized temperature profile of an optical element for microlithography, it is provided that in step 2b) for at least some of the temperature-controlled zones in a first section of the optically unused area, the respective target temperature for the optimized temperature profile remains unchanged compared to the respective target temperature of the initial temperature profile and/or that in step 2b) for at least some of the temperature-controlled zones in a second section of the optically unused area, the respective target temperature for the optimized temperature profile is changed compared to the respective target temperature of the initial temperature profile. By keeping the target temperatures unchanged for the first section, it is made easier that components of a projection exposure system adjacent to the optical element are not influenced, or at least only influenced to a small extent, by the temperature control of the optically used area. It can advantageously be provided that in step 2b) for essentially all temperature-controlled zones in a first section of the optically unused area, the respective target temperature for the optimized temperature profile remains unchanged compared to the respective target temperature of the initial temperature profile. It can be provided that the part of the temperature-controlled zones in the first section of the optically unused area in which the respective target temperature remains unchanged corresponds to the respective target temperature of the reference temperature. By changing the target temperatures for the second section, it is made easier that the demarcation between the optically used area and the optically unused area is less clear and strict, at least with regard to the prevailing temperatures, but is preferably a more fluid transition. It can be provided that for at least some of the temperature-controlled zones in a second section of the optically unused area, the respective target temperature for the optimized temperature profile is changed individually compared to the respective target temperature of the initial temperature profile. Alternatively or additionally, it can be provided, for example, that for essentially all temperature-controlled zones in a second section of the optically unused area, the respective target temperature for the optimized temperature profile is changed, preferably individually, compared to the respective target temperature of the initial temperature profile. However, there may be temperature profiles where it makes sense to leave some zones in the second section of the optically unused area unchanged, especially at reference temperature.

In one embodiment of the method for tempering an optical element for microlithography, it is provided that the optically unused region is arranged at least in sections on the edge of the optical element, in particular at least in sections along the edge of the optical element, and/or that the first section of the optically unused region is arranged at least in sections on the edge of the optical element, in particular at least in sections along the edge of the optical element. This prevents or at least counteracts the fact that components adjacent to the optical element are influenced by the tempering of the optically used region. The optically unused region and/or the first section of the optically unused region can advantageously be arranged essentially completely along the edge of the optical element. This further enhances the aforementioned effect. It is advantageous to arrange the first section of the optically unused region in particular where the optical element can come into contact with other components, in particular where it can be connected to other components. For example, the first portion of the optically unused area can be arranged adjacent to sensors connected to the optical element so as not to affect the function of the sensors.

In one embodiment of the method for determining an optimized temperature profile of an optical element for microlithography, it is provided that the second section of the optically unused region is arranged at least in sections between the first section of the optically unused region and the optically used region and/or the optically used region is arranged at least in sections in the middle of the optical element. By arranging the second section of the optically unused region between the first section of the optically unused region and the optically used region, it is further simplified that the demarcation between the optically used region and the optically unused region is less clear and strict, at least with regard to the prevailing temperatures, but is preferably a more fluid transition. The arrangement of the optically used region in the middle of the optical element in turn simplifies the arrangement of the optical element, in particular the optically used region, in a projection exposure system. On the other hand, it is simplified that adjacent components of the projection exposure system are not influenced by the temperature control, since with a central arrangement there is sufficient space at the edges of the optical element for the optically unused area, in particular the first section of the optically unused area. Advantageously, it can be provided that the optically used area is surrounded at least partially, in particular substantially completely, by the first section of the optically unused area and/or the second section of the optically unused area. This further simplifies a more fluid transition between the different areas, at least with regard to the prevailing temperatures.

The aforementioned object is further achieved by a device for data processing comprising a processor which is configured to carry out the method according to one of claims 7 to 12. In this case, it can preferably be provided that some of the steps or all of the steps of the method, in particular steps 1b) and/or step 2b), are carried out.

The aforementioned object is further achieved by a computer program comprising instructions which, when executed by at least one processor of a device, are designed to cause the device to carry out the method according to one of claims 7 to 12. In this case, it can preferably be provided that some of the steps or all of the steps of the method, in particular steps 1b) and/or step 2b), are carried out.

The aforementioned object is further achieved by a computer-readable medium comprising instructions which, when executed by at least one processor of a device, cause the device to carry out the method according to one of claims 7 to 12. In this case, it can preferably be provided that some of the steps or all of the steps of the method, in particular steps 1b) and/or step 2b), are caused to be carried out.

A data processing device according to the present disclosure can comprise hardware and/or software components. The data processing device can comprise, for example, at least one memory, in particular with instructions of a computer program (e.g. at least one of the disclosed computer programs), and/or at least one processor, in particular designed to execute instructions from the at least one memory. Accordingly, a data processing device should also be understood as disclosed which comprises at least one processor and at least one memory with instructions, wherein the at least one memory and the instructions are designed, together with the at least one processor, to cause the data processing device to execute at least one of the disclosed methods, in particular the method according to one of claims 7 to 12. A data processing device according to the present disclosure can, for example, be part of a control system of a projection exposure system.

Alternatively or additionally, the data processing device may further comprise one or more communication interfaces (e.g. one or more wired and/or wireless communication interfaces, e.g. a wireless communication interface in the form of a radio interface) and/or one or more user interfaces (e.g. a keyboard, a mouse, a screen, a touch-sensitive screen, a loudspeaker, a microphone, etc.). It is understood that the disclosed data processing device may also comprise other means not listed.

In this disclosure, a processor is understood to include, among others, control units, microprocessors, microcontrol units such as microcontrollers, digital signal processors (DSP), application-specific integrated circuits (ASICs) or field programmable gate arrays (FPGAs).

A computer program according to this disclosure may, for example, be distributable over a network such as the Internet, a telephone or mobile network and/or a local area network. The computer program may be at least partially software and/or firmware of a processor. It may equally be implemented at least partially as hardware. The computer program may, for example, be stored on a computer-readable medium, in particular a storage medium, e.g. a magnetic, electrical, optical and/or other type of storage medium. The storage medium may, for example, be part of the processor, for example a (non-volatile or volatile) program memory of the processor or a part thereof.

The storage medium can, for example, be a tangible or physical storage medium.

A computer-readable medium according to this disclosure may be a volatile or non-volatile data storage. For example, the computer-readable medium may be a hard disk, a USB storage device, a RAM, ROM, EPROM, or flash memory. The computer-readable medium may also be a data communication network enabling download of program code, such as the Internet or a data cloud.

• 1 den prinzipiellen Aufbau einer exemplarischen Projektionsbelichtungsanlage,
• 2A ein optisches Element in einer Draufsicht mit einem ersten veranschaulichten Temperaturprofil,
• 2B das optische Element aus 2A in einer Draufsicht mit einem zweiten veranschaulichten Temperaturprofil,
• 3 ein schematisches Blockdiagramm einer Vorrichtung zur Datenverarbeitung, und
• 4 eine schematische Darstellung von Beispielen gegenständlicher und nicht-flüchtiger computerlesbarer Medien.

The disclosure is explained in more detail below with reference to a drawing which merely shows preferred embodiments. In the drawing:

• 1 the basic structure of an exemplary projection exposure system,
• 2A an optical element in a plan view with a first illustrated temperature profile,
• 2 B the optical element 2A in a plan view with a second illustrated temperature profile,
• 3 a schematic block diagram of a data processing device, and
• 4 a schematic representation of examples of tangible and non-transitory computer-readable media.

1 shows the basic structure of an exemplary projection exposure system 1. The projection exposure system 1 shown comprises a radiation source 2, for example an excimer laser, an illumination system 3 and a projection system 4. The illumination system 3 preferably has at least one device for selecting the illumination mode. Between the output of the illumination system 3 and the input of the projection system 4 there is a mask holder 5 which holds and manipulates a mask 6 so that a structure - which structure is part of the mask 6 - of a specific layer of the semiconductor component to be produced lies in the, preferably planar, object plane OE _PR of the projection system 4, wherein the object plane OE _PR of the projection system 4 coincides with the image plane BE _BE of the illumination system 3. The mask holder 5 - also referred to as "reticle stage" - for holding and handling the mask 6 contains a drive with which the mask 6 can be moved parallel to the object plane OE _PR of the projection system 4 and perpendicular to the optical axis OA _PR of the projection system 4 and to the optical axis OA _BE of the illumination system (Z direction) in a scanning direction (Y direction) for scanning operation.

The projection system 4 is preferably telecentric in the object plane OE _PR and the image plane BE _PR and is intended to project an image of a structure provided by the mask 6, preferably at a reduced scale, onto a substrate 7 coated with a radiation-sensitive layer, in particular a wafer. The substrate 7 is arranged such that the flat surface 8 with the radiation-sensitive layer essentially coincides with the image plane BE _PR of the projection system 4. The substrate 7 is held by a substrate holder 9 - also called a "wafer stage" - which comprises a drive for moving the substrate 7. The substrate holder 9 can also comprise manipulators for moving the substrate both in the Z direction parallel to the optical axis OA _PR of the projection system 4 and in the X and Y directions perpendicular to the optical axis OA _PR of the projection system 4. A tilting device with at least one tilting axis running perpendicular to the optical axis OA _PR of the projection system 4 can also be integrated.

In the projection exposure system 1 shown, the projection exposure system 1, here in particular the projection system 4, comprises at least one temperature-controlled optical element 10. The temperature-controlled optical element 10 can alternatively or additionally also be arranged in the illumination system 3. The optical element 10 can be a lens and/or a mirror. The optical element 10 is arranged in and along the optical axis of the projection exposure system 1, in particular the optical axis OA _PR of the projection system 4. In the projection exposure system 1 shown, the optical element 10 comprises a temperature control device. The temperature control device comprises heating elements and cooling elements in order to temperature the optical element 10.

The projection exposure system 1 also comprises a controller 11. The controller 11 is designed, among other things, to control the temperature of the temperature-controlled optical element 10.

2A shows an optical element 10 in a plan view with a first illustrated temperature profile. The optical element is the already described temperature-controlled optical element 10. The surface of the optical element 10 can be seen on and/or through which the radiation is guided during exposure.

The optical element 10 comprises a plurality of temperature-controlled zones 12. These temperature-controlled zones 12 can be heated and/or cooled in order to set a desired temperature profile. The temperature profile, in particular the target temperatures of the temperature profile to be set, are in 2A represented by different dots. However, no absolute temperatures are shown here, but rather the difference between the respective target temperature and a comparison temperature, in this case the reference temperature.

A part of the temperature-controlled zones 12 is arranged in an optically used area OGB of the optical element 10 and another part of the temperature-controlled zones 12 is arranged in an optically unused area OUB of the optical element 10. The optically used area OGB is in the 2a indicated by a circle. However, this circle only serves to better visualize the optically used area OGB and the transition between the optically used area OGB and the optically unused area OUB and is not to be understood as a mandatory demarcation between the optically used area OGB and the optically unused area OUB. The dimensions and/or the shape of the optically used area OGB and the optically unused area OUB can change during operation of the projection exposure system 1, for example depending on the exposure setting used.

The optically unused area OUB is in turn divided into two sections, a first section OUB ₁ and a second section OUB ₂ of the optically unused area OUB. The optically unused area OUB, in particular the first section OUB ₁ of the optically unused area OUB, is arranged, among other things, all the way around the edge of the optical element 12. The optically used area OGB is arranged in the middle of the optical element 12, with the optical axis of the projection exposure system 1 running through the optically used area OGB. The optical axis of the projection exposure system 1 can run centrally through the optically used area OGB and alternatively or additionally run vertically or obliquely through the optically used area OGB. The second section OUB ₂ of the optically unused area OUB is arranged between the first section OUB ₁ of the optically unused area OUB and the optically used area OGB. The optically used area OGB is completely surrounded by the first section OUB ₁ and the second section OUB ₂ of the optically unused area OUB.

The temperature-controlled zones 12 of the optically used area OGB are not tempered to a constant target temperature, but to different target temperatures. The temperature control of the zones 12 in the optically used area OGB is intended to influence the radiation intended for exposure, for example to correct imaging errors. The radiation intended for exposure is used for the exposure of the substrate 7. The 2A The temperature profile illustrated has a constant reference temperature in the optically unused area OUB, both in the first section OUB ₁ and in the second section OUB ₂ . This is intended to prevent other components of the projection exposure system 1 from being influenced by the temperature control of the optical element 10, in particular the temperature-controlled zones 12 in the optically used area OGB. The fact that the temperature-controlled zones 12 in the optically unused area OUB all have the reference temperature, in particular are tempered to the reference temperature, results in a clear and strict demarcation between the prevailing temperatures in the optically unused area OUB and in the optically used area OGB. The corresponding temperature profile can be referred to as the initial temperature profile. The disadvantage of this temperature profile, however, is that it requires a high temperature control power, in particular in the optically unused area OUB adjacent to the optically used area OGB. This temperature control power cannot then be used to influence the radiation intended for exposure.

2 B shows the optical element 2A in a top view with a second illustrated temperature profile. The 2 B The temperature profile shown can be described as an optimized temperature profile. The optimized temperature profile was based on the 2A described initial temperature profile using an optimization procedure.

This in 2 B Temperature profile shown differs from that in 2A shown temperature profile in that in the second section OUB ₂ of the optically unused area OUB at least some of the temperature-controlled zones 12 do not have the same temperature as at least another part of the temperature-controlled zones 12 in the second section OUB ₂ of the optically unused area OUB and/or as at least some of the temperature-controlled zones 12 in the first section OUB ₁ of the optically unused area OUB. In particular, in the second section OUB ₂ of the optically unused area OUB, the temperature-controlled zones 12 at least partially no longer have the constant reference temperature, but a target temperature that deviates therefrom. In the first section OUB ₁ of the optically unused area OUB and in the optically used area OGB, however, the target temperatures are unchanged. It can be seen that there is no longer a clear and strict demarcation between the prevailing temperatures in the optically unused area OUB and in the optically used area OGB, or at least only a weakened one, and instead there is a more fluid transition. A more energy-efficient use of the optical element 10 is thus possible. In addition, without adapting the components of the projection exposure system 1, in particular the optical element 10, temperature profiles can also be implemented which require more temperature control power in the optically used area OGB than was previously usual.

3 shows a schematic block diagram of a data processing device 100 that is configured to carry out the method for determining an optimized temperature profile of an optical element for microlithography. The data processing device 100 comprises a processor 101, a working memory 102, an instruction memory 103, an optional data memory 104, one or more optional communication interfaces 105 and an optional user interface 106.

The data processing device 100 can, for example, be configured to carry out the method for determining an optimized temperature profile of an optical element for microlithography or to comprise corresponding means (in particular one of the means 101 to 108) for carrying out the method. The data processing device 100 can also be a device that comprises at least one processor (in particular processor 101) and at least one memory (preferably memory 102 and/or memory 103) with instructions, wherein the at least one memory and the instructions are configured to cause a device, e.g. the data processing device 100, with the at least one processor, at least to carry out the method for determining an optimized temperature profile of an optical element for microlithography.

The processor 101 may, for example, comprise an initial temperature profile provider 107 as a functional and/or structural unit. The initial temperature profile provider 107 may, for example, be configured to provide an initial temperature profile (see step 1b of the method for determining an optimized temperature profile of an optical element for microlithography).

The processor 101 can, for example, comprise an optimized temperature profile determiner 108 as a functional and/or structural unit. The optimized temperature profile determiner 108 can, for example, be configured to determine an optimized temperature profile, in particular based on the initial temperature profile by means of an optimization method (see step 2b) of the method for determining an optimized temperature profile of an optical element for microlithography).

For example, the processor 101 may execute instructions stored in the instruction memory 103, where the instruction memory 103 may, for example, represent a computer-readable medium containing instructions that, when executed by the processor 101, cause the processor 101 to perform the method for determining an optimized temperature profile of an optical element for microlithography.

The processor 101 may be a processor of any suitable type. The processor 101 may include, but is not limited to, one or more microprocessors, one or more processors with one or more associated digital signal processors, one or more processors without associated digital signal processors, one or more special purpose computer chips, one or more field programmable gate arrays (FPGAs), one or more controllers, one or more application specific integrated circuits (ASICs), or one or more computers.

For example, the processor 101 may control the memories 102-104, the communication interface(s) 105, and the user interface 106. The memory 102 may, for example, be a volatile memory. It may be, for example, a random access memory (RAM) or a dynamic random access memory (DRAM), to name just a few non-limiting examples. It may, for example, be used by the processor 101 in executing an operating system and/or computer program.

The instruction memory 103 and/or data memory 104 may, for example, be a non-volatile memory. It may, for example, be a flash memory (or a part thereof), a ROM, PROM, EPROM or EEPROM memory (or a part thereof) or a hard disk (or a part thereof), to name just a few examples. The communication interface(s) 105 enable the data processing device 100 to communicate with other devices. The communication interface(s) 105 may, for example, comprise a wireless interface (e.g. a cellular interface, a WLAN interface and/or a BT/BLE interface) and/or a wired interface (e.g. an IP-based interface) to communicate with devices via the Internet, for example.

The user interface 106 is optional and may include a display for displaying information to a user and/or an input device (e.g., a keyboard, keypad, touchpad, mouse, etc.) for receiving information from a user.

Some or all components of the data processing device 100 can be connected via a bus, for example. Some or all components of the data processing device 100 can be combined into one or more modules, for example.

4 shows a schematic representation of examples of tangible and non-transitory computer-readable media, in particular storage media, according to the present disclosure, which can be used, for example, to implement the main memory 102, the instruction memory 103 and/or the data memory 104. For this purpose, 4 a flash memory 109, which may be soldered and/or attached to a circuit board, for example, a solid-state drive 110 with a plurality of memory chips (e.g., flash memory chips), a magnetic hard disk 111, a Secure Digital (SD) card 112, a Universal Serial Bus (USB) memory stick 113, an optical storage medium 114 (such as a CD-ROM or DVD), and a magnetic storage medium 115.

List of reference symbols

1

Projection exposure system

2

Radiation source

3

Lighting system

4

Projection system

5

Mask holder

6

mask

7

Substrat

8th

Area

9

Substrate holder

10

temperature-controlled optical element

11

steering

12

temperable zone

100

Device for data processing

101

processor

102

random access memory

103

Instruction memory

104

Data storage

105

Communication interface

106

User interface

107

Initial Temperature Profile Provider

108

Optimized temperature profile determiner

109

Flash memory

110

Solid-state drive

111

magnetic hard drive

112

SD card

113

USB memory stick

114

optical storage medium

115

magnetic storage medium

BABIES

Image plane of the lighting system

BEPR

Image plane of the projection system

OABE

optical axis of the lighting system

OAPR

optical axis of the projection system

OEPR

Object plane of the projection system

OGB

optically used area

OUB

optically unused area

OUB1

first section of the optically unused area

OUB2

second section of the optically unused area

Claims (15)

Method for tempering an optical element (10) for microlithography, comprising the following steps: 1a) providing at least one temperable optical element (10) for microlithography, - wherein the optical element (10) has a plurality of temperable zones (12), - wherein a portion of the temperable zones (12) is arranged in an optically used region (OGB) of the optical element (10), and - wherein a portion of the temperable zones (12) is arranged in an optically unused region (OUB) of the optical element (10), 2a) tempering the optical element (10), - wherein at least a portion of the temperable zones (12) is tempered in the optically used region (OGB), in a first section (OUB1) of the optically unused region (OUB) and/or in a second section ( _OUB2 ) of the optically unused region (OUB), characterized in that in step 2a) in the second section (OUB ₂ ) of the optically unused area (OUB), at least some of the temperature-controlled zones (12) do not have the same temperature as at least another part of the temperature-controlled zones (12) in the second section (OUB ₂ ) of the optically unused area (OUB) and/or as at least some of the temperature-controlled zones (12) in the first section (OUB ₁ ) of the optically unused area (OUB). Procedure according to Claim 1 , characterized in that in step 2a) in the first section (OUB1) of the optically unused area (OUB) at least a part of the temperature-controlled zones (12) is tempered to a reference temperature, that in step 2a) in the second section (OUB ₂ ) of the optically unused area (OUB) at least some of the temperature-controlled zones (12) do not have the reference temperature, that in step 2a) in the second section (OUB ₂ ) of the optically unused area (OUB) at least some of the temperature-controlled zones (12) are tempered to at least one temperature deviating from the reference temperature and/or to different temperatures and/or that in step 2a) in the optically used area (OGB) at least some of the temperature-controlled zones (12) are tempered to at least one temperature deviating from the reference temperature and/or to different temperatures. Procedure according to Claim 2 , characterized in that in step 2a) the optical element (10) is tempered such that the temperature deviation from the reference temperature averaged over at least a part, preferably substantially all, temperable zones (12) is below a predetermined threshold value. Procedure according to one of the Claims 1 until 3 , characterized in that the optically unused region (OUB) is arranged at least in sections on the edge of the optical element (10), in particular at least in sections along the edge of the optical element (10), and/or that the first section (OUB ₁ ) of the optically unused region (OUB) is arranged at least in sections on the edge of the optical element (10), in particular at least in sections along the edge of the optical element (10). Procedure according to one of the Claims 1 until 4 , characterized in that the second section (OUB ₂ ) of the optically unused region (OUB) is arranged at least in sections between the first section (OUB ₁ ) of the optically unused region (OUB) and the optically used region (OGB) and/or the optically used region (OGB) is arranged at least in sections in the middle of the optical element (10). Projection exposure system (1) for microlithography comprising: - at least one temperature-controlled optical element (10), and - a controller (11), - wherein the optical element (10) and/or the controller (11) is configured to carry out the method according to one of the Claims 1 until 5 to carry out. Method for determining an optimized temperature profile of an optical element (10) for microlithography, comprising the following steps: 1b) providing an initial temperature profile of an optical element (10) for microlithography, - wherein the optical element (10) has a plurality of temperature-controlled zones (12), - wherein a portion of the temperature-controlled zones (12) is arranged in an optically used area (OGB) of the optical element (10), - wherein a portion of the temperature-controlled zones (12) is arranged in an optically unused area (OUB) of the optical element (10), - wherein the initial temperature profile for at least a portion of the temperature-controlled zones (12) comprises a respective initial target temperature, and - wherein an initial temperature control power is required to set the initial temperature profile, 2b) determining an optimized temperature profile of the optical element (10) based on the initial temperature profile by means of an optimization method, - wherein the optimized temperature profile for at least some of the temperature-controlled zones (12) comprises a respective optimized target temperature, - wherein an optimized temperature control performance is required in order to set the optimized temperature profile, - wherein for at least some of the temperature-controlled zones (12) in the optically used area (OGB), the respective target temperature for the optimized temperature profile remains unchanged compared to the respective target temperature of the initial temperature profile, - wherein for at least some of the temperature-controlled zones (12) in the optically unused area (OUB), the respective target temperature for the optimized temperature profile is changed compared to the respective target temperature of the initial temperature profile. Procedure according to Claim 7 , characterized in that in step 2b) for at least a part of the temperature-controlled zones (12) in the optically unused area (OUB) the respective target temperature for the optimized temperature profile is changed compared to the respective target temperature of the initial temperature profile such that the optimized temperature control performance is lower than the initial temperature control performance. Procedure according to Claim 7 or Claim 8 , characterized in that in step 1b) for at least a part of the temperature-controlled zones (12) in a first section (OUB ₁ ) and/or a second section (OUB ₂ ) of the optically unused area (OUB) the respective target temperature of the initial temperature profile corresponds to a reference temperature. Method according to one of the Claims 7 until 9 , characterized in that in step 2b) for at least part of the temperature-controlled Zones (12) in a first section (OUB ₁ ) of the optically unused area (OUB), the respective target temperature for the optimized temperature profile remains unchanged compared to the respective target temperature of the initial temperature profile and/or that in step 2b) for at least some of the temperature-controlled zones (12) in a second section (OUB ₂ ) of the optically unused area (OUB), the respective target temperature for the optimized temperature profile is changed compared to the respective target temperature of the initial temperature profile. Procedure according to one of the Claims 7 until 10 , characterized in that the optically unused region (OUB) is arranged at least in sections on the edge of the optical element (10), in particular at least in sections along the edge of the optical element (10), and/or that the first section (OUB ₁ ) of the optically unused region (OUB) is arranged at least in sections on the edge of the optical element (10), in particular at least in sections along the edge of the optical element (10). Procedure according to one of the Claims 7 until 11 , characterized in that the second section (OUB ₂ ) of the optically unused region (OUB) is arranged at least in sections between the first section (OUB ₁ ) of the optically unused region (OUB) and the optically used region (OGB) and/or the optically used region (OGB) is arranged at least in sections in the middle of the optical element (10). A data processing device (100) comprising a processor (101) configured to carry out the method according to one of the Claims 7 until 12 executes. Computer program comprising instructions which, when executed by at least one processor (101) of a device (100), are designed to cause the device (100) to carry out the method according to one of the Claims 7 until 12 to execute. Computer-readable medium (109, 110, 111, 112, 113, 114, 115) comprising instructions which, when executed by at least one processor (101) of a device (100), cause the device (100) to carry out the method according to one of the Claims 7 until 12 to execute.

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