DE102019117484A1 - Method and arrangement for loading a component into a loading position in an optical system for microlithography - Google Patents

Abstract

The invention relates to a method and an arrangement for loading a component into a loading position in an optical system. A method of loading a component into an optical system for microlithography, the system having a first area operated under atmospheric pressure, a second area designed to alternate between atmospheric pressure and vacuum conditions, and a third area operated under vacuum conditions, comprises the following steps: (a ) Introducing a first component in a contamination-protected container from the first area (10) into the second area (20) while the second area (20) is under atmospheric pressure, (b) introducing the first component from the second area (20) into the third region (30), while the second region (20) is under vacuum conditions, and (c) transferring the first component to a loading position (37, 38) in the optical system; wherein the introduction of the first component into the second region (20) according to step (a) takes place in a temporal overlap for the introduction of a second component into the first region (10).

Description

BACKGROUND OF THE INVENTION

Field of invention

The invention relates to a method and an arrangement for loading a component into a loading position in an optical system for microlithography.

State of the art

Microlithography is used for the production of microstructured components, such as integrated circuits or LCDs. The microlithography process is carried out in what is known as a projection exposure system, which has an illumination device and a projection objective. The image of a mask (= reticle) illuminated by the illumination device is projected by means of the projection lens onto a substrate (e.g. a silicon wafer) coated with a light-sensitive layer (photoresist) and arranged in the image plane of the projection lens, in order to apply the mask structure to the light-sensitive coating of the To transfer substrate.

In projection lenses designed for the EUV range, i.e. at wavelengths of e.g. about 13 nm or about 7 nm, mirrors are used as optical components for the imaging process due to the lack of availability of suitable light-permeable refractive materials.

In the lithography process, undesired defects on the mask have a particularly detrimental effect, since these can be reproduced with every exposure step. In order to minimize the mask defects and to realize a successful mask repair, an immediate analysis of the imaging effect of possible defect positions is therefore desirable. There is therefore a need to measure or qualify the mask quickly and easily, and to be precise if possible under the same conditions as they actually exist in the projection exposure system. For this it is i.a. known to record and evaluate an aerial image of a section of the mask in a mask inspection system. In order to record the aerial image, the structures to be measured on the mask are illuminated with illumination optics, the light coming from the mask being projected onto a detector unit via imaging optics and detected. In order to measure the mask, if possible, under conditions analogous to the projection exposure system, the mask is typically illuminated in the mask inspection system in an identical manner to the projection exposure system, with the same wavelength, the same numerical aperture and the identical lighting setting being set in the mask inspection system.

Optical systems for microlithography designed for operation in the EUV range, which in addition to the microlithographic projection exposure system itself also include devices for characterizing the mask or for high-precision (e.g. interferometric) testing of EUV mirrors, typically require the provision of vacuum conditions (depending on Use with pressures of the order of magnitude of 1 mbar or with significantly lower pressures of e.g. 10 ^-3 -10 ^-6 mbar) in order to meet the high accuracy requirements applicable to EUV microlithography, for example with regard to problems occurring at atmospheric pressure as a result of contamination and the temperature dependence of the refractive index of e.g. air to meet.

The requirement of operation under vacuum conditions in turn makes it more difficult to achieve short throughput times with the respective optical system (e.g. a mask inspection system) or the increase in throughput, since the loading of different optical components such as e.g. Masks in the relevant optical system while avoiding contamination or thermally induced aberrations represents a demanding challenge. Another problem that occurs in practice when reducing the throughput time or increasing the throughput is that e.g. after a change in the lighting setting or after loading the mask to be examined into the optical system used for characterization, there is initially no thermal equilibrium in the optical system in question. Corresponding temperature differences in turn result in thermal relaxation processes, which can ultimately lead to incorrect characterization (e.g. incorrect determination of certain mask parameters).

One possible approach to overcoming the problem described above is to e.g. After changing the lighting setting or loading the mask into the optical system, wait a certain (running-in) phase, which, however, leads to a reduction in the total available measurement time (due to the relatively slow approach of the optical system to thermal equilibrium) idle times caused by the waiting phases) and is therefore also associated with an undesirable decrease in the throughput achieved with the optical system.

The state of the art is only given by way of example WO 2019/018281 A1 referenced.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a method and an arrangement for loading a component into a loading position in an optical system for microlithography which enable increased throughput in the operation of the optical system while at least partially avoiding the problems described above.

This object is achieved by the method according to the features of independent claim 1 or the arrangement according to the features of the independent claim 16.

1. a) Einbringen einer ersten Komponente in einem kontaminationsgeschützten Behälter vom ersten Bereich in den zweiten Bereich, während sich der zweite Bereich unter Atmosphärendruck befindet;
2. b) Einbringen der ersten Komponente vom zweiten Bereich in den dritten Bereich, während sich der zweite Bereich unter Vakuumbedingungen befindet; und
3. c) Überführen der ersten Komponente in eine Ladeposition im optischen System;

wobei das Einbringen der ersten Komponente in den zweiten Bereich gemäß Schritt a) in zeitlichem Überlapp zum Einbringen einer zweiten Komponente in den ersten Bereich erfolgt.A method according to the invention for loading a component into an optical system for microlithography, wherein the system has a first area operated under atmospheric pressure, a second area designed to switch between atmospheric pressure and vacuum conditions and a third area operated under vacuum conditions, has the following steps:

1. a) introducing a first component in a contamination-protected container from the first area into the second area, while the second area is under atmospheric pressure;
2. b) introducing the first component from the second area into the third area while the second area is under vacuum conditions; and
3. c) transferring the first component to a loading position in the optical system;

wherein the introduction of the first component into the second area according to step a) takes place in a temporal overlap for the introduction of a second component into the first area.

In the context of the present application, vacuum conditions are preferably to be understood as meaning a state with a (constant or changing) pressure of less than 100 mbar, in particular less than 1 mbar.

The invention is particularly based on the concept of using in an optical system for microlithography such as e.g. a mask inspection system or a projection exposure system to increase the achievable throughput by realizing a temporal overlap in the different components such as Masks to be carried out process steps, the overall processing time required for a plurality of process cycles decreases.

Furthermore, the present invention also includes the concept that the individual components, each time a new component such as e.g. Mask into the relevant optical system or for the subsequent removal of the component from the optical system, to carry out the individual steps required in an automated manner in such a way that the relevant steps for a plurality of components such as e.g. Masks are repeated with permanent maintenance of vacuum conditions in one area of the optical system.

Both the timing according to the invention of the loading of a new component such as e.g. Mask into the relevant optical system or the individual steps required to later lead the component out of the optical system as well as the automated implementation of these individual steps have the advantage, in addition to increasing the achievable throughput, that overall there is a lower risk of contamination for the respective components.

In embodiments of the invention, the aforementioned automated implementation includes in particular, on the one hand, the robot-assisted handling of both the relevant components themselves and of the containers used to protect them from contamination. On the other hand, the automation according to the invention in embodiments also includes the use of magazines for storing a plurality of components (e.g. base parts or cover parts) of such containers, with the result that the relevant components depending on whether they are currently introduced into the optical system or removed from the optical system Component can be removed from the relevant magazine or stored there again as required.

Such storage of the relevant components in the optical system or under the temperature conditions present in the system can also avoid thermal problems, for example as a result of thermal relaxation processes.

According to one embodiment, steps a) to c) are repeated for a plurality of components with uninterrupted maintenance of vacuum conditions in the third region.

1. a) Einbringen einer ersten Komponente in einem kontaminationsgeschützten Behälter vom ersten Bereich in den zweiten Bereich, während sich der zweite Bereich unter Atmosphärendruck befindet;
2. b) Einbringen der ersten Komponente vom zweiten Bereich in den dritten Bereich, während sich der zweite Bereich unter Vakuumbedingungen befindet; und
3. c) Überführen der ersten Komponente in eine Ladeposition im optischen System;

wobei die Schritte a) bis c) für eine Mehrzahl von Komponenten unter permanenter Aufrechterhaltung von Vakuumbedingungen in dem dritten Bereich wiederholt werden.The invention further relates to a method for loading a component into a loading position in an optical system for microlithography, the system having a first area operated under atmospheric pressure and one for changing between atmospheric pressure and Having a second area designed for vacuum conditions and a third area operated under vacuum conditions, the method comprising the following steps:

1. a) introducing a first component in a contamination-protected container from the first area into the second area, while the second area is under atmospheric pressure;
2. b) introducing the first component from the second area into the third area while the second area is under vacuum conditions; and
3. c) transferring the first component to a loading position in the optical system;

wherein steps a) to c) are repeated for a plurality of components with permanent maintenance of vacuum conditions in the third region.

According to one embodiment, the method further comprises transferring the first component from the loading position into the first area in the reverse of the sequence of steps a) -c).

According to one embodiment, the first component is transferred from the loading position into the first area with a temporal overlap for introducing a further component from the first area into the loading position.

According to one embodiment, the first component is transferred from the loading position into the first area while vacuum conditions are permanently maintained in the third area.

According to one embodiment, step c) comprises (in particular robot-assisted) placing a base part of the contamination-protected container in a first magazine which is designed to store a plurality of base parts.

In the context of the present application, a “magazine” is to be understood as any storage or storage device for receiving a plurality (i.e. at least two) components.

According to one embodiment, step c) comprises (in particular robot-assisted) placing a cover part of the contamination-protected container in a second magazine which is designed to store a plurality of cover parts.

According to one embodiment, before step a) of introducing the first component from the first area into the second area, the contamination-protected container receiving the first component (in particular robot-assisted) is removed from a double container, this double container receiving an inner container forming the contamination-protected container within an outer container .

According to one embodiment, the optical system is designed for at least one working wavelength of less than 30 nm, in particular less than 15 nm.

According to one embodiment, the components are lithography masks.

According to a further embodiment, the components are aperture stops.

According to a further embodiment, the components are transport frames.

The invention further relates to an arrangement for loading a component into a loading position in an optical system for microlithography, the arrangement being configured to carry out a method having the features described above. For advantages and preferred configurations of the arrangement, reference is made to the above statements in connection with the method according to the invention.

Further refinements of the invention can be found in the description and in the subclaims.

The invention is explained in more detail below with reference to the exemplary embodiments shown in the accompanying figures.

Figure list

• 1a-1b ein Flussdiagramm zur Erläuterung des möglichen Ablaufs eines erfindungsgemäßen Verfahrens in einer Ausführungsform;
• 2 ein Flussdiagramm zur Erläuterung des möglichen Ablaufs eines erfindungsgemäßen Verfahrens in einer weiteren Ausführungsform;
• 3 eine schematische Darstellung zur Erläuterung eines beispielhaften Aufbaus einer erfindungsgemäßen Anordnung zum Laden einer Komponente in eine Ladeposition in einem optischen System;
• 4 eine schematische Darstellung zur Erläuterung eines beispielhaften Aufbaus eines optischen Systems zur Charakterisierung einer Maske für die Mikrolithographie; und
• 5 eine schematische Darstellung eines Projektionsobjektivs einer für den Betrieb im EUV-Bereich ausgelegten mikrolithographischen Projektionsbelichtungsanlage.

Show it:

• 1a-1b a flow chart to explain the possible sequence of a method according to the invention in one embodiment;
• 2 a flow chart to explain the possible sequence of a method according to the invention in a further embodiment;
• 3 a schematic illustration to explain an exemplary structure of an arrangement according to the invention for loading a component into a loading position in an optical system;
• 4th a schematic illustration to explain an exemplary structure of an optical system for characterizing a mask for microlithography; and
• 5 a schematic representation of a projection objective of a microlithographic projection exposure system designed for operation in the EUV range.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

In the following, exemplary embodiments of the invention are described with reference to the in 1a-1b and 2 flow charts as well as the in 3 schematically illustrated arrangement explained.

• Der erste Bereich 10 ist für den Betrieb unter Atmosphärendruck bzw. nicht unter Vakuumbedingungen ausgestaltet, wobei in diesem Bereich 10 typischerweise unter Verwendung eines geeigneten Spülgases (z.B. Stickstoff) eine möglichst saubere und kontaminationsfreie Umgebung geschaffen wird. Der zweite Bereich 20 ist für einen Wechsel zwischen Atmosphärendruck und Vakuumbedingungen ausgelegt und bildet eine Schleuse, welche nach Bedarf abgepumpt oder belüftet werden kann (wobei entsprechende Schleusentüren mit Vakuumventilen in 3 mit „21“ bzw. „22“ bezeichnet sind). Der dritte Bereich 30 ist für den (dauerhaften) Betrieb unter Vakuumbedingungen ausgelegt.

In each case, a component such as a lithography mask, a transport frame or a screen is transferred to a loading position in an optical system (e.g. a mask inspection system or a microlithographic projection exposure system), this optical system as in 1-3 indicated in particular three areas that can be distinguished from one another 10 , 20th and 30th having:

• The first area 10 is designed for operation under atmospheric pressure or not under vacuum conditions, in this area 10 an environment that is as clean and contamination-free as possible is typically created using a suitable flushing gas (eg nitrogen). The second area 20th is designed for a change between atmospheric pressure and vacuum conditions and forms a lock, which can be pumped out or ventilated as required (with corresponding lock doors with vacuum valves in 3 With " 21st " or. " 22nd "Are designated). The third area 30th is designed for (permanent) operation under vacuum conditions.

Said “vacuum conditions” can, depending on the specific application, be pressures in the range of the order of magnitude of 1 mbar or also well below (eg in the case of a projection exposure system in the range of 10 ^-3 -10 ^-6 mbar).

According to 1a takes place in one step S1 first of all, the transfer of a container holding a component (eg mask) into the optical system or its first area operated under atmospheric pressure 10 . Said container can in embodiments be a double container ("dual pod"), which is designed in a manner known per se with two layers in that it has a vacuum-suitable inner container within an outer container, with both inner and outer containers in each case can be constructed from a base part and a cover part which is releasably fastened on this base part. The use of such “double containers” is, for example, off WO 2019/018281 A1 known.

In particular, the said inner container can in turn be provided with ventilation openings in order to enable the enclosed volume, in which the relevant component can be stored, to be pumped out or ventilated. Furthermore, said inner container can have one or more suitable filter device (s) to provide an atmosphere that is as contamination-free as possible.

The invention is not limited to the implementation in connection with such double containers, so that in further embodiments the respective component is introduced into the optical system or its first area 10 receiving container can also be designed as a single container or single-walled container.

While the above-described inner container is removed from the outer container in a robot-assisted manner when the component is introduced into a double container, when the component is introduced into a single container, the component is initially reloaded into another vacuum-compatible container (which in its design is again preferably corresponds to the inner container described above).

In both scenarios (ie both when using a double container and when using a single container) according to step S2 a robot picks up the component (inner) container. This is followed by step S3 the placement of this component-receiving inner container in the second area 20th forming lock, whereupon the lock in step S4 (typically with the setting in the third area 30th existing vacuum conditions) is pumped out.

This is followed by step S5 the removal of the inner container from the second area 20th or the lock using a third area located under vacuum conditions 30th existing other robot (in 3 With " 39 “Labeled), whereupon the inner container in step S6 (at an in 3 With " 31 “Marked position) and the component (eg mask) in the step S7 either in the respective loading position (in 3 With " 38 “Referred to) is transferred in the optical system or initially stored in a magazine. With " 32 “Is a magazine for storing a plurality of cover parts of corresponding inner containers. If necessary, a suitable transport frame for better handling and to reduce the risk of a Damage to the component or mask. Such a transport frame can according to 3 about the robot 39 from a magazine 35 can be removed. Via an in 3 With " 36 "Designated further robot, the component (eg mask) can be removed from a base part (base plate) of the respective inner container, furthermore according to 3 this base part of the inner container from one with " 33 “Designated position in a magazine 34 can be fed. If the component is an aperture diaphragm, it can be inserted into a " 37 "Designated loading position are transferred.

How now further out 1a-1b As can be seen, further steps are carried out in connection with the introduction of further components into the optical system or the removal of components from the optical system in a temporal overlap in order to achieve an overall increase in the throughput achieved during operation.

Specifically takes place in the embodiment of 1a simultaneously with the placement of the inner container in the second area 20th or the lock according to step S3 also according to step S14 the loading of another container into the optical system or its first area 10 . Furthermore, this “new” component or the (inner) container that receives it is also used in the step S15 (analogous to step S2 ) the second area 20th or fed to the lock. Furthermore, according to 1a after removing the inner container from the second area 20th or the lock in the crotch S5 the lock in the crotch S11 ventilated, so that the inner container receiving the new component in the crotch S12 placed in the lock and the lock in crotch S13 can be pumped out, whereupon the inner container is again removed from the lock according to step S8 he follows.

This inner container is also in the step S9 opened, whereupon the included component (e.g. mask) in step S10 in turn, either in the respective loading position as required 38 placed in the optical system or, if necessary, initially stored in the magazine.

2 shows a flowchart to explain a further possible scenario when carrying out the method according to the invention, wherein according to 2 Process steps on the atmosphere and vacuum side (ie within the first area 10 and the third area 30th ) be carried out with a temporal overlap or partially simultaneously.

According to 2 occurs first (in to 1 in this respect analogous) the loading of a component (eg mask) receiving container into the optical system or its first area 10 according to step S21 and holding an (inner) container with the component via a robot in step S22 followed by placing the inner canister in the second area 20th or the lock according to step S23 and pumping out the lock in the crotch S24 . Simultaneously with the steps S21 and S22 or in a temporal overlap with this now takes place according to 2 on the vacuum side or in the third area 30th the removal of a (eg previously measured or used) component from the loading position according to step S25 and the placement of this component (eg mask) in a magazine according to step S26 . Furthermore takes place according to 2 after pumping out the lock according to step S24 the removal of the inner container from the lock according to step S27 , opening the inner container according to step S28 and transferring the component (eg mask) into a magazine or the loading position in step S29 .

The realization of the above based on 2 described scenarios can alternatively or additionally to the realization of the scenario of 1 respectively.

4th shows the possible structure of a mask inspection system as an example of an optical system 400 .

According to 4th is in a mask inspection system 400 a mask 421 on a mask holder 420 stored. The structures to be measured on the mask 421 are with from a light source 401 generated illumination light via illumination optics 410 illuminated. From the mask 421 incoming light comes from imaging optics 430 on a detector unit 440 mapped and detected. The one from the detector unit 440 The recorded image data are stored in an evaluation unit 450 evaluated to determine the position of the structures. The invention can for example be used to load a new mask 421 or another component (for example an aperture diaphragm or a transport frame) in the mask inspection system 400 be applied.

5 shows, as a further example of an optical system, a schematic representation of a projection exposure system designed for operation in the EUV 500 .

According to 5 has an illumination device of the projection exposure system 500 a field facet mirror 503 and a pupil facet mirror 504 on. On the field facet mirror 503 the light from a light source unit, which in the example is an EUV light source (plasma light source) 501 and a collector mirror 502 includes, steered. In the light path after the pupil facet mirror 504 are a first telescope mirror 505 and a second Telescope mirror 506 arranged. In the light path below is a deflecting mirror 507 arranged that the radiation hitting it on an object field in the object plane of a six mirror 521-526 comprehensive projection lens directs. At the location of the object field there is a reflective structure-bearing mask 531 on a mask table 530 arranged, which is imaged with the aid of the projection objective in an image plane in which a substrate coated with a light-sensitive layer (photoresist) is located 541 on a wafer table 540 is located.
The invention can for example be used to load a new mask 531 or another component (for example an aperture stop or a transport frame) in the projection exposure system 500 be applied.

While the invention has been described in terms of specific embodiments, numerous variations and alternative embodiments will occur to those skilled in the art, e.g. by combining and / or exchanging features of individual embodiments. Accordingly, a person skilled in the art understands that such variations and alternative embodiments are also encompassed by the present invention, and the scope of the invention is limited only within the meaning of the appended patent claims and their equivalents.

QUOTES INCLUDED IN THE DESCRIPTION

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

Patent literature cited

• WO 2019/018281 A1 [0008, 0038]

Claims (16)

A method for loading a component into a loading position in an optical system for microlithography, the system having a first area (10) operated under atmospheric pressure, a second area (20) designed to switch between atmospheric pressure and vacuum conditions and a third area (20) operated under vacuum conditions ( 30), the method comprising the following steps: a) introducing a first component in a contamination-protected container from the first area (10) into the second area (20) while the second area (20) is under atmospheric pressure; b) introducing the first component from the second region (20) into the third region (30) while the second region (20) is under vacuum conditions; and c) transferring the first component to a loading position (37, 38) in the optical system; wherein the introduction of the first component into the second area (20) according to step a) takes place with a temporal overlap for the introduction of a second component into the first area (10). Procedure according to Claim 1 , characterized in that steps a) to c) are repeated for a plurality of components with permanent maintenance of vacuum conditions in the third region (30). A method for loading a component into a loading position in an optical system for microlithography, the system having a first area (10) operated under atmospheric pressure, a second area (20) designed to switch between atmospheric pressure and vacuum conditions and a third area (20) operated under vacuum conditions ( 30), the method comprising the following steps: a) introducing a first component in a contamination-protected container from the first area (10) into the second area (20) while the second area (20) is under atmospheric pressure; b) introducing the first component from the second region (20) into the third region (30) while the second region (20) is under vacuum conditions; and c) transferring the first component to a loading position (37, 38) in the optical system; wherein steps a) to c) are repeated for a plurality of components while permanently maintaining vacuum conditions in the third region (30). Method according to one of the Claims 1 to 3 , characterized in that this further comprises transferring the first component from the loading position (37, 38) to the first area (10) in reverse of the sequence of steps a) -c). Procedure according to Claim 4 , characterized in that the transfer of the first component from the loading position (37, 38) to the first area (10) takes place in a temporal overlap for introducing a further component from the first area (10) into the loading position (37, 38). Procedure according to Claim 4 or 5 , characterized in that the transfer of the first component from the loading position (37, 38) into the first area (10) takes place with permanent maintenance of vacuum conditions in the third area (30). Method according to one of the preceding claims, characterized in that step c) comprises placing a base part of the contamination-protected container in a first magazine (34) which is designed to store a plurality of base parts. Method according to one of the preceding claims, characterized in that step c) comprises placing a cover part of the contamination-protected container in a second magazine (32) which is designed to store a plurality of cover parts. Procedure according to Claim 7 or 8th , characterized in that this placement is carried out with a robot. Method according to one of the preceding claims, characterized in that before step a) of introducing the first component from the first area (10) into the second area (20), the contamination-protected container holding the first component is removed from a double container, this double container accommodates an inner container forming the contamination-protected container within an outer container. Procedure according to Claim 10 , characterized in that this removal is carried out with a robot. Method according to one of the preceding claims, characterized in that the optical system is designed for at least one working wavelength of less than 30 nm, in particular less than 15 nm. Method according to one of the Claims 1 to 12 , characterized in that the components are lithography masks. Method according to one of the Claims 1 to 12 , characterized in that the components are aperture diaphragms. Method according to one of the Claims 1 to 12 , characterized in that the components are transport frames. Arrangement for loading a component into a loading position in an optical system, the system having a first area (10) operated under atmospheric pressure, a second area (20) designed to switch between atmospheric pressure and vacuum conditions and a third area (30) operated under vacuum conditions wherein the arrangement is configured to carry out a method according to any one of the preceding claims.

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