Method and device for producing an adhesive bond between a first component and a second component

Abstract

The invention relates to a method and a device for producing an adhesive bond between a first component and a second component for microlithography, wherein the second component is an optical element. The method comprises the following steps: introducing the first component and the second component into a positioning device (100) which can change the relative position between the first component and the second component; calibrating the first relative position, in which the distance between the first component and the second component has a first value defining a predefined adhesive gap; calibrating the second relative position, in which the distance between the first component and the second component has a second value greater than the first value; applying an adhesive (26) to the first component when the first component and the second component are at a distance greater than the first value from each other; and setting the first relative position when forming the adhesive bond between the first component and the second component; wherein both calibrating the first relative position and calibrating the second relative position are still carried out before applying the adhesive to the first component.

Description

[0001] This application claims the priority of German patent application DE 10 2019 209 610.7 filed on July 1, 2019. The entire content of this German application is also incorporated into the text of the present application by reference. Background of the Invention Technical Field

[0003] The present invention relates to a method and an apparatus for producing an adhesive bond between a first component and a second component for microlithography. The invention can be used in particular for producing an adhesive bond between an actuator and an optical element, such as a mirror, as a component for producing microlithography. The invention also relates to a method for producing a projection exposure apparatus for microlithography comprising an illumination device and a projection lens, wherein the adhesive bond between the first component and the second component is produced in the illumination device and / or the projection lens. Background Art

[0005] Microlithography is used to produce microstructured components such as integrated circuits or LCDs. The microlithography process is carried out in a so-called projection exposure system, which comprises an illumination device and a projection lens. Here, an image of a mask (reticle) illuminated by the illumination device is projected via the projection lens onto a substrate (e.g., a silicon wafer) coated with a photosensitive layer (photoresist) and positioned in the image plane of the projection lens. This transfers the mask structure to the substrate's photosensitive coating.

[0006] In projection lenses designed for the EUV range (ie at wavelengths of eg about 13 nm or about 7 nm), mirrors are used as optical components of the imaging process due to the lack of available suitable light-transmitting refractive materials.

[0007] In both systems designed for the EUV range and DUV systems (i.e. wavelengths below 250 nm, in particular below 200 nm), it is known to configure optical components, such as mirrors, in an adaptive or actuable manner in order to at least partially compensate for imaging aberrations in the optical system, for example by local deformation compensation. To this end, one or more (e.g. piezoelectric) actuators can be attached to the respective optical element, for example to its rear side facing away from the optically active surface, by adhesive bonding.

[0008] In such adhesive bonds, precise setting of the adhesive gap—which is desirable or necessary for the service life of the adhesive bond and to avoid undesirable optical aberrations in the optical system—poses a severe challenge due to the high accuracy requirements in lithographic applications. This is due in particular to the fact that a defined setting of the corresponding adhesive gap at the often curved connection surfaces is made more difficult by a number of factors, including, in particular, manufacturing-related geometric deviations of the connection surfaces, viscosity fluctuations of the adhesive, and the influence of gravity, which affects the flow behavior of the adhesive and the exact orientation of the components. An additional factor is that, given the high accuracy requirements, the introduction of mechanical stresses and the associated deformations, particularly into the corresponding actuators or associated optical elements, must be reliably prevented. Summary of the Invention

[0009] The object of the present invention is to provide a method and a device for producing an adhesive bond between a microlithographic first component and a second component, which enable a reliable and precise setting of the adhesive gap while at least partially avoiding the above-mentioned problems.

[0010] This object is achieved by a method according to the features of independent claim 1 and by a device according to the features of the alternative independent claim 16 .

[0011] The method according to the invention for producing an adhesive bond between a microlithographic first component and a second component, wherein the second component is an optical element, comprises the following steps:

[0012] - introducing the first component and the second component into a positioning device, which can change the relative position between the first component and the second component;

[0013] - calibrating a first relative position in which the distance between the first component and the second component has a first value defining a predefined bonding gap;

[0014] - calibrating a second relative position in which the distance between the first component and the second component has a second value greater than the first value;

[0015] - applying the adhesive to the first component when the first component and the second component are at a distance from each other that is greater than a first value; and

[0016] - setting a first relative position when forming an adhesive between the first component and the second component;

[0017] Therein, both calibrating the first relative position and calibrating the second relative position are still performed before applying the adhesive to the first component.

[0018] Although it is assumed below as an example that the first component is an actuator and the second component is an optical element, for example, in the form of a mirror, both of which are used for microlithography, the present invention is not limited thereto. On the contrary, the present invention can also be advantageously implemented in other applications for microlithography that seek to achieve the most reliable and precise setting of the bonding gap possible while at least partially avoiding the problems described in the introduction.

[0019] In the context of the requirements of microlithography, the present invention is based on the concept of achieving a precise and controlled setting of the bond gap between a first component (e.g., an actuator) and a second component (e.g., an optical component) when producing an adhesive bond, by calibrating the relative position between the actuator and the optical element, both with respect to an end position corresponding to the desired final bond gap distance and with respect to a (starting) position not yet corresponding to said end position, in a positioning device that allows the relative position of the actuator and the optical element to be changed, before the adhesive is applied to one of the connection surfaces. One of these calibration steps, which is still performed without applying adhesive, is typically performed at the beginning or before the actuator has initially been moved to the optical element, while the other calibration step (relating to the calibration of the end position of the actuator relative to the optical element, said end position corresponding to the bond gap distance) is performed after the initial movement to the optical element. Adhesive can then be applied to the actuator again with the actuator at a greater distance from the optical element, and the actuator can finally be moved from the calibrated starting position to the optical element to a similarly calibrated end position corresponding to the bond gap distance.

[0020] Since the last-mentioned step is carried out without the optical element being contacted by the actuator and also with control of the (typically sensor-assisted) bond gap distance setting, a precise bond gap setting is achieved in a controlled manner while at the same time avoiding the introduction of mechanical stresses into the optical element via the actuator.

[0021] According to one embodiment, calibrating the second relative position comprises measuring a position of a calibration element temporarily in contact with the surface of the first component.

[0022] According to one embodiment, the calibration element has a geometry corresponding to the surface of the second component.

[0023] According to one embodiment, the calibration of the first relative position and / or the second relative position is carried out using at least one distance sensor, in particular an optical distance sensor.

[0024] According to an embodiment, calibrating the first relative position and / or the second relative position comprises orienting the second component in six degrees of freedom.

[0025] According to one embodiment, said orientation of the second component is performed using at least one mechanical stop present in the positioning device.

[0026] According to one embodiment, calibrating the first relative position and / or the second relative position comprises a lateral orientation of the first component.

[0027] According to one embodiment, said transverse orientation of the first component is performed using at least one mechanical stop present in the positioning device.

[0028] According to one embodiment, the first component comprises a plurality of partial surfaces, wherein during application of the adhesive the adhesive is metered differently for mutually different partial surfaces taking into account an expected meniscus formation in the edge region of the respective partial surface.

[0029] According to one embodiment, during application of the adhesive, the adhesive is positioned taking into account the angular position between the first component and the second component, which angular position is expected to be in the end position obtained after the adhesive bond has been produced.

[0030] According to one embodiment, the first component is an actuator.

[0031] According to one embodiment, the second component is an optical element, in particular a mirror or a lens element.

[0032] The invention further relates to a method for producing a microlithographic projection exposure apparatus comprising an illumination device and a projection lens, wherein an adhesive bond between a first component and a second component in the illumination device and / or the projection lens is produced by carrying out the method having the above features.

[0033] In this case, the first component may in particular be an actuator and the second component may in particular be an optical element, more in particular a mirror or a lens element.

[0034] The invention further relates to a device for producing an adhesive bond between a microlithographic first component and a second component, wherein the device is configured to carry out a method having the above-mentioned features.

[0035] Further configurations of the invention can be derived from the description and the dependent claims.

[0036] The invention is explained in more detail below based on the exemplary embodiments shown in the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In the attached figure:

[0038] Figures 1a-1e A schematic diagram is shown for illustrating a possible sequence of the method according to the invention;

[0039] Figure 2-3Shown for more specific illustration Figure 1b Detailed schematic diagram of possible configurations of the middle area "A";

[0040] Figure 4 A flow chart is shown for explaining the sequence of the method according to the invention in an exemplary embodiment;

[0041] Figure 5-6 A schematic diagram is shown for illustrating an advantageous configuration of the method according to the invention;

[0042] Figure 7 shows a schematic diagram for illustrating a possible configuration of a microlithography projection exposure apparatus designed for operation under EUV; and

[0043] Figure 8 Shown is a schematic diagram for illustrating a possible configuration of a microlithographic projection exposure apparatus designed for operation in the DUV range. DETAILED DESCRIPTION

[0044] Reference below Figures 1a-1e and Figure 2-3 The schematic diagram and Figure 4 The shown flow chart explains an embodiment of the method according to the invention.

[0045] according to Figure 1a , the method is implemented in a positioning device 100 which, as described in more detail below, enables the orientation of the components (the optical component 10 on the one hand and the actuator 20 on the other hand) to be connected to each other by means of adhesive bonding and adjusting the relative positions of the components with respect to each other. This includes Figure 1a and according to Figure 4 Steps S410 and S420 firstly carry out a process of orienting the optical component 10 in six degrees of freedom (e.g. using mechanical stops 112, 113) and a process of laterally orienting the actuator 20, which is carried by a table 115 movable in the z direction and is adjustable by means of adjustment means 40, e.g. in the form of micron screws. "21" and "22" denote the connection lines and contacts of the respective (e.g. piezoelectric) actuators 20. According to Figure 1a In the exemplary embodiment, lateral orientation of the actuator 20 is achieved by a lateral mechanical stop 24 .

[0046] The next step S430 consists in calibrating the (z) position of the actuator 20, which can be used as a starting position in a relative adjustment later on. Here, the measurement technology mentioned below (e.g., the confocal sensor) is "zeroed" with respect to the actuator surface and defines the position of the boundary surface of the bonding gap later on. This calibration, which corresponds to the "zeroing" of the z position of the actuator 20, is carried out using any suitable measurement technology and, in the exemplary embodiment, by means of the confocal sensor 30 directed toward the reference surface 50a of the calibration element 50 in the form of a reference mirror. As can be seen from Figure 2 As can best be seen, in a specific exemplary embodiment (but the invention is not limited thereto), the measuring portion of the confocal sensor 30 extends through the aperture 23 located in the actuator 20. The reference surface 50a of the calibration element 50, which bears against the surface 20a of the actuator 20 during this calibration, has a geometry corresponding to that of the surface of the optical element 10. By measuring the position of the reference surface 50a by means of the confocal sensor 30, the position of the surface 20a of the actuator 20 is also indirectly determined.

[0047] In other embodiments, the above-described calibration of the position of the actuator 20 may also be performed using any other suitable (eg tactile) measurement technique or using a coordinate measuring machine.

[0048] according to Figure 3 The calibration element (or reference mirror) used in the above-described calibration of the position of the actuator 20 can also be configured with significantly reduced lateral dimensions, so that, for example, Figure 3 In the exemplary embodiment shown, the calibration element 55 is projected precisely over the aperture 23 present in the actuator 20 and used by the confocal sensor 30. Thus, by using such a calibration element 55, Figure 2 In contrast to the configuration in FIG. , generally, imperfections or unevenness in shape present on the surface 20 a of the actuator 20 have no effect on the calibration. Furthermore, imperfections in shape on the surface 20 a of the actuator 20 can also be determined when two separate calibration steps are performed, one using the larger calibration element 50 and the other using the smaller calibration element 55.

[0049] according to Figure 4 as well as Figure 1c The next step S440 then comprises moving the actuator 20 to the optical element 10 until the desired bonding gap (100 μm as an example only) is obtained, the movement being movable in the z direction by means of the table 115 and preferably under control by means of the confocal sensor 30. In an embodiment of the invention, the above steps can also be carried out for a plurality of actuators 20 fixed to the optical element 10 by adhesive bonding. After the desired bonding gap distance is obtained, a corresponding calibration of the z position is again carried out, thus according to Figure 4 and Figure 1d The subsequent step S450 comprises again moving the actuator 20 away from the optical element 10 and applying an adhesive 26 on the surface of the actuator 20 by means of suitable means 25 .

[0050] A further step S460 consists in moving the actuator 20 again towards the optical element 10 until a calibration position previously defined according to the desired adhesive gap is reached, wherein a fine control of the adhesive gap can again be achieved with the aid of the confocal sensor 30. The actual curing process of the adhesive 26 (step S470) can typically last several days. In this case, optionally after a suitable period of time (e.g. 24 hours) during which the adhesive 26 has cured and the actuator 20 has been securely fixed to the mirror 10, the table 115 movable in the z direction can be lowered by a relatively small distance (e.g. 5 μm) in order to avoid, by this "free movement", the subsequent transmission of mechanical stresses from the actuator 20 via the adhesive 26 to the optical element 10.

[0051] Applying current to the (particularly piezoelectric) actuator 20 can likewise be carried out in step S460 and, for example, still before the optional free movement, but preferably after fine positioning of the actuator for safety reasons.

[0052] In other embodiments, the (particularly piezoelectric) actuator can also have a plurality of partial surfaces, in accordance with Figure 4 In step S450, an adhesive is applied to the plurality of partial surfaces in each case in order to produce an adhesive bond. Figure 5 As schematically shown in a-5c, the amount of adhesive applied respectively may vary depending on the specific geometry, with the aim of obtaining a uniform meniscus formation at the respective edge surface with a defined bonding gap.

[0053] to this end, Figure 5 a first schematically shows the formation of a bonding gap 501 between the actuator 501 and the optical element 500 and the formation of a meniscus 502 at the edge region. Figure 5 b, the actuator has different types of partial surfaces ("Type 1" - "Type 4") which differ from one another with respect to the edge region (circular segment or outer edge), wherein the meniscus is correspondingly formed during the adhesive bonding process. In this respect, as an example, for Figure 5In the ("inner") partial surface of "Type 1" schematically shown in c, a meniscus is formed only at the four circular segments 512, and not at the shorter or longer outer edges 513, 514. In contrast, for the partial surface of "Type 2", a meniscus is formed at the shorter outer edges in addition to the four circular segments; for the partial surface of "Type 3", a meniscus is formed at the longer outer edges in addition to the four circular segments; and for the partial surface of "Type 4", a meniscus is formed at both the shorter and longer outer edges in addition to the four circular segments. Therefore, the amount of adhesive applied to the partial surface of "Type 1" is preferably selected to be smaller than the amount of adhesive applied to the partial surface of "Type 2", and the amount of adhesive applied to the partial surfaces of "Type 2" and "Type 3" is selected to be smaller than the amount of adhesive applied to the partial surface of "Type 4", and so on.

[0054] In other embodiments, when Figure 1d When applying the adhesive in step S450, the respective tilt position or angular position of the relevant actuator surface at the respective position may also be taken into account (i.e. a suitable margin is selected in the bonding point position), so that the desired set point position of the bonding point is established only after the adhesive has flowed therein in a manner governed by the respective tilt position. Figure 6 The viscosity of the adhesive (preferably predetermined) is taken into account accordingly by selecting a corresponding margin.

[0055] Figure 7 Shown is a schematic diagram of an exemplary projection exposure apparatus designed for operation under EUV and in which the invention can be implemented.

[0056] according to Figure 7 The illumination device in the projection exposure apparatus 700 designed for EUV includes a field facet mirror 703 and a pupil facet mirror 704. Light from a light source unit comprising a plasma light source 701 and a collector mirror 702 is directed onto the field facet mirror 703. A first telescope mirror 705 and a second telescope mirror 706 are arranged in the beam path downstream of the pupil facet mirror 704. A deflection mirror 707 is arranged downstream of the light path and directs the radiation incident thereon onto an object field in the object plane of a projection lens comprising six mirrors 751-756. At the location of the object field, a mask 721 supported by a reflective structure is arranged on a mask stage 720. The mask is imaged into an image plane by means of the projection lens, wherein a substrate 761 coated with a photosensitive layer (photoresist) is located on a wafer stage 760.

[0057] Among other applications, the invention can also be implemented in projection exposure tools designed for operation in the DUV.

[0058] Figure 8 A schematic diagram of a further possible configuration of a microlithographic projection exposure apparatus 800 is shown, which is designed to operate at a wavelength in the DUV range (eg approximately 193 nm) and likewise comprises an illumination device 801 and a projection lens 808 .

[0059] The illumination device 801 includes a light source 802 and an illumination optical unit, which is represented in a highly simplified manner by lens elements 803, 804, and an aperture 805. When an ArF excimer laser is used as the light source 802, the operating wavelength of the projection exposure apparatus 800 in the illustrated example is 193 nm. However, the operating wavelength can also be, for example, 248 nm when a KrF excimer laser is used as the light source 802, or 157 nm when an F2 laser is used as the light source 802. A mask 807 is arranged in the object plane OP of the projection lens 808 between the illumination device 801 and the projection lens 808. The mask is held in the beam path by a mask holder 806. The mask 807 has structures in the micrometer to nanometer range, which are imaged, for example, by the projection lens 808, with a reduction of 4 or 5 times onto the image plane IP of the projection lens 808. The projection lens 808 includes an arrangement of lens elements defining an optical axis OA, which is also represented only in a highly simplified manner by lens elements 809 to 812.

[0060] A substrate 816 or wafer, which has been provided with a photosensitive layer 815 and is positioned by a substrate holder 818, is held in an image plane IP of the projection lens 808. An immersion medium 850, which can be, for example, deionized water, is located between the last optical element 820 of the projection lens 808, which is situated on the image plane side, and the photosensitive layer 815.

Claims

1. A method for producing an adhesive bond between a microlithographic first component and a second component, wherein: The second component is an optical element, and wherein the method comprises the steps of: a) introducing the first component and the second component into a positioning device (100) capable of changing the relative position between the first component and the second component; b) calibrating a first relative position in which a distance between the first component and the second component has a first value defining a predefined bonding gap; c) calibrating a second relative position in which the distance between the first component and the second component has a second value greater than the first value; d) applying adhesive (26) to the first component when the first component and the second component are spaced apart from each other by a distance greater than the first value; and e) setting the first relative position when forming the adhesive bond between the first component and the second component; Wherein, both calibrating the first relative position and calibrating the second relative position are still performed before applying the adhesive (26) to the first component.

2. The method according to claim 1, characterized in that The calibrating the second relative position comprises measuring the position of a calibration element (50, 55) temporarily in contact with the surface of the first component.

3. The method according to claim 2, characterized in that The calibration element (50) has a geometry corresponding to the surface of the second component.

4. The method according to any one of claims 1 to 3, characterized in that Calibration of the first relative position and / or the second relative position is performed using at least one distance sensor.

5. The method according to any one of claims 1 to 3, characterized in that Calibration of the first relative position and / or the second relative position is performed using an optical distance sensor.

6. The method according to any one of claims 1 to 3, characterized in that Calibrating the first relative position and / or the second relative position comprises orienting the second component in six degrees of freedom.

7. The method according to claim 6, characterized in that Said orientation of said second component is carried out using at least one mechanical stop (112, 113) present in said positioning device.

8. The method according to any one of claims 1 to 3, characterized in that Calibrating the first relative position and / or the second relative position includes a lateral orientation of the first component.

9. The method according to claim 8, characterized in that The transverse orientation of the first component is performed using at least one mechanical stop (24) present in the positioning device.

10. The method according to any one of claims 1 to 3, characterized in that The first component comprises a plurality of partial surfaces, wherein during application of the adhesive the dosage of adhesive is varied for mutually different partial surfaces taking into account the expected formation of a meniscus in the edge region of the respective partial surface.

11. The method according to any one of claims 1 to 3, characterized in that During application of the adhesive, the adhesive is positioned taking into account the angular position between the first component and the second component, which angular position is intended to be in the end position obtained after the adhesive bond has been produced.

12. The method according to any one of claims 1 to 3, characterized in that The first component is an actuator (20).

13. The method according to any one of claims 1 to 3, characterized in that The second component is an optical element (10).

14. The method according to any one of claims 1 to 3, characterized in that The second component is a reflector or a lens element.

15. Method for producing a microlithography projection exposure apparatus (700, 800) comprising an illumination device and a projection lens, wherein the adhesive bond between a first component and a second component in the illumination device and / or the projection lens is produced by carrying out the method according to any one of claims 1 to 14.

16. The method according to claim 15, characterized in that The first component is an actuator (20).

17. The method according to claim 15 or 16, characterized in that The second component is an optical element (10).

18. The method according to claim 15 or 16, characterized in that The second component is a reflector or a lens element.

19. A device for producing an adhesive bond between a microlithographic first component and a second component, characterized in that The apparatus is configured to carry out the method according to any one of claims 1 to 14.

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