DE102021205277A1 - PROCEDURE - Google Patents

Abstract

A method for gluing a component (210) to an optical element (202), comprising the steps of: a) positioning (S1) of the component (210) relative to the optical element (202) such that between the component (210) and an adhesive gap (220) is provided for the optical element (202), b) application (S2) of an adhesive (216) into the adhesive gap (220), and c) independent distribution (S3) of the adhesive (216) in the adhesive gap (220 ) with the help of the capillary effect.

Description

The present invention relates to a method for gluing a component to an optical element.

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

Driven by the striving for ever smaller structures in the production of integrated circuits, EUV lithography systems (English: extreme ultraviolet, EUV) are currently being developed, which emit light with a wavelength in the range from 0.1 nm to 30 nm, in particular 13.5 nm , use. In such EUV lithography systems, because of the high absorption of light of this wavelength by most materials, reflecting optics, ie mirrors, must be used instead of—as hitherto—refractive optics, ie lenses.

In order to be able to influence the reflection properties of such optics, it is possible to deform them using a piezo actuator. This piezo actuator can be glued to the back of the respective optics. For this purpose, dots of adhesive can be applied to the piezo actuator and/or to the optics. The piezo actuator and the optics can then be assembled. However, this can lead to air pockets in the adhesive. This is to be avoided.

Against this background, one object of the present invention is to provide an improved method for gluing a component to an optical element.

Accordingly, a method for gluing a component to an optical element is proposed. The method comprises the following steps: a) positioning the component relative to the optical element in such a way that an adhesive gap is provided between the component and the optical element, b) applying an adhesive into the adhesive gap, and c) distributing the adhesive independently in the Adhesive gap with the help of the capillary effect.

Because the adhesive is distributed in the adhesive gap with the aid of the capillary effect, the inclusion of gas bubbles in the adhesive is reliably prevented. A degree of wetting of 100% can be achieved. Furthermore, the adhesive is prevented from running out of the adhesive gap.

The component is preferably a ceramic component. The component can be an actuator, in particular a piezo actuator, which is suitable for reversibly deforming the optical element. The component preferably has a front side that is glued to the optical element and a back side that faces away from the front side. The optical element is preferably made of a ceramic or glass-ceramic material. The optical element is preferably a mirror. The optical element has a rear side that is glued to the front side of the component and a front side that faces away from the rear side. An optically effective surface, in particular a mirror surface, can be provided on the front side, which is applied to the front side as a coating. The optically effective surface is preferably only produced after the component has been glued to the optical element. Without the optically effective surface, the optical element can be transparent.

The positioning of the component relative to the optical element can be carried out in such a way that the component is arranged within a predetermined tolerance range after positioning. The component can have six degrees of freedom. The degrees of freedom include three translational degrees of freedom along three different spatial directions and three rotational degrees of freedom around the three spatial directions. A device into which the optical element and the component are installed can be provided for positioning the component. A measuring system can be used to check the positioning of the component. The measuring system can be part of the aforementioned device.

The adhesive gap is in particular dimensioned in such a way that the adhesive is in contact with both the component and the optical element when it is applied. This leads to the capillary effect. "Capillarity" or the "capillary effect" is to be understood as meaning the behavior of liquids, in particular the adhesive, which they exhibit when they come into contact with capillaries, such as narrow tubes, gaps or the adhesive gap. These effects are caused by the surface tension of liquids themselves and the interfacial tension between liquids and the solid surface. Due to the capillary effect, the adhesive is sucked into the adhesive gap and spreads there without penetrating intervention from outside. In the present case, “independent” means that the adhesive fills the adhesive gap by itself without external influence, only due to the capillary effect.

According to one embodiment, in step b) the adhesive is applied to the adhesive gap in a number of consecutive time intervals.

The time intervals are performed in immediate succession. The adhesive can distribute itself independently in the adhesive gap between the time intervals.

According to a further embodiment, in step b) the adhesive is applied at exactly one dosing point in the adhesive gap.

This prevents several flow fronts of the adhesive from forming, which could converge and trap air bubbles. The adhesive is therefore bubble-free. A dosing needle can be provided for applying the adhesive.

According to a further embodiment, the adhesive spreads out in a circle in the adhesive gap, starting from the dosing point.

This means that the adhesive spreads automatically and evenly in the adhesive gap, starting from the dosing point. In particular, a flow front of the adhesive is circular or at least arcuate.

According to a further embodiment, the dosing point is provided centrally on the component or the dosing point is provided on the edge of the component.

The dosing point can be, for example, a dosing hole arranged centrally or centrally on the component.

According to a further embodiment, in step a) the component is positioned relative to the optical element in such a way that the adhesive gap has a constant adhesive gap thickness.

This means that at every point on the front side of the component, the thickness of the adhesive gap is the same or at least within a specified tolerance range.

According to a further embodiment, in step c) the independent distribution of the adhesive in the adhesive gap is monitored with the aid of a sensor element, in particular a camera.

The optical element is preferably positioned between the sensor element and the component. The sensor element is thus directed towards the front side of the optical element.

According to a further embodiment, the independent distribution of the adhesive in the adhesive gap is monitored through the optical element with the aid of the sensor element.

In particular, the optical element is transparent for this purpose. After gluing, the optically effective surface can be attached to the front side of the optical element. After the optically active surface has been attached, the optical element is then in particular no longer transparent.

According to a further embodiment, the component and the optical element are spherically curved, with the component being glued to the rear of the optical element.

In particular, the front side of the component is glued to the rear side of the optical element. "Spherical" can mean present spherically curved. In particular, the component and the optical element are in the form of a spherical cap. In the present case, a “spherical cap” is to be understood as meaning a section or section of a sphere. The optical element can be constructed rotationally symmetrically to a central axis or axis of symmetry. However, the optical element can also have any other desired geometry.

According to a further embodiment, the adhesive is a low-viscosity epoxy resin, in particular a low-viscosity filled epoxy resin.

The adhesive preferably has a viscosity of less than 10,000 mPas. The adhesive can be filled with glass beads and/or quartz powder mixtures, for example. However, other fillers can also be used.

"A" is not necessarily to be understood as being limited to exactly one element. Rather, a plurality of elements, such as two, three or more, can also be provided. Any other count word used here should also not be understood to mean that there is a restriction to precisely the stated number of elements. Rather, numerical deviations upwards and downwards are possible, unless otherwise stated.

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

• 1A zeigt eine schematische Ansicht einer Ausführungsform einer EUV-Lithographieanlage;
• 1B zeigt eine schematische Ansicht einer Ausführungsform einer DUV-Lithographieanlage;
• 2 zeigt eine schematische Schnittansicht einer Ausführungsform eines optischen Systems für die Lithographieanlage gemäß 1A oder 1B;
• 3 zeigt eine weitere schematische Schnittansicht des optischen Systems gemäß 2;
• 4 zeigt eine schematische Aufsicht des optischen Systems gemäß 2;
• 5 zeigt eine weitere schematische Schnittansicht des optischen Systems gemäß 2;
• 6 zeigt eine weitere schematische Aufsicht des optischen Systems gemäß 2; und
• 7 zeigt ein schematisches Blockdiagramm einer Ausführungsform eines Verfahrens zum Verkleben eines Bauteils mit einem optischen Element der Lithographieanlage gemäß 1A oder 1B.

Further advantageous refinements and aspects of the invention are the subject matter of the dependent claims and of the exemplary embodiments of the invention described below. The invention is explained in more detail below on the basis of preferred embodiments with reference to the enclosed figures.

• 1A shows a schematic view of an embodiment of an EUV lithography system;
• 1B shows a schematic view of an embodiment of a DUV lithography system;
• 2 shows a schematic sectional view of an embodiment of an optical system for the lithography system according to FIG 1A or 1B ;
• 3 shows a further schematic sectional view of the optical system according to FIG 2 ;
• 4 shows a schematic top view of the optical system according to FIG 2 ;
• 5 shows a further schematic sectional view of the optical system according to FIG 2 ;
• 6 shows a further schematic top view of the optical system according to FIG 2 ; and
• 7 shows a schematic block diagram of an embodiment of a method for gluing a component to an optical element of the lithography system according to FIG 1A or 1B .

Elements that are the same or have the same function have been provided with the same reference symbols in the figures, unless otherwise stated. Furthermore, it should be noted that the representations in the figures are not necessarily to scale.

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

The EUV lithography system 100A has an EUV light source 106A. A plasma source (or a synchrotron), for example, can be provided as the EUV light source 106A, which emits radiation 108A in the EUV range (extreme ultraviolet range), ie for example in the wavelength range from 5 nm to 20 nm. In the beamforming and illumination system 102, the EUV radiation 108A is collimated and the desired operating wavelength is filtered out of the EUV radiation 108A. The EUV radiation 108A generated by the EUV light source 106A has a relatively high absorption by air, which is why the beam guidance spaces in the beam shaping and illumination system 102 and in the projection system 104 are evacuated.

This in 1A The beam shaping and illumination system 102 shown has five mirrors 110, 112, 114, 116, 118. After passing through the beam shaping and illumination system 102 , the EUV radiation 108A is directed onto a photomask (reticle) 120 . The photomask 120 is also designed as a reflective optical element and can be arranged outside of the systems 102, 104. Furthermore, the EUV radiation 108A can be directed onto the photomask 120 by means of a mirror 122 . The photomask 120 has a structure which is imaged on a wafer 124 or the like in reduced form by means of the projection system 104 .

The projection system 104 (also referred to as a projection lens) has six mirrors M1 to M6 for imaging the photomask 120 onto the wafer 124 . In this case, individual mirrors M1 to M6 of the projection system 104 can be arranged symmetrically to an optical axis 126 of the projection system 104 . It should be noted that the number of mirrors M1 to M6 of the EUV lithography tool 100A is not limited to the illustrated number. More or fewer mirrors M1 to M6 can also be provided. Furthermore, the mirrors M1 to M6 are usually curved on their front side for beam shaping.

1B FIG. 12 shows a schematic view of a DUV lithography system 100B, which comprises a beam shaping and illumination system 102 and a projection system 104. FIG. DUV stands for “deep ultraviolet” (DUV) and refers to a working light wavelength between 30 nm and 250 nm. The beam shaping and illumination system 102 and the Pro jection system 104 can - as already related to 1A described - be surrounded by a machine room with appropriate drive devices.

The DUV lithography system 100B has a DUV light source 106B. An ArF excimer laser, for example, can be provided as the DUV light source 106B, which emits radiation 108B in the DUV range at, for example, 193 nm.

This in 1B The beam shaping and illumination system 102 shown directs the DUV radiation 108B onto a photomask 120. The photomask 120 is designed as a transmissive optical element and can be arranged outside of the systems 102, 104. The photomask 120 has a structure which is imaged on a wafer 124 or the like in reduced form by means of the projection system 104 .

The projection system 104 has a plurality of lenses 128 and/or mirrors 130 for imaging the photomask 120 onto the wafer 124 . In this case, individual lenses 128 and/or mirrors 130 of the projection system 104 can be arranged symmetrically to an optical axis 126 of the projection system 104 . It should be noted that the number of lenses 128 and mirrors 130 of the DUV lithography tool 100B is not limited to the number illustrated. More or fewer lenses 128 and/or mirrors 130 can also be provided. Furthermore, the mirrors 130 are typically curved on their front side for beam shaping.

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

2 FIG. 1 shows a schematic sectional view of an embodiment of an optical system 200 for the EUV lithography system 100A according to FIG 1A or for the DUV lithography tool 100B according to FIG 1B . Although the optical system 200 for both the EUV lithography system 100A according to 1A as well as for the DUV lithography system 100B according to 1B is suitable, the optical system 200 is described below only with reference to the EUV lithography system 100A according to FIG 1A explained.

The optical system 200 includes an optical element 202. The optical element 202 can be, for example, one of the mirrors 110, 112, 114, 116, 118 or M1 to M6. The optical element 202 is spherically curved. The optical element 202 can be in the form of a spherical cap. In the present case, a “spherical cap” is to be understood as meaning a section or section of a sphere. However, the optical element 202 can also be plate-shaped or have any other desired geometry. The optical element 202 can be constructed in a rotationally symmetrical manner with respect to a central axis or axis of symmetry 204 .

A coordinate system with a first spatial direction or x-direction x, a second spatial direction or y-direction y and a third spatial direction or z-direction z is assigned to the optical system 200 . The directions x, y, z are oriented perpendicular to one another.

The optical element 202 can be made of a ceramic or glass-ceramic material. The optical element 202 comprises a curved front side 206 and a curved rear side 208 facing away from the front side 206. An optically effective surface (not shown) is provided on or on the front side 206. The optically effective surface can be a coating applied to the front side 206 . In particular, the optically effective surface is a mirror surface that is suitable for reflecting EUV radiation 108A. The optically effective surface can also be suitable for reflecting DUV radiation 108B. The optically effective surface of the optical element 202 can be spherically curved. The rear side 208 can also be spherically curved.

The optical system 200 includes a component 210 attached to the rear side 208 of the optical element 202. The component 210 is also spherically curved. In particular, the component 210 can be curved in the shape of a spherical cap. The component 210 is made of a ceramic material. The component 210 is an actuator, with the help of which the optical element 202 can be deformed. The component 210 can be referred to as an actuator, actuator or setting element. The component 210 is in particular a piezo actuator. The component 210 is deformed with the aid of energizing it, which in turn causes the optical element 202 to be deformed. This deformation is reversible.

The component 210 includes a front side 212, which faces the back side 208 of the optical element 202, and a back side 214, which faces away from the front side 212. The component 210 is glued to the back 208 of the optical element 202 . For this purpose, an adhesive 216 is provided between the component 210 and the rear side 208 . The adhesive 216 wets the Entire front side 212 of the component 210. That is, the degree of wetting is 100%. In the present case, the “degree of wetting” means the percentage of the front side 212 that is wetted with the adhesive 216 .

Adhesive 216 is a low viscosity epoxy. The adhesive 216 can have a viscosity of less than 10,000 mPas. The adhesive 216 can be filled with glass beads, quartz powder mixtures or the like, for example. The adhesive 216 has an adhesive gap thickness d. The adhesive gap thickness d is defined as a distance between the rear side 208 of the optical element 202 and the front side 212 of the component 210. The adhesive gap thickness d can be a few μm to a few tenths of a mm.

The gluing of the component 210 onto the optical element 202 is explained below. First, the adhesive application surfaces, namely the back 208 and the front 212, are surface treated. The surface treatment can include roughening and/or degreasing, for example.

As the 3 shows, the component 210 and the optical element 202 are installed in a device 218 which is set up to align the component 210 and the optical element 202 with one another. In particular, the device 218 is set up to align the component 210 relative to the optical element 202 . The component 210 has six degrees of freedom, namely three translational degrees of freedom in each case along the directions x, y, z and three rotational degrees of freedom in each case about the directions x, y, z. The device 218 is suitable for positioning the component 210 in all six degrees of freedom.

The component 210 is aligned with the optical element 202 in such a way that an adhesive gap 220 is provided between the rear side 208 of the optical element 202 and the front side 212 of the component 210 . The adhesive gap 220 has a constant adhesive gap thickness d over the entire front side 212 of the component 210, as explained above. This means that the adhesive gap thickness d is identical for each point on the front side 212 . The alignment of the component 210 relative to the optical element 202 can be checked using a measuring system 222 . The measuring system 222 can be part of the device 218 .

The adhesive 216 is then applied. For this purpose, a centrally arranged dosing point 224 is provided on the component 210 , through which the adhesive 216 is applied into the adhesive gap 220 with the aid of a dosing needle 226 . The dosing point 224 is a dosing bore that breaks through the component 210 . The adhesive 216 is applied in such a way that it contacts the rear side 208 of the optical element 202 and the front side 212 of the component 210 at the same time. As a result, the adhesive 216 is drawn into the adhesive gap 220 due to the capillary effect until the complete front side 212 of the component 210 and a part of the rear side 208 of the optical element 202 arranged opposite the front side 212 is wetted with the adhesive 216 .

The adhesive is applied in several consecutive short time intervals. The progression of the adhesive 216 in the adhesive gap 220 is in FIG 4 indicated by reference numerals 216' to 216'''. In order to avoid unwanted air inclusions, the adhesive 216 is supplied exclusively through the dosing point 224. Starting from the dosing point 224 , the adhesive 216 then spreads outwards in a circle away from the axis of symmetry 204 .

The progress of the wetting or the quality of the wetting can be detected or monitored using a sensor element 228 . The sensor element 228 is a camera facing the front side 206 of the optical element 202 . The sensor element 228 is suitable for detecting the adhesive 216 through the optical element 202 . For this purpose, the optical element 202 is transparent before the optically active surface is applied to the front side 206 . This means that the optically effective surface is only applied to the optical element 202 after the component 210 has been glued on. The sensor element 228 can be part of the device 218 .

The alignment or positioning of the component 210 relative to the optical element 202 can then be checked again. This can be done using the measurement system 222 . The adhesive 216 then hardens or sets or is hardened or set. If necessary, the alignment or positioning of the component 210 relative to the optical element 202 can then be checked again. Advantageously, 100% wetting can be achieved by using the capillary effect. The adhesive 216 is prevented from escaping from the adhesive gap 220 . The emergence of the adhesive 216 can be prevented in particular by a suitable choice of an applied amount of adhesive.

the 5 and 6 show an alternative way of applying the adhesive 216. According to the 5 and 6 the adhesive 216 is not introduced into the adhesive gap 220 through a central dosing point 224, but rather at a dosing point 230 provided on the edge of the component 210. The dosing point 230 can be a corner of the component 210, for example. In this case, too, the adhesive 216 is applied to only one dosing point 230 with the aid of the dosing needle 226 . The adhesive 216 is then sucked into the adhesive gap 220 by capillary action. The adhesive 216 spreads out from the dosing point 230 starting in a circle, as in FIG 6 with the aid of reference numerals 216', 216'', 216'''. Otherwise, the bonding of the component 210 and the optical element 202 as before with reference to FIG 3 and 4 explained, carried out.

the 7 shows a schematic block diagram of an embodiment of a method for gluing the component 210 to the optical element 202. In the method, in a step S1, the component 210 is positioned relative to the optical element 202 such that between the component 210 and the optical element 202 Adhesive gap 220 is provided. The adhesive 216 is applied into the adhesive gap 220 in a step S2. In a step S3, the adhesive 216 is distributed independently with the aid of the capillary effect. In the present case, “independently” or “automatically” means that the adhesive 216 fills the adhesive gap 220 by itself without external influence.

Although the present invention has been described using exemplary embodiments, it can be modified in many ways.

Reference List

100A

EUV lithography system

100B

DUV lithography system

102

Beam shaping and lighting system

104

projection system

106A

EUV light source

106B

DUV light source

108A

EUV radiation

108B

DUV radiation

110

mirror

112

mirror

114

mirror

116

mirror

118

mirror

120

photomask

122

mirror

124

wafers

126

optical axis

128

lens

130

mirror

132

medium

200

optical system

202

optical element

204

axis of symmetry

206

front

208

back

210

component

212

front

214

back

216

adhesive

216'

adhesive

216''

adhesive

216'''

adhesive

218

contraption

220

glue gap

222

measuring system

224

dosing point

226

dosing needle

228

sensor element

230

dosing point

i.e

adhesive gap thickness

M1

mirror

M2

mirror

M3

mirror

M4

mirror

M5

mirror

M6

mirror

S1

step

S2

step

S3

step

x

x direction

y

y direction

e.g

z direction

Claims (10)

Method for gluing a component (210) with an optical element (202), with the steps: a) positioning (S1) of the component (210) relative to the optical element (202) such that between an adhesive gap (220) is provided between the component (210) and the optical element (202), b) application (S2) of an adhesive (216) into the adhesive gap (220), and c) independent distribution (S3) of the adhesive (216 ) in the gluing gap (220) by means of the capillary effect. procedure after claim 1 , wherein in step b) the adhesive (216) is applied to the adhesive gap (220) in a plurality of successive time intervals. procedure after claim 1 or 2 , wherein in step b) the adhesive (216) is applied to exactly one dosing point (224, 230) in the adhesive gap (220). procedure after claim 3 , wherein the adhesive (216), starting from the dosing point (224, 230), spreads out in a circle in the adhesive gap (220). procedure after claim 3 or 4 , wherein the dosing point (224) is provided centrally on the component (210), or wherein the dosing point (230) is provided at the edge of the component (210). Procedure according to one of Claims 1 - 5 , wherein in step a) the component (210) is positioned relative to the optical element (202) in such a way that the adhesive gap (220) has a constant adhesive gap thickness (d). Procedure according to one of Claims 1 - 6 , wherein in step c) the independent distribution of the adhesive (216) in the adhesive gap (220) is monitored with the aid of a sensor element (228), in particular a camera. procedure after claim 7 , wherein the independent distribution of the adhesive (216) in the adhesive gap (220) is monitored through the optical element (202) with the aid of the sensor element (228). Procedure according to one of Claims 1 - 8th , wherein the component (210) and the optical element (202) are spherically curved, and wherein the component (210) is glued to the rear of the optical element (202). Procedure according to one of Claims 1 - 9 , wherein the adhesive (216) is a low-viscosity epoxy resin, in particular a low-viscosity filled epoxy resin.

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