DE102013204453B4 - Optical system for a microlithographic projection exposure apparatus, microlithographic projection exposure apparatus and method for the microlithographic production of microstructured components - Google Patents

Abstract

An optical system for a microlithographic projection exposure apparatus comprising an optical system axis (OA) and a polarization-influencing optical device, wherein the polarization-influencing optical device (200, 300) comprises: a first polarization-influencing element (220, 320) made of optically uniaxial crystal material and a first orientation of the optical crystal axis perpendicular to the optical system axis (OA) and a thickness varying in the direction of the optical system axis (OA); and a second polarization-influencing element (230, 330) arranged in the light propagation direction after the first polarization-influencing element (220, 320), which is made of optically uniaxial crystal material and has a second orientation of the optical crystal axis perpendicular to the optical system axis (OA) and a plane-parallel geometry wherein the second orientation is different from the first orientation, wherein the polarization-influencing optical device (200, 300) converts a constant linear input polarization distribution of light incident on the device (200, 300) to an output polarization distribution having a polarization direction continuously varying across the light beam cross-section ,

Description

The invention relates to an optical system for a microlithographic projection exposure apparatus.

Microlithographic projection exposure equipment is used to fabricate microstructured devices such as integrated circuits or LCDs. Such a projection exposure apparatus has an illumination device and a projection objective. In the microlithography process, the image of a mask (= reticle) illuminated by means of the illumination device is projected onto a photosensitive layer (photoresist) coated with a photosensitive layer (photoresist) and arranged in the image plane of the projection objective (eg, a silicon wafer) to project the mask structure onto the photosensitive layer Transfer coating of the substrate.

In the operation of a microlithographic projection exposure machine, there is a need to provide defined lighting settings, i. Intensity distributions in a pupil plane of the lighting device to set targeted. Furthermore, various approaches are known for setting specific polarization distributions in the illumination pupil in the illumination device in order to optimize the imaging contrast.

Both in the illumination device and in the projection objective, it is known in particular to set a tangential polarization distribution for a high-contrast image.

"Tangential polarization" (or "TE polarization") is understood to mean a polarization distribution in which the oscillation planes of the electric field strength vectors of the individual linearly polarized light beams are oriented approximately perpendicular to the radius directed onto the optical system axis. By contrast, "radial polarization" (or "TM polarization") is understood to mean a polarization distribution in which the oscillation planes of the electric field strength vectors of the individual linearly polarized light beams are oriented approximately radially to the optical system axis. Accordingly, a quasi-tangential or a quasi-radial polarization distribution is understood as meaning a polarization distribution in which the above criteria are at least approximately fulfilled.

The prior art is for example WO 2005/069081 A2 . WO 2005/031467 A2 . US 6,191,880 B1 . US 2007/0146676 A1 . WO 2009/034109 A2 . WO 2008/019936 A2 . WO 2009/100862 A1 . DE 10 2008 009 601 A1 . DE 10 2004 011 733 A1 . EP 1 306 665 A2 . JP 2010-141091 A such as DE 10 2007 055 567 A1 directed.

The object of the present invention is to provide an optical system for a microlithographic projection exposure apparatus which enables the generation of a desired polarization distribution in the projection exposure apparatus in a comparatively simple manner.

This object is achieved according to the features of independent claim 1.

• - ein erstes polarisationsbeeinflussendes Element, welches aus optisch einachsigem Kristallmaterial hergestellt ist und eine zur optischen Systemachse senkrechte erste Orientierung der optischen Kristallachse und eine in Richtung der optischen Systemachse variierende Dicke aufweist; und
• - ein in Lichtausbreitungsrichtung nach dem ersten polarisationsbeeinflussenden Element angeordnetes zweites polarisationsbeeinflussendes Element, welches aus optisch einachsigem Kristallmaterial hergestellt ist und eine zur optischen Systemachse senkrechte zweite Orientierung der optischen Kristallachse und eine planparallele Geometrie aufweist, wobei die zweite Orientierung von der ersten Orientierung verschieden ist;
• - wobei die polarisationsbeeinflussende optische Anordnung eine konstant lineare Eingangspolarisationsverteilung von auf die Anordnung auftreffendem Licht in eine Ausgangspolarisationsverteilung mit über den Lichtbündelquerschnitt kontinuierlich variierender Polarisationsrichtung umwandelt.

An optical system according to the invention for a microlithographic projection exposure apparatus has an optical system axis and a polarization-influencing optical arrangement, the polarization-influencing optical arrangement having:

• a first polarization-influencing element, which is produced from optically uniaxial crystal material and has a first orientation, which is perpendicular to the optical system axis, of the optical crystal axis and a thickness which varies in the direction of the optical system axis; and
• a second polarization-influencing element arranged in the light propagation direction after the first polarization-influencing element, which is made of optically uniaxial crystal material and has a second orientation of the optical crystal axis perpendicular to the optical system axis and a plane-parallel geometry, the second orientation being different from the first orientation;
• wherein the polarization-influencing optical arrangement converts a constant linear input polarization distribution of light incident on the array into an output polarization distribution with a polarization direction continuously varying over the light beam cross-section.

The invention is based on the consideration that in principle by combination of three linear retarders (ie of three polarization-influencing optical elements, which due to linear birefringence retardation or delay, ie cause an optical path difference between two orthogonal or mutually perpendicular polarization states) depending on Embodiment of this linear retarder can be physically realized any elliptical retarder. Here, an "elliptical retarder" is understood to mean the generalized definition of a polarization-influencing optical element, as the rotation of a predetermined rotation caused by such an elliptical retarder Polarization state on the Poincare sphere can be arbitrary.

The underlying concept of the Poincare sphere is in 5 shown schematically. Here, a linear retarder has the effect of a rotation of a polarization state on the Poincare sphere about an axis which lies in the equatorial plane of the Poincare sphere (for example about the axis "A" or "B" in FIG 5 ). Mathematically, it can now be shown that any elliptical retarder (which indicates the rotation of a polarization state on the Poincare sphere about an arbitrary axis, eg the axis "D" in FIG 5 causes) can be realized by combining three linear retarders each having a predetermined, constant direction of the fast axis of the birefringence or the optical crystal axis.

Based on the above consideration, the invention is now based in particular on the concept of a continuous over the light beam cross-section variations in polarization direction (ie the effect of a rotator with continuously varying polarization rotation angle, corresponding to a rotation of a polarization state on the Poincare sphere about the axis "C" in FIG 5 ) by a combination of a maximum of three linear retarders. On the one hand, it is possible to dispense with the utilization of optical activity or the use of optically active materials, and on the other hand, it is possible to resort to naturally available crystal material with in each case uniform orientation of the optical crystal axis with regard to the retarders used (in particular no local variation of the direction of the optical) Crystal axis must be set in each material).

wobei Δϕ die Phasenverzögerung (welche sich durch Multiplikation des optischen Wegunterschiedes für orthogonale Polarisationszustände mit 2π/Lambda ergibt, wobei Lambda die Arbeitswellenlänge bezeichnet) und β den Winkel der optischen Kristallachse bezeichnen.In principle, a general linear retarder can be described by the following Jones matrix J: $$J=\left(\begin{array}{cc}\text{cos}\frac{\Delta \phi }{2}-i\text{sin}\frac{\Delta \mathrm{<figure-callout\; id="2"\; label="\phi "\; filenames="DE102013204453B4\_0010.png"\; state="\{\{state\}\}">\phi </figure-callout>}}{2}\cdot \text{<figure-callout id="2" label="cos" filenames="DE102013204453B4\_0010.png" state="{{state}}">cos</figure-callout>}2\beta & -i\text{sin}\frac{\mathrm{<figure-callout\; id="2"\; label="\Delta \; \phi "\; filenames="DE102013204453B4\_0010.png"\; state="\{\{state\}\}">\Delta \; </figure-callout>}\phi }{2}\cdot \text{<figure-callout id="2" label="sin" filenames="DE102013204453B4\_0010.png" state="{{state}}">sin</figure-callout>}2\beta \\ -i\text{sin}\frac{\Delta \mathrm{<figure-callout\; id="2"\; label="\phi "\; filenames="DE102013204453B4\_0010.png"\; state="\{\{state\}\}">\phi </figure-callout>}}{2}\cdot \text{<figure-callout id="2" label="sin" filenames="DE102013204453B4\_0010.png" state="{{state}}">sin</figure-callout>}2\beta & \text{<figure-callout id="2" label="cos Δ φ" filenames="DE102013204453B4\_0010.png" state="{{state}}">cos </figure-callout>}\frac{\Delta \phi }{}\frac{}{2}+i\text{sin}\frac{\Delta \phi }{2}\cdot \text{<figure-callout id="2" label="cos" filenames="DE102013204453B4\_0010.png" state="{{state}}">cos</figure-callout>}2\beta \end{array}\right)$$

where Δφ denotes the phase delay (which results from multiplying the optical path difference for orthogonal polarization states by 2π / lambda, where lambda denotes the working wavelength) and β denoting the angle of the optical crystal axis.

The Jones matrix J _{target of} a rotator aimed at according to the invention is general $$J_{tarGet}=\left(\begin{array}{cc}\text{cos}\alpha & -\text{sin}\alpha \\ \text{sin}\alpha & \text{cos}\alpha \end{array}\right)$$

wobei J₁ die Jones-Matrix eines Retarders mit β=0° und Phasenverzögerung Δϕ₁, d.h. $$J_1=\left(\begin{array}{cc}\text{exp}\left(-i\Delta {\varphi }_1/2\right)& 0\\ 0& \text{exp}\left(+i\Delta {\varphi }_1/2\right)\end{array}\right)$$

According to the invention, the following approach of combining three linear retarders, each with a predetermined, constant direction of the fast axis of birefringence, is chosen: $$J_{tarGet}\stackrel{!}{=}{J}_3\cdot {\mathrm{<figure-callout\; id="2"\; label="J"\; filenames="DE102013204453B4\_0010.png"\; state="\{\{state\}\}">J</figure-callout>}}_2\cdot J_1$$

where J _{1 is} the Jones matrix of a retarder with β = 0 ° and phase delay Δφ ₁ , ie $$J_1=\left(\begin{array}{cc}\text{exp}\left(-i\Delta {\phi }_1/2\right)& 0\\ 0& \text{exp}\left(+i\Delta {\phi }_1/2\right)\end{array}\right)$$

und J₃ die Jones-Matrix eines Retarders mit β=0° und Phasenverzögerung Δϕ₃, d.h. $$J_3=\left(\begin{array}{cc}\text{exp}\left(-i\Delta {\varphi }_3/2\right)& 0\\ 0& \text{exp}\left(+i\Delta {\varphi }_3/2\right)\end{array}\right)$$

bezeichnen.J ₂ the Jones matrix of a retarder with β = 45 ° and phase delay Δφ ₂ , ie $$J_{}$$$${}_2=\left(\begin{array}{cc}\text{cos}\left(\mathrm{<figure-callout\; id="2"\; label="\Delta \; \phi "\; filenames="DE102013204453B4\_0010.png"\; state="\{\{state\}\}">\Delta \; </figure-callout>}{\phi }_{}{}_2/2\right)& -i\text{sin}\left(\mathrm{<figure-callout\; id="2"\; label="\Delta \; \phi "\; filenames="DE102013204453B4\_0010.png"\; state="\{\{state\}\}">\Delta \; </figure-callout>}{\phi }_{}{}_2/2\right)\\ -i\text{sin}\left(\mathrm{<figure-callout\; id="2"\; label="\Delta \; \phi "\; filenames="DE102013204453B4\_0010.png"\; state="\{\{state\}\}">\Delta \; </figure-callout>}{\phi }_{}{}_2/2\right)& \text{cos}\left(\mathrm{<figure-callout\; id="2"\; label="\Delta \; \phi "\; filenames="DE102013204453B4\_0010.png"\; state="\{\{state\}\}">\Delta \; </figure-callout>}{\phi }_{}{}_2/2\right)\end{array}\right)$$

and J ₃ the Jones matrix of a retarder with β = 0 ° and phase delay Δφ ₃ , ie $$J_3=\left(\begin{array}{cc}\text{exp}\left(-i\Delta {\phi }_3/2\right)& 0\\ 0& \text{exp}\left(+i\Delta {\phi }_3/2\right)\end{array}\right)$$

describe.

woraus sich die folgende Lösung für die jeweiligen Phasenverzögerungen Δϕ₁, Δϕ₂, und Δϕ₃ ergibt: $$\Delta {\varphi }_1=-\frac{\pi }{2},\Delta {\varphi }_2=2\alpha ,\Delta {\varphi }_3=\frac{\pi }{2}$$

From (4) - (6) follows: $$\begin{array}{c}{J}_3\cdot {\mathrm{<figure-callout\; id="2"\; label="J"\; filenames="DE102013204453B4\_0010.png"\; state="\{\{state\}\}">J</figure-callout>}}_2\cdot {\mathrm{<figure-callout\; id="2"\; label="J"\; filenames="DE102013204453B4\_0010.png"\; state="\{\{state\}\}">J</figure-callout>}}_2=\left(\begin{array}{cc}\text{exp}\left(-\frac{i}{2}\left(\Delta {\phi }_1+\Delta {\phi }_3\right)\right)\cdot \text{cos}\left(\Delta {\mathrm{<figure-callout\; id="2"\; label="\phi "\; filenames="DE102013204453B4\_0010.png"\; state="\{\{state\}\}">\phi </figure-callout>}}_2/2\right)& -i\text{exp}\left(\frac{i}{2}\left(\Delta {\phi }_1-\Delta {\phi }_3\right)\right)\cdot \text{sin}\left(\Delta {\mathrm{<figure-callout\; id="2"\; label="\phi "\; filenames="DE102013204453B4\_0010.png"\; state="\{\{state\}\}">\phi </figure-callout>}}_2/2\right)\\ -i\text{exp}\left(-\frac{i}{2}\left(\Delta {\phi }_1-\Delta {\phi }_3\right)\right)\cdot \text{sin}\left(\Delta {\mathrm{<figure-callout\; id="2"\; label="\phi "\; filenames="DE102013204453B4\_0010.png"\; state="\{\{state\}\}">\phi </figure-callout>}}_2/2\right)& \text{exp}\left(\frac{i}{2}\left(\Delta {\phi }_1+\Delta {\phi }_3\right)\right)\cdot \text{cos}\left(\mathrm{<figure-callout\; id="2"\; label="\Delta \; \phi "\; filenames="DE102013204453B4\_0010.png"\; state="\{\{state\}\}">\Delta \; </figure-callout>}{\phi }_{}{}_2/2\right)\end{array}\right)\\ \stackrel{!}{=}\left(\begin{array}{cc}\text{cos}\alpha & -\text{sin}\alpha \\ \text{sin}\alpha & \text{cos}\alpha \end{array}\right)\end{array}$$

from which the following solution results for the respective phase delays Δφ ₁ , Δφ ₂ , and Δφ ₃ : $$\Delta {\phi }_1=-\frac{\mathrm{<figure-callout\; id="2"\; label="\pi "\; filenames="DE102013204453B4\_0010.png"\; state="\{\{state\}\}">\pi </figure-callout>}}{2}.\mathrm{<figure-callout\; id="2"\; label="\Delta \; \phi "\; filenames="DE102013204453B4\_0010.png"\; state="\{\{state\}\}">\Delta \; </figure-callout>}{\phi }_{}{}_2=2\alpha .\Delta {\phi }_3=\frac{\mathrm{<figure-callout\; id="2"\; label="\pi "\; filenames="DE102013204453B4\_0010.png"\; state="\{\{state\}\}">\pi </figure-callout>}}{2}$$

The solution according to (8) thus corresponds to a polarization-influencing optical arrangement of a lambda / 4 plate with a 90 ° orientation of the optical crystal axis (relative to a given direction, eg the y-direction in a fixed coordinate system), a linear retarder with a 45 ° orientation of the optical crystal axis (based on the predetermined direction, eg the y-direction) and a phase delay of Δφ ₂ = 2α and another lambda / 4 plate with a 0 ° orientation of the optical crystal axis (relative to the predetermined direction, eg the y -Direction). For the generation of a location-dependent varying polarization rotation angle α according to the invention, therefore, the said linear retarder with the 45 ° orientation of the optical crystal axis also has a phase-dependent Δφ ₂ varying over the light bundle cross-section.

Specifically, a polarization-influencing optical arrangement used according to the invention for effective formation of a rotator with a polarization rotation angle varying over the light bundle cross section includes at least two linear retarders, one of which has a thickness profile varying in the light propagation direction or in the direction of the optical system axis, and the further following in the light propagation direction Retarder has a plane-parallel geometry, and wherein these two linear retarder each have to the optical system axis perpendicular, mutually different orientations of the optical crystal axis.

Depending on the specific nature of the input polarization distribution of the light impinging on the polarization-influencing optical arrangement according to the invention, a third linear retarder can also be used to achieve the desired output polarization distribution as further explained below, which likewise has a plane-parallel geometry and, with respect to the light propagation direction, before the first and second linear retarder.

According to one embodiment, the first polarization-influencing element and the second polarization-influencing element are arranged directly following one another in the light propagation direction.

In accordance with one embodiment, the polarization-influencing optical arrangement further has a third polarization-influencing element, which is made of optically uniaxial crystal material and has a third orientation of the optical crystal axis perpendicular to the optical system axis and a plane-parallel geometry, arranged in the light propagation direction in front of the first polarization-influencing element.

According to one embodiment, the first, second and third polarization-influencing elements are arranged in the light propagation direction directly one after the other.

According to one embodiment, the second orientation of the optical crystal axis of the second polarization-influencing element and the third orientation of the optical crystal axis of the third polarization-influencing element extend perpendicular to one another.

According to one embodiment, the first orientation of the optical crystal axis of the first polarization-influencing element extends at an angle of magnitude 45 ° ± 5 ° to the second orientation of the optical crystal axis of the second polarization-influencing element and the third orientation of the optical crystal axis of the third polarization-influencing element.

According to one embodiment, the first polarization-influencing element has a wedge-shaped or wedge-segment-shaped geometry.

According to one embodiment, the first polarization-influencing element has a thickness profile which varies in an azimuthal direction relative to the optical system axis and is constant in a radial direction relative to the optical system axis.

According to one embodiment, the second polarization-influencing element has a delay of lambda / 4, wherein lambda denotes the operating wavelength of the optical system.

According to one embodiment, the third polarization-influencing element has a delay of lambda / 4, where lambda denotes the operating wavelength of the optical system.

In one embodiment, the optically uniaxial crystal material is selected from the group consisting of magnesium fluoride (MgF ₂ ), sapphire (Al ₂ O ₃ ), and crystalline quartz (SiO ₂ ).

According to one embodiment, the polarization-influencing optical arrangement converts a constant linear input polarization distribution of light incident on the array into an at least approximately tangential output polarization distribution.

According to one embodiment, the polarization-influencing optical arrangement is arranged in a pupil plane of the optical system.

The invention further relates to a microlithographic projection exposure apparatus and to a method for microlithographic production of microstructured components.

Further embodiments of the invention are described in the description and the dependent claims.

The invention will be explained in more detail with reference to embodiments shown in the accompanying drawings.

• 1 eine schematische Darstellung des möglichen Aufbaus einer mikrolithographischen Projektionsbelichtungsanlage;
• 2-4 schematische Darstellungen zur Erläuterung des Aufbaus und der Funktionsweise von Ausführungsformen einer polarisationsbeeinflussenden optischen Anordnung gemäß der vorliegenden Erfindung; und
• 5 eine schematische Darstellung der Poincaré-Kugel zur Erläuterung der Wirkungsweise unterschiedlicher Retarder.

Show it:

• 1 a schematic representation of the possible structure of a microlithographic projection exposure system;
• 2-4 schematic diagrams for explaining the structure and operation of embodiments of a polarization-influencing optical arrangement according to the present invention; and
• 5 a schematic representation of the Poincaré sphere for explaining the operation of different retarder.

The following is first referring to 1 in a simplified, schematic representation of a possible structure of a microlithographic projection exposure system explained.

The microlithographic projection exposure machine 100 according to 1 has a light source unit 101 , a lighting device 102 , a structure-wearing mask 103 , a projection lens 104 and a substrate to be exposed 105 on. The light source unit 101 For example, the light source may include an ArF laser for a working wavelength of 193 nm, and beam shaping optics that generate a parallel pencil of light. One from the light source unit 101 emitted parallel tuft of light first strikes a diffractive optical element (DOE) 106 , The DOE 106 generates a desired intensity distribution, eg dipole or quadrupole distribution, in a pupil plane PP via an angular radiation characteristic defined by the respective diffracting surface structure. One in the beam path on the DOE 106 following objective 108 is designed as a zoom lens, which generates a parallel tuft of light with variable diameter. The parallel tuft of light is through a deflection mirror 109 on an axicon 111 directed. Through the zoom lens 108 in conjunction with the upstream DOE 106 and the axicon 111 Depending on the zoom position and position of the axicon elements, different illumination configurations are generated in the pupil plane PP.

In the pupil plane PP is according to 1 a polarization-influencing optical arrangement 200 to which possible embodiments hereinafter with reference to 2 ff. be explained.

The lighting device 102 also includes the axicon 111 one in the area of the pupil plane PP (in 1 immediately after) arranged light mixing system 112 which may have, for example, an arrangement of microoptical elements which is suitable for achieving a light mixture. On the light mixing system 112 as well as possibly further (only by a single lens 110 indicated optical components are followed by a reticle masking system (REMA) 113 which is powered by a REMA lens 114 on the reticle 103 and thereby the illuminated area on the reticle 103 limited. The reticle 103 becomes with the projection lens 104 on the photosensitive substrate 105 displayed. Between a last optical element 115 of the projection lens 104 and the photosensitive substrate 105 In the example shown, there is an immersion liquid 116 with a refractive index different from air.

In further embodiments, the illumination device 102 to produce different lighting configurations also have a well-known mirror assembly with a plurality of independently adjustable mirror elements, such as from WO 2005/026843 A2 known.

In the following, possible embodiments of the according to 1 in the pupil plane PP located polarization-influencing optical arrangement 200 with structure and operation with reference to Fig. 2ff. explained.

According to 2 has the polarization-influencing optical arrangement 200 In a first embodiment, a wedge-segment-shaped polarization-influencing optical element 220 (hereinafter also referred to as "first polarization-influencing element") with in the light propagation direction (corresponding to the z-direction in the drawn coordinate system) varying thickness between two plane-parallel polarization-influencing optical elements 210 and 230 with respect to the light propagation direction immediately before or after the (first) wedge-segment-shaped polarization-influencing optical element 220 are arranged.

The polarization-influencing elements 210 . 220 and 230 are each made of optically uniaxial crystal material with sufficient transmission at the respective operating wavelength transmission, for example, from magnesium fluoride (MgF ₂ ), sapphire (Al ₂ O ₃ ) or crystalline quartz (SiO ₂ ) at an exemplary operating wavelength of about 193 nm. For these materials, the difference between the extraordinary refractive index n _e and the ordinary refractive index n _o is n _e -n _o (SiO ₂ ) ≅ + 0.013, n _e -n _o (Al ₂ O ₃ ) ≅-0.011 and n _e, respectively -n _o (MgF ₂ ) ≅ + 0.014.

In the concrete embodiment is for the polarization-influencing elements 210 and 230 the delay (constant due to the plane-parallel configuration across the light bundle cross section) is lambda / 4, where lambda denotes the operating wavelength of the optical system. The direction of the optical crystal axis is for the polarization-influencing optical elements 210 . 220 and 230 in 2 each symbolized by the double arrows shown and runs in the concrete embodiment with respect to the drawn coordinate system for the element 210 parallel to the y-direction, for the element 230 parallel to the x-direction and for the element 220 at an angle of 45 ° to the x or y direction.

Also in 2 is indicated by the polarization-influencing optical arrangement 200 Overall polarization rotation angle α achieved in a specific embodiment, which varies in the concrete embodiment over the light beam cross section along the y-direction between 0 ° and 90 °, which in particular by the wedge-shaped configuration of the polarization-influencing element 220 is effected.

The polarization-influencing optical arrangement described above 200 realized generation of location-dependent or over the light beam cross-section continuously varying polarization states can be used, for example, by suitable distribution of these polarization states (eg, using a mirror array with a plurality of independently adjustable mirror elements) to produce a desired polarized illumination setting in the illumination device. In other applications, an at least partial compensation of an undesired disturbance of the polarization state present in the illumination device or in the projection objective can also be effected.

In addition, with reference to 3 and 4 the structure and operation of a polarization-influencing optical arrangement 300 explained according to another embodiment of the present invention.

The polarization-influencing optical arrangement 300 serves as in 3 indicated to have a constant linear input polarization distribution 305 in an at least approximately tangential output polarization distribution 335 convert. In contrast to the polarization-influencing optical arrangement 200 out 2 is in the polarization-influencing optical arrangement 300 the mean polarization-influencing optical element 320 not formed wedge-segment-shaped, but has a thickness profile, which as in 4a, b is varied in azimuthal direction with respect to the optical system axis (ie, the z-direction) and is constant in the radial direction with respect to the optical system axis. In the in 4a schematically illustrated embodiment, the polarization-influencing optical element 320 along a radius R perpendicular to the element axis EA stands and an angle 0 with a reference axis RA forms a constant thickness. The thickness profile in this embodiment is thus only from the azimuth angle 0 dependent. In the center of the polarization-influencing optical element 320 There is a central hole 321 ,

4a shows the exemplary thickness profile in perspective, and 4b shows for this thickness curve, a diagram in which the thickness d is plotted as a function of the azimuth angle Θ. In the exemplary embodiment, the thickness curve has a jump at Θ = 180 °, the thickness difference at this jump corresponding to a delay of lambda (or an integral multiple of lambda). Furthermore, the polarization-influencing optical element 320 in the embodiment composed of two sub-elements or has a segmented structure. However, the invention is not limited thereto. In further embodiments, instead, a construction of more (eg four) segments or even a non-segmented or one-piece structure and a continuously continuous thickness profile (ie without jumping in the thickness profile) can be selected.

The referred to the light propagation direction before or after the element 320 arranged polarization-influencing optical elements 310 and 330 are analogous to the embodiment of 2 designed with plane-parallel geometry and a constant delay of lambda / 4.

The polarization-influencing elements 310 . 320 and 330 can analogously to the embodiment of 2 For example, magnesium fluoride (MgF ₂ ), sapphire (Al ₂ O ₃ ), or crystalline quartz (SiO ₂ ) may be produced at an exemplary operating wavelength of about 193 nm. This is the maximum height difference of the polarization-influencing optical element 320 , which in the thickness profile of the element 320 to provide a delay in the range of -λ / 2 to + λ / 2, approximately in the range of 15μm.

Although in the above with reference to 2 and 3 each described embodiment formed from a combination of three polarization-influencing optical elements array 200 respectively. 300 is used, the invention is not limited thereto. Rather, it should be pointed out that, depending on the nature of the input polarization distribution of the light impinging on the polarization-influencing optical arrangement according to the invention for generating the desired output polarization distribution, two polarization-influencing optical elements (in the embodiments described above, the elements 220 and 230 respectively. 320 and 330 ) can be sufficient. If, in fact, the input polarization distribution of the light impinging on the respective polarization-influencing optical arrangement is constantly linear (for example with a polarization direction running in the y-direction), a lambda / 4 plate (corresponding to the elements 210 out 2 respectively. 310 out 3 ) with beispielswese also in the y-direction oriented optical crystal axis has no influence on the input polarization distribution (in the example mentioned, the light in the eigenstate on the respective element 210 respectively. 310 incident.

While the invention has been described in terms of specific embodiments, numerous variations and alternative embodiments, e.g. by combination and / or exchange of features of individual embodiments. Accordingly, it will be understood by those skilled in the art that such variations and alternative embodiments are intended to be embraced by the present invention, and the scope of the invention is limited only in terms of the appended claims and their equivalents.

Claims (16)

An optical system for a microlithographic projection exposure apparatus comprising an optical system axis (OA) and a polarization-influencing optical arrangement, the polarization-influencing optical arrangement (200, 300) comprising: A first polarization-influencing element (220, 320) which is produced from optically uniaxial crystal material and has a first orientation of the optical crystal axis perpendicular to the optical system axis (OA) and a thickness varying in the direction of the optical system axis (OA); and A second polarization-influencing element (230, 330) arranged in the direction of light propagation after the first polarization-influencing element (220, 320), which is made of optically uniaxial crystal material and has a second orientation of the optical crystal axis perpendicular to the optical system axis (OA) and a plane-parallel geometry wherein the second orientation is different from the first orientation; Wherein the polarization-influencing optical arrangement (200, 300) converts a constantly linear input polarization distribution of light incident on the arrangement (200, 300) into an output polarization distribution with a continuously varying polarization direction over the light beam cross-section. Optical system after Claim 1 , characterized in that the first polarization-influencing element (220, 320) and the second polarization-influencing element (230, 330) are arranged directly following one another in the light propagation direction. Optical system after Claim 1 or 2 , characterized in that the polarization-influencing optical arrangement (200, 300) further comprises a third polarization-influencing element (210, 310) arranged in the light propagation direction in front of the first polarization-influencing element (220, 320), which is made of optically uniaxial crystal material and one for optical System axis (OA) has vertical third orientation of the optical crystal axis and a plane-parallel geometry. Optical system after Claim 3 , characterized in that the first, second and third polarization-influencing element are arranged directly successively in the direction of light propagation. Optical system according to one of Claims 1 to 4 , characterized in that the second orientation of the optical crystal axis of the second polarization-influencing element (230, 330) and the third orientation of the optical crystal axis of the third polarization-influencing element (210, 310) are perpendicular to each other. Optical system according to one of the preceding claims, characterized in that the first orientation of the optical crystal axis of the first polarization-influencing element (220, 320) at an angle of magnitude 45 ° ± 5 ° to the second orientation of the optical crystal axis of the second polarization-influencing element (230, 330) and for the third orientation of the optical crystal axis of the third polarization-influencing element (210, 310). Optical system according to one of Claims 1 to 6 , characterized in that the first polarization-influencing element (220) has a wedge-segment-shaped geometry. Optical system according to one of Claims 1 to 6 , characterized in that the first polarization-influencing element (320) has a thickness profile which varies in azimuthal direction relative to the optical system axis (OA) and is constant in a radial direction relative to the optical system axis (OA). Optical system according to one of the preceding claims, characterized in that the second polarization-influencing element (230, 330) has a delay of lambda / 4, wherein lambda denotes the operating wavelength of the optical system. Optical system according to one of Claims 3 to 9 , characterized in that the third polarization-influencing element (210, 310) has a delay of lambda / 4, wherein lambda denotes the operating wavelength of the optical system. Optical system according to one of the preceding claims, characterized in that the optically uniaxial crystal material is selected from the group consisting of magnesium fluoride (MgF ₂ ), sapphire (Al ₂ O ₃ ) and crystalline quartz (SiO ₂ ). Optical system according to one of the preceding claims, characterized in that the polarization-influencing optical arrangement (300) converts a constant linear input polarization distribution of light incident on the arrangement into an at least approximately tangential output polarization distribution. Optical system according to one of the preceding claims, characterized in that the polarization-influencing optical arrangement (200, 300) is arranged in a pupil plane of the optical system. Optical system according to one of the preceding claims, characterized in that this is a lighting device (102) of a microlithographic projection exposure apparatus (100). Microlithographic projection exposure apparatus (100) having an illumination device (102) and a projection objective (104), wherein the illumination device (102) is designed according to one of the preceding claims. Method for the microlithographic production of microstructured components, comprising the following steps: providing a substrate (105) on which at least partially a layer of photosensitive material is applied; Providing a mask (103) having structures to be imaged; Providing a microlithographic projection exposure apparatus (100) Claim 15 ; and projecting at least a portion of the mask onto a region of the layer using the projection exposure apparatus.

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