EP1468333A2

EP1468333A2 - Method for constructing an optical beam guide system in a contamination-free atmosphere and universal optical module for said construction

Info

Publication number: EP1468333A2
Application number: EP02795052A
Authority: EP
Inventors: Thomas Dressler
Original assignee: Jenoptik Optical Systems GmbH
Current assignee: Jenoptik Optical Systems GmbH
Priority date: 2002-01-24
Filing date: 2002-12-20
Publication date: 2004-10-20
Also published as: WO2003062926A2; US20050105855A1; JP2005516385A; WO2003062926A3; DE10296357D2; WO2003062926A8; AU2002360927A1

Abstract

The invention relates to a method for constructing an optical beam guide system in a contamination-free atmosphere and a universal optical module for said construction. The aim of the invention is to prevent contamination of the optical imaging elements during handling, assembly and adjustment. According to the invention, the imaging element is fixated aligned relative to a first reference of a support on said support outside the contamination-free atmosphere of the beam guide system, with its optical axis protected against atmospheric influences. The support, protected against atmospheric influences, is introduced into the contamination-free atmosphere of the beam guide system together with the imaging element and is fastened on the recording element, with the first reference aligned with a second reference of a recording element, thereby aligning the optical axis of the imaging element in the beam guide system. The method and the optical module according to the invention are especially suitable for applications where optical systems have to be positioned in a beam guide system ready for instantaneous use and protected from environmental influences.

Description

Process for building an optical beam delivery system in a contamination-free atmosphere and universal optics module for building

The invention relates to a method for constructing an optical beam guidance system in a contamination-free atmosphere by equipping it with optical imaging elements, and furthermore to a universal optical module with a carrier plate for receiving at least one optical imaging element in a receiving plane.

In optical lithography, it is known that chip structures are transferred to a wafer using a mask and light. While special lasers generate the wavelengths necessary for high resolution, high-resolution projection lenses serve to image the structures, the high-resolution lenses contained therein becoming increasingly important due to ever smaller chip structures.

The fundamental physical connection between the achievable resolution and the working wavelength of the exposure radiation requires the use of increasingly shorter-wave radiation sources in the DUN, VUV and in the future in the EUV.

With the transition to ever shorter wavelengths, new materials, such as calcium fluoride, which are sufficiently transparent for these wavelengths and resistant to the radiation used, are required.

In addition, more and more gas components in our natural atmosphere (oxygen, water vapor, hydrocarbons) have a strong effect on the shorter wavelengths Absorbing and contamination of the optical surfaces with these gas components impair the transmission and the service life of the optical imaging elements and thus the transmission in the optical beam path.

For this reason, such optical beam guidance systems must be surrounded by a contamination-free atmosphere by flushing with high-purity gases or the systems are in a vacuum.

The problem of assembly, handling and, in particular, adjustment of the optical imaging elements under the conditions of the contamination-free atmosphere has not yet been satisfactorily resolved, which is necessary both when first setting up an optical beam guidance system and when replacing individual elements due to wear and tear due to high laser radiation exposure.

The object of the invention is therefore to solve the existing problem, in particular to avoid contamination of the optical imaging elements that occurs during handling, assembly and adjustment measures.

According to the invention, the object is achieved by a method of the type mentioned at the outset in that the imaging element is outside the contamination-free atmosphere of the

Beam guidance system with its optical axis protected against atmospheric influences relative to a first reference of a carrier is fixed on the carrier, and that the carrier, together with the imaging element, is protected from atmospheric influences in the contamination-free atmosphere of the

Bring beam delivery system and aligned with the first reference to a second reference of a receiving element on the receiving element, whereby an alignment of the optical axis of the imaging element takes place in the beam guide system.

It is particularly advantageous if the alignment of the optical axis of the imaging element is based on an adjustment template.

It is also advantageous that cleaning / decontamination of the imaging element and the carrier can be carried out outside the contamination-free atmosphere of the optical beam guidance system.

When transferred to the projection beam path of the beam guiding system, which is protected from environmental influences, the optical imaging element can be functionally mounted immediately with a high reproducibility of the adjustment, without the need for readjustments under the conditions there and additional time-consuming decontamination steps. Complex gas and vacuum-tight bushings for control elements and time-consuming decontamination processes in the arrangement can be avoided.

A transfer of the carrier with the imaging element can, for. B. with the help of a transport container and a lock system, as proposed in DE 101 64 529.5. The costly optical imaging elements, which are loaded with laser radiation, can be easily replaced together with the carrier plate and sent to a reprocessing process. The optical imaging elements loaded by laser radiation can be polished and re-coated in such a process. The re-polished and newly coated optical imaging elements can be stored protected in the pre-adjusted state so that they can be used again in a beam guidance system if necessary.

The invention further relates to a universal optical module of the type mentioned at the outset, in which the carrier plate carries the optical imaging element with its optical axis aligned with an axis with a predetermined axis direction and the axis has a fixed spatial arrangement with a reference connected to the carrier plate which the support plate can be positioned.

In the case of a predetermined axial direction running perpendicular to the receiving plane, contact surfaces are incorporated into the carrier plate as a reference, which are aligned with one another in a common plane parallel to the receiving plane.

It has an advantageous effect if the contact surfaces are embedded in the support plate as balls in a triple formation.

To adjust the optical imaging element, the carrier plate contains at least one actuating element which engages the optical imaging element with a torsion-free stop using an adjustable stop. The rotational movement and the resulting disruptive influence on the optics due to the rubbing movement of adjoining surfaces, such as occur with the sensitive adjusting screws that are usually used, is avoided by attaching the adjustable stop to a lever arm of a solid-state joint that is opposite a fixed one Part is adjustable by an adjusting spindle acting on the lever arm.

The adjusting spindle is biased and locked by a compression spring which is supported on the lever arm and on a pressure sleeve fastened in a spindle bearing in the fixed part. This is advantageous because the loose parts are removed from the spindle by connecting the prestressed adjusting spindle to the lever arm of the solid-state joint. The adjustable linear position can be achieved in increments of 0.3 to 0.4 mm. In this way, an adjustment of the optical imaging element required for adjustment can take place particularly advantageously parallel to the receiving plane of the carrier plate.

Contamination of the optical surface is finally also reduced by the fact that the adjusting spindle and a fine thread that is used to grip the lever arm are provided with a special coating that minimizes frictional forces, which itself does not release any particles and which enables lubricant-free working.

The invention will be explained below with reference to the schematic drawing. Show it: Fig. 1 is a plan view of an optics module with a cylindrical lens attached to it adjusted

Fig. 2 shows a section A-A through the optics module

Fig. 3 is a plan view of an actuator for adjusting an optical imaging element attached to the optical module

Fig. 4 is a front view of the actuator

Fig. 5 shows a section A-A through the actuator

Fig. 6 is a sectional view through a modular protective housing part for receiving an optical imaging element for a beam guiding system and a transport container docked to the protective housing part

The universal optics carrier shown in Fig. 1 is provided according to the invention for an optical imaging element 2, such as. B to accommodate an optically imaging and beam-shaping spherical or cylindrical lens or in particular also an asymmetrically designed imaging element and to serve to equip a projection beam path enclosed by a contamination-free atmosphere.

Of course, the optical module is also for other optical imaging elements, such as. B. Apertures, gratings, prisms, mirrors and beam splitters or test tools and sensors are suitable. For this purpose, the optical imaging element 2 is protected outside of the contamination-free atmosphere of the beam guidance system with its optical axis protected from atmospheric influences with the aid of an adjustment device (not shown) using an adjustment template to an axis XX with a predetermined axis direction, which is in a fixed spatial relationship to one with the carrier plate 1 connected reference and is perpendicular to a recording plane EE, in which supports 3 for the optical imaging element 2 are arranged. In the present exemplary embodiment, the reference is embodied by mutually aligned contact surfaces 4, 5 and 6, which are embedded in the support plate 1 as balls in a triple formation in a common plane BB lying parallel to the receiving plane EE. The spherical contact surfaces 4, 5 and 6 serve to position the support plate 1 both in relation to the adjustment template in the adjustment device and when mounting the support plate 1 in the beam guidance system. On the carrier plate 1, a fastening element 7 with an incorporated screw-in thread 8 is provided for a manipulator, not shown, with which the carrier plate 1 with the optical imaging element 2 fastened thereon, for. B. transferred from a storage and transport container through a lock system into the rinsed work area of a semiconductor processing system and can be positioned there in a projection beam path in a workable state.

The carrier plate 1 contains fastening and adjusting elements in the form of fixed stops, holding elements which are designed to be resilient in the predetermined axial direction or perpendicular thereto, and in the form of adjustable stops for aligning the optical imaging element 2. In the present case, the cylindrical lens is held on the supports 3 by the holding elements 9, 10 and 11, which are designed to be resilient in the predetermined axial direction XX, and rests against a fixed stop 12 and resiliently designed stops 13 perpendicular to the given axial direction , Adjustment elements 14 and 15, in which adjustable stops act directly on the optical imaging element 2 due to the action of the resilient stops 13, serve for an adjustment directed parallel to the receiving plane EE. A low-tension grasping of the optical imaging element 2 is thus made possible.

The arrangement and the number of fastening and adjusting elements is not based on the one described here

Configuration is limited and determined by the optical imaging element to be adjusted and the intended adjustments, in particular by the

Shape of the imaging element, which can be symmetrical or asymmetrical. The arrangement can always be chosen so that reworking the optical

Surfaces without changing the geometry of the clamping surfaces is guaranteed. This will be necessary if the optical surfaces no longer meet the requirements due to high laser radiation exposure

Meet imaging needs.

Furthermore, with a suitable arrangement of the fastening and adjusting elements, adjustments are possible not only in the radial but also in the axial direction.

The structure shown in Figures 3 to 5

Control element, of which at least one is used to adjust the optical imaging element 2 on the carrier plate 1, has an adjustable stop 16, that can engage the optical imaging element 2 without torsion. The freedom from torsion is achieved in that the stop 16 is attached to a lever arm 17 of a solid-state joint 18, which is opposite a fixed part 19 to be fastened on the carrier plate 1 by an adjusting spindle screwed into the lever arm 17 and axially preloaded and locked by a compression spring 20 21 is adjustable. The compression spring 20 is supported on the lever arm 17 and on a pressure sleeve 22 which is fastened in a spindle bearing 23 in the fixed part 19. The stop 16 is pressed axially offset to the adjusting spindle 19 in the lever arm 17. A spherical disk 24 arranged between the adjusting spindle 21 and the pressure sleeve 22 serves to compensate for the movement of the lever arm 17 via the solid body joint 18. The fixed part 19 is fastened on the carrier plate 1 with the counterbores 25 and pin bores 26.

The adjusting spindle 21 and the fine thread, into which the adjusting spindle 21 is screwed, are provided with a non-gassing special coating (e.g. DNC surface finish), with which frictional forces are minimized and lubricant-free working is guaranteed.

The module-like protective housing part 27 shown in FIG. 6 is intended to accommodate at least one universal optical module with the imaging element 2 located therein with its optical axis, flanges 28, 29 arranged on the side serving to connect several such protective housing parts 27 to one another or that To close the protective housing part in a gas-tight manner with at least one entry or exit window in order to enclose an optical beam guidance system surrounded by a contamination-free atmosphere with a projection beam path PP which is guided centrally through the flanges 28, 29.

Within the protective housing part 27, a receiving element 30 with a second reference is provided for each optical module, which is congruent to the spherical contact surfaces 4, 5 and 6 and arranged in a triangle symmetrical to the projection beam path PP, a prismatic, a flat and a conical contact element having.

In the present exemplary embodiment, the receiving element 30 is fastened to an angle 31 fixed to the housing, but can also be additionally adjustable by adjusting the angle 31.

For the transfer of the optical module into the projection beam path PP, protected from atmospheric influences, and out of it, the protective housing part 27 is equipped with a lock opening 32 and a receiving plate 34 serving as an interface for a transport container 33, to which the transport container 33 is shown in FIG. 3 Can be docked by attaching. The lock opening 32 has a closure 35 which can be adjusted by a driver on the transport container 33 after it has been put on. With the aid of a manipulator 36, the optical module can be transferred in a direction perpendicular to the projection beam path P-P.

Claims

claims

1. A method for constructing an optical beam guidance system in a contamination-free atmosphere by equipping it with optical imaging elements, characterized in that

- The imaging element outside the contamination-free atmosphere of the beam guidance system with its optical axis protected against atmospheric influences relative to a first reference of a carrier is fixed on the carrier, and

- That the carrier, together with the imaging element, is protected from atmospheric influences in the contamination-free atmosphere of the

2. The method according to claim 1, characterized in that the alignment of the optical axis of the imaging element is carried out using an adjustment template.

3. The method according to claim 1 or 2, characterized in that a cleaning / decontamination of the imaging element and the carrier is carried out outside the contamination-free atmosphere of the optical beam guidance system.

4. Universal optical module with a carrier plate (1) for receiving at least one optical imaging element

(2) in a receiving plane (EE), characterized in that the carrier plate (1) the optical Imaging element (2) with its optical axis aligned with an axis (XX) with a predetermined axial direction and the axis (XX) has a fixed spatial arrangement with a reference connected to the carrier plate (1), with which the carrier plate (1) can be positioned is.

5. Optics module according to claim 4, characterized in that the axis (XX) extends perpendicular to the receiving plane (EE) and in the support plate (1) as a reference bearing surfaces (4, 5, 6) are incorporated, which in a common to Acquisition plane (EE) parallel plane (BB) lying around the axis (XX) concentrically.

6. Optics module according to claim 5, characterized in that the contact surfaces (4, 5, 6) as balls in one

Triple formation are embedded in the carrier plate (1).

7. Optical module according to one of claims 4 to 6, characterized in that the carrier plate (1) for adjusting the optical imaging element (2) contains at least one actuating element (14, 15) which is torsion-free on the optical with an adjustable stop (16) Imaging element (2) attacks.

8. Optics module according to claim 7, characterized in that the adjustable stop (16) is attached to a lever arm (17) of a solid-state joint (18) which is opposite a fixed part (19) by an adjusting spindle (17) acting on the lever arm (17). 21) is adjustable.

9. Optics module according to claim 8, characterized in that the adjusting spindle (21) is biased and locked by a compression spring (20) which is on the lever arm (17) and on a, in a spindle bearing (23) in the fixed part (19) fixed pressure sleeve (22).

10. Optics support according to claim 9, characterized in that the adjusting spindle (21) and a fine thread serving to engage the lever arm (17) are provided with a special coating which minimizes the frictional forces.

11. Optics support according to one of claims 4 to 10, characterized in that an adjustment of the optical imaging element (2) required for adjustment takes place parallel to the receiving plane (E-E) of the support plate (1).