This application claims benefit under 35 U.S.C. §119 to German Application No. 10 2011 004 375.6, filed on Feb. 18, 2011. The content of this application is hereby incorporated by reference in its entirety.
The disclosure relates to a device for guiding electromagnetic radiation with an optical fibre, wherein the fibre is introduced into a projection exposure apparatus for semiconductor lithography.
Projection exposure apparatuses for semiconductor lithography contain, inter alia, optical elements for optically influencing the EUV or VUV radiation used for imaging. In order to improve the optical ray guiding and the optical imaging performance, the optical elements can in part also be heated, for example in order to homogenize a temperature distribution across the relevant optical element and thus to prevent undesired, temperature-induced deformations of the optical element. By way of example, electromagnetic infrared radiation (for short: IR radiation) can be used for heating the optical elements. In this case, the IR radiation impinges on the optical element, is partly absorbed there and heats said element as a consequence. It can be advantageous to guide the electromagnetic radiation using an optical fibre from the outside into the EUV projection exposure apparatus, the infrared radiation source being situated outside the EUV projection exposure apparatus. The waste heat from the light source can thus be dissipated separately and an additional, undesired energy input into the EUV projection exposure apparatus by the waste heat from the light source is avoided by the use of the fibre. By way of example, a fibre-coupled laser that emits infrared radiation can be used as a radiation source. The optical fibre proceeding from the laser is generally embodied as a single-mode fibre. In order to transport high radiation powers from the output of the light source fibre to the location of the optical element to be heated, a further optical fibre, e.g. a multimode fibre, is used.
At the exit end of the optical fibre that leads to the optical element in the projection exposure apparatus, an inhomogeneous intensity profile distribution of the electromagnetic radiation can be present. Given a lack of homogeneity, rotational symmetry of the radiation distribution with respect to the centre of the fibre cross section is not present. In particular, cases can occur in which the centroid of the intensity profile distribution is situated eccentrically with respect to the fibre cross section. These inhomogeneous distributions of the electromagnetic radiation at the exit end of the fibre have the disadvantage that there impinges on the optical elements in the projection exposure apparatus an electromagnetic radiation which results in an undesired heating of the optical element on account of an incorrect spatially resolved distribution. A correct heating of the optical elements is facilitated, in particular, when the intensity profile distribution at the exit end of the fibre is homogeneous.
Embodiments are disclosed that feature homogenizing the intensity profile distribution at the exit end of the fibre.
This can be achieved using the devices including the features disclosed herein.
Embodiments of devices for guiding the electromagnetic radiation into a projection exposure apparatus for semiconductor lithography have, inter alia, an optical fibre. Said optical fibre serves for transporting the electromagnetic radiation to the optical element in the projection exposure apparatus. For the mechanical manipulation of a section of the fibre, an actuator is provided, as a result of which a temporally averaged homogenization of an intensity profile of electromagnetic radiation emerging at an exit end of the fibre can be achieved. An intensity profile is homogeneous if it is rotationally symmetrical with respect to the centre of the fibre cross section at the exit end of the fibre. In this case, the homogenization is effected using a temporal averaging. The mechanical manipulation of the optical fibre can be carried out repeatedly in a specific time segment. The projection exposure apparatus can be, in particular, an EUV projection exposure apparatus. In this case, the electromagnetic radiation serves for heating an optical element in the apparatus. The electromagnetic radiation can be, for example, in the range of the wavelengths of 1064 nm or 1550 nm. A fibre laser can be present as a source of the electromagnetic radiation; the fibre can be a multimode fibre having a stepped-index profile. The actuator can be suitable, in particular, for causing a section of the fibre to effect a lateral movement or for reversibly altering the fibre cross section on a section of the fibre. The section for the mechanical manipulation of the fibre can be either within or outside the projection exposure apparatus.
As an alternative or in addition to the possibilities outlined above, a homogenization of the intensity profile of the radiation can also be achieved by the use of a diffusing screen.
An exemplary embodiment of the disclosure is explained in greater detail below with reference to the drawing, in which:
The exemplary embodiment illustrated in
An actuator 2 is arranged in that section of the optical multimode fibre 1 which is shown in
Other embodiments are in the following claims.
Number | Date | Country | Kind |
---|---|---|---|
10 2011 004 375 | Feb 2011 | DE | national |
Number | Name | Date | Kind |
---|---|---|---|
5302999 | Oshida et al. | Apr 1994 | A |
6142641 | Cohen et al. | Nov 2000 | A |
6590698 | Ohtsuki et al. | Jul 2003 | B1 |
20010019403 | Schuster et al. | Sep 2001 | A1 |
20040033448 | Ito et al. | Feb 2004 | A1 |
20040246457 | Okazaki | Dec 2004 | A1 |
20050027288 | Oyagi et al. | Feb 2005 | A1 |
20060244940 | Uehara | Nov 2006 | A1 |
20060273263 | Raymond et al. | Dec 2006 | A1 |
20080212045 | Bader | Sep 2008 | A1 |
20100290020 | Mori | Nov 2010 | A1 |
Number | Date | Country |
---|---|---|
100 00 191 | Jul 2001 | DE |
63-173322 | Jul 1988 | JP |
63173322 | Jul 1988 | JP |
2001-196305 | Jul 2001 | JP |
2010-171447 | Aug 2010 | JP |
2010-267966 | Nov 2010 | JP |
Entry |
---|
English translation of Japanese Office Action for corresponding JP Appl No. 2012-022761, dated Apr. 17, 2012. |
German Office Action, with English translation, for corresponding DE Appl No. 10 2011 004 375.6, dated Sep. 12, 2011. |
Number | Date | Country | |
---|---|---|---|
20120212720 A1 | Aug 2012 | US |