DE102012204142A1 - Collector for microlithography projection exposure apparatus used during manufacture of micro-or nano-structured component, has movable portion that is moved to adjust spatial extent of radiation in region of intermediate focus - Google Patents

Abstract

The collector (15) has a collector tray (28) for bundling of radiation irradiated from an extreme UV radiation source (3) in an intermediate focus, such that wavelength of UV radiation is in the range of 5 nm to 30 nm, or 13 nm to 14 nm. The collector tray is provided with a movable portion (29) that is moved so as to adjust spatial extent of radiation in the region of intermediate focus. Independent claims are included for the following: (1) illumination optical unit; (2) illumination optical system; (3) microlithography projection exposure apparatus; (4) method for illuminating object field; and (5) method for producing micro-or nano-structured component.

Description

The invention relates to a collector for a projection exposure apparatus. The invention also relates to an illumination optics and a lighting system for a projection exposure apparatus. Furthermore, the invention relates to a method for illuminating an object field. Finally, the invention relates to a projection exposure apparatus for microlithography, a method for producing a microstructured component and a microstructured component.

Collectors for projection exposure systems are known from the DE 10 2007 041 004 A1 and the EP 1 650 786 A1 ,

It is an object of the present invention to improve a collector for a projection exposure apparatus.

This object is achieved by a collector according to claim 1.

The essence of the invention is to make a collector adjustable. In particular, the collector has at least one adjustable collector shell, that is to say a collector shell with at least one adjustable section. This makes it possible to change the spatial extent of the image of the radiation source imaged by the collector in an intermediate focus. With the aid of the collector according to the invention, in particular the local extent of a secondary radiation source can be influenced. This makes it possible, in particular, to make the local extent of the secondary radiation source independent of an optical conductivity of a specific primary radiation source. The collector is in other words switchable. It is particularly adaptable to the light conductance of the radiation source.

The collector shell is in particular adjustable such that the extent of the image of the radiation source, that is, the extent of the secondary radiation source, by at least 10%, in particular at least 30%, in particular at least 50% is variable.

Preferably, the collector has a variable magnification. In particular, the collector has a continuously variable magnification. As a result, a particularly precise adaptation of the local extent of the secondary radiation source is possible.

Another object of the invention is to improve an illumination optical system for a projection exposure apparatus. This object is solved by the features of claim 4.

The advantages correspond to those described for the collector.

The illumination optics may preferably have a collector unit with a changeover device with at least two collectively interchangeable collectors. In this way, it is particularly easy to adapt the collector of the illumination optics to different radiation sources, in particular to radiation sources with different light conductance.

At least one of the collectors may be designed to be adjustable as described above. As a result, the flexibility of the collector unit is further increased.

Another object of the invention is to improve a lighting system for a projection exposure apparatus. This object is solved by the features of claim 7.

The advantages are the same as those described above.

The radiation source is in particular an EUV radiation source. The EUV radiation is in particular radiation having a wavelength in the range of 5 nm to 30 nm, in particular having a wavelength in the range of 13 nm to 14 nm or in the range of 6.5 nm to 7 nm.

In particular, it can be a plasma source, for example a GDPP source (plasma discharge by glass discharge, gas discharge-produced plasma) or an LPP source (plasma generation by laser, laser-produced plasma).

The EUV radiation is generated in particular in the region of a first focus of the collector.

The collector unit is in particular adjustable such that a predetermined area in a pupil plane of the illumination optics can be illuminated at least 90% independently of the light conductance of the radiation source. In this case, a pupil plane is also understood to mean the intermediate focus plane conjugated to the pupil plane. The collector unit is in particular adjustable in such a way that an aperture opening in the region of the intermediate focus can be illuminated to at least 90%. As a result, individual pupil facets of a pupil facet mirror whose size is adapted to the aperture of such an aperture in the intermediate focus can be illuminated to at least 90%. Based on the positional and alignment tolerance, provision may be made in each case not to fill an edge region of a pupil facet with illumination light in order to To avoid stability problems. In this context, a size of a pupil facet is understood to be only the size that can be used taking tolerances into account. By means of the collector unit according to the invention, it is possible, in particular, to illuminate the pupil facets at least 90%, in particular completely, irrespective of the radiation source used of the illumination system, in particular independently of the light conductance thereof. This makes it possible to minimize the number of illuminated pupil facets, that is to say the pupil filling, which leads to an improved contrast of the aerial image and to an enlarged process window. In particular, an improved contrast leads to increased stability against dose fluctuation. Among other things, the process window describes which dose fluctuations still allow a stable manufacturing process for micro- or nanostructured components.

Another object of the invention is to improve a method of illuminating an object field. This object is solved by the features of claim 9.

The essence of the invention is to adjust the previously described collector unit in such a way that a predetermined area in a pupil plane or a plane conjugate thereto with a radiation source is illuminated at least 90% independently of its light conductance.

The advantages are the same as those described above.

Further objects of the invention are to provide a projection exposure apparatus for microlithography with the illumination system according to the invention, a method for producing a component using the projection exposure apparatus and a component produced by the method. These objects are achieved by a projection exposure system according to claim 9, a manufacturing method according to claim 11 and by a device according to claim 12.

The projection exposure apparatus is preferably designed as a scanner. The projection exposure apparatus then has both for the object to be imaged and for a substrate on which is imaged, for example a wafer, a holder that can be displaced in the scanning direction during the projection exposure.

The benefits of these items are similar to those discussed above.

Further advantages, details and details of the invention will become apparent from the description of several embodiments with reference to the drawings. These show:

1 schematically a meridional section through a projection exposure system for EUV projection lithography;

2 a schematic representation of the Lichtleitwertahahmen in the design of a lighting system;

3 a schematic representation of the illumination situation of the lighting system according to 2 when using a radiation source with a lower optical conductivity;

4 a representation accordingly 3 in an inventive adaptation of the collector unit;

5 a schematic representation of a lighting system with a collector unit according to the invention; and

6 a schematic cross section through a collector according to the invention.

1 schematically shows in a meridional section a projection exposure system 1 for microlithography. A lighting system 2 the projection exposure system 1 has next to a radiation source 3 an illumination optics 4 for the exposure of an object field 5 in an object plane 6 , One is exposed in the object field 5 arranged reticle 7 that of a reticle holder only partially shown 8th is held. The illumination optics 4 has an object-side numerical aperture of at least 0.0825, in particular of at least 0.1125, in particular of at least 0.15. A projection optics 9 serves to represent the object field 5 in a picture field 10 into an image plane 11 , A structure is shown on the reticle 7 on a photosensitive layer in the area of the image field 10 in the picture plane 11 arranged wafers 12 , of a likewise schematically represented wafer holder 13 is held.

At the radiation source 3 it is an EUV radiation source with an emitted useful radiation in the range between 5 nm and 30 nm. It can be a plasma source, for example a GDPP source (plasma generation by gas discharge, gas discharge-produced plasma) or an LPP Source (plasma generation by laser, laser-produced plasma). Information about such a radiation source is the expert, for example from the US Pat. No. 6,859,515 B2 , EUV radiation 14 by the radiation source 3 emanating from a collector 15 bundled. The EUV radiation 14 in particular goes through a Zwischenfokusebene 16 before moving to a field facet mirror 17 meets. In the area of the Zwischenfokusbene 16 is a Zwischenfokusblende 26 with a shutter 27 intended. The field facet mirror 17 is in a plane of illumination optics 4 arranged to the object level 6 is optically conjugated.

The EUV radiation 14 is hereinafter also referred to as illumination light or as imaging light.

After the field facet mirror 17 becomes the EUV radiation 14 from a pupil facet mirror 18 reflected. The pupil facet mirror 18 is in a pupil plane of the illumination optics 4 arranged to a pupil plane of the projection optics 9 is optically conjugated. Using the pupil facet mirror 18 and an imaging optical assembly in the form of a transmission optics 19 with mirrors in the order of the beam path 20 . 21 and 22 become field facets 23 of the field facet mirror 17 in the object field 5 displayed. The last mirror 22 the transmission optics 19 is a grazing incidence mirror. The pupil facet mirror 18 and the transmission optics 19 form a sequential optics for the transfer of the illumination light 14 in the object field 5 , On the transmission optics 19 can be omitted, in particular, when the pupil facet mirror 18 in an entrance pupil of the projection optics 9 is arranged.

For easier description of location relationships is in the 1 a Cartesian xyz coordinate system drawn. The x-axis runs in the 1 perpendicular to the drawing plane into this. The y-axis is to the right. The z-axis is down. The object plane 6 and the picture plane 11 both run parallel to the xy-plane.

The reticle holder 8th is controlled so displaceable that during projection exposure the reticle 7 in a direction of displacement in the object plane 6 can be displaced parallel to the y-direction. The wafer holder is corresponding 13 controlled so displaceable that the wafer 12 in a direction of displacement in the image plane 11 is displaceable parallel to the y-direction. This allows the reticle 7 and the wafer 12 on the one hand through the object field 5 and on the other hand through the image field 10 be scanned. The direction of displacement is hereinafter also referred to as scan direction. The displacement of the reticle 7 and the wafer 12 in the scan direction may preferably be synchronous with each other.

The collector 15 serves in particular for bundling the radiation 14 from the radiation source 3 into an intermediate focus 25 in the Zwischenfokusebene 16 , It serves in particular to the light distribution of the radiation source 3 such that they pass through the aperture 27 the intermediate focus aperture 26 fits and also in the area of the field facet mirror 17 with the field facets 23 has a predetermined shape, in particular a predetermined extent. In particular, it leads to a picture of the radiation source 3 in the area of the intermediate focus level 16 , The image of the radiation source 3 in the area of the intermediate focus level 16 forms a secondary radiation source 32 , The secondary radiation source 32 is over the field facets 23 of the field facet mirror 17 on pupil facets 24 of the pupil facet mirror 18 displayed.

The lighting system 2 is designed such that the size of the pupil facets 24 and the aperture 27 are adapted to each other so that the pupil facets 24 at a complete illumination of the aperture 27 , and that means at a local extension of the radiation 14 in the area of the intermediate focus 25 , which is just the local extent of the aperture 27 corresponds, with an angular distribution such that all field facets 23 with the radiation 14 be lit, are fully lit.

The use of a radiation source 3 with a lower optical conductivity than that used in the design of the lighting system 2 according to 2 was taken into account, can cause the radiation 14 in the area of the intermediate focus 25 , as in 3 shown, a smaller spatial extent and the same angular extent as in the lighting system 2 according to 2 having. In this case again all field facets become 23 with radiation 14 applied. The aperture 27 is only partially lit. The individual pupil facets are also corresponding 24 only partially lit. At the number of with radiation 14 applied pupil facets 24 and thus at the average pupil filling nothing changes.

According to the invention, the collector is provided 15 for influencing the spatial extent of the radiation 14 in the area of the intermediate focus 25 adjustable to train. The collector 15 in particular has at least one collector shell 28 with at least one adjustable section 29 on. The collector 15 in particular has a plurality of adjustable, in particular pivotable sections 29 on. By adjustment, in particular pivoting of one or more of the adjustable sections 29 can the spatial extent of the radiation 14 in the area of the intermediate focus 25 by at least 10%, in particular at least 30%, in particular at least 50% change. The collector 15 in particular has a variable, preferably a continuously variable magnification. By increasing the local extent of the secondary radiation source 32 that is, the image of the primary radiation source 3 in the area of the intermediate focus level 16 lets the angular distribution of the radiation 14 the secondary radiation source 32 to reduce. This leads to a reduction in the illuminated area of the field facet mirror 17 , in particular to a reduction in the number of field facets 23 , which with radiation 14 be charged. This is exemplary in 4 shown. A reduction in the number of illuminated field facets 23 leads to a correspondingly reduced number of illuminated pupil facets 24 , The pupil filling is thus reduced. On the other hand, by the complete illumination of the aperture 27 in the area of the intermediate focus level 16 ensures that the irradiated pupil facets 24 each also completely illuminated.

The reduced pupil filling improves the contrast of the aerial image and enlarges the process window. The contrast of the image of a structure on the reticle, which is a subset of the illumination light 14 which covers a small area of a pupil plane of the illumination optics 4 or the pupil facet mirror 18 to be led. in the object plane 6 depends on the position of the sub-beam in the pupil plane. Partial bundles over certain areas of the pupil plane can produce a low contrast image, especially a non-contrast image. If the pupil filling is small, it is possible to dispense with it, illuminating light 14 through this area of the pupil facet mirror.

As in 5 is shown, can be provided, the illumination optics 4 with a collector unit 30 to provide which a change device 31 with two interchangeable collectors 15 having. The collectors 15 the changing device 31 can be rigid, that is not designed to be adjustable. Preferably, however, at least one of the collectors 15 the collector unit 30 designed adjustable as previously described. The collectors 15 the collector unit 30 In particular, different imaging scales may be used which deviate from one another by at least 10%, in particular at least 30%, in particular at least 50%.

The collector unit 30 can also have more than two, especially three or more collectors 15 exhibit. In particular, it can be provided for different types of radiation source 3 each with its own collector 15 provided. The different collectors 15 are by means of the changing device 31 interchangeable. For example, one collector each 15 for a GDPP source and another collector 15 be provided for an LPP source. At least one of the collectors 15 the collector unit 30 can be designed adjustable. It is also possible, all collectors 15 the collector unit 30 adjustable to train.

By means of an adjustable collector 15 can be the illumination of the aperture 27 or the pupil facets 24 flexible to the light conductance of the radiation source 3 to adjust. In particular, it is possible to vary the light conductance of the radiation source 3 , In particular, changes in the Lichtleitwerts the radiation source 3 over their lifetime, to compensate.

With the collector unit according to the invention 30 , in particular with an adjustable collector 15 , it is possible to measure the light conductance at the reticle 7 without loss of light for a given radiation source 3 to minimize. In particular, it is possible to achieve that the light conductance at the reticle 7 essentially equal to the optical conductivity of the radiation source used 3 is. This can be achieved in particular by reducing the pupil filling. This increases the contrast and the process window. This means, however, that the application of the pupil facets 24 of the pupil facet mirror 18 with illumination radiation 14 and in particular the pupil on the reticle 7 from the radiation source 3 depends. This may necessitate an adaptation of the lithography process, in particular by, for example, line widths in the region of the image plane 11 regardless of the radiation source 3 close. Advantageously, the illumination system is designed such that the field facets 23 of the field facet mirror 17 switchable to adapt to the different illumination pupils, in particular are displaced. For details of a lighting system 2 with switchable, in particular displaceable field facets 23 be on the US 6,658,084 B2 directed. By switching from some or all of the field facets 23 can the illumination pupil, in particular the distribution of illumination light 14 applied pupil facets 24 on the pupil facet mirror 18 be adjusted. The field facets 23 of the field facet mirror 17 are particularly switchable so that the lighting system 2 generates an anular lighting setting. This is understood to mean that with illumination light 14 applied pupil facets 24 in an annular area at the edge of the pupil facet mirror 18 lie. This maximizes the aerial contrast and the process window.

In addition, it can be provided, individual field facets 23 which are only partially illuminated, to pivot such that the radiation reflected by them 14 not for lighting of the object field 5 contributes. In a preferred embodiment, the field facets become 23 which are only partially illuminated so shifted that the effect of the partial illumination of these field facets 23 compensated against each other. One possible realization of this idea is in the US 2008/0278704 A1 described.

In the method according to the invention for illuminating the object field 5 , especially the reticle 7 becomes the collector unit 30 and / or the collector 15 adjusted so that the aperture 27 the intermediate focus aperture 26 completely with radiation 14 is illuminated. Generally, by adjusting the collector unit 30 , in particular of the collector 15 achieves that a given area in a pupil plane of the illumination optics 4 , especially in the area of the intermediate focus level 16 or in the area of the pupil facet mirror 18 with a given radiation source 3 is illuminated with a given optical conductivity to at least 90%. By adjusting the collector unit 30 and / or by adjusting the collector 15 is achieved in particular that the aperture 27 the intermediate focus aperture 26 is at least 90% illuminated. It can also be provided, the collector unit 30 and / or the collector 15 to adjust such that individual pupil facets 24 of the pupil facet mirror 18 at least 90%, in particular completely, are illuminated. With a corresponding adjustment of the size of the pupil facets 24 and the size of the aperture 27 the intermediate focus aperture 26 together is the adaptation of the collector unit 30 and / or the collector 15 to the aperture 27 the intermediate focus aperture 26 equivalent to an adaptation to the pupil facets 24 of the pupil facet mirror 18 ,

When using the projection exposure system 1 become the reticle 7 and the wafer 12 , one for the illumination light 14 photosensitive coating carries, provided. Subsequently, at least a portion of the reticle 7 with the help of the projection exposure system 1 on the wafer 12 projected. At the projection of the reticle 7 on the wafer 12 can the reticle holder 8th and / or the wafer holder 13 in the direction parallel to the object plane 6 or parallel to the image plane 11 be relocated. The relocation of the reticle 7 and the wafer 12 may preferably be synchronous with each other. Finally, the one with the illumination light 14 exposed photosensitive layer on the wafer 12 developed. In this way, a microstructured or nanostructured component, in particular a semiconductor chip, is produced.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102007041004 A1 [0002]
• EP 1650786 A1 [0002]
• US Pat. No. 685,951 B2 [0032]
• US 6658084 B2 [0045]
• US 2008/0278704 A1 [0046]

Claims (12)

Collector ( 15 ) for a projection exposure apparatus ( 1 ) for microlithography comprising a. at least one radiation-reflecting collector shell ( 28 ) for the bundling of radiation ( 14 ) in an intermediate focus ( 25 b. wherein the at least one collector shell ( 28 ) at least one adjustable section ( 29 ) for influencing a spatial extent of the radiation ( 14 ) in the area of the intermediate focus ( 25 ) having. Collector ( 15 ) according to claim 1, characterized by a variable magnification. Collector ( 15 ) according to claim 2, characterized in that the magnification is continuously variable. Illumination optics ( 4 ) for a projection exposure apparatus ( 1 ) for microlithography comprising a. a collector unit ( 30 ; 15 ) which is adjustable in such a way that it can be used to image a radiation source ( 3 ) into an intermediate focus ( 25 i. in a first position has a first magnification and ii. in a second position has a second magnification, iii. wherein the first magnification deviates by at least 10% from the second magnification, and b. at least one facet mirror ( 17 . 18 ) with a plurality of facets ( 23 . 24 ). Illumination optics ( 4 ) according to claim 4, characterized in that the collector unit ( 30 ) a changing device ( 31 ) with at least two interchangeable collectors ( 15 ) having. Illumination optics ( 4 ) according to one of claims 4 or 5, characterized in that the collector unit ( 30 ) at least one collector ( 15 ) according to one of claims 1 to 2. Lighting system ( 2 ) for a projection exposure apparatus ( 1 ) comprising a. an illumination optics ( 4 ) according to one of claims 4 to 6 and b. a radiation source ( 3 ) with an optical conductivity. Lighting system ( 2 ) according to claim 7, characterized in that the collector unit ( 30 ; 15 ) is adjustable such that a predetermined range ( 27 ; 24 ) in a pupil plane of the illumination optics ( 4 ) independent of the light conductance of the radiation source ( 3 ) is at least 90% illuminable. Method for illuminating an object field ( 5 ) comprising the following steps: - providing illumination optics ( 4 ) according to one of claims 4 to 6, - providing a radiation source ( 3 ) with an optical conductivity, - adjustment of the collector unit ( 30 ; 15 ) such that a predetermined area in a pupil plane with the radiation source ( 3 ) is illuminated to at least 90%. Projection exposure apparatus ( 1 ) for microlithography comprising a. a lighting system ( 2 ) according to one of claims 7 to 8 with an illumination optical system ( 4 ) for illuminating an object field ( 5 ) with the collector ( 15 ) reflected radiation ( 14 ) and b. a projection optics ( 9 ) for projecting the object field ( 5 ) in an image field ( 10 ). Method of manufacturing a micro- or nanostructured device - providing a reticle ( 7 ), - providing a wafer ( 12 ) with a photosensitive coating, - projecting at least a portion of the reticle ( 7 ) on the wafer ( 12 ) using the projection exposure equipment ( 1 ) according to claim 10, - developing the exposed photosensitive coating on the wafer ( 12 ). Component produced by the method according to claim 4.

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