Illumination optics for microlithography

Illumination optical mechanism for micro-development and etching

ILLUMINATION OPTICS FOR MICROLITHOGRAPHY

The present invention relates to an illumination optical mechanism used in micro-development etching. The present invention further relates to an illumination system including such an illumination optical mechanism, a projection exposure apparatus including such an illumination system, a method of manufacturing a structural member, and a structural member manufactured by this method.

One purpose of the present invention is to develop an illuminating optical mechanism of the aforementioned type so that it can influence and/or monitor an illumination intensity distribution passing through the object field, so that an illumination angle distribution will be affected to a minimum It is possible to ensure that the size of the illuminating optical mechanism is as small as possible.

According to the present invention, this objective is achieved by an illumination optical mechanism for micro-development etching, which includes:

An optical assembly is used to guide the illuminating light to an object field to be illuminated in an object plane;

The illumination optical mechanism divides an illumination light radiation beam into a plurality of radiation sub-beams, which are assigned to different illumination angles of the object field illumination;

The illuminating optical mechanism is configured such that at least some of the radiation sub-beams will overlap in a superimposed plane, which is separated from the object plane, and will not appear in the superimposed object plane, and The edges of the overlapping radiation sub-beams are at least partially overlapped.

According to the present invention, the object plane is spatially separated from the superimposed plane of the radiation sub-beam of the illuminating light. The object plane and the superimposed plane do not constitute a mutually visible plane; therefore, the object plane can be set to be directly adjacent to the superimposed plane. No optical component is needed between the object plane and the superimposed plane to guide the illuminating light. In the superimposed plane, a device can be provided for setting an illumination intensity distribution through the object field, or for example, by a sensor to monitor the illumination intensity distribution through the object field.

This arrangement allows the device and the illuminating light to interact at the coincidence points of the radiation sub-beams, so that all overlapping radiation sub-beams, in other words, radiation sub-beams from some or all of the illumination angles, etc., can be simultaneously Detection. If necessary, the illuminating light can therefore be detected in a superimposed plane separate from the object plane. The illumination optical mechanism according to the present invention may, but does not have to, include a faceted mirror. It can also be envisaged, for example, to use a honeycomb condenser, that is, a transmissive optical element which is divided into a plurality of individual channels, and/or at least one diffractive element is used to divide the illuminating light radiation beam into the radiation sub-beams . According to the present invention, the partial overlap of the edge portions of the secondary beams of the radiation sub-beams, in other words, the overlap and overlap, is sufficient. The edge parts of the remaining sub-beams of the overlapping radiation sub-beams do not need to overlap; in these parts, aberrations are tolerable. For example, in the case of a roughly rectangular radiation sub-beam, a superimposed system at one of the four sub-beam edges is sufficient. At the overlapping point of the radiation sub-beams in the overlapping plane, for example, an additional sensor system independent of the illumination angle may be used to decouple the radiation, which can provide valuable information about the illumination of the object field. Information on non-dry lighting angles. The overlapping edge portions of the overlapping radiation sub-beams form a common sub-beam edge portion, which is usually perpendicular to an object displacement direction that will be displaced during the projection process of the micro-visual etching technique. This kind of displacement is generated in a projection exposure device designed as a scanner. With the illumination optical mechanism of the present invention, the radiation sub-beams will be overlapped in the overlapping plane.

The aforementioned object can also be achieved by an illumination optical mechanism for micro-development etching according to the present invention, which includes:

An optical assembly for guiding the illuminating light to an object field to be illuminated in an object plane;

Wherein the illumination optical mechanism includes a field facet mirror with a large number of field facets that will be displayed in a superimposed plane, so that the image edges of the field facets will at least partially overlap in the superimposed plane;

And the superimposed plane is separated from the object plane and will not be displayed in the object plane.

The advantages are as described above.

The radiation sub-beams are superimposed by a field intensity setting device, which is set in the superimposed plane to be used as an intensity setting plane, and can be used to adjust the intensity distribution of the illumination light passing through the object field, wherein the The edges of the equally overlapping radiation sub-beams coincide at the point where they can be affected by the field intensity setting device, thereby providing the effect of one of the field intensity setting devices with substantially no illuminating angle. In this example, the overlapping plane will be the same as the intensity setting plane. The field intensity setting device affects the illuminating light radiation beams at the overlapping points of the overlapping radiation sub-beams. Therefore, the field intensity setting device will affect all the radiation sub-beams overlapping at this point in the same way; It does not matter to the angle of illumination assigned to these sub-beams of radiation. The superposition of the radiation sub-beams will occur at least at the point where the field intensity setting device affects the illuminating light radiation beam. For example, in the case of an approximately rectangular radiation sub-beam, a superimposition at the edge affected by the field intensity setting device is sufficient. Of course, the superimposition of the sub-beams or the edge portions of the sub-beams can also occur in areas not affected by the field intensity setting device. The superposition of the radiation sub-beams in the superimposed plane or intensity setting plane. In order to reduce or substantially avoid the influence of the illumination angle of the field intensity setting device, it can also be applied to some systems, wherein the field intensity setting device can influence the overlapping radiation sub-beams from both sides. They can be an illuminating optical mechanism with an intermediate image, or an illuminating optical mechanism with a transmission cover. The field intensity setting device defines the intensity of the illumination light in the plane of the object. The superimposition of the radiation sub-beams at one point. This point is within the range of influence of the field intensity setting device, which allows an increased stability of the object field illumination to be achieved because of the effectiveness of a light source used to generate the illuminating light on the field intensity setting device There will be only a small impact, if any, this is particularly advantageous when an EUV plasma source is used.

A field intensity setting device includes many individual spacers or stoppers arranged adjacently, and at least attenuates the illuminating light when exposed to it, and can insert an illuminating light radiation in a direction parallel to the displacement direction of an object In the beam, a height through the object field will be provided, in other words, a sensitive adjustment of the intensity of the size of the object field perpendicular to the displacement direction of the object.

Another object of the present invention is to develop the aforementioned illuminating optical mechanism so as to achieve a greater number of possible uses of the field intensity setting device.

According to the present invention, this objective is achieved by an illumination optical mechanism for micro-development etching, which includes:

An optical assembly for guiding the illuminating light to an object field to be illuminated in an object plane;

A field intensity setting device can be used to adjust the intensity distribution through the object field with a large number of individual spacers. The spacers are arranged next to each other and at least attenuate the illuminating light when exposed to it. The direction of the displacement direction of an object is inserted into an illuminating light radiation beam;

All the individual spacers of the field intensity setting device can be inserted into the illuminating light radiation beam from the same side.

According to the present invention, it has been found that if the individual spacers of the field intensity setting device can all be inserted into the illuminating light radiation beam from one side, the field intensity setting device can be uniformly applied to the object. The field is set on a reflective object. For example, in the case of a reflective indexing mirror. The field intensity setting device can be set so as not to interfere with the reflected light path of the illuminating light radiation beam.

The field intensity setting device is arranged in an intensity setting plane, which is arranged to coincide with a field plane of the optical assembly, which can also ensure the efficiency of the field intensity setting device without dry illumination angle. The field plane of the optical assembly refers to a plane in which the illumination light radiation beam will be condensed due to the beam guiding effect of the light assembly, and if an illumination light radiation beam is divided into several radiation sub-beams, each radiation The secondary beams will overlap. The field plane of the optical assembly is usually the plane in which the object field forming member of the optical assembly will visualize. In addition, the field plane of the optical assembly is usually a plane independent of position, which will be visualized by a projection optical mechanism downstream of one of the projection exposure devices of a micro-development etching technique, and it is usually called Is the object plane. In all conventional illumination optical mechanisms, the field plane of the optical assembly coincides with the plane of the object. But this is not the case of the illumination optical mechanism of the present invention. The field intensity setting device here is set in the field plane of the optical assembly, not in the object to be imaged, which is usually an indexing mirror. The field intensity setting device of the prior art is usually arranged upstream of an indexing mirror which is arranged in the field plane of the optical assembly, in other words they are not arranged in this field plane. As a result, the field intensity setting device of the prior art has a greater influence on the radiation sub-beams designated as special illumination angles of the illuminating light radiation beam than the radiation sub-beams designated as other illumination angles; therefore, the prior art The field intensity setting device has an effect that the field of the object is poorly dependent on the angle of illumination. This problem has been understood by the inventors and others, and the field intensity setting device is installed in the field plane of the optical assembly to eliminate it. Surprisingly, this allows the object to be moved out of the field plane of the optical assembly without any problems. This is particularly applicable if a projection exposure device includes the illumination optical mechanism and is designed as a scanning device. Moreover, this is particularly applicable if the illumination of the object field is performed using a numerical aperture of one of the illuminating light radiation beams less than or equal to 0.1.

There is a design in which the object plane is adjacent to the intensity setting plane, and there is no pupil plane of the optical assembly between the intensity setting plane and the object plane, it will be particularly compact.

There is a design in which the distance between the intensity setting surface and the plane of the object is within the range of 5mm to 20mm, which will prevent spatial conflicts or metering errors, in other words, undesirable images in the illumination intensity entering the object field Bad wait. The preferred distance is in the range of 10 mm to 20 mm, especially in the range of 15 mm or 16 mm.

There is a design in which the optical assembly includes a faceted mirror with a plurality of field facets, and their images will at least partially overlap the object field, so that the illumination angle distribution of the object field can be easily controlled .

The configuration of one of the field facets will cause the field engraved masks to have a higher x/y aspect ratio than the object field. This means that they are proportionally viewed along the direction of the objects displacement. It is narrower than the object field, and can avoid overexposure of the object field. This is because the object is not placed in the field plane of the optical assembly, also known as the spacer plane, so that the field facet image is in The result of the divergence in the object plane or the indexing mirror plane, where the partial fields, in other words, the image of the object field forming member of the optical assembly of the illumination optical mechanism, are set so that the illumination angle distribution is Feedback will be minimized.

There is a design in which the illuminating light radiation beam facing one edge of the individual spacers will be illuminated by all the field facets of the field facet mirror to ensure that the field intensity setting device has a relatively uniform view of all field facet images. In order to avoid adverse effects on the illumination angle distribution when using the field intensity setting device. As long as the clear images of the field facets are created in the intensity setting plane, a particularly high system stability can be ensured, especially the spatial displacement of a light source of the illuminating light will generally not cause problems. This is particularly advantageous when the light source is an EUV plasma source.

There is a design in which the illuminating light radiation beam facing one edge of the individual spacers will be illuminated in the field plane by a primary group of all field facets of the field facet mirror to ensure the field intensity setting device One is the efficiency of the non-dry illumination angle, even if the recombination of the field facet images at the edge of the illumination light radiation beam facing the individual separators in the field plane cannot be achieved for all the field facet images.

There is a specific distribution of the illumination angles of the field facets of the subgroup that the perfect superimposition system at the edge of the illumination light radiation beam facing the individual separators in the field plane cannot be achieved at all or can only reach one. In the case of a small degree, to improve the independence of the illumination angle of the field intensity setting device. The defined distribution of the illumination angles can be generated, for example, by using a statistical function. This can not only ensure the independence of one of the illumination angles of the intensity setting device, but also ensure the limited influence on one of the illumination angles.

A pupil facet mirror has a large number of pupil facets, which are assigned to the field facets in the light path of the illumination light, so that the illumination angle distribution through the object field can be easily controlled.

It can be tilted for adjusting the superimposed pupil facet of the illumination light in the intensity setting plane, etc. It can allow the individual radiation sub-beams of the illumination light radiation beam to be selectively shifted and directed in the intensity setting plane. Optimizing the secondary positions of the radiation secondary beams in an area within the influence range of the field intensity setting device.

The individual spacers are at least partially transparent at least in some parts, so as to enhance the displacement of the field intensity setting device with respect to the individual spacers, and the position change of the field intensity setting device relative to the illuminating light radiation beam The intensity of the sensitivity.

When the illumination optical mechanism is used to guide EUV illumination light having a wavelength between 5 nm and 30 nm to the object field, the above-mentioned advantages will become more significant.

The aforementioned object can also be achieved by an illumination optical mechanism for micro-development etching according to the present invention, which includes:

An optical assembly for guiding an illuminating light with a wavelength between 5nm and 30nm to an object field to be illuminated in an object plane;

A field intensity setting device is used to adjust the intensity distribution of the illumination light passing through the object field;

The field intensity setting device has an effect on a cross section formed by the illuminating light and perpendicular to an illuminating light radiation beam, so that the beam cross section is opposite to the edge of the field intensity setting device to be set at the field intensity The downstream of the device remains unchanged.

And the function of the field intensity setting device is independent of the illumination angle of the object field.

The advantages are the same as those mentioned above.

An illumination system including an illumination optical mechanism according to the present invention and a light source, and a projection exposure device including an illumination system according to the present invention and a projection objective lens for displaying the object field in an image plane, and A method of manufacturing a structural member including the following steps:

Provide a wafer such that at least part of it is coated with a layer of photosensitive material;

Provide an indexing lens which contains the structure to be imaged;

Provide a projection exposure device according to the present invention; and

The projection exposure device is used to project at least a part of the index mirror on an area of the layer on the wafer.

And the advantages of a component made in this way are the same as those of the aforementioned illumination optical mechanism. The light source may especially be an EUV light source with a useful light wavelength in the range of 5 nm to 30 nm. The projection exposure device will be used for lithography manufacturing of a microstructure or nanostructure component.

The embodiments of the present invention will be described in more detail below with the aid of the drawings, in which:

Figure 1 shows a schematic diagram of a meridian cross-sectional view of an illumination optical mechanism passing through a projection exposure device for micro-development etching;

Figure 2 shows an enlarged cross-sectional view of Figure 1 near the plane of an indexing mirror;

Figure 3 shows a view of a field intensity setting device of the projection exposure device from the direction III in Figure 2;

Figure 4 shows a facet arrangement view of a field facet mirror of the illumination optical mechanism of the projection exposure apparatus according to Figure 1;

Fig. 5 shows a facet arrangement diagram of a pupil facet mirror of the illumination optical mechanism of the projection exposure apparatus according to Fig. 1;

Figure 6 shows another embodiment of a field facet mirror, which is similar to the facet arrangement diagram of Figure 4;

Figure 7 shows a schematic diagram of the optical path of the three selected radiation sub-beams assigned to each specific illumination angle passing through a pupil plane and an indexing mirror plane of the illumination optical mechanism;

Figure 8 shows a field facet according to an embodiment of the field facet mirror of Figure 4;

Figure 9 shows a field facet according to another embodiment of the field facet mirror of Figure 4;

Figure 10 shows that three radiation sub-beams assigned to different illumination angles according to Figure 7 are superimposed on a plane of the field intensity setting device with a changed illumination setting;

Figures 11 to 16 show graphs in which the illumination parameters of the illumination of an indexing mirror become a function of the attenuation (%) of the field intensity setting device in a first illumination pattern; and

Figures 17 to 22 show graphs of the same lighting parameters in another lighting mode, which are optimized to minimize the changes in the lighting parameters caused by the attenuation of the field intensity setting device.

A projection exposure device 1 for micro-development and etching can be used to manufacture a micro-structure or nano-structure electronic semiconductor component. A light source 2 emits EUV radiation in the wavelength range of, for example, 5 nm to 30 nm. In the projection exposure device 1, a useful radiation beam 3 can be used for illumination and projection. Downstream of the light source 2, the useful radiation beam 3 initially passes through a collector 4, which can be, for example, a telescopic collector having a conventional multi-shell configuration. Downstream of the collector 4, the useful radiation beam 3 initially passes through an intermediate focal plane 5, which can be used to separate unwanted radiation parts or particles from the useful radiation beam 3. After passing through the intermediate focal plane 5, the useful radiation beam 3 will start to irradiate a faceted mirror 6.

In each case, the diagrams include an xyz coordinate system to illustrate the positional relationship. In Figure 1, the x-axis extends into a plane perpendicular to it. The y-axis system extends to the left of the first figure. The z-axis extends upward in Figure 1.

Fig. 4 shows an example of the field facet 7 and other facet arrangements of the field facet mirror 6. The field facets 7 are rectangular and all have the same x/y aspect ratio. The field covers 7 define a reflective surface of the field facet mirror 6 and are arranged in four columns, each of which has six field facet groups 8 and so on. The field facet groups 8 usually each include seven field facets 7. The two field facet groups 8 near the edge, which are included in the two central field facet columns, will each contain four additional field facets 7, so there are eleven field facets 7 in total. Between the two central facet columns and between the third and fourth facet rows, the facet array of the field facet mirror 6 has a gap 9, wherein the field facet mirror 6 will be collected by the The supporting spokes of the device 4 are shielded.

After being reflected by the field facet mirror 6, the useful radiation beam 3 will be divided into a plurality of radiation sub-beams assigned to individual facets 7 and enter a pupil facet mirror 10.

FIG. 5 shows an example of the facet arrangement of the circular pupil facet 11 of the pupil facet mirror 10. The pupil facets 11 are arranged into faceted rings, and each ring system is arranged as a ring inside the other ring to surround a center 12. The useful radiation beam 3 has the radiation sub-beams reflected by a field facet 7, and is assigned to a pupil facet 11, so that one of the field facets 7 and a pupil facet 11 is exposed separately The facet of is to define a radiation guiding channel for the specified radiation beam of the useful radiation beam 3. The channel assignment between the pupil facets 11 and the field facets 7 is performed according to the required illumination caused by the projection exposure device. In order to give access to a specific pupil facet 11, the field facets 7 can be individually inclined around the x-axis and the y-axis.

The pupil facet mirror 10 and a downstream transmission optical mechanism 15 including three EUV mirrors 12, 13, 14 can visualize the field facets 7 in a field plane 16 of the projection exposure device 1. The EUV mirror 14 is a grazing incident mirror. An indexing mirror plane 17 is located downstream of the field plane 16 at a distance of about 5mm to 20mm as viewed along the Z direction, wherein the indexing mirror plane 17 is provided with an indexing mirror 18, which will use the useful The radiation beam 3 illuminates an illuminating area, which overlaps with an object field 19 of a downstream projection optical mechanism 20 of the projection exposure device 1. In the projection exposure device 1, the field facets 7 will be displayed by the transmission optical mechanism 15 to form the field plane 16 of the faceted image and will not coincide with the indexing mirror plane 17. The indexing mirror The plane system simultaneously forms the object plane of the projection optical mechanism 20. The useful radiation beam 3 will be reflected by the index mirror 18.

The projection optical mechanism 20 displays the object field 19 in the indexing mirror plane 17 in an image field 21 in an image plane 22. A wafer 23 is provided in the image plane 22 with a photosensitive layer that will be exposed to light during the projection exposure by the projection exposure device 1. During the projection exposure, both the index mirror 18 and the wafer 23 are scanned in the y direction in a synchronized manner. The projection exposure device 1 is a scanner. This scanning direction is also referred to as the object displacement direction hereinafter.

The field plane 16 is provided with a field intensity setting device 24, which will be described in more detail below. The field intensity setting device 24 can be used to define a scanning integrated intensity distribution, in other words, an intensity distribution integrated through the object field 19 in the y direction. Therefore, the field plane 16 is also an intensity setting plane for the illumination optical mechanism 26 at the same time. The field intensity setting device 24 is actuated by a control device 25.

The field facet mirror 6, the pupil facet mirror 10, the mirrors 12, 13, and 14 of the transmission optical mechanism 15, and the field intensity setting device 24 are all components of an illuminating optical mechanism 26 of the projection exposure device 1. The components 6, 10, 12, 13, and 14 form an optical assembly of the illumination optical mechanism 26 for guiding the useful radiation beam 3.

There is no pupil plane of the optical assembly 26a between the field plane 16 and the indexing mirror plane 17.

Figures 2 and 3 show more detailed views of the field intensity setting device 24. The field intensity setting device 24 has a plurality of convex finger-shaped individual spacers 27, which are arranged to be adjacent to each other one after the other. In the embodiment according to Figures 2 and 3, there are a total of twenty-six individual spacers 27, each having a width of 4 mm. The individual spacers 27 are arranged directly next to each other or partially overlap each other. If they partially overlap each other, the adjacent individual spacers 27 must be arranged perpendicular to the beam direction of the illuminating light radiation beam 3 in planes that are as close as possible to each other.

All individual spacers 27 are inserted into the useful radiation beam 3 from the same side.

The control device 25 allows the individual spacers to be set at a designated position along the y direction independently of each other. Based on the field height of an object point on the indexing mirror 18 passing through the object field 19, in other words as measured in the x direction, the object point is along the scanning path of the y direction, and thus the object point will be exposed The integrated intensity of the useful radiation is determined by the y position of the respective spacer 27. In this way, the intensity of the useful radiation that will expose the index lens 18 will be equalized or distributed in a predetermined manner by defining the y positions of the individual spacers 27. The field intensity setting device 24 is also called UNICOM.

Fig. 6 shows another embodiment of a field facet mirror 6. The components that are equivalent to the field facet mirrors described above with reference to FIG. 4 will have the same reference numerals, and will only be described if they are different from the components of the field facet mirror 6 of FIG. 4. The field facet mirror according to Fig. 6 has a field facet arrangement system with curved field facets 7 and so on. The field facets 7 are arranged in a total of five columns, each of which has a plurality of field facet groups 8. The field facet arrangement is engraved in the circular boundary of a carrier 9a of the field facet mirror.

The field facets 7 according to the embodiment in Fig. 6 each have the same surface area and the same ratio of width (along the x direction) to height (along the y direction), which is equivalent to the field engraving of the embodiment in Fig. 4 The x/y aspect ratio of face 7.

The field intensity setting device 24 has an intensity function, which has substantially no effect on the illumination angle distribution of the object field 19. This will be explained later using Figure 7. The figure schematically shows that the three radiation sub-beams 28, 29, 30 pass from a pupil plane 31 in which the pupil facet mirror 10 is provided, and passes through the field plane 16 to the path of the indexing mirror plane 17. In practice, the planes 31, 16, and 17 that are successively arranged in the light paths of the three radiation sub-beams 28, 29, and 30 are shown in Fig. 7 as being arranged next to each other for the sake of explanation. The following is based on an idealized hypothesis, that is, the field facet 7 of the field facet mirror 6 in Fig. 4 is displayed in the field plane and overlaps perfectly. Therefore, a boundary of the useful radiation beam 3 in the field plane 16 will have the same breadth as a single image of a field facet 7 in both the x-direction and the y-direction. As a result, in this case of perfect superposition, the useful radiation beam 3 has an x/y aspect ratio, which is completely equal to the x/y aspect ratio of the field facets 7. All the radiation sub-beams 28 assigned to different illumination directions of the field plane 16, including the radiation sub-beams 28 to 30, etc., will overlap in the field plane 16 through the entire cross section. Specifically, the useful radiation beam 3 will be formed facing one edge 32 of the individual spacers 27 and will be irradiated by all three radiation sub-beams 28 to 30 at the same time. As a result, the individual spacers 27 and the like covering the useful radiation beam 3 by the edge 32 will have exactly the same effect on all the radiation sub-beams 28 to 30, in other words, there is no intensity effect of the dry illumination angle. As for the radiation sub-beams 28 to 30, they are generally shown in the pupil plane 31 on the right side of Fig. 7 in a rectangular frame, and they will act on one side. The shadow frames in the pupil plane 31 do not constitute actual spacers.

The field facet images in the field facet plane 16 do not need to be along the x-direction, in other words perpendicular to the scanning direction, and completely overlap, because the field intensity setting device 24 has the effect of a non-dry illumination angle as described above. ; In fact, the field facet images can also be arranged to have a specific deviation from each other. If the field facet images in the field facet plane 16 coincide well even in the x direction, they can be used for intensity detection by decoupling useful radiation.

In the indexing mirror plane 17, when viewed in the z-direction, it is set in the optical path of the useful radiation beam 3, for example, 20 mm behind the field plane 16, and the three radiation sub-beams 28 to 30 are especially in The y-direction will diverge slightly, so that, for example, the radiation sub-beam 28 will be projected slightly upward in the y-direction, and exceed the radiation sub-beam 29 in the center of the object field 19, and the radiation sub-beam 30 will be slightly along the y-direction. The ground is projected downward beyond this radiation sub-beam 29. When the indexing mirror is scanned in the y direction by the object field 19, the indexing mirror will see the scan products of all three radiation sub-beams 28 to 30 into their full range; therefore, in the indexing mirror plane 17 The y deviation between 28 to 30 of the radiation sub-beams will not have any negative effects.

Compared to the x/y aspect ratio specified by one of the field facets 7, the x/y aspect ratio of the object field 19 is smaller because of the y deviation of the radiation sub-beams 28 to 30 described above.

Figure 8 shows that one of the rectangular field facets 7 of the field facet mirror 6 of Figure 4 has an x/y aspect ratio, which corresponds to the x/y aspect ratio specified by one of the field planes 16. If the specified x/y aspect ratio is not generated in the field plane 16, but is in the index lens 17, a field facet mirror 6 must be used, which includes field facets 33, etc., their x/ The y aspect ratio is greater than the x/y aspect ratio of the object field 19. Therefore, a field facet mirror 6 must actually be used, and its field facet 33 is relatively narrow in the y direction (as shown in Fig. 9). Therefore, the y extent of the facets in these fields y₃₃Will be smaller than the y scale y of facet 7 in these fields₇ 。

In fact, the superposition of the radiation sub-beams assigned to the individual channels in the field plane 16 will deviate from the perfect superposition shown in FIG. 7 due to many imaging effects. There may be many reasons for this.

First, the mutual shielding of the field facets 7 caused by the illumination form of the field facet mirror 10 may produce images of the field facets 7 individually formed in the field plane 16.

Moreover, the transmission optical mechanism 15 may have different imaging specifications for different channels, in other words, different radiation sub-beams, depending on the radiation beams respectively observed. Similarly, these different imaging specifications will also cause the radiation beam to overlap in the field plane 16, which deviates from the perfect overlap.

Depending on the respective inclination of the field facets 7, a facet projection with a different facet size will be obtained perpendicular to the direction of exposure with the useful radiation beam 3. This will also affect the overlap in the field plane 16.

Another reason for imperfect overlap in the field plane 16 is that due to the grazing incident mirror 14, the radiation sub-beams to be overlapped in the field plane 16 may have different curvatures.

In the case of imperfect overlap in the field plane 16, the illumination optical mechanism 26 will be adjusted in a way so that the individual radiation sub-beams that display the respective field facets 7 can be optimized The possible ways are overlapped in the area of the edge 32 facing each spacer 27. This system is schematically shown in Figure 10. An imperfect superposition of the radiation sub-beams at an edge 33a opposite to the edge 33 is acceptable because it is shown by the boundaries 34, 35 of the individual radiation sub-beams that deviate from each other in the y direction.

In the worst case, perfect superposition of the radiation sub-beams will never be achieved at least at the edge 32 facing the individual spacers 27. This is the case if the radiation sub-beams that overlap the edge 32 have different curved edges, for example. In this case, the illuminating optical mechanism must be adjusted by particularly tilting the pupil facets 11 to minimize the influence of the field intensity setting device 24 on the illumination angles.

This will be explained later using Figures 11 to 22. Figures 11 to 16 show the illumination parameters in the object field 19 when one of the radiation sub-beams generated by the illumination optical mechanism 26 is not optimally superimposed; and Figures 17 to 22 show the One of the equal radiation sub-beams corresponds to the same illumination parameters in the case of optimal overlap.

The optical illumination parameters described below are telecentric values tx and ty, which are related to an invalid field intensity setting device (I_rel=1) One of the initial value variables, and the corresponding ellipticity variable ΔE, and its maximum value max(Δt), max(ΔE), etc. occurring on the object field 19.

The tx and ty lines are defined as follows:

Each field point in the illuminated object field 19 defines a centroid beam of a beam assigned to this field point. The centroid beam has the energy weight direction of the beam emitted by the field point. In an ideal situation, the centroid beam of each field point is parallel to the main beam defined by the illumination optical mechanism 26 or the projection optical mechanism 20.

The direction of the centroid beam<img file="TWI474125B_D0001.tif" he="56" id="i0001" img-content="character" img-format="tif" inline="no" orientation="portrait" wi="209" />The system can be known from the design data of the illumination optical mechanism 26 or the projection optical mechanism 20. The main beam at a field point is defined by the connecting line between the field point and the center of the entrance pupil of the projection optical mechanism 20. The direction of the centroid beam at one of the field points x, y of the object field 19 is obtained as follows:

<maths><img file="TWI474125B_D0002.tif" he="239" id="i0002" img-content="drawing" img-format="tif" inline="yes" orientation="portrait" wi="912" /></maths>

E(u, v, x, y) is the energy distribution of the field point x, y, and is a function of the pupil coordinates u, v, in other words, is the angle of illumination seen by the respective field points x, y One function.

<img file="TWI474125B_D0003.tif" he="76" id="i0003" img-content="character" img-format="tif" inline="no" orientation="portrait" wi="640" />Is the total energy of the point x and y being exposed.

For example, a central object field point x₀, Y₀Part of the radiation of the radiation sub-beams will be seen in the directions u, v defined by the positions of the respective pupil facets 11. In this lighting setting, the centroid beam system only forms a centroid beam direction if the individual different energy or intensity combinations of the partial radiation sub-beams assigned to the pupil facets 11 form a centroid beam direction. When all the pupil facets 11 are integrated and are parallel to the direction of the main beam, they will extend along the main beam. This can only be achieved under ideal conditions. In fact, at the centroid beam direction<img file="TWI474125B_D0004.tif" he="55" id="i0004" img-content="character" img-format="tif" inline="no" orientation="portrait" wi="200" />And main beam direction<img file="TWI474125B_D0005.tif" he="56" id="i0005" img-content="character" img-format="tif" inline="no" orientation="portrait" wi="213" />There will be a deviation between them, which is called telecentric error<img file="TWI474125B_D0006.tif" he="56" id="i0006" img-content="character" img-format="tif" inline="no" orientation="portrait" wi="128" />：

<maths><img file="TWI474125B_D0007.tif" he="113" id="i0007" img-content="drawing" img-format="tif" inline="yes" orientation="portrait" wi="745" /></maths>

When the projection exposure device 1 is actually used, it is not the static telecentric error at a specific object field that must be corrected, but x=x₀The telecentric error of the scan product at the location. This telecentric error is obtained as follows:

<maths><img file="TWI474125B_D0008.tif" he="259" id="i0008" img-content="drawing" img-format="tif" inline="yes" orientation="portrait" wi="751" /></maths>

As a result, the telecentric error will be corrected by a point (x such as x₀) A product of objects moving through the indexing mirror plane 17 during a scanning process, in which a difference will be caused between a x-telecentric error (Tx) and a y-telecentric error (Ty). The y telecentric error is defined as the deviation of the centroid beam from the main beam perpendicular to the scanning direction. The x telecentric error is defined as the deviation of the centroid beam from the main beam in the scanning direction.

The ellipticity is another parameter used to determine the illumination quality of the object field 19 in the indexing mirror plane 17. The determination of the ellipticity can assist in obtaining more accurate information about the energy or intensity distribution entering the pupil through the projection optical mechanism 20. Among them, the entering pupil will be divided into eight equal parts, which are numbered O in the counterclockwise direction.₁To O₈, As generally used in mathematics. The eight equal divisions that enter the pupil that are used to illuminate a field O₁To O₈The delivered energy or intensity distribution, hereinafter referred to as energy or intensity distribution I₁To I₈ 。

The following values are called -45°/45° ellipticity (Elly, E_-45°/+45°,E₄₅ )：

<maths><img file="TWI474125B_D0009.tif" he="212" id="i0009" img-content="drawing" img-format="tif" inline="yes" orientation="portrait" wi="678" /></maths>

The following values are called 0°/90° ellipticity (Ellx, E_0°/90°,E₉₀ )：

<maths><img file="TWI474125B_D0010.tif" he="205" id="i0010" img-content="drawing" img-format="tif" inline="yes" orientation="portrait" wi="602" /></maths>

Similarly, a specific object field point x₀, Y₀Or even a scan integration lighting (x=x₀, Y is the ellipticity of the product), which can also be determined based on the above description of the telecentric error. Figure 11 shows that the x-telecentric deviation of five different field heights from an initial value is a function of the amount of intensity that allows the designated individual spacer 27 to pass through at this field height. At a 15% attenuation, in other words at a transmittance of 0.85, especially at the edge of the field, there will be a telecentric deviation Δtx of approximately ±0.75mard (see Figure 11), and a Δty of approximately -2.4mard (see Figure 14). picture). Depending on the height of the field, an ellipticity variable ΔE90 at 0.85 transmittance will change the gap by 2.5% to -1% compared to a non-attenuation value (see Figure 12).

At a transmittance of 0.85, the value ΔE45 will reach a maximum value of -2% or about 4.5% respectively (see Figure 15).

A maximum telecentric variable will reach a value of 2.5% (see Figure 13).

A maximum ellipticity variable max (ΔE) will reach a value in the range of 45% (see Figure 16).

Figures 17 to 22 clearly show the effect of the optimized superposition on the radiation sub-beams in the area of the edge 32 in the field plane 16. At any field height, the maximum telecentric rate of change of -0.5 will not be exceeded (see Figure 19). Similarly, the maximum ellipticity change rate of 2% will not be exceeded at any field height (see Figure 22). These maximum variables can be applied to the attenuation of a transmittance up to 0.85. If the attenuation reaches a transmittance of 0.9, the telecentric variable will not exceed a value of 0.4 mrad, and the ellipticity variable will not exceed a value of 1%.

In a modified embodiment of superimposing the radiation sub-beam on the field plane 16, the edge of the individual spacer 27 facing the field intensity setting device 24 will not be engraved by all the field facets 7, but will be engraved by the fields. Surface 7 is illuminated by the primary group. The subgroup of the field facet 7 is selected so that the field facet 7 of the subgroup represents all the illumination angles. They are achieved by the illumination optical mechanism 26 in a better and even distribution manner. Scheduled lighting. The subgroups of the field facet 7 can be formed by, for example, each field facet 7 of each field facet group 8. Each of the subgroups may also include the central field facet mirror 6 or one of the two central field facet mirrors 6 of each field facet group 8. For example, the field facet 7 etc. which are the selected field facet 8a in the field facet mirror 6 according to Fig. 6 are shown with hatching. The field facets selected for the subgroup may be slightly wider than the remaining field facets 7 of the field facet group 8 in the y direction, for example. For example, the field facet of the subgroup may be the field facet 7 according to FIG. 8, and the other field facets of the field facet group 8 may be the field facet 7 of FIG. 9. The selection of the primary group can also be achieved by the individual guidance of the radiation sub-beams of the channel formed by the field facets 7 of the field facet subgroup; wherein the pupil facets 11 will be inclined correspondingly . An area between the edge 32 of the useful radiation beam 3 and a boundary 36 is only illuminated by the field facets 7 of the subgroup of field facets (see Figure 10). Viewed from the edge 32, the radiation sub-beams of all other channels exceed the boundary 36. The field facets 7 of the subgroup are selected to ensure that the radiation sub-beams coincide in the field plane 16 near the edge 32 in the most possible way. The individual spacers 27 only have an effect on the intensity of the radiation sub-beams associated with the field facets 7 of the subgroup. As for the channels associated with the field facet 7 of the subgroup, they will pass through the pupil facet mirror 10 evenly. This modified embodiment of overlapping the radiation sub-beam in the field plane 16 can also ensure the field The intensity setting is equipped with the efficiency of the non-dry lighting angle of 24.

The individual spacers 27 may be semi-transparent and/or transparent in at least some parts, so as to be available for a selective setting. The adjacent individual spacers 27 may partially overlap each other along the x direction. Especially in this case, it is more advantageous for the individual spacer 27 to have a variable transmittance through its spread.

The transmittance distribution applicable to the individual spacers 27 is disclosed in, for example, WO 2005/040927 A2.

Instead of finger spacers, other embodiments of the field intensity setting device acting in a plane can also be applied. The example is disclosed in EP 1291721 A1 patent case.

The individual spacers 27 may have a structured end surface, such as the example described in the US 2006/0244941 A1 patent case, especially those in Figures 10 to 12.

<p>1. . . Projection exposure device</p><p>2. . . light source</p><p>3. . . Radiation beam</p><p>4. . . collector</p><p>5. . . Intermediate focal plane</p><p>6. . . Field facet mirror</p><p>7. . . Field facet</p><p>8. . . Field facet group</p><p>8a. . . Selected facet</p><p>9. . . gap</p><p>9a. . . Carrier board</p><p>10. . . Pupil facet mirror</p><p>11. . . Pupil facet</p><p>12, 13, 14. . . EUV mirror</p><p>15. . . Transmission optical mechanism</p><p>16. . . Field plane</p><p>17. . . Indexing mirror plane</p><p>18. . . Indexing mirror</p><p>19. . . Object field</p><p>20. . . Projection optics</p><p>twenty one. . . Image field</p><p>twenty two. . . Image plane</p><p>twenty three. . . Wafer</p><p>twenty four. . . Field intensity setting device</p><p>25. . . Control device</p><p>26. . . Illumination optical mechanism</p><p>26a. . . Optical assembly</p><p>27. . . bead</p><p>28, 29, 30. . . Radiation sub-beam</p><p>31. . . Pupil plane</p><p>32. . . edge</p><p>33. . . Field facet</p><p>34, 35, 36. . . boundary</p>

Figure 1 shows a schematic diagram of a meridian cross-sectional view of an illumination optical mechanism passing through a projection exposure device for micro-development etching;

Figure 2 shows an enlarged cross-sectional view of Figure 1 near the plane of an indexing mirror;

Figure 3 shows a view of a field intensity setting device of the projection exposure device from the direction III in Figure 2;

Figure 4 shows a facet arrangement view of a field facet mirror of the illumination optical mechanism of the projection exposure apparatus according to Figure 1;

Fig. 5 shows a facet arrangement diagram of a pupil facet mirror of the illumination optical mechanism of the projection exposure apparatus according to Fig. 1;

Figure 6 shows another embodiment of a field facet mirror, which is similar to the facet arrangement diagram of Figure 4;

Figure 7 shows a schematic diagram of the optical path of the three selected radiation sub-beams assigned to each specific illumination angle passing through a pupil plane and an indexing mirror plane of the illumination optical mechanism;

Figure 8 shows a field facet according to an embodiment of the field facet mirror of Figure 4;

Figure 9 shows a field facet according to another embodiment of the field facet mirror of Figure 4;

Figure 10 shows that three radiation sub-beams assigned to different illumination angles according to Figure 7 are superimposed on a plane of the field intensity setting device with a changed illumination setting;

Figures 11 to 16 show graphs in which the illumination parameters of the illumination of an indexing mirror become a function of the attenuation (%) of the field intensity setting device in a first illumination pattern; and

Figures 17 to 22 show graphs of the same lighting parameters in another lighting mode, which are optimized to minimize the changes in the lighting parameters caused by the attenuation of the field intensity setting device.