Lithography apparatus and related methods

Abstract

The lithography method involves forming an image of the reticle on a substrate multiple times. Each such imaging process includes illuminating a first portion of the reticle-pellicle assembly with a radiation beam, and focusing the radiation scattered by the reticle and projecting it onto a target area on the substrate using a projection optical system. The lithography method further includes periodically illuminating a second portion of the reticle-pellicle assembly that at least partially surrounds the first portion with a radiation beam. Some pellicles are susceptible to hydrogen etching, and such pellicles are prone to damage in the area surrounding the central portion. Advantageously, by periodically illuminating the second portion of the reticle-pellicle assembly with a radiation beam, hydrogen etching of the second portion of the reticle-pellicle assembly can be suppressed.

Description

[Technical Field]

[0001]

[0001] This application claims priority to European application 23168209.7 filed on 17 April 2023 and European application 23188348.9 filed on 28 July 2023, which are incorporated herein by reference in their entirety.

[0002]

[0002] The present invention relates to apparatus and related methods for processing or using reticle-pellicle assemblies used in extreme ultraviolet (EUV) lithography apparatus. The present invention also relates to reticles that are particularly suitable for use in apparatus and methods for processing reticle-pellicle assemblies. The present invention also relates to pellicles used in lithography apparatus. The present invention also relates to lithography apparatus. [Background technology]

[0003]

[0003] A lithography apparatus is a machine built to apply a desired pattern onto a substrate. A lithography apparatus can be used, for example, in the manufacture of integrated circuits (ICs). A lithography apparatus may, for example, project a pattern from a patterning device (e.g., a mask) onto a radiative material (resist) layer provided on the substrate.

[0004]

[0004] The wavelength of radiation that a lithography apparatus uses to project a pattern onto a substrate determines the minimum size of features that can be formed on that substrate. Using a lithography apparatus that uses EUV radiation, which is electromagnetic radiation with wavelengths in the range of 4 to 20 nm, it is possible to form smaller features on a substrate than with conventional lithography apparatuses (for example, electromagnetic radiation with a wavelength of 193 nm may be used).

[0005]

[0005] A patterning device (e.g., a mask) used to impart a pattern to a radiation beam in a lithography apparatus may constitute part of a mask assembly. The mask assembly may include a pellicle that protects the patterning device from particle contamination. The pellicle may be supported by a pellicle frame.

[0006]

[0006] It may be desirable to provide a device that avoids or mitigates one or more problems related to the prior art. [Overview of the project]

[0007]

[0007] According to a first aspect of the present disclosure, a lithography method is provided which involves forming an image of a reticle multiple times on a substrate, each time including illuminating a first portion of a reticle-pellicle assembly with a radiation beam, and focusing the radiation scattered by the reticle and projecting it onto a target area of ​​the substrate using a projection optical system, and periodically illuminating a second portion of a reticle-pellicle assembly with a radiation beam, at least partially surrounding the first portion.

[0008]

[0008] The lithography method according to the first embodiment is advantageous as will be discussed below.

[0009]

[0009] If there is dirt on the reticle, the image formed on the substrate will generally change, resulting in printing errors. To avoid particle contamination of the reticle, it is known to protect the reticle using a thin film known as a pellicle. The pellicle is placed in front of the reticle to prevent particles from adhering to the reticle. The pellicle is placed so as not to be sharply imaged on the substrate (e.g., a resist-coated wafer), and therefore particles on the pellicle are less likely to interfere with the imaging process than particles on the reticle. One particularly promising material used as a pellicle film in EUV lithography equipment is a carbon nanotube (CNT) fabric, which can provide very high EUV transmittance (over 98%) and very good mechanical stability. However, typically, low-pressure hydrogen gas is supplied inside the lithography equipment, creating a hydrogen plasma in the presence of EUV radiation (during exposure). It has been found that hydrogen ions and hydrogen free radicals from hydrogen plasma can etch the pellicle formed from CNTs, potentially limiting the pellicle's potential lifespan and hindering the commercial implementation of CNT pellicles.

[0010]

[0010] It is known that the etching of carbon by hydrogen ions and free radicals is temperature-dependent. Specifically, it is known that (a) the carbon etching rate is not zero at low temperatures, (b) the carbon etching rate decreases to a negligible level at a threshold temperature beyond which carbon etching remains at a negligible level, and (c) the pellicle in an EUV lithography scanner typically cycles through a temperature range that samples temperatures at which the carbon etching rate is not negligible during each cycle. For example, in an EUV lithography scanner, the EUV emission beam may scan back and forth over the pellicle during operation, resulting in persistent temperature fluctuations.

[0011]

[0011] It has also been found that when the pellicle is heated to a temperature above a threshold level (the level at which hydrogen etching becomes negligible), there is a time delay before the etching rate rises from a negligible level even after the heating is stopped. It is thought that when heated to a sufficient temperature, hydrogen is released from the pellicle, and the hydrogen etching rate decreases to a negligible level. Furthermore, it is thought that the time delay in the increase of the etching rate after the heating is stopped is because it takes a non-zero amount of time for hydrogen to be replenished on the pellicle surface after heating.

[0012]

[0012] The first part of the reticle-pellicle assembly is the part that is illuminated by (EUV) radiation to form an image of the reticle on the substrate. Thus, the first part of the reticle-pellicle assembly may include the image-forming part of the reticle and the corresponding part of the pellicle. The first part of the reticle-pellicle assembly is exposed to EUV radiation during each image-forming process. This causes the first part of the reticle-pellicle assembly to be heated (in the case of a lithography scanner, each part of the first part of the reticle-pellicle assembly is heated periodically at a frequency given by the rate at which the image is formed, i.e., once per die). As will be understood by those skilled in the art, within a lithography apparatus, hydrogen plasma is formed by the EUV radiation (used for exposure of the substrate). Thus, hydrogen plasma is formed in the vicinity of the first part of the reticle-pellicle assembly that is exposed to and heated by EUV radiation. Furthermore, it should be understood that this plasma may extend to peripheral areas that are not directly heated by EUV radiation. As a result, the inventors found that the pellicle is prone to damage in the region surrounding the central part (corresponding to the image-forming area).

[0013]

[0013] Advantageously, by periodically illuminating the second portion of the reticle-pellicle assembly with a radiation beam, hydrogen etching of the second portion of the reticle-pellicle assembly (which at least partially surrounds the first portion) can be suppressed.

[0014]

[0014] In this specification, it should be understood that when a second part partially surrounds a first part, it means that the second part is adjacent to the first part. In this specification, it should be understood that when a second part is adjacent to a first part, it means that the first and second parts are in contact with or share a common boundary with at least a portion of the first part. The second part may extend along and be adjacent to at least one side of the first part (which may be roughly rectangular). The second part may extend along two or more sides of the first part (which may be roughly rectangular) and be adjacent to those sides. In some embodiments, the second part may completely surround the first part. That is, the second part may extend along and be adjacent to all (four) sides of the first part (which may be roughly rectangular).

[0015]

[0015] Periodically illuminating the second portion of the reticle-pellicle assembly with a radiation beam can be achieved by periodically illuminating an expanded exposure field.

[0016]

[0016] The exposure field is the area of ​​the reticle-pellicle assembly that is exposed to radiation. It should be understood that the range of the exposure field in the non-scan direction may be defined by the range of the radiation beam in the non-scan direction (which may be defined by a pair of masking blades). It should be understood that the range of the exposure field in the scan direction may be defined by both the range of the radiation beam in the scan direction (which may be defined by a pair of masking blades) and the range of the scan operation.

[0017]

[0017] Such illumination of the magnified field may be part of the exposure of a target area of ​​the substrate (i.e., part of the image formation process). Alternatively, illumination of the magnified field may occur between the exposure of two target areas of the substrate (i.e., between two image formation processes). For example, illumination of the magnified field may occur between the exposure of different target areas (or dies) of a single substrate, or between the exposure of different substrates.

[0018]

[0018] Illuminating the second part of the reticle - pellicle assembly periodically with a radiation beam may be achieved by changing the exposure field.

[0019]

[0019] It should be understood that the range and / or position of the exposure field can be changed.

[0020]

[0020] The exposure field for at least some imaging processes may be different from the exposure field for the previous imaging process.

[0021]

[0021] At least one edge of the exposure field for each of at least some imaging processes may be offset by an offset.

[0022]

[0022] For example, the offset may be approximately 50 μm. At least one edge of the exposure field may be step - moved by such an offset for each of n exposure processes (e.g., for each exposure process). In some embodiments, all edges of the exposure field may be step - moved by such an offset. The method may use approximately five different positions for each edge of the exposure field, for example, and may step - move or cyclically move the position of each edge of the exposure field to all of the different positions (e.g., five).

[0023]

[0023] The exposure fields for multiple imaging processes may change continuously.

[0024]

[0024] For example, the position of at least one edge of the exposure field may change continuously. For example, the position of at least one edge of the exposure field may oscillate over a range of positions around the nominal position. The amplitude of such oscillation may be approximately 100 μm. In some embodiments, all edges of the exposure field may change continuously.

[0025]

[0025] During each imaging process, at least one masking blade may be used to mask adjacent target regions of the substrate from the radiation beam.

[0026]

[0026] Preferably, four masking blades may be used to define an exposure region and mask target regions adjacent to all four sides of the exposure region. The exposure field may be defined by the exposure region, the scan length, and the position of the four masking blades.

[0027]

[0027] In some embodiments, illuminating the enlarged exposure field or changing the exposure field may be achieved by controlling at least one masking blade.

[0028]

[0028] The position of at least one reticle masking blade may be manipulated such that the outer perimeter of the exposure region extends into the expansion area.

[0029]

[0029] For example, the outer perimeter of the exposure region may extend into an area having a dimension of approximately 100 μm.

[0030]

[0030] In some embodiments, during the exposure of each target region, four masking blades may be used to define the exposure field, and for each target region adjacent to the edge of the substrate, at least one of the masking blades corresponding to the edge of the exposure field adjacent to the edge of the substrate may be positioned to expand the exposure field.

[0031]

[0031] Target regions adjacent to the edges of the substrate are sometimes called edge target regions or edge dies. It should be understood that such edge target regions do not have adjacent target regions on all sides. Rather, each edge target region does not have adjacent nearby target regions on at least one side (adjacent to the edge of the substrate). For such edge target regions (or dies) on the substrate, a masking blade may be positioned to expand the exposure area. For example, for such edge target regions (or dies) on the substrate, the masking blade may be shifted by 1 mm or more from its nominal position to expand the exposure area. Advantageously, this will illuminate the portion of the reticle-pellicle assembly adjacent to the first portion of the reticle-pellicle assembly with the radiation beam. When the masking blade is controlled in this way for all such edge dies, the portion of the reticle-pellicle assembly substantially surrounding the first portion of the reticle-pellicle assembly can be illuminated with radiation.

[0032]

[0032] Forming a reticle image multiple times on a substrate may include forming a reticle image on multiple target regions of the substrate. Each of the multiple target regions may be roughly rectangular. The multiple target regions may be arranged as a two-dimensional array.

[0033]

[0033] In some embodiments, a two-dimensional array of target regions may be exposed using a standard meandering scan pattern in which each row of target regions (extending in the non-scanning direction) is exposed sequentially. One target region in each row has no adjacent target regions on one side, and another target region has no adjacent target regions on the other side. Thus, in such a configuration, a portion of the reticle-pellicle assembly that is adjacent to the first portion of the reticle-pellicle assembly but offset in the non-scanning direction can be radiated during the exposure of each row. In contrast, during the exposure of the first half of the substrate, there are some target regions that do not have adjacent target regions on the first side in the scanning direction, but there are no target regions that do not have adjacent target regions on the other (second) side in the scanning direction. Similarly, during the exposure of the first half of the substrate, there are some target regions that do not have adjacent target regions on the second side in the scanning direction, but there are no target regions that do not have adjacent target regions on the first side in the scanning direction.

[0034]

[0034] In some embodiments, in order to increase the frequency of target regions that do not have adjacent target regions on the first or second side in the scanning direction, an exposure pattern may be used in which multiple rows of target regions (extending in the non-scanning direction) are exposed in a different order to expose the two-dimensional array of target regions.

[0035]

[0035] Forming a reticle image multiple times on a substrate may include forming a reticle image on multiple target regions of a substrate arranged as a two-dimensional array, where the two-dimensional array of target regions may be exposed one row at a time, and the rows may be exposed in no particular order.

[0036]

[0036] Each image-forming process may include scanning exposure, in which the reticle-pellicle assembly is moved in the scanning direction relative to the radiation beam.

[0037]

[0037] In embodiments in which the magnified exposure field is illuminated periodically, radiation scattered from the magnified exposure field of the reticle-pellicle assembly may not be projected onto the substrate.

[0038]

[0038] For example, in some embodiments, the substrate may be moved so that radiation scattered from the reticle-pellicle assembly does not enter the substrate. Alternatively, in some embodiments, a shutter may be closed to prevent radiation scattered from the reticle-pellicle assembly from entering the substrate.

[0039]

[0039] Generally, the duration of periodic illumination of the second portion of the reticle-pellicle assembly by the radiation beam may be long enough to heat the second portion of the pellicle to a desired temperature (e.g., to a temperature above a threshold temperature at which hydrogen etching of the pellicle can be ignored). In some embodiments, the desired temperature may be above 900K. It should be understood that the time required to heat the pellicle to the desired temperature will depend on the output of the radiation beam while the pellicle is being heated.

[0040]

[0040] Periodically illuminating the second portion of the reticle-pellicle assembly with a radiation beam may include exposing the second portion to EUV radiation to heat the pellicle to a temperature at which the hydrogen etching rate of the pellicle is negligible.

[0041]

[0041] For example, periodically illuminating a second portion of the reticle-pellicle assembly with a radiation beam may include exposing the second portion to EUV radiation to heat the pellicle to a temperature above 800K, for example, above 900K.

[0042]

[0042] Generally, the time between two consecutive illuminations of the second part of the reticle-pellicle assembly with the radiation beam may be short enough so that the surface of the pellicle does not become saturated with hydrogen after heating by the first illumination. Again, it should be understood that the time required for the surface of the pellicle to become saturated with hydrogen after heating by the first illumination will depend on the conditions in the vicinity of the pellicle. In some embodiments, the time between two consecutive illuminations of the second part of the reticle-pellicle assembly may be approximately 100 ms.

[0043]

[0043] Periodically illuminating the second portion of the reticle-pellicle assembly with a radiation beam may mean that the second portion of the reticle-pellicle assembly is illuminated once per substrate.

[0044]

[0044] Periodically illuminating the second portion of the reticle-pellicle assembly with a radiation beam may mean that the second portion of the reticle-pellicle assembly is illuminated once for each row of target areas on the substrate.

[0045]

[0045] A second aspect of the present disclosure provides a lithography component for a lithography apparatus, the lithography component comprising: a support structure constructed to support a reticle-pellicle assembly for receiving a radiation beam; and a controller that performs an image-forming process which includes (a) forming an image of a reticle supported by the support structure on a substrate multiple times, each time including illuminating a first portion of the reticle-pellicle assembly with a radiation beam and projecting the radiation scattered by the reticle onto a target area of ​​the substrate using a projection optical system; and (b) a controller that is operable to control the support structure and / or the radiation beam to periodically illuminate a second portion of the reticle-pellicle assembly with a radiation beam that at least partially surrounds the first portion.

[0046]

[0046] The lithography component according to the second embodiment is advantageous as will be discussed below.

[0047]

[0047] As discussed above, a pellicle placed in front of the reticle can prevent particles from adhering to the reticle, thereby improving optical performance (by reducing printing errors). One particularly promising material used as a pellicle film in EUV lithography equipment is a carbon nanotube (CNT) fabric, but CNT pellicles are susceptible to hydrogen etching. It is known that the etching of carbon by hydrogen ions and free radicals decreases to a negligible level at a threshold temperature beyond which carbon etching remains at a negligible level. It is also known that when the pellicle is heated to a temperature above the threshold level (where hydrogen etching becomes negligible), there is a time delay before the etching rate rises above a negligible level even after the heating is removed.

[0048]

[0048] The first part of the reticle-pellicle assembly is the part that is illuminated by (EUV) radiation to form an image of the reticle on the substrate. Thus, the first part of the reticle-pellicle assembly may include the image-forming part of the reticle and the corresponding part of the pellicle. The first part of the reticle-pellicle assembly is exposed to EUV radiation during each image-forming process. This causes the first part of the reticle-pellicle assembly to be heated (in the case of a lithography scanner, each part of the first part of the reticle-pellicle assembly is heated periodically at a frequency given by the rate at which the image is formed, i.e., once per die). As will be understood by those skilled in the art, within a lithography apparatus, hydrogen plasma is formed by the EUV radiation (used for exposure of the substrate). Thus, hydrogen plasma is formed in the vicinity of the first part of the reticle-pellicle assembly that is exposed to and heated by EUV radiation. Furthermore, it should be understood that this plasma may extend to peripheral areas that are not directly heated by EUV radiation. As a result, the inventors found that the pellicle is prone to damage in the region surrounding the central part (corresponding to the image-forming area).

[0049]

[0049] Advantageously, by periodically illuminating the second portion of the reticle-pellicle assembly with a radiation beam, hydrogen etching of the second portion of the reticle-pellicle assembly (which at least partially surrounds the first portion) can be suppressed.

[0050]

[0050] The controller may be operable to carry out the method of the first aspect of the present disclosure.

[0051]

[0051] The lithography component may further include a scanning mechanism that can move the support structure in the scanning direction relative to the radiation beam.

[0052]

[0052] The scanning mechanism may also be operable to move the substrate table of the lithography apparatus relative to the projection system of the lithography apparatus so that the image of the reticle formed by the projection system is substantially stationary relative to the substrate. This may be described as synchronous movement of the support structure and the substrate table. The movement (direction and velocity) of the substrate table relative to the support structure will generally depend on the image inversion and magnification characteristics of the projection system.

[0053]

[0053] The controller may be capable of operating to control the scanning mechanism.

[0054]

[0054] The lithography component may further include a first pair of masking blades configured to define a range of the exposure area in a first direction, and a second pair of masking blades configured to define a range of the exposure area in a second direction.

[0055]

[0055] The first and second pairs of masking blades may be movable to change the range of the exposure area. The controller may be operable to control the position of each of the first and second pairs of masking blades. When in use, the two pairs of masking blades may be used to define the exposure area and to mask target areas adjacent to all four sides of the exposure area.

[0056]

[0056] The first direction is the scanning direction, and in order to form an image of the reticle supported by the support structure on a target area of ​​the substrate, the controller may be operable to control the scanning mechanism to move the reticle supported by the support structure within the exposure area and to control the position of a first pair of masking blades to mask adjacent target areas of the substrate from the radiation beam.

[0057]

[0057] As the target region of the substrate moves into the exposure region, the first pair of masking blades move so that only the target region receives radiation (i.e., no part of the substrate outside the target region is exposed). At the start of scan exposure, one of the first pair of masking blades is positioned in the path of the radiation beam and acts as a shutter, so that no part of the substrate receives radiation. At the end of scan exposure, the other of the first pair of masking blades is positioned in the path of the radiation beam and acts as a shutter, so that no part of the substrate receives radiation. In the middle of scan exposure, when there is no overlap between the exposure region (which receives radiation) and any adjacent target region of the substrate, both of the first pair of masking blades are positioned in the retracted position.

[0058]

[0058] In order to illuminate the second portion of the reticle-pellicle assembly with the radiation beam, the controller may be operable to control the first and / or second pair of masking blades to illuminate the expanded exposure field.

[0059]

[0059] The exposure field is the area of ​​the reticle-pellicle assembly that is exposed to radiation. It should be understood that the range of the exposure field in the non-scan direction may be defined by the range of the radiation beam in the non-scan direction (which may be defined by a pair of masking blades). It should be understood that the range of the exposure field in the scan direction may be defined by both the range of the radiation beam in the scan direction (which may be defined by a pair of masking blades) and the range of the scan operation.

[0060]

[0060] Such illumination of the magnified field may be part of the exposure of a target area of ​​the substrate (i.e., part of the image formation process). Alternatively, illumination of the magnified field may occur between the exposure of two target areas of the substrate (i.e., between two image formation processes). For example, illumination of the magnified field may occur between the exposure of different target areas (or dies) of a single substrate, or between the exposure of different substrates.

[0061]

[0061] In order to illuminate a second portion of the reticle-pellicle assembly with a radiation beam, the controller may be operable to control the first and / or second pair of masking blades to vary the exposure field.

[0062]

[0062] It should be understood that the range and / or position of the exposure field may be changed.

[0063]

[0063] The controller may be operable to control the first and / or second pair of masking blades such that the exposure field for at least some of the imaging processes is different from the exposure field for the previous imaging process.

[0064]

[0064] For example, the controller may be operable to control the first and / or second pair of masking blades so that at least one edge of the exposure field for each of at least some of the image formation processes is offset by a certain amount.

[0065]

[0065] For example, the offset may be approximately 50 μm. At least one edge of the exposure field may be stepped by such an offset for every n exposure processes (e.g., per exposure process). In some embodiments, all edges of the exposure field may be stepped by such an offset. The method implemented by the controller may, for example, use approximately five different positions for each edge of the exposure field, and the position of each edge of the exposure field may be stepped or cycled through all (e.g., five) different positions.

[0066]

[0066] The controller may be operable to control the first and / or second pair of masking blades so that the exposure field for multiple image formation processes is continuously changing.

[0067]

[0067] For example, the position of at least one edge of the exposure field may be continuously changing. For example, the position of at least one edge of the exposure field may oscillate over a range of positions around the nominal position. The amplitude of such oscillation may be approximately 100 μm. In some embodiments, all edges of the exposure field may be continuously changing.

[0068]

[0068] In order to illuminate the second portion of the reticle-pellicle assembly with the radiation beam, the controller may be operable to control the first and / or second pair of masking blades so that the outer edge of the exposure area extends into the expanded area.

[0069]

[0069] For example, the outer edge of the exposure area may extend to an area with dimensions of approximately 100 μm.

[0070]

[0070] In order to illuminate the second portion of the reticle-pellicle assembly with a radiation beam, the controller may be operable to control the first and / or second pair of masking blades such that at least one of the masking blades corresponding to the edge of the exposure field adjacent to the edge of the substrate is positioned to expand the exposure field when forming an image of the reticle supported by the support structure on a target area of ​​the substrate adjacent to the edge of the substrate.

[0071]

[0071] Target regions adjacent to the edges of the substrate are sometimes called edge target regions or edge dies. It should be understood that such edge target regions do not have adjacent target regions on all sides. Rather, each edge target region does not have adjacent nearby target regions on at least one side (adjacent to the edge of the substrate). For such edge target regions (or dies) on the substrate, a masking blade may be positioned to expand the exposure area. For example, for such edge target regions (or dies) on the substrate, the masking blade may be shifted by 1 mm or more from its nominal position to expand the exposure area. Advantageously, this will illuminate the portion of the reticle-pellicle assembly adjacent to the first portion of the reticle-pellicle assembly with the radiation beam. When the masking blade is controlled in this way for all such edge dies, the portion of the reticle-pellicle assembly substantially surrounding the first portion of the reticle-pellicle assembly can be illuminated with radiation.

[0072]

[0072] Forming a reticle image multiple times on a substrate may include forming a reticle image on multiple target regions of the substrate. Each of the multiple target regions may be roughly rectangular. The multiple target regions may be arranged as a two-dimensional array.

[0073]

[0073] Generally, the duration of periodic illumination of the second portion of the reticle-pellicle assembly by the radiation beam may be long enough to heat the second portion of the pellicle to a desired temperature (e.g., to a temperature above a threshold temperature at which hydrogen etching of the pellicle can be ignored). In some embodiments, the desired temperature may be above 900K. It should be understood that the time required to heat the pellicle to the desired temperature will depend on the output of the radiation beam while the pellicle is being heated.

[0074]

[0074] When the second portion of the reticle-pellicle assembly is illuminated with a radiation beam, the controller may be able to operate to heat the pellicle to a temperature at which the hydrogen etching rate of the pellicle is negligible.

[0075]

[0075] For example, the controller may be capable of operating to heat the pellicle to a temperature above 800K, for example, above 900K.

[0076]

[0076] According to a third aspect of the present disclosure, a lithography apparatus is provided that comprises the components of the second aspect of the present disclosure.

[0077]

[0077] The lithography apparatus may further include an illumination system configured to adjust the radiant beam received by the reticle-pellicle assembly, a substrate table constructed to support the substrate, and a projection system configured to receive the radiant beam from the reticle-pellicle assembly and project the radiant beam onto the substrate.

[0078]

[0078] According to a fourth aspect of the present disclosure, a pellicle for use in a lithography apparatus is provided, the pellicle comprising a frame and a film surrounded and supported by the frame, wherein the film is generally planar, defining the plane of the pellicle, and the frame having a thickness generally perpendicular to the plane of the pellicle and a width generally parallel to the plane of the pellicle, wherein the outer portion of the frame is in contact with the film in the plane of the pellicle, and along at least one edge of the film, the inner portion of the frame is thinner than the outer portion of the frame so as not to be in contact with the film.

[0079]

[0079] During use, the film is subjected to a thermal load from the radiation used by the lithography apparatus (e.g., EUV radiation), while the frame remains cool. The area of ​​the film in contact with the frame is cooler due to the presence of the frame (which has greater thermal inertia than the film due to its larger dimensions). The pellicle according to the fourth aspect of the disclosure is advantageous because it allows the contact point between the frame and the film to be moved outward along at least one edge of the film without reducing the width of the frame (i.e., the dimensions of the frame roughly parallel to the plane of the pellicle). This allows the frame to maintain a similar level of rigidity while moving the contact point between the frame and the film outward. Furthermore, advantageously, by moving outward the portion of the film that is in contact with the frame (and is cooler than other parts of the film during use), the film is exposed to little to no high-intensity EUV-induced hydrogen plasma.

[0080]

[0080] The recess formed between the inner portion of the thin frame and the film may have a generally uniform thickness.

[0081]

[0081] Alternatively, the recess formed between the thin inner portion of the frame and the film may have a thickness that varies from the inner edge of the frame to the outer portion of the frame.

[0082]

[0082] It should be understood that the width of the inner portion of the thin frame may be selected so that the portion of the film that is in contact with the frame (and is at a lower temperature than other parts of the film during use) is not adjacent to the high-intensity EUV-induced hydrogen plasma.

[0083]

[0083] The width of the inner part of a thin frame may be greater than 2 mm.

[0084]

[0084] The width of the inner portion of the thin frame may be greater than 2.2 mm. In some embodiments, the width of the inner portion of the thin frame may be approximately 2.5 mm.

[0085]

[0085] A fifth aspect of the present disclosure provides a lithography apparatus comprising a frame and a pellicle having a film surrounded and supported by the frame, a hydrogen source and an illumination system configured to illuminate the pellicle by radiation, wherein the portion of the film in contact with the frame is positioned so as not to diffuse the EUV-induced hydrogen plasma.

[0086]

[0086] Advantageously, since the portion of the film in contact with the frame is positioned so that the EUV-induced hydrogen plasma does not diffuse, the film is less susceptible to etching by the plasma. The pellicle of a lithography apparatus according to the fifth aspect of this disclosure may include a pellicle according to the fourth and / or sixth aspect of this disclosure.

[0087]

[0087] According to a sixth aspect of the present disclosure, a pellicle for use in a lithography apparatus is provided, the pellicle comprising a frame, a membrane surrounded and supported by the frame, and a shield adjacent to the peripheral portion of the membrane adjacent to the frame, wherein the membrane is generally planar, defining the plane of the pellicle, and the shield is spaced apart from the membrane in a direction generally perpendicular to the plane of the pellicle.

[0088]

[0088] The pellicle according to the sixth aspect of the present disclosure is advantageous because the shield can protect the pellicle from etching by plasma (e.g., EUV-induced hydrogen plasma) when used, for example, in an EUV lithography apparatus.

[0089]

[0089] Conventionally, it has been thought that a reticle machining blade could function as a plasma shield for the pellicle. However, it has recently been found that the region where etching of the CNT film progresses most is outside the exposure area, below the reticle machining blade (this indicates that the reticle machining blade is not effective as a plasma shield for the pellicle). It is thought that the distance between the reticle machining blade and the pellicle film is too large to provide an effective shielding function. In use, there is usually not a large space between the pellicle film and other components (e.g., the reticle machining blade), but there is sufficient space for a relatively thin shield, and it is thought that the pellicle according to the sixth aspect of this disclosure can be used in existing lithography apparatus.

[0090]

[0090] The shield extends beyond the pellicle boundary but may remain outside the quality area (or the portion of the pellicle corresponding to the image-forming area of ​​the reticle).

[0091]

[0091] The pellicle according to the sixth aspect of the present disclosure may, if necessary, have any of the features of the pellicle according to the fourth aspect of the present disclosure.

[0092]

[0092] The shield may include a first shielding member adjacent to a first surface of the peripheral portion of the film, and a second shielding member adjacent to a second surface of the peripheral portion of the film.

[0093]

[0093] The first surface may be the surface that faces away from the reticle when the pellicle is in use (and may be called the top or front surface of the pellicle). The second surface may be the surface that faces towards the reticle when the pellicle is in use (and may be called the bottom or rear surface of the pellicle).

[0094]

[0094] It may be desirable for the shield to be as close as possible to the surface of the film. This is to minimize the amount of plasma diffusing beneath the shield (i.e., between the shield and the film) and maximize plasma shielding. Generally, it may be desirable for the distance between the shield and the surface of the film to be less than the Debye length of the plasma (which may be less than 1 mm, or less than 0.2 mm during EUV pulses). It may also be desirable for the shield to be far enough away from the surface of the film to allow for some sagging of the film without the risk of the shield contacting the surface of the film.

[0095]

[0095] In embodiments in which the shield comprises a first shielding member and a second shielding member, it should be understood that the first shielding member and the second shielding member may be positioned at different distances from the membrane. Alternatively, the first shielding member and the second shielding member may be positioned at substantially the same distance from the membrane.

[0096]

[0096] The distance between the shield and the film may be less than 1 mm. For example, the distance between the shield and the surface of the film may be approximately 200 μm to 1000 μm. For example, the distance between the shield and the surface of the film may be approximately 400 μm to 800 μm.

[0097]

[0097] It should be understood that the distance between the first shielding member and the film may be less than 1 mm, and / or the distance between the second shielding member and the film may be less than 1 mm. In particular, the distance between the front surface of the film and the adjacent shielding member may be less than 1 mm.

[0098]

[0098] The shield may be less than 1 mm thick. The shield may be about 100 μm to 300 μm thick. The shield may be about 200 μm or less thick. The thickness of the shield may be selected based on readily available market materials.

[0099]

[0099] The shield may extend approximately 1 mm to 1.5 mm away from the frame in a plane parallel to the film.

[0100] [000100] Preferably, the shield may extend to cover portions that, if there is no shield, are adjacent to the plasma when the film is in use but do not receive EUV radiation. The shield may be located about 0.5 mm to 1.5 mm away from the quality area of ​​the pellicle (i.e., the portion of the pellicle corresponding to the image-forming area of ​​the reticle) so as not to interfere with the EUV light cone.

[0101] [000101] The shield may be formed from a material that transmits wavelengths of radiation used to periodically heat the pellicle during use.

[0102] [000102] For example, the shield may be formed from a material that transmits infrared (IR) and / or deep ultraviolet (DUV) radiation. This allows the shield to periodically heat the film using these radiations while protecting the pellicle from the plasma.

[0103] [000103] The shield may be formed from a material that is inert to hydrogen plasma.

[0104] [000104] The shield may contain sapphire (Al2O3).

[0105] [000105] For example, the shield may include a sapphire (Al2O3) coated glass material. Alternatively, the shield may be formed from sapphire.

[0106] [000106] A seventh aspect of the present disclosure provides a lithography apparatus comprising a frame, a film surrounded and supported by the frame, and a pellicle having a shield adjacent to the periphery of the film adjacent to the frame, a hydrogen source, and an illumination system configured to illuminate the pellicle by radiation, wherein the shield is adjacent to a portion of the film to which, in the absence of such shield, EUV-induced hydrogen plasma would diffuse.

[0107] [000107] Advantageously, since the shield is part of the film and adjacent to a portion where EUV-induced hydrogen plasma would diffuse in the absence of such shield, the shield protects the film from the plasma (and associated plasma etching) that would be present in the absence of such shield. The pellicle of a lithography apparatus according to the seventh aspect of the present disclosure may include the pellicle according to the fourth and / or sixth aspects of the present disclosure.

[0108] [000108] It should be understood that one or more aspects or features referred to in the above or below descriptions may be combined with one or more other aspects or features. [Brief explanation of the drawing]

[0109] [000109] Embodiments of the present invention will be described below as merely illustrative examples with reference to the attached schematic diagrams.

[0110] [Figure 1] This is a schematic diagram of a lithography system equipped with a lithography device and a radiation source. [Figure 2A] This is a schematic plan view of the support structure and patterning device shown in Figure 1, which are located at the first end position. [Figure 2B] This is a schematic plan view of the support structure and patterning device shown in Figure 1, which are located at the second end position. [Figure 3A] Figure 1 is a schematic diagram of the first cross-section of the patterning device and reticle masking blade on the support structure of the lithography apparatus. [Figure 3B] Figure 1 is a schematic diagram of a second cross-section of the patterning device and reticle masking blade on the support structure of the lithography apparatus. [Figure 4] This is a plan view showing the y-masking blade and x-masking blade (dotted lines) of the lithography apparatus in the first configuration shown in Figure 1. [Figure 5]The expected etching rates of hydrogen etching of carbon are shown as a function of temperature for hydrogen ion fluxes of 1.5·10¹⁹m-²·s-¹ at four different ion energies, namely 5eV, 10eV, 20eV, and 30eV, and similarly, the sp3 carbon concentration is shown as a function of temperature. [Figure 6] This is a schematic qualitative graph of the hydrogen etching rate as a function of time after the heating period has ended and the material has been heated to a temperature at which hydrogen etching can be ignored. [Figure 7] This is a schematic diagram of a new lithography method according to the embodiment of this disclosure. [Figure 8] Figure 7 is a schematic plan view of a reticle-pellicle assembly 15 that may be used in the lithography method. [Figure 9] This graph shows the change in resist height on a wafer exposed to EUV radiation via a pellicle as a function of the non-scanned position (x position), and the EUV transmittance of the CNT pellicle as a function of the non-scanned position (x position). [Figure 10] A flowchart of the first embodiment of the method shown in Figure 7 is shown. [Figure 11A] This describes a standard lithography method that uses a standard exposure field n × m times to form an image on a target area on a substrate. [Figure 11B] Figure 10 shows a lithography method in which an image is formed on a target area on a substrate using a standard exposure field n times, followed by one exposure using an enlarged exposure field, and this n+1 exposure process is repeated m times. [Figure 12] A flowchart of a second embodiment of the method shown in Figure 7 is shown. [Figure 13] This graph shows the change in resist height on a wafer exposed to EUV radiation via a pellicle as a function of the non-scanned position (x position) at the reticle level. It shows the EUV transmittance of the CNT pellicle as a function of the non-scanned position (x position) for (a) a standard lithography method (solid line) and (b) a novel lithography method in Figure 12 in which the masking blade is stepped in 10 steps of 2 mm each (dashed line). [Figure 14] A flowchart of the third embodiment of the method shown in Figure 7 is shown. [Figure 15] This is a schematic plan view of a (generally circular) substrate containing multiple (generally rectangular) target regions or dies, and also shows a typical meandering scan pattern in which each row of target regions (extending in the non-scanning direction) is exposed sequentially. The exposure order of the target regions is indicated by numbers on each target region, the scan direction of exposure for each target region is indicated by solid arrows, and the movement of the substrate between the exposure of two consecutive target regions C is indicated by dashed lines. [Figure 16] A cross-sectional view shows a portion of the reticle-pellicle assembly, including the reticle, pellicle frame, and pellicle film, as well as a masking blade, a portion that may receive EUV radiation when the pellicle is in use, and a portion that does not receive EUV radiation when the pellicle is in use but is exposed to hydrogen plasma. [Figure 17A] This is a schematic cross-sectional view of a known pellicle. [Figures 17B-17D] These are schematic cross-sectional views of three new pellicle portions, where, along at least one edge of the membrane, the inner portion of the frame has a thinner thickness than the outer portion of the frame, so that the inner portion of the frame does not come into contact with the membrane. [Figure 17E] Figure 17A shows a modified version of a known pellicle, but it is a schematic cross-sectional view of a portion of a new pellicle that is narrower than the known pellicle. [Figure 18] A novel reticle-pellicle assembly according to the present disclosure is shown, comprising a novel pellicle with a shield for protecting the peripheral portion of the film from hydrogen plasma etching. [Figure 19] Figure 18 shows an enlarged view of the new reticle-pellicle assembly. [Modes for carrying out the invention]

[0111] [000110] Figure 1 shows a lithography system. The lithography system comprises a radiation source SO and a lithography apparatus LA. The radiation source SO is configured to generate an extreme ultraviolet (EUV) radiation beam B. The lithography apparatus LA comprises an illumination system IL, a support structure MT configured to support a reticle assembly 15 equipped with a patterning device MA (e.g., a reticle or mask), a projection system PS, and a substrate table WT configured to support a substrate W. The illumination system IL is configured to adjust the radiation beam B before it is incident on the patterning device MA. The projection system is configured to project the radiation beam B (now patterned by the patterning device MA) onto the substrate W. The substrate W may contain a previously formed pattern. In this case, the lithography apparatus aligns the patterned radiation beam B with the pattern previously formed on the substrate W.

[0112] [000111] The radiation source SO, the illumination system IL, and the projection system PS may all be constructed and positioned to be isolated from the external environment. A gas at a pressure lower than atmospheric pressure (e.g., hydrogen) may be supplied into the radiation source SO. A vacuum may be provided in the illumination system IL and / or the projection system PS. A small amount of gas at a pressure considerably lower than atmospheric pressure (e.g., hydrogen) may be supplied into the illumination system IL and / or the projection system PS.

[0113] [000112] The radiation source SO shown in Figure 1 is of a type that may be called a laser-generated plasma (LPP) source. Laser 1, which may be a CO2 laser, is configured to impart energy to a fuel such as tin (Sn) supplied from a fuel ejector 3 via a laser beam 2. In the following description, tin will be mentioned, but any suitable fuel may be used. The fuel may be in the form of a liquid, for example, or a metal or alloy, for example. The fuel ejector 3 may have a nozzle configured to guide tin, for example, in the form of droplets, along a trajectory toward the plasma-forming region 4. Laser beam 2 is incident on the tin in the plasma-forming region 4. When laser energy is imparted to the tin, plasma 7 is generated in the plasma-forming region 4. During the de-excitation and recombination of ions in the plasma, radiation including EUV radiation is emitted from the plasma 7.

[0114] [000113] EUV radiation is focused and concentrated by a per-normal incident radiation collector 5 (sometimes more commonly called a normal incident radiation collector). Collector 5 may have a multilayer structure configured to reflect EUV radiation (e.g., EUV radiation having a desired wavelength such as 13.5 nm). Collector 5 may have an elliptical configuration with two elliptical foci. As will be discussed below, the first focal point may be in the plasma-forming region 4 and the second focal point may be in the intermediate focal point 6.

[0115] [000114] In other embodiments of the laser-generated plasma (LPP) source, the collector 5 may be a so-called oblique incidence collector configured to receive EUV radiation at a grazing incidence angle and focus the EUV radiation to an intermediate focal point. The oblique incidence collector may be a nested collector comprising, for example, multiple oblique incidence reflectors. The oblique incidence reflectors may be arranged axially symmetrically with respect to the optical axis.

[0116] [000115] The radiation source SO may include one or more contamination traps (not shown). For example, a contamination trap may be located between the plasma-forming region 4 and the radiation collector 5. The contamination trap may be, for example, a rotating foil trap or any other suitable form of contamination trap.

[0117] [000116] Laser 1 may be separated from the radiation source SO. In this case, the laser beam 2 may be passed from laser 1 to the radiation source SO using a beam delivery system (not shown) that includes, for example, a suitable guide mirror, a beam expander, and / or other optical systems. Laser 1 and the radiation source SO may together be considered as a radiation system.

[0118] [000117] The radiation reflected by the collector 5 forms a radiation beam B. The radiation beam B is focused at point 6 to form an image of the plasma-forming region 4, which serves as a virtual radiation source for the illumination system IL. Point 6, where the radiation beam B is focused, is sometimes called the intermediate focus. The radiation source SO is positioned such that the intermediate focus 6 is located at or near the opening 8 of the closed structure 9 of the radiation source SO.

[0119] [000118] The radiation beam B passes from the radiation source SO to an illumination system IL configured to adjust the radiation beam. The illumination system IL may include a faceted field mirror device 10 and a faceted pupil mirror device 11. The faceted field mirror device 10 and the faceted pupil mirror device 11 work together to give the radiation beam B a desired cross-sectional shape and a desired angular distribution. The radiation beam B passes through the illumination system IL and is incident on a reticle assembly 15 held by a support structure MT. The reticle assembly 15 includes a patterning device MA and a pellicle 19. The pellicle is attached to the patterning device MA via a pellicle frame 17. The reticle assembly 15 may be called a reticle-pellicle assembly 15. The patterning device MA reflects the radiation beam B and imparts a pattern to it. The illumination system IL may include other mirrors or devices in addition to, or instead of, the faceted field mirror device 10 and the faceted pupil mirror device 11.

[0120] [000119] Following reflection from the patterning device MA, the patterned radiant beam B enters the projection system PS. The projection system comprises several mirrors 13, 14 configured to project the radiant beam B onto a substrate W held by a substrate table WT. The projection system PS may apply a reduction factor to the radiant beam to form an image with features smaller than the corresponding features on the patterning device MA. For example, a reduction factor of 4 may be applied. In Figure 1, the projection system PS has two mirrors 13, 14, but the projection system PS may include any number of mirrors (e.g., six mirrors).

[0121] [000120] A lithography apparatus may be used, for example, in scan mode, in which a pattern applied to the radiation beam is projected onto the substrate W while the support structure (e.g., mask table) MT and the substrate table WT are scanned synchronously (i.e., dynamic exposure). The velocity and direction of the substrate table WT relative to the support structure (e.g., mask table) MT may be determined by the reduction and image inversion characteristics of the projection system PS. The patterned radiation beam incident on the substrate W may include a radiation band. The radiation band may be called the exposure slit. During scan exposure, the exposure slit may move across the exposure field of the substrate W as the substrate table WT and the support structure MT move.

[0122] [000121] The radiation source SO and / or lithography apparatus shown in Figure 1 may include components not shown. For example, a spectral filter may be provided within the radiation source SO. The spectral filter may be substantially transparent to EUV radiation but substantially block radiation of other wavelengths, such as infrared radiation.

[0123] [000122] In other embodiments of the lithography system, the radiation source SO may take other forms. For example, in an alternative embodiment, the radiation source SO may comprise one or more free-electron lasers. The one or more free-electron lasers may be configured to emit EUV radiation that can be supplied to one or more lithography devices.

[0124] [000123] As briefly described above, the reticle assembly 15 includes a pellicle 19 provided adjacent to the patterning device MA. The pellicle 19 is provided in the path of the radiation beam B so that it passes through the pellicle 19 both when the radiation beam B approaches the patterning device MA from the illumination system IL and when it is reflected by the patterning device MA and heads toward the projection system PS. The pellicle 19 includes a thin film or membrane that substantially transmits EUV radiation (but absorbs a small amount of EUV radiation). In this specification, an EUV-transmitting pellicle or a membrane that substantially transmits EUV radiation means that the pellicle 19 transmits at least 65% of the EUV radiation, preferably at least 80%, and more preferably at least 90%. The pellicle 19 serves to protect the patterning device MA from particle contamination.

[0125] [000124] Although efforts are made to maintain a clean environment inside the lithography apparatus LA, particles may still be present inside the lithography apparatus LA. Without the pellicle 19, particles may adhere to the patterning device MA. Particles on the patterning device MA may adversely affect the pattern applied to the radiation beam B and, consequently, the pattern transferred to the substrate W. The pellicle 19 advantageously provides a barrier between the patterning device MA and the environment inside the lithography apparatus LA to prevent particles from adhering to the patterning device MA.

[0126] [000125] The pellicle 19 is positioned sufficiently far from the patterning device MA so that particles incident on the surface of the pellicle 19 do not fall within the field plane of the lithography apparatus LA. This distance between the pellicle 19 and the patterning device MA serves to limit the extent to which particles on the surface of the pellicle 19 impart a pattern to the radiation beam B that is imaged onto the substrate W. It should be understood that even if a particle is present in the radiation beam B, if its position is not within the field plane of the radiation beam B (for example, not on the surface of the patterning device MA), the image of that particle will not be focused on the surface of the substrate W. If there are no other considerations, it may be desirable to position the pellicle 19 considerably far from the patterning device MA. However, in practice, the space available for housing the pellicle within the lithography apparatus LA is limited due to the presence of other components. In some embodiments, the distance between the pellicle 19 and the patterning device MA may be, for example, about 1 mm to 10 mm, for example 1 mm to 5 mm, or for example 2 mm to 2.5 mm.

[0127] [000126] The pellicle may include a boundary and a film. The boundary of the pellicle may be hollow and generally rectangular, and the film may be bordered by the boundary. As is known in the art, the pellicle may be formed by depositing one or more thin layers of material onto a generally rectangular silicon substrate. The silicon substrate supports one or more thin layers during this construction stage of the pellicle. Once layers of the desired or target thickness and composition are deposited, the central part of the silicon substrate is removed by etching (this is sometimes called back etching). The periphery of the rectangular silicon substrate is not etched (or alternatively, etched less than the central part). This periphery forms the boundary of the final pellicle, while one or more thin layers form the film of the pellicle (bordered by the boundary). The boundary of the pellicle may be formed from silicon.

[0128] [000127] Such pellicles may require some support from a more rigid pellicle frame. The pellicle frame may provide two functions. First, the pellicle frame may support the pellicle and keep the pellicle membrane taut. Second, the pellicle frame may facilitate the connection of the pellicle to a patterning device (reticle). In one known configuration, the pellicle frame may comprise a generally rectangular body that is bonded to the boundary of the pellicle and a titanium mounting mechanism that is bonded to the sides of this body. The patterning device (reticle) is fixed to intermediate fixing members (known as studs). The intermediate fixing members (studs) on the patterning device (reticle) may engage (e.g., detachably engage) with mounting members of the pellicle frame.

[0129] [000128] One particularly promising material for use as a pellicle 19 film in EUV lithography equipment is a carbon nanotube (CNT) fabric, which can offer very high EUV transmittance (over 98%) and very good mechanical stability. However, typically, low-pressure hydrogen gas is supplied inside the lithography equipment LA, generating a hydrogen plasma in the presence of EUV radiation B (during exposure of the substrate W). It has been found that hydrogen ions and hydrogen free radicals from the hydrogen plasma can etch the pellicle 19 formed from CNTs, limiting the potential lifetime of the pellicle 19 and potentially hindering the commercial implementation of CNT pellicles.

[0130] [000129] Referring to Figures 2A to 4, some additional features of an exemplary type of lithography apparatus LA, particularly some features and components close to the support structure MT, will now be described.

[0131] [000130] The support structure MT may be movable in the scanning direction to expose a larger area of ​​the patterning device MA of the reticle-pellicle assembly 15 in a single dynamic scan exposure, as will be discussed with reference to Figures 2A and 2B. Figures 2A and 2B show schematic plan views of the support structure MT and the reticle-pellicle assembly 15 in two different positions.

[0132] [000131] The support structure MT is mounted so as to be movable within region 24. Specifically, the support structure MT is movable in the scanning direction between a first end position (shown in Figure 2A) and a second end position (shown in Figure 2B), as indicated by arrow 26.

[0133] [000132] Unless otherwise specified, the following set of Cartesian coordinates will be used throughout this specification. The scan direction is denoted as the y-direction. Similarly, the direction that lies in the plane of the support structure MT and is perpendicular to the scan direction is called the non-scan direction and is denoted as the x-direction. The direction perpendicular to the plane of the support structure MT is denoted as the z-direction.

[0134] [000133] The lithography apparatus LA may be thought to include a scan module that is operable to move the support structure MT in the scan direction between at least a first end position and a second end position. For example, the scan module may be operable to move the support structure MT in the scan direction relative to a support frame (circumstantially shown by region 24) to which the support structure MT may be thought to be movably mounted.

[0135] [000134] The reticle-pellicle assembly 15 may be thought to comprise a central portion 15a and a peripheral portion 15b surrounding the central portion 15a. The central portion 15a may be called the image-forming portion and may coincide with the portion that patterns the radiation beam B of the reticle MA and the film of the pellicle 19. The peripheral portion 15b may coincide with the boundary of the pellicle 19 and the frame of the pellicle 19.

[0136] [000135] The movement of the support structure MT between the first position and the second position defines an extended first partial region 28 of the support structure MT, which is defined by all the areas in which the central portion 15a of the reticle-pellicle assembly 15 can be positioned. In other words, the extended first partial region 28 of the support structure MT is the area defined by moving the central portion 15a of the reticle-pellicle assembly 15 from the first end position (shown in Figure 2A) to the second end position (shown in Figure 2B).

[0137] [000136] The lithography apparatus LA is provided with four reticle masking blades that define the extent of the field on the substrate W to be illuminated, as will be described below with reference to Figures 3A, 3B, and 4. The illumination system IL is operable to illuminate a certain area of ​​the patterning device MA when it is positioned on the support structure MT. This area may be called a slit of the illumination system IL and is at least partially defined by the four reticle masking blades that define a substantially rectangular area that can receive radiation from the patterning device. The extent of the substantially rectangular area in a first direction, which may be called the x-direction, is defined by a pair of x-masking blades 32, 34. The extent of the substantially rectangular area in a second direction, which may be called the y-direction, is defined by a pair of y-masking blades 36, 38.

[0138] [000137] Each of the masking blades 32, 34, 36, and 38 is positioned close to, but slightly outward from, the plane of the patterning device on the support structure MT. The x masking blades 32 and 34 are positioned on the first plane 40, and the y masking blades 36 and 38 are positioned on the second plane 42.

[0139] [000138] Each of the masking blades 32, 34, 36, and 38 defines one edge of a rectangular field area 44 on the plane of the patterning device MA, which can receive radiation. In practice, the illumination system IL may illuminate only a portion of the rectangular field area 44. As shown in Figure 4, the illumination system IL may be configured to illuminate a curved slit area 46, which may coincide with a portion of the rectangular field area 44 (depending on the positions of the masking blades 36, 38).

[0140] [000139] The curved slit region 46 may be partially defined by the optical system in the illumination system IL and / or the projection system PS. The curved slit region 46 may also be partially defined by a plurality of independent movable objects provided along one or both of the curved edges of the curved slit region 46. The plurality of independent movable objects may be called unicom fingers. The plurality of independent movable objects may be provided at different x-positions and may be movable in the y-direction to control the overlap between each movable object and the radiated beam B generated by the illumination system IL. By controlling the y-position of the movable members, the shape (or at least the intensity distribution) of one or both of the curved edges of the curved slit region 46 may be controlled. The movable members may be used to minimize changes in the amount of radiated dose provided by the radiated beam B at different positions in the non-scanning direction (i.e., the x-direction). The curved slit region 46 may also be partially defined by a physical opening, such as the entrance opening of the projection system PS.

[0141] [000140] Each of the masking blades 32, 34, 36, and 38 may be independently movable between a retracted position where it is not positioned in the path of the radiating beam and an insertion position where it at least partially blocks the radiating beam projected onto the patterning device MA by the illumination system IL. By moving the masking blades 32, 34, 36, and 38 into the path of the radiating beam, the radiating beam B can be cut off (in the x and / or y directions), and thus the area of ​​the field region 44 that receives the radiating beam B can be limited.

[0142] [000141] The x-direction corresponds to the non-scanning direction of the lithography apparatus LA, and the y-direction corresponds to the scanning direction of the lithography apparatus LA. The patterning device MA is capable of moving its field region 44 in the y-direction (as indicated here again by arrow 26) in order to expose a larger area of ​​the patterning device MA in a single dynamic scan exposure.

[0143] [000142] During dynamic exposure of the target region of the substrate W, the target region moves within the exposure region, which is the portion of the substrate W where the exposure region 44 of the patterning device MA is imaged by the projection system PS, and which lies in the plane of the substrate W. As the target region of the substrate W moves within the exposure region, the first masking blades 36, 38 move such that only the target region receives radiation (i.e., no portion of the substrate outside the target region is exposed). At the start of scan exposure, one of the y-masking blades 36, 38 is positioned in the path of the radiation beam B and functions as a shutter, so that no portion of the substrate W receives radiation. At the end of scan exposure, the other of the y-masking blades 36, 38 is positioned in the path of the radiation beam B and functions as a shutter, so that no portion of the substrate W receives radiation. During the intermediate part of the scan exposure, when there is no overlap between the exposure area 44 (which receives radiation B) and any of the adjacent target areas on the substrate W, both y-masking blades 36 and 38 are positioned in a retracted position.

[0144] [000143] The rays of radiation beam B are shown adjacent to each of the masking blades 32, 34, 36, and 38. It should be understood that each point within the slit region 46 is illuminated by radiation from a range of angles. For example, each point within the slit region 46 may receive conical radiation. The rays of radiation beam B shown adjacent to each of the masking blades 32, 34, 36, and 38 indicate the average direction of radiation received by the patterning device MA. The rays of radiation beam B shown adjacent to each of the masking blades 32, 34, 36, and 38 are sometimes called principal rays. As can be seen from Figures 3A and 3B, in this embodiment, when projected onto the xz plane, the principal rays of radiation are usually incident perpendicular to the patterning device MA, but when projected onto the yz plane, the principal rays of radiation are usually incident on the patterning device MA at an angle of 48.

[0145] [000144] The lithography apparatus LA may further include a gas nozzle 50, which may be configured to direct a gas flow 52 adjacent to the support structure MT. In particular, the gas flow 52 supplied adjacent to the support structure MT by the gas nozzle 50 may be roughly parallel to the surface of the patterning device MA and may be called a straight-across flow. The gas nozzle 50 may be positioned in approximately the same plane (first plane 40) as the x-masking blades 32, 34. The gas nozzle may be oriented in the scanning direction so that the gas flow 52 is roughly parallel to the scanning direction and flows between the x-masking blades 32, 34. The gas nozzle 50 may be considered to constitute part of a gas supply module that can operate to supply a gas flow adjacent to the support structure MT.

[0146] [000145] The gas nozzle 50 may constitute part of a hydrogen supply unit that is operable to supply hydrogen to the vicinity of the pellicle 19 of the pellicle-reticle assembly 15 when it is supported by the support structure MT.

[0147] [000146] Figure 4 shows a plan view of the y-masking blades 36, 38 in a second plane 42 viewed in the positive z direction (i.e., above Figure 3B). The positions of the x-masking blades 32, 34 and gas nozzles (displaced in the first plane 40) are indicated by dotted lines. In Figure 4, the four masking blades 32, 34, 36, and 38 are arranged to define a roughly rectangular field area 44, and the slit area 46 is located within this roughly rectangular field area 44. This may be a typical configuration of the four masking blades 32, 34, 36, and 38 during exposure of the central part of a target area (e.g., a die on a substrate W). As described above, in order to control the size of the field area 44, each of the x-masking blades 32, 34 is operable to move in the x direction, and each of the y-masking blades 36, 38 is operable to move in the y direction. The y-masking blades 36 and 38 are configured to operate from the same side of the field area 44. To achieve this, the y-masking blades 36 and 38 are shaped such that each of them has one or more support sections extending in the same direction (the negative y-direction in Figure 4), although they are substantially in the same plane 42.

[0148] [000147] The masking blades 32, 34, 36, 38 and the gas nozzle 50 may be mounted on a common masking blade assembly support (not shown). It should be understood that the masking blades 32, 34, 36, 38 may be mounted movably on such a support so that they can move relative to such a support. The gas nozzle may be mounted statically on such a support.

[0149] [000148] In some embodiments, the lithography apparatus LA may be provided with a pellicle 19 formed from CNTs.

[0150] [000149] The interaction between hydrogen ions and carbon materials is quantitatively described in two published papers, the content of which is incorporated herein by reference: (1) J. Roth, C. Garcia-Rosales, "Analytic description of the chemical erosion of graphite by hydrogen ions", Nucl. Fusion 1996, 36 / 12, 1647-1659, and (2) J. Roth, C. Garcia-Rosales, "Corrigendum - Analytic description of the chemical erosion of graphite by hydrogen ions", Nucl. Fusion 1997, 37, 897. This quantitative description of the interaction between hydrogen ions and carbon materials is sometimes referred to as the Roth-Garcia-Rosales (RGR) model. The RGR model can be used to predict the etching yield of carbon materials as a function of temperature for typical hydrogen ion energies encountered in lithography equipment, for example, where the ion energy forms 1 - 30 eV. In an EUV lithography apparatus, the typical hydrogen ion flux incident on the pellicle may be approximately 1·10 19 m -2 ·s -1 . In an EUV lithography apparatus, the typical hydrogen ion flux incident on the pellicle may be within the range of several digits of  1·10 19 m -2 ·s -1 (for example, from 10 18 m -2 ·s -1 to 10 20 m -2 ·s -1 ).

[0151] [000150] Figure 5 shows 1.5·10 19 m -2 ·s -1The expected etching rate of carbon hydrogen etching for a given hydrogen ion flux is shown as a function of temperature. Figure 5 also shows the sp3 carbon concentration as a function of temperature. From Figure 5, it can be seen that under these typical ambient conditions in a lithography apparatus LA, for a pellicle formed purely from CNTs, the hydrogen etching rate of the pellicle is expected to drop to a negligible level at a temperature of approximately 1050 K. However, those skilled in the art will understand that different minimum temperatures may be desirable under different conditions.

[0152] [000151] In some embodiments, the minimum temperature is such that, above which the hydrogen etching rate of the pellicle 19 drops to a negligible level. In some embodiments, the minimum temperature may be 1000K or higher. As described above, this may be beneficial for pellicles formed purely from CNTs, where the hydrogen ion flux incident on the pellicle is approximately 1.10 19 m -2 ·s -1 In some cases, the hydrogen ion energy is approximately 1 to 30 eV. More preferably, the minimum temperature may be 1050 K or higher. In some embodiments, the minimum temperature may be 1100 K or higher.

[0153] [000152] The negligible reduction in the hydrogen etch rate at high temperatures can be governed by the conversion of sp3 carbon to sp2 carbon at a given temperature (see Figure 5). Furthermore, a similar process occurs when forming sp2 carbon structures such as graphene and CNTs, where the temperature of the carbon rises and the carbon is converted to sp2 carbon, resulting in the formation of the sp2 carbon structure. Such processes for growing graphene include, for example, chemical vapor deposition (CVD) and plasma-excited chemical vapor deposition (PE-CVD). Furthermore, it is known that the growth of graphene from an sp3 carbon source can be initiated at a low temperature of 300°C (573K) in the presence of a single-atom catalyst. In other words, the conversion of sp3 carbon to sp2 carbon may be initiated at this temperature in the presence of a single-atom catalyst. Lowering the etch-free operating temperature range of the pellicle 19 is beneficial in reducing the thermal load on the environment of the pellicle 19. It also means that the heating system 20 needs to supply less heat to the pellicle 19, which can make it easier for the system to supply this heat.

[0154] [000153] When the pellicle 19 is heated to a temperature above a threshold level (the level at which hydrogen etching becomes negligible), it has been found that even after the heating is stopped, there is a time delay before the etching rate rises above a negligible level. After a period of heating to a temperature at which hydrogen etching becomes negligible, when the heating is stopped, the hydrogen etching rate changes over time as qualitatively shown in Figure 6.

[0155] [000154] When heated to a sufficient temperature, hydrogen is thought to be released from the pellicle 19, and the hydrogen etching rate is thought to decrease to a negligible level. Furthermore, the existence of a time delay Δt in the increase in etching rate after deheating is thought to be because it takes a non-zero amount of time for hydrogen to be replenished on the surface of the pellicle 19 after heating. This hydrogen replenishment rate may be proportional to the hydrogen radical flux to the pellicle 19 film in the lithography apparatus LA. As the time after deheating increases, the etching rate eventually rises to the standard value for pellicle 19 at room temperature.

[0156] [000155] Some embodiments of the present disclosure relate to a novel lithography method 100, as schematically shown in Figure 7. Figure 8 is a schematic plan view of a reticle-pellicle assembly 15 that may be used in the lithography method 100. The novel lithography method 100 is now considered with reference to Figures 7 and 8. The novel lithography method 100 may be performed using a lithography apparatus LA of the type described above with reference to Figures 1 to 4, and it should be understood that the features of the above lithography apparatus LA related to the novel lithography method 100 are given the same reference numerals as used in the description of Figures 1 to 4 above.

[0157] [000156] The lithography method 100 includes a step 102 of forming multiple images of the reticle on a substrate. Each imaging process includes illuminating a first portion 60 of the reticle-pellicle assembly 15 with a radiation beam B, and focusing the radiation scattered by the reticle MA and projecting it onto a target area of ​​the substrate W using a projection optical system PS.

[0158] [000157] The lithography method 100 further includes step 104 of periodically illuminating a second portion 62 of the reticle-pellicle assembly 15 with a radiation beam B. The second portion 62 of the reticle-pellicle assembly 15 at least partially surrounds the first portion 60. As shown in Figure 8, in at least some embodiments, the second portion 62 of the reticle-pellicle assembly 15 substantially surrounds the first portion 60.

[0159] [000158] The first portion 60 of the reticle-pellicle assembly 15 may correspond to the central portion 15a shown in Figures 2A and 2B and described above. Similarly, the second portion 62 may correspond to at least a portion of the peripheral portion 15b shown in Figures 2A and 2B and described above. As shown in Figure 8, in at least some embodiments, the reticle-pellicle assembly 15 may further comprise a third portion 64 surrounding the second portion 62. In such embodiments, the peripheral portion 15b shown in Figures 2A and 2B and described above may be equivalent to a combination of the second and third portions 62, 64. The third portion 64 may, for example, coincide with the boundary and frame of the pellicle 19.

[0160] [000159] The lithography method 100 schematically shown in Figure 7 is advantageous, as will be discussed below.

[0161] [000160] As described above, if there is dirt on the reticle MA, the image formed on the substrate W will generally change, resulting in printing errors. To avoid particle contamination of the reticle MA, it is known to protect the reticle MA using a thin film known as a pellicle 19. The pellicle 19 is placed in front of the reticle MA to prevent particles from adhering to the reticle MA. The pellicle 19 is placed so as not to be sharply imaged on the substrate W (e.g., a resist-coated wafer), and therefore particles on the pellicle 19 are less likely to interfere with the imaging process than particles on the reticle MA. One particularly promising material used as a pellicle film in EUV lithography equipment is a carbon nanotube (CNT) fabric, which can provide very high EUV transmittance (over 98%) and very good mechanical stability. However, typically, low-pressure hydrogen gas is supplied inside the lithography equipment LA, creating a hydrogen plasma in the presence of EUV radiation (during exposure). It has been found that hydrogen ions and hydrogen free radicals from hydrogen plasma can etch the pellicle 19 formed from CNTs, potentially limiting the potential lifetime of the pellicle 19 and hindering the commercial implementation of CNT pellicles.

[0162] [000161] It is known that the etching of carbon by hydrogen ions and free radicals is temperature-dependent. Specifically, (a) the carbon etching rate is not zero at low temperatures, and (b) the carbon etching rate decreases to a negligible level at a threshold temperature beyond which carbon etching remains at a negligible level. It is also known that when the pellicle 19 is heated to a temperature higher than the threshold level (the level at which hydrogen etching becomes negligible), there is a time delay before the etching rate rises from a negligible level even after the heating is stopped.

[0163] [000162] The first portion 60 of the reticle-pellicle assembly 15 is the portion illuminated by (EUV) radiation B to form an image of the reticle MA on the substrate W. Thus, the first portion 60 of the reticle-pellicle assembly 15 may include the image-forming portion of the reticle MA and the corresponding portion of the pellicle 19. The first portion 60 of the reticle-pellicle assembly 15 is exposed to EUV radiation B during each image-forming process 102. This causes the first portion 60 of the reticle-pellicle assembly 15 to be heated (in the case of the lithography scanner LA, each portion of the first portion 60 of the reticle-pellicle assembly 15 is heated periodically at a rate given by the rate at which the image is formed, i.e., once per die). As will be understood by those skilled in the art, within the lithography apparatus LA, a hydrogen plasma is formed by the EUV radiation B (used for exposure of the substrate W). Therefore, the hydrogen plasma is formed near the first portion 60 of the reticle-pellicle assembly 15, which is exposed to EUV radiation and heated by EUV radiation B. Furthermore, it should be understood that this plasma can extend to peripheral areas that are not directly heated by EUV radiation B. As a result, the inventors have found that the pellicle 19 is prone to damage in the region 62 surrounding the central portion 60 (corresponding to the image-forming portion).

[0164] [000163] Figure 9 shows a graph of the EUV transmittance of the CNT pellicle as a function of the non-scan position (x position). The graph in Figure 9 shows the change in the resist height on the wafer exposed to EUV radiation through the pellicle as a function of the non-scan position (x position). The change in the resist height on the wafer is proportional to the change in the EUV transmittance of the pellicle. The larger the negative change in resist height, the greater the increase in EUV transmittance. Figure 9 also shows the positions of the x masking blades 32 and 34 (see Figures 3A and 3B). In the graph in Figure 9, the portion between the two lines corresponding to the positions of the x masking blades 32 and 34 is the first portion 60 of the reticle-pellicle assembly 15, which corresponds to the image-forming portion of the reticle MA. It can be seen that there is a sharp increase in the EUV transmittance of the pellicle in the region just outside the two lines corresponding to the positions of the x masking blades 32 and 34. This corresponds to a region that is not directly heated by the EUV radiation beam B, but in which hydrogen ions and free radicals from the plasma can freely diffuse. This region may have dimensions of approximately 50 μm or 100 μm and is adjacent to the first portion 60 of the reticle-pellicle assembly 15 and corresponds to the second portion 62 of the reticle-pellicle assembly 15.

[0165] [000164] Advantageously, by periodically illuminating the second portion 62 of the reticle-pellicle assembly 15 with the radiation beam B, hydrogen etching of the second portion 62 (which at least partially surrounds the first portion 60) of the reticle-pellicle assembly 15 can be suppressed.

[0166] [000165] The lithography method 100 shown in Figure 7 includes both (a) a step 102 of forming multiple images of the reticle on a substrate and (b) a step 104 of periodically illuminating a second portion 62 of the reticle-pellicle assembly 15 with a radiation beam B. These steps may be performed in any order, as described below with reference to Figures 10 to 15.

[0167] [000166] In some embodiments, illumination 104 of the second portion 62 of the reticle-pellicle assembly 15 with the radiant beam B may occur between the exposure 102 of two target regions of the substrate W (i.e., between two image-forming processes using the radiant beam B with the first portion 60 of the reticle-pellicle assembly 15). For example, illumination 104 of the second portion 62 of the reticle-pellicle assembly 15 with the radiant beam B may occur between the exposure of different target regions (or dies) of a single substrate W, or between the exposure of different substrates W. Examples of such configurations are discussed below with reference to Figures 10, 11A, and 11B.

[0168] [000167] Alternatively, in some embodiments, illumination 104 of the second portion 62 of the reticle-pellicle assembly 15 with the radiation beam B may occur during the exposure of a target region of the substrate W, or as part of the exposure of a target region of the substrate W (i.e., as part of the image formation process with the radiation beam B using the first portion 60 of the reticle-pellicle assembly 15). Examples of such configurations are discussed below with reference to Figures 12 to 15.

[0169] [000168] In some embodiments, the entire second portion 62 of the reticle-pellicle assembly 15 may be illuminated simultaneously with the radiation beam B. Examples of such configurations are discussed below with reference to Figures 10, 11A, and 11B.

[0170] [000169] Alternatively, in some embodiments, the second portion 62 of the reticle-pellicle assembly 15 may be illuminated with radiation beam B over several different exposures, each exposing a different portion of the second portion 62 of the reticle-pellicle assembly 15 to radiation B. Examples of such configurations are discussed below with reference to Figures 12 to 15.

[0171] [000170] In some embodiments, step 104 of periodically illuminating the second portion 62 of the reticle-pellicle assembly 15 with the radiation beam B is achieved by periodically illuminating an expanded exposure field, as will be discussed with reference to Figures 10 and 11.

[0172] [000171] The exposure field is the area of ​​the reticle-pellicle assembly 15 that is exposed to radiation. It should be understood that the range of the exposure field in the non-scan direction (x direction) can be defined by the range of the radiation beam B in the non-scan direction (which can be defined by a pair of masking blades 32, 34). It should be understood that the range of the exposure field in the scan direction (y direction) can be defined by both the range of the radiation beam in the scan direction (which can be defined by a pair of masking blades 36, 38) and the range of the scan operation.

[0173] [000172] Illumination of such an enlarged field may be part of the exposure of a target area of ​​the substrate W (i.e., part of the image formation process 102).

[0174] [000173] Alternatively, as will be described below with reference to Figures 10 and 11, illumination of the magnified field may occur between the exposure of two target regions of the substrate W (i.e., between two image formation processes). For example, illumination of the magnified field may occur between the exposure of different target regions (or dies) of a single substrate W, or between the exposure of different substrates W.

[0175] [000174] Figure 10 shows a flowchart of a first embodiment 100a of method 100 shown in Figure 7. When the process starts, multiple (n) images are formed on a target region (e.g., die) of the substrate W (e.g., resist-coated wafer). After each image is formed on the target region, if n images have not yet been formed, another image is formed. After each image is formed on the target region, if n images have been formed, an expanded exposure field is formed. It should be understood that the exposure of the expanded field is achieved by appropriate control of the masking blades 32, 34, 36, 38. For example, the masking blades 32, 34, 36, 38 may be positioned in nominal positions while each image is being formed on the target region of the substrate W, but during the exposure of the expanded field, the masking blades 32, 34, 36, 38 may be positioned in different positions.

[0176] [000175] When the magnified field is exposed to the EUV radiation beam B, the image counter may be reset, and exposure of another n images is formed on the target region (e.g., die) of the substrate W (e.g., resist-coated wafer). The process, which is followed by one magnified exposure of the reticle-pellicle assembly 15 after n images have been formed on the target region of the substrate W, may be repeated, for example, m times.

[0177] [000176] Figures 11A and 11B are schematic diagrams comparing method 100a shown in Figure 10 with a standard lithography process.

[0178] [000177] Figure 11A shows a standard lithography method in which a standard exposure field 70 is used n × m times to form an image on a target area of ​​the substrate. The first portion 60 of the reticle-pellicle assembly 15 is exposed to EUV radiation and is therefore periodically heated to a temperature sufficient to minimize hydrogen etching of the first portion 60. The hydrogen plasma formed by the EUV radiation in the vicinity of the first portion 60 of the reticle-pellicle assembly 15 will also diffuse into the region adjacent to the second portion 62 surrounding the first portion 60 of the reticle-pellicle assembly 15. Since the second portion 62 of the reticle-pellicle assembly 15 is not directly heated by the EUV radiation B, this second portion 62 of the reticle-pellicle assembly 15 will undergo significant hydrogen etching, and the pellicle will be prone to damage in this second portion 62.

[0179] [000178] Figure 11B shows the lithography method 100a shown in Figure 10, in which a standard exposure field 70 is used n times to form an image on a target region of the substrate W, followed by one exposure using an enlarged exposure field 72. This n+1 exposure process is repeated m times. The first portion 60 of the reticle-pellicle assembly 15 is exposed to EUV radiation and is therefore periodically heated to a temperature sufficient to minimize hydrogen etching of the first portion 60. During the n exposures using the standard exposure field, the hydrogen plasma formed by the EUV radiation near the first portion 60 of the reticle-pellicle assembly 15 also diffuses to the region adjacent to the second portion 62 surrounding the first portion 60 of the reticle-pellicle assembly 15. However, during exposure using the enlarged exposure field, the second portion 62 of the reticle-pellicle assembly 15 is directly heated by the EUV radiation B, so this second portion 62 of the reticle-pellicle assembly 15 is significantly less susceptible to hydrogen etching. In fact, hydrogen etching of the second portion 62 of the reticle-pellicle assembly 15 may be minimal if the interval between two consecutive illuminations of the second portion 62 of the reticle-pellicle assembly 15 with the radiant beam B using the expanded exposure field 72 is short enough that the surface of the pellicle does not become saturated with hydrogen after heating by the first illumination. Here again, it should be understood that the time required for the surface of the pellicle to become saturated with hydrogen after heating by the first illumination using the expanded field 72 will depend on the conditions in the vicinity of the pellicle. In some embodiments, the interval between two consecutive illuminations of the second portion 62 of the reticle-pellicle assembly may be approximately 100 ms or less.

[0180] [000179] During exposure using the expanded exposure field 72, the hydrogen plasma formed by EUV radiation B near the first and second portions 60 and 62 of the reticle-pellicle assembly 15 also diffuses to the region adjacent to the third portion 66 of the reticle-pellicle assembly 15 that surrounds the second portion 62. Since the third portion 66 of the reticle-pellicle assembly 15 is not directly heated by EUV radiation B, this third portion 66 of the reticle-pellicle assembly 15 undergoes significant hydrogen etching, and the pellicle may be prone to damage in this third portion 66. However, the third portion 66 of the reticle-pellicle assembly 15 is exposed to this plasma for a time of l / (n+l). This is in contrast to standard lithography methods in which the second portion 62 of the reticle-pellicle assembly 15 is exposed to the plasma for almost the entire time. Therefore, the amount of etching in the region experiencing maximum etching is reduced, and correspondingly the lifetime of the pellicle is extended by (n+1 times).

[0181] [000180] When the enlarged exposure field 72 is periodically illuminated with radiation B, radiation scattered from the reticle-pellicle assembly 15 may not be projected onto the substrate W. Such exposure is sometimes called dummy exposure.

[0182] [000181] Such dummy exposure may result in minimal adaptation of standard lithography methods. However, such dummy exposure also results in a decrease in the productivity or throughput of the lithography apparatus LA. In some embodiments, additional dummy exposure may be performed approximately once per wafer (approximately 100 full-field dies). This means that the throughput drop at the dummy exposure site is only about 1%. In some embodiments, dummy exposure may be performed approximately every 10 dies, resulting in a throughput drop of about 10% for dummy exposure.

[0183] [000182] In some embodiments, the substrate W may be moved so that radiation scattered from the reticle-pellicle assembly 15 does not enter the substrate W. Dummy exposure may simply be selected outside the wafer W region and exposed after a row of target regions on the wafer W. Such exposure has already been used in some lithography methods to ensure that the edge die is exposed to the same stray light as the die in the center of the wafer W. Alternatively, in some embodiments, the shutter may be closed to prevent radiation scattered from the reticle-pellicle assembly 15 from entering the substrate W.

[0184] [000183] In some embodiments of the embodiment 100a shown in Figures 10, 11A and 11B, illumination of such an enlarged field 72 may be part of the exposure of a target area of ​​the substrate W (i.e., part of the image formation process 102). Advantageously, this means that exposure of the enlarged field 72 does not adversely affect the productivity of the lithography apparatus LA. Such embodiments may be achieved by making some changes to the field distribution on the reticle and / or wafer W (as will be further discussed below with reference to Figures 14 and 15).

[0185] [000184] In some embodiments of method 100 shown in Figure 7, step 104 of periodically illuminating the second portion 62 of the reticle-pellicle assembly 15 with a radiation beam is achieved by changing the exposure field. It should be understood that in general, the range and / or position of the exposure field may be changed. Embodiment 100a described above with reference to Figures 10 to 11B is an example of such an embodiment of changing the exposure field. Further embodiments of such a method of changing the exposure field will now be described with reference to Figures 12 to 15.

[0186] [000185] Figure 12 shows a flowchart of a second embodiment 100b of method 100 shown in Figure 7. Once the process is started, multiple images are formed on a target region (e.g., die) of the substrate W (e.g., resist-coated wafer). After each image is formed on the target region, the exposure field (range and / or position) is changed. It should be understood that changing the exposure field is achieved by appropriate control of the masking blades 32, 34, 36, and 38.

[0187] [000186] For example, while forming a first image on the target region of the substrate W, the masking blades 32, 34, 36, and 38 may be positioned in a first position, whereas while forming a second image on the target region of the substrate W, the masking blades 32, 34, 36, and 38 may be positioned in a second position. Generally, the position of at least one edge of the exposure field (defined by one of the masking blades 32, 34, and 36) in at least some image forming processes is offset by a certain amount from the position of at least one edge of the exposure field in the previous image forming process.

[0188] [000187] For example, the offset may be approximately 50 μm. At least one edge of the exposure field may be stepped by such an offset for every n exposure processes (e.g., per exposure process). In some embodiments, all edges of the exposure field may be stepped by such an offset (by stepping each of the masking blades 32, 34, 36, and 38 by such an offset). Method 100b may use approximately five different positions for each edge of the exposure field, and the position of each edge of the exposure field may be stepped or cycled through all (e.g., five) different positions.

[0189] [000188] Figure 13 shows a graph of the EUV transmittance of the CNT pellicle as a function of the non-scanned position (x position) for (a) a standard lithography method (solid line) and (b) an embodiment 100b of a new method in which masking blades 32 and 34 are each moved in 10 steps of 2 mm (dashed line). The graph shown in Figure 13 is the change in the resist height on the wafer exposed to EUV radiation through the pellicle, depending on the non-scanned position (x position) at the reticle level. The change in resist height on the wafer is proportional to the change in the EUV transmittance of the pellicle. The larger the negative change in resist height, the greater the increase in EUV transmittance. The approximate positions of the x masking blades 32 and 34 are also shown in Figure 13 (see Figures 3A and 3B). A comparison of the curves of the standard lithography method and the novel method embodiment 100b shows that, advantageously, the sharp peak in the EUV transmittance of the pellicle in the region immediately outside the x-masking blades 32 and 34 is no longer present with step movement of the masking blades 32 and 34.

[0190] [000189] In alternative embodiments, the exposure field for multiple image-forming processes may be continuously changing. For example, the position of at least one edge of the exposure field (defined by the masking blades 32, 34, 36, 38) may be continuously changing. For example, the position of at least one edge of the exposure field (defined by the masking blades 32, 34, 36, 38) may oscillate over a range of positions around a nominal position. The amplitude of such oscillation may be approximately 100 μm. In some embodiments, all edges of the exposure field may be continuously changing (by causing the positions of all masking blades 32, 34, 36, 38 to oscillate).

[0191] [000190] Embodiment 100b shown in Figure 12 includes changing the exposure field after an image formation process, but alternative embodiments may change the exposure field after a different number of image formation processes. Generally, the exposure field for at least some of the image formation processes may differ from the exposure field for the previous image formation process.

[0192] [000191] In some embodiments, in order to form an image on each target region of the substrate W adjacent to the edge of the substrate W, at least one of the masking blades 32, 34, 36, 38 corresponding to the edge adjacent to the edge of the substrate W in the exposure field may be positioned to expand the exposure field, as will be described below with reference to Figures 14 and 15. As described above, generally, four masking blades 32, 34, 36, 38 may be used during exposure of each target region of the substrate W to define the exposure field.

[0193] [000192] Figure 14 shows a flowchart of a third embodiment 100c of method 100 shown in Figure 7. Figure 15 is a schematic plan view of a (generally circular) substrate W containing a plurality of (generally rectangular) target regions C or dies. In the embodiment shown in Figure 15, the substrate W contains 110 target regions C. Target regions C adjacent to the edges of the substrate W are sometimes called edge target regions or edge dies. It should be understood that such edge target regions C do not have adjacent target regions C on all sides. Rather, each edge target region C does not have adjacent neighboring target regions C on at least one side (adjacent to the edge of the substrate W). For example, the top left target region C (number 110) has no adjacent target regions in the positive y direction or the negative x direction. For such edge target regions C (or dies) on the substrate W, masking blades 32, 34, 36, and 38 may be positioned to expand the exposure area, as described below.

[0194] [000193] When the third embodiment 100c of Method 100 is initiated, multiple images are formed on a target region (e.g., die) of the substrate W (e.g., a resist-coated wafer). If the next target region to be exposed is not an edge target region, a nominal exposure region (e.g., with masking blades 32, 34, 36, 38 in their nominal positions) may be used. If the next target region to be exposed is an edge target region, an expanded exposure region (e.g., with at least one of the masking blades 32, 34, 36, 38 in an open position) may be used. It should be understood that varying the exposure field is achieved by appropriate control of the masking blades 32, 34, 36, 38.

[0195] [000194] For example, for such edge target regions C (or dies) on the substrate W, the masking blades 32, 34, 36, and 38 may be shifted by 1 mm or more from their nominal positions to expand the exposure area. Advantageously, this illuminates the portion of the reticle-pellicle assembly 15 adjacent to the first portion 60 of the reticle-pellicle assembly 15 (and corresponding to a portion of the second portion 62 of the reticle-pellicle assembly 15) with the radiation beam B. When the masking blades 32, 34, 36, and 38 are controlled in this manner for all such edge dies C, the portion 62 of the reticle-pellicle assembly 15 substantially surrounding the first portion 60 of the reticle-pellicle assembly 15 can be illuminated with radiation B.

[0196] [000195] Forming multiple images of the reticle MA on the substrate may include forming images of the reticle MA on multiple target regions C of the substrate W. Each of the multiple target regions C may be roughly rectangular. The multiple target regions C may be arranged as a two-dimensional array.

[0197] [000196] In some embodiments, the two-dimensional array of target regions C may be exposed using a standard meandering scan pattern in which each column of target regions C (extending in the non-scanning direction) is exposed sequentially. Such a standard meandering scan pattern is shown in Figure 15, where the exposure order of target regions C is indicated by the numbers on each target region. The scan direction of exposure for each target region C is indicated by a solid arrow, and the movement of the substrate W between exposures of two consecutive target regions C is indicated by a dashed line.

[0198] [000197] One target region C in each column has no adjacent target regions on one side, and another target region has no adjacent target regions on the other side. For example, in the second column from the top, target region 99 has no adjacent target regions to the left (negative x-direction), and target region 106 has no adjacent target regions to the right (negative y-direction). Thus, in such a configuration, a portion of the reticle-pellicle assembly 15 that is adjacent to the first portion 60 of the reticle-pellicle assembly 15 but is offset in the non-scanning direction (x-direction) can be exposed to radiation during the exposure of each column.

[0199] [000198] In contrast, during exposure of the first half of the substrate W, there are several target regions that do not have adjacent target regions C on the first side in the scanning direction, but there are no target regions that do not have adjacent target regions C on the other (second) side in the scanning direction. For example, during exposure of the first half of the substrate W (the lower half of the substrate W in Figure 15), there are several target regions C that do not have adjacent target regions downward (negative y direction), but there are no target regions that do not have adjacent target regions upward (positive y direction). Similarly, during exposure of the first half of the substrate, there are several target regions that do not have adjacent target regions on the second side in the scanning direction, but there are no target regions that do not have adjacent target regions on the first side in the scanning direction. For example, during exposure of the second half of the substrate W (the upper half of the substrate W in Figure 15), there are several target regions C that do not have adjacent target regions upward (positive y direction), but there are no target regions that do not have adjacent target regions downward (negative y direction).

[0200] [000199] In some embodiments, in order to increase the frequency of target regions that do not have an adjacent target region on the first or second side in the scanning direction (i.e., the upper or lower side in Figure 15), the two-dimensional array of target regions C may be exposed using an exposure pattern in which multiple rows of target regions C (extending in the non-scanning direction, i.e., the x-direction) are exposed in a different order. In some embodiments, forming an image of the reticle MA multiple times on the substrate W may include forming an image of the reticle MA on multiple target regions C of the substrate W arranged as a two-dimensional array, where the two-dimensional array of target regions C is exposed one row at a time, and the rows are not exposed in order.

[0201] [000200] In some embodiments of the method 100 shown in Figure 7, during each image forming process, at least one masking blade 32, 34, 36, 38 may be used to mask adjacent target regions C of the substrate W from the radiation beam B. Preferably, four masking blades 32, 34, 36, 38 may be used to define the exposure area and mask the target regions C adjacent to all four sides of the exposure area C. The exposure field C may be defined by the exposure area, the scan length, and the positions of the four masking blades 32, 34, 36, 38.

[0202] [000201] In some embodiments of the method 100 shown in Figure 7, at least one reticle masking blade 32, 34, 36, 38 may be operated so that the outer edge of the exposure area extends into an expanded area. For example, the outer edge of the exposure area may extend into an area having dimensions of approximately 100 μm.

[0203] [000202] In some embodiments of the method 100 shown in Figure 7, each image-forming process may include scanning exposure, in which the reticle-pellicle assembly 15 is moved in the scanning direction (e.g., the y-direction) relative to the radiation beam B.

[0204] [000203] Generally, in the embodiment of Method 100 shown in Figure 7, the duration of periodic illumination of the second portion 62 of the reticle-pellicle assembly 15 by the radiant beam B may be long enough to heat the second portion 62 of the pellicle to a desired temperature (e.g., to a temperature higher than the threshold temperature at which hydrogen etching of the pellicle can be ignored). In some embodiments, the desired temperature may be above 900K. It should be understood that the time required to heat the pellicle to the desired temperature will depend on the output of the radiant beam B while the pellicle is being heated.

[0205] [000204] In some embodiments of the method 100 shown in Figure 7, periodically illuminating the second portion 62 of the reticle-pellicle assembly 15 with radiation beam B may include exposing the second portion 62 to EUV radiation to heat the pellicle to a temperature at which the hydrogen etching rate of the pellicle is negligible. For example, periodically illuminating the second portion 62 of the reticle-pellicle assembly 15 with radiation beam B may include exposing the second portion to EUV radiation to heat the pellicle to a temperature above 800K, for example above 900K.

[0206] [000205] Generally, the time between two consecutive illuminations of the second portion 62 of the reticle-pellicle assembly 15 with the radiation beam B may be short enough so that the surface of the pellicle does not become saturated with hydrogen after heating by the first illumination. Again, it should be understood that the time required for the surface of the pellicle to become saturated with hydrogen after heating by the first illumination will depend on the conditions in the vicinity of the pellicle. In some embodiments, the time between two consecutive illuminations of the second portion of the reticle-pellicle assembly may be approximately 100 ms.

[0207] [000206] In some embodiments of the method 100 shown in Figure 7, step 104 of periodically illuminating the second portion 62 of the reticle-pellicle assembly 15 with the radiation beam B is such that the second portion 62 of the reticle-pellicle assembly 15 is illuminated once per substrate W.

[0208] [000207] In some embodiments of the method 100 shown in Figure 7, step 104 of periodically illuminating the second portion 62 of the reticle-pellicle assembly 15 with the radiation beam B is such that the second portion 62 of the reticle-pellicle assembly 15 is illuminated once for each row of target region C on the substrate W.

[0209] [000208] As described above, embodiments of the present disclosure propose using the masking blades 32, 34, 36, and 38 in novel operating modes. In some embodiments (particularly when exposing an enlarged exposure field as part of image formation onto a target region of the substrate W), this new functionality of the masking blades 32, 34, 36, and 38 may be combined with some modification of the reticle layout and / or pellicle boundary, as will be considered below.

[0210] [000209] Typically, the reticle comprises a central image-forming area surrounded by a black-bordered region. The black-bordered region may have an EUV radiant reflectance in the range of 0.1% to 5%, for example, less than 1%. The black-bordered region may have dimensions of approximately 1 to 5 mm, for example, approximately 2 to 3 mm. The reticle may have one or more alignment markers around the black-bordered region.

[0211] [000210] In embodiments in which an enlarged exposure field is exposed as part of image formation on a target region of the substrate W, the enlarged field may adversely affect critical dimensional uniformity (CDU) due to increased flare, particularly at the corners of the target region. This effect will depend on the effectiveness of the black frame of the reticle and the field layout on the wafer used (e.g., how close two adjacent target regions C are to each other).

[0212] [000211] When magnified exposure is used to restore the pellicle, the usable image area may be reduced. Since the magnified exposure field is not used for all exposure (of the target region C of the substrate W), the additional area (relative to the nominal exposure field) cannot contain imaging information. In some embodiments, an enlarged black frame may be provided on the reticle to mitigate the degradation of imaging performance caused by the magnified exposure field.

[0213] [000212] For example, in some embodiments, the operation of the new masking blades 32, 34, 36, and 38 may involve the periodic use of an expanded exposure field, in which case each of the masking blades 32, 34, 36, and 38 moves outward by a distance of approximately 800 μm with respect to a single die / target region C. As described above with reference to Figures 10, 11A, and 11B, this is done so that a second portion 62 of the reticle-pellicle assembly 15 is illuminated by EUV light, preventing the hydrogen etching of this second portion 62 from beginning. The frequency of this expanded exposure field may be approximately 1 / 50 of the die / target region C, which results in a 50-fold extension of the pellicle life.

[0214] [000213] However, in some existing reticle layouts, the black frame of the reticle is wide enough to allow the masking blades 32, 34, 36, and 38 to move freely up to this distance without causing imaging artifacts at the edges or corners of the target region C.

[0215] [000214] One way to achieve an enlarged black frame may be to reduce the range of the usable image-forming area. For example, the imaging field may be reduced by moving all edges of the reticle's image-forming region inward by approximately 800 μm (in both the x and y directions).

[0216] [000215] Another way to achieve an enlarged black frame may be to move the position of the alignment marker on the reticle. The alignment marker is usually placed in a so-called quiet zone. The quiet zone is the area around the alignment marker where no other radiation scattering or reflection mechanisms are present that could interfere with the signal from the alignment marker. In particular, the absence of other radiation scattering or reflection mechanisms in the quiet zone is to (a) avoid cross-terms to the alignment marker signal and (b) avoid radiation leakage from surrounding absorber materials (the alignment marker may be significantly smaller than the detection area of ​​the detector used for alignment measurements, so that these measurements are also very sensitive to stray radiation that hits the absorption area of ​​the detector). In some embodiments, to achieve an enlarged black frame, the alignment marker may be moved from the quiet zone to the scribe line (the area corresponding to the gap between adjacent target regions C on the wafer W), and the black frame may be enlarged into the quiet zone. Alternatively, in some embodiments, the dimensions of the pellicle boundary and frame may be reduced by, for example, 1 mm, the dimensions of the black frame may be increased by 1 mm, and the alignment marker may be moved 1 mm outward. In such embodiments, the alignment marker may end up on a lower-quality portion of the reticle. However, this is not expected to cause any significant problems.

[0217] [000216] If the reduction in the usable image area is unacceptable or undesirable, an alternative may be to overlap the expanded exposure field with the pellicle boundary. Normally, exposure of the pellicle boundary is avoided because all EUV light is absorbed and the boundary becomes hot, but the thermal load from periodic use of an expanded exposure field at the pellicle boundary may be acceptable.

[0218] [000217] Some embodiments of the present disclosure relate to a lithography apparatus LA of the type shown in Figure 1. The lithography apparatus LA may have the features described above with reference to Figures 1 to 4. Specifically, a new lithography apparatus LA according to an embodiment of the present disclosure includes a controller CN (see Figure 1) which is operable to control an illumination system IL, a support structure MT, a substrate table WT, and a projection system PS to perform an image-forming process which includes (a) forming an image of a reticle MA supported by the support structure MT multiple times on a substrate W, each time including illuminating a first portion 60 of a reticle-pellicle assembly 15 with a radiation beam B and projecting the radiation scattered by the reticle MA onto a target region C of the substrate W using a projection optical system PS, and (b) periodically illuminating a second portion 62 of a reticle-pellicle assembly 15, at least partially surrounding the first portion 60, with the radiation beam B.

[0219] [000218] Such a lithography apparatus LA is advantageous for enabling the implementation of the new lithography methods 100, 100a, 100b, and 100c discussed above.

[0220] [000219] As discussed above, the pellicle 19 placed in front of the reticle MA can prevent particle adhesion to the reticle MA, thereby improving optical performance (by reducing printing errors). One particularly promising material used as a pellicle film in EUV lithography equipment is a carbon nanotube (CNT) fabric, but CNT pellicles are susceptible to hydrogen etching. It is known that carbon etching by hydrogen ions and free radicals decreases to a negligible level at a threshold temperature beyond which carbon etching remains negligible. It is also known that when the pellicle 19 is heated to a temperature above the threshold level (where hydrogen etching becomes negligible), there is a time delay before the etching rate rises above a negligible level even after the heating is removed.

[0221] [000220] The first portion 60 of the reticle-pellicle assembly 15 is the portion illuminated by (EUV) radiation to form an image of the reticle MA on the substrate W. Thus, the first portion 60 of the reticle-pellicle assembly 15 may include the image-forming portion of the reticle MA and the corresponding portion of the pellicle 19. The first portion 60 of the reticle-pellicle assembly 15 is exposed to EUV radiation during each image-forming process. This causes the first portion 60 of the reticle-pellicle assembly 15 to be heated (in the case of the lithography scanner LA, each portion of the first portion 60 of the reticle-pellicle assembly 15 is heated periodically at a rate given by the rate at which the image is formed, i.e., once per die). As will be understood by those skilled in the art, within the lithography apparatus LA, a hydrogen plasma is formed by the EUV radiation (used for exposure of the substrate W). Therefore, the hydrogen plasma is formed near the first portion 60 of the reticle-pellicle assembly 15, which is exposed to and heated by EUV radiation. Furthermore, it should be understood that this plasma can extend to peripheral areas that are not directly heated by EUV radiation. As a result, the inventors have found that the pellicle is prone to damage in the region surrounding the central part (corresponding to the image-forming area).

[0222] [000221] Advantageously, by periodically illuminating the second portion 62 of the reticle-pellicle assembly 15 with the radiation beam B, hydrogen etching of the second portion 62 (which at least partially surrounds the first portion 60) of the reticle-pellicle assembly 15 can be suppressed.

[0223] [000222] The controller CN may be capable of performing the novel lithography methods 100, 100a, 100b, and 100c discussed above.

[0224] [000223] The lithography apparatus LA may further include a scanning mechanism that can be operated to move the support structure MT in the scanning direction (y-direction) relative to the radiant beam B regulated by the illumination system IL. The scanning mechanism may further be operated to move the substrate table WT relative to the projection system PS such that the image of the reticle MA formed by the projection system PS is substantially stationary relative to the substrate W. This may be described as synchronous movement of the support structure MT and the substrate table WT. The movement (direction and velocity) of the substrate table WT relative to the support structure MT will generally depend on the image inversion and magnification characteristics of the projection system PS.

[0225] [000224] The controller CN may be capable of controlling the scanning mechanism.

[0226] [000225] As described above, the lithography apparatus LA may include a first pair of masking blades 36, 38 configured to define a range of the exposure area in a first direction (y direction), and a second pair of masking blades 32, 34 configured to define a range of the exposure area in a second direction (x direction).

[0227] [000226] The first and second pairs of masking blades 36, 38, 32, 34 may be movable to change the extent of the exposure area. The controller CN may be operable to control the respective positions of the first and second pairs of masking blades 36, 38, 32, 34. When in use, the two pairs of masking blades 36, 38, 32, 34 may be used to define the exposure area and mask the target area C adjacent to all four sides of the exposure area.

[0228] [000227] In some embodiments, in order to form an image of the reticle MA supported by the support structure MT on a target region C of the substrate W, the controller CN may be operable to control the scanning mechanism to move the reticle MA supported by the support structure MT within the exposure region and to control the position of a first pair of masking blades 36, 38 to mask adjacent target regions C of the substrate W from the radiation beam.

[0229] [000228] In some embodiments, in order to illuminate the second portion 62 of the reticle-pellicle assembly 15 with the radiation beam B, the controller CN may be operable to control the first and / or second pair of masking blades 36, 38, 32, 34 to illuminate the expanded exposure field.

[0230] [000229] The exposure field is the area of ​​the reticle-pellicle assembly 15 that is exposed to radiation. It should be understood that the range of the exposure field in the non-scan direction (x direction) can be defined by the range of the radiation beam in the non-scan direction (which can be defined by a pair of masking blades 32, 34). It should be understood that the range of the exposure field in the scan direction (y direction) can be defined by both the range of the radiation beam in the scan direction (which can be defined by a pair of masking blades 36, 38) and the range of the scan operation.

[0231] [000230] Such illumination of the magnified field may be part of the exposure of the target region C of the substrate W (i.e., part of the image formation process). Alternatively, illumination of the magnified field may occur between the exposure of two target regions C of the substrate W (i.e., between two image formation processes). For example, illumination of the magnified field may occur between the exposure of different target regions C (or dies) of a single substrate W, or between the exposure of different substrates W.

[0232] [000231] In some embodiments, in order to illuminate the second portion 62 of the reticle-pellicle assembly 15 with the radiation beam B, the controller CN may be operable to control the first and / or second pair of masking blades 36, 38, 32, 34 to vary the exposure field. It should be understood that the range and / or position of the exposure field may be varied.

[0233] [000232] In some embodiments, the controller CN may be operable to control the first and / or second pair of masking blades 36, 38, 32, 34 such that the exposure field for at least some imaging processes is different from the exposure field for previous imaging processes.

[0234] [000233] In some embodiments, the controller CN may be operable to control the first and / or second pair of masking blades 36, 38, 32, 34 such that at least one edge of the exposure field for each of at least some image forming processes is offset by a certain amount. For example, the offset may be approximately 50 μm. At least one edge of the exposure field may be stepped by such an offset for every n exposure processes (e.g., per exposure process). In some embodiments, all edges of the exposure field may be stepped by such an offset. The method implemented by the controller CN may, for example, use approximately five different positions for each edge of the exposure field, and the position of each edge of the exposure field may be stepped or cyclically moved to all (e.g., five) different positions.

[0235] [000234] In some embodiments, the controller CN may be operable to control the first and / or second pair of masking blades 36, 38, 32, 34 such that the exposure field for multiple imaging processes is continuously changing. For example, the position of at least one edge of the exposure field may be continuously changing. For example, the position of at least one edge of the exposure field may oscillate over a range of positions around a nominal position. The amplitude of such oscillation may be approximately 100 μm. In some embodiments, all edges of the exposure field may be continuously changing.

[0236] [000235] In some embodiments, in order to illuminate a second portion 62 of the reticle-pellicle assembly 15 with the radiation beam B, the controller CN may be operable to control the first and / or second pair of masking blades 36, 38, 32, 34 so that the outer perimeter of the exposure area extends into an expanded area. For example, the outer perimeter of the exposure area may extend into an area having dimensions of approximately 100 μm.

[0237] [000236] In some embodiments, in order to illuminate a second portion 62 of the reticle-pellicle assembly 15 with a radiation beam B, the controller CN may be operable to control a first and / or second pair of masking blades 36, 38, 32, 34 such that when an image of the reticle MA supported by the support structure MT is formed on a target region C adjacent to the edge of the substrate W of the substrate W, at least one of the masking blades 36, 38, 32, 34 corresponding to the edge of the exposure field adjacent to the edge of the substrate W is positioned to expand the exposure field.

[0238] [000237] Target regions C adjacent to the edges of the substrate W are sometimes called edge target regions C or edge dies. It should be understood that such edge target regions C do not have adjacent target regions C on all sides. Rather, each edge target region C does not have adjacent nearby target regions on at least one side (adjacent to the edge of the substrate W). For such edge target regions C (or dies) on the substrate W, masking blades 32, 34, 36, and 38 may be positioned to expand the exposure area. For example, for such edge target regions C (or dies) on the substrate W, masking blades 32, 34, 36, and 38 may be shifted by 1 mm or more from their nominal positions to expand the exposure area. Advantageously, this will illuminate portion 62 of the reticle-pellicle assembly 15 adjacent to the first portion 60 of the reticle-pellicle assembly 15 with the radiation beam B. When the masking blades 32, 34, 36, and 38 are controlled in this manner for all such edge dies, the portion 62 of the reticle-pellicle assembly 15 that substantially surrounds the first portion 60 of the reticle-pellicle assembly 15 can be illuminated with radiation B.

[0239] [000238] Forming multiple images of the reticle MA on the substrate may include forming images of the reticle MA on multiple target regions C of the substrate W. Each of the multiple target regions C may be roughly rectangular. The multiple target regions C may be arranged as a two-dimensional array.

[0240] [000239] Generally, the duration of periodic illumination of the second portion 62 of the reticle-pellicle assembly 15 by the radiation beam B may be long enough to heat the second portion 62 of the pellicle to a desired temperature (e.g., to a temperature above a threshold temperature at which hydrogen etching of the pellicle can be ignored). In some embodiments, the desired temperature may be above 900K. It should be understood that the time required to heat the pellicle to the desired temperature will depend on the output of the radiation beam while the pellicle is being heated.

[0241] [000240] In some embodiments, when the second portion 62 of the reticle-pellicle assembly 15 is illuminated with the radiation beam B, the controller CN may be operable to heat the pellicle to a temperature at which the hydrogen etching rate of the pellicle is negligible. For example, the controller CN may be operable to heat the pellicle to a temperature above 800K, for example, above 900K.

[0242] [000241] Some embodiments of the present disclosure, as will be discussed with reference to Figures 16 to 19, relate to a novel pellicle for use in a lithography apparatus adapted to experience less plasma etching during use than existing pellicles, and to a lithography apparatus LA of the type shown in Figure 1 equipped with such a novel pellicle.

[0243] [000242] Figure 16 shows a section of a portion of the reticle-pellicle assembly. Figure 16 shows a portion of the reticle MA, the pellicle frame 17, and the pellicle membrane 19. Also shown is a portion of the support 74 that facilitates the connection between the pellicle (frame 17 and membrane 19) and the reticle MA. The support 74 may include an intermediate fixing member (known as a stud) fixed to the patterning device (reticle). The intermediate fixing member (stud) on the patterning device (reticle) may engage (e.g., detachably engage) with a mounting member of the pellicle frame 17. All of these are schematically shown as the support 74. Also shown is one of the x-masking blades 32.

[0244] [000243] The portion of the pellicle that can receive EUV radiation when in use is indicated by arrow 76 in Figure 16. This EUV radiation-receiving portion 76 of the pellicle may be roughly equivalent to the first portion 60 of the reticle-pellicle assembly 15 discussed above (the portion illuminated by (EUV) radiation B to form an image of the reticle MA on the substrate W). That is, portion 76 of the pellicle may include the portion of the pellicle 19 that corresponds to the image-forming portion of the reticle MA.

[0245] [000244] The portion of the pellicle that does not receive EUV radiation but does receive hydrogen plasma when in use is indicated by arrow 78 in Figure 16. This portion 78 of the pellicle surrounds the central portion 60 of region 62 of the reticle-pellicle assembly 15 and may be roughly equivalent to the portion discussed above. The location where the etching intensity by hydrogen plasma is maximum is indicated by arrow 80 in Figure 16.

[0246] [000245] During use, the film 19 is subjected to a heat load from EUV radiation used by the lithography apparatus (e.g., EUV radiation) and possibly from one or more heaters. However, the frame 17 is kept at a significantly lower temperature than the film 19 due to its remarkably high heat capacity and thermal inertia. The region of the film 19 in contact with the frame 17 experiences a temperature decrease due to the presence of the frame 17 and good thermal contact between the frame 17 and the film 19 (the frame 17 acts like a heat sink). However, it can be seen that there is an overlap between the portion 78 of the pellicle that does not receive EUV radiation but receives hydrogen plasma and the frame 17.

[0247] [000246] Flash heating of this portion of the pellicle film 19 that overlaps with both the frame 17 and the hydrogen plasma region is not effective in raising the temperature of this portion of the film 19 to a temperature higher than 600°C because the frame 17 acts as a heat sink.

[0248] [000247] Some embodiments of the present disclosure relate to a novel pellicle for use in a lithography apparatus LA, which is adapted to move the contact between the frame 17 and the film 19 outward along at least one edge of the film 19, as will be discussed with reference to Figures 17A to 17E.

[0249] [000248] Figure 17A is a schematic cross-sectional view of a portion of a known pellicle 82. The known pellicle 82 comprises a frame 17 and a membrane 19 surrounded and supported by the frame 17. The membrane 19 is generally planar and defines the plane of the pellicle 82. The frame 17 has a generally rectangular cross-section and a thickness 84 that is generally perpendicular to the plane of the pellicle and a width 86 that is generally parallel to the plane of the pellicle.

[0250] [000249] Figures 17B to 17D are schematic cross-sectional views of portions of three new pellicles 88, 89, and 90. The new pellicles 88, 89, and 90 also each comprise a frame 17 and a membrane 19 surrounded and supported by the frame 17. The membrane 19 is generally planar and defines the plane of the pellicles 88, 89, and 90. The frame 17 has a thickness 84 that is generally perpendicular to the plane of the pellicle and a width 86 that is generally parallel to the plane of the pellicle.

[0251] [000250] Each frame 17 of the new pellicles 88, 89, and 90 shown in Figures 17B to 17D may be thought to have an outer portion 17a and an inner portion 17b. The outer portion 17a of the frame 17 is in contact with the film 19, and the inner portion 17b of the frame 17 is not in contact with the film 19 along at least one edge of the film 19. In particular, along at least one edge of the film 19, the inner portion 17b of the frame 17 has a thinner thickness 84 than the outer portion 17a of the frame 17 so that the inner portion 17b of the frame 17 does not come into contact with the film 19.

[0252] [000251] During use, the film 19 is subjected to a thermal load from radiation used by the lithography apparatus (e.g., EUV radiation) and one or more heaters, while the frame 17 remains cool. Therefore, the area of ​​the film 19 in contact with the frame 17 experiences a temperature decrease due to the presence of the frame 17 (which has greater thermal inertia than the film 19 due to its larger dimensions). The new pellicles 88, 89, and 90 shown in Figures 17B to 17D are advantageous because they allow the contact point between the frame 17 and the film 19 to be moved outward along at least one edge of the film 19 without narrowing the width 86 of the frame 17 (i.e., the dimension roughly parallel to the plane of the pellicle of the frame 17). This allows the frame 17 to maintain a similar level of rigidity (e.g., with the known pellicle 82 shown in Figure 17A) while moving the contact point between the frame 17 and the film 19 outward. Furthermore, advantageously, by moving the portion of the film 19 that is in contact with the frame 17 (and is at a lower temperature than other parts of the film 19 during use) outwards, the film 19 is exposed to little to no high-intensity EUV-induced hydrogen plasma.

[0253] [000252] The new pellicles 88, 89, and 90 shown in Figures 17B to 17D each define a recess 92 between the inner portion 17b (which is thinner in thickness 84) of the frame 17 and the film 19. It should be understood that the recess 92 can have a variety of different shapes. For example, the recess 92 may have a generally uniform thickness (as shown in Figures 17C and 17D). The embodiment shown in Figure 17C also includes a fillet or rounded portion between the inner portion 17a and the outer portion 17b of the frame 17. This configuration may reduce stress concentration in the frame 17.

[0254] [000253] Alternatively, the recess 92 formed between the inner portion 17b of the frame 17 (which is thinner in thickness 84) and the film 19 may have a thickness 84 that varies from the inner edge of the frame 17 to the outer portion 17b of the frame 17 (as shown in Figure 17B).

[0255] [000254] The width 86 of the inner portion 17b of the frame 17 (which is thinner at a thickness of 84) may be selected so that the portion of the film 19 that is in contact with the frame 17 (and is at a lower temperature than other parts of the film 19 during use) is not adjacent to the high-intensity EUV-induced hydrogen plasma (i.e., it does not overlap with the region 78 of the pellicle that does not receive EUV radiation but is exposed to the hydrogen plasma and the frame 17 (see Figure 16)).

[0256] [000255] The width 86 of the thin inner portion 17b of the frame 17 may be greater than 2 mm. In some embodiments, the width 86 of the inner portion 17b of the frame 17 may be greater than 2.2 mm. In some embodiments, the width 86 of the inner portion 17b of the frame 17 may be approximately 2.5 mm.

[0257] [000256] Figure 17E is a schematic cross-sectional view of a portion of another new pellicle 94. The new pellicle 94 shown in Figure 17E is similar to the known pellicle 82 shown in Figure 17A, except that the new pellicle 94 has a narrower width 86 than the known pellicle 82 shown in Figure 17A. This also moves the contact point between the frame 17 and the film 19 outward along at least one edge of the film 19, resulting in less etching of the pellicle.

[0258] [000257] Some embodiments of the present disclosure relate to a lithography apparatus of the type shown in Figure 1, comprising a frame 17, a pellicle having a film 19 surrounded and supported by the frame 17, a hydrogen source, and an illumination system configured to irradiate the pellicle, wherein the portion of the film 19 in contact with the frame 17 is positioned so as not to diffuse the EUV-induced hydrogen plasma.

[0259] [000258] Advantageously, since the portion of the film 19 in contact with the frame 17 is positioned where the EUV-induced hydrogen plasma does not diffuse, the film 19 is less susceptible to etching by the hydrogen plasma. The pellicle of such a lithography apparatus may include one of the pellicles 88, 89, 90, and 94 shown in Figures 17B to 17E, and / or a new type of pellicle shown in Figures 18 and 19.

[0260] [000259] Some embodiments of the present disclosure relate to a novel pellicle for use in a lithography apparatus LA adapted to provide a shield for protecting the periphery of a film 19 from hydrogen plasma etching, as will be discussed with reference to Figures 18 to 19.

[0261] [000260] Figure 18 shows a new reticle-pellicle assembly 98 having a new pellicle according to an embodiment of the present disclosure. Figure 19 shows a magnified view of the new reticle-pellicle assembly 98 shown in Figure 18. The new pellicle is for use in a lithography apparatus LA and comprises a frame 17, a membrane 19 surrounded and supported by the frame 17, and shields 98a, 98b adjacent to the periphery of the membrane 19 adjacent to the frame 17. The membrane 19 is generally planar and defines the plane of the pellicle. The shields 98a, 98b are spaced apart from the membrane 19 in a direction generally perpendicular to the plane of the pellicle.

[0262] [000261] In the embodiments shown in Figures 18 and 19, the shield comprises a first shielding member 98a adjacent to a first surface of the peripheral portion of the film 19, and a second shielding member 98b adjacent to a second surface of the peripheral portion of the film 19. The first surface may be the surface that faces away from the reticle MA when the pellicle is in use (and may be referred to as the top or front surface of the pellicle). The second surface may be the surface that faces towards the reticle MA when the pellicle is in use (and may be referred to as the bottom or rear surface of the pellicle). In alternative embodiments, only one of the first and second shielding members 98a, 98b may be included.

[0263] [000262] The novel pellicle shown in Figures 18 and 19 is advantageous because the shields 98a and 98b can protect the pellicle from etching by plasma (e.g., EUV-induced hydrogen plasma) when used, for example, in an EUV lithography apparatus LA.

[0264] [000263] Conventionally, the reticulous machining blades 32, 34, 36, and 38 were thought to be able to function as a plasma shield for the pellicle. However, it has recently been found that the region where etching of the CNT film progresses most is outside the exposure area (i.e., the portion 76 of the pellicle that can receive EUV radiation) below the reticulous machining blades 32, 34, 36, and 38 (this indicates that the reticulous machining blades 32, 34, 36, and 38 are not effective as a plasma shield for the pellicle). It is thought that the distance between the reticulous machining blades 32, 34, 36, and 38 and the pellicle film 19 is too large to obtain an effective shielding function. During use, there is usually not a large space between the pellicle film 19 and other components (e.g., reticle masking blades 32, 34, 36, 38), but there is sufficient space for the relatively thin shields 98a and 98b, suggesting that the new pellicle shown in Figures 18 and 19 can be used with existing lithography apparatus LA.

[0265] [000264] Shields 98a and 98b extend beyond the pellicle boundary but may remain outside the quality area (or the portion of the pellicle corresponding to the image-forming area of ​​the reticle MA).

[0266] [000265] The first shield member 98a and / or the second shield member 98b may be directly or indirectly supported by either the frame 17 or the support 74.

[0267] [000266] The pellicle support 74, which facilitates connection with the reticle MA, may include an additional or extended portion 74b that extends further away from the reticle MA than the membrane 19. The first shield member 98a may be provided as a cantilever structure extending from this additional or extended portion 74b.

[0268] [000267] The second shield member 98b may be provided as a cantilever beam structure extending from the frame 17. As shown in Figure 19, this may be achieved by providing the frame as two frame sections 17a and 17b, sandwiching the second shield member 98b between the two frame sections 17a and 17b, and extending from there adjacent to the membrane 19.

[0269] [000268] Please understand that the new pellicles shown in Figures 18 and 19 may, if necessary, have any of the features of the new pellicles shown in Figures 17B to 17E.

[0270] [000269] It may be desirable that the shields 98a and 98b be as close as possible to the surface of the film 19. This is to minimize the amount of plasma diffusing beneath the shields 98a and 98b (i.e., between the shields 98a and 98b and the film 19) and maximize plasma shielding. Generally, it may be desirable that the distance between the shields 98a and 98b and the surface of the film 19 be less than the Debye length of the plasma (which may be less than 1 mm, or less than 0.2 mm during EUV pulses). It may also be desirable that the shields 98a and 98b be sufficiently far from the surface of the film 19 so as to allow for sagging of the film 19 without the risk of the shields 98a and 98b contacting the surface of the film 19.

[0271] [000270] It should be understood that the first shield member 98a and the second shield member 98b may be positioned at different distances from the film 19. Alternatively, the first shield member 98a and the second shield member 98b may be positioned at substantially the same distance from the film 19.

[0272] [000271] The distance between shields 98a, 98b and the film 19 may be less than 1 mm. It should be understood that the distance 114a between the first shield member 98a and the film 19 can be less than 1 mm, and / or the distance 114b between the second shield member 98b and the film 19 can be less than 1 mm. In particular, the distance between the front surface of the film 19 and the adjacent shield member 98a can be less than 1 mm. The distance 114a between the first shield member 98a and the film 19 can be from 200 μm to 1000 μm. The distance 114a between the first shield member 98a and the film 19 can be from 400 μm to 800 μm. The distance 114b between the second shield member 98b and the film 19 can be from 200 μm to 1000 μm. The distance 114b between the second shield member 98b and the film 19 can be from 400 μm to 800 μm.

[0273] [000272] Shields 98a, 98b may have a thickness less than 1 mm. The thickness 112a of the first shield member 98a can be approximately from 100 μm to 300 μm. The thickness 112b of the second shield member 98b can be approximately from 100 μm to 300 μm. In some embodiments, the shield members 98a, 98b may have thicknesses 112a, 112b that are about 200 μm or less. The thicknesses 112a, 112b of the shield members 98a, 98b may be selected to be readily available on the market.

[0274] [000273] Shields 98a, 98b may extend from the frame 17 by a distance 116 within the plane of the film 19. The distance 116 can be, for example, approximately from 1 mm to 1.5 mm.

[0275] [000274] Preferably, shields 98a, 98b may extend to cover portions that, in the absence of the shields, are adjacent to the plasma during use of the membrane 19 but do not receive EUV radiation. Shields 98a, 98b may be located at a distance 118 from the quality area of the pellicle 78 (i.e., the portion corresponding to the image formation area of the reticle MA of the pellicle) so as not to interfere with the EUV light cone. For example, the distance 118 may be approximately from 0.5 mm to 1.5 mm.

[0276] [000275] Shields 98a, 98b may be formed from a material that transmits the wavelength of radiation used to periodically heat the pellicle during use.

[0277] [000276] For example, shields 98a, 98b may be formed from a material that transmits infrared (IR) and / or deep ultraviolet (DUV) radiation. Thereby, shields 98a, 98b can protect the pellicle from the plasma while periodically heating the membrane 19 using these radiations.

[0278] [000277] Shields 98a, 98b may be formed from a material that is inert to hydrogen plasma.

[0279] [000278] Shields 98a, 98b may include sapphire (Al2O3). For example, shields 98a, 98b may include a sapphire (Al2O3) coated glass material. Alternatively, shields 98a, 98b may be formed from sapphire.

[0280] [000279] Some embodiments of the present disclosure relate to a lithography apparatus LA of the type shown in Figure 1, comprising a frame 17, a film 19 surrounded and supported by the frame 17, and a pellicle having shields 98a, 98b adjacent to the peripheral portion of the film 19 adjacent to the frame 17, a hydrogen source, and an illumination system IL configured to illuminate the pellicle with radiation, wherein the shields 98a, 98b are adjacent to a portion of the film 19 to which, without such shields, the EUV-induced hydrogen plasma would diffuse.

[0281] [000280] Advantageously, the shields 98a and 98b are part of the film and adjacent to the portion where, in the absence of such shields 98a and 98b, the EUV-induced hydrogen plasma would diffuse, thus protecting the film 19 from the plasma (and associated plasma etching) that would be present in the absence of such shields 98a and 98b. The pellicle of such a lithography apparatus LA may include new pellicles 88, 89, 90, 94 and / or new pellicles of the type shown in Figures 18 and 19, as shown in Figures 17B to 17E.

[0282] [000281] References to masks or reticles in this book may be interpreted as references to patterning devices (masks or reticles are examples of patterning devices), and these terms may be used interchangeably. In particular, the term mask assembly is synonymous with reticle assembly and patterning device assembly.

[0283] [000282] While the text specifically refers to embodiments of the present invention in relation to lithography apparatus, embodiments of the present invention may be used in other apparatuses. Embodiments of the present invention may constitute part of a mask inspection apparatus, a metrology apparatus, or any apparatus for measuring or processing objects such as wafers (or other substrates) or masks (or other patterning devices). These apparatuses are generally referred to as lithography tools. Such lithography tools may operate under vacuum conditions or ambient (non-vacuum) conditions.

[0284] [000283] The term "EUV radiation" is sometimes considered to encompass electromagnetic radiation having wavelengths in the range of 4 to 20 nm, for example, in the range of 13 to 14 nm. EUV radiation may have wavelengths less than 10 nm, for example, in the range of 4 to 10 nm, such as 6.7 nm or 6.8 nm.

[0285] [000284] Although this text specifically refers to the use of lithography equipment in the manufacture of ICs, it should be understood that lithography equipment described herein may have other applications. Possible other applications include the manufacture of integrated optical systems, guidance and detection patterns for magnetic domain memory, flat panel displays, liquid crystal displays (LCDs), thin-film magnetic heads, and the like.

[0286] [000285] While specific embodiments of the present invention have been described above, it will be understood that the present invention may be carried out in ways other than those described. The above description is for illustrative purposes only and is not limiting. Accordingly, it will be apparent to those skilled in the art that modifications to the described invention may be made without departing from the following claims and clauses. 1. The reticle image is formed multiple times on the substrate, each time Illuminating the first part of the reticle-pellicle assembly with a radiation beam, and The process of image formation includes focusing radiation scattered by a reticle and projecting it onto a target region of a substrate using a projection optical system, and A lithography method comprising periodically illuminating a second portion of a reticle-pellicle assembly with a radiation beam, at least partially surrounding a first portion. 2. The method of Clause 1, wherein the second portion of the reticle-pellicle assembly is periodically illuminated with a radiation beam, which is achieved by periodically illuminating an expanded exposure field. 3. The method of Clause 1 or Clause 2, wherein the second portion of the reticle-pellicle assembly is periodically illuminated with a radiation beam, which is achieved by changing the exposure field. 4. The method of Clause 3, wherein the exposure field for at least some of the imaging processes is different from the exposure field for the previous imaging process. 5. The method of Clause 4, wherein at least one edge of the exposure field for each of at least some of the image-forming processes is offset by a certain amount. 6. The method of clause 3, wherein the exposure field for multiple image formation processes is continuously changed. 7. The method according to any one of the clauses 1 to 6, wherein during each image-forming process, at least one masking blade is used to mask an adjacent target area of ​​the substrate from the radiation beam. 8. The method of Clause 7, where illuminating an enlarged exposure field or changing the exposure field is achieved by controlling at least one masking blade, directly or indirectly dependent on Clause 2 or Clause 3. 9. The method of Clause 7 or Clause 8, wherein the position of at least one reticle masking blade is operated such that the outer edge of the exposure area extends into the expanded area. 10. The method of any one of the clauses 7 to 9, wherein four masking blades are used during exposure of each target region to define the exposure field, and for each target region adjacent to the edge of the substrate, at least one of the masking blades corresponding to the edge of the exposure field adjacent to the edge of the substrate is positioned to expand the exposure field. 11. A method according to any one of the clauses 1 to 10, wherein forming an image of a reticle multiple times on a substrate includes forming an image of a reticle on a plurality of target regions arranged as a two-dimensional array on the substrate, wherein the two-dimensional array of target regions is exposed one row at a time, and the rows are not exposed sequentially. 12. A method according to any one of the clauses 1 to 11, wherein each image-forming process includes scanning exposure, in which the reticle-pellicle assembly is moved in the scanning direction relative to the radiation beam. 13. The method of any one of the clauses 1 to 12, as directly or indirectly dependent on clause 2, wherein when the magnified exposure field is periodically illuminated, radiation scattered from the reticle-pellicle assembly is not projected onto the substrate. 14. A method according to any one of the clauses 1 to 13, comprising periodically illuminating a second portion of a reticle-pellicle assembly with a radiation beam, or exposing the second portion to EUV radiation to heat the pellicle to a temperature at which the hydrogen etching rate of the pellicle is negligible. 15. The method of any one of the clauses 1 to 14, wherein the second portion of the reticle-pellicle assembly is periodically illuminated with a radiation beam, or the second portion of the reticle-pellicle assembly is illuminated once per substrate. 16. The method of any one of the clauses 1 to 15, wherein the second portion of the reticle-pellicle assembly is periodically illuminated with a radiation beam such that the second portion of the reticle-pellicle assembly is illuminated once for each row of target regions on the substrate. 17. A lithography component of a lithography apparatus, wherein the lithography component is A support structure constructed to support a reticle-pellicle assembly for receiving a radiation beam, It is a controller, (a) Forming multiple images of a reticle supported by a support structure onto a substrate, each image formation process including illuminating a first portion of the reticle-pellicle assembly with a radiation beam and projecting the radiation scattered by the reticle onto a target region of the substrate using a projection optical system, (b) To periodically illuminate the second part of the reticle-pellicle assembly, which at least partially surrounds the first part, with a radiation beam, A lithography component comprising a support structure and / or a controller capable of controlling the radiation beam. 18. A lithography component of Clause 17, wherein the controller is operable to implement any one of the methods described in Clauses 1 through 16. 19. A lithography component according to Clause 17 or Clause 18, further comprising a scanning mechanism capable of moving a support structure in the scanning direction relative to the radiation beam. 20. A first pair of masking blades configured to define a range in a first direction of the exposure area, A lithography component according to any one of clauses 17 to 19, further comprising a second pair of masking blades configured to define a range in a second direction of the exposure area. 21. The first direction is the scanning direction, and in order to form an image of the reticle supported by the support structure on the target region of the substrate, the controller The scanning mechanism is controlled to move the reticle, supported by the support structure, within the exposure area. A lithography component of Clause 20, as subject to Clause 19, which is operable to control the position of a first pair of masking blades to mask adjacent target areas of a substrate from the radiation beam. 22. A lithographic component according to any one of clauses 17 to 21, when directly or indirectly dependent on clause 20, wherein the controller is operable to control the first and / or second pair of masking blades to illuminate a second portion of the reticle - pellicle assembly with a radiation beam such that an enlarged exposure field is illuminated. 23. A lithographic component according to any one of clauses 17 to 22, when directly or indirectly dependent on clause 20, wherein the controller is operable to control the first and / or second pair of masking blades to change an exposure field in order to illuminate a second portion of the reticle - pellicle assembly with a radiation beam. 24. A lithographic component according to clause 23, wherein the controller is operable to control the first and / or second pair of masking blades such that an exposure field for at least some of the imaging processes is different from an exposure field for a previous imaging process. 25. A lithographic component according to clause 24, wherein the controller is operable to control the first and / or second pair of masking blades such that at least one edge of an exposure field for each of at least some of the imaging processes is offset by an offset. 26. A lithographic component according to clause 23, wherein the controller is operable to control the first and / or second pair of masking blades such that exposure fields for a plurality of imaging processes change continuously. 27. A lithographic component according to any one of clauses 17 to 26, when directly or indirectly dependent on clause 20, wherein the controller is operable to control the first and / or second pair of masking blades to illuminate a second portion of the reticle - pellicle assembly with a radiation beam such that an outer perimeter of an exposure area extends into an extended area. 28. A lithography component of any one of the clauses 17 to 27, as directly or indirectly dependent on clause 20, wherein the controller is operable to control a first and / or second pair of masking blades such that, when an image of the reticle supported by the support structure is formed on a target area of ​​the substrate adjacent to the edge of the substrate, at least one of the masking blades corresponding to the edge of the substrate adjacent to the edge of the exposure field is positioned to expand the exposure field when the image of the reticle supported by the support structure is formed on a target area of ​​the substrate adjacent to the edge of the substrate. 29. A lithography component according to any one of Clauses 17 to 28, wherein when the second part of the reticle-pellicle assembly is illuminated with a radiation beam, the controller is operable to heat the pellicle to a temperature at which the hydrogen etching rate of the pellicle is negligible. 30. A lithography apparatus having any one of the components specified in clauses 17 to 29. 31. An illumination system configured to adjust the radiant beam received by a reticle-pellicle assembly, A circuit board table constructed to support the circuit board, A lithography apparatus according to clause 30, further comprising a projection system configured to receive a radiation beam from a reticle-pellicle assembly and project the radiation beam onto a substrate. 32. A pellicle used in a lithography apparatus, wherein the pellicle is Frame and, It comprises a membrane surrounded and supported by a frame, The film is generally planar, defining the plane of the pellicle, The frame has a thickness that is roughly perpendicular to the plane of the pellicle and a width that is roughly parallel to the plane of the pellicle. In the plane of the pellicle, the outer portion of the frame is in contact with the membrane, and along at least one edge of the membrane, the inner portion of the frame is thinner than the outer portion of the frame so as not to come into contact with the membrane. 33. The pellicle of clause 32, wherein the recess formed between the inner portion of the thin frame and the membrane has a generally uniform thickness. 34. The pellicle of clause 32, wherein the recess formed between the thin inner portion of the frame and the membrane has a thickness that varies from the inner edge of the frame to the outer portion of the frame. 35. A pellicle conforming to any one of clauses 32 to 34, where the width of the inner portion of the thin frame is greater than 2.2 mm. 36. A pellicle comprising a frame and a membrane surrounded and supported by the frame, Hydrogen source, It includes a lighting system configured to illuminate the pellicle with radiation, A lithography apparatus in which the portion of the membrane in contact with the frame is positioned so that the EUV-induced hydrogen plasma does not diffuse. 37. A pellicle used in a lithography apparatus, wherein the pellicle is Frame and, A membrane surrounded and supported by a frame, It comprises a shield adjacent to the peripheral part of the membrane adjacent to the frame, The film is generally planar, defining the plane of the pellicle, A pellicle in which the shield is separated from the membrane in a direction roughly perpendicular to the plane of the pellicle. 38. The pellicle according to clause 37, wherein the shield comprises a first shielding member adjacent to a first surface of the peripheral portion of the membrane and a second shielding member adjacent to a second surface of the peripheral portion of the membrane. 39. A pellicle according to Clause 37 or Clause 38, where the distance between the shield and the membrane is less than 1 mm. 40. A pellicle according to any one of clauses 37 to 39, having a shield thickness of less than 1 mm. 41. A pellicle according to any one of the clauses 37 to 40, wherein the shield extends above the membrane, approximately 1 mm to 1.5 mm away from the frame. 42. A pellicle according to any one of the clauses 37 to 41, wherein the shield is formed of a material that transmits wavelengths of radiation used to periodically heat the pellicle when in use. 43. A pellicle according to any one of the clauses 37 to 42, wherein the shield is formed from a material inert to hydrogen plasma. 44. A pellicle according to any one of the clauses 37 to 43, wherein the shield contains sapphire (Al2O3). 45. A pellicle comprising a frame, a membrane surrounded and supported by the frame, and a shield adjacent to the periphery of the membrane adjacent to the frame, Hydrogen source, It includes a lighting system configured to illuminate the pellicle with radiation, A lithography apparatus in which the shield is part of a film and is adjacent to a region where, without such shielding, the EUV-induced hydrogen plasma would diffuse.

Claims

1. A lithography component of a lithography apparatus, wherein the lithography component is A support structure constructed to support a reticle-pellicle assembly for receiving a radiation beam, It is a controller, (a) Forming multiple images of the reticle supported by the support structure onto a substrate, each image forming process including illuminating a first portion of the reticle-pellicle assembly with the radiation beam and projecting the radiation scattered by the reticle onto a target region of the substrate using a projection optical system, (b) To periodically illuminate the second portion of the reticle-pellicle assembly, which at least partially surrounds the first portion, with the radiation beam, A lithography component comprising the support structure and / or a controller operable to control the radiation beam.

2. The lithography component of claim 1, wherein the controller is operable to carry out the method of any one of claims 16 to 31.

3. The lithography component according to claim 1 or 2, further comprising a scanning mechanism capable of moving the support structure in the scanning direction relative to the radiation beam.

4. A first pair of masking blades configured to define a range in a first direction of the exposure area, A lithography component according to any one of claims 1 to 3, further comprising a second pair of masking blades configured to define a range in a second direction of the exposure area.

5. The first direction is the scanning direction, and in order to form an image of the reticle supported by the support structure on the target region of the substrate, the controller The scanning mechanism is controlled to move the reticle supported by the support structure within the exposure area. A lithography component according to claim 4, as dependent on claim 3, which is operable to control the position of the first pair of masking blades in order to mask adjacent target regions of the substrate from the radiation beam.

6. A lithography component according to any one of claims 1 to 5, as directly or indirectly dependent on claim 4, wherein the controller is operable to control the first and / or second pair of masking blades to illuminate an expanded exposure field in order to illuminate the second portion of the reticle-pellicle assembly with the radiation beam.

7. A lithography component according to any one of claims 1 to 6, as directly or indirectly dependent on claim 4, wherein the controller is operable to control the first and / or second pair of masking blades to vary the exposure field in order to illuminate the second portion of the reticle-pellicle assembly with the radiation beam.

8. The lithography component of claim 7, wherein the controller is operable to control the first and / or second pair of masking blades such that the exposure field for at least some imaging processes is different from the exposure field for a previous imaging process.

9. The lithography component of claim 8, wherein the controller is operable to control the first and / or second pair of masking blades such that at least one edge of the exposure field for each of at least some image-forming processes is offset by a certain amount.

10. The lithography component of claim 7, wherein the controller is operable to control the first and / or second pair of masking blades such that the exposure field for a plurality of image-forming processes is continuously changing.

11. A lithography component according to any one of claims 1 to 10, directly or indirectly dependent on claim 4, wherein the controller is operable to control the first and / or second pair of masking blades so that the outer perimeter of the exposure area extends into an extended area, in order to illuminate the second portion of the reticle-pellicle assembly with the radiation beam.

12. A lithography component according to any one of claims 1 to 11, as directly or indirectly dependent on claim 4, wherein the controller is operable to control the first and / or second pair of masking blades so that at least one of the masking blades corresponding to the edge of the exposure field adjacent to the edge of the substrate is positioned to expand the exposure field when the controller forms an image of the reticle supported by the support structure on a target region adjacent to the edge of the substrate of the substrate.

13. A lithography component according to any one of claims 1 to 12, wherein when the second portion of the reticle-pellicle assembly is illuminated with the radiation beam, the controller is operable to heat the pellicle to a temperature at which the hydrogen etching rate of the pellicle is negligible.

14. A lithography apparatus comprising the components of any one of claims 1 to 13.

15. A lighting system configured to adjust the radiant beam received by the reticle-pellicle assembly, A circuit board table constructed to support the circuit board, The lithography apparatus according to claim 14, further comprising a projection system configured to receive the radiation beam from the reticle-pellicle assembly and project the radiation beam onto the substrate.

16. This involves forming the reticle image multiple times on the substrate, each time Illuminating the first part of the reticle-pellicle assembly with a radiation beam, and The process includes collecting the radiation scattered by the reticle and projecting it onto a target region of the substrate using a projection optical system to perform an image forming process, and A lithography method comprising periodically illuminating a second portion of the reticle-pellicle assembly, which at least partially surrounds the first portion, with a radiation beam.

17. The method of claim 16, wherein the periodic illumination of the second portion of the reticle-pellicle assembly with a radiation beam is achieved by periodic illumination of an expanded exposure field.

18. The method of claim 16 or 17, wherein the second portion of the reticle-pellicle assembly is periodically illuminated with a radiation beam by changing the exposure field.

19. The method of claim 18, wherein the exposure field for at least some of the image formation processes is different from the exposure field for a previous image formation process.

20. The method of claim 19, wherein at least one edge of the exposure field for each of at least some of the image-forming processes is offset by a certain amount.

21. The method of claim 18, wherein the exposure field for a plurality of image-forming processes is continuously varied.

22. The method according to any one of claims 16 to 21, wherein, between each image forming process, at least one masking blade is used to mask an adjacent target region of the substrate from the radiation beam.

23. The method of claim 22, in which illumination of the enlarged exposure field or modification of the exposure field is achieved by controlling the at least one masking blade, directly or indirectly dependent on claim 2 or 3.

24. The method of claim 22 or 23, wherein the position of the at least one reticle masking blade is operated such that the outer periphery of the exposure area extends into the expanded area.

25. The method according to any one of claims 22 to 24, wherein four masking blades are used during exposure of each target region to define the exposure field, and for each target region adjacent to the edge of the substrate, at least one of the masking blades corresponding to the edge of the exposure field adjacent to the edge of the substrate is positioned to expand the exposure field.

26. The method according to any one of claims 16 to 25, wherein forming an image of a reticle multiple times on a substrate includes forming the image of the reticle on a plurality of target regions arranged as a two-dimensional array on the substrate, wherein the two-dimensional array of target regions is exposed one row at a time, and the rows are not exposed in order.

27. The method according to any one of claims 16 to 26, wherein each image-forming process includes scanning exposure, in which the reticle-pellicle assembly is moved in a scanning direction relative to the radiation beam.

28. The method according to any one of claims 16 to 27, in which, when the magnified exposure field is periodically illuminated, the radiation scattered from the reticle-pellicle assembly is not projected onto the substrate, as directly or indirectly dependent on claim 17.

29. The method according to any one of claims 16 to 28, wherein periodically illuminating the second portion of the reticle-pellicle assembly with a radiation beam includes exposing the second portion to EUV radiation to heat the pellicle to a temperature at which the hydrogen etching rate of the pellicle is negligible.

30. The method according to any one of claims 16 to 29, wherein the periodic illumination of the second portion of the reticle-pellicle assembly with a radiation beam is such that the second portion of the reticle-pellicle assembly is illuminated once per substrate.

31. The method according to any one of claims 16 to 30, wherein the periodic illumination of the second portion of the reticle-pellicle assembly with a radiation beam is such that the second portion of the reticle-pellicle assembly is illuminated once for each row of target regions on the substrate.

Images