JP6154808B2 - Optical imaging apparatus having vibration isolation support unit - Google Patents

Description

  The present invention relates to an optical imaging apparatus used in an exposure process, and more particularly to an optical imaging apparatus of a microlithography system. The invention further relates to a method for supporting components of an optical projection unit. The invention can be used in the manufacture of photolithographic processes for manufacturing microelectronic devices, in particular semiconductor devices, or devices such as masks or reticles used in such photolithographic processes.

  Typically, an optical system used in the manufacture of a microelectronic device such as a semiconductor device includes a plurality of optical element units having optical elements such as lenses and mirrors arranged in the optical path of the optical system. These optical elements normally cooperate in an exposure process, and transfer a pattern image formed on a mask, a reticle or the like to a substrate such as a wafer. These optical elements are typically incorporated into a group of one or more functionally different optical elements. These various groups of optical elements can be held by various exposure units. Especially in refractive systems, such optical exposure units are often composed of a stack of optical element modules holding one or more optical elements. Usually, these optical element modules have a substantially ring-shaped support device on the outside, and this device supports one or a plurality of optical element holders each holding an optical element.

  An optical element group having at least mainly refractive optical elements, such as lenses, usually has a straight common symmetry axis of the optical elements, usually called an optical axis. Furthermore, the optical exposure unit holding such an optical element group is usually designed to be elongated and substantially tubular, and is therefore also typically referred to as a lens barrel.

  As semiconductor devices are increasingly miniaturized, there is always a need to increase the resolution of optical systems used in the manufacture of these semiconductor devices. The necessity to increase the resolution clearly increases the necessity to increase the numerical aperture (NA) and imaging accuracy of the optical system.

  As a technique for increasing the resolution, there is a shortening of the wavelength of light used in the exposure process. In recent years, approaches have been taken using light in the extreme ultraviolet (EUV) range, using wavelengths of 5 nm to 20 nm, typically about 13 nm. In this EUV range, general refractive optics can no longer be used. This is due to the fact that in this EUV range, the materials generally used for refractive optical elements exhibit an absorbance that is too high to obtain high quality exposure results. Therefore, in the EUV range, a reflection system having a reflection element such as a mirror is used in the exposure process, and a pattern image formed on the mask is transferred to a substrate such as a wafer.

  The transition to the use of high numerical aperture (eg NA> 0.4-0.5) reflective systems in the EUV range poses significant challenges for the design of optical imaging devices.

  One extremely important accuracy requirement is the positional accuracy of the image on the substrate, also referred to as line of sight (LoS) accuracy. The line-of-sight accuracy is typically proportional to the approximate reciprocal of the numerical aperture. Accordingly, the line-of-sight accuracy is 1.4 times smaller in the optical imaging device having the numerical aperture NA = 0.45 than in the optical imaging device having the numerical aperture NA = 0.33. The line-of-sight accuracy is typically 0.5 nm or less when the numerical aperture NA = 0.45. If double patterning is possible in the exposure process, the accuracy will generally have to be further reduced by a factor of 1.4. Therefore, in this case, the line-of-sight accuracy will be even less than 0.3 nm.

  In particular, the above results in very severe conditions with respect to the relative positions between components involved in the exposure process. Furthermore, it is not always necessary to provide an optical system with high imaging accuracy in order to reliably obtain a high-quality semiconductor device. Such high accuracy must also be maintained over the entire exposure process and the lifetime of the optical system. As a result, the components of the optical imaging device, i.e. the masks, optical elements and wafers that cooperate in the exposure process, for example, are supported in a defined manner and a constant spatial relationship between these optical imaging device components is maintained. Thus, a high quality exposure process must be provided.

  In particular under the influence of vibrations introduced by grounding structures supporting the device and / or accelerated masses (eg moving components, turbulent streams, etc.), internal sources of vibration disturbances such as optical imaging devices, and heat In order to maintain a constant spatial relationship between components of the optical imaging device during the entire exposure process, even under the influence of mechanically induced position changes, the spatial relationship between specific components of the optical imaging device is It is necessary to capture at least intermittently and to adjust at least one position of the optical imaging device according to the result of this capture process.

  In conventional systems, this process of capturing the spatial relationship between cooperating components in the exposure process is performed with an optical projection system to allow for rapid synchronization of actively adjusted portions of the imaging device. This is done via a measurement system that uses the central support structure with the substrate system as a common reference.

  On the other hand, increasing the numerical aperture typically results in an increase in the size of the optical element used, also referred to as the optical footprint of the optical element. The increase in the optical footprint of the optical elements used adversely affects their dynamic properties and the control system used to realize the above-described adjustment. Furthermore, an increase in optical footprint typically results in an increase in the light incident angle. However, at such an increased angle of incidence of light, the transmission of the multilayer coating typically used to create the reflective surface of the optical element is greatly reduced, resulting in undesirable loss of optical power and optical due to absorption. An increase in the heating of the element is clearly brought about. As a result, larger optical elements must be used to enable such imaging on a commercially acceptable scale. Such an environment leads to an optical imaging device with relatively large optical elements that have an optical footprint of up to 1 m × 1 m and are arranged very close to each other with a spacing of 60 mm or less.

  Several problems arise from this situation. First, regardless of the so-called aspect ratio of the optical element (ie, the ratio of thickness to diameter), large optical elements generally exhibit a low resonant frequency. On the other hand, for example, the resonant frequency of a mirror with an optical footprint of 150 mm (diameter) and a thickness of 25 mm is typically 4000 Hz, and a mirror with an optical footprint of 700 mm is typically 1500 Hz even with a thickness of 200 mm. The resonance frequency is hardly reached. Furthermore, an increase in the size and weight of the optical element also means an increase in static deformation due to different gravitational constants at various locations around the world, and if not corrected, the imaging performance is impaired.

  In conventional support systems that attempt to support an optical element with maximum stiffness (ie, a maximized resonance frequency of the support system), the low resonance frequency of the optical element itself reduces the adjustment control band, which results in positional accuracy. Decreases.

  In addition, large optical elements that are large objects for image shift ultimately result in a support structure that is large and less rigid for the optical system. Such a low stiffness support structure not only further limits the regulation control performance, but also causes residuals due to quasi-static deformation caused by the remaining low frequency vibration disturbances. Therefore, the adverse effect of vibration disturbance becomes more prominent.

  And the increased thermal load on the optical elements used (due to the absorption of light energy) and the increased throughput desired for such systems requires more cooling work, in particular the flow rate of the cooling liquid used. Need to increase. Such an increase in the flow rate of the cooling liquid tends to increase the vibration disturbance introduced into the system, and thus the line-of-sight accuracy is lowered.

  The object of the present invention is therefore to overcome the above-mentioned drawbacks at least to some extent and to provide good and long-term reliable imaging characteristics of the optical imaging device used in the exposure process.

  A further object of the present invention is to maintain the imaging accuracy of the optical imaging device used in the exposure process while reducing the work required for the optical imaging device.

  According to one aspect of the present invention, these problems are achieved based on the following technical teaching. This technical teaching reduces the overall work required for an optical imaging device while maintaining at least the imaging accuracy of the optical imaging device (stable and accurate global operation of the projection and substrate systems). Conventional support and measurement methods that seek to obtain a central support structure that forms a common measurement standard (for positioning purposes) can be realized if they are not required by the correction concept. According to this correction concept, an optical imaging device that generates an internal secondary vibration disturbance (that is, an oscillation disturbance other than the primary vibration disturbance generated from the mask support and the substrate support) is used for the support of the optical element of the optical projection system. Mechanically isolated from the source support).

  In the present invention, the component in the optical imaging apparatus means a component related to an optical imaging process performed by the optical imaging apparatus. Such a relationship can be direct (in the case of an active component of an optical system or a substrate system) or indirect (in the case of a fluid circulation system such as a cooling system or an immersion system of an optical imaging device). ) In contrast, in the present invention, a component outside the optical imaging apparatus means a component that is not involved in the optical imaging process performed by the optical imaging apparatus. As such an external component, specifically, there is a component adjacent to the optical imaging apparatus.

  This is because the support structure of the optical projection system (ie the support structure of the optical element) and the support structure of such a secondary source of vibration disturbance on the base structure, the support structure of the optical projection system and 2 This can be achieved by supporting the secondary vibration disturbance source so that it is not structurally adjacent to the support structure. Therefore, solid propagation of such secondary vibration disturbance sources is advantageously diverted through the base structure, thereby advantageously reducing the length of the structural path through which the secondary vibration disturbance is transmitted to the optical projection system. As a result, the attenuation of the secondary vibration disturbance is advantageously increased.

  Preferably, at least the support structure of the optical element is supported on the base structure via the vibration isolator, and vibration disturbance energy introduced into the support structure is reduced. More preferably, the support structure of the secondary vibration disturbance source is also supported on the base structure via a similar vibration isolator, thereby reducing the amount of vibration disturbance energy introduced into the base structure.

  In the present invention, it will be understood that the optical element unit is composed of only an optical element such as a mirror. However, such an optical element unit can further include components such as a holder for holding such an optical element.

  Thus, according to the first aspect of the present invention, there is provided an optical imaging apparatus comprising an optical projection system and a support structure system. The optical projection system is configured to transfer the pattern image of the mask supported by the mask support structure onto the substrate supported by the substrate support structure along the exposure path using exposure in the exposure process. And an optical element group. The mask support structure and the substrate support structure form a primary vibration source. The support structure system includes a base support structure, an optical element support structure, and at least one secondary vibration source support structure of a secondary vibration source other than the primary vibration source. The optical element support structure supports the optical element. The at least one secondary vibration source support structure supports a secondary vibration source, and this secondary vibration source is a secondary vibration disturbance source including solid propagation vibration energy, and is disposed in the optical imaging apparatus. The base support structure includes an optical element support structure and a secondary vibration source support structure, and a structural path of solid-propagating vibration energy from the secondary vibration source to the optical element support structure passes only through the base support unit. Support to exist.

  According to a second aspect of the invention, a method for supporting an optical projection system of an optical imaging device is provided. The optical projection system is configured to transfer the pattern image of the mask supported by the mask support structure onto the substrate supported by the substrate support structure along the exposure path using exposure in the exposure process. The mask support structure and the substrate support structure form a primary vibration source. The method comprises the steps of supporting an optical element on a base support structure via an optical element support structure and supporting a secondary vibration source on the base support structure via a secondary vibration source support structure. The secondary vibration source is a secondary vibration disturbance source including solid propagation vibration energy, and is disposed in the optical imaging apparatus. The optical element support structure and the secondary vibration source support structure support so that a structural path of solid propagation vibration energy from the secondary vibration source to the optical element support structure exists only through the base support unit.

  According to a third aspect of the present invention, there is provided an optical imaging apparatus comprising an optical projection system and a support structure system. The optical projection system is configured to transfer the pattern image of the mask supported by the mask support structure onto the substrate supported by the substrate support structure along the exposure path using exposure in the exposure process. Optical element group. The mask support structure and the substrate support structure form a primary vibration source. The support structure system includes a base support structure, an optical element support structure, and at least one secondary vibration source support structure. The optical element support structure supports the optical element, and at least one secondary vibration source support structure supports the secondary vibration source. The secondary vibration source is a secondary vibration disturbance source including solid propagation vibration energy. In an optical imaging device. The base support structure is configured such that the optical element support structure and the secondary vibration source support structure are mechanically isolated from the optical element support structure via at least one vibration isolator. To support.

  According to a fourth aspect of the present invention, a method for supporting an optical projection system of an optical imaging device is provided. The optical projection system is configured to transfer the pattern image of the mask supported by the mask support structure onto the substrate supported by the substrate support structure along the exposure path using exposure in the exposure process. The mask support structure and the substrate support structure form a primary vibration source. The method comprises the steps of supporting an optical element on a base support structure via an optical element support structure and supporting a secondary vibration source on the base support structure via a secondary vibration source support structure. The secondary vibration source is a secondary vibration disturbance source including solid propagation vibration energy, and is disposed in the optical imaging apparatus. The optical element support structure and the secondary vibration source support structure are mechanically isolated from the optical element support structure by the base support structure via at least one vibration isolator. So that it is supported.

According to a fifth aspect of the present invention, there is provided an optical imaging apparatus comprising an optical projection system and a support structure system. The optical projection system is configured to transfer the pattern image of the mask supported by the mask support structure onto the substrate supported by the substrate support structure along the exposure path using exposure in the exposure process. Optical element group. The support structure system includes a base support structure, an optical element support structure, and a projection system measurement support structure. The optical element support structure supports the optical element and is supported on the base support structure via the first vibration isolator. Projection system measures the support structure is configured to be attached to the optical element group, to capture the variables (variable Representative) representing a state of at least one optical element of its optical element group, at least one measuring device To support. The projection system measurement support structure is supported on the optical element support structure via the second vibration isolator.

According to a sixth aspect of the present invention, a method for supporting an optical projection system of an optical imaging device is provided. The optical projection system is configured to transfer the pattern image of the mask supported by the mask support structure onto the substrate supported by the substrate support structure along the exposure path using exposure in the exposure process. Optical element group. The method includes the steps of: supporting an optical element on a base support structure via an optical element support structure; and projecting at least one measurement device associated with the optical element group using a projection system measurement support structure. Supporting the element support structure, and supporting the projection system measurement support structure on the optical element support structure via the second vibration isolator. The at least one measuring device is configured to capture a variable representative representing a state of at least one optical element of the optical element group.

  Further aspects and embodiments of the invention will become apparent from the following description of preferred embodiments with reference to the dependent claims and the accompanying drawings. All combinations of the disclosed features are within the scope of the present invention, whether or not explicitly recited in the claims.

1 is a schematic illustration of a preferred embodiment of an optical imaging device according to the present invention, on which a preferred embodiment of the method according to the present invention can be implemented; 2 is a further schematic diagram of the optical imaging device of FIG. 1. FIG. 2 is a block diagram of a preferred embodiment of a method for supporting an optical projection system that can be performed with the optical imaging apparatus of FIG. 1. Fig. 4 is a schematic representation of a further preferred embodiment of an optical imaging device according to the present invention, on which a further preferred embodiment of the method according to the present invention can be carried out. Fig. 4 is a schematic representation of a further preferred embodiment of an optical imaging device according to the present invention, on which a further preferred embodiment of the method according to the present invention can be carried out.

(First embodiment)
In the following, a preferred first embodiment of an optical imaging device 101 according to the invention, in which a preferred embodiment of the method according to the invention can be carried out, is shown with reference to FIGS. In order to facilitate understanding of the following description, an xyz coordinate system is introduced into the figure. The z direction indicates the vertical direction (that is, the direction of gravity).

  FIG. 1 is a highly schematic non-scale diagram of an optical imaging device in the form of an optical exposure device 101 operating at a wavelength of 13 nm in the EUV range. The optical exposure apparatus 101 positions the pattern image formed on the mask 103.1 (located on the mask table 103.2 of the mask unit 103) on the substrate 104.1 (on the substrate table 104.2 of the substrate unit 104). An optical projection unit 102 adapted to transfer onto. For this reason, the optical exposure apparatus 101 has an illumination system 105 that illuminates the reflective mask 103.1 via an appropriate light guide system (not shown). The optical projection unit 102 receives the light reflected from the mask 103.1 (indicated by the principal ray 105.1) and transfers the pattern image formed on the mask 103.1 onto a substrate 104.1 such as a wafer. Project.

  Therefore, the optical projection unit 102 holds the optical element unit group 106 of the optical element units 106.1 to 106.6. The optical element unit group 106 is held in the optical element support structure 102.1. The optical element support structure 102.1 may be in the form of a housing structure for the optical projection unit 102, which will also be referred to as projection optical box structure (POB) 102.1 in the following. However, it will be appreciated that the optical element support structure need not necessarily be in the form of a complete or tight housing of the optical element unit group 106. Rather, in this example, a partially open structure may be used.

  The projection optical box structure 102.1 is supported by the base structure 107 so as to isolate vibrations. The base structure 107 is connected to the mask table 103.2 and the substrate table support device via the mask table support device 103.3. The substrate table 104.2 is also supported via 104.3. Since the mask table 103.2, the mask table support device 103.3, the substrate table 104.2 and the substrate table support device 104.3 form or include a primary vibration disturbance source, the mask table support device 103.3 and the substrate The table support devices 104.3 each form a primary vibration source support structure, which together form a primary vibration source in the present invention.

  It will be appreciated that the projection optical box structure 102.1 is supported in series via a plurality of vibration isolation devices and at least one intermediate support structure unit to achieve good vibration isolation. In general, these vibration isolators have different separation frequencies as will be described in detail below, and can achieve good vibration isolation over a wide frequency range.

  The optical element unit group 106 includes a total of six optical element units, that is, a first optical element unit 106.1, a second optical element unit 106.2, a third optical element unit 106.3, a fourth optical element unit 106. 4. It has the 5th optical element unit 106.5 and the 6th optical element unit 106.6. In the present embodiment, each of the optical element units 106.1 to 106.6 includes a mirror-like optical element. The sixth optical element 106.6 forms a first optical element subgroup 106.8, and the first to fifth optical elements 106.1 to 106.5 form a second optical element subgroup 106.7.

  However, in other embodiments of the invention, the optical element units each hold, for example, an aperture stop, a holder that holds the optical element and ultimately forms an interface of the support unit that connects the optical element unit to the support structure. It will be appreciated that additional components such as retainers may be included (in addition to the optical element itself).

  It will be further appreciated that other numbers of optical element units may be used in other embodiments of the invention. Preferably, 4 to 8 optical element units are provided.

  Each of the mirrors 106.1 to 106.6 is supported by an associated support device 108.1 to 108.6 on a support structure formed by the projection optical box structure 102.1. Each of the support devices 108.1 to 108.6 is formed as an active device such that each of the mirrors 106.1 to 106.6 is actively supported with a defined control bandwidth.

  In this example, the optical element unit 106.6 is a large and heavy component forming the first optical element unit of the optical element unit group 106, and the other optical element units 106.1 to 106.5 are optical elements. A plurality of second optical element units of the unit group 106 are formed. The first optical element unit 106.6 is actively supported in the first low control bandwidth, and the second optical element units 106.1 to 106.5 are actively supported in the second control bandwidth. A constant spatial relationship of each of the optical element units 106.1 to 106.5 with respect to the first optical element unit 106.6 is substantially maintained.

  In this example, a similar active support concept is selected for the mask table support device 103.3 and the substrate table support device 104.3, which are also actively supported in the third and fourth control bandwidths respectively. A certain spatial relationship between the table 103.2 and the substrate table 104.2 with respect to the first optical element unit 106.6 is substantially maintained. However, in other embodiments of the invention, another support concept may be selected for the mask table and / or the substrate table.

  In the further details described below, control of the active support devices 108.1 to 108.6, 103.3 and 104.3 is performed by the control unit 109 as a function of the signal of the measuring device 110. Adjustment control of components related to the imaging process is performed as follows.

  In order to provide active low-band support of the first optical element unit 106.6, the first support device 108.6 of the first optical element unit 106.6 is switched to a frequency of 5 Hz to 100 Hz, preferably 40 Hz to 100 Hz. Configure and control the first optical element unit 106.6 to adjust the components of the measuring device 110 with one adjustment control bandwidth.

  Furthermore, in order to provide active support of the second optical element units 106.1 to 106.5, the mask table 103.2 and the substrate table 104.2, respectively, the second optical element units 106.1 to 106.5 Each of the second support devices 108.1 to 108.5 and the mask table support device 103.3 and the substrate table support device 104.3 are respectively second, third and second of 5 Hz to 400 Hz, preferably 200 Hz to 300 Hz. The optical element units 106.1 to 106.5, the mask table 103.2, and the substrate table 104.2 are respectively adjusted and controlled with four adjustment control bandwidths. It will be appreciated that in certain embodiments of the invention, the second control bandwidth is different for the second support devices 108.1-108.5.

  This embodiment follows a modified support method compared to the conventional design, which is most severe in reaching the high control bandwidth typically required in EUV microlithography. The large and heavy first optical element unit 106.6, which is a major problem, is active under the control of a low bandwidth (in which this optical element unit 106.6 can be easily controlled). The other components related to the exposure process, that is, the second optical element units 106.1 to 106.5, the mask table 103.2, and the substrate table 104.2 are in relation to the first optical element unit 106.6. , And therefore, are controlled so as to maintain a mutually stable, sufficiently stable and accurate spatial relationship.

  Thus, in this example, despite the fact that all components involved in the imaging process (ie mirrors 106.1 to 106.6, mask 103.1 and substrate 104.1) are actively controlled, the first The greatly relaxed requirement for control bandwidth adjustment of one optical element unit 106.6 is more valuable than the increased cost for active support of individual components. Specifically, adjustment control of components with a large optical footprint, such as a sixth mirror 106.6 (up to 1.5 m × 1.5 m optical footprint, mass up to 350 kg), typically from 200 Hz Use a regulated control bandwidth of 300 Hz and consider this necessary (control bandwidth that is rarely achieved for such large optical footprint components due to the low resonant frequency)) compared to conventional systems Significantly easier.

  According to this support method, one component of the optical system (typically large and / or heavy of these components) is used as an inertial reference and this is used as one of the other components or Multiple (up to all other components) can be the basis for measurement and ultimately adjustment. In this example, a sixth optical mirror 106.6 with a large optical footprint is used as the inertial reference, which, as will be explained in more detail below, all further components 106.1 to 106 involved in the imaging process. .5, 103.1 and 104.1. However, it will be appreciated that in other embodiments of the present invention, any suitable component other than the last optical element unit that was exposed may be used as this inertia criterion, depending on the design of the optical system.

  The pattern image formed on the mask 103.1 is usually reduced in size and transferred to several target areas on the substrate 104.1. The pattern image formed on the mask 103.1 can be transferred to each target area on the substrate 104.1 by two different methods depending on the design of the optical exposure apparatus 101. When the optical exposure apparatus 101 is designed as a so-called wafer stepper apparatus, the entire pattern image is irradiated on the entire pattern formed on the mask 103.1, so that each of the patterns on the substrate 104.1 in one step. Transferred to the target area. If the optical exposure apparatus 101 is designed as a so-called step-and-scan apparatus, the pattern image scans gradually the mask table 103.2 and thus the pattern formed on the mask 103.1 under the projection beam, On the other hand, the substrate table 104.2, and thus the corresponding scanning operation of the substrate 104.1, is simultaneously transferred to the individual target areas of the substrate 104.1.

  In either case, the spatial relationship between the components involved in the exposure process (ie, the optical element unit group 106, ie, the mirrors 106.1 to 106.6), and the constant space for the mask 103.1 and the substrate 104.1. The relationship must be maintained within predetermined limits to obtain high quality imaging imaging.

  During operation of the optical exposure apparatus 101, the position between the mirrors 106.1 to 106.6 and relative to the mask 103.1 and the substrate 104.1 will vary depending on both intrinsic and extrinsic disturbances introduced into the system. . Such disturbances occur, for example, within the system itself, but are introduced through the periphery of the system, for example the base support structure 107 (which itself is supported by the grounding structure 111), for example vibrations It may be a form of mechanical disturbance. These may be thermally induced disturbances, for example changes due to thermal expansion of system components.

  In order to maintain the above-mentioned predetermined limitations on the spatial relationship between mirrors 106.1 to 106.6 and to mask 103.1 and substrate 104.1, each of mirrors 106.1 to 106.6 is supported. Actively placed in space via devices 108.1 to 108.6, respectively. Similarly, the mask table 103.2 and the substrate table 104.2 are actively arranged in space via support devices 103.1 and 104.3, respectively.

  In the following, the control concept of the spatial adjustment of the components 106.1 to 106.6, 103.1 and 104.1 involved in the imaging process will be described with reference to FIGS. As mentioned above, the control of the adjustment of the components 106.1 to 106.6, 103.1 and 104.1 is supported by the support device in the specific adjustment control bandwidth outlined above in a total of six degrees of freedom. Connected to each of 108.1-108.6, 103.3 and 104.3 (indicated by solid and dotted lines in the control unit 109 and the respective support devices of FIG. 1) and provide control signals corresponding to each. This is done using the control unit 109.

  The control unit 109 generates the control signal according to the measurement signal of the measurement device 110, and the measurement device 110 determines the position and orientation of each of the components 106.1 to 106.6, 103.1, and 104.1. Capture with a total of six degrees of freedom (shown in dotted lines in FIGS. 1 and 2). As described above, the measurement device 110 uses the sixth mirror 106.6 having a large optical footprint as a reference for all other components 106.1 to 106.5, 103.1 and 104.1 involved in the imaging process. It is used as an inertia reference (ie, a reference optical element unit). As can be seen from FIG. 1, in the optical path, the sixth mirror 106.6 is the last to which the exposure light 105.1 hits last when the pattern image formed on the mask 103.1 is transferred onto the substrate 104.1. It is a mirror unit.

  For this reason, the measuring apparatus uses a measuring unit 110.1 having a plurality of measuring devices 110.2, 110.3 and 110.4 mechanically connected to the projection system measuring support structure 112.1. The system metrology support structure 112.1 is similar to the measurement device 110.5 mechanically connected to the substrate system metrology support structure 112.2, as shown in FIG. 1 (highly schematic) and FIG. Supported by the projection optical box structure 102.1. In this embodiment, each measurement device 110.2, 110.3, 110.4 and 110.5 is connected to the projection system measurement support structure 112.1 or the substrate system measurement support structure 112.2, respectively. A reference element 110.6 mechanically directly connected to the individual mirrors 106.1 to 106.6, the mask table support device 103.3, the substrate measurement support structure 112.2 and the substrate table support device 104.3; It has a cooperating sensor head.

  The term “mechanically directly connected” refers to a short distance between parts in the present invention that allows the position of one part to be reliably determined by measuring the position of the other part. It should be understood as a direct connection between two parts, including (if any). Specifically, this term means that there are no other intervening parts that cause uncertainty in positioning, for example due to thermal or vibration effects. In certain embodiments of the invention, the reference element is not a separate component connected to the mirror, but is formed directly or integrally on the surface of the mirror, for example as a diffraction grating formed in a separate process during mirror manufacture. It will be understood that

  In this embodiment, the measuring devices 110.2, 110.3, 110.4 and 110.5 operate according to the principle of the encoder, i.e. the sensor head emits a sensor beam towards the construction surface and the structure of the reference element. The reading light beam reflected from the surface is detected. The structural surface may be, for example, a diffraction grating including a series of parallel lines (one-dimensional diffraction grating) or mutually inclined grating lines (two-dimensional diffraction grating). The change in position is basically captured by counting the passing lines of the sensor beam resulting from the signal realized via the reading beam.

  However, in other embodiments of the invention, apart from the principle of the encoder, any other type of non-contact measurement principle (eg interferometry principle, dose measurement principle, inductive measurement principle, etc.) alone or arbitrarily Can be used in combination. However, it will be appreciated that in any other embodiment of the present invention, any suitable contact-based metrology device may be used. As a contact-based operation principle, for example, a magnetostriction or electrostriction operation principle may be used. Specifically, the operation principle may be selected according to accuracy requirements.

  The measurement device 110.2 associated with the sixth mirror 106.6 (in all six degrees of freedom) is the first between the projection system measurement support structure 112 and the sixth mirror 106.6 forming the inertial reference. Capture spatial relationships. Furthermore, the measuring devices 110.2, 110.3, 110.4 and 110.5 associated with the other components 106.1 to 106.5, 103.1 and 104.1 involved in the imaging process are (all 6 Captures the spatial relationship between the projection system metrology support structure 112.2 and the accompanying components 106.1-106.5, 103.1 and 104.1).

  In the case of the substrate 104.1, this is a measurement device 110.4 mechanically connected to the projection system measurement support structure 112.1 (reference directly mechanically connected to the substrate system measurement support structure 112.2). Substrate-based measurement device 110.5 (in combination with element 110.6) and mechanically connected to substrate-based measurement support structure 112.2 (reference directly mechanically connected to substrate table support device 104.3) In combination with element 110.6) (see FIG. 2).

  Finally, the measuring device 110 uses the first spatial relationship and the second spatial relationship to provide a sixth mirror 106.6 and individual further components 106.1 to 106.5, 103.1 and 104.1. Determine the spatial relationship between. Corresponding measurement signals are then provided to the control unit 109, and the control unit 109 responds to these measurement signals with control signals corresponding to the respective signal support devices 108.1 to 108.6, 103.3 and 104.3. Is generated.

  In other embodiments of the present invention, the reference optical element (eg, sixth mirror) and each additional component involved in the imaging process (eg, mirrors 106.1-106.5, mask 103.1 and substrate 104.). It will be appreciated that a direct measurement of the spatial relationship between any one of 1) can also be provided. Any combination of such direct or indirect measurements can be used depending on the spatial boundary conditions.

  In the present embodiment, in response to the measurement signal representing the first spatial relationship between the measurement structure and the sixth mirror 106.6, the control unit 109 controls the sixth mirror 106.6 (that is, the first mirror in the present invention). The control signal corresponding to the first support device 108.6 of the optical element unit) is generated, and the above-mentioned first adjustment control bandwidth (5 Hz) for the projection system measurement support structure 112.1 of the measurement unit 110.1. The sixth mirror 106.6 is adjusted at ˜100 Hz, preferably in the range of 40 Hz˜100 Hz.

  This important low bandwidth control of the first optical element unit 106.6 provides low bandwidth drift control of the first optical element unit 106.6 with respect to the measurement structure of the measurement unit 110.1. In other words, the first optical element unit 106.6 thereby captures the spatial relationship between the first optical element unit 106.6 and the projection system measurement support structure 112.1 of the measurement unit 110.1. The low frequency operation corresponding to the measurement unit 110.1 can be followed. By this means, excessive relative movement between the first optical element unit 106.6 exceeding the capture range in the capture device of the measurement unit 110.1 and the projection system measurement support structure 112.1 of the measurement unit 110.1. In other words, the sensor range problem can be avoided in an advantageous manner.

  It will be appreciated that the spatial relationship between the substrate table 104.2 and the substrate 104.1 is known, for example, by a measurement operation immediately before the exposure process. The same applies to the spatial relationship between the mask table 103.2 and the mask 103.1. Thus, the individual reference elements 110.6 connected to the mask table 103.2 and the substrate table 104.2, respectively, also have their respective spaces between the reference mirror 106.6 and the mask 103.1 and the substrate 104.1. Allows capture of relationships.

  As a result, regardless of the fact that all components involved in the exposure process typically have to be actively controlled, the most important requirement for the control bandwidth of the first optical element unit 106.6 is high Is greatly relaxed in an advantageous manner. This positive effect is generally more valuable than the increased cost for active support of all components.

  Thus, for example, compared to conventional systems that typically use an adjustment control bandwidth of 200 Hz to 300 Hz and are considered necessary for individual optical element units, the present invention provides a considerably lower adjustment control bandwidth, e.g. 5 Hz to 100 Hz, preferably 40 Hz to 100 Hz is used for the important first optical element unit 106.6 and all other components involved in the imaging process (ie optical element units 106.1 to 106.5, mask) The unit 103.1 and the substrate unit 104.1) are easily controlled with a conventionally desired high adjustment control bandwidth, for example 200 Hz to 400 Hz, suitable for the inertial reference formed by the first optical element unit 106.6 Alignment can be provided.

  The above (indirect) measurement concept is that the instantaneous rigid body position and orientation in the projection system measurement support structure of the measurement unit 110.1, specifically the vibration introduced into the measurement structure of the measurement unit 110.1. It will be further appreciated that the disturbance has the advantage that it is essentially irrelevant as long as the projection system metrology support structure 112.1 is sufficiently stiff enough to largely avoid dynamic deformation of the metrology structure. Specifically, the work for stabilizing the position and / or orientation of the projection system measurement support structure in the space can be reduced. However, nonetheless, typically, the projection system measurement support structure itself can also be supported by the projection optical box structure 102.1 to block vibrations, as in this embodiment.

  As described above, in order to reduce the amount of vibration disturbance energy introduced into the projection optical box structure 102.1 (and in the projection system) and finally reduce the adverse effects of such vibration disturbance energy, the present invention is used. According to the above, the projection optical box structure 102.1 is supported on the base support structure 107 via the first vibration isolation device 113, and the substrate system measurement support structure 112.2 is supported via the second vibration isolation device 114. Thus, a support concept of supporting the base support structure 107 is provided.

  By separately supporting the projection optical box structure 102.1 and the substrate system measurement support structure 112.2 in this manner, the optical elements 106.1 to 106.6 are supported by the substrate system measurement support structure 112.2. From the support structure 112.2 of the secondary internal vibration disturbance source such as a cooling circuit (not shown in detail) such as a secondary vibration disturbance generated by the turbulent flow to the refrigerant and releasing the secondary vibration disturbance energy. Shut off mechanically.

  This mechanical shut-off supports the projection optical box structure 102.1 and the substrate system measurement support structure 112.2 via the vibration isolators 113 and 114, respectively, and the projection optical box structure 102.1 and the substrate. This is performed so that the system measurement support structure 112.2 is not in direct structural contact. In other words, the projection optical box structure 102.1 and the substrate-based measurement support structure 112.2 are separated from each other by the solid propagation vibration energy from the substrate-based measurement support structure 112.2 to the projection optical box structure 102.1. Supports that a structural path exists only through the base support structure 107.

  Therefore, on the one hand, the structurally propagated secondary vibration energy is diverted through the base support structure 107 in an advantageous manner, so that the secondary vibration disturbance must travel to reach the optical projection system. The length of the path is advantageously increased, so that the attenuation of secondary vibration disturbances is advantageously increased.

  On the other hand, the vibration isolator 114 further reduces solid propagation secondary vibration disturbance energy introduced into the base support structure 107, and the vibration isolator 113 moves from the base support structure 107 to the projection optical box structure 102.1. Furthermore, the solid propagation vibration disturbance energy amount generated from the substrate system measurement support structure 112.2 is further reduced.

  Preferably, a mask table support device that is also supported on the base support structure 107 via support of a primary source of vibration disturbances, such as the substrate table support device 104.3, and a corresponding anti-vibration device (not shown in detail). It will be appreciated that a similar approach is selected for supporting 103.3.

  As can be seen from FIG. 2, a similar support method is selected for the internal cooling device 115 of the optical projection unit 102 which also forms an internal secondary vibration disturbance source in the present invention. The internal cooling device 115 is a sleeve surrounding the optical elements 106.1 to 106.6. The internal cooling device 115 is not in direct physical or structural contact with the optical elements 106.1 to 106.6, their associated support devices 108.1 to 108.6 and the projection optical box structure 102.1. Designed. The internal cooling device 115 is in direct physical or structural contact only with the base structure 107 via the internal cooling device support structure 115.1. It will be appreciated that the internal cooling device support structure 115.1 can also be supported on the base support structure 107 via additional vibration isolation devices (not shown in detail).

  As can be seen from FIG. 2, in order to avoid such direct physical or structural contact, the internal cooling device 115 has a corresponding opening or recess through which it can contact the internal cooling device 115. The supporting devices 108.1 to 108.6 can be reached respectively. Furthermore, the internal cooling device support structure 115.1 passes through a corresponding opening or recess 102.2 provided in the projection optical box structure 102.1 and arrives without physical contact with the latter.

  One or more additional cooling devices, in particular an external cooling device surrounding the projection optics box structure 102.1, can be produced in a manner similar to the internal cooling device 115 (as indicated by the dotted outline 116 in FIG. 2). Ie, without direct physical or structural contact with the optical elements 106.1 to 106.6, their associated support devices 108.1 to 108.6 and the projection optical box structure 102.1) It will be understood that it can be provided and supported on the support structure 107.

  The first anti-vibration device 113 has a first anti-vibration resonance frequency of about 0.5 Hz, and thus an advantageous low-frequency anti-vibration is realized at this frequency. In another preferred embodiment of the present invention, the first vibration isolation resonance frequency is selected to be in the range of 0.05 Hz to 8.0 Hz, 0.1 Hz to 1.0 Hz, or 0.2 Hz to 0.6 Hz. It will be understood that you can. In any of these cases, advantageous low-frequency vibration isolation is realized.

  In this example, the same applies to the second vibration isolation resonance frequency of the second vibration isolation device 114, which is also about 0.5 Hz. Again, the second anti-vibration resonance frequency can be selected to be 0.05 Hz to 8.0 Hz, 0.2 Hz to 1.0 Hz, or 0.2 Hz to 0.6 Hz. In any of these cases, advantageous low-frequency vibration isolation is realized.

  In order to further improve the vibration behavior of the projection optical box structure 102.1, each of the support devices 108.1 to 108.5 of the second subgroup 106.7 in the optical element is connected via a connection device 117.2. It has a vibration balance mass unit 117.1 connected to the projection optics box structure 102.1.

  Preferably, each vibrationally balanced mass unit 117.1 and its connecting device 117.2 is an actuator device (for each of the support devices 108.1 to 108.5) that drives the optical elements 106.1 to 106.5, respectively. Accompanying it, it is configured to provide at least a partial reaction force that counteracts the driving force that drives the optical elements 106.1 to 106.5, respectively. In other words, the vibration balance mass unit 117.1 forms an actuator reaction force canceling unit.

  This vibration balance system formed by the vibration balance mass unit 117.1 and the connecting device 117.2 is in an advantageous way, by modifying the vibration behavior of the vibration balance system and the vibration behavior in the projection optical box structure 102.1. Provides an advantageous vibration balance and results in an overall reduction in amplitude seen at the level of optical elements 106.1 to 106.6.

  The vibration balance mass unit 117.1 and the connecting device 117.2 define a balance resonance frequency of about 25 Hz in this embodiment. However, it will be appreciated that in other embodiments of the invention, a balanced resonant frequency in the range of 1 Hz to 40 Hz, 5 Hz to 40 Hz, or 15 Hz to 25 Hz can be selected depending on the vibrational behavior in the projection optical box structure.

  In this embodiment, such a vibration balance mass unit is not attached to the first optical element 106.6. However, in other embodiments of the present invention, a structure is selected that associates such a vibrationally balanced mass unit with the first optical element 106.6, as shown by the dotted outline 117.3 in FIG. You can also.

  Furthermore, in this embodiment, each vibrationally balanced mass unit 117.1 is kinematically connected between the projection optical box structure 102.2 and the associated optical elements 106.1 to 106.5 by the connecting device 117.2. It has a plurality of balanced mass elements held by connecting device 117.2 to be arranged in series.

  The number of balanced mass elements is preferably selected according to the vibrational behavior of the support structure of each optical element. In this example, six balanced mass elements are arranged on the outer periphery of each of the optical elements 106.1 to 106.5. It will be appreciated that in any other embodiment of the present invention, any suitable varying number of balanced mass elements may be provided.

  However, in other embodiments of the present invention, one balanced mass element per optical element may be sufficient. Further, depending on the vibration behavior of the support structure of the optical element, it is not always necessary to provide such a vibration balance mass unit for all optical elements, in particular for all optical elements of the first subgroup 106.7. .

  In this example, in order to advantageously influence the vibration behavior of the projection optical box structure 102.1, each connecting device 117.2 has a first damping ratio of about 1% and an associated vibration balance mass unit 117.1. It is configured so as to give vibration damping. It will be appreciated that a different first damping ratio may be selected depending on the vibration behavior in the support structure of the optical element. Preferably, the first damping ratio is selected from the following ranges: 0.2% -15%, 0.2% -5% and 1.0% -3.0%.

  As can be further seen from FIG. 2, the projection system measurement support structure 112.1 is placed on the projection optical box structure 102.1 (and consequently the base support structure 107) via the third vibration isolator 118. Supported. The third vibration isolator 118 has a third vibration isolation resonance frequency of about 3 Hz.

  It will be appreciated that in other preferred embodiments of the present invention, the third anti-vibration resonant frequency can also be selected to be a resonant frequency in the range of 1 Hz to 30 Hz, 2 Hz to 10 Hz, or 3 Hz to 8 Hz. The appropriate third vibration-proof resonance frequency can be specifically selected according to the vibration behavior of the projection system measurement support structure 112.1.

  In this example, the third anti-vibration resonant frequency and the balanced resonant frequency are tuned to each other as long as they are separated by a frequency gap. Thus, an appropriate range of frequency gaps is advantageous to avoid interference effects and ultimately to the problem of vibration system instability.

  The width of the frequency gap is within the projection optical box structure 102.1, the optical elements 106.1 to 106.6, the balance mass unit 117.1, the connection device 117.2 and the projection system measurement support structure 112.1. It will be appreciated that the choice is made according to at least one vibrational behavior. Preferably, the frequency gap is selected from the range of 1 Hz to 40 Hz, 10 Hz to 25 Hz, or 100% to 400% of the third vibration isolation resonance frequency.

  Furthermore, in this example, in order to have an advantageous influence on the vibration behavior of the projection system measurement support structure 112.1, the third vibration isolator 118 is set to a projection system measurement support structure 112 with a second damping ratio of about 20%. Configure to provide vibration damping of .1.

  It will be appreciated that another second damping ratio may be selected depending on the vibrational behavior of the projection system measurement support structure 112.1. Preferably, the second damping ratio is selected from the following ranges: 5% -60%, 10% -30% and 20% -25%.

  This two-stage anti-vibration support of the projection system measurement support structure 112.1 (via the anti-vibration devices 118 and 113) on the base structure 107 provides a primary source of vibration disturbance (substrate table support device 104.3). And support of the mask table support device 103.3) and secondary sources of vibration disturbance (substrate-based measurement support structure 112.2 and internal cooling device 115 of the optical projection unit 102), often at least two stages It will be further understood that achieves three stages of vibration isolation.

  In other words, on the one hand, the solid propagating primary and secondary vibrational disturbance energy is advantageously transferred in an advantageous manner before reaching the projection system measurement support structure 112.1. 102.1, which advantageously increases the length of the structural path that the primary and secondary vibration disturbances must travel to reach the projection system metrology support structure 112.1; As a result, the attenuation of the primary and secondary vibration disturbances is advantageously increased.

  This ultimately leads to a particularly high vibration stabilization of the projection system measurement support structure 112.1, which is very advantageous for the control performance of the system.

  It will be appreciated that any desired and appropriate material can be selected for the individual support structures. For example, metals such as aluminum can be used for individual support structures, specifically, support structures that are relatively light and require relatively high stiffness. It will be appreciated that the material of the support structure is preferably selected depending on the type and function of the support structure.

  Specifically, the projection optical box structure 102.1 includes steel, aluminum (Al), titanium (Ti), a so-called Invar alloy (ie, an iron nickel alloy containing 33% to 36% nickel, Fe64Ni36) and A suitable tungsten alloy (for example a composite material such as DENSIMET®, INERMET®), ie a heavy metal of NiFe or NiCu binder phase with a tungsten content of 90% or more, is preferably used.

Furthermore, the projection system measurement support structure 112.1 includes silicon-impregnated silicon carbide (SiSiC), silicon carbide (SiC), silicon (Si), carbon fiber reinforced silicon carbide composite (C / CSiC), aluminum oxide ( Al ₂ O ₃ ), Zerodur (Zerodur (registered trademark)) (lithium aluminosilicate glass-ceramic), ULE (registered trademark) glass (titanium oxide-silicon glass), quartz, cordierite (magnesium iron aluminum cyclosilicate mineral ) Or other ceramic materials having a low coefficient of thermal expansion and a high modulus of elasticity can also be used advantageously.

  In this example, the projection optical box structure 102.1 is made of steel as a first material having a first stiffness. This measure increases the weight by a factor of 3 compared to a conventional support structure made, for example, of aluminum, which is generally not preferred in conventional systems. However, due to the non-conventional support method according to the invention, an increase in the weight of the projection optical box structure 102.1 is advantageous in terms of vibration behavior.

  Further, the projection metrology support structure 112.1 is made of a second material having a second stiffness that is greater than the stiffness of the steel material of the projection optical box structure 102.1. This high rigidity of the projection measurement support structure 112.1 is advantageous as described above.

  It will be understood that the microlithographic apparatus 101 of this embodiment can obtain a line-of-sight accuracy of 100 pm or less in all relevant degrees of freedom, typically in the x and y directions. In general, when the third resonance frequency of the third vibration isolator 118 is lowered, better line-of-sight accuracy can be provided.

  In the optical imaging apparatus 101 of FIGS. 1 and 2, a method for transferring a pattern image onto a substrate is described with reference to a preferred embodiment of a method for supporting components of an optical projection unit according to the present invention and FIGS. Can be implemented using the method described below to capture the spatial relationship between the optical element unit and the reference unit.

  In the transfer step of the method, the pattern image formed on the mask 103.1 is transferred onto the substrate 104.1 using the optical projection unit 102 of the optical imaging device 101.

  For this reason, in the capture step 119.3 of the transfer step, the spatial relationship between the components 106.1 to 106.6, 103.1 and 104.1 involved in the imaging process is Capture using a method that captures the spatial relationship between the unit and the reference unit.

  In the control step 119.4 of the transfer step, the position and / or orientation of the substrate table 104.2, the mask table 103.2 and the other mirrors 106.1 to 106.5 with respect to the sixth mirror 106.6, and the sixth mirror The position and / or orientation of the measurement unit 110.1 of 106.6 relative to the measurement structure is controlled according to the spatial relationship previously captured in the capture step 119.3, as outlined above. In the exposure step, immediately after the control step 119.4 or finally overlapped with this step, the pattern image formed on the mask 103.1 is transferred onto the substrate 104.1 using the optical imaging device 1. To expose.

  In some steps of the control step 119.4, the space between the mask unit 103 having the mask 103.1 and the substrate unit 104 having the substrate 104.1 is adjusted. It will be understood that the mask 103.1 and the substrate 104.1 can be inserted into the mask unit 103 and the substrate unit 104, respectively, at a later time point before the actual position acquisition or at a later time point before the exposure step.

  According to a preferred embodiment of the method for supporting the components of the optical projection unit according to the invention, in step 119.1 the components of the optical projection unit 102 are first prepared as outlined above, step 119.2. In support. Therefore, in step 119.2, the mirrors 106.1 to 106.6 of the optical projection unit 102 are supported and installed in the optical projection box structure 102.1 of the optical projection unit 102. In step 119.4, the mirrors 106.1 to 106.6 are then actively supported in the projection optical box structure 102.1, respectively, with their respective control bandwidths, as described above with respect to FIGS. Provide a simple configuration.

  The capture step 119.3 uses a measuring device 110 (provided in advance in a configuration as described above with respect to FIGS. 1 and 2). It will be appreciated that the reference elements can be provided earlier at an earlier time with the individual mirrors 106.1 to 106.6 on which they are placed. However, in other embodiments of the present invention, a reference element may be provided along with other components of the measurement device 110 at a later time prior to the actual position acquisition step.

  In the capture step 119.3, the sixth mirror 106.6 as the center inertia reference of the optical imaging device 101, the substrate table 104.2, the mask table 103.2 and the other mirrors 106.1 to 106.5 The actual spatial relationship between is then captured as outlined above.

  The actual spatial relationship between the sixth mirror 106.6 and the substrate table 104.2, mask table 103.2 and other mirrors 106.1 to 106.5 and the measurement unit 110.6 of the sixth mirror 106.6. The actual spatial relationship for one metrology structure can be captured continuously throughout the exposure process. In control step 119.4, the latest result of this continuous capture process is retrieved and used.

  As described above, in the control step 119.4, the positions of the substrate table 104.2, the mask table 103.2 and the mirrors 106.1 to 106.6 are controlled according to this previously captured spatial relationship, and in the exposure step. The pattern image formed on the mask 103.1 is exposed on the substrate 104.1.

(Second Embodiment)
In the following, a second preferred embodiment of the optical imaging device 201 according to the invention, in which a preferred embodiment of the method according to the invention can be implemented, will be described with reference to FIG. Since the optical imaging apparatus 201 substantially corresponds to the optical imaging apparatus 101 in its basic design and function, the differences are mainly described here. Specifically, the same reference number is assigned to the same component, and the same reference number plus 100 is displayed for similar components. Explicit reference is made to the description given above in the first embodiment for these components, except where explicitly deviating from the description below.

  The main difference between the optical imaging device 201 and the optical imaging device 101 is the design of the projection optical box structure 202.1. It will be understood that the projection optical box structure 202.1 is interchangeable with the projection optical box structure 102.1 of the optical imaging device 101.

  In the described embodiment, the projection optical box structure 202.1 includes a first projection optical box substructure 202.3 that supports the second projection optical box substructure 202.4 and a projection system measurement support structure 112. .2 is a two-part design. The second projection optical box substructure 202.4 is connected to the support devices 208.1 to 208.6 of the optical elements 106.1 to 106.6. The second projection optical box substructure 202.4 thus supports the optical elements 106.1 to 106.6.

  The second projection optical box substructure 202.4 is connected to the first projection optical box substructure via a fourth vibration isolation device 219 having a fourth vibration isolation resonance frequency in the vibration isolation resonance frequency range of 20 Hz to 30 Hz. Supported by 202.3. It will be appreciated that in other embodiments of the present invention, the fourth anti-vibration resonant frequency can be selected from the range of 1 Hz to 30 Hz, 1 Hz to 8 Hz, 1 Hz to 40 Hz, or 25 Hz to 30 Hz.

  This two-stage anti-vibration support of the second projection optical box sub-structure 202.4 (via the anti-vibration devices 219 and 113) on the base structure 107 provides a primary source of vibration disturbance (substrate table support device 104). .3 and mask table support device 103.3) and secondary sources of vibration disturbances (such as the substrate-based measurement support structure 112.2 and the internal cooling device 115 of the optical projection unit 102), at least two stages; It will be further appreciated that in many cases three levels of vibration isolation are achieved.

  In other words, the solid propagating primary and secondary vibration disturbance energy is advantageously transferred in an advantageous manner before reaching the second projection optical box substructure 202.4. Advantageously bypasses the length of the structural path that the primary and secondary vibration disturbances must travel to reach the second projection optics box substructure 202.4. As a result, the damping of the primary and secondary vibration disturbances is advantageously increased.

  This ultimately results in a particularly high vibration stability of the second projection optical box substructure 202.4 and thus the optical elements 106.1 to 106.6, which is also very advantageous for the control performance of the system.

  Other anti-vibration devices 113, 114, and 118 are the same as those in the first embodiment. Therefore, the above description regarding the first embodiment also applies here.

  A further difference from the first embodiment of the present description is that the vibration balancing mass unit is not provided in the support devices 208.1 to 208.5 of the second subgroup 106.7 in the optical element. However, any desired number of such vibration balancing mass units may be provided on the desired element of the optical elements 106.1 to 106.6, as indicated by the dotted outline in FIG.

  It will be understood that in the microlithography apparatus 201 of this embodiment, it is possible to obtain a line-of-sight accuracy of 100 pm or less in all related degrees of freedom, typically in the x and y directions. In general, when the third resonance frequency of the third vibration isolator 118 is lowered, better line-of-sight accuracy is provided.

  Again, it will be understood that any desired and appropriate material can be selected for the individual support structures. For example, metals such as aluminum can be used for individual support structures, particularly for support structures that are relatively light and require relatively high stiffness. The materials described in the first embodiment can also be selected depending on the type and / or function of the particular support structure. In this example, the sub-structures of the projection optical box structure 202.1 are both made of aluminum.

(Third embodiment)
In the following, a third preferred embodiment of the optical imaging device 301 according to the invention, in which a preferred embodiment of the method according to the invention can be implemented, will be described with reference to FIG. Since the optical imaging apparatus 301 substantially corresponds to the optical imaging apparatus 101 in its basic design and function, the differences will mainly be described here. Specifically, the same reference number is assigned to the same component, and the same reference number plus 200 is displayed for similar components. Explicit reference is made to the description given above in the first embodiment for these components, except where explicitly deviating from the description below.

  The main difference between the optical imaging device 301 and the optical imaging device 101 is again the design of the projection optical box structure 302.1. It will be understood that the projection optical box structure 302.1 is interchangeable with the projection optical box structure 102.1 of the optical imaging device 101.

  In the described embodiment, the projection optics box structure 302.1 supports a second projection optics box substructure 302.4 that simultaneously forms a projection system metrology support structure 312 to achieve a very compact design. It has a two-part design formed by the first projection optical box substructure 302.3. The second projection optical box substructure 302.4 is connected to the support devices 308.1 to 308.6 of the optical elements 106.1 to 106.6. The second projection optical box substructure 302.4 thus supports the optical elements 106.1 to 106.6.

  The second projection optical box sub-structure 302.4 is connected to the first projection optical box sub-structure 302.3 via a third vibration isolation device 318 having a third vibration isolation resonance frequency of about 3 Hz. Supported on top. It will be appreciated that in other embodiments of the present invention, the third anti-vibration resonant frequency can be selected from the ranges set forth above with respect to the first embodiment.

  Other anti-vibration devices 113 and 114 are the same as those in the first embodiment. Therefore, the above description in the first embodiment is applied.

  A further difference of this embodiment with respect to the first embodiment is that all support devices 308.1-308.6 are connected to the vibrations connected to the projection optics box substructure 302.4 via the connection device 317.2. The balance mass unit 317.1 is provided.

  Each vibration balance mass unit 317.1 and its associated connection device 317.2 is defined in this embodiment to have a balance resonance frequency of about 15 Hz. However, in other embodiments of the present invention, a balanced resonant frequency in the range of 1 Hz to 40 Hz, 5 Hz to 40 Hz, or 15 Hz to 25 Hz is selected according to the vibration behavior of the projection optical box structure 302.1. It will be understood that you can.

  In this example, in order to beneficially affect the vibration behavior of the projection optical box structure 302.1, each connecting device 317.2 has an associated vibration balancing mass unit 317 with a first damping ratio of about 1%. .1 vibration damping. It will be appreciated that a different first damping ratio can be selected depending on the vibration behavior in the support structure of the optical element. Preferably, the first damping ratio is selected from the following ranges: 0.2% to 15%, 0.2% to 5%, 1.0% to 3.0%.

  It will be understood that in the microlithography apparatus 101 of this embodiment, a line-of-sight accuracy of 100 pm or less can be obtained in all related degrees of freedom, typically in the x and y directions. In general, when the third resonance frequency of the third vibration isolator 118 is lowered, better line-of-sight accuracy is provided. Further, the increase in the line-of-sight accuracy is realized by increasing the rigidity of the second projection optical box sub-structure 302.4.

  Again, it will be appreciated that any desired and appropriate material can be selected for the individual support structures. For example, metals such as aluminum can be used for individual support structures, specifically, support structures that are relatively light and require relatively high stiffness. The materials described in the first embodiment can also be selected according to the type and / or function of each individual support structure. In this example, the sub-structures of the projection optical box structure 302.1 are both made of aluminum.

  In the above, the embodiment of the present invention has been described using the optical element as a reflective element exclusively, but in other embodiments of the present invention, a reflective, refractive or diffractive element or any combination thereof is used for the optical element of the optical element unit. It will be understood that you can.

Claims (36)

An optical imaging device comprising an optical projection system and a support structure system,
The optical projection system is configured to transfer the pattern image of the mask supported by the mask support structure onto the substrate supported by the substrate support structure along the exposure path using exposure light in the exposure process. Having a configured optical element group;
The mask support structure and the substrate support structure form a primary vibration source;
The support structure system includes a base support structure, an optical element support structure, and at least one secondary vibration source support structure in a secondary vibration source other than the primary vibration source;
The optical element support structure supports the optical element;
The at least one secondary vibration source support structure supports a secondary vibration source, and the secondary vibration source is a secondary vibration disturbance source including solid propagation vibration energy, and the secondary vibration source is the optical imaging. Located inside the device;
The base support structure includes the optical element support structure and the secondary vibration source support structure, and the structural path of the solid propagation vibration energy from the secondary vibration source to the optical element support structure is supporting to exist only through the base over scan support unit, the optical imaging device. The optical imaging device according to claim 1.
The secondary vibration source is a member of a group of secondary vibration sources;
The secondary vibration source group includes a measurement system component, a cooling unit of the measurement system, a component of the optical projection system, and a moving component of the optical projection system;
The optical imaging device, wherein the secondary vibration source support structure is particularly supported on the base support structure to block vibration. The optical imaging apparatus according to claim 1 or 2,
The optical element support structure comprises at least one optical element support unit;
The at least one optical element support unit supports the optical element;
The optical imaging device, wherein the at least one optical element support unit is supported on the base support structure via a vibration isolator. The optical imaging device according to claim 3.
The anti-vibration device has an anti-vibration resonance frequency in the anti-vibration resonance frequency range;
The vibration isolation resonance frequency range is selected from a group of vibration isolation resonance frequency ranges;
The anti-vibration resonance frequency range group is an optical imaging apparatus including a range of 0.05 Hz to 8.0 Hz, 0.1 Hz to 1.0 Hz, and 0.2 Hz to 0.6 Hz. The optical imaging device according to claim 3 or 4,
The at least one optical element support unit is a first support unit;
The anti-vibration device is a first anti-vibration device having a first anti-vibration resonance frequency;
The optical element support structure has at least one second support unit;
The at least one second support unit supports the optical element;
The optical imaging device, wherein the at least one second support unit is supported on the first support unit via a second vibration isolator. The optical imaging device according to claim 5.
Said second anti-vibration device has a second anti-vibration resonance frequency in the anti-vibration resonance frequency range;
The second vibration isolation resonance frequency range is selected from a second vibration isolation resonance frequency range group;
The second image stabilization resonance frequency range group is an optical imaging device including ranges of 1 Hz to 30 Hz, 1 Hz to 8 Hz, 1 Hz to 40 Hz, and 25 Hz to 30 Hz. In the optical imaging device according to any one of claims 3 to 6,
Said optical element support structure comprises at least one vibrationally balanced mass unit;
The vibration balance mass unit is connected to the optical element support unit via a connection device;
Said connecting device has a balanced resonant frequency in a balanced resonant frequency range;
The balanced resonant frequency range is selected from a balanced resonant frequency range group;
The balanced resonance frequency range group is an optical imaging apparatus including a range of 1 Hz to 40 Hz, 5 Hz to 40 Hz, and 15 Hz to 25 Hz. The optical imaging device according to claim 7.
Said at least one vibration balancing mass unit comprises at least one vibration balancing mass element;
The optical imaging apparatus, wherein the vibration balance mass element is kinematically arranged in series between the optical element support unit and the optical element of the optical element group. The optical imaging device according to claim 7 or 8,
The optical element group includes at least one of a first subgroup of optical elements and a second subgroup of optical elements;
The first subgroup of optical elements comprises at least one first optical element;
The balance mass element of the at least one vibration balance mass unit is not associated with the at least one first optical element;
The second subgroup of optical elements comprises a plurality of second optical elements;
The optical imaging device, wherein at least one balance mass element of the at least one vibration balance mass unit is associated with each of the second optical elements. The optical imaging device according to claim 9.
A plurality of balanced mass elements are associated with at least one of the second optical elements;
The optical imaging apparatus, wherein the plurality of balance mass elements include at least one of at least two balance mass elements and 2 to 6 balance mass elements. In the optical imaging device according to any one of claims 7 to 10,
The connecting device is configured to provide vibration damping of the at least one vibrationally balanced mass unit at a damping ratio;
The attenuation ratio is selected from an attenuation ratio range of an attenuation ratio range group;
The optical imaging apparatus, wherein the attenuation ratio range group includes ranges of 0.2% to 15%, 0.2% to 5%, and 1.0% to 3.0%. In the optical imaging device according to any one of claims 3 to 11,
The support structure has a projection measurement support structure;
The projection system measurement support structure is associated with the optical element group, and is configured to capture a variable representative representing a state of at least one optical element of the optical element group. Support;
The at least one projection system measurement support structure is supported on the base support structure via a further vibration isolator, and the at least one projection system measurement support structure is kinematically arranged in series. An optical imaging device supported on the base support structure via at least two vibration isolation devices. The optical imaging device according to claim 12.
Said further anti-vibration device has a further anti-vibration resonance frequency in the further anti-vibration resonance frequency range;
The further anti-vibration resonance frequency range is selected from a group of further anti-vibration resonance frequency ranges;
The further anti-vibration resonance frequency range group is an optical imaging device comprising a range of 1 Hz to 30 Hz, 2 Hz to 10 Hz, and 3 Hz to 8 Hz. The optical imaging device according to claims 7 and 13,
The further anti-vibration resonant frequency and the balanced resonant frequency are separated by a frequency gap;
The frequency gap is selected from a frequency gap range of a frequency gap range group;
The optical image forming apparatus, wherein the frequency gap range group includes ranges of 1 Hz to 40 Hz, 10 Hz to 25 Hz, and 100% to 400% of the further vibration isolation resonance frequency. In the optical imaging device according to any one of claims 12 to 14,
The further vibration isolator is configured to provide a damping of vibration of the at least one projection system metrology support structure in a damping ratio;
The damping ratio is selected from damping ratio ranges of a damping ratio range group;
The optical imaging apparatus, wherein the attenuation ratio range group includes ranges of 5% to 60%, 10% to 30%, and 20% to 25%. In the optical imaging device according to any one of claims 3 to 15,
At least one of the at least one optical element support unit and the projection system metrology support structure is made of a material selected from a group of materials;
The material group is steel, aluminum (Al), titanium (Ti), invar alloy, tungsten alloy, ceramic material, silicon-impregnated silicon carbide (SiSiC), silicon carbide (SiC), silicon (Si), carbon fiber reinforced carbonization. An optical imaging device composed of silicon composite (C / CSiC), aluminum oxide (Al ₂ O ₃ ), Zerodur (registered trademark), ULE (registered trademark) glass, quartz and cordierite. The optical imaging device according to claim 5.
The first support unit is made of a first material having a first stiffness;
The second support unit is made of a second material having a second stiffness;
The optical imaging apparatus, wherein the second rigidity is higher than the first rigidity. The optical imaging apparatus according to any one of claims 1 to 17, wherein the optical imaging apparatus is
Configured to be used in microlithography using exposure light at exposure wavelengths in the UV range;
The exposure wavelength range is from 5 nm to 20 nm;
The optical element of the optical element group is a reflective optical element;
An optical imaging device that is at least one of the above. A method for supporting an optical projection system of an optical imaging apparatus, wherein the optical projection system uses an exposure light in an exposure process to form a pattern image of a mask supported by a mask support structure along an exposure path. A method comprising: a group of optical elements configured to be transferred onto a substrate supported by a substrate support structure, wherein the mask support structure and the substrate support structure form a primary vibration source; Is
Supporting the optical element on a base support structure via an optical element support structure;
Supporting a secondary vibration source other than the primary vibration source on the base support structure via a secondary vibration source support structure, wherein the secondary vibration source includes solid propagation vibration energy 2 A secondary vibration disturbance source, wherein the secondary vibration source is disposed inside the optical imaging device;
The optical element support structure and the secondary vibration source support structure are routed through the base support unit through a structural path of the solid propagation vibration energy from the secondary vibration source to the optical element support structure. A method that supports only to be present. The method of claim 19, wherein
The optical element support structure comprises at least one optical element support unit;
The at least one optical element support unit supports the optical element;
Supporting the at least one optical element support unit on the base support structure so as to block vibration at a vibration isolation resonance frequency in a vibration isolation resonance frequency range;
The vibration isolation resonance frequency range is selected from a group of vibration isolation resonance frequency ranges;
The anti-vibration resonant frequency range group comprises a range of 0.05 Hz to 8.0 Hz, 0.1 Hz to 1.0 Hz, and 0.2 Hz to 0.6 Hz. The method of claim 20, wherein
The at least one optical element support unit is a first support unit;
The anti-vibration resonance frequency is a first anti-vibration resonance frequency;
The optical element support structure has at least one second support unit;
The at least one second support unit supports the optical element;
The at least one second support unit is supported by the first support unit so as to block vibration at a second vibration isolation resonance frequency in a second vibration isolation resonance frequency range;
The second vibration isolation resonance frequency range is selected from a second vibration isolation resonance frequency range group;
The second anti-vibration resonance frequency range group comprises a range of 1 Hz to 30 Hz, 1 Hz to 8 Hz, 1 Hz to 40 Hz, and 25 Hz to 30 Hz. The method according to claim 20 or 21, wherein
Connecting at least one vibration balance mass unit to the optical element support unit such that at least one of a balance effect at a balance resonance frequency in a range of balance resonance frequencies and a vibration damping effect at a damping ratio is provided;
Selecting the balanced resonant frequency range from a group of balanced resonant frequency ranges;
The balanced resonant frequency range group consists of 1 Hz to 40 Hz, 5 Hz to 40 Hz, and 15 Hz to 25 Hz;
Selecting the damping ratio from the damping ratio range of the damping ratio range group;
The method of claim 1, wherein the damping ratio range group comprises ranges of 0.2% to 15%, 0.2% to 5%, and 1.0% to 3.0%. 23. The method according to claim 20-22, wherein:
Supporting a projection system measurement support structure on the base support structure so as to cut off vibrations at a further vibration isolation resonance frequency in a further vibration isolation resonance frequency range;
The projection system measurement support structure is associated with the optical element group, and is configured to capture a variable representative representing a state of at least one optical element of the optical element group. Support;
Said further vibration isolation resonance frequency range is selected from a group of further vibration isolation resonance frequency ranges;
The further anti-vibration resonant frequency range group comprises a range of 1 Hz to 30 Hz, 2 Hz to 10 Hz, and 3 Hz to 8 Hz. An optical imaging device comprising an optical projection system and a support structure system,
The optical projection system is configured to transfer the pattern image of the mask supported by the mask support structure onto the substrate supported by the substrate support structure along the exposure path using exposure light in the exposure process. Having a configured optical element group;
The mask support structure and the substrate support structure form a primary vibration source;
The support structure system includes a base support structure, an optical element support structure, and at least one secondary vibration source support structure in a secondary vibration source other than the primary vibration source;
The optical element support structure supports the optical element;
The at least one secondary vibration source support structure supports a secondary vibration source, and the secondary vibration source is a secondary vibration disturbance source including solid propagation vibration energy, and the secondary vibration source is the optical imaging. Located inside the device;
The base support structure is configured such that the optical element support structure and the secondary vibration source support structure are mechanically moved from the optical element support structure via at least one vibration isolator. An optical imaging device that supports the optical imaging device so as to be blocked. 25. The optical imaging device of claim 24.
The secondary vibration source is a member of a group of secondary vibration sources;
The secondary vibration source group includes a measurement system component, a cooling unit of the measurement system, a component of the optical projection system, a moving component of the optical projection system, and a cooling unit of the optical projection system;
The optical imaging apparatus, wherein the secondary vibration source support structure is particularly supported on the base support structure so as to block vibration via a vibration isolator. The optical imaging device according to claim 24 or 25.
The optical element support structure comprises at least one optical element support unit;
The at least one optical element support unit supports the optical element;
The optical imaging device, wherein the at least one optical element support unit is supported on the base support structure via a vibration isolator. The optical imaging device of claim 26.
The anti-vibration device has an anti-vibration resonance frequency in the anti-vibration resonance frequency range;
The vibration isolation resonance frequency range is selected from a group of vibration isolation resonance frequency ranges;
The anti-vibration resonance frequency range group is an optical imaging apparatus including a range of 0.05 Hz to 8.0 Hz, 0.1 Hz to 1.0 Hz, and 0.2 Hz to 0.6 Hz. 28. An optical imaging device according to claim 26 or 27.
The at least one optical element support unit is a first support unit;
The anti-vibration device is a first anti-vibration device;
The optical element support structure has at least one second support unit;
The at least one second support unit supports the optical element;
The optical imaging device, wherein the at least one second support unit is supported on the first support unit via a second vibration isolator. The optical imaging device of claim 28.
Said second anti-vibration device has an anti-vibration resonance frequency in the anti-vibration resonance frequency range;
The second vibration isolation resonance frequency range is selected from a second vibration isolation resonance frequency range group;
The second image stabilization resonance frequency range group is an optical imaging device including ranges of 1 Hz to 30 Hz, 1 Hz to 8 Hz, 1 Hz to 40 Hz, and 25 Hz to 30 Hz. The optical imaging device according to any one of claims 26 to 29,
Said optical element support structure comprises at least one vibrationally balanced mass unit;
The vibration balance mass unit is connected to the optical element support unit via a connection device;
Said connecting device has a balanced resonant frequency in a balanced resonant frequency range;
The balanced resonant frequency range is selected from a balanced resonant frequency range group;
The balanced resonance frequency range group is an optical imaging apparatus including a range of 1 Hz to 40 Hz, 5 Hz to 40 Hz, and 15 Hz to 25 Hz. The optical imaging device according to any one of claims 26 to 30, wherein
The support structure has a projection measurement support structure;
The projection system measurement support structure is associated with the optical element group, and is configured to capture a variable representative representing a state of at least one optical element of the optical element group. Support;
The at least one projection system measurement support structure is supported on the base support structure via a further vibration isolator, and the at least one projection system measurement support structure is kinematically arranged in series. An optical imaging device supported on the base support structure via at least two anti-vibration devices. 32. The optical imaging device of claim 31.
Said further anti-vibration device has a further anti-vibration resonance frequency in the range of further anti-vibration resonance frequencies;
The further anti-vibration resonance frequency range is selected from the group of further anti-vibration resonance frequency ranges;
The further anti-vibration resonance frequency range group is an optical imaging device comprising a range of 1 Hz to 30 Hz, 2 Hz to 10 Hz, and 3 Hz to 8 Hz. The optical imaging apparatus according to any one of claims 26 to 32,
At least one of the at least one optical element support unit and the projection system metrology support structure is made of a material selected from a group of materials;
The material group is steel, aluminum (Al), titanium (Ti), invar alloy, tungsten alloy, ceramic material, silicon-impregnated silicon carbide (SiSiC), silicon carbide (SiC), silicon (Si), carbon fiber reinforced carbonization. An optical imaging device composed of silicon composite (C / CSiC), aluminum oxide (Al ₂ O ₃ ), Zerodur (registered trademark), ULE (registered trademark) glass, quartz and cordierite. A method for supporting an optical projection system of an optical imaging apparatus, wherein the optical projection system uses an exposure light in an exposure process to form a pattern image of a mask supported by a mask support structure along an exposure path. A method comprising: a group of optical elements configured to be transferred onto a substrate supported by a substrate support structure, wherein the mask support structure and the substrate support structure form a primary vibration source; Is
Supporting the optical element on a base support structure via an optical element support structure;
Supporting a secondary vibration source other than the primary vibration source on the base support structure via a secondary vibration source support structure, wherein the secondary vibration source includes solid propagation vibration energy 2 A secondary vibration disturbance source, the vibration source being located inside the optical imaging device;
The optical element support structure and the secondary vibration source support structure are arranged such that the secondary vibration source support structure is mechanically isolated from the optical element support structure via at least one vibration isolator. , Supported by the base support structure. An optical imaging device comprising an optical projection system and a support structure system,
The optical projection system is configured to transfer the pattern image of the mask supported by the mask support structure onto the substrate supported by the substrate support structure along the exposure path using exposure light in the exposure process. Having a configured optical element group;
The support structure includes a base support structure, an optical element support structure, and a projection system measurement support structure;
The optical element support structure supports the optical element;
The optical element support structure is supported on the base support structure via a first vibration isolator;
The projection system measurement support structure is associated with the optical element group and is configured to capture a variable representative representing a state of at least one optical element of the optical element group. Support;
The optical imaging apparatus, wherein the projection system measurement support structure is supported on the optical element support structure via a second vibration isolator. A method for supporting an optical projection system of an optical imaging apparatus, wherein the optical projection system uses an exposure light in an exposure process to form a pattern image of a mask supported by a mask support structure along an exposure path. A method comprising a group of optical elements configured to be transferred onto a substrate supported by a substrate support structure, the method comprising:
Supporting the optical element on a base support structure via an optical element support structure;
Supporting at least one measurement device associated with the optical element group on the optical element support structure using a projection system measurement support structure;
Supporting the projection system measurement support structure on the optical element support structure via a second vibration isolator,
The method, wherein the at least one measuring device is configured to capture a variable representative representing a state of at least one optical element of the optical element group.

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