CN105739248B - Optical element support structure, unit microscope group, exposure optical system and litho machine - Google Patents

Abstract

The invention discloses an optical element supporting structure, which is used for supporting an optical element (22) of a unit lens group (21), comprising a mirror seat (24), and the mirror seat (24) is a circularly symmetrical mechanical component. The inner ring of the mirror base (24) protrudes a support rod (246) toward the center of the mirror base, and the support rod (246) is flexible in the optical axis direction and the radial direction of the mirror base, and the end of the support rod (246) is provided with a supporting surface (247), the supporting surface (247) matches the lower surface of the optical element (22) to fix the optical element (22) on the mirror holder (24); the supporting rod (246) The inboard side is connected with a moving platform (245), and the moving platform (245) is connected with the outer ring of the mirror holder (24) by a guide mechanism (243), and the described guiding mechanism (243) is used for moving the platform (245) motion oriented.

Description

Optical element support structure, unit mirror group, exposure optical system and photolithography machine

technical field

The invention belongs to the technical field of high-precision optical lens manufacturing and assembly, and in particular relates to a support structure for an optical element capable of compensating surface shape, a unit lens group, an exposure optical system and a photolithography machine.

Background technique

The design, processing, manufacture and adjustment of high-end lithography projection objective lens is a very precise and complex system engineering. With the extension of Moore's Law, the semiconductor industry has higher and higher requirements for the minimum line width resolution of processor chips. In order to achieve high-quality imaging performance and higher resolution, the RMS value of the surface shape accuracy of optical components is required to reach 1nm ~2nm level. As the NA value of the projection objective optical system of the lithography machine gradually increases, the clear aperture of the optical components in the projection objective lens of the lithography is also increasing, and the outer diameter of the lens often reaches 320mm or even larger. However, with the increase of the outer diameter of the optical element, the influence of external force on the surface shape of the optical element is also more sensitive. If precise control is not carried out, the surface shape error caused by gravity or fastening force is likely to exceed the expected value by 2 to 3 times or even more than 10 times.

In addition to the residual surface error of the optical element itself during optical processing, the size and shape tolerances caused by the processing of supporting structures such as mirror frames will cause uneven force on the optical element and surface error; in addition, when the optical element is fixed When it is in the mirror frame or the mirror holder, no matter whether it is glued or clamped, it cannot achieve a completely "stress-free" effect, and it will also introduce surface shape errors; finally, after connecting all optical components and the mirror frame into a When projecting the objective lens as a whole, certain fixing and connecting measures must be adopted, and the stress generated during this process will also be transmitted to the optical components, introducing a certain degree of surface error. The above-mentioned factors that affect the surface shape accuracy of optical components are all called static surface shape influencing factors.

During the working process of the lithography machine, after continuous exposure, each optical element of the projection objective lens will absorb a certain amount of laser energy. Due to the different sizes and thicknesses of the optical elements, the temperature changes generated by each optical element are different. Since the large-aperture optical lens is more sensitive to temperature changes, the change of the surface shape of the optical element caused by the temperature difference will have an adverse effect on the imaging performance of the optical system. In addition, changes in ambient temperature and air pressure will also lead to deterioration of the imaging performance of the projection objective lens. The above-mentioned factors that interfere with the imaging performance of the projection objective lens during the working process of the lithography machine can be called dynamic surface shape factors.

In order to achieve a higher-precision resolution, it is necessary to compensate the above-mentioned static surface error and dynamic surface error. Patent US6392825B1 discloses a mirror frame structure with multiple elastic support units, which can offset the influence of external stress and deformation through the elasticity of the support units; since the elastic support units are processed by thin plate materials, it is difficult to achieve micron-level processing accuracy, and the elastic support The unit and the mirror frame are connected by welding or screw fastening, and welding stress and screw preload will also reduce the final precision of the elastic support unit. Patent US6229675B1 proposes a structural form that decouples the deformation of the inner and outer frames. This structure has poor processability and is a passive compensation method. Although it can eliminate the influence of external stress on the surface shape accuracy of optical elements, it cannot compensate for dynamics. Surface error. Patent US7031082B2 discloses a mirror frame structure capable of deforming optical elements, and also equipped with a deformation monitoring unit. However, the deformation adjustment part of this structure is assembled from multiple parts, which is complicated in structure and difficult to assemble and adjust. Shape adjustment with nanoscale precision. Patent US7193794B2 discloses a mirror frame structure that actively compensates the surface error of the optical element, which can compensate the influence of astigmatism and trilobes on the imaging performance of the system without changing the spatial position of the optical element; however, this method is axially Arranging the driver or transmission structure in the direction of the optical axis takes up a lot of space, it is difficult to adjust the force of the optical element at each support point, and it cannot be used for surface shape compensation of more optical elements in the same objective lens.

Contents of the invention

In order to solve the compensation problem of static surface error and dynamic surface error of optical elements in the exposure optical system of lithography projection objective lens, and ensure the high-precision support and positioning of optical elements in the manufacturing process of lithography projection objective lens, the present invention proposes a compensable Or the supporting structure of the optical element to adjust the surface shape of the optical element. This structure is simple and has good manufacturability. It can compensate the influence of factors such as processing error, adjustment force and external temperature change on the surface shape accuracy of the optical element. It can be flexibly applied to the objective lens assembly. Tuning, testing and work and other links.

The technical solution adopted by the present invention to solve the problems of the technologies described above is as follows:

An optical element support structure is provided, which is used to support the optical elements of the unit lens group, including a mirror base, the mirror base is a circularly symmetrical mechanical component, and a circle of support rods protrudes from the inner ring of the mirror base to the center, so that The support rod has a certain degree of flexibility in the optical axis direction and the radial direction of the mirror base, and the end of the support rod is provided with a support surface, and the support surface is matched with the lower surface of the optical element to fix the optical element on the mirror base ; The inner side of the support rod is connected with a moving platform, and the moving platform is connected with the outer ring of the mirror base through a guiding mechanism, and the guiding mechanism is used for guiding the movement of the moving platform.

The optical element support structure of the present invention is applied to the unit lens group of the exposure optical system. A ring of support rods protrudes from the inner ring of the mirror base to the center. The support rods have certain flexibility in the direction of the optical axis and the radial direction of the mirror base. A support surface is provided, and the support surface matches the lower surface of the optical element to fix the optical element on the mirror base, which can not only realize the ultra-high precision support and positioning of the optical element, but also cause a certain deformation and displacement of the support rod by driving the moving table. It can also effectively compensate surface shape errors caused by external processing and assembly tolerances, and can also compensate in real time the aberrations caused by ambient temperature, pressure, and laser irradiation during the working process. Therefore, the supporting structure of the optical element can guarantee the overall image quality of the exposure optical system of the lithography projection objective lens in the whole life cycle. In addition, the supporting structure of the optical element of the present invention takes up little space, can be integrally processed with the mirror base of the exposure optical system, and is easy to process and manufacture with low cost. It can manually or automatically compensate the static and dynamic surface shape of the optical element while reducing the size and shape tolerance requirements of the optical element support mirror base, and finally realize the ultra-high-precision surface shape requirements of the optical element. Moreover, the structure can be applied to various types of optical elements, and can be used in a wide range of compensation, which can ensure the final image quality requirements of the exposure optical system.

According to an embodiment of the present invention, an upper connecting flange and a lower connecting flange protrude from the top and the bottom of the mirror base respectively.

According to an embodiment of the present invention, the guide mechanism is connected with the outer ring of the mirror base to form a slit, and the movement range of the moving table is restricted by the width of the slit.

According to the present invention, the optical element supporting structure has a moving table with a guiding structure, which can convert radial displacement into surface shape change of the optical element, realize active compensation of object image quality, and can be driven manually or automatically.

According to an embodiment of the present invention, the guide mechanism is a symmetrically distributed parallel four-bar linkage structure, the parallel four-bar linkage structure can ensure the reciprocating motion of the moving table in a preset radial direction, and the diameter of the guide mechanism is The axial dimension is much smaller than its axial dimension and circumferential dimension, so that its rigidity in the optical axis direction is much greater than its rigidity in the radial direction, so that the guide mechanism has a degree of freedom of movement in the radial direction. Here, much smaller means that the size ratio is less than 1:10; much larger means that the size ratio is greater than 10:1.

According to an embodiment of the present invention, the guide mechanism is composed of four thin leaf springs, and the four thin leaf springs are symmetrically distributed two by two relative to the radial direction, so as to form a pair of parallel four-bar linkages.

According to an embodiment of the present invention, the matching surface of the support surface and the lower surface of the optical element is one of plane, concave or convex, the number of the support rods is greater than or equal to 3, and the support rods are circumferentially uniform around the optical axis. cloth arrangement.

According to an embodiment of the present invention, the support structure further includes a plurality of driving mechanisms, and the mirror base is formed with a plurality of positioning holes extending radially along the mirror base, and the positioning holes extend from the outer ring surface of the mirror base to the The slit communicates, the driving mechanism is inserted into the positioning hole to be fixed in the mirror base, the end of the driving mechanism is in contact with the moving table, and the end of the driving mechanism can output a certain displacement and force, and transmit it to the moving table The supporting rod is directly connected to the moving table, and the radial displacement generated by the moving table can directly drive the supporting rod to generate displacement and deformation, and the supporting rod can transmit the force and deformation to the optical element . The driving mechanism of the present invention has multiple options, and it is easy to realize high-precision compensation and adjustment of the surface shape of the optical element.

In addition, the present invention also provides a unit lens group, which includes the above optical element supporting structure.

In addition, the present invention also provides an exposure optical system, which is formed by stacking a plurality of the above-mentioned unit lens groups.

In addition, the present invention also provides a photolithography machine, which includes a mask stage, the above-mentioned exposure optical system and a silicon wafer stage, and the exposure optical system is arranged between the mask stage and the silicon wafer stage for The pattern on the mask stage is perfectly imaged on the silicon wafer stage.

The supporting structure of the optical element provided by the present invention can realize arbitrary multiple driving point arrangements, and can not only compensate low-order aberrations, but also compensate high-order aberrations. The guiding mechanism of the present invention is simple and compact, has an integrated structure, and can realize the adjustment and compensation of more components in the limited space of the lithography objective lens. The invention has good mechanical processing technology and is easy to realize high-precision processing and detection of the supporting surface. The optical element supporting structure of the present invention has universality and can be adapted to different purposes and different types of optical elements.

Description of drawings

Fig. 1 is an axonometric view of a unit mirror group provided by an embodiment of the present invention;

Fig. 2 is a partial sectional view of a unit mirror group provided by an embodiment of the present invention;

Fig. 3 is a partial top view of a unit lens group provided by an embodiment of the present invention;

Fig. 4 is an axonometric view of a unit lens group provided by an embodiment of the present invention;

Fig. 5 is a measurement diagram of the surface shape change of the optical element of the unit lens group provided by an embodiment of the present invention;

FIG. 6 is a schematic structural diagram of a photolithography machine provided by an embodiment of the present invention.

In the figure: 1 mask stage, 2 exposure optical system, 3 silicon wafer stage, 4 measuring light, 5 surface measuring interferometer, 21 unit mirror group, 22 optical element, 23 driving mechanism, 24 mirror seat, 25 optical axis, 241 upper connection flange, 242 lower connection flange, 243 guide mechanism, 244 slit, 245 motion table, 246 support bar, 247 support surface, 248 positioning holes.

detailed description

Referring to FIG. 1 to FIG. 5 , an optical element supporting structure provided by an embodiment of the present invention includes a mirror holder 24 and a driving mechanism 23 . The mirror base 24 includes an upper connecting flange 241 , a lower connecting flange 242 , a guiding mechanism 243 , a slit 244 , a moving platform 245 , a supporting rod 246 , a supporting surface 247 and a positioning hole 248 which are integrally formed.

As shown in FIG. 1 , the supporting structure of the optical element is included in the unit lens group 21 , and the unit lens group 21 is usually composed of an optical element 22 , a driving mechanism 23 and a lens holder 24 . Usually, the direction parallel to the optical axis of the optical element 22 is defined as the Z axis, the center of the coordinate system is located at the center of the upper or lower surface of the optical element 22, and the plane perpendicular to the Z axis is the XY plane. The material of the optical element 1 is fused silica, glass-ceramics, ULE or calcium fluoride commonly used in deep ultraviolet projection lithography objective lenses, and can also be common optical materials used in ordinary lenses. The mirror base 24 is a ring-shaped rotationally symmetrical metal member with a through hole in the center for placing the optical element 22. The diameter of the through hole is determined by the optical element 22, generally 50mm-350mm, so that light can pass through. There is usually a certain gap between the mirror base 24 and the optical element 22 for the assembly and adjustment of the optical element 22 . The mirror base 24 needs to be made of a material with high strength and stability, generally a metal material, such as: stainless steel, aluminum alloy, copper alloy, indium steel, titanium alloy, high-strength tool steel, etc. One or more optical elements 22 are usually placed in the mirror holder 24, and one optical element 22 is placed in the illustrated example.

As shown in FIG. 2 , an upper connecting flange 241 and a lower connecting flange 242 protrude from the top and bottom of the mirror base 24 respectively, and the two can be fixedly connected with adjacent mirror groups by screws or other means. The mirror base 24 is extended with a support rod 246 close to the central through hole. The end of the support rod 246 has a support surface 247 for supporting and positioning the optical element 22 . Each support rod 246 corresponds to a support surface 247 . The optical element 22 is fixed on the support surface 247 by means of mechanical fastening, elastic clamping (detailed structure is not given in this example), welding or adhesive bonding. According to the difference in surface curvature of the optical element 22, the support Face 247 may be flat, concave or convex. The supporting surface 247 is approximately rectangular, and its area can be between 2mm×2mm～10mm×10mm. According to different ways of fixing the optical element 22, different supporting areas can be selected, so that the optical element 22 can be stably and reliably Fixed in the mirror holder 24. The support surface 247 is usually processed by means of ultra-precision turning, precision laser machining, precision electric discharge machining, ultrasonic vibration machining, precision grinding and the like.

The support rod 246 is a strip-shaped structure along the same direction as the Z axis parallel to the optical axis 25, and its length along the Z direction is L, along the radial direction (from the optical axis 25 to the outer circumference of the mirror holder 24, and vertically The dimension on the optical axis 25) is the thickness T, and the dimension along the circumferential direction (tangent to the outer circumference of the mirror holder 24 and perpendicular to the optical axis 25 and the radial direction) is A. In most cases L>A>T, the size range of L is 3mm-30mm, the size range of A is 1mm-20mm, and the size range of T is 0.1mm-5mm. According to the weight, size and material of the optical element 22, the size of the support rod 246 is also different, so that it has a certain flexibility in the radial direction or the direction of the optical axis. The support rod 246 is located on the motion table 245, and is an integral processing structure or assembly structure. The moving table 245 has sufficient rigidity to bear the weight of the support rod 246 and the optical element 22 . The moving table 245 is connected with the outer ring of the mirror base 24 through the guide mechanism 243 .

As shown in FIG. 3 , the guide mechanism 243 is composed of four thin leaf springs, and the four thin leaf springs are symmetrically distributed two by two relative to the radial direction, forming a pair of parallel four-bar linkages. According to the size and weight of the optical element 22 and the mirror holder 24, the thickness of each thin leaf spring is between 0.1 mm and 2 mm, and the length is between 10 mm and 40 mm, so that the thickness of the thin leaf spring has a certain degree of flexibility in the radial direction , it can produce radial deformation under external force. Due to the guiding effect of the parallel four-bar linkage of the thin leaf spring, the moving table 245 can reciprocate in the radial direction, that is, the R direction shown in the figure. The thin plate spring structure of the guide mechanism 243 is through in the Z direction parallel to the optical axis, and is connected with the moving table 245 and the mirror base 24 to form an integrated structure. The guide mechanism 243 can be processed by laser processing, chemical corrosion, wire cutting, electric spark and the like. The slit 244 is formed after processing in the above-mentioned manner, and the slit width of the slit 244 is generally between 0.2 mm and 3 mm, which is used to limit the range of motion of the motion table 245 and prevent the stress of the thin plate spring of the guide mechanism 243 due to an excessively large motion stroke. Beyond its yield limit, structural damage occurs. The guide mechanism 243 can also be assembled with a separate leaf spring for guiding the motion of the motion table 245 . The guide mechanism 243 is also designed in an asymmetric form, or a parallel six-bar linkage or other structural forms with a guiding function.

A typical example of the driving mechanism 23 is a screw micrometer, which is fixed in the positioning hole 248 and whose end is in contact with the motion table 245 for outputting force and displacement. The driving mechanism 23 is arranged along the radial direction R, and its output displacement direction is also radial. The Z-direction position of the driving mechanism 23 is in the middle of the motion table 245, basically on the same level as the support surface 247, so as to ensure that the motion table 245 only moves parallel to the R direction and does not generate displacement in other directions. The drive mechanism 23 can also adopt other types of displacement output mechanisms, such as: piezoelectric actuators, pneumatic components, hydraulic drive components, linear motors and magnetic devices, etc. The driving method can be manual or automatic.

In a typical example, the driving mechanism 23 corresponds to the moving platform 245 , the guiding mechanism 243 , the supporting rod 246 and the supporting surface 247 one by one. As shown in FIG. 4 , the driving mechanism 23 , the moving table 245 , the guiding mechanism 243 , the supporting rod 246 and the supporting surface 247 are uniformly distributed around the Z-axis in the circumferential direction, and the number is usually between 3 and 40 according to different applications. In other application examples, part of the moving table 245 may not include the driving mechanism 23 and the guiding mechanism 243, and only the supporting rod 246 and the supporting surface 247 are reserved.

As shown in FIG. 5 , through the output displacement and force along the R direction of the driving mechanism 23 , the motion table 245 can be driven to generate a corresponding displacement along the R direction, and finally the driving force is transmitted to the support rod 246 and the support surface 247 . Since the supporting surface 247 is generally an inclined surface, the driving force transmitted to the inclined surface can be decomposed into an axial force along the Z direction, thereby changing the surface shape of the optical element 22 . The surface shape of the optical element 22 can be controlled by the driving mechanism 23, such as: by driving two driving mechanisms 23 at an interval of 180° in the same direction, the surface of the optical element 22 can be astigmatized; The three driving mechanisms 23 are driven in the same direction to produce three-leaf aberration on the surface of the optical element 22; by driving 8 driving mechanisms 23 at intervals of 45° in the same direction, a four-leaf image can be produced on the surface of the optical element 22 Difference. By analogy, by outputting driving displacements in different directions and sizes to different positions and numbers of driving mechanisms 23, various aberrations of the surface shape of the optical element 22 can be artificially realized, and the aberrations can be controlled by controlling the driving force or driving displacement. to fulfill. The surface shape change of the optical element 22 of the unit lens group 21 can be detected by irradiating the measuring light 4 to the optical element by the surface shape measurement interferometer 5 .

Generating desired aberrations on the surface of the optical element 22 can be used for image quality compensation and adjustment of the exposure optical system 2 .

As shown in Figure 6, the mask stage 1, the exposure optical system 2, and the silicon wafer stage 3 are all components of a large-scale integrated circuit manufacturing equipment lithography machine, and the exposure optical system 2 is used to convert the pattern on the mask stage 1 into Perfect imaging on wafer stage 3. The exposure optical system 2 is formed by stacking a plurality of unit lens groups 21 . During the working process, the exposure optical system 2 is affected by changes in external temperature and air pressure, and its imaging focus position will drift to a certain extent. At the same time, the deformation caused by the absorption of laser energy by its internal optical elements 22 will also produce different types of imaging aberrations. The imaging quality of the exposure optical system 2 can be adjusted and compensated by controlling the different positions and numbers of the driving mechanisms 23 of the unit lens group 21 .

The working principle of the above-mentioned embodiment of the present invention is as follows:

The optical elements in the unit lens group are fixed on multiple circumferentially uniform support surfaces of the lens base through laser welding, adhesive bonding or other mechanical locking methods, and the support surfaces are connected with the lens base through support rods. Due to the extremely high requirements for the surface shape accuracy of optical components, usually between 0.3nm and 2nm, considering the influence of the weight of optical components, the requirements for the shape and position tolerances of all supporting surfaces are extremely high, usually sub-micron or even Nanoscale requirements, even if ultra-precision turning is used, it is difficult to fully guarantee that the shape and position tolerances meet the requirements. In the above embodiments of the present invention, the guide mechanism and the slit are processed or assembled on the mirror base to form a moving platform connected to the support rod, so that the guiding mechanism works according to the principle of symmetrically arranged parallel four-bar linkages, thereby ensuring that the moving platform can Reciprocate in the desired radial direction. The driving mechanism is fixed in the outer ring of the mirror base through the positioning hole. During the working process, the front section of the driving mechanism will output the displacement according to the adjustment amount, and push the moving table to generate the desired amount of movement and driving force. The driving mechanism can be manually driven or automatically driven, and its maximum output displacement is limited by the slit of the guiding mechanism to avoid damage to the guiding mechanism due to excessive force.

In this embodiment, the size and shape tolerances caused by the processing and assembling of the mirror frame will bring shape errors of the supporting surface of the optical element. Therefore, before the assembly and integration of the unit mirror group, the surface shape in the supporting state must be detected first. Various error components in the supporting surface shape can be measured through the surface shape interferometer, such as: astigmatism, coma, spherical aberration, three-leaf and four-leaf, etc., through theoretical calculation or simulation analysis of its Zernike coefficient , so as to obtain the compensation adjustment displacement of each driving mechanism. The adjustment values of each driving mechanism are respectively output and applied to the motion table, and then through the transmission of the support rod and the support surface, the optical element will produce a certain amount of force deformation to offset the influence caused by processing and assembly errors. The adjustment at this stage can be called static support surface shape compensation. After that, it is necessary to fix the optical element in the lens holder by precision welding, adhesive bonding or mechanical clamping, and then all the unit lens groups must be connected into a projection objective lens exposure optical system. Avoidance of assembly stress will also introduce varying degrees of surface error. The surface interferometer is also used to detect various error components of the surface shape of the unit mirror group. But at this time, since the optical element has been fixed in the mirror holder, the number of adjustment mechanisms and the output displacement required to compensate the same surface error due to stiffness coupling are more precise and difficult to control than those in the static support surface compensation stage. Therefore, real-time monitoring must be used to calibrate the adjustment amount and compensation effect in order to achieve the best results. The above compensations are all implemented for static surface shape errors. Finally, in the actual working process of the exposure optical system, a certain degree of image quality error will be introduced due to ambient temperature, air pressure changes and laser energy absorption. By analyzing and simulating the system image quality, the optical components that need to be compensated can be calculated. The image quality compensation of the exposure optical system can be realized by outputting the required displacement to the corresponding drive mechanism of the optical element. The above-mentioned factors that affect the surface shape accuracy of optical components are all called dynamic surface shape influencing factors.

The number of optical element supporting structures in the present invention is not limited to one in the exposure optical system 2 , and the number can be 4, 6 or all according to different applications. Apparently, the above-mentioned embodiments are only examples for clearly illustrating the present invention, rather than limiting the implementation of the present invention. For those of ordinary skill in the art, other changes or changes in different forms can be made on the basis of the above description. It is not necessary and impossible to exhaustively list all the implementation manners here. And these obvious changes or modifications derived from the spirit of the present invention are still within the protection scope of the present invention.

Claims (8)

1. a kind of optical element support structure, the optical element (22) for support unit microscope group (21), it is characterised in that including Microscope base (24), the microscope base (24) are the symmetrical mechanical component of circumference, and branch is stretched out at the interior ring microscope base center of the microscope base (24) Strut (246), the support bar (246) are radially respectively provided with flexibility, support bar (246) end in optical axis direction and microscope base Supporting surface (247) is provided with, the supporting surface (247) and the lower surface of optical element (22) are mutually matched, by optical element (22) it is fixed on the microscope base (24)；A sports platform (245), the sports platform are connected with the inside of the support bar (246) (245) it is connected by a guiding mechanism (243) with the outer shroud of microscope base (24), the guiding mechanism (243) is used for sports platform (245) Motion guide；The guiding mechanism (243) is connected formed with slit (244), the motion with the outer shroud of the microscope base (24) The wide constraint that the range of movement of platform (245) passes through the slit (244)；The supporting construction also includes multiple drive mechanisms (23), the microscope base (24) is formed with multiple positioning holes (248) radially extended along microscope base (24), the positioning hole (248) by Microscope base (24) external annular surface extends to be communicated with the slit (244), and the drive mechanism (23) inserts the positioning hole (248) In be fixed on this in microscope base (24), drive mechanism (23) end contacts with sports platform (245), the drive mechanism (23) End can export certain displacement and power, and be transferred to sports platform (245) and be allowed to produce radial displacement, the support bar (246) It is joined directly together with sports platform (245), radial displacement caused by the sports platform (245) can directly drive support bar (246) to produce Raw displacement and deformation, the support bar (246) can be by power and displacement transfers to optical element (22).

2. optical element support structure according to claim 1, it is characterised in that the top and bottom of the microscope base (24) Adpting flange (241) and lower adpting flange (242) are extended with respectively.

3. optical element support structure according to claim 1 or 2, is further characterized in that, the guiding mechanism (243) is The parallel―ordinal shift structure being symmetric, the parallel―ordinal shift structure can ensure sports platform (245) according to default footpath Moved back and forth to direction, the radial dimension of the guiding mechanism (243) is much smaller than its axial dimension and circumferential size so that its Rigidity on optical axis direction is much larger than its rigidity in radial directions, and then the guiding mechanism (243) is had radially The one-movement-freedom-degree in direction.

4. optical element support structure according to claim 1 or 2, is further characterized in that, the guiding mechanism (243) by Four slim plate spring groups are into four slim flat springs are relatively radially distributed in symmetric form two-by-two, to form a pair of parallel four Linkage.

5. optical element support structure according to claim 1 or 2, it is characterised in that the supporting surface (247) and optics The surface that element (22) lower surface is mutually matched is plane, concave surface or the one kind on convex surface, and support bar (246) quantity is more than etc. In 3, and the support bar (246) uniformly arranges around optical axis in circumferential.

6. a kind of unit microscope group, it is characterised in that including the light described in optical element (22) and claim 1-5 any one Learn element support structure.

7. a kind of exposure optical system, it is characterised in that stacked and formed as the unit microscope group described in some claims 6.

8. a kind of litho machine, it is characterised in that including the exposure optical system (2) and silicon described in mask platform (1), claim 7 Piece platform (3), the exposure optical system (2) are arranged between the mask platform (1) and silicon wafer stage (3), for by the mask Figure on platform (1) realizes perfect imaging on silicon wafer stage (3).