JP2017191291A - Liquid immersion holding mechanism and interference measurement device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid immersion holding mechanism and an interference measurement device capable of adjusting positional relationship between an optical component and an object and capable of suppressing evaporation of immersion medium and preventing mixing of foreign matter while maintaining an immersion state of the optical component.SOLUTION: The liquid immersion holding mechanism includes: an immersion object lens 1; a container 5 that covers a front end 1a of the immersion object lens and holds a liquid 6 to immerse the front end; a stage 50 which can change the relative position between an object 7, which is disposed at the bottom 5a of the container facing to the front end of the immersion object lens, and the front end of the immersion object lens; and an elastic film 10 that connects the side 4 of the immersion object lens and the container and seals the liquid in the container.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an immersion holding mechanism for holding a liquid that is an immersion medium for maintaining an immersion state of an optical component that requires immersion during observation in an optical instrument such as a microscope, and an immersion holding mechanism. The present invention relates to an interference measuring apparatus.

  In a microscope or the like used for creating a semiconductor circuit or observing a biological sample, the space between the observation lens and the object to be measured (object) is filled with an immersion medium such as water instead of air, so-called immersion state. And It is known that such an immersion state can provide effects such as improved resolution and unnecessary contrast of the air layer to improve contrast.

  Conventionally, as an immersion holding mechanism for keeping an optical component such as a lens in an immersion state, as disclosed in Patent Document 1, a box or a cylindrical structure is provided at the tip of the lens, and the liquid is held therein. There is a type in which an immersion medium is sealed, and the immersion medium is kept at the tip of the lens to maintain the state.

  FIG. 9 is a view showing a conventional immersion holding mechanism described in Patent Document 1. In FIG.

  In FIG. 9, the conventional immersion holding mechanism includes an immersion lens 25 having a hole 26, a container 27 for holding an immersion medium 28, and an object 29 to be measured fixed in the container 27. ing. As an optical system including the immersion holding mechanism, it is assumed that an observer 32 is provided outside the mechanism in addition to the half mirror 30 and the light source 31.

  Similarly, as disclosed in Patent Document 2, as a mechanism for maintaining the immersion state of the optical component, a liquid supply mechanism is provided near the tip of the objective lens so that the immersion medium lost due to evaporation or the like is always kept. There is something to be supplied.

  FIG. 10 is a diagram showing a conventional immersion holding mechanism described in Patent Document 2. As shown in FIG.

  In FIG. 10, the conventional immersion holding mechanism includes a liquid supply mechanism 36 including a liquid supply path 34 and a liquid recovery path 35 in the immersion lens 33, and an immersion part at the tip of the immersion lens 33. An immersion medium is supplied to and recovered from the vicinity 37.

WO07 / 116647 JP 2005-345597 A

  However, in the configuration of Patent Document 1, the portion surrounded by the lower lens surface 25a in the liquid immersion state of the immersion lens 25 and the container 27 is not completely sealed, and the immersion medium 28 has the hole 26. Or the immersion medium 28 evaporates, or dust or foreign matter is mixed into the immersion medium 28 from the outside of the component, so that the immersion medium 28 is replenished or replaced. Alternatively, the inside of the container 27 needs to be frequently cleaned, and a good optical observation state cannot be maintained for a long time due to contamination of foreign matter in the container 27 or the immersion medium 28. Further, the immersion lens 25 and the container 27 are fixed via the abutting surface 27a and the lower lens surface 25a, and the posture of the object to be measured 29 is fixed. It is difficult to perform relative posture adjustment with the object 29.

  On the other hand, in the configuration of Patent Document 2, since the immersion state of the lens is continuously maintained by replenishing the evaporated immersion medium, the vicinity of the liquid immersion portion 37 is not sealed. Similarly, there is a problem of foreign matter mixed in the immersion medium.

  The present invention solves the above-described conventional problem, while maintaining the immersion state of the optical component, suppressing evaporation of the immersion medium, and preventing foreign matter from entering the immersion medium. It is an object of the present invention to provide an immersion holding mechanism and an interference measuring apparatus that can adjust the position of the liquid crystal.

In order to achieve the above object, an immersion holding mechanism according to one aspect of the present invention includes an immersion objective lens,
A container that covers the tip of the immersion objective lens and holds the liquid so that the tip is immersed;
A stage capable of changing a relative position between an object placed at the bottom of the container and at a position facing the tip of the immersion objective lens and the tip of the immersion objective lens;
An elastic membrane that connects the side of the immersion objective lens and the container and seals the liquid in the container.

In order to achieve the object, an interference measurement apparatus according to another aspect of the present invention is an interference measurement apparatus that measures the object by causing the measurement light irradiated on the object to interfere with a reference light,
The immersion holding mechanism according to the above aspect is provided in the optical path of the reference light.

  As described above, according to the liquid immersion holding mechanism and the interference measuring apparatus according to the aspect of the present invention, while maintaining the liquid immersion state of the optical component, the evaporation of the liquid immersion medium is suppressed, and foreign matter is mixed into the liquid immersion medium. In order to prevent this, it is possible to adjust the position between the optical component and the object while blocking the immersion portion including the immersion medium from the outside air environment.

The figure of the immersion holding mechanism in Embodiment 1 of this invention The figure which shows the arrangement | positioning relationship between the immersion objective lens and rubber film in Embodiment 1 of this invention The figure which expanded the fitting part of the immersion objective lens and rubber film in Embodiment 1 of this invention The figure of the immersion holding mechanism in Embodiment 2 of this invention The figure which expanded the fitting part of the immersion objective lens and O-ring in Embodiment 2 of this invention The figure of the immersion holding mechanism in Embodiment 3 of this invention The figure which expanded the fitting part of the immersion objective lens and sealing member in Embodiment 4 of this invention Schematic of an interference measuring apparatus provided with an immersion holding mechanism in Embodiment 1 of the present invention The figure which shows the structure of the conventional liquid immersion holding | maintenance mechanism described in patent document 1 The figure which shows the structure of the conventional liquid immersion holding | maintenance mechanism described in patent document 2

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
FIG. 1 is a configuration diagram of an immersion holding mechanism 51 for an optical component according to Embodiment 1 of the present invention.

  The immersion holding mechanism 51 includes an immersion objective lens 1, a container 5, a stage 50, and an elastic film (for example, rubber film 10).

  The immersion objective lens 1 is arranged along the optical axis direction 17 with the tip 1a facing downward.

  The container 5 covers the tip 1a of the immersion objective lens 1 and holds a liquid (for example, an immersion medium 6) so that the tip 1a is immersed.

  The stage 50 includes, for example, a focus stage 3 and a tilt stage 8, and supports the immersion objective lens 1 and an object (for example, a mirror 7), and a tip 1 a of the immersion objective lens 1 at the bottom 5 a of the container 5. And the relative position between the mirror 7 disposed at a position facing the optical axis direction 17 and the tip of the immersion objective lens 1 can be changed.

  The elastic film is a film-like member, which is made of, for example, a rubber film 10, and connects the side part (immersion objective lens cylindrical part 4) of the immersion objective lens 1 and the container 5 to connect the liquid 6 in the container 5. To seal.

  Hereinafter, the liquid immersion holding mechanism 51 will be described in more detail.

  In FIG. 1, a base plate 16 is disposed in parallel with the optical axis 17 of the immersion objective lens 1, the focus stage 3 is attached to one end (for example, the upper end of FIG. 1), and the other end (for example, the lower end of FIG. 1). The tilting stage 8 is fixed to the first through the spacers 15 to form the stage 50, and the entire structure functions as one optical component unit.

  In FIG. 1, the immersion objective lens 1 is screwed and fastened to an objective lens mount 2, and the objective lens mount 2 is fixed to a focus stage 3. In FIG. 1, a lens group constituting the immersion objective lens is mounted inside the immersion objective lens 1. The focus stage 3 includes a stage moving unit 3a to which the objective lens mount 2 is fixed and a stage fixing unit 3b. The stage moving unit 3a is moved in the moving direction with respect to the stage fixing unit 3b fixed to the base plate 16. It can be moved in the direction indicated by the arrow 3c. For this reason, the entire configuration in which the immersion objective lens 1 and the objective lens mount 2 are combined can be finely adjusted by the focus stage 3 in the vertical direction of FIG.

  On the inner bottom surface 5b of the bottom 5a of the immersion container 5, a mirror 7 is installed so as to protrude from the inner bottom surface 5b. The mirror 7 includes a mirror surface 7a on the surface (for example, the upper surface in FIG. 1) facing the tip 1a of the immersion objective lens 1. An immersion medium 6 is placed inside the immersion container 5, and the tip 1 a of the immersion objective lens 1 is immersed in the immersion medium 6 and is in a water immersion state. The mirror surface 7 a of the mirror 7 is disposed so as to protrude upward from the immersion container bottom surface 5 b and is immersed in the immersion medium 6. The tip 1 a of the immersion objective lens 1 and the mirror 7 are immersed in the immersion medium 6. The mirror surface 7a faces. The lower end of the frustoconical shape at the bottom of the immersion vessel 5 (for example, the lowermost end in FIG. 1) is fixed to the tilt stage 8 by a screw 9, and an arrow indicated by an inclination movement direction 8c by adjusting the tilt adjustment knob 8a. 1, that is, tilted in the left-right direction in FIG. 1, and tilted in the front-rear direction in FIG. 1 by adjusting the tilt adjustment knob 8 b. In addition, illustration of the inclination movement direction by adjustment of the tilt adjustment knob 8b is omitted.

  A circular thin film-like rubber film 10 is fitted on the outer periphery of the immersion objective lens cylindrical portion 4. As shown in FIGS. 1 and 2, a circular hole 10a having a size through which the immersion objective lens cylindrical portion 4 passes is provided in the central portion of the rubber film 10, and the immersion objective lens 1 is provided in the hole 10a. The tip part and the immersion objective lens cylindrical part 4 are passed through. The peripheral portion of the rubber film 10 is fixed by being sandwiched between an annular rubber film fixing member 11 and a plurality of rubber film fixing screws 12 at an annular upper surface edge 5c of the immersion container 5. The objective lens 1 and the rubber film 10 are configured to cover the immersion container 5. As shown in FIG. 3, a gap formed in the fitting portion 19 between the immersion objective lens cylindrical portion 4 and the rubber film 10 is filled with a caulking material 13 as shown in FIG. A groove 14 is provided inside the immersion container 5 and along the inner wall surface in the vicinity of the upper surface edge above the bottom 5a so that foreign matter can be accumulated in the groove 14 as will be described later. ing.

  Further, the immersion medium 6 is held only in such an extent as to cover the groove 14 in the internal space of the immersion container 5 in which the immersion medium 6 is sealed with the rubber film 10 and the caulking material 13. The immersion medium 6 is not held in the immersion container 5 until it comes into contact with. By configuring in this way, a gas layer 20 as an example of a gas layer is secured between the liquid surface of the immersion medium 6 and the lower surface of the rubber film 10, and is compressed and expanded more than the liquid as will be described later. An easy buffering effect by gas is achieved.

  In this embodiment, an external optical system 53 (see FIG. 8) such as another observation optical system or an interference optical system is positioned above the optical incident direction 18 along the optical axis 17 of the immersion objective lens 1 in the figure. Is assumed to exist. Accordingly, it is assumed that the measurement light is incident from the external optical system 53 into the immersion objective lens 1 along the optical axis 17 in the light incident direction 18.

  FIG. 2 simply shows the positional relationship between the immersion objective lens 1 and the rubber film 10 described above in the first embodiment of the present invention. In FIG. 2, it can be seen that the cylindrical portion 4 of the immersion objective lens 1 penetrates the hole 10 a provided in the central portion of the rubber film 10.

  FIG. 3 is an enlarged view of the vicinity of the fitting portion 19 between the immersion objective lens 1 and the rubber film 10 in FIG. 1 in the first embodiment of the present invention. In FIG. 3, it can be seen that the rubber film 10 is fitted on the outer peripheral surface of the immersion objective lens cylindrical portion 4, and the slight gap is filled with the caulking material 13.

  In an external optical system 53 such as a general imaging optical system or interference optical system, the relative distance in the direction of the optical axis 17 between the immersion objective lens 1 and the mirror 7 in FIG. In many cases, it is necessary to strictly adjust the inclination of the mirror surface 7a with respect to one optical axis 17. For example, in the former case, it is necessary to make the mirror surface 7 a coincide with the focal position of the immersion objective lens 1 with an accuracy of several μm or less, and in the latter case, the mirror surface with respect to the optical axis 17 of the immersion objective lens 1. It is necessary to match the normal line of 7a at an angle of several minutes or less. However, if the components are simply combined, the required adjustment accuracy is not far, so that a fine adjustment step is always performed after combining the components.

  According to this configuration, the immersion container 5 and the immersion objective lens 1 are connected by the flexible rubber film 10. For this reason, the immersion objective lens 1 is moved by the focus stage 3 without applying an excessive load to each constituent member while keeping the water immersion portion of the tip 1a of the immersion objective lens 1 sealed in the immersion vessel 5. And the mirror 7 can be finely adjusted, and the tilt between the immersion objective lens 1 and the mirror 7 by the tilt stage 8 can be finely adjusted. In general, when the immersion medium 6 is sealed in the immersion container 5, the rubber film 10 or the immersion objective lens 1 serving as a lid for sealing the immersion container 5 becomes difficult to move, but the immersion medium 6 is sealed. By providing the gas layer 20 in the inner space of the immersion container 5 that is being operated, the gas that is easier to compress and expand than the liquid exhibits a buffering effect, and the rubber film 10 or the immersion objective lens 1 moves during the fine adjustment operation. There is an effect which becomes easy. In addition, when this configuration is used for the reference surface side optical system of the linic interferometer, the distance between the immersion objective lens 1 and the mirror surface 7a, which is necessary for the interference fringe scanning, can be reduced. This is also effective in the case of performing an operation that periodically changes the wavelength. In that case, for example, even if the spacer 15 is replaced with a fine movement stage that is driven by a piezo element, the operation of changing the direction of the optical axis 17 of the liquid immersion container 5 can be easily performed due to the flexibility of the rubber film 10.

  When the immersion medium 6 is injected into the immersion container 5 and the immersion medium 6 is sealed with the rubber film 10, the immersion objective lens 1, the caulking material 13, the rubber film fixing member 11, and the rubber film fixing screw 12, Is sealed with care so that foreign matter such as dust or lint does not adhere to the inside of the immersion container 5, the tip of the mirror 7 and the immersion objective lens 1, and the lower surface of the rubber film 10. Even if a small amount of foreign matter has entered the immersion medium 6, by providing the groove 14, the foreign matter mixed in the immersion medium 6 accumulates in the groove 14 and minimizes contamination of the immersion medium 6. be able to. Foreign matter heavier than the immersion medium 6 settles on the bottom surface 5 b, and foreign matter lighter than the immersion medium 6 floats on the immersion medium 6. The settled foreign matter stays on the bottom surface 5b of the immersion container which is lower than the mirror surface 7a of the mirror 7, so that it does not affect optically. The foreign matter floating in the immersion medium 6 easily collects on the inner wall surface of the immersion container 5 due to the surface tension of the liquid in the immersion medium 6, and floats in the liquid in the immersion medium 6 by providing a groove 14 in the vicinity thereof. The foreign matter is retained in the groove 14 so as not to float in the immersion medium 6 again. Therefore, by filling the immersion container 5 with the immersion medium 6 to a degree slightly beyond the wall of the groove 14, foreign matter accumulated in the groove 14 is prevented from returning to the immersion medium 6 again. Is preferred.

  With this configuration, it is possible to suppress the evaporation of the immersion medium 6 and prevent foreign matter from entering the immersion medium 6 for an optical component that requires an immersion state. It is possible to adjust the posture such as the distance or relative inclination between the optical component and the object to be measured (object) while maintaining the immersion state.

  The immersion medium 6 may be an immersion medium used in a normal immersion lens. For example, water or oil or an organic solvent may be used, or a small amount of additives may be mixed for preserving the medium. May be.

  The rubber film 10 may be a film-like material having flexibility such as general rubber. For the purpose of suppressing evaporation of the immersion medium 6, a material having a low gas permeability is desirable. , Nitrile rubber, or butyl rubber.

  The gas layer 20 may be air, nitrogen, or carbon dioxide as long as it is a general gas. A gas having low solubility in the immersion medium 6 is desirable because it is in contact with the immersion medium 6, and a gas that is difficult to permeate the rubber film 10 is desirable.

  The volume of the gas layer 20 is desirably 5 to 50% of the total volume inside the immersion container 5 that becomes a sealed space when the rubber film 10 and the immersion objective lens 1 are attached to the immersion container 5. . Further, the gas pressure of the gas layer 20 at that time is preferably within the range of about ± 10% of the external pressure of the immersion container 5, and more preferably if it is equal to the external pressure of the immersion container 5, Usually, it is desirable to be about atmospheric pressure.

  Furthermore, in order to reduce the risk of contamination of foreign matter into the immersion container 5, the gas pressure of the gas layer 20 is set so that the inside of the immersion container 5 is not negative with respect to the external pressure (positive pressure). That is, the pressure of the gas layer 20 is higher than the pressure outside the container. More specifically, the gas layer 20 is preferably set to a pressure of + 10% of the external pressure.

  Note that the elastic modulus of the elastic film (for example, the rubber film 10) is larger than the elastic modulus of the caulking material 13 and smaller than the elastic modulus of the side portion 4 of the immersion objective lens 1. Thereby, it is possible to perform optical adjustment while realizing high-accuracy sealing of the liquid (for example, the immersion medium 6).

  In addition, although demonstrated using the mirror 7 as an example of a target object, if it is a to-be-measured member with which the combination with the immersion objective lens 1 can be considered, it will not be restricted to a mirror.

  The liquid immersion holding mechanism 51 may be incorporated in the interferometer. Specifically, as shown in FIG. 8, a light source 56 that emits measurement light 54A and reference light 55A, a camera 57 that captures interference fringes, and an interference optical system such as a beam splitter 60 and a reflection mirror 61 are provided. While being configured in the external optical system 53, the liquid immersion holding mechanisms 51 and 51D can be arranged in the optical path of the reference light 55A and the optical path of the measurement light 54A, respectively. At this time, the mirror 7 is applied to the object of one immersion holding mechanism 51, and the semiconductor circuit or biological sample which is the object to be measured 59 is applied to the object of the other immersion holding mechanism 51D having the measurement objective lens 58. You may apply. In such a configuration, the reference light 55 </ b> A reflected downward by the beam splitter 60 among the emitted light emitted from the light source 56 irradiates the target mirror 7 of the one immersion holding mechanism 51. . The reference light 55 </ b> A irradiated on the mirror 7 is reflected by the mirror 7, travels in the reverse direction as reflected light 55 </ b> B, passes through the beam splitter 60, and enters the camera 57. On the other hand, the measurement light 54A that has passed through the beam splitter 60 out of the emitted light emitted from the light source 56 passes through the measurement objective lens 58 of the other immersion holding mechanism 51D and irradiates the object 59 to be measured. . The measurement light 54 </ b> A that irradiates the measurement object 59 travels in a reverse direction as reflected light 54 </ b> B reflected by the measurement object 59, passes through the beam splitter 60, and enters the camera 57. Interference fringes are formed by the two reflected lights 54B and 55B entering the camera 57 and captured by the camera 57, and the object 59 to be measured is measured.

  In this way, the interference measuring device 52 that measures the object 7 by causing the measurement light 54 and the reference light 55 irradiating the objects 7 and 59 to interfere with each other in the optical path of the reference light 55 ( For example, the interference measuring device 52 provided with the immersion holding mechanism 51 below the external optical system 53 on the optical axis 17 can be realized. The interference measuring device 52 can perform an operation of periodically changing the distance between the tip 1a of the immersion objective lens 1 and the mirror 7 by a distance of about the wavelength of the light used for the measurement. For this reason, interference fringe scanning generally used at the time of interference measurement is enabled. When applied to the interference measuring apparatus, the immersion holding mechanism 51 (or the immersion holding mechanism 51B or 51C of another embodiment) using the mirror 7 as an object of reference light is suitable.

  As described above, according to the first embodiment, the side 4 of the immersion objective lens 1 and the container 5 are connected by the rubber film 10 so that the immersion medium 6 is sealed in the container 5. Yes. As a result, the liquid containing the immersion medium 6 is used to suppress evaporation of the immersion medium 6 and prevent foreign matter from entering the immersion medium 6 while maintaining the immersion state of the optical component (for example, the immersion objective lens 1). It is possible to adjust the position between the optical component and the object 7 while blocking the immersion portion from the outside air environment.

(Embodiment 2)
FIG. 4 is a configuration diagram of an immersion holding mechanism 51B for optical components according to Embodiment 2 of the present invention.

  In FIG. 4, the same components as those in FIG. In FIG. 4, an O-ring 21 is fitted on the immersion objective lens cylindrical portion 4 of the immersion objective lens 1, and the rubber film 10 and the O-ring 21 are joined by a caulking material 13. The inner diameter of the O-ring 21 is made smaller than the diameter of the immersion objective lens cylindrical portion 4, and the O-ring 21 is made of an elastic material such as rubber. Then, when the O-ring 21 is fitted to the immersion objective lens cylindrical portion 4, the O-ring 21 does not come off naturally due to the tension of the O-ring 21 itself, and is brought into close contact with the immersion objective lens cylindrical portion 4. With such a configuration, the inside of the immersion container 5 is sealed by the O-ring 21, the caulking material 13, and the rubber film 10, and the O-ring 21, the caulking material 13, and the rubber film 10 are integrally sealed. Is functioning as In addition, even if the O-ring 21 is disposed on the upper side or the lower side of the rubber film 10, the effect is not changed.

  FIG. 5 is an enlarged view of the vicinity of the fitting portion 22 between the immersion objective lens 1 and the O-ring 21 in FIG. 4 in the second embodiment of the present invention.

  In FIG. 5, an O-ring 21 is fitted and closely attached to the immersion objective lens cylindrical portion 4, and a slight gap with the rubber film 10 is filled with a caulking material 13, so that the opening of the immersion container 5 is provided. It can be seen that hermetic sealing is realized.

  With this configuration, the caulking material 13 is not directly bonded to the immersion objective lens cylindrical portion 4 while having the function realized in the first embodiment, so that the assembly is easy and the maintainability is improved. The immersion holding mechanism 51B can be realized.

(Embodiment 3)
FIG. 6 is a configuration diagram of an immersion holding mechanism 51C for an optical component according to Embodiment 3 of the present invention.

  In FIG. 6, the same components as those in FIG. In FIG. 6, the immersion objective lens cylindrical portion 4 is fitted in the perforated portion of the rubber film-like sealing member 23. A ring-shaped ring portion 23a having a circular cross section having a diameter larger than the thickness of the sealing member 23 is integrally formed at the edge of the hole opening portion of the sealing member 23, such as an O-ring. The inner diameter of the ring portion 23a is made smaller than the diameter of the immersion objective lens cylindrical portion 4, and the sealing member 23 is made of an elastic material such as rubber. Then, when the perforated portion of the sealing member 23 is fitted into the immersion objective lens cylindrical portion 4, the sealing member 23 does not come off naturally due to the tension of the sealing member 23 itself, and comes into close contact with the immersion objective lens cylindrical portion 4. deep.

  FIG. 7 is an enlarged view of the vicinity of the ring portion 23a of the fitting portion 24 between the immersion objective lens 1 and the sealing member 23 in FIG. 6 in the third embodiment of the present invention.

  In FIG. 7, the ring portion 23 a of the sealing member 23 is fitted into the immersion objective lens cylindrical portion 4, and the ring portion 23 a that is the edge of the hole portion of the sealing member 23 is in close contact with the immersion objective lens cylindrical portion 4. It can be seen that the sealing of the opening of the immersion container 5 is realized.

  With this configuration, the O-ring 21 and the rubber film 10 are bonded with the caulking material 13 to form the sealing member for sealing while having the function realized in the second embodiment. By using the sealing member 23 with an integrated function, it is possible to realize an immersion holding mechanism 51C that improves the reliability of the sealing function, reduces the number of parts, and is easy to handle.

  In addition, it can be made to show the effect which each has by combining arbitrary embodiment or modification of the said various embodiment or modification suitably. In addition, combinations of the embodiments, combinations of the examples, or combinations of the embodiments and examples are possible, and combinations of features in different embodiments or examples are also possible.

  The liquid immersion holding mechanism and the interference measuring apparatus according to the above aspect of the present invention prevent liquid from evaporating the liquid immersion medium and mixing foreign matter into the liquid immersion medium when using an optical component that needs to maintain the liquid immersion state. Maintenance of the immersion holding mechanism can be simplified and facilitated. Therefore, the liquid immersion holding mechanism and the interference measurement apparatus according to the above aspect of the present invention enable fine adjustment of the distance or inclination between the optical component and the object that need to maintain the liquid immersion state, The present invention can be applied to the use of an optical system configuration of an optical apparatus that requires a liquid immersion state widely, such as a reference surface portion such as an interferometer.

DESCRIPTION OF SYMBOLS 1 Immersion objective lens 1a The tip of an immersion objective lens 2 Objective lens mount 3 Focus stage 3a Stage moving part 3b Stage fixing part 4 Immersion objective lens cylindrical part 5 Immersion container 5a Immersion container bottom 5b Immersion container bottom 5c Upper surface edge of immersion container 6 Immersion medium 7 Mirror 7a Mirror surface 8 tilt stage 9 Screw 10 Rubber film 11 Rubber film fixing member 12 Rubber film fixing screw 13 Caulking material 14 Groove 15 Spacer 16 Base plate 17 Optical axis 18 Light incident Direction 19 Fitting portion 20 Gas layer 21 O-ring 22 Fitting portion 23 Sealing member 24 Fitting portion 25 Immersion lens 25a Lower lens surface 26 Hole 27 Container 27a Abutting surface 28 Immersion medium 29 DUT 30 Half mirror 31 Light source 32 Observer 33 Immersion lens 34 Liquid supply path 35 Liquid recovery Path 36 Liquid supply mechanism 37 Near immersion part 50 Stage 51, 51B, 51C Immersion holding mechanism 52 Interference measuring device 53 External optical system 54A Measurement light 54B Reflected light of measurement light 55A Reference light 55B Reflected light of reference light 56 Light source 57 Camera 58 Measuring objective lens 59 Object to be measured 60 Beam splitter 61 Reflecting mirror

Claims (10)

An immersion objective lens;
A container that covers the tip of the immersion objective lens and holds the liquid so that the tip is immersed;
A stage capable of changing a relative position between an object placed at the bottom of the container and at a position facing the tip of the immersion objective lens and the tip of the immersion objective lens;
An immersion holding mechanism comprising: an elastic film that connects a side portion of the immersion objective lens and the container and seals the liquid in the container.   The liquid immersion holding mechanism according to claim 1, further comprising a gas layer between the liquid and the elastic film in the container.   The immersion holding mechanism according to claim 2, wherein the object is a mirror.   The immersion holding mechanism according to claim 3, wherein a gap between the side portion of the immersion objective lens and the elastic film is filled with a caulking material.   The immersion holding mechanism according to claim 4, wherein an elastic modulus of the elastic film is larger than an elastic modulus of the caulking material and smaller than an elastic modulus of the side portion of the immersion objective lens.   The liquid immersion holding mechanism according to claim 5, further comprising a groove in an inner wall surface of the container above the bottom of the container.   The immersion holding mechanism according to any one of claims 1 to 6, wherein the side portion of the immersion objective lens and the elastic film are connected via an O-ring.   The immersion holding mechanism according to claim 2, wherein a volume of the gas layer is 5 to 50% of a total volume inside the container.   The liquid immersion holding mechanism according to claim 2, wherein a pressure of the gas layer is higher than a pressure outside the container. An interference measuring apparatus for measuring the object by causing the measurement light irradiated on the object to interfere with a reference light,
An interference measurement apparatus comprising the liquid immersion holding mechanism according to claim 1 in an optical path of the reference light.

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