Patent Publication Number: US-2022221705-A1

Title: Optical apparatus and solid immersion lens

Description:
TECHNICAL FIELD 
     The present disclosure relates to an optical apparatus and a solid immersion lens. 
     BACKGROUND 
     As a method for observing an object, a method in which a solid immersion lens is brought into contact with the object and a magnified image of the object is acquired to observe the object is known. For example, Japanese Unexamined Patent Application, First Publication No. 2019-197097 describes a method in which a meta-solid immersion lens having a plurality of antenna parts disposed at a period smaller than a wavelength of incident light is prepared and the plurality of antenna parts are brought into contact with an object to acquire a magnified image of the object with high spatial resolution. 
     SUMMARY 
     The meta-solid immersion lens described in Patent Document 1 is effective in that a solid immersion lens can be made thinner, but great care must be taken not to damage a plurality of antenna parts when the plurality of antenna parts are brought into contact with an object. 
     Therefore, it is an objective of the present disclosure to provide an optical apparatus including a solid immersion lens in which thinning and easy handling are realized, and such a solid immersion lens. 
     An optical apparatus of one aspect of the present disclosure includes a support part configured to support an object, a solid immersion lens configured to be brought into contact with the object supported by the support part, and an optical device disposed at a position opposite to the support part with respect to the solid immersion lens on an optical path passing through the solid immersion lens, wherein the solid immersion lens includes a base part having a first surface to be brought into contact with the object and a second surface opposite to the first surface, and a meta-lens disposed on the second surface. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram of an optical apparatus of one embodiment. 
         FIG. 2  is a cross-sectional view of a solid immersion lens unit illustrated in  FIG. 1 . 
         FIG. 3  is a front view of a solid immersion lens illustrated in  FIG. 2 . 
         FIG. 4  is a bottom view of the solid immersion lens illustrated in  FIG. 2 . 
         FIG. 5  is a plan view of the solid immersion lens illustrated in  FIG. 2 . 
         FIG. 6  is a schematic view of a meta-lens illustrated in  FIG. 3 . 
         FIG. 7  is a view for explaining that an effective refractive index has a distribution in the meta-lens illustrated in  FIG. 3 . 
         FIGS. 8A and 8B  are views for explaining a method of forming the meta-lens of the solid immersion lens illustrated in  FIG. 2 . 
         FIGS. 9A and 9B  are views for explaining a method of forming the meta-lens of the solid immersion lens illustrated in  FIG. 2 . 
         FIGS. 10A and 10B  are views for explaining a method of forming the meta-lens of the solid immersion lens illustrated in  FIG. 2 . 
         FIGS. 11A and 11B  are views for explaining a method of forming a first portion of the solid immersion lens illustrated in  FIG. 2 . 
         FIGS. 12A and 12B  are views for explaining a method of forming a first portion of the solid immersion lens illustrated in  FIG. 2 . 
         FIGS. 13A and 13B  are views for explaining a method of forming a first portion of the solid immersion lens illustrated in  FIG. 2 . 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. Further, in each of the drawings, the same or corresponding portions will be denoted by the same reference signs, and duplicate description thereof will be omitted. 
     [Configuration of Optical Apparatus] 
     As illustrated in  FIGS. 1 and 2 , an optical apparatus  1  is an apparatus for observing, for example, a semiconductor device (object)  11  included in a mold-type semiconductor device  10 . Specifically, the optical apparatus  1  is a semiconductor failure analysis apparatus for analyzing for failures in the semiconductor device  11  by, for example, acquiring a magnified image of the semiconductor device  11  and inspecting internal information of the semiconductor device  11  on the basis of the magnified image. 
     The mold-type semiconductor device  10  is one in which the semiconductor device  11  is molded with a resin  14 . The internal information of the semiconductor device  11  includes information on, for example, a circuit pattern of the semiconductor device  11 , light emission from the semiconductor device  11 , and heat generation in the semiconductor device  11 . As the light emission, light emission based on a defect of the semiconductor device  11  and transient light emission associated with a switching operation of a transistor in the semiconductor device  11  can be exemplified. As the heat generation, heat generation based on a defect in the semiconductor device  11  can be exemplified. 
     The semiconductor device  11  includes a semiconductor substrate  12  and an integrated circuit  13 . The integrated circuit  13  is formed on a surface  12   a  of the semiconductor substrate  12 . The semiconductor device  11  is embedded in the resin  14  so that a back surface  12   b  of the semiconductor substrate  12  is exposed. The mold-type semiconductor device  10  is disposed on a stage (support part)  6  so that the back surface  12   b  of the semiconductor device  11  faces upward. That is, the stage  6  supports the semiconductor device  11 . As an example, the semiconductor substrate  12  is a silicon substrate, and in this case, a refractive index of the semiconductor substrate  12  is about 3.5. 
     The optical apparatus  1  includes an observation unit  1   a , a control unit  1   b , and an analysis unit  1   c . The observation unit  1   a  observes the semiconductor device  11 . The control unit  1   b  controls an operation of each part of the observation unit  1   a . The analysis unit  1   c  performs processing, instructions, and the like needed for analyzing the semiconductor device  11 . 
     The observation unit  1   a  includes a solid immersion lens unit  2 , a high-sensitivity camera (optical apparatus, photodetector)  3 , a laser scanning optical system (LSM) unit  4 , an optical system  20 , and an XYZ stage  7 . The solid immersion lens unit  2  is a lens unit for observing the semiconductor device  11 . The high-sensitivity camera  3  and the LSM unit  4  are means for observing the semiconductor device  11 . The XYZ stage  7  is a mechanism for moving the high-sensitivity camera  3  and the LSM unit  4  in an X direction, a Y direction, and a Z direction. The X and Y directions are horizontal directions perpendicular to each other, and the Z direction is a vertical direction with respect to an XY plane. 
     The solid immersion lens unit  2  includes a solid immersion lens  60  and a solid immersion lens holder (holding part)  8 . The solid immersion lens  60  is brought into contact with the semiconductor device  11  supported by the stage  6 . The solid immersion lens  60  has a first surface  61   a  to be brought into contact with the semiconductor device  11  (specifically, the back surface  12   b  of the semiconductor substrate  12 ). The first surface  61   a  is a surface (here, a lower surface) on the semiconductor device  11  side among outer surfaces of the solid immersion lens  60 . 
     The solid immersion lens holder  8  holds the solid immersion lens  60  so that the solid immersion lens  60  is positioned below an objective lens  21  of the optical system  20 . The solid immersion lens holder  8  is formed of, for example, a metal such as aluminum. The solid immersion lens holder  8  includes a cylindrical main body part  8   a  and a lens holding part  8   b . The main body part  8   a  is attached to a lower end portion of the objective lens  21 . The lens holding part  8   b  is provided at an end portion of the main body part  8   a  on the semiconductor device  11  side (a side opposite to the objective lens  21 ) and holds the solid immersion lens  60 . 
     The main body part  8   a  passes infrared laser light L output from a light source  4   a  of the LSM unit  4  to the solid immersion lens  60  side and passes light reflected by the semiconductor device  11  and emitted from the solid immersion lens  60  to the objective lens  21  side. The main body part  8   a  includes a circumferential wall part  8   c  and an extension wall part  8   d . The circumferential wall part  8   c  is a cylindrical portion configured to be externally fitted to the lower end portion of the objective lens  21  and screwed to the lower end portion of the objective lens  21 . The extension wall part  8   d  is a portion configured to extend between the circumferential wall part  8   c  and the lens holding part  8   b . A center of the solid immersion lens holder  8  can be positioned on an optical axis A of the objective lens  21  by screwing the circumferential wall part  8   c  and the lower end portion of the objective lens  21  together. Thereby, a position of the solid immersion lens  60  held by the solid immersion lens holder  8  can be adjusted by driving of the XYZ stage  7 . 
     The lens holding part  8   b  has a clearance (gap) with respect to the solid immersion lens  60 . Thereby, the lens holding part  8   b  holds the solid immersion lens  60  in a state of being able to swing in a state before the solid immersion lens  60  comes into contact with the semiconductor device  11 . When the first surface  61   a  of the solid immersion lens  60  is brought into contact with the back surface  12   b  of the semiconductor substrate  12  from this state, the solid immersion lens  60  swings with respect to the lens holding part  8   b , and thereby the first surface  61   a  follows the back surface  12   b  of the semiconductor substrate  12  to be in close contact therewith. Therefore, for example, even when the back surface  12   b  of the semiconductor substrate  12  is inclined with respect to the optical axis A, the first surface  61   a  can follow the back surface  12   b  of the semiconductor substrate  12  to be satisfactorily in close contact therewith. 
     The high-sensitivity camera  3  is disposed at a position opposite to the stage  6  with respect to the solid immersion lens  60  on an optical path passing through the solid immersion lens  60 . The high-sensitivity camera  3  outputs image data for creating an image such as a circuit pattern of the semiconductor device  11 . The high-sensitivity camera  3  includes a CCD area image sensor, a CMOS area image sensor, an InGaAs area image sensor, or the like. 
     The LSM unit  4  includes the light source (optical device)  4   a  and a photodetector (optical device)  4   b . The light source  4   a  and the photodetector  4   b  are disposed at positions opposite to the stage  6  with respect to the solid immersion lens  60  on the optical path passing through the solid immersion lens  60 . The light source  4   a  emits infrared laser light. The light source  4   a  may be, for example, a semiconductor laser. The photodetector  4   b  detects reflected light from the semiconductor device  11 . The photodetector  4   b  may be, for example, an avalanche photodiode, a photodiode, or a photomultiplier tube. The LSM unit  4  generates image data for creating an image such as a circuit pattern of the semiconductor device  11  by scanning the semiconductor device  11  with infrared laser light in the X and Y directions. 
     The optical system  20  includes the objective lens  21 , a camera optical system  22 , and an LSM unit optical system  23 . The objective lens  21  is disposed at a position between the solid immersion lens  60  and the LSM unit  4  on the optical path passing through the solid immersion lens  60 . The position at which the objective lens  21  is disposed is also a position between the solid immersion lens  60  and the high-sensitivity camera  3  on the optical path passing through the solid immersion lens  60 . A plurality of objective lenses  21  having different magnifications are provided and can be switched between. The objective lens  21  includes a correction ring  24 . When the correction ring  24  is adjusted, a focus of the objective lens  21  can be accurately aligned with a predetermined portion of the semiconductor device  11 . 
     The camera optical system  22  guides reflected light from the semiconductor device  11  that has passed through the solid immersion lens  60  and the objective lens  21  to the high-sensitivity camera  3 . The LSM unit optical system  23  reflects infrared laser light from the LSM unit  4  to the objective lens  21  side by a beam splitter (not illustrated) and guides it to the semiconductor device  11 . The LSM unit optical system  23  guides the reflected light from the semiconductor device  11  that has passed through the solid immersion lens  60  and the objective lens  21  and is directed to the high-sensitivity camera  3  to the LSM unit  4 . Further, the optical system  20  further includes a microscope  5  for observing the semiconductor device  11 . 
     As described above, the XYZ stage  7  moves the solid immersion lens unit  2 , the high-sensitivity camera  3 , the LSM unit  4 , the optical system  20 , and the like in the X, Y, and Z directions. An operation of the XYZ stage  7  is controlled by the control unit  1   b.    
     The control unit  1   b  includes a camera controller  31 , a laser scan (LSM) controller  32 , and a peripheral controller  33 . The camera controller  31  controls an operation of the high-sensitivity camera  3 . The LSM controller  32  controls an operation of the LSM unit  4 . The peripheral controller  33  controls an operation of the XYZ stage  7 . That is, movement, position alignment, focusing, and the like of the solid immersion lens unit  2 , the high-sensitivity camera  3 , the LSM unit  4 , the optical system  20 , and the like to a position corresponding to an observation position of the semiconductor device  11  are controlled. Further, the peripheral controller  33  drives a correction ring adjusting motor  25  attached to the objective lens  21  to control the correction ring  24 . Observation conditions or the like of the semiconductor device  11  performed by the observation unit  1   a  can be controlled by the control unit  1   b.    
     The analysis unit  1   c  includes an image analysis unit  41  and an instruction unit  42 . The image analysis unit  41  creates an image on the basis of image information (image data) output from the camera controller  31  and the LSM controller  32  and executes necessary analysis processing or the like. The instruction unit  42  refers to an input content from an operator, an analysis content of the image analysis unit  41 , and the like and gives a necessary instruction regarding execution of an inspection of the semiconductor device  11  in the observation unit  1   a  via the control unit  1   b . Images, data, and the like acquired or analyzed by the analysis unit  1   c  can be displayed on a display device  43  connected to the analysis unit  1   c.    
     [Configuration of Solid Immersion Lens] 
     As illustrated in  FIGS. 3, 4 and 5 , the solid immersion lens  60  includes a base part  61  and a meta-lens  62 . The base part  61  has the first surface  61   a  and a second surface  61   b . The first surface  61   a  is a surface to be brought into contact with the semiconductor device  11  (specifically, the back surface  12   b  of the semiconductor substrate  12 ). The second surface  61   b  is a surface opposite to the first surface  61   a . An area of the first surface  61   a  is smaller than an area of the second surface  61   b . The area of the first surface  61   a  may be, for example, 0.001 times or more and 0.5 times or less than the area of the second surface  61   b.    
     The base part  61  includes a first portion  611  having the first surface  61   a  and a second portion  612  having the second surface  61   b . The first portion  611  and the second portion  612  are integrally formed. “Integrally formed” means that they are formed as a single member. An outer edge  612   a  of the second portion  612  is positioned outside an outer edge  611   a  of the first portion  611  when viewed from a direction (Z direction) parallel to the optical axis A of the solid immersion lens  60  (meta-lens  62 ). Further, in the optical apparatus  1 , the optical axis A of the solid immersion lens  60  (meta-lens  62 ) coincides with the optical axis A of the objective lens  21 . 
     Examples of shapes and dimensions of the first portion  611  and the second portion  612  are as follows. The first portion  611  has a rectangular plate shape (for example, a square plate shape) in which a length of one side is several millimeters or more and tens of millimeters or less and a thickness is tens of micrometers or more and hundreds of micrometers or less. The second portion  612  has a rectangular plate shape (for example, a square plate shape) in which a length of one side is tens of micrometers or more and hundreds of micrometers or less and a thickness is several micrometers or more and tens of micrometers or less. When viewed from a direction parallel to the optical axis A, a center of the first portion  611  coincides with a center of the second portion  612 . 
     The base part  61  is formed of a material according to the refractive index of the semiconductor substrate  12  of the semiconductor device  11 . As an example, when the semiconductor substrate  12  is a silicon substrate, the base part  61  is formed of silicon, gallium arsenide, gallium phosphide, or the like, and in this case, the refractive index of the base part  61  is about 3.5. 
     The meta-lens  62  is disposed on the second surface  61   b  of the base part  61 . An example of a shape and dimensions of the meta-lens  62  (an aggregate of a plurality of antennas  70  to be described later) are as follows. The meta-lens  62  has a rectangular plate shape (for example, a square plate shape) in which a length of one side is tens of micrometers or more and hundreds of micrometers or less and a thickness is several micrometers or more and tens of micrometers or less. When viewed from the direction parallel to the optical axis A, a center of the meta-lens  62  coincides with the center of the second portion  612  of the base part  61 . 
     As illustrated in  FIGS. 5 and 6 , the meta-lens  62  includes the plurality of antennas  70 . The “meta-lens” is an optical element that functions as a lens by having a meta-surface structure to be described later. Each of the antennas  70  is a member for adjusting an effective refractive index of the solid immersion lens  60 . As an example, each antenna  70  has a pillar shape (more specifically, a columnar shape) in which an axis of each antenna  70  extends along the optical axis A. Further, a shape of each antenna  70  is not limited to a columnar shape or a pillar shape as long as the effective refractive index of the solid immersion lens  60  can be controlled. 
     Each antenna  70  may be formed integrally with the base part  61 . For example, when the base part  61  is formed of silicon and each antenna  70  is formed integrally with the base part  61 , a refractive index of each antenna  70  is about 3.5. That is, the refractive index of each antenna  70  is approximately the same as the refractive index of the semiconductor substrate  12  of the semiconductor device  11 . 
     The antennas  70  are disposed two-dimensionally when viewed from the direction parallel to the optical axis A. As an example, the antennas  70  may be disposed periodically (more specifically, in a matrix shape) when viewed from the direction parallel to the optical axis A. A period in which the antennas  70  are disposed may be determined as follows. That is, incident light having a predetermined wavelength is made to be incident on the solid immersion lens  60 . Here, infrared laser light output from, for example, the LSM unit  4  is made to be incident on the solid immersion lens  60 . The antennas  70  may be disposed at a predetermined period smaller than a predetermined wavelength of the incident light incident on the solid immersion lens  60  when viewed from the direction parallel to the optical axis A. The “predetermined wavelength” may be, for example, a wavelength of 100 nm or more and 5200 nm or less, or a wavelength of 300 nm or more and 2000 nm or less. The “predetermined period” may be the same period in the entire region in which the plurality of antennas  70  are disposed, may be a different period for each portion of the region in which the plurality of antennas  70  are disposed, or may be a period that gradually changes along the region in which the plurality of antennas  70  are disposed. The “predetermined period” may be, for example, 20% or more and 100% or less of the predetermined wavelength, and specifically may be 100 nm or more and 5200 nm or less. In this case, light can be appropriately refracted by the plurality of antennas  70 . 
     In the solid immersion lens  60 , at least one of sizes, shapes, and dispositions of the plurality of antennas  70  change within the second surface  61   b  when viewed from the direction parallel to the optical axis A. Here, “changing within the second surface  61   b ” means that it may differ depending on a position on the second surface  61   b . Thereby, the meta-lens  62  can adjust the effective refractive index of the solid immersion lens  60 . 
     An intermediate portion  66  is a portion positioned between the plurality of antennas  70 . “Positioned between the plurality of antennas  70 ” means, for example, that it is positioned to fill spaces between the plurality of antennas  70  without a gap. The intermediate portion  66  has a refractive index different from the refractive index of the antenna  70 . A member whose material is different from that of the antenna  70  may be disposed as the intermediate portion  66 , and the intermediate portion  66  may be an air layer. 
     In the solid immersion lens  60 , the meta-lens  62  which is a portion in which the plurality of antennas  70  are disposed forms a so-called meta-surface structure. The “meta-lens  62 ” means a portion of the solid immersion lens  60  formed by the plurality of antennas  70  and the intermediate portion  66 . 
     Here, the solid immersion lens  60  functioning as a lens will be described.  FIG. 7  is a view for explaining that an effective refractive index has a distribution in the solid immersion lens  60 . “Having a distribution” means that the effective refractive index may have a different state or a different value depending on a position. The solid immersion lens  60  has the following effective refractive index n eff  in the meta-lens  62 . That is, when a filling factor a of the antenna  70  in a unit volume of the meta-lens  62 , a refractive index n ms  of the antenna  70 , and a refractive index n b  of the intermediate portion  66  are assumed, the effective refractive index n eff  is expressed by the following expression (1). 
       [Math. 1] 
         n   eff =√{square root over (an ms   2 (1− a ) n   b   2 )}  (1)
 
     As described above, at least one of sizes, shapes, and dispositions of the antennas  70  changes within the second surface  61   b  when viewed from the direction parallel to the optical axis A. For example,  FIG. 7  illustrates a configuration in which sizes of the antennas  70  change within the second surface  61   b . In  FIG. 7 , an upper side of the meta-lens  62  is divided into portions V 1 , V 2 , and V 3  of unit volumes. Then, positions P 1 , P 2 , and P 3  having the same phase in transmitted light that has transmitted to a lower side of the meta-lens  62  when incident light having the same phase is incident on each of the portions V 1 , V 2 , and V 3  from an upper side of the meta-lens  62  are each illustrated in  FIG. 7 . 
     In each of the portions V 1 , V 2 , and V 3 , sizes of the antenna  70  (cross-sectional areas when viewed from the direction parallel to the optical axis A) are different from each other. Here, an antenna  70   a  and an intermediate portion  66   a  are defined in the portion V 1 . In the portion V 2 , an antenna  70   b  and an intermediate portion  66   b  are defined. In the portion V 3 , an antenna  70   c  and an intermediate portion  66   c  are defined. The antenna  70   a , the antenna  70   b , and the antenna  70   c  become larger in that order. That is, in the portion V 1 , the portion V 2 , and the portion V 3 , the filling factor a of the antenna  70  increases in that order. 
     Thereby, the effective refractive index n eff  of each of the portions V 1 , V 2 , and V 3  calculated by the above expression (1) increases in the order of the portion V 1 , the portion V 2 , and the portion V 3 , and the effective refractive index n eff  of the meta-lens  62  has a distribution. The position P 1 , the position P 2 , and the position P 3  having the same phase in transmitted light that has transmitted to the lower side of the meta-lens  62  have distances from the first surface  61   a  that become smaller in that order. As a result of the phase difference occurring in the transmitted light as described above, the incident light is refracted by the meta-lens  62 , and the solid immersion lens  60  functions as a lens by adjusting the effective refractive index n eff  of the meta-lens  62 . For example, when the effective refractive index n eff  of the meta-lens  62  changes in a concentric shape around the optical axis A, the solid immersion lens  60  functions more suitably as a lens. Further, when the plurality of antennas  70  are disposed at a period smaller than a wavelength of the incident light, the incident light behaves as if the meta-lens  62  is a continuous medium having the effective refractive index n eff . 
     The above-described “meta-surface structure” is a structure that functions as an optical element by having a plurality of disposed fine structures (for example, the antennas  70 ). For example, as the meta-surface structure, the following six types of typical methods (hereinafter, referred to as “first method to sixth method”) are exemplified. 
     The first method of the meta-surface structure is a so-called Multi-Resonance method, which is described in detail in “Nanfang Yu et al., “Light Propagation with Phase Discontinuities: Generalized Laws of Reflection and Refraction”, Science, 2011, 334, 333.” The first method has, for example, a plasmonic antenna and includes two types of resonance modes, a symmetric mode and an asymmetric mode, which are characterized by a current flowing through the plasmonic antenna. 
     The second method of the meta-surface structure is a so-called GAP-Plasmon method, which is described in detail in “S. Sun et al., “High-efficiency broadband anomalous reflection by gradient meta-surfaces”, Nano Letters, 2012,12, 6223.” The second method is, for example, a reflection type meta-surface structure having a MIM structure as a basic configuration, and a phase of light is modulated by a gap surface plasmon mode. The “gap surface plasmon mode” is a mode in which strong magnetic resonance occurs in a dielectric depending on induced currents of an upper antenna and a lower antenna facing in opposite directions. According to this, a reflection phase can be efficiently modulated by changing a length of the antenna. 
     The third method of the meta-surface structure is a so-called Pancharatnam-Berry phase (PB phase) method, which is described in detail in “Francesco Monticone et al., “Full Control of Nanoscale Optical Transmission with a Composite Metascreen”, Physical Review Letters, 2013, 110, 203903.” The third method modulates a phase by, for example, modulating angles of antennas having the same shape. 
     The fourth method of the meta-surface structure is a so-called Huygens-meta-surface method, which is described in detail in “tingling Huang et al., “Dispersionless Phase Discontinuities for Controlling Light Propagation”, Nano Letters, 2012, 12, 5750″ and “Manuel Decker et. al., “High-efficiency light-wave control with all-dielectric optical Huygens&#39; meta-surfaces”, Advanced Optical Materials, 2015, 3, 813.” The fourth method reduces a reflectance by adjusting, for example, an electric dipole and a magnetic dipole at the same time at an interface of a medium having independent electromagnetic field characteristics. 
     The fifth method of the meta-surface structure is a so-called High-Contrast method, which is described in detail in “Seyedeh M. Kamali et al., “Decoupling optical function and geometrical form using conformal flexible dielectric meta-surfaces”, Nature Communications, 2016, 7, 11618.” The fifth method realizes a plurality of modes of Fabry-Perot resonance with a low Q value by utilizing, for example, a large difference in refractive index between an antenna and the surrounding medium. An electric dipole and a magnetic dipole are included in the plurality of modes. 
     The sixth method of the meta-surface structure is a so-called Gradient-Index method, which is described in detail in “Philippe Lalanne et al., “Design and fabrication of blazed binary diffractive elements with sampling periods smaller than the structural cutoff”, Journal of the Optical Society of America. A, 1999, 16 (5), 1143.” The sixth method modulates phases (effective refractive indexes) of media having different refractive indexes using a change in filling factor in a unit cell thereof. 
     The solid immersion lens  60  configured as described above focuses the infrared laser light L emitted from the light source  4   a  on a predetermined portion of the semiconductor device  11 . An operation of the solid immersion lens  60  will be described with reference to  FIG. 3 . 
     As illustrated in  FIG. 3 , the infrared laser light L emitted from the light source  4   a  of the LSM unit  4  is refracted by the meta-lens  62  of the solid immersion lens  60 , passes through the second portion  612  of the base part  61  of the solid immersion lens  60 , the first portion  611  of the base part  61  of the solid immersion lens  60 , and the semiconductor substrate  12  of the semiconductor device  11  in that order, and is focused on the integrated circuit  13 . That is, a focusing point C of the infrared laser light L is positioned on the integrated circuit  13 . 
     The focusing point C of the infrared laser light L is made on the semiconductor device  11  side (opposite to the meta-lens  62  with respect to the first portion  611  of the solid immersion lens  60 ). Therefore, when a thickness of the base part  61  of the solid immersion lens  60  is adjusted, a distance between the meta-lens  62  and the focusing point C can be controlled. Since the distance between the meta-lens  62  and the focusing point C can be controlled, a size of the meta-lens  62  effective as a lens is not limited, a degree of freedom in phase design improves, and thus it is effective in aberration correction or the like. 
     Since the infrared laser light L passes through the first portion  611  of the base part  61  of the solid immersion lens  60 , a size of the first portion  611  is a size through which the infrared laser light L can pass. That is, the size of the first portion  611  may be equal to or larger than a size through which the infrared laser light L can pass, and the first portion  611  can be miniaturized according to an optical path of the infrared laser light L. 
     The infrared laser light L focused on the focusing point C is reflected by the integrated circuit  13  of the semiconductor device  11 . The reflected light from the semiconductor device  11  passes through the semiconductor substrate  12  of the semiconductor device  11 , the first portion  611  of the base part  61  of the solid immersion lens  60 , and the second portion  612  of the base part  61  of the solid immersion lens  60  in that order, is detected by the photodetector  4   b , and thereby the semiconductor device  11  can be observed. 
     [Method of Manufacturing Solid Immersion Lens] 
     [Method of Forming Meta-Lens] 
     A method of manufacturing the solid immersion lens  60  will be described. First, a method of forming the meta-lens  62  of the solid immersion lens  60  will be described with reference to  FIGS. 8A to 10B .  FIGS. 8A to 10B  are views for explaining a method of forming the meta-lens  62  of the solid immersion lens  60 . 
     First, as illustrated in  FIGS. 8A and 8B , a mask layer  83  is formed on a substrate  80  serving as the base part  61  of the solid immersion lens  60  (layer forming step). The mask layer  83  is formed by laminating a hard mask  81  and a resist  82 . A shape of the substrate  80  may be a thin film shape or a flat plate shape. 
     As illustrated in  FIG. 8A , the hard mask  81  is formed on an upper surface  80   a  of the substrate  80 . The hard mask  81  can be formed by, for example, resistance heating vapor deposition. As a material of the hard mask  81 , silicon nitride or the like can be exemplified. A thickness of the hard mask  81  can be, for example, about 300 nm. 
     Next, as illustrated in  FIG. 8B , the resist  82  is formed on an upper surface  81   a  of the hard mask  81 . The resist  82  can be formed by, for example, applying an electron beam resist. As a material of the resist  82 , an electron beam resist such as ZEP520A can be exemplified. A thickness of the resist  82  can be, for example, about 300 nm. 
     Next, as illustrated in  FIGS. 9A and 9B , a plurality of openings  84  are formed in the mask layer  83  formed on the substrate  80  (opening step). The openings  84  each include a hard mask opening  84   a  formed in the hard mask  81  and a resist opening  84   b  formed in the resist  82 . The hard mask opening  84   a  is formed via the resist opening  84   b . Therefore, the hard mask opening  84   a  and the resist opening  84   b  are formed at the same position as each other when viewed from the direction perpendicular to the upper surface  80   a  of the substrate  80 . The resist opening  84   b  can be formed by performing electron beam lithography and development on the resist  82 . The hard mask opening  84   a  can be formed by performing induced coupled plasma-reactive ion etching (ICP-RIE) on the hard mask  81 . 
     The mask layer  83  after the opening step may be formed to be periodically disposed when viewed from a direction perpendicular to the upper surface  80   a  of the substrate  80 . More specifically, when incident light having a predetermined wavelength is incident on the solid immersion lens  60 , the mask layer  83  may be formed to be disposed at a period smaller than the predetermined wavelength when viewed from the direction perpendicular to the upper surface  80   a  of the substrate  80 . Here, a size, a shape, and a disposition of the mask layer  83  are the size, the shape, and the disposition of the antenna  70  of the meta-lens  62 . The mask layer  83  may have, for example, a circular shape having a diameter of 50 nm or more and 270 nm or less. Also, the mask layer  83  may be formed to be disposed, for example, in a period of 300 nm. Further, at least one of sizes, shapes, and dispositions of a plurality of mask layers  83  may change within the upper surface  80   a  of the substrate  80  when viewed from the direction perpendicular to the upper surface  80   a  of the substrate  80 . Here, “changing within the upper surface  82   a  of the substrate  80 ” means that it may differ depending on a position on the upper surface  82   a  of the substrate  80 . 
     Next, as illustrated in  FIG. 10A , etching is performed through the plurality of openings  84  to form a plurality of recessed parts  80   c  in the substrate  80  (etching step). As the etching, for example, dry etching may be performed, and particularly, reactive ion etching (RIE) may be performed. The etching is performed from the upper surface  80   a  of the substrate  80  to an upper surface  80   b  inside the substrate  80 . Thereby, the recessed part  80   c  having a predetermined depth (etching depth) can be formed on the upper surface  80   a  of the substrate  80 . The etching depth can be, for example, about 800 nm. 
     Next, as illustrated in  FIG. 10B , the mask layer  83  is removed (removal step). That is, the hard mask  81  is lifted off. Thereby, the resist  82  formed on the hard mask  81  can be removed together with the hard mask  81 . As a result, the upper surface  80   a  and the upper surface  80   b  can be formed on the substrate  80 . Then, a protruding part  80   d  having the upper surface  80   a  serves as the antenna  70  of the meta-lens  62  of the solid immersion lens  60 , and the upper surface  80   b  serves as the second surface  61   b  of the solid immersion lens  60 . Thereby, the meta-lens  62  of the solid immersion lens  60  can be formed. 
     [Method of Forming First Portion] 
     Next, a method of forming the first portion  611  of the solid immersion lens  60  will be described with reference to  FIGS. 11A to 13B .  FIGS. 11A to 13B  are views for explaining a method of forming the first portion  611  of the solid immersion lens  60 . 
     First, as illustrated in  FIGS. 11A and 11B , a mask layer  93  is formed on a substrate  90  which will become the base part  61  of the solid immersion lens  60  (layer forming step). The mask layer  93  is formed by laminating a hard mask  91  and a resist  92 . A shape of the substrate  90  may be a thin film shape or a flat plate shape. 
     As illustrated in  FIG. 11A , the hard mask  91  is formed on an upper surface  90   a  of the substrate  90 . The hard mask  91  can be formed by, for example, resistance heating vapor deposition. As a material of the hard mask  91 , silicon nitride or the like can be exemplified. A thickness of the hard mask  91  can be, for example, about 300 nm. 
     Next, as illustrated in  FIG. 11B , the resist  92  is formed on an upper surface  91   a  of the hard mask  91 . The resist  92  can be formed by, for example, applying an electron beam resist. As a material of the resist  92 , an electron beam resist such as ZEP520A can be exemplified. A thickness of the resist  92  can be, for example, about 300 nm. 
     Next, as illustrated in  FIGS. 12A and 12B , the mask layer  93  formed on the substrate  90  is removed (removal step). The portion (removed part  94 ) removed from the mask layer  93  formed on the substrate  90  includes a hard mask removed part  94   a  removed from the hard mask  91  and a resist removed part  94   b  removed from the resist  92 . The hard mask removed part  94   a  is removed via the resist removed part  94   b . Therefore, the hard mask removed part  94   a  and the resist removed part  94   b  are at the same position as each other when viewed from a direction perpendicular to the upper surface  90   a  of the substrate  90 . The resist removed part  94   b  can be removed by performing electron beam lithography and development on the resist  92 . The hard mask removed part  94   a  can be removed by performing induced coupled plasma-reactive ion etching (ICP-RIE) on the hard mask  91 . 
     Next, as illustrated in  FIG. 13A , etching is performed through the removed part  94  to remove the substrate  90  to a predetermined depth (etching depth) (etching step). As the etching, for example, dry etching may be performed, and particularly, reactive ion etching (RIE) may be performed. The etching is performed from the upper surface  90   a  of the substrate  90  to the upper surface  90   b  inside the substrate  90 . The etching depth can be, for example, about 5 μm. 
     Next, as illustrated in  FIG. 13B , the mask layer  93  is removed (mask layer removing step). That is, the hard mask  91  is lifted off. Thereby, the resist  92  formed on the hard mask  91  can be removed together with the hard mask  91 . As a result, the upper surface  90   a  and the upper surface  90   b  can be formed on the substrate  90 . Then, a protruding part  90   d  having the upper surface  90   a  serves as the first portion  611  of the base part  61  of the solid immersion lens  60 . As described above, the first portion  611  of the solid immersion lens  60  can be formed. 
     [Operation and Effects] 
     As described above, in the optical apparatus  1 , the solid immersion lens  60  includes the meta-lens  62  disposed on the second surface  61   b  of the base part  61 . Thereby, the effective refractive index of the meta-lens  62  can be controlled by controlling at least one of sizes, shapes, and dispositions of the plurality of antennas  70  included in the meta-lens  62  in a direction along the second surface  61   b  of the base part  61 . Therefore, the solid immersion lens  60  can be made thinner. Also, when the solid immersion lens  60  is brought into contact with the semiconductor device  11 , the first surface  61   a  of the base part  61  is brought into contact with the semiconductor device  11 . Thereby, the solid immersion lens  60  can be easily handled as compared with, for example, a case in which the meta-lens  62  is brought into contact with the semiconductor device  11 . Therefore, according to the optical apparatus  1 , thinning of the solid immersion lens  60  and easy handling of the solid immersion lens  60  can be realized. 
     Also, according to the optical apparatus  1 , since the optical device serves as the photodetector  4   b , light emitted from the semiconductor device  11  or light reflected by the semiconductor device  11  can be detected with high accuracy. 
     Also, according to the optical apparatus  1 , since the optical device serves as the light source  4   a , the semiconductor device  11  can be irradiated with light with high accuracy. 
     Also, according to the optical apparatus  1 , since the area of the first surface  61   a  of the solid immersion lens  60  is smaller than the area of the second surface  61   b , the first surface  61   a  of the base part  61  can be reliably brought into contact with the semiconductor device  11 , for example, to prevent intervention of an air layer while a sufficient size for holding the solid immersion lens  60  is secured on the base part  61 . 
     Also, according to the optical apparatus  1 , since the objective lens  21  is provided at a position between the solid immersion lens  60  and the optical device (the light source  4   a , the photodetector  4   b ) on the optical path, a focus of the objective lens  21  can be accurately aligned with a desired position of the semiconductor device  11 . 
     Also, according to the solid immersion lens  60 , as described above, thinning of the solid immersion lens  60  and easy handling of the solid immersion lens  60  can be realized. Further, the first surface  61   a  of the base part  61  can be reliably brought into contact with the semiconductor device  11 , for example, to prevent intervention of an air layer while a sufficient size for holding the solid immersion lens  60  is secured on the base part  61 . 
     Also, according to the solid immersion lens  60 , the base part  61  may include the first portion  611  having the first surface  61   a  and the second portion  612  having the second surface  61   b , the outer edge  612   a  of the second portion  612  may be positioned outside the outer edge  611   a  of the first portion  611  when viewed from a direction parallel to the optical axis A of the meta-lens  62 , and the first portion  611  and the second portion  612  may be integrally formed. According to this, the solid immersion lens  60  can be stably held on the second portion  612 . Also, an interface causing refraction and reflection of light can be prevented from being formed between the first portion  611  and the second portion  612 . 
     Modified Example 
     The embodiment described above can be implemented in various forms in which various changes and improvements are made on the basis of knowledge of those skilled in the art. 
     Also, in the embodiment described above, the light source of the optical apparatus  1  is not limited to the light source  4   a  configured to irradiate the infrared laser light L. The light source of the optical apparatus  1  may be a light source configured to irradiate ultraviolet light or a light source configured to irradiate visible light. 
     Also, in the embodiment described above, the optical apparatus  1  includes the light source  4   a  and the photodetector  4   b , but the optical apparatus  1  may be configured as an illuminating device having a light source and not having a photodetector or may be configured as an observation device not having a light source and having a photodetector. 
     Also, in the embodiment described above, the optical apparatus  1  may not include the objective lens  21 . When the optical apparatus  1  does not include the objective lens  21 , the apparatus can be miniaturized. 
     Also, in the embodiment described above, the solid immersion lens holder  8  is not limited to the configuration of the above-described embodiment as long as it can hold the solid immersion lens  60 . For example, the lens holding part  8   b  of the solid immersion lens holder  8  may not have a gap with respect to the solid immersion lens  60 . 
     Also, in the embodiment described above, the semiconductor device  11  may not be molded with the resin  14  as the mold-type semiconductor device  10 . 
     For example, in the embodiment described above, the solid immersion lens  60  is not particularly limited in shape when viewed from the direction parallel to the optical axis A and may have, for example, a circular shape when viewed from the direction parallel to the optical axis A. 
     Also, in the embodiment described above, the first portion  611  of the base part  61  of the solid immersion lens  60  is not particularly limited in shape when viewed from the direction parallel to the optical axis A and may have, for example, a circular shape when viewed from the direction parallel to the optical axis A. 
     Also, in the embodiment described above, the first portion  611  and the second portion  612  of the base part  61  of the solid immersion lens  60  may not be integrally formed. The first portion  611  and the second portion  612  of the base part  61  of the solid immersion lens  60  may be formed of different materials. 
     Also, in the embodiment described above, the antenna  70  is not particularly limited in shape. For example, the antenna  70  may have a shape corresponding to a method of a meta-surface structure of the meta-lens  62 . 
     Also, in the embodiment described above, the antenna  70  may not be formed of silicon. For example, the antenna  70  may be formed of germanium, gold, silver, chromium, or the like. Even in these cases, the effective refractive index of the meta-lens  62  can be set to a suitable value. 
     Also, in the embodiment described above, the antenna  70  is not limited to the disposition in the embodiment described above as long as the infrared laser light L emitted from the light source  4   a  of the LSM unit  4  can be focused on a predetermined portion of the semiconductor device  11 . For example, the antennas  70  may be periodically disposed to be a honeycomb shape, a radial shape, or the like when viewed from the direction parallel to the optical axis A, or may be disposed aperiodically when viewed from the direction parallel to the optical axis A. 
     An optical apparatus of one aspect of the present disclosure includes a support part configured to support an object, a solid immersion lens configured to be brought into contact with the object supported by the support part, and an optical device disposed at a position opposite to the support part with respect to the solid immersion lens on an optical path passing through the solid immersion lens, in which the solid immersion lens includes a base part having a first surface to be brought into contact with the object and a second surface opposite to the first surface, and a meta-lens disposed on the second surface. 
     In the optical apparatus, the solid immersion lens includes the meta-lens disposed on the second surface of the base part. Thereby, an effective refractive index of the meta-lens can be controlled by controlling at least one of sizes, shapes, and dispositions of the plurality of antennas included in the meta-lens in a direction along the second surface of the base part. Therefore, the solid immersion lens can be made thinner. Also, when the solid immersion lens is brought into contact with the object, the first surface of the base part is brought into contact with the object. Thereby, the solid immersion lens can be easily handled as compared with, for example, a case in which the meta-lens is brought into contact with the object. Therefore, according to the optical apparatus, thinning of the solid immersion lens and easy handling of the solid immersion lens can be realized. 
     In the optical apparatus of one aspect of the present disclosure, the optical device may be a photodetector. According to this, light emitted from the object or light reflected by the object can be detected with high accuracy. 
     In the optical apparatus of one aspect of the present disclosure, the optical device may be a light source. According to this, the object can be irradiated with light with high accuracy. 
     In the optical apparatus of one aspect of the present disclosure, an area of the first surface may be smaller than an area of the second surface. According to this, the first surface of the base part can be reliably brought into contact with the object, for example, to prevent intervention of an air layer while a sufficient size for holding the solid immersion lens is secured on the base part. 
     In the optical apparatus of one aspect of the present disclosure, the base part includes a first portion having the first surface and a second portion having the second surface, an outer edge of the second portion is positioned outside an outer edge of the first portion when viewed from a direction parallel to an optical axis of the meta-lens, and the first portion and the second portion are integrally formed. According to this, the solid immersion lens can be stably held on the second portion. Also, an interface causing refraction and reflection of light can be prevented from being formed between the first portion and the second portion. 
     The optical apparatus of one aspect of the present disclosure may further include an objective lens disposed at a position between the solid immersion lens and the optical device on the optical path. According to this, a focus of the objective lens can be accurately aligned with a desired position of the object. 
     In the optical apparatus of one aspect of the present disclosure, the object may be a semiconductor device. According to this, for example, a failure analysis of a semiconductor device can be performed with high accuracy. 
     A solid immersion lens of one aspect of the present disclosure includes a base part having a first surface to be brought into contact with an object and a second surface opposite to the first surface, and a meta-lens disposed on the second surface, in which an area of the first surface is smaller than an area of the second surface. 
     According to the solid immersion lens, as described above, thinning of the solid immersion lens and easy handling of the solid immersion lens can be realized. Also, the first surface of the base part can be reliably brought into contact with the object, for example, to prevent intervention of an air layer while a sufficient size for holding the solid immersion lens is secured on the base part. 
     In the solid immersion lens of one aspect of the present disclosure, the base part includes a first portion having the first surface and a second portion having the second surface, an outer edge of the second portion is positioned outside an outer edge of the first portion when viewed from a direction parallel to an optical axis of the meta-lens, and the first portion and the second portion are integrally formed. According to this, the solid immersion lens can be stably held on the second portion. Also, an interface causing refraction and reflection of light can be prevented from being formed between the first portion and the second portion. 
     According to the present disclosure, it is possible to provide an optical apparatus including a solid immersion lens in which thinning and easy handling are realized, and such a solid immersion lens.