Optical device and solid immersion lens

Abstract

To provide an optical device that includes a solid immersion lens having thinning and easy-to-use achieved, and to provide such a solid immersion lens.SOLUTION: An optical device comprises: a stage that supports a semiconductor device 11; a solid immersion lens 60 that is caused to abut with the semiconductor device 11 supported by the stage; and an optical detector that is arranged in a position on a side opposite the stage relative to the solid immersion lens 60 out of positions on an optical path passing through the solid immersion lens 60. The solid immersion lens 60 includes: a base part 61 that has a first surface 61a to be caused to abut with the semiconductor device 11, and a second surface 61b on a side opposite the first surface 61a; and a meta lens 62 that is arranged in the second surface 61b.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to an optical device and a solid immersion lens. [Background technology]

[0002] As a method for observing an object, a method is known in which a solid immersion lens is brought into contact with the object, an enlarged image of the object is obtained, and the object is observed. For example, Patent Document 1 describes a method in which a meta solid immersion lens having a plurality of antenna parts arranged at a period shorter than the wavelength of incident light is prepared, and the plurality of antenna parts are brought into contact with the object to obtain an enlarged image of the object with high spatial resolution. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-197097 A Summary of the Invention [Problem to be solved by the invention]

[0004] The meta solid immersion lens described in Patent Document 1 above is effective in that it allows the solid immersion lens to be made thinner, but great care must be taken when bringing the multiple antenna units into contact with the target object so as not to damage the multiple antenna units.

[0005] Therefore, an object of the present invention is to provide an optical device equipped with a solid immersion lens that has been made thin and easy to handle, and to provide such a solid immersion lens. [Means for solving the problem]

[0006] The optical device of the present invention comprises a support for supporting an object, a solid immersion lens that is brought into contact with the object supported by the support, and an optical device arranged at a position on the optical path passing through the solid immersion lens on the opposite side of the support with respect to the solid immersion lens, wherein the solid immersion lens includes a base having a first surface that is brought into contact with the object and a second surface opposite the first surface, and a metalens arranged on the second surface.

[0007] In this optical device, the solid immersion lens includes a metalens disposed on the second surface of the base. This allows the effective refractive index of the metalens to be controlled by controlling at least one of the size, shape, and arrangement of the multiple antennas included in the metalens in a direction along the second surface of the base. This allows the solid immersion lens to be thinned. Furthermore, when the solid immersion lens is brought into contact with the object, the first surface of the base is brought into contact with the object. This allows the solid immersion lens to be handled more easily than when, for example, the metalens is brought into contact with the object. Therefore, this optical device allows the solid immersion lens to be thinned and easily handled.

[0008] In the optical apparatus of the present invention, the optical device may be a photodetector, which makes it possible to accurately detect light emitted from an object or light reflected by the object.

[0009] In the optical apparatus of the present invention, the optical device may be a light source, which makes it possible to precisely irradiate the object with light.

[0010] In the optical device of the present invention, the area of ​​the first surface may be smaller than the area of ​​the second surface, which allows the first surface of the base to be reliably abutted against the object while ensuring a size in the base sufficient for holding the solid immersion lens, for example, to prevent the inclusion of an air layer.

[0011] In the optical device of the present invention, the base includes a first portion having a first surface and a second portion having a second surface, and when viewed from a direction parallel to the optical axis of the metalens, the outer edge of the second portion is located outside the outer edge of the first portion, and the first and second portions may be formed integrally. This allows the solid immersion lens to be stably held in the second portion. In addition, it is possible to prevent an interface that causes refraction and reflection of light from being formed between the first and second portions.

[0012] The optical device of the present invention may further include an objective lens disposed at a position on the optical path between the solid immersion lens and the optical device, whereby the focus of the objective lens can be adjusted to a desired position on the object with high precision.

[0013] In the optical apparatus of the present invention, the object may be a semiconductor device, and thus, for example, failure analysis of the semiconductor device can be performed with high accuracy.

[0014] The solid immersion lens of the present invention comprises a base having a first surface that is brought into contact with an object and a second surface opposite the first surface, and a metalens disposed on the second surface, wherein the area of ​​the first surface is smaller than the area of ​​the second surface.

[0015] As described above, this solid immersion lens can be made thinner and easier to handle. In addition, while ensuring a sufficient size for holding the solid immersion lens in the base, the first surface of the base can be reliably abutted against the object so as to prevent, for example, the presence of an air layer.

[0016] In the solid immersion lens of the present invention, the base includes a first portion having a first surface and a second portion having a second surface, and when viewed from a direction parallel to the optical axis of the metalens, the outer edge of the second portion is located outside the outer edge of the first portion, and the first and second portions may be formed integrally. This allows the solid immersion lens to be stably held in the second portion. In addition, it is possible to prevent an interface that causes refraction and reflection of light from being formed between the first and second portions. Effect of the Invention

[0017] According to the present invention, it is possible to provide an optical device equipped with a solid immersion lens that has been made thin and easy to handle, and such a solid immersion lens. [Brief description of the drawings]

[0018] [Figure 1] FIG. 1 is a block diagram of an optical device according to an embodiment. [Diagram 2] 2 is a cross-sectional view of the solid immersion lens unit shown in FIG. 1. [Diagram 3] FIG. 3 is a front view of the solid immersion lens shown in FIG. 2. [Figure 4] FIG. 3 is a bottom view of the solid immersion lens shown in FIG. [Diagram 5] FIG. 3 is a plan view of the solid immersion lens shown in FIG. 2. [Figure 6] FIG. 4 is a schematic diagram of the metalens shown in FIG. [Figure 7] FIG. 4 is a diagram for explaining that the metalens shown in FIG. 3 has an effective refractive index distribution. [Figure 8] FIG. 3 is a diagram for explaining a method of forming the metalens of the solid immersion lens shown in FIG. 2. [Figure 9] FIG. 3 is a diagram for explaining a method of forming the metalens of the solid immersion lens shown in FIG. 2. [Figure 10] FIG. 3 is a diagram for explaining a method of forming the metalens of the solid immersion lens shown in FIG. 2. [Figure 11]3 is a diagram for explaining a method of forming a first portion of the solid immersion lens shown in FIG. 2. [Figure 12] 3 is a diagram for explaining a method of forming a first portion of the solid immersion lens shown in FIG. 2. [Figure 13] 3 is a diagram for explaining a method of forming a first portion of the solid immersion lens shown in FIG. 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In each drawing, the same or corresponding parts are denoted by the same reference numerals, and duplicated explanations will be omitted.

[0020] [Optical device configuration] 1 and 2, the optical device 1 is, for example, a device for observing a semiconductor device (object) 11 included in a molded semiconductor device 10. Specifically, the optical device 1 is, for example, a semiconductor failure analysis device that acquires an enlarged image of the semiconductor device 11 and analyzes failures in the semiconductor device 11 by inspecting internal information of the semiconductor device 11 based on the enlarged image.

[0021] The molded semiconductor device 10 is a semiconductor device 11 molded with a resin 14. The internal information of the semiconductor device 11 includes, for example, the circuit pattern of the semiconductor device 11, light emitted from the semiconductor device 11, and information regarding heat generation in the semiconductor device 11. Examples of the light emission include light emission due to defects in the semiconductor device 11 and transient light emission associated with the switching operation of a transistor in the semiconductor device 11. Examples of the heat generation include heat generation due to defects in the semiconductor device 11.

[0022] The semiconductor device 11 has a semiconductor substrate 12 and an integrated circuit 13. The integrated circuit 13 is formed on a front surface 12a of the semiconductor substrate 12. The semiconductor device 11 is embedded in a resin 14 so that a back surface 12b of the semiconductor substrate 12 is exposed. The molded semiconductor device 10 is placed on a stage (support) 6 so that the back surface 12b of the semiconductor device 11 faces upward. In other words, the stage 6 supports the semiconductor device 11. As an example, the semiconductor substrate 12 is a silicon substrate, and in this case, the refractive index of the semiconductor substrate 12 is about 3.5.

[0023] The optical device 1 includes an observation unit 1a, a control unit 1b, and an analysis unit 1c. The observation unit 1a observes a semiconductor device 11. The control unit 1b controls the operation of each unit of the observation unit 1a. The analysis unit 1c performs processing and issues instructions necessary for analyzing the semiconductor device 11.

[0024] The observation section 1a has a solid immersion lens unit 2, a high-sensitivity camera (optical device, photodetector) 3, a laser scanning optical system (LSM: Laser Scanning Microscope) unit 4, an optical system 20, and an XYZ stage 7. The solid immersion lens unit 2 is a lens unit for observing a 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 the X, Y, and Z directions. The X and Y directions are horizontal directions that are perpendicular to each other, and the Z direction is a vertical direction with respect to the XY plane.

[0025] The solid immersion lens unit 2 has a solid immersion lens 60 and a solid immersion lens holder (holding portion) 8. The solid immersion lens 60 is abutted against a semiconductor device 11 supported by a stage 6. The solid immersion lens 60 has a first surface 61a that is abutted against the semiconductor device 11 (specifically, the back surface 12b of the semiconductor substrate 12). The first surface 61a is the surface of the outer surface of the solid immersion lens 60 that faces the semiconductor device 11 (here, the lower surface).

[0026] The solid immersion lens holder 8 holds the solid immersion lens 60 so that the solid immersion lens 60 is located below the objective lens 21 of the optical system 20. The solid immersion lens holder 8 is formed of a metal such as aluminum. The solid immersion lens holder 8 has a cylindrical main body portion 8a and a lens holding portion 8b. The main body portion 8a is attached to the lower end portion of the objective lens 21. The lens holding portion 8b is provided at the end portion of the main body portion 8a on the semiconductor device 11 side (the side opposite to the objective lens 21), and holds the solid immersion lens 60.

[0027] The main body 8a passes the infrared laser light L output from the light source 4a of the LSM unit 4 to the solid immersion lens 60 side, and passes the light reflected by the semiconductor device 11 and emitted from the solid immersion lens 60 to the objective lens 21 side. The main body 8a includes a peripheral wall 8c and an extending wall 8d. The peripheral wall 8c is a cylindrical portion that can be extrapolated to the lower end of the objective lens 21 and screwed to the lower end of the objective lens 21. The extending wall 8d is a portion that extends between the peripheral wall 8c and the lens holding portion 8b. By screwing the peripheral wall 8c to the lower end of the objective lens 21, the center of the solid immersion lens holder 8 can be positioned on the optical axis A of the objective lens 21. This allows the position of the solid immersion lens 60 held by the solid immersion lens holder 8 to be adjusted by driving the XYZ stage 7.

[0028] The lens holding portion 8b has a clearance (gap) with respect to the solid immersion lens 60. As a result, the lens holding portion 8b holds the solid immersion lens 60 in a state in which it can oscillate before the solid immersion lens 60 comes into contact with the semiconductor device 11. When the first surface 61a of the solid immersion lens 60 is brought into contact with the back surface 12b of the semiconductor substrate 12 from this state, the solid immersion lens 60 oscillates with respect to the lens holding portion 8b, so that the first surface 61a comes into close contact with the back surface 12b of the semiconductor substrate 12. Therefore, for example, even if the back surface 12b of the semiconductor substrate 12 is inclined with respect to the optical axis A, the first surface 61a can be satisfactorily brought into close contact with the back surface 12b of the semiconductor substrate 12.

[0029] The high-sensitivity camera 3 is disposed at a position on the optical path passing through the solid immersion lens 60, on the opposite side of the stage 6 with respect to the solid immersion lens 60. The high-sensitivity camera 3 outputs image data for creating an image of the circuit pattern, etc. of the semiconductor device 11. The high-sensitivity camera 3 has a CCD area image sensor, a CMOS area image sensor, an InGaAs area image sensor, etc.

[0030] The LSM unit 4 has a light source (optical device) 4a and a photodetector (optical device) 4b. The light source 4a and the photodetector 4b are disposed at positions on the optical path passing through the solid immersion lens 60, on the opposite side of the stage 6 with respect to the solid immersion lens 60. The light source 4a emits infrared laser light. The light source 4a is, for example, a semiconductor laser. The photodetector 4b detects reflected light from the semiconductor device 11. The photodetector 4b is, for example, an avalanche photodiode, a photodiode, or a photomultiplier tube. The LSM unit 4 scans the semiconductor device 11 with infrared laser light in the X direction and the Y direction, thereby generating image data for creating an image of the circuit pattern of the semiconductor device 11, etc.

[0031] The optical system 20 has an objective lens 21, an optical system for camera 22, and an optical system for LSM unit 23. The objective lens 21 is disposed at a position between the solid immersion lens 60 and the LSM unit 4 among positions 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 among positions on the optical path passing through the solid immersion lens 60. A plurality of objective lenses 21 with different magnifications are provided and can be switched. The objective lens 21 has a correction collar 24. By adjusting the correction collar 24, the focus of the objective lens 21 can be accurately adjusted to a predetermined portion of the semiconductor device 11.

[0032] The camera optical system 22 guides the 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 the infrared laser light from the LSM unit 4 toward the objective lens 21 using a beam splitter (not shown) and guides it to the semiconductor device 11. The LSM unit optical system 23 guides the reflected light from the semiconductor device 11 that passes through the solid immersion lens 60 and the objective lens 21 and heads toward the high-sensitivity camera 3 to the LSM unit 4. The optical system 20 further includes a microscope 5 for observing the semiconductor device 11.

[0033] 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, etc. in the X, Y, and Z directions. The operation of the XYZ stage 7 is controlled by the control unit 1b.

[0034] The control unit 1b has a camera controller 31, a laser scan (LSM) controller 32, and a peripheral controller 33. The camera controller 31 controls the operation of the high-sensitivity camera 3. The LSM controller 32 controls the operation of the LSM unit 4. The peripheral controller 33 controls the operation of the XYZ stage 7. That is, it controls the movement, alignment, focusing, etc. of the solid immersion lens unit 2, the high-sensitivity camera 3, the LSM unit 4, and the optical system 20 to positions corresponding to the observation position of the semiconductor device 11. The peripheral controller 33 also drives the correction collar adjustment motor 25 attached to the objective lens 21 to control the correction collar 24. The control unit 1b can control the observation conditions, etc. of the semiconductor device 11 performed in the observation unit 1a.

[0035] The analysis unit 1c has an image analysis unit 41 and an instruction unit 42. The image analysis unit 41 creates an image based on image information (image data) output from the camera controller 31 and the LSM controller 32, and executes necessary analysis processing, etc. The instruction unit 42 refers to the input contents from the operator and the analysis contents by the image analysis unit 41, etc., and issues necessary instructions regarding the execution of the inspection of the semiconductor device 11 in the observation unit 1a via the control unit 1b. Images, data, etc. acquired or analyzed by the analysis unit 1c can be displayed on a display device 43 connected to the analysis unit 1c.

[0036] [Solid immersion lens configuration] As shown in Figures 3, 4 and 5, the solid immersion lens 60 includes a base 61 and a metalens 62. The base 61 has a first surface 61a and a second surface 61b. The first surface 61a is a surface that is brought into contact with the semiconductor device 11 (specifically, the back surface 12b of the semiconductor substrate 12). The second surface 61b is a surface opposite to the first surface 61a. The area of ​​the first surface 61a is smaller than the area of ​​the second surface 61b. The area of ​​the first surface 61a is, for example, 0.001 to 0.5 times the area of ​​the second surface 61b.

[0037] The base 61 includes a first portion 611 having a first surface 61a, and a second portion 612 having a second surface 61b. The first portion 611 and the second portion 612 are integrally formed. "Integral formed" means formed as a single member. When viewed from a direction parallel to the optical axis A of the solid immersion lens 60 (metalens 62) (Z direction), the outer edge 612a of the second portion 612 is located outside the outer edge 611a of the first portion 611. Note that in the optical device 1, the optical axis A of the solid immersion lens 60 (metalens 62) coincides with the optical axis A of the objective lens 21.

[0038] An example of the shapes and dimensions of the first portion 611 and the second portion 612 is as follows. The first portion 611 has a rectangular plate shape (e.g., a square plate shape) with a side length of several mm to several tens of mm and a thickness of several tens of μm to several hundreds of μm. The second portion 612 has a rectangular plate shape (e.g., a square plate shape) with a side length of several tens of mm to several hundreds of mm and a thickness of several μm to several tens of μm. When viewed from a direction parallel to the optical axis A, the center of the first portion 611 coincides with the center of the second portion 612.

[0039] The base 61 is formed of a material corresponding 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 61 is formed of silicon, gallium arsenide, gallium phosphide, or the like, and in this case, the refractive index of the base 61 is about 3.5.

[0040] The metalens 62 is disposed on the second surface 61b of the base 61. An example of the shape and dimensions of the metalens 62 (an assembly of a plurality of antennas 70, described below) is as follows. The metalens 62 has a rectangular plate shape (for example, a square plate shape) with a side length of at least several tens of μm and at most several hundreds of μm and a thickness of at least several μm and at most several tens of μm. When viewed from a direction parallel to the optical axis A, the center of the metalens 62 coincides with the center of the second portion 612 of the base 61. As shown in Figs. 5 and 6, the metalens 62 has a plurality of antennas 70. A "metalens" is an optical element that functions as a lens by having a metasurface structure described later. Each antenna 70 is a member for adjusting the effective refractive index of the solid immersion lens 60. As an example, each antenna 70 has a columnar shape (more specifically, a cylindrical shape) in which the axis of each antenna 70 extends along the optical axis A. Note that the shape of each antenna 70 is not limited to being cylindrical or columnar, as long as the effective refractive index of the solid immersion lens 60 can be controlled.

[0041] Each antenna 70 may be formed integrally with the base 61. For example, when the base 61 is made of silicon and each antenna 70 is formed integrally with the base 61, the refractive index of each antenna 70 is about 3.5. In other words, 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.

[0042] The antennas 70 are arranged two-dimensionally when viewed from a direction parallel to the optical axis A. As an example, the antennas 70 are arranged periodically (more specifically, in a matrix) when viewed from a direction parallel to the optical axis A. The period at which the antennas 70 are arranged may be determined as follows. That is, incident light of a predetermined wavelength is incident on the solid immersion lens 60. Here, for example, infrared laser light output from the LSM unit 4 is incident on the solid immersion lens 60. The antennas 70 may be arranged at a predetermined period shorter than the predetermined wavelength of the incident light incident on the solid immersion lens 60 when viewed from a 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 may be a wavelength of 300 nm or more and 2000 nm or less. The "predetermined period" may be the same period in the entire area where the multiple antennas 70 are arranged, may be a period that differs for each part of the area where the multiple antennas 70 are arranged, or may be a period that gradually changes along the area where the multiple antennas 70 are arranged. The "predetermined period" may be, for example, 20% or more and 100% or less of the predetermined wavelength, specifically, 100 nm or more and 5200 nm or less. In this case, the light can be refracted appropriately by the multiple antennas 70.

[0043] In the solid immersion lens 60, at least one of the size, shape, and arrangement of the multiple antennas 70 varies within the second surface 61b when viewed from a direction parallel to the optical axis A. Here, "varying within the second surface 61b" means that it can vary depending on the position on the second surface 61b. This enables the metalens 62 to adjust the effective refractive index of the solid immersion lens 60.

[0044] The intermediate portion 66 is a portion located between the multiple antennas 70. "Located between the multiple antennas 70" means, for example, that the intermediate portion 66 is located so as to fill the gaps between the multiple antennas 70 without any gaps. The intermediate portion 66 has a refractive index different from that of the antennas 70. The intermediate portion 66 may be a member made of a different material from that of the antennas 70, or may be an air layer.

[0045] In the solid immersion lens 60, the metalens 62, which is the portion in which the multiple antennas 70 are arranged, forms a so-called metasurface structure. "Metalens 62" means the portion of the solid immersion lens 60 that is composed of the multiple antennas 70 and the intermediate portion 66.

[0046] Here, the function of the solid immersion lens 60 as a lens will be described. FIG. 7 is a diagram for explaining that the effective refractive index in the solid immersion lens 60 has a distribution. "Having a distribution" means that it can have a different state or value depending on the position. The solid immersion lens 60 has an effective refractive index n eff That is, the filling factor a of the antenna 70 in a unit volume of the metalens 62, the refractive index n ms , the refractive index n of the intermediate portion 66 b In this case, the effective refractive index n eff is expressed by the following equation (1).

number

[0047] As described above, when viewed from a direction parallel to the optical axis A, at least one of the size, shape, and arrangement of the antenna 70 varies within the second surface 61b. For example, FIG. 7 shows a configuration in which the size of the antenna 70 varies within the second surface 61b. In FIG. 7, the upper side of the metalens 62 is divided into portions V1, V2, and V3 of a unit volume. FIG. 7 also shows positions P1, P2, and P3 where the transmitted light that has passed through the lower side of the metalens 62 has the same phase when incident light of the same phase is incident on each of the portions V1, V2, and V3 from the upper side of the metalens 62.

[0048] The size of the antenna 70 (cross-sectional area when viewed from a direction parallel to the optical axis A) differs from one another in each of the portions V1, V2, and V3. Here, in portion V1, it is an antenna 70a and an intermediate portion 66a. In portion V2, it is an antenna 70b and an intermediate portion 66b. In portion V3, it is an antenna 70c and an intermediate portion 66c. The antennas 70a, 70b, and 70c are larger in this order. In other words, the filling rate a of the antenna 70 increases in the order of portion V1, portion V2, and portion V3.

[0049] As a result, the effective refractive index n of each of the portions V1, V2, and V3 calculated by the above formula (1) is eff is larger in the order of portion V1, portion V2, and portion V3, and the effective refractive index n eff has a distribution. Positions P1, P2, and P3, which are in phase in the transmitted light that has been transmitted to the lower side of the metalens 62, are located at shorter distances from the first surface 61a in this order. As a result of this phase difference occurring in the transmitted light, the incident light is refracted by the metalens 62, and the effective refractive index n eff By adjusting the effective refractive index n eff The solid immersion lens 60 functions more suitably as a lens when the antennas 70 change concentrically around the optical axis A. When the multiple antennas 70 are arranged at a period shorter than the wavelength of the incident light, the incident light is reflected by the metalens 62 at an effective refractive index n effIt behaves as if it were a continuous medium having

[0050] The above-mentioned "metasurface structure" is a structure that functions as an optical element by having a plurality of arranged microstructures (e.g., antenna 70). For example, the metasurface structure may be exemplified by the following six representative types (hereinafter referred to as "Type 1 to Type 6").

[0051] The first type of metasurface structure is a so-called Multi-Resonance type, 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 type, for example, has a plasmonic antenna and includes two types of resonant modes, a symmetric mode and an asymmetric mode, characterized by the current flowing through the plasmonic antenna.

[0052] The second type of metasurface structure is the so-called GAP-Plasmon type, 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 type is, for example, a reflective metasurface structure based on an MIM structure, which modulates the phase of light by the gap surface plasmon mode. The gap surface plasmon mode is a mode in which strong magnetic resonance occurs in the dielectric material depending on the induced currents in the upper and lower antennas being oriented in opposite directions. This allows the reflection phase to be efficiently modulated by changing the length of the antenna.

[0053] The third method of metasurface structure is the 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 the phase by, for example, modulating the angle of an antenna of the same shape.

[0054] The fourth method of metasurface structure is the so-called Huygens-metasurface method, which is described in detail in "Lingling 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' metasurfaces", Advanced Optical Materials, 2015, 3, 813". The fourth method reduces the reflectance by simultaneously adjusting the electric dipole and magnetic dipole at the interface of a medium with independent electromagnetic field properties, for example.

[0055] The fifth type of metasurface structure is the so-called high-contrast type, which is described in detail in "Seyedeh M. Kamali et al., "Decoupling optical function and geometrical form using conformal flexible dielectric metasurfaces", Nature Communications, 2016, 7, 11618". The fifth type, for example, utilizes the large difference in refractive index between the antenna and the surrounding medium to realize multiple modes of Fabry-Perot resonance with a low Q value. These multiple modes include electric dipoles and magnetic dipoles.

[0056] The sixth method of metasurface structure is the 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 the phase (effective refractive index) by changing the filling rate in a unit cell of media with different refractive indices, for example.

[0057] The solid immersion lens 60 configured as above focuses the infrared laser light L emitted from the light source 4a onto a predetermined portion of the semiconductor device 11. The action of the solid immersion lens 60 will be described with reference to FIG.

[0058] 3, the infrared laser light L emitted from the light source 4a of the LSM unit 4 is refracted by the metalens 62 of the solid immersion lens 60, passes through the second portion 612 of the base 61 of the solid immersion lens 60, the first portion 611 of the base 61 of the solid immersion lens 60, and the semiconductor substrate 12 of the semiconductor device 11 in this order, and is focused on the integrated circuit 13. In other words, the focusing point C of the infrared laser light L is positioned on the integrated circuit 13.

[0059] A focal point C of the infrared laser light L occurs on the semiconductor device 11 side (the side opposite the metalens 62 with respect to the first portion 611 of the solid immersion lens 60). Therefore, it is possible to control the distance between the metalens 62 and the focal point C by adjusting the thickness of the base 61 of the solid immersion lens 60. And, because it is possible to control the distance between the metalens 62 and the focal point C, there is no restriction on the size of the metalens 62 that is effective as a lens, and the degree of freedom in phase design is improved, which is effective in aberration correction, etc.

[0060] Since the infrared laser light L passes through the first portion 611 of the base 61 of the solid immersion lens 60, the size of the first portion 611 is a size that allows the infrared laser light L to pass through. In other words, the size of the first portion 611 only needs to be equal to or larger than the size through which the infrared laser light L can pass, and the first portion 611 can be made smaller in size depending on the optical path of the infrared laser light L.

[0061] The infrared laser light L focused at 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 61 of the solid immersion lens 60, and the second portion 612 of the base 61 of the solid immersion lens 60 in this order, and is detected by the photodetector 4b, allowing the semiconductor device 11 to be observed.

[0062] [Manufacturing method of solid immersion lens] [Metalens formation method] We will now explain a method for manufacturing the solid immersion lens 60. First, we will explain a method for forming the metalens 62 of the solid immersion lens 60 with reference to Figures 8 to 10. Figures 8 to 10 are diagrams for explaining the method for forming the metalens 62 of the solid immersion lens 60.

[0063] 8(a) and 8(b), a mask layer 83 is formed on a substrate 80 that will become the base 61 of the solid immersion lens 60 (layer formation step). The mask layer 83 is formed by laminating a hard mask 81 and a resist 82. The shape of the substrate 80 may be a thin film or a flat plate.

[0064] 8(a), a hard mask 81 is formed on an upper surface 80a of a substrate 80. The hard mask 81 can be formed by, for example, resistance heating deposition. Examples of materials for the hard mask 81 include silicon nitride. The thickness of the hard mask 81 can be, for example, about 300 nm.

[0065] 8(b), a resist 82 is formed on the upper surface 81a of the hard mask 81. The resist 82 can be formed by, for example, applying an electron beam resist. Examples of materials for the resist 82 include electron beam resists such as ZEP520A. The thickness of the resist 82 can be, for example, about 300 nm.

[0066] 9(a) and 9(b), a plurality of openings 84 are formed in a mask layer 83 formed on a substrate 80 (opening process). The openings 84 include a hard mask opening 84a formed in a hard mask 81 and a resist opening 84b formed in a resist 82. The hard mask opening 84a is formed via a resist opening 84b. Therefore, the hard mask opening 84a and the resist opening 84b are formed at the same position as each other when viewed from a direction perpendicular to the upper surface 80a of the substrate 80. The resist opening 84b can be formed by performing electron beam lithography and development on the resist 82. The hard mask opening 84a can be formed by performing inductively coupled plasma-reactive ion etching (ICP-RIE) on the hard mask 81.

[0067] The mask layers 83 after the opening step may be formed so as to be periodically arranged when viewed from a direction perpendicular to the upper surface 80a of the substrate 80. More specifically, when incident light of a predetermined wavelength is incident on the solid immersion lens 60, the mask layers 83 may be formed so as to be arranged at a period shorter than the predetermined wavelength when viewed from a direction perpendicular to the upper surface 80a of the substrate 80. Here, the size, shape, and arrangement of the mask layers 83 are the size, shape, and arrangement of the antennas 70 of the metalens 62. The mask layers 83 may be, for example, circular with a diameter of 50 nm or more and 270 nm or less. The mask layers 83 may also be formed so as to be arranged at a period of, for example, 300 nm. Furthermore, at least one of the size, shape, and arrangement of the multiple mask layers 83 may vary within the upper surface 80a of the substrate 80 when viewed from a direction perpendicular to the upper surface 80a of the substrate 80. Here, "varying within the upper surface 82a of the substrate 80" means that it may vary depending on the position on the upper surface 82a of the substrate 80.

[0068] 10(a), etching is performed through the multiple openings 84 to form multiple recesses 80c in the substrate 80 (etching step). The etching may be, for example, dry etching, and in particular, reactive ion etching (RIE) may be performed. The etching is performed from the upper surface 80a of the substrate 80 to the upper surface 80b inside the substrate 80. This allows the recesses 80c to be formed to a predetermined depth (etching depth) in the upper surface 80a of the substrate 80. The etching depth may be, for example, about 800 nm.

[0069] Subsequently, as shown in FIG. 10(b), the mask layer 83 is removed (removal step). That is, the hard mask 81 is lifted off. This makes it possible to remove the resist 82 formed on the hard mask 81 together with the hard mask 81. As a result, it is possible to form an upper surface 80a and an upper surface 80b on the substrate 80. Then, the convex portion 80d having the upper surface 80a becomes the antenna 70 of the metalens 62 of the solid immersion lens 60, and the upper surface 80b becomes the second surface 61b of the solid immersion lens 60. In this manner, the metalens 62 of the solid immersion lens 60 can be formed.

[0070] [Method of forming the first part] 11 to 13, a method for forming the first portion 611 of the solid immersion lens 60 will be described. FIGS. 11 to 13 are diagrams for explaining the method for forming the first portion 611 of the solid immersion lens 60.

[0071] 11(a) and 11(b), a mask layer 93 is formed on a substrate 90 that will become the base 61 of the solid immersion lens 60 (layer formation step). The mask layer 93 is formed by laminating a hard mask 91 and a resist 92. The shape of the substrate 90 may be a thin film or a flat plate.

[0072] 11(a), a hard mask 91 is formed on an upper surface 90a of a substrate 90. The hard mask 91 can be formed by, for example, resistance heating deposition. Examples of materials for the hard mask 91 include silicon nitride. The thickness of the hard mask 91 can be, for example, about 300 nm.

[0073] 11(b), a resist 92 is formed on an upper surface 91a of the hard mask 91. The resist 92 can be formed, for example, by applying an electron beam resist. Examples of materials for the resist 92 include electron beam resists such as ZEP520A. The thickness of the resist 92 can be, for example, about 300 nm.

[0074] 12(a) and 12(b), the mask layer 93 formed on the substrate 90 is removed (removal step). The portion (removed portion 94) to be removed from the mask layer 93 formed on the substrate 90 includes a hard mask removed portion 94a removed from the hard mask 91 and a resist removed portion 94b removed from the resist 92. The hard mask removed portion 94a is removed via the resist removed portion 94b. Therefore, the hard mask removed portion 94a and the resist removed portion 94b are at the same position as each other when viewed from a direction perpendicular to the upper surface 90a of the substrate 90. The resist removed portion 94b can be removed by performing electron beam lithography and development on the resist 92. The hard mask removed portion 94a can be removed by performing Induced Coupled Plasma-Reactive Ion Etching (ICP-RIE) on the hard mask 91.

[0075] 13(a), etching is performed through the remover 94 to remove the substrate 90 to a predetermined depth (etching depth) (etching step). The etching may be, for example, dry etching, and in particular, reactive ion etching (RIE: Reactive Ion Etching). The etching is performed from the upper surface 90a of the substrate 90 to the upper surface 90b inside the substrate 90. The etching depth may be, for example, about 5 μm.

[0076] 13(b), the mask layer 93 is removed (mask layer removal step). That is, the hard mask 91 is lifted off. This makes it possible to remove the resist 92 formed on the hard mask 91 together with the hard mask 91. As a result, the upper surface 90a and the upper surface 90b can be formed on the substrate 90. Then, the convex portion 90d having the upper surface 90a becomes the first portion 611 of the base 61 of the solid immersion lens 60. In this manner, the first portion 611 of the solid immersion lens 60 can be formed.

[0077] [Action and Effects] As described above, in the optical device 1, the solid immersion lens 60 includes the metalens 62 arranged on the second surface 61b of the base 61. This makes it possible to control the effective refractive index of the metalens 62 by controlling at least one of the size, shape, and arrangement of the multiple antennas 70 included in the metalens 62 in the direction along the second surface 61b of the base 61. This makes it possible to thin the solid immersion lens 60. Furthermore, when the solid immersion lens 60 is brought into contact with the semiconductor device 11, the first surface 61a of the base 61 is brought into contact with the semiconductor device 11. This makes it possible to handle the solid immersion lens 60 more easily than, for example, when the metalens 62 is brought into contact with the semiconductor device 11. Therefore, according to this optical device 1, it is possible to realize a thin solid immersion lens 60 and easy handling of the solid immersion lens 60.

[0078] Furthermore, according to the optical apparatus 1, since the optical device is the photodetector 4b, the light emitted from the semiconductor device 11 or the light reflected by the semiconductor device 11 can be detected with high accuracy.

[0079] Furthermore, according to the optical apparatus 1, since the optical device is the light source 4a, the semiconductor device 11 can be irradiated with light with high precision.

[0080] Furthermore, according to the optical device 1, since the area of ​​the first surface 61a of the solid immersion lens 60 is smaller than the area of ​​the second surface 61b, it is possible to ensure a size sufficient for holding the solid immersion lens 60 in the base 61 while reliably abutting the first surface 61a of the base 61 against the semiconductor device 11 so as to prevent, for example, the interposition of an air layer.

[0081] Furthermore, the optical device 1 includes an objective lens 21 that is disposed at a position on the optical path between the solid immersion lens 60 and the optical device (light source 4a, photodetector 4b), and therefore the focus of the objective lens 21 can be adjusted to a desired position on the semiconductor device 11 with high precision.

[0082] Moreover, as described above, the solid immersion lens 60 can be made thinner and easier to handle. Moreover, while ensuring a size sufficient for holding the solid immersion lens 60 in the base 61, the first surface 61a of the base 61 can be reliably abutted against the semiconductor device 11 so as to prevent, for example, the presence of an air layer.

[0083] Moreover, according to the solid immersion lens 60, the base 61 includes a first portion 611 having a first surface 61a and a second portion 612 having a second surface 61b, and when viewed from a direction parallel to the optical axis A of the metalens 62, an outer edge 612a of the second portion 612 is located outside an outer edge 611a of the first portion 611, and the first portion 611 and the second portion 612 may be formed integrally. This allows the solid immersion lens 60 to be stably held in the second portion 612. Also, it is possible to prevent an interface that causes refraction and reflection of light from being formed between the first portion 611 and the second portion 612.

[0084] [Variations] The above-described embodiment can be implemented in various forms with various modifications and improvements based on the knowledge of those skilled in the art.

[0085] In the above-described embodiment, the light source of the optical device 1 is not limited to the light source 4a that irradiates the infrared laser light L. The light source of the optical device 1 may be a light source that irradiates ultraviolet light or a light source that irradiates visible light.

[0086] Furthermore, in the above-described embodiment, the optical device 1 was equipped with a light source 4a and a photodetector 4b, but the optical device 1 may be configured as an illumination device equipped with a light source and no photodetector, or may be configured as an observation device equipped with a photodetector and no light source.

[0087] Furthermore, in the above-described embodiment, the optical device 1 does not necessarily have to include the objective lens 21. By not including the objective lens 21 in the optical device 1, the device can be made smaller.

[0088] Furthermore, in the above-described embodiment, the solid immersion lens holder 8 is not limited to the configuration in the above-described embodiment as long as it is capable of holding the solid immersion lens 60. For example, the lens holding portion 8b of the solid immersion lens holder 8 does not need to have a gap with respect to the solid immersion lens 60.

[0089] In the above-described embodiment, the semiconductor device 11 does not have to be molded in the resin 14 as the molded semiconductor device 10 .

[0090] For example, in the above-described embodiment, the shape of the solid immersion lens 60 when viewed from a direction parallel to the optical axis A is not particularly limited, and may be, for example, circular when viewed from a direction parallel to the optical axis A.

[0091] Furthermore, in the above-described embodiment, the shape of the first portion 611 of the base 61 of the solid immersion lens 60 when viewed from a direction parallel to the optical axis A is not particularly limited, and may be, for example, circular when viewed from a direction parallel to the optical axis A.

[0092] Furthermore, in the above-described embodiment, the first portion 611 and the second portion 612 of the base 61 of the solid immersion lens 60 do not have to be integrally formed. The first portion 611 and the second portion 612 of the base 61 of the solid immersion lens 60 may be formed of different materials.

[0093] Furthermore, in the above-described embodiment, there is no particular limitation on the shape of the antenna 70. For example, the antenna 70 may have a shape corresponding to the type of metasurface structure of the metalens 62.

[0094] Furthermore, in the above-described embodiment, the antenna 70 does not have to be made of silicon. For example, the antenna 70 may be made of germanium, gold, silver, chromium, or the like. Even in these cases, the effective refractive index of the metalens 62 can be set to a suitable value.

[0095] Furthermore, in the above-described embodiment, the antennas 70 are not limited to the arrangement in the above-described embodiment as long as they can focus the infrared laser light L emitted from the light source 4a of the LSM unit 4 on a predetermined portion of the semiconductor device 11. For example, the antennas 70 may be periodically arranged in a honeycomb or radial pattern when viewed from a direction parallel to the optical axis A, or may be non-periodically arranged when viewed from a direction parallel to the optical axis A. [Explanation of symbols]

[0096] 1...optical apparatus, 3...high-sensitivity camera (optical device, photodetector), 4a...light source (optical device), 4b...photodetector (optical device), 6...stage (support), 11...semiconductor device (object), 21...objective lens, 60...solid immersion lens, 61...base, 61a...first surface, 61b...second surface, 611...first portion, 611a...outer edge, 612...second portion, 612a...outer edge, 62...metalens, A...optical axis.

Claims

1. a base including a first portion having a first surface and a second portion having a second surface opposite the first surface; a metalens having a plurality of antennas arranged two-dimensionally at a predetermined period on the second surface; the first portion is a protrusion on one surface of the base, A solid immersion lens, wherein an area of ​​the first surface is smaller than an area of ​​the second surface.

2. 2. The solid immersion lens according to claim 1, wherein the area of ​​the first surface is 0.001 to 0.5 times the area of ​​the second surface.

3. The solid immersion lens according to claim 1 , wherein the base is integrally formed.

4. 4. The solid immersion lens according to claim 1, wherein the base is formed of silicon, gallium arsenide, or gallium phosphide.

5. The solid immersion lens according to any one of claims 1 to 4, wherein the plurality of antennas are formed from silicon, germanium, gold, silver, or chromium.

6. A support portion that supports an object; A solid immersion lens according to any one of claims 1 to 4, an objective lens disposed on an optical path passing through the solid immersion lens; The first surface abuts the object.

7. 7. The optical device of claim 6, wherein light from the objective lens is refracted by the metalens of the solid immersion lens and is focused inside the target object via the second portion and the first portion.

8. 8. The optical device according to claim 6, wherein light from the object passes through the first portion and the second portion in this order, and is guided to the objective lens.

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