Optical probe, probe card, measurement system, and measurement method

Abstract

The optical probe is composed of a core and a cladding portion arranged on the periphery of the core, and the incident surface on which the optical signal is incident is a curved surface with a curvature radius (R). Using the radiation angle (γ) of the optical signal, the effective incident radius (Se) at the incident surface of the optical signal propagating in the core without passing through the cladding portion, the refractive index (n(r)) of the core at the incident point of the incident surface of the optical signal, and the refraction angle (β) at the incident point, the curvature radius (R) and the central half angle (ω) at the incident point satisfy the following relationship: R = Se / sin(ω), ω = ±sin ‑1 ({K2 2 / (K1 2 +K2 2 )} 1 / 2 ). Among them, K1=n(r)×cos(β)-cos(γ / 2), K2=n(r)×sin(β)-sin(γ / 2).

Description

Technical Field

[0001] The present invention relates to an optical probe, a measurement system, and a measurement method used for measuring characteristics of an optical semiconductor element. Background Art

[0002] Silicon photonics technology is used to form optical semiconductor elements on wafers that use electrical and optical signals as input and output signals. In order to measure the characteristics of optical semiconductor elements when they are formed on wafers, a measurement system having electrical probes that propagate electrical signals and optical probes that propagate optical signals is used to connect the optical semiconductor elements to a measurement device such as a tester.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 62-31136

[0006] Patent Document 2: Japanese Patent Application Laid-Open No. 60-64443 Summary of the invention

[0007] Problem that the invention aims to solve

[0008] In the measurement method using an optical probe, there is sometimes a positional deviation between the incident surface of the optical probe on which the optical signal from the optical semiconductor element is incident and the optical semiconductor element, and an angular offset is generated between the central axis of the optical probe and the optical axis of the optical signal from the optical semiconductor element. The power of the optical signal incident on the optical probe changes due to the positional deviation and angular offset, thereby impairing the stability of the output of the measured optical signal. Due to such variable factors, etc., there is a problem of reduced measurement accuracy in the measurement using the optical probe.

[0009] In view of the above problems, an object of the present invention is to provide an optical probe, a probe card, a measurement system, and a measurement method capable of measuring an optical semiconductor element in a short time and with high accuracy in a wafer state.

[0010] Solutions for solving problems

[0011] According to one embodiment of the present invention, an optical probe is provided in which the incident surface of the optical signal is a curved surface with a curvature radius. When using the radiation angle γ of the optical signal, the effective incident radius Se of the optical signal propagating in the core without passing through the cladding portion, the refractive index n(r) of the core at the incident point of the incident surface of the optical signal, and the refraction angle β at the incident point, the curvature radius R of the incident surface and the central half angle ω at the incident point satisfy the following relationship: R = Se / sin(ω), ω = ±sin -1 ({K2 2 / (K12 +K2 2 )} 1 / 2 ). Among them, K1=n(r)×cos(β)-cos(γ / 2), K2=n(r)×sin(β)-sin(γ / 2).

[0012] Effects of the Invention

[0013] According to the present invention, it is possible to provide an optical probe, a probe card, a measurement system, and a measurement method capable of measuring an optical semiconductor element in a wafer state in a short time, with high accuracy, and stably. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic diagram showing the structure of the optical probe according to the first embodiment.

[0015] Figure 2 FIG. 1 is a schematic diagram showing the structure of the optical probe at the maximum working distance.

[0016] Figure 3 It is a schematic plan view showing an example of deviation between the central axis of the optical probe and the optical axis of the optical signal.

[0017] Figure 4 Schematic diagram showing examples of tilt angles.

[0018] Figure 5 It is a schematic diagram showing the structure of a planar light probe whose incident end is a plane.

[0019] Figure 6 This is a graph showing an example of an incident intensity pattern measured using a planar light probe.

[0020] Figure 7 It is a graph showing the relationship between the radius of curvature of the incident surface of the optical probe and the numerical aperture at the incident surface.

[0021] Figure 8 It is a graph showing the relationship between the radius of curvature of the incident surface and the incident angle ratio.

[0022] Fig. 9 It is a graph showing the relationship between the radiation half angle of the optical signal and the cladding incident angle.

[0023] Fig.10 is a graph showing an example of an incident intensity pattern.

[0024] Fig.11 This is a conceptual diagram of an incident intensity pattern when the position of the optical axis of the optical signal relative to the central axis of the optical probe is changed.

[0025] Fig.12This is a graph showing changes in the incident intensity pattern when the working distance is changed.

[0026] Fig.13 It is a graph showing the relationship between the curvature radius of the incident surface and the effective incident radius.

[0027] Fig.14 It is a graph showing the relationship between the radius of curvature of the incident surface and the incident stable distance.

[0028] Fig.15 It is a graph showing the relationship between the radius of curvature of the incident surface and the maximum working distance.

[0029] Fig.16 This is a graph showing the loss characteristics of an optical signal incident on an optical probe.

[0030] Fig.17 It is a schematic diagram showing a configuration example of a measurement system using the optical probe according to the first embodiment.

[0031] Fig.18 This is a flowchart showing an example of a measurement method using the optical probe according to the first embodiment.

[0032] Fig.19 It is a schematic diagram showing the structure of an optical probe according to the second embodiment.

[0033] Fig. 20 It is a schematic diagram showing the structure of an optical probe according to the third embodiment. DETAILED DESCRIPTION

[0034] Next, the embodiments of the present invention will be described with reference to the accompanying drawings. In the description of the following drawings, the same or similar parts are marked with the same or similar figure marks. However, it should be noted that the drawings are schematic. In addition, the embodiments shown below illustrate the devices and methods for concretizing the technical concept of the present invention, and the embodiments of the present invention are not used to limit the structure, configuration, etc. of the constituent parts to the following structures, configurations, etc. The embodiments of the present invention can be subjected to various changes in the claims.

[0035] (First Embodiment)

[0036] like Figure 1 As shown, the optical probe 10 according to the first embodiment of the present invention receives an optical signal L output from an optical semiconductor element 20. The optical probe 10 has a refractive index distribution type optical waveguide composed of a core 111 and a cladding 112 arranged on the periphery of the core 111. The refractive index of the core 111 is larger than the refractive index of the cladding 112. Figure 1One end portion of the optical probe 10 including an incident surface 100 into which an optical signal L is incident is shown. The incident surface 100 is a convex spherical surface with a constant radius of curvature R.

[0037] exist Figure 1 , the core radius Cr is the radius of the core 111. In addition, the probe radius Dr is the radius of the optical probe 10 including the cladding 112. The optical probe 10 can be an optical fiber, a structure in which an optical fiber and a lens are combined, etc. For example, the optical probe 10 can be manufactured using a graded-index (GI) optical fiber.

[0038] exist Figure 1 In FIG. 1 , the extension direction of the central axis C10 of the core 111 of the optical probe 10 and the optical axis C20 of the optical signal L is set as the Z direction. In addition, the plane perpendicular to the Z direction is set as the XY plane, and Figure 1 The left-right direction of the paper is set as the X direction, and the direction perpendicular to the paper is set as the Y direction.

[0039] The optical semiconductor element 20 is, for example, a vertical cavity surface emitting laser (VCSEL) etc. The optical semiconductor element 20 is optically connected to the optical probe 10 , and the optical signal L output from the optical semiconductor element 20 is incident on the optical probe 10 .

[0040] The optical probe 10 and the optical semiconductor element 20 are arranged at a working distance WD in the Z direction. The working distance WD is set to a range in which the optical probe 10 can receive the optical signal L output from the optical semiconductor element 20. That is, the working distance WD is set so that the incident range of the optical signal L at the incident surface 100 is located at a position further inside than the outer edge of the core 111. Here, the incident range of the optical signal L is set to a range in which the optical signal L is 1 / e of the peak value. 2 The above intensity travels in a range of directions.

[0041] like Figure 1 As shown, an optical signal L having a radiation angle of γ is output from the optical semiconductor element 20. The optical signal L travels in the core 111 in such a manner that a refraction angle β is formed with the direction of the curvature radius at the incident point Q, which is the end of the incident range of the optical signal L at the incident surface 100. The central half angle of the incident surface 100 at the incident point Q is set to ω.

[0042] exist Figure 1 In the formula (1), the diameter of the incident range of the light signal L with a radiation angle of γ at the incident surface 100 is represented as the incident diameter Sd, and the radius of the incident range is represented as the incident radius Sr. Using the radiation angle γ of the light signal L, the incident diameter Sd is represented by the following formula (1):

[0043] Sd = 2 × WD × tan (γ / 2) (1)

[0044] exist Figure 21 shows a state where the distance between the incident surface 100 of the optical probe 10 and the optical semiconductor element 20 is the maximum working distance WD (hereinafter referred to as the "maximum working distance WDm") that can be obtained. Figure 2 As shown, the radiation half angle at the maximum working distance WDm is α. When the central axis C10 and the optical axis C20 coincide with each other at the maximum working distance WDm, the central half angle ω is maximum. Hereinafter, the maximum central half angle ω is referred to as "maximum central half angle ωm".

[0045] When measuring the optical signal L, it is necessary to consider the positional deviation between the optical probe 10 and the optical semiconductor element 20 in the XY plane. Figure 3 2 shows a state in which the central axis C10 of the optical probe 10 and the optical axis C20 of the optical signal L are offset in the X direction due to positional deviation.

[0046] exist Figure 3 In FIG. 1 , the effective incident radius Se is used to represent the incident area at the incident surface 100 of the optical signal L propagating in the core 111 without passing through the cladding portion 112. Figure 3 , the incident radius Sr of the optical signal L is shown. If the range of the incident radius Sr is included in the range specified by the effective incident radius Se, the transmission loss of the optical signal L in the optical probe 10 can be suppressed even if there is a positional deviation between the optical probe 10 and the optical semiconductor element 20. Figure 3 In FIG. 1 , the distance between the central axis C10 and the optical axis C20 at which no transmission loss of the optical signal L occurs is represented as an “incident stable distance Ds”.

[0047] In addition, if Figure 4 As shown, when the central axis C10 of the optical probe 10 is not parallel to the optical axis C20 of the optical signal L and the central axis C10 and the optical axis C20 intersect at an inclination angle ζ, an incident variation of the optical signal L also occurs in the optical probe 10. As described in detail later, according to the optical probe 10, the incident variation can be suppressed even when the inclination angle ζ occurs.

[0048] Next, the measurement of the radiation angle of the optical signal L is described. By setting the working distance WD to be fixed and moving the optical semiconductor element 20 relative to the incident surface 100 in the X direction and the Y direction, a characteristic (hereinafter referred to as an "incident intensity pattern") indicating the relationship between the incident intensity and the moving distance can be obtained. First, the measurement of the radiation angle of the optical signal L using the optical semiconductor element 20 can be described. Figure 5 The incident surface 100 shown is a planar optical probe (hereinafter referred to as a “planar optical probe”) for measuring an incident intensity pattern.

[0049] Figure 5The plane light probe shown uses an optical fiber with a core diameter Cd of 2×Cr and a numerical aperture NA of sin(αf). The incident diameter Sd of the light signal L incident on the incident surface 100 is 2×Sr. In addition, according to the numerical aperture NA of the plane light probe, the relationship between the radiation angle γ and the incident allowable half angle αf is γ<2αf (αf=sin -1 (NA)).

[0050] When the optical signal L with a radiation angle of γ is incident on the incident surface 100 of the planar light probe, the optical signal L traveling inside the core 111 is incident on the boundary surface between the core 111 and the cladding 112 at an incident angle of π / 2-β. The refractive index n(r) of the core 111 at a distance r in the radial direction from the central axis C10 is used to define the refractive angle β using equation (2):

[0051] β=sin -1 (sin(γ / 2) / n(r))…(2)

[0052] The refractive index n(r) is expressed by the following formula (3):

[0053] n(r)=n(c)×(1-(A 1 / 2 ×r) 2 / 2)…(3)

[0054] Here, n(c) is the refractive index of the core 111 at the central axis C10, and A 1 / 2 is the refractive index distribution constant of the core 111 .

[0055] In addition, the boundary refractive index n(rc) and boundary refractive angle β(rc) of the core 111 at the position of the core radius Cr are expressed by equations (4) and (5), respectively:

[0056] n(rc)=n(c)×(1-(A 1 / 2 ×Cr) 2 / 2)…(4)

[0057] β(rc)=sin -1 {sin(γ / 2) / n(rc)}…(5)

[0058] When the refraction angle β is equal to or greater than the boundary refraction angle β(rc), the optical signal L is not reflected and propagated in the core 111, but is transmitted and radiated to the cladding 112. Therefore, the optical signal L propagating in the core 111 is attenuated.

[0059] Next, the measurement of the radiation angle of the optical signal L is described. By moving the optical semiconductor element 20 relative to the incident surface 100 on the XY plane while the working distance WD is fixed, an incident intensity pattern indicating the relationship between the incident intensity and the moving distance is obtained for the optical signal L.

[0060] Figure 6 The incident intensity pattern of the incident intensity P of the light signal L when the optical semiconductor element 20 is moved relative to the incident surface 100 of the planar light probe in each case where the working distance WD is 20 μm, 50 μm, 100 μm, 150 μm, and 200 μm, respectively. As the working distance WD increases, the distance from the central axis C10 at the incident surface 100 to the outer edge of the light signal L (hereinafter referred to as "movement distance D") also increases. In addition, Figure 6 This is a diagram showing a light signal L having a radiation angle γ of 17.6° being incident on an incident surface 100 of a planar optical fiber having a core radius Cr of 44.5 μm and a numerical aperture NA of 0.29.

[0061] like Figure 6 As shown in FIG. 1 , when the working distance WD is small, the incident intensity pattern of the incident intensity P is a trapezoid. As the working distance WD increases, the peak value of the incident intensity P decreases, and the shape of the incident intensity pattern approaches a Gaussian shape. Figure 6 In the incident intensity pattern shown, when the working distance WD is 100 μm or more, there is a tendency that the attenuation of the peak value of the incident intensity P with respect to the moving distance D becomes larger.

[0062] The working distance WD is set according to the incident intensity pattern so that the incident diameter Sd (Sd=2×Sr) and the core diameter Cd (Cd=2×Cr) are substantially equal. Figure 6 The incident intensity pattern shown in FIG. 1 is a condition in which the peak value of the incident intensity P does not decrease and the shape of the incident intensity pattern becomes approximately Gaussian when WD=150 μm, which is a condition in which the outer edge of the core 111 of the planar light probe is approximately consistent with the outer edge of the optical signal L. In this case, according to Figure 6 , so that the incident intensity P is 1 / e of the peak value 2 1 / e of the XY plane 2 The moving distance De is De=4×Sr=112 μm. Therefore, the incident intensity P is 1 / e of the peak value. 2 1 / e 2 Radiation angle γe, equation (6) holds true:

[0063] tan(γe / 2)=De / (4×WD)=0.187…(6)

[0064] According to formula (6), γe = 2 × tan -1 (De / (4×WD))=21.2°.

[0065] In addition, the 1 / 2 moving distance Dh that makes the incident intensity P 1 / 2 of the peak value is 77.5 μm. Therefore, for the 1 / 2 radiation angle γh that makes the incident intensity P 1 / 2 of the peak value, equation (7) holds:

[0066] tan(γh / 2)=Dh / (4×WD)=0.129…(7)

[0067] According to formula (7), γh = 2 × tan -1 (Dh / (4×WD))=14.7°.

[0068] As described above, the radiation angle of the optical signal L can be calculated based on the relationship between the relative movement distance of the incident surface 100 and the optical semiconductor element 20 on the XY plane perpendicular to the central axis C10 and the incident intensity of the optical signal L.

[0069] On the other hand, the measured values ​​of the radiation angle obtained using a measuring instrument such as a far field pattern (FFP) measuring instrument (hereinafter referred to as "measured values") are γe = 21.2° and γh = 17.6°. When the optical semiconductor element 20 is a VCSEL, the incident intensity pattern of the incident intensity P is approximately trapezoidal, not Gaussian. Therefore, a smaller 1 / 2 radiation angle γh is measured, which makes the incident intensity P 1 / 2 of the peak value.

[0070] Next, the measurement of the radiation angle using the optical probe 10 whose incident surface 100 is a curved surface with a curvature radius R is described. Here, the numerical aperture NA at the incident surface 100 of the optical probe 10 is set to sin(α). At the incident surface 100 of the optical probe 10, according to Snell's law, the following relationship (8) holds:

[0071] sin(α+ωm)=n(r)×sin(β+ωm)…(8)

[0072] According to formula (8), the following formula (9) is obtained:

[0073] α=sin -1 (n(r)×sin(β+ωm)}-ωm…(9)

[0074] At the end of the core diameter Cd, ωm=Cr / R.

[0075] Therefore, it is possible to obtain a relationship between the radius of curvature R of the incident surface 100 and the radiation half-angle α of the optical signal L. The radiation half-angle α is also the allowable incident half-angle of the optical signal L incident on the incident surface 100. When the radiation angle γ exceeds 2×α, the optical signal L passes through the boundary between the core portion 111 and the cladding portion 112 and radiates toward the cladding portion 112, thereby attenuating and causing transmission loss.

[0076] exist Figure 7 The relationship between the numerical aperture (hereinafter referred to as "incident numerical aperture RNA") at the incident surface 100 with a curvature radius of R when using an optical fiber with NA = 0.29 and a core diameter Cd = 89 μm and when using an optical fiber with NA = 0.275 and a core diameter Cd = 62.5 μm is shown.

[0077] like Figure 7 As shown, the smaller the radius of curvature R is, the larger the incident numerical aperture RNA of the optical probe 10 is. For example, when an optical probe 10 with a radius of curvature R of 145 μm is constructed using an optical fiber with NA=0.29, RNA=0.5 and γ=60° become the incident boundary conditions of the optical signal L. The "incident boundary conditions" are conditions that allow the optical signal L to propagate in the core 111 without passing through the cladding 112. On the other hand, when an optical probe 10 with a radius of curvature R of 145 μm is constructed using an optical fiber with NA=0.275, RNA=0.4 and γ=48° become the incident boundary conditions.

[0078] If the radiation angle γ of the optical signal L is in the relationship of α≥γ / 2, after the optical signal L is incident on the core 111 of the optical probe 10, the optical signal L does not pass through the cladding portion 112, and propagates in the core 111 with almost no attenuation. By setting the incident surface 100 as a curved surface in this way, compared with an optical probe whose incident surface 100 is a flat surface, the transmission loss can be suppressed, and the incident optical signal L can be incident even if the radiation angle γ is large. Therefore, it is effective to set the incident surface 100 as a curved surface, especially when the radiation angle γ of the optical signal L is large. That is, when the radiation angle γ of the optical signal L is large, the incident boundary condition of the optical probe 10 can be adjusted by setting the radius of curvature R.

[0079] When the optical probe 10 moves to the left of the paper along the X direction by the incident stable distance Ds, the equation (10) holds true at the incident surface 100 of the optical probe 10:

[0080] sin(γ / 2+ω)=n(r)×sin(β+ω)…(10)

[0081] Here, according to the relationship regarding the numerical aperture NA of the optical waveguide (eg, optical fiber) used in the optical probe 10

[0082] Formula β = sin -1 (NA / n(r)), we get formula (11):

[0083] ω=±sin -1 ({K2 2 / (K1 2 +K2 2 )} 1 / 2 )…(11)

[0084] In formula (11), coefficient K1 and coefficient K2 are as follows:

[0085] K1=n(r)×cos(β)-cos(γ / 2)

[0086] K2=n(r)×sin(β)-sin(γ / 2)

[0087] In addition, when the effective incident radius Se is consistent with the core radius Cr of the optical probe 10, when the radiation half angle α of the allowable optical signal L incident on the optical probe 10 when the working distance WD is the maximum working distance WDm, the curvature radius R satisfies the relationship of formula (12), and the center half angle ω is expressed by (13):

[0088] R ≥ Cr / sin(ω)…(12)

[0089] ω=±sin -1 ({K2 2 / (K1 2 +K2 2 )} 1 / 2 )…(13)

[0090] Here, WDm=Cr / tan(α). In formula (13), coefficient K1 and coefficient K2 are the following values:

[0091] K1=n(r)×cos(β)-cos(α)

[0092] K2=n(r)×sin(β)-sin(α)

[0093] Here, α = sin -1 {n(r)×sin(β+ω)}−ω. When the radiation angle γ of the optical signal L of the optical semiconductor element to be measured is known, α and ω can be set so that 2α≥γ, and the curvature radius R of the incident surface 100 can be set.

[0094] When the optical probe 10 moves the incident stable distance Ds, the following equations (14) to (16) hold true:

[0095] Se=R×sin(ω)…(14)

[0096] Ds=Se-Sr…(15)

[0097] Sr=WD×tan(γ / 2)…(16)

[0098] Here, Cr≥Se>Sr≥0, R≥Dr. The larger the radius of curvature R is, the larger the effective incident radius Se is, and the smaller the working distance WD is, the smaller the incident radius Sr is. By setting the incident stable distance Ds to be large, that is, setting the effective incident radius Se to be large and setting the incident radius Sr to be small, the allowable value of the position deviation between the center axis C10 of the optical probe 10 and the optical axis C20 of the optical signal L for measuring the stable characteristics of the optical signal L can be increased. Based on formula (14), the following formula (17) is obtained for the radius of curvature R:

[0099] R=Se / sin(ω)…(17)

[0100] exist Figure 8 , the relationship between the incident angle ratio Ir of the optical probe 10 and the plane optical probe and the curvature radius R is shown with respect to the incident angle of the optical signal L after passing through the incident surface 100 at the boundary surface between the core 111 and the cladding 112 (hereinafter referred to as "cladding incident angle θ"). Here, the cladding incident angle θ1 of the plane optical probe and the cladding incident angle θ2 of the optical probe 10 with the curvature radius R, the incident angle ratio Ir = θ2 / θ1. In addition, in the plane optical probe, the curvature radius R is infinite, and the incident angle ratio Ir is 1.

[0101] like Figure 8 As shown, the smaller the radius of curvature R is, the smaller the incident angle ratio Ir is, and the smaller the cladding incident angle θ is. Therefore, even if there is an angle change in the optical axis C20 of the optical signal L relative to the central axis C10 of the optical probe 10, the smaller the radius of curvature R is, the less likely it is that the optical signal L will change when propagating in the core 111 of the optical probe 10. For example, in an optical probe array in which the optical probes 10 are arranged in an array, a small tilt angle ζ is generated in the X direction or the Y direction, and the cladding incident angle θ changes. However, since the incident surface 100 in the optical probe 10 is a curved surface, the cladding incident angle θ becomes smaller. Therefore, even if the angle of the optical axis C20 relative to the central axis C10 changes due to the generation of the tilt angle ζ, the cladding incident angle θ is sufficiently converged to below the cladding incident critical angle θ (rc) at which the optical signal L is attenuated by passing through the cladding portion 112, and attenuation caused by radiation from the cladding portion 112 is less likely to occur. Therefore, it is possible to suppress the variation of the optical signal L caused by the tilt angle ζ when propagating in the core 111 .

[0102] Fig. 9 The results are a comparison of the relationship between the cladding incident angle θ and the radiation half angle α of the incident light signal L when the incident surface 100 is a flat surface and when the incident surface 100 is a curved surface with a curvature radius R of 100 μm, 125 μm, and 150 μm. Fig. 9In the formula, the cladding incident critical angle θ(rc) is the critical angle of the cladding incident angle θ. When the cladding incident angle θ is greater than the cladding incident critical angle θ(rc), the optical signal L passes through the cladding portion 112 and is attenuated. Fig. 9 It can also be seen from the curve graph that by setting the incident surface 100 as a curved surface, the cladding incident angle θ can be reduced with respect to the radiation angle γ of the optical signal L. In addition, when the curvature radius R is small, the cladding incident angle θ tends to become smaller. Fig. 9 As shown in FIG. 1 , when the incident surface 100 is a curved surface, the cladding incident angle θ is sufficiently small relative to the cladding incident angle θ(rc) which is the critical angle. Therefore, by setting the incident surface 100 as a curved surface, even if the incident angle of the optical signal L is angularly offset at the incident surface 100 due to the tilt angle ζ, the attenuation of the optical signal L can be suppressed.

[0103] Fig.10 This is a graph comparing measured values ​​of incident intensity patterns when the working distance WD is 100 μm when the radius of curvature R of the incident surface 100 of the optical probe 10 is 70 μm, 74 μm, and 80 μm and when the incident surface 100 is a flat surface. Fig.10 The horizontal axis of the graph shown is the moving distance D. Fig.10 , the smaller the radius of curvature R, the greater the incident intensity P. This is because the cladding incident angle of the incident light becomes smaller according to the radius of curvature R, so that it is less likely to cause attenuation caused by cladding radiation. In contrast, when the incident surface 100 is a flat surface, the intensity of the incident intensity pattern is lower than when the incident surface 100 is a spherical surface, and the shoulders of the incident intensity pattern become rounded, and the attenuation is gentle.

[0104] Fig.11 This is a conceptual diagram of the incident intensity pattern when the position of the optical axis C20 of the optical signal L is changed by a distance Dxy in the X direction or Y direction relative to the central axis C10 of the optical probe 10 under a fixed working distance WD. The incident intensity pattern based on the change in distance Dxy is roughly trapezoidal. The flat portion of the incident intensity pattern where the incident intensity P=1 is the incident stable range corresponding to the incident stable distance Ds in the + direction and the - direction. Within this incident stable range, even if position deviation occurs, the incident intensity P does not change, and a stable incident intensity can be obtained. The incident movement range Dw and the incident stable range Dp for causing at least a portion of the optical signal L to be incident on the core 111 of the optical probe 10 are represented by Dw=2(Se+Sr) and Dp=2(Se-Sr)=2Ds.

[0105] When the incident surface 100 is a plane, Se=Cr. Therefore, the radiation angle γx in the X direction and the radiation angle γy in the Y direction that do not cause transmission loss are calculated by the following equations (18) and (19), respectively:

[0106] γx=2×tan -1 (Srx / WD)…(18)

[0107] γy=2×tan -1 (Sry / WD)…(19)

[0108] Here, Cr≥Se>Sr≥0.

[0109] Fig.12 It shows the change of the incident intensity pattern when the working distance WD is changed by 50 to 200 μm. Here, the optical probe 10 with a curvature radius R of 70 μm on the incident surface 100 is used. When the optical semiconductor element 20 is a VCSEL, the far-field pattern is a trapezoidal intensity distribution, so that the radiation angle γh at which the intensity is 1 / 2 of the peak intensity is approximately the radiation angle of the average value of the intensity distribution. Therefore, the effective incident radius Se and the incident radius Sr can also be regarded as the trajectory representing the average value of the incident intensity. Fig.11 According to Se-Sr=Dp / 2, Se+Sr=Dw / 2, we can get Se=1 / 4×(Dw+Dp), Sr=1 / 4×(Dw-Dp). Fig.12 , Dp = 40 (μm), Dw = 80 (μm). According to the above formula, Se = 30 (μm), Sr = 10 (μm). In the case of WD = 100 μm, γh = 2 × tan -1 (Sr / WD) = 2 × tan -1 (10 / 100) = 11.4°. When the radiation angle γh is set to 1 / 2 and 1 / e 2 When the radiation angle γe is in a proportional relationship, according to the incident intensity pattern, it can be obtained that γe = 2×(De / Dh)tan -1 (γh)=2×(66 / 56)tan -1 (10 / 100)=13.5°.

[0110] However, when WD = 100 to 200 (μm) as in this measurement, the measured value is not the far-field pattern but is closer to the reduced near-field pattern, and thus becomes a value deviated from the values ​​γe = 21.2° and γh = 17.6° measured from the measured value. Therefore, calibration is required to obtain the far-field pattern value.

[0111] When there is a difference between the value obtained from such an incident intensity pattern and the value obtained from the measured value, the difference can be reduced by performing the following processing.

[0112] When the radiation angle γ is used as the measured value, tan(γh / 2)=Sr / cWD. Here, the conditions for making the incident intensity P 1 / 2 of the peak value are Sr=10μm, γh=17.6°, so tan(17.6° / 2)=Sr / cWD=10 / cWD=0.155, and thus cWD=64.5μm. Here, cWD=Sr / tan(γ / 2) is the working distance obtained from the measured value of the radiation angle (hereinafter referred to as the "assumed working distance").

[0113] Using the assumed working distance cWD, 1 / e is calculated as follows 2 Radiation angle γe and 1 / 2 radiation angle γh:

[0114] γe=2×(De / Dh)×tan -1 (Sr / (cWD))

[0115] γh=2×tan -1 (Sr / (cWD))

[0116] Therefore, using the actual measured 1 / e 2 The radiation angles γe and γh in the X and Y directions are obtained by using the values ​​of the moving distance De and 1 / 2 the moving distance Dh. For example, the radiation angle of the reference VCSEL is used as a reference, and the radiation angle is set according to the difference from the radiation angle used as the reference. In this way, the radiation angle can be set more accurately according to the measured value.

[0117] Fig.13 is a graph showing the theoretical value of the relationship between the curvature radius R of the incident surface 100 and the effective incident radius Se. Fig.13 2 shows the case where the numerical aperture NA of the optical fiber used in the optical probe 10 is 0.29 and the case where the numerical aperture NA is 0.275. The relationship between the curvature radius R and the effective incident radius Se can be obtained from equation (17).

[0118] By making the effective incident radius Se consistent with the core diameter Cd, the effective incident radius Se can be used to the maximum extent to suppress the transmission loss caused by position deviation. Fig.13 According to the condition Se=Cr=44.5μm, in the optical probe 10 with NA=0.29 and core radius Cr=44.5μm, the curvature radius R can be set to about 155μm. In addition, according to the condition Se=Cr=31.3μm, in the optical probe 10 with NA=0.275 and core radius Cr=31.3μm, the curvature radius R can be set to about 127μm.

[0119] Fig.14The graphs are graphs showing the relationship between the incident stable distance Ds at which a stable incident intensity can be obtained and the curvature radius R when optical fibers with NA=0.275 and NA=0.29 are used in the optical probe 10 . Fig.14 The × mark shown indicates the measured value when NA = 0.29. Fig.14 As shown, the larger the curvature radius R, the larger the incident stable distance Ds. In addition, the larger the core diameter Cd (=2×Cr) of the optical fiber used in the optical probe 10, the larger the incident stable distance Ds. In the case of core radius Cr=44.5μm, the incident stable distance Ds can be set to approximately ±30μm. In the case of core radius Cr=31.3μm, the incident stable distance Ds can be set to approximately ±15μm.

[0120] Fig.15 : is a graph showing the relationship between the curvature radius R of the incident surface 100 and the maximum working distance WDm. When the core radius Cr = 44.5 μm and the curvature radius R = 155 μm, the maximum working distance WDm is slightly less than 300 μm. When the core radius Cr = 31.3 μm and the curvature radius R = 125 μm, the maximum working distance WDm is about 200 μm. When the optical probe 10 is used, WD ≤ WDm is set.

[0121] Fig.16 It is a graph showing the loss characteristics of the optical signal L incident on the optical probe 10 when WD=100 μm. Fig.16 The horizontal axis of the graph shown is the moving distance D. When the moving distance D that makes the loss change within 0.1 dB is set as the incident stable distance Ds, according to Fig.16 , when R=75μm, the incident stable distance Ds is ±15μm. In addition, when R=93μm, the incident stable distance Ds is ±20μm. When R=116μm, the incident stable distance Ds is more than ±20μm. On the other hand, when the incident surface 100 is a plane, the incident stable distance Ds is ±17μm. Based on the above, by setting the incident surface 100 as a curved surface, the incident stable distance Ds changes, and the larger the curvature radius R, the larger the incident stable distance Ds.

[0122] As described above, the optical probe 10 according to the first embodiment has a curvature radius R=Se / sin(ω) expressed by equation (17) and a center half angle ω=±sin(ω) expressed by equation (11). -1 ({K2 2 / (K1 2 +K2 2 )} 1 / 2) characteristics. Thus, the curvature radius R of the incident surface 100 of the optical probe 10 is set in such a way that the incident stable distance Ds becomes a large range. Thus, the incident variation corresponding to the position deviation and the tilt angle ζ can be suppressed, and the optical signal L can be stably incident on the optical probe 10. As a result, according to the measurement of the optical semiconductor element 20 using the optical probe 10, even if the optical probe 10 and the optical semiconductor element 20 have a position deviation and a tilt angle ζ in the XY plane, the transmission loss of the optical signal L incident on the incident surface 100 of the optical probe 10 can be suppressed.

[0123] In addition, by relatively moving the optical probe 10 and the optical semiconductor element 20 in the XY plane, the incident range of the optical signal L is within an appropriate working distance WD inside the core 111, and the optical signal L can be stably incident on the incident surface 100 of the optical probe 10. Therefore, the radiation angle γx in the X direction and the radiation angle γy in the Y direction of the optical semiconductor element 20 can be measured based on the incident intensity pattern of the optical signal L obtained by changing the relative distance between the optical probe 10 and the optical semiconductor element 20 in the X direction and the Y direction, respectively. The incident intensity pattern of the optical signal L is measured by moving the optical probe 10 in the ± direction in the X direction and the Y direction, respectively. Moreover, as described above, 1 / e can be calculated based on the incident intensity pattern. 2 Radiation angle γe and 1 / 2 radiation angle γh. Even if the incident surface 100 of the optical probe 10 is a flat surface, a method of finding the radiation angle using the incident intensity pattern of the optical signal L is also effective.

[0124] In addition, multiple Figure 1 The optical probes 10 shown are arranged to form a multi-core optical probe array. For example, n optical probes 10 are arranged in a row to form an optical probe group, and m optical probe groups are arranged to form an optical probe array in which n×m optical probes 10 are arranged in an array. By using an optical probe array composed of optical probes 10 corresponding to a plurality of optical semiconductor elements 20, a plurality of optical semiconductor elements 20 arranged in an array on a wafer 200 can be measured simultaneously. As a result, the total measurement time of the optical semiconductor elements 20 formed on the wafer 200 can be shortened.

[0125] exist Fig.17 2 shows a configuration example of a measurement system using the above-mentioned optical probe array. Fig.17The measurement system shown in the figure includes an optical probe head 15, which holds an optical probe array in which optical probes 10 are arranged in an array, and an electrical probe head 35, which holds an electrical probe array in which a plurality of electrical probes 30 are arranged. As the electrical probe 30, for example, a cantilever type, a vertical needle type, a vertical spring type, etc. are used. The optical probe 10 and the electrical probe 30 are arranged at equal intervals in the X direction. The optical probe 10 and the electrical probe 30 are arranged at equal intervals in the Y direction as in the X direction, but are not shown in the figure.

[0126] Fig.17 The measurement system shown is used to measure the characteristics of a plurality of optical semiconductor elements 20 formed on a wafer 200. The optical semiconductor elements 20 are formed in an array on the main surface of the wafer 200 mounted on a mounting table 50. For example, an optical probe 10 and an electrical probe 30 are arranged in pairs for one optical semiconductor element 20. In this way, a probe unit including the optical probe 10 and the electrical probe 30 is formed for one optical semiconductor element 20. The probe unit is arranged corresponding to the arrangement of the optical semiconductor elements 20 formed on the wafer 200. In addition, in Fig.17 2 , the number of optical probes 10 and electrical probes 30 constituting one measurement unit is shown as an example. However, the number of optical probes 10 and electrical probes 30 included in the measurement unit can be arbitrarily set according to the structure of the optical semiconductor element 20 and the measurement content.

[0127] The optical probe head 15 is moved in the Z direction by the control of the optical probe driving device 41. Thus, the distance along the Z direction between the incident surface 100 of the optical probe 10 and the optical semiconductor element 20 can be finely adjusted. In addition, the electrical probe head 35 is moved in the Z direction by the control of the electrical probe driving device 42. Thus, the distance along the Z direction between the tip of the electrical probe 30 and the optical semiconductor element 20 can be finely adjusted.

[0128] By moving the stage 50 using the stage driving device 43, the optical probe head 15 and the electrical probe head 35 can be aligned with the optical semiconductor element 20 in the X direction and the Y direction. In addition, by rotating the stage 50 about the Z direction using the stage driving device 43, the position of the optical probe 10 and the electrical probe 30 relative to the optical semiconductor element 20 can be adjusted in the rotation direction about the Z direction (hereinafter referred to as the "Z rotation direction").

[0129] The stage 50 can be fixed in position and the optical probe head 15 and the electrical probe head 35 can be moved in the directions of X, Y, and Z. That is, the relative positions of the optical probe 10 and the electrical probe 30 with respect to the optical semiconductor element 20 can be adjusted by the optical probe driving device 41 and the electrical probe driving device 42.

[0130] As mentioned above, according to Fig.17 The measurement system shown can align the positions of the optical probe 10 and the electric probe 30 with the optical semiconductor element 20. In addition, the measurement system can be configured to independently control the position of the optical probe head 15 and the position of the electric probe head 35. In addition, a method can be used to fix the optical probe head 15 and the electric probe head 35, move the mounting table 50 in the X, Y, and Z directions, and rotate it around the Z direction to control the positions of the optical probe head 15, the electric probe head 35, and the optical semiconductor element 20. In this way, various adjustment methods can be used to align the positions of the optical probe 10 and the electric probe 30 with the optical semiconductor element 20.

[0131] via Fig.17 The measurement system shown in the figure performs the transmission of electric signals and optical signals to measure the optical semiconductor element 20. That is, the electric signal output from the tester (not shown) is sent to the electric probe 30 via the connection terminal (not shown) arranged on the electric probe head 35. For example, in the case where the optical semiconductor element 20 is a VCSEL formed on a semiconductor substrate, the electric probe 30 applies an electric signal to the electric signal terminal arranged on the upper surface of the VCSEL, and the VCSEL outputs the optical signal L. The optical signal L is received by the optical probe 10.

[0132] The optical probe 10 is connected to a photoelectric conversion unit 47 having a photoelectric conversion module 45 and an electrical connection terminal 46. The optical signal L output by the optical semiconductor element 20 is transmitted to the photoelectric conversion module 45 optically connected to the optical probe 10. The photoelectric conversion module 45 converts the optical signal L into an electrical signal, and outputs the converted electrical signal to the electrical connection terminal 46. The electrical connection terminal 46 is electrically connected to a tester (not shown), and the electrical signal obtained by photoelectric conversion of the optical signal L is sent from the electrical connection terminal 46 to the tester.

[0133] The photoelectric conversion module 45 can use a type that converts the optical signal L into an electrical signal by a photodetector or the like, or a type that splits the optical signal L by a diffraction grating type device and detects wavelength variation according to the diffraction angle direction. The type of photoelectric conversion module 45 used can be distinguished according to the purpose of measurement. In addition, the optical signal L can also be branched before reaching the photoelectric conversion module 45, and multiple measurements can be performed simultaneously. By using the photoelectric conversion unit 47 to perform photoelectric conversion on the output of the optical probe 10 near the optical probe head 15, it is possible to simplify the measurement system, speed up the measurement time, and improve the reproducibility of the measurement value. In this way, the optical semiconductor element 20 can be measured using a probe card having an optical probe 10 and an optical probe head 15 for holding the optical probe 10.

[0134] use Fig.17 The measurement system shown in the figure measures the optical semiconductor element 20, for example, Fig.18Next, refer to the flowchart shown in Fig.18 An example of a method for measuring the optical semiconductor element 20 will be described.

[0135] First, in step S10, the optical probe 10 and the electric probe 30 are aligned with the optical semiconductor element 20. Then, the relative position of the electric probe 30 and the optical semiconductor element 20 is changed along the Z direction, and the tip of the electric probe 30 is connected to the electric signal terminal of the optical semiconductor element 20. In this state, an electric signal is applied to the optical semiconductor element 20 through the electric probe 30, and the optical semiconductor element 20 outputs an optical signal L.

[0136] Then, in step S20, the light intensity of the optical signal L is measured. That is, the optical probe head 15 is moved in the Z direction to arrange the optical probe 10 in such a manner as to achieve a predetermined working distance WD. Furthermore, the optical signal L received by the optical probe 10 is subjected to photoelectric conversion by the photoelectric conversion module 45, and the light output of the optical signal L is monitored. At this time, the position of the optical probe 10 is controlled so that the output of the optical signal L from the optical semiconductor element 20 is maximized. Furthermore, the optical probe 10 is fixed at a position where the light output of the optical signal L is maximized. In this state, the optical signal L from the optical probe 10 is measured. In this way, the light intensity of the optical signal L is obtained.

[0137] Next, in step S30, the incident intensity pattern is acquired by changing the relative positions of the optical probe 10 and the optical semiconductor element 20 while keeping the working distance WD constant. Then, in step S40, the radiation angle γ of the optical signal L is measured based on the incident intensity pattern.

[0138] The above-mentioned measurement is repeated until the measurement of all the optical semiconductor elements 20 formed on the wafer 200 is completed. In addition, the example of measuring the light intensity and radiation angle characteristics of the optical signal L is described above, but it is self-evident that the spectral characteristics, various temperature characteristics, etc. other than the light intensity and radiation angle of the optical signal L can also be measured. In addition, the order of measuring these characteristics is arbitrary.

[0139] By using an optical probe 10 whose curvature radius R of the incident surface 100 is set using equation (17), the optical probe 10 can stably receive the optical signal L even in the measurement using an optical probe array formed by arranging a plurality of optical probes 10. That is, by using the optical probe array, even if the relative position of the optical probe 10 and each optical semiconductor element 20 formed on the wafer 200 changes individually on the XY plane, the optical signal L of each optical semiconductor element 20 can be stably incident on the incident surface 100. Therefore, the optical probe array can be used to simultaneously measure the incident intensity patterns of each of the plurality of optical semiconductor elements 20. That is, the radiation angle γx in the X direction and the radiation angle γy in the Y direction can be simultaneously measured for the optical semiconductor elements 20 formed on the wafer 200.

[0140] In the conventional radiation angle measurement method, it is impossible to measure the radiation angle of the optical signal L for the optical semiconductor element 20 in the wafer state. The optical semiconductor element 20 must be mounted on a substrate through wiring after being chipped, and then the radiation angle must be measured using a beam analyzer, FFP measuring instrument, or the like. That is, the chipped optical semiconductor element 20 must be mounted on a substrate or modularized to measure the radiation angle of the optical signal L for each optical semiconductor element 20. Therefore, the measurement of the radiation angle is time-consuming and laborious. In addition, since the optical semiconductor element 20 is measured individually, the measurement requires time and effort, and it is difficult to measure all the optical semiconductor elements 20. In addition, when a portion of the optical semiconductor elements 20 are sampled and inspected, there is a problem that it is impossible to determine whether other optical semiconductor elements 20 are good. Therefore, in the conventional measurement method, it is impossible to achieve an improvement in the yield.

[0141] In contrast, according to Fig.17 The measurement system shown in the figure can uniformly measure the radiation angle of the optical signal L for a plurality of optical semiconductor elements 20 in a wafer state by using the optical probe 10 to form a multi-core optical probe array. Therefore, the measurement time can be reduced. In addition, all optical semiconductor elements 20 can be inspected, thereby improving the yield rate.

[0142] As described above, according to the optical probe 10 involved in the first embodiment, by adjusting the curvature radius R of the incident surface 100, the incident stable distance Ds=Se-Sr can be extended. Therefore, the relative distance between the optical probe 10 and the optical semiconductor element 20 can be changed on the XY plane under a fixed working distance WD, so that the incident intensity pattern of the optical signal L can be obtained in the X direction and the Y direction, respectively. That is, the radiation angle γx in the X direction can be calculated using the incident intensity pattern obtained in the X direction, and the radiation angle γy in the Y direction can be calculated using the incident intensity pattern obtained in the Y direction. Moreover, 1 / e in the X direction and in the Y direction can be calculated, respectively. 2Radiation angle γe and 1 / 2 radiation angle γh. Thus, for example, the radiation angle can be measured for an optical signal L whose far-field pattern is an ellipse.

[0143] In addition, in the optical probe 10, the incident stable distance Ds is large, and the incident variation caused by the tilt angle ζ can be suppressed. Therefore, when a plurality of optical semiconductor elements 20 formed on the wafer 200 are measured by a single position alignment using an optical probe array formed by arranging the optical probes 10, even if the optical probes 10 and the optical semiconductor elements 20 are positionally offset or angularly offset, the incident variation can be suppressed. In other words, the optical signal L from the optical semiconductor element 20 can be incident on each optical probe 10 in a stable state.

[0144] Furthermore, since the intensity measurement and radiation angle measurement of the optical semiconductor element 20 can be performed in the wafer state, the measurement process of the optical semiconductor element 20 can be simplified and the measurement time can be greatly shortened. At this time, the electrical probes 30 can be arranged in an array on a substrate separate from the optical probe array, or the optical probe array and the electrical probe array can be integrated into a structure. However, in the case where the optical probe array and the electrical probe array are constructed as an integral whole, the electrical probe 30 moves in the X direction, the Y direction, and the Z direction while in contact with the electrical signal terminal of the optical semiconductor element 20. Therefore, the electrical probe 30 adopts a shape, matching material, and structure with deformable strain elastic properties, so that even if the electrical probe 30 is moved in a state of contact with the electrical signal terminal, the contact state of the electrical probe 30 and the electrical signal terminal will not change, so that the electrical signal can be stably provided to the electrical signal terminal.

[0145] (Second Embodiment)

[0146] like Fig.19 As shown, the optical probe 10 according to the second embodiment has a structure in which a first region 101 and a second region 102 are connected. One end face of the first region 101 is an incident face 100, and the other end face of the first region 101 is bonded to the end face of the second region 102. The central axes C10 of the first region 101 and the second region 102 coincide with each other.

[0147] The first region 101 having the incident surface 100 has the same structure as the optical probe 10 described in the first embodiment. That is, the incident surface 100 of the first region 101 is a curved surface whose curvature radius R and central half angle ω are set in a manner that satisfies the relationship between equations (17) and (11). For example, a GI type optical fiber is used in the first region 101.

[0148] For example, it is manufactured as follows Fig.19The optical probe 10 shown in the figure. First, the end faces of the large-diameter GI type optical fiber as the first region 101 and the standard-diameter GI type optical fiber as the second region 102 are fusion-connected to each other. In addition, the large-diameter GI type optical fiber is cut into a predetermined length of the first region 101. Thereafter, processing is performed so that the end face of the large-diameter GI type optical fiber has a curvature radius R.

[0149] The length T of the first region 101 may be set so that the optical signal L is focused at the boundary between the first region 101 and the second region 102. When a GI optical fiber is used, T=2π×P / A 1 / 2 Here, P is the pitch length, and one pitch is one period. 1 / 2 is the refractive index distribution constant, which is a constant determined by the relative refractive index difference Δ obtained based on the refractive index of the central axis C10 and the cladding portion 112, and the core radius Cr. Assuming that P = 0.27, T = 0.54π / A 1 / 2 Therefore, in order to set the vicinity of the boundary between the first region 101 and the second region 102 as the focal position of the optical signal L, WD=0.46π×n(c) / A 1 / 2 When , the total distance from the optical semiconductor element 20 to the boundary between the first region 101 and the second region 102 is 0.5P of the half period. Thus, the optical signal L is focused at a position near the boundary between the first region 101 and the second region 102, and the optical signal L is incident on the core of the second region 102 fused to the first region 101.

[0150] In addition, if Fig.19 As shown, the core radius Cr1 and the probe radius Dr1 of the first region 101 may be different from the core radius Cr2 and the probe radius Dr2 of the second region 102. Fig.19 In the optical probe 10 shown, the thickness of the cladding portion 112 of the first region 101 and the second region 102 is equal, and the diameter of the second region 102 is smaller than the diameter of the first region 101. That is, the core radius Cr of the first region 101 is larger than the core radius Cr2 of the second region 102. For example, the optical probe 10 can be constructed by using a large-diameter GI type optical fiber in the first region 101 and a standard-diameter GI type optical fiber in the second region 102. By using a structure in which a standard-diameter GI type optical fiber is used in the second region 102, the end of the optical probe 10 can be connected to an optical circuit component, a coupler, an optical switch, etc. using an optical fiber with a standard core diameter to realize a low-loss multi-input optical circuit.

[0151] (Third Embodiment)

[0152] exist Fig. 20In the optical probe 10 according to the third embodiment shown, the additive for increasing the refractive index of the core 111 is diffused within a range of a fixed length U along the central axis C10 from the incident surface 100 . Fig. 20 The optical probe 10 shown has a first region 101 extending from an incident surface 100 to a length U, and a second region 102 connected to the first region 101. For example, the first region 101 using an optical fiber having a core diameter Cd of 50 μm or 62.5 μm is heated to about 1200 to 1400° C. Thus, a substance such as germanium (Ge) that increases the refractive index and is present in the core 111 of the second region 102 is diffused into the first region 101.

[0153] By adding a substance for increasing the refractive index to the first region 101, the propagation area of ​​the optical signal L in the radial direction is increased. As a result, the core diameter Cd of the incident surface 100 is expanded to about 80 μm to 100 μm. As a result, the incident area of ​​the optical signal L at the incident surface 100 is expanded, and the tolerance characteristics can be improved. In this case, by increasing the core diameter Cd, the refractive index n(c) of the core 111 at the central axis C10 is reduced. Therefore, the numerical aperture NA is reduced, and the value of NA can be adjusted by the curvature radius R of the incident surface 100.

[0154] By configuring the optical probe 10 using a common optical fiber as described above, it becomes easy to connect optical circuit system elements such as a branch circuit and an optical switch to the optical probe 10. Therefore, the optical probe 10 can be easily handled in the optical measurement system.

[0155] (Other Embodiments)

[0156] As described above, the present invention is described through the embodiments, but it should not be understood that the description and drawings constituting a part of the present disclosure limit the present invention. Various alternative embodiments, examples, and application techniques should be clear to those skilled in the art based on the present disclosure.

[0157] For example, the optical probe 10 using a profiled-refractive-index optical fiber has been described above, but the optical probe 10 may be configured using a step-refractive-index optical fiber.

[0158] In addition, as an optical waveguide structure provided at equal intervals, a structure in which the incident surface 100 is shaped into a shape of a curvature radius R, or a structure in which a lens having the same shape and function is mounted can also be equivalently realized.

[0159] As described above, the present invention naturally includes various embodiments and the like not described here.

[0160] Description of Reference Numerals

[0161] 10: optical probe; 15: optical probe head; 20: optical semiconductor element; 30: electric probe; 35: electric probe head; 41: optical probe driving device; 42: electric probe driving device; 43: stage driving device; 50: stage; 100: incident surface; 111: core; 112: cladding; 200: wafer.

Claims

1. An optical probe, characterized in that: The optical probe is composed of a core and a cladding portion arranged on the outer periphery of the core, and the incident surface of the optical probe on which the optical signal from the optical semiconductor element is incident is a curved surface with a curvature radius R. Using the radiation angle γ of the optical signal, the effective incident radius Se at the incident surface of the optical signal propagating in the core without passing through the cladding portion, the refractive index n(r) of the core at the incident point of the incident surface of the optical signal, and the refraction angle β at the incident point, the curvature radius R and the central half angle ω at the incident point satisfy the following relationship: R=Se / sin(ω), ω=±sin -1 ({K2 2 / (K1 2 +K2 2 )} 1 / 2 ), in, K1=n(r)×cos(β)-cos(γ / 2) K2=n(r)×sin(β)-sin(γ / 2).

2. The optical probe according to claim 1, characterized in that Using the radiation half angle α of the optical signal when the effective incident radius Se is equal to the core radius Cr of the optical probe and the distance between the optical semiconductor element and the incident surface is the maximum achievable working distance, the curvature radius R satisfies the following relationship: R ≥ Cr / sin(ω), in, K1=n(r)×cos(β)-cos(α) K2=n(r)×sin(β)-sin(α) α=sin -1 {n(r)×sin(β+ω)}-ω.

3. The optical probe according to claim 2, characterized in that The maximum working distance WDm is Cr / tan(α), The working distance WD satisfies the relationship WD≤WDm.

4. The optical probe according to any one of claims 1 to 3, characterized in that The optical probe has a structure in which a first region and a second region are connected, the first region is connected to the incident surface, and the diameter of the core of the second region is smaller than the diameter of the core of the first region.

5. The optical probe according to any one of claims 1 to 3, characterized in that The additive for increasing the refractive index of the core is diffused within a range of a fixed length along the central axis from the incident surface.

6. A probe card, characterized in that: have: The optical probe according to any one of claims 1 to 5; and An optical probe head holds the optical probe.

7. A measurement system, characterized in that have: The optical probe according to any one of claims 1 to 5; an optical probe head holding the optical probe; an optical probe driving device, which controls the position of the optical probe head; an electric probe head that holds an electric probe that sends an electric signal to the optical semiconductor element; as well as an electric probe driving device, which controls the position of the electric probe head, Here, one probe unit including the optical probe and the electrical probe is configured for one optical semiconductor element.

8. The measuring system according to claim 7, characterized in that The optical probe array is formed by arranging the optical probes in an array shape. The optical probe head holds the optical probe array.

9. A determination method, characterized in that: A measurement method using the optical probe according to any one of claims 1 to 5, in which: The optical semiconductor element is moved relative to the optical probe while the working distance between the optical semiconductor element and the incident surface is fixed, and an incident intensity pattern indicating the relationship between the incident intensity of the optical signal and the moving distance is obtained. The incident intensity pattern is used to calculate a radiation angle of the optical signal.

10. The measuring method according to claim 9, characterized in that Using a working distance WD and making the incident intensity 1 / e of the peak 2 The moving distance De is calculated using the following formula to make the incident intensity 1 / e of the peak value 2 1 / e 2 Radiation angle γe: γe=2×tan -1 (De / (4×WD))。 11. The measuring method according to claim 9, characterized in that Using the working distance WD and the moving distance Dh that makes the incident intensity 1 / 2 of the peak value, the 1 / 2 radiation angle γh that makes the incident intensity 1 / 2 of the peak value is calculated using the following formula: γh=2×tan -1 (Dh / (4×WD)).

12. The measuring method according to claim 9, characterized in that Using the incident movement range Dw in which at least a portion of the optical signal is incident on the core of the optical probe and the incident stable range Dp as the flat portion of the incident intensity pattern, the effective incident radius Se and the incident radius Sr of the optical signal satisfy the following relationship: Se=1 / 4×(Dw+Dp), Sr = 1 / 4 × (Dw-Dp), The incident intensity is set to 1 / e of the peak value. 2 The moving distance De that makes the incident intensity 1 / 2 of the peak value is calculated using the following relationship: 2 1 / e 2 The radiation angle γe and the 1 / 2 radiation angle γh that makes the incident intensity 1 / 2 of the peak value: γe6×De / Dh×tan -1 (Sr / WD) γh=2×tan -1 (Sr / WD).

13. The measuring method according to claim 9, characterized in that The radiation angle γ when the optical probe is used with respect to the optical semiconductor element serving as a reference is measured by a measuring instrument. The assumed working distance cWD is calculated based on the measured value of the measuring device. The radiation angle of the optical signal is calculated using the assumed working distance and the moving distance.

14. The measuring method according to claim 9, characterized in that The optical semiconductor element is moved in the X direction and the Y direction respectively on an XY plane perpendicular to the extending direction of the optical axis of the optical signal, Using the incident intensity pattern acquired in the X direction, the radiation angle in the X direction is calculated, The radiation angle in the Y direction is calculated using the incident intensity pattern acquired in the Y direction.

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