JP2014059154A - Inspection method of optical element and inspection device of optical element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inspect irregularity in optical characteristics of an optical element or a defect therein as to the optical element having a polarization filter different in a polarization direction two-dimensionally arranged at a predetermined area ratio at high speed, and to evaluate a quality determination of the optical element with high accuracy.SOLUTION: The inspection method of an optical element having a first polarization area transmitting a first polarization component of incident light and a second polarization area transmitting a second polarization component of the incident light two-dimensionally arranged at a predetermined area ratio is configured to: calculate transmittance of the first polarization component passing through the optical element (S9); calculate transmittance of the second polarization component passing through the optical element (S15); calculate a transmittance ratio from the transmittance of the first polarization component and the transmittance of the second polarization component (S17); and, when an absolute value of a value deducted by a predetermined reference value in accordance with the area ratio from the calculated transmittance ratio falls within a predetermined range, determine that the optical element is non-defective (S19).

Description

  The present invention relates to an optical element inspection method and an optical element inspection apparatus, and in particular, to determine whether optical characteristics of an optical element in which polarization regions having different polarization directions are two-dimensionally arranged at a predetermined area ratio are high speed and high accuracy. The present invention relates to an optical element inspection method and an optical element inspection apparatus.

With the progress of semiconductor microfabrication technology, it has become possible to produce polarizing filters having different optical characteristics in unit regions each having a side of about several μm, and their use is progressing.
For example, in a liquid crystal panel or the like, a color filter array in which RGB filters are respectively produced in unit areas each having a side of about several μm by using photolithography in which a color resist mixed with a dye is applied to a substrate and then exposed and developed. Has been put to practical use.
In addition, a polarizing filter (hereinafter referred to as a “mixed filter”) in which a sub-wavelength polarizing element, a wire grid polarizer, or a photonic crystal element having a microstructure with a length equal to or shorter than an incident wavelength is manufactured in a unit region having a side of about several μm. ") Has been put to practical use. In the mixed filter, regions (filters) having different polarization characteristics are arranged at a predetermined area ratio.
Incidentally, the inspection of the optical characteristics of the polarizing filter is generally performed by irradiating the optical element to be inspected with inspection light and measuring the reflection intensity and transmission intensity of the inspection light (see, for example, Patent Document 1).

However, it is difficult to inspect the characteristics of the mixed filter with the conventional optical element inspection method described in Patent Document 1. That is, since the unit area of the mixed filter is about several μm on a side, when the inspection light is irradiated from a general optical characteristic evaluation apparatus, the size of the unit area is larger than the size of the area irradiated with the inspection light. Therefore, there is a problem that characteristics such as transmittance and reflectance cannot be measured for each unit region of the mixed filter.
Conventionally, as an alternative, a monitor pattern (or a monitor sample) having a size that can be measured by a general optical property evaluation apparatus, in other words, a size sufficiently larger than the size of the area irradiated with the inspection light has been used. . In other words, an optical filter is manufactured under the same conditions as the filter formed in each unit area of the mixed filter, the optical characteristics of the monitor pattern are evaluated, and the evaluation result is applied to the mixed filter, whereby the mixed filter The optical properties of were evaluated.

However, mixed filters using fine structures such as photonic crystals and wire grid polarizers may have different dimensions after processing due to the difference in the arrangement of fine structures in the mixed filter and the monitor pattern. The optical characteristics on the mixed filter may not match the optical characteristics of the monitor pattern.
In addition, when shipping mixed filters as products, it is necessary to inspect optical characteristics unevenness and defects, but these cannot be replaced by monitor patterns, and actual mixed filters must be inspected directly. There is. However, as described above, a general optical evaluation apparatus or inspection apparatus has a low resolution of the evaluation area, that is, the area irradiated with inspection light is much larger than each unit area of the mixed filter. There was a problem that only the entire optical characteristics could be evaluated.

Therefore, there is provided an optical element inspection method and inspection apparatus capable of inspecting unevenness and defects of optical characteristics of a mixed filter at high speed without using a monitor pattern at a high speed, and evaluating the pass / fail judgment of an optical element with high accuracy. It was anxious.
The present invention has been made in view of the above-described circumstances, and inspects optical characteristics unevenness and defects of an optical element in which polarizing filters having different polarization directions are two-dimensionally arranged at a predetermined area ratio, and the optical element It is an object of the present invention to provide an optical element inspection method and an optical element inspection apparatus capable of accurately evaluating the quality determination.

  In order to solve the above problem, the invention according to claim 1 is a first polarization region that transmits the first polarization component of the incident light, and a first polarization region that transmits the second polarization component of the incident light. An inspection method for an optical element in which two polarization regions are two-dimensionally arranged at a predetermined area ratio, the inspection light having an irradiation region sufficiently larger than the first polarization region and the second polarization region A first detection step of irradiating the optical element to detect the intensity of the first polarization component of the inspection light transmitted through the optical element; irradiating the optical element with the inspection light; From the second detection step of detecting the intensity of the second polarization component of the transmitted inspection light and the intensity of the first polarization component of the inspection light detected in the first detection step, the first A first transmittance calculating step for calculating the transmittance of the polarization component of A second transmittance calculating step of calculating a transmittance of the second polarization component from an intensity of the second polarization component of the inspection light detected in the second detection step; and the first transmittance. A transmittance ratio for calculating a transmittance ratio from the transmittance of the first polarization component calculated in the calculation step and the transmittance of the second polarization component calculated in the second transmittance calculation step. When the absolute value of a value obtained by subtracting a predetermined reference value according to the area ratio from the transmittance ratio calculated in the transmittance step and the transmittance ratio calculating step is within a predetermined range, the optical element is A pass / fail judgment step for judging that the product is non-defective.

In the present invention, the first polarization component detected in the first detection step is substantially equal to the first polarization component transmitted through the first polarization region. Accordingly, the transmittance of the first polarization component transmitted through the optical element is substantially equal to the transmittance of the first polarization component transmitted through the first polarization region.
Further, the second polarization component detected in the second detection step is substantially equal to the second polarization component transmitted through the second polarization region. Accordingly, the transmittance of the second polarization component transmitted through the optical element is substantially equal to the transmittance of the second polarization component transmitted through the second polarization region.
According to the present invention, the transmittance ratio, which is the ratio of the transmittance of the first polarization component and the transmittance of the second polarization component obtained in the detection step, is defined as the area of the first polarization region and the second polarization region. Since the optical element is evaluated by comparing with a reference value according to the ratio, it is possible to inspect unevenness and defects of optical characteristics for each irradiation region of the inspection light, and to determine the quality of the optical element with high accuracy. it can.

(A)-(c) is a schematic diagram of the optical element by which the wire grid polarizer is arrange | positioned. It is a schematic block diagram of an inspection apparatus. It is the flowchart which showed the inspection method of the optical element performed with an inspection apparatus. 1 is a schematic diagram of an optical element that is an inspection target in Example 1. FIG. It is a schematic diagram of the optical element made into the test object in Examples 2 and 3. FIG. FIG. 6 is a schematic diagram of an optical element that is an inspection target in Example 4;

  Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings. However, the components, types, combinations, shapes, relative arrangements, and the like described in this embodiment are merely illustrative examples and not intended to limit the scope of the present invention only unless otherwise specified. .

The present invention relates to an optical element inspection method for determining the quality of an optical element (mixed filter) in which polarizing filters having different polarization characteristics are two-dimensionally arranged at a predetermined area ratio, and further inspecting a defect of the mixed filter. The optical element inspection apparatus has the following features.
In short, the present invention grasps the transmittance (reference value) of the inspection light in the reference portion that is determined as “good” in advance, and transmits the transmittance of the reference portion and the inspection light transmitted through the inspection target portion (measurement). Value) to determine whether or not the portion to be inspected is a “non-defective product”. In particular, since a value corresponding to the area ratio of the two types of polarizing filters constituting the mixed filter is used as the reference value, conventionally, the optical characteristics of the mixed filter that could not be directly measured have been measured. It is possible to inspect irregularities and defects at high speed and evaluate the quality of optical elements with high accuracy.

The features of the present invention described above will be described in detail with reference to the following drawings.
[Non-defective product judgment principle]
First, the principle of the present invention will be described with reference to FIG. 1A to 1C are schematic views of an optical element in which a wire grid polarizer is arranged.
A wire grid polarizer is an optical element in which fine metal lines (metal wires) are periodically arranged in parallel in one direction. It has an optical characteristic of reflecting light having an electric field component oscillating in a direction parallel to the extending direction of the metal line (line direction) and transmitting the electric field component oscillating in a direction perpendicular to the extending direction of the metal line. Hereinafter, TE polarized light (S polarized light) of a wire grid polarizer is polarized light having an electric field component that vibrates in parallel with a metal line forming the wire grid, and TM polarized light (P polarized light) is a wire. It is defined as polarized light having an electric field component that vibrates perpendicularly to the metal lines forming the grid.

First, as shown in FIGS. 1A and 1B, a wire grid polarizer composed of a single polarization region is considered.
As shown in FIG. 1A, in a wire grid (X-direction wire grid) in which a metal line structure in which fine metal lines are arranged in parallel in the X direction with respect to the entire region of the wire grid polarizer is formed. The TM polarized light (P polarized light) transmittance is defined as Tp1, and the TE polarized light (S polarized light) transmittance is defined as Ts1. Similarly, as shown in FIG. 1B, a wire grid (Y-direction wire grid) in which a metal line structure is formed in which fine metal lines are arranged in parallel in the Y direction with respect to the entire region of the wire grid polarizer. The TM polarized light (P polarized light) transmittance is defined as Tp2 and the TE polarized light (S polarized light) transmittance is defined as Ts2.
The polarization selection performance of a wire grid polarizer is expressed by its extinction ratio (TM transmittance) / (TE transmittance), Tp1 / Ts1, or Tp2 / Ts2, and the higher these values, the better the polarization selection performance, Indicates fewer wire grid defects. Generally, when these values are 100 or more, it is determined that the polarization selection performance is good.

  Next, consider an optical element in which a plurality of regions having different polarization characteristics are mixed as shown in FIG. The illustrated mixed filter 10 has a plurality of fine unit regions 11 (11x, 11y) divided into micron-order regions, and each unit region 11 has an X-direction wire grid 11x or a Y-direction. A wire grid 11y is formed. That is, in the mixed filter 10, an X-direction wire grid 11x (first polarization region) that transmits light (0 ° polarization: first polarization component) having an electric field component oscillating in the X direction out of the incident light. And a Y-direction wire grid 11y (second polarization region) that transmits light having an electric field component oscillating in the Y direction (90 ° polarization: second deflection component) are two-dimensionally arranged at a predetermined area ratio. ing. The mixed filter 10 includes two types of wire grids in which the directions of the metal lines are orthogonal to each other.

Here, the area ratio of the X-direction wire grid 11x formation region to the total area of the mixed filter 10 is A, and the area ratio of the Y-direction wire grid 11y formation region to the total area of the mixed filter 10 is B (= 1−A). ). A and B are design values for producing the mixed filter 10 and are known values.
Further, when the quality determination of the mixed filter 10 is performed, the following two measurements are performed.
[1] The transmittance T0 of 0 ° polarized light transmitted through the mixed filter is measured.
[2] The transmittance T90 of 90 ° polarized light that passes through the mixed filter is measured.
Note that the direction of polarized light for measuring the transmittance is aligned with the direction of the transmission axis of the wire grid constituting the mixed filter 10. That is, 0 ° polarization is light having an electric field component parallel to the transmission axis of the X-direction wire grid 11x, and 90 ° polarization is light having an electric field component parallel to the transmission axis of the Y-direction wire grid 11y.
From the measured transmittances T0 and T90 and the area ratios A and B, the quality of the mixed filter 10 is determined. Hereinafter, a mechanism capable of determining pass / fail and a procedure for determining pass / fail are shown below.

If the line dimensions of the X-direction wire grid and the Y-direction wire grid in the mixed filter are the production results as designed, and there are no defects, the transmittances T0 and T90 are expressed by the equations (1) and (2). It is represented by
T0 = A × Tp1 + B × Ts2
= A * Tp1 * {(1+ (B / A) * (Ts2 / Tp1)} (1)
T90 = A × Ts1 + B × Tp2
= B * Tp2 * {(A / B) * (Ts1 / Tp2) +1} (2)
Here, when the extinction ratio [TM transmittance / TE transmittance] of the wire grid polarizer is 100 or more, Ts1 / Tp1 <1/100 and Ts2 / Tp2 <1/100. When the X-direction wire grid and the Y-direction wire grid have the same manufacturing accuracy, Tp1≈Tp2 and Ts1≈Ts2. From these facts, it can be approximated as Ts2 / Tp1 <1/100 and Ts1 / Tp2 <1/100.

Furthermore, when the ratio of the area ratio A and the area ratio B is about 1: 5 (or 5: 1) at the maximum, 0.2 <A / B <5 or 0.2 <B / A <5 Become. Therefore, (B / A) × (Ts2 / Tp1) in equation (1) and (A / B) × (Ts1 / Tp2) in equation (2) are sufficiently smaller than 1 and should be ignored. And each formula is
T0≈A × Tp1 (1 ′)
T90≈B × Tp2 (2 ′)
Can be approximated. Therefore, the ratio (transmittance ratio) between T0 and T90 is T0 / T90 = (A / B) × (Tp1 / Tp2) (3)
It becomes.
Here, in order to establish an approximation from Equations (1) and (2) to Equation (3), (B / A) × (Ts2 / Tp1) in Equation (1) and ( A / B) × (Ts1 / Tp2) needs to be sufficiently smaller than 1. Therefore, when the ratio of A and B is large (for example, larger than 5), the extinction ratio of the polarizer constituting the mixed filter is required to be high (for example, higher than 100). If the extinction ratio of each wire grid constituting the mixed filter is 1000 or more, the ratio of A and B can be allowed up to about 10.

Since the transmittances T0 and T90 are values obtained by measurement, the transmittance ratio T0 / T90 can be calculated from the measured values. Further, since the area ratio A / B is clear from the design value of the mixed filter, Tp1 / Tp2 can be approximately calculated from the equation (3). Hereinafter, Tp1 / Tp2 is referred to as “TM transmittance ratio”.
The transmittance ratio T0 / T90 is a value that changes according to the area ratio A / B of the X-direction wire grid 11x and the Y-direction wire grid 11y included in the mixed filter 10. Further, the TM transmittance ratio Tp1 / Tp2 is a value obtained by dividing the transmittance ratio T0 / T90 by the area ratio A / B, so that the transmittance ratio T0 / T90 and the TM transmittance ratio Tp1 / Tp2 are obtained. Are values corresponding to the area ratio of the X-direction wire grid 11x and the Y-direction wire grid 11y included in the mixed filter 10.
From this TM transmittance ratio, the tendency of the polarization characteristics of the X-direction wire grid and the Y-direction wire grid can be known as described below.

Here, the metal line pattern is usually produced by etching using a resist pattern. For example, after depositing (depositing) an aluminum thin film on a wafer, resist patterning is performed, and a concavo-convex structure of a wire grid is formed by a technique such as metal etching, thereby producing a metal line pattern.
In the case of a wire grid, the optical characteristics differ depending on the pitch, height (length of the metal line in the thickness direction of the wire grid), and width of the metal line, and TM transmittance (Tp1, Tp2) or TM transmittance ratio (Tp1) / Tp2).

If the wire grid constituting the mixed filter is within the same wafer, the pitch and line height of the metal lines are substantially constant, and the line width tends to vary. In particular, when a wire grid is produced by etching, the line width error tends to be larger than the metal line pitch or height error.
That is, in the mixed filter, the height of the metal line is determined at the time of forming the metal film, so that the entire area of the mixed filter is almost constant (uniform), and the X-direction wire grid and the Y-direction wire grid There is no big difference between them. Further, the height of the resist remaining after the etching does not greatly affect the optical characteristics of the wire grid element.
Furthermore, if the pitch of the metal lines is within the same wafer, there is a tendency that the pitch of the metal lines is substantially constant, similar to the height of the metal lines.

Therefore, the factor that affects the TM transmittance and the TM transmittance ratio is the difference in line width between the X direction and the Y direction. For example, when a wire grid is manufactured by etching, the difference in the width of the resist pattern in the X direction and the Y direction appears as the difference in line width as it is.
Whether or not the line widths in the X direction and the Y direction are different can be determined by the value of Tp1 / Tp2. For example, when Tp1 / Tp2> 1, the line width in the X direction is smaller than that in the Y direction. In the case of Tp1 / Tp2≈1, the line width in the X direction and the line width in the Y direction are almost the same, which is a preferable state. When Tp1 / Tp2 <1, the line width in the X direction is larger than that in the Y direction.

In this way, by using the TM transmittance ratio obtained from the transmittances T0 and T90 of the mixed filter and the area ratio A / B, it is possible to know whether or not there is a difference in the line widths in two orthogonal directions. it can. Therefore, the quality of the wire grid production result can be determined.
In the actual pass / fail judgment, the pass / fail ratio may be determined after obtaining the TM transmissivity ratio by dividing the transmissivity ratio T0 / T90 by the area ratio A / B. It may be used to make a pass / fail judgment.

Here, in the non-defective product determination, it is basically necessary to set a reference value that can be determined as a good product in advance, and to compare this reference value with the value (measured value) of the inspection target portion (measurement point) of the mixed filter 10. is there. For example, the boundary between the X-direction wire grid and the Y-direction wire grid does not function as a wire grid. For this reason, if light is incident on the boundary between the X-direction wire grid and the Y-direction wire grid, the transmittance tends to decrease, so that comparison with the theoretical value cannot be performed.
For example, when quality determination is performed based on the transmittance ratio T0 / T90, the portion of the mixed filter 10 that has been determined to be non-defective in advance is used as a reference point, and the transmittance ratio T0 / T90 at this reference point is used as a reference value. Set. The quality is determined by comparing this reference value with the transmittance ratio T0 / T90 (measured value) at the measurement point.

  The reference point may be a measurement point at which fine measurement is performed in advance with respect to the line width, the presence / absence of a defect, etc. by observation with an electron beam microscope. Alternatively, instead of the reference point, a reference value reflecting a tendency regarding the line width and pitch of the mixed filter may be set with reference to a value obtained by simulation or the like. When the difference between the measured value and the reference value is within the predetermined allowable value, the measurement point portion of the mixed filter that is the inspection target is determined as non-defective, and when it is not within the allowable value, the mixed type that is the inspection target The measurement point portion of the filter is determined to be defective. In this way, the quality comparison of the mixed filter to be inspected can be performed by comparing the data of the reference value and the measured value.

Further, from the transmittances T0 and T90 obtained by the measurement, it can be determined whether or not the “black defect” or “white defect” of the mixed filter exists.
A “black defect” is a defect in which light is blocked for some reason, and occurs, for example, when metal lines are connected to each other, or when a foreign object exists on the metal lines. In this case, both the TM transmittance and the TE transmittance are small. A “white defect” is a defect that allows light to pass through for some reason, and occurs, for example, when there is no metal line or when the metal is oxidized. In this case, both the TM transmittance and the TE transmittance are increased.
A black defect or a white defect is determined as follows. First, the transmittances T0 and T90 in the portion (reference point) of the mixed filter 10 that has been determined to be non-defective in advance are measured and used as reference values. The transmittances T0 and T90 (measured values) are also measured for the portion (measurement point) of the mixed filter 10 to be inspected. The quality is determined by comparing the measured values of the transmittances T0 and T90 with the reference values.

For example, if the transmittances T0 and T90 at the measurement point are too small compared to the transmittances T0 and T90 at the reference point, it can be determined that both the TM transmittance and the TE transmittance are too low compared to the reference point. It can be determined that a black defect may exist. Conversely, if the transmittances T0 and T90 at the measurement point are too large compared to the transmittances T0 and T90 at the reference point, it can be determined that both the TM transmittance and the TE transmittance are too high compared to the reference point. It can be determined that a white defect may exist.
If the transmittance T0 of the mixed filter to be inspected is significantly different from the transmittance T0 of the reference point, it can be determined that there is a problem (white defect or black defect) in the X-direction wire grid. If the transmittance T90 of the mixed filter is a large difference from the transmittance T90 of the reference point, it can be determined that there is a problem (white defect or black defect) in the Y-direction wire grid.
In the above method, it can be determined that a black defect or a white defect exists, particularly when the size of the defect is relatively large on the order of micrometers.
In the non-defective product determination using the TM transmittance ratio and the transmittances T0 and T90, by changing the measurement point of the mixed filter to be inspected, there is a difference in the line width in the mixed filter. A certain place or a place where a defect exists can be specified.

[Inspection equipment]
An inspection apparatus for inspecting a mixed filter based on the good product determination principle will be described with reference to FIG. FIG. 2 is a schematic configuration diagram of the inspection apparatus.
The inspection apparatus 100 generally includes an optical system 110 and a processing apparatus 130.
The optical system 110 includes a light source 111 of inspection light that irradiates the measurement target S (mixed filter), a beam expander 113 (light intensity averaging means) that makes the light intensity of the inspection light emitted from the light source 111 uniform. , A pinhole 115 that irradiates the measuring object S in a spot shape with the inspection light that has passed through the beam expander 113, an XY stage 117 that supports the measuring object S so as to be movable, and the XY stage 117 in the X-axis and Y-axis directions. A stage driving unit 119 (stage driving means) that is independently driven, an analyzer 121 (inspection polarizer) that transmits a predetermined polarization component of the inspection light transmitted through the measurement object S, and an analyzer 121. An analyzer rotating device 123 that supports the angle of the polarization axis so as to be adjustable, a rotating device driving unit 125 (rotation driving means) that rotationally drives the analyzer rotating device 123, and Detector 127 for detecting the test light transmitted through the polarizer 121 (the detection means), and a.

As the light source 111, it is desirable to use a laser or an LED. Since both the laser and the LED have good directivity, the measurement accuracy can be increased.
Further, the use of a light source having a single wavelength such as a laser can irradiate light having a high intensity, and an effect that the transmittance can be easily evaluated can be obtained. When a laser is used, the inspection may be performed by selecting a specific wavelength such as a wavelength of 660 nm (red), a wavelength of 532 nm (green), or a wavelength of 780 nm (near infrared). It is possible to perform an evaluation focusing on optical characteristics at a specific wavelength of the mixed filter.
The inspection light emitted from the light source 111 is light such that the light intensity detected by the detector 127 is substantially the same when the transmission axis of the analyzer 121 is 0 ° and 90 °. In other words, it is preferably non-polarized light. When a semiconductor laser is used as the light source 111, the emitted light tends to have a high light intensity in a direction perpendicular to the light emitting layer, and thus there is a problem that the light intensity is not constant depending on the incident angle. Therefore, when a semiconductor laser is used as the light source 111, the inspection light is incident on the surface of the measuring object S and the analyzer 121 with an inclination of about 45 ° so that the light intensity becomes uniform. Is preferred. Note that when a non-polarized white light source, a laser, or an LED is used as the light source 111, the above matters do not matter.

The beam expander 113 is disposed between the light source 111 and the measurement target S. The beam expander 113 equalizes the light intensity of the inspection light from the light source 111 within the irradiation range so that the inspection light with a uniform intensity is irradiated onto the measurement point of the measurement target S. adjust. By making the light intensity uniform by the beam expander 113, the measurement accuracy of the transmittance can be improved.
The pinhole 115 reduces the diameter of the inspection light to a predetermined dimension. The diameter of the spot light formed by the pinhole 115 is set to be sufficiently larger than the area where each wire grid of the mixed filter that is the measurement target S is formed. Therefore, since a sufficient number of regions are included in the spot irradiation range, the area ratio between the X-direction wire grid and the Y-direction wire grid included in the spot irradiation range is a mixed filter as the measurement target S. The area ratio of the X-direction wire grid and the Y-direction wire grid is substantially equal.

The XY stage 117 moves the measurement target S so that the inspection light is irradiated to a desired measurement point of the measurement target S. The stage drive unit 119 that drives the XY stage 117 is driven and controlled by a control unit 131 in the processing apparatus 130 described later.
The analyzer 121 is a polarization filter that transmits a predetermined polarization component of the inspection light. The angle of the transmission axis of the analyzer 121 is adjusted by the analyzer rotating device 123 so as to transmit 0 ° polarized light (first polarized component) or 90 ° polarized light (second polarized component). The rotating device driving unit 125 that rotates the analyzer rotating device 123 is driven and controlled by a control unit 131 in the processing device 130 described later.
The detector 127 (first detection means, second detection means) is a well-known light detection device having a photodiode. The detector 127 detects the intensity of the inspection light transmitted through the analyzer 121 and outputs an analog light intensity signal to the control unit 131 in the processing device 130 at the subsequent stage.

The processing device 130 includes a control unit 131 that executes various arithmetic processes, a storage unit 133 that stores a calculation program and various data necessary for determination of pass / fail of a measurement target, and a storage unit that displays determination results, setting contents, and the like. 135 and an input unit including a keyboard 137 and a mouse 139 for inputting setting contents.
The control unit 131 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like.
The ROM stores a startup program for the processing device 130 and the like. In the RAM, programs stored in the ROM or the storage unit 133 are booted, and when the programs are started, the RAM becomes a work area by the CPU of these programs. The CPU boots programs in the ROM and the storage unit 133 to the RAM, and executes each program while using the RAM as a work memory.
The storage unit 133 includes an HDD (Hard Disk Drive) and the like. The storage unit 133 stores a control program for controlling the stage driving unit 119 and the rotating device driving unit 125, a program related to calculation of transmittance and transmittance ratio, a measurement result of each measurement point of the measurement target S, and the like. Remembered.
The keyboard 137 and the mouse 139 are means for inputting tolerance values for determining the quality of the measurement target, the coordinate axes of the measurement points of the measurement target, and the like. The input tolerance value is stored in the RAM.

In the inspection apparatus 100 described above, the analyzer 121 is disposed between the measurement target S and the detector 127. However, instead of the analyzer 121, a polarizer (inspection polarizer) may be arranged at an arbitrary position between the light source 111 and the measurement target S. The polarizer referred to here is a polarizing filter that transmits a predetermined polarization component of the inspection light.
Also in this case, like the above-described analyzer 121, the polarizer is supported by a polarizer rotating device that supports the angle of the polarization axis so as to be adjustable. Then, by rotating and driving the polarizer rotating device by the rotating device driving unit, the polarization axis of the polarizer is transmitted so that the 0 ° polarized light (first polarized component) or the 90 ° polarized light (second polarized component) is transmitted. Adjust. The operation of the rotating device driving unit is controlled by the control unit 131.
Further, both the analyzer 121 and the polarizer may be arranged. In this case, when measuring the transmittance T0 and the transmittance T90, it is necessary to match the angles of the polarization axes of the analyzer and the polarizer. Therefore, when measuring the transmittance T0, the control unit 131 rotates the rotation device driving unit 125 of the analyzer rotating device 123 and the polarizer rotating device so that both the analyzer and the polarizer transmit 0 ° polarized light. Controls both of the device drive units. Further, when measuring the transmittance T90, the control unit 131 rotates the rotating device driving unit 125 of the analyzer rotating device 123 and the polarizer rotating device so that both the analyzer and the polarizer transmit 90 ° polarized light. Controls both of the device drive units.

[Inspection procedure]
The procedure of the optical element inspection method will be described.
The outline of the procedure of the mixed filter inspection method based on the above-mentioned non-defective product determination principle is as follows.
[Procedure 1] Measurement of transmittance (T0, T90) of reference sample (reference point) and calculation of transmittance ratio T0 / T90 [Procedure 2] Grasping defects of reference sample (electron micrographs, defects such as foreign matter) Observation)
[Procedure 3] Measurement of transmittance (T0, T90) of sample to be inspected (measurement point) and calculation of transmittance ratio T0 / T90 [Procedure 4] Transmittance between sample to be inspected and reference sample (T0, T90) , T0 / T90 comparison [Procedure 5] Judging non-defective samples

FIG. 3 is a flowchart showing an optical element inspection method performed by the inspection apparatus. This flowchart shows the procedure 3-5. Note that the procedure 1 is also performed by the inspection apparatus. In this case, the operation is performed without executing steps S19, S23, and S25 in the flowchart of FIG.
First, the storage unit 133 of the inspection apparatus 100 stores intensity data (initial data for transmittance calculation) of inspection light detected by the detector 127 in a state in which a measurement target is not installed in advance. Data is used to calculate transmittance.

In step S1, the control unit 131 controls the stage drive unit 119 to move the XY stage 117 to the initial position. Here, the initial position is a position where the first measurement point of the mixed filter 10 that is the measurement target S is irradiated with the inspection light.
In step S3, the control unit 131 controls the rotation device driving unit 125 so that the analyzer 121 transmits 0 ° polarized light. That is, the control unit 131 adjusts the angle of the polarization axis of the analyzer 121 by controlling the rotation device driving unit 125.
In step S5, the control unit 131 controls the light source 111 to emit inspection light. The inspection light emitted from the light source 111 enters the beam expander 113 and the light intensity is made uniform. The inspection light having the uniform light intensity enters the pinhole 115 and is converted into spot light having a predetermined diameter. The inspection light converted into the spot shape is irradiated to a predetermined measurement point of the measuring object S. This inspection light is sufficiently larger than the unit area of the X-direction wire grid and Y-direction wire grid of the mixed filter included in the measurement point, and the X-direction wire grid and Y-direction wire included in the irradiation area of the inspection light. The area ratio of the grid is equal to the area ratio of the X-direction wire grid and the Y-direction wire grid of the mixed filter. The inspection light that has passed through the measuring object S enters the analyzer 121. The analyzer 121 transmits only 0 ° polarized light of the inspection light. The inspection light (0 ° polarized light) that has passed through the analyzer 121 is incident on the detector 127. The detector 127 detects the intensity of the inspection light (0 ° polarized light) and outputs an analog light intensity signal.

In step S7, the control unit 131 converts the analog light intensity signal related to 0 ° polarization output from the detector 127 into digital data by using a sampling clock having a predetermined frequency in the A / D converter 131a, and the light intensity. Get the data.
In step S <b> 9, the control unit 131 calculates a transmittance T <b> 0 of 0 ° polarized light that has passed through the measurement object S. That is, the control unit 131 reads from the storage unit 133 light intensity data (comparative intensity data) of 0 ° polarized light that has been measured in advance without the measurement target S and stored in the storage unit 133. The control unit 131 calculates the transmittance T0 of 0 ° polarized light transmitted through the measuring object S from the comparison intensity data and the light intensity data of 0 ° polarized light acquired in step S7. Further, the control unit 131 stores the calculated transmittance T0 in the storage unit 133.
In step S11, the control unit 131 controls the rotation device driving unit 125 so that the analyzer 121 transmits 90 ° polarized light. That is, the control unit 131 adjusts the angle of the polarization axis of the analyzer 121 by controlling the rotation device driving unit 125.

In step S13, the control unit 131 converts the analog light intensity signal related to the 90 ° polarization output from the detector 127 into digital data by the sampling clock having a predetermined frequency in the A / D converter 131a, and the light intensity. Get the data.
In step S15, the control unit 131 calculates a transmittance T90 of 90 ° polarized light that has passed through the measurement object S. That is, the control unit 131 reads out 90 ° -polarized light intensity data (comparative intensity data) measured in advance in a state where the measurement target S does not exist and stored in the storage unit 133 from the storage unit 133. The control unit 131 calculates the transmittance T90 of 90 ° polarized light transmitted through the measuring object S from the comparison intensity data and the light intensity data of 90 ° polarized light acquired in step S13. Further, the control unit 131 stores the calculated transmittance T0 in the storage unit 133.
In step S17, the control unit 131 reads the transmittance T0 and the transmittance T90 stored in the storage unit 133, and calculates the transmittance ratio T0 / T90. The control unit 131 stores the calculated transmittance ratio T0 / T90 in the storage unit 133.

In step S19, the control unit 131 determines pass / fail of the measurement point. Specifically, pass / fail ratio T0 / T90 (measured value) calculated in step S17 is compared with a reference value of transmittance ratio T0 / T90 to determine pass / fail. The control unit 131 reads from the storage unit 133 the transmittance ratio T0 / T90 (reference value) at the reference point of the mixed filter that has been determined to be non-defective in advance. An absolute value of a value obtained by subtracting a predetermined reference value of the transmittance ratio from the transmittance ratio T0 / T90 (measured value) calculated in step S17 is calculated. When this absolute value is within a predetermined tolerance range, it is determined that the measurement point is a non-defective part having good optical characteristics, and when the absolute value is outside the tolerance range, The measurement point is determined to be a defective part that does not have good optical characteristics.
Further, in this step, the control unit 131 may perform determination of the quality of the measurement point based on the transmittance T0 and the transmittance T90 in addition to the quality determination of the measurement point based on the transmittance ratio T0 / T90. Specifically, similarly to the pass / fail determination based on the transmittance ratio T0 / T90, the transmittance T0 (measured value) calculated in step S9 and the transmittance T90 (measured value) calculated in step S15 are calculated in advance. When the difference between the measured value and the reference value is within a predetermined tolerance range, the transmittance is compared with the reference values of the transmittance T0 and the transmittance T90 at the reference point of the mixed filter determined to be non-defective. From this point of view, it may be determined that the measurement point is a non-defective part.

When the pass / fail judgment of the measurement point is performed based on the three values of the transmittance ratio T0 / T90, the transmittance T0, and the transmittance T90, all of the transmittance ratio T0 / T90, the transmittance T0, and the transmittance T90 When the difference from the reference value is within the allowable value, the measurement point is determined to be a non-defective part.
In addition, the pass / fail judgment based on the transmittance T0 and the transmittance T90 is added only when the measurement point is determined as “non-defective” by comparing the value of the measurement point and the reference point with respect to the transmittance ratio T0 / T90. You may make it carry out.
The control unit 131 labels the determination result together with the coordinate axis of the XY stage, in other words, the position coordinate of the measurement point, and stores the result in the storage unit 133.

In step S21, the control unit 131 controls the light source 111 to stop emitting inspection light.
In step S <b> 23, the control unit 131 confirms whether the non-defective product determination is performed at all the measurement points of the measurement target S. If the non-defective product determination has been completed for all measurement points (Yes in step S13), the process ends. If there are remaining measurement points to be judged as good (No in step S13), the process proceeds to step S14.
In step S14, the control unit 131 controls the stage driving unit 119 so as to move the XY stage 117 to a position where the inspection light is irradiated to the next measurement point to be measured.
Then, step S2 and subsequent steps are repeated.

[Example 1]
FIG. 4 is a schematic diagram of an optical element to be inspected in the first embodiment. The mixed filter 10 to be inspected in the present embodiment is a mixed filter in which an X-direction wire grid and a Y-direction wire grid are arranged in a checkered pattern, and the wire grid area ratio A between the X direction and the Y direction. : B is 1: 1. This mixed filter 10 is a mixture of an X-direction wire grid and a Y-direction wire grid formed of aluminum (Al) on a quartz substrate (4 inch wafer, thickness: 1 mm).
In Example 1, a red semiconductor laser (wavelength 660 nm) was used as the light source 111 of the inspection apparatus 100 (see FIG. 2). The pinhole 115 had a diameter of about 2 mm, and the surface of the mixed filter 10 was irradiated with spot-shaped inspection light having a diameter of about 2 mm.
Hereinafter, the procedure number of “Summary of Procedure” shown in the above [Inspection Procedure] will be described with reference to the description.

[Procedure 1 and 2]
The measurement point 1 in FIG. 4 is almost free from defects, and the Al line width is almost constant in the XY directions, which is revealed by electron microscope observation. This measurement point 1 is set as a reference measurement point.
When the transmittance T0 of 0 ° polarized light and the transmittance T90 of 90 ° polarized light were measured by the inspection apparatus 100 at the measurement point 1, T0 = 43.2% and T90 = 43.0%. Therefore, the measurement parameter α1 is
α1 = T0 / T90 = (A × Tp1) / (B × Tp2) = 1.0046
It became.
Although the absolute values of Tp1 and Tp2 at the measurement point 1 are not clear, α1 is almost equal to the area ratio of the X-direction wire grid and the Y-direction wire grid (α1≈A / B = 1). It can be inferred that the TM transmittance of the directional wire grid and the TM transmittance of the Y-direction wire grid are substantially equivalent values. Therefore, it can be determined that the manufacturing error of the X-direction wire grid and the manufacturing error of the Y-direction wire grid are substantially the same for the pitch, line height, and line width of the metal lines.

  As described above, if the wire grid constituting the mixed filter is within the same wafer, the pitch and line height of the metal lines are substantially constant, and the line width tends to vary easily. Therefore, assuming that the pitch and line height of the metal lines are the same, Tp1 and Tp2 mainly depend on the line width, but since α1≈A / B = 1, the X-direction wire grid also relates to the line width. It is assumed that the Y-direction wire grid is almost constant. From the above, this measurement point 1 is used as a reference measurement point and compared with other measurement points.

[Procedure 3]
The measurement results of 0 ° polarized light transmittance T0 and 90 ° polarized light transmittance T90 at measurement point 2 were T0 = 43.0% and T90 = 42.4%. Therefore, the measurement parameter α2 is
α2 = T0 / T90 = (A × Tp1) / (B × Tp2) = 1.0141
It became.
The measurement results of 0 ° polarized light transmittance T0 and 90 ° polarized light transmittance T90 at measurement point 3 were T0 = 42.0% and T90 = 42.8%. Therefore, the measurement parameter α3 is
α3 = T0 / T90 = (A × Tp1) / (B × Tp2) = 0.9860
It became.
As a result of measuring the transmittance T0 of 0 ° polarized light and the transmittance T90 of 90 ° polarized light at the measurement point 4, T0 = 43.1% and T90 = 42.9%. Therefore, the measurement parameter α4 is
α4 = T0 / T90 = (A × Tp1) / (B × Tp2) = 1.0047
It became.

[Procedures 4 and 5]
As described above, since the measurement point 1 is known to be free from defects and the line width is substantially constant in the vertical and horizontal directions,
Using the value of T0 / T90 (measurement parameter α1) at measurement point 1 as a reference value, non-defective product determination at measurement points 2 to 4 is performed. When the absolute value of the difference from the value at the measurement point 1 with respect to the value of T0 / T90 at the measurement points 2, 3, and 4 is calculated as a determination parameter, it is as follows.
| Α2-α1 | = 0.0095
| Α3-α1 | = 0.0186
| Α4-α1 | = 0.0001
Here, if a tolerance value of 0.001 or less is set as a difference between the reference point and α2, and α3 are separated from α1 by 0.001 or more, the wire grid of the measurement points 2 and 3 has some defect. Alternatively, it can be determined that there is a problem in optical characteristics such as line widths differing vertically and horizontally. The value (α4) of T0 / T90 at the measurement point 4 is close to the value at the measurement point 1, the value of | α4-α1 | is 0.001 or less, and a good pattern is formed as in the measurement point 1, It can be judged as a good product.

Moreover, when the transmittance | permeability T0 and T90 are compared about the reference | standard measurement point 1 and the other measurement points 2-3, it is as follows.
Measurement point 1 T0 = 43.2%, T90 = 43.0%
Measurement point 2 T0 = 43.0% (−0.2%), T90 = 42.4% (−0.6%)
Measurement point 3 T0 = 42.0% (−1.2%), T90 = 42.8% (−0.2%)
Measurement point 4 T0 = 43.1% (−0.1%), T90 = 42.9% (−0.1%)
Here, if an absolute value of 0.5% or less is set as the allowable value of the difference from the reference measurement point 1, the transmittances T0 and T90 are both within the allowable value from the measurement point 1 for the measurement point 4. It can be determined that there are no defects such as black defects and white defects.
On the other hand, the transmittance T90 at the measurement point 2 is 0.6% lower than the transmittance T90 at the measurement point 1, and there is a difference exceeding the allowable value. Also, the transmittance T0 at the measurement point 3 is 1.2% lower than the transmittance T0 at the measurement point 1, and there is a difference exceeding the allowable value. For this reason, the Y-direction wire grid at the measurement point 2 and the X-direction wire grid at the measurement point 3 are “defective products”, and it can be determined that a black defect may exist.

The pass / fail judgment with respect to the reference point is made with only three points, but in actuality, it is possible to inspect more measurement points. In addition, since it is possible to continuously scan the XY stage and examine the surface distribution of the presence / absence of defects, the determination mechanism of the present invention can be used to make a high-speed determination.
The allowable value is determined according to the yield of the product and the performance of the product to be finally obtained. If the allowable value is set to be small, that is, the difference from the reference point is set to be small, only a high-performance mixed filter can be selected, but the product yield is reduced. On the contrary, if the allowable value is increased, the product yield will be improved.

[Example 2]
FIG. 5 is a schematic diagram of an optical element to be inspected in the second embodiment. In the mixed filter 10 to be inspected in this embodiment, the area ratio A: B of the Y direction wire grid to the X direction wire grid is 3: 1, that is, A is 75% and B is 25%. It is mixed. Since the inspection apparatus 100 used for the inspection is the same as that of the first embodiment, the description thereof is omitted.

[Procedure 1 and 2]
Since the measurement point 1 in FIG. 5 is almost free of defects and the Al line width is almost constant in the XY directions, it has been revealed by electron microscope observation. Let it be a point.
When the 0 ° polarized light transmittance T0 and the 90 ° polarized light transmittance T90 at the measurement point 1 were measured by the inspection apparatus 100, T0 = 64.5% and T90 = 21.6%. Therefore, the measurement parameter α1 is
α1 = T0 / T90 = (A × Tp1) / (B × Tp2) = 2.8661
It becomes.

Although the absolute values of Tp1 and Tp2 at the measurement point 1 are not clear, α1 is a value approximately equal to the area ratio of the X-direction wire grid and the Y-direction wire grid (α1≈A / B = 3). It can be inferred that the TM transmittance of the directional wire grid and the TM transmittance of the Y-direction wire grid are substantially equivalent values. Therefore, it can be determined that the manufacturing error of the X-direction wire grid and the manufacturing error of the Y-direction wire grid are substantially the same for the pitch, line height, and line width of the metal lines.
As described above, if the wire grid constituting the mixed filter is within the same wafer, the pitch and line height of the metal lines are substantially constant, and the line width tends to vary easily. Therefore, assuming that the pitch and line height of the metal lines are the same, Tp1 and Tp2 mainly depend on the line width, but α1≈A / B = 3. It is assumed that the Y-direction wire grid is almost constant. From the above, this measurement point 1 is used as a reference measurement point and compared with other measurement points.

[Procedure 3]
As a result of measuring the transmittance T0 of 0 ° polarized light and the transmittance T90 of 90 ° polarized light at the measurement point 2, T0 = 62.5% and T90 = 21.0%.
α2 = T0 / T90 = (A × Tp1) / (B × Tp2) = 2.9762
It becomes.
As a result of measuring the transmittance T0 of 0 ° polarized light and the transmittance T90 of 90 ° polarized light at the measurement point 3, T0 = 64.6% and T90 = 21.6%.
α3 = T0 / T90 = (A × Tp1) / (B × Tp2) = 2.909
It becomes.
As a result of measuring the transmittance T0 of 0 ° polarized light and the transmittance T90 of 90 ° polarized light at the measurement point 4, T0 = 64.4% and T90 = 21.3%.
α4 = T0 / T90 = (A × Tp1) / (B × Tp2) = 3.0235
It becomes.

[Procedures 4 and 5]
Based on the value of T0 / T90 at the measurement point 1 (measurement parameter α1), the non-defective product determination at the measurement points 2 to 4 is performed. When the values of T0 / T90 at the measurement points 2, 3, 4 are (measurement parameters α2, α3, α4) α2, α3, α4, and the absolute value of the difference from the value at the measurement point 1 is calculated as a determination parameter, It becomes like this.
| Α2-α1 | = 0.999
| Α3-α1 | = 0.0006
| Α4-α1 | = 0.0374
Here, if the allowable value of the difference from the reference point is 0.001 or less, it can be determined that all measurement points are defective. If the allowable value is 0.003 or less, the measurement points 2 and 3 are good products, but the measurement point 4 can be determined as a defective product. As described above, it is a feature of the present invention that the determination criteria for good products and defective products can be determined from the balance with the desired optical characteristics and can be arbitrarily selected.
In the present embodiment, as in the first embodiment, in addition to the transmittance ratio T0 / T90, the pass / fail determination may be performed by comparing the transmittances T0 and T90 with reference values.

Example 3
The optical elements to be inspected in Example 3 are the same as those in Example 2 (FIG. 5). That is, in the mixed filter 10 to be inspected, the area ratio A: B of the Y-direction wire grid to the X-direction wire grid is 3: 1, that is, A is 75% and B is 25%. ing. Moreover, since the inspection apparatus 100 used for the inspection is the same as that of the first embodiment, the description thereof is omitted.

The mixed filter to be inspected is a one-dimensional photonic crystal element using a multilayer film. The sample to be inspected is formed with a multilayer film in which Ta ₂ O ₅ (tantalum pentoxide) and SiO ₂ (silicon dioxide) are alternately laminated. Note that Ta ₂ O ₅ functions as a high refractive index material, and SiO ₂ functions as a low refractive material.
Such a mixed filter can be formed by preparing a line pattern in advance on the surface of a quartz substrate and then alternately depositing Ta ₂ O ₅ and SiO ₂ by a vacuum film forming method. That is, by appropriately changing the direction of the line pattern on the quartz substrate surface for each reference region, the first polarizing region that transmits the X-polarized component and the second polarizing region that transmits the Y-polarized component in a predetermined pattern. Two-dimensional arrangement is possible. The mixed filter used in Example 3 is one in which each film thickness is adjusted so as to exhibit a polarization separation function at a wavelength of 660 nm.
The transmittance of the mixed filter was examined at four points in the figure.

[Procedure 1 and 2]
The measurement point 1 has no defects, has substantially the same polarization separation characteristics in the XY directions, and the line width on the substrate is also uniform by electron microscope observation. At this measurement point, the transmittance of 0 ° polarized light and the transmittance of 90 ° polarized light are T0 = 68.25% and T90 = 22.82%, and the measurement parameter α1 is
α1 = T0 / T90 = (A × Tp1) / (B × Tp2) = 2.908
It becomes.

[Procedure 3]
As a result of measuring the transmittance of 0 ° polarized light and the transmittance of 90 ° polarized light at measurement point 2, T0 = 68.51%, T90 = 22.93%, and the measurement parameter α2 is
α2 = T0 / T90 = (A × Tp1) / (B × Tp2) = 2.888
It becomes.
As a result of measuring the transmittance of 0 ° polarized light and the transmittance of 90 ° polarized light at the measurement point 3, T0 = 65.66% T90 = 20.85%, and the measurement parameter α3 is
α3 = T0 / T90 = (A × Tp1) / (B × Tp2) = 3.1491
It becomes.
As a result of measuring the transmittance of 0 ° polarized light and the transmittance of 90 ° polarized light at the measurement point 4, T0 = 68.20%, T90 = 22.83%, and the measurement parameter α4 is
α4 = T0 / T90 = (A × Tp1) / (B × Tp2) = 2.873
It becomes.

[Procedures 4 and 5]
Since it is known that the measurement point 1 is free of defects and the line width is almost constant in the vertical and horizontal directions, the non-defective product determination of the measurement points 2 to 4 is performed using the measurement parameter α1 as a reference value. When the absolute value of the value obtained by subtracting the value at the measurement point 1 (measurement parameter α1) from the value of T0 / T90 at the measurement points 2 to 4 (measurement parameters α2, α3, α4) is calculated as a determination parameter as follows: Become.
| Α2-α1 | = 0.020
| Α3-α1 | = 0.1583
| Α4-α1 | = 0.0035
Here, if the allowable value of the difference from the reference point is set to 0.003 or less, the measurement point 2 can be determined as a non-defective product, and the measurement points 3 and 4 are defective, or Ta ₂ O ₅ and SiO ₂ are When the film is formed, it can be determined that the product is inferior in quality because the film thickness or the like is not formed as designed.
In the present embodiment, as in the first embodiment, in addition to the transmittance ratio T0 / T90, the pass / fail determination may be performed by comparing the transmittances T0 and T90 with reference values.

Example 4
FIG. 6 is a schematic diagram of an optical element to be inspected in Example 4.
A plurality of chips 15 are formed on the 4-inch wafer 13 shown in FIG. The chip 15 is a 3 mm square chip. A plurality of micron-order unit regions 11 are formed on the chip 15, and an X-direction wire grid 11 x or a Y-direction wire grid 11 y is formed in each unit region 11. That is, the chip 15 is substantially the same as the mixed filter 10 described above. The chip 15 is a mixed filter in which the X-direction wire grid 11x and the Y-direction wire grid 11y are arranged in a checkered pattern, and the area ratio A: B of the wire grid between the X direction and the Y direction is 1: 1. It is.
In this example, the wafer 13 was placed on the XY stage 117 as the measurement object S shown in FIG. The stage driving unit 119 was controlled by the stage driving unit of the control unit 131 so that the inspection light was irradiated to the center of each chip 15.
Since the inspection apparatus 100 used for the inspection is the same as that of the first embodiment, the description thereof is omitted.
In this example, as a result of the pass / fail judgment, it was possible to discriminate 34 good products and 2 defective products from the 36 chips 15.

  In the embodiments described above, the mixed type filter to be inspected includes a wire grid element and a one-dimensional photonic crystal with a multilayer film. However, the inspection method described in this specification uses 0 ° polarized light. Other types of optical elements in which regions that transmit 90 ° polarized light are arranged at a predetermined area ratio can be the inspection target. For example, a polarizer including silver ellipsoidal particles in borosilicate glass can be an inspection target. Further, the substrate of the optical element is not limited to a glass substrate such as a quartz substrate, a borosilicate glass substrate, or BK7, but may be a transparent resin film.

  DESCRIPTION OF SYMBOLS 10 ... Mixed filter, 11 ... Unit area | region, 11x ... X direction wire grid, 11y ... Y direction wire grid, 13 ... Wafer, 15 ... Chip, 100 ... Inspection apparatus, 110 ... Optical system, 111 ... Light source, 113 ... Beam Expander, 115 ... pinhole, 117 ... XY stage, 119 ... stage driving unit, 121 ... analyzer, 123 ... analyzer rotating device, 125 ... rotating device driving unit, 127 ... detector, 130 ... processing device, 131 ... Control unit, 133 ... storage unit, 135 ... storage unit, 137 ... keyboard, 139 ... mouse, S ... measurement object

JP 2007-315990 A

Claims (8)

An optical system in which a first polarization region that transmits a first polarization component of incident light and a second polarization region that transmits a second polarization component of incident light are two-dimensionally arranged at a predetermined area ratio. A method for inspecting an element,
The optical element is irradiated with inspection light having an irradiation area sufficiently larger than the first polarizing area and the second polarizing area, and the intensity of the first polarization component of the inspection light transmitted through the optical element is detected. A first detection step to
A second detection step of irradiating the optical element with the inspection light and detecting the intensity of the second polarization component of the inspection light transmitted through the optical element;
From the intensity of the first polarization component of the inspection light detected in the first detection step, a first transmittance calculation step of calculating the transmittance of the first polarization component;
From the intensity of the second polarization component of the inspection light detected in the second detection step, a second transmittance calculation step of calculating the transmittance of the second polarization component;
A transmittance ratio from the transmittance of the first polarization component calculated in the first transmittance calculation step and the transmittance of the second polarization component calculated in the second transmittance calculation step. A transmittance ratio calculating step for calculating
When the absolute value of a value obtained by subtracting a predetermined reference value corresponding to the area ratio from the transmittance ratio calculated in the transmittance ratio calculating step is within a predetermined range, the optical element is a non-defective product A pass / fail judgment step for judging,
An inspection method for an optical element, comprising:   2. The optical element inspection method according to claim 1, wherein a polarization component transmitted by the first polarization region and a polarization component transmitted by the second polarization region are orthogonal to each other.   In the non-defective product determination step, the value obtained by dividing the transmittance ratio by the area ratio is approximately transmitted through the first polarization component and the second polarization region of the inspection light transmitted through the first polarization region. The optical element inspection method according to claim 1, wherein a TM transmittance ratio that is a ratio of the inspection light to the second polarization component is used. An optical element in which a first polarization region that transmits a first polarization component of incident light and a second polarization region that transmits a second polarization component of incident light are two-dimensionally arranged at a predetermined area ratio Inspection equipment,
A light source for irradiating inspection light to a region sufficiently larger than the first polarizing region and the second polarizing region of the optical element;
First detection means for irradiating the optical element with the inspection light from the light source and detecting the intensity of the first polarization component of the inspection light transmitted through the optical element;
Second detection means for irradiating the optical element with the inspection light from the light source and detecting the intensity of the second polarization component of the inspection light transmitted through the optical element;
First transmittance calculation means for calculating the transmittance of the first polarization component from the intensity of the first polarization component of the inspection light detected by the first detection means;
Second transmittance calculation means for calculating the transmittance of the second polarization component from the intensity of the second polarization component of the inspection light detected by the second detection means;
A transmittance ratio from the transmittance of the first polarization component calculated by the first transmittance calculation unit and the transmittance of the second polarization component calculated by the second transmittance calculation unit. A transmittance ratio calculating means for calculating
When the absolute value of a value obtained by subtracting a predetermined reference value corresponding to the area ratio from the transmittance ratio calculated by the transmittance ratio calculating means is within a predetermined range, the optical element is a non-defective product A pass / fail judgment means for judging;
An optical element inspection apparatus comprising:   The optical element inspection apparatus according to claim 4, wherein the polarization component transmitted by the first polarization region and the polarization component transmitted by the second polarization region are orthogonal to each other.   In the non-defective product determination step, the value obtained by dividing the transmittance ratio by the area ratio is approximately transmitted through the first polarization component and the second polarization region of the inspection light transmitted through the first polarization region. 6. The optical element inspection apparatus according to claim 4, wherein a TM transmittance ratio which is a ratio of the inspection light to the second polarization component is utilized.   The optical element according to any one of claims 4 to 6, further comprising light intensity averaging means for making the light intensity of the inspection light uniform in the irradiation region in front of the optical element. Inspection device.   8. The optical element inspection apparatus according to claim 4, wherein the light source is a light source that emits single-wavelength inspection light.

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