KR20120089575A - Transmittance measurement apparatus and transmittance measurement method - Google Patents

Abstract

PURPOSE: A device and a method for measuring a penetration ratio are provided to measure a penetration ratio at a high precision by controlling errors caused by internal reflecting lights. CONSTITUTION: A device(100) for measuring a penetration ratio comprises a light source(2), a first optical system, a second optical system, a diaphragm(7), and an optical detecting member. The light source injects lights to be inspected. The first optical system collects the lights to be inspected, thereby forming a spot on a measurement object. The second optical system collects the lights to be inspected penetrating through the measurement object, thereby forming a common region phase of the spot. The diaphragm is arranged near to the common region phase. The optical detecting member detects the lights to be inspected penetrating the diaphragm.

Description

Transmittance measuring apparatus and transmittance measuring method {TRANSMITTANCE MEASUREMENT APPARATUS AND TRANSMITTANCE MEASUREMENT METHOD}

The present invention relates to a transmittance measuring device and a transmittance measuring method for measuring a transmittance of a measurement target having a region that transmits light.

In the manufacturing process of electronic components, such as a liquid crystal panel, what is called a multi-gradation photomask which added at least 1 layer of semi-permeable film pattern to the conventional monochrome pattern is used for cost reduction by reducing the number of masks [Japan See Patent Application Publication No. 2009-258250 (hereinafter referred to as Patent Document 1). Controlling the transmittance of this kind of semipermeable membrane pattern is important for managing the quality of the multi-gradation photomask. Therefore, in the quality control of the multi-gradation photomask, a reference mask is prepared using the same components as the semi-permeable film actually patterned, the transmittance is measured, and evaluated as the transmittance of the semi-transmissive film pattern.

Japanese Unexamined Patent Publication No. 4358848 (hereinafter referred to as Patent Document 2) describes a transmittance measuring method for measuring the transmittance of a specific region (pixel of a color filter) of a sample. In the transmittance measurement method described in Patent Document 2, the test light is focused on the measurement target region of the sample, the transmitted light intensity is measured, and the transmittance of the region is calculated based on the measured intensity.

By the way, since the semi-transmissive film pattern is complicated and finely formed on the transparent substrate which has a large area, it may be difficult to manufacture with uniform transmittance and may not correspond with the transmittance | permeability of a reference mask. In addition, when the light transmittance at the stage in which only the semi-transmissive film is formed and the photomask finished product subjected to patterning through a plurality of processes, the same transmittance may not be exhibited. Therefore, in order to manage a photomask, it is preferable to measure the transmittance | permeability of the semi-permeable film pattern formed in the arbitrary position on a photomask irrespective of the surrounding pattern.

It is considered that the transmittance of the fine semi-transmissive film pattern can be measured by improving and developing the transmittance measurement method described in Patent Document 2 above and condensing the test light onto the multi-gradation photomask. For example, when the light to be examined is focused on the semi-transmissive film pattern and the transmitted light is detected by the photodetector, it is considered that the transmittance of the fine semi-transmissive film pattern can be measured without being affected by the transmittance of the surrounding pattern.

However, in the case where the above-described transmittance measuring method is carried out, it is assumed that the photodetector detects not only the direct light transmitted directly through the multi-gradation photomask but also the internal reflected light of the transparent substrate. The internal reflected light is defined as the light emitted from the transparent substrate after the internal reflection component generated at the time of ejection of the transparent substrate is internally reflected again on the transfer pattern formation surface of the transparent substrate. The internal reflected light also includes multiple reflected light that repeats the internal reflection of the exit surface of the transparent substrate and the transfer pattern forming surface a plurality of times.

The reflectance on the transfer pattern forming surface is changed depending on the pattern drawn on the transfer pattern forming surface. When the reflectance is changed, the amount of detected light detected by the photodetector is also changed. That is, since the transmittance of the semi-transmissive film pattern measured using the photodetector changes depending on the pattern on the transfer pattern formation surface, it is difficult to accurately measure it.

This invention is made | formed in view of the said situation, Comprising: It aims at providing the transmittance | permeability measuring apparatus suitable for measuring the transmittance | permeability of the measurement object area | region by high precision, suppressing the error by the internal reflected light.

The transmittance | permeability measurement apparatus which concerns on one form of this invention which solves the said subject transmits the light source device which injects a test light, the 1st optical system which collects the said test light, and forms a spot on a measurement object, and a measurement object And a second optical system for condensing a light to be inspected to form a spot conjugate image, an aperture disposed in the vicinity of a formation position of the conjugate image, and light detecting means for detecting the detected light transmitted through the aperture. Doing.

According to the present invention, the internally reflected light generated when the light to be examined passes through the object to be measured can be guided to the photodetecting means without any internal reflection of the object to be measured while cutting the internally reflected light by the aperture. Since the change in the transmittance depending on the pattern on the measurement target is substantially suppressed, for example, the transmittance measurement of the fine semipermeable membrane pattern is performed with high accuracy. That is, according to this invention, the transmittance | permeability measurement apparatus suitable for measuring the transmittance | permeability of the measurement object area | region by high precision by suppressing the error by internal reflection light is provided.

In order to satisfy the function of transmitting the direct light and the function of blocking the internal reflected light, the diaphragm has a luminous flux at the position of the aperture of the internal reflected light generated when the aperture diameter is equal to or larger than the conjugate diameter and the test light passes through the measurement object. It may be less than the diameter.

The diaphragm may have an opening diameter that falls within a range of 2 to 400 times the diameter of the airspace in order to more appropriately exhibit the function of transmitting the direct light and blocking the internal reflected light.

The light source device may be configured to emit light of a specific wavelength in order to form a minute spot on the measurement target.

Moreover, the transmittance | permeability measurement method which concerns on one form of this invention is a transmittance | permeability measurement method of the photomask which has the semi-transmissive pattern in which at least a semi-transmissive film is patterned on a transparent substrate, and uses the said transmittance measurement apparatus of the It includes a method of measuring the transmittance.

The photomask which is the measurement target according to the present invention has a transflective pattern on which a transflective film is patterned and a light shielding film pattern on which a light shielding film is patterned on a transparent substrate, thereby providing a multi-gradation photo including a light transmitting part, a light shielding part, and a transflective part. It is a mask.

BRIEF DESCRIPTION OF THE DRAWINGS The block diagram which shows the structure of the transmittance | permeability measurement apparatus of embodiment of this invention.
2 is a block diagram showing the configuration of a transmittance measuring device according to an embodiment of the present invention.
3 is a diagram showing a transfer pattern forming surface of a photomask to be measured.
4 is a diagram showing a transfer pattern forming surface of a photomask to be measured.

EMBODIMENT OF THE INVENTION Hereinafter, with reference to drawings, the transmittance | permeability measurement apparatus of embodiment of this invention is demonstrated.

The transmittance measuring device of the present embodiment is a device for measuring the transmittance of a photomask, and is suitably configured for measuring the transmittance of a fine semi-transmissive film pattern formed on a transparent substrate. 1 and 2 are block diagrams showing the configuration of the transmittance measuring apparatus 100 according to the present embodiment. FIG. 1 shows the structure of the entire transmittance measuring apparatus 100, and FIG. 2 shows the structure of a part of the transmittance measuring apparatus 100. As shown in FIG.

As shown in FIG. 1, the transmittance measuring device 100 has a light transmitting unit 1 and a light receiving unit 4. Between the light transmitting unit 1 and the light receiving unit 4, the photomask 8 which is a measurement object is provided so that the measurement object surface (transfer pattern formation surface) may face the light transmission unit 1 side. In this embodiment, the photomask 8 is what is called a multi-gradation photomask for liquid crystal panel manufacture in which the semi-transmissive film pattern was formed in addition to the monochrome pattern on the transparent substrate.

In addition, as mentioned later, the transmittance | permeability measurement apparatus and method of this invention are not limited to the photomask for liquid crystal panel manufacture, nor are it limited to the multi-gradation photomask.

The light transmission unit 1 has the light source device 2 and the 1st condensing lens system 3. The light source device 2 is provided with a laser light source which emits the test light of a specific single wavelength. The light source device 2 may be provided with a light source of another form, such as a light emitting diode (LED).

In addition, the light source device 2 may have a configuration in which a light source for emitting light in a broad wavelength region, such as a mercury lamp, a halogen lamp or a xenon lamp, is combined with a wavelength selection filter for selectively transmitting light of a specific wavelength. As an example, the light source device 2 emits a test light having a wavelength of 405 nm. The light source device 2 includes a collimated lens that converts the emitted light from the light source into collimated light and guides it efficiently to the first condensing lens system 3.

In this invention, a light source can be selected according to the use of a subject. When the object to be measured for transmittance is a photomask for a liquid crystal panel, it is preferable to use the wavelength included in the light source of the exposure machine used when transferring the transfer pattern of the photomask to the transfer object as the wavelength to be examined. For example, a mercury lamp, a halogen lamp, a xenon lamp, an LED which uses any one of i-ray (365 nm), g-ray (405 nm), and h-ray (436 nm) as a representative wavelength and can emit this representative wavelength. Light sources and the like can be used.

In addition, it is common for the laser beam to have a substantially Gaussian distribution in light intensity in the beam (beam). That is, on a plane perpendicular to the optical axis, the light intensity at the center of the beam (near the optical axis) decreases relatively largely (as it goes to the periphery) from the optical axis. On the other hand, in the above-described lamps and LEDs having a plurality of wavelengths, they do not have the same intensity distribution as the laser light, and the light intensity in the light beam depends on the shape of the light source and the optical system for forming the light beam. In this case, in order to have similar light intensity distribution to a laser beam, you may provide the filter (for example, an apodization filter) for the purpose of adjusting the light distribution of a light beam.

When a mercury lamp, a halogen lamp, a xenon lamp, etc. are used as a light source, it is preferable to use combining the wavelength selection filter which selectively transmits the light of a desired wavelength from the light in which the some wavelength was mixed. On the other hand, in the case of a light source that emits light of a specific wavelength, such as a laser light source or an LED, the wavelength selection filter may be provided. Alternatively, it is also useful to apply a light source device having a plurality of single wavelength LEDs or laser light sources. As described above, by switching between and using a plurality of light sources having different single wavelengths, the transmittances for different wavelengths can be measured. Moreover, since the light of the single wavelength emitted from these LED or a laser light source is easy to collect by an optical system, and the diameter of a light beam can be narrowed small, it is suitable.

When using these highly directional light sources, the diameter (beam diameter) of the emitted light beam is enlarged at a predetermined magnification using an optical element such as a beam expander (not shown), and the first condensing lens system described later. It can also introduce into (3). In addition, when using a laser light source as a light source, it is suitable to make oscillation single mode, and it is suitable that the shape of a beam diameter is a circle or an ellipse.

The first condensing lens system 3 is sufficiently aberration corrected so that a minute spot can be formed on the measurement target region 11 of the photomask 8. The first condensing lens system 3 is, for example, NA 0.4, and condenses the test light having a wavelength of 405 nm emitted from the light source device 2 on the measurement target region 11 at a spot diameter of 2.0 μm or less. In the present specification, when it is in the Gaussian intensity distribution of the light source, such as laser light has and is defined as the diameter the range having a strength of at least (about 13.5% of the peak value) 1 / e ² spot light source such as a lamp or LED When using the thing whose intensity distribution does not become a Gaussian distribution, the range where 86.4% or more of light quantity is concentrated is defined as a spot diameter. In addition, all the diameters which are not specified as a "radius" in this specification mean a "diameter."

The light transmitting unit 1 can be moved in a plane parallel to the transfer pattern forming surface of the photomask 8 (that is, in a plane perpendicular to the optical axis) by a moving mechanism (not shown), and a photomask for a liquid crystal panel. The relative position of the optical axis direction with (8) is comprised so that fine adjustment is possible. The light transmitting unit 1 is, for example, when the measurement target region 11 is a semi-transmissive film pattern, in-plane parallel to the transfer pattern forming surface such that the light collecting point of the first condensing lens system 3 is on the semi-transmissive film pattern. And the position in the optical axis direction is adjusted.

In addition, the light receiving unit 4 can also be moved by the moving mechanism of which illustration is abbreviate | omitted. The light transmitting unit 1 and the light receiving unit 4 are preferably integrated through the interlock mechanism to move relative to the photomask 8.

The test light focused on the semi-transmissive film pattern passes through the photomask 8. As the light under test is shown by a dotted line in Fig. 2, when the transparent substrate of the photomask 8 is ejected, a part of the light is internally reflected to reflect the internally again on the transfer pattern formation surface, and then the transparent substrate is ejected. In addition to the direct light (solid line in FIG. 2) transmitted through the photomask 8 without internal reflection, the light receiving unit 4 also enters such internal reflected light (dashed line in FIG. 2).

The light receiving unit 4 has a light quantity detector 5, a second condensing lens system 6, and an aperture 7. The NA on the photomask 8 side of the second condensing lens system 6 is adapted to be photographed by the first condensing lens system 3 so as to efficiently introduce the entire luminous flux of the inspection light focused by the first condensing lens system 3. It is preferable that it is larger than NA of the light beam converging on the measurement target area 11 of the mask 8.

In the present embodiment, the diaphragm 7 is disposed at a position at which the condensing point of the first condensing lens system 3 on the measurement target region 11 is conjugated by the second condensing lens system 6. Therefore, the direct light of the inspected light transmitted through the measurement target region 11 forms a conjugated phase of a minute spot at the position of the diaphragm 7, and passes through the diaphragm 7 (solid line in FIG. 2), but the internal reflected light Since it forms in a position different from direct light and becomes wider at the position of the diaphragm 7, most are blocked by the diaphragm 7 (dashed line in FIG. 2). Therefore, substantially only direct light is detected by the light quantity detector 5.

The luminous flux radius L (unit: mm) of the internal reflection light at the position of the diaphragm 7 defines the condensing angle of the light to be inspected by the first condensing lens system 3 as θ (unit: deg), and the photomask 8 ) Is defined as t (unit: mm), the refractive index of the photomask 8 is defined as n, and the image forming magnification by the second condensing lens system 6 is defined as m. Appears as 1.

In addition, the thickness of the semi-transmissive film pattern is very thin compared to the thickness of the transparent substrate, and can be ignored in calculation. In the present embodiment, the light beam radius L is calculated by making the thickness and refractive index of the transparent substrate alone as the thickness t and the refractive index n of the photomask 8, respectively.

The area ratio Sr between the luminous flux of the internal reflection light at the position of the diaphragm 7 and the opening of the diaphragm 7 is expressed by the following equation when the aperture radius of the diaphragm 7 is defined as r (unit: mm). appear.

The ratio of the internal reflection light reaching the light amount detector 5 among the entire inspection light passing through the measurement target region 11 (hereinafter referred to as "internal reflection transmittance Iy") is a test transmission through the measurement target region 11. In the case where the ratio of the internal reflection light reaching the diaphragm 7 in the entire light is defined as the internal reflection transmittance Ix, it is represented by the following expression (3). In addition, internal reflection light is made into the light beam which has the same intensity distribution.

Here, the diaphragm 7 requires a function of transmitting direct light and a function of blocking internal reflection light. Since the aperture diameter of the diaphragm 7 satisfies both functions, it is equal to or larger than the conjugate phase diameter (direct light diameter) SP formed at the position of the diaphragm 7 and is less than the luminous flux diameter (beam radius L × 2) of the internally reflected light. Is enough. In addition, in this specification, the conjugate phase diameter is a range having an intensity of 1 / e ² or more (about 13.5% of the peak value) when the intensity distribution of the light source becomes a Gaussian distribution like the laser beam, similarly to the spot diameter. Is defined as the conjugate phase diameter, and in the case where the intensity distribution of a light source such as a lamp or an LED does not become a Gaussian distribution, the range where 86.4% or more of the amount of light is concentrated is defined as the conjugate phase diameter.

When the formation position of the conjugated phase and the center of the opening of the diaphragm 7 are eccentric due to an assembly error or the like, there is a fear that the conjugated phase is carried by the diaphragm 7. In addition, depending on the product specification, it is required to further reduce the internal reflected light reaching the light amount detector 5. In order to suppress the amount of Kerare, the aperture diameter of the diaphragm 7 is designed to be large, and the aperture diameter of the diaphragm 7 needs to be designed to reduce the internal reflected light reaching the light amount detector 5. In order to meet these conflicting needs, the aperture diameter of the diaphragm 7 is preferably designed to be limited in size to a range of 2 to 400 times the airspace diameter SP.

When the aperture diameter is twice as large as the conjugate phase diameter SP, the diaphragm 7 shields a part of the portion outside the spot diameter 1 / e ² of the direct light transmitted through the first condensing lens system 3. As a result, about 99.97% of direct light reaches the light amount detector 5. Even when the formation position of the airspace phase and the center of the opening of the diaphragm 7 are eccentric due to an assembly error or the like, the lower end portion having low strength in the airspace phase is only carried by the diaphragm 7. That is, since the loss of direct light is slight, there is no substantial effect on the transmittance measurement of the semi-transmissive film pattern.

In consideration of the measurement accuracy required in the technical field of the photomask, the internal reflected light reaching the light amount detector 5 is preferably suppressed to 1/100 or less by the aperture 7. That is, the aperture radius r of the diaphragm 7 may be designed to be 1/10 or less of the luminous flux radius L of the internal reflection light so as to have an area ratio Sr of 1/100 or less. For example, when tan θ = 0.4, t = 6.0, n = 1.47, and m = 4, L = 13.32 from the equation (1). In order to make area ratio Sr 1/100, it is r = 1.332 from Formula (2). When the spot diameter on the measurement object area | region 11 by the 1st condensing lens system 3 is 2.0 micrometers, since the conjugate phase diameter SP is m = 4, it is 8.0 micrometers. In order that the area ratio Sr is 1/100 or less, since the opening radius r is 1.332 mm and the radius of the conjugated diameter SP is 4.0 µm, the aperture diameter of the diaphragm 7 needs to be about 333 times or less of the conjugated diameter SP. In low cost photomasks, however, the required measurement accuracy is lower than in the above example, and in the measurement device with the required low measurement accuracy, the allowable range for mechanical misalignment is increased or the aberration correction performance of the measurement optical system is low. In consideration of the above, the aperture diameter of the diaphragm 7 may be allowed up to a size 400 times or less of the conjugate air diameter SP.

In addition, in this embodiment, the diaphragm 7 is arrange | positioned in the position where the image converging with the condensing point of the 1st condensing lens system 3 on the measurement object area | region 11 is connected by the 2nd condensing lens system 6. . However, according to the present invention, the diaphragm 7 includes not only the case where the diaphragm 7 is in a position which is completely conjugate with the condensing point of the first condensing lens system 3, but also the case where the diaphragm 7 is disposed on the front side or the rear side thereof. That is, the diaphragm 7 may adjust a luminous flux by blocking a part of the luminous flux before the test light condensed by the 2nd condensing lens system 6 enters a light quantity detector. In this sense, according to the present invention, the stop 7 is arranged near the formation position of the image converging with the condensing point of the first condensing lens system 3 on the measurement target region 11. For example, it is preferable to include the formation position of a conjugated phase, and to exist in the area within 1000 micrometers in an optical axis direction.

Preferably, the diaphragm 7 is disposed at a position within a predetermined allowable tolerance with the median position of the condensing point. The permissible disposition of the diaphragm 7 with respect to the airspace point is the opening diameter of the diaphragm 7 (the amount of air space on the airspace due to the diaphragm 7 due to an assembly error or the like) or the interior detected by the light amount detector 5. This is determined in consideration of the allowable degree of reflected light and the like.

According to the inventors' review, for example, when the reflectance of the light to be inspected on the surface of the object is 80% and the reflectance on the back surface is 4%, the aperture diameter of the diaphragm 7 is 1/2 of the luminous flux diameter of the internally reflected light. Thereby, the influence to the measurement error of the transmittance of the internal reflection light can be about 1% or less.

Si photodiode, photomultiplier, etc. are assumed for the light quantity detector 5. In order to measure the amount of transmitted light of the measurement target region 11 with high accuracy, the light quantity detector 5 may be provided on the inner surface of the integrating sphere, for example. This integrating sphere plays a role of integrating and uniformizing the light (transmitted light flux) received from the incidence port spatially by diffusion reflection on the inner wall surface of the sphere and incidence the light quantity detector.

The light quantity data detected by the light quantity detector 5 is input to the computing device 9. The calculating | arithmetic apparatus 9 calculates the transmittance | permeability T (unit:%) of the photomask 8 based on the input light quantity data. Here, the transmittance Tb (unit:%) of the transparent substrate alone before the thin film is formed is measured in advance using the transmittance measuring device 100 and stored in the memory of the computing device 9. The calculating | arithmetic apparatus 9 calculates the transmittance | permeability Ta (unit:%) of the semi-permeable membrane pattern on the measurement object area | region 11 using following formula (4).

In the transmittance measuring apparatus according to the present invention, an aperture stop adjusting means (not shown) for adjusting the size of the aperture diameter of the stop may be provided. Furthermore, the diaphragm position varying means which can adjust the position of a diaphragm in an optical axis direction can be provided. For example, a case where there are a plurality of types of photomasks having different thicknesses can be considered. In this case, depending on the thickness of the photomask, the formation position of the conjugated phase changes, which may affect the measurement accuracy. In that case, measurement precision can be improved using the said aperture position variable apparatus.

Moreover, the transmittance | permeability measurement apparatus of this invention may be equipped with the means which adjusts the position of a stop to a perpendicular | vertical direction with respect to an optical axis direction.

3 is a diagram showing a transfer pattern forming surface of the photomask 8. Here, the photomask for liquid crystal panels is shown. 4A and 4B are enlarged views of regions R ₁ and R ₂ of FIG. 3, respectively. 3 and 4, the pattern is not formed uniformly on the transfer pattern formation surface. Since the region R ₁ located in the center of the photomask 8 is a portion corresponding to the pixel, the pattern is small and the ratio of the transmissive region is large. Since the region R ₂ located near the outer circumference of the photomask 8 is a wiring portion, there are many patterns and the ratio of the light shielding film pattern is large. Region R _2, the internal reflected light becomes greater than the light-shielding film, because the proportion of the pattern size, the region R _1. Hereinafter, it demonstrates concretely using a comparative example.

(Comparative Example)

In FIG.4 (a), (b), the transmittance | permeability Ta of the semi-permeable membrane itself is 45.0%, and the transmittance | permeability Tb of a transparent substrate is 96.0%. The transmittance T of the photomask 8 is expressed by Equation 4,

0.45 × 0.96 × 100 = 43.2%

to be. In addition, the internal reflectance (the average value of the reflectance of the area | region irradiated by the light beam of the reflected light from the transparent substrate back surface) when internal reflection light is internally reflected by the transcription pattern formation surface is 5.0% in the example of FIG. When the internal reflection transmittance Ix is set to 40.0% in the example of Fig. 4B,

0.45 × (1-0.96) × 0.05 × 100 = 0.09%

0.45 × (1-0.96) × 0.40 × 100 = 0.72%

to be.

In the absence of the second condensing lens system 6 and the diaphragm 7, the transmittance T of the photomask 8 measured using the light quantity detector 5 is the transmittance T + internal reflection transmittance Ix. Is 43.29% in the example, and 43.92% in the example of FIG. As described above, in the absence of the second condensing lens system 6 and the diaphragm 7, the transmittance T, which should be essentially the same value, is changed depending on the surrounding pattern on the measurement target region 11, so that the transmittance of the semi-transmissive film pattern is measured. It causes trouble. In addition, in this comparative example and each Example demonstrated below, in order to grasp | ascertain the characteristic of this invention easily, since the quantity of light with respect to multiple reflection light is very small, it is not considered.

Example 1

In Example 1, the specification of each element which comprises the transmittance | permeability measurement apparatus 100 is as showing next. In addition, in Example 1 and Example 2 described below, the values of the transmittances T, Ta, Tb, and the internal reflection transmittance Ix are the same as those of the comparative example and the respective examples because the photomask 8 as the measurement target is the same. The value of the comparative example is used.

Light source device 2... 405nm semiconductor laser module for emitting collimated light

First condensing lens system 3... Microscope objective lens with NA 0.4 (tanθ = 0.43 of Equation 1)

Light quantity detector 5... Si photodiode

Second condensing lens system 6... Aspheric lens with a focal length of 30 mm

Aperture 7... Pinhole with opening φ20㎛

Photomask 8. Synthetic quartz with a thickness of t = 7.0 mm (index of refraction at wavelength 405 nm n = 1.46966)

The second condensing lens system 6 is arranged at a position where the condensing point of the first condensing lens system 3 is quadrupled on the aperture 7 (that is, m = 4).

In the first embodiment, the luminous flux radius L is 16.38 mm from equation (1). The area ratio Sr is 3.72E-7 from equation (2). The notation E represents a power with 10 being the base and the number on the right side of E being the exponent. From Equation 3, the internal reflection transmittance Iy when the light to be transmitted passes through the semi-transmissive film pattern among the regions R ₁ and R ₂ is as follows.

0.09 × (3.72E-7) × 100 = 3.35E-6

0.72 x (3.72 E-7) x 100 = 2.68 E-5

In the case where the second condensing lens system 6 and the diaphragm 7 are arranged, the transmittance T of the photomask 8 measured using the light amount detector 5 is the transmittance T + internal reflection transmittance Iy. Also in any example of a) and (b), it is about 43.2%. In the first embodiment, by arranging the second condensing lens system 6 and the diaphragm 7, the internal reflection light can be substantially cut while inducing direct light to the light amount detector 5 without fail, and thus the measurement target area 11 The change in transmittance due to the pattern around the image can be substantially suppressed. Therefore, the transmittance | permeability measurement of a fine semi-permeable membrane pattern is performed correctly.

[Example 2]

In the present Example 2, the specification of each element which comprises the transmittance | permeability measurement apparatus 100 is as showing next.

Light source device 2... YAG laser + beam expander (collimator) of wavelength 355nm

First condensing lens system 3... Microscope objective lens with NA 0.65 (tanθ = 0.86 of Equation 1)

Light quantity detector 5... Photo multiplier

Second condensing lens system 6... Lens system of two elements of focal length 50mm

Aperture 7... Opening φ1.5 mm

Photomask 8. Synthetic quartz with a thickness of t = 12.0 mm (refractive index at wavelength 355 nm n = 1.47604)

The second condensing lens system 6 is arranged at a position where the condensing point of the first condensing lens system 3 is tripled on the diaphragm 7 (that is, m = 3).

In the second embodiment, the luminous flux radius L is 41.95 mm from equation (1). Area ratio Sr is 3.20E-4 from Formula (2). From Equation 3, the internal reflection transmittance Iy when the light to be transmitted passes through the semi-transmissive film pattern among the regions R ₁ and R ₂ is as follows.

0.09 x (3.20E-4) x 100 = 0.003

0.72 x (3.20E-4) x 100 = 0.023

The transmittance T of the photomask 8 measured using the light amount detector 5 is 43.203% in the example of FIG. 4A, and 43.223% in the example of FIG. 4B. In the second embodiment, by arranging the second condensing lens system 6 and the diaphragm 7, the internal reflection light can be roughly cut while guiding the direct light to the light amount detector 5 without any omission. The change of the transmittance | permeability by the pattern around an image can be suppressed slightly. Therefore, the transmittance | permeability measurement of a fine semi-permeable membrane pattern is performed correctly.

The above is description of embodiment of this invention. This invention is not limited to said structure, A various deformation | transformation is possible in the range of the technical idea of this invention. For example, this invention is not limited to the transmittance | permeability measurement apparatus which makes a measurement object a photomask, It is applicable also to the transmittance | permeability measurement apparatus which measures the transmittance | permeability of the measurement object of another form which has the area | region which permeate | transmits light.

In addition, as described in the present embodiment, the present invention includes a method for measuring transmittance, and a measurement object includes one having a semitransmissive film pattern formed by patterning a semipermeable film formed on a transparent substrate. In addition, by having the light shielding film pattern further, the effect of the present invention is remarkable in a multi-gradation photomask having a light shielding part, a transmission part, and a semi-transmissive part. It is preferable that the transmittance | permeability of a semi-transmissive film is 5 to 80% with respect to exposure light.

By using such a photomask, by exposing and developing the resist film formed on the transfer object, the exposure amount is partially varied, and the resist pattern having the remaining amount of film depending on the portion can be formed. In this case, since the process which used two masks conventionally becomes one mask, the number of masks used can be reduced and production efficiency of a liquid crystal panel etc. becomes high.

In addition, a multi-gradation photomask of four or more gradations having a plurality of semi-transmissive portions formed by two or more kinds of semi-transmissive film patterns having different light transmittances has also been proposed. The present invention is also effective for ensuring the transmittance of such a plurality of transflective parts.

As a photomask for liquid crystal panels, the part corresponding to the source and the drain in TFT (thin film transistor) is formed as a light shielding part, for example, and the part corresponded to the channel part located adjacent between the said source and the drain is half. A multi-gradation photomask formed as a transmission portion can be used. In recent years, with the miniaturization of patterns such as TFT channel portions, more and more fine patterns are required in multi-gradation photomasks, and portions corresponding to channel widths in the pattern of TFT channel portions, that is, widths of semi-transmissive portions between light shielding films There is a tendency to micronization. Such miniaturization is effective for improving the brightness of the liquid crystal panel and the improvement of the reaction speed. In order to achieve miniaturization, it is important to manage the transmittance of the fine pattern portion.

In addition, the present invention can also be effectively applied to a photomask in which only a semi-transmissive film is formed on a transparent substrate and a predetermined pattern is applied thereto, and the transmittance of the fine pattern of the semi-transmissive portion can be accurately measured. have.

As a measurement object of this invention, what has a line width of 0.5 micrometer or more and 10 micrometers or less in a semi-transmissive pattern is illustrated. Moreover, the effect of this invention is remarkable when it is 1 micrometer or more and 7 micrometers or less, More preferably, they are 2 micrometers or more and 7 micrometers or less.

In the above, although the photomask for liquid crystal panels was illustrated and demonstrated, the use of a photomask is not limited to this. The apparatus and method for measuring transmittance of the present invention can be similarly applied to the measurement of transmittance of photomasks for other applications, and can exhibit useful effects. For example, a photomask for a display device, a photomask for an imaging device, a photomask for an integrated circuit, etc. which contain an organic EL etc. other than a liquid crystal are mentioned. Depending on the application, the semi-transmissive film phase-reverses the transmitted light to use the interference action (the amount of phase shift is 180 degrees ± 30 degrees with respect to the representative wavelength of the transmitted light), or substantially does not use the interference effect (the transmitted light The effect of the present invention is advantageously obtained for any of the followings) of a representative wavelength with a phase shift amount of 60 degrees or less.

Claims (6)

A light source device for emitting the light to be inspected,
A first optical system for condensing the light under test to form a spot on the measurement object;
A second optical system for condensing the test light transmitted through the measurement object to form a conjugate image of the spot;
An aperture disposed near the formation position on the airspace;
Light detecting means for detecting the light to be transmitted through the aperture
Transmittance measuring apparatus having a. 2. The transmittance according to claim 1, wherein the aperture diameter of the diaphragm is equal to or larger than the conjugated phase diameter and is less than the luminous flux diameter at the position of the diaphragm of the internal reflection light generated when the inspected light passes through the measurement object. Measuring device. The transmittance measuring device according to claim 1, wherein the stop has an opening diameter in a range of 2 to 400 times the diameter of the conjugated phase. The transmittance measuring device of claim 1, wherein the light source device emits light having a specific wavelength. As a method for measuring the transmittance of a photomask having a semi-transmissive pattern formed by patterning at least a semi-transmissive film on a transparent substrate,
The transmittance | permeability measurement method of the photomask which measures the transmittance | permeability of the said semi-transmissive pattern using the transmittance | permeability measuring apparatus in any one of Claims 1-4. 6. The photomask of claim 5, wherein the photomask has a transflective pattern in which a transflective film is patterned on a transparent substrate and a light shielding film pattern in which a light shielding film is patterned. A method of measuring the transmittance of a photomask that is a photomask.

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