JP2021139873A - Monitoring device and method of semiconductor substrate protection film peeling - Google Patents

Abstract

To provide a device and method for monitoring peeling of a protection film on a semiconductor substrate.SOLUTION: A monitoring device of semiconductor substrate protection film peeling comprises: light emission means 10 for emitting light to a substrate in a positive direction; a first polarizer 20 located in front of the light emission means 10 and converting the light generated by the light emission means 10 into linear polarization light to emit it in a subject direction; a second polarizer 30 having linearity with the first polarizer 20, located between the substrate and a light receiving sensor 50, converting first reflectance reflected by the substrate into second reflectance, and transmitting the light in a direction of the light receiving sensor 50; the light receiving sensor 50 receiving the light passing through the second polarizer 30, and generating an electrical signal related to the light; and a control part 60 determining whether a film remains on an inspection target substrate surface on the basis of the electrical signal or light intensity of the transmitted light from the light receiving sensor 50.SELECTED DRAWING: Figure 1

Description

The present invention is an apparatus for monitoring whether or not the protective film of a semiconductor substrate is peeled off by utilizing the periodic variability of the intensity of the received light and the magnitude of the variability by utilizing the periodicity of light reception due to the rotation of an optical filter containing a polarizer. And methods.

Korea Registered Patent No. 10-1119571 (Automatic Protective Film Peeler for Semiconductor Printing Circuit Substrate and Film Peeling Method) is a loading device that loads a substrate with films on the upper and lower surfaces onto a table, and a substrate located on the table. An aligner that aligns the film, a scratching device that forms upper and lower scratches on one side of the film (the side in which the substrate travels) to form a gap between the substrate and the film, and a table top. The upper shuttle is configured to attract the upper part of the substrate and reciprocate to about the first reciprocating distance, and the first adhesive tape is attached to one side of the lower film on which the scratched portion is formed. Moves the substrate to one side, or moves the lower tape unit to the other side to peel off the lower film, and grips the lower tape unit by receiving transmission from the upper shuttle to the substrate from which the lower film has been peeled off. A lower shuttle configured to reciprocate about a second reciprocating distance and a second adhesive tape are attached to one side of the upper film on which the scratch is formed, and the lower shuttle moves the substrate to one side. Alternatively, the present invention provides an automatic protective film peeler for a semiconductor printing circuit substrate, characterized in that the upper tape unit is configured to include an upper tape unit that moves to the other side to peel the upper film.

Korean registered patent No. 10-1837443 (patent holder: same as the applicant of the present invention) states that "a vision camera 10 that illuminates a feeling substrate to acquire an image and the vision camera 10 Whether to control the film automatic peeling device according to the processing result of the image processing unit 20 and the image processing unit 20 that executes an image processing algorithm that separates the substrate and the film in order to confirm whether the film remains in the image acquired by Alternatively, for a protective film peeling confirmation system using a vision camera and a semiconductor substrate using a vision camera, which is configured to include a control unit 30 that displays an alarm to an operator or an administrator. The video processing algorithm used in the protective film peeling confirmation system is disclosed.

Thus, there is a need for a device or method to confirm that the film has been completely peeled off by the automatic film peeling device, but in the case of the applicant's several test results unpolarized image analysis, there are problems due to false detection and unsensing. there were. This affects mass production and reduces the reliability of equipment. Therefore, there is a need for a system that can accurately determine whether the feeling has been made properly.

The applicant developed an automatic film peeling device several years ago and succeeded in commercializing it, and then tried to develop a residual film presence / absence determination device that can be applied in the field for several years. We have come to develop this system, which has a bottleneck, has excellent on-site applicability, has extremely few discrimination errors, and does not have a complicated device configuration.

The present invention can solve the problem of film peeling confirmation using the conventional macroscopic or unpolarized image analysis, and automatically and quickly and accurately determine the film feeling or the residue of a part of the film. The purpose of the present invention is to provide a monitoring device and method for peeling a protective film for a semiconductor substrate.

The present invention is an apparatus for monitoring the peeling of a semiconductor substrate protective film by utilizing the periodic variability of the intensity of the received light and the magnitude of the variability by utilizing the light receiving periodicity due to the rotation of an optical filter containing a polarizer. To provide a method.

A film in the inspection area using only a photodiode signal and a discriminator (discrimination program, discriminant algorithm) due to the difference in the intensity of the reflected light or the variability of the intensity of the reflected light without performing conventional precision image analysis. The purpose of the present invention is to provide a monitoring device and method for peeling off a protective film for a semiconductor substrate, which can accurately determine the presence or absence of residual light.

In the present invention, the difference in reflected light characteristics (difference in light intensity) with and without film is amplified by utilizing the birefringence phenomenon due to the residual film after incident after passing through the polarizer, and then the film remains in a certain region with a photosensor. The purpose of the present invention is to provide a monitoring device and method for peeling off a protective film for a semiconductor substrate, which can quickly determine the presence or absence of a protective film.

The monitoring device for peeling off the protective film for a semiconductor substrate of the present invention includes a light emitting means 10 that irradiates light (F1) in the positive direction toward the substrate (T, subject).
A first polarizing element located in front of the light emitting means 10 (between the light emitting means and the substrate) and converting the light (F1) generated by the light emitting means 10 into linearly polarized light (F2) and incident on the subject. The first reflected light (R1) reflected by the substrate (T), which is orthogonal to the (polarizer) 20 and the first polarizing element 20 and is located between the substrate (T) and the light receiving sensor 50, is secondly reflected. A second polarizer (polarizer) 30 that converts light (R2) and passes it in the direction of the light receiving sensor 50, and a control unit that receives light that has passed through the second polarizer 30 and generates it as an electrical signal related to light. Based on the light receiving sensor 50 sent to the light receiving sensor 50 and the electric signal or light intensity value related to the light transmitted from the light receiving sensor 50, it is determined whether or not the film remains on the surface of the substrate (T) to be inspected (whether the film is peeled off). The control unit 60 is included in the control unit 60.

The method for monitoring the peeling of the semiconductor substrate protective film of the present invention is light having other light transmission characteristics for isotropic substances (light blocking) and non-isotropic substances (partially passing light and periodic light blocking). A preparatory step (S100) for preparing the filter means, a light irradiation step (S200) in which the light emitting means 10 irradiates light in the positive direction toward the substrate (T, subject), and the light filtering means is the light emitting means 10 and the substrate. The light filter rotation step (S300) in which the rotating means (motor) 70 rotates the optical filter means while being positioned between (T, subject) and the light receiving sensor 50 are reflected by the substrate (T, subject). The inspection target is based on the reflected light sensing step (S400) that receives the reflected light and generates an electric signal for the intensity of the light, and the control unit 60 based on the electric signal related to the light transmitted from the light receiving sensor 50. It is characterized by a determination step (S500) for determining whether the film remains on the surface of the substrate (T) (whether the film is peeled off).

In the case of the present invention, a semiconductor is used by utilizing the periodic variability of the intensity of the received light or the magnitude of the variability by utilizing the light receiving periodicity generated by the rotation of the optical filter including the polarizer (intentionally generated by the apparatus). A device and a method for monitoring the peeling of the substrate protective film are provided.

In addition, the inspection area is determined only by the photodiode signal and the discriminator (discrimination program, discriminant algorithm) due to the difference in the intensity of the reflected light or the variability of the intensity of the reflected light without performing conventional precision image analysis. Provided are a monitoring device and a method for peeling off a protective film for a semiconductor substrate, which can accurately determine the presence or absence of residual film.

Further, in the case of the present invention, the difference in reflected light characteristics (difference in light intensity) with and without film is amplified by utilizing the birefringence phenomenon due to the residual film after incident after passing through the polarizer, and then the photosensor is used to obtain a certain region. Provided are a monitoring device and a method for peeling a protective film for a semiconductor substrate, which can quickly process and determine whether or not a film remains.

In addition, the device can be realized with components that are easy to compare with excellent performance and are relatively inexpensive compared to video processing, and protection for semiconductor substrates that is excellent in semiconductor line field applicability, productivity, and commercial value. A monitoring device and method for film peeling are provided.

FIG. 5 is an exploded perspective view of a monitoring device for peeling off a semiconductor substrate protective film according to an embodiment of the present invention. It is an external view of the monitoring device of the semiconductor substrate protective film peeling according to one Example of this invention. It is sectional drawing of the monitoring device of the semiconductor substrate protective film peeling according to one Example of this invention. It is a monitoring device use state diagram of how the semiconductor substrate protective film peeling of the present invention depends on the presence or absence of a film. It is a flow chart of the monitoring method of peeling of the semiconductor substrate protective film of this invention. It is a birefringence explanatory view of the isotropic (when there is no film) isotropic (film) material of this invention. It is explanatory drawing of rotation periodicity of the intensity of light intentionally generated in the apparatus of this invention (when there is no residual film, when there is a residual film). It is a rotation periodicity evaluation conceptual explanatory drawing of the light intensity of a control part in the apparatus of this invention (when there is no residual film, when there is a residual film). FIG. 5 is a configuration diagram of a monitoring device for peeling off a semiconductor substrate protective film according to a second embodiment of the present invention. 10a and 10b are drawings for explaining the polarization blocking effect according to the second embodiment of the present invention. It is a monitoring device block diagram of peeling of the protective film for a semiconductor substrate by 2nd Example of this invention (only a part of the configurations are applied).

Hereinafter, the semiconductor substrate protective film peeling monitoring device and method according to the embodiment of the present invention will be described in detail with reference to the attached drawings.

FIG. 1 is an exploded perspective view of a monitoring device for peeling a semiconductor substrate protective film according to an embodiment of the present invention, and FIG. 2 is an external view of a monitoring device for peeling a semiconductor substrate protective film according to an embodiment of the present invention. FIG. 3 is a cross-sectional view of a monitoring device for peeling a semiconductor substrate protective film according to an embodiment of the present invention, and FIG. 4 is a usage state diagram of a monitoring device for peeling a semiconductor substrate protective film according to the present invention.
<First Example>

As shown in FIGS. 1 to 4, the monitoring device for peeling off the semiconductor substrate protective film according to the embodiment of the present invention includes a light emitting means 10, a first polarizing element 20, a second polarizing element 30, and a light receiving sensor 50. It is configured to include a control unit 60. As shown in FIG. 1, the first polarizer 20 and the second polarizer 30 can be coupled while forming one circular flat plate shape. The other polarizer is located in the center.

The light emitting means 10 irradiates the light (F1) in the positive direction toward the substrate (T, subject). The first polarizer 20 is located in front of the light emitting means 10 (between the light emitting means and the substrate), converts the light (F1) generated by the light emitting means 10 into linearly polarized light (F2), and is incident on the subject. Let me.

The second polarizer 30 has orthogonality with the first polarizer 20 and is located between the substrate (T) and the light receiving sensor 50, and secondly reflects the first reflected light (R1) reflected by the substrate. It is converted into reflected light (R2) and passed in the direction of the light receiving sensor 50. The light receiving sensor 50 receives the light that has passed through the second polarizer 30 and generates an electrical signal related to the light and sends it to the control unit 60.

As shown in FIGS. 1 to 4, the control unit 60 determines whether the film remains on the surface of the substrate (T) to be inspected based on the electrical signal or the light intensity value related to the light transmitted from the light receiving sensor 50. Judge (how the film is peeled off). Here, at least one or all of the first polarizing element 20 and the second polarizing element 30 rotate relative to each other with respect to the substrate (T) to be inspected.

When the film remains, the control unit 60 determines whether the film remains based on the degree of periodic variation in the intensity (amplitude) of light generated due to the rotational movement of the first polarizer 20 or the second polarizer 30. To judge.

As shown in FIG. 1, the light emitting means 10 is an LED, and it is desirable that a condenser lens 15 is further provided in front of each of them. Further, as shown in FIG. 4, the second reflected light (R2) located between the second polarizing element 30 and the light receiving sensor 50 and passing through the second polarizing element 30 in the opposite direction is collected. A light receiving lens 40 to be sent to the light receiving sensor 50 can be further included.

The monitoring device 100 for peeling off the semiconductor substrate protective film of the present invention having a shape as shown in FIG. 2 is in a state where the base 70 is gripped by a scanning robot capable of moving the X and Y axes by a fixing means in the reverse posture of FIG. Scan the upper surface of the substrate (where the film peeling work has proceeded) as shown in FIG. The control unit 60 evaluates the degree of periodic variation in the intensity (amplitude) of light generated by scanning in real time due to the rotational movement of the optical filter, and determines whether or not the film remains.

As shown in the drawing, the control unit 60 sets the measured value (V_real) of the fluctuation of the light intensity generated during the fixed time interval (T1) measured in real time to the region where there is no residual film (complete peeling of the film). The variability measurement value (V_real) is the variability reference value (V_ref) compared to the variability reference value (V_ref, current value, average value, maximum value, minimum value) of the light intensity measured in advance in the region). If it is larger than a certain value, it is judged that the film remains in the inspection area.

FIG. 6 is a birefringence explanatory view of an isotropic (without film) material of the present invention (without a film), and FIG. 7 is an explanatory view of the intensity of light intentionally generated in the apparatus of the present invention. It is an explanatory diagram of the rotational periodicity (when there is no residual film, when there is a residual film), and FIG. 8 is a conceptual explanatory diagram of the rotational periodicity evaluation of the light intensity of the control unit in the apparatus of the present invention (the residual film is If not, if there is a residual film).

As shown in FIGS. 7 and 8, the periodicity of the light intensity at one rotation of the optical filter may differ depending on the combination of filters, but it was found that it appears twice (or once) in the embodiment of the present invention. rice field. That is, the maximum and minimum amplitudes appear twice while the light intensity waveform forms a sine wave.

For example, the control unit can use the variance of the received light intensity value (level value) as a variability index (evaluation of variability). The control unit can perform an operation on the variance for T2 = T1 × (0.5 to 10) seconds in a fixed period to evaluate the variability.

In an actual test, the difference between the maximum value and the minimum value is small when there is no residual film as shown in the left waveform in FIG. 7, and the difference between the maximum value and the minimum value is small when there is a residual film as shown in the right waveform in FIG. In order to form a large sine wave, for example, when there is no residual film (at the time of complete peeling), the real-time calculated dispersion value remains in the range of 5 to 10, and when there is a remaining film, the real-time calculated dispersion value is 80 to 100 or more. It turns out that it will rise sharply to the level of.

It was found that in such a method, even if the material of the film or the material of the substrate, that is, the specifications of the product to be monitored change, the difference phenomenon of the dispersion value is maintained when the film is present and the control unit can make a clear judgment. .. This is because the average value of the light intensity when there is no residual film (at the time of complete peeling) or the average value of the light intensity when there is a residual film (T2 period) differs depending on the material of the film substrate, but when the film is present. This is because the phenomenon of a rapid increase in the dispersion value due to the formation of a sine wave still exists.

Alternatively, the control unit has a fixed period to evaluate the variability, the average value between T2 = T1 × (0.25 to 5) seconds, the difference value between the maximum value and the minimum value (maximum value-minimum value), or , Maximum and minimum difference values (maximum value-minimum value) and mean value relative ratio, maximum value-mean value, mean value-minimum value, variance, standard deviation, etc. can be used in the variability evaluation index. ..

For example, the rotation period (T1) of the optical filter is set to 20 msec, the sampling period (Ts) for the light intensity value is set to 2 msec, and the variance is obtained three times continuously (for 60 msec) in units of 20 msec, and one of them is dispersed. The value (V_real) can be used in the judgment material.

The rotation period (T1) of the optical filter is 60 msec, the sampling period (Ts) is 2 msec, and the variance is obtained three times continuously (for 60 msec) in units of 20 msec, and one of them (V_real) is used as the judgment material. You can also do it.

<Method>
FIG. 5 is a flow chart of a monitoring method for peeling off the semiconductor substrate protective film of the present invention. As shown in FIG. 5, the monitoring method for peeling off the semiconductor substrate protective film of the present invention includes an optical filter preparation step (S100), a light irradiation step (S200), an optical filter rotation step (S300), and a reflected light sensing step (S300). It includes S400) and a stage of determining whether the film remains (S500).

As shown in the drawing, in the optical filter preparation stage (S100), it has other light transmission characteristics for isotropic substances (light receiving blocking) and anisotropic substances (partially passing light receiving and periodic light receiving blocking). Prepare optical filter means. In the light irradiation step (S200), the light emitting means 10 irradiates the light toward the substrate (T, subject) in the positive direction.

In the optical filter rotation step (S300), the rotating means (motor) 70 rotates the optical filter means in a state where the optical filter means is positioned between the light emitting means 10 and the substrate (T, subject). In the reflected light sensing stage (S400), the light receiving sensor 50 receives the reflected light reflected by the substrate (T, subject) and generates an electric signal with respect to the intensity of the light.

At the stage of determining whether the film remains (S500), the control unit 60 determines whether the film remains on the surface of the substrate (T) to be inspected (film peeling) based on the electrical signal regarding the light transmitted from the light receiving sensor 50. to decide.

Here, as in the first embodiment of FIG. 1, the optical filter means is a first optical filter means in which a first polarizing element 20 and a second polarizing element 30 having orthogonality to the first polarizing element 20 form a set. May be. Otherwise, as shown in part of FIG. 11, the polarizer 320 and the quarter wave plate 330 can be a pair of second optical filter means.

Here, the control unit 60 sets a variability reference value (V_ref) of the light intensity transmitted from the light receiving sensor 50 when there is no residual film, and determines the light intensity (amplitude) calculated in real time. When the variability measurement value (V_real) is compared with the variability reference value (V_ref) and the difference or ratio between the variability measurement value (V_real) and the variability reference value (V_ref) is larger than a certain value, the film remains. , Judge.

<Second Example>
FIG. 9 is a configuration diagram of a monitoring device for peeling off the semiconductor substrate protective film according to the second embodiment of the present invention, and FIGS. 10 (a and b) are drawings for explaining the polarization blocking effect according to the second embodiment of the present invention. FIG. 11 is a configuration diagram of a monitoring device for peeling off a protective film for a semiconductor substrate according to a second embodiment of the present invention (only a partial configuration is applied).

As shown in FIGS. 9 to 11, the monitoring device for peeling off the protective film for semiconductor substrates according to the second embodiment of the present invention is the first light (unpolarized light, unpolarized light) in the monitoring device for peeling off the protective film for semiconductor substrates. A polarizer 320 that converts the light of the light emitting means 310 that causes L1) to emit light forward and the light source 310 that is located so as to be separated in front of the light emitting means 310 and that advances in the forward direction into second-line polarized light (L2). And a 1/4 λ wave plate (Quarter wave plate) that is located adjacent to the front of the polarizer 320 and converts the second-line polarized light (L2) passing in the positive direction into circularly light (L3) or elliptically polarized light. ) Includes 330.

Further, the monitoring device for peeling off the protective film for a semiconductor substrate according to the second embodiment of the present invention hits the surface of the PCB substrate (T), which is the object of determining whether the film adheres, and is reflected, and then the 1/4 λ wave plate 330. Light calculated using a light receiving sensor 350 that receives light that has passed through the polarizer 320 in the opposite direction and generates an electric signal related to the light, and an electric signal related to the light transmitted from the light receiving sensor 350. It is characterized by further including a control unit 360 for determining whether or not a film adheres to the surface of the PCB substrate to be inspected (whether or not the film is peeled off) by using the strength value (V_1) of.

In the semiconductor substrate protective film peeling monitoring device according to the second embodiment of the present invention, when at least one or all of the polarizer 320 or the 1/4 λ wave plate 330 is viewed with reference to the substrate (T) to be inspected. Rotate (similar to the previous first embodiment in this respect). The control unit 360 evaluates the periodic variability of the light intensity (amplitude) generated due to the rotational motion when the film remains, or the fluctuation characteristic of the light intensity value, and determines whether the film remains.

Although the present invention has been described in connection with the preferred examples mentioned above, the scope of the invention is not limited to such examples, the scope of the invention is determined by the following claims. It will include various modifications and modifications that fall within the same scope of the present invention.

The drawings code described in the claims below is merely for the purpose of assisting the understanding of the invention, and the scope of rights is defined by the drawing code described while clarifying that it does not affect the interpretation of the scope of rights. It should not be narrowly interpreted.

10 Light emitting means 20 1st polarizer 30 2nd polarizer 50 Light receiving sensor 60 Control unit 70 Rotating means 310 Light emitting means 320 Polarizer 330 1 / 4λ Wave plate 340 Optical lens 350 Light receiving sensor 360 Control unit

Claims (10)

In monitoring equipment such as peeling of protective film for semiconductor substrates
A light emitting means 10 that irradiates light (F1) in a positive direction toward a substrate (T, subject), and
Located in front of the light emitting means 10 (between the light emitting means and the substrate), the light (F1) generated by the light emitting means 10 is converted into linearly polarized light (F2) in the direction of the substrate (subject). The first polarizer 20 to be incident on the
2.
A light receiving sensor 50 that receives light that has passed through the second polarizing element 30 and generates an electrical signal related to the light.
A control unit 60 that determines whether or not the film on the surface of the substrate (T) remains (whether or not the film is peeled off) based on the electrical signal or the intensity value of the light transmitted from the light receiving sensor 50.
Including
A monitoring device for peeling a protective film for a semiconductor substrate, wherein the second polarizing element 30 is configured to be located between the substrate (T) and the light receiving sensor 50. 2. Monitoring device. When the film remains, the control unit 60 of the film is based on the degree of periodic variation in the intensity (amplitude) of light generated due to the rotational movement of the first polarizer 20 or the second polarizer 30. The monitoring device for peeling off a protective film for a semiconductor substrate according to claim 2, wherein the residual condition is determined. The control unit 60
The measured variability of light intensity (V_real) generated during the fixed time interval (T1) measured in real time,
Compared with the light intensity variability reference values (V_ref, current value, average value, maximum value, minimum value) measured in advance in the region where there is no residual film (film complete peeling region),
The protective film for a semiconductor substrate according to claim 1, wherein when the measured variability value (V_real) is larger than a certain value or more than the reference value of variability (V_ref), it is determined that the film remains in the inspection region. A monitoring device for peeling. The monitoring device for peeling off a protective film for a semiconductor substrate according to claim 1, wherein the light emitting means 10 is an LED, and a condensing lens 15 is further provided in front of the light emitting means 10. In monitoring equipment such as peeling of protective film for semiconductor substrates
A light emitting means 310 that causes the first light (unpolarized light, L1) to emit light forward, and
A polarizer 320 that is positioned so as to be separated in front of the light emitting means 310 and converts the light of the light source 310 that advances in the positive direction into second-line polarized light (L2).
A 1 / 4λ wave plate 330 that is located in contact with the front of the polarizer 320 and converts the second-line polarized light (L2) that passes in the positive direction into circularly light (L3) or elliptically polarized light.
Electricity related to light is received by receiving light that has passed through the 1 / 4λ wave plate 330 and the polarizer 320 in the opposite direction after being reflected by hitting the surface of the PCB substrate (T), which is the object of determining whether the film adheres. A light receiving sensor 350 that generates a target signal and
Using the light intensity value (V_1) calculated using the electrical signal related to the light transmitted from the light receiving sensor 350, the adhesion of the film on the surface of the PCB substrate to be inspected (film peeling) is determined. Control unit 360 to judge and
A monitoring device for peeling off a protective film for a semiconductor substrate, which is characterized by including. At least one of the polarizer 320 or the 1 / 4λ wave plate 130 rotates when the PCB substrate (T) to be inspected is viewed as a reference.
The control unit 360 evaluates the periodic variability of the light intensity (amplitude) generated due to the rotational motion when the film remains, or the fluctuation characteristic of the light intensity value to determine whether the film remains. The monitoring device for peeling off the protective film for a semiconductor substrate according to claim 6, wherein the protective film is peeled off. Optical filter preparation stage for preparing an optical filter means containing a polarizer, which has other light transmission characteristics for isotropic substances (light receiving blocking) and anisotropic substances (partially passing light receiving and periodic light receiving blocking). (S100) and
A light irradiation step (S200) in which the light emitting means 10 irradiates light toward the substrate (T, subject) in the positive direction, and
An optical filter rotation step (S300) in which the rotating means (motor) 70 rotates the optical filter means while the optical filter means is positioned between the light emitting means 10 and the substrate (T, subject).
A reflected light sensing step (S400) in which the light receiving sensor 50 receives the reflected light reflected by the substrate (T, subject) and generates an electric signal with respect to the intensity of the light.
The control unit 60 determines whether the film on the surface of the substrate (T) to be inspected remains (film peeling) based on the electrical signal for the light intensity transmitted from the light receiving sensor 50. Judgment stage (S500) and
A method for monitoring the peeling of a semiconductor substrate protective film, which comprises. The optical filter means
It is the first optical filter means in which the first polarizing element 20 and the second polarizing element 30 having an orthogonality with the first polarizing element 20 form a set, or the polarizer 320 and the 1/4 λ wave plate 330 form a set. The monitoring method for peeling off a protective film for a semiconductor substrate according to claim 8, wherein the second optical filter means is used. The control unit 60 sets a variability reference value (V_ref) of the intensity of light transmitted from the light receiving sensor 50 when there is no residual film.
Comparing the variability measurement value (V_real) of the light intensity (amplitude) calculated in real time with the variability reference value (V_ref),
The semiconductor according to claim 8 or 9, wherein when the difference or ratio between the measured variability value (V_real) and the reference value of variability (V_ref) is larger than a certain value, it is determined that the film remains. How to monitor the peeling of the protective film for the substrate.

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