JP2001124524A - Apparatus and method of measuring film thickness - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus and a method of measuring the film thickness which is capable of accurately measuring films having various thicknesses. SOLUTION: This film thickness measuring apparatus comprises a reflected light information collector 3 for collecting reflected light information DI from a film 2 formed on a sample 1 with a light irradiating the film 2 and a film thickness calculator 4 for calculating the film thickness, based on the reflected light information DI collected from the reflected light information collector 3. In the film thickness measuring method, a film thickness calculating wavelength range calculator 4c in the film thickness calculator 4 calculates the film thickness calculating wavelength region, from the relation between an inter-peak-wavelength distance calculated by an inter-peak-wavelength distance calculator 4b and the wavelength resolution of the reflected light information DI, i.e., the wavelength resolution of a spectrophotometer 7, hence if films having various thicknesses are measured, an optimum film thickness calculating wavelength region is always calculated and the film thickness can be measured accurately.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film thickness measuring device and a film thickness measuring method for measuring a film thickness.

[0002]

2. Description of the Related Art Conventionally, as a method of measuring a film thickness of a film, a contact type film thickness measuring method such as a step gauge and an eddy current type film thickness meter,
A non-contact type film thickness measurement method using a color difference method, an interference method, a light absorption method or the like has been devised.

In particular, film thickness measurement using an interference method can be performed relatively easily and in a short time. For example, a transparent film such as an undercoat layer or a charge transport layer in an electrophotographic photosensitive member can be measured. Often used for measuring film thickness.

The principle of this optical interference method is as follows.
FIG. 6 is a schematic diagram when light is incident on a transparent thin film having a film thickness d and a relative refractive index n of the film formed on the sample. When light is incident on such a film and the spectrum of the reflected light is collected, the spectrum has, for example, a waveform as shown in FIG.
Two adjacent light-emission maximum wavelengths (hereinafter referred to as “PEAK wavelengths”) or 2 obtained with such a waveform.
The wavelength at which two adjacent light quantities have a minimum (hereinafter referred to as “BOTT
This is a method of obtaining the film thickness by obtaining λ ₁ and λ ₂ as “OM wavelengths”) and substituting them into the following formula (1), which is a film thickness calculation formula.

Equation (1) d = λ ₁ λ ₂ / 2n (λ ₁ -λ ₂ )

FIG. 7 shows two adjacent PEAKs.
In this example, the film thickness is calculated from the wavelength. However, depending on the waveform, two adjacent BOTTOM wavelengths may be used.

[0007]

On the other hand, in film thickness measurement, there are cases where films of various thicknesses are measured with the same device, and a typical example is film thickness measurement on an electrophotographic photosensitive member. . Coating films of an electrophotographic photoreceptor have various thicknesses depending on the purpose of use. It varies up to about 40 μm. Regarding the film thickness tolerance in these film forming processes,
In general, a predetermined range is determined and managed. For example, in the case of a charge transport layer, a range of about 4 to 5 μm is provided at the maximum.

When measuring films of various thicknesses with the same device, in the optical interference method, the PEAK wavelength is detected from the interference waveform of reflected light collected by a spectrophotometer to determine the film thickness. And PE due to the variation of the film thickness to be measured
The distance between AK wavelengths also varies. For example, as is clear from the above equation (1), the distance between the PEAK wavelengths decreases as the film thickness increases. On the other hand, the wavelength resolution in a spectrophotometer is fixed for each device used, and as the film thickness increases, the ratio of the distance between PEAK wavelengths to the wavelength resolution decreases.

That is, since the spectrophotometer for collecting the interference waveform of the reflected light has a fixed wavelength resolution, a decrease in the measurement accuracy due to the increase in the thickness of the film is unavoidable, and within a range of the film thickness tolerance in the same device. This causes a problem that the measurement accuracy on the thick film side is insufficient.

The present invention has been made in view of the above problems, and provides a film thickness measuring apparatus and a film thickness measuring method capable of accurately measuring a film having various thicknesses. The purpose is to:

[0011]

A film thickness measuring device according to claim 1 is a film thickness measuring device for measuring a film thickness of a sample on which a film is formed, and is obtained by irradiating the sample with light. Interference characteristic detecting means capable of detecting an interference characteristic based on reflected light information obtained, a peak wavelength is calculated from an interference characteristic detected by the interference characteristic detecting means, and a peak wavelength distance calculation capable of calculating a peak wavelength distance. Means and a wavelength resolution of reflected light information in the interference characteristic detecting means, and a film thickness calculating wavelength area calculation capable of calculating a film thickness calculating wavelength area from the relationship between the peak wavelength distances calculated by the peak wavelength distance calculating means. Means, and a film thickness calculating means for calculating a film thickness from the distance between peak wavelengths in the film thickness calculating wavelength region calculated by the film thickness calculating wavelength region calculating means.

Therefore, in the film thickness measuring device according to the first aspect, the wavelength resolution of the reflected light information in the interference characteristic detecting means and the peak wavelength distance calculating means are used by the film thickness calculating wavelength region calculating means. To calculate the film thickness calculation wavelength region from the calculated relationship between the peak wavelengths, even when measuring films of various thicknesses, the optimum film thickness calculation wavelength region is always calculated, and the film thickness is accurately calculated. Can be measured.

According to a second aspect of the present invention, in the thickness measuring apparatus according to the first aspect, the formed sample is an electrophotographic photosensitive member having at least a photosensitive layer on a conductive substrate. It is characterized by the following.

Therefore, in the film thickness measuring apparatus according to the second aspect, even if the film thickness of an electrophotographic photosensitive member having films of various thicknesses is measured depending on the purpose of use, the film thickness can be measured accurately. it can.

According to a third aspect of the present invention, there is provided a film thickness measuring method for measuring a film thickness of a sample on which a film is formed,
An interference characteristic detection step of detecting an interference characteristic based on reflected light information obtained by irradiating the sample with light, a peak wavelength is determined from the interference characteristics detected in the interference characteristic detection step, and a distance between peak wavelengths is determined. A wavelength region for calculating a film thickness is calculated from a relationship between a wavelength resolution of reflected light information in the peak wavelength distance calculating step to be calculated and the interference characteristic detecting step, and a peak wavelength distance calculated in the peak wavelength distance calculating step. A film thickness calculating wavelength region calculating step; and a film thickness calculating step of calculating a film thickness from a distance between peak wavelengths in the film thickness calculating wavelength region calculated in the film thickness calculating wavelength region calculating step. .

Therefore, in the film thickness measuring method according to the third aspect, in the film thickness calculating wavelength region calculating step, the wavelength resolution of reflected light information in the interference characteristic detecting step and the peak wavelength distance calculating step are calculated. To calculate the film thickness calculation wavelength region from the calculated relationship between the peak wavelengths, even when measuring films of various thicknesses, the optimum film thickness calculation wavelength region is always calculated, and the film thickness is accurately calculated. Can be measured.

According to a fourth aspect of the present invention, in the method of measuring a film thickness, the sample on which the film is formed is an electrophotographic photosensitive member having at least a photosensitive layer on a conductive substrate.

Therefore, according to the film thickness measuring method of the present invention, the film thickness can be measured accurately even if the film thickness of the electrophotographic photosensitive member having various thicknesses is measured depending on the purpose of use. it can.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a film thickness measuring apparatus and method according to the present invention will be further described with reference to the drawings. First Embodiment Hereinafter, a film thickness measuring apparatus according to a first embodiment will be described with reference to FIG.
This will be described with reference to FIG. The method for measuring the film thickness will be described together with the apparatus.

FIG. 1 is a schematic configuration diagram showing a film thickness measuring apparatus according to a first embodiment of the present invention. A film thickness measuring device 10 shown in FIG. 1 irradiates a film 2 formed on a sample 1 with light, and collects reflected light information D _1, and a reflected light information collecting unit 3. 3 on the basis of the collected reflected light information D ₁ from the and a thickness calculating unit 4 for calculating the film thickness.
Although not shown, the film thickness calculation unit 4 may be connected to a display device that displays the calculated film thickness, or a coating device that controls the formation of a coating film based on the calculated film thickness.

The reflected light information collecting section 3 includes a light source 5, a probe 6, and a spectrophotometer 7. Light source 5 and probe 6
Are connected via an optical fiber 8. Probe 6
And the spectrophotometer 7 are connected via an optical fiber 9. As the light source 5, a general light source such as halogen and xenon can be used. Further, the spectrophotometer 7 forms an image of the reflected light L _out and reflects the reflected light information D ₁ , that is, the reflected light L _out.
The spectrum of is collected. Here, the wavelength resolution of the reflected light information D ₁ indicates the wavelength resolution of the spectrophotometer 7. The reflected light information collecting unit 3 is not limited to such a configuration, and may be configured by a conventionally known optical system or the like.

In the reflected light information collecting section 3, light emitted from the light source 5 is transmitted through the optical fiber 8 to the probe 6.
The film 2 from being irradiated as an incident light L _in. Then, the reflected light L _out reflected from the film 2 is received by the probe 6, forms an image of the reflected light L _out by the spectrophotometer 7 via the optical fiber 9, and collects reflected light information D ₁ . . The collected reflected light information D ₁ is input to the film thickness calculator 4.

The film thickness calculating section 4 includes an interference characteristic detecting section 4a,
It includes a peak wavelength-to-peak wavelength calculation unit 4b, a film thickness calculation wavelength region calculation unit 4c, and a film thickness calculation unit 4d. Film thickness calculator 4
May be configured as software using a computer system, or may be configured as a dedicated electric circuit.

The interference characteristic detection unit 4a is for detecting an interference characteristic based on the inputted reflected light information D _1. The inter-peak wavelength calculating section 4b calculates the inter-peak wavelength distance by obtaining the peak wavelength from the interference characteristics detected by the interference characteristic detecting section 4a. Film thickness calculation wavelength region calculation unit 4
c is the wavelength resolution of the reflected light information D _1, i.e. the spectrophotometer 7
The wavelength region for calculating the film thickness is calculated from the relationship between the wavelength resolution and the distance between the peak wavelengths calculated by the distance between peak wavelengths calculating unit 4b. The film thickness calculator 4d calculates the film thickness from the distance between peak wavelengths in the film thickness calculation wavelength region calculated by the film thickness calculation wavelength region calculator 4c.

The configuration of the film thickness measuring device 10 has been described above. Next, the specific operation of the film thickness measuring device 10 will be described with reference to FIG. FIG. 2 is a flowchart showing a specific operation of the film thickness measuring apparatus according to the first embodiment of the present invention.

The reflected light information D ₁ collected by the reflected light information collecting unit 3 is input to the film thickness calculating unit 4. The incident light L _in is irradiated to the film 2, after being reflected by the sample surface and passes through the inner membrane 2, and the reflected light L _out to reach the probe 6 again, film 2
Reflected light L _out reflected by the surface and reaching the probe 6 again
Divided into At this time, the two reflected lights L _out have 2nd
(N is the relative refractive index of the film, and d is the film thickness). The reflected light L _out reflected on the sample surface is 180 ° out of phase when reflected. Therefore, the amount of reflected light becomes maximum in the following equation (2), and the amount of reflected light becomes minimum in the following equation (3). Therefore,
The reflected light information D ₁ , that is, the spectrum of the reflected light, satisfies the following equations (2) and (3). The following equation (2)
In (3) and (3), n is the relative refractive index of the film, d is the film thickness, λ is the wavelength of the reflected light, and m is the interference order.

Equation (2) 2nd = mλ (m = 1, 2, 3,...) Equation (3) 2nd = (2m−1) λ / 2 (m = 1, 2, 3,...)

Based on the reflected light information D ₁ input to the film thickness calculating unit 4, the interference characteristic detecting unit 4 a sorts the wavelength and the reflected light amount as a two-dimensional data array, and then performs a waveform obtained by moving average processing. , And the interference characteristics are detected (step s11). FIG. 3 shows an example of the waveform of the interference characteristic obtained by this processing.

Based on the detected interference characteristics, the wavelength between peak wavelengths is calculated by the peak wavelength distance calculation section 4b, and the distance between peak wavelengths adjacent to each other is calculated.
(X) is calculated (step s12). In the waveform of the interference characteristic shown in FIG. 3, since each wavelength of w (1) to w (n) is a peak point, the distance a (x) between adjacent peak wavelengths is calculated by the following equation (4). .

Equation (4) a (x) = w (x + 1) −w (x)

Based on the distance a (x) between the peak wavelengths obtained by the film thickness calculation wavelength region calculation unit 4c, the distance a (x) between the peak wavelengths and the wavelength resolution Δw of the spectrophotometer 7 are calculated. The ratio R (x) is calculated, and a film thickness calculation wavelength region, that is, a film thickness calculation start wavelength w (s) to a film thickness calculation end wavelength w (e) is calculated (step s13).

The distance a (x) between the peak wavelengths and the spectrophotometer 7
The ratio R (x) with respect to the wavelength resolution Δw is calculated by the following equation (5).

Equation (5) R (x) = a (x) / Δw

The film thickness calculation start wavelength w (s) is calculated by the ratio R
Since the accuracy of the film thickness calculation depends on the size of (x), the calculation is performed so as to satisfy the following expression (6). Since the wavelength peak inter-wavelength distance a (x) increases as it goes to the longer wavelength side, if the ratio R (x) is too small, ie,
If the wavelength resolution Δw is insufficient for the distance a (x) between adjacent peak wavelengths to be detected, the measurement accuracy will be poor. On the other hand, if the value of the ratio R (x) is too large, the number of combinations of adjacent peak wavelengths in the limited wavelength resolution Δw is reduced, which also causes deterioration in measurement accuracy. From this, it is desired that the value of R (x) be an appropriate size, and this value is stored in advance as the optimal wavelength resolution ratio r (the value of r is preferably in the case of an electrophotographic photosensitive member. 5 or more, more preferably 10
As described above, when the value exceeds C / 2 (where C indicates the number of channels of the detection element of the spectrophotometer 7), only one set of adjacent peak wavelengths exists, and the measurement accuracy deteriorates. In some cases, this is not preferable. ), And calculate the film thickness calculation start wavelength w (s).

Equation (6) R (x) ≧ r

The film thickness calculation end wavelength w (e) is calculated by the following equation (7) based on the film thickness calculation start wavelength w (s). Here, W indicates a wavelength range width. This wavelength range width is a wavelength range width for detecting one or a plurality of wavelength peak wavelength distances a (x) used for calculating the film thickness, and is a predetermined constant (the value of W is an electron In the case of a photographic photosensitive member, the number is preferably 100 to 400.).

Equation (7) w (e) = w (s) + W

Thus, the wavelength region for calculating the film thickness is calculated.

The film thickness calculating unit 4d calculates the film thickness d (x) by the following equation (8) based on the peak wavelength in the film thickness calculating wavelength region obtained by the film thickness calculating wavelength region calculating unit 4c. After calculating and calculating the film thickness d (x), the obtained film thickness d
The average value of (x) is calculated as a film thickness value (step s1).
4).

Equation (8) d (x) = {w (x + 1) w (x)} / {2n} w (x + 1) −w (x)} (x = s to e)

As described above, the film thickness measuring device and method according to the first embodiment are provided by the film thickness calculating wavelength region calculating section 4c.
From the relationship between the wavelength resolution of the spectrophotometer 7 and the peak-to-peak wavelength distance calculated by the peak-to-peak wavelength calculation unit 4b, films of various thicknesses were measured to calculate a film thickness calculation wavelength region. However, the optimum film thickness calculation wavelength region is always calculated, and the film thickness can be accurately measured.

Second Embodiment A film thickness measuring apparatus according to a second embodiment will be described below with reference to FIGS. The method for measuring the film thickness will be described together with the apparatus.

FIG. 4 is a schematic configuration diagram showing a film thickness measuring apparatus according to the first embodiment of the present invention. The film thickness measuring device 20 shown in FIG. 4 has the same configuration as the film thickness measuring device 10 shown in FIG. 1 except that the film thickness calculating unit 4 further includes a relative refractive index storage unit 4e. The relative refractive index storage unit 4e includes a film thickness calculation unit 4
When calculating the film thickness from the distance between peak wavelengths in the film thickness calculation wavelength region calculated by the film thickness calculation wavelength region calculation unit 4c in d, the relative refractive index to be used is calculated based on the wavelength. Further, the film thickness calculation unit 4d calculates the distance between the peak wavelengths in the film thickness calculation wavelength region calculated by the film thickness calculation wavelength region calculation unit 4c and the relative refractive index calculated by the relative refractive index storage unit 4e. This is for calculating the film thickness. The description of the same configuration as that of the film thickness measuring apparatus 10 shown in FIG. 1 is omitted.

The configuration of the film thickness measuring device 20 has been described above. Next, the specific operation of the film thickness measuring device 20 will be described with reference to FIG. FIG. 5 is a flowchart showing a specific operation of the film thickness measuring apparatus according to the second embodiment of the present invention. Steps s21 to s23 are the same as steps s11 to s13 in FIG.

The film thickness calculation unit 4d calculates the peak wavelength in the film thickness calculation wavelength region obtained by the film thickness calculation wavelength region calculation unit 4c and the relative refractive index n obtained by the film storage unit 4e.
Based on (x), the film thickness d (x) is calculated. With this, the film thickness d (x) is calculated, and the average value of the obtained film thickness d (x) is calculated as the film thickness value. (Step s24).

In the relative refractive index storage section 4e, the relative refractive index n
(X) is calculated by the following equation (9). Here, the function f ({w (x + 1) + w (x)} / 2) is a function representing the relationship between the wavelength and the relative refractive index. In the film thickness calculation wavelength region obtained by the film thickness calculation wavelength region calculation section 4c, the relationship between the wavelength and the relative refractive index is obtained in advance, and the relative refractive index used is changed according to the wavelength at the time of film thickness calculation.

Equation (9) n (x) = f ({w (x + 1) + w (x)} / 2)

The film thickness d (x) is calculated by the following equation (10) based on the peak wavelength in the film thickness calculation wavelength region region and the relative refractive index n (x) obtained by the relative refractive index storage unit 4e. Is calculated.

Equation (10) d (x) = {w (x + 1) w (x)} / {2n (x) w (x + 1) −w (x)} (x = s to e)

As described above, in the film thickness measuring apparatus and method according to the second embodiment, in the relative refractive index storage unit 4e, within the film thickness calculation wavelength region obtained by the film thickness calculation wavelength region calculation unit 4c, Since the relationship between the wavelength and the relative refractive index is determined in advance, and the relative refractive index to be used is changed according to the wavelength at the time of calculating the film thickness in the film thickness calculating unit 4d, the relative refractive index of the target film to be measured changes according to the wavelength. Even in this case, the film thickness can be measured more accurately.

The configuration and measurement operation of the film thickness measuring apparatus and method according to the first and second embodiments have been described above, but the present invention is not limited to this embodiment.

The film thickness measuring apparatus and method of the present invention are preferably adapted to the film thickness measurement of an electrophotographic photosensitive member. Since the electrophotographic photosensitive member has various thicknesses depending on the purpose of use, the film thickness measuring apparatus and method of the present invention, which can accurately measure the film thickness, are particularly effective.

In the film thickness measuring apparatus and method of the present invention, the electrophotographic photoreceptor may be one having at least a photosensitive layer on a conductive substrate. A layer in which a layer, a charge generation layer, and a charge transport layer are sequentially formed. Conventionally known materials are used for the conductive substrate and the material of each layer constituting the electrophotographic photosensitive member.

In the film thickness measuring apparatus and method of the present invention, when the coating film such as the undercoat layer and the charge transport layer of the electrophotographic photosensitive member is applied, the film thickness measuring apparatus and the method of the present invention sequentially It is preferable to measure the film thickness and feed back the measurement result to control the film thickness. In this case, for example, the film thickness can be controlled by the film thickness measurement device according to the first or second embodiment and the measurement result of the film thickness calculated by the film thickness calculation unit in the film thickness measurement device. It comprises a conventionally known coating device.

In the film thickness measuring apparatus and method according to the present invention, a coating speed and the like can be mentioned as a factor for controlling the film thickness in forming an electrophotographic photosensitive member by coating. For example, when the coating in the dip coating method is taken as an example, the relationship between the coating speed V (here, the coating speed is the speed at which the substrate is immersed in the coating liquid and pulled up) and the film thickness d is expressed by the following equation. As shown in (11), it can be seen that the film thickness d is proportional to the coating speed V to the 0.5th power under the conditions of constant viscosity η and coating liquid density ρ. In the following equation (11), g is the gravitational acceleration, and K is a constant (K
Is a value unique to the material or the like. ), The film thickness d can be controlled by changing other conditions (coating speed V, viscosity η, coating liquid density ρ).

Equation (11) d = K (Vη / ρg) ^0.5

In the film thickness measuring apparatus and method of the present invention, when the coating film such as the undercoat layer and the charge transport layer of the electrophotographic photosensitive member is applied, the film thickness measuring apparatus and the method of the present invention sequentially By measuring the film thickness and feeding back the measurement result to control the film thickness, the film thickness of the electrophotographic photoreceptor can be accurately evaluated in the state of the intermediate product, and fluctuations in the process can be detected quickly. In addition, it is possible to stabilize the process and prevent a large outflow of a defective film thickness product to a subsequent process.

[0058]

EXAMPLES The present invention will be specifically described with reference to examples relating to the measurement of the film thickness of an electrophotographic photosensitive member, but the present invention is not limited to these examples.

(Embodiment) An immersion coating apparatus having the film thickness measuring device shown in FIG. 2 and capable of controlling the film thickness based on the film thickness measurement result calculated by the film thickness calculating section 4 in the film thickness measuring device. When a charge transport layer was formed on a conductive substrate and six electrophotographic photosensitive members (thicknesses having six different thicknesses) were prepared, the measurement repeatability σ of the thickness was 0.07 μm.
Good result was obtained. From the above, it can be seen that the film thickness could be measured accurately. The electrophotographic photoreceptor was prepared so that the charge transport layer had six different thicknesses, and the coating speed was determined as a factor for controlling the thickness. Note that the wavelength range width of the spectrophotometer 7 is 300 to 1100 nm, and the wavelength resolution Δw is 1.
It was 56 nm. The film thickness calculation wavelength region is selected so that the wavelength resolution ratio r in the film thickness calculation wavelength region calculation section 4c takes a value of 10 or more, and the wavelength range width w for detecting the peak wavelength distance a (x) is 300 nm. .

The film thickness measurement repeatability σ is calculated by calculating the standard deviation from the results of the film thickness measurement repeated five times for each of the six electrophotographic photosensitive members having different film thicknesses at each stage, and calculating the six standard values. The representative value was obtained from the deviation by a statistical method.

(Comparative Example) A charge transport layer was formed on a conductive substrate using the production method described in Japanese Patent Application Laid-Open No. 4-336540 (coating apparatus shown in FIG. 2). As a result, the measurement repeatability σ was 0.25 μm, and the measurement accuracy was insufficient.

As is apparent from the above description, according to the present invention, the film thickness calculation wavelength region calculating means calculates the wavelength resolution in the interference characteristic detecting means and the wavelength resolution in the peak wavelength distance calculating means. In order to calculate the film thickness calculation wavelength region from the calculated peak wavelength distance, even when measuring films of various thicknesses, the optimum film thickness calculation wavelength region is always calculated and the film thickness is accurately measured. can do.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a film thickness measuring device according to a first embodiment.

FIG. 2 is a flowchart showing an operation of the film thickness measuring apparatus according to the first embodiment.

FIG. 3 is an example of a waveform of an interference characteristic in an operation of the film thickness measuring apparatus according to the first embodiment.

FIG. 4 is a schematic configuration diagram illustrating a film thickness measuring apparatus according to a second embodiment.

FIG. 5 is a flowchart showing an operation of the film thickness measuring apparatus according to the second embodiment.

FIG. 6 is a schematic diagram when light is incident on a transparent thin film sample having a thickness d and a refractive index n.

FIG. 7 is an example of a spectrum of reflected light when light is incident on a transparent thin film sample having a thickness d and a refractive index n.

[Explanation of symbols]

Reference Signs List 1 sample 2 film 3 reflected light information collecting section 4 film thickness calculating section 4a interference characteristic detecting section 4b peak wavelength separation calculating section 4c film thickness calculating wavelength region calculating section 4e relative refractive index storage section 4d film thickness calculating section 5 light source 6 probe 7 Spectrophotometer 8 Optical fiber 9 Optical fiber 10 Film thickness measuring device 20 Film thickness measuring device D ₁ Reflected light information L _in incident light L _out reflected light

Continued on the front page F term (reference) 2F065 AA30 CC31 FF01 FF51 GG02 GG03 LL02 NN20 PP21 QQ15 QQ25 QQ29 QQ42 2H068 EA41 EA43

Claims (4)

[Claims] 1. A film thickness measuring device for measuring a film thickness of a sample on which a film is formed, wherein an interference characteristic is detected based on reflected light information obtained by irradiating the sample with light. Means, a peak wavelength is determined from the interference characteristics detected by the interference characteristic detection means, the wavelength resolution of reflected light information in the peak wavelength distance calculation means and the interference characteristic detection means capable of calculating the peak wavelength distance, and A film thickness calculating wavelength region calculating means capable of calculating a film thickness calculating wavelength region from the relationship between the peak wavelength distances calculated by the peak wavelength distance calculating device; and a film thickness calculating wavelength region calculating device. A film thickness calculating means for calculating a film thickness from a distance between peak wavelengths in a film thickness calculating wavelength region. 2. The film thickness measuring apparatus according to claim 1, wherein the sample on which the film is formed is an electrophotographic photosensitive member having at least a photosensitive layer on a conductive substrate. 3. A method for measuring a film thickness of a sample having a film formed thereon, the method comprising: detecting an interference characteristic based on reflected light information obtained by irradiating the sample with light. And determining a peak wavelength from the interference characteristics detected in the interference characteristic detecting step, a wavelength resolution of reflected light information in the peak wavelength distance calculating step and the interference characteristic detecting step of calculating a peak wavelength distance, and the peak A film thickness calculation wavelength region calculation step of calculating a film thickness calculation wavelength region from the relationship between the peak wavelength distances calculated in the wavelength distance calculation step, and a film thickness calculation calculated in the film thickness calculation wavelength region calculation step A film thickness calculation step of calculating a film thickness from a distance between peak wavelengths in a wavelength region. 4. The method according to claim 3, wherein the sample on which the film is formed is an electrophotographic photosensitive member having at least a photosensitive layer on a conductive substrate.