JP2002039720A - Film thickness measuring apparatus, method for obtaining data in the film thickness measuring apparatus, and recording medium which stores program for obtaining data - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a film thickness measuring apparatus which can detect surely film surfaces of plural thin films different in reflectivity, a method for obtaining data in the apparatus, and a recording medium which stores a program for obtaining data. SOLUTION: A specimen 6 in which thin films of plural layers are formed and an objective 5 are moved relatively. The specimen 6 is irradiated with a laser light via the objective 5. The thin film surface is detected from the change of a detected signal of an optical detector 9, corresponding to the reflected light from the thin film of each layer. According to the state of the detected signal of the optical detector 9, the gain and the number of times of integration are set as data obtaining conditions. Data are obtained by executing the adjustment of gain and the number of times of integration set as the conditions for obtaining data, to the detected signal of the optical detector 9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a film thickness measuring device, for example, a film thickness measuring device to which a scanning laser microscope is applied, a data acquisition method by the film thickness measuring device, and a recording medium storing a data acquisition program. About.

[0002]

2. Description of the Related Art Transparent or translucent thin films are sometimes formed on the surface of a substrate such as a semiconductor wafer. If the thickness of these thin films varies, or if foreign matter is mixed in, the product becomes a product. The specified characteristics may not be obtained.

For this reason, conventionally, as a film thickness measuring device for measuring the thickness dimension of a thin film, a substrate (sample) on which a thin film is formed and an objective lens are relatively moved, and the sample is moved to the sample via the objective lens. There is known a scanning laser microscope which irradiates a laser beam, detects reflected light from the surface of a thin film of a sample and the surface of a substrate, and detects the thickness of the thin film from a change in the detection signal.

By the way, there is a sample in which a plurality of thin films are stacked, and when measuring the thickness of the thin film of each layer of such a sample, the sample and the objective lens are moved relatively to each other. The thin film surface of each layer is irradiated with laser light via an objective lens, the reflected light is detected, and the thin film surface of each layer is detected from the peak value of the detection signal.

[0005]

However, if a plurality of thin films have a low reflectance, the S / N of the detection signal peak value on the low reflectance film surface is lower than the darkness of the reflected light. Therefore, the accuracy of film thickness measurement using the peak value is deteriorated. For this reason, it is conceivable to raise the overall detection sensitivity in advance in consideration of such a situation. However, in such a case, the detection signal from the high-reflectance film surface is saturated, and information on the correct film thickness is obtained. Will be difficult to obtain. In other words, in the case where high reflectance and low reflectance are mixed in a plurality of thin films, if the gain is adjusted so that the low reflectance film surface can be detected, the detection signal from the high reflectance film surface will be saturated. Therefore, it is difficult to obtain information on a correct film thickness. Also, if the gain is adjusted so that the detection signal from the film surface with the highest reflectance does not saturate, the peak value of the detection signal from the film surface with a low reflectance may not be detected, and the film surface actually exists. However, there is a problem that a boundary between the thin films cannot be determined, and a detection error or a measurement error occurs.

The present invention has been made in view of the above circumstances, and a film thickness measuring apparatus capable of reliably detecting the film surfaces of a plurality of thin films having different reflectances, a data acquisition method and data in the film thickness measuring apparatus It is an object to provide a recording medium storing a program for acquisition.

[0007]

According to the first aspect of the present invention,
A thin film is formed, and a sample having at least two surfaces to be measured is irradiated with spot light through an objective lens, and while the sample and the objective lens are relatively moved on an optical axis, A film thickness measurement for measuring a thickness of a thin film formed on the sample by detecting reflected light from the sample with a light detection unit and detecting a measurement target surface from a change in a detection output of the light detection unit. In the apparatus, according to the state of the detection output of the light detection means, a data acquisition condition setting means for setting a gain or the number of integrations for the detection output as a data acquisition condition, and the data for the detection output of the light detection means Data acquisition means for executing the gain adjustment or the number of integrations set by the acquisition condition setting means and acquiring data.

According to a second aspect of the present invention, in the first aspect of the present invention, the apparatus further comprises a setting range determining means for determining a setting range of a data acquisition condition from information of the thin film given as a design value in advance. The condition setting means sets, as a data acquisition condition, a gain or an integration count for the detection output from the state of the detection output of the light detection means in the range determined by the setting range determination means.

According to a third aspect of the present invention, a thin film is formed,
While irradiating spot light via an objective lens to a sample having at least two surfaces to be measured, while relatively moving the sample and the objective lens on the optical axis,
A film thickness measurement for measuring a thickness of a thin film formed on the sample by detecting reflected light from the sample with a light detection unit and detecting a measurement target surface from a change in a detection output of the light detection unit. In the data acquisition method in the device, a gain or an integration count for the detection output is set as a data acquisition condition according to a state of a detection output of the light detection unit, and the data acquisition condition is set for a detection output of the light detection unit. The method is characterized in that the gain adjustment or the number of integrations set by the setting means is executed to acquire data.

According to a fourth aspect of the present invention, in the third aspect of the present invention, a setting range of a data acquisition condition is determined from information of the thin film given in advance as a design value, and the light detection is performed in the determined range. It is characterized in that the gain or the number of integrations for the detection output is set as a data acquisition condition from the state of the detection output of the means.

According to a fifth aspect of the present invention, a thin film is formed,
While irradiating spot light via an objective lens to a sample having at least two surfaces to be measured, while relatively moving the sample and the objective lens on the optical axis,
A film thickness measurement for measuring a thickness of a thin film formed on the sample by detecting reflected light from the sample with a light detection unit and detecting a measurement target surface from a change in a detection output of the light detection unit. A recording medium on which a program for acquiring data in an apparatus is recorded, wherein a gain or an integration count for the detection output is set as a data acquisition condition in accordance with a state of a detection output of the light detection means, The data is acquired by executing the gain adjustment or the number of integrations set by the data acquisition condition setting means for the detection output.

According to a sixth aspect of the present invention, in the fifth aspect of the present invention, the recording medium in which the program for acquiring data in the film thickness measuring apparatus is recorded is obtained from the information of the thin film previously given as a design value. A set range of the condition is determined, and in this determined range, a gain or the number of times of integration for the detected output is set as a data acquisition condition based on the state of the detected output of the light detecting means.

As a result, according to the present invention, the detection output of the detecting means for detecting the reflected light from the film surface is subjected to the adjustment of the gain and the number of integrations set as the data acquisition conditions, whereby the detection output is obtained. Can be improved to a level that does not hinder the detection of information on the thin film surface.
The thin film surface can be reliably detected without being affected by the reflectance of the film surface.

Further, since the surface position of the thin film and the setting range of the data acquisition condition can be obtained from the information on the film thickness given as a design value in advance, the data output from the setting of the data acquisition condition to the detection output of the detecting means can be obtained. A series of operations from execution of acquisition conditions to acquisition of data can be automatically performed.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) FIG. 1 shows a schematic configuration of a scanning laser microscope applied to a film thickness measuring apparatus of the present invention.

In this case, the laser light emitted from the laser light source 1 is reflected by the mirror 2, passes through the half mirror 3 and enters the two-dimensional scanning mechanism 14.

The two-dimensional scanning mechanism 14 two-dimensionally scans the laser beam under the control of the control unit 41 of the computer 4.
2 is two-dimensionally scanned over the entire area of the measurement target surface of the sample 6 placed on the sample 2.

The reflected light from the sample 6 passes through the objective lens 5, is reflected by the half mirror 3 via the two-dimensional scanning mechanism 14, and is transmitted through the imaging lens 7 and the pinhole 8 to the photodetector. 9 is detected.

The signal from the photodetector 9 is input to the image input section 42 of the computer 4 by the two-dimensional scanning mechanism 14.
The data is captured in synchronization with the dimensional scanning and stored in the main memory 43 as image data.

The image data stored in the main memory 43 is
The image is displayed on the monitor 10 as a two-dimensional image via the CPU bus 47 and the video card 44.

The image input section 42 has an A / D conversion function for converting an analog signal from the photodetector 9 into a digital signal.

In this case, the light detector 9 includes the objective lens 5
Other than the reflected light of the sample 6 from the focal position of
, The image of the sample 6 can be obtained only from the in-focus position of the objective lens 5.

Under the control of the control unit 41 of the computer 4 utilizing this property, the position of the objective lens 5 by the two-dimensional scanning of the laser beam and the Z-axis moving mechanism 11 in the optical axis direction is set by a predetermined distance (a predetermined interval). ) (Z-axis scanning), and the position (peak position) at which the detection signal (luminance data) of the photodetector 9 becomes maximum is measured on the surface of the sample 6 to be measured (here, the thin film 61). , The boundary surface 62b between the thin film 61 and the thin film 62, the boundary surface 63b between the thin film 62 and the thin film 63, and the boundary surface (substrate surface) 64b between the thin film 63 and the substrate 64 (see FIG. 3). I have to.

In the above-described embodiment, an example has been described in which the objective lens 5 is moved up and down in the optical axis direction. However, the present invention is not limited to this, and the sample 6 is moved in the optical axis direction (Z axis direction). Any configuration may be used as long as the configuration is such that the and the objective lens 5 can relatively move.
For example, a configuration in which the stage 12 is moved up and down may be used.

These series of movements are realized by integrally controlling the control unit 41 and the image input unit 42 of the computer 4.

Also, a screen for controlling the operation of the scanning laser microscope is displayed on the monitor 10 together with the two-dimensional image of the sample 6, and the operator can handle the microscope through this screen. I have.

The above control is performed by the recording medium 46 (magnetic recording medium, hard disk, CD-R) of the computer 4.
OM, etc.).

The control program is stored in the main memory 43 and executed by the CPU 45.

The control program does not need to be recorded on the recording medium 46. For example, the control program is downloaded from a server computer at a remote place via a network (not shown) connected to the computer 4 and executed. You may.

FIG. 2 shows a display example displayed on the screen of the monitor 10 in order to set conditions for obtaining optimum data in advance when recognizing the surface to be measured by such a film thickness measuring apparatus. ing.

In this case, the condition setting area 10 is displayed on the screen.
1 and a setting condition display area 102 are displayed.

In the condition setting area 101, a Z position setting unit 101a for setting a surface to be measured, a gain adjustment unit 101b for obtaining a detection output of an optimal size, and an optimal background brightness are set. Adjustment unit 101 for
c, The same measurement target surface is taken in a plurality of times, and an integration number setting unit 101d for setting the number of times of integrating the same and a condition registration button 101e are displayed.

In the setting condition display area 102, setting items such as a layer number 102a, a surface to be measured (Z position) 102b, an integration (times) 102c, a gain (times) 102d, and an offset (%) 102e are displayed. ing.

Then, the operator uses the display on the monitor 10 to set optimum data acquisition conditions.

Now, as shown in FIG.
It is assumed that the third to third thin films 61, 62, 63 are formed on the substrate 64.

In this state, the operation according to the flowchart shown in FIG. 4 is performed.

First, as step 401, the monitor 10
The condition setting area 101 is displayed at the top, and waits for input from the operator.

The operator operates the Z position setting section 101a to select and enter the layer number of the first thin film 61 of the sample 6.

Next, in step 402, the first thin film 61, which is the first surface to be measured, is focused on the surface 61b of the thin film 61.

In this case, the laser light of the laser light source 1 shown in FIG. 1 is irradiated onto the surface 61b of the thin film 61 via the objective lens 5, and the reflected light is detected by the photodetector 9 and
The position of the objective lens 5 is moved in the direction of the optical axis by the axis moving mechanism 11, here, from the upper side to the lower side, and the in-focus position at which the detection signal of the photodetector 9 is maximized is detected.

Next, at step 403, a position where the detection signal of the photodetector 9 is large and the maximum luminance is sufficiently bright is determined.

In this case, if the detection signal is small and the maximum luminance is not sufficiently bright, in step 404, the operation waits for the operator to operate the gain adjustment unit 101b of the condition setting area 101. Is performed.

If it is determined that sufficient brightness has been obtained, the flow advances to step 405 to determine whether or not the brightness of the background is sufficient and the brightness of the background is optimum. Is determined.

In this case, if the brightness of the background is not sufficient, the operation waits for the operator to operate the offset adjustment unit 101c of the condition setting area 101 in step 406, and the offset adjustment of the photodetector 9 is performed. .

If it is determined that sufficient background brightness has been obtained, the process proceeds to step 407, where detection signals on the same measurement target surface, here, the surface 61b of the thin film 61, are fetched a plurality of times. It is determined whether it is necessary to add up.

If it is determined that the integration is necessary, the process proceeds to step 408, and the number of times can be set by operating the integration number setting unit 101d of the condition setting area 101.

The number-of-integration-times setting unit 10 in the condition setting area 101
When the operation of 1d is performed, the process proceeds to step 409.

If it is not necessary to perform the integration, the flow directly proceeds to step 409.

Next, in step 409, the condition registration button 101e is brought into a state where the operator can operate it. When the operator operates the condition registration button 101e, the conditions are set to the layer number 102a of the setting condition display area 102, the measurement target plane (Z
Position) 102b, integration (times) 102c, gain (times) 1
02d, and written into the offset (%) 102e, and simultaneously stored in the memory 43 of the computer 4.

When the above processing is completed, the routine proceeds to step 410, where it is determined whether or not the setting of the optimum data acquisition conditions has been completed for all the surfaces to be measured.

If the optimum data acquisition conditions have not been set for all the surfaces to be measured, the process returns to step 401, and thereafter, the second thin film 62 surface (the thin film 61 and the thin film 62) Similar processing is performed on each measurement target surface such as the boundary surface 62b), the third thin film 63 surface (the boundary surface 63b between the thin film 62 and the thin film 63), and the substrate 64 surface (substrate surface 64b).

Here, as a specific example, the reflectance distributions on the respective measurement target surfaces of the first to third thin films 61, 62, 63 and the substrate 64 are given, for example, as shown in FIGS. In this case, relatively large reflected light is obtained on the surface 61b of the first thin film 61 shown in FIG. 3A, the detection signal is large, and it is determined that there is no problem in data acquisition. The gain adjustment unit 101b and the offset adjustment unit 101c The condition in this state is stored without performing any operation in the integration number setting unit 101d.

The boundary surface 62b of the second thin film 62 shown in FIG. 3B includes a low-reflectance surface, is slightly dark, and tends to have a low S / N ratio. When the operator enters a condition setting waiting state and the operator sets the optimal number of integrations in the integration number setting unit 101d, the conditions are stored.

Since the boundary surface 63b of the third thin film 63 shown in FIG. 3C includes an ultra-low reflectance surface and has a small peak value, there is a problem in data acquisition as in the case of FIG. 3B. It is determined that the operator is waiting for the condition setting,
In addition to the adjustment by the operator in the gain adjustment unit 101b and the offset adjustment unit 101c, the integration frequency setting unit 1
When the number of integrations considered to be optimal in 01d is set,
The condition is stored.

Then, at the boundary surface (substrate surface) 64b of the substrate 64 shown in FIG.
In the same manner as described above, since a relatively large reflectance is obtained, it is determined that the data is sufficiently bright and there is no problem in data acquisition. Without this, the condition of this state is stored.

After setting such data acquisition conditions, the extended capture width of the applicable range of the data acquisition conditions for the first to third thin films 61, 62, 63 is set.

In this case, the first to third thin films 61, 6
The boundary Z positions 61a, 62a, and 63a of the first and second thin films 61, 62, and 63 are set substantially in the middle of the thickness direction of the first to third thin films 61, 63, and the applicable range of the data acquisition condition for the first thin film 61 is set. Is arbitrarily set from -α to the boundary Z position 6
The range up to 1a, the application range of the data acquisition condition for the second thin film 62 is the range from the boundary Z position 61a to 62a, and the application range of the data acquisition condition for the third thin film 63 is the range from the boundary Z position 62a to 63a. Range, substrate 64
The applicable range of the data acquisition condition for the boundary Z position 63
It is set in the range from a to + α.

Next, the first to third thin films 61, 62, 6
Data acquisition is performed on each measurement target surface (thin film surface 61b, boundary surface 62b, boundary surface 63b, substrate surface 64b) of substrate 3 and substrate 64.

First, when the data acquisition of the first thin film 61 is performed, the data acquisition is performed under the data acquisition conditions of the first thin film 61 in which the extended take-in width is set in the range from -α to the boundary Z position 61a. Will be

The data of the first thin film 61 is obtained by moving the position of the objective lens 5 from the upper side to the lower side in the optical axis direction under the above-mentioned data obtaining conditions. The detection signal of the photodetector 9 with respect to the surface 61b is taken into the image input unit 42 as acquisition data (luminance data).

In this case, the data acquisition condition for the first thin film 61 is that all operations are not performed in the gain adjustment unit 101b, the offset adjustment unit 101c, and the integration number setting unit 101d. It is captured.

Next, when data acquisition of the second thin film 62 is performed, data acquisition is performed under the data acquisition condition of the second thin film 62 in which the extended take-in width is set in the range from the boundary Z positions 61a to 62a. Will be

The data acquisition of the second thin film 62 is performed by moving the position of the objective lens 5 from the upper side to the lower side in the optical axis direction under the setting of the data acquisition conditions described above. The detection signal of the photodetector 9 with respect to the boundary surface 62b is taken into the image input unit 42 as acquisition data (luminance data).

In this case, the data acquisition condition for the second thin film 62 is set to the optimum number of accumulations by the accumulation number setting unit 101d, so that the data acquisition from the second thin film 62 is repeated the set number of times. , And the acquired data is taken in a state where the S / N is improved.

Next, when data acquisition of the third thin film 63 is performed, data acquisition is performed under the data acquisition condition of the third thin film 63 in which the extended take-in width is set in the range from the boundary Z positions 62a to 63a. Will be

The data of the third thin film 63 is obtained by moving the position of the objective lens 5 from the upper side to the lower side in the optical axis direction under the setting of the data obtaining conditions described above. The detection signal of the photodetector 9 with respect to the boundary surface 63b is taken into the image input unit 42 as acquisition data (luminance data).

In this case, the data acquisition conditions for the third thin film 63 include the adjustment by the gain adjustment unit 101b and the offset adjustment unit 101c, as well as the integration number setting unit 1
01d, the number of times of integration that seems to be optimal is set, so that the data acquisition from the third thin film 63 is adjusted for each of the gain and offset, and the data acquisition is repeated for the set number of times. The acquired data is captured in a state where is avoided.

When the data of the substrate 64 is obtained, the extend take-in width is set to + from the boundary Z position 63a.
Data acquisition is performed under the data acquisition conditions of the boundary surface (substrate surface) 64a of the substrate 64 set in the range up to α.

The data acquisition of the substrate 64 is performed by moving the position of the objective lens 5 from the upper side to the lower side in the optical axis direction under the setting of the data acquisition conditions described above to obtain the boundary surface of the substrate 64 (substrate surface). ) The detection signal of the photodetector 9 for 64b is taken into the image input unit 42 as acquisition data (luminance data).

In this case, the data acquisition conditions for the substrate 64 include a gain adjustment unit 101b and an offset adjustment unit 101
c, Since all operations have not been performed in the integration number setting unit 101d, the acquired data is taken as it is.

Accordingly, by doing so, the photodetector for detecting the reflected light from the first to third thin films 61, 62, 63 of the sample 6 and the respective measurement target surfaces 61b, 62b, 63b, 64b of the substrate 64 By performing the gain adjustment and the number of integrations set as the data acquisition conditions for each of the nine detection signals, the detection of each detection signal for each surface to be measured is improved to a level that does not hinder the detection and the accuracy is improved. Since the detection can be performed, each of the measurement target surfaces can be reliably detected without being influenced by the measurement target surfaces such as different reflectances, and a detection error and a measurement error can be eliminated.

By detecting the surface to be measured with high accuracy as described above, it is possible to measure the film thickness with high accuracy even if, for example, the reflectivities of the stacked thin films are different.

Further, by setting a threshold value for judging that a correct detection result has been obtained in advance, and providing a judgment unit capable of comparing and judging the threshold value with the detection result, a provisional judgment can be made between the thin film and the substrate. Even if film thickness measurement is performed with air bubbles or foreign matter mixed in, the operator is informed of the error in the detection result in that state by displaying or notifying the operator with a buzzer, or by changing the measurement position. The measurement can be performed again, so that the film thickness measurement can be performed more efficiently and with higher accuracy.

(Second Embodiment) In the first embodiment, the data acquisition conditions are set manually, but in the second embodiment, the optimum data acquisition conditions are automatically set. Is set.

The schematic configuration of the scanning laser microscope applied to the film thickness measuring apparatus according to the second embodiment is the same as that of FIG. 1, and the description will be omitted with reference to FIG.

Further, as shown in FIG.
It is assumed that the third to third thin films 61, 62, 63 are laminated on the substrate 64.

Further, the setting condition display area (see FIG. 5) displayed on the monitor 10 screen when automatically setting the data acquisition conditions is the same as the setting condition display area 10 shown in FIG.
2, a layer number 102a, a measurement target surface (Z position) 102b,
In addition to the setting items of the number of integrations (times) 102c, gain (times) 102d, and offset (%) 102e, a design film thickness 102f, a layer upper limit Z position (= the thin film surface 61b) 102
g and the lower limit Z position (= substrate surface 64b) 102h are displayed.

The items set as the data acquisition conditions are not limited to those described above. For example, the reflectance of each thin film and substrate may be input as information.

In this state, first, the operation according to the flowchart shown in FIG. 6 is performed.

At step 601, the input state of the thickness of each thin film of the sample 6 is entered, and the input is made by the operator.

Here, the film thicknesses of the first to third thin films 61, 62, 63 input by the operator correspond to design values given in advance in the design stage.

Here, the first to third thin films 61,
As shown in FIG. 3, the film thicknesses of 62 and 63 are d1, d2 and d3.
, And these film thicknesses d1 and d1
2, d3 are input in order until it is determined in step 602 that a necessary amount has been input.

The thicknesses d1, d2, d3 of the first to third thin films 61, 62, 63 inputted by the operator are:
While being stored in the memory 43 of the computer 4, FIG.
Is displayed at the design film thickness 102f in the setting condition display area shown in FIG.

Next, in the flowchart shown in FIG. 7, step 701 waits for the operator to mount the sample 6 on the stage 12.
When the sample 6 is placed thereon, the process proceeds to step 702.

Next, step 702 and step 70
In step 3, the position of the objective lens 5 is moved in the optical axis direction by the Z-axis moving mechanism 11 every two-dimensional scanning of the laser beam under the control of the control unit 4 of the computer 4, so that the detection signal of the photodetector 9 is maximized. The surface 61b of the first thin film 61 of the sample 6 is detected from the changed focus position.

Next, in step 704, the first thin film 61
From the surface 61b and the film thicknesses d1, d2, d3 of the first to third
The Z position of the measurement target surface of the thin films 61, 62, and 63 and the setting range of the data acquisition condition (hereinafter, referred to as the data acquisition range) are determined.

In this case, following the surface 61b of the first thin film 61, the position of the surface 61b of the first thin film 61 + the film thickness d1
The Z position of the boundary surface 62b of the second thin film 62 is obtained by
The Z position of the boundary surface 63b of the third thin film 63 is determined from the position of the boundary surface 62b of the second thin film 62 + the thickness d2.

Further, the range from the surface 61b of the first thin film 61 to the position of ((the position of -α to the position of the surface 61b of the first thin film 61) + (film thickness d1 / 2)) is obtained. The range obtained is the data acquisition range of the first thin film 61.

Then, ((the surface 61b of the first thin film 61)
(Position of the surface 61b of the first thin film 61) + (Film thickness d1 of the first thin film 61) + (Film thickness of the second thin film 62) The range up to the position of d2 / 2)) is obtained, and the obtained range is set as the data acquisition range of the second thin film 62.

Further, ((the surface 61b of the first thin film 61)
Position) + (the thickness d1 of the first thin film 61) + (the thickness d2 / 2 of the second thin film 62)).
Position of first surface 61b) + (film thickness d of first thin film 61)
1) + (thickness d2 of second thin film 62) + (third thin film 6
A range up to the position of the third film thickness d3 / 2)) is obtained, and the obtained range is defined as a data acquisition range of the third thin film 63.

Then, from the position of the surface 61b of the first thin film 61 + the thickness d1 of the first thin film 61 + the thickness d2 of the second thin film 62 + the thickness d3 / 2 of the third thin film 63, the first Of the surface 61b of the first thin film 61 + the thickness d of the first thin film 61
1 + the thickness d2 of the second thin film 62 + the thickness d3 + α of the third thin film 63 to the boundary surface of the substrate 64 (substrate surface)
The setting range of the data acquisition condition of 64b is obtained.

The first to third thin films 61, 62, 63
The Z position and the data acquisition range of each of the measurement target surfaces 61b, 62b, 63b are the Z position 102g of the uppermost limit (thin film surface 61b) of the setting display area shown in FIG.
4b) position 102h, measurement target surface (Z position) 102b
And the memory 43 of the computer 4
Is stored.

Next, in step 705, the first thin film 61
The auto-contrast is applied to the surface 61b, and "gain" and "offset" conditions are obtained.

These are the data acquisition conditions, the layer number 102a of the setting condition display area shown in FIG.
Position) 102b, gain (times) 102d, and offset (%) 102e.
Is stored in the memory 43.

Next, at step 706, the number of times of integration is determined.

In this case, at the Z position of the surface 61b of the first thin film 61, a relatively uniform luminance distribution can be obtained, so that the computer 4 obtains the acquired data in a relatively small area such as the central portion on the screen of the monitor 10, for example. The number of integrations is determined from the standard deviation of (luminance data), and this is taken into account in the data acquisition conditions.

Although the number of times of integration is set by the computer 4 here, the present invention is not limited to this, and may be manually input by an operator.

In this case, the variation of the random noise is reduced to 1 / √n by the integration of n times, so that a threshold value of a certain standard deviation is provided, and if the standard deviation of the acquired data is a times, this threshold value The number of integrations required to make the following is a2.

Next, at step 707, the second thin film 62
Then, in step 708, auto-contrast is applied to the boundary surface 62b of the second thin film 62 to determine “gain” and “offset” conditions. In step 709, the number of integrations is determined. .

These results are used as data acquisition conditions.
The layer number 102a, the measurement target surface (Z position) 102b, the number of integrations (times) 102c, the gain (times) 102d, and the offset (%) 102e of the setting condition display area shown in FIG. Is stored.

Then, in step 710, it is determined whether data acquisition conditions have been set for all layers.

Here, since there is still the third thin film 63 and thereafter, the process returns to step 707 and the above-described operation is repeated, and the “gain” and “offset” conditions for the third thin film 63 and the substrate 64 are calculated. FIG. 5 shows the result of the frequency determination.
Are written in the layer number 102a, the measurement target surface (Z position) 102b, the number of integrations (times) 102c, the gain (times) 102d, and the offset (%) 102e in the setting condition display area shown in FIG. Is done.

Thereafter, if it is determined in step 710 that the data acquisition conditions have been set for all the layers, the process proceeds to step 711, where the first to third thin films 61, 62,
63 and the respective measurement target surfaces 61b, 62b, 63 of the substrate 64
Data acquisition is performed for b and 64b.

Data acquisition in this case is the same as that described in the first embodiment, and a description thereof will not be repeated.

Therefore, according to this, each of the thin films 61, 62, 63 and the substrate 64 is obtained from the film thicknesses d1, d2, d3 of the first to third thin films 61, 62, 63 which are given in advance as design values. Measurement target surfaces 61b, 62b, 63b, 64
By automatically determining the position of b and the setting range of the data acquisition condition, setting of the data acquisition condition for each of these setting ranges,
Data acquisition conditions are executed for the detection signal of the photodetector 9 according to the reflected light from the first to third thin films 61, 62, 63, and a series of operations up to data acquisition are automatically performed. In this embodiment, three thin films of the first to third thin films 61, 62, and 63 are formed as the sample 6 in the above-described embodiment. However, the same can be applied to the sample 6 in which a plurality of thin films other than three layers are formed.

As described above, the detection of the measurement target surface with high accuracy can be automatically performed. Therefore, even if the reflectivities of a plurality of laminated thin films are different, for example, the high reflectivity as in the first embodiment is obtained. Accurate film thickness measurement can be performed automatically.

In the second embodiment as well, a threshold for determining in advance that a correct detection result has been obtained is set in advance, and a determination unit for comparing the threshold with the detection result is provided. Even if the film thickness measurement is performed in a state where bubbles or foreign substances are mixed between the thin film and the substrate,
It is also possible to notify the operator of the error in the detection result in that state with a display or a buzzer, or to change the measurement position and perform the measurement again. It is also possible to proceed more efficiently and with high precision.

In the above-described embodiment, the scanning laser microscope has been described as an example. However, the microscope to which the present invention is applied is not limited to this. For example, a disk scan confocal microscope such as a Nikowow Disk can be used. The microscope may be a microscope, or a microscope configured to perform high-speed scanning in the X direction using an acousto-optic device instead of a galvanometer mirror and receive light from a sample by a line sensor without passing through a pinhole. Can also be used.

[0110]

As described above, according to the present invention, a film thickness measuring apparatus capable of reliably detecting the film surfaces of a plurality of thin films having different reflectivities, a data acquisition method and data in the film thickness measuring apparatus A recording medium storing a program for acquisition can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of a scanning laser microscope applied to a first embodiment of the present invention.

FIG. 2 is an exemplary diagram showing a display example of a monitor screen according to the first embodiment.

FIG. 3 is a diagram illustrating a sample used in the first embodiment.

FIG. 4 is a flowchart for explaining an operation in the first embodiment.

FIG. 5 is a diagram showing a display example of a monitor screen according to the second embodiment of the present invention.

FIG. 6 is a flowchart illustrating an operation according to the second embodiment.

FIG. 7 is a flowchart for explaining the operation of the second embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Laser light source 2 ... Mirror 3 ... Half mirror 4 ... Computer 41 ... Control part 42 ... Image input part 43 ... Main memory 44 ... Video card 45 ... CPU 46 ... Recording medium 47 ... CPU bus 5 ... Objective lens 6 ... Sample 61 ... first thin film 62 ... second thin film 63 ... third thin film 61a, 62a, 63a ... boundary Z position 64 ... substrate 7 ... imaging lens 8 ... pinhole 9 ... photodetector 10 ... monitor 101 ... condition setting Area 101a: Z position setting unit 101b: Gain adjustment unit 101c: Offset adjustment unit 101d: Accumulation count setting unit 101e: Condition registration button 102: Setting condition display area 102a: Layer number 102b: Film surface (Z position) 102c: Integration ( Times) 102d ... gain (times) 102e ... offset (%) 102f ... design film thickness 102g ... layer upper limit Z position 102h Layer lower Z position 11 ... Z-axis moving mechanism 12 ... Stage 14 ... two-dimensional scanning mechanism

Claims (6)

[Claims] 1. A sample having a thin film formed thereon and having at least two surfaces to be measured is irradiated with spot light through an objective lens, and the sample and the objective lens are relatively positioned on an optical axis. While detecting the thickness of the thin film formed on the sample, the reflected light from the sample is detected by the light detection unit, and the surface to be measured is detected from a change in the detection output of the light detection unit. In the film thickness measuring device for measuring, according to the state of the detection output of the light detection means, a data acquisition condition setting means for setting a gain or the number of integrations for the detection output as a data acquisition condition, and a detection output of the light detection means A data acquisition unit that executes gain adjustment or integration count set by the data acquisition condition setting unit and acquires data. 2. The method according to claim 1, further comprising: setting range determining means for determining a setting range of a data acquisition condition from information of the thin film provided as a design value in advance, wherein the data acquisition condition setting means is determined by the setting range determining means. 2. The film thickness measuring apparatus according to claim 1, wherein a gain or an integration count for the detected output is set as a data acquisition condition based on a state of a detected output of the light detecting unit. 3. A sample on which a thin film is formed and which has at least two surfaces to be measured is irradiated with spot light through an objective lens, and the sample and the objective lens are relatively positioned on an optical axis. While detecting the thickness of the thin film formed on the sample, the reflected light from the sample is detected by the light detection unit, and the surface to be measured is detected from a change in the detection output of the light detection unit. In the data acquisition method in the film thickness measurement device to be measured, according to the state of the detection output of the light detection unit, a gain or the number of integration for the detection output is set as a data acquisition condition, and the detection output of the light detection unit is Executing the gain adjustment or the number of integrations set by the data acquisition condition setting means to acquire data. 4. A setting range of a data acquisition condition is determined from information of the thin film given in advance as a design value, and a gain or a gain for the detection output is determined in the determined range from a state of a detection output of the light detection means. 4. The data acquisition method according to claim 3, wherein the number of times of integration is set as a data acquisition condition. 5. A sample on which a thin film is formed and which has at least two surfaces to be measured is irradiated with spot light through an objective lens, and the sample and the objective lens are relatively positioned on an optical axis. While detecting the thickness of the thin film formed on the sample, the reflected light from the sample is detected by the light detection unit, and the surface to be measured is detected from a change in the detection output of the light detection unit. A recording medium on which a program for acquiring data in a film thickness measuring device to be measured is recorded, wherein a gain or an integration count for the detected output is set as a data acquisition condition in accordance with a state of a detection output of the light detection unit. Data in a film thickness measuring device, wherein the data is acquired by executing gain adjustment or the number of integrations set by the data acquisition condition setting means with respect to a detection output of the light detection means. A recording medium on which a program for acquisition is recorded. 6. A recording medium in which a program for acquiring data in a film thickness measuring device is recorded, a setting range of data acquisition conditions is determined from information of the thin film given as a design value in advance, and 6. A program for acquiring data in the film thickness measuring apparatus according to claim 5, wherein a gain or an integration count for the detected output is set as a data acquisition condition based on a state of a detection output of the light detection means. Recording medium.