JPH10300433A - Film thickness measuring method and device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately measure the thickness of a film to be measured which is formed on one side of a subject for measurement, even if the thickness of the object for measurement varies. SOLUTION: An upper-surface displacement gauge 51 and a lower-surface displacement gauge 52 are placed, respectively, on the upper side where a film 17 is formed and on the lower side where the film 17 is not formed, and at a predetermined interval (d) to each other. The measuring light of the lower surface displacement gauge 52 placed on the lower side of a substrate 16 is transmitted through the substrate 16 to measure the amount K2 of displacement of the lower surface of the film 17. The lower surface displacement gauge 52 moves by a preset amount Za to measure the amount K1 of displacement of the lower surface of the substrate 16. A correction value K3 for the thickness of the substrate 16 is calculated on the basis of the amounts K1, K2 of displacement and the amount Za of movement of the lower surface displacement gauge 52. The thickness (m) of the film 17 is calculated on the basis of the interval (d) between the displacement gauges 51, 52, the amount a2 of displacement of the upper surface of the film 17 measured by the upper surface displacement gauge 51, the amount b2 of displacement of the lower surface of the film 17 measured by the lower surface displacement gauge 52, and the correction value K3 calculated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for measuring a film thickness formed on a surface of a transparent substrate used for a display device such as a PDP.

In recent years, plasma display panels (PDs)
Display devices such as P) have been increasing in size. Then, it is required to accurately measure the thickness of a film formed on a display substrate of the display device.

[0003]

2. Description of the Related Art Conventionally, a display substrate used for a large display device such as a PDP or an LCD is provided on one side thereof. A film such as a dielectric film is formed by a thin film or thick film technique. And, in order to measure the thickness of the formed film in a non-contact manner,
For example, a laser displacement meter is used. The laser displacement meter measures the distance (displacement amount) from the displacement meter to the object based on the irradiation position of the laser light and the light receiving position where the reflected light of the object is received. Therefore, laser displacement meters are provided on both the upper and lower surfaces of the display substrate, and the distance between the upper surface of the film and the distance between the lower surface of the film are measured simultaneously, and the film thickness is calculated from both distances.

[0004]

In the above method, however, the laser displacement meter provided on the lower surface transmits the laser beam to be measured through the display substrate to measure the distance between the film and the lower surface. Therefore, when the thickness of the display substrate changes, the state (refractive angle, etc.) of the laser beam transmitted through the display substrate changes, and the distance between the lower surface of the film greatly changes. Therefore, it is necessary to measure the thickness of the film accurately. There is a problem that can not be.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a film to be measured formed on one surface of a measured object even when the thickness of the measured object varies. It is an object of the present invention to provide a film thickness measuring method and a film thickness measuring device capable of accurately measuring a thickness.

[0006]

In order to achieve the above object, the present invention provides a method for measuring the thickness of a film formed on one surface of a substrate, comprising: An upper surface displacement meter and a lower surface displacement meter are respectively arranged at predetermined intervals on the upper surface side where the film is formed and the lower surface side where the film is not formed, and the measurement light of the lower surface displacement meter arranged on the lower surface side of the substrate is measured. The amount of displacement of the lower surface of the film is measured by transmitting the light through the substrate, and the amount of displacement of the lower surface of the substrate is measured by moving the lower surface displacement meter by a predetermined amount. A correction value for the thickness of the substrate is calculated based on the displacement amount of the lower surface displacement meter and the displacement amount of the film upper surface measured by the upper surface displacement meter, and the lower surface displacement. The amount of displacement of the film lower surface measured by the meter,
The gist is that the film thickness of the film is calculated based on the calculated correction value.

According to a second aspect of the present invention, in the film thickness measuring method according to the first aspect, the lower surface of the film is offset by a refractive index of the substrate, and the lower surface displacement meter transmits the measurement light through the substrate. The gist of the invention is to measure a displacement amount of the film lower surface offset by the offset, and calculate an offset amount by which the film lower surface is offset based on a refractive index of the substrate material as a correction value for the thickness of the substrate.

[0008] The invention according to claim 3 is the invention according to claim 1 or 2.
In the film thickness measuring method according to the above, the displacement amount of the film lower surface measured by passing through the substrate, the displacement amount of the substrate lower surface measured by the moved lower surface displacement meter, and the displacement amount of the lower surface displacement meter The actual thickness of the substrate is calculated by multiplying the thickness of the substrate including the refractive index calculated based on the refractive index of the substrate by subtracting the thickness of the substrate including the refractive index from the actual thickness. The gist is that the correction value is calculated.

The invention described in claim 4 is the first to third aspects of the present invention.
In the film thickness measuring method according to any one of the above, before measuring the film thickness of the film, a reference gauge having a predetermined thickness is disposed between the two displacement gauges, the upper and lower of the reference gauge The gist is that the amount of displacement on both sides is measured by the upper and lower displacement meters, and the distance between the two displacement meters is calculated based on the measurement results.

[0010] The invention described in claim 5 provides the invention according to claims 1 to 4.
In the film thickness measuring method according to any one of the above, the refractive index of the substrate with respect to the wavelength of the measurement light of the lower surface displacement meter is obtained in advance, and the correction value is calculated using the refractive index. That is the gist.

According to a sixth aspect of the present invention, in the film thickness measuring method according to the fifth aspect, the displacement amount of the upper surface of the substrate on which the film is not formed is measured by the upper surface displacement meter. Measure the amount of displacement of the upper surface of the substrate by passing through the substrate at, measure the amount of displacement of the lower surface of the substrate by moving the lower surface displacement meter, the displacement amount, the amount of movement of the lower surface displacement meter, The gist is that the refractive index of the substrate is calculated based on the distance between the two displacement meters.

According to a seventh aspect of the present invention, there is provided a film thickness measuring device for measuring the thickness of a film formed on one surface of a substrate, wherein the upper surface displacement is disposed on the upper surface side of the substrate on which the film is formed. Meter, a lower surface displacement meter arranged on the lower surface side of the substrate on which the film is not formed, facing the upper surface displacement meter, and measurement light of the lower surface displacement meter arranged on the lower surface side of the substrate. First measuring means for measuring the amount of displacement of the lower surface of the film by transmitting the light; a vertical movement mechanism for moving the lower surface displacement meter by a predetermined amount; and a displacement amount of the lower surface of the substrate by the moved lower surface displacement meter A second measuring means for measuring
Correction value calculation means for calculating a correction value for the thickness of the substrate based on the measurement result of the second measurement means and the amount of movement of the lower surface displacement meter by the vertical movement means; and A third measuring means for measuring the amount of displacement, a film thickness calculating means for calculating the film thickness based on the measurement results of the first to third measuring means, and the correction value calculated by the correction calculating means; The gist is that it is provided.

According to an eighth aspect of the present invention, in the film thickness measuring apparatus according to the seventh aspect, a frame-like member which is supported by a frame so as to be movable in a vertical direction of the substrate, and in which the substrate passes therethrough. A table, the upper surface displacement meter and the lower surface displacement meter are fixed to the table,
The gist is that the table is moved up and down by a predetermined amount.

According to a ninth aspect of the present invention, there is provided the method of the seventh or eighth aspect.
In the film thickness measuring device according to the above, the up and down moving mechanism,
The eccentric cam includes a pair of eccentric cams arranged at a predetermined distance from the center of gravity of the table, and a motor for driving the eccentric cam to rotate. The eccentric cam is related to a pair of pins protrudingly provided on the frame. In addition, the table is supported, and the eccentric cam is rotationally driven by the motor to move the table up and down.

According to a tenth aspect of the present invention, in the film thickness measuring apparatus according to the ninth aspect, a bearing is provided on an outer periphery of the eccentric cam, and the outer periphery of the bearing is engaged with the pin. Is the gist.

According to an eleventh aspect of the present invention, in the film thickness measuring device according to any one of the seventh to tenth aspects, a reference gauge having a predetermined thickness is arranged between the two displacement gauges. A distance calculating means for measuring a displacement amount of both the upper and lower surfaces of the reference gauge with the upper and lower displacement gauges to calculate a distance between the two displacement gauges, wherein the film thickness calculating means is calculated by the distance calculating means. The point is that the thickness of the film is calculated based on the distance.

According to a twelfth aspect of the present invention, in the film thickness measuring device according to any one of the seventh to eleventh aspects, the substrate for the wavelength of the measuring light of the lower surface displacement meter based on each of the measurement results. The gist of the invention is that there is provided a refractive index calculating means for calculating the refractive index, and the correction value calculating means calculates the correction value based on the calculated refractive index.

(Operation) Therefore, according to the first aspect of the present invention, the upper surface displacement meter and the lower surface displacement meter are arranged at predetermined intervals on the upper surface side where the film is formed and the lower surface side where the film is not formed. Is done. The measurement light of the lower surface displacement meter arranged on the lower surface side of the substrate is transmitted through the substrate, and the amount of displacement of the lower surface of the film is measured. The lower surface displacement meter is moved by a preset amount to measure the displacement amount of the lower surface of the substrate, and a correction value for the thickness of the substrate is calculated based on the displacement amount of the lower surface of the film, the displacement amount of the lower surface of the substrate, and the displacement amount of the lower surface displacement meter. Is calculated. Then, the film thickness of the film is calculated based on the distance between the two displacement meters, the displacement amount of the film upper surface measured by the upper surface displacement meter, the displacement amount of the film lower surface measured by the lower surface displacement meter, and the calculated correction value. You.

According to the second aspect of the invention, the lower surface of the film is offset by the refractive index of the substrate, and the lower surface displacement meter measures the amount of displacement of the offset lower surface of the film by transmitting measurement light through the substrate. . Then, an offset amount in which the lower surface of the film is offset by the refractive index of the substrate material is calculated as a correction value for the thickness of the substrate.

According to the third aspect of the present invention, the displacement amount of the lower surface of the film measured by passing through the substrate, the displacement amount of the lower surface of the substrate measured by the moved lower surface displacement meter, and the displacement amount of the lower surface displacement meter The actual thickness of the substrate is calculated by multiplying the thickness of the substrate including the refractive index calculated based on the above by the refractive index of the substrate, and the thickness of the substrate including the refractive index is subtracted from the actual thickness. A correction value is calculated.

According to the fourth aspect of the present invention, a reference gauge having a predetermined thickness is disposed between the two displacement meters, and the displacement of the upper and lower surfaces of the reference gauge is measured by the upper and lower displacement meters. The distance between the two displacement meters is calculated based on the measurement result.

According to the fifth aspect of the present invention, the refractive index of the substrate with respect to the wavelength of the measurement light of the lower surface displacement meter is obtained, and the correction value is calculated using the refractive index. According to the invention described in claim 6, the displacement amount of the upper surface of the substrate on which the film is not formed is measured by the upper surface displacement meter, and the displacement amount of the upper surface of the substrate through the substrate is measured by the lower surface displacement meter. Then, the lower surface displacement meter is moved to measure the amount of displacement of the lower surface of the substrate. Then, the refractive index of the substrate is calculated based on each displacement amount, the movement amount of the lower surface displacement meter, and the distance between the two displacement meters.

According to the present invention, the upper surface displacement meter is disposed on the upper surface side of the substrate on which the film is formed, and the lower surface displacement meter is disposed on the lower surface side of the substrate on which the film is not formed. And are arranged to face. The first measuring means measures the amount of displacement of the lower surface of the film by transmitting the measurement light of the lower surface displacement meter disposed on the lower surface side of the substrate through the substrate. The vertical movement mechanism moves the lower surface displacement meter by a predetermined amount. The second measuring means measures the amount of displacement of the lower surface of the substrate with the lower surface displacement meter after the movement.
The correction value calculation means includes a measurement result of the first and second measurement means,
A correction value for the thickness of the substrate is calculated based on the amount of movement of the lower surface displacement meter by the vertical movement means. Then, the third measuring means measures the amount of displacement of the upper surface of the film using the upper surface displacement meter.
Then, the film thickness calculating means calculates the film thickness of the film based on the measurement results of the first to third measuring means and the correction value calculated by the correction calculating means.

According to the eighth aspect of the present invention, there is provided a frame-shaped table which is supported by the frame so as to be movable in the vertical direction of the substrate, and through which the substrate passes. The upper surface displacement meter and the lower surface displacement meter are fixed to the table, and the up and down movement mechanism moves the table up and down by a predetermined amount.

According to the ninth aspect of the present invention, the up-and-down moving mechanism is arranged at a predetermined distance from the center of gravity of the table.
A pair of eccentric cams and a motor for driving the eccentric cams are provided. The eccentric cam engages with a pair of pins projecting from the frame to support the table, and the motor drives the eccentric cam to rotate the table up and down.

According to the tenth aspect of the present invention, a bearing is provided on the outer periphery of the eccentric cam, and the outer periphery of the bearing engages with the pin. According to the eleventh aspect of the present invention, a reference gauge having a predetermined thickness is disposed between the two displacement meters, and the distance calculating means measures the displacement of the upper and lower surfaces of the reference gauge with the upper and lower displacement meters. Then, the distance between the two displacement meters is calculated. Then, the film thickness calculating means calculates the film thickness of the film based on the distance calculated by the distance calculating means.

According to the twelfth aspect of the present invention, there is provided a refractive index calculating means for calculating the refractive index of the substrate with respect to the wavelength of the measuring light of the lower surface displacement meter based on each measurement result. And
The correction value calculation means calculates a correction value based on the calculated refractive index.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. FIG. 2 is a schematic front view of the film thickness measuring device 11 of one embodiment, and FIG. 3 is a partially cutaway sectional view of the film thickness measuring device 11. A base frame 12 is provided in the film thickness measuring device 11. At the center of the upper surface of the base frame 12, a pair of left and right rails 13 is disposed so as to extend in the front-rear horizontal direction (the direction of the front and back in FIG. 2). It is arranged movably.

On the X-axis table 14, a plurality of (four in this embodiment) support members 15 extending in the front-rear direction are arranged in the left-right direction. Each support member 15 is connected to the X-axis table 14 by connecting members (not shown) at front and rear ends, and moves in the front-rear direction integrally with the X-axis table 14.

Each support member 15 has the same upper surface height, and a display substrate (a glass substrate in this embodiment) 16 as an object to be measured is supported by each support portion 15 material. On one surface of the glass substrate 16, a film 1 as a film to be measured is formed.
7 (see FIG. 1B). Then, the glass substrate 16 is placed on the support member with the surface on which the film 17 is formed as the upper surface.

At the left end of the upper surface of the base frame 12,
An upright 8 is provided, and a frame 19 extending in the left-right direction is disposed above the base frame 12 at the upper end of the support column 18. The width of the frame 19 in the left-right direction is substantially the same as the width of the base frame 12 in the left-right direction, and is supported by a support column a predetermined distance above the upper surface of the base frame 12.

As shown in FIG. 4, a pair of upper and lower rails 20 are disposed on the front surface of the frame 19 (the right side surface in FIG. 4) so as to extend in the left-right direction. Also, the frame 19
A Y-axis table 21 is provided on the front surface of the device so as to be movable in the left-right direction by a rail 20. Y-axis table 21
Are driven by the driving force of the Y-axis motor 22 shown in FIG.
It moves in the left-right direction along 0.

As shown in FIG. 3, the Y-axis table 21 has a pair of left and right pins 23 projecting forward. The pin 23 is provided on the front surface of the Y-axis table 21.
A pair of left and right Z-axis guides 24 are provided on both left and right sides of the Z-axis guide.

In front of the frame 19, a Z-axis table 25 is provided. The Z-axis table 25 is vertically moved by a Z-axis guide 24 provided on the Y-axis table 21 (in the front-to-back direction in FIG. 3). It is arranged to be movable.

The Z-axis table 31 has a first base 32 extending in the left-right direction and having a Z-axis guide 24 attached to its back surface.
And pillar members 3 suspended from both left and right ends of the first base 32
3 and 34, and a second base 35 connecting both lower ends of the column members 33 and 34, and is formed in a frame shape extending in the left-right direction. The first base 32 is formed integrally with left and right and up and down ribs 32a on the front surface of the plate member, so that the first base 32 is reinforced and reduced in weight. The second base 35 is disposed between the X-axis table 14 and each support member 15 that supports the glass substrate 16 in the up-down direction. Therefore, the glass substrate 16 moves in the front-rear direction through the inside of the frame-shaped Z-axis table 31 that opens in the front-rear direction.

The Z-axis table 31 is provided on the front surface of the first base 32 with a vertical moving mechanism 41 for moving the table 31 in the vertical direction. Vertical movement mechanism 41
Is constituted by a Z-axis motor 42 and a pair of cams 44 attached to a rotation shaft 43 connected to an output shaft of the motor 42.

Below the pair of cams 44, the first base 3
The pin 23 inserted in the hole 36 penetrated in the front-rear direction in 2
Are arranged, and the Z-axis table 31 is supported by the engagement of the cam 44 and the pin 23. Also, both cams 4
Reference numeral 4 denotes an eccentric cam, and both cams 4
When the pivot 4 is driven, the Z-axis table 31 moves up and down along the Z-axis guide 24 with respect to the pin 23 on the fixed side by an amount corresponding to the pivot angle.

The amount of eccentricity of the two cams 44 is such that the amount of vertical movement of the Z-axis table 31 is greater than the thickness of the glass substrate 16 in accordance with the thickness of the glass substrate 16 as the object to be measured. Is set to The diameter of the hole 36 into which the pin 23 is inserted is set to a size that does not hinder the vertical movement of the Z-axis table 31.

The rotating shaft 43 to which the two cams 44 are attached is disposed at the center of gravity of the Z-axis table 31 in the front-rear direction by a pair of right and left mounting members 45. A pair of cams 44
Are disposed equidistant from the center of gravity of the Z-axis table 31 in the left-right direction. Then, the pair of Z-axis guides 24 engage with the pair of cams 44 and
Are provided on both left and right sides of a pair of pins 23 that support the pins. Therefore, since the Z-axis table 31 is supported at the position of the center of gravity, the load on the Z-axis guide 24 is reduced.

Further, as shown in FIG.
A bearing 46 is provided on the outer periphery, and the outer periphery of the bearing 46 is in contact with the pin 23. That is, the contact point between the cam 44 and the pin 23 has a rolling contact structure by the bearing 46.
Therefore, the resistance between the cam 44 and the pin 23 becomes the rolling resistance due to the bearing 46, and is smaller than the sliding resistance when the bearing 46 is not provided.

As shown in FIG. 3, the first base 32
A position sensor 47 is provided on the front surface of the. The position sensor 47 is provided to detect a vertical position of the Z-axis table 31, for example, an initial position.

The initial position is set as a position where the distance to the upper surface of the film 17 can be measured by the upper surface displacement meter 51 described later. The upper surface displacement meter 51 and the lower surface displacement meter 52 are laser displacement meters, and measure the distance to the object to be measured based on the light receiving position of the laser light reflected by the object. Therefore, the measurement range of the laser displacement meter with respect to the reference distance from the displacement meter is determined by the size thereof. Therefore, the initial position is determined and the Z-axis table 31 is aligned so that the upper surface of the film 17 comes within the measurement range.

The position sensor 47 comprises a photo interrupter in this embodiment, and detects the presence or absence of a slit (not shown) of a rotary plate 47a provided on the output shaft of the Z-axis motor 42. Then, for example, by stopping the Z-axis motor 42 when the position sensor 47 detects the slit, the cam 44 that is driven to rotate by the motor 42 is stopped at a certain angle, and the Z-axis table 31 is moved in a desired direction in the vertical direction. Stop in position. The rotating plate 47a is connected to a pair of cams 4.
4, a position sensor 47 may be provided at a position for detecting the presence or absence of a slit of the rotary plate 47a.

As shown in FIG. 3, a plurality of pairs (three pairs in this embodiment) of displacement gauges 51 and 52 are arranged on the Z-axis table 31 in the left-right direction. Displacement gauges 51 and 52 for each pair
Are arranged at equal intervals in the left-right direction. Further, each pair of displacement gauges 51 and 52 comprises a laser displacement gauge, and
6 are arranged oppositely above and below. Top surface displacement meter 51
Is provided for measuring the distance to the upper surface of the film 17. The lower surface displacement meter 52 is provided for measuring the distance to the lower surface of the film 17.

As shown in FIG. 5, the upper surface displacement meter 51 is mounted on an adjustment stage 53, and the adjustment stage 53 is fixed to the lower end of the front surface of the first base 32 via a bracket 54. The lower surface displacement meter 52 is attached to an adjustment stage 55, and the adjustment stage 55 is fixed to an upper surface of the second base 35 via a bracket 56. The adjustment stages 53 and 55 are stages that can be finely adjusted in the left-right direction or the like, and are provided for performing position adjustment such as alignment of the optical axes of the two displacement meters 51 and 52, and are configured so that the adjusted positions can be fixed. Have been. Therefore, when the Z-axis table 31 moves up and down, the upper surface displacement meter 51 and the lower surface displacement meter 52 move integrally in the vertical direction, and the distance between the two displacement meters 51 and 52 does not change.

As shown in FIG. 4 and FIG.
A cylinder 57 is provided on a bracket 56 for fixing the second cylinder 2. The cylinder 57 is an air cylinder with a guide, and moves a support member 59 to which a reference gauge 58 is fixed at the tip thereof to move the reference gauge 58 to the two displacement meters 51,
It is provided so as to be arranged between 52.

The reference gauge 58 has a known thickness and is used for measuring the distance between the two displacement gauges 51 and 52. That is, the displacement amount (distance) to the upper surface of the reference gauge 58 measured by the upper surface displacement meter 51 and the displacement amount (distance) to the lower surface of the reference gauge 58 measured by the lower surface displacement meter 52.
And the thickness of the well-known reference gauge 58 is added to calculate the distance between the two displacement gauges 51 and 52. The cylinder 57 is connected to the reference gauge 58 by the displacement gauges 51 and 5.
The measurement position at which the distance can be measured by the
When the film thickness of the film 17 formed on the substrate is measured, the reference gauge 58 is retracted obliquely downward, and is switched to a retracted position where the reference gauge 58 is not engaged with the glass substrate 16.

Next, the electrical configuration of the film thickness measuring device 11 will be described. As shown in FIG. 7, the film thickness measuring device 11 includes a control device 6 as first to third measuring means, correction value calculating means, film thickness calculating means, distance calculating means, and refractive index calculating means.
1 is provided. The controller 61 includes an upper surface displacement meter 5
1, the lower surface displacement meter 52 and the position sensor 47 are connected. The control device 61 includes the X-axis table 1.
4 for moving the X-axis motor 62 and the Y-axis motor 2
2. The Z-axis motor 42 and the cylinder 57 are connected.

The control device 61 includes a storage device such as a ROM (not shown), and the storage device includes a film 1 as a film to be measured.
A measurement program for measuring the film thickness of No. 7 is stored. Further, the control device 61 is a RAM in which various data such as a refractive index of glass constituting the glass substrate 16 is stored.
(Not shown).

The control device 61 operates based on the measurement program, and measures the thickness of the film 17 based on the distance measured by the upper surface displacement meter 51 and the lower surface displacement meter 52. At this time, the control device 61 performs correction based on the refractive index and correction based on the thickness of the glass substrate 16 on the measured film thickness to calculate a true film thickness.

Next, the procedure of measuring the film thickness in the film thickness measuring device 11 configured as described above will be described with reference to FIGS.
Details will be described according to (c). First, according to FIG.
The control device 61 measures the distance d between the upper surface displacement meter 51 and the lower surface displacement meter 52 prior to the measurement of the film 17. The control device 61 drives and controls the cylinder 57 to arrange the reference gauge 58 at the measurement position. And the control device 6
1 measures the distance a1 from the upper surface displacement meter 51 to the upper surface of the reference gauge 58 and the distance b1 from the lower surface displacement meter 52 to the lower surface of the reference gauge 58. Further, assuming that the thickness of the well-known reference gauge 58 is c, the distance d between the displacement gauges 51 and 52 is calculated as d = a1 + b1 + c --- (1). The control device 61 includes both displacement meters 51 and 5
The distance d between the two is measured for each pair and stored in the RAM.

Next, according to FIG.
Performs measurement for correction based on the refractive index and correction based on the thickness of the glass substrate 16. First, the control device 61 measures the distance to the upper surface of the glass substrate 16, that is, the distance to the lower surface of the film 17 using the lower surface displacement meter 52. At this time, the measured distance to the lower surface of the film 17 is measured as a distance K2 offset from the actual lower surface of the film 17 toward the lower surface displacement meter 52 due to the influence of the refractive index of glass.

Next, the control device 61 controls the drive of the Z-axis motor 42 to move the Z-axis table 31 downward by a predetermined movement amount Za, and measures the distance K1 to the lower surface of the glass substrate 16. I do. The movement amount Za of the Z-axis table 31 at this time is measured in advance for each lower surface displacement meter 52 for a predetermined number of pulses for driving the Z-axis motor 42 composed of a pulse motor, and is stored in the RAM. An external measuring device such as a linear scale is used for measuring the movement amount Za.

That is, an external measuring device is set in the film thickness measuring device 11, and the Z-axis motor 42 is driven by a predetermined number of pulses. At this time, the amount of movement of each lower surface displacement meter 52 of the Z-axis table 31 that moves in the vertical direction is measured by an external measuring device and stored in the RAM. Since the Z-axis motor 42 composed of a pulse motor always rotates by the same angle with respect to the number of input pulses, the Z-axis table 31, ie,
Each lower surface displacement meter 52 moves by the same amount as the movement amount stored in the RAM.

Incidentally, when the lower surface displacement meter 52 is moved by a predetermined amount, position control by a semi-closed loop which has relatively few components and is relatively easy to control is generally known. However, in the case of this method, it is difficult to accurately control the position of the displacement meter corresponding to the moving secondary side, even though the primary drive side of the servomotor or the like can be accurately controlled. However, in the film thickness control device 61 of the present embodiment, since the Z-axis motor 42 is controlled by accurately measuring the movement amount by the external measuring device, the position of the lower surface displacement meter 52 must always be accurately controlled. Is easy.

Then, the control device 61 sets the predetermined movement amount Z
After accurately moving the lower surface displacement meter 52 by a, the distance K1 to the lower surface of the glass substrate 16 is measured. The lower surface displacement meter 52 is fixed to the Z-axis table 31, and the Z-axis table 31 is moved by the Z-axis motor. Therefore, the upper surface displacement meter 51 is also moved downward by the same amount.
In FIG. 1B, the positions of the upper surface displacement meter 51 and the lower surface displacement meter 52 after the movement are indicated by the alternate long and short dash line so that the distance between the lower surface displacement meter 52 and the lower surface of the glass substrate 16 can be easily understood. Although it is illustrated in FIG.

The movement amount Za for moving the lower surface displacement meter 52 is set in advance so that the lower surface displacement meter 52 can measure the distance to the lower surface of the glass substrate 16, similarly to the initial position of the Z-axis table 31. Is set. Normally, the thickness of the glass substrate 16 is about 3 mm, and the measurement range is narrow with a high-precision laser displacement meter. Therefore, the distance to the upper surface and the distance to the lower surface of the glass substrate 16 should be measured with one displacement meter. Can not. On the other hand, in a displacement meter having a wide measurement range, the measurement accuracy is low, and the displacement meter itself is large, resulting in an increase in the size of the device. Therefore, the distance to the upper and lower surfaces of the glass substrate 16 can be accurately measured by moving the lower surface displacement meter 52 composed of a high-precision laser displacement meter by a certain amount corresponding to the thickness of the glass substrate 16. . Also,
The amount of eccentricity of the pair of cams 44 is set in accordance with the amount of movement of the lower surface displacement meter 52.

Then, the controller 61 determines the measured distance K2 to the upper surface of the glass, the distance K1 to the lower surface of the glass substrate 16 after the movement, and the upper surface of the glass substrate 16 due to the refraction of the glass based on the predetermined movement amount Za. Is calculated as the offset value K3. At this time, the glass substrate 16
The distance G1 from the lower surface to the offset upper surface is expressed as G1 = K2 + Za-K1. Also, the actual thickness G of the glass substrate 16
2 is expressed as G2 = G1 * G, where G is the refractive index of glass. Therefore, the offset amount K3 on the upper surface of the glass substrate 16 can be calculated from the above equation as follows: K3 = G2-G1 = G1 * G-G1 = (K2 + Za-K1) * G- (K2 + Za-K1) = (K2 + Za-K1) * (G-1) --- (2) With the offset amount K3, the distance K2 to the lower surface of the film 17 measured including the refractive index is corrected, and the actual distance from the lower surface displacement meter 52 to the lower surface of the film 17 (= K2 +
K3) is required.

Next, according to FIG.
Measures the thickness of the film 17 as the film to be measured. The control device 61 drives and controls the Z-axis motor 42 to move the Z-axis table 31 to the initial position. In this state, the control device 6
1 is a distance a2 from the upper surface displacement meter 51 to the upper surface of the film 17.
Is measured. Further, the control device 61 measures the distance b2 to the lower surface of the film 17 by transmitting the glass substrate 16 with the lower surface displacement meter 52.

At this time, the distance b2 to the lower surface of the film 17 is a value offset by the offset amount K3 due to the influence of the refractive index of the glass as described above. And
Since the distance d between the two displacement meters 51 and 52 is constant, the thickness m of the film 17 to be obtained is m = d-a2-b2-K3 (3). Therefore, from Equations (1) and (2), m = (a1 + b1 + c) -a2-b2- (K2 + Za-K1) * (G-1) --- (4) Is calculated.

By the way, the displacement meter is usually adjusted on the premise that measurement is performed in the atmosphere. When measuring the distance from the glass substrate 16 to the lower surface of the film 17 as described above, the laser light emitted from the displacement meter is affected by the refractive index of the glass. In this case, it is possible to calculate an accurate distance by performing correction using the refractive index of the glass. However, the refractive index of commonly known glass is the refractive index at a specific wavelength. Therefore, since the refractive index differs depending on the wavelength of the laser beam of the displacement meter used, the calculated distance to the lower surface of the film 17 deviates from the actual distance, and the thickness of the film 17 cannot be accurately calculated.

Therefore, in FIG. 1C, the same film thickness measurement as described above is performed on the glass substrate 16 on which the film 17 is not formed. In the above equation (4), by setting the film thickness m to 0 (zero), the refractive index of the glass at the wavelength of the laser beam emitted from the displacement meter used can be obtained. That is, from the equation (4), if m = (a1 + b1 + c) -a2-b2- (K2 + Za-K1) * (G-1) = 0- (5) The refractive index G can be calculated as G = (((a1 + b1 + c) -a2-b2) / (K2 + Za-K1)) + 1 (6). In equation (6), the distance a2 is a distance to the surface of the glass substrate 16 where the film 17 is not formed, that is, the upper surface of the glass substrate 16 measured by the upper surface displacement meter 51.

Then, the refractive index of the glass is calculated for each pair of displacement meters 51 and 52 and stored in the RAM. Using the stored refractive index of the glass, the control device 61 can accurately calculate the thickness of the film 17 by the above equation (4). Further, by calculating and storing the refractive index of the glass for each pair of displacement meters, the difference between the respective displacement meters (difference in the wavelength of the laser beam to be used) is simultaneously corrected and the thickness of the film 17 is adjusted. Can be calculated accurately.

As described above, the present embodiment has the following advantages. The displacement of the lower surface of the glass substrate 16 is measured by moving the lower surface displacement meter 52 by a predetermined amount Za, and a correction value for the refractive index of the glass is calculated based on the measurement result. Then, the displacement amount a of the upper surface of the film 17 measured by the upper surface displacement meter 51
2, a displacement amount b2 of the lower surface of the film 17 measured by the lower surface displacement meter 52, an offset amount K3 as a correction value, and a distance d between the two displacement meters 51 and 52, to calculate a film thickness m of the film 17. I did it. As a result, even if the thickness of the glass substrate 16 fluctuates, the thickness of the glass substrate 16 is corrected, so that the thickness m of the film 17 formed on the upper surface of the glass substrate 16 can be accurately measured.

The offset K3 calculated as the correction value
Is obtained by measuring the distance to the upper surface of the glass substrate 16 offset by the refractive index and the distance to the lower surface of the glass substrate 16. Therefore, even if the thickness of the glass substrate 16 itself varies, the distance to the upper surface of the glass substrate 16, that is, the film 17
Since the distance to the lower surface of the can be accurately measured,
The thickness of the film 17 can be accurately measured.

The present invention may be carried out in the following modes in addition to the above embodiment. In the above embodiment, the thickness of a film formed on the surface of a substrate other than the glass substrate 16 through which measurement light can pass may be measured.

In FIG. 1B of the above embodiment, when the correction value is calculated, when the displacement amount of the upper surface of the glass substrate 16 offset by the lower surface displacement meter 52 is measured, the film 17 is also measured by the upper surface displacement meter 51. After the displacement amount of the upper surface of the film 17 is measured, the offset amount K3 is calculated, and then the film thickness m of the film 17 may be calculated using the offset amount K3.

[0068]

As described above in detail, according to the first to sixth aspects of the present invention, even if the thickness of the object to be measured fluctuates, the thickness of the film to be measured formed on one surface of the object to be measured can be improved. It is possible to provide a film thickness measuring method capable of accurately measuring a film thickness.

According to the present invention, even if the thickness of the object to be measured fluctuates, the thickness of the film to be measured formed on one surface of the object to be measured is accurately measured. It is possible to provide a film thickness measuring device capable of performing the above.

[Brief description of the drawings]

FIGS. 1A to 1C are explanatory diagrams showing a film thickness measuring method.

FIG. 2 is a schematic front view of a film thickness measuring device according to one embodiment.

FIG. 3 is a partially broken plan view of the film thickness measuring apparatus according to one embodiment.

FIG. 4 is a partially broken side view of the vertical movement mechanism.

FIG. 5 is a detailed explanatory view of the upper and lower displacement meter mounting portions.

FIG. 6 is a detailed explanatory view of the upper and lower displacement gauge mounting portions.

FIG. 7 is an electric configuration block diagram of a film thickness measuring apparatus according to one embodiment.

[Explanation of symbols]

 Reference Signs List 16 Glass substrate as substrate 17 Film 51 Upper surface displacement meter 52 Lower surface displacement meter m Film thickness K3 Offset amount as correction value

Claims (12)

[Claims] 1. A film thickness measuring method for measuring a film thickness of a film formed on one surface of a substrate, wherein an upper surface displacement meter is provided on each of an upper surface side on which the film is formed and a lower surface side on which the film is not formed. And a lower surface displacement meter are arranged at a predetermined interval, measurement light of the lower surface displacement meter arranged on the lower surface side of the substrate is transmitted through the substrate to measure a displacement amount of the film lower surface, and the lower surface displacement meter is preset. The amount of displacement of the lower surface of the substrate is measured by moving by a given amount, and a correction value for the thickness of the substrate is calculated based on the amount of displacement of the lower surface of the film, the amount of displacement of the lower surface of the substrate and the amount of movement of the lower surface displacement meter. The distance between the two displacement meters, the amount of displacement of the film upper surface measured by the upper surface displacement meter, the amount of displacement of the film lower surface measured by the lower surface displacement meter, and the calculated correction value of the film based on A film thickness measuring method for calculating a film thickness. 2. The film thickness measuring method according to claim 1, wherein the lower surface of the film is offset by a refractive index of a substrate, and the lower surface displacement meter is offset by transmitting measurement light through the substrate. A film thickness measuring method comprising: measuring a displacement amount of the substrate; and calculating an offset amount in which the lower surface of the film is offset by a refractive index of the substrate material as a correction value for the thickness of the substrate. 3. The film thickness measuring method according to claim 1, wherein a displacement amount of the film lower surface measured by passing through the substrate;
The displacement amount of the lower surface of the substrate measured by the lower displacement meter after the movement and the thickness of the substrate including the refractive index calculated based on the displacement amount of the lower displacement meter are multiplied by the refractive index of the substrate. A thickness measuring method for calculating the correction value by calculating the actual thickness of the substrate and subtracting the thickness of the substrate including the refractive index from the actual thickness. 4. The method according to claim 1, wherein before measuring the film thickness of the film, a reference having a predetermined thickness between the two displacement meters. A film thickness measuring method comprising: disposing a gauge, measuring displacement amounts of upper and lower surfaces of the reference gauge with upper and lower displacement meters, and calculating a distance between the two displacement meters based on the measurement result. 5. The film thickness measuring method according to claim 1, wherein a refractive index of the substrate with respect to a wavelength of measurement light of the lower surface displacement meter is obtained, and the refractive index is used. A film thickness measuring method for calculating the correction value. 6. The film thickness measuring method according to claim 5, wherein the upper surface displacement meter measures a displacement amount of an upper surface of a substrate on which a film is not formed, and the lower surface displacement meter transmits the substrate. Measuring the amount of displacement of the upper surface of the substrate, measuring the amount of displacement of the lower surface of the substrate by moving the lower surface displacement meter, and the displacement amounts, the amount of movement of the lower surface displacement meter, and the distance between the two displacement meters. A film thickness measuring method for calculating the refractive index of the substrate based on 7. A film thickness measuring device for measuring a film thickness of a film formed on one surface of a substrate, comprising: an upper surface displacement meter arranged on an upper surface side of the substrate on which the film is formed; A lower surface displacement meter disposed on the lower surface side of the substrate that is not subjected to the upper surface displacement meter, and a measurement light of the lower surface displacement meter disposed on the lower surface side of the substrate is transmitted through the substrate to form a lower surface of the film lower surface. First measuring means for measuring a displacement amount, a vertical movement mechanism for moving the lower surface displacement meter by a predetermined amount, and second measuring means for measuring the displacement amount of the lower surface of the substrate by the moved lower surface displacement meter Correction value calculation means for calculating a correction value for the thickness of the substrate based on the measurement results of the first and second measurement means and the amount of movement of the lower surface displacement meter by the vertical movement means; The displacement of the upper surface of the film is measured by a meter A film thickness measurement unit comprising: a third measurement unit; and a film thickness calculation unit that calculates a film thickness of the film based on a measurement result of the first to third measurement units and a correction value calculated by the correction calculation unit. apparatus. 8. The film thickness measuring device according to claim 7, wherein the film thickness measuring device is supported by a frame so as to be movable in a vertical direction of the substrate,
The substrate includes a frame-shaped table through which the substrate passes, the upper surface displacement meter and the lower surface displacement meter are fixed to the table, and the vertical movement mechanism moves the table up and down by a predetermined amount. Film thickness measuring device. 9. The film thickness measuring device according to claim 7, wherein the up-and-down moving mechanism rotates a pair of eccentric cams arranged at a predetermined interval from a center of gravity of the table. The eccentric cam is provided to protrude from the frame.
A film thickness measuring device in which the table is supported by being engaged with a pair of pins, and the eccentric cam is rotationally driven by the motor to move the table up and down. 10. The film thickness measuring device according to claim 9, wherein a bearing is provided on an outer periphery of the eccentric cam, and an outer periphery of the bearing is engaged with the pin. 11. The film thickness measuring device according to claim 7, wherein a reference gauge having a predetermined thickness is arranged between the displacement gauges, and upper and lower surfaces of the reference gauge. Distance measuring means for measuring the amount of displacement of the upper and lower displacement meters and calculating the distance between the two displacement meters, wherein the film thickness calculating means, based on the distance calculated by the distance calculating means A film thickness measuring device for calculating the film thickness of the film. 12. The refraction apparatus according to claim 7, wherein a refraction index of the substrate with respect to a wavelength of measurement light of the lower surface displacement meter is calculated based on the measurement results. A film thickness measuring apparatus comprising: a ratio calculating unit, wherein the correction value calculating unit calculates the correction value based on the calculated refractive index.