JPH02311704A - Transparent linear film thickness measuring device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Summary] A film thickness measuring device that optically measures the film thickness of a transparent linear film on a sample in which a transparent linear film is formed directly or via a transparent film on a substrate. With the aim of making it possible to measure the film thickness of a transparent linear film with a simple configuration, we have developed an irradiation optical means that irradiates a slit light across the transparent linear film to form a light cutting line; an imaging means for capturing an image of a light cutting line; extracting an image of the light cutting line formed on the substrate surface from the captured light cutting line image; an image processing means for measuring a displacement interval; a film thickness calculation means for calculating a film thickness of the transparent linear film using the displacement interval, an incident angle of slit light with respect to the sample, and a refractive index of the transparent linear film; , and configure it.

[Industrial application field]

The present invention relates to a film thickness measuring device for optically measuring the film thickness of a transparent linear film on a sample in which a transparent linear film is formed directly or via a transparent film on a substrate.

[Conventional technology]

Optical sectioning is used to measure the thickness of linear objects such as printed wiring. Further, an ellipsometer is used to measure the thickness of a transparent film.

[Problem to be solved by the invention]

However, since the conventional light cutting method uses reflected light from the surface of the dough, it cannot be applied to transparent linear materials whose reflectance is extremely low. Further, the ellipsometer uses a stabilized laser, an analyzer, a polarizer, an optical modulator, etc., and therefore has a complicated configuration.

SUMMARY OF THE INVENTION In view of these problems, an object of the present invention is to provide a film thickness measuring device that can measure the thickness of a transparent linear film with a simple configuration.

[Means to solve the problem]

FIG. 1 shows the basic structure of a transparent linear film thickness measuring device according to the present invention. This device is used for a sample 1 in which a transparent linear film 1c is formed on a base material 1a directly or via a transparent film 1h.
The film thickness d1 of the transparent linear film 1c is optically measured.

In the figure, reference numeral 2 denotes a light irradiation optical means, which irradiates a slit light 3 across the transparent linear film 1c to form a light cutting line 4.

Reference numeral 5 denotes an imaging means, which images the optical cutting line 4.

Reference numeral 6 denotes an image processing means, which extracts an image of the light section line formed on the surface of the base material 1a from the photographed light section line image, and calculates the deviation interval due to the transverse cutting with respect to the extracted light section line image. Measure.

7 is a film thickness calculating means, which calculates the deviation interval, the incident angle θ of the slit light with respect to the sample l, and the refractive index n of the transparent linear 1!1c.
1 to calculate the film thickness d1 of the transparent linear film 1c.

[Effect]

FIG. 2 shows the optical path of the slit light 3 with respect to the sample 1. Hereinafter, a line segment refers to a line segment perpendicular to the paper surface of the second drawing.

Sample 1 consists of a transparent wire 11 placed on a base material 1a via a transparent film 1b.
c is formed. The middle part of the slit light 3 is located on the transparent linear film 1c, is refracted by a line segment A in the surface Sl, is refracted by a line segment B in the surface S2 of the transparent Mlb, and is refracted by a line segment B in the surface S2 of the transparent linear film 1c. It is reflected by a line segment C in the surface S3, refracted by a line segment in the surface S2 of the transparent film 1b, and then refracted by a line segment E in the surface Sl of the transparent linear film 1c to become reflected light 3d. on the other hand,
Both ends of the slit light 30 are located on the side of the transparent linear film 1c and on the transparent film lb, and are refracted by a line segment F in the surface S2 of the transparent film 1b, and are refracted by a line segment in the surface S3 of the base material 1a. G, and refracted by the line segment H in the surface S2 of the transparent film 1b, resulting in reflected light 3.
It becomes C.

The reflected light 3a on the line segment A and the reflected light 3b on the line segment F are reflected light on the surface of the transparent film, and therefore have a lower light intensity than the reflected light 3c and the reflected light 3d. Also, as shown in Figure 3,
The optical section line formed on the line segment C is shifted from the optical section line formed on the line segment G. The light-section line image captured by the imaging means 5 is a line segment G', C on the extension surface of the reflected light 3cs 3d.
', and the shift interval W on the image is 3C% of reflected light 3d
When the imaging magnification is equal to the same magnification, it is expressed by the following formula.

W = 2dl (tanθ-tanθ1)cosθ-
--(1) Here, θ and θ1 are the incident angle and refraction angle of the slit light 3 with respect to the surface S1, respectively, and dl is the film thickness of the transparent linear 1!1c.

From the above formula (1), the thickness d1 of the transparent linear film 1c is expressed by the following formula.

dl=W (2(tanθ-tanθ1) co8θ
)-' (2) Furthermore, if the refractive index of the transparent linear film 1c is nl, the following equation holds true according to Snell's law.

θ1=sin −' (sinθ/n1)...(3
) Therefore, using W2O and nl, the transparent linear l1l
The film thickness d1 of C can be determined. As can be seen from the above equation (2), the film thickness d1 does not depend on the film thickness d2 of the transparent film 1b, the refractive index 02, and the refraction angle θ2 within the transparent film 1b. Therefore, the above formula (2) holds true even when the film thickness d2 of the transparent film 1b is zero. Furthermore, even if the transparent film 1b is formed from a plurality of layers having different refractive indexes, the above formula (2) holds true.

Therefore, according to the present invention, the thickness of a transparent linear film can be measured with a simple configuration.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 4 shows the configuration of a film thickness measuring device for a transparent linear film.

On the X-Y stage 10, as in FIG.
A sample 1 on which a transparent linear film 1c is formed with a transparent film 1b interposed thereon is placed. This sample 1 is irradiated with slit light at an incident angle θ. That is, the laser beam emitted from the laser 12 is expanded in diameter and parallelized by the beam expander 14, passes through the cylindrical lens 16, becomes a slit beam, and an optical cutting line is formed on the surface of the sample 1 and each boundary surface in the direction perpendicular to the plane of the paper. It is formed. This optical cutting line is the x-Y stage 1
The image is captured by an imaging device 18 placed on the 0. The video signal taken out from the imaging device 18 is sent to the A/D converter 2.
0 and is converted into digital data by the microcomputer 22.
is loaded into.

FIG. 4 shows the software configuration of the microcomputer 22 using functional blocks.

The luminance data output from the A/D converter is written into the image storage section 22a to form an image of the optical cutting line. From this image, the deviation determination unit 22b determines whether or not there is a deviation in the light section line image as shown in FIG. If there is this deviation, that is, if the optical cutting line crosses the transparent linear film 1c as shown in FIG. 1, the film thickness is measured as follows.

First, the principal ray section line image extracting section 22c extracts only images corresponding to the optical section lines formed in the line segments G and C shown in FIG. 2 (hereinafter referred to as principal ray section lines). This means that the principal ray section line is line segments A and B.

Since the brightness is sufficiently higher than the image of the light section line formed in F, it can be determined whether it is the principal light section line based on the magnitude of the peak of the brightness. FIG. 5 shows the extracted principal light section line image.

Next, the peak position detection afs 22d detects a peak position on a certain line segment of the principal beam section line image. For example, in FIG. 5, the peak position P%Q in the luminance distribution along the principal ray section line (a straight line passing through the longitudinal midpoints of ILL, L2, and L3 and perpendicular to Ll, L2, and L3, respectively)
and R are detected.

FIG. 6 shows the brightness along lines A-A and B-B in FIG.

Next, the shift interval measuring section 22e measures the shift interval W of the principal beam section line image. This is the straight line P in Figure 5.
This is done by finding the shortest distance between Q and point R'.

Next, the film thickness calculating unit 22f uses this shift interval W, the incident angle θ set by the setting device 24, and the refractive index nl of the transparent linear film 1c, and calculates the value based on the above equations (2) and (3). The film thickness di of the transparent linear film 1c is calculated and supplied to the recorder 26.

At this time, the measurement position calculation section 22g
In response to the determination that there is a shift based on b, the coordinates (X, Y) supplied from the x-y stage 10 are converted to the slit light irradiation position on the sample 1 and supplied to the recorder 26.

The film thickness d1 is calculated by the film thickness calculation unit 22f, or
Determine the presence or absence of deviation! 22b, when it is determined that there is no deviation, the stage controller 28 drives the XY stage 10 in steps.

By repeating the above process, the film thickness distribution of the transparent linear film 1c formed on the sample 1 is recorded on the recorder 26.

Note that the present invention includes various other modifications.

For example, if a binarization circuit is used instead of the A/D converter 20, only the chief beam section line image can be written in the image storage section 22b. In addition, the shift interval W is the principal light section line L1,
A configuration may be adopted in which a plurality of peak positions as described above are detected and measured for each of L2 and L3.

〔Effect of the invention〕

In the film thickness measuring device for a transparent linear film according to the present invention, a slit light is irradiated across the transparent linear film to form a light cutting line, an image of this light cutting line is taken, and the imaged light cutting line is Among the images, for the image of the light cutting line formed on the substrate surface, the deviation interval due to the cross-cutting is measured, and the transparent Since the film thickness of the linear film is calculated, the excellent effect of being able to measure the film thickness of the transparent linear film with a simple configuration is achieved.

[Brief explanation of the drawing]

1 to 3 relate to the present invention; FIG. 1 is a diagram of the principle configuration of the present invention; FIG. 2 is an optical path diagram of a slit light beam relative to a sample; and FIG. 3 is a diagram showing light cutting in correspondence with FIG. It is a layout diagram of lines and their images. 4 and 5 relate to an embodiment of the present invention, in which FIG. 4 is a configuration diagram of a film thickness measuring device, FIG. 5 is a graph of brightness along line AA and line BB in FIG. 5. FIG. In the figure, 12 is a laser 14, a beam expander 16, a cylindrical lens 18, an imaging device 20, an A/D converter 22, a microcomputer 22a, an image storage section 22c, a chief ray section line image extraction section 22d, a peak position detection section 22e. Discrepancy interval measurement part Figure 1 Running cut-off point (V building) and 70-point line (iL) Figure 3 degree figure 6

Claims (1)

[Claims] For the sample (1) in which a transparent linear film (1c) is formed on a substrate (1a) directly or via a transparent film (1b), a film of the transparent linear film (1c) is In a film thickness measuring device that optically measures the thickness (d1), a slit light (3) is emitted across the transparent linear film (1c).
an irradiation optical means (2) for irradiating to form a light cutting line (4);
); an imaging means (5) for capturing an image of the light cutting line; extracting an image of the light cutting line formed on the substrate surface from among the captured light cutting line images; an image processing means (6) for measuring the deviation interval (W) due to the transverse traversal of the line image, the deviation interval (W), the incident angle (θ) of the slit light on the sample, and the refractive index of the transparent linear film. Film thickness calculation means (7) for calculating the film thickness (d1) of the transparent linear film using (n1)
A film thickness measuring device for a transparent linear film, comprising: