JPH0510727A - Thin film inspection apparatus and its inspection method - Google Patents

Abstract

PURPOSE:To make the thin films uniformity inspection efficient. CONSTITUTION:A thin film inspection apparatus is composed of a light source 4, a monochrometer 5, a light intensity detector 6 facing to the monochrometer 5, a stage 10 to support a substrate 2 coated with a thin film 3, a radiation light controller 9 to control the wavelength of the radiation light 17, a stage controller 11 to drive the stage 10 so that the radiation light 17 scans the thin film 3, a detected light controller 12 to control the wavelength of the detection light to be detected by the light intensity detector 6, a controlling processing apparatus 13 to control the stage 10, the radiation light controller 9, and the detected light controller 12 and carry out data processing of output signals from the light intensity detector 6, and output apparatus 14, 15 to make the output signals from the controlling processing apparatus 13 into visible data. Using the apparatus, the uniformity of the thickness of a thin film 3 is inspected based on the light transmitted through the thin film 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inspection apparatus and an inspection method for a thin film deposited on a transparent substrate, and more particularly to an inspection of film thickness uniformity.

In recent years, the speeding up and increasing the capacity of computers have been remarkably advanced, and accordingly, further refinement of semiconductor device manufacturing technology is required. Therefore, it is necessary to inspect the thin film efficiently and highly accurately.

[0003]

2. Description of the Related Art Conventionally, as a method for inspecting the thickness of a thin film used for a semiconductor device, there are known an optical interference method, an X-ray method, a stylus method, an optical observation method of a cross section, a spectrum method using a laser beam and the like. Has been. These conventional methods are suitable for measuring the film thickness in a small range, but when applied to the uniformity inspection of thin films deposited on the entire semiconductor wafer and large substrates such as liquid crystal display panels, distortion of the wafer and the substrate itself, It is difficult to separate the influence of the height deviation of the board mounting table from the measured value.

In particular, when the length of one side of the thin film is 25 cm or more as in a liquid crystal display panel, it takes too much time to inspect the uniformity of the thin film by the conventional method.

[0005]

As described above, according to the conventional film thickness inspection method, the film thickness in a small range is 1% or 2%.
Å Can be measured with high accuracy. However, when trying to efficiently measure the uniformity of the film thickness over a wide range, there is a problem that it is unsuitable due to the strain of the substrate itself, and that it takes too much time.

[0006]

According to the present invention for solving the above-mentioned problems, according to FIG. 1, the uniformity of the thickness of the thin film 3 deposited on the transparent substrate 2 is measured by the change of the light transmittance. The light intensity detector 6, which faces the light source 4 through the light source 4, the monochromator 5 that transmits light of a specific wavelength, and the monochromator 5, and the substrate 2 includes the monochromator 5 and the light intensity detector 6. 10, the irradiation light controller 9 that controls the wavelength of the light 17 that radiates the thin film 3 through the monochromator 5, so that the light 17 that illuminates the thin film 3 scans the entire surface of the thin film 3. A stage controller 11 that moves the stage 10 in two axial directions, a detection light controller 12 that controls the wavelength of the detection light that the light intensity detector 6 detects from the transmitted light that has passed through the thin film 3, a stage 10, an irradiation light controller 9, and detection Light control And a control processing device 13 for controlling the image data output signal from the light intensity detector 6 and output devices 14 and 15 for converting the output signal from the control processing device 13 into visible data. It is a thin film inspection device, and in the uniformity inspection of the thin film thickness using the thin film inspection device, the wavelength of the detection light by the detection light controller 12 is the same as the wavelength of the irradiation light 17 by the irradiation light controller 9. And, in the uniformity inspection of the thin film thickness using the thin film inspection apparatus, an opaque mask showing the required portions of the thin film 3 deposited on the transparent substrate 2 is placed on the thin film 3 and the stage 10 is moved. , Inspecting the uniformity of the thin film 3 at required locations. Further, in the uniformity inspection of the thin film thickness using the thin film inspection apparatus, the stage 10 is moved to move the entire thin film 3. Scanning of the irradiation light 17 to follow is a thin film inspection method characterized by a repeating zig-zag course of shifting to a predetermined direction.

[0007]

The above-mentioned means is a thickness uniformity test that utilizes the fact that the light transmittance decreases as the thickness of the thin film differs from that in which the absolute value of the thickness of the thin film is measured. Therefore, the device of the present invention comprises a wavelength controller for irradiation light and a wavelength controller for detection light because it is necessary to select the wavelength of light to be irradiated and the wavelength of light to be detected depending on the physical properties of the thin film.
The test sample in which the thin film is applied to the transparent substrate is mounted on a stage that moves in two axis directions so that the irradiation light can scan the entire surface of the thin film.

Furthermore, the inspection accuracy is improved by controlling the wavelength of the irradiation light and the wavelength of the detection light to be the same, and by using a mask that exposes the required portion of the sample to be tested, the irradiation light is repeated by repeating the zigzag course. By irradiating the thin film on the thin film, the wide area inspection is made efficient.

[0009]

1 is a system diagram of a thin film inspection apparatus according to the present invention. In FIG. 1, 1 is a test sample in which a thin film 3 is coated on a transparent substrate (glass substrate) 2, 4 is a light source that emits light toward the thin film 3, 5 is a monochromator that transmits light of a single wavelength, 6 Is a light intensity detector (photomultiplier) for measuring the intensity of light transmitted through the thin film 3, 7 is an amplifier for amplifying the output signal (voltage) of the light intensity detector 6, and 8 is an XY connected to the amplifier 7. A recorder, 9 is an irradiation light controller that controls the wavelength of light that passes through the monochromator 5 and irradiates the thin film 3, 10 is a stage on which the inspection sample 1 is mounted, and 11 is irradiation light 17 that irradiates the thin film 3 with the entire surface of the thin film 3. A stage controller for moving the stage 10 in two axial directions so as to scan the beam, and 12 is a light intensity detector 6 from the transmitted light transmitted through the thin film 3.
Detection light controller, which controls the wavelength of light detected by
Is a control processing device (personal computer) that controls the irradiation light controller 9, the stage controller 11, and the detection light controller 12, and the control device 13 passes through the amplifier 7.
The thickness distribution signal of the thin film 3 input to is printed by the printer 14 and displayed on the display panel 15.

The monochromator 5 which transmits the light of the single wavelength from the light 16 emitted from the light source 4 transmits the irradiation light 17 of the single wavelength selected from, for example, 380 nm to 780 nm by the irradiation light controller 9. The wavelength of the irradiation light 17 is the thin film 3
Set to a value suitable for detecting the thickness variation from the spectrum of.

The light intensity detector 6 on which the transmitted light 18 transmitted through the thin film 3 when irradiated with the irradiation light 17 is set in advance by the detection light controller 12 so as not to be affected by incident light from the outside. Convert light of wavelength to electric quantity,
Output as an electric signal. The electric signal is amplified by the amplifier 7 and recorded in the XY recorder 8, and the control device
13 to display on the display panel 15
Record at 14.

The stage 10 moves in the two axial directions of the inspection sample 1 in the vertical direction and the width direction (thickness direction of the drawing paper), and reciprocates in the width direction while shifting by a fixed amount in the vertical direction to form a thin film. Irradiation light 17 is applied to the entire surface of 3. Therefore, when the irradiation light 17 is a light flux having a diameter of 1 mm, the vertical shift amount is 1 mm or less, and when the width direction length of the thin film 3 is 150 mm, the irradiation light 17 moves in the width direction more than 150 times. Become.

Therefore, when the stage 10 is moved in the width direction and the stage 10 is reciprocated in the vertical direction at an appropriate amplitude, for example, an amplitude of 10 mm, the scanning line of the irradiation light 17 is moved. Will draw a sine wave (zigzag course), and the scanning frequency of the irradiation light 17 is
The test efficiency is improved to 10.

FIG. 2 shows an example of the transmitted light output distribution obtained by actually measuring the uniformity of the thin film by the apparatus of the present invention shown in FIG. 1, and FIG. 3 shows the output distribution on the straight line connecting the points X _-1 and X _-2 in FIG. X-Y
FIG. 4 is a schematic diagram of recording with a recorder, and FIG. 4 is a diagram showing a relationship between film thickness and light transmittance. However, the thin film of FIG. 2 is a glass substrate coated with a red pixel thin film for color filters, and the thin film of FIG. 4 is a glass substrate coated with a transparent conductive film.

In FIGS. 2 and 3, in the thickness distribution 19 of the thin film indicated by the grid line, a thick portion (low transmittance portion) is detected in the portion near the center and the upper left corner. Generally, in such a film thickness uniformity inspection, the transmittance of the thin film is T, the intensity of the detection light transmitted through the thin film is I, the intensity of the irradiation light for irradiating the thin film is I ₀ , the film thickness is d, and the irradiation of the thin film is performed. When the light absorption coefficient is k, it follows the formula ^expressed by T = I / I ₀ = e ^−kd .

FIG. 4 is a simulation showing the relationship between the film thickness of the transparent conductive film (ITO film) and the transmittance. In FIG. 4, where the horizontal axis represents the thickness (μm) of the transparent conductive film and the vertical axis represents the light transmittance, the solid line T ₋₁ in the figure indicates that the transmittance is 90 when the thickness is 1 μm.
%, The transmittance characteristic of the transparent conductive film, the broken line T _-2 in the figure is the transmittance characteristic of the transparent conductive film having a transmittance of 50% when the thickness is 1 μm. Decreases with increasing.

FIG. 5 is a spectrum of a red pixel thin film for a color filter used in a liquid crystal display panel. In FIG. 5, the vertical axis is the transmittance (%) of the irradiation light, the horizontal axis is the wavelength (nm), and the solid line in the figure is the spectral characteristic of the red pixel thin film with a thickness of 1.9 μm, the dashed line in the figure. Is the spectral characteristics of a red pixel thin film having a thickness of 2.4 μm.

In order to inspect the uniformity of the thin thickness by the transmitted light, it is necessary to select the irradiation light wavelength capable of detecting the uniformity based on the transmitted light characteristic of the thin film. Therefore,
Irradiation (detection) used for thickness uniformity inspection of red pixel thin film
For light, the change in transmittance with respect to the change in thickness is stable,
In addition, as a wavelength range that is stable with respect to wavelength fluctuation,
It is more desirable to set it to 450 nm to 550 nm.

6A and 6B are explanatory views of an embodiment of the present invention applied to a thickness uniformity test of a color-specific pixel film in a color filter. FIG. 6A is a schematic plan view of the color filter, and FIG. 6B is a color filter. FIG. 4C is a cross-sectional view, FIG. 6C is a plan view of a mask for inspecting a color-specific pixel film, and FIGS. 4D, 4E, and 4F are plan views for explaining the color-specific pixel film inspection method.

In FIGS. 6A and 6B, the color filter 21 forms a black mask 23 having a large number of pixel through holes on the surface of a transparent (glass) substrate 22, and fills the through holes. A large number of red pixels R, green pixels G, and blue pixels B are formed respectively. In such a color filter 21,
The wavelength of the illuminating light used to test the thickness uniformity of the pixels R, G, B depends on the pixels R, G, B.

In FIG. 6C, a mask 24 prepared for testing the thickness uniformity of the pixels R, G, B has a light-shielding film 25 deposited on a glass substrate, and the light-shielding film 25 has a large number of through holes. Formed 26. Such a mask 24 covers the pixels G and B when testing the thickness uniformity of the pixel R, and covers the pixels R and B when testing the thickness uniformity of the pixel G. It will cover pixels R, G when testing for thickness uniformity.

In FIG. 6D, the mask 24 for testing the thickness uniformity of the red pixels R is overlaid on the color filter 21 so that the red pixels R are displayed in the through holes 26, and the state is shown in FIG. Such a thin film inspection apparatus is mounted, and a large number of red pixels R are sequentially irradiated with inspection irradiation light to inspect their uniformity. As a result, the transmitted light (detection output) becomes zero when the irradiation light is applied to the mask 24, and the thickness uniformity of the red pixel R is known from the output variation when the irradiation light is applied to the red pixel R. You can

In FIG. 6 (e), the mask 24 for testing the thickness uniformity of the blue pixel B is overlaid on the color filter 21 so that the blue pixel B appears in the through hole 26, and the state is shown in FIG. It is mounted on such a thin film inspection apparatus, and a large number of blue pixels B are sequentially irradiated with inspection irradiation light to inspect their uniformity. As a result, the transmitted light (detection output) becomes zero when the irradiation light irradiates the mask 24, and the thickness uniformity of the blue pixel B can be known from the output fluctuation when the irradiation light irradiates the blue pixel B. You can

In FIG. 6F, the mask 24 for testing the thickness uniformity of the green pixel G is overlaid on the color filter 21 so that the green pixel G is displayed in the through hole 26, and the state is shown in FIG. Such a thin film inspection apparatus is mounted, and a large number of green pixels G are sequentially irradiated with inspection irradiation light to inspect their uniformity. As a result, the transmitted light (detection output) becomes zero when the irradiation light irradiates the mask 24, and the thickness uniformity of the green pixel G can be known from the output fluctuation when the irradiation light irradiates the green pixel G. You can

[0025]

As described above, the inspecting apparatus and the inspecting method of the present invention are for inspecting the uniformity of the film thickness by the intensity of the transmitted light transmitted through the thin film. Compared to thickness uniformity inspection, it has the effect of enabling high-efficiency and wide-range measurement. Furthermore, by controlling the irradiation light wavelength and the detection light wavelength to be the same, and by using a mask that exposes the required portion of the sample to be tested, data processing is simplified and inspection accuracy is improved, resulting in a zigzag course. By adopting a method of irradiating the thin film with irradiation light by repeating
The inspection efficiency will be further improved.

[Brief description of drawings]

FIG. 1 is a system diagram of a thin film inspection apparatus according to the present invention.

FIG. 2 is an example of a transmitted light output distribution obtained by actually measuring the uniformity of a thin film by the device of the present invention in FIG.

FIG. 3 is a schematic diagram when a transmitted light output distribution on a line connecting X ₋₁ point and X point ₋₂ in FIG. 2 is recorded by an XY recorder.

FIG. 4 is a diagram showing a relationship between film thickness and light transmittance.

FIG. 5 is a spectrum of a red pixel thin film for a color filter used in a liquid crystal display panel.

FIG. 6 is an explanatory diagram of an example of the present invention applied to a thickness uniformity test of color-specific pixel films in a color filter.

[Explanation of symbols]

1 is an inspection sample 2 is a transparent substrate (glass substrate) 3 is a thin film 4 attached to a transparent substrate 4 is a light source 5 is a monochromator 6 is a light intensity detector (photomultiplier) 9 is a controller 10 which controls the wavelength of irradiation light Is the stage 11 on which the sample to be tested is mounted.The stage controller 12 drives the stage.The controller 12 controls the wavelength of the light detected by the light intensity detector.The controller 13 is a control processor (personal computer) 14.The printer 15 is the display panel 17. Light that illuminates the thin film (irradiation light) 18 is light that has passed through the thin film (transmitted light) 24 is an opaque mask that covers unnecessary parts of the thin film

Claims (4)

[Claims] 1. A method for measuring the thickness uniformity of a thin film (3) deposited on a transparent substrate (2) by a change in light transmittance, wherein a light source (4) transmits light of a specific wavelength. Monochromator
(5), a light intensity detector (6) facing the light source (4) through the monochromator (5), and the substrate (2) to the monochromator (5)
And a stage (1
0), an irradiation light controller (9) for controlling the wavelength of the light (17) which is transmitted through the monochromator (5) and is irradiated to the thin film (3), and the light (17) which is irradiated to the thin film (3) is A stage controller (11) for moving the stage (10) biaxially so as to scan the entire surface of the thin film (3), and the light intensity detector (6) from the transmitted light transmitted through the thin film (3). The detection light controller (12) for controlling the wavelength of the detection light to be detected, the stage (10), the irradiation light controller (9), and the detection light controller (12) to control the light intensity detector (6) A thin film inspection apparatus comprising: a control processing device (13) for data processing an output signal; and an output device (14, 15) for converting an output signal from the control processing device (13) into visible data. 2. In the uniformity inspection of thin film thickness using the thin film inspection apparatus according to claim 1, the wavelength of the detection light by the detection light controller (12) is adjusted by the irradiation light controller (9). A thin film inspection method characterized in that the wavelength is the same as that of the light (17). 3. An opaque mask for showing a required portion of a thin film (3) deposited on the transparent substrate (2) in a thin film thickness uniformity inspection using the thin film inspection apparatus according to claim 1.
A thin film inspection method characterized in that (24) is superposed on the thin film (3), the stage (10) is moved, and the uniformity of the thin film (3) at a required position is inspected. 4. Irradiation light (17) for moving the stage (10) to follow the whole surface of the thin film (3) in the thin film thickness uniformity inspection using the thin film inspection apparatus according to claim 1. Scanning is repeated zigzag course shifting in a predetermined direction.