JPH02193050A - Evaluation of defect within surface of thin film and infrared spectral analysis method and apparatus - Google Patents

Abstract

PURPOSE:To enable evaluation of a position of a defect quickly and easily by irradiating a light irradiation part of a thin film with a light energy of a fixed amplitude intermittently to determine a distribution of an AC temperature at non-irradiation part with an AC temperature of the light irradiation part as reference. CONSTITUTION:A masking member 2 is shielded so that a part of one side of a thin film 1 is not irradiated with light energy to make a light irradiation part and a non- irradiation part. When light energy of a light source 4 is made irradiate the thin film 1 intermittently with the rotation of a chopper 3, the light irradiation part of the thin film 1 is heated to raise the temperature thereof while the temperature of the non-irradiation part of the thin film 1 does not rise. Hence, there is a temperature gradient caused between the light irradiation part and the non-irradiation part and a periodical heat wave travels in both directions of the thin film 1, which allows measurement of an AC temperature using thermocouples 6A and 6B. Thus, an AC temperature distribution of the non-irradiation part is determined with an AC temperature of the light irradiation part as reference to detect a position of a defect from a change in gradient of the AC temperature distribution thereby enabling the evaluation of the position of a defect quickly and easily.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for evaluating in-plane defects in a thin film, an infrared spectroscopic analysis method, and an apparatus, and particularly relates to an in-plane defect evaluation method and an infrared spectroscopic analysis method and apparatus for thin films. The present invention relates to a quick and easy evaluation method for voids, thickness unevenness, etc., and a quick and easy infrared spectroscopy method and apparatus for thin-sheet materials.

[Conventional technology]

Conventionally known methods for evaluating in-plane defects include a method using an infrared thickness needle, a method using an ultrasonic W4 microscope, and an X-ray photograph method. Furthermore, methods such as a dispersive infrared spectroscopy method and an FT-IR method are known for measuring infrared absorption spectra.

[Problem to be solved by the invention]

However, controlling thickness unevenness using an infrared thickness gauge 1. Foreign matter detected using an ultrasonic microscope at a research site.

Evaluations of cracks and voids are being carried out, but these methods cannot detect all types of in-plane defects such as foreign particles, single grain boundaries, orientation failure, cracks, void thickness unevenness, and unevenness. Because it cannot be applied, the applicable range is narrow, and the applicable material is 1lf.
In addition, sample pretreatment and measurement require a lot of effort and time, and there are problems in that screening tests of many types and large numbers of samples and rapid measurement of large area samples in thin film manufacturing processes are not possible. Ta.

In addition, with the dispersive infrared spectroscopy method and FT-IR method, it is difficult to measure when the thickness of the sample is less than 1-10-10-10-10-20-10-200-2000-2000-2000-10000000-000000000-0000000000000000000000000 or more, or more than 1000000000000000000000000000 or more or more of a sample thickness of less than 100000000000000000000000000000000000 or more. However, there are problems in that measurement is difficult and generally requires expensive equipment.

This invention has been made in view of the above points, and its purpose is to provide a quick and easy in-plane method of thin films that can be generally applied to thin films with various defects, materials, and shapes by utilizing heat absorption and thermal diffusion of thin films. It is an object of the present invention to provide a defect evaluation method, an infrared spectroscopic analysis method, and an apparatus for in-plane defect evaluation and an infrared spectroscopic analysis that are simple in structure and inexpensive, to which these methods are applied.

[Means to solve the problem]

According to the present invention, the above-mentioned objects are as follows: 1) In a method for evaluating in-plane defects in a thin film, a light beam of a constant amplitude is applied to a light-irradiated area of a thin film that is partitioned into a light-irradiated area and a non-irradiated area by a scannable linear boundary. Energy is irradiated intermittently, the AC temperature of the light irradiated part and the non-irradiated part is measured, the distribution of the cross 71L temperature of the non-irradiated part is determined based on the AC temperature of the light irradiated part, and the gradient of this temperature distribution is calculated. 2) In an apparatus for evaluating in-plane defects in a thin film, a light source 4 that irradiates the thin film with light, a chopper 3 that cuts off light from the light source at an arbitrary period, and a chopper 3 that irradiates the thin film with light. a mask member 2 that blocks a portion of the light that is emitted to form a light irradiation part and a non-irradiation part that have linear boundaries in the thin film; and an optical sensor 7 that is installed in the optical path and detects the intermittent cycle of the irradiation light. and a temperature sensor 6 which detects the temperature of the light irradiated part and the non-irradiated part of the thin film, and in which the polarities of the temperature outputs of the light irradiated part and the non-irradiated part are connected to each other in reverse; a lock-in amplifier 8 that separates and amplifies an AC temperature component having the same frequency as the intermittent cycle detected by the sensor; a boundary scanning means 5 that moves the linear boundary between the light irradiation part and the non-irradiation part of the thin film; 3) A method for infrared spectroscopic analysis of a thin film, further comprising a temperature sensor scanning means 13 for measuring the AC temperature of the non-irradiated part of the y-thin film with reference to the AC temperature of the light-irradiated part and determining the AC temperature distribution. The light irradiation part of the thin film, which is divided into a light irradiation part and a non-irradiation part by a scannable linear boundary part, is intermittently irradiated with infrared rays of a predetermined wavelength and a constant amplitude, and a predetermined wavelength in the non-irradiation part is irradiated. 4) In an apparatus for infrared spectroscopic analysis of a thin film, a light source 4 that irradiates the thin film with light and a light source 4 that spectrally spectra the light from this light source are used. a spectrometer 9 that sends infrared rays of a predetermined wavelength to the thin film;
A chopper 3 that cuts off the infrared rays at an arbitrary period; a mask member 2 that blocks a portion of the infrared rays irradiated onto the thin film to form a light irradiated part and a non-irradiated part having linear boundaries on the thin film; and an optical path. An optical sensor 7 is installed inside and detects the intermittent cycle of the irradiated infrared rays, a temperature sensor 6 detects the alternating current temperature at a predetermined position in the non-irradiated part of the yi film, and the output of the optical sensor is determined from the output of this temperature sensor. A lock-in amplifier 8 that separates and amplifies an AC temperature component having the same frequency as the detected intermittent cycle, and a boundary scanning means 5 that moves the linear boundary between the light irradiated part and the non-irradiated part of the thin film. and 5) In the method of infrared spectroscopic analysis of thin films, this is achieved by determining the AC temperature spectrum of a specific layer from the difference between the AC temperature spectrum of a multilayer thin film containing a specific layer and the AC temperature spectrum of a multilayer thin film that does not include a specific layer. Ru.

[Effect]

Since an in-plane defect causes a change in thermal diffusivity regarding heat propagation, a change in the gradient of AC temperature from a light-irradiated area to a non-irradiated area corresponds to the in-plane position of the defect. Furthermore, since the AC temperature distribution is determined, the defect location can be determined quickly and easily.

At wavelengths that exhibit infrared absorption, the temperature of the light irradiated area increases and heat diffuses to the non-irradiated area. The AC temperature of the non-irradiated area is I
This corresponds to the infrared absorption of thin films. Since propagation of AC thermal energy occurs in any material, measurement of AC temperature distribution can be applied to general thin films.

〔Example〕

Next, embodiments of the invention will be described with reference to the drawings.

FIGS. 1 and 2 are layout diagrams of main parts showing a method for evaluating in-plane defects in a thin film. This method is disclosed in Japanese Patent Application Laid-Open No. 60-155950.
i! by the intermittent heating method disclosed in the publication. In! In the figure, 1 is a thin film of a sample for in-plane defect measurement, which is based on the method of measuring thermal diffusivity in the plane direction perpendicular to the thickness of . It is 0.5 crane. Reference numeral 2 denotes a mask member that covers a part of one side of the thin film 1, and is movable in one direction along the surface of the thin film 10 using a micrometer 5. The mask member 2 shields a part of one side of the thin film 10 from being irradiated with light energy, thereby creating a light irradiated area and a non-irradiated area.

3 is a semicircular plate that is rotatably supported by a chopper provided on the upper part of the mask member 2 and rotated at a predetermined number of rotations by a motor (not shown). Reference numeral 4 denotes a light source such as a tungsten lamp, which is attached to the chopper 3 and heats the light irradiated portion of the thin film 1 with light energy. 5 is the mask member 2
This is a boundary scanning means that moves the linear boundary between the light irradiated part and the non-irradiated part of the thin film 1 using a micrometer connected to the .

Thermocouples 6A and 6B are in point contact with the light irradiated part and the non-irradiated part of the thin film 1, respectively, and are connected with opposite polarities.

The distance between the thermocouples 6A and 6B can be arbitrarily varied by the temperature sensor scanning means 13 shown in FIGS. 3 and 4.

8 is a lock-in amplifier that amplifies the AC output of the thermocouples 6^ and 6B using the output of the optical sensor 7 such as a phototransistor as a reference signal.

When the chopper 3 is rotated in such a main part arrangement and the thin film 1 is intermittently irradiated with light energy, the portion of the II thin film 1 that is irradiated with the light energy is heated and its temperature rises, whereas the thin film Since the temperature of the non-irradiated part 1 does not rise, a temperature gradient is created between the light irradiated part and the non-irradiated part, and periodic heat waves advance in the surface direction of the thin film.
B can be used to measure the AC temperature at a point where the thermocouple is in point contact. This AC temperature reflects the thermal diffusivity, which is the thermal property of the thin film. Now thermocouple 6A, 6
The distance between B! , the AC temperature at the thermocouple 6B at this time is T, the frequency of intermittent light energy is f, the amount of heat absorbed by the \iJ film is Q, the heat capacity per unit volume of the thin film is C1, the sample thickness is d, then the thickness of the thin film is The thermal diffusivity a satisfies the following relationship.

n T ,'y ”I n(Q/ 4 n f Cd
) JT (billion) j! ---fl) Expression (1)!
Differentiating with d l n T / d j −−FG 慴=−−−−−
--(2) The right side of equation (2) indicates that as long as the thermal diffusivity a is constant, the slope of the logarithm of the AC temperature (hereinafter referred to as the slope of the temperature distribution) is constant. However, if there is a defect within the plane, the thermal diffusivity a at that point changes, so the gradient of the temperature distribution changes. Therefore, it is possible to obtain the AC temperature distribution of the non-irradiated portion of the thin film and determine the defect position from the change in the gradient of this AC temperature distribution.

The temperature sensor scanning means 13 is shown in FIG. 6A6B
The distance E between the two thermocouples can be arbitrarily changed by this scanning means. The temperature sensor scanning means 13 is an XY stage 10
and a micrometer 105. Thermocouple 6^ is thin film 1
The AC temperature of the light irradiation section 21 is measured. Micrometer 105 moves thermocouple 6B in the X direction. The X-Y stage 10 determines the position of the thermocouple 6A by moving in the X direction and the X direction. The xy stage 10 can be coupled with the mask member 2.

The thermocouples 6A and 6B are connected with their polarities reversed, and a signal representing the difference in AC temperature is input to the lock-in amplifier 8.

Lock-in amplifier 8 uses the frequency of the intermittent signal from optical sensor 7 as a reference signal, and separates and amplifies an AC temperature signal having the same frequency. Thin Il! There is an alternating current temperature gradient between the light irradiation section 21 and the non-irradiation section 22, and the AC temperature difference between the light irradiation section and the non-irradiation section can be measured using the thermocouples 6A and 6B. The linear boundary between the light irradiated area and the non-irradiated area can be detected not only by using a boundary scanning means such as the micrometer 5 as described above, but also by moving the thin film 1.

FIG. 4 shows an X stage 110 and a micrometer 105 which are temperature sensor scanning means 13 according to another embodiment. Other embodiments of temperature sensors are also shown. This temperature sensor consists of a photodiode array 106 equipped with a Rondo lens 11 and a slit 12.

In the case of this temperature sensor, it is sufficient to electrically scan the array in the X direction, so mechanical movement is only required in the X direction.
FIG. 5 shows the results of in-plane defect measurement of a thin film measured by the present invention, which has a simple drive mechanism and allows rapid measurement to be performed more suitably. An alumina sintered substrate with a thickness of 100 nm was used as a sample. A test piece was cut into a size of 10 fl x 10 fi, and the AC temperature difference ΔTac was measured by moving it approximately 500 mm in both the X and X directions, and it was displayed as a three-dimensional mesh in correspondence with the X-Y coordinates. is shown in Figure 5 (11),
Figure 5 (bl) is the one after shading processing. Also, when two-dimensional contour lines are displayed, it becomes as shown in Figure 5 (C). It is clearly seen that there are in-plane defects in three locations.When each section was cut and the cross section was observed with an electron l!J microscope and composition analyzed, it was found that there were grain boundaries and disk-shaped voids due to the precipitation of impurities. It became clear that this was the case, and this result provided important knowledge for improving the manufacturing method.

Note that the thin film material may be either amorphous, single crystal, or crystal, and the method and apparatus of the present invention can also be generally applied to polymer films, composite materials, multilayer materials, etc. can.

FIGS. 6 and 7 are layout diagrams of main parts showing a method for infrared spectroscopic analysis of thin films. 1 and 2 are different from each other in that a spectroscope 9 is added and that a thermocouple 6 is provided only in the non-irradiated area.The spectrometer 9 allows the light from the light source 4 to be The thin film 1 is irradiated with infrared rays of different wavelengths in sequence. A thermocouple cannot be provided in the light irradiation part because it absorbs i3 excess light.

The thin Ml is sequentially irradiated with infrared rays of a predetermined wavelength. When irradiated with infrared rays having a wavelength that exhibits infrared absorption, the AC temperature of the light irradiation section rises rapidly. At this time, due to the relationship of equation (2) above, dl
Since nT/dj is constant, the cross'fL temperature of the non-irradiated area also rises rapidly. By measuring the AC temperature at a predetermined position in the non-irradiated area in this manner, it can be determined whether or not there is infrared absorption in the light-irradiated area. By using a boundary scanning means such as a micrometer 5, the value of l can be made as small as possible and its detection sensitivity can be increased. By scanning the wavelength of infrared rays, an AC temperature spectrum is obtained corresponding to the absorption of infrared rays.

FIG. 8 is a diagram showing an AC temperature spectrum of a polycarbonate thin film according to an embodiment of the present invention.

A thermocouple was attached to approximately the center of an irregular polygonal sample thin film (3 μm thick) to measure the alternating current temperature. When there is infrared absorption, the temperature rises, so the peak appears upward. Figure 10 shows the infrared absorption standard spectrum of a polycarbonate thin film measured by the transmission method.The wave number (reciprocal of the wavelength) of both spectra is shown in Figure 10.
are in good agreement.

FIG. 9 is a diagram showing an AC temperature spectrum of an amorphous silicon film. The AC temperature corresponding to infrared absorption due to the locking of 5i-H at wave number 630 (cll-') is
The AC temperature corresponding to the infrared absorption due to stretching of 5i-H is shown at 080 (am-'). The alternating current temperature caused by this infrared absorption causes the amorphous silicon film to melt into a silicon wafer.
(thickness: 300 Pa) to measure the AC temperature due to infrared absorption, and then measure the AC temperature due to infrared absorption of only silicon wafers from the same lot, and from the difference between the two spectra. It can be obtained by detecting only the AC temperature spectrum of the amorphous silicon film. The AC temperature spectrum of the amorphous silicon film provides knowledge about the manufacturing conditions of the amorphous silicon film.

Scanning of the wave number can be performed by a conventional method using a wave number cam or a cosecant bar mechanism. A diffraction grating is used as the zero spectrometer.

In conventional infrared spectroscopy, the measurable thickness of a thin film is limited to a range of several to ten nanometers, but the method of the present invention can be applied to samples of up to five nanometers.

〔Effect of the invention〕

According to the present invention, 1) In a method for evaluating in-plane defects in a thin film, light energy of a constant amplitude is intermittently applied to a light irradiation area of a thin film that is partitioned into a light irradiation area and a non-irradiation area by a scannable linear boundary. The AC temperature of the light irradiated part and the non-irradiated part was measured.
2) In an apparatus for evaluating in-plane defects in a thin film, a light source that irradiates the thin film with light is used. , a mask that cuts off the light from the light source at an arbitrary period, and a mask that blocks a portion of the light irradiated onto the thin film to form a light irradiated part and a non-irradiated part having linear boundaries in the thin film. a member, an optical sensor installed in the optical path to detect the intermittent cycle of the irradiated light, and a light sensor that detects the temperature of the light irradiated part and the non-irradiated part of the thin film and determines the polarity of the temperature output of the light irradiated part and the non-irradiated part. temperature sensors connected in reverse to each other, a lock-in amplifier that separates and amplifies an AC temperature component having the same frequency as the intermittent cycle detected by the optical sensor from the output of the temperature sensor, and a light irradiated part and a non-irradiated part of the thin film. boundary part scanning means for moving the linear boundary part of the thin film; and temperature sensor scanning means for measuring the AC temperature of the non-irradiated part and determining the AC temperature distribution based on the AC temperature of the light irradiation part of the thin film. 3) In a thin film infrared spectroscopic analysis method, infrared rays of a predetermined wavelength and a constant i width are dispersed into a light irradiated part of a thin film that is partitioned into a light irradiated part and a non-irradiated part by a scannable linear boundary part. 4) A light source that irradiates the thin film with light in an apparatus that performs infrared spectroscopic analysis of the thin film; , a spectrometer that splits the light from this light source and sends infrared rays of a predetermined wavelength to the thin film, a chipper that cuts off the infrared rays at an arbitrary cycle, and a chipper that intercepts a portion of the infrared rays that are irradiated to the thin film and directs the infrared rays to the thin film in a straight line. a mask member that forms a light irradiation part and a non-irradiation part having a shaped boundary part; an optical sensor installed in an optical path to detect the intermittent cycle of the irradiated infrared rays; and an alternating current at a predetermined position in the non-irradiation part of the thin film. A temperature sensor that detects temperature, a lock-in amplifier that separates and amplifies an AC temperature component having the same frequency as the intermittent cycle detected by the optical sensor from the output of this temperature sensor, and a thin film that separates the light irradiated part and the non-irradiated part. 5) a method for infrared spectroscopic analysis of a thin film, the AC temperature spectrum of the multilayer f1 film including the specific layer and the AC temperature of the multilayer iIM not including the specific layer; The AC temperature spectrum of a specific layer is determined from the difference in spectra, so changes in the slope of temperature distribution correspond to changes in thermal diffusivity, and changes in thermal diffusivity are caused by a wide variety of defects, and further measurements of temperature distribution (including various types of defects due to gradient ablation of temperature distribution, which is easily done)
II! *In general, it is possible to quickly evaluate in-plane defects. Furthermore, the temperature sensor scanning means makes it extremely easy to measure the AC temperature distribution, and the present device further speeds up the evaluation of in-plane defects.

Furthermore, since the AC temperature in the non-irradiated area is proportional to the amount of infrared absorption in the light-irradiated area, infrared absorption spectroscopic analysis of the thin film can be performed by measuring the AC temperature spectrum of the non-irradiated area. In this case, measurement of AC temperature can be applied to thin films and can be easily performed, so by measuring AC temperature spectrum, infrared spectroscopy can be performed quickly and easily without being constrained by the shape or material of thin films in general. becomes possible. The effect of having fewer restrictions on thickness can also be obtained.

The device that measures AC temperature spectra does not require precision optical components or highly sensitive detectors as in the past, making it possible to reduce the cost of the device.

[Brief explanation of the drawing]

FIG. 1 is a side view of the main parts explaining the in-plane defect evaluation method according to the embodiment of the present invention, FIG. 2 is a plan view of the main parts explaining the in-plane defect evaluation method according to the embodiment of the invention, FIG. 3 is a cutaway perspective view of a main part of an apparatus for evaluating in-plane defects according to an embodiment of the present invention, and FIG. 4 is a cutaway perspective view of a main part of an apparatus for evaluating in-plane defects according to another embodiment of the present invention. Figure 5 shows the AC temperature distribution of the embodiment of this invention, Figure 5 1b+ is a Mesosch diagram, Figure 5 1b+ is a shading diagram, Figure 5 1cI is a contour diagram, and Figure 6 is a diagram of this invention. FIG. 7 is a side layout diagram of essential parts showing an infrared spectroscopic analysis method according to an embodiment of the invention, FIG. 7 is a plan layout diagram of essential parts showing an infrared spectroscopy method according to an embodiment of the present invention, and FIG. FIG. 9 is a diagram showing the AC temperature spectrum of the amorphous silicon thin film according to the embodiment of the present invention, and FIG. 10 is a diagram showing the AC temperature spectrum of the polycarbonate thin film according to the present invention. It is a diagram showing a spectrum. tzi film, 2: mask member, 3: tzisopa, 4: light source,
5: Micrometer, 6.6A, 6Bj thermocouple, 7:
Optical sensor, 8; Lock-in amplifier, 9: Spectrometer, to:
xy stage, 11: Rondo lens, 12 Nislit, 105: micrometer, 106: photodiode array, 1107 X stage, 13: temperature sensor scanning means. Fig. 1 Fig. 2 Fig. 2 Fig. Fig. Fig. 10 (not shown)

Claims (1)

[Claims] 1) In a method for evaluating in-plane defects in a thin film, light energy of a constant amplitude is applied intermittently to a light irradiated area of a thin film that is partitioned into a light irradiated area and a non-irradiated area by a scannable linear boundary. The AC temperature of the light irradiated area and the non-irradiated area is measured, the AC temperature distribution of the non-irradiated area is calculated based on the AC temperature of the light irradiated area, and the defect location is determined from the change in the gradient of this temperature distribution. A method for evaluating in-plane defects in thin films characterized by detecting. 2) In an apparatus for evaluating in-plane defects in a thin film, there is a light source that irradiates the thin film with light, a chopper that cuts off the light from the light source at an arbitrary period, and a chopper that cuts off a part of the light that is irradiated to the thin film. A mask member that forms a light irradiation part and a non-irradiation part having a linear boundary part, an optical sensor installed in an optical path and detecting the intermittent cycle of the irradiation light, and a thin film between the light irradiation part and the non-irradiation part. A temperature sensor that detects temperature and connects the polarity of the temperature output of a light irradiation part and a non-irradiation part with each other in reverse, and an AC temperature component having the same frequency as the intermittent cycle detected by the light sensor from the output of the temperature sensor. a lock-in amplifier for separating and amplifying; a boundary scanning means for moving the linear boundary between the light irradiated part and the non-irradiated part of the thin film; 1. A device for evaluating in-plane defects in a thin film, comprising: a temperature sensor scanning means for measuring an AC temperature of a substrate and determining an AC temperature distribution. 3) In an infrared spectroscopic analysis method for a thin film, infrared rays of a constant amplitude and a predetermined wavelength are intermittently applied to the light irradiated part of the thin film, which is divided into a light irradiated part and a non-irradiated part by a scannable linear boundary part. A method for infrared spectroscopic analysis of a thin film, characterized in that the AC temperature at a predetermined position in the non-irradiated area is amplified by a lock-in amplifier to obtain an AC temperature spectrum. 4) In an apparatus that performs infrared spectroscopic analysis of thin films, there is a light source that irradiates the thin film, a spectrometer that spectrally specifies the light from this light source and sends infrared rays of a predetermined wavelength to the thin film, and this infrared ray is intermittent at an arbitrary period. a chopper that shields a portion of the infrared rays irradiated to the thin film to form a light irradiated part and a non-irradiated part having linear boundaries in the thin film, and a mask member that is installed in the optical path and interrupts the irradiated infrared rays. An optical sensor that detects the cycle,
a temperature sensor that detects the AC temperature at a predetermined position in the non-irradiated portion of the thin film; and a lock-in amplifier that separates and amplifies an AC temperature component having the same frequency as the intermittent cycle detected by the optical sensor from the output of the temperature sensor. An apparatus for performing infrared spectroscopic analysis of a thin film, comprising a boundary scanning means for moving the linear boundary between the light irradiated part and the non-irradiated part of the thin film. 5) A method for infrared spectroscopic analysis of a thin film, characterized in that the AC temperature spectrum of a specific layer is determined from the difference between the AC temperature spectrum of a multilayer thin film containing the specific layer and the AC temperature spectrum of a multilayer thin film that does not include the specific layer. Item 3. The method for infrared spectroscopic analysis of a thin film according to item 3.