JP2008046040A - Sample evaluating method and apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sample evaluating method and a sample evaluating apparatus capable of more correctly evaluating quality without destroying a sample, such as a thin film used as a measurement object. <P>SOLUTION: In this sample evaluation method, the sample S held in a sample holding part 2 is moved at a fixed speed along one way within its plane by a moving part 4 while electron beams E are irradiated onto the moving sample S by an electron beam generator 5, cathode luminescence CL generated from the sample S is detected by a CL spectrum detector 6, and the sample S is evaluated based on the detection result of the cathode luminescence CL. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a sample evaluation method and evaluation apparatus, and more particularly, a compound semiconductor thin film such as a gallium nitride (GaN) thin film for an optical device or a high-frequency device, or an insulating protective film for a plasma display (PDP). The present invention relates to a sample evaluation method and an evaluation apparatus capable of non-destructively evaluating in-plane characteristics of a sample such as a metal oxide thin film such as a magnesium oxide (MgO) thin film.

Conventionally, a gallium nitride (GaN) thin film which is a III-V compound semiconductor is known as a semiconductor thin film for an optical device or a high-frequency device.
This GaN thin film is formed by chemical vapor deposition such as metal organic chemical vapor deposition (MO-CVD) or chloride, or physical vapor deposition such as molecular beam epitaxy (MBE) or reactive vapor deposition. Be filmed. In general, the GaN thin film is characterized by measuring electrical characteristics, and carrier characteristics and electron mobility are usually used as the electrical characteristics. Generally, the quality of the film is evaluated based on the measurement result.
When evaluating the electrical characteristics of the GaN thin film, for example, in order to measure the characteristic distribution corresponding to the size of a 4-inch wafer, it is necessary to secure 75 measurement points. Therefore, a method is used in which 75 samples of 10 mm square evaluation samples are cut out from the 4-inch wafer and measured.

As a method for evaluating the crystallinity of a GaN thin film, a method is proposed in which the thin film is irradiated with an electron beam, cathode luminescence (CL) generated from the thin film is detected, and the crystallinity is evaluated based on the detection result. (Patent Document 1). The band gap energy (Eg) of GaN is 3.4 eV, and in the case of cathodoluminescence (CL), the crystallinity of the film affects the waveform shape appearing near the wavelength of 360 nm. For example, when the film crystallinity is good, a sharp and strong peak is observed, and when the film crystallinity is not good, a broad and weak peak is observed. In addition, when the thin film contains impurities, a peak appears in the vicinity of 550 nm. Therefore, the crystallinity of the GaN thin film can be determined based on the presence or absence of the peak.
Furthermore, as a method for quality control of the GaN thin film, a method for evaluating impurities in the film by secondary ion mass spectrometry (SIMS) has been proposed.

On the other hand, a magnesium oxide (MgO) thin film is widely known as an insulating protective film for a plasma display (PDP), and deposition methods such as a vapor deposition method, a sputtering method, and a powder coating method are known as methods for forming this MgO thin film. At present, the vapor deposition method is generally the mainstream.
The film quality characteristic of the MgO thin film has a very large influence on the discharge start voltage of the plasma display (PDP) and the panel life. Since the film quality characteristics vary depending on the film forming conditions and the impurity concentration in the film, the film forming conditions and the impurity concentration in the film have a great influence on the characteristics and life of the subsequent PDP. Therefore, it is necessary to determine whether or not this MgO thin film is suitable as an insulating protective film for PDP at the stage before the actual panel is formed. It is common to judge the suitability by analogy.

Further, in the optical semiconductor crystal, cathodoluminescence (CL) generated from this crystal is measured, and various characteristics are evaluated based on the measurement result. There has been proposed an attempt to evaluate the change of the above using cathodoluminescence (CL) (Patent Document 2).
JP 2001-83087 A JP 2005-353455 A

By the way, the conventional GaN thin film evaluation method described above has the following problems.
(1) The evaluation method based on electrical characteristics is a destructive measurement because a plurality of evaluation samples of a certain size are cut out from a wafer to be evaluated. Therefore, it cannot be measured nondestructively.
(2) In the evaluation method using cathodoluminescence (CL), although it can be measured nondestructively, the sample is heated by irradiation with an electron beam, so that the heating effect of the electron beam is added to the measurement result of cathodoluminescence (CL). Therefore, accurate evaluation of the thin film itself cannot be performed.
(3) In the evaluation method by secondary ion mass spectrometry (SIMS), evaluation is difficult when the impurity concentration in the GaN thin film is extremely low. In particular, since the impurity concentration in the GaN thin film by the recent film forming method is close to the detection limit, this method is difficult to evaluate.

On the other hand, the conventional MgO thin film evaluation method described above has the following problems.
(1) In the evaluation method for judging from the empirical value of the film formation condition, the suitability is judged by analogy with the crystal structure and refractive index of the film from the empirical value of the film formation condition. In many cases, the film quality of the thin film is different from the film quality of the MgO thin film inferred from empirical values of the film forming conditions, and in fact, the exact film quality of the MgO thin film cannot be understood unless it is made into a panel.
(2) In the evaluation method using cathodoluminescence (CL), it is necessary to evaluate the film quality only by measuring cathodoluminescence (CL) because of the crystal structure and geometric structure of the MgO thin film. The measurement result cannot be obtained.
As described above, regarding the MgO thin film that influences the panel characteristics of the plasma display (PDP), when developing a highly functional MgO thin film, the film characteristic of the MgO thin film that gives a guideline for the characteristics after panel formation There was a need for an evaluation method.

  The present invention has been made to solve the above-described problems, and a sample evaluation method and evaluation capable of more accurately evaluating quality without destroying a sample such as a thin film to be measured. An object is to provide an apparatus.

  When evaluating the characteristics of a sample using cathodoluminescence (CL), the present inventors moved the sample at a constant speed along one direction in the plane, and from the moving sample. If the generated cathodoluminescence is detected, the energy amount of the electron beam per unit time irradiated on the sample is suppressed, so that the sample can be evaluated nondestructively. If there is a correlation between the characteristics of this sample and the device characteristics when this sample is applied to the desired device, a guideline for device characteristics can be obtained according to the characteristics of this sample. The inventors have found that it is possible to provide the present invention and have completed the present invention.

  That is, in the sample evaluation method of the present invention, the sample is moved at a constant speed along one direction in the plane, and the cathode generated from the sample by irradiating the moving sample with an electron beam. Luminescence is detected, and the sample is evaluated based on the detection result of the cathodoluminescence.

In this sample evaluation method, the electron beam spot moves on the sample along one direction in the plane at a constant speed, so that the electron beam irradiates at a specific point on the sample. Accordingly, the amount of energy of the electron beam per unit time irradiated on the sample is suppressed, and damage to the sample due to the energy of the electron beam is reduced. This makes it possible to evaluate the sample nondestructively.
Further, by irradiating the moving sample with an electron beam and detecting cathodoluminescence generated from the sample, an in-plane distribution of the characteristics of the sample can be easily obtained.
Further, if there is a correlation between the characteristics of this sample and the device characteristics when this sample is applied to a desired device, it is possible to give a guide to the device characteristics based on the characteristics of this sample.

The sample is preferably a sample made of a III-V group compound or a II-VI group compound.
The sample is preferably a sample made of a metal oxide.
The speed is preferably 0.5 mm / min or more and 5 mm / min or less.
By setting the speed to 0.5 mm / min or more and 5 mm / min or less, damage to the sample due to the energy of the electron beam becomes extremely small.

  The sample evaluation apparatus of the present invention includes a vacuum container, a sample holding means provided in the vacuum container for holding the sample, a moving means for moving the sample holding means in a predetermined direction at a constant speed, and the sample An electron beam generating means for irradiating the sample held by the holding means with an electron beam, and a detecting means for detecting cathodoluminescence generated from the sample are provided.

In this sample evaluation apparatus, the sample holding means for holding the sample by the moving means is moved at a constant speed in a predetermined direction, and the electron beam generating means irradiates the sample with the electron beam and detects it Cathodoluminescence generated from the sample is detected by means.
As a result, the electron beam spot moves on the sample along one direction in the plane at a constant speed, and thus the energy amount of the electron beam per unit time irradiated on the sample is suppressed, The sample can be evaluated nondestructively and easily without damaging the sample due to the energy of the electron beam.
Further, by irradiating the moving sample with an electron beam and detecting cathodoluminescence generated from the sample, the in-plane distribution of the characteristics of the sample is easily measured.

The sample holding means includes heating means for heating the sample to be held.
In this sample evaluation apparatus, the sample holding means is provided with a heating means for heating the sample, whereby the sample can be heated within a desired temperature range.

According to the sample evaluation method of the present invention, the sample is moved at a constant speed along one direction in the plane, and the cathode generated from the sample by irradiating the moving sample with an electron beam. Since the luminescence is detected and the sample is evaluated based on the detection result of the cathodoluminescence, the sample can be evaluated nondestructively, and the in-plane distribution of the characteristics of the sample can be easily obtained. Therefore, a higher quality sample can be obtained.
In addition, by obtaining a correlation between the film characteristics of the sample and the device characteristics when the sample is applied to a desired device, a guideline can be given to the device characteristics by the characteristics of the sample.

According to the sample evaluation apparatus of the present invention, the moving means for moving the sample holding means for holding the sample in a predetermined direction at a constant speed, and the electron beam for irradiating the sample held by the sample holding means with an electron beam Since the generating means and the detecting means for detecting the cathodoluminescence generated from the sample are provided, the sample can be evaluated nondestructively and easily without damaging the sample with an electron beam.
Further, since the cathode luminescence generated from the sample is detected by irradiating the moving sample with the electron beam, the in-plane distribution of the characteristics of the sample can be easily measured.

  By providing the sample holding means with heating means for heating the sample to be held, the sample can be heated within a desired temperature range.

The best mode for carrying out the sample evaluation method and evaluation apparatus of the present invention will be described.
This embodiment is specifically described for better understanding of the gist of the invention, and does not limit the present invention unless otherwise specified.

  FIG. 1 is a schematic diagram showing a sample evaluation apparatus according to the present embodiment. In the figure, 1 is a vacuum chamber (vacuum container), 2 is a sample holding unit (inside the vacuum chamber 1) for holding a sample S ( (Sample holding means) 3 is a heater (heating means) built in the sample holding section 2, 4 is a moving section (moving means) for moving the sample holding section 2, and 5 is a sample S held by the sample holding section 2. An electron beam generation source (electron beam generation means) that is excited by irradiation with an electron beam E, 6 is a cathode luminescence (CL) spectroscopic detector (detection means) that detects cathode luminescence (CL) generated from the sample S, and 7 is A quartz cathodoluminescence (CL) condenser lens also serving as a vacuum sealing window, 8 is a spare window for irradiating the surface of the sample S with laser light, and 9 is a turbo molecular pump exhaust system.

The heater 3 heats the sample S held in the sample holding unit 2 to a predetermined temperature, for example, a room temperature (25 ° C.) or higher and a temperature range of 400 ° C. or lower. For example, a tungsten (W) wire, tantalum ( Ta) wire or the like is preferably used.
The moving unit 4 moves the sample holding unit 2 along a direction in the plane of the sample S (in the direction of the arrow in FIG. 1) at a constant speed, and this speed is 0.5 mm / min or more and 5 mm. / Min or less, more preferably 1 mm / min or more and 2 mm / min or less.

Here, the reason why the moving speed of the sample S, that is, the sample holder 2 is limited to 0.5 mm / min or more and 5 mm / min or less is that when the speed is slower than 0.5 mm / min, the unit time irradiated on the sample This is because the amount of energy of the hit electron beam increases so much that the sample is damaged and may be destroyed. On the other hand, when the speed is faster than 5 mm / min, the cathodoluminescence (CL) generated from the sample becomes unstable, and the measurement result of the cathodoluminescence (CL) does not accurately reflect the characteristics of the sample. It is.
Further, the speed range of 5 mm / min or less is a desirable range for controlling the mechanical parts constituting the moving unit 4 with high accuracy. If the speed exceeds 5 mm / min, the control accuracy of the mechanical parts is reduced, The moving speed of the sample holder 2 becomes extremely unstable.

The electron beam generation source 5 only needs to have a stability having a fluctuation range smaller than 1 × 10 ⁻³ , and a hot filament, a thermal field emitter, or the like is preferably used.
The energy of the electron beam E generated from the electron beam generation source 5 is 10 keV, the electron dose is 80 nA or less, and the beam diameter is preferably 100 μm or more and 200 μm or less, more preferably 140 μm or more and 160 μm or less.
Here, the reason why the beam diameter of the electron beam E is limited to 100 μm or more and 200 μm or less is that if the beam diameter is less than 100 μm, the sample is likely to be damaged by electron beam irradiation. This is because if it exceeds 200 μm, it is out of the focal position of light collection.

The turbo molecular pump exhaust system 9 only needs to be able to stabilize the inside of the vacuum chamber 1 within a predetermined degree of vacuum, for example, within a range of 10 ⁻³ to 10 ⁻⁴ Pa. A dry pump is used.
The CL spectroscopic detector 6 detects cathodoluminescence (CL) having a wavelength range of 200 nm or more and 900 nm or less.
The CL condensing lens 7 condenses cathodoluminescence (CL) on the CL spectroscopic detector 6, and a parabolic concave mirror may be used instead of the CL condensing lens 7.

Next, the sample evaluation method of this embodiment will be described.
First, the sample S is fixed to the sample holding unit 2, the sample holding unit 2 is fixed at a predetermined position in the vacuum chamber 1, and the inside of the vacuum chamber 1 is made airtight. Next, the turbo molecular pump exhaust system 9 is driven to set the inside of the vacuum chamber 1 to a predetermined degree of vacuum, for example, a degree of vacuum within a range of 10 ⁻³ to 10 ⁻⁴ Pa.
As the sample S, a sample made of a III-V group compound such as GaN, a II-VI group compound such as ZnS, a metal oxide such as MgO, and the like, particularly a thin film is preferable.
Next, the moving unit 4 is driven to move the sample holding unit 2 along a direction in the surface of the sample S at a constant speed within a range of 0.5 mm / min to 5 mm / min. The sample S is irradiated with an electron beam E from the line source 5.

Here, the energy of the electron beam E is adjusted to 10 keV, the electron dose is 8 nA, and the beam diameter is adjusted to 100 μm to 200 μm, more preferably 140 μm to 160 μm.
While the sample S moves at a constant speed along one direction in the plane, the sample S is excited by irradiation with the electron beam E, and the cathodoluminescence CL is emitted and emitted by the excitation.
The cathodoluminescence CL emitted in this way is collected by the quartz CL condenser lens 7 and detected by the CL spectroscopic detector 6.

The characteristics of the sample S can be evaluated by comparing the CL spectral characteristics detected by the CL spectral detector 6 with the CL spectral characteristics detected from the standard sample.
Based on the CL spectral characteristics, the film characteristics such as the crystallinity and minute impurities of the sample S can be evaluated.
In addition, the correlation between the CL spectral characteristics and the electrical characteristics of the sample S is examined in advance, and the CL spectral characteristics of the sample S are compared with the above correlation, so that the sample S can be converted into a device or a panel. Characteristics can be estimated.
In addition, by irradiating the predetermined region of the sample S with the electron beam E in a zigzag manner, the in-plane distribution of the CL spectral characteristics in the predetermined region of the sample S can be obtained. You can know the distribution.

According to the sample evaluation method of the present embodiment, the sample S is irradiated with the electron beam E while moving the sample S at a constant speed along one direction in the surface thereof, and the cathode luminescence generated from the sample S. Since CL is detected and the characteristics of the sample S are evaluated based on the detection result of the cathodoluminescence CL, it is possible to evaluate the crystallinity of the sample S, film characteristics such as minute impurities, or electrical characteristics without destruction. it can.
Also, the characteristics of the sample S can accurately estimate the device characteristics when the sample S is applied to a desired device such as a PDP or an optical element, and the device characteristics can be guided based on the characteristics of the sample S. Can be given.

According to the sample evaluation apparatus of the present embodiment, the sample holding unit 2 that holds the sample S, the moving unit 4 that moves the sample holding unit 2, and the electron beam generation that excites the sample S by irradiating it with the electron beam E. Since the source 5 and the CL spectroscopic detector 6 for detecting the cathodoluminescence CL generated from the sample S are provided, the sample S can be evaluated nondestructively and easily without damaging the sample S with the electron beam E. be able to.
In addition, the in-plane distribution of the characteristics of the sample S can be easily measured.
In addition, by incorporating the heater 3 in the sample holder 2, the surface temperature of the sample S can be controlled with high accuracy.

EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention concretely, this invention is not limited by these Examples.
"Example 1"
First, as a sample S, three types of GaN thin films (GaN-A, GaN-B, GaN-C) are formed on a sapphire substrate by MOCVD, and each of these GaN-A, GaN-B, and GaN-C is formed. The temperature dependence of mobility (cm ² / V · s) was examined.

Figure 2 is a diagram showing temperature dependence of mobility in GaN-A ^(cm 2 / V · s), 3, mobility in GaN-B and GaN-C respectively ^(cm 2 / V · s It is a figure which shows the temperature dependence of (). In these figures, the temperature range is from room temperature (300K) to 77K.
In FIG. 3, “●” and “□” indicate GaN-B, and “◯”, “Δ”, and “×” indicate GaN-C, respectively.
2 and 3, it can be seen that the mobility at room temperature (300K) is excellent in the order of GaN-A >>GaN-B> GaN-C. It can be seen that this tendency becomes more prominent as the temperature becomes lower.

Next, trace impurities of each of the three types of GaN thin films (GaN-A, GaN-B, GaN-C) were measured by secondary ion mass spectrometry (SIMS).
Here, four elements of hydrogen (H), carbon (C), oxygen (O), and gallium (Ga) were selected as trace impurities.
4 is a diagram showing the SIMS intensity of a trace impurity of GaN-A, FIG. 5 is a diagram showing the SIMS intensity of the trace impurity of GaN-B, and FIG. 6 is a chart showing the SIMS intensity of the trace impurity of GaN-C.
It can be seen that these GaN-A, GaN-B, and GaN-C samples have only a slight difference in the strength of carbon (C) and no difference in impurities.

Next, each of the three types of GaN thin films (GaN-A, GaN-B, GaN-C) is irradiated with the electron beam E while moving at a constant speed, and each of GaN-A, GaN-B, and GaN-C. The cathodoluminescence (CL) intensity was measured.
Here, the vacuum degree of the vacuum chamber 1 is 5.0 × 10 ⁻⁴ Pa, the moving speed of the GaN thin film is 1.0 mm / min, the surface temperature of the GaN thin film is 30 ° C., the energy of the electron beam E is 10 keV, and the electron dose. Was 20 nA, and the beam diameter was 150 μm.

FIG. 7 is a diagram showing the CL intensity of each of GaN-A, GaN-B, and GaN-C. The emission intensity at the band edge near 360 nm is strongest for GaN-A, and each of GaN-B and GaN-C. It can be seen that the emission intensity at the band edge of the lowering corresponds to the mobility (cm ² / V · s). Note that light emission near 720 nm is light emission caused by using a grating in the CL spectroscopic detector 6 and is a peak due to interference of light emission at 360 nm.

Next, for comparison, GaN-A, GaN- when the electron beam E is irradiated for 30 minutes with each of the three types of GaN thin films (GaN-A, GaN-B, GaN-C) fixed in position. The cathodoluminescence (CL) intensity of each of B and GaN-C was measured.
FIG. 8 is a diagram showing the CL intensities of GaN-A, GaN-B, and GaN-C. The emission intensity at the band edge near 360 nm is not changed in GaN-A, but GaN-B and GaN. It can be seen that the emission intensity at each band edge of -C is reversed as compared with the case of moving at a moving speed of 1.0 mm / min.

In addition, light emission having a peak near 550 nm appears. These light emission is caused by impurities such as carbon (C), and shows behavior different from the carbon (C) intensity by SIMS in FIGS. Yes.
As shown in FIG. 7 and FIG. 8, by controlling the irradiation time of the electron beam E, crystallinity, impurities, damage caused by electron beam irradiation, etc., which are film characteristics of the GaN thin film, can be easily evaluated.

Next, each of GaN-A, GaN-B, and GaN-C when irradiated with the electron beam E with the positions of the three types of GaN thin films (GaN-A, GaN-B, GaN-C) fixed. The relationship between the emission peak intensity at the band edge and the electron beam irradiation time was investigated.
FIG. 9 is a diagram showing the CL intensity at the band edge with respect to the electron beam irradiation time of each of GaN-A, GaN-B, and GaN-C, and the CL intensity at the band edge changes by changing the electron beam irradiation time. I understand that. Therefore, by strictly controlling the electron beam irradiation time, the CL intensity of the band edge generated from the GaN thin film can be accurately measured, and this measurement result shows the film quality of the GaN thin film such as crystallinity, impurities, damage, etc. Evaluation can be made.

"Example 2"
First, as a sample S, two kinds of MgO thin films (MgO-A, MgO-B) are formed on a sapphire substrate by vapor deposition, and the cathodoluminescence (CL) spectrum in each of these MgO-A and MgO-B is measured. did.
Here, a film formed using a high-purity MgO evaporation base material having an impurity concentration of several tens of ppm or less is formed using MgO-A and an MgO evaporation base material having an impurity concentration of 0.5% by weight. It was set as MgO-B.
Moreover, the vacuum degree of the vacuum chamber 1 is 5.0 × 10 ⁻⁴ Pa, the moving speed of the MgO thin film is 1.0 mm / min, the temperature of the MgO thin film is 30 ° C., the energy of the electron beam E is 10 keV, and the electron dose is 80 nA. The beam diameter was 150 μm.

FIG. 10 is a diagram showing cathodoluminescence (CL) spectra in MgO-A and MgO-B.
In the MgO thin film, it is known that oxygen defects in the film greatly affect the film characteristics, and the amount of oxygen defects is reflected in the CL spectrum, so that a CL spectrum having main peaks in the vicinity of 380 nm, 450 nm and 700 nm is obtained. Observed. In FIG. 10, the peak near 380 nm is the emission from the F + center (emission center) in which one electron is injected into the oxygen defect, and the peak near 450 nm is the F center (emission center) in which two electrons are injected into the oxygen defect. ), And the peak near 700 nm is light emission due to metal impurities. The light emission by this metal impurity is similar to the ruby light emission by the metal impurity in the sapphire substrate.

In the CL spectrum of the MgO thin film, the emission intensity in the vicinity of 380 nm and 450 nm is related to the emission characteristic of the PDP, and the luminance and resolution of the PDP improve as the emission intensity at 380 nm and 450 nm increases.
FIG. 10 shows that the emission intensity of MgO-A at 380 nm and 450 nm is stronger than that of MgO-B, and MgO-A is an oxygen defect type MgO thin film. Further, in this CL spectrum, it can be seen that the peak around 700 nm is weak and the amount of metal impurities is extremely small.
Therefore, it can be seen that when this MgO-A is applied to a PDP, an insulating protective film with excellent film quality is obtained.

FIG. 11 is a diagram showing the cathodoluminescence (CL) peak intensity with respect to the elapsed time after vacuum introduction in MgO-A.
According to this figure, it can be seen that the CL peak intensity becomes stable after 10 hours from the introduction of the vacuum. Therefore, it can be seen that stable CL characteristics can be obtained by measuring the CL intensity after 10 hours.

Next, the characteristics when the above MgO-A was applied to PDP were examined.
FIG. 12 is a diagram showing a CL spectrum when the above MgO-A is applied to a PDP.
Even when this MgO-A is applied to a PDP, it shows a CL spectrum similar to the CL spectrum of the above MgO-A, indicating that the insulating protective film has excellent film quality.

Next, the difference in characteristics between oxygen-deficient MgO and oxygen-free MgO was examined using CL spectra.
FIG. 13 is a diagram showing a CL spectrum in an MgO single crystal substrate. Here, an oxygen defect type (O / Mg = 0.922) MgO single crystal substrate was used.
This MgO single crystal substrate shows that the light emission from the F + center and the F center is weaker than the light emission from the metal impurity, and the amount of oxygen defects is smaller than that of the MgO-A.

FIG. 14 is a diagram showing a CL spectrum after baking the oxygen defect type (O / Mg = 0.922) MgO single crystal substrate at 1050 ° C. for 2 hours.
This MgO single crystal substrate has disappeared from the emission center caused by oxygen defects such as F + center and F center, and becomes an oxygen-free defect type (O / Mg = 1.000) MgO single crystal substrate. I understand that

FIG. 15 shows the writing speed with respect to the CL intensity from the F + center after the above MgO-A is applied to the PDP, and FIG. 16 shows the writing speed with respect to the CL intensity from the F center.
From these figures, it can be seen that there is a strong correlation between the CL intensity and the writing speed. Therefore, if the CL intensity is measured, the writing speed when applied to the PDP can be estimated.

  As described above, by measuring the CL spectrum of the MgO thin film, it is possible to determine whether the emission center is any one of F + center, F center, and metal impurity. From the CL spectrum corresponding to the emission center, MgO It was found that film characteristics when a thin film is applied to a PDP can be easily known. As a result, it was found that if the CL spectrum of the MgO thin film was measured, the film quality of the MgO thin film could be easily evaluated before applying to the PDP.

It is a schematic diagram which shows the evaluation apparatus of the sample of one Embodiment of this invention. It is a figure which shows the temperature dependence of the mobility (cm < ² > / V * s) in GaN-A. It is a figure which shows the temperature dependence of the mobility (cm < ² > / V * s) in each of GaN-B and GaN-C. It is a figure which shows the SIMS intensity | strength of the trace impurity of GaN-A. It is a figure which shows the SIMS intensity | strength of the trace impurity of GaN-B. It is a figure which shows the SIMS intensity | strength of the trace impurity of GaN-C. It is a figure which shows CL intensity | strength of a GaN thin film. It is a figure which shows CL intensity | strength of a GaN thin film. It is a figure which shows CL intensity | strength of the band edge with respect to the electron beam irradiation time of a GaN thin film. It is a figure which shows CL spectrum in a MgO thin film. It is a figure which shows CL peak intensity with respect to the elapsed time after the vacuum introduction in MgO-A. It is a figure which shows CL spectrum after applying MgO-A to PDP. It is a figure which shows CL spectrum in a MgO single crystal substrate. It is a figure which shows CL spectrum after baking a MgO single-crystal board | substrate at 1050 degreeC for 2 hours. It is a figure which shows the writing speed with respect to CL intensity | strength from F + center after applying MgO-A to PDP. It is a figure which shows the writing speed with respect to CL intensity | strength from F center after applying MgO-A to PDP.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vacuum chamber 2 Sample holding part 3 Heater 4 Moving part 5 Electron beam generation source 6 CL spectroscopic detector 7 Quartz CL condensing lens 8 Preliminary window 9 Turbo molecular pump exhaust system S Sample E Electron beam CL Cathode luminescence

Claims (6)

  The sample is moved at a constant speed along one direction in the plane, and the cathode luminescence generated from the sample is detected by irradiating the moving sample with an electron beam. The detection result of the cathode luminescence A method for evaluating a sample, wherein the sample is evaluated based on the method.   The sample evaluation method according to claim 1, wherein the sample is a sample made of a group III-V compound or a group II-VI compound.   The sample evaluation method according to claim 1, wherein the sample is a sample made of a metal oxide.   The sample evaluation method according to claim 1, 2, or 3, wherein the speed is 0.5 mm / min or more and 5 mm / min or less.   A vacuum container; a sample holding means for holding a sample provided in the vacuum container; a moving means for moving the sample holding means in a predetermined direction at a constant speed; and an electron in the sample held in the sample holding means. An apparatus for evaluating a sample, comprising: electron beam generating means for irradiating a beam; and detecting means for detecting cathodoluminescence generated from the sample.   6. The sample evaluation apparatus according to claim 5, wherein the sample holding means includes a heating means for heating the sample.

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