JPH08178874A - Surface-analyzing apparatus - Google Patents

Abstract

PURPOSE: To obtain a compact surface analysis apparatus with high resolution according to an He atomic beam scattering method by forming He atomic beam of a narrow energy width and making the inciden and reflecting directions the atomic beam the same. CONSTITUTION: After an atomic beam 16 is introduced into a scattering chamber 23, the atomic beam is bent 90 deg. by a reflecting plate 19 of a metallic single crystal such as platinum, gold or the like or an ionic crystal, so that an atomic beam 17 is cast on a measuring sample 21. The measuring sample 21 is set at a sample holder capable of controlling temperature in a range of 150K-2300K. The position of the sample 21 can be changed by a manipulator adjustable in five axial directions. A scattering atomic beam 18 passing through differential evacuating chambers 4-6 is detected by a detector 13 at a detecting chamber η evacuated to He partial pressure of 1/10<13> Pa or lower. A flying time over a flying distance of 750mm from a chopper 12 to the detector 13 is measured, thereby the energy is analyzed. The energy dispersibility of surface phonons can be detected by rotating the sample and changing measuring conditions. At the same time, the spatial distribution can be measured by measuring the intensity of the atomic beam while rotating the sample. Data related to the surface structure can be obtained as well.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface analysis method for analyzing vibrations and bonding states of a solid surface, and more particularly to a high resolution surface analysis apparatus which does not damage a measuring object.

[0002]

2. Description of the Related Art In a conventional apparatus for directly observing the energy dispersion relationship of surface phonons and analyzing the vibration and bonding state of a solid surface, high resolution electron energy loss spectroscopy using a slow electron beam and energy loss of a He atom beam are performed. The measuring He atom beam scattering method is adopted. The former is commercially available but has the best energy resolution of about 1 meV. In addition, when analyzing an adsorbate that is weakly bound to the surface, attention must be paid to desorption of the adsorbate and damage to the surface due to electron beam irradiation. The latter does not damage the surface because it uses a low energy He atom beam,
The angle of incidence and reflection is 90 °, and it is necessary to perform several stages or more of differential evacuation between the atomic beam source and the measurement sample, and between the measurement sample and the atomic beam detector to increase the energy resolution and detection sensitivity. Will be.

[0003]

According to the above conventional technique,
It is impossible to provide a high-resolution and downsized device using the He atomic beam scattering method. In order to obtain high resolution, the energy width of the incident He atomic beam must be narrowed, and when the atomic beam is ejected from an atomic beam source into a vacuum,
This is because the energy distribution becomes uniform and the energy width becomes narrow due to the temperature decrease due to the adiabatic expansion of the compressed gas. Therefore, in order to achieve high resolution, a large-sized pump having the ability to increase the pressure of the compressed gas and exhaust it is required, and high resolution and device miniaturization are contradictory.

It is an object of the present invention to provide a high-resolution and downsized surface analysis apparatus by He atom beam scattering method.

[0005]

The above-mentioned object is achieved by preparing a He atomic beam having a narrow energy width and making the incidence and the reflection of the atomic beam in the same direction. It is possible to narrow the energy width of the incident atomic beam by using the diffraction and scattering by the diffraction grating. Moreover, since the energy width can be narrowed by the diffraction grating, the vacuum exhaust system of the atomic beam source can be miniaturized. By using a He atomic beam reflector next to the measurement sample, the angle of incidence and reflection on the surface of the measurement sample can be 90 °, and the generation direction (incident) and reflection direction of the atomic beam can be the same direction. The overall size of the device can be reduced.

[0006]

According to the present invention, the energy resolution can be improved by the diffraction and scattering of the He atomic beam. This is because when a He atom beam is irradiated onto a diffraction grating having a certain period, the angle at which the He atom beam is diffracted and scattered differs depending on the energy due to the effect of wave nature. This is because it can be monochromatic. Further, according to the present invention, the He atom beam is a single crystal of metal such as platinum or gold, LiF, KBr, NaC.
It is possible to reduce the loss and change the direction of the atomic beam by using specular reflection such as an ionic crystal such as l or a diffraction grating. Therefore, by using this as a reflector, the degree of freedom in designing the device itself is increased. Can be provided, which contributes to downsizing of the device.

[0007]

EXAMPLES The present invention will be described in detail below based on examples.

Example 1 In this example, a surface analysis method using the He atomic beam scattering method and its apparatus configuration will be specifically described. An example thereof is shown in FIG. This apparatus includes an atomic beam generating chamber 1, a modulator chamber 2 for pulsing an atomic beam, a differential exhaust chamber 3 to 6 for keeping a scattering chamber 23 and a detection chamber 7 in an ultrahigh vacuum, and a scattering with a measurement sample. The chamber 23 and the detection chamber 7 are composed of an ultra-high vacuum container,
In particular, the detection chamber 7 is an extremely high vacuum container made of titanium alloy in order to reduce hydrogen as a background component and reduce noise. The generation chamber 1 is a diff stack diffusion pump with an exhaust speed of 2000 liters / second, and the modulator chamber 2 is an exhaust speed 1
80 liter / sec wide range turbo molecular pump,
The differential evacuation chambers 3 to 6 are wide-range turbo molecular pumps having an evacuation speed of 60 liters / second, and the scattering chamber 23 and the detector chamber 7 are wide-range turbo molecular pumps having an evacuation speed of 180 liters / second and liquid nitrogen-cooled titanium sublimation. By pump, generation chamber 1/10 ⁴ , modulator chamber 1/10 ⁵ , differential exhaust chamber 1/10
It is evacuated during generation of an atomic beam to a vacuum degree of about ⁷ to 1/10 ⁹ , scattering chamber 1/10 ⁸ , detection chamber 1/10 ¹⁰ Pascal (Pa). Injection of nozzles, skimmers, detectors, etc. between each vacuum chamber,
To adjust the alignment of the reflected atomic ray axis, use He through the viewing window 15.
-Introducing a Ne laser.

The supersonic He atom beam 16 is used in the gas generator 8
It is created by sending a higher pressure He gas to the pulse valve nozzle 9 of the generation chamber 1, generating a pulse atom beam of 0.1 to 10 ms from the nozzle, and cutting it out partially with a conical skimmer 11. At that time, the temperature control device 10 is installed in the nozzle 9.
Is installed, and the energy is controlled to 10 to 150 m by controlling the nozzle temperature in the range of 40 to 500K.
It can be changed up to about eV. The He atom beam is in the modulator room 2
It is further pulsed by a chopper 12 attached to a motor that can rotate at high speed in vacuum. This chopper 12 is a disc provided with a thin slit, and can be pulsed by passing an atomic beam through the slit, and the pulse width of the atomic beam can be arbitrarily changed by changing the slit width and the number of rotations. The pulsed atomic beam is introduced into the scattering chamber 23 through the differential exhaust chamber 3. Differential exhaust chamber 3,
Shut-off valves 27 and 28 are provided between the No. 4 and the scattering chamber 23 so that when exchanging a sample or adjusting a nozzle, work can be performed independently while keeping the other vacuum.

After introducing the atomic beam 16 into the scattering chamber 23, platinum,
The measurement sample 21 is irradiated with the atomic beam 17 after being bent at 90 ° by a reflection plate 19 such as a metal single crystal such as gold or an ionic crystal such as LiF, KBr or NaCl. The reflector is attached to a position controller (not shown) so that it can be moved during sample irradiation position adjustment and sample replacement. When used as a reflector, the measurement sample may be irradiated with an atomic beam before being bent by 90 ° by the reflector. Further, if the reflection plate 19 uses an ionic crystal of LiF, KBr, NaCl or the like or an artificial lattice having a certain period and the atomic beam 17 after diffraction and scattering using the slit 20, the energy resolution is improved. Here, the resolution can be changed depending on the size of the slit hole diameter. The measurement sample 21 is attached to a sample holder (not shown) capable of controlling the temperature of 150K to 2300K, and its position can be changed by a manipulator with 5-axis position adjustment. The scattered atomic beam 18 passes through the differential evacuation chambers 4 to 6 and is detected by the detector 13 of the detection chamber 7 that is evacuated to a He partial pressure of 1/10 ¹³ Pa or less, and the chopper 12
Energy analysis is performed by measuring the flight time of the flight distance of 750 mm from the detector 13 to the detector 13, and the energy dispersion relation of the surface phonons can be investigated by rotating the sample and changing the measurement conditions. By measuring the atomic beam intensity while rotating the sample, it is possible to measure the spatial distribution and obtain information on the surface structure. In addition,
The distances between the nozzle and the sample and between the sample and the detector are 400 mm.

Here, it is better to make the distance between the nozzle and the sample as short as possible in order to increase the atomic beam intensity, and to increase the distance between the sample and the detector in order to increase the energy resolution. As the detector 13, a magnetic field type mass spectrometer that can be manufactured at low cost is used. This is a method in which He atoms are ionized by electron impact ionization, mass analysis is performed by a magnetic field, and then the ions are detected by an electron multiplier. A quadrupole mass spectrometer may be used as the detector 13, but He
There is a drawback that it becomes expensive to detect only atoms with high sensitivity. Noise can be reduced by 30% or more by providing another differential exhaust chamber after the detection chamber in order to reduce the noise due to the components that remain as background gas without being detected by the He atomic beam entering the detection chamber 7. It was

The proposed device is attached to the scattering chamber by one flange port 14, and can be easily attached to other devices. When the measurement sample is inert to hydrogen, hydrogen may be used instead of helium.

Second Embodiment In the first embodiment, since the distance between the diffraction grating 19 and the slit 20 is short, a sufficient energy width reduction does not occur. An atomic beam with a narrow energy width can be formed by increasing the distance between them. An example thereof is shown in FIG.

The atomic beam 16 is irradiated on the diffraction grating 26, then passes through the chopper, changes its direction by the reflection plate 19, is energy-selected by the slit 20, and is then irradiated on the measurement sample 21. In this case, the distance between the diffraction grating 26 and the slit 20 is 500 mm, and the slit hole diameter is φ1 mm. FIG.
Shows the time-of-flight distribution of each atomic beam in a typical case.
(A) is a flight time distribution of the atomic beam 16 obtained when the hole diameter of the pulse valve nozzle is 0.01 mm and the internal pressure of the nozzle is 80 atm, and the energy width is about 0.3 meV. (B)
Is an atomic beam 1 after being monochromaticized by a diffraction grating and a slit
At 7, the energy width is narrowed to about 0.1 meV.
(C) is a time-of-flight distribution of the atomic beam 18 scattered from the measurement sample, and inelastic scattering peaks are obtained in addition to specular reflection (elastic scattering: scattering with zero energy loss) peaks. The energy dispersion of these inelastic scatterings is measured, and the energy dispersion relation of the surface phonons is measured by rotating the measurement sample and changing the conditions. Here, it was possible to further improve the energy resolution by replacing the reflection plate 19 with a diffraction grating and using two diffraction gratings at the same time. When the number of diffraction gratings and the distance to the slit are increased as described above, the energy resolution is improved, but the intensity of the scattered atomic beam is weakened and it is difficult to detect.

Third Embodiment In the first and second embodiments, the measurement condition is changed by rotating the measurement sample 21, but the measurement condition is changed without rotating the measurement sample 21, and a method for simultaneously measuring a plurality of samples is shown. Is shown below.

The principle is shown in FIG. By moving the positions of the reflection plate 19 and the slit 20 in the lateral direction, the incident angle of the atomic beam on the measurement sample 21 can be changed. This eliminates the need for a high-precision rotation mechanism for the measurement sample 21 and makes it possible to add other functions. For example, when the measurement sample holder 29 as shown in FIG. 4 is used, it is possible to simultaneously examine a plurality of samples by rotating the holder 29 and automatically exchanging the measurement sample 21 corresponding to the rotation.

FIG. 5 shows an embodiment in which the measurement sample 21 can be replaced without exposing the scattering chamber 23 to the atmosphere. A sample exchange chamber 25 is connected to the scattering chamber 23 via a gate valve 24. When the sample 21 is mounted, the sample 21 is once introduced into the sample exchange chamber 25, the inside of the exchange chamber 25 is evacuated to an ultrahigh vacuum, and then the gate valve 24 is opened to move the sample 21 to the scattering chamber 23. When the sample 21 is taken out, the procedure is reversed.

Further, the sample exchange chamber is connected to other surface analysis equipment and process equipment, or they are directly connected to the scattering chamber to exchange the sample, and thereby the atomic lattice in each process under the conditions of ultra-high vacuum. It is also possible to obtain vibration information.

Example 4 In Example 1-3, only surface analysis is carried out, but an example of a method for carrying out analysis in the middle of a process such as thin film formation in real time is shown below. The principle is shown in FIG. The slit 20 is made larger than that of the above-described embodiment, the scattering chamber 23 is divided into two, the thin film vapor deposition source 30 is attached to the facing position of the sample 21, and a thin film is formed by this vapor deposition source 30 to analyze the surface during fabrication. Is possible.

Thus, by observing the oscillation of the reflected high-energy electron beam diffraction signal by the molecular beam epitaxial method and controlling the atomic layer one layer at a time, the intensity oscillation of the He atomic beam is observed to obtain the atomic layer. Surface analysis can be performed while controlling the thin film at the level.

[0021]

In the prior art, in order to improve the energy resolution, the vacuum pump of the atomic beam generating chamber uses a large vacuum pump, and the device itself is large and special, so that it is not commercially available. In the present invention, by using the reflection plate of the diffraction grating,
It is possible to improve the energy resolution and make the atomic beam incident and reflection lines in the same direction to miniaturize the device itself.

Since the device of the present invention is small and can be realized by one flange port, it is easy to put on the market, and it can be easily attached to other devices and is highly versatile. Furthermore, application of the present invention is expected to improve the performance and build a new material field in functional materials in which the surface phonon structure dominates the characteristics.

[Brief description of drawings]

FIG. 1 is a block diagram showing a basic schematic configuration relating to a high resolution He atomic beam scattering method.

FIG. 2 is a block diagram showing a schematic configuration of a high resolution He atom beam scattering method in which a distance between a diffraction grating and a slit is increased.

FIG. 3 is a diagram showing a flight time distribution of each atomic beam.

FIG. 4 is a schematic configuration diagram regarding measurement of a plurality of samples.

FIG. 5 is a schematic configuration diagram regarding sample exchange.

FIG. 6 is a schematic configuration diagram regarding real-time analysis during the process during thin film production.

[Explanation of symbols]

1: Atomic beam generation chamber, 2: Modulator chamber, 3: Differential exhaust chamber,
4: differential exhaust chamber, 5: differential exhaust chamber, 6: differential exhaust chamber,
7: Detection chamber, 8: Gas generator, 9: Pulse valve nozzle, 10: Temperature controller, 11: Skimmer, 12: Chopper, 13: Detector, 14: Mounting flange, 15: Viewing window, 16: Supersonic velocity He atom beam, 17: He atom beam after being monochromated, 18: Scattered He atom beam, 19: Reflector, 20: Slit, 21: Measurement sample, 22: Position control device, 23: Scattering chamber, 24: Gate valve, 25: Sample exchange chamber, 26: Diffraction grating, 27: Shutoff valve, 28:
Shut-off valve, 29: sample holder, 30: thin film deposition source.

Claims (8)

[Claims] 1. A supersonic velocity H that is thermally non-equilibrium and has variable energy.
e In a surface analyzer for analyzing vibrations and binding states of solid surface atoms and adsorbates by observing inelastic scattering of atomic beams, the atomic beams are reflected by the reflection plate and the sample surface of the atomic beams. A surface analysis device characterized in that the incidence and the reflection on the scattering chamber are in the same direction. 2. A reflector made of the diffraction grating is made of LiF, KB.
The surface analyzer according to claim 1, which is a monochromator such as an ionic crystal such as r or NaCl or an artificial lattice having a periodic structure. 3. The sample surface according to claim 1, wherein the atomic beam is changed in direction by 90 ° by a reflection plate formed of a diffraction grating, and then changed again by 90 ° in direction by an arbitrary reflection plate, and then the sample surface is irradiated with the atomic beam. Surface analyzer. 4. The surface analysis device according to claim 3, wherein the arbitrary reflection plate is a diffraction grating. 5. The surface analyzer according to claim 1, wherein the incident position of the measurement sample and the incident He atomic beam is held at a predetermined position, and the position of the reflection plate with respect to the measurement sample is variable. 6. The surface analyzer according to claim 5, wherein a plurality of measurement samples are arranged on the rotating surface of the rotating sample holder. 7. The surface analysis device according to claim 1, further comprising a sample preparation chamber which is connected to the atomic beam scattering chamber and can be shielded from each other. 8. An atomic beam scattering chamber and a chamber accommodating a reflection plate formed by the atomic beam diffraction grating are separated from each other except a space for passing the atomic beam, and the atomic beam scattering chamber is provided with a sample. The surface analysis device according to claim 1, further comprising a thin film deposition source on the surface.