JPH06109856A - Measuring device for momentum of atomic beam and molecular beam - Google Patents

Abstract

PURPOSE:To measure a mean momentum of an atomic beam or a molecular beam by a comparatively simple device structure and without relation to a charged condition of an atom or a molecule. CONSTITUTION:There are arranged a collision face 1 where an atomic beam or a molecular beam executes collision, a mechanism 3 that displaces the collision face 1 by a proportional quantity to a power which the collision face 1 received through a collision of an atom or a molecule, and a mechanism that executes measurement by an optical position detecting device 6 through detecting a displacement of a reflection position of an irradiating laser light 4. As a composition is comparatively simple, an atomic beam or a molecular beam can be measured at an actually moving state and an usage as an acting state monitor of a semiconductor device or a nuclear fusion reaction reactor is possible.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for measuring the momentum of a directional atomic beam or molecular beam used in a semiconductor manufacturing process device or a nuclear fusion reactor. The present invention relates to a device capable of evaluating the velocity or flow rate of a molecular beam.

[0002]

2. Description of the Related Art In recent years, in a semiconductor manufacturing process, a nuclear fusion reactor, etc., an atom beam or a molecular beam in which an atom or a molecule having a certain kinetic energy is caused to flow in a certain direction has been often used. At this time, in order to evaluate the action and effect of the atomic beam or the molecular beam, it is necessary to quantitatively grasp the physical quantity such as the flow rate or velocity of the atomic beam or the molecular beam. However, in general, when measuring the physical quantity of an atomic beam or molecular beam, if they are composed of charged particles such as ions, it is possible to measure from the change of the orbit due to an electric field or magnetic field or the measurement of the current by a detector. However, in the case of neutral particles that do not have electric charges, there is no method for directly detecting them, and their measurement was extremely difficult. Therefore, generally, a mechanism for ionizing atoms or molecules is provided in the middle of the flow of the atomic beam or the molecular beam, and the neutral particles are generally converted into charged particles before measurement.

For example, conventionally, there has been a method of measuring the flight time of atoms or molecules as a method for evaluating the velocity of an atomic beam or a molecular beam in a gas phase. In this case as well, in the case of neutral particles, A special mechanism is required for ionization in the device, resulting in a complicated device configuration and a large size.

Therefore, while the atomic beam or the molecular beam is in a practical operating state, for example, while the atomic beam or the molecular beam is being used for processing a semiconductor, the atomic beam or the molecular beam is detected by a device such as the time-of-flight measuring device. It is difficult to directly measure the molecular beam, and it is practically impossible to use them as a process monitor.

[0005]

As described above, a means for easily measuring the physical quantity of an atomic beam or a molecular beam that generally does not have an electric charge has not been found, and a process device for semiconductor manufacturing or a fusion reaction is not found. Practical motion monitors for atomic and molecular beams used in furnaces have not yet existed.

The present invention has been made in order to solve the above-mentioned problems, and the momentum of an atomic beam or a molecular beam is measured irrespective of the presence or absence of an electric charge to easily evaluate the velocity and flow rate of the atomic beam or the molecular beam. The object is to provide a device that can.

[0007]

In order to achieve this object, the present invention collides an atomic beam or a molecular beam with a plate-shaped collision surface held in a vacuum container, and the force received by the collision surface is applied to the collision surface. It is detected as a change in the position of, and the average momentum of an atomic beam or a molecular beam is measured.

First, in order to make the amount of change in the position of the collision surface proportional to the force received by the collision surface, the collision surface is supported by a spring. Next, since the amount of displacement of the collision surface is extremely small, as a method of detecting the amount of displacement, the change in the position of the laser light reflected on the collision surface is measured with an optical position detector. It is measured by the change in the capacitance between the electrodes placed in close proximity, it is measured by the tunnel current flowing in the probe placed close to the back surface of the collision surface, or the collision surface is measured like a windmill. As a structure, a mechanism such as measuring from the number of rotations is provided.

[0009]

The above-mentioned device for measuring the momentum of an atomic beam or a molecular beam essentially measures the pressure applied to the collision surface. Both particles and ions can be measured in exactly the same way.
Also, since the pressure received by the collision surface is given by the product of three physical quantities of the mass of atoms and molecules, the average velocity, and the flow rate, if two of these parameters are known, the other one can be easily obtained. be able to.

Further, when measuring the amount of displacement of the collision surface, the minimum detection sensitivity is μ when laser light is used.
The order is m, the order is nm in the case of using the tunnel current of the probe, and the range is intermediate in the case of the electrostatic capacitance, and these measuring means can be arbitrarily selected according to the application.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the operating principle of the atomic beam and molecular beam momentum measuring apparatus according to the present invention will be described with reference to FIG. First, let us consider how the atomic (molecular) beam 2 collides with the collision surface 1 by considering individual particles in the atomic (molecular) beam 2. Mass m
When one particle (kg) collides with the collision surface 1 completely elastically at a velocity of u (m / s), the change in momentum on the collision surface is 2
It will be mu. Therefore, when N particles per second are similarly incident on the collision surface 1 and a perfect elastic collision occurs, the force received by the collision surface is 2 muN (N). If the elastic collision does not occur, a part of the kinetic energy of the particles incident on the collision surface 1 becomes thermal energy that raises the temperature of the collision surface 1. However, the rate of conversion into this thermal energy depends on the state of the collision surface, the type of incident particles, the velocity of the incident particles, and the state of the internal energy of the incident particles. Therefore, if the atom (molecule) beam is in a constant state, the force acting on the collision surface 1 has a value proportional to muN.

From the above, the force acting on the collision surface is proportional to the average momentum of the atomic (molecular) ray, and its direction is the atomic (molecular)
The direction of travel of the line. Next, in order to convert the force acting on the collision surface 1 into the displacement of the collision surface, in the device configuration of FIG.
Is installed. With this spring 3, the collision surface can be displaced in the direction of the force in proportion to the force acting on the collision surface 1. Since the collision surface 1 is held in the vacuum container, it receives the gas pressure of the vacuum atmosphere in the container, but since the front and back surfaces of the collision surface 1 are in the same vacuum, the gas pressures of the vacuum atmosphere are mutually different. However, it does not appear as a pressure for displacing the collision surface 1.

The displacement of the collision surface 1 due to the collision of the atomic (molecular) beam is generally very small. In order to detect this minute amount of displacement, in the device configuration of FIG. 1, a laser light oscillator 5 that irradiates the back surface of the collision surface 1 with the laser light 4 and an optical position detector that detects the displacement of the reflected light 9 of the laser light 4 are detected. 6 is installed. The principle by which the displacement of the collision surface 1 can be detected with the configuration of FIG. 1 will be described with reference to FIG. When the collision surface 1 is slightly displaced to the position shown by the broken line due to collision of the atomic (molecular) beam, the reflected light 9 of the laser light 4 emitted from the fixed laser light oscillator 5 is generated.
Is displaced from the position reached by the optical position detector 6 before the collision surface 1 is displaced. If the amount of this shift is detected by the optical position detector 6, the amount of displacement of the collision surface 1 can be known.

The displacement of the collision surface 1 is detected in FIG.
The case where the capacitance between the electrode 11 and the electrode 11 that is brought close to the back surface of the collision surface is detected is shown. As shown in FIG. 3, the electrode 11 having a constant area is accurately and parallelly and closely fixed to the back surface of the collision surface. The capacitance between the collision surface 1 and the electrode 11 is inversely proportional to the distance between the collision surface 1 and the electrode 11. Therefore, by measuring this capacitance with the capacitance measuring device 12, the displacement of the collision surface 1, that is, the average momentum of the atomic (molecular) ray can be measured.

The displacement of the collision surface 1 is detected in FIG.
And a case where the probe 13 is placed close to the back surface of the collision surface 1. The probe 13 is brought close to the back surface of the collision surface 1 on the order of several angstroms, and a power supply 14 is provided between the probe 13 and the collision surface 1.
When a voltage is applied at, a tunnel current flows between the probe 13 and the collision surface 1. This tunnel current depends on the distance between the probe 13 and the back surface of the collision surface 1, and the distance between the probe 13 and the back surface of the collision surface 1 can be arbitrarily changed by the laminated piezoelectric drive element 15. . Therefore, if the laminated piezoelectric driving element 15 is driven by the laminated piezoelectric driving element controller 16 so that the tunnel current flowing through the probe 13 becomes constant, the driving amount of the laminated piezoelectric driving element 15 is the collision surface 1.
Therefore, the displacement amount of the collision surface 1 can be measured from the voltage required for driving the laminated piezoelectric drive element 15.

FIG. 5 shows a case where the force received by the collision surface is converted into a rotational force and measured. A plurality of collision surfaces are radially installed on the rotating shaft 17 to form a wind turbine 18. When an atomic (molecular) beam collides with one collision surface, the collision surface rotates about the rotation axis 17 as shown in FIG. 5, and the next collision surface is exposed to the atomic (molecular) ray. In this way, the collision surfaces are atoms (molecules) one after another.
By being exposed to the rays, the wind turbine 18 converges on the rotational speed that is proportional to the flow rate and velocity of the atomic (molecular) ray. Therefore,
By counting the number of rotations of the windmill 18, the average momentum of the atomic (molecular) ray can be measured.

As mentioned above, these atoms (molecules)
An apparatus for measuring the momentum of a line can measure an average momentum of an atomic beam or a molecular beam with a relatively small and simple structure regardless of the charged state of the atom or the molecule. Therefore, the present apparatus can be used as a practical operating state monitor for atomic beams and molecular beams used in semiconductor manufacturing processes, nuclear fusion reactors, and the like.

[0018]

According to the present invention, it is possible to measure the average momentum of an atomic beam or a molecular beam regardless of the charge state of atoms or molecules and with a relatively simple device configuration. It can be used as a practical operating state monitor for atomic and molecular beams used in nuclear fusion reactors.

[Brief description of drawings]

FIG. 1 is a basic configuration diagram of an atomic beam / molecular beam momentum measuring device according to the present invention.

FIG. 2 is an explanatory diagram of the principle of measuring the displacement of the collision surface by reflection of laser light.

FIG. 3 is a device configuration diagram in the case of measuring the displacement of a collision surface by a change in electrostatic capacitance.

FIG. 4 is a device configuration diagram in the case of measuring the displacement of the collision surface by a tunnel current flowing between the probe and the collision surface.

FIG. 5 is a principle explanatory view in the case of measuring the average momentum of an atomic (molecular) ray by the rotation speed of the collision surface.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Collision surface 2 ... Atom (molecule) beam 3 ... Spring 4 ... Laser light 5 ... Laser light oscillator 6 ... Optical position detector 9 ... Reflected light 11 ... Electrode 12 ... Capacitance measuring instrument 13 ... Probe 14 ... Power supply 15 ... Laminated piezoelectric drive element 16 ... Laminated piezoelectric drive controller 17 ... Rotating shaft 18 ... Windmill

Claims (6)

[Claims] 1. A means for holding a collision surface for colliding an atomic beam and a molecular beam in a vacuum vessel, and displacing the collision surface by an amount proportional to the force received by the collision surface from the atomic beam and the molecular beam. ,
An atomic beam and molecular beam momentum measuring device comprising means for detecting the amount of displacement of the collision surface. 2. The atomic beam and molecule according to claim 1, wherein the means for displacing the collision surface by an amount proportional to the force received by the collision surface is a spring attached to the collision surface. Line momentum measuring device. 3. A means for detecting the amount of displacement of the collision surface, irradiating the collision surface or the back surface of the collision surface with laser light, and detecting the displacement of the reflected light by an optical position detector. The atomic beam and molecular beam momentum measuring device according to claim 1. 4. A means for bringing an electrode close to the back surface of the collision surface to detect a capacitance between the back surface of the collision surface and the electrode,
2. The atomic beam and molecular beam momentum measuring device according to claim 1, wherein the displacement amount of the collision surface is detected from the change in the electrostatic capacitance. 5. A means for detecting a tunnel current flowing between the back surface of the collision surface and the probe by bringing the probe close to the back surface of the collision surface, the tunnel current flowing through the probe is constant. 2. The atomic beam and molecular beam momentum measuring apparatus according to claim 1, wherein the displacement of the collision surface is detected from the displacement of the probe. 6. A means for converting a force received by the collision surface by collision of an atomic beam or a molecular beam into the collision surface into a rotational force of the collision surface, counting the number of revolutions of the collision surface, The atomic beam and molecular beam momentum measuring device according to claim 1, which measures the atomic beam and molecular beam momentum.