JPH0321830A - Guided-in light selector - Google Patents

Abstract

PURPOSE:To scan an observation position electronically and to shorten the time required for the scanning by providing a Faraday rotator group, an incidence-side polarizing plate and a projection-side polarizing plate, and a magnetic field application control means. CONSTITUTION:The guided-in light selector 8 is equipped with a Faraday rotator glass fiber array (Faraday rotator group) 10 and the incidence-side polarizing plate 11 and projection-side polarizing plate 12 which are provided opposite each other across the array 10. The array 10 is formed by arranging Faraday rotational glass fibers longitudinally. The respective glass fibers rotate planes of polarization of passing light by a specific angle by being applied with a magnetic field. Electromagnetic coils wound around the glass fibers respectively are connected to the magnetic field application control means 13. The control means 13 is connected to a power source 14, which feeds electricity selectively to only glass fibers to be applied with the magnetic field. Consequently, the Faraday rotational glass fibers can be scaned electronically.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention is a method for introducing a part of this light into a spectrometer when light is spatially distributed in a chamber such as in a plasma CVD apparatus. Introducing the optical selector. [Prior Art] For example, in a plasma CD device as a thin film type device, parallel plate electrodes are arranged in a chamber, and a high frequency is applied between the parallel plate electrodes to generate plasma between the two electrodes. The film is deposited on a substrate placed on an electrode connected to the ground side. In an apparatus that performs thin film formation using such a plasma CVD method, by observing the discharge state in the chamber, that is, the plasma light, it is possible to determine the state of the introduced reactant gas (ionization, excitation state, etc.). ), and it can also be used to determine the density of excited and activated gas molecules and atoms. Furthermore, the deposition speed of the film formed on the substrate and the compositional ratio of the film formed on the substrate can be determined by analyzing plasma light. Furthermore, since the way of light emission is different between the center of the plasma region and the vicinity of the top surface of the substrate, the plasma light at each position in the plasma region is introduced into a spectrometer to perform spatial emission intensity measurement and emission spectrum analysis. By doing so, the opposite. You can understand the overall mechanism of the reaction.

Therefore, in conventional devices, a viewing window is constructed from quartz glass or the like on the side wall of the chamber, and the plasma light is introduced from this viewing window into a spectrometer through a light introduction slit, etc., and the plasma light is analyzed. That's what I do. In addition, spatial analysis can be performed by moving the spectrometer itself and the light introduction fiber connected to the spectrometer up and down according to the observation position. [Problems to be Solved by the Invention] As mentioned above, in conventional devices, when measuring the spatial distribution of emission spectra, the light introduction mechanism such as a spectrometer or an optical fiber for light introduction is mechanically moved up and down. ing. Therefore, there is a delay in the time it takes to move the light introduction mechanism to the target observation position. Plasma CVD equipment and E, which performs film deposition in a higher vacuum than plasma CVD equipment.
In a CR plasma CVD apparatus, the time required for a reactive gas introduced into a chamber to be excited, ionized or reacted, and deposited on a substrate is fast. Therefore, in order to understand the overall reaction mechanism, it is necessary to repeatedly scan the light introduction mechanism described above at high speed. There is a limit to the reduction in scanning time.
An object of the present invention is to provide an introduced light selector that can shorten the scanning time of a light introduction mechanism and easily perform spatial emission intensity measurement and emission spectrum analysis.

[Means to solve the problem]

The introduced light selector according to the present invention is for introducing a part of spatially distributed light into a spectrometer. and,
Magnetic field application control that controls the timing of applying a magnetic field to a Faraday rotator group, an entrance side polarizing plate and an output side polarizing plate that are arranged to face each other with the Faraday rotator group in between, and each of a plurality of Faraday rotators. It is equipped with the means. The Faraday rotator group is made up of an array of Faraday rotators that rotate the polarization plane of passing light by a predetermined angle by applying a magnetic field.

Further, the incident-side polarizing plate and the exit-side polarizing plate are arranged such that their polarization plane selection directions are shifted by the polarization plane rotation angle of the Faraday rotator.

[Effect]

In this invention, for example, plasma light generated in a certain film chamber enters the incident-side polarizing plate of the introduced light selector through a viewing window on the side wall of the chamber. Since this polarizing plate on the incident side has a plane of polarization in a specific direction, the light that passes through the polarizing plate on the incident side has a fixed plane of polarization. The light that has passed through this incident-side polarizing plate enters the Faraday rotator group.

A magnetic field is applied to a Faraday rotator at a predetermined position among the Faraday rotators from a magnetic field application control means,
The light passing through the Faraday rotator to which this magnetic field is applied is rotated by a predetermined angle. An exit side polarizing plate is disposed on the exit side of the Faraday rotator, and the polarization plane selection direction of the exit side polarizing plate is different from the polarization plane selection direction of the input side polarizing plate of the Faraday rotator. It is shifted by the rotation angle of the polarization plane. Therefore, among the light that has passed through multiple Faraday rotators, only the light that has passed through the Faraday rotator to which a magnetic field has been applied can pass through the exit side polarizing plate, and only the light at a specific position can be passed through the spectroscope. is input.

By sequentially scanning the Faraday rotator to which the magnetic field is applied, the observation position can be moved. [Embodiment] FIG. 3 is a schematic diagram showing a plasma CVD apparatus using an introduced light selector and its plasma light measurement system according to an embodiment of the present invention. Chamber 1 of plasma CVD equipment
Inside, parallel plate electrodes 2 and 3 are arranged facing each other in the vertical direction. On the upper surface of the lower electrode 3, there is a substrate 4 to be coated.
is arranged, and a heater 5 is provided below the lower electrode 3. A high frequency power source 6 is connected to the upper electrode 2, so that high frequency can be applied between the two electrodes 2 and 3. The chamber 1 is provided with a reaction gas inlet for introducing a reaction gas between the electrodes 2 and 3, and an exhaust port for exhausting the inside of the chamber 1.

A viewing window 7 made of quartz glass or the like is provided on the side wall of the chamber 1, and an introduction light selector 8 is provided on the side of this viewing window 7. The output of the introduced light selector 8 is input to a spectrometer 9. Figure 1 shows the structure of the introduced light selector 8. The introduced light selector 8 is provided with a Faraday rotator glass fiber array (Faraday rotator group) 10 and a polarized light beam on the incident side, which is provided to face the Faraday rotator glass fiber array (hereinafter simply referred to as a glass fiber array). Board 11
and an output side polarizing plate 12. The glass fiber array 10 is formed by arranging a plurality of Faraday-rotated glass fibers (hereinafter simply referred to as glass fibers) in the vertical direction. Each of the glass fibers is used to rotate the polarization plane of passing light by a predetermined angle by applying a magnetic field.

Note that the direction of rotation of the plane of polarization is determined only by the direction of the magnetic field and does not depend on the direction in which the light travels. In a paramagnetic material, the rotation angle θ of the plane of polarization has the relationship θ−VHf, where the length of the glass fiber is l and the applied magnetic field strength is H. Here, ■ is the Verdet constant, which is a coefficient representing the magnitude of Faraday rotation. In this example, the applied magnetic field strength H and the length l of the glass fiber are each set so that the rotation angle θ of the plane of polarization is 90'. The input side polarizing plate 1j has a polarization plane selected in the horizontal direction, and the output side polarizing plate -12 has a polarization plane selection direction in the vertical direction. In this way, the polarization plane selection direction of the input-side polarizing plate 11 and the polarization plane selection direction of the output-side polarization plate 12 are arranged to be shifted by the polarization plane rotation angle (90°) of the glass fiber. As shown in FIG. 2, an electromagnetic coil 16 for applying a magnetic field is wound around each of the glass fibers 15. In addition, the electromagnetic coil 1
A magnetic shield 17 is provided around the outer periphery of the magnetic shield 6. The electromagnetic coil 16 of each glass fiber 15 is connected to the magnetic field application control means 13 shown in FIG. This magnetic field application control means 13 is connected to the power supply 14, and selectively energizes only the glass fibers to which a magnetic field is to be applied.

Next, the operation will be explained.

First, with reference to Figure 4, we will explain the principle of light extraction when using a Faraday rotating glass fiber. Incident light Li
has a random plane of polarization. When the incident light Li passes through the incident-side polarizing plate 11, the incident-side polarizing plate 11 allows only the horizontal polarization plane to pass through, so that the polarization plane of the light on the entrance side of the glass fiber 15 is horizontal. This light is applied to a glass fiber 15 to which a magnetic field is applied.
When the light is incident on the light, its plane of polarization rotates as the light travels. As mentioned above, the length l of the glass fiber 150 and the intensity H of the applied magnetic field are set so that the rotation angle of the polarization plane is 90°, so the polarization plane of the light emitted from the glass fiber 15 is is in the vertical direction. Since the polarization plane selection direction of the output-side polarizing plate 12 is set to the vertical direction, the light rotated by the glass fiber 15 passes through the output-side polarizing plate 12 and is sent to the spectrometer 9 side as output light Lo. is output to . In the introduced light selector 8 of this embodiment, the glass fibers 15 as described above are arranged in an array in the vertical direction. Therefore, as shown in FIG. 5, if the plasma between the parallel plate electrodes 2 and 3 is schematically shown as an arrow P, the magnetic field H is applied only to the glass fiber at the lowest position by the magnetic field application control means 13. If you keep it, plasma light P
Only the light P at the lowest end of the light beams is rotated by passing through the glass fiber 15, and the light P is rotated by passing through the glass fiber 15.
It is selectively emitted from 2. Other parts of plasma light P! Although the horizontal plane of polarization passes through the incident side polarizing plate 11, since the magnetic field H is not applied to the glass fiber corresponding to the Pt portion, this polarization plane passes through the glass fiber as it is, and the vertical plane passes through the incident side polarizing plate 11. It cannot pass through the output side polarizing plate 12 which has a polarization plane selection direction.

Next, by applying the magnetic field H only to the second glass fiber from the bottom, only the plasma light above P+ can be selectively extracted by the same operation as described above. In this way, by sequentially scanning the glass fiber to which a magnetic field is applied, the spatial distribution characteristics of the spectrum within the chamber 1 can be obtained.In this example, the Faraday rotating glass fiber is electronically scanned. This makes it possible to repeatedly scan at a much higher speed than conventional mechanical vertical movement, making it possible to analyze reaction mechanisms in vacuum. [Other Examples] (a) In the above embodiment, the polarization plane selection direction of the incident side polarizing plate 11 was set to the horizontal direction, and the polarization plane selection direction of the output side polarizing plate l2 was set to the vertical direction. 11 and 1
The two polarization plane selection directions may be opposite to each other.

(b) Furthermore, the polarization plane selection directions of the incident side polarizing plate 11 and the output side polarizing plate 12 are not limited to a specific angular direction, and the angular shift between the polarization plane selection directions of both is set to 90°. It is enough if it is. (C) In the above embodiment, the angular deviation between the polarization plane rotation angle in the Faraday rotary glass fiber 15 and the polarization plane selection direction of the input side polarizing plate and the output side polarizing plate is 90°.
However, this angle is not limited to 901. That is, it may be set to 45'' or 60°, for example, as long as the rotation angle of the polarization plane of the Faraday rotary glass fiber and the angular deviation of the polarization plane selection direction of the input side polarizing plate and the output side polarizing plate are the same. ( b) In the above embodiment, the magnetic field was applied one by one in the vertical direction in the Faraday rotating glass fiber array, but it is also possible to change the combination of fibers to which the magnetic field is applied.

For example, a magnetic field can be applied simultaneously to multiple fibers at a predetermined interval, or a magnetic field can be applied simultaneously to multiple adjacent fibers, and the combinations of these multiple fibers can be sequentially shifted. , any combination is possible. (e) In the above examples, the present invention was used to analyze the emission spectrum of a plasma CVD device, but it can also be applied to investigating the spatial distribution characteristics of the spectrum in other devices, such as an emission spectrometer. Of course. [Effects of the Invention] As described above, in the present invention, the Faraday rotators are arranged in an array, and the timing of applying the magnetic field to each Faraday rotor is controlled, so the observation position can be electronically adjusted. The time required for scanning can be significantly reduced.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of the structure of an introduction light selector according to an embodiment of the present invention, FIG. Figure 3 is a schematic configuration diagram of a plasma CVD apparatus in which the introduced light selector is used;
The figure is a diagram for explaining the basic principle of the present invention, and FIG. 5 is a diagram for explaining the operation of the introduced light selector.

Claims (1)

[Claims] (1) An introduction light selector for introducing a part of spatially distributed light into a spectrometer, in which Faraday rotators are arranged in an array to rotate the polarization plane of passing light by a predetermined angle by applying a magnetic field. a group of Faraday rotators, and an input-side polarizing plate and an output-side polarizing plate that face each other across the Faraday rotator group and are arranged such that the polarization plane selection direction is shifted by the polarization plane rotation angle of the Faraday rotator. and a magnetic field application control means for controlling the timing of applying a magnetic field to each of the plurality of Faraday rotators.