JP3199807B2 - Optical evaporation monitor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical evaporation monitor for measuring the intensity of excited luminescence generated when electrons collide with an evaporating substance and measuring the deposition rate of the evaporating substance from the measured value. Related to the configuration.

[0002]

2. Description of the Related Art There are two types of conventional devices of this type, one utilizing a cold cathode discharge and the other utilizing a hot cathode.
For example, as a device utilizing cold cathode discharge, Japanese Patent Publication No. 2-4
No. 8625, and an apparatus utilizing a hot cathode is disclosed in US Pat. No. 4,036,167. FIG. 2 shows the former configuration, and FIG. 3 shows the latter configuration.
Shown in

In the device shown in cross section in FIG.
Inside, a cylindrical box-shaped anode 16 is provided coaxially with the surrounding two disk-shaped cold cathodes 1a and 1b facing each other. The evaporant is configured to pass through a steam window 12 formed in the body of the cylinder, in a direction perpendicular to the plane of the drawing. A high voltage of 1 kV to 3 kV is applied between the cold cathodes 1 a and 1 b and the anode 16 by the power supply 13 to form the electric flux lines 8 (represented by dotted arrows). The permanent magnet 2 is arranged outside the anode 16,
The magnet forms a magnetic field indicated by the magnetic field lines 7 (represented by one thick arrow). The electrons (not shown) emitted from the cold cathodes 1a and 1b become the electron current rotating around the magnetic field lines 7 by the action of the mutually perpendicular magnetic field and electric field, and the excitation probability of the evaporating substance passing therethrough is remarkably improved. Then, excitation light of sufficient intensity is emitted from the evaporated substance.

An optical window 11 is provided on a side wall of the anode 16. Therefore, the excitation light 10 emitted from the evaporating substance is transmitted through the optical window 11 arranged in a direction perpendicular to the vapor flow path.
The light is taken out through the optical system introduction tube 15. The excitation light 10 is externally incident on a photodetector (not shown), and the emission intensity is measured by the detector. Then, the deposition rate of the evaporated substance (and the thickness of the deposited thin film by integrating the deposition rate over time) is measured from the emission intensity.

[0005] In the device whose essential part is shown in a perspective view in FIG. 3, thermoelectrons 18 are emitted from a heated filament 19, and the thermoelectrons 18 are used for electron acceleration to which a high voltage of 180 V to 200 V is applied. The anode 23 accelerates and advances in the direction indicated by the arrow. During the forward movement, the evaporating substance 9 introduced from the steam window 12 is irradiated.
The excitation light 10 generated by the electron collision is taken out to the outside by the optical system introduction tube 15 (the original position is indicated by a dashed line), and the same measurement as described above is performed.

[0006]

However, the conventional devices shown in FIGS. 2 and 3, respectively, exhibit sufficient performance when the evaporating substance is a single element such as a metal. When the substance is a compound, especially an oxide, there is a disadvantage that the deposition rate cannot be measured with sufficient accuracy.

[0007] For example, SiO ₂ and (silicon oxide) in the case of electron beam evaporation, the evaporation component generated by irradiation of the electron beam, Si many SiO ₂ is not remained SiO ₂ molecules, SiO, O It is known that they are included after being decomposed into the like. Molecules that have come to the optical vapor deposition sensor are subjected to electron impact inside the sensor, so that the decomposition tends to proceed further.

The most problematic here is the presence of oxygen. FIG. 4 shows an emission spectrum of oxygen for reference. The horizontal axis indicates wavelength (nm), and the vertical axis indicates emission intensity (relative intensity).
Is shown. Since oxygen has various transition states and energy states, the excitation light of oxygen is 200 nm to 600 nm.
It occurs broadly over the entire wavelength region of nm and has a strong intensity. Therefore, the excitation light of oxygen makes it difficult to separate and detect light having a wavelength of 252 nm or 288 nm, which is the main excitation light of Si, and makes it difficult to separate and measure the amount of evaporation of SiO ₂ .

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and accordingly, an object of the present invention is to provide a method for depositing a deposited film even when a compound or oxide is used as an evaporating substance. An object of the present invention is to provide an optical vapor deposition monitor device capable of measuring a film deposition rate with high accuracy.

[0010]

In order to achieve this object, a grid to which a negative potential is applied is provided inside a discharge chamber of an optical evaporation monitor, and the grid is used to move the discharge chamber in the direction of vapor movement. The apparatus is configured to divide into two chambers, a front chamber and a rear chamber, and to perform measurement using excitation light emission generated in the rear chamber for detection.

Electrons used for electron impact include those generated by cold cathode discharge, those generated by a hot cathode, and those generated by a combination of both.

[0012]

In the case of an oxide, generally, oxygen dissociated from the oxide becomes a negative ion. Since a negative potential is applied to the grid, oxygen of negative ions in the vapor flow path is confined in the front chamber 21, and only dissociated positive metal ions and neutral particles are stored in the rear chamber 22. proceed. Then, the excitation light is generated in the chamber 22 after this. Particles that have been once subjected to electron impact often remain in a metastable state without returning to a perfect ground state, but are in a state of being easily excited by the next electron impact. Therefore, when the above-described two-chamber structure is formed by using the grid, a double effect of reducing the excitation light of oxygen, which is an obstacle to measurement, and increasing the intensity of excitation light of the metal element can be obtained.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. It should be noted that the figures are to the extent that the present invention can be understood.
It merely shows the shape, size and arrangement of each component schematically. FIG. 1 is a view showing an embodiment of a cold cathode type optical evaporation monitor according to the present invention, in which (A) is a front sectional view and (B) is a plan sectional view.

Steam windows 120a, 1
20b and the optical window 110 are open. The yoke 3 of the opposed permanent magnets 2a and 2b forms a regular hexahedral box-shaped discharge chamber, and is electrically connected to the internal anode rods 4a and 4b. In addition, the discharge chamber incorporates the cold cathode 1 described above and the grid 5 introduced via the insulating stones 6a and 6b. The grid 5 is inserted in a direction perpendicular to the direction of the flow of the evaporating substance. Therefore, the above-mentioned discharge chamber is divided into two chambers, a front chamber 21 and a rear chamber 22.

The lines of magnetic force 7 are formed by the permanent magnets 2a and 2b. There is a power supply 13 for applying an electric field between the cold cathode 1 and the anode rods 4a and 4b, and a power supply 14 for applying a negative potential to the grid. Electric lines of force 8 are formed between them.

The evaporating substance 9 is introduced into the discharge chamber through the vapor window 12, and the excitation light 10 emitted inside the optical window 1
1 is configured to be taken out through the optical system introduction tube 15 to the outside.

Next, the operation of this apparatus will be described. The structure of each of the discharge chambers divided into two chambers 21 and 22 before and after by the grid 5 is substantially the center of the anode 4.
The cold cathode 1 and the grid 5 surround the outside, and have a so-called inverted magnetron type structure. Before this, electric fields of electric lines of force 8 are formed radially from the anode rods 4a, 4b in the center of the rear chambers 21, 22 toward the cold cathode 1 and the grid 5 surrounding the anode rods 4a, 4b, and further by the permanent magnets 2a, 2b. A magnetic field of the magnetic field lines 7 is formed in a direction orthogonal to the electric field. The electrons emitted from the cold cathode 1 by the action of the electric field and the magnetic field generate a rotating electron current around the magnetic field lines 7, travel a long distance, and stay in the discharge chamber for a long time. For this reason, the probability of collision with the evaporating substance 9 flowing from the vapor window 12a increases, and even when the amount of evaporation of the evaporating substance 9 is very small, a sufficient amount of excitation light 10 for measurement is generated.

The roles of the discharge chambers before and after are as follows.
The oxide evaporating substance 9 that has flown from the bottom of the figure is the vapor window 1
From 2a, first, it enters the front chamber 21, where it is further decomposed and ionized or excited by electron impact. Since a negative potential is applied to the grid 5 between the front and rear chambers 21 and 22, only positive ions and neutral particles are
And moves to the rear chamber 22, and all negative ions such as oxygen negative ions generated by decomposition of the oxide remain in the front chamber 21. That is, oxygen negative ions are confined in the front chamber 21, and only metal ions and neutral particles, which are dissociated positive ions, are guided to the rear chamber 22. Therefore, by detecting the excitation light in the rear chamber 22, oxygen harmful to the emission detection is removed, and the emission can be detected in a state rich in metal elements. In addition, particles that have once been impacted by electrons or the like in the front chamber 21 often do not return to a perfect ground state and remain in a metastable state, and in this case, they are very easily excited by the next electron impact in the rear chamber 22. In this state, the emission of the metal element in the rear chamber 22 has a higher intensity.

In this embodiment, the cold cathode power supply 13 and the grid power supply 14 are separately provided, and the case where the potentials of the cold cathode and the grid are different is shown. It is clear that the same effect can be obtained even when the potential of the grid is the same.

FIG. 5 is a front sectional view of an optical evaporation monitor according to another embodiment of the present invention. The same members as those in FIG. 1 are denoted by the same reference numerals. In this embodiment, the cold cathode 1 is removed from the apparatus shown in FIG. 1, and the grid 5 has a structure also serving as the cold cathode shown in FIG. Such a configuration is also possible.

FIG. 6 is a front sectional view of an optical vapor deposition monitor apparatus according to another embodiment of the present invention. In this embodiment, the configuration in which the anode rod 4 is further removed from the apparatus shown in FIG. 5 is employed. In this case, the wall surface of the yoke 3 also serves as the anode 16.

FIG. 7 is a front sectional view of an embodiment of the hot cathode type optical evaporation monitor of the present invention. The operation is the same as that of the cold-cathode type device, except that the electrons do not travel in the magnetron because no magnet is provided, and the electrons used for electron impact are extracted from the hot cathode 19. In this embodiment, the grid 5 and the Wehnelt electrode 20 are set to the same potential, but they may be set to different potentials using individual power supplies. Further, a total of two hot cathodes 19, which are electron sources, may be used in the front chamber and the rear chamber, respectively.

FIG. 8 is a front sectional view of an embodiment of a composite type optical vapor deposition monitor apparatus of a hot cathode type and a cold cathode type. The same operation as that of the cold cathode type in the front room 21 and the hot cathode type in the rear room 22 is performed. In this figure, the same effect can be obtained by replacing the cold cathode type and the hot cathode type in the front and rear chambers.

Although the above embodiment is an embodiment in which the discharge chamber is divided into two chambers, the same effect can be obtained by dividing the discharge chamber into three or more chambers and detecting the light emission of the last chamber as the rear chamber. is there. All but the last room can be considered as the front room.

[0025]

According to the present invention, it is possible to monitor compounds, oxides, and the like, which is difficult with the conventional optical-beam evaporation monitor of the excitation light detection type, thereby improving the detection sensitivity even in the detection of a single element. You can do it.

[Brief description of the drawings]

FIG. 1 is a diagram of an embodiment of a cold cathode type optical vapor deposition monitor device of the present invention, wherein (A) is a front sectional view and (B) is a plan sectional view.

FIG. 2 is a plan sectional view of a conventional optical vapor deposition monitor device using cold cathode discharge.

FIG. 3 is a plan sectional view of a conventional optical vapor deposition monitor device using hot cathode discharge.

FIG. 4 is a diagram of an emission spectrum of oxygen.

FIG. 5 is a front sectional view of an optical evaporation monitor according to another embodiment of the present invention.

FIG. 6 is a front sectional view of an optical evaporation monitor according to another embodiment of the present invention.

FIG. 7 is a front sectional view of a hot cathode type optical vapor deposition monitor device according to another embodiment of the present invention.

FIG. 8 is a front sectional view of a cold cathode / hot cathode combined type optical vapor deposition monitor device according to another embodiment of the present invention.

[Explanation of symbols]

1, 1a, 1b: cold cathode, 2: permanent magnet,
3: Yoke 4a, 4b: anode rod, 5: grid 6, 6a, 6b, 6c: insulating stone, 7: magnetic field line,
8: line of electric force 9: evaporating substance, 10: excitation light, 1
1: optical window 12, 12a, 12b, 120a, 120b: vapor window 13: power supply for applying an electric field between cold cathode and anode 14: power supply for applying voltage to the grid,
15: optical system introduction tube 16: anode, 17: outer wall,
18: electron 19: filament (hot cathode), 20: Wehnelt electrode 21: front chamber of discharge chamber, 22: rear chamber of discharge chamber,
23: Anode for electron acceleration

Claims (4)

(57) [Claims] 1. An evaporation rate of an evaporating substance is measured by exciting an evaporating substance by an electron impact in a discharge chamber and detecting an intensity of an excited luminescence generated when the excited evaporating substance returns to a ground state. In the optical vapor deposition monitor device, a grid for applying a negative potential is provided inside the discharge chamber, and the grid is divided into two chambers, a front chamber and a rear chamber, with respect to the traveling direction of vapor by the grid. An optical vapor deposition monitor device, wherein excitation light emitted in a chamber is used for detection. 2. The optical vapor deposition monitor device according to claim 1, wherein electrons used for the electron impact are generated by cold cathode discharge. 3. The optical vapor deposition monitor according to claim 1, wherein electrons used for the electron impact are generated by a hot cathode. 4. The method according to claim 1, wherein the electrons used for the electron impact are generated by both a cold cathode discharge and a hot cathode.
2. The optical vapor deposition monitor device according to 1.