JPH0342036Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a crystal oscillator for monitoring that detects the amount of a thin film formed on the surface of an object to be deposited based on the amount of change in vibration frequency. The present invention relates to a monitoring crystal oscillator that can control the amount of particles generated from a deposition source by preventing the generation of spurious waves, and can equalize the amount of thin films formed on a plurality of objects to be deposited.

[Technical background of the invention]

FIG. 2 is a schematic configuration diagram showing an example of a vapor deposition apparatus equipped with a conventional monitoring crystal resonator. In the figure, 1 is a vacuum container, and the inside of the container 1 is maintained at a low pressure by vacuum pumps 2 and 9. Reference numeral 3 denotes an object to be vapor-deposited, for example, a crystal piece on which metal particles serving as an electrode are vapor-deposited on a plate surface, and a mask corresponding to a desired electrode shape is disposed parallel to the plate surface. 4 is a crystal piece cut into a disk shape using an AT cut, for example, and has an excitation electrode formed on its main surface, and is a monitoring crystal resonator having a predetermined resonance frequency. At the time of vapor deposition of the object to be evaporated 3, metal particles are simultaneously vapor-deposited on the excitation electrode of the monitoring crystal resonator, and the vibration frequency is lowered. This method detects the amount of thin film formed. Reference numeral 5 denotes a heat source control device, which monitors the vibration frequency of the monitoring crystal oscillator 4, which decreases due to an increase in the mass of the electrode, and uses a metal The current applied to the heat source 7 that heats the evaporation source 6, which is a source of particles, is controlled. When the amount of thin film formed on the object 3 reaches a predetermined value, that is, when the vibration frequency of the monitoring crystal oscillator decreases to a predetermined value, the shutter 8 of the heat source 7 is activated to evaporate the film. The current is set to zero after the current is interrupted. Therefore, according to this vapor deposition apparatus, by setting the amount of change in the frequency of the monitoring crystal resonator to a predetermined value, a predetermined amount of a thin film can be formed on the deposition target 3.

By the way, the vapor deposition source 6 placed horizontally in the vapor deposition apparatus
The vapor deposition mass ratio of metal particles generated from is shown in Figure 3a,
Like the function curve shown in b, it is generally given by the following equation.

d(α)/d(o)=con ⁿ α...(1) However, α is the inclination angle from the center line extending perpendicularly from the evaporation source, and d(α) is the distance h from the evaporation source. A point Q in a distant horizontal plane tilted by an angle α
and d(o) are the deposition amount at a point P on the center line that intersects with the horizontal plane. n is a coefficient that determines the function (1) having the deposition rate as a variable.

Therefore, the distance between the object to be evaporated and the evaporation source and the angle formed by the main surface of the object to be evaporated and the installation surface of the evaporation source are appropriately selected so that the above equation always shows 1, and the evaporation rate is kept constant. By arranging the main surfaces of a plurality of objects 3 facing the vapor deposition source on a curved surface that faces the vapor deposition source obtained by , a uniform thin film can be formed. For this reason, the control device 5 described above controls the amount of decrease in the frequency of the monitoring crystal oscillator per unit time, that is, the deposition rate, so that the function curve in which the deposition density in the vacuum chamber 1 is uniform is always constant. The current flowing through the heat source 7 must be controlled to maintain a constant value. Note that when such a crystal oscillator for monitoring is used once or several times, the rate of change in frequency becomes slow, so it must be converted. Since it is not reasonable to replace the entire crystal resonator, it is desirable to be able to quickly replace only the crystal piece.

[Problems with background technology]

By the way, when the present inventors formed electrodes on the plate surface under the same conditions using this evaporation apparatus using a crystal piece as the object to be evaporated, and caused each to oscillate, there were cases where variations occurred in the oscillation frequencies that were supposed to be the same value. It turns out that there is something. The cause of this was that the amount of thin film deposited per unit time of the thin film forming the electrode formed on each crystal piece was different. That is, in order to investigate the cause of such variations in vibration frequency, before forming the electrodes by vapor deposition as described above, the vapor deposition was performed with special care so that each crystal piece was made under the same conditions down to the smallest details. Even so, the result was the same. Therefore, the present inventors conducted a detailed study on the interrelationship between the vibration frequency, which continuously decreases due to an increase in the electrode film thickness of the monitoring crystal oscillator during vapor deposition, and the current flowing to control the heat source, and reached the following conclusion. Ta. In Fig. 4, A shows the change in the frequency reduction rate of the monitoring crystal oscillator with time as the horizontal axis, and B in the same figure shows the change in the current flowing through the heat source due to the change in the frequency reduction rate in A. In the figure, the control device 5 controls the control current so that the rate of decrease in the vibration frequency due to the increase in the electrode film thickness of the monitoring crystal resonator is a constant value indicated by K in the figure.

That is, in the conventional system, the current flowing to control the heat source 7 fluctuates drastically over time.
Since a function curve with a constant vapor deposition mass ratio on the crystal piece cannot be obtained and the evaporation rate of the metal particles generated from the evaporation source 6 changes, the amount of metal particles deposited on the crystal piece fluctuates, causing variations in the vibration frequency. It was found that this occurs. The reason why the control current of the heat source 7 fluctuates drastically over time is that the oscillation frequency of the monitoring crystal oscillator, which should continuously decrease at a constant rate, sequentially combines with spurious waves and exhibits a jump phenomenon. This is because the vibration frequency changes discontinuously.

[Purpose of invention]

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a monitoring crystal resonator that can deposit a uniform amount of thin film onto a plurality of objects to be deposited.

[Characteristics of the solution]

By adding mass to the plate surface of the crystal piece where the thickness-based vibrations on which the electrodes are formed are excited, unnecessary vibrations that occur in response to the continuously changing vibration frequency during vapor deposition are controlled, and jumps in the vibration frequency are prevented. The crystal resonator is characterized in that it is applied to a monitor crystal resonator.

[Example of idea]

FIG. 1 is a side sectional view showing an example of a monitor crystal resonator. In the figure, numeral 11 is a round crystal piece with an AT cut cut at a predetermined angle with respect to the crystal axis of the crystal. This crystal piece 11 has excitation electrodes 111 and 112 formed in the center of the front and back surfaces, respectively, and these excitation electrodes 111 and 112 are connected to lead-out electrodes 113 and 112, respectively.
114 to the end of the plate surface. Then, the outer peripheral edges of the front and back plate surfaces of this crystal piece 11 are connected to the bottom plate 131 of the outer cylinder 13 and the conductive pressure plate 14 via a ring-shaped soft material 12 such as silicon rubber or carbon rubber.
It is sandwiched between. The outer cylinder 13 is a metal cylinder with a bottom, and has a through hole 132 formed in the center of the bottom plate. A lid 15 made of an insulating material is screwed onto the open end of the outer cylinder 13, and a spring 16 is inserted between the lid 15 and the conductive pressure plate 14 to elastically hold the crystal piece 11. I try to do that. Note that an appropriate insulating plate 17 is interposed between the outer peripheral edge of the crystal piece 11 and the inner wall of the outer tube 13 to provide electrical insulation. and lid body 15
A contact 18 is provided at the center of the crystal blank 11 so that one electrode formed on the crystal piece 11 is led out through the spring 16 and the conductive pressure plate 14, and the other electrode is led out through the outer cylinder 13. Also conductive pressure plate 1
4 is a crystal piece 1 with a through hole 141 bored at an appropriate position.
The pressure on the front and back plate surfaces of No. 1 is made to be equalized. Therefore, the crystal piece 11 is attached to the bottom plate 1 of the outer cylinder 13.
31, and a lid 1 screwed onto the open end of this outer cylinder 13.
5, the outer peripheral edge is held between a ring-shaped soft material 12 and held elastically by the elasticity of a spring 16 applied via a conductive pressure plate 14. Further, one electrode 111 formed on the plate surface of the crystal blank 11 is led out through the spring 16, and the other electrode 112 is led out through the outer cylinder 13. Therefore, by unscrewing the screw between the lid 15 and the outer cylinder 13, the crystal piece 11 can be easily taken out or replaced.

5 is a sectional view taken along the line D--D in FIG. 1, and FIG. 6 is a bottom view of FIG. 1.

Then, the monitoring crystal resonator shown in Fig. 1 is placed in a vacuum container as shown in Fig. 2, and the electrodes are deposited by placing it in an atmosphere of metal vapor together with a large number of crystal pieces placed in this container. Of course.

In this way, since the outer periphery of the monitor crystal resonator is elastically held, the degree of freedom with respect to displacement during vibration is high, and thereby the generation of spurious waves can be minimized. Therefore, a jump does not occur when the resonance frequency changes due to an increase in the electrode film thickness during vapor deposition, and there is no sudden change in the current flowing to the heat source that heats the vapor deposition source.

FIG. 7 shows changes in the amount of frequency reduction (E in the figure) and changes in the current flowing through the heat source (F in the figure) when vapor deposition is performed using the monitoring crystal resonator shown in FIG. As is clear from this figure, the rate of change in frequency can be kept almost constant, and the current flowing through the heat source can also be kept almost constant, so the constant function curve of the vapor deposition mass ratio in the vacuum container does not change. do not have. Therefore, by arranging multiple deposited objects, such as crystal pieces, on a preset function curve, a crystal resonator of constant quality can be formed with a uniform amount of thin film and no variation in vibration frequency. can do.

In addition, in this example, the object to be evaporated is described as a crystal piece, and the evaporation particles are metal. However, the object to be evaporated is not limited to a crystal piece, and the evaporation particles are not limited to metal either. Needless to say.

[Effect of idea]

As described above, according to the present invention, it is possible to provide a monitoring crystal resonator that can suppress the generation of spurious as much as possible, thereby making the amount of thin film deposited per unit time uniform.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view showing an example of a monitoring crystal oscillator used in an embodiment of the present invention, FIG. 2 is a schematic configuration diagram showing an example of an electrode vapor deposition apparatus, and FIGS. 3a and 3b. 4 is a diagram explaining the deposition quality ratio when placed parallel to the evaporation source, FIG. 6 is a bottom view of the vibrator shown in FIG.
The figure is a diagram showing changes in the frequency and current of the monitoring crystal oscillator in a device using the monitoring crystal oscillator shown in FIG. DESCRIPTION OF SYMBOLS 1... Container, 3... Crystal piece, 4... Crystal resonator for monitoring, 5... Control device, 6... Evaporation source, 1
2... Soft substance.

Claims (1)

[Claims for Utility Model Registration] Particles generated from a vapor deposition source are attached to electrodes formed on the plate surface of the object to be vaporized and a crystal resonator, and the mass of the particles is changed depending on the mass of the particles attached to the electrodes of the crystal resonator. In a monitoring crystal oscillator that detects the amount of a thin film formed by the particles adhering to the vapor deposited body from the amount of change in the vibration frequency, the outer part has a through hole in the bottom plate and a lid screwed to the opening end. The outer periphery of the tube and the front and back plates are connected to the bottom plate and the conductive material through a ring-shaped soft material that suppresses unnecessary vibrations generated in response to the vibration frequency of the crystal resonator that continuously changes depending on the mass of the particles. A monitor comprising: a crystal piece held between a pressure plate; and a spring inserted between the lid body and the conductive pressure plate to elastically hold the crystal piece. crystal oscillator.