JPS58223009A - Crystal oscillation type film thickness monitor - Google Patents

Abstract

PURPOSE:To improve working efficiency, by providing a means, which heats a sensor of a monitor comprising a crystal oscillator, in the vicinity of a container. CONSTITUTION:Pressure in a vacuum container is restored. Before the next evaporating process is started, a valve of a cooling water pipe 8 is closed so as to stop cooling water. When a heater 7 is conducted, heat is conducted through a sensor front cover 41 and a crystal holder 10 and reaches a sensor 9. Then the sensor 9 is heated. Moisture and the like, which are adsorbed to minute particles that are attached to the sensor 9 at the previous evaporating process, are quickly removed. At this time, since the heat of the heater 7 is also conducted to a sensor body 42, the temperature is measured by a thermocouple 12. It is desirable that the heating temperature is 150 deg.C or more. After the enough heating, the current conduction to the heater 7 is stopped, valve is opened, the cooling water is flowed through the cooling water pipe 8, and the temperature of the container and the sensor 9 enclosed in the container is decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a film thickness monitor for measuring the thickness of a thin film formed on ceramic or the like by a method such as vacuum evaporation or sputtering.

The vacuum evaporation and sputtering described above are methods for forming a thin film by colliding and depositing fine particles of a film-forming substance on the surface of a material such as a ceramic in a vacuum. A crystal oscillation type film thickness monitor, which is generally used to monitor the thickness of thin films formed using these materials, is a method in which a sensor consisting of a crystal oscillator is placed in a vacuum container alongside the above-mentioned material, and the sensor is placed under the same conditions as the material. By attaching fine particles of the above substances to the sensor and detecting the change in oscillation frequency due to the change in mass of the sensor, the thickness of the thin film formed on the material can be detected in terms of conversion. be.

Figure 1 shows the configuration of an apparatus generally used when forming thin films by vacuum evaporation. A molybdenum or tungsten boat is placed inside a hard glass vacuum vessel 1 connected to a vacuum pump (not shown). 2 is installed. This boat 2 is energized by an energizing means (not shown) and generates resistance heat. A pellet-shaped thin film forming substance A is placed in the port 2, and when it is heated by the heat generated by the port 2 in a vacuum, it becomes vapor particles and emits it.

On the other hand, a jig (not shown) is placed above the vacuum container 1.
A material 3 such as ceramic is disposed facing the direction of the boat 2. A film thickness monitor container 4 is provided in close proximity to this material 3 using a jig (not shown). A sensor called υ such as a crystal oscillator is housed in this container 4, and an opening is provided at the bottom of the container 4, and the emitted vapor particles pass through this opening and are almost identical to those in material 3. Depending on the conditions, it adheres to the sensor and its oscillation frequency changes.

Container 4 has a signal cape A151 that sends a sensor output signal.
One end of the cable is connected, and the other end of this cable reaches a measuring device 5 outside the vacuum vessel 1. In addition, a cooling water conduit 8 through which cooling water flows is wound around the outer circumference of the container 4 in order to prevent the temperature of the container 4 from rising due to radiant heat from the boat 2 during thin film formation. A pulp 81 is provided to adjust the flow of cooling water.

By the way, when the vacuum container l is returned to the atmosphere for exchanging materials, etc., gas components in the atmosphere, especially moisture, are adsorbed by the fine particles adhering to the sensor. In the film thickness monitor, new particles are attached to the sensor in the next film formation process on top of the particles that were attached to the sensor in the previous film formation process, and the newly formed film is measured by the increase in the weight of the sensor at this time. Since the thickness is to be measured, if the moisture adsorbed during the above-mentioned pressure restoration is desorbed during the next film forming step, the mass reduction of this desorbed moisture will cause a measurement error. Conventionally, before starting film formation, it was necessary to perform a long period of evacuation to remove moisture from the sensor. The rate of desorption of this water is very slow, and it takes several hours to completely remove the water. , :
It takes.

The present invention provides a crystal oscillation type film thickness monitor, in which water adsorbed to the fine particles adhering to the sensor is actively desorbed by providing means for heating the sensor of the monitor made of a crystal oscillator, The aim is to significantly shorten the time required for desorption and increase work efficiency.
Here, as the heating means, either heating by conduction heat transfer or heating by radiation heat transfer may be used.

The present invention will be explained below with reference to illustrated embodiments.

FIG. 2 shows the first embodiment, which is an example in which heating by conduction heat transfer is used. The film thickness monitor container 4 has a sensor front cover 41 as a lower half and a sensor body 42 as an upper half.
A hole 41a is provided in the center of the bottom surface of the sensor front cover 41. The sensor 9 consists of a circular thin-plate crystal oscillator 91 and electrodes 92 (only one of which is shown) bonded to the top and bottom surfaces of the crystal oscillator 91, and a metal crystal holder 10.
It is stored in. A hole 10a having the same shape as the hole 41a of the sensor front cover 41 is provided at the center of the bottom surface of the crystal holder 10. A glue retainer 11 made of insulating ceramic is fitted into this crystal holder 10. A plurality of leaf spring members 11a are provided on the bottom surface of the retainer 11, and are brought into elastic pressure contact with the electrodes 92 when the retainer 11 is fitted. The proximal end of the leaf spring member 11a penetrates the bottom surface of the retainer 11,
It is connected to the electrode 11j) formed on the entire upper surface of the bottom surface.

The crystal holder 10 and retainer 11, which house the sensor 9 and are integrated as described above, are attached to the sensor front cover 41.
Store it in. At this time, punch hole 1 of crystal holder 10
The positions of the hole 41a of the sensor front cover 41 and the position of the hole 41a of the sensor front cover 41 match. In this state, sensor front cover 411C
When the sensor body 42 is mounted, a spring member (not shown) provided on the sensor body 42 is pressed into contact with the tixlb of the retainer 11. This spring member is attached to the sensor body 4.
It is connected to a connector 52a provided on the outer peripheral surface of 2.

The connector 52a has a mating connector 521)
Therefore, the signal cape/1151 is connected. Therefore, the output signal of the sensor 9 is transmitted from the electrode 92 attached to the top surface of the crystal oscillator 91 to the leaf spring member 1 of the retainer 11.
1a, electrode 111) to reach connector 152a, and from an electrode (not shown) attached to the lower surface of crystal oscillator 91 to connector 52a via each main body of crystal holder 10, sensor front cover 41, and sensor body 42. The signal is input via a signal cable 51 to the measuring device 5 (FIG. 1) outside the vacuum vessel 1 via both paths.

A thermocouple 12 having a washer-shaped tip is screwed onto the sensor body 42 to measure the temperature of the film thickness monitor container 4.

On the other hand, the sensor front cover 41 to which the cooling water conduit 8 is attached as described above is provided with the heater 7 which is the heating means of the present invention. The heater 7 has a metal protection tube 72 wound around the outer periphery of the front cover 41, and an insulating coated nichrome heater (not shown) housed inside the tube.

- The protection tube 72 and the outer peripheral surface of the front cover are welded all around, and both ends of the protection tube 72 are integrally joined to the connector 71a. A power cape/L'71 is connected to the connector 71b that is paired with the connector '71a, and the other end is connected to a power source (not shown) outside the vacuum vessel l (FIG. 1).

Next, the operation of the film thickness monitor according to the present invention will be described.

Before repressurizing the vacuum container 1 and proceeding to the next vapor deposition process, the valve 81 of the cooling water conduit 8 is closed to stop the cooling water. Next, when the heater 7 is energized, the heat of the heater 7 is conducted through the sensor front cover 41 and the crystal holder 10 and the sensor 9
The sensor 9 is heated, and moisture and the like adsorbed by the fine particles that adhered to the sensor 9 in the previous vapor deposition step are quickly desorbed. At this time, the heat of the heater is also transmitted to the sensor body 42, so the temperature is measured with the thermocouple 12. This heating temperature is 1
It is desirable to keep the temperature at 50°C or higher. Although the heater 7 may be energized at any time during the deposition preparation period, it is more efficient to energize the heater 7 after the vacuum is sufficiently high.

After sufficient heating, stop energizing the heater 7 and close the valve 81.
The container 4 is opened and cooling water is allowed to flow through the cooling water conduit 8 to lower the temperature of the container 4 and the sensor 9 housed therein. The thermocouple 1 attached to the sensor body 42 indicates that the temperature has decreased sufficiently.
Confirm by 2.

After the moisture in the sensor 9 is sufficiently and quickly removed in this way, the next vapor deposition step is started.

As described above, according to the crystal oscillation type film thickness monitor according to the present invention, moisture etc. adsorbed to the fine particles of the thin film forming substance attached to the crystal oscillator serving as the sensor are removed by the heater wound around the monitor. Thermal desorption can be carried out quickly, and the preparation time for vapor deposition, which conventionally required a long time, can be dramatically shortened.

FIG. 3 shows a second embodiment of the present invention, and is an example of heating by radiant heat transfer. Since the surface of the film-forming substance is contaminated by adhesion of atmospheric moisture, etc., the material and film thickness monitor should be closed with a shutter during the early stages of vapor deposition to prevent contaminated film-forming substance vapor from adhering. ing. In this embodiment, a heater 7 is installed on the upper surface of a shutter 13 which is supported by a support column 14 and is rotatable. A heater protection tube 72 is provided in a corrugated shape by welding on almost the entire surface of the shutter 13, and a coated nichrome wire is housed in the protection tube 72 as in the previous embodiment. Also thermocouple 12
is attached to the bottom surface of the sensor front cover 41.

In this embodiment, the sensor is directly heated by radiation from the heater through the hole 41a. The temperature rise due to this radiant heat is measured by the thermocouple 12 attached to the bottom of the sensor Freon F cup-41. The present embodiment is not limited to the nichrome heater, but a heating pump may be attached to the shutter to serve as a radiant heating means.

In the above embodiment, the heating temperature and cooling temperature are confirmed using a thermocouple, but the energizing voltage and energizing time of the heater are determined in advance based on the capacity of the heater and the heat capacity of the sensor section, and the cooling time is also determined in advance. If the length is long, the above thermocouple is not necessarily required.

As described above, according to the present invention, the crystal oscillator of the crystal oscillation type film thickness monitor can be regenerated in a very short time. This greatly contributes to improving work efficiency and film thickness measurement accuracy.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of a conventional device for forming thin films by vacuum evaporation, FIG. 2 is an exploded perspective view of the first embodiment of the crystal oscillation type film thickness monitor of the present invention, and FIG. Second fruit〃1-
FIG. 2 is an overall perspective view of an example. 4...Crystal oscillation type membrane j4j monitor container 41a
...hole 7 in the container of the crystal oscillation type film thickness monitor...
... Heater (heating means) 72 ... Heater protection tube 13 ... Shutter member 91 ... Crystal oscillator Fig. 1 Fig. 2 Fig. 3 Fig. 42

Claims (3)

[Claims] (1) In a crystal oscillation type film thickness monitor that has a crystal oscillator built into the container and has a hole in the container for introducing fine particles of a film-forming substance into the container, the oscillator is placed close to the container. A quartz crystal film thickness monitor characterized by being provided with a heating means for heating and evaporating attached moisture. (2) The crystal oscillation type film thickness monitor according to claim 1, wherein the heating means is constructed by winding a protective tube with a nichrome wire heater inside the container around the container. (3) The crystal oscillation type film thickness monitor according to claim 1, wherein the heating means is constructed by attaching a radiant heating source to a shutter member for opening and closing a hole provided in the container.