JPS59232269A - Vacuum device - Google Patents

Abstract

PURPOSE:To provide a vacuum device which prevents soar-up of dust owing to the gaseous flow in a vessel and reduces the time for evacuation by providing a fluid throttling means in a fluid flow passage between the vessel and an evacuating pump and decreasing gradually the resistance of the flow passage with time. CONSTITUTION:A stop valve 305 for evacuation and a fluid restricting means 304 of which the flow passage resistance decreases gradually with time are connected between a vacuum vessel 301 and a vacuum pump 303 which evacuates the inside thereof. Said means 304 is constituted of a fluid throttling valve 306 and a means 307 for driving the throttling valve. The valve 306 is opened at a prescribed speed to decrease the flow passage resistance with time in the stage of evacuating the inside of the vessel 301. The change rate of the pressure in the vessel 301 is thus maintained constant and the state of preventing soar- up of the dust in the vessel 301 by the gaseous fluid is assured; moreover, the evacuation is completed in short time.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to the structure of a vacuum apparatus used for vacuum evaporation and the like.

Structure of conventional examples and their problems In recent years, vacuum evaporation technology has become indispensable to the semiconductor and optical industries, and plays a major role in thin film formation technology.

A vacuum evaporation apparatus is composed of two parts: a vacuum apparatus and a heating source for heating and evaporating a evaporation source. As shown in FIG. 1, the vacuum device is mainly composed of a container 101 and an evacuation means 102 for evacuating the inside of the container. Usually, the exhaust means 102 includes an exhaust pump 103 and this exhaust pump 10.
3 and the container 101.
and an exhaust opening/closing valve 105 connected in series thereto. The exhaust opening/closing valve 105 is the exhaust pump 103
The fluid throttle valve 104 is a valve that directly connects the container 101 and puts the container 101 into the exhaust state, and the fluid throttle valve 104 regulates the exhaust speed in the throttle state.

The time Δt required for a container with a volume V to go from atmospheric pressure P1 to P2 is the time required for a container with a volume V to reach the target pressure P2, assuming no gas flows in from the outside and when the pumping speed S is constant. It can be seen that Δt is inversely proportional to the pumping speed S.

FIG. 2 is an example of the experimentally determined relationship between pressure and time when a container at atmospheric pressure is evacuated at each evacuation speed S. As the pumping speed S becomes smaller, the rate of change in pressure over time becomes smaller, and the time it takes to reach a certain predetermined pressure also becomes longer in inverse proportion to the pumping speed.

In recent years, there has been a trend toward dust-free vacuum deposition, and it is often necessary to perform deposition in a highly clean atmosphere. For example, if there is dust attached to the substrate to be evaporated before vapor deposition, the evaporated film will be formed on top of the dust, which will not only impair the device characteristics but also cause the evaporated film to fall off along with the dust and cause pinholes. .

This may cause defects such as dropouts. For this reason, as higher density devices are desired, cleaning the atmosphere during vapor deposition has become an important issue and a key point in quality.

However, in vacuum evaporation, there is no problem if all the deposited film is deposited only on the object to be deposited and the location to be deposited, but the result is that the deposited film also adheres to other locations within the container. As the vapor deposition is repeated, the vapor deposited film deposited inside the container undergoes a peeling phenomenon, and the film that accumulates at the bottom of the container becomes easily peeled off, if not peeled off.

As a result, when a vacuum container is initially drawn from atmospheric pressure to a vacuum by an evacuation means, a large gas flow outside the container causes dust such as vapor deposits attached to the container or accumulated at the bottom of the container to fly up. This results in the deposition target being contaminated. Therefore, as a countermeasure, it is effective to reduce the gas flow when evacuating the container by reducing the evacuation speed S, but this has the disadvantage that the evacuation time until the target pressure is reached is extremely long. appears on the other hand.

Purpose of the Invention The present invention solves the above-mentioned conventional problems.When a vacuum container such as a vapor deposition apparatus is evacuated, the dust attached to the container or accumulated at the bottom is blown up by the gas flow and the object to be evaporated inside the container is blown up. It is an object of the present invention to provide a vacuum device that can prevent the container from being contaminated and complete the evacuation of the container in the shortest possible time.

Structure of the Invention The present invention includes a container and an evacuation means for evacuating the inside of the container, and the evacuation means is connected to an evacuation pump, and the evacuation pump is inserted into the container, so that the flow path resistance gradually decreases over time. The container is constructed of a fluid throttling means for evacuating the container, and an exhaust opening/closing valve connected in series to the fluid throttling means, thereby preventing dust from flying up at the beginning of evacuation and completing the evacuation of the container in the shortest possible time.

Description of examples Embodiments of the present invention will be described below with reference to the drawings.

FIG. 3 is an explanatory diagram thereof, and when the vacuum container 301 is evacuated by the exhaust pump 303, it is constituted by a throttle valve driving means 307 that opens a direct throttle between the two at a required speed. The dependence of road resistance R on time t is realized. By gradually decreasing the flow path resistance R with time t as shown in FIG. 4, when the container is evacuated from atmospheric pressure, the rate of change in pressure over time can be kept constant. That is, when the pumping speed S is constant, as the pressure decreases as shown by the broken line in FIG. By gradually decreasing the flow path resistance 2 over time, the rate of change in pressure over time can be made almost uniform as shown by the solid line in FIG. 5, and the time required for evacuation can also be shortened.

Therefore, at the beginning of evacuation, the container 301 and the vacuum pump 3
After increasing the flow path resistance of the throttle valve 306 between 03 and ensuring that no dust is raised, the flow path resistance was gradually decreased to keep the rate of change in pressure over time constant.

As a result, dust was prevented from flying up, and the exhaust time required to reach a predetermined pressure was shortened.

As a throttle valve driving means for opening the throttle valve 306 between the container 301 and the exhaust pump 303 at a predetermined speed, the means shown in FIG. 6 is very effective. A fluid throttle valve 606 is used to adjust the pressure detection means 607 that detects the pressure inside the container 601 to a desired rate of change in the pressure inside the container 601 with respect to time.
A pressure signal 6 is provided from a pressure detection means 607, and a pressure command means 608 is provided to command the constriction to be gradually reduced under optimal conditions.
09 and the pressure command signal 610 from the pressure command means 608 is extracted.

This pressure deviation signal 611 is converted into a speed command signal 613 via a preamplifier 612, further amplified by a motor drive manual 14, and driven to drive a motor 615 directly connected to the throttle of the fluid throttle valve 606. is gradually reduced at an optimized speed, and predetermined exhaust characteristics can be obtained with high precision.

As described above, the fluid throttling means for gradually reducing the flow path resistance over time is performed by means of a throttling valve driving means that opens the throttle valve at a required speed, but in addition to this, the following means are also effective. As shown in Figure 7, this includes multiple exhaust valves,
705a, 705b...705n These exhaust opening/closing valves 705a, 705b...
Different fluid throttles P) 706a, 706b, 706n, which are connected in series to each of 705n, are connected in parallel, from the fluid throttle with a large flow path resistance to the fluid throttle 9 with a large flow path resistance. The on-off valve operating means 704 sequentially opens the exhaust on-off valves connected thereto, thereby gradually reducing the flow path resistance of the fluid restriction system as a whole over time. It can be kept constant.

Effects of the Invention As described above, the vacuum device of the present invention connects a vacuum pump to the vacuum container via a fluid restricting means and an exhaust opening/closing valve arranged in series when evacuating a vacuum container to a vacuum state. The resistance of the flow path in the air means is gradually reduced over time to keep the rate of change in pressure over time almost constant, which prevents dust from flying up due to the flow of Inukihiko gas at the beginning of exhaust, and prevents dust from flying up onto the object to be evaporated. Not only is pollution eliminated, but the exhaust time required to reach the target pressure is also greatly shortened, and its industrial value is extremely large.

[Brief explanation of drawings]

Fig. 1 is a principle diagram of a conventional vacuum device, Fig. 2 is a characteristic diagram showing the relationship between the internal pressure of the container and the evacuation time when the pumping speed is kept constant in the same device, and Fig. 3 is an example of an embodiment of the present invention. FIG. 4 is a characteristic diagram showing the relationship between the flow path resistance of the throttle valve and time in the vacuum device in the example, and FIG. FIG. 6 is a block diagram showing a more specific embodiment of the present invention, and FIG. 7 is a block diagram showing a similar embodiment. 301.601.701-- Container, 303,
603゜703...Vacuum pump, 306.60
6,70θa. TO6b~70e)n------Fluid throttle valve, 305
．． 605°706a, 705b ~705n...
...Exhaust opening/closing valve, 307... Throttle valve driving means,
704...Exhaust opening/closing valve operation means. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 Open when exhausting (5eO) Figure 3 Figure 4 Time □L Figure 5 Open when exhaust L Figure 6 Figure 7

Claims (1)

[Claims] (1) Container type, comprising an evacuation means for evacuating the inside of the container, and the evacuation means is connected to an evacuation pump, and the evacuation pump is inserted into the container to reduce the flow path resistance. A vacuum device comprising a fluid throttling means that gradually decreases over time, and an exhaust opening/closing valve connected in series to the fluid throttling means. (b)) The vacuum device according to claim 1, wherein the fluid restriction means is constituted by a variable restriction valve and a restriction valve driving means for opening the restriction valve of the variable restriction valve at a required speed. 3) The throttle valve driving means is controlled by a pressure detection means for detecting the pressure inside the container, a pressure command means for instructing the pressure inside the container to gradually decrease at a required speed, and a pressure signal from the pressure detection means. 3. The vacuum apparatus according to claim 2, further comprising a throttle valve control means for driving said throttle valve so that the deviation of the pressure command signal from said pressure command means is zero. (4) The fluid control means includes a plurality of exhaust on-off valves, a fluid restriction system connected in series with each of the plurality of exhaust on-off valves and having different flow path resistances, and a fluid restriction system with a large flow path resistance. The vacuum device according to claim 1, wherein the vacuum device is configured by means for operating the on-off valves to sequentially open the on-off valves connected to the fluid restrictor having small flow path resistance, starting with the on-off valves connected to the flow path resistance.