JP5648204B2 - Safety device for ozone gas delivery system - Google Patents

Description

  The present invention relates to a safety device in an ozone gas supply system used in the semiconductor manufacturing field, and more particularly to a safety device in an ozone gas supply system that supplies ozone gas having an ozone concentration higher than 20 vol%.

Since ozone gas has a high oxidizing power, the same oxide film formation rate can be obtained even when the temperature of the silicon substrate is lower than the temperature during the oxidation treatment using oxygen gas during the oxidation treatment of the silicon substrate surface. Further, if the concentration of ozone gas is increased, the reactivity is improved and the oxidation treatment time can be shortened. Therefore, a high concentration ozone gas generator has been developed (Patent Document 1). A continuous supply ozone gas generator for generating a large amount of high concentration ozone gas has also been developed (Patent Document 2).
Japanese Patent No. 3825854 JP 11-335102 A

  However, if there is a reactive part in the gas contact part with the ozone gas such as the inner wall of the piping and various containers that make up the ozone gas supply system, the ozone decomposes there and becomes oxygen. There is a problem that the ozone concentration supplied to the vicinity of the surface or the like decreases.

  In addition, in order to remove particulates in the gas, if a fine gas filter or a valve with a complicated flow path is arranged in the ozone gas supply system, the presence of these gas filter and valve tends to cause an ozonolysis chain, In some cases, there is a problem of heat damage. This is because once the ozonolysis begins, the temperature of the filter and the like rises due to the heat generated during the ozonolysis, and further a chain mechanism occurs in which ozone begins to thermally decompose.

  When the flow rate of ozone gas is increased, the chain reaction of the generation of decomposition heat is likely to proceed rapidly, and the generated decomposition heat is also increased. Therefore, if the chain mechanism continues, there is a concern that the filter and the valve may be damaged by heat.

  In particular, when the ozone concentration exceeds 20 vol%, ozone decomposition easily propagates, and therefore ozone decomposition may propagate toward the ozone generator in the ozone supply path.

The present invention has been proposed in view of the above points. When the decomposition of ozone gas begins in the ozone gas supply system, the gas flow rate can be limited without detecting it and interrupting the ozone gas supply. For the purpose.

In order to achieve the above-mentioned object, the present invention as set forth in claim 1 is directed to an ozone gas supply system for supplying ozone gas generated by an ozone gas generator to an ozone gas utilization device. the abnormal variation of the pressure at the ozone gas utilizing apparatus-side detected by the sensor, enter the detection signal from the sensor abnormality determining device, a flow of ozone gas through the ozone gas supply passage on the basis of the abnormal state determination in the abnormality determining device It is characterized by being configured to limit the gas flow rate without interruption .

  The present invention described in claim 2 is characterized in that a gas filter is disposed on the ozone gas utilization device side in the ozone gas supply path, and a detection sensor is disposed in the vicinity of the portion where the gas filter is disposed.

  The present invention described in claim 3 is characterized in that, in the invention described in claim 1 or 2, the ozone gas supplied to the ozone gas utilization device is a high-concentration ozone gas having an ozone gas concentration of 20 vol% or more.

In the present invention, a sensor detects an abnormal variation in pressure on the ozone gas utilization device side of ozone gas flowing through an ozone gas supply path, and a detection signal from the sensor is input to the abnormality determination device. Based on the abnormal condition judgment, it is configured to limit the gas flow rate without interrupting the flow of ozone gas flowing through the ozone gas supply path, so the pressure and gas temperature of the ozone-oxygen mixed gas in the ozone gas supply path are constantly monitored It becomes possible to do.

For this reason, when heat is generated in the gas filter arranged on the ozone gas utilization device side of the ozone gas supply system and decomposition of the ozone gas starts in the gas filter part, the pressure of the ozone-oxygen mixed gas flowing through the ozone gas supply path fluctuates or Although the temperature rises, this pressure change signal is detected by a sensor and input to the abnormality determination device. When the occurrence of an abnormal decomposition state is detected, the shutoff valve is operated to close the valve and the flow of ozone gas is interrupted. Thus, the gas flow rate is limited without restricting the ozone gas decomposition from propagating to the ozone gas supply device side while continuing the supply of the ozone gas to the ozone gas utilization device .

FIG. 1 shows an implementation apparatus of the present invention, and FIG. 1 is a schematic configuration diagram showing a basic configuration of an ozone gas use facility.
This ozone gas use facility communicates an ozone gas generator (1) composed of an ozonizer, adsorption-type ozone concentrator, etc. with an ozone gas utilization device (2) such as an oxide film generator for a semiconductor substrate through an ozone gas supply pipe (3). Connect the gas flow regulator (4) and the first shutoff valve (5) to the ozone gas generator side of the ozone gas supply pipe (3), and the second shutoff valve (6) to the ozone gas utilization device (2). A sensor (7) and a gas filter (8) are arranged in order from the upstream side in the ozone distribution direction, and the detection signal from the sensor (7) arranged in the ozone gas supply pipe (3) is input to input the ozone gas supply pipe (3 ) Is provided with an abnormality determination device (9) that monitors the state of ozone gas, and this abnormality determination is based on physical changes in pressure and temperature in the ozone gas supply pipe (3) detected by the sensor (7). Device (9) is ozone gas supply distribution When it is detected that abnormal decomposition has occurred in the pipe (3), the first shut-off valve (5) is actuated to the closed side to prevent the abnormal decomposition from chain-propagating to the ozone gas generator (1) side. I have to do it.

  As the sensor (7) disposed in the ozone gas supply pipe (3), a diaphragm type pressure sensor capable of measuring the pressure regardless of the gas concentration or component, or a temperature sensor for detecting the temperature of the gas flow path is used. be able to. Further, the location where the sensor (7) is disposed is preferably close to a location where ozone decomposition is likely to occur, such as the gas filter (8) or the second shutoff valve (6), because it is sensitive to ozone decomposition. Furthermore, in the above-described embodiment, the sensor (7) is disposed between the second shut-off valve (6) and the gas filter (8), but the sensor (7) may be located downstream of the gas filter (8). Good.

  The ozone gas flowing through the ozone gas supply pipe (3) is an ozone-oxygen mixed gas, and a high-concentration ozone gas having an ozone gas concentration of 20 vol% or more is effective. The higher the ozone concentration, the higher the detection sensitivity and the easier to apply. The pressure range of ozone gas is preferably 100 Pa to 1 MPa. In addition to the oxygen described above, an inert gas such as argon, helium, krypton, or xenon may be included as a component contained in the ozone gas.

  FIG. 2 shows a case where an oxidation furnace is used as the ozone gas utilization device (2). In this oxidation furnace, the inside of the oxidation furnace main body (11) is vertically divided by a quartz partition wall (12), a silicon substrate (13) is placed on the upper surface of the quartz partition wall (12), and the quartz partition wall (12) A heater (14) is disposed on the lower side, and the surface of the substrate is oxidized with a gas containing ozone while the silicon substrate (13) is heated.

When the ozone gas utilization device (2) is configured in this way, if the ozone decomposition begins to proceed rapidly for some reason in the oxidation furnace, the pressure in the furnace rises rapidly, and the ozone gas supply pipe (3) accordingly. Since the internal pressure also rises, the sensor (7) detects the pressure rise and outputs the signal, and the abnormality determination device (9) outputs the pressure signal value input from the sensor (7) in a steady state. The occurrence of abnormality is detected based on the amount of deviation from the detected pressure value, and the first shut-off valve (5) is operated to the valve closing side .

FIG. 3 shows a case where an oxidation furnace of a type that irradiates ozone gas near the substrate surface with ultraviolet rays is used as the ozone gas utilization device (2).
In this oxidation furnace, the inside of the oxidation furnace main body (11) is vertically divided by a quartz partition wall (12), a silicon substrate (13) is placed on the upper surface of the quartz partition wall (12), and the quartz partition wall (12) A heater (14) is placed on the lower side, a quartz window (15) is placed on the upper surface of the oxidation furnace body (11), and an ultraviolet light source (16) that irradiates ultraviolet rays through the quartz window (15) is placed. When the substrate surface is oxidized with a gas containing ozone while the silicon substrate (12) is heated, when the substrate temperature is low and ozone is not easily decomposed by the heat of the substrate surface temperature, an ultraviolet ray having a wavelength of around 250 nm is used. Is used to improve the oxidation rate of the substrate by photolysis of ozone.

In the case of this device, when the ultraviolet light source (16) breaks down and photolysis stops, the pressure in the furnace decreases, and the pressure in the ozone gas supply pipe (3) also decreases accordingly. The abnormality detection device (9) detects the occurrence of the abnormality by the amount of deviation from the detected pressure value in the steady state of the pressure signal value input from the sensor (7). Then, the first shut-off valve (5) is operated to the valve closing side.

  In the embodiment shown in FIG. 1 to FIG. 3, the gas flow regulator (4) for adjusting the supply flow rate of ozone gas sent from the ozone gas generator (1) to the ozone gas supply pipe (3) to be constant is supplied with ozone gas. Although arranged on the ozone gas generator (1) side of the pipe (3), the gas flow rate regulator (4) may be mounted inside the ozone gas generator (1).

  FIG. 4 shows the basic configuration of an ozone gas use facility showing a further different embodiment. This is the use of the ozone gas use facility shown in FIG. 1 that can control the gas supply pressure as the ozone gas generator (1). Therefore, the gas flow regulator is omitted. When an ozone gas generator (1) that can control the gas supply pressure is used, the gas supply flow rate can be substantially controlled by the gas pressure control.

Even in the ozone gas use facility shown in FIG. 4, there are pressure abnormalities such as ozone decomposition due to the presence of valves, gas filters, etc., pressure increase due to ozone decomposition in the ozone utilization device (2), or pressure decrease due to insufficient ozone decomposition. When it occurs, the output signal from the sensor that detects the pressure state is determined by the pressure abnormality determination device (9), and when it is determined as an abnormal state, the shut-off valve is operated in the closing direction, so that FIG. -It can cope with abnormality like what was disclosed in FIG.

  In each of the above embodiments, the abnormality determination device (9) has been described as being installed separately from the ozone gas generation device (1) and the ozone gas utilization device (2). However, the abnormality determination device (9) is replaced with the ozone gas generation device (1). ) Or as a part of the gas filter (8).

  Moreover, although each said embodiment demonstrated what installed the gas filter (8) in the ozone gas supply piping (3), the gas filter (8) may be installed in the ozone utilization apparatus (2). . The filter element of the gas filter (8) can be made of ceramic, metal, or fluororesin, and the particle size filtered by the filter element is preferably small, and is 0.01 μm or less. Is preferred.

  FIG. 5 shows changes over time in the temperature of the gas filter and the amount of ozone flowing when ozone is decomposed in the gas filter (8) to generate heat in the apparatus shown in FIG. When the ozone gas flowed down to a 150 cc oxidation furnace per minute, the filter gradually generated heat. The ozone gas flow rate was reduced to 100 cc / min at the stage of 97 minutes after the start of ozone supply. Although the temperature rise subsided, the temperature began to rise rapidly again around 110 minutes after the start of ozone supply.

  When there is no abnormality determination device (9), the flow rate is not controlled as shown by the line (a), so the temperature rises rapidly. On the other hand, when the shutoff valve is completely closed as shown by the line (c) and the ozone gas flow rate is made zero, heat generation stops immediately, but ozone supply to the oxidation furnace also stops. Therefore, when the abnormality determination device (9) detects an abnormal state, the state when the abnormality determination device (9) controls the flow rate is indicated by a line (b). The temperature change curve after 110 minutes after the start of ozone supply shows a state in which the flow rate control is performed, and the temperature rise shows a tendency to gradually decrease.

  The present invention can be widely used in an ozone gas supply system that supplies ozone gas.

It is a schematic block diagram which shows the basic composition of ozone gas usage equipment. It is a schematic block diagram in case the ozone gas utilization apparatus of an ozone gas use equipment is an oxidation furnace. It is a schematic block diagram in case the ozone gas utilization apparatus of an ozone gas use equipment is an oxidation furnace of a different type. It is a schematic block diagram which shows the basic composition of a different type of ozone gas usage equipment. It is a figure which shows the time-dependent change of the temperature of a gas filter at the time of ozone decomposition | disassembly heat_generation | fever, and ozone flow amount.

  DESCRIPTION OF SYMBOLS 1 ... Ozone gas generator, 2 ... Ozone gas utilization apparatus, 3 ... Ozone supply path, 5 ... Shut-off valve, 7 ... Sensor, 8 ... Gas filter, 9 ... Abnormality determination apparatus.

Claims (3)

The ozone gas generator (1) and the ozone gas utilization device (2) are connected by the ozone supply path (3), and the ozone gas generated by the ozone gas generation device (1) is sent to the ozone gas utilization device (2). In the supply system,
The sensor (7) detects abnormal fluctuations in the pressure of the ozone gas flowing through the ozone gas supply path (3) on the ozone gas utilization device (2) side, and the detection signal from this sensor (7) is sent to the abnormality determination device (9). Safety in the ozone gas supply system configured to limit the gas flow rate without interrupting the flow of ozone gas flowing through the ozone gas supply path (3) based on the abnormal state determination by the abnormality determination device (9) apparatus.   The gas filter (8) is disposed on the ozone gas supply device (2) side in the ozone gas supply path (3), and a sensor (7) is disposed in the vicinity of the portion where the gas filter (8) is disposed. Safety device in the ozone gas delivery system described.   The safety device in the ozone gas supply system according to claim 1 or 2, wherein the ozone gas supplied to the ozone gas utilization device (2) is a high concentration ozone gas having an ozone gas concentration of 20 vol% or more.

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