JPH057764A - Exhaust method - Google Patents

Abstract

PURPOSE:To rapidly discharge the residual gas component in piping by holding a gas adhering surface to a state heated to gas non-adsorbing critical Lamp. or higher and intermittently supplying purge gas during the continuation of evacuation. CONSTITUTION:A cylindrical resistance type heater 2 is provided to the periphery of a heat-resistant vertical reaction container 1 and a uniform heating region is formed at the arranging position of the object to be heat-treated in a reaction container 1 by the heater 2. At first, a current is allowed to flow to the heater 2 and the object to be heat-treated in the reaction container 1 is set to the uniform heating region and the reaction container 1 is subsequently evacuated so as to reach a predetermined vacuum degree. Next, a valve 10 is opened to supply reaction gas into the reaction container 1 from a supply pipe 7 to form a film and, thereafter, the valve 10 is closed. Further, purge gas is supplied into the reaction container 1 from a supply source 7a to replace the interior of the supply pipe 7 with the purge gas within the reaction container 1 to again discharge the reaction gas. By this constitution, the component adsorbed on the inner surface of the reaction container 1 or the supply pipe 7 is rapidly discharged as a residual gas component.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust method.

[0002]

2. Description of the Related Art In semiconductor diffusion processing, film formation processing, etching processing and the like using a semiconductor manufacturing apparatus or the like, processing steps are executed using a liquefied gas. A liquefied gas that is liquid at room temperature, such as SiH ₂ Cl ₂ , is discharged from the processing container when the processing is completed, and is replaced with a purge gas such as N ₂ . Such a process is repeated many times to form a semiconductor element.

[0003]

[SUMMARY OF THE INVENTION However, for example when deposited treated with liquefied gas such as SiH ₂ Cl _2, relatively to the low temperature wall surface SiH ₂ Cl ₂ gas is liquefied deposition. In particular, there is a large amount of adhesion to low temperature parts such as in gas supply pipes and exhaust pipes. The deposits, since the amount of vaporized by increasing temperature increases, SiH ₂ Cl ₂ gas deposition process after the end of the evacuation time with the required long, after forming processing object to be processed, the residual SiH ₂ There is an improvement in that one treatment process until the Cl ₂ gas component is discharged becomes long and the throughput is deteriorated. In particular, when vaporized gas such as SiH ₂ Cl ₂ gas is toxic, residual SiH ₂ Cl ₂
Since sufficient exhaustion is required until the exhaust gas becomes less, the exhaust time has an improvement that requires longer time.

The present invention has been made in consideration of the above points, and provides an exhaust method capable of quickly exhausting a residual gas component in a pipe.

[0005]

According to the present invention, when a purge gas is introduced into a pipe of a gas supply pipe for supplying a process gas which is a liquid at room temperature into a process vessel, and the vacuum is exhausted by exhausting the purge gas, A step of maintaining the inner wall of the pipe in contact with the heated state above the process gas non-adsorption critical temperature;
And a step of intermittently supplying a purge gas into the pipe during evacuation.

[0006]

In the present invention, the residual gas component in the pipe can be quickly removed by keeping the gas adhering surface heated to the gas non-adsorption critical temperature or higher and intermittently supplying the purge gas while vacuuming is continued. Can be exhausted.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment in which the apparatus of the present invention is applied to a heat treatment apparatus will be described with reference to the drawings. The heat treatment apparatus is as shown in FIG. 1, that is, a cylindrical resistance heating type heater 2 is provided around a heat-resistant vertical reaction vessel 1 made of, for example, quartz, and is provided in the reaction vessel 1 from this heater 2. Further, the heat-treated body, for example, the semiconductor wafer 6 is arranged so as to form a soaking region at the arrangement position.

A reaction vessel inner pipe 1a is coaxially provided in the reaction vessel 1, and a lid-like support stand 3 is provided at the bottom of the reaction vessel 1. The support stand 3 is configured to be vertically movable by an elevator 3a. ing. This vertical movement is a loading / unloading operation of the semiconductor wafer 6 to / from the heat treatment furnace. That is, FIG.
And the semiconductor wafer 6 is unloaded by moving the support table 3 up and down by the elevator 3a.

A row of semiconductor wafers 6 on the support base 3 is accommodated in a wafer board 5 provided via a heat insulating cylinder 4. A gas supply device is connected in order to perform batch processing on the 6 rows of semiconductor wafers accommodated in the wafer board 5. This gas supply device uses a processing gas, for example, SiH ₂ Cl ₂ gas as a reaction gas and inert N ₂ gas as a purge gas.
Gas supply source 7a to which gas is supplied, and this gas supply source 7a
It is composed of a gas supply pipe 7 that connects a to the reaction container 1. Further, the reaction gas is connected to an exhaust pump 9 via an exhaust pipe 8 in order to form a predetermined flow in the reaction vessel 1, so that the reaction gas is exhausted.

Further, a heating means such as a heater 16 is provided so as to surround the envelope of the low temperature portion of the supply pipe 7, and a temperature control circuit 15 for heating the supply pipe 7 to a desired temperature by the heater 16 is provided. The temperature control circuit 11 is configured so that the temperature control circuit 15 operates according to a signal from the set value 13.

In the heat treatment apparatus thus constructed, for example, the following film forming process is executed. That is, the heater 2
An electric current is passed through to form a soaking region at a film forming temperature of, for example, 800 ° C. in the region where the six rows of semiconductor wafers are provided in the reaction container 1. Then, the inside of the reaction container 1 is evacuated to a predetermined vacuum degree.

Next, the reaction gas is supplied from the reaction gas supply pipe 7 into the reaction container 1 through the valve 10 in an open state.
As the reaction gas at this time, a liquefied gas which is a liquid at room temperature, for example, SiH ₂ Cl ₂ gas is supplied to uniformly form a gas flow on the surface to be processed of each semiconductor wafer 6, and S
An i film is formed. The reaction product gas after this reaction is exhausted from the exhaust pipe 8. After performing this step for a predetermined period, for example, 60 minutes, the reaction gas is supplied by the valve 10
Is closed to stop the film forming process.

Next, purge gas is supplied from the gas supply source 7a. This purge gas is, for example, an inert gas such as N 2.
₂ gas or, for example, H ₂ gas is supplied to the reaction container 1 through the valve 10. By this supply, the inside of the reaction vessel 1 and the inside of the supply pipe 7 are replaced with a purge gas, and then the gas is exhausted again. Even after the purging step of these series of steps, the components adsorbed on the inner surface of the reaction vessel 1 and the inner surface of the supply pipe 7 are generated as a residual release gas with a very low concentration, though slightly. In particular, when unloading a semiconductor wafer, the presence of residual released gas causes workers in a clean room in which clean air is circulated to come into contact with toxic gas, or undesired effects on the semiconductor wafer, generation of dust, etc. There are improvements such as deterioration of film quality.

At this time, the above-mentioned S is formed on the low temperature inner wall surface of the supply pipe 7.
The iH ₂ Cl ₂ gas adheres, and even if the N ₂ purge gas is sufficiently purged after the film forming process, the residual gas is hardly released from the low temperature inner wall surface. In order to prevent this, the wall surface of the entire gas supply device that comes into contact with the reaction gas to which the reaction gas may be attached is heated in advance prior to the treatment. As shown in FIG. 2, this heating temperature was found to have a critical temperature at which SiH ₂ Cl ₂ gas is adsorbed by decreasing the adhering amount when the temperature is raised, and the adhering amount is drastically reduced. It has been found that by setting the temperature above this temperature, the adhesion is prevented or limited to the minimum.

As can be seen from FIG. 2, the amount of SiH ₂ Cl ₂ adsorbed was 600 μg at 40 ° C., but it was 50 μg at 160 ° C., which is a remarkable effect that the amount adsorbed was reduced to 1/10 or less. Further, the amount of adsorption does not change so much even when heated to 160 ° C. or higher, and it is preferable to set the critical temperature of SiH ₂ Cl _{2 to} 160 ° C. or higher at which the gas adsorption is drastically reduced. In addition, it is natural that the other liquefied gases may be set to the optimum critical temperature or higher.

Next, the system for measuring the amount of SiH ₂ Cl ₂ adsorption shown in FIG. 2 will be described with reference to FIG. The pure water supply source 21 is connected to a pump 21a for pumping pure water,
For example, 65 ml / min pressure-fed by this pump 21a
Pure water and, for example, 100 supplied from the gas supply source 7a
The sccm purge gas N ₂ is supplied to the mixing point 22 via the supply pipe 7.
Mixed in. The mixed purge gas N ₂ and pure water are contained in the purge gas N ₂ while being passed through a pipe 23 having an inner diameter of 5 mm and a length of 5 m, which is a minute amount to be measured. Detection gas component, eg SiH ₂
Most of Cl ₂ is dissolved in pure water.

The pure gas in which the purge gas N ₂ and minute gas components to be measured are dissolved is pressure-fed to the separator 24, and the purge gas N ₂ is discharged into the atmosphere from the open upper end of the separator. The pure water containing the gas component to be measured is separated by the separator 2
4 is supplied to the pump 25 through the pipe 24a, and is pumped to the detector 26 at a rate of 40 ml / min by the pump 25, for example. The detector 26 is for detecting the ion concentration in the liquid, for example chlorides meter (Orion Corporation) by an object to be detected such as chlorine ions (C1 ^-) amount detecting the outputs electric signals in and, C1 ^- is output as an electric signal by detecting the variation of the interelectrode current generated by the arrival of ^- C1 by selective electrode.

The output signal of the detector 26 is calculated by the arithmetic unit 27.
The arithmetic unit 27 is configured to perform a predetermined arithmetic operation and a predetermined arithmetic operation, and output the absolute value of the measured gas component dissolved in pure water. The amount of deionized water supplied to the separator 24 by the pump 21a and the amount of deionized water discharged from the pump 25 are overflowed from the separator 24 and flow into the container 24b.
And is discharged from a discharge part 24c provided at the bottom of the container 24b. Further, the pure water after being supplied to the detector 26 and detecting a predetermined amount of ions is discharged into the discharge pipe 2.
It is discharged from 6a. As described above, the gas detection device 20 is configured, and as shown in FIG. 2, it is possible to measure the relationship between the heating temperature of the supply pipe 7 and the SiH ₂ Cl ₂ adsorption amount.

The chemical reaction in the gas detecting step is considered to be due to the following steps. That is, when the purge gas N ₂ + SiH ₂ Cl ₂ gas from the supply pipe 4 and pure water H ₂ O are mixed and dissolved, a reaction of N ₂ + SiH ₂ Cl ₂ + H ₂ O results.
As a result of this reaction, a component according to the following chemical formula 1 is generated, and the ion amount is detected by the sensor 26 with respect to 2Cl ⁻ of the charged particles in the following chemical formula 2 after separating the purge gas N ₂ gas by the separator 24. To do.

[0020]

[Chemical 1]

[0021]

[Chemical 2]

In this way, it is possible to detect how much undesired gas is present in the purge gas shown in FIG. This detection is performed in this embodiment by using the liquefied gas SiH ₂ C.
It is considered that when the l ₂ gas is adsorbed to the low temperature part and heated to a high temperature, it becomes vaporized gas and is detected as the amount of ions by the sensor 26 as described above.

Therefore, by preventing the adsorption of the processing gas to the inner wall surface of the supply device for supplying the processing gas, it is possible to prevent the generation of fine particles and various troubles caused by the supply device. It significantly contributes to the improvement of yield in the process. Even when there is no detector for low-concentration gas as described above, detection can be made possible by dissolving the gas in a solvent and detecting the gas.

Furthermore, in the above embodiment, the example of pure water was explained as the solvent, but any solvent may be used, for example alcohol. Furthermore, in the reaction system of the heat treatment apparatus, it is effective for use in detecting corrosive gas. For example, residual gas of ClF ₃ may be dissolved in pure water to detect fluorine ion. Such gas detection also has an effect that it can be detected in real time.

That is, the purge gas supplied from the supply pipe 7,
For example, the amount of SiH ₂ Cl ₂ gas in N ₂ gas is detected, the detected value is compared with a preset set value 13, and if it is within the set value range, the current temperature is maintained, and if it is out of the range. For example, the temperature control circuit 15 controls the temperature so that it falls within the set value range. Of course, the temperature of the heater of the supply pipe 7 may be detected and controlled so that the temperature of the supply pipe 7 is maintained above the non-adhesion critical temperature of the processing gas.

The exhaust process after this process will be described below. FIG. 2 shows the purging method in the gas supply pipe and the residual gas with respect to the inner wall temperature of the container. As is clear from FIG. 2, the residual gas decreases when the heating temperature by the heater is high, and the residual gas decreases when the purge gas is supplied more than once and intermittently. There is. As shown in FIG. 2, it is desirable that the heating temperature of the heater is not lower than the non-adhesion critical temperature of the reaction gas.

In the purging method of FIG. 4, evacuation is always continued. The display of V shows only the period of vacuuming, and the display of N ₂ shows that N ₂ gas is introduced while the vacuuming is continued.

In order to quickly remove the reaction gas after the treatment, a purge gas (for example, N ₂ gas) is intermittently introduced into the reaction tube 1 while vacuuming is continued, and the purge gas is discharged together with the residual gas by the vacuum pump 9. To do. Furthermore, the low temperature wall surface of the gas flow path is heated and maintained above the non-adhesion critical temperature of the reaction gas. By repeating such a process, the gas remaining in the gas supply device can be quickly discharged. By performing the above process several times, the gas can be discharged more quickly.

No. 1 in FIG. In the example of No. 1, when the vacuum is evacuated at a temperature of 40 ° C. for a certain period of time, for example, 50 minutes, the residual amount of the reaction gas is 1400 μg, whereas No. In the example of No. 4, the temperature is set to 160 ° C. for 10 minutes and the N
_{When two} gases are introduced alternately for 10 minutes for a total of 50 minutes,
The residual amount of the reaction gas could be reduced to 200 μg. Although the example of the gas supply device of the heat treatment apparatus has been described in the above embodiment, it is natural that this technique can be applied to the exhaust pipe as well. Further, the present invention can be applied not only to the heat treatment apparatus but also to processing apparatuses such as an etching apparatus, a CVD apparatus and a sputtering apparatus. As the gas adhering to the inner wall surface of the pipe, there are corrosive gases such as HBr gas and ClF _{3 in} addition to SiH ₂ Cl ₂ gas.

[0030]

As described above, according to the method of the present invention, the residual gas component in the pipe to which the processing gas adheres can be quickly exhausted.

[Brief description of drawings]

FIG. 1 is an explanatory view of a heat treatment apparatus for explaining an embodiment of a method of the present invention.

FIG. 2 is a diagram showing the relationship between the amount of SiH ₂ Cl ₂ adsorbed in the container and the heating temperature.

FIG. 3 is a configuration diagram for explaining the gas detection device of FIG. 1 in detail.

FIG. 4 is a diagram showing the relationship between various purging methods and the inner wall temperature of the container, and the residual amount of reaction gas after purging.

[Explanation of symbols]

 1 Reaction Pipe 7 Supply Pipe 7a Gas Supply Source 11 Temperature Control Section 16 Heater 21 Pure Water Supply Source 22 Mixing Point 23 Piping 24 Separator 26 Detector

Claims (1)

Claim: What is claimed is: 1. A purge gas is introduced into a gas supply pipe for supplying a process gas that is a liquid at room temperature into a process container, and the purge gas is brought into contact with the purge gas flow when the gas is evacuated and exhausted. An exhaust method comprising: a step of maintaining an inner wall of the pipe in a heated state at a non-adsorption critical temperature of a processing gas or higher; and a step of intermittently supplying a purge gas into the pipe during vacuum evacuation. ..