JP2009231332A - Cleaning gas supply device and semiconductor processing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cleaning gas supply device which uses a cleaning gas produced by thermally dissolving dichloroethylene or allowing dichloroethylene and oxygen to be reacted with each other and cleans metallic contamination in the inside of a processing pipe of a semiconductor processing apparatus so that carbon or water may not be introduced into the processing pipe. <P>SOLUTION: The cleaning gas supply device includes: a container 10 to store dichloroethylene; a dichloroethylene reaction section 20 to prepare a cleaning gas by allowing dichloroethylene and oxygen to be reacted with each other or thermally dissolving dichloroethylene; a carrier gas introduction passage 30 connected with the container 10 so as to produce bubbling of a carrier gas in the container; a mixed gas supply passage 40 to supply a mixed gas to the dichloroethylene reaction section 20 from the container 10; an oxygen supply passage 50 to supply oxygen to the dichloroethylene reaction section 20; and a cleaning gas supply passage 60 to supply a cleaning gas to the processing pipe from the dichloroethylene reaction section 20. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a cleaning gas supply device for supplying a cleaning gas for cleaning the inside of a processing tube of a semiconductor processing device provided with a processing tube for heat treating a semiconductor wafer, a semiconductor processing device including the same, and a cleaning method About.

  When manufacturing semiconductor devices such as ICs (integrated circuits), processing involving high-temperature heating, such as oxide film formation, annealing, metal thin film formation, and metal atom implantation, is performed on semiconductor wafers in high-temperature processing tubes. Has been done. In such treatment, the inner wall of the treatment tube and structures such as susceptors and boats placed in the treatment tube are contaminated with alkali metals such as sodium and potassium, and heavy metals such as iron, cobalt and chromium. These metal atoms are taken into the semiconductor wafer, and the performance of the semiconductor device is degraded.

  For this reason, it is performed to replace a metal-contaminated processing tube, susceptor, or the like with a clean one. In addition, structures such as the removed processing pipe and exhaust pipe, and the taken out boat are reused after sufficiently washed with a cleaning liquid. However, when such replacement work or cleaning work is performed, there is a risk that they are once cleaned and then recontaminated with metal again. On the other hand, since these operations require an enormous amount of time, the downtime of the semiconductor processing apparatus is lengthened, and it is inevitable that the processing efficiency of the semiconductor wafer is greatly reduced.

Therefore, a daily maintenance method for purifying metal contamination inside the processing tube without replacing the processing tube is desired, and one method is to heat it to a high temperature (usually 1000 ° C or higher). Oxygen in a ratio of 2 moles per mole of dichloroethylene is introduced into the treated tube and reacted with each other in the treated tube to generate HCl gas (C ₂ H ₂ Cl ₂ + 2O ₂ → 2HCl + 2CO ₂ ). It has been proposed to chlorinate contaminated metals with HCl gas and volatilize them as metal chlorides to remove the exhaust (Patent Document 1).

JP 2004-104029 A

  However, when dichloroethylene and oxygen are directly introduced into the processing tube as in Patent Document 1, the specific gravity of dichloroethylene is about three times as large as that of oxygen, so the dichloroethylene concentration in the lower space inside the processing tube is high. As a result, a region where the ratio of oxygen to dichloroethylene is locally low or a region where the oxygen ratio is excessively large is generated.

In the former region where the proportion of oxygen is excessively small relative to dichloroethylene, carbon is generated by the thermal decomposition reaction of dichloroethylene (C ₂ H ₂ Cl ₂ → 2HCl + 2C) and adheres to the inner wall of the processing tube. There is a risk of causing carbon contamination that greatly reduces the yield.

On the other hand, in a region where the ratio of oxygen to dichloroethylene is excessive, hydrogen chloride is generated as a cleaning gas species at a relatively low temperature (about 500 ° C.), but at a relatively high temperature (about 900 ° C.) Instead, chlorine is generated (C ₂ H ₂ Cl ₂ + 5/2 · O ₂ → H ₂ O + 2CO ₂ + Cl ₂ ), and metal contamination is cleaned by chlorine gas, but water is generated. Naturally, it is assumed that the amount of water present at the location differs depending on the location. This becomes a problem when a semiconductor wafer is processed at a high temperature exceeding 1200 ° C. That is, when processing a semiconductor wafer at a high temperature exceeding 1200 ° C., silicon carbide, which has higher heat resistance than quartz, is used for structures such as processing tubes, susceptors, and boats. There is a problem that the surface of the silicon carbide is changed to a silicon dioxide film by wet oxidation due to the water generated in the region where the ratio is excessive. Further, as described above, the amount of water present inside the processing tube varies depending on the location. For this reason, the silicon dioxide film thickness on the surface of silicon carbide differs depending on the location, and the diffusion rate of contaminating metal atoms in silicon carbide and silicon dioxide is higher than that of the former. The level may vary depending on the location. Therefore, when using silicon carbide, it is desired to suppress the amount of water in the processing tube as much as possible.

  An object of the present invention is to solve the above-described problems of the prior art, and a semiconductor processing apparatus using a clean gas obtained by thermally decomposing dichloroethylene or reacting dichloroethylene and oxygen. It is an object of the present invention to prevent carbon and water that may impede cleaning from being introduced into a processing tube when cleaning metal contamination inside the processing tube.

  Prior to introducing dichloroethylene into the processing tube of the semiconductor processing apparatus, the present inventor prepared a cleaning gas by mixing and reacting with oxygen in advance or by thermally decomposing dichloroethylene to obtain a cleaning gas. As a result, it was found that the above-mentioned object can be achieved by removing components unnecessary for cleaning in the cleaning gas as required, and the present invention has been completed.

That is, the present invention is a cleaning gas supply device for supplying a gas for cleaning the inside of a processing tube of a semiconductor processing apparatus having a processing tube capable of processing a semiconductor wafer at a high temperature,
A container containing dichloroethylene;
A dichloroethylene reaction section for preparing a cleaning gas by reacting dichloroethylene with oxygen or thermally decomposing dichloroethylene;
A carrier gas introduction path connected to the container so that bubbling of the carrier gas occurs in dichloroethylene in the container;
A mixed gas supply path for supplying a mixed gas of carrier gas and dichloroethylene from the container to the dichloroethylene reaction section;
An oxygen supply path for supplying oxygen to the dichloroethylene reaction section as required;
A cleaning gas supply device having a cleaning gas supply path for supplying a cleaning gas from the dichloroethylene reaction section to the processing tube is provided. In particular, a cleaning gas supply device is provided in which a trap portion for removing components unnecessary for cleaning in the cleaning gas is provided in the cleaning gas supply path.

  The present invention also relates to a semiconductor processing apparatus having a processing tube capable of processing a semiconductor wafer at a high temperature, a plurality of process gas supply passages connected to the processing tube, and an exhaust gas passage connected to the processing tube. There is provided a semiconductor processing apparatus having the above-described cleaning gas supply apparatus, the cleaning gas supply path of which is connected to at least one of the plurality of process gas supply paths or directly connected to a processing tube. This semiconductor processing apparatus can also be applied to a case where a structure in which at least a part is formed from silicon carbide exists inside the processing tube.

Furthermore, the present invention is a cleaning method for cleaning the inside of a processing tube of a semiconductor processing apparatus having a processing tube capable of processing a semiconductor wafer at a high temperature,
Provided is a cleaning method for obtaining a cleaning gas by reacting dichloroethylene with oxygen or thermally decomposing dichloroethylene, and introducing the obtained cleaning gas into the processing tube heated to a cleaning temperature. This method is particularly applicable to a cleaning method in which a cleaning gas purified by removing components unnecessary for cleaning in the acquired cleaning gas is introduced into the processing tube heated to the cleaning temperature.

  According to the present invention, before introducing dichloroethylene into the processing tube, the dichloroethylene is previously thermally decomposed or reacted with dichloroethylene and oxygen to prepare a cleaning gas, and the resulting cleaning gas is introduced into the processing tube. Because it is guided to the processing tube after removing unnecessary components in the cleaning gas as necessary, avoid mixing carbon and water into the processing tube of the semiconductor processing equipment. Can do.

  First, a cleaning gas supply device of the present invention for supplying a gas for cleaning the inside of a processing tube of a semiconductor processing apparatus having a processing tube capable of processing a semiconductor wafer at a high temperature will be described with reference to the drawings. To do.

As shown in FIG. 1, the cleaning gas supply apparatus 100 of the present invention includes:
A container 10 containing dichloroethylene (mainly transdichloroethylene, sometimes abbreviated as DCE);
A DCE reaction unit 20 for preparing a cleaning gas by reacting DCE and oxygen or thermally decomposing DCE;
A carrier gas introduction path 30 connected to the container portion 10 so as to bubble a carrier gas selected from an inert gas such as argon or nitrogen in the DCE in the container 10;
A mixed gas supply path 40 for supplying a mixed gas of carrier gas and DCE from the container 10 to the DCE reaction unit 20;
An oxygen supply path 50 for supplying oxygen to the DCE reaction unit as required;
A cleaning gas supply path 60 for supplying a cleaning gas from the DCE reaction unit 20 to the processing tube to be cleaned is provided. Further, the cleaning gas supply path 60 is provided with a trap portion 70 for removing components unnecessary for cleaning in the cleaning gas, that is, carbon and water.

  The container 10 is preferably made of quartz in order to prevent metal contamination. Moreover, the container 10 is stored in the thermostat 11 in order to keep the temperature of DCE constant. As the thermostat 11, a known thermostat can be used. The temperature chamber 11 is preferably temperature controlled with an accuracy of ± 0.5 ° C. based on temperature data from a temperature monitor 12 attached to the container 10.

  The carrier gas introduction path 30 can usually be composed of a stainless steel tube, a quartz tube, a Teflon (registered trademark) lining glass tube, or the like. Further, it is preferable to have a known mass flow meter (hereinafter sometimes referred to as MFC) 31 for controlling the flow rate of the carrier gas and a valve 32.

The relationship of the vapor pressure P (mmHg) to the DCE temperature T (° C.) is expressed by the following equation between 0 to 50 ° C.

Therefore, the amount of DCE per unit time to be used for cleaning can be determined from the temperature and the flow rate of the carrier gas. When the temperature of the thermostatic chamber 11 changes, the carrier gas MFC 31 in accordance with the above relational expression The flow rate may be controlled by a microcomputer. For example, when argon is used as the carrier gas and the temperature of the thermostatic chamber 11 is 20 ° C. and bubbling at 10 to 300 cc / min, the amount of DCE used for cleaning is 15 to 448 mg / min (in other words, 1.5 × 10 ^{− 4 to} 4.6 × 10 ⁻³ mol / min).

  The mixed gas supply path 40 can usually be composed of a stainless steel tube, a quartz tube, a Teflon (registered trademark) lining glass tube, or the like. Moreover, it is preferable to have a known valve 41.

  The oxygen supply path 50 can usually be composed of a stainless steel tube, a quartz tube, a Teflon (registered trademark) lining glass tube, or the like. Moreover, it is preferable to have a known mass flow meter (hereinafter sometimes referred to as MFC) 51 for controlling the flow rate of oxygen and a valve 52. In principle, the supply of oxygen is unnecessary when pyrolyzing DCE. In that case, the valve 52 may be closed.

  In FIG. 1, the oxygen supply path 50 is connected to the mixed gas supply path 40, but may be directly connected to the DCE reaction tube 20.

As described above, when the carrier gas was bubbled at 10 to 300 cc / min (in other words, the DCE amount was 15 to 448 mg / min (1.5 × 10 ^{−4 to} 4.6 × 10 ⁻³ mol / min Min)) when mixed with oxygen gas 50-400 cc / min (2.25 × 10 ⁻³ to 18 × 10 ⁻³ mol / min), the molar ratio of oxygen to DCE [oxygen / DCE] α is calculated Above, it can be varied in the numerical range of about 0.5-120.

  The DCE reaction unit 20 is preferably composed of a quartz tube and is heated to 400 to 900 ° C. by the heater 21. Further, it is preferable to increase the cross-sectional area of the flow path in order to surely cause the reaction between DCE and oxygen gas, or to fold the flow path and extend the flow path length as shown in FIG.

  Here, in terms of stoichiometry, when only HCl is generated as a gas species, α = 0 is used for thermal decomposition in an oxygen-free state, and when hydrogen chloride and carbon dioxide gas are generated, 0 <α ≦ 2. When generating hydrogen chloride and chlorine, it is desirable that 2 <α <2.5, and when generating mainly chlorine, 2.5 ≦ α.

Actually, when the DCE reaction unit 20 is heated to 350 to 450 ° C. and the flow rate of the carrier gas and the oxygen gas is set so that the molar ratio [oxygen / DCE] α is about 2 to 2.2, “C ₂ It is expected that a reaction of “H ₂ Cl ₂ + 2O ₂ → 2HCl + 2CO ₂ ” occurs and a cleaning gas composed of hydrogen chloride, carbon dioxide gas and unreacted oxygen flows out from the DCE reaction unit 20. Further, when the DCE reaction unit 20 is further heated to a high temperature (700 to 950 ° C.) with the molar ratio [oxygen / DCE] α being about _{2 to} 2.2, “C ₂ H ₂ Cl ₂ + 5/2 · O” is obtained. It is expected that chlorine, water, carbon dioxide gas, and free carbon will flow out of the DCE reaction unit 20 because the amount of oxygen that satisfies the reaction formula of “ ₂ → H ₂ O + 2CO ₂ + Cl ₂ ” is insufficient. When the molar ratio α exceeds 3, stoichiometric free carbon is not generated, and a mixed cleaning gas of chlorine, water, carbon dioxide, and unreacted oxygen may flow out from the DCE reaction unit 20. Be expected.

  When using a vertical processing tube that simultaneously processes 100 or more semiconductor wafers, the molar ratio α may be about 10 to 12 in order to avoid a local oxygen deficiency situation.

  The cleaning gas supply path 60 can be generally constituted by a stainless steel tube, a quartz tube, a Teflon (registered trademark) lining glass tube, or the like. The cleaning gas supply path 60 is provided with a valve 61 for exhaust and a valve 62 leading to the processing pipe. The trap unit 70 provided in the cleaning gas supply path 60 is temperature-controlled in order to remove unnecessary components from the cleaning gas flowing out from the DCE reaction unit 20. Although there is no restriction | limiting in particular as the method, Cooling by carrying out adiabatic expansion of a refrigerant | coolant and heating by electrical resistance heating are mentioned. In addition, you may provide the trap bath 72 accommodated in the thermostat 71. FIG. Examples of the trap bath 72 include an ice bath, an oil bath, a liquid nitrogen bath, a dry ice-acetone bath, a hot water bath, and the like. For example, in order to remove water from the cleaning gas, the trap bath 71 is preferably a -79 ° C. dry ice-acetone bath. When removing carbon, it is preferable to use a trap bath of about 20 ° C. or lower, preferably an ice bath of 0 ° C.

  Further, it is preferable that the cleaning gas supply path 60 extends the length of the flow path at the trap portion 70 by folding the flow path as shown in FIG.

  In the cleaning gas supply path 60, as shown in FIG. 2, a bypass path 63 is provided so that the cleaning gas can be introduced into the processing pipe without passing through the trap section 70, and valves 64 to 66 are provided in the bypass path 63. Also good.

  If unnecessary components are excessively accumulated in the trap unit 70, the cleaning gas supply path 60 may be clogged. Therefore, the trap is kept at 100 to 500 ° C. while flowing only oxygen gas or only carrier gas (the target is water). If it is carbon, it heats to 100 degreeC or more, and if it is carbon, 300 degreeC or more, letting oxygen gas flow, and closes valve | bulb 62, On the other hand, by opening valve | bulb 61, the accumulated unnecessary component (water becomes water vapor, carbon By exhausting (as carbon dioxide), the trap function of the trap unit 70 can be recovered.

  The cleaning gas supply apparatus described above is used by being incorporated in a semiconductor processing apparatus. As shown in FIG. 3, a specific semiconductor processing apparatus includes a processing tube 200 capable of processing a semiconductor wafer at a high temperature, a plurality of process gas supply paths 201, 202, and 203) connected to the processing tube 200, and processing. The exhaust gas passage 204 is connected to the pipe 200, and the cleaning gas supply passage 60 of the cleaning gas supply device 100 of the present invention is connected to at least one of the process gas supply passages. Each process gas supply path is provided with an MFC (205 to 207) and a valve (208 to 210), respectively. The processing tube 200 is provided with a heating device 211.

  In FIG. 3, there are three process gas supply paths, but there may be one. In addition, the cleaning gas supply path 60 may be connected to the process gas supply path, but may be directly connected to the processing tube 200.

  The processing tube 200 is made of ordinary quartz or silicon carbide. The inner wall of the processing tube 200 is a cleaning target. In addition, a structure such as a susceptor and a boat housed in the processing tube 200 also becomes the processing object 212. The heating temperature and heating time conditions for cleaning the processing tube 200 include a condition that the temperature and time of the actual process are about 50 ° C. higher than the process temperature and about 10 times the process time. It is done. Preferably, heating is continued at 800 to 1500 ° C., more preferably 1000 to 1400 ° C. for 1 to 24 hours.

  When cleaning the processing tube 200 of such a semiconductor processing apparatus, the cleaning gas supply device reacts DCE with oxygen or thermally decomposes dichloroethylene to acquire the cleaning gas, and the acquired cleaning gas is cleaned. What is necessary is just to introduce | transduce into the processing tube 200 heated to temperature. In this case, if a component unnecessary for cleaning in the acquired cleaning gas is removed, cleaning can be performed with the purified cleaning gas.

An example of a method for evaluating the cleaning result of the processing tube 200 and the workpiece 212 will be described below. First, Ar carrier gas is 10 to 300 cc / min, oxygen gas 50 to 400 cc / min, molar ratio of oxygen to DCE [oxygen / DCE] α = about 0.5 to 120, temperature of DCE reaction unit 20 is 300 to 950 ° C. The cleaning gas acquired under the condition of the temperature of the trap section 70 of about −70 to 0 ° C. is continuously introduced into the processing tube 200 heated to 1350 to 1400 ° C. together with N ₂ process gas 1000 to 2000 cc / min for 5 hours. A cleaning process is performed. Contaminated metal transfer in which a silicon wafer is placed on the workpiece 104 and heated at 1350-1400 ° C. for 1 hour while flowing Ar (1800 cc / min) and oxygen (200 cc / min) after the cleaning process. Process. After performing the contaminated metal transfer process, the wafer surface that has been in contact with the workpiece 212 is exposed to hydrofluoric acid vapor, and the liquefied hydrofluoric acid liquid is recovered, and the contaminated metal species contained in the hydrofluoric acid liquid is ICP- Analysis processing is performed by MS (Inductively Coupled Plasma Mass) analysis. As the analysis target species, it is preferable to analyze all contaminating metal species such as Na, Al, Fe, Cu, Cr, Ni, etc. Among them, Na and the influence of handling are strongly reflected and included in the material In addition, if Fe, which is an impurity that causes a decrease in the performance of the semiconductor, is monitored, it is sufficient for the evaluation of the cleaning result. Therefore, Fe and Na were analyzed. If the detected concentrations of Fe and Na in this analysis process exceed the allowable concentration, the cleaning process, the contaminated metal transfer process, and the analysis process are performed again to detect the concentrations of Fe and Na. This series of processes is performed until the concentration of Fe and Na falls below the allowable concentration. In addition, when a silicon wafer having a diameter of 2 inches is used as a wafer and ICP-MS analysis based on a so-called semiconductor microanalysis method is performed, the detection limit of Fe is 0.5 × 10 ¹⁰ pieces / cm ² , and Na The detection limit is 0.7 × 10 ¹⁰ pieces / cm ² .

  When it can be confirmed that the Fe and Na concentrations are lower than the allowable concentration, the processing tube 200 determines that the cleaning is completed, the cleaning gas from the cleaning gas supply device is stopped, and the processing tube 200 should be processed. A wafer may be loaded and a desired process (annealing process, metal thin film forming process, metal atom implantation process, etc.) may be performed.

  Note that the cleaning gas supply apparatus and the semiconductor manufacturing apparatus including the cleaning gas supply apparatus according to the present invention can be applied not only to cleaning but also to edge etching by thermal wet oxidation of silicon or hydrogen chloride as described below. That is, a technique for thermally oxidizing silicon by introducing DCE and oxygen into a reaction system is attracting attention as a technique that can be applied to the creation of an element isolation structure in the STI (Shallow Trench Isolation) technique accompanying the progress of miniaturization ( JP, 2007-35823, A, etc.). In this technique, thermal wet oxidation with water and etching with hydrogen chloride generated by the reaction between DCE and oxygen are generated. Therefore, a single oxidation process is sharp for a three-dimensional structure such as a trench structure. The edge portion can be rounded or the oxide film thickness can be changed depending on the location. Therefore, the present invention can increase the degree of freedom of the silicon oxidation process. Further, in the thermal decomposition of DCE, it is possible to generate only hydrogen chloride, so that it can be used only for etching.

  Hereinafter, the present invention will be specifically described by way of examples. In the following comparative examples and examples, the silicon carbide processing tube of the semiconductor processing apparatus of FIG. 3 provided with the cleaning gas supply apparatus of FIG. 1 was cleaned. Table 1 shows a list of experimental conditions and the results obtained.

Comparative Example 1
Valves 32, 41, 52, 62, 61, 208 and 209 are closed (OFF), while valve 210 is opened (OPEN), and Ar is adjusted to 2 liters / minute with MFC 207 and introduced into reaction tube 200. However, the silicon carbide reaction tube 200 was heated by the reaction system heater 211 so that the temperature of the silicon carbide workpiece 212 within the silicon carbide reaction tube 200 was 1350 ° C. (corresponding to a cleaning process).

  After this heat treatment, when the temperature of the reaction tube 200 drops to room temperature, a 2-inch diameter silicon wafer is placed on the workpiece 212, the argon flow rate is set to 1800 ml / min with the MCF 207, and further Then, the valve 209 is opened, the oxygen is adjusted by the MCF 206 so as to be 200 ml / min, and the mixed gas is introduced into the reaction tube 200, while the temperature of the workpiece 212 becomes 1350 ° C. The reaction tube 200 was heated by 211 for 1 hour to perform a metal contamination transfer process.

After the metal contamination transfer treatment, the cooled wafer is taken out from the reaction tube 200, the wafer surface on which the contamination metal is transferred is exposed to hydrofluoric acid vapor, and the liquefied hydrofluoric acid solution is recovered, and Fe and Na are analyzed by ICP-MS analysis. The analysis process was performed. As a result of the analysis process, the contamination level of Fe is 1 to 5 × 10 ¹³ pieces / cm ² , the contamination level of Na is 5 to 10 × 10 ¹⁰ pieces / cm ² , and the detection limit (Fe: 0.5 × 10 ¹⁰ pieces / cm ² , Na: 0.7 × 10 ¹⁰ pieces / cm ² ), and the cleaning effect was insufficient.

Comparative Example 2
Valves 32, 41, and 62 were opened, and transdichloroethylene was introduced at a flow rate of 50 ml / min, and bubbled into the container 10 held at 20 ° C. (DCE transport amount: 7.5 × 10 ⁻⁴ mol / min). Min). On the other hand, the valve 52 was opened and the oxygen flow rate was adjusted with the MCF 51 so that the molar ratio [oxygen / DCE] α was 20. The temperatures of the DCE reaction unit 20 and the trap unit 70 were each room temperature. Therefore, in the DCE reaction unit 20, cleaning species (HCl and Cl ₂ ) are not generated from the DCE, and it is a mixed gas of DCE and oxygen that passes through the trap unit. A cleaning process, a contaminated metal transfer process, and an analysis process were performed in the same manner as in Comparative Example 1 except that this mixed gas was introduced into the reaction tube 200. As a result of the analysis process, the contamination level of Fe is 3 to 10 × 10 ¹² pieces / cm ² , and the contamination level of Na is 1 to 5 × 10 ¹⁰ pieces / cm ² , greatly exceeding the detection limit. The effect was insufficient. When the molar ratio [oxygen / DCE] α is 20, it is considered that the cleaning gas species with metal impurities is chlorine at least in the maximum temperature region in the reaction tube 200 where the workpiece 212 is placed.

Comparative Example 3
Except that the molar ratio [oxygen / DCE] α is set to about 5, a cleaning process was performed in the same manner as in Comparative Example 2. As a result, a transparent quartz lid in which carbon deposition blocked both open ends of the reaction tube 200 was obtained. The experiment was stopped because of visual observation. Stoichiometrically, it was a condition in which no carbon deposition occurred, but it is considered that it occurred because DCE and oxygen were not uniformly mixed in the reaction tube 200.

Example 1
A cleaning process, a metal contamination transfer process, and an analysis process were performed in the same manner as in Comparative Example 2 except that the temperature of the DCE reaction unit 20 was set to 500 ° C. No carbon deposition was observed, and the contamination level of Fe was 1 to 5 × 10 ¹¹ pieces / cm ² , which was significantly lower than that of Comparative Example 2. Therefore, it was confirmed that the cleaning gas was generated in the DCE reaction unit 20 in advance.

Example 2
The cleaning ratio was the same as in Example 1 except that the molar ratio [oxygen / DCE] α was lowered from 5 to 2.2 and the trap portion 70 was cooled to 0 ° C. in an ice bath as a countermeasure when free carbon was generated. Metal contamination transfer processing and analysis processing were performed. As a result, Fe and Na were each below the detection limit.

Example 3
Cleaning treatment, metal contamination transfer treatment, and analysis treatment were performed in the same manner as in Example 1 except that the trap 70 was cooled to -79 ° C. with a dry ice-acetone bath so that water in the cleaning gas could be removed. As a result, Fe and Na were each below the detection limit.

Example 4
A cleaning process, a metal contamination transfer process, and an analysis process were performed in the same manner as in Example 2 except that the molar ratio [oxygen / DCE] α was decreased from 2.2 to 1.8. As a result, it was confirmed that carbon was adhered to the inner wall on the inflow side of the cleaning gas supply path 60 in the trap bath 72 of the trap unit 70 and no carbon was adhered to the inner wall on the outflow side. Fe and Na were each below the detection limit.

Example 5
The cleaning process, the metal contamination transfer process, and the analysis were performed in the same manner as in Example 3 except that the valve 51 was closed and the DCE was introduced into the DCE reaction section 20 heated to 900 ° C. in the absence of oxygen to thermally decompose the DCE. Processed. As a result, it was confirmed that carbon was adhered to the inner wall on the inflow side of the cleaning gas supply path 60 in the trap bath 72 of the trap unit 70 and no carbon was adhered to the inner wall on the outflow side.

Reference example 1 (trap recovery)
The valves 32, 41 and 62 are closed, 52 and 61 are opened, the trap bath 72 of the trap unit 70 is replaced with a heater, and the cleaning gas supply path 60 in the trap unit 70 is heated to 400 ° C., and oxygen is supplied at 500 ml / min. The water and carbon could be completely removed after flowing for 1 hour.

  The cleaning gas supply device and the semiconductor processing apparatus of the present invention can efficiently clean metal contamination inside the processing tube of the semiconductor processing device so that carbon and water are not introduced into the processing tube. Therefore, it is useful for various processes such as silicon wafers.

FIG. 1 is a schematic view of a cleaning gas supply apparatus of the present invention. FIG. 2 is a partial schematic view of the cleaning gas supply apparatus of the present invention. FIG. 3 is a schematic diagram of the semiconductor processing apparatus of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Container part 11 Constant temperature bath 12 Temperature monitor 20 DCE reaction part 21 Heater 30 Carrier gas introduction path 31, 51, 205-207 MFC
32, 41, 52, 61, 62, 64 to 66, 208 to 210 Valve 40 Mixed gas supply path 50 Oxygen supply path 60 Cleaning gas supply path 63 Bypass path 70 Trap section 71 Constant temperature bath 72 Trap bath 100 Cleaning gas supply apparatus 200 Processing pipe 201, 202, 203 Process gas supply path 204 Exhaust gas path 211 Heating device 212 Object to be processed

Claims (6)

A cleaning gas supply device for supplying a gas for cleaning the inside of a processing tube of a semiconductor processing apparatus having a processing tube capable of heat-treating a semiconductor wafer,
A container containing dichloroethylene;
A dichloroethylene reaction section for preparing a cleaning gas by reacting dichloroethylene with oxygen or thermally decomposing dichloroethylene;
A carrier gas introduction path connected to the container so that bubbling of the carrier gas occurs in dichloroethylene in the container;
A mixed gas supply path for supplying a mixed gas of carrier gas and dichloroethylene from the container to the dichloroethylene reaction section;
An oxygen supply path for supplying oxygen to the dichloroethylene reaction section as required;
A cleaning gas supply device having a cleaning gas supply path for supplying a cleaning gas from the dichloroethylene reaction section to the processing tube.   The cleaning gas supply device according to claim 1, wherein a trap portion for removing a component unnecessary for cleaning in the cleaning gas is provided in the cleaning gas supply path.   2. A semiconductor processing apparatus comprising: a processing tube capable of processing a semiconductor wafer at a high temperature; at least one process gas supply path connected to the processing pipe; and an exhaust gas path connected to the processing pipe. 3. A semiconductor processing apparatus comprising the cleaning gas supply apparatus according to 2, wherein the cleaning gas supply path is connected to the process gas supply path or directly connected to a processing tube.   The semiconductor processing apparatus according to claim 3, wherein a structure in which at least a part is formed of silicon carbide exists in the processing tube. A cleaning method for cleaning the inside of a processing tube of a semiconductor processing apparatus having a processing tube capable of processing a semiconductor wafer at a high temperature,
A cleaning method in which dichloroethylene is reacted with oxygen or dichloroethylene is thermally decomposed to obtain a cleaning gas, and the obtained cleaning gas is introduced into the heated processing tube.   6. The cleaning method according to claim 5, wherein the cleaning gas purified by removing components unnecessary for cleaning in the acquired cleaning gas is introduced into the heated processing tube.

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