JP2007162139A - Film-deposition apparatus and source supplying apparatus therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a CVD (chemical vapor deposition) film-deposition apparatus where the concentration of a source gas in a carrier gas can be adjusted with high precision and at high speed even when the CVD process is conducted by using a low vapor pressure source material. <P>SOLUTION: The film-deposition apparatus is provided with a source supply apparatus supplying a source gas generated from a solid or liquid source to a film-formation chamber by transportion with a carrier gas. The source supplying apparatus comprises: a concentration measurement means measuring the concentration of the source gas; and an inert-gas flow-rate controlling means increasing/decreasing the flow rate of the inert gas added to the above carrier gas in the process of transporting the source gas on the basis of the measured concentration of the source gas. The inert-gas flow-rate controlling means performs control of increasing the flow rate of the inert gas when the measured concentration exceeds the upper limit value of the proper concentration range, and decreasing the flow rate of the inert gas when the measured concentration is lower than the lower limit value of the proper concentration range, and corrects any deviation from the proper concentration range of the source gas. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention generally relates to a film forming apparatus, and more particularly to a CVD film forming apparatus that monitors and controls the concentration of a source gas using an infrared spectrophotometer.

  The CVD film forming technique is an indispensable technique as a film forming process in manufacturing a semiconductor device.

  In a film formation process by a CVD method (chemical vapor deposition method), particularly an MOCVD (organometallic chemical vapor deposition method) method using an MO (organic metal) raw material, a liquid raw material compound generally containing the constituent elements of the film to be formed Or a liquid raw material formed by dissolving a solid raw material compound containing such a constituent element in a solvent is transported to a vaporizer provided in the vicinity of the processing vessel and vaporized by the vaporizer to form a source gas. Has been done. The source gas thus formed is introduced into a processing container of a CVD apparatus, and a desired insulating film, metal film, or semiconductor film is formed in the processing container by decomposing the source gas.

  On the other hand, in the MOCVD method, a liquid source compound or a solid source compound is heated and vaporized with a bubbler or the like to form a source gas, and the source gas thus formed is transferred to a processing vessel via a pipe. In some cases, the film is transported to form a desired film. In such a case, it is necessary to control the concentration of the source gas by controlling the flow rate or pressure of the source gas in the pipe.

  When the vaporizer is installed in the vicinity of the processing vessel or inside the processing vessel, the concentration of the source gas supplied to the processing vessel can be determined by using the liquid mass flow controller or the like for the amount of liquid transferred to the vaporizer. In general, it is not necessary to directly detect and monitor the concentration of the source gas introduced into the processing vessel. On the other hand, when the source gas can be generated sufficiently efficiently even when the source gas is transported from a bubbler or the like to a processing vessel via piping as in the latter case, the carrier gas flow rate and pressure should be controlled. Therefore, the concentration of the source gas supplied to the processing container can be easily adjusted, and in particular, the concentration of the source gas introduced into the processing container is not directly detected and monitored.

  However, a high-dielectric film or a ferroelectric film used in recent semiconductor devices, or a W film or a Ru film used in a semiconductor device using such a high-dielectric film or ferroelectric film is used. In this case, the vapor pressure of the source gas obtained from the raw material used is very low, so that even when the raw material compound is heated, a sufficient amount of gas can be obtained to apply the conventional normal source gas concentration control. Often not.

  That is, when performing a CVD process using such a low vapor pressure raw material compound, a small amount of vapor obtained by maintaining the raw material compound at a predetermined temperature is transported to the processing vessel together with the carrier gas as the source gas. However, at that time, the source gas is significantly diluted by the carrier gas, and it may be difficult to accurately detect the concentration of the source gas actually supplied to the processing container.

  In particular, when a desired CVD process is performed using a solid raw material compound having a low vapor pressure, the state of the raw material changes during the process as the raw material is consumed. In particular, the effective raw material surface area in contact with the carrier gas is reduced. Change. When such a change in the raw material surface area occurs, it is inevitable that the source gas concentration fluctuates greatly. In addition, since such a solid material has poor heat transfer compared to a liquid, a temperature distribution tends to occur in the material, and the concentration of the source gas tends to deviate from an appropriate concentration range.

  Even in the case of using a liquid raw material, since the vapor pressure of the raw material compound is low, fluctuations in the source gas concentration have a large effect on the process.

  Thus, in the recent MOCVD film forming apparatus, the direct detection of the source gas concentration is an important issue.

  When a film is formed by CVD using such a low vapor pressure raw material compound, direct concentration measurement or concentration monitoring of the source gas is desirable. However, acoustic emission (AE) conventionally used for gas concentration measurement is used. ) And a concentration measurement method using specific heat are not suitable for measuring the concentration of the source gas under a low pressure such as 50 Torr (6660 Pa) or less, and a low vapor pressure as in the MOCVD method. It cannot be used for the CVD film forming process using the raw materials.

On the other hand, conventionally, as disclosed in, for example, JP-A-2001-234348, a gas concentration is directly measured using a Fourier transform infrared spectrophotometer (FTIR), and the gas flow rate is controlled based on the measurement result. Membrane devices are known. In this conventional film forming apparatus, the mixing ratio of a plurality of gases is measured by FTIR, and the carrier gas flow rate ratio is adjusted when the plurality of gases are fed into the film forming processing container main body. The mixing ratio is adjusted.
JP 2001-234348 A Satake "Gas phase measurement of MOCVD raw material by FTIR" HORIBA Technical Reports Readout No.22, pp.36-39, March 2001

  When FTIR is used, the relative concentration of the source gas can be directly detected even under a low pressure. However, even if it is found that the concentration deviates from the proper range by using FTIR, it is not easy to immediately correct the concentration to the proper range for the following reason.

  That is, when it is determined by FTIR measurement that the source gas concentration is out of the proper range, the conventional film forming apparatus compensates for variations in the source gas concentration by increasing or decreasing the carrier gas flow rate. When the carrier gas flow rate is increased or decreased, the concentration of the source gas transferred to the processing vessel may show an unpredictable change depending on the relationship between the vaporization rate of the liquid raw material or the solid raw material and the carrier gas flow rate. Immediately correcting the source gas concentration to an appropriate range is not easy.

  For example, if the source gas concentration in the carrier gas is smaller than the appropriate range and the carrier gas flow rate is increased to increase the source gas concentration by promoting the vaporization and transportation of the raw material, the vaporization of the raw material is sufficient. The source gas formed as a result is diluted with a large amount of carrier gas, and the source gas concentration may decrease instead. In this case, it is necessary to perform complicated and time-consuming control to recover a desired source gas concentration. Also, if the source gas concentration in the carrier gas is larger than the appropriate range, the carrier gas flow rate is reduced, and if the source gas concentration is reduced by suppressing the vaporization and transportation of the raw material, the carrier gas flow rate is reduced. As a result, the concentration of the source gas may increase.

  The source gas concentration can also be controlled by adjusting the temperature of the liquid raw material or solid raw material, but the vaporization rate of the raw material varies greatly depending on the vaporization temperature. In that case, very strict temperature control is required. However, such rapid and precise fine adjustment of the vaporization temperature is difficult. Also, even if the vaporization temperature is changed during one film formation process, the response of the corresponding source gas concentration is poor, and it is quick to compensate for variations in the source gas concentration that occur during one film formation process. When it is necessary to adjust the concentration of the source gas, it is difficult to apply this method.

  Accordingly, it is a general object of the present invention to provide a new and useful film forming apparatus that solves the above problems.

  A more specific problem of the present invention is CVD that can adjust the concentration of the source gas supplied to the processing container together with the carrier gas with high accuracy and speed during the film forming process by the CVD method using the low vapor pressure raw material. An object of the present invention is to provide a film forming apparatus and a raw material supply apparatus used therefor.

The present invention solves the above problems.
As described in claim 1,
A film forming apparatus provided with a raw material supply device for conveying a source gas generated from a solid or liquid raw material to a film forming chamber by a carrier gas,
The raw material supply device includes a concentration measuring means for measuring the concentration of the source gas,
An inert gas mass flow rate control means for increasing or decreasing the flow rate of the inert gas added to the carrier gas that is transporting the source gas based on the measured concentration of the source gas,
The inert gas mass flow rate control means increases the flow rate of the inert gas when the measured concentration exceeds the upper limit value of the concentration range appropriate for the film forming process, and the measured concentration is within the appropriate concentration range. If the lower limit value of the gas concentration is below the lower limit value, the flow rate of the inert gas is controlled, and the deviation from the appropriate concentration range of the source gas concentration is corrected. Or as claimed in claim 2,
The film forming apparatus according to claim 1 or 3, wherein the concentration measuring means is arranged to measure the concentration of the source gas after the inert gas is added to the carrier gas. Like
The film forming apparatus according to claim 1 or 2, wherein the concentration measuring means is arranged to measure the concentration of the source gas before film formation and / or during film formation, or as described in claim 4. In addition,
In the raw material supply device, the flow path through which the carrier gas with the inert gas added flows is a first flow path leading to the film formation chamber or a second flow path bypassing the film formation chamber. And further includes switching means for selectively switching,
The said concentration measurement means is arrange | positioned in either the 1st flow path or the 2nd flow path, The film-forming apparatus as described in any one of Claims 1 thru | or 3, or Claim 5 characterized by the above-mentioned. like,
The inert gas mass flow rate control means increases or decreases the flow rate of the inert gas added to the carrier gas, and the flow rate of the carrier gas so that the flow rate of the carrier gas containing the inert gas becomes substantially constant. The film forming apparatus according to claim 1, or as described in claim 6,
The carrier gas and the inert gas are introduced from the same flow path, and the inert gas is diverted to another flow path before the carrier gas conveys the source gas, and the carrier gas is After conveying the source gas, by the film forming apparatus according to any one of claims 1 to 5, which merges with the flow path of the carrier gas, or as described in claim 7,
The inert gas mass flow rate control means controls the flow rate divided into the other flow path by the film forming apparatus according to claim 6, or as described in claim 8.
The source gas is W (CO) ₆ , by the film forming apparatus according to claim 1, or as described in claim 9.
The concentration measuring means is a Fourier transform infrared spectrophotometer, by the film forming apparatus according to any one of claims 1 to 8, or as described in claim 10.
It solves with the raw material supply apparatus with which the film-forming apparatus as described in any one of Claims 1 thru | or 9 is provided.

  According to the present invention, the concentration of the source gas can be controlled before or during the film formation process for each substrate to be processed, and the source gas having an appropriate concentration range can be always supplied into the processing container body during the film formation process. . As a result, it is possible to stably realize film formation with good film quality. In addition, since the source gas is adjusted so as to have a concentration within an appropriate concentration range with the inert gas added, when the measured concentration exceeds the upper limit value of the appropriate concentration range, If the flow rate of the inert gas is increased and conversely falls below the lower limit value of the concentration range, the deviation can be corrected immediately by controlling the flow rate of the inert gas. In addition, the flow rate of the dilution gas that should be increased or decreased to correct this deviation depends only on the measured concentration by the concentration measuring means and the predetermined appropriate concentration range. Unlike the case, it is highly accurate and can be predicted quickly and easily.

  Further, since the concentration of the source gas is measured in a state including the added inert gas, it is measured in a state close to the gas supplied at the time of actual film formation. In particular, when the concentration in the flow path leading to the film formation chamber is measured, the concentration can be directly controlled with respect to the gas supplied at the time of film formation. Such a direct control can be said to be a control that can be achieved only by the present invention that can quickly correct the deviation as described above.

  If a Fourier transform infrared spectrophotometer is used as the concentration measuring means, the Fourier transform infrared spectrophotometer can selectively measure the concentration of the raw material with high sensitivity and high accuracy even under a low pressure. Therefore, it is suitable for film formation using a low vapor pressure raw material, and particularly a low vapor pressure solid raw material in which the amount of generated source gas is likely to fluctuate.

  In particular, when a signal is supplied into a gas, such as a Fourier transform infrared spectrophotometer or a non-dispersive infrared spectrophotometer, and the source gas concentration is obtained based on the signal that has passed through the gas, the entire mixed gas to be measured is measured. The absolute concentration of the source gas can be obtained by measuring the pressure and correcting the detection signal obtained based on the measured pressure.

  Since the present invention is as described above, the following effects can be obtained. According to the present invention, the concentration of the source gas can be controlled before or during the film formation process for each substrate to be processed, and the source gas having an appropriate concentration range can be always supplied into the processing container body during the film formation process. .

[First Embodiment]
FIG. 1 is a cross-sectional view schematically showing a configuration of a processing vessel 100 used in the first embodiment of the present invention.

  Referring to FIG. 1, the processing container 100 is disposed in a processing container main body 120 and the processing container main body 120, and holds a semiconductor substrate 101 and a heating element 132 driven by a power source 132A. A mounting head 130 and a shower head that is provided in the processing container main body 120 so as to face the mounting base 130 and introduces a gas supplied from a raw material supply line 30 described later into a process space in the processing container main body 120. 110 and a gate valve 140 that is provided on the side wall of the processing container main body 120 and carries the semiconductor substrate 101 in and out, and the processing container main body 120 is exhausted through the exhaust line 32.

  FIG. 2 schematically shows a configuration of an MOCVD apparatus 200 according to the first embodiment of the present invention using the processing vessel 100 of FIG.

Referring to FIG. 2, the MOCVD apparatus 200 includes a raw material container 10, and an inert gas such as Ar, Kr, N ₂ , H ₂ is supplied to the raw material container 10, the raw material supply line 30, and the raw material supply line 30. It is supplied via a mass flow controller (MFC) 12A provided in a part. The mass flow controller 12A controls the flow rate of the inert gas supplied to the raw material container 10.

  A liquid or solid raw material is accommodated in the raw material container 10, and a source gas is generated in the raw material container 10 by vaporizing these raw materials. The inert gas supplied to the raw material container 10 acts as a carrier gas, and transports the source gas from the raw material container 10 to the processing container 100. That is, the source gas flows out together with the carrier gas from the outlet of the raw material container 10 through the raw material supply line 30. A pressure gauge 18 for detecting the pressure in the raw material container 10 is provided near the outlet of the raw material container 10 in the raw material supply line 30.

In the MOCVD apparatus 200 of FIG. 2, the raw material supply line 30 is further provided with a dilution gas line 31 that merges after the pressure gauge 18, that is, at a downstream position. The dilution gas line 31 includes Ar, An inert gas such as Kr, N ₂ , or H ₂ is supplied via a mass flow controller (MFC) 12B. The mass flow controller 12 </ b> B controls the flow rate of the inert gas that joins the raw material supply line 30. The inert gas is added as a dilution gas to the source gas and the carrier gas from the raw material container 10 at the time of joining to the raw material supply line 30 (hereinafter, the gas containing these three gases is referred to as “mixed gas”). , Dilute the concentration of the source gas. The mixed gas is supplied to the processing container 100 through the raw material supply line 30.

  In the configuration of FIG. 2, a turbo molecular pump (TMP) 14 is provided in the exhaust line 32 connected to the processing vessel 100, and the turbo molecular pump 14 is boosted behind the turbo molecular pump 14. A dry pump (DP) 16 is provided. These pumps 14 and 16 maintain the inside of the processing container main body 120 at a predetermined degree of vacuum. For example, the turbo molecular pump 14 can reduce the pressure in the processing vessel main body 120 to a high vacuum of, for example, about 1 Torr (133 Pa) in cooperation with the dry pump 16, and uses a raw material having a low vapor pressure. A film forming process is possible.

  The raw material supply line 30 is provided with a preflow line 33 that bypasses the processing container 100 on the downstream side of the raw material container 10, and the mixed gas from the raw material supply line 30 is preliminarily opened and closed by opening and closing the valve 26. It is selectively supplied to the raw material supply line 30 that leads to the flow line 33 or the processing vessel 100. The preflow line 33 is provided to stabilize the flow rate of the mixed gas supplied to the processing container 100 during film formation and to adjust the concentration of the mixed gas in advance. The mixed gas is supplied prior to processing each semiconductor substrate 101.

  By the way, the mixed gas supplied to the processing container 100 needs to include a source gas having an appropriate concentration range in order to realize a desired film forming process. In addition, this mixed gas needs to include a source gas having an appropriate concentration range that is not different for each film forming process in order to reduce variations in film quality for each film forming process.

  On the other hand, in the MOCVD apparatus 200 of FIG. 2, since the carrier gas (including the dilution gas) is interposed when the source gas is supplied, the source gas is different from the case where the source gas is directly supplied by the vaporizer. It is difficult to accurately detect the gas concentration. Further, the concentration of the source gas tends to fluctuate due to fluctuations in the pressure in the raw material container 10 and the surface area of the raw material (particularly solid raw material), and it is difficult to stabilize the concentration of the source gas in the mixed gas. is there.

  Therefore, in the first embodiment of the present invention, the Fourier transform infrared spectrophotometer is used to accurately detect the change in the concentration of the source gas in the mixed gas, and the mass flow control devices 12B and / or 12A are provided. It is used to control the flow rate of the inert gas so that the concentration of the source gas in the mixed gas is always in an appropriate concentration range.

  More specifically, in the present embodiment, in the MOCVD apparatus 200, a Fourier transform infrared spectrophotometer 40 (hereinafter referred to as this) having a wave number monitor using laser light and a moving mirror in the preflow line 33. Is referred to as “FTIR40”). The FTIR 40 has an interferometer, an infrared detection means, and an arithmetic processing unit, and irradiates the analysis target gas with infrared light through the interferometer and outputs an output value detected by the infrared light detection means. , The concentration of the gas component contained in the gas is measured from the absorption spectrum of each component contained in the gas.

  The preflow line 33 joins the exhaust line 32 described above on the upstream side of the dry pump 16 and is maintained at a predetermined degree of vacuum by the dry pump 16. In the MOCVD apparatus 200 of FIG. 2, by providing the FTIR 40 in the preflow line 33, the pressure in the raw material supply line 30 is maintained at a low value of 50 Torr (6660 Pa) or less, which cannot be measured by acoustic emission. However, the source gas concentration can be measured.

  In this embodiment, the FTIR 40 of the preflow line 33 measures the concentration of the source gas in the mixed gas (hereinafter, the concentration measured by the FTIR 40 is referred to as “measured concentration”), and a signal representing the measured concentration is controlled by the control device. To 201. On the other hand, when the control device 201 determines that the measured concentration change output by the FTIR 40 deviates from an appropriate range, the control device 201 controls the mass flow control devices 12B and / or 12A to control the flow rate of the inert gas. Increase or decrease. The control device 201 may be incorporated in the FTIR 40 itself or in the mass flow control device 12B and / or 12A itself.

  According to the first embodiment of the present invention described above, the concentration of the source gas in the mixed gas is controlled to be constant before the film forming process for each substrate to be processed, and the source gas having a concentration adjusted for each film forming process. Is introduced into the main body of the processing container, so that variations in film quality for each film forming process can be reduced. Further, by using FTIR, it can be applied to a film forming process using a raw material having a low vapor pressure.

  In the present embodiment, the source gas concentration is adjusted at the beginning of the process so as to be within an appropriate concentration range in a state including the dilution gas added to the carrier gas. Even when the concentration of the source gas is reduced due to a decrease in the raw material or the vaporization of the raw material, the concentration of the source gas in the mixed gas is rapidly increased by reducing the flow rate of the dilution gas. be able to. If the concentration of the source gas decreases due to a decrease in the raw material, etc., the vaporization efficiency of the raw material will decrease even if the carrier gas flow rate is increased (especially in the case of a solid raw material, the surface area will decrease). Although the concentration of the source gas is not substantially increased, according to the present embodiment, the concentration of the source gas is increased by reducing the flow rate of the dilution gas even in such a case. Is possible. At this time, the flow rate of the diluent gas may be reduced and the flow rate of the carrier gas may be increased.

  Even when the flow rate of the dilution gas is increased or decreased to optimize the concentration, according to the present embodiment, since the dilution gas does not contain the source gas, the increase / decrease amount can be easily measured by FTIR. It can be easily determined based only on the density and a predetermined appropriate density range. As described above, the concentration control of the source gas by increasing / decreasing the flow rate of the dilution gas can be executed with high accuracy, quickly and easily unlike the case of concentration control only by increasing / decreasing the flow rate of the carrier gas.

[Second Embodiment]
FIG. 3 schematically shows the configuration of an MOCVD apparatus 200A according to the second embodiment of the present invention. In the figure, portions corresponding to the portions described above are denoted by the same reference numerals, and description thereof is omitted.

Referring to FIG. 3, an inert gas such as Ar, Kr, N ₂ , and H ₂ is supplied to the raw material container 10 through the raw material supply line 30 via the mass flow controller (MFC) 12A. The mass flow controller 12 </ b> A controls the flow rate of the inert gas supplied to the raw material container 10. The raw material container 10 stores a liquid raw material or a solid raw material used for film formation. The source gas is generated by vaporizing these raw materials in the raw material container 10. The inert gas supplied to the raw material container 10 is transported through the raw material supply line 30 from the outlet of the raw material container 10 as the source gas as a carrier gas.

  According to the second embodiment of the present invention, the raw material supply line 30 is provided with a dilution gas line 31 that bypasses the raw material container 10 after the mass flow controller 12A. The inert gas is supplied to the dilution gas line 31 in a diverted manner from the raw material supply line 30. This inert gas is mixed with the carrier gas that carries the source gas from the raw material container 10 as a dilution gas at the time of merging into the raw material supply line 30 (point B in the figure) (hereinafter, these three gases are combined). The gas containing this is referred to as “mixed gas”), and the source gas concentration is diluted. The flow rate of the dilution gas is adjusted by a valve 20 provided in the dilution gas line 31.

  This mixed gas is then selectively supplied to the processing vessel 100 as described above through the raw material supply line 30 or to the preflow line 33 equipped with the FTIR 40 as in the first embodiment. The

  The FTIR 40 of the preflow line 33 measures the source gas concentration in the mixed gas (hereinafter, the concentration measured by the FTIR 40 is referred to as “measured concentration”), and outputs the measured concentration to the control device 201. When it is determined that the measured concentration output from the FTIR 40 is outside the appropriate concentration range, the control device 201 performs control to increase or decrease the flow rate of the dilution gas by controlling the valve 20.

  According to the second embodiment of the present invention described above, as in the first embodiment, by monitoring the concentration of the source gas by the FTIR 40 of the preflow line 33, the quality of each substrate to be processed is formed. Can be reduced. Further, by using FTIR, it can be applied to a film forming process using a raw material having a low vapor pressure. Further, deviation from the appropriate range of the concentration of the source gas in the mixed gas can be corrected immediately by increasing or decreasing the flow rate of the dilution gas.

  In addition, since the flow rate of the dilution gas is adjusted by the valve 20 of the dilution gas line 31, the flow rates of both the dilution gas and the carrier gas can be adjusted using the single mass flow controller 12A. Further, since the dilution gas line 31 is diverted from the raw material supply line 30 and merged again, the flow rate of the inert gas before the diversion is substantially the same as the flow rate of the inert gas at the merge point B. Thereby, the flow rate of the mixed gas supplied to the processing container 100 can be kept constant while controlling the concentration of the source gas by increasing or decreasing the flow rate of the dilution gas, and the film quality of the film formed on each substrate to be processed can be maintained. Variations can be further reduced with a simple configuration.

[Third Embodiment]
FIG. 4 schematically shows a configuration of an MOCVD apparatus 200B according to the third embodiment of the present invention. However, in the figure, the same reference numerals are assigned to portions corresponding to the portions described above, and description thereof is omitted.

Referring to FIG. 4, an inert gas such as Ar, Kr, N ₂ , and H ₂ is supplied to the raw material container 10 through the raw material supply line 30 via the mass flow controller (MFC) 12A. The mass flow controller 12 </ b> A controls the flow rate of the inert gas supplied to the raw material container 10. The raw material container 10 stores a liquid raw material or a solid raw material used for film formation. The source gas is generated by vaporizing these raw materials in the raw material container 10. The inert gas supplied to the raw material container 10 carries the source gas from the raw material container 10 as a carrier gas. A pressure gauge 18 for detecting the pressure in the raw material container 10 is provided near the outlet of the raw material container 10 in the raw material supply line 30.

The raw material supply line 30 is provided with a dilution gas line 31 that merges after the pressure gauge 18. An inert gas such as Ar, Kr, N ₂ and H ₂ is supplied to the dilution gas line 31 via a mass flow controller (MFC) 12B. The mass flow controller 12 </ b> B controls the flow rate of the inert gas that joins the raw material supply line 30. The inert gas is mixed with the source gas and the carrier gas from the raw material container 10 as a dilution gas at the time of joining to the raw material supply line 30 (hereinafter, the gas containing these three gases is referred to as “mixed gas”). The source gas concentration will be diluted. The mixed gas is supplied to the processing container 100 as described above through the raw material supply line 30. In the present embodiment, the configuration of the dilution gas line 31 and the dilution gas line 31 described above may be the same as that of the second embodiment.

  A turbo molecular pump (TMP) 14 may be provided in the exhaust line 32 for exhausting the reaction gas and the like from the processing vessel 100, and a dry pump 16 is further provided later. These pumps 14 and 16 maintain the inside of the processing container main body 120 at a predetermined degree of vacuum. This turbo molecular pump 14 cooperates with the dry pump 16 to make the pressure in the processing vessel main body 120 a high vacuum of, for example, 1 Torr (133 Pa) or less, and a film forming process using a low vapor pressure raw material. Especially needed for.

  The raw material supply line 30 is provided with a preflow line 33 that bypasses the processing container 100 after the raw material container 10. The preflow line 33 is supplied with the mixed gas from the raw material supply line 30. This mixed gas is selectively supplied to the preflow line 33 or the raw material supply line 30 leading to the processing container 100 by opening and closing the valve 26. The preflow line 33 is a gas flow path for stabilizing the flow rate of the mixed gas supplied to the processing container 100 during film formation and adjusting the concentration of the mixed gas in advance. The preflow line 33 is joined to the exhaust line 32 described above before the dry pump 16. Accordingly, the preflow line 33 is maintained at a predetermined degree of vacuum by the dry pump 16.

  In the first and second embodiments described above, the concentration of the mixed gas supplied to the processing container 100 is monitored by the FTIR 40 installed in the preflow line 33. However, when the mixed gas supplied to the preflow line 33 is switched to the raw material supply line 30 leading to the processing vessel 100 and supplied, the difference in the pipe diameter of each line, the presence of the processing vessel main body 120 and the difference in the vacuum pump system 37. Due to (difference in pressure in the raw material container 10), the concentration of the source gas changes before and after the switching. In particular, when a film is formed using a low vapor pressure raw material, the pressure in the raw material container 10 may be maintained at a low pressure of 1 Torr (133 Pa) or less by the turbo molecular pump 14 to promote vaporization. When the flow line 33 is used, it is not possible to maintain the pressure in the raw material container 10 at such a low pressure only by the dry pump 16.

  Even in this case, as in the first and second embodiments described above, the concentration of the source gas in the mixed gas flowing through the preflow line 33 is kept within a predetermined range before each film forming process. Thus, it is possible to reduce the variation in the film quality of the film formed on each substrate to be processed between the respective film forming processes. However, it is more useful if the concentration of the source gas in the mixed gas actually introduced into the processing vessel 100 can be controlled. On the other hand, since the mixed gas introduced into the processing container 100 is a gas that is actually used for film formation, it is inappropriate to adjust the concentration of the source gas in the mixed gas over a long period of time. There is. In the present invention, as described above, the deviation of the concentration of the source gas can be corrected immediately by increasing or decreasing the dilution gas, so that the concentration of the source gas in the mixed gas actually introduced into the processing vessel 100 can be controlled. .

  Specifically, according to the third embodiment of the present invention, the FTIR 40 is provided in the raw material supply line 30 leading to the processing container 100 in order to measure the concentration of the source gas in the mixed gas introduced into the processing container 100. It is done. The raw material supply line 30 may be maintained at a low pressure of 1 Torr (133 Pa) or less by the turbo molecular pump 14 and the dry pump 16 in order to promote vaporization of the low vapor pressure raw material. Even in such a case, the concentration of the source gas can be measured with high accuracy by the FTIR 40.

  In this embodiment, the FTIR 40 of the raw material supply line 30 leading to the processing vessel 100 measures the concentration of the source gas in the mixed gas (hereinafter, the concentration measured by the FTIR 40 is referred to as “measured concentration”), and the measured concentration is Output to the control device 201. When the controller 201 determines that the measured concentration output by the FTIR 40 is out of the appropriate concentration range, the controller 201 controls the mass flow controllers 12B and / or 12A, as in the above-described embodiment. Control is performed to increase or decrease the flow rate of the inert gas supplied through the air.

  According to the third embodiment of the present invention described above, the deviation from the appropriate range of the concentration of the source gas in the mixed gas is immediately corrected by increasing or decreasing the flow rate of the dilution gas, as in the above-described embodiment. can do.

  Further, the concentration of the source gas in the mixed gas that is actually used for film formation can be controlled by the FTIR 40 of the raw material supply line 30 that leads to the processing container 100. Therefore, it is possible to monitor the concentration of the source gas in the mixed gas that is actually used for the film forming process, and to correct the deviation immediately when the concentration of the source gas deviates from an appropriate range. . As a result, the film forming process can always be performed using a source gas having a concentration in an appropriate range, so that a desired film quality can always be maintained and the quality can be made uniform between the processes.

[Fourth Embodiment]
FIG. 5 schematically shows the configuration of an MOCVD apparatus 200C according to the fourth embodiment of the present invention.

Referring to FIG. 5, an inert gas such as Ar, Kr, N ₂ , and H ₂ is supplied to the raw material container 10 through the raw material supply line 30 via the mass flow controller (MFC) 12A. The mass flow controller 12 </ b> A controls the flow rate of the inert gas supplied to the raw material container 10. The raw material container 10 stores a liquid raw material or a solid raw material used for film formation. The source gas is generated by vaporizing these raw materials in the raw material container 10. The inert gas supplied to the raw material container 10 carries the source gas from the raw material container 10 as a carrier gas. A pressure gauge 18 for detecting the pressure in the raw material container 10 is provided near the outlet of the raw material container 10 in the raw material supply line 30.

The raw material supply line 30 is provided with a dilution gas line 31 that merges after the pressure gauge 18. An inert gas such as Ar, Kr, N ₂ and H ₂ is supplied to the dilution gas line 31 via a mass flow controller (MFC) 12B. The mass flow controller 12 </ b> B controls the flow rate of the inert gas that joins the raw material supply line 30. The inert gas is mixed with the source gas and the carrier gas from the raw material container 10 as a dilution gas at the time of joining to the raw material supply line 30 (hereinafter, the gas containing these three gases is referred to as “mixed gas”). The source gas concentration will be diluted. The mixed gas is supplied to the processing container 100 as described above through the raw material supply line 30. In the present embodiment, the configuration of the dilution gas line 31 and the dilution gas line 31 described above may be the same as that of the second embodiment.

  The raw material supply line 30 is provided with a preflow line 33 that bypasses the processing container 100 after the raw material container 10. The preflow line 33 is supplied with the mixed gas from the raw material supply line 30. This mixed gas is selectively supplied to the preflow line 33 or the raw material supply line 30 leading to the processing container 100 by opening and closing the valve 26. The preflow line 33 is a gas flow path for stabilizing the flow rate of the mixed gas supplied to the processing container 100 during film formation and adjusting the concentration of the mixed gas in advance. The preflow line 33 is joined to the exhaust line 32 described above before the dry pump 16. Accordingly, the preflow line 33 is maintained at a predetermined degree of vacuum by the dry pump 16.

  According to the fourth embodiment of the present invention, both the concentration of the source gas in the mixed gas introduced into the processing vessel 100 and the concentration of the source gas in the mixed gas flowing through the preflow line 33 can be measured. The raw material supply line 30 is provided with an FTIR 40 after the dilution gas line 31 is joined and before the preflow line 33 is branched. As shown in FIG. 5, the FTIR 40 may be provided in a bypass line 35 that bypasses the raw material supply line 30. The bypass line 35 is provided with valves 21 and 25, and a valve 23 is provided at a portion of the raw material supply line 30 that is bypassed by the bypass line 35. The mixed gas may be selectively supplied to the bypass line 35 or the raw material supply line 30 by opening and closing these valves 21, 23, 25. Thereby, when measuring the concentration of the source gas, the mixed gas is supplied to the bypass line 35, and when there is no need to measure the concentration of the source gas, it is possible to selectively supply the raw material supply line 30. Become.

  The output of the FTIR is supplied to the control device 201, and the control device 201 controls the mass flow rate control devices 12A and / or 12B according to the output of the FTIR.

  According to the fourth embodiment of the present invention described above, the deviation from the appropriate range of the concentration of the source gas in the mixed gas is immediately corrected by increasing or decreasing the flow rate of the dilution gas, as in the above-described embodiment. can do.

  Further, since the FTIR 40 is arranged so as to measure both the concentration of the source gas introduced into the processing vessel 100 and the concentration of the source gas in the preflow line 33, the source gas before being used for film formation is arranged. In addition to the concentration, the concentration of the source gas actually used for film formation can be controlled. Therefore, it is possible to monitor the concentration of the source gas in the mixed gas that is actually used for the film forming process, and to correct the deviation immediately when the concentration of the source gas deviates from an appropriate range. . In addition, since the mixed gas actually used for film formation has already been adjusted in the concentration of the source gas when the preflow line 33 is used, the concentration of the source gas introduced into the processing vessel 100 is There is no significant departure from the appropriate range initially. As a result, it is possible to avoid a drastic change in the concentration of the source gas by greatly increasing or decreasing the flow rate of the dilution gas during the film forming process, thereby realizing a more stable film forming process.

  Each embodiment described above relates to a film forming process using one kind of source gas, but the present invention can also be applied to a film forming process using two or more kinds of source gases. In such a case, the two or more types of raw material supply lines that supply each source gas to the CVD film forming apparatus as described above have the same configuration as that of each of the embodiments described above.

  In each of the above-described embodiments, the preflow line 33 is shown to join the exhaust line 32 before the dry pump 16. In this case, when the FTIR 40 is installed in the preflow line 33, the concentration is measured in a higher pressure state than when the source gas actually flows into the processing container 100. In order to avoid this and to measure the concentration at the same pressure as when flowing into the processing vessel 100, the pipe from the exhaust side of the FTIR 40 to the point before joining the dry pump 16 is thickened, or the preflow line 33 is connected to the dry pump. 16 before the turbo molecular pump 14 instead of before 16, or a pressure regulating valve (not shown) is provided before the merge so that the cell pressure when the FTIR 40 measures the concentration You may adjust so that it may correspond to piping pressure.

  Next, the control method by the control apparatus 201 in each embodiment mentioned above is mentioned.

  FIG. 6 shows an embodiment of a control routine for controlling the concentration of the source gas in the mixed gas, which is executed by the control device 201. Although not shown in the figure, the control device 201 is composed of a microcomputer mainly composed of a CPU, and includes a target concentration C1 of the source gas in the mixed gas, an initial set value Q1 of the flow rate of the dilution gas, and a carrier gas. Is stored in a memory such as a RAM.

  In step 300, the microcomputer generates a control signal in which the flow rate of the dilution gas is Q1 and the flow rate of the carrier gas is Q2 based on the stored value of the memory, and transmits the control signal to the mass flow rate control devices 12A and 12B.

  In step 302, in response to the measured concentration C2 input from the FTIR, the microcomputer determines the flow rate of the dilution gas and the flow rate of the carrier gas so that the measured concentration C2 becomes the target concentration C1. Alternatively, the microcomputer determines whether or not the measured concentration C2 deviates from the allowable range based on the target concentration C1, and only when the microcomputer determines that the measured concentration C2 deviates from the allowable range, the measured concentration C2 is within the allowable range. The flow rate of the dilution gas and the flow rate of the carrier gas may be determined so that

  In this embodiment, the total flow rate of the dilution gas and the carrier gas is constant before and after the adjustment, the flow rate of the adjusted dilution gas is expressed as Q1 ′ = Q1 + β, and the flow rate of the adjusted carrier gas is expressed as Q2 ′ = Q2−β. β is determined.

  That is, in step 302 of the initial routine, -Q2 / 10 or + Q2 / 10 is substituted for β, and the initial setting values Q1 and Q2 are updated to Q1 ′ and Q2 ′, respectively, and stored in the memory. It is transmitted to the mass flow controllers 12A and 12B. Thereafter, the process of step 302 is repeated in response to the input from FTIR.

  In step 302 of the next routine, the difference between the newly measured measured density C2 and the target density C1 becomes small, and β determined and substituted in the previous routine (the previous routine is the initial routine). In this case, a new β having an absolute value smaller than −Q2 / 10 or + Q2 / 10) is determined and substituted, and similarly, the initial setting values Q1 and Q2 are updated to Q1 ′ and Q2 ′, respectively, in the memory. The stored control signal is transmitted to the mass flow controllers 12A and 12B.

[Example 1]
FIG. 7 shows an infrared absorption spectrum of the organometallic gas W (CO) ₆ (hexacarbonyltungsten) as a measurement result by FTIR (the horizontal axis indicates the wave number and the vertical axis indicates the transmittance). From FIG. 7, it can be seen that characteristic absorption corresponding to the carbonyl group (= CO) of the organometallic gas W (CO) ₆ appears in the vicinity of wave numbers (cm ⁻¹ ) 2900, 1900, and 500.

In order to confirm the sensitivity of FTIR to the concentration change of W (CO) ₆ gas, the temperature of the raw material container is set to three types of unheated (25 ° C.), 45 ° C. and 60 ° C., and argon gas as carrier gas is 50 sccm (1 sccm is , Meaning that a fluid at 0 ° C. and 1 atm flows 1 cm ³ ). The FTIR was installed at the position shown in the third embodiment (that is, not the preflow line but the position before the film forming apparatus). At this time, the pressure in the cell portion of FTIR was 80 Pa, 85 Pa, and 87 Pa, respectively, and the values obtained by correcting the absorbance converted from the peak intensity of the carbonyl group at 1330 Pa (10 Torr) were 0.337, 0.656, and 1 respectively. .050. From this result, it was confirmed that the sensitivity of FTIR was sufficiently high even at a low pressure, and it was found that the change in the concentration of W (CO) ₆ gas could be monitored based on the change in the peak intensity at each wave number.

[Example 2]
W (CO) ₆ was used as a raw material, and argon gas was used as a carrier gas and a dilution gas. FTIR is installed at the position shown in the third embodiment (that is, not in the preflow line but in front of the film forming apparatus), the temperature of the raw material container is 45 ° C., and the carrier gas is 50 sccm and the dilution gas is 10 sccm. I let you. At this time, the value obtained by correcting the absorbance converted from the peak intensity of the carbonyl group with 1330 Pa (10 Torr) was 0.235.

  Since the absorbance changed to 0.267 during the flow for 5 minutes, the absorbance could be returned to 0.233 when the flow rate of the dilution gas was gradually adjusted to increase to 12 sccm.

[Example 3]
A tungsten film was formed by thermal CVD using W (CO) ₆ as a raw material. The temperature of the raw material container 10 was 60 degreeC. The carrier gas was argon gas and the flow rate was 300 sccm, and the dilution gas was argon gas and the flow rate was 100 sccm.

In addition, in order to promote the vaporization of W (CO) ₆ which is a low vapor pressure raw material (vapor pressure at 60 ° C. is about 106 Pa) and improve the film formation rate, the turbo molecular pump and the dry pump are operated, and the processing vessel body An internal pressure of 0.15 Torr (about 20 Pa) and a raw material supply line pressure of 1.5 Torr (about 200 Pa) were realized.

  When the film formation process was performed at a substrate temperature of 450 ° C., a tungsten film was formed at a film formation rate of 7.1 nm / min, and the specific resistance of the tungsten film was 27 μΩcm.

[Fifth Embodiment]
In each of the embodiments described above, the concentration of the source gas supplied to the processing vessel main body 100 using the FTIR 40 and the control device 201 is maintained constant after one process is started. Since the absolute concentration of the gas is not measured, when the gas supply is stopped after completing a series of processes and then the next series of processes is started, a desired source gas concentration is realized after the process starts. It is necessary to process a large number of test substrates and search for optimum processing conditions. However, searching for such optimum conditions is time consuming and increases the cost of the manufactured semiconductor device.

  On the other hand, FIG. 8 shows a configuration of an MOCVD apparatus 200D according to the fifth embodiment of the present invention, which can measure the absolute concentration of the source gas using FTIR. However, in the figure, the same reference numerals are given to the parts described above, and the description will be omitted.

  Referring to FIG. 8, the MOCVD apparatus 200 </ b> D has the same configuration as the previous MOCVD apparatus 200 </ b> A, but the downstream side of the point P <b> 1 where the dilution gas line 31 joins the raw material supply line 30 and the processing vessel 100. Another pressure gauge 18A is provided on the upstream side, and the pressure of the mixed gas in the pipe 30 in a state after the Ar gas from the dilution gas line 31 is added is measured.

  The pressure gauge 18A supplies an output signal corresponding to the detected pressure to the control device 201, and the control device 201 sends the output signal to the processing container 100 based on the output signal of the FTIR 40 and the output signal of the pressure gauge 18A. The absolute concentration of the source gas in the mixed gas supplied through the source gas line 30 is obtained.

In general, in the configuration in which the source gas is supplied together with the carrier gas and the dilution gas into the processing container 100 through the pipe 30, the source gas flow rate S supplied to the processing container 100 and the source gas transported through the pipe 30. The absorption spectrum intensity Ir of the source gas component obtained by FTIR or the like for the mixed gas of / carrier gas / dilution gas, the pressure P in the pipe 30, and the total flow rate of the mixed gas in the pipe 30, that is, the source gas Between the total flow rate C of the carrier gas and the dilution gas,
S = A × Ir × (1 / P) × C (1)
It is considered that this relationship is established. However, A is a coefficient depending on the cell length.

  For example, if the source gas flow rate S is increased under conditions where the pressure P and the total flow rate C are constant, the value of the output signal Ir of the FTIR 40 increases in proportion to this. Further, when the pressure P increases under the condition that the values of the source gas flow rate S and the output signal Ir of the FTIR 40 are constant, the total flow rate C increases in proportion thereto. If the source gas flow rate S increases under the condition that the value of the output signal Ir of the FTIR 40 and the pressure P are constant, the total flow rate C increases in proportion to this.

When the above equation (1) is transformed,
S / C = A × Ir × (1 / P) (2)
However, the term S / C on the left side is nothing but the absolute concentration of the source gas in the mixed gas introduced into the processing container 100.

  When the measurement of the pressure P by the pressure gauge 18A and the measurement of the absorption spectrum intensity Ir by the FTIR 40 are performed on the downstream side of the junction P1, the above equation (2) is obtained from the FTIR output value Ir and the pressure value P. This means that the absolute concentration of the source gas in the mixed gas supplied to the processing vessel 100 can be calculated.

  Therefore, in step 302 in the flowchart of FIG. 6, the absolute concentration of the source gas is determined in advance by using the absolute concentration obtained in this way when the control device 201 controls the mass flow rate control devices 12A and 12B. It becomes possible to control to the value. This means that the original deposition conditions can be reliably reproduced even when the gas supply is resumed after another series of film forming processes is completed and another series of film forming processes is performed. Yes.

  In equation (2), the coefficient A is a constant unique to the apparatus, but this has a dimension of pressure and can be obtained by experiment.

  In the present embodiment, the position of the pressure gauge 18A is not limited to the position shown in FIG. 8 because it is sufficient if the pressure of the mixed gas whose concentration is measured can be measured. For example, as shown in FIG. It can also be provided immediately before or after the FTIR 40.

  Further, in the present embodiment, since the absolute concentration of the source gas can be measured by the FTIR 40, it is not always necessary to measure the concentration of the source gas downstream from the point P1, and as shown in FIG. It can also be done on the side. In this case, the pressure measurement can be performed by the pressure gauge 18 provided in the pipe 30, and there is no need to provide an additional pressure gauge.

[Modification]
Similarly, as shown in the MOCVD apparatus 200E of FIG. 11, the absolute concentration of the source gas in the raw material supply line 30 can be obtained by adding a pressure gauge 18A based on the MOCVD apparatus 200A of FIG. . In FIG. 11, the parts described above are denoted by the same reference numerals, and description thereof is omitted.

  Also, the MOCVD apparatus 200E in FIG. 11 can be modified in the same manner as in FIGS.

  Further, as shown in the MOCVD apparatus 200F of FIG. 12, the absolute concentration of the source gas in the raw material supply line 30 can be obtained by adding a pressure gauge 18A based on the MOCVD apparatus 200B of FIG. In FIG. 12, the parts described above are denoted by the same reference numerals, and description thereof is omitted.

  The MOCVD apparatus 200F in FIG. 12 can be modified in the same manner as in FIGS.

  Further, as shown in the MOCVD apparatus 200G of FIG. 13, the absolute concentration of the source gas in the raw material supply line 30 can be obtained by adding a pressure gauge 18A based on the MOCVD apparatus 200C of FIG. In FIG. 13, the parts described above are denoted by the same reference numerals, and description thereof is omitted.

  The MOCVD apparatus 200G in FIG. 13 can be modified in the same manner as in FIGS.

[Sixth Embodiment]
FIG. 14 shows the configuration of the FTIR 40 used in each of the above embodiments.

  Referring to FIG. 14, the FTIR 40 includes a gas passage 401 having optical windows 401A and 401B, mirrors 401a to 401c formed in the gas passage, and multiple-reflecting a light beam incident from the optical window 401A, And a detector 402 that detects a light beam reflected by the mirror 401c and emitted through the optical window 401B. Further, a fixed mirror 403a, a movable mirror 403b, and a translucent mirror 403c are provided outside the optical window 401A. An interferometer 403 is formed. The interferometer 403 introduces the light beam from the infrared light source 404 into the gas passage 401 through the optical window 401A.

  The output signal of the detector 402 is converted into a digital signal by an A / D converter 402A and then fast Fourier transformed by a computer 402B. For example, as shown in FIG. 7, the gas passing through the gas passage 401 is converted. A spectrum is calculated.

  In the FTIR 40 of FIG. 14, the movable mirror 403b is moved while detecting the incoming infrared light intensity at the detector 402 to change the baseline length of the interferometer 403, thereby obtaining an interference pattern. An infrared spectrum of the source gas is obtained by fast Fourier transforming the interference pattern obtained in this way in the computer 402B.

  In the configuration of FIG. 14, the light from the light source 404 repeatedly reciprocates due to multiple reflection in the gas flow flowing in the gas passage 401, thereby ensuring a long effective optical path in the gas flow.

  In this embodiment, the mirrors 401a and 401c are held on a base 401C, and the mirror 401b is held on a base 401D. The base 401C includes a temperature sensor 401CT such as a thermocouple. And heaters 401CB and 401CD are incorporated. A temperature sensor 401DT and a heater 401DB are also incorporated in the base 401D that holds the mirror 401b. Further, although not shown, temperature sensors and heaters are also incorporated in the optical windows 401A and 401B.

  By maintaining the mirror in direct contact with the gas flow at a predetermined temperature in this way, the raw material gas that needs to be maintained at a high temperature is cooled when passing through the FTIR 40, thereby avoiding problems such as the generation of precipitates. Can do.

  In each of the above embodiments, instead of the FTIR 40, for example, as shown in FIG. 16, a non-dispersive infrared spectrometer (NDIR) 50 shown in FIG. 15 can be used. An output signal can be obtained at a speed of 1 second or less. However, in FIG. 15, the same reference numerals are given to the parts described above, and the description thereof is omitted. The non-dispersive infrared spectrum measuring apparatus 50 has a configuration similar to that of the FTIR 40 of FIG. 14, but is configured such that infrared light from the light source 404 is interrupted by the chopper 404A, and the optical interferometer 403 The computer 402B that performs the fast Fourier transform is omitted. The chopper 404A may be provided anywhere in the optical path of the infrared light beam from the light source 404 to the detector 402.

  Also in the measuring apparatus 50 of FIG. 15, the mirrors 401a to 401c that are in direct contact with the gas flow are maintained at a predetermined temperature, and the problem of precipitate generation is avoided.

  The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to the above-described embodiments, and various modifications and substitutions can be made to the above-described embodiments without departing from the scope of the present invention. Can be added. For example, in the above-described embodiment, only the dry pump 16 is provided in the preflow line 33. However, a turbo molecular pump is provided in the preflow line 33 in accordance with a film forming process using a low vapor pressure raw material. May be newly provided, and the pipe diameter of the preflow line 33 may be further adjusted. As a result, the FTIR 40 of the preflow line 33 can measure the concentration of the source gas under conditions very close to the case of flowing through the raw material supply line 30 during film formation.

  In each of the above embodiments, the source gas concentration is detected by measuring FTIR or infrared absorption spectrum. However, this can be performed by other methods. For example, when film formation is performed in a region where the process pressure is sufficiently high, since the high source gas pressure is used, the AE method described above can be used. Also in this case, the absolute concentration of the source gas can be calculated by applying pressure correction to the detected sound wave signal intensity according to the equation (2).

  While the present invention has been described with reference to the preferred embodiments, the present invention is not limited to such specific embodiments, and various modifications and changes can be made within the scope of the claims.

2 is a cross-sectional view schematically showing a configuration of a processing container 100. FIG. 1 is a diagram schematically showing the configuration of an MOCVD apparatus according to a first embodiment of the present invention. It is a figure which shows roughly the structure of the MOCVD apparatus by the 2nd Embodiment of this invention. It is a figure which shows schematically the structure of the MOCVD apparatus by the 3rd Embodiment of this invention. It is a figure which shows roughly the structure of the MOCVD apparatus by the 4th Embodiment of this invention. It is a flowchart which shows an example of the process for controlling the density | concentration of the source gas in mixed gas. It is a figure which shows the infrared absorption spectrum of W (CO) ₆ as a measurement result by FTIR. It is a figure which shows the structure of the MOCVD apparatus by the 5th Embodiment of this invention. It is a figure which shows the structure of the MOCVD apparatus by the modification of FIG. It is a figure which shows the structure of the MOCVD apparatus by the modification of FIG. It is a figure which shows the structure of the MOCVD apparatus by the other modification of this invention. It is a figure which shows the structure of the MOCVD apparatus by the other modification of this invention. It is a figure which shows the structure of the MOCVD apparatus by the other modification of this invention. It is a figure which shows the structure of the FTIR apparatus by the 6th Embodiment of this invention. It is a figure which shows the structure of the non-dispersion type | mold infrared spectroscopy analyzer by the 6th Embodiment of this invention. It is a figure which shows the structure of the MOCVD apparatus by the other modification of this invention.

Explanation of symbols

10 Raw material container 12A Mass flow controller (MFC)
12B Mass flow controller (MFC)
14 Turbo molecular pump (TMP)
16 Dry pump (DP)
18, 18A Pressure gauge 20 Valve 21 Valve 23 Valve 25 Valve 26 Valve 30 Raw material supply line 31 Dilution gas line 32 Exhaust line 33 Preflow line 35 Bypass line 40 Fourier transform infrared spectrophotometer (FTIR)
40A non-dispersive infrared spectrophotometer (NDIR)
50
DESCRIPTION OF SYMBOLS 100 Film-forming apparatus 110 Shower head 120 Processing container main body 130 Mounting stand 140 Gate valve 200 Raw material supply apparatus 201 Control apparatus 401 Gas passage 401A, 401B Optical window 401C Base 401a-401c Mirror 401CA, 401CB, 401DB Heater 401CT, 401DT Thermocouple 402 Detector 404 Light source

Claims (10)

A film forming apparatus provided with a raw material supply device for conveying a source gas generated from a solid or liquid raw material to a film forming chamber by a carrier gas,
The raw material supply device includes a concentration measuring means for measuring the concentration of the source gas,
An inert gas mass flow rate control means for increasing or decreasing the flow rate of the inert gas added to the carrier gas that is transporting the source gas based on the measured concentration of the source gas,
The inert gas mass flow rate control means increases the flow rate of the inert gas when the measured concentration exceeds the upper limit value of the concentration range appropriate for the film forming process, and the measured concentration is within the appropriate concentration range. When the value falls below the lower limit of the above, the film forming apparatus is characterized in that control for reducing the flow rate of the inert gas is performed to correct deviation of the source gas concentration from the appropriate concentration range.   The film forming apparatus according to claim 1, wherein the concentration measuring unit is arranged to measure a concentration of the source gas after the inert gas is added to the carrier gas.   The film forming apparatus according to claim 1, wherein the concentration measuring unit is arranged to measure a concentration of the source gas before film formation and / or during film formation. In the raw material supply device, the flow path through which the carrier gas with the inert gas added flows is a first flow path leading to the film formation chamber or a second flow path bypassing the film formation chamber. And further includes switching means for selectively switching,
The film forming apparatus according to claim 1, wherein the concentration measuring unit is disposed in either the first flow path or the second flow path.   The inert gas mass flow rate control means increases or decreases the flow rate of the inert gas added to the carrier gas, and the flow rate of the carrier gas so that the flow rate of the carrier gas containing the inert gas becomes substantially constant. The film forming apparatus according to claim 1, wherein the film forming device is increased or decreased.   The carrier gas and the inert gas are introduced from the same flow path, and the inert gas is diverted to another flow path before the carrier gas conveys the source gas, and the carrier gas is The film forming apparatus according to claim 1, wherein the film is merged with a flow path of the carrier gas after the source gas is conveyed.   The film forming apparatus according to claim 6, wherein the inert gas mass flow rate control unit controls a flow rate divided into the another flow path. The film forming apparatus according to claim 1, wherein the source gas is W (CO) ₆ .   The film forming apparatus according to claim 1, wherein the concentration measuring unit is a Fourier transform infrared spectrophotometer.   The raw material supply apparatus with which the film-forming apparatus as described in any one of Claims 1 thru | or 9 is provided.

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