JP5408085B2 - Silicon epitaxial wafer manufacturing system and silicon epitaxial wafer manufacturing method - Google Patents

Description

  The present invention relates to a silicon epitaxial wafer manufacturing system and a silicon epitaxial wafer manufacturing method.

  From the viewpoint of manufacturing a semiconductor element, a silicon epitaxial wafer can form an electrically active layer having a resistivity different from that of a substrate, so that the degree of freedom in designing a semiconductor element is large, and crystal defects Since there are many advantages such as the ability to form a high-purity single crystal thin film with a low concentration of oxygen and carbon, which has an arbitrary thickness, high voltage semiconductor elements, integrated circuit elements, solid-state imaging elements (CCD <Charge-Coupled) Device>, CIS <CMOS Image Sensor>) and the like.

As a general method for forming an epitaxial layer, for example, a CVD (Chemical Vapor Deposition method) is used, and a raw material mixed gas obtained by diluting the following four main silicon source gases with hydrogen gas is used. That is, in the hydrogen reduction method, SiCl ₄ and SiHCl ₃ are used as the silicon source gas, and in the thermal decomposition method, SiH ₂ Cl ₂ and SiH ₄ are used as the silicon source gas.

  In general, a silicon epitaxial growth apparatus is designed on the assumption that a raw material mixed gas having a constant concentration is supplied. Therefore, if there is a concentration variation in the raw material mixed gas supplied to the silicon epitaxial growth device, the silicon epitaxial growth device is directly connected to the film thickness variation. It greatly affects the characteristics of the epitaxial layer grown in phase, particularly the resistance value. Therefore, in order to make the film thickness of the epitaxial film constant, it is extremely important to make the concentration of the raw material mixed gas supplied to the silicon epitaxial growth apparatus constant.

  The hydrogen-trichlorosilane mixed gas, which is the most frequently used raw material mixed gas, is an excess of the trichlorosilane vaporized by bubbling hydrogen gas into the liquid trichlorosilane heated in the vaporizer in the raw material mixed gas supply device. A hydrogen-trichlorosilane mixed gas having a concentration is produced, and then the excess is liquefied and recovered by cooling to a constant temperature with a condenser (condenser) in a concentrated trichlorosilane supply apparatus.

  The hydrogen-trichlorosilane mixed gas generated in this way is supplied to the reaction chamber in the silicon epitaxial growth apparatus. In this raw material mixed gas supply device, there are an individual supply method in which a small raw material mixed gas supply device is provided for each silicon epitaxial growth device, and a concentrated supply method in which a large raw material mixed gas supply device is distributed to reaction chambers of a plurality of silicon epitaxial growth devices. is there. The concentrated supply system is highly stable in the concentration of the raw material mixed gas supplied to the silicon epitaxial growth apparatus.

  Since the concentration of the raw material mixed gas produced is determined by the condenser temperature in the raw material mixed gas supply device, attention is usually paid to make the condenser cooling water temperature as constant as possible using feedback control, etc. Such a system also has some disturbance, and is affected by, for example, fluctuations in the temperature of day and night, so it is difficult to continue supplying a raw material mixed gas having a completely constant concentration. For this reason, even with the concentrated supply method, slight fluctuations in the concentration of the source gas are inevitable, resulting in fluctuations in the thickness of the epitaxial layer that is vapor-phase grown, which greatly affects the characteristics of the silicon epitaxial wafer, particularly the resistance value. Giving was a problem. On the other hand, it has been desired to develop a silicon epitaxial wafer manufacturing system and a silicon epitaxial wafer manufacturing method capable of supplying the raw material mixed gas so that the film thickness does not change even when the concentration of the raw material mixed gas varies.

  As a method for solving this problem, a method is known in which the amount of source gas used is adjusted according to the concentration of the source mixed gas supplied to the silicon epitaxial growth apparatus (Cited Document 1). In this method, a process program created assuming an ideal concentration of hydrogen-trichlorosilane mixed gas is used. This method measures the concentration of the actual trichlorosilane in the hydrogen-trichlorosilane mixed gas actually generated in the supply apparatus before executing each epitaxial step, and modifies the program based on the measured value. In this method, the amount of trichlorosilane supplied is optimized. However, in this method, since the correction is performed before the epitaxial process, when the concentration of trichlorosilane varies during execution of the process program, the concentration of trichlorosilane after the variation cannot be dealt with. Therefore, when the concentration of trichlorosilane fluctuates during execution of the process program, there is a problem that the film thickness fluctuates. In fact, the concentration of the trichlorosilane is constantly changing throughout the day because the temperature of the condenser in the feeder is influenced by the outside air temperature, and the concentration of trichlorosilane can vary during the execution of the process program. . Therefore, such a method has not led to a fundamental solution of the above problem.

JP-A-7-193014

  The present invention has been made in view of the above-described problems, and even when the epitaxial process program is being executed, the concentration value of the silicon source gas measured by the concentration value measuring device, or a correction value calculated from the concentration value. A silicon epitaxial wafer manufacturing system and a silicon epitaxial wafer manufacturing system capable of correcting the amount of the raw material mixed gas supplied to the reaction chamber of the silicon epitaxial growth apparatus based on the above and supplying a constant amount of silicon source gas to the reaction chamber of the silicon epitaxial growth apparatus. It aims to provide a method.

In order to achieve the above object, in the present invention,
A silicon epitaxial wafer manufacturing system comprising at least a plurality of silicon epitaxial growth apparatuses and a raw material mixed gas concentration supply apparatus for supplying a raw material mixed gas composed of a silicon raw material gas diluted with hydrogen gas to each of the silicon epitaxial growth apparatuses. ,
A concentration value measuring device that constantly measures the concentration value of the silicon source gas in the source mixed gas generated by the source mixed gas concentration supply device;
Transmitting means for transmitting the concentration value, or a correction value calculated from the concentration value, to each of the silicon epitaxial growth apparatuses by a digital signal;
A silicon epitaxial wafer comprising: a flow rate control device for correcting the amount of the raw material mixed gas supplied to the reaction chamber in the silicon epitaxial growth apparatus as needed based on the concentration value or the correction value. Provide a manufacturing system.

  Thus, a silicon epitaxial wafer manufacturing system comprising a plurality of silicon epitaxial growth apparatuses and a raw material mixed gas concentrated supply apparatus, wherein the silicon raw material gas in the raw material mixed gas generated by the raw material mixed gas concentrated supply apparatus A concentration value measuring device that constantly measures a concentration value; a transmission means that transmits the concentration value or a correction value calculated from the concentration value to each silicon epitaxial growth device as a digital signal; and the concentration value or the correction value. Based on the above, if the silicon epitaxial wafer manufacturing system includes the flow rate control device that corrects the amount of the raw material mixed gas supplied to the reaction chamber in the silicon epitaxial growth device as needed, the concentration value even during the epitaxial growth step Concentration of silicon source gas constantly measured by the measuring device Or silicon capable of correcting the amount of the raw material mixed gas supplied to the reaction chamber of the silicon epitaxial growth apparatus at any time based on the correction value calculated from the concentration value, and supplying a certain amount of silicon source gas to the reaction chamber of the silicon epitaxial growth apparatus An epitaxial wafer manufacturing system can be provided.

  The silicon epitaxial wafer manufacturing system according to the present invention preferably includes a plurality of the concentration value measuring devices.

  Thus, in the case of a silicon epitaxial wafer manufacturing system having a plurality of concentration value measuring devices, even if one concentration value measuring device fails, the other concentration value measuring device operates normally, so that the reliability is higher. It becomes a silicon epitaxial wafer manufacturing system. In addition, when one concentration value measuring device fails, the measured value differs between the failed concentration value measuring device and other concentration value measuring devices that operate normally. It becomes a silicon epitaxial wafer manufacturing system that can be understood immediately.

  Furthermore, it is preferable that the plurality of concentration value measuring devices provided in the silicon epitaxial wafer manufacturing system according to the present invention have concentration value measuring devices based on different measurement principles.

  In this way, if the silicon epitaxial wafer manufacturing system is equipped with concentration value measuring devices based on different measurement principles, it is possible to prevent all concentration value measuring devices from failing due to the same cause. The measured concentration value is highly reliable. In addition, when one concentration value measuring device fails, the measured value differs between the failed concentration value measuring device and other concentration value measuring devices that operate normally. It becomes a silicon epitaxial wafer manufacturing system that can be understood immediately.

  In addition, the silicon epitaxial wafer manufacturing system according to the present invention preferably includes a recording apparatus that records the concentration value or the correction value on a recording medium automatically or manually.

  As described above, if the silicon epitaxial wafer manufacturing system includes a recording apparatus that automatically or manually records the density value or the correction value on a recording medium, it can be provided for a failure of the system.

  Furthermore, the silicon epitaxial wafer manufacturing system according to the present invention provides a recording medium that automatically or manually records the supply amount of the raw material mixed gas corrected by the flow rate control device and the supply amount of the raw material mixed gas before the correction. It is preferable to have a recording device for recording in the above.

  As described above, the silicon epitaxial wafer having the recording apparatus for automatically or manually recording the supply amount of the raw material mixed gas corrected by the flow rate control device and the supply amount of the raw material mixed gas before the correction onto the recording medium. If it is a manufacturing system, it can be prepared for a failure of the system.

  In the silicon epitaxial wafer manufacturing system according to the present invention, the silicon source gas is preferably trichlorosilane.

  Thus, if the silicon source gas is trichlorosilane, a silicon epitaxial wafer manufacturing system in which the film thickness of the manufactured epitaxial film is less likely to fluctuate.

In order to achieve the above object, in the present invention,
A silicon epitaxial wafer manufacturing method using a plurality of silicon epitaxial growth apparatuses and a raw material mixed gas concentration supply apparatus for supplying a raw material mixed gas composed of a silicon raw material gas diluted with hydrogen gas to each of the silicon epitaxial growth apparatuses,
While constantly measuring the concentration value of the silicon source gas in the source mixed gas generated by the source mixed gas supply device using a concentration value measuring device,
The concentration value, or a correction value calculated from the concentration value is transmitted to each silicon epitaxial growth apparatus using a transmission means as a digital signal,
A silicon epitaxial wafer manufacturing method characterized in that, based on the concentration value or the correction value, the amount of the raw material mixed gas supplied to the reaction chamber in the silicon epitaxial growth apparatus is corrected at any time using a flow control device. provide.

  Thus, a silicon epitaxial wafer manufacturing method using a plurality of silicon epitaxial growth apparatuses and a raw material mixed gas concentration supply apparatus for supplying a raw material mixed gas composed of a silicon raw material gas diluted with hydrogen gas to each silicon epitaxial growth apparatus The concentration value of the silicon raw material gas in the raw material mixed gas generated by the raw material mixed gas supply device is constantly measured using a concentration value measuring device, and is calculated from the concentration value or the concentration value. The corrected value is transmitted as a digital signal to each silicon epitaxial growth apparatus using a transmission means, and the amount of the raw material mixed gas supplied to the reaction chamber in the silicon epitaxial growth apparatus is determined based on the concentration value or the correction value. Silicon epitaxy, which is corrected at any time using a flow controller If it is a manufacturing method of a wafer, it is supplied to the reaction chamber of the silicon epitaxial growth apparatus based on the concentration value of the silicon source gas that is always measured by the concentration value measuring apparatus or the correction value calculated from the concentration value even during the epitaxial growth process. Thus, it is possible to provide a method for producing a silicon epitaxial wafer in which the amount of the raw material mixed gas is corrected as needed, and a certain amount of silicon raw material gas can be supplied to the reaction chamber of the silicon epitaxial growth apparatus.

  In the method for producing a silicon epitaxial wafer according to the present invention, it is preferable that the concentration value of the silicon source gas in the source mixed gas is constantly measured using a plurality of the concentration value measuring devices.

  Thus, if a silicon epitaxial wafer manufacturing method that constantly measures the concentration value of the silicon source gas in the source mixed gas using a plurality of concentration value measuring devices, even if one concentration value measuring device fails, Since other concentration value measuring devices operate normally, a more reliable method for manufacturing a silicon epitaxial wafer is obtained. In addition, when one concentration value measuring device fails, the measured value differs between the failed concentration value measuring device and other concentration value measuring devices that operate normally. This is a method for producing a silicon epitaxial wafer that can be readily understood.

  Furthermore, in the method for producing a silicon epitaxial wafer according to the present invention, it is preferable that the concentration value of the silicon source gas in the source mixed gas is constantly measured using the plurality of concentration value measuring devices based on different measurement principles.

  As described above, if the silicon epitaxial wafer manufacturing method always measures the concentration value of the silicon source gas in the source mixed gas based on different measurement principles using a plurality of concentration value measuring devices, all the concentration value measurements are performed. It is possible to prevent the apparatus from failing due to the same cause, and the concentration values measured by a plurality of measurement principles are highly reliable. In addition, when one concentration value measuring device fails, the measured value differs between the failed concentration value measuring device and other concentration value measuring devices that operate normally. This is a method for producing a silicon epitaxial wafer that can be readily understood.

  In the method for producing a silicon epitaxial wafer according to the present invention, it is preferable to record the density value or the correction value on a recording medium automatically or manually using a recording apparatus.

  As described above, any method of manufacturing a silicon epitaxial wafer including a recording apparatus that automatically or manually records the density value or the correction value on a recording medium can be prepared for a system failure or the like.

  Furthermore, in the method for producing a silicon epitaxial wafer according to the present invention, the supply amount of the raw material mixed gas corrected by the flow rate control device and the supply amount of the raw material mixed gas before the correction are automatically recorded using a recording device. It is preferable to record on a recording medium manually or manually.

  As described above, the silicon epitaxial wafer having the recording apparatus for automatically or manually recording the supply amount of the raw material mixed gas corrected by the flow rate control device and the supply amount of the raw material mixed gas before the correction onto the recording medium. If this manufacturing method is used, it is possible to prepare for a failure of the system.

  In the method for producing a silicon epitaxial wafer according to the present invention, it is preferable to use trichlorosilane as the silicon source gas.

  As described above, when trichlorosilane is used as the silicon source gas, a method for manufacturing a silicon epitaxial wafer is obtained in which the thickness of the manufactured epitaxial film is less likely to vary.

  As described above, according to the present invention, the concentration value of the silicon raw material gas in the raw material mixed gas measured by the concentration value measuring device or the correction value is always calculated during execution of the process program of the epitaxial process. Since the amount of the raw material mixed gas supplied to the reaction chamber of the silicon epitaxial growth apparatus is corrected as needed based on the above, the raw material mixed gas in which the influence of the concentration change of the silicon raw material gas is always suppressed is supplied to the reaction chamber of the silicon epitaxial growth apparatus. In addition, a silicon epitaxial wafer manufacturing system and a silicon epitaxial wafer manufacturing method capable of obtaining an epitaxial wafer with high quality and reliability can be provided.

1 is a conceptual diagram showing an embodiment of a silicon epitaxial wafer manufacturing system according to the present invention. It is a conceptual diagram which shows the conventional silicon epitaxial wafer manufacturing system. It is the figure which showed the change of the daily concentration value of the trichlorosilane in the raw material mixed gas used in Example 1 and Comparative Example 1 as a concentration value on the vertical axis and time on the horizontal axis. The film thickness transition of the epitaxial film manufactured by the silicon epitaxial wafer manufacturing system according to the present invention used in Example 1 is the relative value when the vertical axis represents the average value over a long period of time, and the horizontal axis It is the figure shown as time. The film thickness transition of the epitaxial film manufactured by the conventional silicon epitaxial wafer manufacturing system used in Comparative Example 1 is the relative value when the average value of the film thickness over the long term is 1, and the horizontal axis is time. FIG.

Hereinafter, although an embodiment is described about the present invention, the present invention is not limited to this.
As described above, a silicon epitaxial wafer manufacturing system and silicon that can supply a constant raw material mixed gas so that the thickness of the epitaxial film to be manufactured does not change even if the concentration of the silicon raw material gas in the raw material mixed gas varies. Development of a method for manufacturing an epitaxial wafer has been desired.

As a result of intensive research, the present inventor
In order to supply a constant raw material mixed gas so that the film thickness of the epitaxial film to be manufactured does not fluctuate even if the concentration of the silicon raw material gas in the raw material mixed gas fluctuates, the raw material mixture is first mixed by a concentration value measuring device. It is necessary to constantly measure the concentration value of the silicon source gas in the hydrogen gas generated by the gas concentration supply device to detect concentration fluctuations. In addition, the concentration fluctuations are transmitted as digital signals, and the detected concentration fluctuations are detected. Accordingly, the present inventors have found that the flow rate control device for correcting the amount of the raw material mixed gas supplied to the reaction chamber in the silicon epitaxial growth apparatus as needed is necessary, and reached the present invention. This will be described in detail below.

The present invention
A silicon epitaxial wafer manufacturing system comprising at least a plurality of silicon epitaxial growth apparatuses and a raw material mixed gas concentration supply apparatus for supplying a raw material mixed gas composed of a silicon raw material gas diluted with hydrogen gas to each of the silicon epitaxial growth apparatuses. ,
A concentration value measuring device that constantly measures the concentration value of the silicon source gas in the source mixed gas generated by the source mixed gas concentration supply device;
Transmitting means for transmitting the concentration value, or a correction value calculated from the concentration value, to each of the silicon epitaxial growth apparatuses by a digital signal;
The silicon epitaxial device comprising: the flow rate control device that corrects the amount of the raw material mixed gas supplied to the reaction chamber in the silicon epitaxial growth device as needed based on the concentration value or the correction value. Wafer manufacturing system.

  FIG. 2 shows a schematic diagram of a conventional silicon epitaxial wafer manufacturing system 20. In the conventional silicon epitaxial wafer manufacturing system 20, the raw material mixed gas sent from the raw material mixed gas concentrated supply device 1 is supplied to the reaction chambers 21 c of the silicon epitaxial growth devices 21, 22, 23 through the line 2 and the mass flow controllers 21 b, 22 b, 23 b, 22c and 23c. The mass flow controllers 21b, 22b, and 23b that supply the raw material mixed gas are controlled by the control units 21a, 22a, and 23a that command the supply amount of the standard mixed raw material mixed gas that should flow according to the progress of the epitaxial growth process program. Therefore, there is no mechanism that can cope with the case where the concentration fluctuation of the silicon source gas in the source mixed gas occurs during execution of the process program of the epitaxial process. Therefore, when the concentration fluctuation of the silicon source gas in the source mixed gas occurs during the execution of the process program of the epitaxial process, the amount of silicon source gas supplied to the reaction chambers 21c, 22c, 23c becomes excessive or insufficient. As a result, the film thickness of the epitaxial layer which is vapor-phase grown is changed, which greatly affects the characteristics of the silicon epitaxial wafer, particularly the resistance value.

  On the other hand, FIG. 1 shows a schematic diagram of an embodiment of a silicon epitaxial wafer manufacturing system 10 according to the present invention. In the silicon epitaxial wafer manufacturing system 10 according to the present invention, the raw material mixed gas sent from the raw material mixed gas concentrated supply device 1 is supplied to the reaction chamber of each silicon epitaxial growth device 11, 12, 13 via the line 2 and the mass flow controllers 11b, 12b, 13b. Before being supplied to 11c, 12c, and 13c, the mass flow controllers 11b, 12b, and 13b that supply the raw material mixed gas are controlled by the flow rate control devices 14, 15, and 16. The flow rate control devices 14, 15, 16 are the concentration values or corrections of the silicon raw material gas in the raw material mixed gas produced by the raw material mixed gas concentration supply device 1 obtained by the concentration value measuring devices 18 a, 18 b via the transmission means 17. Value information can always be obtained. Therefore, even if the concentration of the silicon source gas in the source mixed gas varies during execution of the process program for the epitaxial process, the supply amount of the source mixed gas to be actually flowed is changed according to the concentration variation of the silicon source gas. It can be corrected at any time. Therefore, even when the concentration of the silicon raw material gas in the raw material mixed gas varies during execution of the process program of the epitaxial process, the amount of silicon raw material gas supplied to the reaction chambers 11c, 12c, and 13c is a standard value. It can be kept constant in the vicinity, the film thickness fluctuation of the epitaxial layer grown by vapor phase can be prevented, and the characteristics of the silicon epitaxial wafer, in particular, the resistance value can be kept constant. Hereinafter, each device and means constituting the silicon epitaxial wafer manufacturing system according to the present invention will be described.

Concentration value measuring device
The silicon epitaxial wafer manufacturing system 10 according to the present invention includes concentration value measuring devices 18a and 18b. The concentration value measuring devices 18a and 18b are devices that constantly measure the concentration value of the silicon raw material gas in the raw material mixed gas generated by the raw material mixed gas concentration supply device 1. The concentration value measuring devices 18 a and 18 b can be installed at the outlet of the raw material mixed gas concentration supply device 1. It is preferable to install a plurality of density value measuring devices 18a and 18b so that a failure of the density value measuring devices 18a and 18b itself can be detected. That is, since the failed concentration value measuring device shows a concentration value different from other normal concentration value measuring devices, if there are a plurality of concentration value measuring devices 18a and 18b in this way, the measurement of each concentration value measuring device 18a and 18b is performed. By comparing the values, it is possible to identify a concentration value measuring device that is malfunctioning. In addition, if there are a plurality of concentration value measuring devices 18a and 18b in this way, even if one concentration value measuring device fails, the other concentration value measuring device gives a normal concentration value, thus ensuring the redundancy of the entire system. The

  Furthermore, the silicon epitaxial wafer manufacturing system 10 according to the present invention preferably includes concentration value measuring apparatuses 18a and 18b having different measurement principles. Thus, if the measurement principles of the respective density value measuring devices 18a and 18b are different, it is possible to prevent the density value measuring devices 18a and 18b from failing due to the same cause. Moreover, the reliability of a measured value can be ensured by measuring with a different measurement principle. Examples of different measurement principles include a concentration value measuring device based on thermal conductivity, a concentration value measuring device based on sound velocity, and the like.

Means of transmission
The silicon epitaxial wafer manufacturing system according to the present invention includes a transmission means 17. The transmission means 17 for transmitting the concentration value or the correction value calculated from the concentration value to each of the silicon epitaxial growth apparatuses by a digital signal is an input unit 17a for receiving the concentration value from the concentration value measuring apparatuses 18a and 18b. A communication unit 17b for transmitting digital data received by the unit 17a to the silicon epitaxial growth apparatuses 11, 12, and 13 is provided. Furthermore, the transmission means 17 can have a CPU.

  In the CPU of the input unit 17a, for example, after the voltages received from the two density value measuring devices 18a and 18b are converted into density values, respectively, if there is no difference between the two density values, it is determined that both measured values are equal. The “correction value” can be calculated by comparison with the standard density. Here, the “standard concentration” is the concentration of the silicon source gas to be supplied to the reaction chambers 11c, 12c, and 13c of the silicon epitaxial growth apparatuses 11, 12, and 13. At this time, the calculation is performed in consideration of changes in the conversion factor of mass flow controllers (MFC) 11b, 12b, and 13b of the silicon epitaxial growth apparatuses 11, 12, and 13. The concentration value and the calculated correction value are transmitted to the silicon epitaxial growth apparatuses 11, 12, and 13 via the communication unit 17b.

  In addition, if there is a certain difference between the two density values, the CPU of the transmission means 17 determines that one of the density value measuring devices 18a and 18b has failed, and automatically notifies the administrator. can do.

The correction value is a value for correcting the amount of the raw material mixed gas supplied to the reaction chambers 11c, 12c, and 13c in the silicon epitaxial growth apparatuses 11, 12, and 13, and was measured by the concentration value measuring apparatuses 18a and 18b. This is a value calculated based on the concentration value of the silicon source gas in the source mixed gas. For example, the correction value is calculated by the following calculation formula. The “concentration value of the standard silicon source gas” in the following calculation formula is the concentration value of the silicon source gas to be supplied to the reaction chambers 11c, 12c, and 13c of the silicon epitaxial growth apparatuses 11, 12, and 13. The “concentration value of the measured silicon source gas” is the concentration value of the silicon source gas measured by the concentration value measuring devices 18a and 18b. The conversion factor in the following calculation formula is a numerical value representing a change in the flow rate display depending on the gas type of the mass flow controllers 11b, 12b, 13b, and the normal mass flow controllers-11b, 12b, 13b are nitrogen (N ₂ ). Alternatively, calibration is performed with a conversion factor of 1 for argon (Ar ₂ ).
Correction value = (concentration value of measured silicon source gas × conversion factor at the measured concentration value of silicon source gas) / (concentration value of standard silicon source gas × conversion factor at concentration value of standard silicon source gas)

  As the transmission means 17, it is preferable to use an assembly type PLC (Power Line Communication). PLC is a technology that uses a power line as a communication line. Since electrical wiring is stretched around the building, it is possible to construct a local communication network by using a PLC without newly laying cables or the like. When the assembly type PLC is used, the communication unit 17b is an electric wiring stretched around the building. Since the assembly type PLC has units having various functions, the input unit 17a can be selected according to the output method of the concentration value measuring apparatuses 18a and 18b. For example, when the concentration value measuring device based on the thermal conductivity, the concentration value measuring device based on the sound velocity, etc. output the measurement result as a voltage, the transmission means 17 having the assembly type PLC is adapted to this output method. An input unit 17a can be included. In addition, various protocols are prepared for the method of transmitting the digitized density value or the correction value in the assembly type PLC, and the protocol of the density value or the correction value transmitted via the communication unit 17b is also available. It is preferable to select the number of silicon epitaxial growth apparatuses 11, 12, and 13 to be connected and the robustness. Further, instead of transmitting the density value itself input to the input unit 17a, it is also possible to perform a necessary calculation by the CPU in the PLC and convert it to the “correction value” before transmission.

Flow control device
The silicon epitaxial wafer manufacturing system 10 according to the present invention includes flow rate control devices 14, 15 and 16. The flow controllers 14, 15, and 16 are instructed by the controllers 11 a, 12 a, and 13 a that instruct the supply amount of the raw material mixed gas having a standard concentration that should flow according to the progress of the epitaxial growth process program, and the controllers 11 a, 12 a, and 13 a The mass flow controller 11b, the supply amount of the raw material mixed gas to be flowed and the supply amount of the raw material mixed gas to be actually flowed corrected based on the concentration value or the "correction value" transmitted by the transmission means 17; 12b and 13b are provided with correctors 11d, 12d and 13d as needed.

The correction units 11d, 12d, and 13d can be a PLC, for example, and can include a CPU. In the CPUs of the correction units 11d, 12d, and 13d, the concentration value or the correction value received from the communication unit 17b of the transmission unit 17 and the supply amount of the raw material mixed gas having the standard concentration received from the control units 11a, 12a, and 13a are supplied Based on this, it is possible to calculate the supply amount of the raw material mixed gas that should actually flow into the reaction chambers 11c, 12c, and 13c of the silicon epitaxial growth apparatuses 11, 12, and 13. Examples of the calculation method include the following formula. The supply amount of the raw material mixed gas to be actually flown calculated in this way is output from the analog output unit of the flow controllers 14, 15, 16 to the mass flow controllers 11 b, 12 b, 13 b, so that the silicon raw material gas in the raw material mixed gas The flow rate correction according to the concentration of can be realized.
Supply amount of raw material mixed gas to be actually flown = Supply amount of raw material mixed gas of standard concentration to be flown × correction value

Recording device
The silicon epitaxial wafer manufacturing system according to the present invention can include recording devices 19a and 19b. It is preferable that the recording device 19a can record the density value or the correction value automatically or manually. Moreover, it is preferable that the recording device 19b can record the supply amount of the raw material mixed gas having the standard concentration to be flowed automatically or manually and the calculated supply amount of the raw material mixed gas to be actually flowed. Thus, it is possible to avoid losing each data even in the case of a system failure or the like. An example of the recording medium is a flash memory. The recording method can be performed automatically or manually, for example, can be set to automatically record every 5 minutes, and the concentration value, the correction value, the supply amount of the raw material mixed gas of the standard concentration to be flowed, and It can also be set to automatically record when the calculated supply amount of the raw material gas mixture to flow actually falls below a certain threshold value.

  The recording devices 19a and 19b can be installed in, for example, the input unit 17a and the correction units 11d, 12d, and 13d.

Silicon source gas
The silicon source gas may be a silicon source gas used in a general epitaxial layer forming method, and examples thereof include SiCl ₄ , SiHCl ₃ , SiH ₂ Cl ₂ , and SiH ₄ , and trichlorosilane is particularly preferable. . If the silicon source gas is trichlorosilane, a silicon epitaxial wafer manufacturing system in which the film thickness of the manufactured epitaxial film is less likely to fluctuate.

The present invention also provides:
A silicon epitaxial wafer manufacturing method using a plurality of silicon epitaxial growth apparatuses and a raw material mixed gas concentration supply apparatus for supplying a raw material mixed gas composed of a silicon raw material gas diluted with hydrogen gas to each of the silicon epitaxial growth apparatuses,
While constantly measuring the concentration value of the silicon source gas in the source mixed gas generated by the source mixed gas supply device using a concentration value measuring device,
The concentration value, or a correction value calculated from the concentration value is transmitted to each silicon epitaxial growth apparatus using a transmission means as a digital signal,
A silicon epitaxial wafer manufacturing method characterized in that, based on the concentration value or the correction value, the amount of the raw material mixed gas supplied to the reaction chamber in the silicon epitaxial growth apparatus is corrected at any time using a flow control device. provide.

  An embodiment of the method for producing a silicon epitaxial wafer according to the present invention will be described using each apparatus described above. However, the present invention is not limited to this.

  A method for manufacturing a silicon epitaxial wafer according to the present invention described below will be described with reference to the aforementioned schematic diagram 1. First, two types of concentration sensors having different measurement principles are attached as concentration value measuring devices 18a and 18b to the raw material mixed gas discharge port of the raw material mixed gas supply device 1 (concentration sensors 1 and 2). One device is a concentration value measuring device based on thermal conductivity, and the other device is a concentration value measuring device based on sound velocity. Since the concentration value of the silicon source gas in the source gas mixture generated by the source gas mixture supply device 1 is always measured using the concentration value measuring devices 18a and 18b, both output the measurement results as voltage. An analog input unit is attached to the CPU unit of the PLC (input unit 17a) which is the unit 17a, and the output voltages from the two types of concentration value measuring devices 18a and 18b are taken into the PLC (input unit 17a) as digital data.

In the PLC (input unit 17a), after the output voltages from the two types of concentration value measuring devices are converted into concentration values, respectively, it is determined that both measured values are equal if there is no difference between the two concentration values. The “correction value” is calculated by the following formula. At this time, the calculation is performed in consideration of the change in the conversion factor of the mass flow controllers 11b, 12b, and 13b of the silicon epitaxial growth apparatuses 11, 12, and 13. The calculated concentration value and the correction value are transmitted from the communication unit 17b so that the concentration value or the correction value calculated from the concentration value is transmitted as a digital signal to each of the silicon epitaxial growth apparatuses 11, 12, and 13 using the transmission means 17. To the PLCs (correcting units 11d, 12d, and 13d) of the flow rate control devices 14, 15, and 16. At the same time, recording is automatically performed every 5 minutes in a flash memory (recording device 19a) connected to the PLC (input unit 17a). If there is a difference between the two measured values above a certain level, it is determined that one of the density sensors 1 and 2 is out of order, and the administrator is automatically notified.
Correction value = (concentration value of measured silicon source gas × conversion factor of measured silicon source gas concentration) / (concentration value of standard silicon source gas × concentration value of standard silicon source gas)

  The silicon epitaxial growth apparatus 11, 12, 13 side PLC (correcting units 11d, 12d, 13d) receives the concentration value and the correction value sent from the concentration sensor 1, 2 side PLC (input unit 17a). The supply amount of the raw material mixed gas having the standard concentration sent from the control units 11a, 12a, and 13a of the flow rate control devices 14, 15, and 16 is received as a voltage value. Based on the concentration value and the correction value, the amount of the raw material mixed gas supplied to the reaction chambers 11c, 12c, and 13c in the silicon epitaxial growth apparatuses 11, 12, and 13 is corrected as needed using the flow rate control devices 14, 15, and 16. Thus, a value obtained by multiplying the voltage value by the correction value (a supply amount of the raw material mixed gas to be actually flowed) is sent from the analog output unit of the PLC (correction unit 11d, 12d, 13d) to the mass flow controllers 11b, 12b, 13b. Output at any time. Accordingly, it is possible to correct the supply amount according to the concentration of the silicon source gas in the source mixed gas generated by the source mixed gas supply device 1 as needed.

  Further, when information from the PLC (input unit 17a) on the density sensors 1 and 2 side to the PLC (correction units 11d, 12d, 13d) is interrupted, the PLC (correction units 11d, 12d, 13d) uses a correction value received and continues correction as needed and automatically notifies the administrator that there is a problem.

  Further, the PLCs (correcting units 11d, 12d, 13d) on the silicon epitaxial growth apparatus 11, 12, 13 side sent to the mass flow controllers 11b, 12b, 13b to instruct the supply amount of the raw material mixed gas to be actually flowed. While the voltage exceeds a certain threshold, it is determined that epitaxial growth is in progress, and during this time, the concentration value, the correction value, the supply amount of the raw material mixture gas at the standard concentration to be flowed, and the supply amount of the raw material mixture gas to be actually flowed And the average value is automatically recorded in the flash memory (recording device 19b) connected to the PLC (correction unit 11d, 12d, 13d) when it falls below the threshold.

The silicon source gas used as the silicon source gas may be a silicon source gas used in a general epitaxial layer forming method, and examples thereof include SiCl ₄ , SiHCl ₃ , SiH ₂ Cl ₂ , and SiH _4. In particular, it is preferable to use trichlorosilane. If trichlorosilane is used as the silicon source gas, a method for producing a silicon epitaxial wafer in which the film thickness of the produced epitaxial film is less likely to vary will be obtained.

  According to the embodiment described above, the silicon epitaxial wafer manufacturing method according to the present invention causes the concentration fluctuation even when the concentration of the silicon raw material gas in the raw material mixed gas generated by the raw material mixed gas concentration supply device 1 fluctuates. Accordingly, the amount of the raw material mixed gas to be actually flowed can be controlled, so that the amount of the silicon raw material gas supplied to the reaction chamber can be kept constant near the standard value, and the vapor-phase grown epitaxial layer Thus, the silicon epitaxial wafer manufacturing method can prevent the fluctuation of the film thickness and keep the characteristics, particularly the resistance value, of the silicon epitaxial wafer constant.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated more concretely, this invention is not limited to the following Example.

Example 1
The outline of the silicon epitaxial wafer manufacturing system used in Example 1 coincides with the above-described schematic diagram 1. First, two types of concentration sensors having different measurement principles as concentration value measuring devices 18a and 18b were attached to the raw material mixed gas discharge port of the raw material mixed gas supply apparatus 1 (concentration sensors 1 and 2). One is a concentration value measuring device based on thermal conductivity, and the other is a concentration value measuring device based on the speed of sound. While constantly measuring the concentration value of trichlorosilane in the hydrogen-trichlorosilane mixed gas (raw material mixed gas) generated by the raw material mixed gas supply device 1 using the concentration value measuring devices 18a and 18b, Therefore, an analog input unit is attached to the CPU unit of the PLC (input unit 17a) which is the input unit 17a, and the output voltages from the two types of concentration value measuring devices 18a and 18b are digitally connected to the PLC (input unit 17a). Imported as data.

In the PLC (input unit 17a), after the output voltages from the two types of concentration value measuring devices are converted into concentration values, if there is no difference between the two concentration values, it is determined that both measured values are equal. The “correction value” is calculated by the equation. At this time, the calculation was performed in consideration of changes in the conversion factors of the mass flow controllers 11b, 12b, and 13b of the silicon epitaxial growth apparatuses 11, 12, and 13. The calculated concentration and the correction value are transmitted via the communication unit 17b so that the concentration value or the correction value calculated from the concentration value is transmitted to each of the silicon epitaxial growth apparatuses 11, 12, and 13 using the transmission means 17 as a digital signal. To the PLCs (correcting units 11d, 12d, and 13d) of the flow rate control devices 14, 15, and 16. At the same time, recording was automatically performed every 5 minutes in a flash memory (recording device 19a) connected to the PLC (input unit a). In addition, when there is a difference between two measured values above a certain level, it is determined that one of the sensors has failed, and the administrator is automatically notified.
Correction value = (Concentration value of measured trichlorosilane × Conversion factor of measured concentration value of trichlorosilane) / (Concentration value of standard trichlorosilane × Conversion factor of concentration value of standard trichlorosilane)

  The silicon epitaxial growth apparatus 11, 12, 13 side PLC (correcting units 11d, 12d, 13d) receives the concentration value and the correction value sent from the concentration sensor 1, 2 side PLC (input unit 17a). The supply amount of the standard-concentration hydrogen-trichlorosilane mixed gas sent from the control units 11a, 12a, and 13a of the flow control devices 14, 15, and 16 is received as a voltage value. Based on the concentration value and the correction value, the amount of the hydrogen-trichlorosilane mixed gas supplied to the reaction chambers 11 c, 12 c, 13 c in the silicon epitaxial growth apparatuses 11, 12, 13 is used using flow rate controllers 14, 15, 16. Then, a value obtained by multiplying this voltage value by the correction value (amount of hydrogen-trichlorosilane mixed gas to be actually supplied) is supplied from the analog output unit of the PLC (correction unit 11d, 12d, 13d) to the mass flow controller. Output to 11b, 12b, 13b as needed. As a result, the supply amount corresponding to the concentration of trichlorosilane in the hydrogen-trichlorosilane mixed gas was corrected as needed.

  Further, when information from the PLC (input unit 17a) on the density sensors 1 and 2 side to the PLC (correction units 11d, 12d, 13d) is interrupted, the PLC (correction units 11d, 12d, 13d) immediately before the information is interrupted. ) Is used to continue corrections as needed and automatically notify the administrator that there is a problem.

  Further, the PLCs (correcting units 11d, 12d, 13d) on the silicon epitaxial growth apparatuses 11, 12, 13 side instruct the mass flow controllers 11b, 12b, 13b to supply the hydrogen-trichlorosilane mixed gas to be actually supplied. It is determined that epitaxial growth is in progress while the voltage sent to the voltage exceeds a certain threshold value. During this period, the concentration value, the correction value, the supply amount of the standard concentration hydrogen-trichlorosilane mixed gas to be flowed, and the actual flow should be flowed. The supply amount of the hydrogen-trichlorosilane mixed gas is averaged, and the average value is automatically recorded in the flash memory (recording device 19b) connected to the PLC (correction unit 11d, 12d, 13d) when the amount falls below the threshold value. I did it.

(Comparative Example 1)
The outline of the silicon epitaxial wafer manufacturing system used in Comparative Example 1 is the same as the above-described schematic diagram 2. The hydrogen-trichlorosilane mixed gas sent from the raw material mixed gas concentrated supply device 1 is supplied to the reaction chambers 21c, 22c, 23c of the silicon epitaxial growth devices 21, 22, 23. The mass flow controllers 21b, 22b, and 23b for supplying the hydrogen-trichlorosilane mixed gas are controlled by the control units 21a, 22a, and 23a for instructing the supply amount of the standard-concentration hydrogen-trichlorosilane mixed gas to flow according to the progress of the epitaxial growth process program. Be controlled. Accordingly, there is no concentration value measuring device 18a, 18b, transmission means 17, and flow rate control devices 14, 15, 16 for measuring the concentration value of trichlorosilane in the hydrogen-trichlorosilane mixed gas in the present invention, and hydrogen-trichlorosilane mixing. There is no mechanism that can correct the amount of the hydrogen-trichlorosilane mixed gas supplied to the reaction chambers 21c, 22c, and 23c in the silicon epitaxial growth apparatuses 21, 22, and 23 in response to fluctuations in the concentration of trichlorosilane in the gas.

  FIG. 3 is a graph in which the change in the daily concentration value of trichlorosilane in the hydrogen-trichlorosilane mixed gas used in Example 1 and Comparative Example 1 is plotted with the vertical axis representing the concentration value change and the horizontal axis representing time. It is shown. It can be seen from FIG. 3 that the concentration of trichlorosilane in the hydrogen-trichlorosilane mixed gas generated by the raw material mixed gas supply apparatus 1 tends to decrease in the daytime when the temperature is high. This is because if the outside air temperature rises, the temperature of the condenser in the raw material mixed gas concentrated supply device 1 also rises, and the concentration of trichlorosilane in the generated hydrogen-trichlorosilane mixed gas is affected. This is because the concentration of trichlorosilane in the generated hydrogen-trichlorosilane mixed gas is determined by the temperature of the condenser in the raw material mixed gas concentration supply apparatus 1, and cooling the condenser as much as possible using normal feedback control or the like. Care is taken to keep the water temperature constant, but it has proved difficult to keep supplying a completely constant concentration of hydrogen-trichlorosilane mixed gas.

  FIG. 5 shows the film thickness transition of the epitaxial film manufactured by the conventional silicon epitaxial wafer manufacturing system used in Comparative Example 1, with the vertical axis representing the relative value when the long-term average value is 1, and the horizontal axis It is the figure which showed as time. Further, FIG. 4 shows the film thickness transition of the epitaxial film manufactured by the silicon epitaxial wafer manufacturing system according to the present invention used in Example 1, and the relative value when the vertical axis indicates the long-term average value of the film thickness as 1. And the horizontal axis represents time. FIG. 5 shows that the film thickness of the epitaxial film tends to be thin during the daytime due to the influence of the change in the concentration of trichlorosilane in the hydrogen-trichlorosilane mixed gas. On the other hand, in FIG. 4, there is no tendency for the film thickness of the epitaxial film to decrease during the day. As a result, the silicon epitaxial wafer manufacturing system 10 according to the present invention can keep the amount of hydrogen-trichlorosilane mixed gas supplied to the reaction chambers 11c, 12c, and 13c constant, and the vapor-phase grown epitaxial layer. It was shown that the film thickness fluctuation can be prevented and the characteristics of the silicon epitaxial wafer, particularly the resistance value, can be kept constant.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has substantially the same configuration as the technical idea described in the claims of the present invention, and any device that exhibits the same function and effect is the present invention. It is included in the technical scope of the invention.

DESCRIPTION OF SYMBOLS 1 ... Raw material mixed gas concentration supply apparatus, 2 ... Line, 11, 12, 13, 21, 22, 23 ... Silicon epitaxial growth apparatus, 11a, 12a, 13a, 21a, 22a, 23a ... Control part, 11b, 12b, 13b, 21b, 22b, 23b ... mass flow controller (MFC), 11c, 12c, 13c, 21c, 22c, 23c ... reaction chamber, 11d, 12d, 13d ... correction unit, 14, 15, 16 ... flow control device, 17 ... transmission means , 17a ... input unit, 17b ... communication unit, 18a, 18b ... concentration value measuring device, 19a, 19b ... recording device.

Claims (8)

A silicon epitaxial wafer manufacturing system comprising a plurality of silicon epitaxial growth apparatuses and a raw material mixed gas concentration supply apparatus for supplying a raw material mixed gas composed of a silicon raw material gas diluted with hydrogen gas to each of the silicon epitaxial growth apparatuses,
A concentration value measuring device that constantly measures the concentration value of the silicon source gas in the source mixed gas generated by the source mixed gas concentration supply device;
Transmitting means for transmitting the concentration value, or a correction value calculated from the concentration value, to each of the silicon epitaxial growth apparatuses by a digital signal;
On the basis of the density value or the correction value state, and are not provided with a flow control device which from time to time correcting the amount of the raw material mixed gas supplied to the reaction chamber of the silicon epi growth apparatus,
A plurality of the concentration value measuring devices,
The plurality of concentration value measuring apparatuses have a concentration value measuring apparatus based on different measurement principles . The silicon epitaxial wafer manufacturing system according to claim 1 , further comprising a recording device that automatically or manually records the density value or the correction value on a recording medium. A recording device that automatically or manually records the supply amount of the raw material mixed gas corrected by the flow rate control device and the supply amount of the raw material mixed gas before the correction to a recording medium; 3. The silicon epitaxial wafer manufacturing system according to claim 1 , wherein the silicon epitaxial wafer manufacturing system is characterized. The silicon epitaxial wafer manufacturing system according to any one of claims 1 to 3 , wherein the silicon source gas is trichlorosilane. A silicon epitaxial wafer manufacturing method using a plurality of silicon epitaxial growth apparatuses and a raw material mixed gas concentration supply apparatus for supplying a raw material mixed gas composed of a silicon raw material gas diluted with hydrogen gas to each of the silicon epitaxial growth apparatuses,
While constantly measuring the concentration value of the silicon source gas in the source mixed gas generated by the source mixed gas supply device using a concentration value measuring device,
The concentration value, or a correction value calculated from the concentration value is transmitted to each silicon epitaxial growth apparatus using a transmission means as a digital signal,
Based on the concentration value or the correction value, the amount of the raw material mixed gas supplied to the reaction chamber in the silicon epitaxial growth apparatus is corrected at any time using a flow control device ,
A method for producing a silicon epitaxial wafer, wherein a plurality of concentration value measuring devices are used to constantly measure the concentration value of silicon source gas in the source mixed gas based on different measurement principles . 6. The method of manufacturing a silicon epitaxial wafer according to claim 5 , wherein the density value or the correction value is recorded on a recording medium automatically or manually using a recording apparatus. The supply amount of the raw material mixed gas corrected by the flow rate control device and the supply amount of the raw material mixed gas before the correction are recorded on a recording medium automatically or manually using a recording device. A method for producing a silicon epitaxial wafer according to claim 5 or 6 . The method for producing a silicon epitaxial wafer according to any one of claims 5 to 7 , wherein trichlorosilane is used as the silicon source gas.

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