JP4155654B2 - Gas mixing supply method and apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention mixes at least two kinds of gases so as to have a set mixing ratio, and supplies a mixed gas having a stable mixing ratio to a desired use point (use place) such as an epitaxial apparatus, for example. The present invention relates to a method and apparatus.
[0002]
[Prior art]
In the field of the semiconductor industry, a semiconductor is frequently processed using a gas. For example, in the manufacturing process of a silicon epitaxial wafer using an epitaxial device, the resistivity of an epitaxial film is controlled. , Hydrogen H ₂ Diborane gas diluted with gas to about 100 ppm (B ₂ H ₆ / H ₂ ) Is widely used as a dopant gas.
[0003]
FIG. 3 shows a general system for supplying diborane gas to an epitaxial apparatus. Hydrogen gas H is used as a dopant gas supply source. ₂ A cylinder 1 filled with diborane gas diluted to 100 ppm with gas is arranged, and the diluted diborane gas in the cylinder 1 is used through a pipe line 2 equipped with necessary elements such as a valve and a filter. ) Epitaxial device (not shown).
[0004]
In the figure, reference numeral 4 denotes a cylinder containing nitrogen gas for purging a necessary portion of the pipe line 2 with nitrogen gas when the diluted diborane gas cylinder 1 is replaced.
[0005]
[Problems to be solved by the invention]
In general, in the production of silicon epitaxial wafers using an epitaxial device, the device is continuously operated over a period of 3 months or 4 months, and the device is temporarily stopped every time this continuous device operating period elapses. Has been taken. When the resistivity of the epitaxial film is controlled using the system shown in FIG. 3, since the diborane gas in the cylinder 1 is a 100 ppm dilute gas that matches the concentration used at the point of use, the consumption per unit time In many cases, the cylinder 1 needs to be replaced relatively frequently during the continuous apparatus operation period.
[0006]
However, the diborane gas of the cylinder 1 has a slight variation in the concentration of diborane gas due to different production lots, and the concentration of the diborane gas changes immediately after the replacement of the cylinder 1, so that there is a problem that the optimum control of the resistivity is hindered. appear.
[0007]
Further, every time the cylinder 1 is replaced, there is a possibility of contamination, which causes a problem in the quality of semiconductor processing.
[0008]
Furthermore, frequent replacement of the cylinder 1 causes a problem that the cost of the cylinder increases and the manufacturing cost increases accordingly.
[0009]
The present invention has been made to solve the above-mentioned problems, and its purpose is to prevent the occurrence of malfunction due to cylinder replacement by avoiding replacement of supply gas cylinders such as diborane gas during the continuous apparatus operation period. An object of the present invention is to provide a gas mixture supply method and apparatus capable of supplying a processing gas having a constant and stable mixture concentration over the entire continuous apparatus operation period.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides means for solving the problems with the following configuration. That is, in the invention of the gas mixing and supplying method, the first gas supplied from the first gas supply source and the second gas supplied from the second gas supply source are mixed by the gas mixer. A gas mixture supply method for supplying a mixed gas of the first gas and the second gas to the use point, wherein the gas supply line from the first and second gas supply sources to the gas mixer is finely adjusted with the coarse mixing line. The first gas and the second gas in an amount suitable for the amount of gas used at the use point are formed using the rough mixing line. The amount of the crude mixed gas supplied to the gas mixer at a ratio is generated, and the first gas and the second gas are used to eliminate the deviation of the rough mixed gas concentration with respect to the set mixed concentration using the fine mixing line. Imposing with a configuration to adjust the gas supply amount It is a means to solve.
[0011]
Further, the first invention of the gas mixing device is the first gas by mixing the first gas supplied from the first gas supply source and the second gas supplied from the second gas supply source. A gas mixer that supplies a mixed gas of the gas and the second gas to the use point, and the gas supply lines from the first and second gas supply sources to the gas mixer are a coarse mixing line and a fine mixing line. A configuration having two lines is used as a means for solving the problem.
[0012]
Further, a second invention of the gas mixture supply apparatus includes a gas amount detection sensor for detecting a use amount of the mixed gas used at a use point in the structure including the configuration of the first invention of the gas mixture supply apparatus. The supply amount of the first gas and the second gas supplied through the rough mixing line with the distribution ratio of the set gas mixture ratio, with the gas use amount detected by the gas amount detection sensor as the gas generation amount set value And a gas mixing control means for performing distribution control so that the mixing amount becomes the gas generation amount set value.
[0013]
Further, a third aspect of the gas mixing and supplying apparatus according to the first aspect includes the configuration of the first or second aspect of the gas mixing and supplying apparatus, and detects a mixed concentration of the mixed gas discharged from the gas mixer. A detection means and a first mixed gas supplied to a gas mixer through a fine mixing line to obtain a deviation of the detected mixture concentration with respect to a set mixture concentration determined by a set gas mixture ratio of the first gas and the second gas and to eliminate the deviation. A configuration provided with gas concentration fine control means for controlling the supply amount of the gas and the second gas serves as means for solving the problem.
[0014]
Further, the fourth invention of the gas mixing and supplying apparatus is provided with the configuration of the third invention of the gas mixing and supplying apparatus, and the mixed concentration detecting means is an infrared absorption type gas concentration detecting sensor. As a means to solve the problem.
[0015]
Further, a fifth aspect of the gas mixing and supplying apparatus according to the present invention is the gas mixing and supplying apparatus having the first, second, third or fourth aspect of the invention, wherein the first gas is a high-concentration dopant gas. The second gas is a pure gas for dilution that dilutes the dopant gas, and is used as a means for solving the problem.
[0016]
In the present invention, the usage amount of the mixed gas at the use point is detected by the gas amount detection sensor. Then, by using the coarse mixing line, the gas mixing control means supplies the gas amount corresponding to the usage amount at the set mixing ratio of the first gas and the second gas, so that it is used at the use point. An appropriate amount of mixed gas is continuously generated by a gas mixer and supplied to a use point.
[0017]
Since the first gas and the second gas are mixed and controlled based on the flow rate, for example, so that the concentration of the mixed gas generated using this rough mixing line becomes the set mixing ratio, It is assumed that a slight deviation occurs in the actual mixture concentration with respect to the set mixture concentration determined by the set mixture ratio.
[0018]
However, in the present invention, the concentration of the mixed gas discharged from the gas mixer is instantaneously detected from moment to moment by the mixture concentration detecting means, and the deviation amount with respect to the set mixture concentration is obtained instantaneously based on this detected value. When the mixed concentration of the first gas is low, the supply amount of the first gas is increased by an amount corresponding to the deviation, and when the mixed concentration of the first gas is high, the supply amount of the second gas is increased The supply amount of the first gas and the second gas is finely adjusted using the fine mixing line so as to increase the amount to eliminate the deviation, and the concentration of the mixed gas discharged from the gas mixer is always set to the set mixing concentration. Stable adjusted and supplied to the point of use.
[0019]
In particular, in the present invention, since the first gas and the second gas are mixed to generate and supply a mixed gas having a set mixing ratio (set mixed concentration), for example, the first gas is a high-concentration diborane gas. Then, the second gas is hydrogen gas, so that diborane gas having a high concentration (for example, 1000 ppm) is diluted with hydrogen gas and diborane gas having a set mixing ratio (for example, 100 ppm) is supplied to the epitaxial apparatus. As a result, the consumption per unit time of high-concentration diborane gas can be reduced, and a stable and constant concentration of diluted diborane gas can be continuously supplied to the epitaxial device without replacing the high-concentration diborane gas supply cylinder during the continuous operation period. It is something that can be done.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of a gas mixture supply apparatus according to the present invention, and FIG. 2 shows a diborane gas supply system including the apparatus of this embodiment. This system dilutes a high concentration diborane gas with hydrogen gas and supplies it to an epitaxial device. In the following description, elements corresponding to those shown in FIG. 3 of the conventional example are denoted by the same reference numerals, and redundant description thereof is simplified or omitted.
[0021]
In FIG. 2, a plurality of (four in this figure) cylinders 9 are arranged as a diborane gas supply source, and high-concentration diborane gas as a first gas diluted to 1000 ppm with hydrogen gas is placed in each cylinder 9. Packed. The delivery passages of the cylinders 9 are integrated into a pipe line 2, and the pipe line 2 is branched into a coarse mixing line 2a and a fine mixing line 2b, and then integrated again to form a gas mixer (hereinafter also simply referred to as a mixer). ) 5 is connected in communication. The branching pipe line may be bifurcated, but if the pipe of the branching part in the example of FIG. 2 is described in more detail, the coarse mixing line 2a is a pipe line that extends the pipe pipe line 2, The fine mixing line 2b is a bypass pipeline of the extension pipeline.
[0022]
On the other hand, a piping line 10 equipped with elements such as a check valve 6, a filter 7 and various required valves 8 is led out from a supply source of hydrogen gas as the second gas. The path 10 is branched into a coarse mixing line 10a and a fine mixing line 10b, and is then integrated again and connected to the mixer 5. The branch pipe may be a bifurcated pipe, but the rough mixing line 10a shown in FIG. 2 is formed by an extension pipe of the pipe pipe 10, and the fine mixing line 10b is an extension pipe 10 (10a). It is a bypass pipeline.
[0023]
The rough mixing line 2a and the rough mixing line 10a are mixers for high-concentration diborane gas supplied from the cylinder 9 through the pipe line 2 and hydrogen gas supplied from the hydrogen gas supply source through the pipe line 10. 5 comprises a coarse mixing line of one system for rough mixing, and the fine mixing line 2b and the fine mixing line 10b are a high-concentration diborane gas supplied from the cylinder 9 via the pipe line 2 and a hydrogen gas supply source. A fine-mixing line is configured to finely mix the hydrogen gas supplied through the pipe line 10 from within the mixer 5. The coarse mixing lines 2a and 10a are provided with flow control devices (mass flow controllers) 12a and 13a for controlling the flow rate according to the valve opening of the mixing ratio of high-concentration diborane gas and hydrogen gas. Are provided with electronic flow control valves 12b and 13b for controlling the flow rate by variable control of the valve opening. In addition, 12b and 13b can be comprised using a mass flow controller (flow control apparatus) instead of a flow control valve.
[0024]
A mixed gas supply line 14 is connected to the outlet of the mixer 5, and the mixed gas supply path 14 functions as a mixed gas concentration detection means 15, a mixer buffer 16, and a monitor gas concentration detection sensor 17. The gas amount detection sensor (mass flow meter) 18 and the buffer container 3 are sequentially led to a plurality of epitaxial devices that are randomly operated, not shown. The gas concentration detection sensor 15 is an infrared absorption type in-line sensor that instantaneously and continuously detects the concentration of the mixed gas of diborane gas and hydrogen gas (diborane gas concentration) discharged from the mixer 5. An in-line sensor is a sensor that samples a gas to detect its concentration, and does not discard the sampled gas, but directly puts it in the line for measurement.
[0025]
The mixer buffer 16 is a buffer tank that equalizes the gas pressure discharged from the mixer 5. The monitor gas concentration detection sensor 17 is an infrared absorption sensor that monitors the concentration of the mixed gas whose gas pressure is leveled. The detection signal of the monitor gas concentration detection sensor 17 is a monitoring device (not shown) or the like. When the abnormal concentration is detected by the monitoring gas concentration detection sensor 17, the monitoring device notifies the abnormality.
[0026]
The gas amount detection sensor 18 detects the amount of gas mixture (the amount used per unit time) used at the use point of the epitaxial apparatus by measuring the flow rate. A gas removal conduit 19 is branchedly connected to the mixed gas supply passage 14 between the gas amount detection sensor 18 and the buffer container 3, and the gas removal conduit 19 is connected via a pressure holding valve (back pressure regulator) 20. It is led out of the system. When the pressure rises above the set pressure, the holding pressure valve 20 releases the increased pressure to the outside of the system through the gas removal pipe 19, maintains the pressure in the buffer container 3 at the set pressure, and maintains a constant pressure mixed gas. Is supplied to the epitaxial apparatus.
[0027]
The first feature point in the present embodiment is that the mixed gas obtained by roughly mixing the high-concentration diborane gas and the hydrogen gas at a set mixing ratio using the rough mixing lines 2a and 10a is used at the use point of the epitaxial apparatus. In other words, it has a configuration in which the used amount is continuously generated every moment. In addition, the second feature point in the present embodiment is that the concentration of the coarse mixed gas generated by using the coarse mixing lines 2a and 10a (deviation with respect to the set concentration) is changed to the fine adjustment mixing lines 2b and 10b. Is used to eliminate (correct the deviation to zero).
[0028]
As shown in FIG. 1, the configuration of the first feature point includes a gas amount detection sensor 18 and a gas mixing control unit, and this gas mixing control unit includes an arithmetic control unit (signal generator). ) 21 and the control drive signal output unit 22 (in the configuration in the figure, the illustration is simplified and illustrated as one output (one output)), but in reality, there are two outputs, and in the figure, 2 is indicated as x2. And the flow rate control devices 12a and 13a. The gas amount detection sensor 18 detects the amount (flow rate) of the mixed gas discharged from the mixer buffer 16 as a gas usage amount at a use point in the epitaxial apparatus, and adds the detection value PV to the calculation control unit 21.
[0029]
The calculation control unit 21 is provided with a preset mixing ratio of high-concentration diborane gas and hydrogen gas to the data storage unit, for example, 1: 9, and the calculation control unit 21 uses the detected value PV as a gas generation amount set value. It is taken in as SV and temporarily stored in a memory, and the amount (flow rate) of high-concentration diborane gas and the amount (flow rate) of hydrogen gas required to obtain a mixed gas in the amount of the gas generation amount set value SV at the set mixing ratio. ) Is calculated. Then, the control drive signal output unit 22 sends this calculated value as a set value signal to the flow rate control devices 12a and 13a. In the flow rate control devices 12a and 13a, the gas flow rate is controlled by the control valve in the flow rate control devices 12a and 13a and the built-in PID calculation unit so as to become the gas flow rate of the set value signal according to the set value signal. Send to 5.
[0030]
That is, the flow control device 12a controls the valve opening so that the flow rate of the high-concentration diborane gas is the set value signal. The amount of the high concentration diborane gas produced.
[0031]
Similarly, the flow rate control device 13a controls the valve opening so that the hydrogen gas flow rate of the set value signal is obtained. As a result, the amount (flow rate) of hydrogen gas passing through the rough mixing line 10a is calculated by the arithmetic control unit 21. The amount of hydrogen gas.
[0032]
As described above, the valve opening amount control of the flow rate control devices (mass flow controllers) 12a and 13a is performed based on the detection result of the gas usage amount of the gas amount detection sensor 18. As a result, the coarse mixing lines 2a and 10a are used to increase the flow rate. A mixed gas (crude mixed gas) obtained by mixing a concentration diborane gas and hydrogen gas at a set mixing ratio is continuously generated and supplied to the use point by the amount used at the use point.
[0033]
The configuration of the second feature point in the present embodiment is configured to include a gas concentration detection sensor 15 and a gas concentration fine control unit, and the gas concentration fine control unit includes a two-output type regulator 31 and a flow rate. It has a control valve 12b and a flow rate control valve 13b. The configuration of the second feature point is provided to correct a deviation (a deviation from a set mixture concentration) of the concentration of the mixed gas (diborane gas concentration) generated using the coarse mixing lines 2a and 10a. ing.
[0034]
That is, the generation of the mixed gas using the coarse mixing lines 2a and 10a is performed by setting the gas amount of the gas generation amount setting value SV (the target generation gas amount) to the amount of the high-concentration diborane gas and the amount of hydrogen gas at a set mixing ratio. The mixed gas is generated by the flow rate control of the flow rate control devices 12a and 13a. However, the control valve of the flow rate control has, for example, a solid difference (accuracy variation) of ± 2% in the control accuracy. Therefore, when gas is mixed using the flow rate control devices 12a and 13a, there is a relationship between the flow rate and the mixing concentration. In order not to be linear, if the amount of gas used at the point of use changes from moment to moment depending on the recipe, the mixing concentration will also change according to the amount of change in use (flow rate change), and the coarse mixing lines 2a, 10a will be changed. There is a circumstance that it is difficult to control the mixing concentration to be constant by the gas mixing method using the mixing ratio used.
[0035]
In view of such circumstances, in the present embodiment, an amount of mixed gas suitable for use is a gas having a substantially set concentration (a concentration assuming a slight deviation from the set concentration) using the coarse mixing lines 2a and 10a. The deviation from the set concentration is intended to be performed using the fine mixing lines 2b and 10b of the minute flow rate line, and the gas concentration detection sensor 15 uses the concentration of the mixed gas discharged from the mixer 5 ( The concentration of diborane gas) is instantaneously detected and the detection signal is applied to the two-output type controller 31.
[0036]
The two-output type controller 31 is preliminarily given with a memory or the like a set mixture concentration determined by the set mixture ratio of high-concentration diborane gas and hydrogen gas. The two-output type controller 31 detects the gas amount. Based on the mixed gas usage data detected by the sensor 18, the set mixed concentration data read from the memory, and the mixed gas detection concentration data detected by the gas concentration detection sensor 15, the mixed gas with respect to the set mixed concentration The amount of gas compensation for the addition of either high-concentration diborane gas or hydrogen gas required to correct the detected concentration deviation to zero is calculated by PID calculation.
[0037]
For example, if the mixed gas detection concentration (diborane gas concentration) deviates higher than the set mixture concentration, the gas compensation amount of hydrogen gas to obtain the set mixed concentration is calculated, and conversely, the mixed gas detection concentration deviates slightly. If so, the gas compensation amount of the high concentration diborane gas is calculated. Further, the two-output regulator 31 creates a valve opening control signal for the flow rate control valves 12b and 13b for obtaining the calculated gas compensation amount and applies it to the corresponding flow rate control valves 12b and 13b.
[0038]
As a result of obtaining this valve opening control signal, the flow rate control valve 12b performs variable opening / closing driving of the valve so that the required valve opening amount is obtained. As a result, a high concentration diborane gas with a gas compensation amount is added to the mixer 5 through the fine mixing line 2b. The mixed gas in the mixer 5 that is supplied and has a lower concentration is corrected to a gas having a set mixed concentration.
[0039]
Similarly, the valve opening control signal is obtained, and the flow rate control valve 13b performs variable opening / closing of the valve so that the required opening amount is obtained. As a result, a gas compensation amount of hydrogen gas is added to the mixer 5 through the fine mixing line 10b. The supplied mixed gas in the mixer 5 having a higher concentration is corrected to a gas having a set mixed concentration.
[0040]
Next, the diborane gas mixture supply operation using the system of FIG. 2 will be described. In the resistivity control step of the epitaxial film using the epitaxial apparatus, 1000 ppm high-concentration diborane gas (diluted with hydrogen gas) delivered from each cylinder 9 with the four cylinders 9 of the diborane gas supply source opened. High-concentration diborane gas) joins while passing through the pipe line 2, passes through the coarse mixing line 2 a, and is introduced into the mixer 5. On the other hand, the hydrogen gas passes from the hydrogen gas supply source through the pipe line 10 and is introduced into the mixer 5 via the coarse mixing line 10a. At this time, the amount (flow rate) of the mixed gas of high-concentration diborane gas and hydrogen gas supplied from the mixer 5 to the epitaxial apparatus is detected by the gas amount detection sensor 18 as the value of the amount of gas used at the point of use. The valve opening amounts of the flow rate control devices 12a and 12b are set to gas mixture control means (calculation control unit 21, control drive signal output unit 22 and It is controlled by the flow rate control devices 12a, 13a). As a result, the mixed gas used at the point of use is generated by the mixer 5 continuously and constantly to the epitaxial device by mixing control to achieve the set mixing ratio.
[0041]
On the other hand, the concentration of the mixed gas discharged from the mixer 5 is detected by the gas concentration detection sensor 15, and when the detected concentration is higher than the set concentration, the gas concentration fine adjustment control means (two-output type regulator 31 and flow control valve). 12b and 13b), hydrogen gas (trace hydrogen gas) for correcting the concentration deviation from the fine mixing line 10b is additionally introduced into the mixer 5 under the control of the flow control valve 13b, and the gas mixture concentration is corrected to the set mixture concentration. Is done.
[0042]
Similarly, when the detected concentration of the gas concentration detection sensor 15 is lower than the set concentration, the high concentration diborane gas for correcting the concentration deviation from the fine mixing line 2b by the gas concentration fine control means is controlled by the flow control valve 12b. In addition, the gas mixture concentration is corrected to the set mixture concentration.
[0043]
The pressure of the mixed gas having the set mixed concentration is leveled by the mixer buffer 16, and the mixed gas concentration in this pressure leveled state is detected by the monitor gas concentration detection sensor 17. When an abnormality occurs in the detected concentration of the monitor gas concentration detection sensor 17, a safe operation such as stopping the system operation is performed.
[0044]
A mixed gas having a set mixed concentration is supplied to the buffer container 3 via the mixer buffer 16, but a pressure holding valve 20 is provided on the front side of the buffer container 3, and when the set pressure is exceeded, an excessive pressure is gas. Since it is discharged out of the system through the removal conduit 19, the buffer container 3 is always maintained at the set pressure. That is, when a concentration-adjusting gas is additionally supplied using the fine mixing lines 2b and 10b, a mixed gas larger than the amount used is generated by the mixer 5, so the pressure of the mixed gas exceeds the set pressure. At this time, the additionally generated amount of the mixed gas is thrown out of the system through the gas removal line 19, and the mixed gas adjusted to the set pressure by the buffer container 3 is stably supplied to the epitaxial apparatus. The gas thrown out of the system is a waste of resources, but the additional gas supply amount for concentration adjustment is performed using the fine mixing lines 2b and 10b, so the amount of the discarded gas is very small and the fine mixing line 2b. Compared with the case where the concentration adjustment is performed without using 10b, the amount of gas to be discarded can be significantly reduced to effectively use resources.
[0045]
According to the present embodiment, since the high-concentration diborane gas is diluted and generated and supplied to the epitaxial apparatus, a cylinder 9 filled with a high-concentration diborane gas of 1000 ppm, for example, is used as the diborane gas supply source. Can do. This makes it possible to reduce the consumption per unit time of the diborane gas in the cylinder as compared with the case of using the cylinder 1 filled with 100 ppm dilute diborane gas as shown in FIG. Replacing the diborane gas cylinder during the period can be avoided, and the problems of the conventional example associated with the cylinder replacement can be solved.
[0046]
In particular, in this embodiment, a plurality (four) of high-concentration diborane gas cylinders 9 are used at the same time, so that the period until the cylinders 9 are replaced can be made sufficiently long. In addition, by simultaneously using a plurality (four) of high-concentration diborane gas cylinders 9, it is possible to reduce the influence of variations in diborane gas concentration between the cylinders 9. That is, when the diborane gas cylinders 9 are replaced or used one by one, concentration variation occurs immediately after the cylinder 9 is replaced (switched), but by using a plurality of cylinders 9 at the same time, The concentration of the delivered gas is a concentration obtained by averaging the concentrations of the cylinders. Therefore, the variation in gas concentration before and after the cylinder replacement can be sufficiently reduced, and the influence of the variation in gas concentration accompanying the replacement of the cylinder 9 can be reduced.
[0047]
Further, as described above, since the frequency of replacing the cylinder 9 can be reduced, it is possible to greatly reduce the cost of the cylinder. In particular, in the current market, the price of diborane gas is almost the same due to the difference in gas concentration, so the benefit of reducing the cost of the cylinder is significant.
[0048]
Further, in this embodiment, the gas concentration detection sensor 15 is arranged immediately after the mixer 5 and upstream of the mixer buffer 16 before the pressure is leveled. A change in gas concentration can be detected instantaneously, and a deviation from the set concentration can be quickly corrected. In particular, in this embodiment, the gas concentration detection sensor 15 is composed of an infrared absorption sensor, so that the detection response characteristics are excellent, and the control accuracy for correcting the gas concentration deviation can be remarkably increased.
[0049]
Further, since the monitor gas concentration detection sensor 17 and the gas amount detection sensor 18 are provided on the downstream side of the mixer buffer 16, the monitor gas concentration detection sensor 17 can accurately detect the leveled gas concentration. The gas amount detection sensor 18 can accurately detect the gas amount detection without the influence of the pressure fluctuation.
[0050]
In addition, this invention is not limited to the said embodiment example, Various other embodiment can be taken. For example, in the above-described embodiment, the pipe line 2 is branched to form the coarse mixing line 2a and the fine mixing line 2b. For example, the pipe line 2 is configured as a pipe of the coarse mixing line 2a, and the fine mixing line is formed. 2b may be configured by separately providing piping for connecting the cylinder 9 and the mixer 5 in communication, and the lines 2a and 2b may be configured by mutually independent pipelines connecting the cylinder 9 and the mixer 5. Similarly, in the above embodiment, the pipe line 10 is branched to form the coarse mixing line 2a and the fine mixing line 10b. For example, the pipe line 10 is configured as a pipe of the coarse mixing line 10a and fine adjustment is performed. The mixing line 10 b may be configured by separately providing a pipe for connecting the hydrogen gas supply source and the mixer 5, and the lines 10 a and 10 b may be configured by mutually independent pipe lines connecting the hydrogen gas supply source and the mixer 5. However, by branching the coarse mixing line and the fine mixing line as in this embodiment, simplification of the pipe line can be achieved, cost savings associated with the saving of pipe members can be achieved, and the pipes of the pipe line can be cleaned up. In addition, the effect of facilitating piping construction can be obtained.
[0051]
Furthermore, in the above embodiment, the high concentration diborane gas of 1000 ppm that is the first gas is diluted and mixed with the hydrogen gas that is the second gas, and 100 ppm of diborane gas that is used at the point of use is generated and supplied. The first gas may be a pure gas and the second gas may be a diluted gas. In the above example, the second gas is a gas for diluting the first gas (base gas hydrogen gas for diluting the diborane gas, which is the mother dope gas), but the first gas and the second gas A component is not limited to this, For example, the gas of the component which is not contained in 1st gas is good also as 2nd gas. In the above embodiment, a diborane gas having a concentration of 1000 ppm is used as the high-concentration diborane gas. Of course, a concentration other than 1000 ppm may be used. In this specification, a diborane gas having a concentration of 500 ppm or more is used. It is defined as
[0052]
Furthermore, in the above-described embodiment, the mixed supply of two types of gases, the first gas and the second gas, has been described, but the present invention can be applied to a mixed supply of three or more types of gases. . In this case, the supply source of each gas type and the mixer 5 are connected by a pipe line having a coarse mixing line and a fine mixing line, and the coarse mixing line is used in the same manner as in the case of mixing the above two kinds of gases. The flow rate is controlled by the ratio of the mixing ratio, and the deviation from the set concentration may be corrected using the fine mixing line.
[0053]
Further, in the above embodiment, the gas concentration detection sensor 15 is configured by an infrared absorption sensor, but other concentration detection means such as gas chromatography may be used.
[0054]
Furthermore, in the above embodiment, when finely adjusting the deviation of the mixed gas concentration (diborane gas concentration) using the fine adjustment mixing lines 2b and 10b, the information on the amount of gas used by the gas amount detection sensor 18 is used. The deviation correction of the mixed gas concentration may be performed without using the detection information of the amount detection sensor 18. In that case, in the memory of the two-output type controller 31, the relationship data between the deviation amount and the gas compensation amount, which increases the gas compensation amount (additional gas supply amount) as the deviation amount with respect to the set mixed concentration increases, is stored. Give it in advance.
[0055]
In this state, the two-output type controller 31 compares the mixed gas detection concentration detected by the gas concentration detection sensor 15 with the set mixed concentration to obtain a deviation of the mixed gas detection concentration with respect to the set mixed concentration. A gas compensation amount corresponding to the magnitude of the deviation amount is obtained by PID calculation based on the relational data (when the deviation amount is positive, the gas compensation amount of hydrogen gas is obtained, and when the deviation amount is minus, the gas of high concentration diborane gas is obtained. In addition to the corresponding flow rate control valves 12b and 13b, the flow rate control valves 12b and 13b are added to the corresponding flow rate control valves 12b and 13b in addition to the obtained gas compensation amount valve opening control signal for the high concentration diborane gas or hydrogen gas. The deviation of the mixed gas concentration can be corrected to zero by opening the valve.
[0056]
If this control mode is adopted, the gas compensation amount additionally supplied decreases as the deviation of the mixed gas concentration is corrected and the deviation becomes smaller. The amount of deviation converges to zero over time, and thereafter, the amount of deviation disappears, so that the mixed gas having the set mixed concentration can be stably supplied and maintained, and it is high without being affected by the detection error of the gas amount detection sensor 18. An epoch-making effect that the gas concentration can be accurately adjusted can be obtained.
[0057]
Further, in FIG. 2 of the above-described embodiment, four high-concentration diborane gas cylinders 9 are bundled and used. However, two high-concentration diborane gas cylinders 9 are set and used by alternately switching one by one. Also good. In addition, when different concentrations of gas are required at the point of use, another set of the configuration of the portion A surrounded by the broken line in FIG. 2 should be added (the portion B surrounded by the broken line in FIG. 2 is commonly used). It is possible to respond.
[0058]
Further, in the above-described embodiment, the resistivity control of the epitaxial film has been described as an example. However, the present invention is not limited to the generation of mixed gas in the field of semiconductor manufacturing other than that. This is applied to the field of mixed gas generation other than manufacturing.
[0059]
【The invention's effect】
In the present invention, the gas supply line from each of the first and second gas supply sources to the gas mixer has two lines of a coarse mixing line and a fine mixing line. The amount of gas used at the point of use (the amount of gas commensurate with the use of the point of use) is mixed and generated with a concentration close to the set concentration by the mixing ratio control, and the minute concentration deviation from the set concentration is finely adjusted. It can be corrected using a mixing line. As described above, the mixed gas is generated by using the two lines of the mixing ratio control line and the concentration fine adjustment line. For example, the first gas and the second gas are formed by only one line. Compared with the case where the mixed gas is generated by controlling the flow rate of the gas, the control accuracy of the concentration is remarkably increased, and an effect of stably supplying a highly reliable mixed gas having a constant concentration is obtained.
[0060]
In particular, in the present invention, the gas mixture control means mixes the first gas and the second gas with the distribution ratio of the set gas mixture ratio to generate the amount of gas used at the point of use. Therefore, as described above, the mixed concentration is substantially equal to the set mixed concentration. Therefore, even if the control means on the fine-mixing line side that corrects the fine deviation in concentration should break down, the amount of gas supplied from the fine-mixing line to the gas mixer is very small. It is possible to prevent a problem that gas is supplied to the use point.
[0061]
Furthermore, since the present invention detects the concentration of the mixed gas discharged directly from the gas mixer by the mixed concentration detecting means, the change in the mixed concentration can be detected instantaneously, and the gas concentration can be detected based on the detected value. Since the concentration deviation is instantly corrected and controlled by the fine control means, the accuracy of the gas concentration deviation correction control can be improved. In particular, by configuring the mixed concentration detection means with an infrared absorption sensor, the responsiveness of concentration detection can be improved, and the mixed gas used for detection (the mixed gas in contact with the infrared absorption sensor) can be used. Since it can be used by supplying it to a use point without being thrown away, there is no waste of gas utilization, and the effect that the utilization efficiency of the mixed gas can be sufficiently increased can be obtained.
[0062]
Further, in the present invention, the first gas is a high-concentration diborane gas (high-concentration dopant gas), the second gas is hydrogen gas (a pure gas for dilution), and the diluted diborane gas obtained by mixing the high-concentration diborane gas and the hydrogen gas is epitaxial. When it is applied to a usage pattern in which the resistivity of the epitaxial film is supplied to the apparatus, high-concentration diborane gas is stored in a container (eg, a cylinder) of a diborane gas supply source, and this high-concentration diborane gas is diluted with hydrogen gas for use. Since the system configuration to supply to the point can be adopted, compared to the case where diborane gas having a dilute concentration equal to the concentration used at the point of use is supplied from the cylinder to the epitaxial device as in the conventional example, high concentration diborane gas from the cylinder is supplied to the gas mixer. The present invention, which can adopt the supply method, is a unit of diborane gas in the cylinder. The consumption of gas per between can be significantly reduced.
[0063]
Therefore, by adopting the configuration of the present invention, it is not necessary to replace the diborane gas cylinder during the continuous operation period of the epitaxial apparatus, and the concentration change of the diborane gas occurs immediately after the cylinder replacement, which hinders the resistivity control. It is possible to solve the conventional problems caused by cylinder replacement.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating the configuration of an embodiment of a gas mixture supply apparatus applied to a gas mixture supply method according to the present invention.
FIG. 2 is an explanatory diagram of a diborane gas supply system including the gas mixture supply apparatus shown in FIG.
FIG. 3 is an explanatory diagram of a conventional example of a diborane gas supply system.
[Explanation of symbols]
2a, 10a Coarse mixing line
2b, 10b Fine mixing line
5 Mixer (gas mixer)
12a, 13a Flow control device (mass flow controller)
12b, 13b Flow control valve
15 Gas concentration detection sensor
18 Gas amount detection sensor
20 Holding valve
21 Operation control unit (signal generator)
31 2-output regulator

Claims (4)

The first gas supplied from the first gas supply source and the second gas supplied from the second gas supply source are mixed by a gas mixer, and the first gas and the second gas are mixed. A gas mixture supply method for supplying a mixed gas having a set mixed concentration to a use point,
Said first and second gas supply line to the gas mixer from the gas supply source and formed with two systems of lines of the respective crude mixed Gora in and fine adjustment mixing line,
Detect the amount of mixed gas used at the use point,
The detected gas usage amount is set as a gas generation amount set value, and the first gas gas is supplied from the gas supply source to the gas mixer through a coarse mixing line with a distribution ratio of a set gas mixture ratio that becomes the set mixture concentration. The distribution amount of the gas and the second gas is distributed and controlled so that the mixed amount becomes the gas generation amount setting value, and
Detecting the mixed concentration of the mixed gas discharged from the gas mixer;
Find the deviation of the detected mixed concentration with respect to the set mixed concentration,
When the detected mixed concentration of the first gas deviates higher than the set mixed concentration, a gas compensation amount of the second gas for obtaining the set mixed concentration is additionally supplied, and the first gas is supplied to the set mixed concentration. When the detected mixed concentration of the gas is deviated slightly, a gas compensation amount of the first gas for obtaining the set mixed concentration is additionally supplied. A gas mixed supply method, wherein the first gas and the second gas are selectively supplied additionally . The first gas supplied from the first gas supply source and the second gas supplied from the second gas supply source are mixed by a gas mixer, and the first gas and the second gas are mixed. A gas mixing supply device for supplying a mixed gas having a set mixed concentration to a use point,
  Forming a gas supply line from each of the first and second gas supply sources to the gas mixer having two lines, a coarse mixing line and a fine mixing line, respectively;
  A gas amount detection sensor for detecting the amount of mixed gas used at the use point;
  The gas usage detected by the gas amount detection sensor is set as a gas generation amount set value, and supplied from the gas supply source to the gas mixer through the coarse mixing line with the distribution ratio of the set gas concentration to the set mixed concentration. Gas mixing control means for distributing and controlling the supply amount of the first gas and the second gas so that the mixing amount becomes the gas generation amount set value;
  Mixed concentration detection means for detecting the mixed concentration of the mixed gas discharged from the gas mixer;
  The difference between the detected mixture concentration with respect to the set mixture concentration is obtained, and the supply amounts of the first gas and the second gas supplied from the respective gas supply sources to the gas mixer through the respective fine mixing lines in order to eliminate the deviation. Gas concentration fine control means for controlling,
  The gas concentration fine adjustment control unit additionally supplies a gas compensation amount of the second gas for obtaining the set mixed concentration when the detected mixed concentration of the first gas is deviated higher than the set mixed concentration, When the detected mixed concentration of the first gas deviates slightly from the set mixed concentration, detection for the set mixed concentration is performed such that a gas compensation amount of the first gas for obtaining the set mixed concentration is additionally supplied. Alternatively supply the first gas and the second gas in accordance with the direction of deviation of the mixed concentration,
Gas mixing supply device. 3. The gas mixture supply apparatus according to claim 2, wherein the mixed concentration detection means is an infrared absorption type gas concentration detection sensor. 4. The gas mixture supply apparatus according to claim 2, wherein the first gas is a high-concentration dopant gas, and the second gas is a dilution pure gas for diluting the dopant gas.

Images