High-precision gas concentration monitoring device based on ultrasonic flight time

Abstract

The utility model discloses a high-precision gas concentration monitoring device based on ultrasonic flight time. The high-precision gas concentration monitoring device is horizontally or vertically arranged beside an MFC (Microbial Fuel Cell) in a cabinet gas cabinet and is used for monitoring the gas concentration in real time. The device structurally comprises a sensor and a controller, wherein the sensor comprises a gas pipeline, a gas chamber, an ultrasonic chamber, a sealing ring and a temperature control assembly. Ultrasonic waves are sequentially sent out through the ultrasonic transducer in the downstream direction and the countercurrent direction, the controller processes the ultrasonic waves and calculates flight time signals, the flight time signals are converted into real-time concentration of gas to be output, and a process gas concentration (VOL%)-time (s) curve graph is displayed on a GUI interface. The gas concentration monitoring device has the beneficial effects that the gas concentration monitoring with high detection precision and wide range is realized through the work of the high-frequency ultrasonic transducer, and the gas concentration monitoring device is suitable for various semiconductor process applications.

Description

Technical Field

[0001] The utility model relates to the technical field of semiconductor gas monitoring, and particularly relates to a high-precision gas concentration monitoring device based on ultrasonic flight time. Background Technique

[0002] Many types of process gases are involved in semiconductor manufacturing processes. These gases are toxic or flammable substances, presenting a series of risks such as personal safety, equipment safety, and fires, especially being most critical to the process quality. Therefore, it is necessary to accurately monitor the real-time concentration changes of process gases during semiconductor manufacturing processes.

[0003] In the prior art, semiconductor machine systems generally control the flow rates of different gases through multiple MFCs. Its measurement principle is capillary heat transfer differential calorimetry, and after mixing, it enters the process chamber of the machine for the process production process. Although the MFC is an accurate flow stabilizing device and its measurement value is not inaccurate due to fluctuations in temperature or pressure, it will be distorted due to dust, metal ion deposition, and humid corrosive gases, resulting in inaccurate measurements, and gas concentration fluctuations directly affect the process quality. In actual processes, it is found that when only using the MFC, its accuracy is 1.0%, and there is a certain fluctuation in the gas flow.

[0004] In summary, to improve the deficiency of low accuracy in concentration monitoring of the prior art, it is urgent to develop a new type of gas concentration monitoring device. In addition, the gas to be detected still needs to enter the chamber to participate in the process after passing through the device, so the impact brought by the particle level of the device itself cannot be ignored to prevent process pollution or even serious damage to the machine. Therefore, the existence of these deficiencies restricts the further improvement of the semiconductor process production level. Content of the Utility Model

[0005] The purpose of the utility model is to provide a high-precision gas concentration monitoring device based on ultrasonic flight time to solve the problems raised in the above background technique.

[0006] The utility model provides a high-precision gas concentration monitoring device based on ultrasonic flight time, which is horizontally or vertically installed beside the MFC in the machine cabinet of the machine to monitor the gas concentration in real time, including:

[0007] Sensor:

[0008] A gas pipeline, the gas pipeline includes an intake pipeline and an outlet pipeline;

[0009] A gas chamber, the gas chamber includes an intake chamber and an outlet chamber, and the intake chamber and the outlet chamber are hollow annular structures with small holes on the side walls;

[0010] An ultrasonic chamber, the ultrasonic chamber includes two ultrasonic transducers and the enclosed space thereof with a gas chamber, and the ultrasonic transducers are respectively disposed on both sides of the gas chamber;

[0011] A sealing ring, the sealing ring includes two sealing rings for sealing the gas chamber and the ultrasonic chamber;

[0012] A temperature control component, the temperature control component includes a thermostat and a heating jacket;

[0013] A controller.

[0014] Wherein, the sensor is connected to the controller through two data lines, and the controller is used to control the operation of the sensor.

[0015] Preferably, the frequency of the ultrasonic transducer is 5MHZ.

[0016] Preferably, the temperature control accuracy of the temperature control component is ±0.01°C.

[0017] Preferably, the length of the ultrasonic chamber is 8.66mm.

[0018] Preferably, the ports of the intake pipe and the outlet pipe of the device are standard 1 / 4” VCR male connectors.

[0019] Compared with the prior art, the beneficial effects of the present utility model are:

[0020] (1) Small volume: The device of the present utility model has a small volume, the length of the ultrasonic chamber is 8.66mm, and it is convenient to install and use;

[0021] (2) High detection accuracy: The detection accuracy range is 0.001232%-0.004381%;

[0022] (3) Wide detection range: It can detect the concentration range of 0-100%VOL, and has the advantage of wide-range concentration detection;

[0023] (4) Wide process application: It can be used in EPI, MOCVD, PECVD, ALD and CVD processes.

[0024] In summary, the present utility model has the advantages of small volume, convenient installation and use, high precision, wide range and multi-process application. Description of the Drawings

[0025] Figure 1 It is the effect diagram of the controller and the sensor of the present utility model;

[0026] Figure 2 It is the structural diagram of the sensor (excluding the heating jacket) of the present utility model;

[0027] Figure 3This is the internal gas distribution diagram of the ultrasonic chamber of the present utility model;

[0028] Figure 4 This is the working principle diagram of the ultrasonic chamber of the present utility model;

[0029] Figure 5 It is a graph of process gas concentration (VOL%) - time (s) in the application of EPI process;

[0030] Figure 6 It is a graph of process gas concentration (VOL%) - time (s) in the application of MOCVCD process;

[0031] Figure 7 It is a graph of process gas concentration (VOL%) - time (s) in the application of PEVCD process;

[0032] Figure 8 It is a graph of process gas concentration (VOL%) - time (s) in the application of ALD process;

[0033] Figure 9 It is a graph of process gas concentration (VOL%) - time (s) in the application of CVD process;

[0034] Figure 10 It is a graph of process gas concentration (VOL%) - time (s) in the application of EPI process.

[0035] In the figure: 11 sensor; 12 controller; 20, sensor (excluding heating jacket); 211, intake pipe; 212, outlet pipe; 221, gas chamber; 231 and 232, ultrasonic transducer; 311, binary mixed process gas; 312, air flow direction; 321 and 322, sealing ring; 411, downstream ultrasonic signal; 412, upstream ultrasonic signal; 421, intake chamber; 422, ultrasonic chamber; 423, outlet chamber; 4201 to 4202 to 4203 to 4204, air flow direction; thermistor; 431, downstream signal reception; 432, upstream signal reception. Specific embodiments

[0036] Next, the technical solutions in the embodiments of the present utility model will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present utility model. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all of the embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present utility model.

[0037] Embodiment 1

[0038] This embodiment specifically describes and demonstrates the structure and working principle of an ultrasonic device, as shown in Figure 1-4 Shown. A high-precision gas concentration monitoring device based on the time of flight of ultrasonic waves is horizontally or vertically installed beside the MFC in the machine cabinet to monitor the gas concentration in real time, including:

[0039] Sensor 12:

[0040] A gas pipeline, the gas pipeline includes an intake pipeline 111 and an outlet pipeline 112;

[0041] A gas chamber, the gas chamber 121 includes an intake chamber 421 and an outlet chamber 423, and the intake chamber and the outlet chamber are hollow annular structures with small holes on the side walls;

[0042] An ultrasonic chamber, the ultrasonic chamber includes two ultrasonic transducers 131, 132 and the space surrounded by them and the gas chamber, and the ultrasonic transducers are respectively placed on both sides of the gas chamber;

[0043] Sealing rings, the sealing rings include two sealing rings 312, 322, which are used for sealing the gas chamber and the ultrasonic chamber;

[0044] A temperature control component, the temperature control component includes a thermostat and a heating jacket;

[0045] A controller.

[0046] Among them, the sensor is connected to the controller through two data lines, and the controller is used to control the operation of the sensor.

[0047] Specifically, the frequency of the ultrasonic transducer is 5MHZ.

[0048] Specifically, the temperature control accuracy of the temperature control component is ±0.01°C.

[0049] Specifically, the length of the ultrasonic chamber is 8.66mm.

[0050] Specifically, the ports of the intake pipeline and the outlet pipeline of the device are standard 1 / 4" VCR male connectors.

[0051] Figure 1 This is the appearance effect diagram of the controller and sensor of the device described in the present invention, Figure 2 showing Figure 1 The internal structure and appearance 20 of the sensor 12 without the heating jacket shown in.

[0052] The specific gas flow direction and gas distribution in the sensor 12 of the present utility model are as follows: The gas enters the gas chamber 221 through the intake pipe 211 and then is discharged from the device through the outlet pipe 212. Among them, the gas flow direction of the gas 311 in the gas chamber 221 is from 4201 to 4202 to 4203 to 4204. Figure 3 The gas distribution of the gas 311 in the ultrasonic chamber is simulated. The gas flow direction in the ultrasonic chamber is 312, and the sealing rings 321 and 322 are used to seal the ultrasonic chamber. The internal gas path of the sensor 20 is designed through fluid field simulation and calculation, which solves the problems of gas flow velocity and interference with the sound velocity in the ultrasonic chamber 422. At the same time, the temperature control component makes the temperature field distribution of the sensor 20 uniform.

[0053] The working process in the ultrasonic chamber is as Figure 4 shown: The ultrasonic transducer 231 emits a downstream ultrasonic signal 411, which passes through the gas 311 in the ultrasonic chamber 422 and reaches the ultrasonic transducer 232 for downstream signal reception 431; immediately afterwards, the ultrasonic transducer 232 emits an upstream ultrasonic signal 432, which passes through the gas 311 in the ultrasonic chamber 422 and reaches the ultrasonic transducer 231 for upstream signal reception 412. Finally, the controller processes and converts the ultrasonic signals and outputs a curve graph of process gas concentration (VOL%) - time (s) on the GUI interface.

[0054] Embodiment 2

[0055] Based on Embodiment 1, in this embodiment, the device described in Embodiment 1 is used for EPI process application, including the following steps:

[0056] Step 1: Install the device on the machine tool of the target application process and turn on the power supply.

[0057] Step 2: Adjust the reading of the temperature controller to a certain temperature.

[0058] Step 3: Purge the sensor with pure nitrogen, and then introduce a binary mixed gas into the sensor for concentration calibration, and then start monitoring the real-time value of the process gas at the process-set concentration.

[0059] Step 4: The binary mixed gas enters the intake chamber through the intake pipe, then enters the ultrasonic chamber, and then is discharged through the outlet chamber and the outlet pipe.

[0060] Step 5: The ultrasonic transducers on both sides of the ultrasonic chamber successively emit ultrasonic signals in the downstream and upstream directions.

[0061] Step 6: The controller processes the ultrasonic signals to obtain the ultrasonic flight time and outputs the gas concentration in real time, and displays a curve graph of process gas concentration (VOL%) - time (s) on the GUI interface.

[0062] Specifically, the target application process in Step 1 is EPI.

[0063] Specifically, adjust the reading of the thermostat to 40 °C in Step 2.

[0064] Specifically, the binary mixed gas in Step 3 includes a process gas and a carrier gas. The process gas is DCS and the carrier gas is H2.

[0065] Specifically, calibrate the concentration of the process gas DCS in Step 3.

[0066] Specifically, monitor the concentration of the process gas DCS in Step 3.

[0067] Specifically, the set concentration of the EPI process in Step 3 is 0% VOL.

[0068] Specifically, the real-time output precision of the TCS gas concentration in Step 6 is 0.001232%.

[0069] Using the device provided in Example 1, it is applied to monitor the concentration of the process gas DCS in the EPI process. The curve graph of the process gas concentration (VOL%) - time (s) is as Figure 5 shown. Figure 5 It shows the real-time change of the concentration of the process gas DCS monitored by the present utility model. The overall trend of the concentration curve is stable, without drift, and its detection precision is 0.001232%. Compared with the test precision of only using MFC 1.0% in the machine platform system, the monitoring precision of the process gas concentration by this device is higher. Therefore, the measured concentration curve of the process gas DCS is stable and has small fluctuations. In this embodiment, the signal of the 5MHZ ultrasonic transducer passes through the mixed gas of DCS and H2 for signal transmission and reception. Through the precise control and extraction of the tiny ultrasonic time signal, the concentration of the process gas DCS is accurately output. Obviously, using the present utility model in the machine platform of the target process EPI is more conducive to controlling the concentration of the process gas DCS in a steady state. The present utility model achieves the purpose of precisely and stably transporting the process gas DCS in the EPI process.

[0070] Example 3

[0071] Based on Example 1, this example conducts MOCVD process applications through the device described in Example 1, including the following steps:

[0072] Step 1: Install the device in the machine platform of the target application process and turn on the power supply;

[0073] Step 2: Adjust the reading of the thermostat to a certain temperature;

[0074] Step 3: Purge the sensor with pure nitrogen, and then introduce the binary mixed gas into the sensor for concentration calibration, and then start monitoring the real-time value of the process gas at the process-set concentration;

[0075] Step 4: The binary mixed gas enters the intake chamber through the intake pipeline, then enters the ultrasonic chamber, and then is discharged through the outlet chamber via the outlet pipeline;

[0076] Step 6: The ultrasonic transducers on both sides of the ultrasonic chamber successively emit ultrasonic signals in the downstream and upstream directions;

[0077] Step 6: The controller processes the ultrasonic signals to obtain the ultrasonic flight time and outputs the gas concentration in real time, and displays the process gas concentration (VOL%) - time (s) curve graph on the GUI interface.

[0078] Specifically, the target application process in Step 1 is MOCVD.

[0079] Specifically, in Step 2, adjust the reading of the thermostat to 40°C.

[0080] Specifically, in Step 3, the binary mixed gas includes the process gas and the carrier gas. The process gas is TCS and the carrier gas is H2.

[0081] Specifically, in Step 3, calibrate the concentration of the process gas TCS.

[0082] Specifically, in Step 3, monitor the concentration of the process gas TCS.

[0083] Specifically, in Step 3, the EPI process-set concentration is 20% VOL.

[0084] Specifically, in Step 6, the real-time output accuracy of the TCS gas concentration is 0.004381%.

[0085] Using the device provided in Example 1, it is applied to monitor the concentration of the process gas TCS in the MOCVD process, and its process gas concentration (VOL%) - time (s) curve graph is as Figure 6 shown. Figure 6It shows the real-time change of the concentration of the process gas TCS monitored by the utility model. The overall trend of the concentration curve is stable without drift, and its detection accuracy is 0.004381%. Compared with the 1.0% test accuracy of only using MFC in the machine system, the monitoring accuracy of the process gas concentration by this device is higher. Therefore, the measured concentration curve of the process gas TCS is stable with small fluctuations. In this embodiment, the signal of the 5MHZ ultrasonic transducer passes through the mixed gas of TCS and H2 for signal transmission and reception. Through the precise control and extraction of the ultrasonic time micro-signal, the concentration of the process gas TCS is accurately output. Obviously, it is easier to control the concentration of the process gas TCS in a steady state when using the utility model in the machine of the target process MOCVD. The utility model achieves the purpose of precisely and stably transporting the process gas TCS in the MOCVD process.

[0086] Embodiment 4

[0087] Based on Embodiment 1, this embodiment applies the PECVD process through the device described in Embodiment 1, including the following steps:

[0088] Step 1: Install the device in the machine of the target application process and turn on the power supply;

[0089] Step 2: Adjust the reading of the temperature controller to a certain temperature;

[0090] Step 3: Purge the sensor with pure nitrogen, and then pass the binary mixed gas into the sensor for concentration calibration and start monitoring the real-time value of the process gas at the process-set concentration;

[0091] Step 4: The binary mixed gas enters the intake chamber through the intake pipeline, then enters the ultrasonic chamber, and then is discharged through the outlet chamber through the outlet pipeline;

[0092] Step 5: The ultrasonic transducers on both sides of the ultrasonic chamber successively emit ultrasonic signals in the downstream and upstream directions;

[0093] Step 6: The controller processes the ultrasonic signals to obtain the ultrasonic flight time and real-time outputs the gas concentration, and displays the process gas concentration (VOL%) - time (s) curve graph on the GUI interface.

[0094] Specifically, the target application process in Step 1 is PECVD.

[0095] Specifically, in Step 2, the reading of the temperature controller is adjusted to 40°C.

[0096] Specifically, in Step 3, the binary mixed gas includes a process gas and a carrier gas. The process gas is HCD and the carrier gas is NH3.

[0097] Specifically, in step 3, the concentration of process gas HCD is calibrated.

[0098] Specifically, what is monitored in step 3 is the concentration of process gas HCD.

[0099] Specifically, the set concentration of the EPI process in step 3 is 40% VOL.

[0100] Specifically, the real-time output accuracy of the HCD gas concentration in step 6 is 0.003331%.

[0101] Using the device provided in Example 1, it is applied to monitor the concentration of process gas HCD in the PECVD process. The curve graph of the process gas concentration (VOL%) - time (s) is as Figure 7 shown. Figure 7 It shows the real-time change of the concentration of process gas HCD monitored by the present utility model. The overall trend of the concentration curve is stable without drift, and its detection accuracy is 0.003331%. Compared with the 1.0% test accuracy of only using MFC in the machine platform system, the monitoring accuracy of the process gas concentration by this device is higher. Therefore, the measured concentration curve of process gas HCD is stable with small fluctuations. In this embodiment, the signal of the 5MHZ ultrasonic transducer passes through the mixed gas of HCD and NH3 for signal transmission and reception. Through the precise control and extraction of the tiny ultrasonic time signal, the concentration of process gas HCD is accurately output. Obviously, using the device of the present utility model in the machine platform of the target process PECVD is more conducive to controlling the concentration of process gas HCD in a steady state. The present utility model achieves the purpose of precisely and stably transporting process gas HCD in the PECVD process.

[0102] Example 5

[0103] Based on Example 1, this embodiment applies the device described in Example 1 to the ALD process, including the following steps:

[0104] Step 1: Install the device in the machine platform of the target application process and turn on the power supply;

[0105] Step 2: Adjust the reading of the temperature controller to a certain temperature;

[0106] Step 3: Purge the sensor with pure nitrogen, and then pass the binary mixed gas into the sensor for concentration calibration and then start monitoring the real-time value of the process gas at the set process concentration;

[0107] Step 4: The binary mixed gas enters the intake chamber through the intake pipeline, then enters the ultrasonic chamber, and then is discharged through the outlet chamber and the outlet pipeline;

[0108] Step 5: The ultrasonic transducers on both sides of the ultrasonic chamber successively emit ultrasonic signals in the downstream and upstream directions;

[0109] Step 6: The controller processes the ultrasonic signals to obtain the ultrasonic flight time and outputs the gas concentration in real time, and displays the process gas concentration (VOL%) - time (s) curve graph on the GUI interface.

[0110] Specifically, the target application process in Step 1 is ALD.

[0111] Specifically, in Step 2, the reading of the thermostat is adjusted to 40 °C.

[0112] Specifically, in Step 3, the binary mixed gas includes a process gas and a carrier gas. The process gas is TMA, and the carrier gas is O3.

[0113] Specifically, in Step 3, the concentration of the process gas TMA is calibrated.

[0114] Specifically, in Step 3, the concentration of the process gas TMA is monitored.

[0115] Specifically, in Step 3, the set concentration of the EPI process is 60% VOL.

[0116] Specifically, in Step 6, the accuracy of the real-time output of the TMA gas concentration is 0.002737%.

[0117] Using the device provided in Example 1, it is applied to monitor the concentration of the process gas TCS in the ALD process. The process gas concentration (VOL%) - time (s) curve graph is as Figure 8 shown. Figure 8 It shows the real-time change of the concentration of the process gas TMA monitored by the device of the present invention. The overall trend of the concentration curve is stable, without drift, and its detection accuracy is 0.002737%. Compared with the test accuracy of only using MFC 1.0% in the machine platform system, the device of the present invention has a higher monitoring accuracy for the process gas concentration. Therefore, the measured concentration curve of the process gas TMA is stable and has small fluctuations. In this embodiment, the signal of the 5MHZ ultrasonic transducer passes through the mixed gas of TMA and O3 for signal transmission and reception. Through the precise control and extraction of the ultrasonic time micro-signal, the concentration of the process gas TMA is accurately output. Obviously, using the device of the present invention in the machine platform of the target process ALD is more conducive to controlling the concentration of the process gas TMA in a steady state. The present invention achieves the purpose of accurately and stably transporting the process gas TMA in the ALD process.

[0118] Example 6

[0119] On the basis of Example 1, this embodiment applies the device described in Example 1 to the CVD process, including the following steps:

[0120] Step 1: Install the device in the machine of the target application process and turn on the power supply;

[0121] Step 2: Adjust the reading of the thermostat to a certain temperature;

[0122] Step 3: Purge the sensor with pure nitrogen, then introduce the binary mixed gas into the sensor for concentration calibration, and then start monitoring the real-time value of the process gas at the process-set concentration;

[0123] Step 4: The binary mixed gas enters the intake chamber through the intake pipeline, then enters the ultrasonic chamber, and then is discharged through the outlet chamber via the outlet pipeline;

[0124] Step 5: The ultrasonic transducers on both sides of the ultrasonic chamber successively emit ultrasonic signals in the downstream and upstream directions;

[0125] Step 6: The controller processes the ultrasonic signals to obtain the ultrasonic flight time and outputs the gas concentration in real time, and displays the process gas concentration (VOL%) - time (s) curve graph on the GUI interface.

[0126] Specifically, the target application process in Step 1 is CVD.

[0127] Specifically, the reading of the thermostat is adjusted to 40 °C in Step 2.

[0128] Specifically, the binary mixed gas in Step 3 includes a process gas and a carrier gas. The process gas is DCS and the carrier gas is NH3.

[0129] Specifically, the concentration of the process gas DCS is calibrated in Step 3.

[0130] Specifically, the concentration of the process gas DCS is monitored in Step 3.

[0131] Specifically, the CVD process-set concentration in Step 3 is 80% VOL.

[0132] Specifically, the accuracy of the real-time output of the DCS gas concentration in Step 6 is 0.001746%.

[0133] Using the device provided in Example 1, it is applied to monitor the concentration of the process gas DCS in the CVD process. The process gas concentration (VOL%) - time (s) curve graph is as Figure 9 shown. Figure 6It shows the real-time change of the DCS concentration of the process gas monitored by the device of the present utility model. The overall trend of the concentration curve is stable without drift, and its detection accuracy is 0.001746%. Compared with the 1.0% test accuracy of only using MFC in the machine system, the concentration monitoring accuracy of the process gas by this device is higher. Therefore, the measured concentration curve of the process gas DCS is stable with small fluctuations. In this embodiment, the signal of the 5MHZ ultrasonic transducer passes through the mixed gas of DCS and NH3 for signal transmission and reception. Through the precise control and extraction of the tiny ultrasonic time signal, the concentration of the process gas DCS is accurately output. Obviously, using the device of the present utility model in the machine of the target process CVD is more conducive to controlling the concentration of the process gas DCS in a steady state. The present utility model achieves the purpose of precisely and stably transporting the process gas DCS in the CVD process.

[0134] Example 7

[0135] Based on Example 1, in this example, the device described in Example 1 is used for the EPI process application, including the following steps:

[0136] Step 1: Install the device in the machine of the target application process and turn on the power supply;

[0137] Step 2: Adjust the reading of the temperature controller to a certain temperature;

[0138] Step 3: Purge the sensor with pure nitrogen, and then introduce the binary mixed gas into the sensor for concentration calibration, and then start monitoring the real-time value of the process gas at the process-set concentration;

[0139] Step 4: The binary mixed gas enters the intake chamber through the intake pipeline, then enters the ultrasonic chamber, and then is discharged through the outlet chamber via the outlet pipeline;

[0140] Step 5: The ultrasonic transducers on both sides of the ultrasonic chamber successively emit ultrasonic signals in the downstream and upstream directions;

[0141] Step 6: The controller processes the ultrasonic signal to obtain the ultrasonic flight time and outputs the gas concentration in real time, and displays the process gas concentration (VOL%) - time (s) curve graph on the GUI interface.

[0142] Specifically, the target application process in Step 1 is EPI.

[0143] Specifically, in Step 2, the reading of the temperature controller is adjusted to 40°C.

[0144] Specifically, in Step 3, the binary mixed gas includes a process gas and a carrier gas. The process gas is DCS and the carrier gas is H2.

[0145] Specifically, in step 3, the concentration of process gas DCS is calibrated.

[0146] Specifically, what is monitored in step 3 is the concentration of process gas DCS.

[0147] Specifically, the set concentration of the EPI process in step 3 is 100% VOL.

[0148] Specifically, the accuracy of the real-time output of the TCS gas concentration in step 6 is 0.001345%.

[0149] Using the device provided in Embodiment 1, it is applied to monitor the concentration of process gas DCS in the EPI process. The curve graph of the process gas concentration (VOL%) - time (s) is as Figure 10 shown. Figure 10 It shows the real-time change of the concentration of process gas DCS monitored by the device of the present invention. The overall trend of the concentration curve is stable without drift, and its detection accuracy is 0.001345%. Compared with the test accuracy of only using MFC 1.0% in the machine platform system, the monitoring accuracy of the process gas concentration by this device is higher. Therefore, the measured concentration curve of process gas DCS is stable with small fluctuations. In this embodiment, the signal of the 5MHZ ultrasonic transducer passes through the mixed gas of DCS and H2 for signal transmission and reception. Through the precise control and extraction of the tiny ultrasonic time signal, the concentration of process gas DCS is accurately output. Obviously, using the device of the present invention in the machine platform of the target process EPI is more conducive to controlling the concentration of process gas DCS in a steady state. The present invention achieves the purpose of precisely and stably transporting process gas DCS in the EPI process.

[0150] Embodiment 8

[0151] The present invention determines the concentration of the binary mixed process gas through the relationship between the speed of sound of the gas in the medium and its relative molecular mass. At the hardware structure level, the internal gas path of the sensor is designed through fluid field simulation and calculation, solving the problems of gas flow rate and interference with the speed of sound in the ultrasonic chamber. At the same time, the temperature control component controls the uniform distribution of the temperature field of the sensor. At the software level, the key technical factor lies in the precise control and extraction of the tiny signal of the flight time through a 5MHZ high-frequency ultrasonic transducer. The present invention is based on a high-precision gas concentration monitoring device and method based on ultrasonic flight time to realize the real-time and precise monitoring of semiconductor gas concentration. The results of Embodiments 1 to 7 show that in various combinations and different concentrations of binary mixed gases, very stable process gas concentration curve graphs are obtained when applied to EPI, MOCVD, PECVD, ALD, and CVD processes.

[0152]

[0153] Table 1 shows the test average standard deviation and detection accuracy data for concentrations from 0 VOL - 100% VOL. The detection accuracy range is 0.001232% - 0.004381%, which is two orders of magnitude higher than the detection accuracy of MFC at 1.0%. Gas concentration monitoring is more stable and accurate. In summary, the present utility model achieves the purpose of precisely and stably transporting process gases in EPI, MOCVD, PECVD, ALD, and CVD processes.

[0154] Although the embodiments of the present utility model have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present utility model. The scope of the present utility model is defined by the appended claims and their equivalents.

Claims

1. A high-precision gas concentration monitoring device based on ultrasonic time of flight, which is horizontally or vertically installed beside the MFC in the machine cabinet to monitor the gas concentration in real time, and is characterized in that, Comprising: Sensor: Gas pipeline, the gas pipeline comprising an intake pipeline and an outlet pipeline; Gas chamber, the gas chamber comprising an intake chamber and an outlet chamber, the intake chamber and the outlet chamber being hollow annular structures with small holes on the side walls; Ultrasonic chamber, the ultrasonic chamber comprising two ultrasonic transducers and the space enclosed by them and the gas chamber, the ultrasonic transducers being respectively placed on both sides of the gas chamber; Sealing ring, the sealing ring comprising two sealing rings for sealing the gas chamber and the ultrasonic chamber; Temperature control component, the temperature control component comprising a thermostat and a heating jacket; Controller, wherein, the sensor is connected to the controller through two data lines, and the controller is used to control the operation of the sensor.

2. The high-precision gas concentration monitoring device based on ultrasonic time of flight according to claim 1, wherein: The frequency of the ultrasonic transducer is 5 MHZ.

3. The high-precision gas concentration monitoring device based on ultrasonic flight time according to claim 2, characterized in that: The temperature control accuracy of the temperature control component is ±0.01 °C.

4. The high-precision gas concentration monitoring device based on ultrasonic time of flight according to claim 3, characterized in that: The length of the ultrasonic chamber is 8.66 mm.

5. The high-precision gas concentration monitoring device based on ultrasonic time-of-flight according to claim 4, wherein: The ports of the intake pipeline and the outlet pipeline of the device are standard 1 / 4" VCR male connectors.

Images