Semiconductor process equipment and pneumatic valve control method thereof

Abstract

The invention provides semiconductor process equipment and a pneumatic valve control method thereof. The pneumatic valve control method comprises the following steps: firstly, determining a target pneumatic valve in a plurality of pneumatic valves, and calculating a first time difference between the target pneumatic valve and a specified pneumatic valve; wherein the specified pneumatic valve is any one of the pneumatic valves except the target pneumatic valve; secondly, in the technological process, a second time difference between the target pneumatic valve and the designated pneumatic valve is determined; and finally, determining a time domain deviation value according to the first time difference and the second time difference, and controlling the target pneumatic valve and the specified pneumatic valve to be opened according to the time domain deviation value, so that the process source gas in the gas pipelines where the target pneumatic valve and the specified pneumatic valve are located simultaneously reaches the process chamber. Therefore, the problem of time domain deviation when multiple process source gases are introduced into the process chamber is relieved, and the process result of the epitaxial wafer is ensured.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and more particularly to semiconductor process equipment and its pneumatic valve control method. Background Art

[0002] Epitaxial growth refers to growing a specific thin film on the basis of a wafer through an epitaxial process. The substrate wafer and the epitaxial thin film are collectively called an epitaxial wafer. In practical applications, the epitaxial layer growth of silicon carbide wafers mainly uses the Chemical Vapor Deposition (CVD) method, using silane SiH4 or trichlorosilane TCS as the Si source, and ethylene C2H4 or propane C3H8 as the C source. Under high temperature and reduced pressure environments, Si atoms and C atoms are generated through cracking reactions, and these two atoms recombine on the wafer surface to form a silicon carbide epitaxial layer.

[0003] Among them, in the silicon carbide epitaxial process, for the non-growth stage, the C-source gas and the Si-source gas are introduced into the vacuum pipeline and enter the vacuum exhaust gas to adjust and stabilize the flow rates of various gases; for the growth stage, the C-source gas and the Si-source gas are introduced into the process pipeline and enter the process chamber for epitaxial growth. In addition, pneumatic valves are respectively arranged in the gas paths of the C-source gas and the Si-source gas introduced into the process pipeline to open or close the corresponding gas from entering the process chamber. In the existing pneumatic valve control process, different pneumatic valves are sequentially issued commands from the host computer to the slave computer, and the slave computer outputs control commands to the pneumatic valve groups corresponding to different pneumatic valves, so that the pneumatic valve groups control the corresponding pneumatic valves to perform opening and closing actions. However, if the commands issued by the host computer are not in the same cycle, it will cause a time difference in the control commands issued by the slave computer; at the same time, the control commands received by different pneumatic valve groups may also have a time difference, and the actions performed by different pneumatic valves may also have a time difference. All of these will cause the opening and closing action times of the pneumatic valves to be inconsistent. At the same time, the distances of different pneumatic valves from the process chamber are also different, resulting in a deviation in the time when the C-source gas and the Si-source gas enter the process chamber, making the ratio of the C-source gas and the Si-source gas inconsistent with the process requirements, resulting in abnormal surface defects of the silicon carbide epitaxial layer; for example, when there is more C-source gas, small pits will appear on the surface of the epitaxial layer, and when there is more Si-source gas, silicon droplets will appear on the surface of the epitaxial layer. Both of these situations will cause the roughness and defects of the epitaxial layer to be unqualified, and in severe cases, the epitaxial wafer will be scrapped. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide semiconductor process equipment and its pneumatic valve control method, which realizes that multiple process source gases reach the process chamber simultaneously, solves the problem of time-domain deviation in the introduction of multiple process source gases into the process chamber, and thus ensures the process results of the epitaxial wafer.

[0005] First aspect, an embodiment of the present invention provides a pneumatic valve control method for a semiconductor process equipment. The semiconductor process equipment includes: a process chamber, a process pipeline connected to the process chamber, and a plurality of gas pipelines connected to the process pipeline. A pneumatic valve is provided between each gas pipeline and the process pipeline. The method includes: determining a target pneumatic valve among the plurality of pneumatic valves, and calculating a first time difference between the target pneumatic valve and a designated pneumatic valve; wherein, the designated pneumatic valve is any one of the plurality of pneumatic valves other than the target pneumatic valve, and the first time difference is used to represent the time difference between the valve opening action time of the target pneumatic valve and the valve opening action time of the designated pneumatic valve; during the process, determining a second time difference between the target pneumatic valve and the designated pneumatic valve; wherein, the second time difference is used to represent the time difference for the gas to enter the process chamber due to the distance between the first interface and the second interface. The first interface is the interface where the gas pipeline where the target pneumatic valve is located leads into the process pipeline, and the second interface is the interface where the gas pipeline where the designated pneumatic valve is located leads into the process pipeline; determining a time domain deviation value according to the first time difference and the second time difference; controlling the opening of the target pneumatic valve and the designated pneumatic valve according to the time domain deviation value, so that the process source gas in the gas pipelines where the target pneumatic valve and the designated pneumatic valve are located reaches the process chamber simultaneously.

[0006] In one embodiment, the step of calculating the first time difference between the target pneumatic valve and the designated pneumatic valve includes: obtaining the action execution duration of each pneumatic valve; wherein, the action execution duration is used to represent the duration used for the pneumatic valve to execute the opening action; calculating the first time difference according to the action execution duration of the target pneumatic valve and the action execution duration of the designated pneumatic valve.

[0007] In one embodiment, each gas pipeline is further provided with a detection device; wherein, the detection device is arranged between the pneumatic valve and the process pipeline; the step of obtaining the action execution duration of each pneumatic valve includes: simultaneously issuing a plurality of opening instructions, so that each pneumatic valve executes the opening action according to the corresponding opening instruction; for each pneumatic valve, obtaining the current time fed back by the detection device corresponding to the pneumatic valve; wherein, the current time is the time when the temperature difference between both ends of the detection device reaches a preset temperature difference; and, taking the difference between the current time and the issuing time of the opening instruction as the action execution duration of the pneumatic valve.

[0008] In one embodiment, before the step of simultaneously issuing a plurality of opening instructions, the method further includes: controlling the gas pipelines where the plurality of pneumatic valves are located to meet a preset condition; wherein, the preset condition includes: the product of the flow rate and specific heat capacity of the process source gas corresponding to each gas pipeline is a preset value.

[0009] In one embodiment, the step of determining a second time difference between a target pneumatic valve and a designated pneumatic valve includes: obtaining detection parameters of a process pipeline; wherein, the detection parameters include: actual carrier gas temperature, actual pipeline pressure, carrier flow rate, and multiple process source gas flow rates; calculating the second time difference between the target pneumatic valve and the designated pneumatic valve according to the detection parameters and preset basic parameters; wherein, the preset basic parameters include: standard temperature, standard air pressure, pipeline cross-sectional area, and pipeline distance difference, and the pipeline distance difference is the distance between a first interface and a second interface.

[0010] In one embodiment, the step of controlling the opening of the target pneumatic valve and the designated pneumatic valve according to a time domain deviation value includes: controlling the target pneumatic valve to open, and recording a first duration after opening; when the first duration reaches the time domain deviation value, controlling the designated pneumatic valve to open.

[0011] In one embodiment, the method further includes: when controlling the target pneumatic valve to close, recording a second duration after closing; when the second duration reaches the time domain deviation value, controlling the designated pneumatic valve to close.

[0012] In one embodiment, the step of determining a target pneumatic valve among multiple pneumatic valves includes: calculating the distance from each pneumatic valve to the process chamber, and taking the pneumatic valve with the largest distance as the target pneumatic valve.

[0013] In one embodiment, the step of determining a target pneumatic valve among multiple pneumatic valves includes: taking the pneumatic valve with the largest action execution duration as the target pneumatic valve.

[0014] In a second aspect, an embodiment of the present invention further provides a semiconductor process equipment, including: a lower computer, a process chamber, a process pipeline connected to the process chamber, and multiple gas pipelines connected to the process pipeline, and a pneumatic valve is provided between each gas pipeline and the process pipeline; wherein, the lower computer is configured to execute the method of the first aspect above.

[0015] The embodiments of the present invention bring the following beneficial effects:

[0016] Embodiments of the present invention provide a semiconductor process equipment and a pneumatic valve control method. First, a target pneumatic valve among multiple pneumatic valves is determined, and a first time difference between the target pneumatic valve and a specified pneumatic valve is calculated; wherein, the specified pneumatic valve is any one of the multiple pneumatic valves other than the target pneumatic valve, and the first time difference is used to characterize the time difference between the valve opening action time of the target pneumatic valve and the valve opening action time of the specified pneumatic valve; then, during the process, a second time difference between the target pneumatic valve and the specified pneumatic valve is determined; wherein, the second time difference is used to characterize the time difference for gas to enter the process chamber due to the distance between the first interface and the second interface, the first interface is the interface where the gas pipeline where the target pneumatic valve is located leads into the process pipeline, and the second interface is the interface where the gas pipeline where the specified pneumatic valve is located leads into the process pipeline; finally, a time domain deviation value is determined according to the first time difference and the second time difference, and the target pneumatic valve and the specified pneumatic valve are controlled to open according to the time domain deviation value, so that the process source gas in the gas pipelines where the target pneumatic valve and the specified pneumatic valve are located reaches the process chamber simultaneously, thereby alleviating the problem of time domain deviation when multiple process source gases are introduced into the process chamber, and further ensuring the process result of the epitaxial wafer.

[0017] Other features and advantages of the present invention will be described in the following description, and, in part, will be obvious from the description, or will be understood by implementing the present invention. The objectives and other advantages of the present invention are achieved and obtained by the structures specifically pointed out in the description and the drawings.

[0018] To make the above objectives, features, and advantages of the present invention more obvious and understandable, the following specifically enumerates preferred embodiments and, in conjunction with the accompanying drawings, the detailed description is as follows. Description of the Drawings

[0019] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0020] Figure 1 It is a schematic diagram of the existing silicon carbide epitaxial gas path structure;

[0021] Figure 2 It is a control flow chart of the existing pneumatic valve;

[0022] Figure 3 It is a control flow chart of the existing pneumatic valve with a position feedback function;

[0023] Figure 4 It is a schematic diagram of the process gas path structure of a semiconductor process equipment provided by an embodiment of the present invention;

[0024] Figure 5 This is a flowchart of a pneumatic valve control method for a semiconductor process equipment provided by an embodiment of the present invention;

[0025] Figure 6 This is a schematic structural diagram of a detection device provided by an embodiment of the present invention;

[0026] Figure 7 This is a flowchart of another pneumatic valve control method for a semiconductor process equipment provided by an embodiment of the present invention;

[0027] Figure 8 This is a schematic diagram of a hardware circuit provided by an embodiment of the present invention;

[0028] Figure 9 This is a schematic diagram of time-domain deviation correction control for a pneumatic valve in a semiconductor process equipment provided by an embodiment of the present invention. Detailed implementation manners

[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Apparently, the described embodiments are some but not all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0030] During the silicon carbide epitaxial process, it mainly includes three steps: substrate pretreatment (Etch), buffer layer growth (Buffer), and epitaxial layer growth (Epi). Among them, in different epitaxial processes, the buffer layer will be grown one or more times to reduce the influence caused by the defects and stresses of the wafer itself and improve the interface quality at the same time; after the buffer layer growth is completed, it enters the epitaxial layer growth stage until the process is completed. Therefore, both the buffer layer and the epitaxial layer are in the epitaxial growth process (both the buffer layer and the epitaxial layer grow SiC), and the main differences lie in parameters such as growth rate, carbon-silicon ratio, and doping concentration. And between different buffer layers, process source gases will be introduced into the vacuum exhaust gas pipeline to adjust and stabilize the flow rates of various process gases, and then introduced into the process chamber for epitaxial growth after the process source gases are stable.

[0031] The existing silicon carbide epitaxial process mainly uses hydrogen H2 as the carrier gas for gas pipeline transportation to carry the C source and Si source gases into the process chamber. Among them, the flow rates of the C source and Si source gases are controlled by a mass flow controller (MFC), and the pipelines through which the gases are introduced are controlled by pneumatic valves.

[0032] The specific silicon carbide epitaxial gas pipeline structure is as Figure 1As shown, C-source and Si-source gases are introduced into the process pipeline (i.e., the RUN pipeline) during the growth process and enter the process chamber, and into the vacuum pipeline (i.e., the VENT pipeline) during the non-growth process to enter the vacuum exhaust gas; MFC3 is the gas mass flow controller corresponding to the Si-source gas (such as SiH4), MFC4 is the gas mass flow controller corresponding to the C-source gas (such as C2H4), pneumatic valve V3 is the control valve for the Si-source gas to enter the RUN pipeline, pneumatic valve V4 is the control valve for the Si-source gas to enter the VENT pipeline, pneumatic valve V5 is the control valve for the C-source gas to enter the RUN pipeline, and pneumatic valve V6 is the control valve for the C-source gas to enter the VENT pipeline. In addition, in the RUN pipeline, there are also MFC1 and pneumatic valve V1 for regulating the flow rate of the process source gas, and in the VENT pipeline, there are also MFC2 and pneumatic valve V2 for regulating the flow rate of the process source gas.

[0033] Specifically, the control process of the pneumatic valves is as Figure 2 shown. First, the software (i.e., the host computer of the semiconductor process equipment) issues valve control signals to the lower computer item by item according to the process menu settings during the execution of the process recipe. Here, the lower computer is a PLC (Programmable Logic Controller); then, the PLC issues control instructions to the pneumatic valve group after the control cycle ends according to the received valve control signals; finally, the pneumatic valve group opens or closes the pneumatic valves (such as Figure 1 V1 - V6 in it) according to the received control instructions to introduce the process source gas into the specified pipeline. Among them, for the non-growth stage, the C-source gas and the Si-source gas are introduced into the VENT pipeline, and only during the growth stage, the C-source gas and the Si-source gas are introduced into the RUN pipeline.

[0034] Therefore, during the silicon carbide epitaxial process, it is necessary to strictly control the introduction amount and introduction rate of the C-source gas and the Si-source gas, and keep the ratio of the two at the required level all the time. When the ratio of the two elements is inconsistent with the process requirements, a large number of defects will occur during the growth process, and such defects are easily replicated layer by layer during the growth process, resulting in abnormal surface defects in the final epitaxial layer. For example, when there is more C-source gas, small pits will appear on the surface of the epitaxial layer, and when there is more Si-source gas, silicon droplets will appear on the surface of the epitaxial layer. Both of these situations will lead to unqualified roughness and defects of the epitaxial layer, and even result in the scrapping of the epitaxial wafer.

[0035] However, in the existing control process of C source gas and Si source gas, the following situations exist: ① The communication cycle from software to PLC is generally more than 100 ms. The valve control signals corresponding to the C source and Si source are sent sequentially. When the valve control signals are not sent in the same cycle, it will cause a time difference of more than 100 ms in the valve control signals of each pneumatic valve sent by the PLC. ② The communication cycle from PLC to the pneumatic valve group is generally more than 20 ms. If the C source and Si source are controlled by different pneumatic valve groups and there is a time difference in the control instructions received by them, it will cause the actions of each pneumatic valve to be unable to be synchronized. ③ If the power transmission from the pneumatic valve group to the pneumatic valve uses compressed nitrogen (CDN), and the CDN pipeline lengths of different pneumatic valves are different, it will also cause a time difference in the actions of each pneumatic valve. ④ The opening and closing action times of different pneumatic valves cannot be made exactly the same, and there are time differences in the switching actions. In addition, the connection points of different gas pipelines to the process pipeline are different, and the distances from the process chamber are also inconsistent, which will also cause a time difference in the process source gas entering the process chamber. These situations will cause unstable differences in the times when the C source gas and Si source gas enter the process chamber, resulting in defect problems in the process.

[0036] To address this problem, the related technical solutions use pneumatic valves with position feedback functions, such as Figure 3 shown, and use the fast response unit of the PLC to collect the opening state signals (i.e., feedback signals) of the pneumatic valves. Before the epitaxial process starts, each pneumatic valve is tested to obtain the time difference between the issuance of the valve control signal and the actual opening of each pneumatic valve. During the epitaxial process, the actual time of issuing the corresponding valve control signal is corrected according to the recorded time differences of each pneumatic valve to ensure that the pneumatic valves corresponding to the C source and Si source open simultaneously.

[0037] However, there is still a time difference when the valve control signal of the pneumatic valve with feedback function is sent to the gas inlet RUN pipeline. Since the feedback signal of the pneumatic valve is connected after the valve body is fully opened, it generally takes dozens of ms for the valve body to be fully opened. However, during the opening process of the pneumatic valve, the source gas pipeline is already connected to the RUN pipeline, and there are action time differences for the pneumatic valves of different source gases. The opening signal of the pneumatic valve cannot accurately represent the time when the source gas enters the RUN pipeline. At the same time, the connection points of different gas pipelines to the RUN pipeline are different, and there are differences in the actual distances from the process chamber. This part of the hardware difference will still cause the C source and Si source to be unable to enter the process chamber simultaneously when the pneumatic valves open simultaneously.

[0038] In addition, during the growth process, the cumulative time difference mentioned above will still lead to the introduction of process defects. Especially in the multi-buffer layer growth process, due to the different growth rates and doping concentrations used in different buffer layers and epitaxial layers, the process source gas will be switched to the VENT pipeline for flow regulation after each growth stage is completed. After the process source gas is stabilized, it will be switched to the RUN pipeline for growth. The switching between the RUN / VENT pipelines will introduce a time-domain deviation of the process source gas introduced due to the opening and closing of the valves, resulting in an increase in defects layer by layer. Eventually, the process results of the epitaxial wafer are prone to abnormal defects. Therefore, how to alleviate the defects in the process results of the epitaxial wafer due to the time-domain offset when the C source and Si source are introduced into the process chamber is an urgent problem to be solved.

[0039] Based on this, the embodiments of the present invention provide a semiconductor process equipment and its pneumatic valve control method. First, determine the target pneumatic valve among multiple pneumatic valves and calculate the first time difference between the target pneumatic valve and the specified pneumatic valve; then, during the process, determine the second time difference between the target pneumatic valve and the specified pneumatic valve; finally, determine the time-domain deviation value according to the first time difference and the second time difference, and control the opening of the target pneumatic valve and the specified pneumatic valve according to the time-domain deviation value, so that the process source gas in the gas pipelines where the target pneumatic valve and the specified pneumatic valve are located reaches the process chamber simultaneously, thereby alleviating the problem of time-domain deviation when multiple process source gases are introduced into the process chamber, and further ensuring the process results of the epitaxial wafer.

[0040] For the convenience of understanding this embodiment, the embodiments of the present invention will be introduced in detail below.

[0041] Embodiment 1

[0042] The embodiments of the present invention provide a pneumatic valve control method for a semiconductor process equipment; among them, as Figure 4 shown, the semiconductor process equipment includes: a process chamber, a process pipeline (i.e., the RUN pipeline) connected to the process chamber, and multiple gas pipelines connected to the process pipeline. A pneumatic valve is provided between each gas pipeline and the process pipeline; by way of example, the gas pipeline corresponding to the C source gas (such as C2H4) (i.e., the gas pipeline between A and B) and the gas pipeline corresponding to the Si source gas (such as SiH4) (i.e., the gas pipeline between C and D) are shown here; among them, a pneumatic valve V5 is provided between the gas pipeline corresponding to the C source gas and the RUN pipeline, which is used to control the opening or closing of the gas pipeline corresponding to the C source gas; similarly, a pneumatic valve V3 is provided between the gas pipeline corresponding to the Si source gas and the RUN pipeline, which is used to control the opening or closing of the gas pipeline corresponding to the Si source gas. It should be noted that the number of gas pipelines can be set according to the number of process source gases required during the process, and the embodiments of the present invention do not limit this.

[0043] Based on the above gas path structure, the pneumatic valve control method of the semiconductor process equipment provided by the embodiment of the present invention is as follows Figure 5 shown, including the following steps:

[0044] Step S502, determine the target pneumatic valve among multiple pneumatic valves, and calculate the first time difference between the target pneumatic valve and the designated pneumatic valve.

[0045] In practical applications, for the pneumatic valves in multiple gas pipelines, the opening and closing action times of each pneumatic valve cannot be exactly the same, and there are time differences in the switching actions. Taking the pneumatic diaphragm valve as an example of the pneumatic valve, its working principle is that when the diaphragm valve opens, compressed air (CDA) or compressed nitrogen (CDN) is used as the power source to offset the internal spring force, drive the diaphragm of the diaphragm valve to move, and connect the upstream and downstream pipelines of the diaphragm valve; when the diaphragm valve closes, the power source is released, and the compressed gas remaining in the valve body is discharged from the inlet, and the internal spring pushes the diaphragm of the diaphragm valve to move, disconnecting the upstream and downstream pipelines of the diaphragm valve. In addition, the action time of the pneumatic diaphragm valve is negatively correlated with the power source pressure when the power source pressure is within the required range (generally 0.4 bar to 0.8 bar), and the higher the pressure, the shorter the action time. Therefore, from the principle of the pneumatic diaphragm valve, it can be seen that the pressure of the power source and the mechanical properties of the internal spring will affect its action time. There is a certain time difference in the action times of different diaphragm valves due to the influence of the power source and the consistency of internal hardware, and this time difference has nothing to do with the pressure difference between the upstream and downstream of the diaphragm valve.

[0046] In order to ensure that multiple process source gases can reach the process chamber simultaneously, it is of great significance to ensure the time consistency of the opening actions of multiple pneumatic valves. For the convenience of description, the embodiment of the present invention first determines the target pneumatic valve among multiple pneumatic valves, and based on the target pneumatic valve, calculates the first time difference between the target pneumatic valve and the designated pneumatic valve, where the designated pneumatic valve is any one of the multiple pneumatic valves other than the target pneumatic valve, and the first time difference is used to characterize the time difference between the time used for the valve opening action of the target pneumatic valve and the time used for the valve opening action of the designated pneumatic valve. It should be noted that when there are multiple designated pneumatic valves, the first time difference between each designated pneumatic valve and the target pneumatic valve is calculated respectively, so as to ensure that the remaining designated pneumatic valves and the target pneumatic valve maintain time consistency during the opening action based on the target pneumatic valve, and alleviate the problem that multiple process source gases cannot reach the process chamber simultaneously due to the time difference in the switching actions of different pneumatic valves.

[0047] Step S504, during the process, determine the second time difference between the target pneumatic valve and the designated pneumatic valve.

[0048] Among them, the second time difference is used to characterize the time difference caused by the distance between the first interface and the second interface for the gas to enter the process chamber. The first interface is the interface where the gas pipeline where the target pneumatic valve is located accesses the process pipeline, and the second interface is the interface where the gas pipeline where the specified pneumatic valve is located accesses the process pipeline. Therefore, through the second time difference, the problem that the process source gas cannot reach the process chamber simultaneously due to different connection points of different gas pipelines accessing the process pipeline is alleviated.

[0049] Step S506, determine the time domain deviation value according to the first time difference and the second time difference.

[0050] Step S508, control the target pneumatic valve and the specified pneumatic valve to open according to the time domain deviation value, so that the process source gas in the gas pipelines where the target pneumatic valve and the specified pneumatic valve are located reaches the process chamber simultaneously.

[0051] The pneumatic valve control method of the semiconductor process equipment provided by the embodiment of the present invention first determines the target pneumatic valve among multiple pneumatic valves and calculates the first time difference between the target pneumatic valve and the specified pneumatic valve; then, during the process, determines the second time difference between the target pneumatic valve and the specified pneumatic valve; finally, determines the time domain deviation value according to the first time difference and the second time difference, and controls the target pneumatic valve and the specified pneumatic valve to open according to the time domain deviation value, so that the process source gas in the gas pipelines where the target pneumatic valve and the specified pneumatic valve are located reaches the process chamber simultaneously, thereby alleviating the problem of time domain deviation when multiple process source gases are introduced into the process chamber, and further ensuring the process result of the epitaxial wafer.

[0052] In one embodiment, the step of calculating the first time difference between the target pneumatic valve and the specified pneumatic valve includes: obtaining the action execution duration of each pneumatic valve; where the action execution duration is used to characterize the duration used for the pneumatic valve to execute the opening action; calculate the first time difference according to the action execution duration of the target pneumatic valve and the action execution duration of the specified pneumatic valve.

[0053] In practical applications, when multiple pneumatic valves are opened simultaneously, due to the influence of the power source and the internal hardware consistency on the action of the diaphragm valve, there is a certain time difference in the execution of the opening action. For the sake of easy explanation, the embodiment of the present invention refers to the duration used for the pneumatic valve to execute the opening action as the action execution duration. Therefore, for the target pneumatic valve and the specified pneumatic valve, the first time difference T can be determined according to the action execution duration of the target pneumatic valve and the action execution duration of the specified pneumatic valve. d where T d can be understood as the time difference caused by the inconsistent valve opening actions when the target pneumatic valve and the specified pneumatic valve are opened simultaneously.

[0054] In one embodiment, each gas pipeline is further provided with a detection device; wherein, the detection device is arranged between the pneumatic valve and the process pipeline; the step of obtaining the action execution duration of each pneumatic valve includes: simultaneously sending multiple opening instructions to enable each pneumatic valve to perform an opening action according to the corresponding opening instruction; for each pneumatic valve, obtaining the current time fed back by the detection device corresponding to the pneumatic valve; wherein, the current time is the time when the temperature difference between both ends of the detection device reaches a preset temperature difference; and, taking the difference between the current time and the sending time of the opening instruction as the action execution duration of the pneumatic valve.

[0055] Specifically, as Figure 4 shown, a detection device is arranged between V3 and the process pipeline, and a detection device is arranged between V5 and the process pipeline. The structures of the two detection devices are the same. The specific number of detection devices can be set according to the number of gas pipelines or pneumatic valves. It should be noted that the detection device can be arranged not only between the pneumatic valve and the process pipeline, but also upstream of the pneumatic valve, and can be specifically set according to the actual situation.

[0056] In practical applications, for any detection device, as Figure 6 shown, the detection device includes: a control module 61, a heating element H, a first detection element Ra upstream of the heating element H, and a second detection element Rb downstream of the heating element H; here, the first detection element Ra and the second detection element Rb are preferably high-precision thermistors, and the heating temperature of the heating element H is higher than the source gas temperature. Here, the source gas temperature refers to the temperature of the process source gas in the gas pipeline, generally room temperature. The control module 61 is used to control the heating power of the heating element H and detect the temperatures fed back by the first detection element Ra and the second detection element Rb. In practical applications, the heating element H, the first detection element Ra, and the second detection element Rb are all installed at the central position of the corresponding gas pipeline. The external is wrapped with a 316L stainless steel protective sleeve 62 for isolating the process source gas. A good insulating and heat-conducting material is filled between the element and the protective sleeve. The protective sleeve and the detection device pipeline are welded for ensuring airtightness, and the detection device and the gas pipeline are connected using a VCR joint. It should be noted that in the detection device, the distances between the various elements need to be short to reduce the internal volume of the detection device, thereby reducing the process source gas ratio error in the process chamber caused by the internal stored gas, and further ensuring the process result of the epitaxial wafer.

[0057] In addition, for the detection device, when the gas in the gas pipeline is relatively static, the upstream and downstream temperatures in the pipeline are symmetrically distributed with the heating element H as the center, and the temperature difference ΔT between the first detection element Ra and the second detection element Rb remains unchanged; when the gas in the gas pipeline flows from upstream to downstream (as Figure 6When the arrow direction in [Figure] is such that the heat of the heating element H is carried by the gas in the downstream direction, the temperature difference ΔT between the first detection element Ra and the second detection element Rb becomes larger. Therefore, according to the following formula (1), when the power of the heating element H remains unchanged and the product of the gas flow rate and specific heat capacity flowing through the detection device remains unchanged, the temperature difference between the first detection element Ra and the second detection element Rb in the detection device is constant. That is, when the product of the gas flow rate and specific heat capacity introduced is the same, the change in the temperature difference (i.e., the temperature difference) between the front and rear ends of the detection device within the same time is the same.

[0058] P = m × Cp × ΔT (1)

[0059] Wherein, P represents the heating power of the heating element H, m represents the gas mass flow rate, Cp represents the gas specific heat capacity, and ΔT represents the temperature difference between the two ends of the detection device, that is, the temperature difference between the first detection element Ra and the second detection element Rb.

[0060] Therefore, when the lower computer such as a PLC simultaneously issues multiple opening instructions to the pneumatic valve group, the pneumatic valve group controls the corresponding pneumatic valve to perform the opening action according to the opening instructions; at this time, for any pneumatic valve, the PLC obtains the current time fed back by its corresponding detection device; here, the current time is the time when the temperature difference between the two ends of the detection device reaches the preset temperature difference; and the difference between the current time and the time when the opening instruction is issued is used as the action execution duration of the pneumatic valve. That is, under the same temperature difference, the current time corresponding to each pneumatic valve is different due to the inconsistent actions of the diaphragm valves. Since the opening instructions are issued simultaneously, the action execution duration of different pneumatic valves can be confirmed according to the current time and the time when the opening instruction is issued.

[0061] It should be noted that the above preset temperature difference can be 10% of the steady-state temperature change value at the maximum ventilation volume, or can be adjusted adaptively according to the actual situation. The embodiments of the present invention do not limit this.

[0062] In one embodiment, before the step of simultaneously issuing multiple opening instructions, the method further includes: controlling the gas pipelines where the multiple pneumatic valves are located to meet preset conditions; wherein, the preset conditions include: the product of the flow rate and specific heat capacity of the process source gas corresponding to each gas pipeline is a preset value. Therefore, through the preset conditions, it is ensured that the heat carried away by the gas introduced into the multiple pneumatic valves within the same time is the same. At this time, the current time is only related to the inconsistent opening execution actions of the pneumatic valves, thereby ensuring the accuracy of determining the action execution duration of the pneumatic valves, further ensuring the control accuracy of the time-domain deviation correction of the pneumatic valves, and further ensuring the process results of the epitaxial wafers.

[0063] For the sake of understanding, here, such as Figure 4Taking the pneumatic valve V5 corresponding to the C source gas and the pneumatic valve V3 corresponding to the Si source gas as examples, the specific process of obtaining the execution time of the actions of V3 and V5 is described. Specifically, the following steps are included:

[0064] Step A1. Before testing, first open the pneumatic valve V1 of the RUN pipeline and the pneumatic valve V2 of the VENT pipeline, and set the flow of MFC1 and MFC2 to the process flow, and keep the pressure of the process chamber to the process pressure, so that the states of the RUN pipeline and the VENT pipeline are close to the process.

[0065] Step A2, open the pneumatic valve V6 for the C source gas to enter the VENT pipeline and the pneumatic valve V4 for the Si source gas to enter the VENT pipeline, and set the flow rates of MFC3 and MFC4 respectively until the C source gas flow rate × C source gas specific heat capacity = Si source gas flow rate × Si source gas specific heat capacity. At this time, the gases (i.e., process source gases) introduced by V6 and V4 take away the same amount of heat in the same time, that is, the rates at which the two gases take away heat when flowing through the detection device are the same.

[0066] Step A3: After the flow rates of the C source gas and the Si source gas are stabilized, close V6 and V4 at the same time.

[0067] Step A4, PLC simultaneously issues an opening instruction to simultaneously open the pneumatic valve V5 for the C source gas to enter the RUN pipeline and the pneumatic valve V3 for the Si source gas to enter the RUN pipeline, and records the issuance time Ts of the opening instruction.

[0068] Step A5: For the detection device on the gas pipeline of the C source gas, the control module detects the temperature difference at both ends of the detection device, and takes 10% of the steady-state temperature change value at the maximum ventilation volume as the preset temperature difference. When the temperature difference reaches the preset temperature difference, the control module records the current time Tc at this time, and sets the current time T C Feedback to PLC; Similarly, for the detection device on the gas pipeline of Si source gas, when its control module detects that the temperature difference between its two ends reaches the preset temperature difference, the current time T at this time is recorded. Si , and the current time T Si Feedback to PLC.

[0069] Step A6: PLC issues a closing command to close all pneumatic valves such as V1 to V6 and all MFCs such as MFC1 to MFC4, and turns T C -Ts is used as the action execution time of the pneumatic valve V5. Si -Ts is the action execution time of the pneumatic valve V3; and when V3 is the target pneumatic valve and V5 is the designated pneumatic valve, according to T C - Ts and T Si- Ts can obtain the valve time difference between V5 and V3, i.e., the first time difference T d , where the first time difference T d is the time difference caused by the inconsistency of the internal power source and hardware of the pneumatic valve when the diaphragm valves of V3 and V5 perform the opening action.

[0070] In addition, in the above process, the opening instructions corresponding to V3 and V5 must be sent by the PLC simultaneously, and the feedback signal sampling periods of the C-source gas and Si-source gas introduced into the corresponding detection devices should be as short as possible to avoid affecting the measurement accuracy. To meet this condition, V3 and V5 can be connected to the pneumatic valve group using hard wires respectively, and the opening instructions are sent by the PLC in the same control cycle and the current time is recorded using an interrupt instruction. The stable cycle time characteristic of the PLC itself ensures that the two control instructions are sent simultaneously; in addition, the feedback signal is connected to the high-speed sampling unit of the PLC, and an interrupt instruction is used to calculate the time from the instruction issuance to the receipt of the feedback signal, so as to achieve a time calculation accuracy of the microsecond level, ensure the detection accuracy of the action execution duration of each pneumatic valve, further guarantee the time-domain deviation correction control accuracy of the pneumatic valve, and thus improve the process result of the epitaxial wafer.

[0071] In one embodiment, the steps of determining the second time difference between the target pneumatic valve and the designated pneumatic valve include: obtaining the detection parameters of the process pipeline; wherein, the detection parameters include: the actual temperature of the carrier gas, the actual pressure of the pipeline, the carrier flow rate, and the flow rates of various process source gases; calculating the second time difference between the target pneumatic valve and the designated pneumatic valve according to the detection parameters and the preset basic parameters; wherein, the preset basic parameters include: the standard temperature, the standard air pressure, the pipeline cross-sectional area, and the pipeline distance difference, and the pipeline distance difference is the distance between the first interface and the second interface.

[0072] In practical applications, due to the distance difference between the interfaces of any two gas pipelines and the process pipeline, even if the process source gases corresponding to the two gas pipelines enter the process pipeline simultaneously, there is still a time difference when entering the process chamber, and this time difference is positively correlated with the carrier flow rate. Therefore, after determining the target pneumatic valve, it is also necessary to calculate the time difference caused by the pipeline distance difference between the gas pipeline where any other pneumatic valve is located and the gas pipeline where the target pneumatic valve is located according to the detection parameters and the preset basic parameters, that is, to calculate the second time difference between the target pneumatic valve and the designated pneumatic valve. The calculation formula of the second time difference is as follows:

[0073]

[0074] where L represents the pipeline distance difference, P1 represents the actual pressure of the pipeline, P0 represents the standard air pressure, T0 represents the standard temperature, T0 is equal to 273.15K, T1 represents the actual temperature of the carrier gas, F1 represents the carrier flow rate, F2~F nrepresents the flow rates of multiple process source gases, n is a positive integer greater than 2, S represents the cross-sectional area of the pipeline, T l represents the second time difference.

[0075] In practical applications, such as Figure 4 shown, the carrier gas flow rate F1 can be measured by the MFC1 set on the process pipeline, the actual temperature T1 of the carrier gas can be detected by a temperature sensor, and the actual pressure P1 of the pipeline can be detected by a corresponding pressure sensor. Here, the temperature sensor and the pressure sensor can be set at the front end of MFC1 in the process pipeline ( Figure 4 not shown in the figure), and the flow rates F2 to F of multiple process source gases n can be detected by the MFCs in their corresponding gas pipelines respectively. Therefore, through the above formula (2), the second time difference between the specified pneumatic valve and the target pneumatic valve can be calculated.

[0076] It should be noted that the second time difference T here l can be understood as the time difference in the entry of the process source gases in the two gas pipelines caused by the pipeline distance difference L between the gas pipeline where the target pneumatic valve is located and the gas pipeline where the specified pneumatic valve is located. Exemplarily, as Figure 4 shown, when the target pneumatic valve is V3 and the specified pneumatic valve is V5, at this time, the pipeline distance difference L is the distance between the first interface and the second interface, that is, the distance between point D and point B.

[0077] Therefore, when the specified pneumatic valve is different, the pipeline distance difference L is also different, and the second time difference T between the target pneumatic valve and the specified pneumatic valve l is also different. When based on the target pneumatic valve, the time domain deviation values corresponding to each specified pneumatic valve are also different. Therefore, when performing time domain deviation correction control on the specified pneumatic valve according to the time domain deviation value, it is possible to make the process source gas in the gas pipeline where the specified pneumatic valve is located and the process source gas in the gas pipeline where the target pneumatic valve is located reach the process chamber simultaneously, alleviating the problem of time domain deviation in the introduction of multiple process source gases into the process chamber, and further ensuring the process result of the epitaxial wafer.

[0078] In one embodiment, the steps of controlling the opening of the target pneumatic valve and the specified pneumatic valve according to the time domain deviation value include: controlling the opening of the target pneumatic valve and recording the first duration after opening; when the first duration reaches the time domain deviation value, controlling the opening of the specified pneumatic valve.

[0079] Specifically, after determining the time-domain deviation value between the target pneumatic valve and the specified pneumatic valve, first control the target pneumatic valve to open, and record the duration after opening, which is the first duration; when the first duration reaches the time-domain deviation value, then control the specified pneumatic valve to open, so that the process source gas in the gas pipeline where the specified pneumatic valve is located and the process source gas in the gas pipeline where the target pneumatic valve is located can reach the process chamber simultaneously.

[0080] For example, as Figure 4 shown, when the target pneumatic valve is V3 and the specified pneumatic valve is V5, according to the first time difference T d and the second time difference T l the time-domain deviation value T a can be determined, that is, T a = T d + T l ; this time-domain deviation value T a can be understood as the time difference caused by hardware differences when the control instructions of the C source and the Si source can be issued simultaneously during the control process; at this time, first control V3 to open, and after an extension of T a control V5 to open, so that the process source gases corresponding to the C source and the Si source reach the process chamber simultaneously, thus ensuring the process result of the epitaxial wafer.

[0081] In addition, when there are multiple specified pneumatic valves, each specified pneumatic valve corresponds to a time-domain deviation value. At this time, the process of controlling the opening of multiple pneumatic valves according to multiple time-domain deviation values is as follows: sort the multiple time-domain deviation values in ascending order, and after the target pneumatic valve is opened, when the first duration reaches the first time-domain deviation value, control the specified pneumatic valve corresponding to the first time-domain deviation value to open, and when the first duration reaches the second time-domain deviation value, control the specified pneumatic valve corresponding to the second time-domain deviation value to open; and so on, until the first duration reaches the last time-domain deviation value, control the specified pneumatic valve corresponding to the last time-domain deviation value to open. Therefore, by performing time-domain deviation correction control on multiple pneumatic valves according to the corresponding time-domain deviation values, multiple process source gases in the gas pipelines where the multiple pneumatic valves are located enter the process chamber simultaneously, thus solving the problem of time-domain deviation when multiple process source gases are introduced into the process chamber and ensuring the process result of the epitaxial wafer.

[0082] Similarly, the method further includes: when controlling the target pneumatic valve to close, record the second duration after closing; when the second duration reaches the time-domain deviation value, control the specified pneumatic valve to close.

[0083] Specifically, when the process flow (or the current process step) ends, it is necessary to control multiple pneumatic valves to close at this time. Among them, during the closing process, first control the target pneumatic valve to close and record the second duration after closing; when the second duration reaches the time domain deviation value, then control the specified pneumatic valve to close, thus avoiding the situation where the proportion of the process source gas in the gas pipeline where the specified pneumatic valve is located and the process source gas in the gas pipeline where the target pneumatic valve is located in the process chamber is inconsistent with the process requirements during the closing processes of the target pneumatic valve and the specified pneumatic valve, avoiding the influence of the residual process source gas in the process chamber on the epitaxial wafer in the chamber and even on the next process step, effectively reducing the number of defects generated during the process, and thus further ensuring the process result of the epitaxial wafer.

[0084] In addition, for the case of multiple specified pneumatic valves, the process of controlling the closing of multiple pneumatic valves according to multiple time domain deviation values is as follows: sort the multiple time domain deviation values in ascending order, and after the target pneumatic valve is closed, when the second duration reaches the first time domain deviation value, control the specified pneumatic valve corresponding to the first time domain deviation value to close, and when the second duration reaches the second time domain deviation value, control the specified pneumatic valve corresponding to the second time domain deviation value to close; and so on, until the second duration reaches the last time domain deviation value, control the specified pneumatic valve corresponding to the last time domain deviation value to close. Therefore, through the time domain deviation correction control of multiple pneumatic valves according to the corresponding time domain deviation values, the situation where the proportion of multiple process source gases in the process chamber is inconsistent with the process requirements during the closing processes of multiple pneumatic valves is avoided, avoiding the influence of the residual process source gas in the process chamber on the epitaxial wafer in the chamber and even on the next process step, effectively reducing the number of defects generated during the process, and thus further ensuring the process result of the epitaxial wafer.

[0085] Therefore, for the pneumatic valves in multiple gas pipelines, first determine the target pneumatic valve among multiple pneumatic valves, and calculate the first time difference and the second time difference between the target pneumatic valve and each specified pneumatic valve, so as to determine the time domain deviation value of each specified pneumatic valve relative to the target pneumatic valve according to the first time difference and the second time difference, and perform opening or closing control on the specified pneumatic valve and the target pneumatic valve according to the time domain deviation value, so that multiple process source gases reach the process chamber simultaneously, not only alleviating the problem of time domain deviation when multiple process source gases are introduced into the process chamber, but also avoiding the situation where the proportion of multiple process source gases is inconsistent with the process requirements during the closing process of the pneumatic valve, and avoiding the influence of the residual process source gas in the process chamber on the epitaxial wafer in the chamber and even on the next process step, effectively reducing the number of defects generated during the process, and thus ensuring the process result of the epitaxial wafer.

[0086] In one embodiment, the step of determining a target pneumatic valve among a plurality of pneumatic valves includes: calculating the distance from each pneumatic valve to the process chamber, and taking the pneumatic valve with the maximum distance as the target pneumatic valve.

[0087] Specifically, when a plurality of pneumatic valves complete the opening action simultaneously, due to the different distances of each pneumatic valve from the process chamber, as Figure 4 shown, V5 is closer to the process chamber, and V3 is farther from the process chamber. At this time, after the C-source gas and the Si-source gas respectively pass through V5 and V3 simultaneously, due to the different distances of the pneumatic valves from the process chamber, there is still a time difference in the entry of the C-source gas and the Si-source gas into the process chamber. Considering that the process source gas in the gas pipeline where the pneumatic valve with a longer distance is located takes a longer time to enter the process chamber, therefore, in the process, the pneumatic valve with the maximum distance is taken as the target pneumatic valve, and time-domain deviation correction control is performed on the specified pneumatic valve according to the time-domain deviation value, so that the process source gases in the gas pipelines where the target pneumatic valve and the specified pneumatic valve are located reach the process chamber simultaneously, thereby alleviating the problem of time-domain deviation in the introduction of multiple process source gases into the process chamber, and further ensuring the process result of the epitaxial wafer.

[0088] In one embodiment, the step of determining a target pneumatic valve among a plurality of pneumatic valves includes: taking the pneumatic valve with the maximum action execution duration as the target pneumatic valve.

[0089] In practical applications, for a plurality of pneumatic valves, when they are opened simultaneously, due to the time difference in the opening action of the diaphragm, there may be a time-domain deviation in the arrival of the process source gas in the corresponding gas pipeline at the process chamber. Considering that the process source gas in the gas pipeline where the pneumatic valve with a longer action execution duration is located takes a longer time to enter the process chamber, therefore, before the process starts, for a plurality of pneumatic valves, the pneumatic valve with the maximum action execution duration is taken as the target pneumatic valve, and time-domain deviation correction control is performed on the specified pneumatic valve according to the time-domain deviation value, so that the process source gases in the gas pipelines where the target pneumatic valve and the specified pneumatic valve are located reach the process chamber simultaneously, avoiding the problem of time difference in the entry of multiple process source gases into the process chamber due to different action execution durations of different pneumatic valves, thereby ensuring the process result of the epitaxial wafer.

[0090] It should be noted that in some scenarios, the target pneumatic valve can also be determined jointly according to the action execution duration of each pneumatic valve and its distance from the process chamber; for example, the weights of the action execution duration and the distance are respectively set, and the corresponding values are calculated according to the action execution duration, the distance and the corresponding weights, and the pneumatic valve with the maximum value is taken as the target pneumatic valve. The specific method for determining the target pneumatic valve can be set according to the actual situation, and the embodiments of the present invention do not limit this.

[0091] Embodiment 2

[0092] Based on the above method embodiments, the embodiments of the present invention further provide another method for controlling a pneumatic valve of a semiconductor process equipment. This method focuses on the time-domain deviation correction control process of the pneumatic valve V5 on the gas pipeline corresponding to the C source gas and the pneumatic valve V3 on the gas pipeline corresponding to the Si source gas in the silicon epitaxy process. Figure 4 In the process shown in

[0093] As shown in Figure 7 , this method includes the following steps:

[0094] Step S702, equipment initialization; in the initialization of the semiconductor process equipment, the action execution durations of V3 and V5 are respectively detected by a detection device. Specifically, reference can be made to the foregoing embodiments, and the embodiments of the present invention will not elaborate in detail herein.

[0095] Step S704, calculate the first time difference T d between V3 and V5; that is, determine the first time difference caused by the inconsistent actions of the diaphragm valves between V3 and V5 according to the action execution durations of V3 and V5.

[0096] Step S706, obtain the process recipe.

[0097] Specifically, before the process starts, the host computer (i.e., software) sends the process recipe (Recipe) to the lower computer (such as PLC), and the PLC executes the process recipe, thereby eliminating the unstable time difference in the communication between the host computer and the PLC. In addition, the PLC is a periodic operation system, and all outputs are refreshed at the same time in the same cycle, thereby ensuring the synchronization of control instructions, such as the synchronization of the opening instructions for V3 and V5.

[0098] Step S708, execute the current process step Step i ; where the process recipe includes multiple process steps Step. Here, the current process step Step i is elaborated, and i is any value between 1 and M, where M represents the total number of process steps in the process recipe.

[0099] Step S710, set the target pneumatic valve as V3, and calculate the second time difference T l between V3 and V5; specifically, the determination process of the target pneumatic valve and the calculation process of the second time difference T l can refer to the foregoing embodiments, and the embodiments of the present invention will not elaborate in detail herein.

[0100] Step S712, calculate the time-domain deviation value T d according to T l and T a .

[0101] Step S714, control V3 to open; at this time, control the pneumatic valve V4 between the gas pipeline and the VENT pipeline to close.

[0102] Step S716, the delay time reaches T a .

[0103] Step S718, control V5 to open; at this time, control the pneumatic valve V6 between the gas pipeline and the VENT pipeline to close, so that the C-source gas and the Si-source gas can reach the process chamber through the RUN pipeline simultaneously during the growth process, and control the process chamber according to the current process step Step i to process the wafer.

[0104] Step S720, Step i ends.

[0105] Step S722, control V3 to close; and control the pneumatic valve V4 between the gas pipeline and the VENT pipeline to open.

[0106] Step S724, the delay time reaches T a .

[0107] Step S726, control V5 to close; at this time, control the pneumatic valve V6 between the gas pipeline and the VENT pipeline to open, so that the C-source gas and the Si-source gas can enter the vacuum exhaust gas through the VENT pipeline during the non-growth process; and let i = i + 1, return to Step S708 to execute the next process step Step i+1 , until all the process steps in the process recipe are completed.

[0108] In the existing technical solution, the control instruction of the pneumatic valve is sent from the host computer to the PLC and executed in the PLC. However, the control period of the software is affected by its own architecture, and it is impossible to ensure that the control instructions are sent simultaneously. Moreover, there is a random deviation in the communication between the software and the PLC, that is, there is a control time-domain deviation value T caused by software control in the existing technical solution r , and this deviation value is a random quantity and cannot be effectively compensated.

[0109] Based on this, in order to simultaneously issue the control instructions for the C source and the Si source, meet the measurement conditions and compensation requirements of the time-domain correction value, the embodiment of the present invention optimizes the control process of the C source and the Si source, transfers the control of the process recipe from the software to the PLC, and realizes the synchronous issuance of instructions by virtue of the stable operation cycle of the PLC system, thereby eliminating the unstable time difference in the communication between the host computer and the PLC and ensuring that multiple process source gases reach the process chamber simultaneously.

[0110] In addition, for multiple process steps in the process recipe, the second time difference T corresponding to the specified pneumatic valve in each process step is calculated according to the detection parameters of the process pipeline and the preset basic parameters in each process step l , and based on T d and T l the time domain deviation value T corresponding to the specified pneumatic valve in each process step is determined a , so that the specified pneumatic valve is controlled to be switched on and off according to the corresponding time domain deviation value T a in each process step. This not only ensures that in each process step, the process source gas in the gas pipeline where the specified pneumatic valve is located and the process source gas in the gas pipeline where the target pneumatic valve is located reach the process chamber simultaneously in each process step, but also alleviates the defects caused by some gases remaining in the process chamber due to the process step switching, thereby ensuring the process results of the epitaxial wafer.

[0111] It should be noted that the above method is not only applicable to the silicon carbide epitaxial process, but also applicable to the time domain deviation problems in various compound epitaxies.

[0112] Embodiment III

[0113] The embodiment of the present invention further provides a semiconductor process equipment, including: a lower computer, a process chamber, a process pipeline connected to the process chamber, and a plurality of gas pipelines connected to the process pipeline. A pneumatic valve is provided between each gas pipeline and the process pipeline; wherein, when the lower computer works, it executes the above method embodiment.

[0114] Wherein, the semiconductor process equipment further includes a plurality of pneumatic valve groups, and the pneumatic valve groups are provided in one-to-one correspondence with the pneumatic valves; the pneumatic valve groups are used to obtain the opening instruction sent by the lower computer and control the corresponding pneumatic valve to execute the opening action according to the opening instruction.

[0115] In addition, a detection device is respectively provided between each pneumatic valve and the process pipeline; wherein, the detection device includes: a control module, a heating element, and a first detection element upstream of the heating element and a second detection element downstream of the heating element; the control module is used to control the heating power of the heating element and detect the temperature difference between the first detection element and the second detection element when the pneumatic valve executes the opening action; and, when the temperature difference reaches the preset temperature difference, record the current time and feedback the current time to the lower computer; at this time, the lower computer is further used to obtain the current time and calculate the action execution duration of the pneumatic valve according to the current time and the issuing time of the opening instruction. The specific detection device can refer to the foregoing embodiment, and the embodiment of the present invention will not be elaborated in detail here.

[0116] It should be noted that the above detection device is as follows Figure 6In addition to the device shown, pressure detection devices, flow detection devices, gas analyzers and other devices can be used for replacement. After replacement, the calculation logic of the time domain deviation value needs to be corrected according to the device principle. For example, the pressure detection device needs to introduce temperature and pipeline volume parameters to calculate the actual gas volume introduced corresponding to the pressure change; the flow monitoring device needs to integrate the flow rate of the process source gas introduced and calculate the total amount introduced per unit time; the gas analyzer needs to introduce the pipeline volume and the current concentration of the internal gas and calculate the total amount introduced per unit time according to the concentration change. Such devices may lose some detection accuracy due to reasons such as response time and threshold setting, but can still play a replacement role to a certain extent. The specific working process can refer to the detection device in the embodiment of the present invention and make adaptive adjustments, which will not be elaborated in detail in the embodiment of the present invention.

[0117] Further, most of the control methods of existing pneumatic valves adopt a pneumatic valve group with network communication, generally based on Devicenet, and the time delay affected by the communication cycle is about 20 ms to 100 ms. The fastest EtherCAT bus generally also has a deviation of 2 ms to 5 ms, and there are also control deviations inside the valve group in the form of communication, generally within 10 ms.

[0118] Based on this, in order to ensure the deviation correction time domain control accuracy between pneumatic valves, in the embodiment of the present invention, a hard-wired method is adopted, and the PLC digital output DO module directly drives the pneumatic valve group and directly controls the pneumatic valve group to avoid the random delay caused by communication. The electrical signal is generally considered to be transmitted at the speed of light in a good conductor; and when the control instruction is issued, the PLC built-in interrupt instruction is used for execution to obtain the control accuracy at the ms level; if a higher time domain control accuracy is required for the process, such as the control accuracy at the us level, a hardware circuit scheme can be adopted to control the pneumatic valve group and minimize the control chip and communication protocol as much as possible.

[0119] Specifically, the hardware circuit is as Figure 8 shown. The PLC DO is the digital output module of the PLC control system, the EN signal is the enable signal, the Ta SP is the counter setting value calculated from the time domain deviation value (i.e., the time domain deviation value between V3 and V5), and this setting value is equal to the time domain deviation value Ta * crystal oscillator frequency; the crystal oscillator is the clock signal source of the hardware circuit; the start / stop timer is a hardware counter used to accurately measure the number of pulses required for deviation correction; NOT is a NOT gate logic circuit; SR is a Set / Reset gate logic circuit; SET is the enable input signal of the SR gate circuit; RST is the reset input signal of the SR gate circuit, and CLK represents the clock signal.

[0120] Based on the above hardware circuit, the time-domain deviation correction control process of the pneumatic valve is as follows: ① The time-domain deviation value Ta is calculated by the high-speed sampling module and interrupt instruction of the PLC; ② According to the time-domain control requirements, the hardware circuit is designed. Taking the control accuracy at the microsecond level as an example, a 1 MHz crystal oscillator is selected as the clock source of the hardware counter; ③ At the beginning of the process step Step, the PLC DO outputs a high-level EN signal to start the timing counter, and at the same time, this signal is used as the opening control signal of the Si source valve V3 to open V3; ④ The opening timing counter counts according to the clock signal (i.e., CLK). When the opening timing counter reaches the time-domain deviation value Ta, it outputs a SET signal to SR. At this time, SR outputs a high-level enable signal EN to open the C source valve V5; ⑤ At the end of the process step Step, the PLC DO outputs a low-level EN signal. At this time, the Si source valve V3 closes according to the low-level EN signal. At the same time, the low-level EN signal is inverted by NOT to become a high-level EN signal. At this time, the inverted high-level EN signal is used as the enable signal to close the timing counter; ⑥ The closing timing counter counts according to the clock signal (i.e., CLK). When the closing timing counter reaches the time-domain deviation value Ta, it outputs a RST signal to SR. At this time, SR outputs a low-level enable signal EN to close the C source valve V5.

[0121] Therefore, this control scheme can implement an accurate time-domain deviation correction control algorithm for the C source and Si source. Due to the periodic cyclic execution characteristic of the PLC, its output signal will be uniformly refreshed at the end of each cycle, resulting in the actual compensation time exceeding the required deviation correction time. The maximum theoretical error is 1 PLC clock cycle, and there is clock jitter in the PLC. Even if the time-domain compensation value is an integer multiple of the PLC clock cycle, there may still be a control error of 1 PLC clock cycle. Therefore, PLC control can only meet the control accuracy at the millisecond level. The above hardware circuit is implemented by a combination of various logic gate integrated circuits. Compared with the PLC, its control accuracy only depends on the crystal oscillator frequency and is proportional to the crystal oscillator frequency. The crystal oscillator frequency of a common hardware circuit can reach dozens of MHz or more. Taking a 10 MHz crystal oscillator as an example, the pulse signal period is 0.1 us, which can meet the requirement that the control time-domain error is less than 1 us (generally, it is considered that the control accuracy is better than the required accuracy by one order of magnitude to meet the control requirements).

[0122] Furthermore, based on the above hardware circuit, combined with the time-domain deviation correction control algorithm, the microsecond-level control of the pneumatic valve can be realized, and the semiconductor process equipment also meets the synchronization requirements of different process sources entering the process chamber for different process requirements.

[0123] Specifically, such as Figure 9As shown in the figure, the software is the host computer of the semiconductor process equipment, and the Recipe is the process recipe, which is transmitted by the software to the PLC before the process starts; the PLC is the lower computer, which is used to calculate the time domain deviation value and issue the time domain deviation correction enable signal; the high-speed IO acquisition unit is a high-speed response digital quantity acquisition module, which is used to collect the feedback signal of the detection device and transmit the signal to the PLC; here, the detection device is a flow detection device, which is used to detect the flow rate of the process source gas and feed the detected flow rate back to the PLC through the high-speed IO acquisition unit, so that the PLC can determine the time domain deviation value Ta of the corresponding pneumatic valve (i.e., the specified pneumatic valve) according to the detected flow rate.

[0124] During the process, the PLC can directly implement the deviation correction control of the pneumatic valve through the pneumatic valve group according to the time domain deviation value Ta, but this PLC control can only meet the control accuracy of the ms level. In addition, the PLC can also implement the deviation correction control of the pneumatic valve through the hardware circuit. The hardware circuit performs time domain deviation correction control according to the process step execution (Step RUN) and the time domain deviation correction enable signal issued by the PLC, and issues the control signal corresponding to the time domain deviation value Ta to the pneumatic valve group; the pneumatic valve group uses hard wiring to implement the control of the pneumatic valve. When receiving the digital quantity control signal issued by the hardware circuit, it operates the corresponding CDN gas path to make the pneumatic valve perform the switch action, realizing the deviation correction control of the pneumatic valve with the control accuracy of the us level.

[0125] In addition, through the detection device, it is possible to accurately measure the time difference between the issuance of the valve control signal and the actual entry of the process source gas into the RUN pipeline, and at the same time, the accurate control time difference caused by the hardware differences of different gas pipelines can be obtained and used for the time domain deviation correction control of the pneumatic valve. In addition, through the hardware circuit, it is possible to accurately compensate the domain offset when different process source gases are introduced into the process chamber due to various controls and hardware differences, effectively reducing the number of defects generated during the process.

[0126] It should be noted that, in addition to the structure shown in Figure 8 the above hardware circuit can also use control schemes such as FPGA (Field Programmable Gate Array), embedded hardware controller, high-speed logic controller, etc. to replace. The control logic after replacement can be implemented in the above controllers. Among them, the FPGA only needs to consider the influence factor of the crystal oscillator frequency, and control schemes such as high-speed logic controller or PLC need to reduce the control cycle and bus delay as much as possible to reduce the influence caused by the time domain deviation value introduced by the controller.

[0127] The semiconductor process equipment provided by the embodiment of the present invention has the same technical features as the pneumatic valve control method of the semiconductor process equipment provided by the above embodiment, so it can also solve the same technical problems and achieve the same technical effects.

[0128] An embodiment of the present invention further provides a lower computer, which includes a processor and a memory. The memory stores machine-executable instructions that can be executed by the processor, and the processor executes the machine-executable instructions to implement the pneumatic valve control method for the semiconductor process equipment described above.

[0129] This embodiment also provides a machine-readable storage medium. The machine-readable storage medium stores machine-executable instructions. When the machine-executable instructions are called and executed by the processor, the machine-executable instructions prompt the processor to implement the pneumatic valve control method for the semiconductor process equipment described above.

[0130] The computer program product of the semiconductor process equipment and its pneumatic valve control provided by the embodiment of the present invention includes a computer-readable storage medium storing program code. The instructions included in the program code can be used to execute the method described in the foregoing method embodiments. For specific implementation, reference can be made to the method embodiments, which will not be elaborated here.

[0131] Those skilled in the art can clearly understand that for the convenience and conciseness of description, the specific working processes of the systems and devices described above can refer to the corresponding processes in the foregoing method embodiments, which will not be elaborated here.

[0132] In addition, in the description of the embodiments of the present invention, unless otherwise clearly specified and limited, the terms "installation", "connection", and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0133] If the above functions are implemented in the form of software function units and sold or used as independent products, they can be stored in a non-volatile computer-readable storage medium executable by a processor. Based on such an understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or a part of this technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions to enable a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in the embodiments of the present invention. The foregoing storage medium includes: various media such as USB flash drives, mobile hard disks, read-only memories (ROM, Read-Only Memory), random access memories (RAM, Random Access Memory), magnetic disks, or optical discs that can store program code.

[0134] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present invention. In addition, the terms "first", "second", "third" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0135] Finally, it should be noted that the above-described embodiments are only specific embodiments of the present invention, which are used to illustrate the technical solutions of the present invention, rather than limiting them. The protection scope of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that any person skilled in the art within the technical scope disclosed by the present invention can still modify the technical solutions described in the foregoing embodiments, or can easily conceive of changes, or make equivalent replacements for some of the technical features; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the protection scope of the claims.

Claims

1. A pneumatic valve control method for a semiconductor process equipment, the semiconductor process equipment comprising: A process chamber, a process pipeline connected to the process chamber, and a plurality of gas pipelines connected to the process pipeline. A pneumatic valve is provided between each of the gas pipelines and the process pipeline. It is characterized in that the method includes: Determining a target pneumatic valve among the plurality of pneumatic valves, and calculating a first time difference between the target pneumatic valve and a specified pneumatic valve; wherein, the specified pneumatic valve is any one of the plurality of pneumatic valves other than the target pneumatic valve, and the first time difference is used to characterize the time difference between the valve opening action time of the target pneumatic valve and the valve opening action time of the specified pneumatic valve; During the process, determining a second time difference between the target pneumatic valve and the specified pneumatic valve; wherein, the second time difference is used to characterize the time difference for gas to enter the process chamber due to the distance between a first interface and a second interface. The first interface is the interface where the gas pipeline where the target pneumatic valve is located leads into the process pipeline, and the second interface is the interface where the gas pipeline where the specified pneumatic valve is located leads into the process pipeline; Determining a time domain deviation value according to the first time difference and the second time difference; Controlling the opening of the target pneumatic valve and the specified pneumatic valve according to the time domain deviation value, so that the process source gas in the gas pipelines where the target pneumatic valve and the specified pneumatic valve are located reaches the process chamber simultaneously.

2. The method according to claim 1, characterized in that, The step of calculating the first time difference between the target pneumatic valve and the specified pneumatic valve includes: Obtaining the action execution duration of each pneumatic valve; wherein, the action execution duration is used to characterize the duration of the pneumatic valve performing the opening action; Calculating the first time difference according to the action execution duration of the target pneumatic valve and the action execution duration of the specified pneumatic valve.

3. The method according to claim 2, wherein Each of the gas pipelines is further provided with a detection device; wherein, the detection device is arranged between the pneumatic valve and the process pipeline. The step of obtaining the action execution duration of each pneumatic valve includes: Simultaneously issuing a plurality of opening instructions, so that each pneumatic valve performs an opening action according to the corresponding opening instruction; For each pneumatic valve, obtaining the current time fed back by the detection device corresponding to the pneumatic valve; wherein, the current time is the time when the temperature difference between both ends of the detection device reaches a preset temperature difference; and, taking the difference between the current time and the issuing time of the opening instruction as the action execution duration of the pneumatic valve.

4. The method according to claim 3, wherein Before the step of simultaneously issuing a plurality of opening instructions, the method further includes: Controlling the gas pipelines where the plurality of pneumatic valves are located to meet preset conditions; wherein, the preset conditions include: the product of the flow rate and specific heat capacity of the process source gas corresponding to each gas pipeline is a preset value.

5. The method according to claim 1, characterized in that The step of determining the second time difference between the target pneumatic valve and the specified pneumatic valve includes: Obtaining the detection parameters of the process pipeline; wherein, the detection parameters include: the actual temperature of the carrier gas, the actual pressure of the pipeline, the carrier flow rate, and the flow rates of multiple process source gases; Calculate a second time difference between the target pneumatic valve and the specified pneumatic valve according to the detection parameter and the preset basic parameter; wherein, the preset basic parameter includes: standard temperature, standard air pressure, pipeline cross-sectional area, and pipeline distance difference, and the pipeline distance difference is the distance between the first interface and the second interface.

6. The method according to claim 1, characterized in that The step of controlling the opening of the target pneumatic valve and the specified pneumatic valve according to the time domain deviation value includes: Control the target pneumatic valve to open and record the first duration after opening; When the first duration reaches the time domain deviation value, control the specified pneumatic valve to open.

7. The method according to claim 6, wherein The method further includes: When controlling the target pneumatic valve to close, record the second duration after closing; When the second duration reaches the time domain deviation value, control the specified pneumatic valve to close.

8. The method according to claim 1, characterized in that, The step of determining the target pneumatic valve among multiple pneumatic valves includes: Calculate the distance from each pneumatic valve to the process chamber, and use the pneumatic valve with the largest distance as the target pneumatic valve.

9. The method according to claim 2, wherein The step of determining the target pneumatic valve among multiple pneumatic valves includes: Use the pneumatic valve with the largest action execution duration as the target pneumatic valve.

10. A semiconductor processing apparatus, characterized in that, Includes: A lower computer, a process chamber, a process pipeline connected to the process chamber, and a plurality of gas pipelines connected to the process pipeline. A pneumatic valve is provided between each gas pipeline and the process pipeline; wherein, the lower computer is used to execute the method according to any one of claims 1-9 above.

Images