Mixed flow metering for improved chamber matching

Abstract

A gas delivery system of a substrate processing system includes a gas tank including a mass flow controller to control a gas flow from a gas source. An airflow path is in fluid communication with the gas tank. A mixed flow metering system is in fluid communication with the gas flow path and includes a controller configured to perform a first flow metering to determine a flow rate of gas supplied by at least one of the mass flow controllers when a desired flow rate of gas supplied by at least one of the mass flow controllers is less than a predetermined flow rate. The at least one of the mass flow controllers is calibrated based on a differential mass of gas in the gas flow path between the gas tank and a flow metering system during a predetermined period of time. The controller is further arranged to perform a second flow metering when the desired flow rate is greater than the predetermined flow rate.

Description

This application is a divisional application of application number 201980052686.X, filed on July 30, 2019, entitled "Mixed Flow Metering for Improving Room Matching". Cross-reference to related applications

[0001] This application claims priority to U.S. Patent Application No. 16 / 056,980, filed August 7, 2018. The entire disclosure of the above-cited application is incorporated herein by reference. Technical Field

[0002] This disclosure relates to flow metering in substrate processing systems, and more specifically to mixed flow metering in substrate processing systems. Background Technology

[0003] The background description provided herein is for the purpose of presenting the general context of this disclosure. The work of the currently designated inventors, within the scope described in this background section and in the various aspects of the specification that could not be identified as prior art at the time of filing, neither expressly nor impliedly acknowledges that it is prior art to this disclosure.

[0004] Substrate processing systems can be used to perform etching, deposition, and / or other processes on substrates such as semiconductor wafers. Example processes that can be performed on a substrate include, but are not limited to, etching, deposition, and cleaning processes. During processing, the substrate is positioned on a substrate support, such as a pedestal, electrostatic chuck (ESC), etc., within the processing chamber of the substrate processing system. A gas delivery system supplies a gas mixture into the processing chamber to process the substrate. Plasma may be excited to enhance the chemical reactions within the processing chamber. RF bias may also be provided to the substrate support to control ion energy.

[0005] To improve quality and reduce defects, one or more metering systems can be used to validate the operation of the processing chamber. For example, a flow metering system can be used to validate the flow rate of the gas mixture supplied by the gas delivery system. When multiple substrate processing chambers are arranged in a substrate processing tool, gas lines are used to connect the gas delivery systems of the processing chambers to multiple flow metering systems.

[0006] Flow metering systems may include orifice-based, steady-state flow measurement devices. Gas delivery systems typically require calibration and supply at flow rates from 10 to 3000 sccm. Gas flowing into a gas line at low flow rates takes a long time to reach the flow metering device and accumulate sufficient pressure for measurement, which adversely affects measurement time during tooling startup. In other words, calibrating at flow rates from 10 to several hundred sccm takes a long time. Recently, process formulations have also required calibration and supply at flow rates from 0.1 to 10 sccm. As can be understood, unacceptable time delays may occur during chamber matching or calibration at lower flow rates from 0.1 to 10 sccm using orifice-based methods. Summary of the Invention

[0007] A metering system for a substrate processing system includes N primary valves that selectively allow gas to flow from N gas sources, where N is an integer. N mass flow controllers are connected to the N primary valves to allow N gases to flow from the N gas sources. N secondary valves selectively allow gas to flow from the N mass flow controllers. A gas flow path connects the N secondary valves to a flow metering system located remotely from the N secondary valves, wherein the gas flow path includes gas lines. A controller is configured to perform a first flow metering of a selected gas from one of the N mass flow controllers at a desired flow rate by: purging the gas flow path; measuring an initial pressure in the gas flow path; determining an initial mass in the gas flow path; allowing the selected gas to flow from one of the N mass flow controllers at the desired flow rate for a predetermined time period; measuring a final pressure in the gas flow path; determining a final mass in the gas flow path; and determining an actual flow rate based on the initial mass, the final mass, and the predetermined time period.

[0008] Among other features, the controller is also configured to determine the effective volume of the gas flow path for the selected gas and the desired flow rate. The controller is further configured to determine the actual flow rate based on the effective volume. The gas flow path also includes a manifold and a valve. The controller is configured to use the first flow metering when the actual flow rate is determined to be less than a predetermined flow rate. The predetermined flow rate is in the range of 5 sccm to 15 sccm.

[0009] Among other features, the controller is configured to determine the actual flow rate using a second flow meter, different from the first flow meter, when the desired flow rate is greater than the predetermined flow rate. The predetermined flow rate is in the range of 5 sccm to 15 sccm.

[0010] Among other features, the second flow metering includes orifice-based metering. A valve is connected to the outlet of the orifice. A pressure sensor senses the pressure at the inlet of the orifice. The controller is configured to use the valve, the pressure sensor, and the orifice to determine the actual flow rate when the desired flow rate is greater than the predetermined flow rate.

[0011] Among other features, the controller is configured to wait for a first predetermined adjustment period after purging the gas flow path and before measuring the initial pressure in the gas flow path. The controller is also configured to wait for a second predetermined adjustment period after allowing the selected gas to flow from one of the N mass flow controllers at the desired flow rate during a predetermined period and before measuring the final pressure in the gas flow path.

[0012] A gas delivery system for a substrate processing system includes a gas chamber containing N mass flow controllers to control gas flow from N gas sources, where N is an integer. A gas flow path is in fluid communication with the gas chamber. A mixed flow metering system is in fluid communication with the gas flow path and includes a controller configured to perform a first flow metering to calibrate the at least one of the N mass flow controllers based on the differential mass of the gas in the gas flow path between the gas chamber and the flow metering system during a predetermined time period Δt when a desired flow rate of the gas supplied by at least one of the N mass flow controllers is less than a predetermined flow rate. The controller is further configured to perform a second flow metering to calibrate the at least one of the N mass flow controllers when the desired flow rate of the at least one of the N mass flow controllers is greater than the predetermined flow rate.

[0013] Among other features, the first flow meter and the second flow meter are used to determine the effective volume of the gas flow path for the gas at the desired flow rate. The first flow meter also determines the differential mass based on the effective volume of the gas flow path for the gas at the desired flow rate. The second flow meter is an orifice-based method.

[0014] Among other features, the mixed flow metering system includes a controller configured to determine the effective volume of the gas flow path for a selected gas and a selected flow rate. The controller is also configured to further determine the actual flow rate based on the effective volume. The gas flow path also includes a manifold and valves. The predetermined flow rate is in the range of 5 sccm to 15 sccm.

[0015] Among other features, the valve is connected to the outlet of an orifice. A pressure sensor senses the pressure at the inlet of the orifice. The controller is configured to use the valve, the pressure sensor, and the orifice to determine the actual flow rate when the desired flow rate is greater than the predetermined flow rate.

[0016] Among other features, the controller is configured to perform the first flow metering by: purging the airflow path; measuring the initial pressure in the airflow path; determining the initial mass in the airflow path; causing the selected gas to flow from one of the N mass flow controllers at the desired flow rate during a predetermined time period; measuring the final pressure in the airflow path; determining the final mass in the airflow path; and determining the actual flow rate based on the initial mass, the final mass, and the predetermined time period.

[0017] Among other features, the controller is configured to wait for a first predetermined adjustment period after purging the gas flow path and before measuring the initial pressure in the gas flow path. The controller is also configured to wait for a second predetermined adjustment period after allowing the selected gas to flow from one of the N mass flow controllers at the desired flow rate during a predetermined period and before measuring the final pressure in the gas flow path.

[0018] A method for performing gas flow metering in a substrate processing system includes: providing a gas chamber containing N mass flow controllers for controlling gas flows from N gas sources, where N is an integer; and providing a gas flow path in fluid communication with the gas chamber. The method includes: using a first flow metering to calibrate the at least one of the N mass flow controllers based on differential mass of gas in the gas flow path between the gas chamber and the flow metering system during a predetermined time period when a desired flow rate of gas supplied by at least one of the N mass flow controllers is less than a predetermined flow rate. The method further includes: using a second flow metering to calibrate the at least one of the N mass flow controllers when the desired flow rate of the at least one of the N mass flow controllers is greater than the predetermined flow rate.

[0019] Among other features, the first flow meter and the second flow meter are used to determine the effective volume of the gas flow path for the gas at the desired flow rate.

[0020] Among other features, the first flow meter also determines the differential mass based on the effective volume of the gas flow path for the gas at the desired flow rate.

[0021] Among other features, the second flow metering is an orifice-based method. The predetermined flow rate is in the range of 5 sccm to 15 sccm.

[0022] Among other features, the first flow metering includes: purging the airflow path; measuring the initial pressure in the airflow path; determining the initial mass in the airflow path; causing selected gas to flow from one of the N mass flow controllers at the desired flow rate during a predetermined time period; measuring the final pressure in the airflow path; determining the final mass in the airflow path; and determining the actual flow rate based on the initial mass, the final mass, and the predetermined time period.

[0023] Among other features, the method includes: waiting for a first predetermined adjustment period after purging the gas flow path and before measuring the initial pressure in the gas flow path. The method also includes: waiting for a second predetermined adjustment period after allowing the selected gas to flow from one of the N mass flow controllers at the desired flow rate during a predetermined period and before measuring the final pressure in the gas flow path.

[0024] The further scope of the applicability of this disclosure will become apparent from the detailed description, claims, and drawings. The detailed description and specific examples are for illustrative purposes only and are not intended to limit the scope of this disclosure. Attached Figure Description

[0025] This disclosure will be more fully understood from the detailed description and accompanying drawings, in which:

[0026] Figure 1 A functional block diagram of an example substrate processing system;

[0027] Figure 2 A functional block diagram of an example substrate processing tool;

[0028] Figure 3 For use Figure 1 and 2 A functional block diagram of a gas delivery system according to this disclosure in a system;

[0029] Figure 4 A functional block diagram of an example air box according to this disclosure;

[0030] Figure 5 A functional block diagram of an example of a hybrid flow metering system according to this disclosure;

[0031] Figure 6 A functional block diagram of an example of a hybrid flow metering controller according to this disclosure;

[0032] Figure 7A and 7B A flowchart illustrating an example of a method for performing hybrid flow metering as described in accordance with this disclosure;

[0033] Figure 8 A flowchart illustrating an example of a differential quality method described in accordance with this disclosure;

[0034] Figure 9 A graph depicting the pressure versus time function during the differential mass method according to this disclosure; and

[0035] Figure 10 This is a flowchart illustrating an example of a method for calculating the change in the effective volume of a given gas over time as an additional metrological verification, as described in accordance with this disclosure.

[0036] In the accompanying drawings, reference numerals may be used repeatedly to identify similar and / or identical elements. Detailed Implementation

[0037] Orifice-based flow metering systems, such as Absolute Flow Verification (AFV), supply gas from a mass flow controller (MFC) through an orifice bank to the pump. The orifice bank contains multiple precision orifices selectable using corresponding valves. Pressure accumulates upstream of the selected orifice and is monitored by a pressure sensor such as a pressure gauge. The pressure value is used to determine the flow rate based on an empirically derived gas meter that correlates the orifice pressure with the gas flow rate for each gas. Temperature corrections can also be applied to account for temperature variations and determine the true gas flow rate of the MFC.

[0038] Because it takes time for the gas flow path downstream of the MFC and upstream of the selected orifice to fill and pressurize, the measurement time for AFV increases significantly at lower flow rates. The gas flow path typically includes gas supply lines, manifolds, valves, etc. (located between the gas chamber and the flow metering system). The long calibration period increases the downtime required to perform gas flow calibration during initial setup and later during chamber matching. At very low flow rates and with long gas supply lines, it is difficult to detect when the orifice flow stabilizes (to obtain steady-state pressure). Small cumulative changes in pressure are difficult to detect due to the increased volume of the gas line.

[0039] According to the hybrid flow metering system and method of this disclosure, a differential mass measurement (DMM) method is used for flow rates below a predetermined flow rate, and another flow metering method is used for flow rates above the predetermined flow rate. In some examples, the predetermined flow rate is 10 sccm, but other flow rate values ​​can be used. In some examples, orifice-based flow metering is used for flow rates above the predetermined flow rate, but other flow metering methods can be used.

[0040] As will be described further below, the DMM method fills the gas volume in the gas lines, valves, manifolds, etc., between the gas tank and the flow metering system. In some examples, the gas volume is emptied and the initial pressure is measured after a settling period. The initial mass is determined based on the initial pressure and the effective volume of the gas flow path through the gas lines, manifolds, valves, and / or other volumes located between the gas tank and the flow metering system.

[0041] After determining the initial mass, the valve is opened and the MFC flows the gas at the desired flow rate (to be calibrated) for a predetermined period Δt. The pressure in the gas volume between the gas tank and the flow metering system rises steadily. After the predetermined period Δt, the valve is closed and the final pressure is measured. The final mass is calculated based on the final pressure. The flow rate is calculated by dividing the difference between the final mass and the initial mass by Δt.

[0042] Although the DMM method is similar to the Rate of Rise in Chambers (ROR), the DMM method uses the volume of gas lines, valves, manifolds, etc., rather than the volume of the chamber / tank, to calculate the mass flow rate. In ROR, the governing equations for calculating the mass flow rate are obtained after calculating the time derivative of the equation of state. In an ROR tank, instantaneous pressure and temperature are sampled over time during gas compression, and the rate of change of pressure / temperature is calculated.

[0043] More specifically, when performing the DMM method for low flow rates, the MFC gas flow is used to pressurize a known volume V of the casing for a predetermined time period Δt. The initial and final gas pressures and temperatures within the casing are used to calculate the net mass of gas supplied to the casing based on the following gas law: PV = mRTZ / MW (1) Where P is pressure, V is volume, m is mass, MW is molecular weight, R is the universal gas constant, and Z is the gas compressibility under conditions (p, T).

[0044] The equation for the absolute gas flow rate Q is: The subscripts 1 and 2 represent the initial state and the final state, respectively.

[0045] The compressibility effect is important only for polyatomic gases and when the pressure and temperature are close to atmospheric (ATM) conditions. Since the downstream pressure of the MFC is subatmospheric and can be maintained at an pressure one order of magnitude lower than the ATM when the gas volume is pressurized in the DMM method, the compressibility effect can be ignored even for polyatomic gases. Therefore, the flow equation simplifies to:

[0046] In some examples, the gas in the enclosure is allowed to settle for a predetermined conditioning period before the initial and final p and T measurements are taken. This conditioning period reduces the influence of gas kinetic energy, which eliminates the pressure gradient caused by airflow. This conditioning period also allows the gas temperature to stabilize with the environment. In other words, the gas is heated or cooled by the surrounding enclosure (wall temperature Tw), which eliminates the effects caused by gas expansion or compression, respectively.

[0047] When the housing is evacuated (based on previous measurements) to remove gas residue, gas expansion occurs at the start of metrological calibration. As gas is supplied into the housing, it undergoes compression and heating, raising its temperature. Accurate measurement of direct gas temperature is impossible because using a rapid temperature sensor in the gas path is impractical (due to the potential risk of sensor damage from exposure to corrosive gases).

[0048] If the gas can be stabilized during the conditioning period, the initial and final gas temperatures will be related to the initial and final wall temperatures, respectively. and The same applies. Similarly, due to the elimination of the pressure gradient along the length of the gas supply line and the change in gas temperature, the initial and final pressures (p1 and p2) are also adjusted to... and Therefore, the flow rate equation simplifies to:

[0049] As mentioned above, the casing (internal volume of gas lines, valves, manifolds, etc.) used in the DMM method behaves differently than the casing used in the ROR method. In the ROR method, the effective volume V is the same as the true volume of the tank. However, experimental testing of the casing (gas lines, valves, manifolds, etc.) used in the DMM method leads to errors. In other words, the effective volume V (calculated using known flow rates) is incorrect. eff The internal volume is significantly different from what was expected.

[0050] Some differences in volume can be attributed to variations in geometric manufacturing tolerances. Furthermore, experiments show that the calibrated effective volume V... eff This can vary depending on the gas and flow rate. These differences can be attributed to various other factors. For example, the differences can be attributed to the relatively small volume of the gas supply line (which is more significantly affected by variations in manufacturing tolerances of the gas line, internal valve, and / or substrate volume). The differences can also be attributed to the overall complex geometry of the supply volume assembly (a long tubular shape with an internal valve) compared to the simple, uniform geometry of the tank used in the ROR method.

[0051] The ROR method uses a tank with a larger volume than the gas flow path containing the gas supply line. If not properly considered, the pressure gradient in the gas supply line due to gas viscosity effects can significantly impact mass flow rate calculations and cause inaccuracies. Therefore, the ROR method is not suitable when using the volume of the gas supply line as a casing and performing pressure measurements at a single point.

[0052] However, this problem can be solved by using the calibrated effective volume V of each gas. eff (Instead of the theoretical actual volume) and / or flow rate, this can be determined empirically. As will be described further below, the effective volume of this calibration can be calculated using orifice techniques or another flow metering method.

[0053] More specifically, Equation 4 can be used to calculate the effective volume V. Initially, the corresponding MFC is set to one of the low flow rate setpoints, and the DMM method is executed. During the DMM method, the initial and final pressures and temperatures are measured. The orifice method is used to run the MFC at the same flow rate setpoint (with the same gas). The orifice method provides the absolute (true) flow rate Q of the MFC. Equation 4, the absolute flow rate Q, and the initial and final pressures and temperatures are used to determine the effective volume V.

[0054] During initial tool startup and only for gases with low flow rates, only one calculation for the effective volume is required. This single calibration also takes into account variations in manufacturing tolerances of the gas supply lines between tools used for chamber flow matching. Therefore, chamber matching can be performed more quickly using a hybrid approach. Furthermore, calibrating the DMM method (for low flow rates) with an orifice technique method (for higher flow rates) ensures no deviation at flow rate crossovers or overlaps when switching between the two methods. Another advantage of the proposed hybrid flow metering is the ability to track and monitor calculations at flow rate crossovers as an additional system health check to ensure accuracy does not deviate over time.

[0055] Additional details regarding AFV can be found in co-assigned U.S. Patent No. 7,822,570, granted October 26, 2010, entitled "Methods for Performing Actual Flow Verification," which is incorporated herein by reference in its entirety. Additional details regarding ROR can be found in co-assigned U.S. Patent No. 9,778,083.

[0056] Now for reference Figure 1An exemplary substrate processing system 120 is shown. Although an example of a processing chamber using capacitively coupled plasma (CCP) for etching, chemical vapor deposition, or atomic layer deposition (ALD) is shown, the flow metering system and method described herein can be used in any other type of system or substrate processing system. For example, the flow metering system and method described herein can be used in substrate processing systems using remote plasma or inductively coupled plasma (ICP). Furthermore, the system and method described herein can be used in any other semiconductor device requiring precise flow metering.

[0057] The substrate processing system 120 includes a processing chamber 122 that surrounds other components of the substrate processing system 120 and contains RF plasma (if used). The substrate processing system 120 includes an upper electrode 124 and a substrate support 126, such as an electrostatic chuck (ESC). During operation, a substrate 128 is arranged on the substrate support 126.

[0058] By way of example only, the upper electrode 124 may include a gas distribution device 129, such as a nozzle, that introduces and distributes process gases. The gas distribution device 129 may include a rod portion, one end of which is connected to a top surface of the processing chamber. A base portion is typically cylindrical and extends radially outward from the opposite end of the rod portion at a location spaced apart from the top surface of the processing chamber. The substrate-facing surface or panel of the base portion of the nozzle includes a plurality of orifices through which precursors, reactants, etch gases, inert gases, carrier gases, other process gases, or purge gases flow. Alternatively, the upper electrode 124 may include a conductive plate and may introduce process gases in another manner.

[0059] The substrate support 126 includes a substrate 130 serving as a lower electrode. The substrate 130 supports a heating plate 132, which may correspond to a ceramic multi-zone heating plate. A thermal resistance layer 134 may be disposed between the heating plate 132 and the substrate 130. The substrate 130 may include one or more channels 136 for allowing coolant to flow through the substrate 130.

[0060] If plasma is used, the RF generation system 140 generates an RF voltage and outputs it to one of the upper electrode 124 and the lower electrode (e.g., substrate 130 of ESC 126). The other of the upper electrode 124 and substrate 130 can be DC grounded, AC grounded, or floating. By way of example only, the RF generation system 140 may include an RF generator 142 that generates RF power fed to the upper electrode 124 or substrate 130 by a matching and distribution network 144. In other examples, the plasma may be generated inductively or remotely.

[0061] A typical gas delivery system 150 includes one or more gas sources 152-1, 152-2, ..., 152-N (collectively referred to as gas source 152), where N is a positive integer. Gas source 152 is connected to manifold 160 via valves 154-1, 154-2, ..., 154-N (collectively referred to as valve 154) and MFCs 156-1, 156-2, ..., 156-N (collectively referred to as MFC 156). Secondary valves may be used between MFC 156 and manifold 160. Although a single gas delivery system 150 is shown, two or more gas delivery systems may be used.

[0062] Temperature controller 163 can be connected to multiple thermal control elements (TCEs) 164 arranged in the heating plate 132. Temperature controller 163 can be used to control the multiple TCEs 164 to control the temperature of substrate support 126 and substrate 128. Temperature controller 163 can communicate with coolant assembly 166 to control the flow of coolant through channel 136. For example, coolant assembly 166 may include a coolant pump, reservoir, and / or one or more temperature sensors. Temperature controller 163 operates coolant assembly 166 to selectively flow coolant through channel 136 to cool substrate support 126. Valve 170 and pump 172 can be used to evacuate reactants from processing chamber 122. System controller 180 can be used to control components of substrate processing system 120.

[0063] Now for reference Figure 2 The flow metering system and method described herein can be used to provide flow metering for gases supplied to one or more substrate processing tools 210, thereby reducing costs. Although an example of substrate processing tool 210 is shown, other substrate processing tools can be used.

[0064] The substrate processing tool 210 includes a robotic arm 212 positioned at a central location. The robotic arm 212 can be operated under vacuum or atmospheric pressure. The substrate processing tool 210 includes multiple stations (or substrate processing chambers) 216-1, 216-2, ..., 216-S (collectively referred to as stations 216) arranged around the robotic arm 212 (where S is an integer greater than 1). The stations 216 can be arranged around the center of the substrate processing tool 210 with equal or irregular angular deviations. Examples of stations 216 may include one or more deposition, etching, pre-cleaning, post-cleaning, spin cleaning, etc.

[0065] The substrate may initially be located in cassette 234. A robotic arm and loading lock, typically identified at 238, are used to move the substrate from cassette 234 to substrate handling tool 210. When processing is complete, the robotic arm and loading lock 238 may return the substrate to cassette 234 and / or another cassette 239. As will be described further below, a gas delivery system supplies gas to the station, and a flow metering system calibrates the gas flow.

[0066] Now for reference Figure 3 The diagram shows a gas delivery system 300 comprising multiple gas boxes 310-1, 310-2, ..., 310-10 (collectively referred to as gas boxes 310). Although ten (10) gas boxes are shown, the gas delivery system 300 may include additional or fewer gas boxes. Gas boxes 310-1, 310-2, ..., 310-10 are connected to a mixed flow metering system 320 by first gas lines 312-1, 312-2, ..., 312-10 (collectively referred to as first gas lines 312). First gas lines 312 may be connected to a manifold 313 and then delivered to the mixed flow metering system 320. Return gas from the mixed flow metering system 320 may be connected to gas boxes 310-1, 310-2, ..., 310-10 by second gas lines 314-1, 314-2, ..., 314-10 (collectively referred to as second gas lines 314). The second gas line 314 flows from the mixed flow metering system 320 into the manifold 315 and is separated into independent lines connected to gas boxes 310-1, 310-2, ..., 310-10.

[0067] Gas lines 316-1, 316-2, ..., 316-10 (collectively referred to as gas lines 316) connect the outputs of gas boxes 310-1, 310-2, ..., 310-10 to the processing chamber. In some examples, a clean dry air (CDA) source 330 is also connected to gas boxes 310-1, 310-2, ..., 310-10. As can be understood, the mixed flow metering system 320 is shared or time-multiplexed by gas boxes 310-1, 310-2, ..., 310-10, which reduces costs.

[0068] Now for reference Figure 4This shows one of the gas chambers 310. Gas sources 410-1, 410-2, ..., and 410-G (collectively referred to as gas sources 410) are connected to a flow control device comprising: primary valves 420-1, 420-2, ..., and 420-G (where G is an integer greater than 1) (collectively referred to as primary valves 420), mass flow controllers (MFCs) 430-1, 430-2, ..., 430-G (collectively referred to as MFC 430), and secondary valves 434-1, 434-2, ..., and 434-G (collectively referred to as secondary valves 434). The output of secondary valve 434 is connected to a mixing manifold 435 and inputs to valves 440, 442, and 448. Valves 440 and 442 are connected to a mixing flow metering system 320. Valve 442 is associated with the gas flowing in gas line 312 to the mixing flow metering system 320. Valve 440 is associated with the gas returning from the mixing flow metering system 320 in gas line 314. Valve 448 is associated with the gas flowing in gas line 316 to the processing chamber associated with gas box 310. One or more temperature sensors 480 may be used to sense the temperature of the gas lines. In some examples, portions of the gas lines are heated by resistance heaters (not shown).

[0069] Now for reference Figure 5 This shows a portion of the mixed flow metering system. The inlet B of the mixed flow metering system 320 is connected to valve 510. The inlets B' associated with gas boxes GB2, GB4, GB6, GB8, and GB10 are connected to valve 511. The outputs of valves 510 and 511 are connected via manifold 513 to multiple gas lines 518-1, 518-2, ..., and 518-O (where O is an integer greater than or equal to 1) (collectively referred to as gas lines 518). Gas lines 518 are connected to precision orifices 520-1, 520-2, ..., and 520-O (collectively referred to as precision orifices 520).

[0070] In some examples, the precision orifice 520 has a varying orifice size. An orifice 520 is considered "precision" if it has a predetermined, known size and shape and is not blocked. When the precision orifice is operating in a choke state, one or more pressure sensors 530 sense the pressure upstream of the precision orifice 520. The choke state occurs when gas exits the precision orifice at the speed of sound. One of the precision orifices is selected based on the flow rate to be calibrated.

[0071] Pressure sensor 530 is connected to the outputs of valves 510 and 511 and the inlet of precision orifice 520. For example, the first pressure sensor 530 operates in a first pressure range, while the second pressure sensor 530 operates in a second pressure range that is the same as or different from the first pressure range. For example, the first pressure sensor 530 measures pressures up to 50T, while the second pressure sensor 530 measures pressures up to 500T, but other pressure ranges can be used. Precision orifice 520 is connected to the inlet of valves 524-1, 524-2, ..., and 524-0 (collectively referred to as valve 524). The outlets of valve 524 are connected together and output to pump 540.

[0072] Now for reference Figure 6 The image shows a hybrid flow metering controller 610. In some examples, the hybrid flow metering controller 610 includes an AFV meter 620 and a V meter 620. eff Table 622 and V eff Estimation module 624. AFV table 620 is an empirically established table relating orifice pressure to flow rate for each gas. V eff Table 622 contains calibrated V values ​​indexed by gas and / or desired flow rate. eff value.

[0073] The mixed flow metering controller 610 communicates with valve 634, mass flow controller 636, pressure sensor 530, and temperature sensor 480. As will be described further below, the mixed flow metering controller 610 controls valve 634 based on feedback from temperature sensor 480 and pressure sensor 530. In some examples, V eff The estimation module 624 can be used to estimate V based on other calibrations using interpolation, formulas, or other techniques. eff Value to estimate V eff .

[0074] Now for reference Figure 7A and 7B This demonstrates a method for performing mixed flow metering. Figure 7A In this process, method 700 determines the effective volume for calibration of the low-flow-rate gas. In other words, when using the DMM method, only the effective volume for calibration needs to be determined for the gas to be supplied at a flow rate lower than a predetermined flow rate. Furthermore, each of the gases to be used and the flow rate can be calibrated. Alternatively, one or more calibrations can be performed for one or more gases and one or more flow rates. Interpolation, formulas, or other compensation methods can be used to determine the flow rates of other gases and / or other flow rates (below the predetermined flow rate) without requiring separate calibration.

[0075] At 710, the gas and flow rate for calibration of the effective volume are selected. At 714, the effective volume of the selected gas at the selected flow rate is determined using the first and second flow metering methods.

[0076] In some examples, Equation 4 can be used to calculate the effective volume V. Initially, the corresponding MFC is set to one of the low flow rate setpoints, and the DMM method is executed. During the DMM method, the initial and final pressures and temperatures are measured. The orifice method is used to run the MFC at the same flow rate setpoint (with the same gas). The orifice method provides the absolute (true) flow rate Q of the MFC. Equation 4, the absolute flow rate Q, and the initial and final pressures and temperatures are used to determine the effective volume V.

[0077] If additional samples are needed, the method continues at 718, and another flow rate for the selected gas is calibrated. Once all flow rates for the selected gas have been calibrated, the method continues at 722, and it is determined whether another gas needs calibration. If 722 is true, the method returns to 710. Otherwise, the method terminates.

[0078] exist Figure 7B The image shows a method 750 for operating a hybrid flow metering system according to this disclosure. At 760, the method determines whether flow metering should be performed. If 760 is true, the method determines whether the desired flow rate to be calibrated is less than or equal to a first flow rate threshold TH1. If 764 is true, the method uses a DMM method and an effective calibration volume corresponding to the selected gas and / or flow rate. If 764 is false, the method uses a second flow metering method. In some examples, this second flow metering method includes an orifice-based method.

[0079] Now for reference Figure 8 The diagram illustrates a method 800 for performing flow metering. At 810, a gas line is evacuated from the gas tank to the orifice. At 814, a valve is closed to isolate the gas line from the outlet of the MFC leading to the orifice. At 816, the method waits for a settling period to allow kinetic energy to dissipate and the gas to reach wall temperature. In some examples, this settling period ranges from 10 to 60 seconds. At 820, noise from the pressure sensor is filtered, the pressure is measured, and an initial mass is determined based on the measured pressure. At 824, the secondary valve of the MFC is opened, and a flow is supplied at the desired rate. The gas line, manifold, and other structures are filled for a predetermined period Δt at the desired flow rate output by the MFC. At 830, the secondary valve of the MFC is closed, and the flow is stopped. At 834, the method waits for the settling period. At 838, noise from the pressure sensor is filtered, the pressure is measured, and the final mass is determined based on the measured pressure and the effective volume (for the selected gas and / or the selected flow rate). In 842, the flow rate is determined based on the final mass, the initial mass, and Δt.

[0080] Now for reference Figure 9 For the example DMM method, the measured pressure is displayed as a function of time. After evacuating the gas line, the gas is allowed to settle and reach equilibrium temperature with a surface such as the inner wall of the gas line. This results in an initial pressure P l A slight increase. Next, the MFC is set to the desired flow rate to be calibrated within a time period Δt. After time period Δt, the gas is allowed to settle to eliminate the pressure gradient along the gas supply line and reach equilibrium temperature with a surface such as the inner wall of the gas line. This causes a slight change in the final pressure p2.

[0081] Now for reference Figure 10 This paper illustrates a method 1000 for providing additional validation in the calibration of an MFC. In some examples, during operation, a first flow metering system and a second flow metering system will have overlap of one or more flow rates within a comparable predetermined range. For example, the first flow metering system can be used to calibrate flow rates less than or equal to 10 sccm, while the second flow metering system can be used to calibrate flow rates greater than or equal to 10 sccm. In some examples, both the first and second flow metering systems can be used to calibrate the same desired flow rate of the MFC. For example, both metering systems can be used to calibrate 10 sccm.

[0082] The calibration results using the first and second flow metering systems can be compared. If the results fall within the predetermined tolerances, the first and second flow metering systems are correctly executed. If the results are not within the predetermined tolerances, the system sends a notification, generates an alert message, activates a warning light, and / or takes other actions.

[0083] In step 1010, the MFC is configured to flow the selected gas at a desired flow rate within a predetermined flow rate range. In some examples, the predetermined flow rate range is close to the predetermined flow rate used for switching between a first metering system and a second metering system. For example, the desired flow rate of the MFC may be in the range of 5 sccm to 15 sccm.

[0084] At 1020, a first flow rate MFR1 is measured using a first metering system. At 1030, a second flow rate MFR2 is measured using a second metering system. At 1040, the first flow rate MFR1 and the second flow rate MFR2 are compared. At 1050, the system determines whether the difference between the first flow rate MFR1 and the second flow rate MFR2 is less than a predetermined value or within a predetermined tolerance. If 1050 is true, the method ends. Otherwise, the system sends a notification, generates an alert message, activates an alert light, or takes other actions at 1052.

[0085] The foregoing description is merely illustrative in nature and is in no way intended to limit this disclosure, its application, or its use. The broad teachings of this disclosure can be implemented in various forms. Therefore, while this disclosure includes specific examples, its true scope should not be so limited, as other modifications will become apparent upon examination of the drawings, specification, and appended claims. It should be understood that one or more steps in the method may be performed in different orders (or simultaneously) without altering the principles of this disclosure. Furthermore, while each embodiment is described above as having certain features, any one or more of those features described relative to any embodiment of this disclosure may be implemented in and / or combined with features of any other embodiment, even if such combination is not explicitly described. In other words, the described embodiments are not mutually exclusive, and substitution of one or more embodiments for each other remains within the scope of this disclosure.

[0086] Various terms are used to describe spatial and functional relationships between elements (e.g., between modules, between circuit elements, between semiconductor layers, etc.), including “connection,” “joint,” “coupled,” “adjacent,” “next to,” “on top of,” “above,” “below,” and “set.” Unless the relationship between the first and second elements is explicitly described as “direct,” the relationship described in the above disclosure can be a direct relationship, where no other intermediate element exists between the first and second elements, but it can also be an indirect relationship, where one or more intermediate elements exist between the first and second elements (spatially or functionally). As used herein, the phrase “at least one of A, B, and C” should be interpreted as meaning the use of a non-exclusive logical OR (A or B or C) logic and should not be interpreted as meaning “at least one of A, at least one of B, and at least one of C.”

[0087] In some implementations, the controller is part of a system, which may be part of the examples described above. Such a system may include semiconductor processing apparatus, which includes one or more processing tools, one or more chambers, one or more platforms for processing, and / or specific processing components (wafer pedestals, gas flow systems, etc.). These systems may be integrated with electronics for controlling their operation before, during, and after the processing of semiconductor wafers or substrates. The electronics may be referred to as a “controller”, which can control various components or sub-components of one or more systems. Depending on the processing requirements and / or system type, the controller may be programmed to control any process disclosed herein, including the delivery of processing gases, temperature settings (e.g., heating and / or cooling), pressure settings, vacuum settings, power settings, radio frequency (RF) generator settings, RF matching circuit settings, frequency settings, flow rate settings, fluid delivery settings, position and operation settings, wafer transfer tools and other transfer tools, and / or loading locks connected to or interfaced with a specific system.

[0088] In general, a controller can be defined as an electronic device having various integrated circuits, logic, memory, and / or software for receiving instructions, issuing instructions, controlling operations, enabling cleaning operations, enabling endpoint measurements, etc. Integrated circuits can include chips in the form of firmware storing program instructions, digital signal processors (DSPs), chips defined as application-specific integrated circuits (ASICs), and / or one or more microprocessors, or microcontrollers that execute program instructions (e.g., software). Program instructions can be instructions sent to the controller in the form of various individual settings (or program files), which define operating parameters for performing a specific process on or for a semiconductor wafer or system. In some embodiments, operating parameters can be part of a recipe defined by a process engineer to complete one or more processing steps during the fabrication of one or more layers, materials, metals, oxides, silicon, silica, surfaces, circuits, and / or the die of the wafer.

[0089] In some implementations, the controller may be part of or coupled to a computer integrated with, coupled to, or otherwise networked to the system, or a combination thereof. For example, the controller may be in the “cloud” or be all or part of a fab host system, allowing remote access to wafer processing. The computer may enable remote access to the system to monitor the current progress of manufacturing operations, examine the history of past manufacturing operations, examine trends or performance criteria of multiple manufacturing operations, change parameters of the current process, set processing steps to follow the current process, or initiate a new process. In some examples, a remote computer (e.g., a server) may provide process recipes to the system via a network (which may include a local network or the Internet). The remote computer may include a user interface that enables input or programming of parameters and / or settings, which are then transmitted from the remote computer to the system. In some examples, the controller receives instructions in the form of data specifying parameters for each processing step to be performed during one or more operations. It should be understood that the parameters may be specific to the type of process to be performed and the type of tool, to which the controller is configured to interface with or control the tool. Therefore, as described above, a controller can be distributed, for example, by comprising one or more discrete controllers networked together and operating toward a common purpose (such as the process and control described herein). An example of a distributed controller for such a purpose is one or more integrated circuits on a room that communicate with one or more integrated circuits remotely (e.g., at the platform level or as part of a remote computer), which together control the process on the room.

[0090] Example systems may include, but are not limited to, plasma etching chambers or modules, deposition chambers or modules, rotary rinsing chambers or modules, metal plating chambers or modules, cleaning chambers or modules, chamfering edge etching chambers or modules, physical vapor deposition (PVD) chambers or modules, chemical vapor deposition (CVD) chambers or modules, atomic layer deposition (ALD) chambers or modules, atomic layer etching (ALE) chambers or modules, ion implantation chambers or modules, orbital chambers or modules, and any other semiconductor processing systems that may be associated with or used in the manufacture and / or preparation of semiconductor wafers.

[0091] As described above, depending on one or more processing steps to be performed by the tool, the controller may communicate with one or more other tool circuits or modules, other tool components, cluster tools, other tool interfaces, adjacent tools, neighboring tools, tools located throughout the plant, a host computer, another controller, or tools used in the transport of materials to and from the tool location and / or loading port in the semiconductor manufacturing plant.

Claims

1. A method for performing gas flow metering in a substrate processing system, the substrate processing system comprising N main valves for selectively flowing N gases from N gas sources; N mass flow controllers connected to the N main valves to allow the N gases to flow from the N gas sources; N secondary valves for selectively allowing the N gases to flow from the N mass flow controllers; and a gas flow path connecting the N secondary valves to a flow metering system located remotely from the N secondary valves, wherein the gas flow path includes gas lines, and N is an integer; the method comprising: The following operations are performed to first flow meter a selected gas from the N gases from one of the N mass flow controllers at a desired flow rate: Empty the airflow path; Measure the initial pressure in the airflow path; Determine the initial mass in the airflow path; The selected gas is made to flow from one of the N mass flow controllers at the desired flow rate during a predetermined time period; Measure the final pressure in the airflow path; Determine the final mass in the airflow path; as well as The actual flow rate is determined based on the initial quality, the final quality, and the predetermined time period.

2. The method of claim 1, further comprising determining an effective volume of the gas flow path for the selected gas and the desired flow rate.

3. The method of claim 2, further comprising determining the actual flow rate based on the effective volume.

4. The method of claim 1, further comprising using the first flow meter when determining the actual flow rate when the expected flow rate is less than the predetermined flow rate.

5. The method of claim 4, wherein the predetermined flow rate is in the range of 5 sccm to 15 sccm.

6. The method of claim 4, further comprising determining the actual flow rate using a second flow meter different from the first flow meter when the desired flow rate is greater than the predetermined flow rate.

7. The method of claim 6, wherein the predetermined flow rate is in the range of 5 sccm to 15 sccm.

8. The method of claim 6, wherein the second flow metering comprises orifice-based metering.

9. The method of claim 4, further comprising, when the desired flow rate is greater than the predetermined flow rate, using a valve connected to the outlet of the orifice and a pressure sensor that senses the pressure at the inlet of the orifice to determine the actual flow rate.

10. The method of claim 1, further comprising waiting for a first predetermined adjustment period after purging the airflow path and before measuring the initial pressure in the airflow path.

11. The method of claim 10, further comprising, after the selected gas is flowed from one of the N mass flow controllers at the desired flow rate during the predetermined time period, and before the final pressure in the gas flow path is measured, waiting for a second predetermined adjustment period.

12. A method for performing airflow metering in a substrate processing system, the substrate processing system comprising: A gas chamber and an airflow path in fluid communication with the gas chamber, the gas chamber including N mass flow controllers to control airflow from N gas sources respectively, where N is an integer, the method comprising: Set the desired flow rate of the gas supplied by at least one of the N mass flow controllers; Using a first flow meter, at least one of the N mass flow controllers is calibrated based on the differential mass of the gas in the airflow path between the gas box and the flow metering system during a predetermined time period when the desired flow rate is less than or equal to a predetermined flow rate; and A second flow meter is used to calibrate at least one of the N mass flow controllers when the desired flow rate is greater than the predetermined flow rate.

13. The method of claim 12, wherein the first flow meter and the second flow meter are used to determine the effective volume of the gas flow path for the gas at the desired flow rate.

14. The method of claim 13, wherein the first flow metering is further based on the effective volume of the gas flow path for the gas at the desired flow rate to determine the differential mass.

15. The method of claim 12, wherein the second flow metering is based on an orifice.

16. The method of claim 12, wherein the predetermined flow rate is in the range of 5 sccm to 15 sccm.

17. The method of claim 12, wherein the first flow metering comprises: Empty the airflow path; Measure the initial pressure in the airflow path; Determine the initial mass in the airflow path; During the predetermined time period, the selected gas is made to flow from at least one of the N mass flow controllers at the desired flow rate; Measure the final pressure in the airflow path; Determine the final mass in the airflow path; as well as The actual flow rate is determined based on the initial quality, the final quality, and the predetermined time period.

18. The method of claim 17, further comprising waiting for a first predetermined adjustment period after emptying the airflow path before measuring the initial pressure in the airflow path.

19. The method of claim 18, further comprising waiting for a second predetermined adjustment period after allowing the selected gas to flow from at least one of the N mass flow controllers at the desired flow rate during the predetermined period, prior to measuring the final pressure in the airflow path.

20. A method for performing airflow metering in a substrate processing system, the substrate processing system comprising: A gas chamber and an airflow path in fluid communication with the gas chamber, the gas chamber including N mass flow controllers that respectively control airflow from N gas sources, where N is an integer, the method comprising: Set the desired flow rate of the gas supplied by at least one of the N mass flow controllers; and At least one of the N quality flow controllers is calibrated using a first flow meter and a second flow meter selected based on a comparison between a predetermined flow rate and a desired flow rate.

21. The method of claim 20, further comprising: When the desired flow rate is less than or equal to the predetermined flow rate, the first flow meter is selected; as well as When the desired flow rate is greater than the predetermined flow rate, the second flow meter is selected.

22. The method of claim 20, further comprising performing the first flow measurement based on the differential mass of gas in the airflow path between the gas tank and the flow measurement system during a predetermined time period.

23. The method of claim 22, wherein the first flow meter and the second flow meter are used to determine the effective volume of the gas flow path for the gas at the desired flow rate.

24. The method of claim 23, wherein the first flow metering is further based on the effective volume of the gas flow path for the gas at the desired flow rate to determine the differential mass.

25. The method of claim 20, wherein the second flow metering is based on an orifice.

26. The method of claim 20, wherein the predetermined flow rate is in the range of 5 sccm to 15 sccm.

27. The method of claim 22, wherein the first flow metering comprises: Empty the airflow path; Measure the initial pressure in the airflow path; Determine the initial mass in the airflow path; The selected gas is made to flow from at least one of the N mass flow controllers at the desired flow rate during a predetermined time period; Measure the final pressure in the airflow path; Determine the final mass in the airflow path; as well as The actual flow rate is determined based on the initial quality, the final quality, and the predetermined time period.

28. The method of claim 27, further comprising waiting for a first predetermined adjustment period after emptying the airflow path before measuring the initial pressure in the airflow path.

29. The method of claim 28, further comprising, after the selected gas is flowed from one of the N mass flow controllers at the desired flow rate during the predetermined time period, waiting for a second predetermined adjustment period before measuring the final pressure in the gas flow path.

30. A hybrid flow metering system, comprising: An airflow path in fluid communication with a gas box, the gas box comprising N mass flow controllers to control airflow from N gas sources respectively, where N is an integer; as well as A controller is configured to calibrate at least one of the N mass flow controllers using a first flow meter and a second flow meter, the first flow meter and the second flow meter being selected based on a comparison between a predetermined flow rate and a desired flow rate of gas supplied by the at least one of the mass flow controllers.

31. The hybrid flow metering system of claim 30, wherein the controller is configured to: When the desired flow rate is less than or equal to the predetermined flow rate, the first flow meter is selected; and When the desired flow rate is greater than the predetermined flow rate, the second flow meter is selected.

32. The hybrid flow metering system of claim 30, wherein the controller is configured to perform the first flow metering based on the differential mass of gas in the airflow path between the gas box and the hybrid flow metering system during a predetermined time period.

33. The hybrid flow metering system of claim 32, wherein the first flow meter and the second flow meter are used to determine the effective volume of the gas flow path for the gas at the desired flow rate.

34. The hybrid flow metering system of claim 33, wherein the first flow metering further determines the differential mass based on the effective volume of the gas flow path for the gas at the desired flow rate.

35. The hybrid flow metering system of claim 30, wherein the second flow metering is based on an orifice method.

36. The hybrid flow metering system of claim 30, wherein the controller is configured to determine the effective volume of the airflow path for the selected gas and the selected flow rate.

37. The hybrid flow metering system of claim 36, wherein the controller is further configured to determine the actual flow rate based on the effective volume.

38. The mixed flow metering system of claim 30, wherein the airflow path further includes a manifold and a valve.

39. The hybrid flow metering system of claim 30, wherein the predetermined flow rate is in the range of 5 sccm to 15 sccm.

40. The hybrid flow metering system according to claim 30, further comprising: orifice; A valve, which is connected to the outlet of the orifice; as well as A pressure sensor senses the pressure at the inlet of the orifice. The controller is configured to use the valve, the pressure sensor, and the orifice to determine the actual flow rate when the desired flow rate is greater than the predetermined flow rate.

41. The hybrid flow metering system of claim 36, wherein the controller is configured to perform the first flow metering by: Empty the airflow path; Measure the initial pressure in the airflow path; Determine the initial mass in the airflow path; The selected gas is made to flow from one of the N mass flow controllers at the desired flow rate during a predetermined time period; Measure the final pressure in the airflow path; Determine the final mass in the airflow path; as well as The actual flow rate is determined based on the initial quality, the final quality, and the predetermined time period.

42. The hybrid flow metering system of claim 41, wherein the controller is configured to wait for a first predetermined adjustment period after emptying the airflow path and before measuring the initial pressure in the airflow path.

43. The hybrid flow metering system of claim 42, wherein the controller is configured to wait for a second predetermined adjustment period after the selected gas flows from one of the N mass flow controllers at the desired flow rate during the predetermined period, and before measuring the final pressure in the gas flow path.

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