Mixed flow metering for improved chamber matching

Abstract

A gas delivery system for a substrate processing system includes a gas box including a mass flow controller for controlling gas flow from a gas source. A gas flow path is in fluid communication with the gas box. A hybrid flow metering system is in fluid communication with the gas flow path and includes a controller configured to: perform a first flow metering operation to calibrate at least one of the mass flow controllers based on a differential mass of gas in the gas flow path between the gas box and the flow metering system during a predetermined period when a desired flow rate of gas supplied by at least one of the mass flow controllers is less than a predetermined flow rate; and perform a second flow metering operation when the desired flow rate is greater than the predetermined flow rate.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. Patent Application No. 16 / 056,980, filed on August 7, 2018. The entire disclosure of the above-referenced application is incorporated herein by reference. Technical Field

[0003] The present disclosure relates to flow metering for substrate processing systems, and more particularly to hybrid flow metering for substrate processing systems. Background Art

[0004] The background description provided here is for the purpose of generally presenting the context of the present disclosure. No admission is made, either explicitly or implicitly, that the work of the presently designated inventors is prior art to the present disclosure to the extent that it is described in this background section and in aspects of the specification that were not determined to be prior art at the time the application was filed.

[0005] A substrate processing system can be used to perform etching, deposition, and / or other processing on a substrate, such as a semiconductor wafer. 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 placed on a substrate support, such as a pedestal, electrostatic chuck (ESC), or the like, in a processing chamber of the substrate processing system. A gas delivery system supplies a gas mixture into the processing chamber to process the substrate. A plasma may be excited to enhance chemical reactions within the processing chamber. An RF bias may also be provided to the substrate support to control ion energy.

[0006] To improve quality and reduce defects, one or more metrology systems may be used to verify the operation of the processing chambers. For example, a flow metering system may be used to verify 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 the multiple flow metering systems.

[0007] The flow metering system may include an orifice-based, steady-state flow measurement device. Gas delivery systems generally require calibration and supply flow rates from 10-3000 sccm. Gas flowing into the gas line at low flow rates takes a long time to reach the flow metering device and build up sufficient pressure for measurement, which has a negative impact on measurement time during tool startup. In other words, calibrating flow rates from 10 to several hundred sccm takes a long time. More recently, process recipes also require calibration and supply flow rates from 0.1-10 sccm. As can be appreciated, unacceptable time delays can occur during chamber matching or calibration at lower flow rates from 0.1 to 10 sccm using orifice-based methods. Summary of the Invention

[0008] A metering system for a substrate processing system includes N primary valves that selectively cause gases to flow from N gas sources, respectively, where N is an integer. N mass flow controllers are connected to the N primary valves, respectively, for causing N gases to flow from the N gas sources, respectively. N secondary valves selectively cause gases to flow from the N mass flow controllers, respectively. A gas flow path connects the N secondary valves to a flow metering system located remote from the N secondary valves, wherein the gas flow path includes a gas pipeline. A controller is configured to perform a first flow metering of a selected gas at a desired flow rate from one of the N mass flow controllers by: evacuating the gas flow path; measuring an initial pressure in the gas flow path; determining an initial mass in the gas flow path; causing the selected gas to flow from the one of the N mass flow controllers at the desired flow rate during a predetermined period of time; 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 period of time.

[0009] In other features, the controller is further configured to determine an 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 further on the effective volume. The gas flow path also includes a manifold and a valve. The controller is configured to use the first flow metric when determining the actual flow rate if the desired flow rate is less than a predetermined flow rate. The predetermined flow rate is in the range of 5 sccm to 15 sccm.

[0010] In other features, the controller is configured to determine the actual flow rate using a second flow metric different from the first flow metric when the desired flow rate is greater than the predetermined flow rate. The predetermined flow rate is in the range of 5 seem to 15 seem.

[0011] In other features, the second flow meter comprises an orifice-based meter. A valve is connected to an outlet of the orifice. A pressure sensor senses a pressure at an inlet of the orifice. The controller is configured to determine the actual flow rate using the valve, the pressure sensor, and the orifice when the desired flow rate is greater than the predetermined flow rate.

[0012] In other features, the controller is configured to wait a first predetermined adaptation period after evacuating the gas flow path and before measuring the initial pressure in the gas flow path. The controller is configured to wait a second predetermined adaptation period after causing the selected gas to flow from the 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.

[0013] A gas delivery system for a substrate processing system includes a gas box including N mass flow controllers for respectively controlling gas flows from N gas sources, where N is an integer. A gas flow path is in fluid communication with the gas box. A hybrid flow metering system is in fluid communication with the gas flow path and includes a controller configured to: perform a first flow metering operation to calibrate at least one of the N mass flow controllers based on a differential mass of gas in the gas flow path between the gas box and the flow metering system during a predetermined time period Δt 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; and perform a second flow metering operation to calibrate at least one of the N mass flow controllers when the desired flow rate of at least one of the N mass flow controllers is greater than the predetermined flow rate.

[0014] In other features, the first flow metric and the second flow metric are used to determine an effective volume of the gas flow path for the gas at the desired flow rate. The first flow metric further 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 metric is an orifice-based method.

[0015] In other features, the hybrid flow metering system includes a controller configured to determine an effective volume of the gas flow path for a selected gas and a selected flow rate. The controller is further configured to determine the actual flow rate based further on the effective volume. The gas flow path also includes a manifold and a valve. The predetermined flow rate is in the range of 5 sccm to 15 sccm.

[0016] In other features, a valve is connected to an outlet of an orifice. A pressure sensor senses pressure at an inlet of the orifice. The controller is configured to determine an actual flow rate using the valve, the pressure sensor, and the orifice when the desired flow rate is greater than the predetermined flow rate.

[0017] In other features, the controller is configured to perform the first flow metering by: evacuating the airflow path; measuring an initial pressure in the airflow path; determining an 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 period of time; measuring a final pressure in the airflow path; determining a final mass in the airflow path; and determining an actual flow rate based on the initial mass, the final mass, and the predetermined period of time.

[0018] In other features, the controller is configured to wait a first predetermined adaptation period after evacuating the gas flow path and before measuring the initial pressure in the gas flow path. The controller is configured to wait a second predetermined adaptation period after causing the selected gas to flow from the 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.

[0019] A method for performing gas flow metering in a substrate processing system includes providing a gas box containing N mass flow controllers for respectively controlling gas flows from N gas sources, where N is an integer, and providing a gas flow path in fluid communication with the gas box. The method includes using a first flow meter to calibrate at least one of the N mass flow controllers based on the differential mass of gas in the gas flow path between the gas box and a flow meter system during a predetermined 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 includes using a second flow meter to calibrate at least one of the N mass flow controllers when the desired flow rate of at least one of the N mass flow controllers is greater than the predetermined flow rate.

[0020] In other features, the first flow metric and the second flow metric are used to determine an effective volume of the gas flow path for the gas at the desired flow rate.

[0021] In other features, the first flow metric further determines the differential mass based on the effective volume of the gas flow path for the gas at the desired flow rate.

[0022] In other features, the second flow meter is an orifice-based method.The predetermined flow rate is in a range from 5 seem to 15 seem.

[0023] In other features, the first flow metering includes: evacuating the airflow path; measuring an initial pressure in the airflow path; determining an initial mass in the airflow path; causing a selected gas to flow from one of the N mass flow controllers at the desired flow rate during a predetermined period of time; measuring a final pressure in the airflow path; determining a final mass in the airflow path; and determining an actual flow rate based on the initial mass, the final mass, and the predetermined period of time.

[0024] In other features, the method includes waiting a first predetermined adaptation period after evacuating the gas flow path and before measuring the initial pressure in the gas flow path. The method includes waiting a second predetermined adaptation period after flowing the selected gas from the 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.

[0025] Further scope of applicability of the present disclosure will become apparent from the detailed description, claims and drawings.The detailed description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The present disclosure will be more fully understood from the detailed description and accompanying drawings, in which:

[0027] Figure 1 is a functional block diagram of an example of a substrate processing system;

[0028] Figure 2 is a functional block diagram of an example of a substrate processing tool;

[0029] Figure 3 For use in Figure 1 and 2 A functional block diagram of a gas delivery system according to the present disclosure in a system of FIG.

[0030] Figure 4 is a functional block diagram of an example of an air box according to the present disclosure;

[0031] Figure 5 is a functional block diagram of an example of a hybrid flow metering system according to the present disclosure;

[0032] Figure 6 is a functional block diagram of an example of a hybrid flow metering controller according to the present disclosure;

[0033] Figure 7A and 7B A flowchart of an example of a method for performing hybrid flow metering according to the present disclosure is provided;

[0034] Figure 8 is a flow chart illustrating an example of a differential quality method according to the present disclosure;

[0035] Figure 9 is a graph of pressure as a function of time during a differential mass method according to the present disclosure; and

[0036] Figure 10A flow chart illustrating an example of a method for using the calculated effective volume of a given gas over time as additional metrological confirmation according to the present disclosure.

[0037] Among the drawings, reference numerals may be repeated to identify similar and / or identical elements. DETAILED DESCRIPTION

[0038] Orifice-based flow metering systems such as Absolute Flow Verification (AFV) supply gas from a mass flow controller (MFC) to a pump through an orifice bank. The orifice bank contains multiple precision orifices that can be selected using corresponding valves. Pressure is accumulated upstream of the selected orifice and monitored using a pressure sensor such as a manometer. The pressure value is used to determine the flow rate based on an empirically generated gas table that correlates orifice pressure with gas flow rate on a gas-by-gas basis. Temperature correction can also be applied to account for temperature variations and determine the true gas flow rate of the MFC.

[0039] Because the gas flow path filling and pressurization at the downstream of the MFC and at the upstream of the selected orifice takes time, the measurement time of the AFV increases greatly at lower flow rates. The gas flow path generally includes a gas supply line, a manifold, a valve, etc. (which is located between the gas box and the flow metering system). The long calibration period increases the downtime required for performing gas flow calibration during the initial setup and later during chamber matching. At very low flow rates and using a long gas supply line, it is difficult to detect when the orifice flow stabilizes (to obtain a steady-state pressure). Due to the increased volume of the gas line, it is difficult to detect small changes in the pressure accumulation.

[0040] According to the hybrid flow metering system and method of the present 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.

[0041] As will be described further below, the DMM method fills a gas volume in a gas line, valve, manifold, etc. between a gas box and a flow metering system. In some examples, the gas volume is evacuated and an 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 line, manifold, valve, and / or other volume between the gas box and the flow metering system.

[0042] After determining the initial mass, the valve is opened and the MFC flows gas at a desired flow rate (to be calibrated) for a predetermined period of time, Δt. The pressure in the gas volume between the gas tank and the flow metering system steadily rises. 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.

[0043] Although the DMM method is similar to the chamber rise rate (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 the ROR, the governing equation for calculating the mass flow rate is obtained after calculating the time derivative of the state equation. The instantaneous pressure and temperature are sampled over time during the compression of the gas in the ROR tank, and the rate of change of pressure / temperature is calculated.

[0044] More specifically, when performing the DMM method for low flow rates, the MFC gas flow is used to pressurize an enclosure of known volume V for a predetermined period of time Δt. The initial and final gas pressures and temperatures in the enclosure are used to calculate the net mass of gas supplied to the enclosure based on the following gas state equation:

[0045] PV=mRTZ / MW (1)

[0046] Where P is pressure, V is volume, m is mass, MW is molecular weight, R is the universal gas constant, and Z is the compressibility of the gas under conditions (p, T).

[0047] The equation for the absolute gas flow rate Q is:

[0048]

[0049] The subscripts 1 and 2 represent the initial state and the final state, respectively.

[0050] Compressibility effects are important only for polyatomic gases and when the pressure and temperature are close to atmospheric (ATM) conditions. Since the pressure downstream of the MFC is subatmospheric and can be maintained at an order of magnitude less than the ATM pressure when pressurizing the gas volume in the DMM method, compressibility effects can be ignored even for polyatomic gases. Therefore, the flow equation is simplified to:

[0051]

[0052] In some examples, the gas in the enclosure is allowed to settle for a predetermined acclimation period before measuring the initial and final p and T. This acclimation period reduces the effects of the gas's kinetic energy, which eliminates pressure gradients due to airflow. This acclimation period also allows the gas temperature to stabilize with the surroundings. In other words, the gas is heated or cooled by the surrounding enclosure (wall temperature Tw), which eliminates effects due to gas expansion or compression, respectively.

[0053] Gas expansion occurs at the start of metrological calibration when the housing is evacuated to remove gas residues (according to previous measurements). As gas is supplied to the housing, it undergoes compression, which raises its temperature. Because the use of fast temperature sensors in the gas path is impractical (due to potential sensor damage from exposure to corrosive gases), accurate direct gas temperature measurement is not possible.

[0054] If the gas is allowed to stabilize during the conditioning period, the initial and final gas temperatures will be the same as the initial and final wall temperatures ( and Similarly, due to the elimination of pressure gradients along the length of the gas supply line and changes in gas temperature, the initial and final pressures (p1 and p2) are also adjusted to and Therefore, the flow rate equation is simplified to:

[0055]

[0056] As mentioned above, the enclosure used for the DMM method (the internal volume of the gas lines, valves, manifolds, etc.) behaves differently than the enclosure used for the ROR method. In the ROR method, the effective volume V is the same as the actual volume of the tank. However, experimental testing of the enclosure used for the DMM method (gas lines, valves, manifolds, etc.) resulted in errors. In other words, the effective volume V (calculated using a known flow rate) is eff The internal volume was significantly different than expected.

[0057] Some of the differences in volume can be attributed to variations in geometric manufacturing tolerances. Furthermore, experiments have shown that the calibrated effective volume V eff The differences in volume can vary for different gases and flow rates. These differences can be attributed to a variety of 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). Differences can also be attributed to the overall complex geometry of the supply volume assembly (long tubular shape with internal valve) compared to the simple, uniform geometry of the tank used in the ROR process.

[0058] The ROR method uses a tank with a larger volume than the gas flow path containing the gas supply line. If not properly accounted for, pressure gradients in the gas supply line due to gas viscosity effects can significantly affect mass flow calculations and cause inaccuracies. Therefore, the ROR method is not applicable when using the volume of the gas line as the enclosure and measuring pressure at a single point.

[0059] However, this problem can be solved by using the calibrated effective volume V of each gas. eff (rather than theoretical actual volume) and / or flow rate to be solved empirically. As will be described further below, the calibrated effective volume can be calculated using orifice technology or another flow measurement method.

[0060] More specifically, the effective volume V can be calculated using Equation 4. Initially, the corresponding MFC is set to one of the low flow rate settings and the DMM method is performed. During the DMM method, the initial and final pressures and temperatures are measured. The MFC is run at the same flow rate setting (with the same gas) using the orifice method. The orifice method provides the absolute (true) flow rate Q of the MFC. Using Equation 4, the absolute flow rate Q, and the initial and final pressures and temperatures, the effective volume V is determined.

[0061] During initial tool startup and only for gases with low flow rates, only one calculation for the effective volume is required. A single calibration will also account for variations in manufacturing tolerances of the gas supply lines between tools used for chamber flow matching. Therefore, chamber matching can be performed faster using the hybrid approach. In addition, the DMM method (for low flow rates) is calibrated with the orifice technique method (which is used for higher flow rates) to ensure that there is no deviation at flow rate crossovers or overlaps when switching between the two methods. Another advantage of the proposed hybrid flow metering is that the calculations at flow rate crossovers can be tracked and monitored as an additional system health check to ensure that accuracy has not drifted over time.

[0062] Additional details regarding AFV can be found in commonly assigned U.S. Patent No. 7,822,570, issued on October 26, 2010, and entitled “Methods for Performing Actual Flow Verification,” which is incorporated herein by reference in its entirety. Additional details regarding ROR can be found in commonly assigned U.S. Patent No. 9,778,083.

[0063] Now refer to Figure 1, an exemplary substrate processing system 120 is shown. Although an example of a process chamber using capacitively coupled plasma (CCP) for etching, chemical vapor deposition, or atomic layer deposition (ALD) is shown, the flow metering systems and methods described herein can be used with any other type of system or substrate processing system. For example, the flow metering systems and methods described herein can be used with substrate processing systems using remote plasma or inductively coupled plasma (ICP). Furthermore, the systems and methods described herein can be used in any other semiconductor equipment requiring precise flow metering.

[0064] The substrate processing system 120 includes a processing chamber 122 that surrounds the other components of the substrate processing system 120 and contains an 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 disposed on the substrate support 126.

[0065] By way of example only, the upper electrode 124 may include a gas distribution device 129, such as a showerhead, that introduces and distributes the process gas. The gas distribution device 129 may include a stem portion including one end connected to the top surface of the processing chamber. The base portion is generally cylindrical and extends radially outward from the opposite end of the stem portion at a position spaced from the top surface of the processing chamber. The substrate-facing surface or faceplate of the base portion of the showerhead includes a plurality of holes for allowing precursors, reactants, etching gases, inert gases, carrier gases, other process gases, or purge gases to flow therethrough. Alternatively, the upper electrode 124 may include a conductive plate, and the process gas may be introduced in another manner.

[0066] The substrate support 126 includes a base plate 130 that serves as a lower electrode. The base plate 130 supports a heater plate 132, which may correspond to a ceramic multi-zone heater plate. A thermal resistance layer 134 may be disposed between the heater plate 132 and the base plate 130. The base plate 130 may include one or more channels 136 for flowing a coolant through the base plate 130.

[0067] If plasma is used, the RF generation system 140 generates an RF voltage and outputs the RF voltage to one of the upper electrode 124 and the lower electrode (e.g., the substrate 130 of the ESC 126). The other of the upper electrode 124 and the substrate 130 can be DC grounded, AC grounded, or floating. By way of example only, the RF generation system 140 can include an RF generator 142 that generates RF power that is fed to the upper electrode 124 or the substrate 130 by a matching and distribution network 144. In other examples, the plasma can be generated inductively or remotely.

[0068] A typical gas delivery system 150 includes one or more gas sources 152-1, 152-2, ..., and 152-N (collectively, gas sources 152), where N is an integer greater than zero. The gas sources 152 are connected to a manifold 160 via valves 154-1, 154-2, ..., and 154-N (collectively, valves 154) and MFCs 156-1, 156-2, ..., and 156-N (collectively, MFCs 156). A secondary valve may be used between the MFCs 156 and the manifold 160. Although a single gas delivery system 150 is shown, two or more gas delivery systems may be used.

[0069] The temperature controller 163 can be connected to a plurality of thermal control elements (TCEs) 164 arranged in the heating plate 132. The temperature controller 163 can be used to control the plurality of TCEs 164 to control the temperature of the substrate support 126 and the substrate 128. The temperature controller 163 can be communicated with a coolant assembly 166 to control the flow of coolant flowing through the channel 136. For example, the coolant assembly 166 can include a coolant pump, a reservoir, and / or one or more temperature sensors. The temperature controller 163 operates the coolant assembly 166 to selectively flow coolant through the channel 136 to cool the substrate support 126. A valve 170 and a pump 172 can be used to evacuate reactants from the processing chamber 122. A system controller 180 can be used to control components of the substrate processing system 120.

[0070] Now refer to Figure 2 The flow metering systems and methods described herein may be used to provide flow metering to reduce costs for gases supplied to one or more substrate processing tools 210. Although one example of a substrate processing tool 210 is shown, other substrate processing tools may be used.

[0071] The substrate processing tool 210 includes a centrally located robot 212. The robot 212 can be operated under vacuum or atmospheric pressure. The substrate processing tool 210 includes a plurality of stations (or substrate processing chambers) 216-1, 216-2, ..., and 216-S (collectively referred to as stations 216) (where S is an integer greater than 1) arranged around the robot 212. The stations 216 can be arranged around the center of the substrate processing tool 210 at regular or irregular angles. Examples of stations 216 may include one or more of deposition, etching, pre-cleaning, post-cleaning, spin cleaning, and the like.

[0072] The substrate may initially be located in a cassette 234. A robot and load lock, generally identified at 238, may be used to move the substrate from the cassette 234 to the substrate processing tool 210. When processing is complete, the robot and load lock 238 may return the substrate to the 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.

[0073] Now refer to Figure 3 , shows a gas delivery system 300 including a plurality of gas boxes 310-1, 310-2, ..., and 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. The 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). The first gas line 312 can be connected to a manifold 313 and then transported to the mixed flow metering system 320. Return gas from the mixed flow metering system 320 can be connected to the 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 hybrid flow metering system 320 into the manifold 315 and is separated into independent lines connected to the gas boxes 310 - 1 , 310 - 2 , . . . , 310 - 10 .

[0074] 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 process chamber. In some examples, a clean dry air (CDA) source 330 is also connected to the gas boxes 310-1, 310-2, ..., 310-10. As can be appreciated, the hybrid flow metering system 320 is shared or time-multiplexed by the gas boxes 310-1, 310-2, ..., 310-10, which reduces costs.

[0075] Now refer to Figure 4, shows one of the gas boxes 310. Gas sources 410-1, 410-2, ..., and 410-G (collectively, gas sources 410) are connected to a flow control device, which includes primary valves 420-1, 420-2, ..., and 420-G (where G is an integer greater than 1) (collectively, primary valves 420), mass flow controllers (MFCs) 430-1, 430-2, ..., 430-G (collectively, MFCs 430), and secondary valves 434-1, 434-2, ..., and 434-G (collectively, secondary valves 434). The output of secondary valve 434 is connected to a mixing manifold 435 and input 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 line. In some examples, portions of the gas line are heated by resistive heaters (not shown).

[0076] Now refer to Figure 5 , shows a portion of a hybrid flow metering system. Inlet B of hybrid flow metering system 320 is connected to valve 510. Inlet B' associated with gas boxes GB2, GB4, GB6, GB8, and GB10 is connected to valve 511. The outputs of valves 510 and 511 are connected by manifold 513 to a plurality of gas pipelines 518-1, 518-2, ..., and 518-O (where O is an integer greater than or equal to 1) (collectively referred to as gas pipelines 518). Gas pipelines 518 are connected to precision orifices 520-1, 520-2, ..., and 520-O (collectively referred to as precision orifices 520).

[0077] In some examples, the precision orifice 520 has varying orifice sizes. A precision orifice 520 is considered "precision" if it has a predetermined, known size and shape and is unobstructed. When the precision orifice operates in a choked state, one or more pressure sensors 530 sense the pressure upstream of the precision orifice 520. A choked 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.

[0078] Pressure sensors 530 are connected to the outputs of valves 510 and 511 and to the inlet of precision orifice 520. For example, a first of pressure sensors 530 operates in a first pressure range, while a second of pressure sensors 530 operates in a second pressure range that is the same as or different from the first pressure range. For example, the first of pressure sensors 530 measures pressures up to 50 T, while the second of pressure sensors 530 measures pressures up to 500 T, although other pressure ranges may be used. Precision orifice 520 is connected to the inlets of valves 524-1, 524-2, ..., and 524-0 (collectively, valves 524). The outlets of valves 524 are connected together and output to pump 540.

[0079] Now refer to Figure 6 , shows a hybrid flow metering controller 610. In some examples, the hybrid flow metering controller 610 includes an AFV table 620, a V eff Table 622 and V eff Estimation module 624. AFV table 620 is an empirically developed table that relates orifice pressure to flow rate on a per gas basis. eff Table 622 contains V values ​​calibrated and indexed by gas and / or desired flow rate. eff value.

[0080] The hybrid flow metering controller 610 communicates with the valve 634, the mass flow controller 636, the pressure sensor 530, and the temperature sensor 480. As will be described further below, the hybrid flow metering controller 610 controls the valve 634 based on feedback from the temperature sensor 480 and the pressure sensor 530. In some examples, V eff The estimation module 624 may be used to estimate V based on other calibrations using interpolation, formulas, or other techniques. eff value to estimate V eff .

[0081] Now refer to Figure 7A and 7B , shows a method for performing hybrid flow metering. Figure 7A In the example embodiment, method 700 is performed to determine the calibrated effective volume for the low flow rate gas. In other words, when the DMM method is to be used, the calibrated effective volume only needs to be determined for the gas to be supplied at a flow rate lower than the predetermined flow rate. In addition, calibration can be performed for each of the gases and flow rates to be used. 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 (lower than the predetermined flow rate) without calibrating them separately.

[0082] At 710, a gas and flow rate are selected for calibration of the effective volume. At 714, the effective volume of the selected gas at the selected flow rate is determined using the first and second flow metering methods.

[0083] In some examples, the effective volume V can be calculated using Equation 4. Initially, the corresponding MFC is set to one of the low flow rate settings and the DMM method is performed. During the DMM method, the initial and final pressures and temperatures are measured. The MFC is run at the same flow rate setting (with the same gas) using the orifice method. The orifice method provides the absolute (true) flow rate Q of the MFC. The effective volume V is determined using Equation 4, the absolute flow rate Q, and the initial and final pressures and temperatures.

[0084] If additional samples are needed, the method continues at 718 and calibrates another flow rate of the selected gas. When all flow rates of the selected gas have been calibrated, the method continues at 722 and determines whether to calibrate another gas. If 722 is true, the method returns to 710. Otherwise, the method ends.

[0085] exist Figure 7B , a method 750 for operating a hybrid flow metering system according to the present disclosure is shown. At 760, the method determines whether to perform flow metering. 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 a calibrated effective volume corresponding to a selected gas and / or flow rate. If 764 is false, the method uses a second flow metering method. In some examples, the second flow metering method comprises an orifice-based method.

[0086] Now refer to Figure 8 , shows a method 800 for performing flow metering. At 810, a gas line is pumped from a gas box to an orifice. At 814, a valve is closed to isolate the gas line from the MFC outlet to the orifice. At 816, the method waits for an adaptation period to allow kinetic energy to dissipate and the gas to reach wall temperature. In some examples, the adaptation period is in the range of 10 seconds 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 flow is supplied at a desired flow rate. The gas line, manifold, and other structures are filled at the desired flow rate output by the MFC for a predetermined period Δt. At 830, the secondary valve of the MFC is closed and flow is stopped. At 834, the method waits for the adaptation period. At 838, noise from the pressure sensor is filtered, the pressure is measured, and a final mass is determined based on the measured pressure and the effective volume (for the selected gas and / or selected flow rate). At 842 , a flow rate is determined based on the final mass, the initial mass, and Δt.

[0087] Now refer to Figure 9 , for the example DMM method, the measured pressure is displayed as a function of time. After the gas line is evacuated, 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 Next, the MFC is set to the desired flow rate to be calibrated within a period of Δt. After the period of Δt, the gas is allowed to settle to eliminate the pressure gradient along the gas supply line and reach equilibrium temperature with surfaces such as the inner wall of the gas line. This results in a slight change in the final pressure p2.

[0088] Now refer to Figure 10 , shows a method 1000 for providing additional confirmation of the calibration of an MFC. In some examples, during operation, a first flow metering system and a second flow metering system will have one or more flow rates overlapping 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 certain examples, both the first flow metering system and the second flow metering system can be used to calibrate the same desired flow rate of the MFC. For example, both metering systems can be used to calibrate at 10 sccm.

[0089] The results of the calibration using the first flow metering system and the second flow metering system can be compared. If the results fall within a predetermined tolerance, then the first and second flow metering systems are performing correctly. If the results are not within the predetermined tolerance, the system can send a notification, generate an alert message, activate a warning light, and / or take other action.

[0090] At 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 approximates a predetermined flow rate for switching between the first metering system and the second metering system. For example, the desired flow rate of the MFC may be in the range of 5 sccm to 15 sccm.

[0091] 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, at 1052, the system sends a notification, generates an alert message, activates a warning light, or takes other action.

[0092] The foregoing description is merely illustrative in nature and is in no way intended to limit the present disclosure, its application or use. The broad teachings of the present disclosure can be implemented in various forms. Therefore, although the present disclosure includes specific examples, the true scope of the present disclosure should not be so limited, because other modifications will become apparent when studying the drawings, description and appended claims. It should be understood that one or more steps in the method can be performed in a different order (or simultaneously) without changing the principles of the present disclosure. In addition, although each embodiment is described above as having certain features, any one or more of those features described with respect to any embodiment of the present disclosure can be implemented in the features of any other embodiment and / or combined with the features of any other embodiment, even if the combination is not explicitly described. In other words, the embodiments described are not mutually exclusive, and the replacement of one or more embodiments with each other remains within the scope of the present disclosure.

[0093] Various terms are used to describe the spatial and functional relationships between elements (e.g., between modules, between circuit elements, between semiconductor layers, etc.), including "connected," "engaged," "coupled," "adjacent," "next to," "on top of," "above," "below," and "disposed." Unless the relationship between a first and a second element is explicitly described as "direct," when such a relationship is described in the above disclosure, the relationship can be a direct relationship, in which there are no other intervening elements between the first and second elements, but can also be an indirect relationship, in which there are one or more intervening elements (spatially or functionally) between the first and second elements. As used herein, the phrase "at least one of A, B, and C" should be construed to mean a logical (A or B or C), using a non-exclusive logical OR, and should not be construed to mean "at least one of A, at least one of B, and at least one of C."

[0094] In some implementations, the controller is part of a system that can be part of the examples above. Such a system can include semiconductor processing equipment that 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 can be integrated with electronic devices for controlling their operation before, during, and after processing of semiconductor wafers or substrates. The electronic device can be referred to as a "controller" that can control various components or subcomponents of one or more systems. Depending on the processing requirements and / or system type, the controller can be programmed to control any process disclosed herein, including the delivery of process 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 in and out tools and other transfer tools and / or load locks connected to or interfaced with a specific system.

[0095] In general, a controller can be defined as an electronic device having various integrated circuits, logic, memory, and / or software that receive instructions, issue instructions, control operations, enable cleaning operations, enable endpoint measurements, and the like. The integrated circuits can include chips in the form of firmware that stores 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). The program instructions can be instructions sent to the controller in the form of various separate settings (or program files) that define operating parameters for performing a particular process on or for a semiconductor wafer or system. In some embodiments, the operating parameters can be part of a recipe defined by a process engineer to complete one or more processing steps during the manufacture of one or more layers, materials, metals, oxides, silicon, silicon dioxide, surfaces, circuits, and / or the die of the wafer.

[0096] In some implementations, the controller can be part of or coupled to a computer that is integrated with the system, coupled to the system, otherwise networked to the system, or a combination thereof. For example, the controller can be in the "cloud" or all or part of a wafer fab host system that can allow remote access to wafer processing. The computer can enable remote access to the system to monitor the current progress of manufacturing operations, review the history of past manufacturing operations, review trends or performance metrics for multiple manufacturing operations, change parameters of the current process, set processing steps to follow the current process, or start a new process. In some examples, a remote computer (e.g., a server) can provide process recipes to the system via a network (which can include a local network or the Internet). The remote computer can include a user interface that enables the input or programming of parameters and / or settings, which are then sent from the remote computer to the system. In some examples, the controller receives instructions in the form of data that specify parameters for each processing step to be performed during one or more operations. It should be understood that the parameters can be specific to the type of process to be performed and the type of tool the controller is configured to interface with or control. Thus, as described above, the controller can be distributed, for example, by including one or more discrete controllers networked together and working toward a common purpose (e.g., process and control as described herein). An example of a distributed controller for such a purpose is one or more integrated circuits on a chamber communicating with one or more integrated circuits remotely (e.g., at a platform level or as part of a remote computer), which combine to control the process on the chamber.

[0097] Example systems may include, but are not limited to, plasma etch chambers or modules, deposition chambers or modules, spin rinse chambers or modules, metal plating chambers or modules, cleaning chambers or modules, bevel edge etch 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 etch (ALE) chambers or modules, ion implantation chambers or modules, track chambers or modules, and any other semiconductor processing system that may be associated with or used in the manufacture and / or preparation of semiconductor wafers.

[0098] As described above, depending on one or more processing steps to be performed by the tool, the controller can 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 factory, a host computer, another controller, or tools used in the material transport of wafer containers to and from tool locations and / or load ports in a semiconductor manufacturing facility.

Claims

1. A gas flow metering system for a substrate processing system, comprising: N primary valves selectively enable gas to flow from N gas sources, respectively, where N is an integer; N mass flow controllers, respectively connected to the N primary valves, for respectively flowing N gases from the N gas sources; N secondary valves selectively allowing gas to flow from the N mass flow controllers, respectively; a gas flow path connecting the N secondary valves to a flow metering system located remote from the N secondary valves, wherein the gas flow path comprises a gas line; and A controller configured to perform a first flow metering of a selected gas at a desired flow rate from one of the N mass flow controllers by: evacuating the airflow path; measuring an initial pressure in the airflow path; determining an initial mass in the airflow path; causing the selected gas to flow from the one of the N mass flow controllers at the desired flow rate during a predetermined period; measuring a final pressure in the airflow path; determining a final mass in the airflow path; as well as An actual flow rate is determined based on the initial mass, the final mass, and the predetermined period of time. 2 . The gas flow metering system of claim 1 , wherein the controller is further configured to determine an effective volume of the gas flow path for the selected gas and the desired flow rate. 3 . The gas flow metering system of claim 2 , wherein the controller is further configured to determine the actual flow rate based further on the effective volume. The gas flow metering system of claim 1 , wherein the gas flow path further comprises a manifold and a valve.

5. The gas flow metering system of claim 1, wherein the controller is configured to use the first flow metric when determining the actual flow rate if the desired flow rate is less than a predetermined flow rate.

6. The gas flow metering system of claim 5, wherein the predetermined flow rate is in the range from 5 sccm to 15 sccm.

7. The gas flow meter system of claim 5, wherein the controller is configured to determine the actual flow rate using a second flow metric different from the first flow metric when the desired flow rate is greater than the predetermined flow rate.

8. The gas flow metering system of claim 7, wherein the predetermined flow rate is in the range from 5 sccm to 15 sccm.

9. The gas flow metering system of claim 7, wherein the second flow meter comprises an orifice-based metering.

10. The gas flow metering system according to claim 5, further comprising: orifice; a valve connected to an outlet of the orifice; and a pressure sensor for sensing the pressure at the inlet of the orifice, Wherein the controller is configured to determine the actual flow rate using the valve, the pressure sensor, and the orifice when the desired flow rate is greater than the predetermined flow rate.

11. The gas flow metering system of claim 1, wherein the controller is configured to wait for a first predetermined adaptation period after evacuating the gas flow path and before measuring the initial pressure in the gas flow path.

12. The gas flow metering system of claim 1 , wherein the controller is configured to wait for a second predetermined adaptation period after causing the selected gas to flow from the 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.

13. A gas flow metering system for a substrate processing system, comprising: a gas box comprising N mass flow controllers to respectively control gas flows from N gas sources, wherein N is an integer; an air flow path in fluid communication with the air box; a hybrid flow metering system in fluid communication with the airflow path and comprising a controller configured to: performing a first flow metering to calibrate the at least one of the N mass flow controllers based on a differential mass of gas in the gas flow path between the gas box and a flow metering system during a predetermined period when a desired flow rate of gas supplied by the at least one of the N mass flow controllers is less than a predetermined flow rate; and A second flow measurement is performed 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.

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

15. The gas flow meter system of claim 14, wherein the first flow metric further determines the differential mass based on the effective volume of the gas flow path for the gas at the desired flow rate.

16. The gas flow metering system of claim 13, wherein the second flow meter is an orifice-based method.

17. The gas flow metering system of claim 14, wherein the hybrid flow metering system comprises a controller configured to determine the effective volume of the gas flow path for a selected gas and a selected flow rate.

18. The gas flow metering system of claim 17, wherein the controller is further configured to determine the actual flow rate based further on the effective volume.

19. The gas flow metering system of claim 13, wherein the gas flow path further comprises a manifold and a valve.

20. The gas flow metering system of claim 13, wherein the predetermined flow rate is in a range from 5 seem to 15 seem.

21. The gas flow metering system according to claim 13, further comprising: orifice; a valve connected to an outlet of the orifice; and a pressure sensor for sensing the pressure at the inlet of the orifice, Wherein the controller is configured to determine an actual flow rate using the valve, the pressure sensor, and the orifice when the desired flow rate is greater than the predetermined flow rate.

22. The gas flow metering system according to claim 17, wherein the controller is configured to perform the first flow metering by: evacuating the airflow path; measuring an initial pressure in the airflow path; determining an initial mass in the airflow path; causing the selected gas to flow from the one of the N mass flow controllers at the desired flow rate during a predetermined period; measuring a final pressure in the airflow path; determining a final mass in the airflow path; as well as An actual flow rate is determined based on the initial mass, the final mass, and the predetermined period of time.

23. A gas flow metering system according to claim 22, wherein the controller is arranged to wait for a first predetermined adaptation period after evacuating the gas flow path and before measuring the initial pressure in the gas flow path.

24. The gas flow metering system of claim 22, wherein the controller is configured to wait for a second predetermined adaptation period after causing the selected gas to flow from the 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.

25. A method for performing gas flow metering in a substrate processing system, comprising: providing a gas box comprising N mass flow controllers for respectively controlling gas flows from N gas sources, wherein N is an integer; providing an air flow path in fluid communication with the air box; using a first flow meter to calibrate the at least one of the N mass flow controllers based on a differential mass of gas in the gas flow path between the gas box and a flow meter system during a predetermined period when a desired flow rate of gas supplied by the at least one of the N mass flow controllers is less than a predetermined flow rate; as well as A second flow metric is used 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.

26. The method of claim 25, wherein the first flow metric and the second flow metric are used to determine an effective volume of the gas flow path for the gas at the desired flow rate.

27. The method of claim 26, wherein the first flow metric further determines the differential mass based on the effective volume of the gas flow path for the gas at the desired flow rate.

28. The method of claim 25, wherein the second flow meter is an orifice-based method.

29. The method of claim 25, wherein the predetermined flow rate is in a range from 5 seem to 15 seem.

30. The method of claim 25, wherein the first flow measurement comprises: evacuating the airflow path; measuring an initial pressure in the airflow path; determining an initial mass in the airflow path; causing a selected gas to flow from said one of said N mass flow controllers at said desired flow rate during a predetermined period of time; measuring a final pressure in the airflow path; determining a final mass in the airflow path; as well as An actual flow rate is determined based on the initial mass, the final mass, and the predetermined period of time.

31. The method of claim 30, further comprising: After evacuating the airflow path and before measuring the initial pressure in the airflow path, a first predetermined adaptation period is waited.

32. The method of claim 31 , further comprising: After flowing the selected gas at the desired flow rate from the one of the N mass flow controllers during a predetermined period and before measuring the final pressure in the gas flow path, a second predetermined adaptation period is waited.

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