Hybrid flow metrology for improved chamber matching

Abstract

SOLUTION: A gas delivery system for a substrate processing system includes a gas box including mass flow controllers controlling a flow of gas from gas sources. A gas flow path is in fluid communication with the gas box. A hybrid flow measurement system is in fluid communication with the gas flow path, and includes a controller configured to perform first flow measurement. The first flow measurement is for calibrating at least one of the mass flow controllers on the basis of a differential mass of gas in the gas flow path between the gas box and the flow measurement system during a predetermined period when a desired flow rate for gas supplied by the at least one of the mass flow controllers is less than a predetermined flow rate. The controller is configured to perform second flow measurement when the desired flow rate is greater than the predetermined flow rate.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Patent Application No. 16 / 056,980, filed August 7, 2018. The entire disclosures of the above-referenced applications are incorporated herein by reference.

[0002] FIELD OF THE DISCLOSURE The present disclosure relates to flow measurements for substrate processing systems, and more particularly, to hybrid flow measurements for substrate processing systems. [Background technology]

[0003] The background description provided herein is intended to provide a general overview of the contents of the present disclosure. Work by the currently named inventors within the scope of what is described in this Background section, as well as aspects of the description that may not otherwise be regarded as prior art at the time of filing, are not admitted, expressly or impliedly, as prior art against the present disclosure.

[0004] Substrate processing systems may be used to perform etching, deposition, and / or other processing of substrates, such as semiconductor wafers. Examples of processes that may 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 to the processing chamber for processing the substrate. A plasma may be struck to enhance chemical reactions in the processing chamber. An RF bias may also be supplied to the substrate support to control ion energy.

[0005] To improve quality and reduce defects, one or more metrology systems can be used to verify the operation of a processing chamber. For example, a flow measurement system can be used to verify the flow rate of a gas delivery system that provides a gas mixture. When multiple substrate processing chambers are disposed within a substrate processing tool, gas lines are used to connect the gas delivery system of each processing chamber to the multiplexed flow measurement system.

[0006] The flow measurement system may include an orifice-based steady-state flow measurement device. The gas delivery system is typically required to calibrate and supply flow rates of 10-3000 sccm. Gases entering the gas lines at low flow rates take a long time to reach the flow measurement device and build up enough pressure for measurement, adversely affecting measurement times during tool startup. In other words, calibration of flow rates of 10-hundreds of sccm takes a long time. Recently, process recipes also require calibration and supply of flow rates of 0.1-10 sccm. As can be appreciated, unacceptable time delays can occur during calibration or chamber matching of flow rates as low as 0.1-10 sccm using orifice-based methods. Summary of the Invention

[0007] A measurement system for a substrate processing system includes N primary valves that selectively flow gases from N gas sources, where N is an integer. N mass flow controllers are connected to the N primary valves, respectively, and flow N gases from the N gas sources. N secondary valves selectively flow gases from the N mass flow controllers, respectively. A gas flow path connects the N secondary valves to a flow measurement system located remotely from the N secondary valves. The gas flow path includes a gas line. A controller is configured to perform a first flow measurement on a select gas flowed at a desired flow rate from one of the N mass flow controllers, and is configured to perform the first flow measurement by evacuating the gas flow path; measuring an initial pressure in the gas flow path; determining an initial mass in the gas flow path; flowing the select gas at the desired flow rate from one of the N mass flow controllers for 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.

[0008] In other features, the controller is further configured to determine an effective volume of the gas flow path for the selected gas and a desired flow rate. The controller is further configured to determine a flow rate based on the effective volume. The gas flow path further comprises a manifold and a valve. The controller is configured to use the first flow measurement in 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.

[0009] In other features, the controller is configured to determine the actual flow rate using a second flow measurement different from the first flow measurement when the desired flow rate exceeds a predetermined flow rate, the predetermined flow rate being in a range of 5 sccm to 15 sccm.

[0010] In other features, the second flow measurement includes an orifice-based measurement. 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 an actual flow rate using the valve, the pressure sensor, and the orifice when the desired flow rate exceeds a predetermined flow rate.

[0011] In other features, the controller is configured to wait a first predetermined dwell period after evacuating the gas flow path before measuring an initial pressure in the gas flow path, and the controller is configured to wait a second predetermined dwell period after flowing the select gas at a desired flow rate through one of the N mass flow controllers for a predetermined period before measuring a final pressure in the gas flow path.

[0012] The gas delivery system of the substrate processing system includes a gas box including N mass flow controllers each controlling a flow of gas from N gas sources, where N is an integer. The gas flow path is in fluid communication with the gas box. The hybrid flow measurement system includes a controller in fluid communication with the gas flow path and configured to perform a first flow measurement. The first flow measurement is to calibrate at least one of the N mass flow controllers based on a mass difference of gas in the gas flow path between the gas box and the flow measurement system during a predetermined time period Δt if a desired flow rate for the gas delivered by at least one of the N mass flow controllers is less than a predetermined flow rate. The controller is configured to perform a second flow measurement to calibrate at least one of the N mass flow controllers if a desired flow rate for the at least one of the N mass flow controllers exceeds the predetermined flow rate.

[0013] In other features, the first flow measurement and the second flow measurement are used to determine an effective volume of a gas flow path for the gas at a desired flow rate. The first flow measurement further determines a mass difference based on the effective volume of the gas flow path for the gas at the desired flow rate. The second flow measurement is an orifice-based method.

[0014] In other features, the hybrid flow meter 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 flow rate based on the effective volume. The gas flow path further comprises a manifold and a valve. The predetermined flow rate is in the range of 5 sccm to 15 sccm.

[0015] In other features, a valve is connected to the outlet of the orifice. A pressure sensor senses pressure at the 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 exceeds a predetermined flow rate.

[0016] In other features, the controller is configured to perform a first flow measurement by evacuating the gas flow path, measuring an initial pressure in the gas flow path, determining an initial mass in the gas flow path, flowing a selected gas at a desired flow rate from one of the N mass flow controllers for 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.

[0017] In other features, the controller is configured to wait a first predetermined dwell period after evacuating the gas flow path before measuring an initial pressure in the gas flow path, and the controller is configured to wait a second predetermined dwell period after flowing the select gas at a desired flow rate through one of the N mass flow controllers for a predetermined period before measuring a final pressure in the gas flow path.

[0018] A method of performing gas flow metrology in a substrate processing system includes providing a gas box including N mass flow controllers each controlling a flow of gas 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 calibrating at least one of the N mass flow controllers based on a mass difference of gas in the gas flow path between the gas box and the flow measurement system during a predetermined time period using a first flow measurement if a desired flow rate for a gas supplied by at least one of the N mass flow controllers is less than a predetermined flow rate. The method includes calibrating at least one of the N mass flow controllers using a second flow measurement if a desired flow rate for at least one of the N mass flow controllers exceeds the predetermined flow rate.

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

[0020] In other features, the first flow measurement further determines a mass difference based on an effective volume of the gas flow path for the gas at the desired flow rate.

[0021] In another feature, the second flow measurement is an orifice type method. The predetermined flow rate is in the range of 5 sccm to 15 sccm.

[0022] In other features, the first flow measurement includes evacuating the gas flow path, measuring an initial pressure in the gas flow path, determining an initial mass in the gas flow path, flowing a selected gas at a desired flow rate from one of N mass flow controllers for 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.

[0023] In other features, the method includes waiting a first predetermined dwell period after evacuating the gas flow path before measuring an initial pressure in the gas flow path. The method includes waiting a second predetermined dwell period after flowing a select gas at a desired flow rate from one of the N mass flow controllers for a predetermined period before measuring a final pressure in the gas flow path.

[0024] Other areas of applicability of the present disclosure will become apparent from the detailed description, claims, and drawings. The detailed description and specific examples are for purposes of illustration only and are not intended to limit the scope of the present disclosure. [Brief description of the drawings]

[0025] The present disclosure will become more fully understood from the detailed description and the accompanying drawings, wherein:

[0026] [Figure 1] FIG. 1 is a functional block diagram of an example of a substrate processing system.

[0027] [Diagram 2] FIG. 2 is a functional block diagram of an example substrate processing tool.

[0028] [Diagram 3] FIG. 3 is a functional block diagram of a gas delivery system according to the present disclosure that can be used in the systems of FIGS.

[0029] [Figure 4] FIG. 4 is a functional block diagram of an example gas box according to the present disclosure.

[0030] [Diagram 5] FIG. 5 is a functional block diagram of an example hybrid flow measurement system according to the present disclosure.

[0031] [Figure 6]FIG. 6 is a functional block diagram of an example hybrid flow measurement controller according to the present disclosure.

[0032] [Figure 7A] FIG. 7A is a flow chart illustrating an example of a method for implementing a hybrid flow meter according to the present disclosure. [Figure 7B] FIG. 7B is a flow chart illustrating an example of a method for implementing a hybrid flow meter according to the present disclosure.

[0033] [Figure 8] FIG. 8 is a flow chart illustrating an example of a mass difference method according to the present disclosure.

[0034] [Figure 9] FIG. 9 is a graph showing pressure as a function of time in a mass difference method according to the present disclosure.

[0035] [Figure 10] FIG. 10 is a flow chart illustrating one example of a method for using changes over time for an effective volume calculation for a given gas as an additional metrology check according to the present disclosure.

[0036] In the drawings, reference numbers may be reused to refer to similar and / or identical elements. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0037] In an orifice-based flow metering system, such as an absolute flow verification (AFV), gas is delivered to a pump from a mass flow controller (MFC) through an orifice bank. The orifice bank contains multiple precision orifices that can be selected using corresponding valves. Pressure builds up upstream of one 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 empirically developed gas tables that relate orifice pressure to gas flow rate for each gas. Temperature compensation can also be applied to account for temperature changes and determine the actual gas flow rate of the MFC.

[0038] Measurement times for AFV are significantly longer at low flow rates due to the time required to fill and pressurize the gas flow path downstream of the MFC and upstream of the selected orifice. The gas flow path typically includes gas supply lines, manifolds, valves, etc. (located between the gas box and the flow measurement system). Longer calibration periods result in longer downtimes required to perform gas flow calibrations during initial setup and subsequent chamber alignment. At very low flow rates and with longer gas supply lines, it is difficult to detect when the orifice flow has stabilized (and steady-state pressure has been achieved). Small changes in pressure rise are difficult to detect due to the increased volume of the gas lines.

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

[0040] As described further below, the DMM method fills a gas volume in a gas line, valve, manifold, etc. between a gas box and a flow measurement system. In some examples, the gas volume is evacuated and an initial pressure is measured after a settling period. An initial mass is determined based on the initial pressure and the effective volume of a flow path through the gas lines, manifolds, valves, and / or other volumes located between the gas box and the flow measurement system.

[0041] After the initial mass is determined, the valve is opened and the MFC flows gas at the desired flow rate (to be calibrated) for a predefined period Δt. The pressure in the gas volume between the gas box and the flow measurement system steadily increases. After the predefined 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] The DMM method is similar to chamber ROR (rate of rise), but the DMM method uses the volumes of gas lines, valves, manifolds, etc., rather than the chamber / tank volume, to calculate the mass flow rate. In ROR, the governing equation for calculating the mass flow rate is obtained after taking the time derivative of the equation of state. During gas compression in the ROR tank, the transient pressure and temperature are sampled over time to calculate the rate of change of pressure / temperature.

[0043] More specifically, when implementing 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 gas mass delivered to the enclosure based on the following gas equation of state:

number

[0044] The equation for the absolute gas flow rate Q is:

number

[0045] The effect of compressibility becomes important only for polyatomic gases as pressure and temperature approach atmospheric (ATM) conditions. However, even for polyatomic gases, the effect of compressibility can be neglected because the pressure downstream of the MFC is lower than atmospheric pressure and can be maintained an order of magnitude lower than ATM pressure when pressurizing the gas volume in the DMM method. Thus, the flow equation simplifies to:

number

[0046] In some examples, the gas in the enclosure is allowed to rest for a predefined settling period before measuring the initial and final values ​​of p and T. This settling period reduces the effect of the kinetic energy of the gas and eliminates pressure gradients due to gas flow. This settling 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), eliminating the effects of gas expansion or compression, respectively.

[0047] The gas expansion phenomenon occurs when the enclosure is evacuated at the beginning of a metrology calibration to remove any gas residue (from a previous measurement). When gas is fed into the enclosure, it is compressed and heated, causing the temperature to increase. It is not possible to accurately measure the gas temperature directly, since it is not practical to use a fast temperature sensor in the gas path (due to the risk of potential sensor damage from exposure to corrosive gases).

[0048] When the gas is stabilized during the settling period, the initial and final gas temperatures are the initial wall temperature T W1and the final wall temperature T W2 Similarly, the initial and final pressures (p1 and p2) are equal to, respectively, due to the elimination of pressure gradients along the length of the gas supply line and the change in gas temperature. TIFF2025024118000005.tif14170 and TIFF2025024118000006.tif12170. As a result, the flow equation simplifies to:

number

[0049] As mentioned above, the enclosure in the DMM method (the internal volume of the gas lines, valves, manifolds, etc.) behaves differently than the enclosure in 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 (gas lines, valves, manifolds, etc.) in the DMM method introduced errors. In other words, the effective volume V (calculated using a known flow rate) eff differs significantly from the expected internal volume.

[0050] Part of the volume difference is due to variations in geometric manufacturing tolerances. Also, the calibrated effective volume V eff Experiments have shown that can vary with gas and flow rate. These differences can be due to a variety of other factors. For example, these differences can be due to the relatively small volumes of the gas supply lines (which are further affected by manufacturing tolerance variations in the gas lines, internal valves, and / or substrate volumes). Differences can also be due to the overall complex geometry of the supply volume assembly (long tubular shape with internal valves) compared to the simple uniform geometry of the tanks used in the ROR process.

[0051] The ROR method uses a tank with a much larger volume compared to the gas flow path including the gas supply line. The pressure gradient in the gas supply line due to the viscous effect of the gas flow has a significant effect and if not properly taken into account, it will lead to inaccurate calculation of the mass flow rate. Therefore, the ROR method cannot be applied when using the volume of the gas line as the enclosure and a single pressure measurement point.

[0052] However, this problem is solved by calculating the calibrated effective volume V (rather than the theoretical actual volume) for each gas and / or flow rate. eff As will be further explained below, orifice technology or another flow measurement method can be employed to calculate a calibrated effective volume.

[0053] More specifically, the effective volume V can be calculated using Equation 4. First, the corresponding MFC is set to one of multiple low flow rate set points and the DMM method is performed. During the DMM method, the initial and final pressure and temperature are measured. The MFC is operated at the same flow rate set point (with the same gas) using the orifice method. The orifice method gives the absolute flow rate (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 pressure and temperature.

[0054] The calculation of the effective volume is required only once at the initial start-up of the tool and only for low gas flow rates. This one-time calibration also accounts for the variation in manufacturing tolerances of the gas delivery lines from tool to tool for chamber flow matching. Therefore, chamber matching can be performed more quickly using the hybrid method. In addition, by calibrating the DMM method (used for low flow rates) with the orifice technology method (used for high flow rates), mismatches or overlaps at the flow junction can be eliminated when switching between the two methods. The proposed hybrid flow measurement also has the added benefit of being able to track and monitor the calculation at the flow junction as an additional system health check, eliminating drift in accuracy over time.

[0055] AFV is described in further detail in commonly assigned U.S. Patent No. 7,822,570, entitled "Methods for Performing Actual Flow Verification," issued Oct. 26, 2010, which is incorporated herein by reference in its entirety, and ROR is described in further detail in commonly assigned U.S. Patent No. 9,778,083, which is also assigned to the present assignee.

[0056] Reference is now made to FIG. 1, which illustrates an exemplary substrate processing system 120. Although an example of a processing chamber for etching, chemical vapor deposition, or atomic layer deposition (ALD) using a capacitively coupled plasma (CCP) is illustrated, the flow measurement systems and methods described herein can be used in any other type of system or substrate processing system. For example, the flow measurement systems and methods described herein can be used in substrate processing systems using remote plasma or inductively coupled plasma (ICP). Additionally, the systems and methods described herein can be used in any other semiconductor equipment requiring accurate flow measurement.

[0057] The substrate processing system 120 includes a processing chamber 122 that encloses 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.

[0058] By way of example only, the upper electrode 124 may include a gas distributor 129, such as a showerhead, for introducing and distributing process gases. The gas distributor 129 may include a stem portion having one end connected to the top surface of the processing chamber. A base portion is generally cylindrical and extends radially outward from the other end of the stem portion at a location spaced from the top surface of the processing chamber. The substrate-facing surface or faceplate of the showerhead base portion includes a number of holes through which precursors, reactants, etching gases, inert gases, carrier gases, other process gases, or purge gases flow. Alternatively, the upper electrode 124 may include a conductive plate, or the process gases may be introduced in another manner.

[0059] The substrate support 126 includes a base plate 130 that acts as a bottom electrode. The base plate 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 base plate 130. The base plate 130 may include one or more channels 136 for flowing a coolant through the base plate 130.

[0060] If a plasma is used, an RF generating system 140 generates and outputs an RF voltage to either the upper electrode 124 or the lower electrode (e.g., the base plate 130 of the ESC 126). The other of the upper electrode 124 and the base plate 130 may be DC grounded, AC grounded, or floating. By way of example only, the RF generating system 140 may include an RF generator 142 that generates RF power that is delivered to the upper electrode 124 or the base plate 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, ..., 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 by valves 154-1, 154-2, ..., and 154-N (collectively, valves 154) and MFCs 156-1, 156-2, ..., and 156-N (collectively, MFCs 156). Secondary valves may be used between the MFCs 156 and the manifold 160. Although one gas delivery system 150 is shown, more than one gas delivery system may be used.

[0062] The temperature controller 163 may be connected to a number of thermal control elements (TCEs) 164 disposed within the heating plate 132. The temperature controller 163 may be used to control the number of TCEs 164 to control the temperature of the substrate support 126 and the substrate 128. The temperature controller 163 may be in communication with a coolant assembly 166 to control the flow of coolant through the channel 136. For example, the coolant assembly 166 may 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 may be used to evacuate reactants from the processing chamber 122. A system controller 180 may be used to control the components of the substrate processing system 120.

[0063] 2, the flow measurement systems and methods described herein can be used to provide and reduce cost flow measurement of gases supplied to one or more substrate processing tools 210. Illustrated is one example of a substrate processing tool 210, although other substrate processing tools may be used.

[0064] The substrate processing tool 210 includes a robot 212 disposed at a central location. The robot 212 can operate at vacuum or atmospheric pressure. The substrate processing tool 210 includes a number of stations (or substrate processing chambers) 216-1, 216-2, ..., and 216-S (collectively stations 216), where S is an integer greater than 1, disposed around the robot 212. The stations 216 can be disposed around the center of the substrate processing tool 210 with uniform or irregular angular offsets. Examples of the stations 216 can include one or more of deposition, etch, pre-clean, post-clean, spin-clean, etc.

[0065] The substrates may be initially placed in a cassette 234. A robot and load lock, generally indicated at 238, may be used to move the substrates from the cassette 234 to the substrate processing tool 210. Once processing is complete, the robot and load lock 238 may return the substrates to the cassette 234 and / or to another cassette 239. As described further below, a gas delivery system supplies gas to the stations and a flow measurement system calibrates the gas flow rates.

[0066] 3, the illustrated gas delivery system 300 includes multiple gas boxes 310-1, 310-2, ... 310-10 (collectively, gas boxes 310). Although ten gas boxes are shown, the gas delivery system 300 may include more or fewer gas boxes. The gas boxes 310-1, 310-2, ... 310-10 are connected to a hybrid flow measurement system 320 by first gas lines 312-1, 312-2, ... 312-10 (collectively, first gas lines 312). The first gas lines 312 may be connected to the hybrid flow measurement system 320 via a manifold 313. Return gas from the hybrid flow metering system 320 is connected to the gas boxes 310-1, 310-2, ... 310-10 by second gas lines 314-1, 314-2, ... 314-10 (collectively second gas lines 314). The second gas lines 314 exit the hybrid flow metering system 320 into a manifold 315 and are split into individual lines connected to the gas boxes 310-1, 310-2, ... 310-10.

[0067] Gas lines 316-1, 316-2, ... 316-10 (collectively gas lines 316) connect the outputs of the gas boxes 310-1, 310-2, ... 310-10 to the processing chambers. 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, thereby reducing costs.

[0068] Reference is now made to FIG. 4, which illustrates one of the gas boxes 310. Gas sources 410-1, 410-2, ..., and 410-G (collectively gas sources 410) are connected to flow control devices including 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, 442 are connected to a hybrid flow metering system 320. Valve 442 is associated with gas flowing through gas line 312 to hybrid flow metering system 320. Valve 440 is associated with gas returning from the hybrid flow metering system 320 through gas line 314. Valve 448 is associated with gas flowing through gas line 316 to a process chamber associated with the gas box 310. One or more temperature sensors 480 can be used to sense the temperature of the gas lines. In some examples, portions of the gas lines are heated by resistive heaters (not shown).

[0069] Reference is now made to Figure 5, which illustrates a portion of a hybrid flow metering system. Inlet B to hybrid flow metering system 220 is connected to valve 510. Inlet B' associated with gas boxes GB2, GB4, GB6, GB8, and GB10 is connected to valve 511. The outlets of valves 510 and 511 are connected by manifold 513 to a number of gas lines 518-1, 518-2, ..., and 518-O (where O is an integer equal to or greater than 1) (collectively, gas lines 518). Gas lines 518 are connected to precision orifices 520-1, 520-2, ..., and 520-O (collectively, precision orifices 520).

[0070] In some examples, the precision orifices 520 have a variety of orifice sizes. The precision orifices 520 are considered "precise" when the orifices have a predetermined, known size and shape and are unobstructed. One or more pressure sensors 530 sense the pressure upstream from the precision orifice 520 when the precision orifice is operating in a choked flow condition. The choked flow condition 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 outlets of valves 510 and 511 and the inlet of precision orifice 520. For example, first pressure sensor 530 operates in a first pressure range and second pressure sensor 530 operates in a second pressure range that is the same or different than the first pressure range. For example, first pressure sensor 530 measures pressures up to 50T and second pressure sensor 530 measures pressures up to 500T, although other pressure ranges may be used. Precision orifice 520 is connected to the inlets of valves 524-1, 524-2, ..., and 524-O (collectively valves 524). The outlets of valves 524 are connected together and output to pump 540.

[0072] Reference is now made to FIG. 6, which illustrates a hybrid flow measurement controller 610. In some examples, the hybrid flow measurement controller 610 includes an AFV table 620 and a V eff Table 622 and V eff and an estimation module 624. The AFV table 620 is an empirically developed table that relates orifice pressure to flow rate for each gas. eff Table 622 is a V eff Contains a value.

[0073] The hybrid flow measurement controller 610 is in communication with the valve 634, the mass flow controller 636, the pressure sensor 530, and the temperature sensor 480. The hybrid measurement controller 610 controls the valve 634 based on feedback from the temperature sensor 480 and the pressure sensor 530, as described further below. In some examples, V eff The estimation module 624 may use interpolation, formulas, or other techniques to estimate the other V eff Based on the value of V eff may be used to estimate

[0074] Reference is now made to Figures 7A and 7B, which illustrate a method for implementing hybrid flow metering. In Figure 7A, a method 700 for determining a calibrated effective volume for a low flow rate gas is implemented. In other words, a calibrated effective volume needs to be determined only for gases delivered at flow rates below the predetermined flow rate for which the DMM method is used. Furthermore, a calibration may be performed for each of the flow rates and gases used. Alternatively, one or more calibrations may be performed for one or more gases and one or more flow rates. For other gases and / or other flow rates (below the predetermined flow rate), the flow rate may be determined using interpolation, formulas, or other compensations without individual calibration.

[0075] A gas and flow rate for which to calibrate the effective volume is selected at 710. At 714, a first and second flow measurement method are used to determine the effective volume at the selected flow rate for the selected gas.

[0076] In some examples, the effective volume V can be calculated using Equation 4. First, the corresponding MFC is set to one of multiple low flow rate set points and the DMM method is performed. During the DMM method, the initial and final pressure and temperature are measured. The MFC is operated at the same flow rate set point (with the same gas) using the orifice method. The orifice method gives the absolute flow rate (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 pressure and temperature.

[0077] If additional samples are needed, the method proceeds to 718 to calibrate another flow rate for the selected gas. Once all flow rates have been calibrated for the selected gas, the method proceeds to 722 to determine whether to calibrate another gas. If 722 is true, the method returns to 710. If not true, the method ends.

[0078] 7B illustrates a method 750 of operating a hybrid flow measurement system according to the present disclosure. At 760, determine whether to perform a flow measurement. If 760 is true, determine whether the desired flow rate to be calibrated is less than or equal to a first flow rate threshold TH1. If 764 is true, use the DMM method and use the calibrated effective volume corresponding to the selected gas and / or selected flow rate. If 764 is false, use a second flow measurement method. In some examples, the second flow measurement method includes an orifice-based method.

[0079] Reference is now made to FIG. 8, which illustrates a method 800 for performing flow measurements. At 810, the gas line is pumped from the gas box to the orifice. At 814, the valve is closed and the gas line is isolated from the outlet of the MFC to the orifice. At 816, a settling period is waited to allow kinetic energy to subside and the gas line to reach wall temperature. In some examples, the settling period ranges from 10 seconds to 60 seconds. At 820, the pressure sensor noise 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 to provide flow at a desired flow rate. The gas lines, manifolds, and other structures are filled with the desired flow rate output by the MFC for a predetermined period of time Δt. At 830, the secondary valve of the MFC is closed, stopping the flow. At 834, a settling period is waited. At 838, the pressure sensor noise is filtered, the pressure is measured, and a final mass is determined based on the measured pressure and 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.

[0080] Reference is now made to FIG. 9, which shows the measured pressure as a function of time for an example of the DMM method. After evacuating the gas line, the gas is allowed to stand and the equilibrium temperature (T W2 ), which results in a slight increase in the initial pressure p1. The MFC is then set to the desired flow rate to be calibrated for a period Δt. After the period Δt, the gas is allowed to come to rest, eliminating the pressure gradient along the gas supply line and allowing the gas to reach an equilibrium temperature (T w2 ) As a result, the final pressure p2 changes slightly upward.

[0081] Reference is now made to FIG. 10, which illustrates a method 1000 for performing additional checks on the calibration of an MFC. In some examples, during operation, the first and second flow measurement systems will have one or more comparable flow rate overlaps within a predetermined range. For example, the first flow measurement system may be used to calibrate flow rates below 10 sccm, while the second flow measurement system may be used to calibrate flow rates above 10 sccm. In some examples, both the first and second flow measurement systems may be used to calibrate the same desired flow rate of the MFC. For example, both measurement systems may be used to perform a 10 sccm calibration.

[0082] Results of the calibration using the first and second flow measurement systems can be compared. If the comparison results are within a predetermined tolerance, the first and second flow measurement systems are functioning properly. If the comparison results are not within the predetermined tolerance, the system sends a notification, generates a warning message, turns on a warning light, and / or takes other action.

[0083] At 1010, the MFC is configured to flow the select gas at a desired flow rate within a predetermined flow rate range. In some examples, the predetermined flow rate range is close to a predetermined flow rate at which the first and second measurement systems are switched. For example, the desired flow rate of the MFC can be in the range of 5 sccm to 15 sccm.

[0084] At 1020, a first flow rate MFR1 is measured using a first measurement system. At 1030, a second flow rate MFR2 is measured using a second measurement 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. If not true, the system sends a notification at 1052, generates a warning message, turns on a warning light, or takes other action.

[0085] The foregoing description is merely exemplary in nature and is in no way intended to limit the disclosure, its application, or uses. The broad teachings of the disclosure can be embodied in various forms. Thus, while the disclosure includes specific examples, the true scope of the disclosure should not be limited to such examples, since other modifications will become apparent upon review of the drawings, the specification, and the following claims. It should be understood that one or more steps in a method may be performed in a different order (or simultaneously) without altering the principles of the disclosure. Furthermore, although each embodiment is described above as having certain features, any one or more of these features described with respect to any embodiment of the disclosure can be implemented in other embodiments and / or combined with any features of the other embodiments (even if such combination is not explicitly described). In other words, the described embodiments are not mutually exclusive, and it is within the scope of the disclosure to substitute one or more embodiments for one another.

[0086] Spatial and functional relationships between elements (e.g., modules, circuit elements, semiconductor layers, etc.) are described using various terms such as "connected," "engaged," "coupled," "adjacent," "next to," "on," "above," "below," and "disposed." Also, when a relationship between a first element and a second element is described in the above disclosure, unless expressly described as "direct," the relationship may be a direct relationship in which there are no other intervening elements between the first element and the second element, but may also be an indirect relationship in which there are one or more intervening elements (spatial or functional) between the first element and the second element. As used herein, the phrase at least one of A, B, and C should be interpreted in the sense of a logic (A or B or C) using a non-exclusive logical OR, and not in the sense of "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, and such a system may be part of the examples described above. Such a system may include semiconductor processing equipment including one or more processing tools, one or more chambers, one or more processing platforms, and / or specific processing components (wafer pedestals, gas flow systems, etc.). These systems may be integrated with electronics for controlling system operations before, during, and after processing of a semiconductor wafer or substrate. Such electronics may be referred to as a "controller" and may control various components or subparts of one or more systems. The controller may be programmed to control any of the processes disclosed herein depending on the processing requirements and / or type of system. Such processes may include supply 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 settings, fluid supply settings, position and motion settings, wafer loading and unloading from the tool, and wafer loading and unloading from other transport tools and / or load locks connected or interlocked with the particular system.

[0088] In broad terms, a controller may 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, etc. Integrated circuits may include chips in the form of firmware that store program instructions, digital signal processors (DSPs), chips defined as application specific integrated circuits (ASICs), and / or one or more microprocessors, i.e., microcontrollers, that execute program instructions (e.g., software). Program instructions may be instructions communicated to the controller in the form of various individual settings (or program files) that define operational parameters for performing a particular process on or for a semiconductor wafer or for a system. The operational parameters may, in some embodiments, be part of a recipe defined by a process engineer to accomplish one or more processing steps in the fabrication of one or more layers, materials, metals, oxides, silicon, silicon dioxide, surfaces, circuits, and / or wafer dies.

[0089] The controller, in some embodiments, may be part of a computer integrated with, coupled to, or otherwise networked to the system, or may be coupled to such a computer, or a combination thereof. For example, the controller may be in the "cloud" or may be all or part of a fab host computer system. This allows remote access of wafer processing. The computer may allow remote access to the system to monitor the current progress of a fabrication operation, review the history of past fabrication operations, review trends or performance criteria from multiple fabrication operations, modify parameters of a current process, set processing steps following a current process, or start a new process. In some examples, a remote computer (e.g., a server) may provide a process recipe to the system over a network. Such a network may include a local network or the Internet. The remote computer may include a user interface that allows entry or programming of parameters and / or settings, which are then communicated from the remote computer to the system. In some examples, the controller receives instructions in the form of data. Such data identifies parameters for each processing step performed during one or more operations. It should be understood that the parameters may be specific to the type of process being performed and the type of tool that the controller is configured to interface with or control. Thus, as discussed above, the controller may be distributed, for example, by having one or more individual controllers networked together and working together toward a common purpose (such as the processes and controls described herein). An example of a distributed controller for such purposes would include one or more integrated circuits on the chamber that communicate with one or more integrated circuits that are remotely located (e.g., at the platform level or as part of a remote computer) and coupled to control the process in the chamber.

[0090] Exemplary systems may include, but are not limited to, a plasma etch chamber or module, a deposition chamber or module, a spin rinse chamber or module, a metal plating chamber or module, a cleaning chamber or module, a bevel edge etch chamber or module, a physical vapor deposition (PVD) chamber or module, a chemical vapor deposition (CVD) chamber or module, an atomic layer deposition (ALD) chamber or module, an atomic layer etch (ALE) chamber or module, an ion implantation chamber or module, a tracking chamber or module, and any other semiconductor processing system that may be associated with or used in the fabrication and / or manufacturing of semiconductor wafers.

[0091] As described above, depending on the process step or steps being 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, nearby tools, tools located throughout the factory, a main computer, another controller, or tools used for material transport to and from tool locations and / or load ports within a semiconductor manufacturing factory.

Claims

1. 1. A gas flow measurement system for a substrate processing system, comprising: N primary valves, each of which selectively flows gas from N gas sources, where N is an integer; N mass flow controllers each connected to the N primary valves and each configured to flow N types of gas from the N gas sources; N secondary valves each selectively flowing gas from the N mass flow controllers; A gas flow path connecting the N secondary valves to a flow measurement system installed remotely from the N secondary valves, the gas flow path including a gas line; a controller configured to perform a first flow measurement on a selected gas flowed at a desired flow rate from one of the N mass flow controllers, the first flow measurement comprising: evacuating the gas flow path; measuring an initial pressure in the gas flow path; determining an initial mass in the gas flow path; flowing the selected gas at the desired flow rate through the one of the N mass flow controllers for 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 time period; a controller configured to implement the A gas flow measurement system comprising:

2. 2. The gas flow measurement system according to claim 1, The gas flow metering system, 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. 3. The gas flow measurement system according to claim 2, The gas flow measurement system, wherein the controller is further configured to determine the actual flow rate based on the effective volume.

4. 2. The gas flow measurement system according to claim 1, The gas flow metering system, wherein the gas flow path further comprises a manifold and a valve.

5. 2. The gas flow measurement system according to claim 1, The gas flow measurement system, wherein the controller is configured to use the first flow measurement in determining the actual flow rate if the desired flow rate is less than a predetermined flow rate.

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

7. 6. The gas flow measurement system according to claim 5, A gas flow measurement system, wherein the controller is configured to determine the actual flow rate using a second flow measurement different from the first flow measurement when the desired flow rate exceeds the predetermined flow rate.

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

9. 8. The gas flow measurement system according to claim 7, The gas flow measurement system, wherein the second flow measurement includes an orifice-type measurement.

10. 6. The gas flow measurement system according to claim 5, An orifice; a valve connected to an outlet of the orifice; a pressure sensor for detecting a pressure at an inlet of the orifice; Further equipped with the controller is configured to determine the actual flow rate using the valve, the pressure sensor, and the orifice if the desired flow rate exceeds the predetermined flow rate. Gas flow measurement system.

11. 2. The gas flow measurement system according to claim 1, The gas flow meter system, wherein the controller is configured to wait a first predetermined dwell period after evacuating the gas flow path before measuring the initial pressure in the gas flow path.

12. 2. The gas flow measurement system according to claim 1, the controller is configured to wait a second predetermined static period after flowing the selected gas at the desired flow rate from the one of the N mass flow controllers during the predetermined period and before measuring the final pressure in the gas flow path.

13. A gas flow measurement system for a substrate processing system, comprising: a gas box including N mass flow controllers each controlling a flow of gas from N gas sources, where N is an integer; a gas flow path in fluid communication with the gas box; a hybrid flow measurement system including a controller in fluid communication with the gas flow path and configured to perform a first flow measurement and a second flow measurement, The first flow measurement is to calibrate the at least one of the N mass flow controllers based on a mass difference of gas in the gas flow path between the gas box and a flow measurement system during a predetermined time period when a desired flow rate for the gas supplied by at least one of the N mass flow controllers is less than a predetermined flow rate; The second flow measurement is to calibrate the at least one of the N mass flow controllers if the desired flow rate for the at least one of the N mass flow controllers exceeds the predetermined flow rate. Hybrid flow measurement system A gas flow measurement system comprising:

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

15. 15. The gas flow measurement system according to claim 14, The gas flow measurement system, wherein the first flow measurement further determines the mass difference based on the effective volume of the gas flow path for the gas at the desired flow rate.

16. 14. The gas flow measurement system according to claim 13, A gas flow measurement system, wherein the second flow measurement is an orifice type method.

17. 15. The gas flow measurement system according to claim 14, 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.

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

19. 14. The gas flow measurement system according to claim 13, The gas flow metering system, wherein the gas flow path further comprises a manifold and a valve.

20. 14. The gas flow measurement system according to claim 13, The gas flow measurement system, wherein the predetermined flow rate is in the range of 5 sccm to 15 sccm.

21. 14. The gas flow measurement system according to claim 13, An orifice; a valve connected to an outlet of the orifice; a pressure sensor for detecting a pressure at an inlet of the orifice; Further equipped with the controller is configured to determine an actual flow rate using the valve, the pressure sensor, and the orifice if the desired flow rate exceeds the predetermined flow rate. Gas flow measurement system.

22. 18. The gas flow measurement system according to claim 17, The controller: evacuating the gas flow path; measuring an initial pressure in the gas flow path; determining an initial mass in the gas flow path; flowing the selected gas at the desired flow rate through the one of the N mass flow controllers for 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 time period; and configured to perform the first flow measurement by Gas flow measurement system.

23. 23. The gas flow measurement system according to claim 22, The gas flow meter system, wherein the controller is configured to wait a first predetermined dwell period after evacuating the gas flow path before measuring the initial pressure in the gas flow path.

24. 23. The gas flow measurement system according to claim 22, the controller is configured to wait a second predetermined static period after flowing the selected gas at the desired flow rate from the one of the N mass flow controllers during the predetermined period and before measuring the final pressure in the gas flow path.

25. 1. A method for performing gas flow measurements in a substrate processing system, comprising: providing a gas box including N mass flow controllers respectively controlling flow of gas from N gas sources, N being an integer; providing a gas flow path in fluid communication with the gas box; if a desired flow rate for the gas supplied by at least one of the N mass flow controllers is less than a predetermined flow rate, calibrating the at least one of the N mass flow controllers based on a mass difference of gas in the gas flow path between the gas box and a flow measurement system during a predetermined time period using a first flow measurement; calibrating the at least one of the N mass flow controllers using a second flow measurement if the desired flow rate for the at least one of the N mass flow controllers exceeds the predetermined flow rate. A method comprising:

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

27. 27. The method of claim 26, The method of claim 1, wherein the first flow measurement further determines the mass difference based on the effective volume of the gas flow path for the gas at the desired flow rate.

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

29. 26. The method of claim 25, The method, wherein the predetermined flow rate is in the range of 5 sccm to 15 sccm.

30. 26. The method of claim 25, The first flow measurement includes: evacuating the gas flow path; measuring an initial pressure in the gas flow path; determining an initial mass in the gas flow path; flowing a selected gas at the desired flow rate through said one of said N mass flow controllers for 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 time period; A method comprising:

31. 31. The method of claim 30, The method further comprising waiting a first predetermined dwell period after evacuating the gas flow path before measuring the initial pressure in the gas flow path.

32. 32. The method of claim 31 , the method further comprising waiting a second predetermined dwell period after flowing the selected gas at the desired flow rate from the one of the N mass flow controllers during the predetermined period before measuring the final pressure in the gas flow path.

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