Method and assembly for gas flow ratio control

Abstract

Methods and gas flow control assemblies are configured to deliver gases to a process chamber region at desired flow ratios. In some embodiments, the assemblies include one or more MFCs and a back pressure controller (BPC). The assemblies include a controller, a process gas source, a distribution manifold, a pressure sensor coupled to the distribution manifold and configured to sense a back pressure of the distribution manifold, one or more mass flow controllers connected between the distribution manifold and the process chamber to control gas flow between the distribution manifold and the process chamber, and a back pressure controller disposed in fluid parallel relationship with the one or more mass flow controllers, wherein precise flow ratio control is achieved. Alternative embodiments include an upstream pressure controller configured to control the flow of carrier gas to control back pressure. Further methods and assemblies for controlling zoned gas flow ratios are described as other aspects.

Description

[0001] This application is a divisional application of the application patent application entitled "METHODS AND ASSEMBLIES FOR GAS FLOW RATIO CONTROL" having application number 201780016943.5, filing date March 10, 2017.

[0002] RELATED APPLICATION

[0003] This application claims priority to U.S. Non-Provisional Application No. 15 / 070,342, entitled "METHODS AND ASSEMBLIES FOR GAS FLOW RATIO CONTROL" (Attorney Docket No. 23700-02 / USA), filed March 15, 2016, which is incorporated by reference in its entirety for all purposes. TECHNICAL FIELD

[0004] The present disclosure relates generally to gas flow control to processing chambers for electronic device manufacturing, and more particularly to methods and assemblies for gas flow ratio control. BACKGROUND

[0005] Semiconductor processing of a substrate in a processing chamber can be particularly sensitive to variations and perturbations in process gas flow rates. In particular, these variations can affect one or more critical dimensions and / or film thicknesses during processing, for example. Accordingly, gas delivery assemblies for semiconductor processing chambers attempt to deliver stable flows at precise flow rates, flow ratios, and pressures to multiple input ports of the processing chamber.

[0006] Prior art gas delivery assemblies can utilize a flow-splitting method to improve flow ratio accuracy, repeatability, and reproducibility in multi-injection point and / or multi-chamber processing systems. Flow-splitting can be provided by using multiple mass flow controllers (MFCs) that actively attempt to control the relative flow rates of gases dispensed at multiple input port locations. However, as new chamber processing technologies continue to enable smaller critical dimensions for microelectronic devices, a higher degree of flow control accuracy, particularly flow ratio control, is beneficial. Accordingly, methods and assemblies are needed to make gas flow rate control, particularly flow ratio control, more accurate. SUMMARY

[0007] In one or more embodiments, a method of controlling flow of gas to a process chamber is provided. The method includes providing a distribution manifold fluidly coupled to a process chamber, providing one or more mass flow controllers fluidly coupled between the process chamber and the distribution manifold, providing a back pressure controller fluidly coupled to the distribution manifold, controlling flow through each of the one or more mass flow controllers to a dynamically controllable flow setpoint, and controlling back pressure upstream of the back pressure controller to a back pressure setpoint.

[0008] In some embodiments, a gas flow control assembly is provided. The gas flow control assembly includes a controller, a process gas source, a distribution manifold fluidly coupled to the process gas source, a pressure sensor coupled to the distribution manifold and operatively connected to sense back pressure in the distribution manifold, one or more mass flow controllers fluidly and operatively connected to the distribution manifold and to the process chamber to control gas flow between the distribution manifold and the process chamber, and a back pressure controller fluidly and operatively connected to the distribution manifold.

[0009] In further embodiments, a gas flow control assembly is provided. The gas flow control assembly includes a controller, a process gas source, a distribution manifold fluidly coupled to the process gas source, the distribution manifold having at least two outlets, a back pressure sensor operatively connected to the controller and configured to sense gas pressure in the distribution manifold, one or more mass flow controllers each fluidly and operatively connected to an outlet of the distribution manifold and to a zone of the process chamber to control a percentage of gas flow into each zone, and a back pressure controller fluidly connected to the distribution manifold and operatively connected to the controller to control the back pressure controller to a back pressure setpoint in response to output from the back pressure sensor.

[0010] In another embodiment, a method of controlling flow of gas to a process chamber is provided. The method includes providing a distribution manifold fluidly coupled to a process chamber; providing a process gas source fluidly coupled to the distribution manifold, the process gas source including an upstream pressure controller and one or more process gases, the upstream pressure controller operatively coupled to a carrier gas, the flow of the one or more process gases controlled by one or more source mass flow controllers; providing one or more mass flow controllers fluidly coupled between the process chamber and the distribution manifold; controlling the flow of gas through each of the one or more mass flow controllers at a dynamically controllable flow setpoint; and controlling the back pressure of the distribution manifold at a back pressure setpoint by controlling the flow of carrier gas using the upstream pressure controller.

[0011] According to one or more embodiments, a gas flow control assembly is provided. The gas flow control assembly includes a controller, a process gas source including a carrier gas and one or more process gases, a distribution manifold fluidly coupled to the process gas source, a back pressure sensor fluidly connected to the distribution manifold and configured to sense a back pressure in the distribution manifold, a process chamber including a plurality of zones, each of a plurality of mass flow controllers fluidly and operatively connected between the distribution manifold and the process chamber and configured to control a flow of gas into the plurality of zones of the process chamber, and an upstream pressure controller fluidly and operatively connected to the distribution manifold and configured to control a flow of the carrier gas in response to a back pressure setpoint provided by the controller.

[0012] In yet another embodiment, a gas flow control assembly is provided. The gas flow control assembly includes a controller, a process gas source including a carrier gas and one or more process gases configured to mix at a junction, a distribution manifold fluidly coupled to the process gas source downstream of the junction, the distribution manifold having a plurality of outlets, a back pressure sensor operatively connected to the controller and configured to sense a back pressure in the distribution manifold, a process chamber including a plurality of zones, each of one or more mass flow controllers fluidly and operatively connected to an outlet of the distribution manifold and to one of the plurality of zones to control a gas flow ratio into each of the plurality of zones, and an upstream pressure controller fluidly connected to the carrier gas upstream of the junction and operatively connected to the controller to control the back pressure at a back pressure setpoint in response to an output signal from the back pressure sensor.

[0013] Numerous other features are provided in accordance with these and other aspects of the present application. Other features and aspects of embodiments of the present application will become more fully apparent from the following description, the appended claims and the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 A schematic top view of a gas flow control assembly including a mass flow controller and a back pressure controller is depicted in accordance with one or more embodiments.

[0015] Figure 2 A schematic top view of an alternative embodiment of a gas flow control assembly including a mass flow controller and a back pressure controller, wherein the output from the back pressure controller bypasses the processing chamber, is depicted in accordance with one or more embodiments.

[0016] Figure 3 A schematic top view of another embodiment of a gas flow control assembly including multiple mass flow controllers and a back pressure controller is depicted in accordance with one or more embodiments.

[0017] Figure 4 A schematic top view of another alternative embodiment of a gas flow control assembly including multiple mass flow controllers and a back pressure controller, wherein the output from the back pressure controller bypasses the processing chamber, is depicted in accordance with one or more embodiments.

[0018] Figure 5 A schematic top view of another embodiment of a gas flow control assembly including multiple mass flow controllers and a back pressure controller, wherein the output from the carrier gas source is pressure controlled, is depicted in accordance with one or more embodiments.

[0019] Figure 6 A schematic top view of an alternative embodiment of a gas flow control assembly including multiple mass flow controllers and a pressure controller, wherein the output from the carrier gas source is pressure controlled, is depicted in accordance with one or more embodiments.

[0020] Figure 7 A schematic top view of an alternative embodiment of a gas flow control assembly including multiple mass flow controllers and a pressure controller, wherein the output from the carrier gas source is pressure controlled, is depicted in accordance with one or more embodiments.

[0021] Figure 8 A flow diagram of a method of controlling the flow of gas to a processing chamber including back pressure control in accordance with one or more embodiments is depicted.

[0022] Figure 9 A flow diagram of a method of controlling the flow of gas to a processing chamber including pressure control of the output from a carrier gas source in accordance with one or more embodiments is depicted. DETAILED DESCRIPTION

[0023] The present invention provides improved methods and assemblies for controlling gas flow into a process chamber, such as a semiconductor processing chamber or the like. In particular, embodiments of the present invention reduce flow variation, dithering, and / or flow starvation of mass flow controllers (hereinafter MFCs) in an assembly when the MFCs compete for gas flow in order to reach the flow set points required for the control flow ratios of each MFC.

[0024] Prior art gas flow ratio control methods do not attempt to reach a steady state for the flows through the MFCs coupled to the process chamber. Each prior art MFC is set to its flow set point (which is typically a percentage of the total flow) in an attempt to maintain a constant flow at that set point percentage. However, any change in the incoming flow causes a change in back pressure and causes each MFC to adjust its flow demand. If the pressure is low, the only way to achieve more flow through one MFC is to starve another MFC. Thus, transient flows through the MFCs are provided in which all of the MFCs in the assembly are constantly competing with each other to reach their respective flow set points. As a result, unwanted flow variations can occur at the inlet port of each process chamber. This can affect process quality and / or uniformity. For example, in some embodiments, this can result in non-uniform etching or deposition. Embodiments of the present invention can substantially eliminate this competition between the MFCs and provide precise flow set point control and flow ratio control.

[0025] Furthermore, embodiments of the present invention can allow the use of a simple feedback control method to control the percentage set points to the desired flow ratios.

[0026] One or more embodiments of the present invention provide a novel combination of MFCs and back pressure controllers in a flow ratio apparatus to precisely control the individual flow ratios of the MFCs. Example embodiments of gas flow control assemblies and methods are described herein with reference to Figures 1-4 and 8, which include a back pressure controller for controlling the flow of gas to a process chamber.

[0027] Example embodiments of gas flow control assemblies and methods are described herein with reference to Figures 4-7 and 9, which include an upstream pressure controller configured to control the pressure of a carrier gas exiting a process gas source for controlling gas flow and gas flow ratios to a process chamber.

[0028] Reference is now made to Figure 1, illustrating a first example embodiment of a gas flow control assembly 100 according to the present disclosure. The gas flow control assembly 100 includes a controller 102 (e.g., a digital controller having a processor), a process gas source 104, and a flow ratio apparatus 105 fluidly coupled to the process gas source 104. The flow ratio apparatus 105 can include a distribution manifold 106 fluidly coupled to the process gas source 104, which can provide a carrier gas and one or more process gases (e.g., process gas 1 through process gas N) to be used in a process to be performed in a process chamber 110.

[0029] The term "fluidly coupled" as used herein means that components are coupled by piping suitable for carrying a fluid (e.g., a gas) therethrough. The flow ratio apparatus 105 of the gas flow control assembly 100 further includes a back pressure sensor 108 fluidly and operatively connected to the distribution manifold 106 and operatively connected to the controller 102 and configured to sense a gas pressure within the distribution manifold 106 and provide an output signal to the controller to be used for flow ratio control, as will become apparent from the following description.

[0030] The gas flow control assembly 100 further includes a process chamber 110 that receives gas flow from the flow ratio apparatus 105. The flow ratio apparatus 105 includes one or more mass flow controllers (MFCs) 112 (one shown in the illustrated embodiment), each of which is fluidly and operatively connected to the distribution manifold 106 and to the process chamber 110 and operatively connected to the controller 102 to control gas flow to one or more zones (e.g., zone 1, zone 2A, zone 2B) of the process chamber 110. The process chamber 110 can be any chamber in which a process is performed on a substrate 120 (indicated in phantom), such as an etch process chamber, a deposition process chamber (e.g., atomic layer deposition (ALD), physical vapor deposition (PVD), or chemical vapor deposition (CVD) deposition), epitaxial deposition, a clean process chamber, or the like.

[0031] The flow ratio apparatus 105 further includes a back pressure controller 114 fluidly and operatively connected to the distribution manifold 106. In the illustrated embodiment, the back pressure controller 114 is also fluidly coupled to the process chamber 110. In the illustrated embodiment, a single MFC 112 is disposed in a fluid parallel relationship with a single back pressure controller 114. However, later embodiments will include multiple MFCs 112A, 112B in parallel with a single back pressure controller 114. Figure 1

[0032] ​MFC 112 is a device for measuring and controlling the flow of a gas. MFC 112 is designed and calibrated to control a specific type or range of types of gas at a specific range of flow rates. MFC 112 can be given a dynamic adjustable set point from 0% to 100% of its full range, but it typically operates at about 10% to about 90% of its full range, where the best accuracy can be achieved. MFC 112 then controls the flow rate to the individual flow set point. MFCs can be analog or digital. Multi-gas and multi-range MFCs are generally capable of controlling more than one gas, and are therefore preferred in cases where more than one gas recipe is supplied from process gas source 104 to process chamber 110. Standard MFCs can be used, but standard MFCs can be limited to a specific gas recipe, which the standard MFC is calibrated for.

[0033] All MFCs 112 have an inlet port, an outlet port, an internal mass flow sensor, and a proportional control valve, which can be actuated by an actuator, such as an appropriate motor or element that causes automatic movement. MFCs 112 can typically be equipped with a closed loop control system, which controller 102 can give a flow set point control signal to, which is then compared to the value from the internal mass flow sensor and adjusts the proportional valve via actuation to achieve the desired flow rate. The flow set point control signal can typically be specified as a percentage of the full range flow (flow ratio) that it is calibrated for, and can be supplied as a voltage from controller 102 to MFC 112. In some embodiments, the closed loop control system is provided as circuitry within MFC 112, which is operatively connected to controller 102 and receives the flow set point control signal from controller 102. In other embodiments, the closed loop control can be done separately by controller 102. All MFCs described herein are of this structure.

[0034] In the embodiment shown, the gas supply to MFC 112 from distribution manifold 106 is provided at a specified back pressure set by controller 102 at the inlet port of MFC 112. Because BPC 114 ensures that the desired back pressure is achieved in distribution manifold 106, MFC 112 of this embodiment is not starved of gas, and is therefore able to accurately achieve the flow set point and flow ratio.

[0035] In the embodiment shown, each MFC 112 can be any suitable type of mass flow controller with a normally closed valve, such as, for example, a mass flow controller available from HORIBA, Kyoto, Japan. The MFC 112 can, for example, be capable of handling flow rates between about 10 sccm and 200 slm. For all embodiments described herein, the backpressure controller 114 can be any suitable pressure controller or pressure regulator for closed-loop control of backpressure, such as a Digital Auto Pressure Regulator available from HORIBA, Kyoto, Japan, or an integrated pressure controller for closed-loop pressure control available from MKS, Andover, Mass. The backpressure controller 114 includes an internal control valve that can be actuated by an internal actuator and can include internal digital electronics to provide a feedback control loop and an actuation signal to control the backpressure to a desired pressure set point transmitted to the backpressure controller by the controller 102. In some embodiments, backpressure sensor 108 may be located within backpressure controller 114 to sense backpressure in distribution manifold 106. Closed loop control may be selectively performed by controller 102 alone or by any combination of controller 102 and internal digital electronics.

[0036] like Figure 1 As shown, the process gas source 104 is fluidly and operatively connected to the distribution manifold 106 of the flow ratio device 105 via a feed line 116 and feeds the process gas to the distribution manifold 106 of the flow ratio device 105 via the feed line 116. The feed line 116 can be a pipe or a collection of pipes. The process gas source 104 can include a plurality of different gases, which can be mixed as needed for the various processes performed in the process chamber 110. For example, in one embodiment, a carrier gas 118 can be provided, which is mixed with one or more process gases (process gases 1-N). The carrier gas 118 can be any suitable gas for carrying the process gas, such as nitrogen, hydrogen, an inert gas (such as helium, argon), or a combination thereof.

[0037] The process gas source 104 can also include one or more process gases, such as a plurality of process gases (e.g., process gas 1, process gas 2, process gas 3, and up to process gas N). The process gases 1-N can be used to perform one or more processes on a substrate 120 housed in the process chamber 110. The substrate 120 can be an electronic device precursor article, such as a semiconductor wafer, a crystalline silicon wafer, a silicon wafer, a doped silicon wafer, a doped or undoped polysilicon wafer, a masked silicon wafer, a patterned or unpatterned silicon wafer, or a silicon-containing disk or sheet, other silicon-containing article, or the like. The substrate 120 can be positioned and supported for processing on a suitable support (e.g., such as a pedestal or lift pins) within the process chamber 110. The process chamber 110 can be a semiconductor processing chamber suitable for processing the substrate 120 therein. The process gases 1-N can be a reducing agent gas, such as oxygen (O2), carbon dioxide (CO2), nitrogen oxide (NO), dinitrogen oxide (N2O), nitrogen dioxide (NO2), methane (CH4), carbon tetrafluoride (CF4), tetrafluoromethane (CHF4), trifluoromethane (CHF3), difluoromethane (CH2F2), chlorine trifluoride (CIF3), sulfur hexafluoride (SF6), hexafluorobutadiene (C4F6), hexafluoroethane (C2F6), octafluorocyclobutane (C4F8), octafluorocyclopentene (C5F8), octafluoropropane (C3F8), propylene (C3H6), nitrogen trifluoride (NF3), dichlorosilane (H2SiCl2), phosphine (PH3), silane (SiH4), trichlorosilane (TCS), trimethylsilane (3MS), boron trichloride (BC13), chlorine (CI2), ammonia (NH3), germane (GeH4), tungsten hexafluoride (WF6), xenon (Xe), or the like. Other suitable process gases can be used.

[0038] More particularly, the process gas source 104 can include a plurality of source MFCs, such as source MFC 1241 through source MFC 124 N where N can be equal to the number of process gases present. For example, there can be three or more source MFCs, such as source MFCs 1241, 1242, 1243, and 124 N Other numbers of process gases and source MFCs can be used. The process gas source 104 can further include control valves 125, 126, which are operatively connected to the controller 102 to control the relative flow and ratio of the carrier gas 118 to the process gases (process gas 1, process gas 2, process gas 3,..., process gas N), thus not only controlling the ratio of the carrier gas 118 to the process gases, but also controlling the total gas flow provided to the distribution manifold 106 of the flow ratio device 105. The controller 102 determines and sets the source MFCs 1241-124 NThe process gas flow set points of each and the flow through the control valves 125 and 126.

[0039] The process gas source 104 is operatively coupled to and provided in fluid communication with a flow ratio device 105, which includes a distribution manifold 106, one or more MFCs 112, a back pressure controller 114, and a back pressure sensor 108. Depending on the process recipe to be supplied during semiconductor substrate processing, the flow ratios of the source gas from the source MFCs 1241-124 may be varied. N Quantities of different process gases supplied to flow ratio device 105. In addition, the relative proportions of the total flow to the various zones (eg, zone 1, zone 2A, and zone 2B) of process chamber 110 may also be varied.

[0040] Thus, the processing chamber 110 may be adapted to receive gases in more than one zone within the processing chamber 110, and thus an output manifold 130 may be provided that is coupled to one or more MFCs 112 and BPCs 114 and may include a plurality of manifold sections 130A-130C that feed into the processing chamber 110 at the plurality of zones. The function of the flow ratio device 105 allows the flow of gases through the one or more mass flow controllers 112 and the backpressure controller 114 to enter one or more zones (e.g., zone 1, zone 2A, zone 2B) of the processing chamber 110. Different flows may be provided to two or more zones.

[0041] like Figure 1 As shown, the flow ratio device 105 can be coupled to an output manifold 130, which can be coupled to multiple zones (e.g., zone 1, zone 2A, and zone 2B) of the process chamber 110 at respective outputs of output manifold segments 130A-130C. For example, flow from the MFC 112 can be routed to an inner zone (e.g., zone 1) via output manifold segment 130A, and airflow from the backpressure controller 114 can be provided to one or more outer zones (e.g., zones 2A and 2B) via output manifold segments 130B and 130C. For example, the output manifold segments 130A, 130B, and 130C can include multiple output channels, each of which can be distributed within each respective zone. In some embodiments, the zones (e.g., zone 1, zone 2A, and zone 2B) can be arranged horizontally across the process chamber 110, as shown. In other embodiments, the multiple zones can be arranged as one or more concentric rings around a circular center zone. Other zone arrangements may be used to provide zoned gas flow control. In other embodiments, some outputs may be located at the top of the processing chamber 110, while other outputs may be located on the side or even the bottom of the processing chamber 110, or any combination thereof. Multiple output ports may be provided to each zone (e.g., Zone 1, Zone 2A, and Zone 2B).

[0042] In the illustrated embodiment, the MFC 112 is controlled to a flow set point by way of interaction and communication with the controller 102. For example, the flow set point of the MFC 112 can be set such that a desired fraction (e.g., 60%) of the total flow provided from the gas source 104 to the feed line 116 is provided to zone 1. The remaining gas flow to zone 2A and zone 2B can then be set based on the desired designed back pressure in the distribution manifold 106. In particular, the back pressure controller 114 is configured and operable to control the back pressure to a predetermined back pressure set point (Pb). For example, the designed back pressure set point (Pb) can be between about 50 Torr and about 1600 Torr, and for example, about 350 Torr in some embodiments. Other back pressure set points (Pb) can be used. In some embodiments, the back pressure set point (Pb) can be set based on the pressure of the gas source minus the pressure of the processing chamber 110.

[0043] In other embodiments, more than one MFC 112 can be used. For example, a first MFC 112 coupled to the distribution manifold 106 can control a first flow ratio to a first zone (e.g., zone 1), a second MFC (not shown) coupled to the distribution manifold 106 can control a second flow ratio to a second zone (e.g., zone 2A), and the BPC 114 can control the flow to a third zone (e.g., zone 2B) in response to a desired back pressure set point (Pb). A greater number of MFCs can be used to provide more fine-grained flow ratio control to additional zones of the processing chamber 110. In this way, multiple MFCs do not compete with each other for flow because the flow ratio through each MFC can be controlled to very tight tolerances, such as even + / - 1% or less. Likewise, tight tolerances of about + / - 1% or less can be provided for the flow set point of each MFC 112.

[0044] The controller 102 herein can include suitable processors, memory and software, firmware, or a combination of the above, A / D converters, conditioning electronics, and / or drivers to control the flow from the process gas source 104, control each MFC 112 to the desired flow setpoint, and receive a back pressure signal to control the back pressure in the distribution manifold 106 via a control signal to the back pressure controller 114 of the desired back pressure setpoint (Pb). The desired back pressure setpoint (Pb) can be responsive to a pressure signal received by the controller 102 through the back pressure sensor 108. For example, in the illustrated embodiment, the flow setpoint can be set between about 0.5% and 99.5% of the total full range flow. In some embodiments, the flow setpoint should be between about 5% and about 95%. In some embodiments, the sensor 108 can be provided as an integral part of the BPC 114, and the BPC 114 can then control the back pressure to the back pressure setpoint (Pb) supplied to the internal closed loop electronics by the controller 102 in communication with the internal closed loop electronics. In other embodiments, closed loop control can be achieved by any suitable combination of the internal closed loop electronics and the controller 102.

[0045] Figure 2 Details of an alternative embodiment of a gas flow control assembly 200 are illustrated. The gas flow control assembly 200 includes a controller 102, a process gas source 104, and a process chamber 110, which are the same as previously described. Other items not specifically described are the same as in the embodiment of Figure 1 However, in this embodiment, the flow ratio device 205 includes a first MFC1 112A operatively and fluidly coupled to a first zone (e.g., zone 1 - the center zone) of the process chamber 110 and a second MFC2 112B operatively and fluidly coupled to at least one other zone (e.g., coupled to zone 2A and zone 2B, as shown) of the process chamber 110. The BPC 114 in this embodiment of the flow ratio device 205 controls the back pressure to the back pressure setpoint (Pb) by the controller 102 monitoring the back pressure of the distribution manifold 206 via the back pressure sensor 108 and making appropriate adjustments to the internal control valves in the BPC 114.

[0046] As noted above, in some embodiments, the sensor 108 can be integrated as one with the BPC 114, and closed loop control can be achieved by the internal closed loop electronics of the BPC 114 to control the back pressure to the back pressure setpoint (Pb) supplied to the internal closed loop electronics by the controller 102, or in some embodiments, by a combination of the internal closed loop electronics of the BPC 114 and processing performed by the controller 102.

[0047] InFigure 2 In embodiments, the outflow of the BPC 114 is not fed to the process chamber 110, but bypasses the process chamber 110 and fluidly couples to and flows to a vent or scrubber 232. The exhaust gas from the exhaust line 234 can be sent to a vent, i.e., if the gas does not need any treatment, it is vented to the atmosphere, or if the gas is toxic or flammable and needs to be treated, the gas is instead sent to an abatement system, such as a scrubber. Any suitable abatement system can be used for treatment, such as described in U.S. Publication Nos. US20100192773; US20100119984; US20090175771; and US20090056544, and U.S. Patent Nos. 8,668,868; 8,003,067; and 6,277,347. Other suitable abatement systems can be used.

[0048] Each of the MFCs 112A, 112B can have a flow set point set between about 0.5% and 100% of the total gas flow. In one embodiment, the first MFC 112A can be set to a flow set point of about 85% of the total flow, the second MFC 112B can be set to a flow set point of about 10% of the total flow, and the back pressure set point (Pb) can be set to about 800 Torr via operation of the BPC 114, such that less than about 5% of the total flow is exhausted in the exhaust line 234. The total flow can be set slightly higher, taking into account gas loss to the vent or scrubber 232. Because a constant back pressure value set by (Pb) is provided in the distribution manifold 206, the first and second MFCs 112A, 112B can be precisely controlled and precisely maintained at their selected flow set points, so that precise flow ratio control to the multiple zones (e.g., zone 1, zone 2A, zone 2B) of the process chamber 110 can be achieved. Each mass flow controller (e.g., MFC 112A, MFC 112B) can be configured and operatively connected in parallel to the process gas source 104, so as to provide high gas flow from the process gas source 104 in some embodiments at flow rates higher than about 90 slm, higher than 95 slm, or even higher than 100 slm.

[0049] Figure 3 and 4Additional embodiments representing gas flow control assemblies 300, 400 are shown, where the flow ratio device 305 includes multiple MFCs (e.g., MFC1, MFC2, MFC3, MFC4,..., MFCN). As previously described, these embodiments include a process chamber 310, 410 and a distribution manifold 306, the process chamber 310, 410 being configured to receive and process a substrate 120. In this embodiment, multiple MFCs 112A-112N can be fluidly coupled between the process chamber 310, 410 and the distribution manifold 306. As previously described, a back pressure controller 114 is fluidly coupled to the distribution manifold 306. However, in embodiments of Figure 3 the flow through the BPC 114 is directed to the process chamber 310, while in embodiments of Figure 4 the flow through the BPC 114 bypasses the process chamber 410 entirely and is instead exhausted to a vent or scrubber 232.

[0050] The flow ratio device 305 in each embodiment includes multiple MFCs 112A-112N, a BPC 114, a distribution manifold 306, and a back pressure sensor 108. As previously described, in some embodiments, the back pressure sensor 108 can be integrated with the BPC 114. In each embodiment, the controller 102 is configured to control the flow through each of the one or more MFCs 112A-112N to a particular dynamically controllable flow set point, i.e., the dynamically controllable flow set point can be changed as the process recipe changes. The flow ratio set point can be set for each MFC 112A-112N-1 based on a user specified setting. The setting for MFCN 112N can be based on the total mass flow from the process gas source minus a percentage of each of the other MFCs 1 through MFCN-1. Likewise, in each embodiment, the back pressure of the distribution manifold 306 can be controlled by the controller 102 to a back pressure set point (Pb) that has been set by the user. The control can be responsive to a feedback signal from the back pressure sensor 108, so the BPC 114 receives the remainder of the total flow. In some embodiments, the back pressure set point (Pb) can be based on the pressure upstream of the process gas source 304 minus the pressure at the process chamber 310, 410. In each embodiment, the total mass flow provided to the distribution manifold 306 in the feed line 316 is the sum of the set mass flow from each MFC 1-MFCN of the carrier gas and process gases 1-N in response to a signal from the controller 102. The process gas source 304 can provide the carrier gas 118 and process gases (e.g., process gas 1, process gas 2, process gas 3,..., process gas N) through the control of a source MFC 1261-126 N The control of the source MFC 1261-126

[0051] As should be appreciated, in each of the above embodiments, the adjustment of the percentage of the flow ratio to each input port of the process chamber 110, 310, 410 can be a dynamic adjustment. Since the MFCs 112 and 112A-112N are no longer competing with each other for flow when the BPC 114 is provided in fluidic parallel with the MFCs 112 and 112A-112N, the transient time (i.e., the adjustment time for the gas flow control assembly 100, 200, 300, 400 to reach a steady state condition) is relatively shortened when the individual flow ratios are changed.

[0052] Thus, in the embodiment of Figure 3 it should be apparent that the plurality of mass flow controllers 112A-112N supply gas from the process gas source 104 to a plurality of zones (e.g., zones Z1-Z4) of the process chamber 310, and the back pressure controller 114 supplies gas to another zone (e.g., Z5) of the process chamber 410.

[0053] In the embodiment of Figure 4 the flow through the MFCs 1-N 112A-112N is provided to a plurality of zones (e.g., zones Z1-Z4), and the remaining flow is provided to the back pressure controller 114 and directly exhausted to one of a vent or scrubber 232, the back pressure controller 114 is completely bypassed around the process chamber 410. The back pressure set point (Pb) of the back pressure controller 114 can be set as described above.

[0054] Figure 5 Another embodiment of a gas flow control assembly 500 is illustrated, which includes a process gas source 504 and a flow ratio controller 505, where the flow ratio controller 505 is similar to the flow ratio controller 305 described above. Figure 2embodiments, the BPC 114 has been replaced with an upstream pressure controller 514. The upstream pressure controller 514 can be used to control the pressure of the carrier gas 118 supplied to the feed line 116, and thus can be used to remotely control the pressure provided in the manifold 506. The upstream pressure controller can include a valve and internal electronics, and optionally contain an internal pressure sensor. As previously described, in some embodiments, the back pressure sensor 108 can be integrated with the upstream pressure controller 514, and the controller 102 provides the pressure set point. In the illustrated embodiment, the upstream pressure controller 514 can be located upstream of the junction 536, where the carrier gas 118 and one or more process gases 1-N are mixed together. The distribution manifold 506 is fluidly coupled to the process gas source 504 downstream of the junction 536. In this embodiment, the flow ratio controller 505 includes only two or more mass flow controllers (e.g., MFC1, MFC2) to control the flow, but no back pressure controller. Thus, in this embodiment, because 100% of the gas flowing from the process gas source 504 is provided to the process chamber 110, no gas is wasted. This also reduces the need for abatement. The gas flow can be provided to at least as many or more zones (e.g., zone 1, zone 2A, zone 2B) of the process chamber 110 as the number of MFCs (e.g., MFC1, MFC2).

[0055] Figure 6 Another alternative embodiment of a gas flow control assembly 600 is illustrated, including a flow ratio controller 605, where the flow ratio controller 605 is similar to Figure 3 embodiments, the BPC 114 has been replaced with an upstream pressure controller 614. The upstream pressure controller 614 can be used to control the pressure of the carrier gas 118 supplied to the feed line 316, and thus can be used to remotely control the pressure provided in the manifold 606. As previously described, in some embodiments, the back pressure sensor 108 can be integrated with the upstream pressure controller 614. As Figure 5 The upstream pressure controller 614 can be located upstream of the junction 536, where the carrier gas 118 and one or more process gases 1-N are mixed together, as in the embodiment of FIG. 6. In this embodiment, the flow ratio controller 605 includes only a plurality of mass flow controllers (e.g., MFC1, MFC2, MFC3,..., MFCN) to control the flow into the process chamber 610, but no back pressure controller 114. Thus, in this embodiment, because 100% of the gas is provided to the process chamber 410, no gas is wasted, reducing the need for abatement. The gas flow can be provided to at least as many or more zones (e.g., zones Z1-Z4) of the process chamber 410 as the number of MFCs.

[0056] Figure 7Another alternative embodiment of a gas flow control assembly 700 is shown, which includes a process gas source 704 and a flow ratio controller 605, wherein the flow ratio controller 605 is connected to the process gas source 704. Figure 6 In this embodiment, the upstream pressure controller 714 can be used to control the pressure of the carrier gas 118 supplied to the feed line 316, and thus can be used to remotely control the pressure provided in the manifold 606. As previously mentioned, in some embodiments, the back pressure sensor 108 can be integrated with the upstream pressure controller 714. Figure 5 and 6 As shown, the upstream pressure controller 714 can be located upstream of the junction 536 where the carrier gas 118 and one or more process gases 1-N are mixed together. In this embodiment, the pressure controller 714 can be arranged in a fluidic parallel relationship with the carrier gas MFCC 726. Therefore, also in this embodiment, because 100% of the gas is provided to the processing chamber 410, no gas is wasted, thereby reducing the need for abatement. Only a portion of the carrier gas flows through the upstream pressure controller 714. Therefore, the carrier gas MFCC 726 can be set to a desired flow set point, and the upstream pressure controller 714 can be adjusted to control the back pressure of the distribution manifold 606 to a desired back pressure set point (Pb). It should be understood that the arrangement of the pressure controller 714 arranged in a fluidic parallel relationship with the carrier gas MFCC 726 can be applied to Figure 5 , thereby replacing the pressure controller 514, with everything else remaining the same.

[0057] Figure 8 A flow chart is shown illustrating an example method for controlling the flow of a gas to a process chamber (e.g., process chambers 110, 310, 410) according to one or more embodiments of the present invention. Method 800 includes providing a process chamber (e.g., process chambers 110, 310, 410) and a distribution manifold (e.g., distribution manifolds 106, 206, or 306) at 802, providing one or more mass flow controllers (e.g., MFCs 112, 112A and 112B, or 112A-112N) fluidly coupled between the process chamber (e.g., process chambers 110, 310, 410) and the distribution manifold (e.g., distribution manifolds 106, 206, 306) at 804, and providing a backpressure controller (e.g., backpressure controller 114) fluidly coupled to the distribution manifold (e.g., distribution manifolds 106, 306) at 806.

[0058] The method 800 further includes controlling, in 808, the flow through each of the one or more mass flow controllers (e.g., MFCs 112, 112A and 112B, or 112A-112N) to a dynamically controllable flow ratio setpoint, and controlling, in 810, the back pressure upstream of the back pressure controller (e.g., back pressure controller 114) to a back pressure setpoint (Pb).

[0059] Note that although the example method 800 described above is described as a sequence of discrete steps, embodiments of the application are not limited to this. The steps described are merely for the sake of illustration so as to facilitate an understanding of one or more embodiments of the application. Any number of additional or intermediate steps can be included, several steps can be omitted or combined, and any portion of any step can be split into sub-steps. Further, the particular order of steps presented is merely for the sake of illustration, and any suitable order of steps (including simultaneous performance of any steps or any combination or sub-combination thereof) can be employed.

[0060] The dynamically controllable flow setpoint for each of the one or more mass flow controllers (e.g., MFCs 112, 112A and 112B, or 112A-112N) in 808 can be set to any percentage of the total flow rate within an allowed range. In some embodiments, the nominal flow rate for the one or more mass flow controllers (e.g., MFCs 112, 112A and 112B, or 112A-112N) can be controlled to + / - 1%, thus very precise flow ratio control between the individual MFCs is possible. Thus, it should be appreciated that precise splitting of flow for 2 or more channels can be achieved. Further, because the MFCs are no longer competing with each other, flow imbalance can be reduced, and changes in the individual flow ratios for the mass flow controllers (e.g., MFCs 112, 112A and 112B, or 112A-112N) can achieve an adjustment time of less than about 1 second. Further, back pressure control can be performed using simple control algorithms, such as simple error feedback control, proportional control, and the like. It is apparent that more complex feed forward or predictive control can be used, but even with simple feedback control methods adequate response times can be achieved.

[0061] Figure 9A flow diagram illustrating another example method of controlling flow of gas to a process chamber (e.g., process chamber 110, 410) in accordance with one or more embodiments of the present disclosure is depicted. The method 900 includes, at 902, providing a distribution manifold (e.g., distribution manifold 506, 606) fluidly coupled to a process chamber (e.g., process chamber 110, 410). The method 900 further includes, at 904, providing a process gas source (e.g., process gas source 504, 604, 704) fluidly coupled to the distribution manifold, the process gas source including an upstream pressure controller (e.g., upstream pressure controller 514, 614, 714) and one or more process gases (e.g., process gas 1, process gas 2, process gas 3,..., process gas N), the upstream pressure controller operatively coupled to a carrier gas (e.g., carrier gas 118), the flow of the one or more process gases controlled by one or more source mass flow controllers (e.g., source mass flow controllers 1241, 1242, 1243,..., 124N). N ) controlled by one or more source mass flow controllers (e.g., source mass flow controllers 1241, 1242, 1243,..., 124

[0062] The method 900 further includes, at 906, providing one or more mass flow controllers (e.g., MFC1 112A and MFC2 112B, or MFC1 112A to MFCN 112N) fluidly coupled between the process chamber and the distribution manifold.

[0063] In operation, the method 900 includes, at 908, controlling the flow of gas through each of the one or more mass flow controllers (e.g., MFC1 112A and MFC2 112B, or MFC1 112A to MFCN 112N) at a dynamically controllable flow setpoint, and at 910, controlling the back pressure of the distribution manifold at a back pressure setpoint (e.g., back pressure setpoint Pb) by controlling the flow of the carrier gas using the upstream pressure controller (e.g., upstream pressure controller 514, 614, 714).

[0064] While certain carrier gases and process gases and certain pressure ranges and flow rates are described herein, it should be understood that embodiments of the present disclosure can equally use other gases, other pressure ranges, and other gas flow rates.

[0065] Thus, while the present disclosure has been disclosed with reference to example embodiments, it is to be understood that other embodiments can fall within the scope of the present disclosure as defined by the following claims.

Claims

1. A method of controlling the flow of a gas into a processing chamber, the processing chamber comprising a plurality of zones, the method comprising: controlling a flow of a gas through each of a plurality of mass flow controllers fluidly coupled between the processing chamber and a distribution manifold, wherein a first mass flow controller of the plurality of mass flow controllers is configured to control a flow of a first gas into a first subset of the plurality of zones, the first gas flow being controlled at a first dynamically controllable flow set point, and a second mass flow controller of the plurality of mass flow controllers is configured to control a flow of a second gas into a second subset of the plurality of zones, the second gas flow being controlled at a second dynamically controllable flow set point; controlling backpressure upstream of a backpressure controller fluidly coupled to the distribution manifold to a determined backpressure set point; and A flow of a third gas into a third subset of the plurality of zones of the processing chamber through the backpressure controller is controlled, the third subset of zones not including any zones of the first subset of zones or the second subset of zones. 2 . The method of claim 1 , wherein the backpressure controller controls backpressure in the distribution manifold.

3. The method of claim 1, wherein the backpressure controller is fluidly coupled to at least one of a vent or a scrubber fluidly coupled to the process chamber.

4. The method of claim 3, further comprising: A flow provided to the backpressure controller is exhausted to at least one of the vent or the scrubber.

5. The method of claim 1, wherein the processing chamber is a semiconductor processing chamber.

6. The method of claim 1, wherein the first dynamically controllable flow set point and the second dynamically controllable flow set point are set to a nominal flow rate + / - 1%.

7. The method of claim 1, wherein the backpressure controller controls the backpressure to a predetermined backpressure set point.

8. A method of controlling the flow of a gas mixture into a processing chamber, the method comprising: providing a carrier gas and one or more process gases from a process gas source to a distribution manifold, the distribution manifold being fluidly coupled to the process gas source; sensing back pressure in the distribution manifold via a back pressure sensor connected to a first controller and fluidly coupled to the distribution manifold; providing, by the backpressure sensor, a signal to the first controller based at least in part on the backpressure; determining, by the first controller, a backpressure set point based at least in part on the signal; controlling the flow of the gas mixture comprising the carrier gas and the one or more process gases into one or more zones of the processing chamber via one or more mass flow controllers, wherein the one or more mass flow controllers are fluidly and operatively connected between the distribution manifold and the processing chamber; and The flow of the carrier gas is controlled based on the backpressure set point by an upstream pressure controller fluidly and operatively connected to the distribution manifold.

9. The method of claim 8, further comprising: A flow set point through each of the one or more mass flow controllers is set by the first controller, wherein the first controller is a digital controller including a processor.

10. The method of claim 8, further comprising: The gas mixture is flowed through the one or more mass flow controllers at a flow rate greater than 90 slm.

11. The method of claim 8, further comprising: A flow rate of the carrier gas to be mixed with the one or more process gases is controlled by the upstream pressure controller in response to the backpressure set point.

12. The method of claim 8, wherein the processing chamber comprises a plurality of zones, wherein the one or more mass flow controllers comprises a plurality of mass flow controllers, and wherein each mass flow controller of the plurality of mass flow controllers is configured to control the flow of the gas mixture into a corresponding zone of the plurality of zones.

13. The method of claim 8, further comprising: The flow rate of the carrier gas is controlled by an additional mass flow controller disposed in fluid parallel relationship with the upstream pressure controller.

14. The method of claim 8, wherein the process gas source comprises one or more additional mass flow controllers, and wherein each of the one or more additional mass flow controllers is associated with one of the one or more process gases, the method further comprising: A set point for each of the one or more additional mass flow controllers is controlled by the first controller to control a proportion of the one or more process gases in the gas mixture.

15. The method of claim 8, further comprising: The gas mixture including the carrier gas and the one or more process gases is flowed into the one or more zones of the processing chamber.

16. The method of claim 8, further comprising: The flow of the carrier gas to the junction where it mixes with the one or more process gases is controlled by the upstream pressure controller.

17. A method of controlling the flow of a gas mixture into a processing chamber, the method comprising: providing, by a main controller, a carrier gas to a distribution manifold via a carrier gas source and a process gas to the distribution manifold via a process gas source, the distribution manifold being operatively coupled to a processing chamber, wherein the carrier gas source is fluidly coupled to a pressure controller, and wherein the process gas has a process gas flow rate controlled by a first mass flow controller, the pressure controller and the first mass flow controller being operatively connected to the main controller; controlling, by the primary controller, a flow of a gas mixture comprising the carrier gas and the process gas through a second mass flow controller to a dynamically controllable flow set point, wherein the second mass flow controller is fluidly coupled between the processing chamber and the distribution manifold and is operatively connected to the primary controller; receiving, by the master controller, an indication of back pressure of the distribution manifold from a back pressure sensor operatively connected to the master controller; and The back pressure of the distribution manifold is controlled at a back pressure set point by controlling the carrier gas flow by the pressure controller in combination with the indication received from the back pressure sensor.

18. The method of claim 17, further comprising: The gas mixture is flowed through the second mass flow controller and into a zone of the processing chamber.

19. The method of claim 17, further comprising: The flow of the carrier gas to the junction is controlled by the pressure controller, and the carrier gas and the process gas are mixed at the junction to form the gas mixture.

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