Rapid gas exchange devices, systems, and methods

Abstract

A gas distribution apparatus is provided having a first reservoir having a first upstream end and a first downstream end, and a second reservoir having a second upstream end and a second downstream end. A reservoir switching valve is in fluid communication with the first downstream end of the first reservoir and the second downstream end of the second reservoir. The reservoir switching valve is operable to selectively couple the first reservoir to an outlet of the reservoir switching valve when in a first state and to selectively couple the second reservoir to the outlet of the reservoir switching valve when in a second state. A plurality of proportional flow control valves are provided having inlets coupled in parallel to the outlets of the reservoir switching valve. The plurality of proportional flow control valves have outlets configured to provide gas to a processing chamber.

Description

[Technical Field]

[0001] FIELD OF THE DISCLOSURE

[0001] Embodiments of the present disclosure generally relate to substrate processing systems. More particularly, embodiments of the present disclosure relate to methods and apparatus for providing process gases to a substrate processing system. [Background technology]

[0002]

[0002] The formation of semiconductor devices is generally performed in a substrate processing platform that includes multiple chambers. In some cases, a multi-chamber processing platform or cluster tool is used to perform two or more processes on a single substrate, sequentially, in a controlled environment.

[0003] During semiconductor device manufacturing, a steady flow of process gas into a processing chamber is desired to provide process uniformity and minimize processing defects. Typically, the flow rate of a process gas increases over time from zero to a steady state as gas delivery valves open. In some processes, the duration of the gas flow to reach a steady state can be a significant portion of the overall gas flow time. In such processes, a relatively long settling time can lead to undesirable process results. To reduce, and in some cases eliminate, settling time, some gas delivery systems maintain a steady-state process flow by diverting the full flow into the chamber foreline when flow into the chamber is not required. When needed, the full flow can be quickly switched from the foreline into the processing chamber with little or no settling time, resulting in improved process uniformity and processing results. Splitting the process gas flow between the foreline and the processing chamber has proven to be an effective technique for achieving desired process results, but it utilizes a large amount of process gas. Furthermore, the delivery hardware for providing precursor flows is expensive and often requires dedicated gas sticks for delivery of process gases to different regions of the processing chamber, such as the regions inside and outside the showerhead, which only has the added negative effect of increasing gas usage.

[0004]

[0004] Therefore, there is a need for providing process gas to a processing chamber using optimized amounts of gas without using multiple dedicated gas sticks. Summary of the Invention

[0005] In some embodiments, a gas distribution apparatus is provided having a first reservoir having a first upstream end and a first downstream end, and a second reservoir having a second upstream end and a second downstream end. A reservoir switching valve is in fluid communication with the first downstream end of the first reservoir and the second downstream end of the second reservoir. The reservoir switching valve is operable to selectively couple the first reservoir to an outlet of the reservoir switching valve when in a first state and to selectively couple the second reservoir to the outlet of the reservoir switching valve when in a second state. A plurality of proportional flow control valves are provided, each having an inlet coupled in parallel to the outlet of the reservoir switching valve. The plurality of proportional flow control valves have an outlet configured to provide gas to a processing chamber.

[0006] In some embodiments, a semiconductor processing system is provided having a process chamber with a process space for processing a substrate. The process chamber has a first process gas inlet and a second process gas inlet. The system includes a gas distribution assembly having a first reservoir having a first upstream end and a first downstream end, and a second reservoir having a second upstream end and a second downstream end. A reservoir switching valve is in fluid communication with the first downstream end of the first reservoir and the second downstream end of the second reservoir. The reservoir switching valve is operable to selectively couple the first reservoir to an outlet of the reservoir switching valve when in a first state and to selectively couple the second reservoir to the outlet of the reservoir switching valve when in a second state. The first and second proportional flow control valves have inlets coupled in parallel to the outlets of the reservoir switching valve, the first proportional flow control valve having an outlet coupled to a first inlet of the processing chamber, and the second proportional flow control valve having an outlet coupled to a second inlet of the processing chamber.

[0007] In some embodiments, a method for supplying gas to a process space of a process chamber is provided. The method includes supplying a first process gas from a first reservoir to the process space through a reservoir switching valve in a first state. Supplying the first process gas to the process space includes maintaining a first gas pressure range in the first reservoir and controlling a flow of the first process gas from the first reservoir to one or more regions of the process space using a plurality of proportional flow control valves disposed upstream of the process space. The reservoir switching valve is switched to a second state. A second process gas is supplied to the process space through the reservoir switching valve in the second state. The second process gas is provided from a second reservoir. Supplying the second process gas includes maintaining a second gas pressure range in the second reservoir and controlling a flow of the second process gas from the second reservoir to one or more regions of the process space using a plurality of proportional flow control valves disposed upstream of the process space.

[0008]

[0008] So that the features of the present disclosure described above may be understood in detail, a more particular description of the present disclosure briefly summarized above may be had by reference to embodiments, some of which are illustrated in the accompanying drawings. It should be noted, however, that the accompanying drawings depict only exemplary embodiments and therefore should not be considered to limit the scope of the present disclosure, as other equally effective embodiments may also be acceptable. [Brief explanation of the drawings]

[0009] [Figure 1]

[0009] A schematic diagram of a gas distribution system according to an embodiment of the present disclosure is shown. [Figure 2]

[0010] 1 shows a schematic diagram of a gas distribution system used to distribute gas to multiple regions of a single process chamber. [Figure 3]

[0011] 1 shows a flow diagram of a method according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0010]

[0012] For ease of understanding, wherever possible, identical reference numerals have been used to designate identical elements common to the figures. It is contemplated that elements and features of one embodiment may be beneficially incorporated in multiple other embodiments without further description.

[0011]

[0013] Embodiments of the present disclosure provide a substrate processing system with a stable process gas supply that improves throughput and increases processing efficiency. One or more embodiments of the present disclosure are described with respect to a plasma etch processing chamber. However, the gas distribution system may be utilized in other types of processing chambers, such as chemical vapor deposition chambers, atomic layer deposition chambers, implant chambers, or other processing chambers. In particular, the gas distribution system described herein provides very fast flow stabilization, whereby flows may be turned on or switched between gases with little or no flow rate settling time. This results in a very stable gas supply that promotes process uniformity and defect elimination. Furthermore, very fast flow stabilization also allows for faster cycling between gases, thereby enabling larger process windows and more diverse processes. Furthermore, the gas distribution system does not rely on dumping process gas flow into the foreline to enable fast flow stabilization, as is done in conventional systems, advantageously reducing the amount and cost of process gas required to perform cyclic processes, such as trench etch processes. Additionally, the gas distribution system disclosed herein further reduces expensive process gas supply hardware costs by eliminating the need in conventional processing chambers for dedicated gas sticks to supply process gases to different processing regions of the processing chamber.

[0012]

[0014] FIG. 1 shows a schematic diagram of a gas distribution system 100. The gas distribution system 100 includes a common housing 108 for distributing gas to multiple process regions 101. The process regions 101 may be separate process chambers or separate process regions of a single process chamber. FIG. 2 shows a gas distribution system used to distribute gas to multiple regions of a single process chamber 203 according to one embodiment. While FIG. 1 shows three process regions 101, it is contemplated that more or fewer process regions 101 may be used with the gas distribution system 100 of the present disclosure.

[0013]

[0015] The common housing 108 includes two or more gas reservoirs (e.g., a first gas reservoir 114 and a second gas reservoir 124). In some embodiments, which may be combined with other embodiments described herein, the common housing is temperature controlled or the common housing is not temperature controlled. While the first and second reservoirs 114, 124 are depicted within the common housing 108, the gas distribution system 100 described herein may also include embodiments that do not include a common housing 108. In some embodiments, which may be combined with other embodiments described herein, the first and second reservoirs 114, 124 are disposed proximate to and coupled to the multiple process regions 101. The first gas reservoir 114 includes a first upstream end 113 and a first downstream end 115. The second gas reservoir 124 includes a second upstream end 123 and a second downstream end 125. A pressure gauge (e.g., a first pressure gauge 116 for the first reservoir 114, a second pressure gauge 126 for the second reservoir 124) can be coupled to the corresponding reservoir and measure the pressure of the corresponding reservoir. In some embodiments, which can be combined with other embodiments described herein, each reservoir includes two or more pressure gauges configured to measure pressure at different points between the upstream end (e.g., 113, 123) and downstream end (e.g., 115, 125) of each reservoir.

[0014]

[0016] One or more regulators (e.g., a first regulator 110 for a first reservoir 114) are coupled to a first upstream end 113 of the first reservoir 114, and one or more regulators (e.g., a second regulator 120 for a second reservoir 124) are coupled to a second upstream end 123 of the second reservoir 124. Each regulator (110, 120) may be any suitable gas regulator or any suitable mass flow controller known in the art. Each regulator provides a supply pressure (or input pressure) to each of the first and second reservoirs (114, 124). The regulators may be any mechanically or electrically controlled proportional pressure control component. Each regulator (110, 120) is coupled to a corresponding fill valve. A corresponding fill valve is coupled to the corresponding reservoir (e.g., a first fill valve 112 for the first reservoir 114, a second fill valve 122 for the second reservoir 124). Each fill valve 112, 122 is a valve that is either fully open or fully closed to allow gas to flow therethrough or prevent gas from flowing therethrough. Alternatively, each fill valve 112, 122 is a variable release valve that allows adjustment of the flow profile through the valve. Each fill valve 112, 122 is selected from fast-acting valves, solenoid valves, and piezo valves. The fill valves 112, 122 are fast-acting valves that can transition between positions (e.g., open / closed) within 50 milliseconds, e.g., within 40 milliseconds, or within 30 milliseconds, or within 10 to 20 milliseconds. In some embodiments, which may be combined with other embodiments described herein, the fill valves 112, 122 are gas-pressure-activated, normally closed (NC), fast-acting valves configured to engage when the reservoir is within about 90% of a pressure setpoint and to pulse at intervals of about 100 ms or less until the pressure in the reservoir is within an acceptable range. The first regulator 110 and first fill valve 112 are operable to maintain the pressure in the first reservoir 114 within a substantially constant pressure range, and the second regulator 120 and second fill valve 122 are operable to maintain the pressure in the second reservoir 124 within a substantially constant pressure range.

[0015]

[0017] The regulators 110, 120 and fill valves 112, 122 are coupled to a first gas source 109a and a second gas source 109b via inlet lines. Each process gas from each gas source is used to fill a corresponding reservoir 114, 124 and flow from the corresponding reservoir to a reservoir switching valve 134. The switching valve 134 is one or more valve clusters, such as a three-way valve, configured to switch from a first gas from the first reservoir 114 to a second gas from the second reservoir 124 and release each of the first and second gases downstream. While the switching valve 134 is depicted as a three-way valve in the drawings, other embodiments, such as one or more valve clusters, are contemplated for systems having three or more reservoirs. The reservoir switching valve is in fluid communication with a first downstream end of the first reservoir and a second downstream end of the second reservoir. In operation, when the reservoir switching valve 134 is in a first state, it is operable to selectively couple a first reservoir to the outlet 135 of the reservoir switching valve 134. When the reservoir switching valve 134 is in a second state, it is operable to selectively couple a second reservoir to the outlet 135 of the reservoir switching valve 134.

[0016]

[0018] Conventional gas distribution assemblies do not use switching valves downstream of the distribution lines. Instead, conventional gas distribution assemblies use multiple distribution lines from each gas source, with each distribution line corresponding to a different process station or process region. Conventional distribution assemblies continuously route gases that are diverted to either the foreline 138 or a high-speed pulse delivery valve that pulses the gas into the process space. It has been discovered that incorporating a switching valve 134 that can switch between a first reservoir 114 and a second reservoir 124 can minimize the total number of distribution lines used in a process. Instead, the switching valve 134 alternates between each of the first and second process gases according to a process recipe, routing the gases to multiple proportional flow control valves (140a, 140b, 140c, etc.). The multiple proportional flow control valves have inlets coupled in parallel to the outlets of the reservoir switching valve 134.

[0017]

[0019] A diverter valve 136 is disposed between the switching valve 134 and the proportional flow control valves 140 a, 140 b, and 140 c. The diverter valve 136 is used to purge gas from each of the reservoirs into a foreline 138. The diverter valve 136 is also operable to direct gas flow to each of the plurality of proportional flow control valves (e.g., 140 a, 140 b, and 140 c) to each process region 101. The plurality of proportional flow control valves have inlets coupled in parallel to the outlets of the diverter valve 136.

[0018]

[0020] Each of the proportional flow control valves is coupled to a corresponding process region 101. Each of the plurality of proportional flow control valves (e.g., 140a, 140b, 140c) can divide the gas flow among each of the process regions 101. Each of the plurality of proportional flow control valves (e.g., 140a, 140b, 140c) is an electrically actuated piezoelectric flow control valve (e.g., piezo valve). Each of the plurality of proportional flow control valves is coupled to a heater. Downstream of each proportional flow control valve is a normally open solenoid valve (NO valve), such as gas pressure actuated valves 142a, 142b, 142c. The gas pressure actuated valves are used to regulate the gas flow therethrough and are used in conjunction with pressure gauges 144a, 144b, 144c.

[0019]

[0021] Gas distribution system 100 includes a controller 190. Controller 190 is coupled to and controls the operation of various components of gas distribution system 100. Controller 190 may be a single controller controlling the system or multiple controllers controlling individual portions of the system. In some embodiments, each of the proportional flow control valves is communicatively coupled to controller 190. Controller 190 controls the flow ratio between proportional flow control valves 142a, 142b, 142c.

[0020]

[0022] In some embodiments, which may be combined with other embodiments described herein, controller 190 includes a central processing unit (CPU) 192, memory 194, and support circuits 196. Controller 190 controls gas distribution system 100 either directly or through computers (or controllers) associated with particular process chambers and / or support system components. Controller 190 is one or any form of general-purpose computer processor used in industrial settings to control various chambers and sub-processors. The controller's memory 194 or computer-readable medium is one or more of readily available memory, such as random access memory (RAM), read-only memory (ROM), floppy disk, hard disk, optical storage media (e.g., compact disk or digital video disk), flash drive, or any other form of digital storage, local or remote. Support circuits 196 are coupled to CPU 192 to support the processor in a conventional manner. These circuits include cache, power supplies, clock circuits, input / output circuits and subsystems, etc. One or more processes are stored in memory as software routines that are executed or invoked to control the operation of the system or individual components in the manner described herein. The controller 190 includes one or more configurations, including any commands or functions for controlling flow rates, gas valves, gas sources, or other processes to implement various configurations.

[0021]

[0023] The controller 190 is connected to one or more of the regulators 110, 120, the fill valves 112, 122, the switching valve 134, the diverter valve 136, the proportional flow control valves 140a, 140b, 140c, or the gas pressure actuated valves 142a, 142b, 142c. The controller 190 has one or more configurations. In some embodiments that may be combined with other embodiments described herein, the controller 190 has configurations for opening and closing one or more of the fill valves 112, 122. In some embodiments that may be combined with other embodiments described herein, the controller 190 has configurations for monitoring pressure using one or more of the pressure gauges 116, 126, 144a, 144b, 144c.

[0022]

[0024] While the gas distribution system 100 is suitable for several different processes, one particular application is through-silicon via (TSV) etching, which uses a low-frequency bias and a low-temperature environment to form deep trenches in silicon substrates. One type of etching system is in situ plasma etching, in which trenches are formed by alternating removal and deposition of material on a substrate in a single reactor with removal and deposition plasmas. Another type of etching system is remote plasma etching, in which trenches are formed using a plasma generated in a remote reactor before being introduced to a substrate positioned in a primary reactor (e.g., process chamber 203 shown in FIG. 2). Processing of the substrate involves alternately depositing and etching films on the substrate by sequentially supplying deposition and etching gases. While only two gas sources 109a, 109b are depicted in FIGS. 1 and 2, alternative or additional gas sources are contemplated. In this approach, an etching gas is provided to incrementally etch a trench or other feature into the substrate in a series of pulses, while a deposition gas is provided to coat and protect the sidewalls of the trench or other feature being etched into the substrate between the etching pulses of the etching gas.

[0023]

[0025] 2 illustrates a reactor 200 having a process chamber 203 and a gas distribution system 100 that distributes gas to multiple regions within a process space 202 of the process chamber 203. The process chamber 203 includes a lid 204, a power supply 215 and matching network 217, a bias power supply 220 and matching network 221, an electrostatic chuck 240, and the gas distribution system 100. Proportional flow control valves 140a and 140b of the gas distribution system 100 direct gas to a nozzle assembly 207 coupled to the lid 204 of the process chamber 203. The proportional flow control valve 140a is coupled to an edge nozzle of the nozzle assembly 207 via a first gas inlet 232, which directs gas to an edge region of the process space 202. The proportional flow control valve 140b is coupled to a center nozzle of the nozzle assembly 207 via a second gas inlet 234, which directs gas to a central region of the process space 202. The first gas inlet 232 is positioned outboard of the second gas inlet 234 relative to the vertical centerline of the processing chamber. While the drawings depict the second gas inlet as being centered on the nozzle assembly 207, other locations, such as offset from the center, are contemplated. The radial location of the second gas inlet 234 (e.g., from the centerline of the nozzle assembly 207) may be offset from the radial location of the first gas inlet 232. The proportional flow control valve 140c directs gas to a side nozzle 205 located on a side 206 of the process chamber 203. While three proportional flow control valves are depicted in the drawings, more or fewer proportional flow control valves are contemplated to direct gas to more or fewer regions of the process space 202 for customized adjustment of gas flow.

[0024]

[0026] A power source 215 for generating and sustaining the plasma process is coupled to the process chamber 203 via a generator (not shown), which may take the form of one or more antennas or coils. The power source 215 is operable to generate a radio frequency in the range of about 12 MHz to about 13.5 MHz with pulse delivery capability, a power in the range of about 10 Watts to about 7500 Watts, e.g., about 300 Watts to about 5000 Watts, and further includes a dynamic matching network 217. The power source 215 includes a dual tunable source so that the radio frequency can be changed during an etching cycle. In some embodiments, which may be combined with other embodiments described herein, the power source 215 includes a remote plasma source attachable to the process chamber 203 and capable of generating high levels of plasma dissociation. The process chamber 203 includes in-situ source power, remote plasma source power, or a combination of both. In some embodiments, which may be combined with other embodiments described herein, a plasma is generated with a remote plasma source power and transported to the process chamber 203, and an in situ source power 215 maintains the generated plasma within the process chamber 203. An etch cycle is performed in which the power range of the power source 215 may be increased or decreased during the etch cycle and / or may be pulsed during the etch cycle.

[0025]

[0027] A bias power 220 for biasing the substrate is coupled to the process chamber 203 and the chuck 240. The bias power 220 is operable to generate a radio frequency of about 2 MHz with pulse delivery capability, a low power range of about 10 Watts to about 500 Watts, and further includes a dynamic matching network 221. The bias power 220 can generate a selectable radio frequency range of about 100 kHz to about 13.56 MHz with pulse delivery capability and a power range of about 10 Watts to about 2000 Watts. In some embodiments, which may be combined with other embodiments described herein, an etching cycle includes a deposition operation and an etching operation that are periodically repeated. After an etching operation of the etching cycle, the radio frequency and / or wattage of the bias power 220 may be increased or decreased relative to the previous etching operation of the etching system. In one example, the bias power 220 is greater during the etching operation compared to the deposition operation.

[0026]

[0028] 3 shows a flow diagram of a process 300 for distributing gas according to embodiments of the present disclosure. The method includes, in operation 302, supplying a first process gas from a first reservoir 114 to a process region 101 through a reservoir switching valve in a first state. The first reservoir 114 is filled using a first gas source 109a, and a first gas pressure range is maintained within the first reservoir. A plurality of proportional flow control valves positioned upstream of the process space 202 are used to control the flow of the first process gas from the first reservoir to one or more regions of the process space 202.

[0027]

[0029] It is also contemplated that more than one gas source may be coupled to the first reservoir 114, such as for etching applications. In addition to an etchant, one or more of oxygen, helium, and argon may be provided. In some embodiments, which may be combined with other embodiments described herein, a plasma-sustaining gas, such as argon, is provided. In some embodiments, which may be combined with other embodiments described herein, the gas distribution assembly is configured for silicon etching, and the first process gas is an etching gas, such as a fluoride-containing gas, a sulfur-containing gas, or a gas containing one or both of fluoride and sulfur. The first process gas is supplied to the process space 202 at about 10 sccm to about 3000 sccm for a predetermined duration. In some embodiments, the first process gas is an etching gas and etches a portion of a feature in a substrate disposed in the process space 202.

[0028]

[0030] In conventional processes, high-speed valves are turned on and off at a specific high-speed frequency, such as in a pulsed manner, to control the amount of gas introduced into the process space 202. In the gas distribution system 100 described herein, proportional flow control valves, such as piezo valves, are instead used to control the amount of gas introduced to specific regions of the process space 202. Thus, the gas distribution system of the present disclosure eliminates the use of valves with pulsed supply mechanisms. Each proportional flow control valve is controlled by the controller 190 and uses a process time of about 0.2 seconds or more, such as about 0.3 seconds or more, such as about 1 to 2 seconds, or about 0.3 to about 0.5 seconds, for each process operation.

[0029]

[0031] In operation 304, gas flow is switched from the first reservoir to a second gas from a second reservoir. Specifically, the reservoir switching valve 134 is switched from a first state to a second state, causing the second gas from the second reservoir to flow through an outlet of the reservoir switching valve 134. The switching valve 134 directs the gas to a plurality of proportional flow control valves (140a, 140b, 140c). The plurality of proportional flow control valves are operable to divide the gas flow therethrough in predetermined proportions to the process space 202. A controller 190 is communicatively coupled to the reservoir switching valve 134 and controls the synchronized switching of gas according to a predetermined time sequence of flow controller actuation, such as valve timing control. The controller 190 is communicatively coupled to the plurality of proportional flow control valves 140a, 140b, 140c and gas pressure-actuated valves downstream of the proportional flow control valves for regulating gas flow to each region of the process space 202. Adjusting the gas flow to each region of the process space 202 improves substrate processing and process uniformity. In some embodiments, which may be combined with other embodiments described herein, switching from the first reservoir 114 to the second reservoir 124 occurs substantially simultaneously with opening the first fill valve 112 to refill a partially depleted first reservoir 114. Alternatively, the fill valve 112 opens when the first pressure gauge 116 reaches a lower reservoir pressure limit and / or closes when the first pressure gauge 116 reaches an upper reservoir pressure limit. In some embodiments, which may be combined with other embodiments described herein, the first and second fill valves are piezo valves used to maintain the pressures of the first and second reservoirs within a predetermined range, such as between about 100 Torr and about 1000 Torr, depending on the process. Similar process control can be applied to the second reservoir to switch from the second reservoir to the first reservoir during processing.

[0030]

[0032] In operation 306, a second process gas is supplied to the process region 101 from the second reservoir 124. The second reservoir 124 is filled using a second gas source 109b. A second gas pressure range is maintained in the second reservoir. A plurality of proportional flow control valves disposed upstream of the process space 202 are used to control the flow of the second process gas from the second reservoir to one or more regions of the process space 202. It is also contemplated that two or more gas sources, such as one or more of oxygen, helium, and argon, may be coupled to the second reservoir 124. In some embodiments, which may be combined with other embodiments described herein, the second process gas is a deposition gas, such as a polymer deposition gas (e.g., a fluoride-containing gas, a carbon-containing gas, or a gas having one or more of fluoride and carbon, such as a fluorocarbon). The second process gas is supplied to the process space 202 at about 10 sccm to about 3000 sccm. In some embodiments, which may be combined with other embodiments described herein, the second process gas is used to deposit a protective polymer layer over the etched portion of the substrate feature (e.g., etched in operation 302). Each proportional flow control valve is controlled by the controller 190 to use a process time for each process operation of about 0.2 seconds or more, such as about 0.3 seconds or more, for example, about 1 second to 2 seconds, or about 0.3 seconds to about 0.5 seconds.

[0031]

[0033] After supplying the second gas to the process space 202, in operation 308, the reservoir switching valve is switched from the second state to the first state. Thus, the first process gas from the first reservoir is again in fluid communication with the process space. Operations 302, 304, 306, and 308 are repeated in a predetermined process cycle to form a feature on the substrate by cyclically etching a portion of the feature, depositing a protective polymer layer on the etched portion, then etching another portion of the feature, depositing another polymer layer on the etched portion, etc., until a desired depth is etched to form the feature. The gas distribution system 100 described herein is used to rapidly switch between gases to process a substrate, such as to form a predetermined profile on a silicon substrate disposed in the process space 202.

[0032]

[0034] The fast gas exchange assembly described herein is useful in etching systems employing multi-step processes. The same hardware and operating schemes can also be used in other processes, such as atomic layer deposition processes, that require fast gas switching through the processing chamber 203.

[0033]

[0035] While the forgoing is directed to multiple embodiments of the present disclosure, other and further embodiments of the present disclosure may be devised without departing from the scope of the present disclosure, which is defined by the claims that follow.

Claims

1. a first reservoir having a first upstream end and a first downstream end; a second reservoir having a second upstream end and a second downstream end; a reservoir selector valve in fluid communication with the first downstream end of the first reservoir and the second downstream end of the second reservoir, the reservoir selector valve operable to selectively couple the first reservoir to an outlet of the reservoir selector valve when in a first state and to selectively couple the second reservoir to the outlet of the reservoir selector valve when in a second state; and a gas distribution apparatus comprising a plurality of proportional flow control valves having inlets coupled in parallel to the outlets of the reservoir switching valve, the plurality of proportional flow control valves having outlets configured to provide gas to a processing chamber.

2. The gas distribution apparatus of claim 1 , wherein the first reservoir and the second reservoir are disposed within a common housing.

3. a first fill valve and a first regulator coupled to the first upstream end of the first reservoir and operable to maintain a pressure in the first reservoir within a substantially constant pressure range; and 10. The gas distribution apparatus of claim 1, further comprising a second fill valve and a second regulator coupled to the second upstream end of the second reservoir and operable to maintain a pressure in the second reservoir within a substantially constant pressure range.

4. 4. The gas distribution apparatus of claim 3, wherein the first fill valve and the second fill valve are selected from the group consisting of solenoid valves, piezo valves, fast acting valves, and combinations thereof.

5. The gas distribution apparatus of claim 1 , wherein each of the plurality of proportional flow control valves is a piezoelectric valve.

6. a first pressure gauge coupled to the first reservoir; and The gas distribution apparatus of claim 1 , further comprising a second pressure gauge coupled to the second reservoir.

7. a processing chamber including a process space for processing a substrate, the processing chamber having a first process gas inlet and a second process gas inlet; 1. A semiconductor processing system comprising a gas distribution assembly, the gas distribution assembly comprising: a first reservoir having a first upstream end and a first downstream end; a second reservoir having a second upstream end and a second downstream end; a reservoir selector valve in fluid communication with the first downstream end of the first reservoir and the second downstream end of the second reservoir, the reservoir selector valve operable to selectively couple the first reservoir to an outlet of the reservoir selector valve when in a first state and to selectively couple the second reservoir to the outlet of the reservoir selector valve when in a second state; and 1. A semiconductor processing system comprising: a first proportional flow control valve and a second proportional flow control valve having an inlet coupled in parallel to the outlet of the reservoir switching valve, the first proportional flow control valve having an outlet coupled to the first process gas inlet of the processing chamber, and the second proportional flow control valve having an outlet coupled to the second process gas inlet of the processing chamber.

8. the first reservoir is in fluid communication with a source of etching gas; The semiconductor processing system of claim 7 , wherein the second reservoir is in fluid communication with a deposition gas source.

9. 8. The semiconductor processing system of claim 7, wherein said first process gas inlet is positioned outward of said second process gas inlet relative to a vertical centerline of said processing chamber.

10. a first regulator coupled to the first upstream end of the first reservoir, the first regulator operable to maintain a pressure in the first reservoir within a substantially constant pressure range; and 10. The semiconductor processing system of claim 9, further comprising a second regulator coupled to the second upstream end of the second reservoir, the second regulator operable to maintain a pressure in the second reservoir within a substantially constant pressure range.

11. 10. The semiconductor processing system of claim 9, wherein the first process gas inlet is configured to provide the first process gas into the processing chamber through a ceiling or a showerhead.

12. 10. The semiconductor processing system of claim 9, wherein the first process gas inlet is configured to provide the first process gas into the processing chamber through a sidewall of the processing chamber.

13. 12. The semiconductor processing system of claim 11, wherein said first reservoir and said second reservoir are disposed within a common enclosure, said common enclosure being temperature controlled.

14. 1. A method for supplying gas to a process space of a processing chamber, comprising: supplying a first process gas from a first reservoir to the process space through a reservoir switching valve in a first state; maintaining a first gas pressure range in the first reservoir; and controlling a flow of the first process gas from the first reservoir to one or more regions of the process space using a plurality of proportional flow control valves disposed upstream of the process space. switching the reservoir switching valve to a second state; and supplying a second process gas from a second reservoir to the process space through the reservoir switching valve in the second state; maintaining a second gas pressure range in the second reservoir; and controlling a flow of a second process gas from the second reservoir to one or more regions of the process space using the plurality of proportional flow control valves located upstream of the process space.

15. Controlling the flow of the first process gas from the first reservoir to one or more regions of the process space includes: controlling the flow of the first process gas to a first region of the one or more regions of the process space using a first proportional flow control valve of the plurality of proportional flow control valves; and 15. The method of claim 14, further comprising using a second proportional flow control valve of the plurality of proportional flow control valves to control the flow of the first process gas to a second region of the one or more regions of the process space, the first region being disposed outside the second region relative to a vertical centerline of the processing chamber.

16. Controlling the flow of the first process gas from the first reservoir to one or more regions of the process space includes:

16. The method of claim 15, further comprising flowing the first process gas stream from the reservoir switching valve to the first proportional flow control valve and the second proportional flow control valve in parallel.

17. supplying the first process gas to the process space further comprises flowing an etching gas into the process space; 17. The method of claim 16, wherein supplying the second process gas to the process space further comprises flowing a deposition gas into the process space.

18. 15. The method of claim 14, further comprising switching the reservoir switching valve to cyclically etch features in a substrate disposed in the process space.

19. Switching the reservoir switching valve to cyclically etch the features in the substrate comprises: (a) etching a portion of the feature with an etching gas; (b) depositing a protective layer on the etched portion of the feature with a deposition gas; 20. The method of claim 18, further comprising: (c) periodically repeating (a) and (b) to form the feature.

20. 20. The method of claim 19, further comprising directing gas to a foreline or the process space at a foreline valve downstream of the reservoir switching valve, the foreline valve operable to divert gas to the foreline or the process space.

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