Apparatus and method for providing pulse of precursor

Abstract

To provide an apparatus, system, and method for providing a pulse of a precursor.SOLUTION: For example, an apparatus, system, and method can be used for quickly providing a pulse of a precursor to a reactor to provide a relatively high flow of purge gas in a purge of the reactor.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] FIELD OF THE DISCLOSURE The present disclosure relates generally to gas phase reactor systems and methods of using gas phase reactor systems, and more particularly to an apparatus and method for providing pulses of gas to a reaction chamber of a reactor system. [Background technology]

[0002] Gas-phase reactors, such as chemical vapor deposition (CVD), plasma-enhanced chemical vapor deposition (PECVD), atomic layer deposition (ALD), plasma-enhanced atomic layer deposition (PEALD), and atomic layer etching (ALE), can be used for a variety of applications. For example, such reactors can be used to deposit material on a substrate, etch material from a substrate surface, and / or clean the surface of a substrate. Gas-phase reactors can be used in the manufacture of electronic devices, such as semiconductor devices, flat panel display devices, photovoltaic devices, microelectromechanical systems (MEMS), and the like.

[0003] A typical gas-phase reactor system includes one or more reactors, each reactor including one or more reaction chambers, one or more precursor gas sources and / or reactant gas sources fluidly connected to the one or more reaction chambers, one or more carrier gas sources and / or purge gas sources fluidly connected to the one or more reaction chambers, one or more gas distribution systems for delivering gases (e.g., one or more precursor gases / reactant gases and / or carrier gases or one or more purge gases) to the surface of the substrate in any of the reaction chambers, and at least one exhaust source fluidly connected to the one or more reaction chambers.

[0004] In some processes performed in a reaction chamber, it may be desirable to provide pulses of precursors to the reaction chamber. For example, in cyclic processes such as cyclic CVD, ALD, or ALE processes, precursors and / or reactants can be pulsed into the reaction chamber. A carrier or purge gas is often used to assist in delivering the precursor during the pulse, and the same gas is often used to purge the reaction chamber. Furthermore, during the precursor delivery pulse, the precursor flow rate is set to a predetermined value using a mass flow controller, and a valve between the precursor sources is switched between an open and a closed position. While such configurations can work well in various applications, typical configurations for providing pulses of precursor or reactant to a reaction chamber limit the precursor or reactant concentration that can be delivered to the reaction chamber, are relatively slow, have limited overall purge flow rates, limited purge efficiency, are prone to leaks, and / or are prone to deposition on the backside of the substrate. As a result, improved apparatus and methods for providing pulsed gases to a reaction chamber are desired.

[0005] Any discussion of problems and solutions related to the related art included in this disclosure is solely for the purpose of providing context for the disclosure and should not be construed as an admission that any or all of those discussions were publicly known at the time the invention was made. Summary of the Invention

[0006] Various embodiments of the present disclosure relate to apparatuses and methods, systems including the apparatuses, and methods of using the apparatuses and systems for providing pulses of gas (e.g., precursors or reactants) to a reactor or reaction chamber. The apparatuses, systems, and methods of the present disclosure can be used in connection with a variety of applications, such as, for example, the manufacture of electronic devices. While the manner in which various embodiments of the present disclosure address the problems of conventional methods and systems is discussed in more detail below, in general, various embodiments of the present disclosure provide improved apparatuses, systems, and methods suitable for providing pulses of precursors to a reaction chamber, allowing for higher precursor concentrations, faster pulse on / off rates, higher purge flow rates, rapid flow rate changes, and the ability to change the conductance of a path, such as the path between a precursor source and a reaction chamber. Additionally, the exemplary apparatuses and methods described herein can reduce leakage in any system and / or reduce unwanted backside deposition on a substrate.

[0007] According to exemplary embodiments of the present disclosure, an apparatus for providing a pulse of precursor (e.g., to a reaction chamber) includes a pressure flow controller fluidly connected to a carrier gas source; a precursor source including a precursor container; a precursor container inlet; a precursor container outlet; a carrier gas line having a first branch connected to a flow bypass assembly and a second branch connected to the precursor container inlet; and a precursor line connected to the precursor container outlet. According to aspects of these embodiments, the pressure flow controller is upstream of the precursor source. According to a further aspect, the outlet of the flow bypass assembly is connected to the precursor line downstream of the precursor source. According to yet a further aspect, the flow bypass assembly includes a first flow bypass line and a second flow bypass line, wherein the first flow bypass line has a conductance less than the conductance of the second flow bypass line. The first bypass line and / or the second bypass line may include a corresponding first or second bypass metering valve and a corresponding first or second bypass shutoff valve. According to still additional aspects, the carrier gas line includes a carrier gas metering valve upstream of the precursor source and a carrier shutoff valve upstream of the precursor source. According to further embodiments, the apparatus includes a back suction line. The back suction line may be coupled to the precursor line downstream of the precursor source and upstream of the outlet of the flow bypass assembly. The back suction line may include an orifice. According to still further embodiments, the conductance of the second flow bypass line is at least 5 to 10 times greater than the conductance of the first flow bypass line. The apparatus may further include a reactor inlet line coupled to the outlet of the flow bypass assembly. According to exemplary aspects of these embodiments, the conductance of the reactor inlet line is greater than the conductance of the first flow bypass line. The apparatus may further include an accumulator coupled to the precursor vessel outlet. In such cases, a pressure sensor may be coupled to the interior of the accumulator. The pressure sensor may include a heated manometer.The exemplary apparatus may further comprise a housing around the precursor container and a radiant heat source.

[0008] According to yet further embodiments of the present disclosure, a reactor system is provided. An exemplary reactor system includes a reactor, a vacuum source coupled to the reactor, a controller, and an apparatus for providing a pulse of precursor. The apparatus for providing a pulse of precursor can be as described above or elsewhere in this disclosure.

[0009] According to a further embodiment, a method for pulsing a precursor (e.g., into a reaction chamber) is provided. An exemplary method includes: providing a flow bypass assembly including a first flow bypass line and a second flow bypass line, wherein the conductance of the first flow bypass line is smaller than the conductance of the second flow bypass line; providing a carrier gas to a precursor container containing the precursor and to the flow bypass assembly using a pressure and flow controller; and providing the precursor to the reaction chamber in a pulsed manner by opening a valve between the pressure and flow controller and the precursor container and closing a valve in the second flow bypass line. The exemplary method may further include opening the valve in the second flow bypass line to purge the reaction chamber, and / or other steps described in more detail below.

[0010] These and other embodiments will be readily apparent to those skilled in the art from the following detailed description of any embodiments which refers to the accompanying drawings, although the present invention is not limited to any particular embodiment or embodiments disclosed.

[0011] A more complete understanding of the exemplary embodiments of the present disclosure may be obtained by reference to the detailed description and claims in light of the following illustrative drawings. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 illustrates a reactor system including an apparatus according to at least one embodiment of the present disclosure. [Figure 2] FIG. 1 illustrates a reactor system including an apparatus according to at least one embodiment of the present disclosure. [Figure 3] 1 illustrates a portion of a precursor source assembly in accordance with at least one embodiment of the present disclosure. [Figure 4] 1 illustrates a portion of a precursor source assembly in accordance with at least one embodiment of the present disclosure. [Figure 5] FIG. 10 illustrates a heat pipe and an enclosure around the heat pipe according to a still further embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0013] It will be understood that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of the illustrated embodiments of the present disclosure.

[0014] While certain specific embodiments and examples are disclosed below, those skilled in the art will recognize that the scope of the invention extends beyond the specifically disclosed embodiments and / or uses of the invention, and obvious variations and equivalents thereof. It is therefore not intended that the scope of the disclosed invention should be limited by the specifically disclosed embodiments described below.

[0015] The present disclosure generally relates to apparatus, reactor systems, and methods suitable for providing pulses of gases (e.g., precursors), for example, to a reaction chamber. The apparatus, systems, and methods described herein can be used to process substrates, such as semiconductor wafers, for example, to form electronic devices. By way of example, the apparatus, systems, and methods described herein can be used to provide precursors for depositing layers, etching layers, and / or cleaning substrates or reaction chambers.

[0016] In this disclosure, gas may include materials that are gases at normal temperature and pressure (NTP), vaporized solids, and / or vaporized liquids, and may consist of a single gas or a mixture of gases, depending on the circumstances. Gases other than process gases, i.e., gases introduced without passing through a gas distribution assembly, other gas distribution device, or the like, may be used, for example, to seal the reaction space and may include seal gases such as noble gases.

[0017] The term precursor can refer to a compound that participates in a chemical reaction that produces another compound. The term "reactant" can be used interchangeably with the term precursor. The term "inert gas" can refer to a gas that does not participate in a chemical reaction and / or does not become part of the layer to any significant extent. Exemplary inert gases include helium and argon and any combination thereof. In some cases, molecular nitrogen and / or hydrogen may be inert gases. The carrier gas and / or purge gas may be or include an inert gas.

[0018] The term substrate, as used in this disclosure, may refer to any underlying material or materials that may be used to form a device, circuit, or film, or on which a device, circuit, or film may be formed. The substrate may include a bulk material such as silicon (e.g., single crystal silicon), other Group IV materials such as germanium, or compound semiconductor materials such as GaAs, and may include one or more layers above or below the bulk material. Additionally, the substrate may have various topologies (such as depressions, lines, and the like) formed within or on at least some of the layers of the substrate.

[0019] The terms "cyclic deposition process" or "cyclical deposition process" may refer to sequentially introducing precursors (and / or reactants) into a reaction chamber (e.g., pulsing one or more precursors (and / or one or more reactants)) to deposit a layer on a substrate, and include processing techniques such as atomic layer deposition (ALD), cyclic chemical vapor deposition (cyclic CVD), and hybrid cyclic deposition processes that include an ALD component and a cyclic chemical vapor deposition (CVD) component. The process may include a purge step after pulsing a reactant and / or precursor. In some cases, one or more reactants and / or precursors may be provided sequentially to the reaction chamber, and one or more other reactants and / or precursors may be pulsed into the reaction chamber. Similarly, a cyclical etch or clean process may include pulsing an etch or clean precursor, followed by a purge step.

[0020] The term "atomic layer deposition," or ALD, can refer to a vapor deposition process in which deposition cycles (typically multiple successive deposition cycles) are performed in a process chamber. As used in this disclosure, the term atomic layer deposition is also meant to include processes denoted by related terms, such as chemical vapor deposition (CVD), when performed with alternating pulses of one or more precursors / one or more reactive gases and one or more purge (e.g., inert carrier) gases.

[0021] Further, in this disclosure, any two numbers for a variable can constitute a workable range for that variable, and any range stated may include or exclude endpoints. In addition, any value for a stated variable (whether or not it is stated with the term "about") refers to an exact or approximate value, may include equivalents, and may refer to an average, median, representative value, or majority or the like. Furthermore, in this disclosure, the terms "including," "constituted by," and "having" can independently refer to "typically or broadly comprising," "comprising," "consisting essentially of," or "consisting of," in some embodiments. In this disclosure, any given meaning does not necessarily exclude, in some embodiments, the ordinary and customary meaning.

[0022] Turning now to the drawings, Figures 1 and 2 illustrate a reactor system 100 in accordance with at least one embodiment of the present disclosure. Figure 1 shows the system 100 in the process of providing a pulse of precursor. Figure 2 shows the system 100 during a purge step of the process.

[0023] The reactor system 100 includes a reactor 102, an apparatus 104 for providing a pulse of a precursor (e.g., to the reactor 102), a vacuum source 106, and a controller 108. Although described in this disclosure in the context of providing a precursor, the system 100 can also be used to provide a pulse of any gas or volatile compound.

[0024] The reactor 102 may be or include a reaction chamber suitable for gas-phase reactions. The reaction chamber may be formed from a suitable material, such as quartz, metal, or the like, and may be configured to hold one or more substrates for processing. The reactor system 100 may include any suitable number of reactors 102 and may optionally include one or more substrate handling systems.

[0025] The reactor 102 may be configured as a CVD reactor, a cyclic deposition process reactor (e.g., a cyclic CVD reactor), an ALD reactor, or the like, any of which may include a plasma device, such as a direct plasma device and / or a remote plasma device. The reactor 102 may be configured to deposit various films or layers, such as multi-component layers, epitaxial layers, and / or perform etching and / or cleaning processes.

[0026] The apparatus 104 for providing pulses of precursor comprises a pressure and flow controller 110, a precursor source 112, a carrier gas line 114, and a precursor line 116. In the illustrated embodiment, the apparatus 104 further comprises a carrier gas source 118, a backsuction line 120, and a reactor inlet line 160.

[0027] The pressure and flow controller 110 may include any suitable pressure and flow control device for controlling the pressure of a gas. By way of example, the pressure and flow controller 110 may be or include a pressure controller with an integrated mass flow meter, such as an MKS GCPMA. The pressure and flow controller 110 is fluidly connected to (e.g., between) the carrier gas source 118 and the carrier gas line 114 to provide a desired amount of carrier gas to the carrier gas line 114. The pressure and flow controller 110 is upstream of the precursor source 112. The various lines and branches described herein, such as the carrier gas line 114, precursor line 116, bypass line, and backsuction line, may be or include any suitable gas conduits, such as tubes, pipes, etc.

[0028] The carrier gas source 118 may include a container 122 and a carrier gas contained therein. As described above, exemplary carrier gases include inert gases such as nitrogen (N), argon, helium, and hydrogen. The carrier gas may be pressurized to a pressure of, for example, about 100 torr to about 900 torr. In some cases, the carrier gas may include a gas that becomes a reactant when activated by a plasma.

[0029] The precursor source 112 includes a precursor container 124 and a precursor 126 contained therein. The precursor source 112 also has a precursor container inlet 128 and a precursor container outlet 130. The precursor line 116 and the isolation valve 156 are fluidly connected to the precursor container outlet 130.

[0030] Precursor 126 may be comprised of any suitable precursor, such as a precursor that is liquid or solid at ambient pressure and temperature. By way of example, precursor 126 may be or comprise one or more liquid or solid ALD or CVD precursors.

[0031] The carrier gas line 114 has a first branch 132 connected to a flow bypass assembly 136 and a second branch 134 connected to the precursor vessel inlet 128. The carrier gas line 114 may also be referred to as a purge gas line.

[0032] The flow bypass assembly 136 includes a first flow bypass line 138 and a second flow bypass line 140. According to various aspects of the illustrated embodiment, the conductance of the first flow bypass line 138 is less than the conductance of the second flow bypass line 140. For example, the conductance of the second flow bypass line 140 may be at least 2 to 5 times, or about 2 to about 15 times, greater than the conductance of the first flow bypass line 138 or other ranges or values ​​described herein. An outlet 141 of the flow bypass assembly 136 is fluidly coupled to the precursor line 116 downstream of the precursor source 112 and / or the reactor inlet line 160. The reactor inlet line 160 may form part of the precursor line 116, or the precursor line 116 may be fluidly coupled to the reactor inlet line 160. As shown, first flow bypass line 138 and second flow bypass line 140 are fluidly coupled (e.g., directly) to precursor line 116 / reactor inlet line 160 at region 142, which is upstream of reactor 102 and downstream of precursor source 112. Reactor inlet line 160 extends from region 142 to the inlet of reactor 102. According to embodiments of the present disclosure, the conductance of reactor inlet line 160 is greater than the conductance of first flow bypass line 138. For example, the conductance of reactor inlet line 160 may be greater than 2 times, greater than 5 times, or about 2-5 times, or about 2-15 times greater than the conductance of first flow bypass line 138.

[0033] As shown, the first flow bypass line 138 has a first bypass metering valve 144 and a first bypass shutoff valve 146. Similarly, the second flow bypass line 140 has a second bypass metering valve 148 and a second bypass shutoff valve 150. Additionally, the carrier gas line 114 has a carrier gas metering valve 152 and a carrier shutoff valve 154. Both the carrier gas metering valve 152 and the carrier shutoff valve 154 are upstream of the precursor source 112. As shown, the metering valves 144, 148, and 152 can be upstream of the respective shutoff valves 146, 150, and 154. In this configuration, the carrier gas line 114, the first flow bypass line 138, and the second flow bypass line 140 each have a metering valve that allows for variable conductance of the respective line. Such a design allows, for example, to provide a high concentration of precursor 126 by utilizing a relatively fast shutoff of the second flow bypass line 140; to provide a faster shutoff of the inert gas valve at the start of the purge, for example, by opening the second flow bypass lines 140, 148, 150 to form the precursor line 116 in region 142; to increase the overall purge / carrier gas flow rate; to relatively quickly change the flow rate, for example, by using the pressure flow controller 110 and changing the conductance of one or more of the first flow bypass line 138, the second flow bypass line 140, and the carrier gas line 114 using metering valves 144, 148, 152; to independently optimize precursor dose concentration and purge efficiency; to reduce leakage by using the pressure flow controller 110 to stagger the flow through the system 100 / apparatus 104, allowing for a higher purge gas flow rate independent of the precursor concentration, thereby reducing undesired deposition or reaction on the backside of the substrate, and so on.

[0034] The back suction line 120 is fluidly connected between the precursor line 116 and the vacuum source 106. More specifically, the back suction line 120 is fluidly connected to the precursor line 116 downstream of the precursor source 112 and upstream of the outlet 141 of the flow bypass assembly 136. This design allows for the formation of an inert gas valve 121, which allows for rapid switching between pulses supplying precursor from the precursor source 112 and pulses providing a higher flow of, for example, purge gas to the reactor 102. In the illustrated embodiment, the back suction line 120 includes an orifice 158 to restrict flow in the back suction line 120.

[0035] The controller 108 is configured to cause the system 100 or apparatus 104 to pulse precursors and / or perform purge steps as described herein. The controller 108 is suitably coupled to the pressure and flow controller 110, the metering valves 144, 148, 152, and the shut-off valves 146, 150, 154 to perform the delivery and purge steps as described herein. The controller 108 includes electronic circuitry and software for selectively operating the pressure and flow controller 110 and the valves 144, 148, 152, 146, 150, 154. The controller 108 can further be configured to selectively operate other manifolds, heaters, pumps (e.g., vacuum source 106), and other components of the system 100. Such circuits and components operate to introduce one or more precursor and purge gases from the respective sources 118 or 112. The controller 108 may control the timing of gas pulse sequences, the temperature of the substrate and / or reaction chamber, the pressure within the reaction chamber, and various other operations to properly operate the system 100. The controller 108 may include control software that independently controls the valves 144, 148, 152, 146, 150, and 154, either electrically or pneumatically, to independently control the flow of precursor and purge gas into the reactor 102. The controller 108 may also include software and / or hardware components, such as modules, such as field-programmable gate arrays (FPGAs) or application-specific integrated circuits (ASICs), that perform specific tasks. The modules are preferably configured to reside on addressable storage media of the control system and to perform one or more processes.

[0036] The vacuum source 106 may be one or more vacuum pumps or may be a configuration that includes one or more vacuum pumps.

[0037] 1 shows system 100 during the step of pulsing a precursor into the reaction chamber. During this step, pressure and flow controller 110 provides carrier gas from carrier gas source 118 to precursor vessel 124, which contains precursor 126, and to flow bypass assembly 136. Isolation valves 154, 156, and 146 are open during the precursor pulsing step, and isolation valve 150 is closed. Metering valves 144, 148, and 152 are all open and may be set to predetermined values.

[0038] During the purge step, as shown in FIG. 2, the isolation valves 154 and / or 156 are closed and the second bypass isolation valve 150 is opened to increase the amount of purge / carrier gas provided during the purge step.

[0039] According to an additional embodiment of the present disclosure, the precursor source assembly 166 includes the precursor source 112, an accumulator 162 coupled to the precursor vessel outlet 130, a pressure sensor 164 coupled to the interior of the accumulator 162, and shut-off valves 154, 156. The precursor source assembly 166 may include a housing 168 that encloses the precursor vessel 124 and a radiant heat source, as described in more detail below.

[0040] 3-5 show exemplary details of a precursor source assembly 300 suitable for use as the precursor source assembly 166 according to embodiments of the present disclosure. The precursor source assembly 300 includes a precursor source 112 (not separately shown in FIGS. 3-5 ), a valve plate 302 with a valve 304 coupled to a vessel 124, an accumulator 306 (which may be the same as the accumulator 162), and a pressure sensor 308 (which may be the same as the pressure sensor 164). The pressure sensor 308 may be or may include a heated manometer. The pressure sensor 308 may be used to determine the amount of material in the accumulator 306. The pressure sensor 308 may be coupled to the controller 108 to provide an indication of the amount of material in the accumulator 306.

[0041] The precursor source assembly 300 also includes a radiant heat source 402, as shown in FIG. 4, within the housing 168. The radiant heat source 402 may include any suitable heat source, such as a resistive element or an infrared heat source. As shown, the radiant heat source 402 may be located between the accumulator 306 and the pressure sensor 308. The housing 168 and the radiant heat source 402 may form a heated inert gas assembly 404.

[0042] The precursor source assembly 300 also includes a heat pipe 310 for providing heat to the pressure sensor 308 from the interior of the housing 168. As shown, the heat pipe 310 is disposed between the accumulator 306 and the pressure sensor 308. The heat pipe 310 may be formed of any suitable thermally conductive material, such as aluminum, copper, tungsten, molybdenum, or a thermally conductive ceramic, such as aluminum nitride. As illustrated in more detail in FIG. 5 , the heat pipe 310 may include two or more parts 502 surrounding a tube 504 that fluidly connects the accumulator 306 and the pressure sensor 308. Using two or more parts for the heat pipe 310 allows the heat pipe 310 to have a relatively large bottom section or base 506 relative to the top section 508. This design allows the heat pipe 310 to be inserted into a port in the housing 168. The two or more parts 502 may be joined together using any suitable technique, such as bolts, screws, adhesives, or other fasteners.

[0043] The precursor source assembly 300 also includes a connector 510 that can be used to reduce heat transfer to the pressure sensor 308. The connector 510 can be made of, for example, stainless steel or the like. The connector 510 can be welded to a (e.g., KFW) seal ring or flange 512, which can be coupled to a corresponding (e.g., KFW) flange 514, which can be welded to an outer wall 516 of the housing 168. A seal 522 can be provided between the flange 512 and the flange 514. The seal 522 can be made of, for example, a polymer such as Viton®, PFA (perfluoroalkoxyalkane), Kalrez®, or Chemrez®. The precursor source assembly 300 can also include a bracket 520 around the flange 512.

[0044] The precursor source assembly 300 may also include an insulator 518 around a portion of the tube 504 above the housing 168. The insulator 518 may be made of, for example, polyetheretherketone (PEEK).

[0045] The above-described exemplary embodiments are merely examples of embodiments of the present disclosure, and these exemplary embodiments of the present disclosure do not limit the scope of the present disclosure. For example, while illustrated with three gas sources, embodiments similar to the illustrated embodiment may be configured with two, four, or more gas sources. Any equivalent embodiments are intended to be within the scope of the present disclosure. Also, various modifications of the present disclosure in addition to those shown and / or described herein, such as alternative useful combinations of the elements described, will become apparent to those skilled in the art from this description. Such modifications and embodiments are also intended to be within the scope of the appended claims.

Claims

1. 1. An apparatus for providing a pulse of a precursor, comprising: a pressure and flow controller fluidly connected to the carrier gas source; a precursor source comprising a precursor container, a precursor container inlet, and a precursor container outlet; a carrier gas line having a first branch connected to a flow bypass assembly and a second branch connected to the precursor vessel inlet; a precursor line connected to the precursor vessel outlet; the pressure and flow controller is upstream of the precursor source; An apparatus wherein the outlet of the flow bypass assembly is connected to the precursor line downstream of the precursor source.

2. the flow bypass assembly includes a first flow bypass line and a second flow bypass line; The apparatus of claim 1 , wherein the conductance of the first flow bypass line is less than the conductance of the second flow bypass line.

3. 3. The apparatus of claim 2, wherein the first flow bypass line comprises a first bypass metering valve and a first bypass shutoff valve.

4. 3. The apparatus of claim 2, wherein the second flow bypass line comprises a second bypass metering valve and a second bypass shutoff valve.

5. 10. The apparatus of claim 1, wherein the carrier gas line comprises a carrier gas metering valve upstream of the precursor source and a carrier shutoff valve upstream of the precursor source.

6. 10. The apparatus of claim 1, further comprising a back suction line coupled to the precursor line downstream of the precursor source and upstream of the outlet of the flow bypass assembly.

7. The apparatus of claim 6 , wherein the back suction line comprises an orifice.

8. 3. The apparatus of claim 2, wherein the conductance of the second flow bypass line is at least 2 to 15 times greater than the conductance of the first flow bypass line.

9. The apparatus of claim 2 further comprising a reactor inlet line connected to the outlet of the flow bypass assembly.

10. 10. The apparatus of claim 9, wherein the conductance of the reactor inlet line is greater than the conductance of the first flow bypass line.

11. 10. The apparatus of claim 1, further comprising an accumulator coupled to the precursor vessel outlet.

12. The apparatus of claim 11 , further comprising a pressure sensor coupled to an interior of the accumulator.

13. The apparatus of claim 12 , wherein the pressure sensor comprises a heated manometer.

14. The apparatus of claim 12 further comprising a heat pipe interposed between the accumulator and the pressure sensor.

15. The apparatus of claim 14 further comprising an enclosure around the heat pipe.

16. The apparatus of claim 1 further comprising a housing around the precursor container and the radiant heat source.

17. 1. A reactor system comprising: a reactor; and a vacuum source coupled to the reactor; A controller; 1. An apparatus for providing a pulse of a precursor, the apparatus comprising: a pressure and flow controller fluidly connected to the carrier gas source; a precursor source comprising a precursor container, a precursor container inlet, and a precursor container outlet; a carrier gas line having a first branch connected to a flow bypass assembly and a second branch connected to the precursor vessel inlet; a precursor line connected to the precursor vessel outlet; the pressure and flow controller is upstream of the precursor source; an outlet of the flow bypass assembly coupled to the precursor line downstream of the precursor source.

18. 20. The reactor system of claim 17, further comprising an accumulator coupled to the precursor vessel outlet and a pressure sensor coupled to the accumulator.

19. 1. A method of providing pulsed precursors to a reaction chamber, comprising: providing a flow bypass assembly comprising a first flow bypass line and a second flow bypass line, the first flow bypass line having a conductance less than the conductance of the second flow bypass line; providing a carrier gas to a precursor vessel containing a precursor therein and to the flow bypass assembly using a pressure and flow controller; The precursor opening a valve between the pressure and flow controller and the precursor container; and closing a valve in the second flow bypass line to pulse the solution into the reaction chamber.

20. 20. The method of claim 19, further comprising opening a valve in the second flow bypass line to purge the reaction chamber.

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