Patent Publication Number: US-11377732-B2

Title: Reactant vaporizer and related systems and methods

Description:
REFERENCE TO RELATED APPLICATION 
     This application is a continuation of U.S. patent application Ser. No. 15/283,120, filed Sep. 30, 2016, the entire disclosure of which is incorporated herein by reference in its entirety. 
    
    
     BACKGROUND 
     Field 
     The present application relates generally to systems and methods involving semiconductor processing equipment and specifically to vaporizing systems for chemical vapor delivery. 
     Description of the Related Art 
     A typical solid or liquid source reactant delivery system includes a solid or liquid source vessel and a heating means (e.g., radiant heat lamps, resistive heaters, etc.). The vessel includes the solid (e.g., in powder form) or liquid source precursor. The heating means heats up the vessel to vaporize the reactant in the vessel. The vessel has an inlet and an outlet for the flow of an inert carrier gas (e.g., N 2 ) through the vessel. The carrier gas sweeps reactant vapor along with it through the vessel outlet and ultimately to a substrate reaction chamber. The vessel typically includes isolation valves for fluidly isolating the contents of the vessel from the vessel exterior. Ordinarily, one isolation valve is provided upstream of the vessel inlet, and another isolation valve is provided downstream of the vessel outlet. 
     SUMMARY 
     In one aspect, a solid source chemical vaporizer is provided. The vaporizer can include a housing base, a first tray that is configured to be housed within the housing base such that the first tray defines a first serpentine path adapted to hold solid source chemical and allow gas flow thereover, a second tray that is configured to be housed within the housing base vertically adjacent the first tray such that the second tray defines a second serpentine path adapted to hold solid source chemical and allow gas flow thereover, and a housing lid. 
     In some embodiments, the first serpentine path and the second serpentine path are fluidly connected in series. In other embodiments, the first serpentine path and the second serpentine path are fluidly connected in parallel. In such embodiments, the first serpentine path and the second serpentine path can be not in fluid communication with each other within the solid source chemical vaporizer. 
     The first and second serpentine paths can each include a recess formed in a solid metal block. Each of the recesses can define a height:width aspect ratio in a range of about 1.5-5. 
     In some embodiments, the housing lid includes a first inlet valve mounted on the lid and in fluid communication with the first serpentine path, a first outlet valve mounted on the lid and in fluid communication with the first serpentine path, a second inlet valve mounted on the lid and in fluid communication with the second serpentine path, and a second outlet valve mounted on the lid and in fluid communication with the second serpentine path. 
     The housing lid can further include a vent valve mounted on the lid and in fluid communication with each of the first and second serpentine paths. 
     In another aspect, a solid source chemical vaporizer includes a housing base, a first tray configured to be housed within the housing base such that the first tray defines a first path adapted to hold solid source chemical and allow gas flow thereover, and a second tray configured to be housed within the housing base vertically adjacent the first tray. The second tray defines a second path adapted to hold solid source chemical and allow gas flow thereover. The vaporizer also includes a housing lid, a first inlet valve mounted on the housing lid and in fluid communication with the first path, a first outlet valve mounted on the housing lid and in fluid communication with the first path, a second inlet valve mounted on the housing lid and in fluid communication with the second path, and a second outlet valve mounted on the housing lid and in fluid communication with the second path. 
     The housing lid can further include a vent valve mounted on the lid and in fluid communication with each of the first and second serpentine paths. 
     In some embodiments, the solid source chemical vaporizer defines a ratio of a volume (in mm 3 ) enclosed by the solid source chemical vaporizer to the total path length (in mm) of the first and second trays in a range of about 400-1200. 
     In another aspect, a multiple chamber deposition module is provided. The multiple chamber deposition module includes a first vapor phase reaction chamber for depositing a first material on a first substrate, a second vapor phase reaction chamber for depositing a second material on a second substrate, and a solid source chemical vaporizer connected to supply each of the first and second vapor phase reaction chambers. 
     In some embodiments, the solid source chemical vaporizer can include a first tray defining a first serpentine path such that the first serpentine path is adapted to hold solid source chemical and allow gas flow thereover, and a second tray defining a second serpentine path such that the second serpentine path is adapted to hold solid source chemical and allow gas flow thereover. 
     The solid source chemical vaporizer can further include a housing base, a housing lid, a first inlet valve mounted on the housing lid and in fluid communication with the first serpentine path, a first outlet valve mounted on the housing lid and in fluid communication with the first serpentine path, a second inlet valve mounted on the housing lid and in fluid communication with the second serpentine path, a second outlet valve mounted on the housing lid and in fluid communication with the second serpentine path, and a vent valve mounted and in fluid communication with each of the first and second serpentine paths. The first outlet valve and the second outlet valve can be in fluid communication at a connection point, and a carrier gas can selectively pass from a separation point into the first vapor phase reaction chamber and/or the second vapor phase reaction chamber. The module can also include a first gas panel valve fluidly interposed between the connection point and the separation point. The module can additionally include a first filter on the housing lid or in a wall of the housing base, where the first filter adapted to prevent solid particulate matter from flowing therethrough. The module can additionally include a heater plate vertically adjacent the solid source chemical vaporizer. 
     In some embodiments, the module additionally includes control processors and software configured to operate the first vapor phase reaction chamber to perform atomic layer deposition (ALD). In other embodiments, the module additionally includes control processors and software configured to operate the first vapor phase reaction chamber to perform chemical vapor deposition (CVD). 
     In some embodiments, the first serpentine path and the second serpentine path are fluidly connected in parallel. In such embodiments, the first serpentine path and the serpentine module path can fluidly communicate at a connection point fluidly interposed between the solid source chemical vaporizer and a separation point. The separation point can be disposed at an upper valve plate and can be fluidly interposed between the connection point and each of the first and second vapor phase reaction chambers. 
     In some embodiments, module additionally includes a heater plate vertically adjacent the solid source chemical vaporizer and a valve plate heater disposed above the housing lid. The heater plate and valve plate heater can be adapted to heat the housing base to an operating temperature in a range of about 50° C.-250° C. 
     In another aspect, a method for delivering vaporized precursor in a multiple chamber deposition module can include connecting a solid source chemical vaporizer to supply each of first and second vapor phase reaction chambers and heating the solid source chemical vaporizer to an operating temperature. 
     In some embodiments, the method additionally includes providing a first solid source chemical in a first serpentine path of a first tray and a second solid source chemical in a second serpentine path of a second tray. The first and second serpentine paths can be fluidly connected in parallel. In other arrangements, the first and second serpentine paths can be fluidly connected in series. The first and second serpentine paths can be arranged to not be in fluid communication with each other within the solid source chemical vaporizer. 
     In some embodiments, the method also includes passing a first inert gas over the first solid source chemical and a second inert gas over the second solid source chemical, depositing a first material on a first substrate in the first vapor phase reaction chamber, and depositing a second material on a second substrate in the second vapor phase reaction chamber. The first material can be different from the second material. Depositing the first material and depositing the second material can each include performing atomic layer deposition (ALD). Depositing the first material and depositing the second material can each include performing chemical vapor deposition (CVD). 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other aspects of the disclosure will be readily apparent to the skilled artisan in view of the description below, the appended claims, and from the drawings, which are intended to illustrate and not to limit the invention, and wherein: 
         FIG. 1A  illustrates a schematic of some embodiments of solid source chemical vaporizer (SSCV) vessels. 
         FIG. 1B  shows schematically an embodiment of a multiple-chamber deposition module that includes a vessel supplying multiple deposition chambers. 
         FIG. 2A  shows a fluid configuration of the trays of the vessel such that the trays have separate flow paths within the vessel. 
         FIG. 2B  shows a fluid configuration of the trays of the vessel such that the flow paths through the trays are arranged in parallel but may merge within the vessel. 
         FIG. 2C  shows a fluid configuration of the trays of the vessel such that the flow paths through the trays are arranged in series. 
         FIG. 2D  illustrates an exemplary ALD process. 
         FIG. 3  schematically shows an example SSCV vessel that is fluidly connected to multiple deposition chambers. 
         FIG. 4  is an exploded front, top and right isometric view of a housing lid, a housing base, and two internal reactant trays of a solid source chemical vessel, in accordance with an embodiment. 
         FIG. 5  is a front, top and right isometric view of the assembled vessel of  FIG. 4 . 
         FIG. 6A  is a partial top plan view of the base and top tray of  FIG. 4 , showing various porting recesses and other fluidic structures in various embodiments. 
         FIG. 6B  is a top isometric view of the base and top tray various porting recesses and tray structure in certain embodiments. 
         FIG. 7  is a cross-sectioned front, top and right isometric view of the top tray and lid of  FIG. 4  in certain configurations. 
         FIG. 8  is a cross-sectional side view of an example vessel through one of the valves configured to be in fluid communication with a first tray. 
         FIG. 9  is a cross-sectional side view of an example vessel through one of the valves configured to be in fluid communication with a second tray. 
         FIG. 10  is a cross-sectional side view of an example vessel through a vent valve configured to be in fluid communication with a first tray and a second tray. 
         FIG. 11  is a front, top and left isometric view of a solid source assembly incorporating the solid source chemical vessel of  FIG. 4 . 
         FIG. 12  is a front elevational view of a multi-chamber deposition module incorporating the solid source assembly of  FIG. 11 , in accordance an embodiment. 
         FIG. 13  illustrates a schematic fluid-flow diagram of an example multiple chamber deposition module. 
         FIG. 14  schematically illustrates a solid source assembly in accordance with some embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     The headings provided herein, if any, are for convenience only and do not necessarily affect the scope or meaning of the claimed invention. 
     Described herein are systems and related methodologies for delivering vaporized reactant in a multiple-chamber deposition module. This application further describes systems for vaporizing chemical solid source material and delivering reactant vapor that may be used in deposition modules comprising one or more deposition modules. 
     The following detailed description of the preferred embodiments and methods details certain specific embodiments to assist in understanding the claims. However, one may practice the present invention in a multitude of different embodiments and methods, as defined and covered by the claims. 
     Chemical vapor deposition (CVD) is a known process in the semiconductor industry for forming thin films of materials on substrates such as silicon wafers. In CVD, reactant vapors (including “precursor gases”) of different reactant chemicals are delivered to one or more substrates in a reaction chamber. In many cases, the reaction chamber includes only a single substrate supported on a substrate holder (such as a susceptor), with the substrate and substrate holder being maintained at a desired process temperature. In typical CVD processes, mutually reactive reactant vapors react with one another to form thin films on the substrate, with the growth rate being related to the temperature and the amounts of reactant gases. In some variants, energy to drive the deposition reactants is supplied in whole or in part by plasma. 
     In some applications, the reactant gases are stored in gaseous form in a reactant source vessel. In such applications, the reactants are often gaseous at standard pressures and temperatures of around 1 atmosphere and room temperature. Examples of such gases include nitrogen, oxygen, hydrogen, and ammonia. However, in some cases, the vapors of source chemicals (“precursors”) that are liquid or solid (e.g., hafnium chloride, hafnium oxide, zirconium dioxide, etc.) at standard pressure and temperature are used. For some solid substances (referred to herein as “solid source precursors”), the vapor pressure at room temperature is so low that they are typically heated and/or maintained at very low pressures to produce a sufficient amount of reactant vapor for the reaction process. Once vaporized, it is important that the vapor phase reactant is kept at or above the vaporizing temperature through the processing system so as to prevent undesirable condensation in the valves, filters, conduits, and other components associated with delivering the vapor phase reactants to the reaction chamber. Vapor phase reactants from such naturally solid or liquid substances are useful for chemical reactions in a variety of other industries. 
     Atomic layer deposition (ALD) is another known process for forming thin films on substrates. In many applications, ALD uses a solid and/or liquid source chemical as described above. ALD is a type of vapor deposition wherein a film is built up through self-saturating reactions performed in cycles. The thickness of the film is determined by the number of cycles performed. In an ALD process, gaseous reactants are supplied, alternatingly and/or repeatedly, to the substrate or wafer to form a thin film of material on the wafer. One reactant adsorbs in a self-limiting process on the wafer. A different, subsequently pulsed reactant reacts with the adsorbed material to form a single molecular layer of the desired material. Decomposition may occur through mutual reaction between the adsorbed species and with an appropriately selected reagent, such as in a ligand exchange or a gettering reaction. In a theoretical ALD reaction, no more than a molecular monolayer forms per cycle. Thicker films are produced through repeated growth cycles until the target thickness is achieved. 
     In theoretical ALD reactions, mutually reactive reactants are kept separate in the vapor phase with intervening removal processes between substrate exposures to different reactants. For example, in time-divided ALD processes, reactants are provided in pulses to a stationary substrate, typically separated by purging or pump down phases; in space-divided ALD processes, a substrate is moved through zones with different reactants; and in some processes aspects of both space-divided and time-divided ALD can be combined. The skilled artisan will appreciate that some variants or hybrid processes allow some amount of CVD-like reactions, either through selection of the deposition conditions outside the normal ALD parameter windows and/or through allowing some amount of overlap between mutually reactive reactants during exposure to the substrate. 
     Reactant source vessels are normally supplied with gas lines extending from the inlet and outlet, isolation valves on the lines, and fittings on the valves, the fittings being configured to connect to the gas flow lines of the remaining substrate processing apparatus. It is often desirable to provide a number of additional heaters for heating the various valves and gas flow lines between the reactant source vessel and the reaction chamber, to prevent the reactant vapor from condensing and depositing on such components. Accordingly, the gas-conveying components between the source vessel and the reaction chamber are sometimes referred to as a “hot zone” in which the temperature is maintained above the vaporization/condensation temperature of the reactant. 
       FIG. 1A  illustrates a schematic of some embodiments of solid source chemical vaporizer (SSCV) vessels. A solid source precursor is a source chemical that is solid under standard conditions (i.e., room temperature and atmospheric pressure). In some embodiments, the vessel  104  can include a housing base  480 , a housing lid  113 , a first tray  108 , and a second tray  112 . The vessel  104  may include one or more trays, and  FIG. 1A  should not be viewed as limiting the number of trays the vessel  104  can contain, as described herein. In some embodiments, the lid  113  is adapted to be mechanically attached to the housing base  480 . This may be done using one or more of attachment devices (e.g., bolts, screws, etc.). In certain embodiments, the lid  113  and the housing base  480  are mechanically attached in a gas-tight fashion. 
     In certain configurations, the trays  108 ,  112  are adapted to hold solid source chemical and allow the flow of gas thereover. In some embodiments, the second tray  112  is housed within the vessel vertically adjacent the first tray  108 . In certain configurations, vertically adjacent includes being in physical contact. In some embodiments, adjacent includes being fluidly sealed such that vapor in one tray does not directly communicate with another tray, as described in further detail herein. In some embodiments, the second tray  112  is situated above the first tray  108 . In some embodiments, the second tray  112  is situated below the first tray  108 . In certain embodiments, the trays  108 ,  112  each define a serpentine path that is adapted to hold solid source chemical for a vapor deposition reaction. 
       FIG. 1B  shows schematically how a multiple-chamber deposition module  198  can include a vessel  104  and two or more deposition chambers  312 ,  316 . In some embodiments, the deposition chambers  312 ,  316  can be controlled using corresponding controllers  313 ,  317 . In some embodiments, the controllers  313 ,  317  are configured to perform ALD, as described in more detail herein. In some embodiments, the controllers  313 ,  317  include processors and memory programmed to perform ALD. While shown as separately associated with deposition chambers, the skilled artisan will appreciate that a single controller or multiple controllers can govern the operation of both chambers, any heaters in the deposition module  198 , pumps and/or valves to pumps for pressure control, robotic control for substrate handling, and valves for control of vapor flow, including carrier flow to and vapor flow from the solid source vessel  104 . The module  198  may include more than two deposition chambers  312 ,  316 , and  FIG. 1B  should not be viewed as limiting the number of deposition chambers  108 ,  112  the module  198  can contain, as described herein. In the illustrated embodiment, the deposition chambers  312 ,  316  are in fluid communication with the vessel, as described herein in more detail. 
     The illustrated SSCV vessel  104  and multiple-chamber deposition module  198  are particularly suited for delivering vapor phase reactants to be used in multiple vapor phase reaction chambers. The vapor phase reactants can be used for deposition (e.g., CVD) or Atomic Layer Deposition (ALD). In some embodiments, control processors and programming stored on computer-readable media are included such that the embodiments disclosed herein are configured to perform ALD. In certain embodiments, control processors and programming stored on computer-readable media are included such that the embodiments disclosed herein are configured to perform CVD. 
     In some embodiments, a fluid configuration  200  of the trays  108 ,  112  of the vessel  104  is such that the trays form parts of flow paths that are separate from one another, e.g., are not in direct fluid communication with one another, within the vessel  104 , as shown in  FIG. 2A . Inlet flow of a carrier gas splits at a separation point  124  is positioned between a gas entry point  130  and inlet valves  116 ,  120 . The flow of carrier gas into the vessel  104  at inlets  152 ,  156  can be controlled by opening and/or closing the inlet valves  116 ,  120 . Fluid flow paths continue from the vessel inlets  152 ,  156  to their respective tray inlets  162 ,  166 . The vessel inlets  152 ,  156  and the tray inlets  162 ,  166  can coincide in some embodiments. Each of the trays  108 ,  112  may define serpentine reactant beds and flow paths thereover, as will be better understood from the description of  FIGS. 4-12  below. 
     As shown in  FIG. 2A , the flow paths of the first tray  108  and of the second tray  112  are not in fluid communication within the vessel  104 . In the illustrated configuration, the trays  108 ,  112  have respective tray outlets  172 ,  176  in fluid communication with respective vessel outlets  182 ,  186 . In certain configurations, the tray outlets  172 ,  176  can coincide with the vessel outlets  182 ,  186 . Fluid that passes through trays  108 ,  112  can exit the fluid configuration shown at exit points  140 , which can lead to other flow control devices (e.g., valves) and the deposition chamber(s). The effluent from the vessel  104  includes carrier gas and reactant gas vaporized within the trays  108 ,  112 . In some embodiments, the effluent from both trays can merge downstream of the illustrated exit points  140 . 
     Inactive or inert gas is preferably used as the carrier gas for the vaporized precursor. The inert gas (e.g., nitrogen, argon, helium, etc.) may be fed into the SSCV vessel  104  through the entry point  130 . In some embodiments, different inert gases may be used for various processes and in various systems described herein. 
     It will be appreciated that additional valves and/or other fluidic control elements may be included that are not shown. For example, in addition to inlet valves, each of the trays  108 ,  112  can be provided with separate outlet valves, as will be appreciated from the description of embodiments described with respect to  FIGS. 4-12  below. 
       FIG. 2B  illustrates another embodiment in which the trays  108 ,  112  can be arranged in parallel.  FIG. 2B  differs from  FIG. 2A  in that the flow can split at the separation point  124  and merge at a merger point  260  within the SSCV vessel  104 . In the illustrated embodiment, the separation point  124  is downstream of an inlet valve  204  and vessel inlet  256 , while the merger point  260  is upstream of a vessel outlet  286  and outlet valve  208 . In still other arrangements that combine features of  FIGS. 2A and 2B , one of the separation point  124  and merger point  260  can be within the vessel  104 , while the other is outside the vessel  104 . 
     As will be appreciated by the skilled artisan, parallel flow arrangements through the trays  108 ,  112  as shown in  FIGS. 2A and 2B  enable high concentration doses to be delivered to the deposition chamber(s) without occupying the volume or footprint that multiple vapor sources would entail. As described in more detail below, each tray can include an elongated path, particularly a serpentine path, over solid reactant to enable contact of the carrier gas with a high surface area of solid reactant. 
     It will be appreciated that additional valves and/or other fluidic elements may be included that are not shown. For example, a three-way switching valve can be provided at the separation point  162  that can alternate the flow through the first tray  108  and the second tray  112 . Such configurations can also allow the first tray  108  to continue vaporizing and collecting vapor above the solid source chemical bed(s) without removal thereof while carrier gas flows through and carries away reactant vapor in the second tray  112 , and vice versa. Additionally, switching valves can be provided downstream of the SSCV vessel  104  to alternate flow from the vessel  104  to two or more reactors (for example, deposition chambers). Such additional switching valves can be applied to either of the parallel arrangements of  FIGS. 2A and 2B . 
     In some embodiments, the trays  108 ,  112  can be arranged in series, as shown in  FIG. 2C . In such a fluid configuration  200  the trays  108 ,  112  can receive gas from a common entry point  130  that feeds a common inlet valve  204 . Carrier gas can enter the vessel at a vessel inlet  256 . In certain embodiments, the gas passes through a first tray inlet  162  before passing into the first tray  108 . After passing through the first tray  108 , which may include a serpentine reactant bed and flow path, the gas can exit the first tray  108  at a first tray outlet  152  before entering the second tray  112 , which may also include a serpentine reactant bed and flow path, at a second tray inlet  166 . It will be understood that  FIG. 2C  is schematic and that the two trays  108 ,  112  may have various physical relations to each other within the SSCV vessel  104 . In embodiments shown in  FIGS. 4-12 , low profile trays are vertically stacked within a single housing, and in such embodiments the first tray  108  can represent the upper or the lower tray. 
     As shown, in some embodiments the gas can exit the second tray  112  through a second tray outlet  176 . The gas can pass from the vessel outlet  286  through the outlet valve  208  to an exit point  140 . In some embodiments, the outlet valve  208  can be used to regulate the flow of fluid that passes to the exit point  140  and/or the flow of gas that passes through the vessel outlet  286 . 
     It will be appreciated that additional valves and/or other fluidic elements may be included that are not shown. For example, one or more of the vessel inlet  256 , the tray inlets  162 ,  166 , the tray outlets,  172 ,  176 , and vessel outlet  286  can be equipped with valves that are configured to regulate the flow of gas therethrough. Additional valves and other fluidic elements may be included that are not shown in certain configurations. 
       FIG. 2D  illustrates an exemplary ALD process  2100 . Some embodiments may include a pretreatment process at block  2110  applied to the substrate surface. A pretreatment may comprise one or more processes. In the pretreatment, the substrate surface on which a first reactant (e.g., comprising a metal) is to be deposited may be exposed to one or more pretreatment reactants and/or to specific conditions, such as temperature or pressure. A pretreatment may be used for any number of reasons, including to clean the substrate surface, remove impurities, remove native oxide, and provide desirable surface terminations to facilitate subsequent deposition reactions or adsorption. In some embodiments, a pretreatment comprises exposing the substrate surface to one or more pretreatment reactants, such as an oxidation source and/or cleaning reactant, such as H 2 O, O 3 , HCl, HBr, Cl 2 , HF, plasma products, etc. In some embodiments, a pretreatment process comprises one or more exposures of the substrate of a suitable chemical, the exposures ranging from about 0.05 s to about 600 s, preferably from about 0.1 s to about 60 s. In some embodiments, the pressure during a pretreatment process is maintained between about 0.01 Torr and about 100 Torr, preferably from about 0.1 Torr to about 10 Torr. In some embodiments, multiple pretreatment reactants are used sequentially or simultaneously. In some embodiments, a pretreatment may involve multiple applications of one or more pretreatment reactants. 
     A pretreatment process may utilize pretreatment reactants in vapor form and or in liquid form. The pretreatment process may be performed at the same temperature and/or pressure as the subsequent ALD process; however, it may also be performed at a different temperature and/or pressure. For example, where an ex situ pretreatment involves the immersion of the substrate in an aqueous solution, it may be desirable to allow the pretreatment to proceed at a higher pressure than the ALD process, which may be performed at relatively low pressures that could undesirably evaporate the pretreatment reactant. 
     Referring again to  FIG. 2D , the substrate is contacted with a first reactant at block  2120 . Reactants may also be referred to as precursors where the reactant leaves element(s) in the film being deposited. In some embodiments with a stationary substrate (time divided ALD) the first reactant is conducted into a reaction chamber in the form of vapor phase pulse and contacted with the surface of the substrate. Where the first reactant is a precursor to be adsorbed, conditions can be selected such that no more than about one monolayer of the precursor is adsorbed on the substrate surface in a self-limiting manner. The first precursor pulse is supplied in gaseous form. The first precursor gas is considered “volatile” for purposes of the present description if the species exhibits sufficient vapor pressure under the process conditions to transport the species to the workpiece in sufficient concentration to saturate exposed surfaces. 
     In some embodiments the first precursor contacts the substrate for about 0.01 seconds to about 60 seconds, for about 0.02 seconds to about 30 seconds, for about 0.025 seconds to about 20 seconds, for about 0.05 seconds to about 5.0 seconds, about 0.05 seconds to about 2.0 seconds or about 0.1 seconds to about 1.0 second. As the skilled artisan will appreciate, exposure time to ensure surface saturation will depend on reactor volume, size of the substrate, precursor concentration in the carrier gas, and process conditions. 
     The first precursor employed in the ALD type processes may be solid, liquid, or gaseous material under standard conditions (room temperature and atmospheric pressure), provided that the first precursor is in vapor phase before it is conducted into the reaction chamber and contacted with the substrate surface. In some embodiments, the first precursor may include a metal and may be a solid source material under standard conditions, such as in the form of a powder in the SSCV vessel  104  described herein. 
     At block  2130  excess first reactant and reaction byproducts, if any, are removed from the substrate surface, for example by supply of inert gas such as nitrogen or argon. Vapor phase precursors and/or vapor phase byproducts are removed from the substrate surface, for example by evacuating the chamber with a vacuum pump and/or by replacing the gas inside the reactor with an inert gas such as argon or nitrogen. Typical removal times are from about 0.05 to 20 seconds, more preferably between about 1 and 10 seconds, and still more preferably between about 1 and 2 seconds. However, other removal times can be utilized if necessary, such as when depositing layers over extremely high aspect ratio structures or other structures with complex surface morphology is needed. The appropriate removal times can be readily determined by the skilled artisan based on the particular circumstances. 
     In other embodiments, removing excess first reactant and reaction byproducts, if any, may comprise moving the substrate so that the first reactant no longer contacts the substrate. In some embodiments no reactant may be removed from the various parts of a chamber. In some embodiments the substrate is moved from a part of the chamber containing a first precursor to another part of the chamber containing a second reactant or no reactant at all. In some embodiments the substrate is moved from a first reaction chamber to a second, different reaction chamber. In such embodiments, the substrate may be moved, for example, through a zone or curtain of inert gas to aid removal, analogous to purging a chamber for a stationary substrate. 
     At block  2140  the substrate is contacted with a second reactant (e.g., precursor). In some embodiments, the second reactant comprises oxygen (e.g., water vapor, ozone, etc.). 
     In some embodiments the second precursor contacts the substrate for about 0.01 seconds to about 60 seconds, for about 0.02 seconds to about 30 seconds, for about 0.025 seconds to about 20 seconds, for about 0.05 seconds to about 5.0 seconds, about 0.05 seconds to about 2.0 seconds or about 0.1 seconds to about 1.0 second. However, depending on the reactor type, substrate type and its surface area, the second precursor contacting time may be even higher than 10 seconds. In some embodiments, particularly batch reactors with high volumes, contacting times can be on the order of minutes. The optimum contacting time can be readily determined by the skilled artisan based on the particular circumstances. 
     The concentration of the second precursor in the reaction chamber may be from about 0.01% by volume to about 99.0% by volume. And the second precursor may flow through the reaction chamber at a rate of between about 1 standard cm 3 /min and about 4000 standard cm 3 /min for typical single substrate reactors. The skilled artisan will appreciate that reaction conditions outside the above ranges may be suitable for certain types of reactors. 
     At block  2150 , excess second reactant and gaseous by-products of the surface reaction, if any, are removed from the substrate surface, as described above for block  2130 . In some embodiments excess reactant and reaction byproducts are preferably removed with the aid of an inert gas. The steps of contacting and removing may be optionally repeated at block  2160  until a thin film of the desired thickness has been formed on the substrate, with each cycle leaving no more than a molecular monolayer in a pure ALD process. However, the skilled artisan will appreciate that in some embodiments, more than a monolayer may be achieved by modifying conditions to be outside theoretical ALD conditions. For example, some amount of overlap between the mutually reactive reactants may be allowed to result in partial or hybrid CVD-type reactions. In some cases, it might be desirable to achieve at least partial decomposition of at least one the various precursors through selection of temperatures above the normal ALD window, by injection of energy through other means (e.g., plasma products), or condensation of multiple monolayers of the first reactant may be achieved by selection of temperatures below the normal ALD window for those reactants. 
     Various other modifications or additions to the process are possible. For example, more complicated cycles may include phases for additional precursors or other types of reactants (e.g., reducing agents, oxidizing agents, gettering agents, plasma or thermal treatments, etc.). Different cycles may be employed at selected relative frequency to tune compositions of the desired films. For example, silicon oxynitride may include 5 silicon oxide cycles for every 1 silicon nitride cycles, or any other desired ratio of cycles, depending upon the desired nitrogen content, and the ratios may change during the deposition if grading is desired in the layer composition. Additionally, because the process is cyclical, the “first” reactant may be supplied second without materially altering the process. 
     With reference to  FIG. 3 , in some embodiments, the SSCV vessel  104  can be fluidly connected to one or more deposition chambers  312 ,  316 . In some embodiments, the deposition chambers  312 ,  316  can be controlled using corresponding controllers  313 ,  317 . In some embodiments, the controllers  313 ,  317  are associated with individual the deposition chambers (as shown). In some embodiments, the electronics and/or computer elements for use in controlling the deposition chambers  312 ,  316  can be found elsewhere in the system. For example, central controllers may control both apparatus of the chambers  312 ,  316  themselves as well as control the valves that connect to the SSCV vessel  104  and heaters associated with the SSCV vessel  104 . One or more valves may be used to control the flow of gas throughout the multiple chamber deposition module  300 . As shown in  FIG. 3 , a gas can flow from an entry point  330  into one or more inlet valves  116 ,  120 . 
     In some circumstances, precursor source vessels are typically supplied with a head pressure of inert gas (e.g., helium) in the vessel when they are filled or recharged with precursor powder to minimize disturbance while moving the vessels. Before operation, it is desirable to vent this overpressure, but during such venting, solid precursor particles can become aerosolized and entrained in the inert gas outflow. This can contaminate the gas delivery system because such gas is typically vented out through the vessel&#39;s outlet isolation valve, the reactant gas delivery system, and ultimately the reactor&#39;s exhaust/scrubber. Later, during substrate processing, the contaminated portions of the gas panel that are common to the precursor delivery path and the vent path can cause processing defects during ALD on the substrate. In certain embodiments, a separate vent valve  320  can be used to fluidly connect to both of the trays  108 ,  112 . In some cases the vent valve can be used to release pressure from one or more of the trays  108 ,  112 . To achieve this, for example, inlet valves  116 ,  120  and outlet valves  304 ,  308  can be closed to facilitate the flow of gas through the vent valve  320  in some embodiments. The flow of gas can exit the system at an exit point  341 . The exit point  341  can release the gas as waste. 
     With continued reference to  FIG. 3 , in some embodiments the module  300  can be configured to allow gas to flow through a first inlet valve  116  into vessel inlet  152 . Similarly, the module  300  can be configured to facilitate gas flow through a second inlet valve  120  and through a second vessel inlet  156 . Gas can pass from the vessel inlets  152 ,  156  into the respective trays  108 ,  112  through respective tray inlets  162 ,  166 . 
     As shown in  FIG. 3 , in some embodiments, the gas can flow out of the trays  108 ,  112  via respective tray outlets  172 ,  176  and through respective vessel outlets  162 ,  166 . In some embodiments, the trays  108 ,  112  can be in fluid communication at one or more connection points  324 ,  328 . In some embodiments, one or more of the connection points  324 ,  328  can include one or more valves (not shown) that can facilitate gas through the appropriate gas lines. For example, a valve at the first connection point  324  can be closed to facilitate gas flow through a valve that is open at the second connection point  328 . 
     In some variations, the module  300  can be configured to allow gas to flow through a first outlet valve  304 . In some embodiments, the gas can continue to flow through to an exit point  340 . The exit point  340  can lead, e.g., to a separate deposition chamber module or for analysis of the gas. Such an analysis may include monitoring the saturation levels, ratios of chemicals, or levels of impurities in the gas. 
     In some embodiments, the system  300  can be configured to allow gas to flow a second outlet valve  308  to a chamber separation point  332 . In some embodiments, the chamber separation point  332  can include one or more valves such that the flow of gas into or more deposition chambers  312 ,  316  can be controlled. For example, in some configurations, a three-way valve at the chamber separation point  332  can be configured such that gas flows alternately or simultaneously to the deposition chambers  312 ,  316 . 
     It will be appreciated that additional valves and/or other fluidic elements may be included that are not shown. For example, one or more of the vessel inlets  152 ,  156 , the tray inlets  162 ,  166 , the tray outlets,  172 ,  176  and vessel outlets  162 ,  166  can be equipped with valves that are configured to regulate the flow of gas therethrough. Additional valves and other fluidic elements may be included that are not shown, in certain configurations. 
       FIG. 4  illustrates an exploded view of some embodiments of the SSCV vessel  104 . In some embodiments, the vessel  104  can include one or more valves  420 ,  424 ,  428 ,  432 ,  436 . Certain configurations allow for a greater or fewer number of valves than are shown. In some embodiments, valves can be removably attached to the vessel  104 . As illustrated, a first tray  108  and a second tray  112  can be housed or contained within a housing base  480 . As shown, the first tray  108  can be vertically adjacent the second tray  112 . In some embodiments, a housing lid  113  can be mechanically attached to the housing base  480 . In some embodiments, the attachment can be achieved using one or more attachment devices (e.g., screws, bolts, etc.). In some embodiments, the housing lid  113  and housing base  480  are fluidly sealed such that gas substantially cannot enter and/or escape the vessel  104 , except as described herein. 
     In some configurations, the housing lid  113  can comprise one or more inlet valves,  420 ,  424 , one or more outlet valves  432 ,  436 , and/or a vent valve  428 . In some embodiments, these valves can be attached to, but can be separate from, the housing lid  113 . In some embodiments, valves can be removably attached to the housing lid  113 . 
     In some embodiments, one or more of the trays  108 ,  112  can comprise a metal, particularly stainless steel or aluminum. Similarly, in some embodiments, one or more of the housing lid  113  and/or housing base  480  can comprise a metal. The trays  108 ,  112 , housing lid  113  and/or housing base  480  can each be monolithic metal parts in some embodiments. 
       FIG. 5  shows how the housing lid  113  and housing base  480  can be assembled to form the vessel  104  in certain embodiments. In some embodiments, the height of the assembly of the housing lid  113  and housing base  480  can be in the range of about 30 mm-750 mm. In some embodiments, the height of the assembly of the housing lid  113  and housing base  480  can be in the range of about 50 mm-100 mm, and is about 76 mm (about 3 inches) in the illustrated embodiment. In some embodiments, the length of the vessel  104  can be in the range of about 100 mm-635 mm. In some embodiments, the length of the vessel  104  can be in the range of about 200 mm-400 mm, and is about 305 mm (about 12 inches) in the illustrated embodiment. In some embodiments, the width of the vessel  104  can be in the range of about 100 mm-525 mm. In some embodiments, the width of the vessel  104  can be in the range of about 180 mm-360 mm, and is about 254 mm (about 10 inches) in the illustrated embodiment. In some embodiments, the vessel  104  can have a length:width aspect ratio in the range of about 1-3.5. In some embodiments, the vessel occupies a shape approximating a rectangular prism with rounded corners. In some embodiments, the mass of the vessel in various embodiments described herein can range from in the range of about 25 kg-110 kg. In some embodiments, the mass of the vessel can be in the range of about 35 kg-65 kg. Lower masses of vessels and/or trays allow for easier transportation, but higher masses can facilitate more uniform temperature distribution and a thermal flywheel effect to moderate fluctuations. 
       FIG. 6A  illustrates a top view of various porting recesses and other fluidic structures in various embodiments. In some embodiments, one or more porting recesses  626 ,  634 ,  642 ,  650 ,  658  can be milled into the housing base  480 . In certain configurations, the porting recesses  626 ,  634 ,  642 ,  650 ,  658  can be adapted to receive filters associated with corresponding valves  420 ,  424 ,  428 ,  432 ,  436 , shown in  FIG. 5 , which may be mechanically attached to the housing base  480 , as described herein. One or more vessel inlets  622 ,  630 , vessel outlets  646 ,  654 , and/or a vessel vent port  638  can be milled into the vessel housing  480 . In some configurations, the vessel vent port  638  can be configured to be in fluid communication with the vent valve  428  ( FIG. 5 ). In some embodiments, one or more trays  108 ,  112  can include one or more tray inlets  602 ,  606 , one or more tray outlets  614 ,  618 , and/or one or more tray vent channels  610 . 
     In some configurations, each of the trays  108 ,  112  can be configured to include a separate tray vent channel  610 . In some configurations, one or more tray vent channels  610  can be configured to permit gas flow into and/or out of the corresponding tray  108 ,  112 . In certain embodiments, each of the one or more tray vent channels  610  can be in fluid communication with the vessel vent port  638 , which in turn can be in fluid communication with the vent valve  428  ( FIG. 5 ). In some embodiments, the tray inlets  602 ,  606  can be configured to be in fluid communication with corresponding vessel inlets  622 ,  630 . Similarly, the tray outlets  614 ,  618  can be configured to be in fluid communication with corresponding vessel outlets  646 ,  654 . 
       FIG. 6B  illustrates the SSCV vessel  104  with the lid removed. As shown, the porting recesses  626 ,  634 ,  642 ,  650 ,  658  can be configured as described above. The vessel  104  can include one or more trays, but in  FIG. 6B  only the upper tray  108  is visible. In some embodiments, the one or more trays can each define a corresponding serpentine path  674 . Each serpentine path  674  can be adapted to hold solid source chemical and allow the flow of gas thereover. In some configurations, each serpentine path  674  can be milled and/or machined into the tray(s)  108 ,  112  ( FIG. 4 ), or the tray can be molded to have the serpentine path  674 . In some embodiments, the serpentine path(s)  674  can be milled out of a solid (e.g., cast) metal block. 
     In some embodiments, the serpentine path  674  can be in fluid communication with a corresponding tray inlet  602 ,  606 , a corresponding tray outlet  614 ,  618 , and/or a corresponding tray vent channel  610 . Each serpentine path  674  can be in fluid communication with a corresponding inlet valve,  420 ,  424 , a corresponding outlet valve  432 ,  436 , and/or a vent valve  428  as discussed with respect to  FIGS. 5 and 6A . The fluid configuration used to connect the serpentine path(s)  674  with one or more valves can be as described herein. 
     It will be appreciated that longer path lengths can increase a surface area of gas exposure of the solid source chemical. The serpentine path  674  for each tray  108 ,  112  can have a length in the range of about 2000 mm-8000 mm. In some embodiments, the serpentine path  674  can have a length in the range of about 3000 mm-5000 mm, and in the illustrated embodiment is about 3973 mm (156.4 inches). The total path length counting both trays  108 ,  112  can therefore be in the range of about 6000 mm-10000 mm, or about 7946 mm in the illustrate embodiment. 
     As will be appreciated by the skilled artisan, it may be advantageous to reduce the volume or footprint that multiple vapor sources would entail. Compact vessel assemblies can reduce such a footprint. In certain embodiments, each tray  108 ,  112  can have a height of between about 25 mm-50 mm. In certain configurations, each tray  108 ,  112  can have a height of between about 15 mm-30 mm. In some embodiments, each tray  108 ,  112  can have a height of between about 40 mm-80 mm. In some embodiments, a stack of trays can have a combined height of between about 50 mm-100 mm. In some embodiments, the stack of trays can have a combined height of between about 35 mm-60 mm. In some embodiments, a stack of trays can have a combined height of between about 85 mm-150 mm. 
     An ability to hold a large mass and/or volume of solid source chemical in the SSCV vessel can increase the time needed between recharging treatments. Moreover, this can allow for greater mass of sublimated solid source chemical in the same amount of time. Thus, in some embodiments the serpentine path(s)  674  can be adapted to hold in the range of about 750 g-2000 g of typical solid source chemical for vapor phase deposition, particularly inorganic solid source metal or semiconductor precursors, such as HfCl 4 , ZrCl 4 , AlCl 3 , or SiI 4 . In some embodiments the serpentine path(s)  674  can each be adapted to hold in the range of about 500 g-1200 g of solid source chemical. In some embodiments the two serpentine paths  674  of the SSCV vessel  105  can together be adapted to hold between about 1500 g-2000 g of solid source chemical. Longer path lengths and/or greater masses of solid source chemical that the trays can hold can lead to a greater amount of precursor to the deposition chambers in the same amount of time. In some cases, the longer path length and/or greater masses of solid source chemical can increase the amount of saturation that can be achieved in the same amount of time. In some embodiments, an elapsed time between two consecutive vapor processes (e.g., a pulse/purge length) can be between about 100 ms-3 s. In some embodiments, the elapsed time can be between about 30 ms-1.5 s. 
     The size of a vessel can be related to the amount of solid source chemical. For example, a ratio of a volume (in mm 3 ) enclosed by the vessel to the mass (in g) of solid source chemical it can hold can be in a range of about 2000-5000. In certain configurations, a ratio of the total path length (in mm) of all trays to a mass (in g) of the total amount of solid source chemical they can hold can be in a range of about 1-10. In some embodiments, a ratio of a volume (in mm 3 ) enclosed by the vessel to the total path length (in mm) of all trays can be in a range of about 400-1200. These ranges are determined in part by natural limitations placed on the vessel, the materials used, and space limitations. 
       FIG. 7  illustrates a cross-sectional side view of the first tray  108  in certain configurations, which can be similar to the second tray  112 . The serpentine path  674  of the tray  108  can have a recess height  704  and a recess width  708 . In some embodiments, the recess height  704  can be between about 10 mm-50 mm. In some embodiments, the recess height  704  can be between about 20 mm-40 mm. In some embodiments, the recess width  708  can be between about 3.0 mm-20 mm. In some embodiments, the recess width  708  can be between about 5 mm-8 mm. In some embodiments, the recess height  704  and recess width  708  can define a height:width aspect ratio of 3-7. In some embodiments, the recess height  704  and recess width  708  can define a height:width aspect ratio of between about 4.0-5.5. In the illustrated embodiment, the recess height is about 30 mm, the width is about 6.35 mm, and the ratio of height:width is about 4.7. As an example, about ⅔ of the height (e.g., around 19 mm to 22 mm) may be filled with solid precursor when initially filled, and the headroom above that fill height (e.g., around 8 mm to 11 mm) can be reserved as head space to facilitate collection of reactant vapor above the solid precursor, and allow carrier gas flow to pick up such vapor. 
     It may be advantageous to obtain increased mixing of the reactant with the carrier gas. In some embodiments, this is achieved by increasing the turbulence of the carrier gas within the flow paths. For example, some embodiments include structural features within one or more flow paths that create more turbulence compared to smooth gas flow paths and thus encourage mixing of the flowing carrier gas with the reactant vapor formed from vaporizing the solid reactant bed at the lower of the flow path(s)  674 . In certain configurations, the structures can be protrusions that extend horizontally from the vertical side walls of the recesses that define the serpentine paths  674 , particularly in the upper approximately ⅓ of the height reserved for inert gas flow when the lower ⅔ is filled with precursor. The middle ⅓ of the recess height may also include horizontal protrusions for additional turbulence when the bed of solid precursor is partially exhausted. The lower ⅓ of the recess can also include horizontal protrusions for better mixing when the solid precursor bed is almost exhausted but still in operations. The protrusions can include features directing carrier gas flow downwardly and/or upwardly to encourage to increase turbulence relative to smooth walls. Such protrusions can be adapted to promote vortices, such as, for example, horizontal slit arrays, hole arrays, and/or roll cells. The protrusions can be arranged horizontally or vertically. In some configurations, the combination of carrier gas flow rate and configuration of the structures for increasing turbulence can be tuned to increase mixing of carrier gas and reactant vapor without excessively stirring unevaporated reactant (e.g., powder) that can clog the filters. The carrier gas flow rates in some embodiments can range from about 500 sccm to 10 slm, preferably from about 1 slm to 3 slm. The size of any features described above within the flow path(s) may depend on the carrier gas flow rate. 
       FIG. 8  illustrates a cross-sectional side view of an example vessel  104  where a valve  802  is configured to be in fluid communication with a first tray  108 . The valve  802  of  FIG. 8  may represent an inlet valve or an outlet valve for communication with the first tray  108 . A filter  804  is adapted to prevent solid particulate matter from flowing therethrough. The filter material is configured to restrict the passage of particles greater than a certain size, for example about 0.003 μm. The material can comprise any of a variety of different materials, such as nickel fiber media, stainless steel, ceramics (e.g., alumina), quartz, or other materials typically incorporated in gas or liquid filters. 
     As shown in  FIG. 8 , a vessel inlet/outlet  808  can be in fluid communication with a tray inlet  812 . Thus, via the tray inlet  812 , the vessel inlet/outlet  808  can be in fluid communication with the first tray  108 , in certain embodiments. In certain configurations, the tray inlet/outlet  812  can correspond to one or more of the tray inlets or tray outlets  602 ,  606 ,  614 ,  618  as described herein with respect to  FIGS. 4-6B . Similarly, the vessel inlet/outlet  808  can correspond to one or more of the vessel inlets or vessel outlets  622 ,  360 ,  646 ,  654 , as described herein with respect to  FIGS. 4-6B . The valve  802  may represent one or more of the inlet valves and outlet valves  420 ,  424 ,  432 ,  436  as described herein with respect to  FIGS. 4-6B . 
       FIG. 9  illustrates a cross-sectional side view of an example vessel  104  where a valve  902  is configured to be in fluid communication with a second tray  112 . The valve  802  of  FIG. 8  may represent an inlet valve or an outlet valve for communication with the second tray  112 . A filter  904  can be similar to that described above. As shown, a vessel inlet/outlet point  908  can be in fluid communication with a tray inlet/outlet  912 . Thus, via the tray inlet/outlet  912 , the vessel inlet/outlet  908  can be in fluid communication with the second tray  112 , in certain embodiments. In certain configurations, the tray inlet/outlet  912  can correspond to any of the tray inlets or tray outlets  602 ,  606 ,  614 ,  618  as described herein with respect to  FIGS. 4-6B . Similarly, the vessel inlet/outlet  908  can correspond to any of the vessel inlets or vessel outlets  622 ,  360 ,  646 ,  654 , as described herein with respect to  FIGS. 4-6B . The valve  902  may represent any of the inlet valves or outlet valves  420 ,  424 ,  432 ,  436  as described herein with respect to  FIGS. 4-6B . 
       FIG. 10  illustrates a cross-sectional side view of some embodiments of a vessel  104  where a valve  1002  is configured to be in fluid communication with both the first tray  108  and the second tray  112 . In one embodiment, the valve  1002  of  FIG. 10  may represent the vent valve  428  ( FIG. 5 ) for venting inert gas overpressure that is provided with recharged vessels for movement with minimal disturbance of the solid precursor. As shown, a gas can selectively pass through piping  1034 , the valve  1002  and piping  1028 . In an embodiment where the valve  1002  is a vent valve, the piping  1028  can lead directly or indirectly to vent or a vacuum pump. The vessel can be configured to permit a gas to pass through a filter  1004 . As shown, a vessel inlet/outlet  1008  can be in fluid communication with both a first tray inlet/outlet  1012  and a second tray inlet/outlet  1016 . Thus, in some embodiments, via the first tray inlet/outlet  1012  and/or the second tray inlet/outlet  1016 , the vessel inlet/outlet  1008  can be in fluid communication with the respective first tray  108  and/or second tray  112 . In some embodiments, the filter  1004  can share one or more properties of the filter  804  as discussed above. In certain configurations, one or more of the tray inlets/outlets  1012 ,  1016  can correspond to the tray vent channels  610 , as described above with respect to  FIG. 6A . Similarly, the vessel inlet/outlet  1008  can correspond to one or more of the vessel vent port(s)  638 , as described above with respect to  FIG. 6A . The valve  1002  may represent the vent valve  428  as described above. 
       FIG. 11  shows an example of how a solid source chemical vaporizer (SSCV) vessel can be incorporated into a solid source assembly  1350 . A solid source assembly  1350  can include the SSCV vessel  104 , which can include the housing lid  113  and housing base  480  as described above. In some embodiments, a solid source assembly  1350  can include one or more heating elements  1102 ,  1106 ,  1110 . In some embodiments, one or more of the heating elements can serve as a first vessel heater  1102  and be disposed vertically adjacent or vertically proximate the SSCV vessel  104 . In some embodiments, the first vessel heater  1102  is configured to heat the vessel  104  by conduction. In certain embodiments, the first vessel heater  1102  is a heater plate that is disposed below the housing of the SSCV vessel  104 . In certain embodiments, a second vessel heater  1110  can be disposed above the housing lid  113 . In some embodiments, the second vessel heater  1110  is disposed above one or more valves  420 ,  424 ,  428 ,  432 ,  436  and is configured to radiantly heat one or more valves and the SSCV vessel  104  in the solid source assembly  1350 . In certain configurations, a valve plate heater  1106  can be disposed above a valve plate  1112 , which supports valves for distribution of vapors received from the SSCV vessel  104 . In some embodiments, one or more hot feed throughs can be included in the walls of the solid source assembly  1350  to provide a heated path for gas to leave the solid source assembly  1350 . The cabinet of the solid source assembly  1350  maybe be gas tight to allow pumping down to low pressures, such as between about 0.1 Torr and 20 Torr, e.g., about 5 Torr, and thus facilitate efficient radiant heating minimal conductive or convective losses to the atmosphere within the cabinet. 
     In some embodiments, the first vessel heater  1102  and the second vessel heater  1110  are adapted to heat the vessel housing (lid  113  and base  408 ) to an operating temperature. In some embodiments, the operating temperature is in the range of about 50° C.-250° C. The selected operating temperature may depend, of course, upon the chemical to be vaporized. For example, the operating temperature may be about 160° C.-240° C., particularly about 170° C.-190° C. for HfCl 4 ; about 170° C.-250° C., particularly about 180° C.-200° C. for ZrCl 4 ; about 90° C.-110° C. for Al 2 Cl 3 ; about 90° C.-120° C. for SiI 4 . The skilled artisan will readily appreciate other temperatures may be selected for other source chemicals. In certain embodiments, the valve plate  1112  is adapted to be heated to a temperature in the range of about 110° C.-240° C. In some embodiments, the one or more deposition chambers  312 ,  316  are adapted to be heated to a temperature in the range of about 160° C.-280° C. for HfO and ZrO deposition processes. The temperatures may be kept higher at the valve plate  1112  and the deposition chambers  312 ,  316  ( FIG. 12 ), compared to the temperature of the SSCV vessel  104 , to minimize risk of condensation upstream of the substrate in the deposition chambers  312 ,  316 , while still remaining below decomposition temperatures. 
       FIG. 12  shows a diagram of some embodiments of a multi-chamber deposition module  1200 . In some embodiments, a solid source assembly  1350  can house a SSCV vessel (not shown), which may be heated within the solid source assembly  1350  as discussed above to vaporize solid chemical source and deliver vapor reactant alternately or simultaneously to the deposition chamber  312  and  316 .  FIG. 12  illustrates how the solid source assembly  1350 , despite incorporating a relatively large footprint SSCV vessel (e.g., 450 mm lateral dimension), fits within the footprint and vertical headroom of a dual chamber module, and yet delivers higher mass flow of vaporized reactant than prior vessels. 
       FIG. 13  illustrates a schematic fluid-flow diagram of an example multiple chamber deposition module  1300 , similar to that of  FIG. 12 . A flow of an inert gas (e.g., nitrogen) can enter the module  1300  at an entry point  1302 . In some embodiments, the flow of gas can be controlled using valves  1310   a ,  1310   b . If the gas is directed through the valve  1310   a , it can pass through a downstream pressure controller  1314   a , which can modulate the pressure in conjunction with control valves leading to a vacuum pump  1318 . Inert gas flow can enter the solid source assembly  1350  and be further controlled by valves  1336 ,  1337 . The flow of gas can be controlled so as to allow gas flow through the valve  1336  and into the solid source chemical vaporizer (SSCV) vessel  104 . In some embodiments, gas can flow into one or more of inlet valves  420 ,  424  and into one or more corresponding trays (not shown) in the housing. After flowing through the serpentine flow paths above solid reactant beds and picking up reactant vapor, carrier gas flow can continue out of the housing via one or more outlet valves  432 ,  436 . One or more valves  1338 ,  1339 ,  1334  can control the flow of the reactant vapor en route to the deposition chambers  312 ,  316 . Additional valves  1340 ,  1342  can control flow from the system to vent or vacuum. In some embodiments, the valve  1334  can control whether the gas flow continues through a separation point  332  and into one or more deposition chambers  312 ,  316 . In some embodiments, the separation point  332  can include one or more valves to further manage the flow of gas into the one or more deposition chambers. The deposition chambers  312 ,  316  can be fed gas using respective showerheads (not shown) for each chamber. A plurality of the valves  1336 - 1342  may be mounted on the separately heated valve plate  1112  ( FIG. 11 ) over the SSCV vessel  104  and within the solid source assembly  1350 , as explained above. 
     In some cases, gas flow may be directed to vent or vacuum through valves  1340 ,  1342 . For example, such flow may be established to vent prior to stabilizing the flow and sending the flow to the reaction chambers In some embodiments, a vacuum pump  1318  can be used to create a vacuum pressure in order to help drive the flow of gas. In some embodiments, the vent valve  428  can also be in fluid communication with the vent or vacuum through the valve  1342 ; with one or more trays in the housing base  480  such that gas can be removed therefrom via the vent valve  428 . 
     In some variations, the module  1300  can be configured to allow gas to flow through the valve  1310   b  and a downstream pressure controller  1314   b , which can regulate pressure within the solid source assembly  1350  when the valve  1310  is open to the vacuum pump  1330  Inert gas can be vented to the vacuum pump  1330 , e.g. when removing the SSCV vessel  104  for recharging with solid source chemical. In certain embodiments, a pressure relief valve  1326  can be used to relieve pressure from the solid source chamber  1350  if the internal pressure exceeds a threshold pressure (e.g., 1.5 psig) when the chamber is backfilled to atmospheric pressure, e.g., for maintenance or for replacing an exhausted SSCV vessel  104  with a recharged vessel. Maintaining low pressures (e.g., 0.1 Torr to 20 Torr, particularly about 5 Torr) within the solid source assembly  1350  during operation can facilitate radiant heating with minimal conductive/convective losses to the air or gas surrounding the heated components. An exit point  1306  can be arranged to supply inert gas to other systems (e.g., to the deposition chamber for purging or as a carrier gas to other chemical sources). 
       FIG. 14  schematically illustrates the solid source assembly  1350  of  FIG. 11 . In some embodiments, the valve plate heater  1106  is configured to heat the valve plate  1112  and associated valves  1334 ,  1338 ,  1339 ,  1340 . In some embodiments, the valve plate heater  1106  is configured and positioned to heat the valve plate  1112  using radiant heat. In some embodiments, the vessel heater  1110  is configured to heat a solid source chemical vaporizer (SSCV) vessel  104  and its associated valves  420 ,  424 ,  428 ,  432 ,  436 . In some embodiments, the second vessel heater  1110  is configured to heat the SSCV vessel  104  using radiant heat. In some embodiments, first vessel heater  1102  can be disposed below the housing base  480 . In some configurations, the first vessel heater  1102  is configured to heat the housing base  480  by conduction. 
     With continued reference to  FIG. 14 , gas can flow from the SSCV vessel  104  to the valve plate  1112  as shown. In some embodiments, the gas can be directed to one or more hot feed throughs  1412 ,  1416  via feed ports  1428 ,  1432 . Some embodiments are configured such that gas flow can be directed from the one or more hot feed throughs  1412 ,  1416  to one or more deposition chambers (not shown). 
     In some embodiments, the solid source assembly (as disclosed herein) can operate at a target vacuum pressure. In some embodiments, the target vacuum pressure can be in the range of about 0.5 Torr-20 Torr, such as 5 Torr. In certain embodiments, the vacuum pressure in the solid source assembly can be regulated using one or more pressure controllers. 
     In some embodiments, the vent valve  428  can be used to vent off pressurized inert gas from one or more trays and/or one or more valves in the systems and/or methods described herein. 
     In a typical SSCV arrangement, carrier gas flows through the SSCV vessel  104  (e.g., above the solid chemical bed in the serpentine path  674 ). However, in other embodiments, a precursor vapor can be drawn out of the vessel by an external gas flow that creates a lower pressure outside of the vessel, as in a Venturi effect. For example, the precursor vapor can be drawn by flowing a carrier gas toward the one or more deposition chambers  312 ,  316  along a path downstream of the vessel. Under some conditions, this can create a pressure differential between the vessel and the flow path of the carrier gas. This pressure differential causes the precursor vapor within the SSCV vessel  104  to flow toward the one or more reaction chambers  312 ,  316 . 
     In the foregoing specification, the invention has been described with reference to specific embodiments thereof. It will, however, be evident that various modifications and changes may be made thereto without departing from the broader spirit and scope of the invention. The specification and drawings are, accordingly, to be regarded in an illustrative rather than restrictive sense. 
     Indeed, it will be appreciated that the systems and methods of the disclosure each have several innovative aspects, no single one of which is solely responsible or required for the desirable attributes disclosed herein. The various features and processes described above may be used independently of one another, or may be combined in various ways. All possible combinations and subcombinations are intended to fall within the scope of this disclosure. 
     Certain features that are described in this specification in the context of separate embodiments also may be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment also may be implemented in multiple embodiments separately or in any suitable subcombination. Moreover, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination may in some cases be excised from the combination, and the claimed combination may be directed to a subcombination or variation of a subcombination. No single feature or group of features is necessary or indispensable to each and every embodiment. 
     It will be appreciated that conditional language used herein, such as, among others, “can,” “could,” “might,” “may,” “e.g.,” and the like, unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain embodiments include, while other embodiments do not include, certain features, elements and/or steps. Thus, such conditional language is not generally intended to imply that features, elements and/or steps are in any way required for one or more embodiments or that one or more embodiments necessarily include logic for deciding, with or without author input or prompting, whether these features, elements and/or steps are included or are to be performed in any particular embodiment. The terms “comprising,” “including,” “having,” and the like are synonymous and are used inclusively, in an open-ended fashion, and do not exclude additional elements, features, acts, operations, and so forth. Also, the term “or” is used in its inclusive sense (and not in its exclusive sense) so that when used, for example, to connect a list of elements, the term “or” means one, some, or all of the elements in the list. In addition, the articles “a,” “an,” and “the” as used in this application and the appended claims are to be construed to mean “one or more” or “at least one” unless specified otherwise. Similarly, while operations may be depicted in the drawings in a particular order, it is to be recognized that such operations need not be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. Further, the drawings may schematically depict one more example processes in the form of a flowchart. However, other operations that are not depicted may be incorporated in the example methods and processes that are schematically illustrated. For example, one or more additional operations may be performed before, after, simultaneously, or between any of the illustrated operations. Additionally, the operations may be rearranged or reordered in other embodiments. In certain circumstances, multitasking and parallel processing may be advantageous. Moreover, the separation of various system components in the embodiments described above should not be understood as requiring such separation in all embodiments, and it should be understood that the described program components and systems may generally be integrated together in a single software product or packaged into multiple software products. Additionally, other embodiments are within the scope of the following claims. In some cases, the actions recited in the claims may be performed in a different order and still achieve desirable results. 
     Accordingly, the claims are not intended to be limited to the embodiments shown herein, but are to be accorded the widest scope consistent with this disclosure, the principles and the novel features disclosed herein. For example, although many examples within this disclosure are provided with respect to supplying vapor from solid sources for feeding deposition chambers for semiconductor fabrication, certain embodiments described herein may be implemented for a wide variety of other applications and/or in numerous other contexts.