Patent Publication Number: US-11387120-B2

Title: Chemical dispensing apparatus and methods for dispensing a chemical to a reaction chamber

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation and claims priority to U.S. patent application Ser. No. 15/719,208 filed Sep. 28, 2017 titled CHEMICAL DISPENSING APPARATUS AND METHODS FOR DISPENSING A CHEMICAL TO A REACTION CHAMBER, the disclosure of which is hereby incorporated by reference in its entirety. 
    
    
     FIELD OF INVENTION 
     The present disclosure relates generally to a chemical dispensing apparatus and to methods for dispensing a chemical to a reaction chamber. The disclosure is particularly related to the storage and conversation of a chlorine-containing species to a chlorine vapor for use in a reaction chamber. 
     BACKGROUND OF THE DISCLOSURE 
     Some semiconductor fabrication processes utilized in the manufacture of semiconductor device structures may utilize highly corrosive and highly toxic chemical species. Such hazardous chemical species may require complex safety protocols associated with the proper procedures for safe storage, handling and disposal. 
     A non-limiting example of a toxic chemical species commonly used in a semiconductor fabrication process is that of chlorine (Cl 2 ) vapor. For example, chlorine vapor may be utilized in cleaning processes, etching processes and deposition processes, wherein each semiconductor process requires specialized storage, handling and disposal of the chlorine vapor and any chlorine based reaction byproducts. It is well known that chlorine vapor is extremely corrosive and therefore storage and particularly long term stable storage may require specialist corrosion resistant storage vessels and purity monitoring procedures. In addition, chlorine vapor is a highly toxic gas that attacks both the respiratory system, as well as eyes and skin. Accordingly, apparatus and methods are desirable that may utilize alternative chemical species to chlorine vapor in the manufacture of semiconductor device structures. 
     SUMMARY OF THE DISCLOSURE 
     This summary is provided to introduce a selection of concepts in a simplified form. These concepts are described in further detail in the detailed description of example embodiments of the disclosure below. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. 
     In some embodiments, a chemical dispensing apparatus for providing a chlorine vapor to a reaction chamber is provided. The apparatus may comprise: a chemical storage vessel configured for storing a chlorine-containing chemical species, a reservoir vessel in fluid communication with the chemical storage vessel, the reservoir vessel configured for converting the chlorine-containing chemical species to the chlorine vapor; and a reaction chamber in fluid communication with the reservoir vessel. 
     The embodiments of the disclosure may also provide methods for supplying a chlorine vapor to a reaction chamber. The methods may include: providing a chemical storage vessel, the chemical storage vessel containing a chlorine-containing chemical species, flowing the chlorine-containing chemical species from the chemical storage vessel to a reservoir vessel, converting the chlorine-containing chemical species into the chlorine vapor inside the reservoir vessel, and controllably flowing the chlorine vapor into the reaction chamber. 
     For purposes of summarizing the invention and the advantages achieved over the prior art, certain objects and advantages of the invention have been described herein above. Of course, it is to be understood that not necessarily all such objects or advantages may be achieved in accordance with any particular embodiment of the invention. Thus, for example, those skilled in the art will recognize that the invention may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught or suggested herein without necessarily achieving other objects or advantages as may be taught or suggested herein. 
     All of these embodiments are intended to be within the scope of the invention herein disclosed. These and other embodiments will become readily apparent to those skilled in the art from the following detailed description of certain embodiments having reference to the attached figures, the invention not being limited to any particular embodiment(s) disclosed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING FIGURES 
       While the specification concludes with claims particularly pointing out and distinctly claiming what are regarded as embodiments of the invention, the advantages of embodiments of the disclosure may be more readily ascertained from the description of certain examples of the embodiments of the disclosure when read in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a schematic diagram of a chemical delivery apparatus for providing a chlorine vapor to a reaction chamber according to the embodiments of the disclosure; 
         FIG. 2  is a process flow diagram for an exemplary method for dispensing a chemical to a reaction chamber according to embodiments of the disclosure. 
     
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     Although certain embodiments and examples are disclosed below, it will be understood by those in the art that the invention extends beyond the specifically disclosed embodiments and/or uses of the invention and obvious modifications and equivalents thereof. Thus, it is intended that the scope of the invention disclosed should not be limited by the particular disclosed embodiments described below. 
     The illustrations presented herein are not meant to be actual views of any particular material, structure, or device, but are merely idealized representations that are used to describe embodiments of the disclosure. 
     As used herein, the term “substrate” may refer to any underlying material or materials that may be used, or upon which, a device, a circuit or a film may be formed. 
     As used herein, the term “chlorine-containing chemical species” may refer to any chemical species including a chlorine (Cl) component, excluding chlorine vapor itself. 
     The embodiments of the disclosure may include apparatus and methods for dispensing a chlorine vapor to a reaction chamber of a semiconductor processing apparatus. The embodiments of the disclosure substitute pure chlorine vapor with one or more chlorine-containing chemical species which may be less corrosive and less toxic than pure chlorine vapor. Therefore, the chemical dispensing apparatus and methods of the embodiments of the disclosure do not require as stringent corrosion and safety protocols, increasing semiconductor device fabrication efficiency and safety. 
     The embodiments of the disclosure may be understood in more detail with reference to  FIG. 1  which illustrates a semiconductor apparatus comprising, a chemical dispensing apparatus for a reaction chamber. In some embodiments of the disclosure, the apparatus  100  comprises; chemical storage vessel  102  which may be configured for storing a chlorine-containing chemical species  103 , a reservoir vessel  104  in fluid communication with the chemical storage vessel  102 , the reservoir vessel  104  configured for converting the chlorine-containing chemical species into the chlorine vapor, and a reaction chamber  106  in fluid communication with the reservoir vessel  104 . 
     It should be noted that the chemical dispensing apparatus  100  as illustrated in  FIG. 1  is a simplified schematic version of the chemical dispensing apparatus of the current disclosure and does not contain each and every element, i.e., such as each and every valve, particle filter, seal and gas line that may be utilized in the fabrication of the chemical dispensing apparatus of the current disclosure. The chemical dispensing apparatus  100  as illustrated in  FIG. 1  provides the key features of the chemical dispensing apparatus which provides sufficient disclosure to one skilled in the art to appreciate the embodiments of the current disclosure. 
     In more detail, apparatus  100  may comprise a chemical storage vessel  102  which may be configured for storing a chlorine-containing chemical species  103 . In some embodiments of the disclosure, the chlorine-containing chemical species  103  to be stored in the chemical storage vessel  102  may be in the form of a solid, a liquid, or a gas. In some embodiments, the chlorine-containing chemical species  103  to be stored in chemical vessel  102  may be less hazardous, less toxic and/or less corrosive than pure chlorine vapor. However, the chlorine-containing chemical species  103  may still require careful handling and storage even if the chemical species is less hazardous compared with pure chlorine vapor. 
     In some embodiments of the disclosure, the chemical storage vessel  102  may comprise a quartz material, i.e., the chemical storage vessel may be substantially fabricated from a quartz material, which is substantially chemically inert to the chlorine-containing chemical species  103  to be stored in the chemical storage vessel  102 . In alternative embodiments of the disclosure, the chemical storage vessel  102  may be fabricated from a corrosion resistant metal or metal alloy, such as, for example, Hastelloy, Monel, or a combination thereof. 
     In some embodiments of the disclosure, the chemical storage vessel  102  may comprise an inner surface  105  in contact with the chlorine-containing chemical species  103 . Due to the direct contact between the inner surface  105  of the chemical storage vessel  102  and the chlorine-containing chemical species  103 , the inner surface  105  of the vessel may comprise a corrosion resistant coating which provides a corrosion resistant surface to the chemical storage vessel, i.e., the corrosion resistant coating is provide on the inner surface of the chemical storage vessel  102  such that the chlorine-containing chemical species is in direct contact with the corrosion resistant coating and not in direct contact with the quartz/metal surface of the chemical storage vessel. 
     In some embodiments of the disclosure, the corrosion resistant coating on inner surface  105  may comprise a fluorine based corrosion resistance coating. For example, the fluorine based corrosion resistant coating may comprise one or more of polytetrafluoroethylene (PTFE), fluorinated ethylene propylene copolymer (FEP), perfluoroalkoxy (PFA), polyethylene terephthalate copolymer (PETG) or a polyamide based copolymer. 
     In addition to the inner surface of the chemical storage vessel being coated with a corrosion resistant coating, in some embodiments of the disclosure, all the vapor passageways, i.e., the gas pipelines, between the various components of the apparatus  100  may be configured such that they are corrosion resistant to the chlorine-containing chemical species stored in the chemical storage vessel  102  and corrosion resistant to any reaction byproducts that may be produced during the conversion of the chlorine-containing chemical species into a chlorine vapor. For example, the vapor passageways, valves, connectors, seals, mass flow units and particular all regions of the apparatus  100  which may be in contact with one or more corrosive species, may all be fabricated from corrosion resistant materials including Hastelloy, Monel, nickel-based alloys, tantalum, a tantalum-based alloy, silicon carbide, boron nitride, boron carbide, aluminum nitride, fused silica, bonded amorphous silicon and other known chlorine resistant materials. In addition, the portions of chemical dispensing apparatus  100  which may be wetted by the chlorine-containing chemical species or reaction byproducts, may be coated with a fluorine based corrosion resistant liner, including, but not limited to, polytetrafluoroethylene (PTFE), fluorinated ethylene propylene copolymer (FEP) or perfluoroalkoxy (PFA). 
     In some embodiments of the disclosure, the chemical storage vessel  102  may further comprise one or more heating units  112  configured for heating the chlorine-containing chemical species  103  stored in the chemical storage vessel  102 . In some embodiments of the disclosure the one or more heating units  112  may be utilized to heat the chlorine-containing chemical species  103  to a temperature of approximately greater than 0° C., or approximately greater than 20° C., or approximately greater than 100° C., or approximately greater than 150° C., or approximately greater than 200° C., or approximately greater than 200° C., or approximately greater than 300° C., or even approximately greater than 400° C. 
     In some embodiments, the one or more heating units  112  associated with the chemical storage vessel  102  are configured for converting the chlorine-containing chemical species from a solid to either a liquid or a gas. In some embodiments, the one or more heating units  112  associated with the chemical storage vessel  102  may be utilized to control the viscosity of the chlorine-containing chemical species stored in the chemical storage vessel  102 . 
     In more detail, a vapor passageway  108  may be connected to the chemical storage vessel  102  such that one or more carrier gases may be transported from a carrier gas storage vessel (not shown) into the chemical storage vessel  102  via vapor passageway  108 . A mass flow controller  107  may be placed on the vapor passageway  108  and disposed proximate to the chemical storage vessel  102 . For example, the mass flow controller  107  may be calibrated to control the mass flux of the carrier gas entering the chemical storage vessel  102  thereby allowing greater control over the subsequent flow of the chlorine-containing chemical species  103 . 
     The carrier gas (e.g., hydrogen, nitrogen, helium, argon and mixtures thereof) may be flowed over an exposed surface of the chlorine-containing chemical species  103 , thereby picking up a portion of the chlorine-containing chemical species  103  and transporting the chlorine-containing chemical species, along with the carrier gas, to a desired location in the apparatus  100 . In alternative embodiments of the disclosure, the carrier gas may be “bubbled” though the chlorine-containing chemical species  103 , e.g., by optional vapor passageway  108 ′, thereby agitating and picking up a portion of the chlorine-containing chemical species and transporting the chlorine-containing chemical species, along with the carrier gas, to a desired location in the apparatus  100 . For example, in some embodiments the chlorine-containing chemical species  103  may comprise a highly viscous fluid which is not suitable for vapor transport by bubbling a carrier gas through the chlorine-containing chemical species. Therefore, in some embodiments of the disclosure, the one or more heating units  112  associated with the chemical storage vessel  102  are utilized to decrease the viscosity of the chlorine-containing chemical species  103  making it more suitable for bubbling a carrier gas through the chlorine-containing chemical species  103  for species transport to additional portions of the apparatus  100 . 
     In some embodiments of the disclosure, the chlorine-containing chemical species  103  may comprise a solid, a liquid, or a gas. In some embodiments, the chlorine-containing chemical species  103  may comprise a solid. In some embodiments, the chlorine-containing chemical species  103  may comprise a liquid. In some embodiments, the chlorine-containing chemical species  103  stored in the chemical storage vessel  102  may comprise, non-metal or semi-metal chlorides, such as at least one of S 2 Cl 2 , Se 2 Cl 2 , SCl 2 , SCl, PCl 5 , SeCl 4 , SeCl 2 , SiCl 4 , SbCl 3 , SbCl 5 , BCl 3 , SOCl 2 , SeO 2 Cl 2 , SO 2 Cl 2 , or SeOCl 2 . In some embodiments, the chlorine-containing chemical species may comprise carbon and chlorine atoms, such as, for example, CCl 4  or C 2 Cl 6 . In some embodiments, the chlorine-containing chemical species may comprise substituted or unsubstituted alkyl as well as aryl poly-acyl halides, such as, for example, succinyl chloride, malonyl chloride, fumaryl chlorie, methylenesiccinic acid chloride, glutaryl chloride, or oxalyl chloride. In some embodiments, the chloride-containing chemical species may comprise metal oxy halides, such as, for example, TiOCl 2 , NbOCl 3 , MoOCl 4 , WOCl 4 , or ReO 2 Cl 3 . In some embodiments, the chlorine-containing chemical species may comprise an interhalogen having the general formula X a Y b , such as, for example, ClF, BrCl, ClF 3 , ClF 5 , ICl 3  or ICl. In some embodiments, the chlorine-containing chemical species may comprise an Oxyhalide having the general formula O b X a  and O b X a Y c , such as, for example, FClO 2 , FClO 3 , or perchlorates (e.g., Cl 2 O). In some embodiments, the chlorine-containing chemical species may comprise Fumaryl chloride (C 2 H 2 C 2 O 2 Cl 2 ). In some embodiments, the chlorine-containing chemical species may comprise a chloronitrate. In some embodiments, the chlorine-containing chemical species does not comprise a metal. In some embodiments, the chlorine-containing chemical species does not comprise a semi-metal. In some embodiments, the chlorine-containing chemical species  103  stored in the chemical storage vessel  102  may comprise a substituted or unsubstituted alkyl Sulfenyl chloride, including, but not limited to, trichloromethanesulfenyl chloride or chlorocarbonylsulfenyl. In some embodiments, the chlorine-containing chemical species  103  stored in the chemical storage vessel  102  may comprise a substituted or unsubstituted alkyl Sulfonyl chloride, such as, but not limited to, trichloromethanesulfonyl chloride. 
     In some embodiments of the disclosure, at least a portion of the chlorine-containing chemical species is transported directly from the chemical storage vessel  102  to the reaction chamber  106  via vapor passageway  110 . In such embodiments, the chlorine-containing chemical species bypasses the reservoir vessel  104  and is transported directly to the reaction chamber  106  via vapor passageway  110 . In such embodiments, valve  109 A on vapor passageway  110  may be at least partially open to allow flow of the chlorine-containing chemical species directly to the reaction chamber  106 . 
     In embodiments wherein the chlorine containing chemical species is dispensed directly from the chemical storage vessel  102  to the reaction chamber  106 , the chlorine-containing chemical species may be in a gaseous form or may be converted into a gaseous form by utilizing the one or more heating units  112  associated with the chemical storage vessel  102 . In some embodiments, the vapor passageway  110  may include a mass flow controller  114  disposed along the vapor passageway  110  prior to entry into the reaction chamber  106 . In some embodiments, the mass flow controller  114  may be calibrated for the specific chlorine-containing chemical species present in the chemical storage vessel  102  such that the mass flow controller  114  may control the mass flux of the chlorine-containing chemical species into the reaction chamber  106 . 
     In some embodiments of the disclosure, at least a portion of the chlorine-containing chemical species is transported, along with any carrier gas, to the reservoir vessel  104  via vapor passageway  114 . For example, valve  109 B may be at least partially open to allow vapor flow from the chemical storage vessel  102  to the reservoir vessel  104 . In such embodiments, the chlorine-containing chemical species may undergo a conversion process within the reservoir vessel  104 , wherein the conversion process converts the chlorine-containing chemical species into chlorine (Cl 2 ) vapor. 
     In some embodiments of the disclosure, the reservoir vessel  104  may comprise a quartz material, i.e., the reservoir vessel  104  may be substantially fabricated from a quartz material. In alternative embodiments, the reservoir vessel  104  may be fabricated from a corrosion resistant metal or metal alloy, such as, for example, Hastelloy, Monel, or a combination thereof. 
     In some embodiments of the disclosure, the chlorine-containing chemical species may undergo a decomposition process within the reservoir vessel  104 . In other embodiments of the disclosure, the chlorine-containing chemical species may undergo a chemical reaction with a suitable chemical reagent within the reservoir vessel  104 . In some embodiments, the reaction between chlorine-containing chemical species and a suitable chemical reagent may be activated by radiation and/or electrical means. 
     In some embodiments of the disclosure, the chlorine-containing chemical species may decompose within the reservoir vessel  104  thereby forming a chlorine (Cl 2 ) vapor and one or more decomposition byproducts. In some embodiments, one or more heating units  116  may be associated with the reservoir vessel  104 . In some embodiments, one or more energy units, such as, for example, electrical, or radiation sources may be associated with the reservoir vessel  104 . For example, the one or more heating units  116  associated with the reservoir vessel  104  may be disposed external to the reservoir vessel  104  (as shown in  FIG. 1 ), or in alternative embodiments, the one or more heating units may be disposed within the reservoir vessel  104  (not shown). The one or more heating  116  (or alternative energy units, such as, for example, radiation or electrical units) associated with the reservoir vessel  104  may be utilized to decompose the chlorine-containing chemical species into a chlorine vapor and one or more decomposition byproducts. For example, in some embodiments of the disclosure, the one or more heating units  116  associated with the reservoir vessel  104  may be utilized to heat the chlorine-containing chemical species within the reservoir vessel  104 . In some embodiments of the disclosure, the one or more heating units  116  associated with the reservoir vessel  104  may be configured for heating the chlorine-containing chemical species to a temperature greater than approximately 0° C., or greater than approximately 20° C., or greater than approximately 100° C., or greater than approximately 150° C., or greater than approximately 200° C., or greater than approximately 300° C., or even greater than approximately 400° C. In some embodiments, the one or more heating units  116  associated with the reservoir vessel  104  may heat the chlorine-containing chemical species to a temperature beyond which the chlorine-containing chemical species thermally decomposes into a chlorine (Cl 2 ) vapor and one or more decomposition byproduct. 
     In some embodiments of the disclosure, the decomposition of the chlorine-containing chemical species may result in the formation of chlorine (Cl 2 ) vapor and one or more decomposition byproducts. In some embodiments of the disclosure, the reservoir vessel  104  may include a means for separation of the chlorine (Cl 2 ) vapor from the one or more decomposition products, such that only chlorine vapor is transported to the reaction chamber  106 . For example, in some embodiments the chlorine-containing chemical species may comprise SO 2 Cl 2  and upon heating to a temperature greater than 80° C. utilizing the one or more heating units  116 , the chlorine-containing chemical species may decompose forming chlorine vapor and a decomposition product comprising SO 2 . In some embodiments of the disclosure, the decomposition byproduct may be selectively separated from the chlorine vapor utilizing nickel (Ni) powder or other catalytically activated surfaces, such that only chlorine vapor is dispensed to the reaction chamber  106 . 
     As previously stated, in some embodiments of the disclosure, the decomposition of the chlorine chemical species may result in the formation of chlorine vapor and one or more decomposition byproducts. In some embodiments, the decomposition byproducts may be utilized in the reaction chamber  106 , i.e., the one or more decomposition byproducts may be utilized by processes run in the reaction chamber  106 . Therefore, in some embodiments of the disclosure, the one or more decomposition byproducts produced during the decomposition of the chlorine-containing chemical species are transported to the reaction chamber  106 . 
     In some embodiments of the disclosure, the reservoir vessel  104  may include a receptacle  118  for holding a chemical reagent  120 . In some embodiments, the reservoir vessel  104  may be fluidly connected via additional vapor passageways (not shown) to allow further chemical reagents, such as, for example, oxygen containing regents (e.g., O 2 , O 3 , or H 2 O), to enter the reservoir vessel  104  for reaction with the chlorine-containing chemical species. In some embodiments of the disclosure, the chemical reagent  120  may be selected to react with the chlorine-containing chemical species to produce a chlorine (Cl 2 ) vapor and one or more reaction byproducts. For example, a chlorine-containing chemical species may flow from chemical storage vessel  102  into reservoir vessel  104  via vapor passageway  114 , whereupon the chlorine-containing chemical species may react with the chemical reagent  120  held within receptacle  118 . The reaction between the chlorine-containing chemical species and the chemical reagent  120  may result in the formation of chlorine (Cl 2 ) vapor, which may be transported to the reaction chamber  106 , and one or more reaction byproducts. In some embodiments of the disclosure, the one or more reaction byproducts remain held in the receptacle  118 , whereas in other embodiments the one or more reaction by products may be transferred to the reaction chamber  106  for utilization in a semiconductor fabrication process. 
     In some embodiments of the disclosure, reservoir vessel  104  may include a means for separation of the chlorine vapor from the one or more reaction products produced by the reaction between the chlorine-containing chemical species and the chemical reagent  120 . As a non-limiting example embodiment, the chemical reagent  120  may comprise manganese oxide (MnO 2 ) and the chlorine-containing chemical species may comprise hydrochloric acid (HCl). As the HCl is passed over the MnO 2  a chlorine vapor may be produced along with a reaction byproduct comprising a non-volatile MnCl 2  hydrate powder which may be retained within the receptacle  118 . In some embodiments of the disclosure, the chemical reagent  120  may comprise a solid or a vapor and may include at least one of an oxygen containing reagent (e.g., O 2 , H 2 O, or O 3 ), a transition metal (e.g., nickel (Ni), or manganese (Mn)), lithium (Li), aluminum (Al)), or a metal oxide (e.g., Al 2 O 3  or MnO 2 ). 
     In some embodiments of the disclosure, the reaction between the chlorine-containing chemical species and the chemical reagent  120  may take place at an elevated temperature. For example, the one or more heating units  116  associated with reservoir vessel  104  may be utilized to heat the chemical reagent  120  prior to reaction with the chlorine-containing chemical species. As a non-limiting example embodiment, the chemical reagent  120  may be heated within the reservoir vessel  104  to a temperature greater than approximately 0° C., or greater than approximately 20° C., or even greater than approximately 100° C. In some embodiments of the disclosure, alternative energy units may be associated with the reservoir vessel  104 , such that the reaction between the chlorine-containing chemical species and the chemical reagent may be promoted via the alternative energy units, such as, for example, electric energy units or radiation energy units. 
     In some embodiments of the disclosure, the chlorine vapor produced in the reservoir vessel  104  may be transported directly to the reaction chamber  106  for use in a semiconductor fabrication process; in other words, the chlorine vapor produced in the reservoir vessel  104  may be utilized immediately in the reaction chamber  106 . In such embodiments, the chlorine vapor may flow through at least partially open valve  124  and then through mass flow controller  126  disposed prior to the entrance into the reaction chamber  106 . In some embodiments, the mass flow controller  126  is calibrated for chlorine vapor and optionally any reaction byproducts, so that the mass flux of the chlorine vapor entering the reaction chamber can be carefully controlled. 
     In other embodiments of the disclosure, the chlorine vapor produced in the reservoir vessel may be accumulated in a vapor storage unit prior to entry in the reaction chamber. In more detail, an optional vapor storage unit  122  may be disposed between the reservoir vessel  104  and the reaction chamber  106  and such a vapor storage unit  122  may collect and accumulate the chlorine vapor produced by the reservoir vessel  104 . In some embodiments of the disclosure, the vapor storage unit  122  may be integral to and disposed within the reservoir vessel  104 , whereas in other embodiments the vapor storage unit  122  may be disposed externally from the reservoir vessel but fluidly connected to the reservoir vessel  104  (as shown in  FIG. 1 ). In some embodiments of the disclosure, the vapor storage unit  122  may accumulate enough chlorine vapor to supply the reaction chamber for one or more fabrication processes. As a non-limiting example embodiment, the vapor storage unit  122  may be configured to accumulate a total amount of chlorine concentration greater than 0.01 g/cm 3 , or greater than 1 g/cm 3 , or even greater than 10 g/cm 3 . In some embodiments of the disclosure, the vapor storage unit may be configured to dispense, accumulate, and/or extract vapors of chlorine with a partial pressure of chlorine greater than 0.01 Torr, or greater than 0.10 Torr, or greater than 1 Torr, or greater than 10 Torr, or even greater than 50 Torr. In some embodiments of the disclosure, the vapor storage unit  122  may dispense, extract and/or accumulate chlorine vapor such that the vapor storage unit  122  may provide a flow of chlorine with a flow greater than 0.1 sccm, or greater than 1 sccm, or greater than 10 sccm, or greater than 100 sccm, or greater than 500 sccm, or even greater than 1000 sccm. 
     In some embodiments of the disclosure, a chlorine vapor and/or a chlorine-containing chemical species is dispensed to the reaction chamber  106 . The reaction chamber  106  and the associated semiconductor processing apparatus (not shown) may take many forms depending on the semiconductor fabrication process to be performed in the reaction chamber  106 . In some embodiments of the disclosure, the reaction chamber may comprise the reaction chamber of at least one of an atomic layer etch apparatus, an atomic layer deposition apparatus, a plasma etch apparatus, a chemical vapor deposition apparatus, or a pretreatment apparatus. In some embodiments, the apparatus does not comprise a plasma. 
     In some embodiments, the reaction chamber  106  may further comprise a substrate support  128 , upon which at least one substrate  130  may be positioned for processing. In some embodiments, the chlorine vapor may enter the reaction chamber  106 , having being dispensed from reservoir vessel  104 , and the chlorine vapor may contact the substrate  130 . 
     As a non-limiting example embodiment, the reaction chamber  106  may comprise the reaction chamber of an atomic layer etching apparatus and the substrate may be contacted with a chlorine vapor such that the exposed surface of the substrate  130  may be chlorinated, i.e., a single monolayer of chlorine may be present on the surface of the substrate  130 . Having chlorinated the surface of the substrate  130  a subsequent process stage may comprise the ion bombardment of the chlorinated surface utilizing an optional plasma source  132 , for example, the ions bombarding the substrate surface may comprise argon ions. The process of chlorinating the substrate surface and subsequently bombarding the chlorinated surface with argon ions may result in the removal of a portion of the substrate  130  in an atomic layer etching process. The process of chlorinating the substrate surface and bombarding the chlorinated surface with argon ions may be repeated multiple times until a desired amount of the substrate  130  has been removed. 
     The embodiments of the disclosure may also include methods for dispensing a chlorine vapor to a reaction chamber. The methods of the disclosure may be illustrated with reference to  FIG. 2  which illustrates a process flow diagram for an exemplary method  200  according to the embodiments of the disclosure. 
     The exemplary method  200 , may include a process block  210  comprising, providing a chemical storage vessel containing a chlorine containing chemical species. In more detail, the methods may comprise fabricating the chemical storage vessel from a quartz material or a corrosion resistant metal or metal alloy, such as, for example, Hastelloy or Monel. In addition, fabricating the chemical storage vessel may comprise fabricating the chemical storage vessel with an inner surface coated with a fluorine based film, such as, for example, polytetrafluoroethylene (PTFE), fluorinated ethylene propylene copolymer (FEP) or perfluoroalkoxy (PFA). The method of providing a chemical storage vessel may also further comprise, providing one or more heating units configured to heat the chemical storage vessel and the chlorine-containing chemical species stored therein. For example, in some embodiments, the methods of the disclosure may comprise heating the chlorine-containing chemical species in the chemical storage vessel to a temperature of greater than 0° C., or greater than 20° C., or greater than 100° C., or greater than 200° C., or greater than 300° C., or even greater than 400° C. 
     The method of providing a chemical storage vessel containing a chlorine-containing chemical species may further comprise selecting the chlorine-containing chemical species to comprise a chemical which is liquid or solid at room temperature and ambient pressure, such as, at least one of S 2 Cl 2 , Se 2 Cl 2 , SCl 2 , SCl, PCl 5 , SeCl 4 , SeCl 2 , SiCl 4 , SbCl 3 , SbCl 5 , BCl 3 , SeO 2 Cl 2 , SO 2 Cl 2 , SeOCl 2 , SbCl 5  or SnCl 4 . Alternatively, the chlorine-containing chemical species may be selected from a substituted (or unsubstituted) alkyl sulfenyl chloride or a substituted (or unsubstituted) alkyl sulfonyl chloride. 
     The method  200  may continue with a process block  220  comprising, flowing the chlorine-containing chemical species to a reservoir vessel. In more detail, the flow of the chlorine-containing chemical species to the reservoir vessel may comprise providing a carrier gas into the chemical storage vessel. For example, the carrier gas may comprise at least one of hydrogen, nitrogen, helium, argon and mixtures thereof. The carrier gas may be utilized to convey the chlorine-containing chemical species to the reservoir vessel. For example, in some embodiments of the methods, the carrier gas may be passed over a surface of the chlorine-containing chemical species, whereas in other embodiments the carrier gas may be “bubbled” through the chlorine-containing chemical species to assist in vapor pickup. To provide further control over the flow of the chlorine-containing chemical species to the reservoir vessel, the mass flux of the carrier gas into the chemical storage vessel may be controlled by utilizing a mass flow controller. 
     The method  200  may continue with a process block  230  comprising, converting the chlorine-containing chemical species into a chlorine vapor in the reservoir vessel. In more detail, the methods of the disclosure may comprise converting the chlorine-containing chemical species into a chlorine vapor by decomposing the chlorine-containing chemical species in the reservoir vessel. For example, the methods may comprise decomposing the chlorine-containing chemical species by heating the chlorine-containing chemical species to a temperature greater than 0° C., or greater than 20° C., or greater than 100° C., or greater than 200° C., or greater than 300° C., or even greater than 400° C. Decomposing the chlorine-containing chemical species to form a chlorine vapor may also produce one or more decomposition byproducts which may be separated from the chlorine vapor or alternatively may be dispensed to the reaction chamber to be utilized in a fabrication process. 
     The methods of the disclosure may also comprise converting the chlorine-containing chemical species into a chlorine vapor by reacting the chlorine-containing chemical species with a chemical reagent disposed within the reservoir vessel. For example, the chemical reagent utilized to react with the chlorine-containing chemical species may comprise at least one of an oxygen containing reagent (e.g., O 2 , H 2 O, or O 3 ), a transition metal (e.g., nickel (Ni), or manganese (Mn)), lithium (Li), aluminum (Al)), or a metal oxide (e.g., Al 2 O 3  or MnO 2 ). The reaction between the chlorine-containing chemical species and the chemical reagent may produce a chlorine vapor and one or more reaction byproducts. In some embodiments of the disclosure, methods may comprise separating the one or more reaction byproducts from the chlorine vapor, or alternatively the one or more reaction byproducts may be dispensed to the reaction chamber to be utilized in a fabrication process. 
     The method  200  may continue with a process block  240  comprising, controllably flowing the chlorine vapor into the reaction chamber. In more detail, the chlorine vapor produced in the reservoir vessel may be dispensed to the reaction chamber utilizing a mass flow controller to regulate the mass flux of the chlorine vapor entering the reaction chamber. For example, a mass flow controller may be disposed between the reservoir vessel and the reaction chamber such that the mass flux of the chlorine vapor may be controlled prior to entering the reaction chamber. In some embodiments of the disclosure, the methods may comprise converting the chlorine-containing chemical species to the chlorine vapor prior to running processes in the reaction chamber. 
     In some embodiments of the disclosure, the method of controllably flowing the chlorine vapor into the reaction chamber may further comprise accumulating and storing the chlorine vapor in a vapor storage unit prior to entering the reaction chamber. For example, a vapor storage unit may be disposed between the reservoir vessel and the reaction chamber and may accumulate and store the chlorine vapor produced in the reservoir vessel. In some embodiments, methods of the disclosure may comprise converting the chlorine-containing chemical species to the chlorine vapor whilst simultaneously running processes in the reaction chamber. 
     In some embodiments of the disclosure, the method of controllably flowing the chlorine vapor into the reaction chamber may further comprise exposing a substrate within the reaction chamber to the chlorine vapor. For example, exposing a substrate to the chlorine vapor may comprise a portion of a semiconductor fabrication process performed within the reaction chamber, the semiconductor fabrication process comprising at least one of a deposition process, an etching process, or a cleaning process. As a non-limiting example, exposing a substrate within the reaction chamber to the chlorine vapor may comprise a portion of an atomic layer etching process, wherein exposing the substrate to the chlorine vapor results in the chlorination of an exposed surface of the substrate. The atomic layer etching process may proceed by bombarding the chlorinated surface of the substrate with ions, such as, for example, argon ions. The bombardment of the chlorinated substrate surface with ions may be achieved by providing a plasma source to the reaction chamber, such as, for example, a remote plasma source or a direct plasma source. The exposure of the substrate to the chlorine vapor and subsequent ion bombardment may result in the etching of a portion of the substrate in an atomic layer etching process. In some embodiments of the disclosure, the methods may comprise repeatedly exposing the substrate to the chlorine vapor and subsequently bombarding the chlorinated surface with ions to enable controlled atomic etching of the substrate until a desired amount of the substrate is removed via the etch process. In some embodiments of the disclosure, the apparatus  100  may not comprise a plasma source. 
     The example embodiments of the disclosure described above do not limit the scope of the invention, since these embodiments are merely examples of the embodiments of the invention, which is defined by the appended claims and their legal equivalents. Any equivalent embodiments are intended to be within the scope of this invention. Indeed, various modifications of the disclosure, in addition to those shown and described herein, such as alternative useful combination of the elements described, may become apparent to those skilled in the art from the description. Such modifications and embodiments are also intended to fall within the scope of the appended claims.