Patent Publication Number: US-2010119734-A1

Title: Laminar flow in a precursor source canister

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     Embodiments of the present invention relate to a precursor source canister, sometimes referred to as an ampoule, for providing a vaporized precursor material to a processing chamber. 
     2. Description of the Related Art 
     Chemical vapor deposition (CVD) and atomic layer deposition (ALD) are well-known techniques for forming a layer or layers of a material on a substrate. The material is generally formed by the reaction of vapor phase chemicals on and/or near the surface of the substrate. Typically, CVD and ALD processes involve the delivery of gaseous reactants to the substrate surface where a chemical reaction takes place under temperature and pressure conditions favorable to the thermodynamics of the reaction. The type, composition, deposition rate, and thickness uniformity of the materials that may be formed using conventional CVD or ALD processes are generally limited by the ability to deliver chemical reactants or precursors to the substrate surface. 
     The precursor materials to form the gaseous reactants may originate from either a liquid precursor material or a solid precursor material. The liquid or solid precursor material is typically provided to a canister where the material is heated to form vapors. The vapors typically flow to a processing chamber having the substrate therein and react to deposit a material on the substrate surface. 
     Many conventional canisters are commercially available for delivery of precursors to the processing chamber. However, the conventional canisters create challenges. For example, turbulent flow within the canister may pick up or entrain solids or liquids in a carrier gas that flows along with the vapors to the processing chamber. The entrained solids or liquids may result in particle contamination of the processing chamber and/or the substrate. 
     Therefore, there is a need for an improved canister capable of minimizing or eliminating turbulence of the gas flow within the canister. 
     SUMMARY OF THE INVENTION 
     Embodiments of the present invention generally provide a canister apparatus capable of providing a laminar flow inside the canister. In one embodiment, the canister apparatus comprises a container defining an interior volume and an inlet and an outlet in fluid communication with the interior volume, the container having an outer sidewall comprising a first diameter transitioning to an extended flange portion having a second diameter that is greater than the first diameter, and a tubular member extending through the inlet to a distal end thereof adjacent a bottom surface of the interior volume, the tubular member having an upper portion with a plurality of holes formed therethrough at an angle that is substantially normal to a longitudinal axis of the tubular member, each of the plurality of holes configured to allow introduction of a carrier gas into the interior volume. 
     In another embodiment, a method for providing a vaporized precursor material to a processing chamber is disclosed. The present invention method includes providing a container defining an interior volume containing a precursor material, heating the precursor material to form a vapor, flowing a carrier gas into the interior volume from a tubular member disposed in the interior volume, wherein the carrier gas is introduced from a perforated portion of the tubular member and the flow path is substantially normal relative to and parallel with the upper surface of the precursor material, and flowing the carrier gas and vapor to an outlet. 
     In another embodiment, a canister apparatus is disclosed. The canister apparatus includes an annular body having a first diameter coupled to an outwardly extending flange portion having a second diameter greater than the first diameter, an interior volume defined by the annular body, the interior volume comprising a first inside diameter transitioning to a second inside diameter that is greater than the first inside diameter, and a plurality of arcuate shoulder regions coupled to and extending inwardly away from the second inside diameter wherein each of the arcuate shoulder regions includes a threaded opening adapted to receive a fastener. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments. 
         FIG. 1A  is a cross-sectional view of one embodiment of a precursor source canister. 
         FIG. 1B  is a top view of the precursor source canister shown in  FIG. 1A  without the lid. 
         FIG. 1C  is a partial cross-sectional view of one embodiment of the upper portion of a tubular member. 
         FIG. 2  is a cross-sectional view of another embodiment of a precursor source canister. 
         FIG. 3  is a cross-sectional view of another embodiment of a precursor source canister. 
     
    
    
     To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements disclosed in one embodiment may be beneficially utilized on other embodiments without specific recitation. 
     DETAILED DESCRIPTION 
     Embodiments described herein relate to a canister, which may also be known as an ampoule, adapted to contain a precursor material. In particular, the embodiments described herein relate to a canister apparatus equipped with the perforated tubular member capable of minimizing or eliminating turbulence inside the canister, and minimizing or eliminating particle entrainment and/or particle generation. 
       FIG. 1  illustrates one embodiment of a precursor source canister  100 . The canister  100  comprises a lid  102 , a bottom  104 , and sidewalls  106  that define an interior volume  107 . The canister  100  may be made from process resistant materials, such as stainless steel, ceramics, or aluminum. The canister  100  also comprises openings in the lid  102  configured as an inlet  108  and an outlet  110 . The inlet  108  is coupled to a carrier gas source  112 , and the outlet  110  is coupled to a processing chamber  114 . The carrier gas source  112  supplies a carrier gas that is introduced into the interior volume  107  through a tubular member  116 . The interior volume  107  of the canister  100  is adapted to contain a precursor material  118 , which may be in a liquid phase or solid phase. In this embodiment, the precursor material  118  is a liquid precursor material. 
     Examples of suitable precursor source materials disposed in the ampoule  110  and/or delivered from remote precursor material source  180  include titanium tetrachloride (TiCl 4 ), tetrakis(dimethylamido)titanium (TDMAT, (Me 2 N) 4 Ti)), tetrakis(diethylamido)titanium (TEMAT, (Et 2 N) 4 Ti)), bis(ethylcyclopentadienyl)ruthenium((EtCp) 2 Ru), bis(dimethylpentadienyl)ruthenium, bis(diethylpentadienyl)ruthenium, tetrakis(dimethylamido)hafnium(TDMAH, (Me 2 N) 4 Hf)), tetrakis(diethylamido) hafnium(TDEAH, (Et 2 N) 4 Hf)), tetrakis(methylethylamido)hafnium(TMEAH, (MeEtN) 4 Hf)), tertbutylimido-tris(dimethylamido)tantalum(TBTDAT, ( t BuN)Ta(NMe 2 ) 3 ), tertbutylimido-tris(diethylamido)tantalum(TBTDET, ( t BuN)Ta(NEt 2 ) 3 ), tertbutylimido-tris(methylethylamido)tantalum(TBTMET, ( t BuN)Ta(NMe 2 ) 3 ), pentakis(dimethylamido)tantalum(PDMAT, Ta(NMe 2 ) 5 ), tertiaryamylimido-tris(dimethylamido)tantalum(TAIMATA, ( t AmylN)Ta(NMe 2 ) 3 ), wherein  t Amyl is the tertiaryamyl group (C 5 H 11 — or CH 3 CH 2 C(CH 3 ) 2 —), derivatives thereof, or combinations thereof. Other suitable exemplary precursor source materials include water, hydrogen peroxide (H 2 O 2 ), ammonia (NH 3 ), hydrazine (N 2 H 4 ). Suitable silicon precursor source materials include silane (SiH 4 ), disilane (Si 2 H 6 ), chlorosilane (SiH 3 Cl), dichlorosilane (SiH 2 Cl 2 ), trichlorosilane (SiHCl 3 ), silicon tetrachloride (SiCl 4 ), hexachlorodisilane (Si 2 Cl 6 ), and derivatives thereof. 
     The precursor material  118  is heated within the canister  100  to a vapor phase and the vapors are flowed to the processing chamber  114 . In one embodiment, a heater element  120  may be embedded within or coupled to the sidewalls  106 . In another embodiment, a heating device  126  may be coupled to, surround, or otherwise be in thermal communication with the sidewalls  106  and other surfaces of the canister  100 . In one embodiment, the heating device  126  is a heated jacket or heater tape. In another embodiment, the canister  100  may be placed adjacent or in a heat source (not shown), such as an oven, a heated tube, or a hot plate. The heater element  120  or heating device  126  is operable to heat and vaporize the precursor material  118 . The vaporized precursor material  118  may then be flowed out by the carrier gas through the outlet  110  to the processing chamber  114 . 
     An upper portion  121  of the tubular member  116  is perforated and includes a plurality of radial holes  122  configured to direct flow of the carrier gas in a direction substantially normal to the longitudinal axis A of the tubular member  116  and/or the canister  100 . The radial holes  122  may be distributed in a pattern or randomly on the outer peripheral surface of the tubular member  116 . A portion of the introduced carrier gas may thereby flow out of the tubular member  116  through the holes  122  horizontally as shown and in a direction orthogonal and/or approximately parallel to the surface  128  of the precursor material  118 . The height of the upper portion  121  containing the radial holes  122  may be set so that the radial holes  122  remain constantly above the top surface  128  of the precursor material  118 . In one embodiment, a minimum distance D from the lowermost hole  122  of the upper portion  121  to the top surface  128  of the precursor material  118  is about 0.25 inches. 
     In one embodiment, a distal end of the tubular member  116  includes an opening  124  configured to introduce a portion of the carrier gas within the precursor material  118 . In one implementation, the opening  124  may also be sealed or capped so that the carrier gas is allowed to flow only through the radial holes  122 . In another embodiment, the distal end of the tubular member  116  includes a cap (not shown) having small apertures configured to restrict carrier gas flow from the distal end. 
     As the holes  122  are set at a minimum distance D from the top surface  128  of the precursor material  118 , the carrier gas flowing out through the holes  122  do not directly impinge on the precursor material  118 . Moreover, the opening  124  may have a small size so as to restrict the amount of carrier gas flowing into the precursor material  118 . The configuration of the holes  122  and opening  124  may be constructed such that gas flow provided to the opening  124  is minimized and gas flow through the holes  122  above the precursor material  118  is maximized. Thus, particle generation from the precursor material  118  is mitigated or eliminated entirely by the increase in gas flow occurring above the top surface  128  of the precursor material  118 . When the precursor material  118  is heated by the heater element  120 , the precursor material  118  begins to vaporize. The portion of carrier gas flowing out through the radial holes  122  creates a laminar flow path, which is substantially normal to the direction in which the tubular member  116  extends and the carrier gas is adapted to flow the vapor phase precursor material to the outlet  110  in a controlled manner. This flow path provided by one or both of the holes  122  and opening  124  prevents or minimizes turbulence and particle generation. 
     The canister  100  further includes an annular shelf region  132  adapted to increase the volume or head space of the canister  100 . In one embodiment, the annular shelf region  132  is provided by an enlarged diametrical portion of the upper portion of the canister  100 . The enlarged upper portion of the canister  100  comprises an outwardly extending flange portion  138 . In one embodiment, the annular shelf region  132  extends radially outward from the external portion of sidewalls  106  of the canister  100 . The outwardly extending flange portion  138  is coupled to an annular sidewall  142  having a greater diameter than the outer diameter of the sidewalls  106 . The annular sidewall  142  provides an upper surface adapted to couple to the lid  102 . In one aspect, the annular shelf region  132  increases the head space of the interior volume  107 . The lid  102  is adapted to couple to the body of the canister  100  by a plurality of fasteners  136 , such as screws or bolts. The annular shelf region  132  further includes a plurality of shoulders  134  to increase the thickness of the upper portion of the canister  100  so as to provide additional mechanical support for the fasteners  136 . In one embodiment, each shoulder  134  includes at least one threaded hole  140  through which a fastener  136  may be inserted. In this embodiment, the lid  102  is coupled to the canister  100  by six fasteners  136  (only three are shown in this view). In other embodiments, the lid  102  may be coupled to the canister  100  by more or less fasteners  136  adapted to be received by a corresponding number of holes  140 . 
     In conjunction with  FIG. 1A ,  FIG. 1B  is a top view illustrating the annular shelf region  132  with the lid  102  removed. The approximate positioning of the inlet  108  and outlet  110  formed in the central portion of the lid  102  (not shown) are shown in phantom. The annular shelf region  132  includes a plurality of shoulders  134  that are configured as semicircular regions within the annular shelf region  132 . In one embodiment, the shoulders  134  includes a threaded bolt hole  140  adapted to receive a fastener  136 . 
     In one embodiment, the plurality of shoulders  134  are equally spaced on the annular shelf region  132 . Each of the plurality of shoulders  134  include an arcuate portion  144  bowing inwardly toward the interior volume  107  and interfacing with arcuate portions of the interior of the annular sidewall  142 . The area between the shoulders  134  and the interior of the annular sidewall  142  increases the volume of the canister  100 . In one embodiment, the annular shelf region  132  defines an expanded diameter portion of the interior volume  107 . The annular shelf region  132  transitions inward to the reduced diameter of the interior volume  107 . In this configuration, head space of the canister is increased, which may facilitate extended dwell time of the carrier gas and vapors carried therein. Thus a greater concentration of vapors may be provided to the processing chamber. 
     In conjunction with  FIG. 1A ,  FIG. 1C  illustrates the placement of the radial holes  122  on the upper portion  121  of the tubular member  116 . The radial holes  122  are formed through the peripheral surface of the tubular member  116  along an axis B and at an angle substantially normal to the longitudinal axis A. 
     In conjunction with  FIG. 1A ,  FIG. 2  illustrates another canister  200  according to one embodiment of the present invention. The canister  200  contains a solid phase precursor material  202 . The canister  200  comprises the interior volume  107  defined by the lid  102 , bottom  104 , and sidewalls  106 . The solid precursor material  202  may be introduced into the interior volume  107  by removing the lid  102 . 
     In this embodiment, a heater element  216  surrounds at least a portion of the canister  200 . The heater element  216  may be any heat source configured to provide thermal energy to the surfaces of the canister  200 . In one embodiment, the heater element  216  is heater tape that may be in direct contact with surfaces of the canister  200 . The solid precursor material  202  may be vaporized and/or sublimed when heated by the heater element  216 . In one embodiment, a slurry  204  and/or solid particles  206  may be also provided within the precursor material  202  to facilitate heat transfer from the heater element  216 . 
     The canister  200  includes the inlet  108  and outlet  110 . The inlet  110  is coupled to a carrier gas source  112 , and the outlet  110  is connected to a processing chamber  114 . The carrier gas source  112  is adapted to provide a carrier gas into the interior volume  107  through the inlet  108  and a tubular member  226  coupled to the inlet  108 . 
     In this embodiment, the tubular member  226  has distal end including a cap  230 . The cap  230  enables higher flow of carrier gas through the plurality of radial holes  122  formed in the upper portion  121  of the tubular member  226 . The cap  230  also prevents flow of carrier gas within or near the precursor material  202 , which minimizes or eliminates particle contamination. The radial holes  122  are formed on the peripheral surface of the tubular member  226 . The height of the upper portion  121  containing the radial holes  122  may be set so that the radial holes  122  remain constantly above the top surface of the precursor material  202 . In one embodiment, a minimum distance D from the lowermost radial hole  122  to the top surface of the precursor material  202  may be about a 0.25 inches. 
     As the holes  122  are set at a minimum distance D from the top surface of the precursor material  202 , the carrier gas flowing out through the holes  122  would not directly impinge on the precursor material  202 . The cap  230  might be configured to prevent any carrier gas from being flowed out. In another implementation, the cap  230  of the tubular member  226  might be having a plurality of apertures (not shown) so that a limited amount of the carrier gas might be flowing out of the tubular member  226  through those apertures. The configuration of the radial holes  122  and apertures may be constructed such that gas flow provided to the apertures is minimized and gas flow above the precursor material  202  is maximized. Thus, particle generation from the precursor material  202  is mitigated or eliminated entirely by the increase in gas flow occurring above the precursor material  202 . 
     When the precursor material  202  is heated by the heater element  216 , the precursor material  202  begins to vaporize. The portion of carrier gas flowing out through the radial holes  122  creates a laminar flow path, which is substantially normal to the direction in which the tubular member  226  extends and the carrier gas is adapted to flow the vapor phase precursor material to the outlet  110  in a controlled manner. 
     The canister  200  includes the annular shelf region  132  adapted to increase the volume or head space of the canister as shown in  FIG. 1A . In one embodiment, the annular shelf region  132  is provided by an enlarged diametrical portion of the upper portion of the canister  100 . The enlarged upper portion of the canister  100  comprises an outwardly extending flange portion  138 . The outwardly extending flange portion  138  is coupled to an annular sidewall  142  having a greater diameter than the outer diameter of the sidewalls  216 . In one aspect, the annular shelf region  132  further includes a plurality of shoulders  134  to increase the thickness of the upper portion of the canister  200 . 
     After exiting the radial holes  122 , the carrier gas flows generally parallel to a top surface of the precursor material  202 , and then converges toward the outlet  110 . Because the flow of the carrier gas through the radial holes  122  contributes to an increase in the gas pressure above the top surface of the precursor material  202 , the “stirring-up” effect of the precursor material  202  owing to the release of the carrier gas can be minimized. 
     Since the radial holes  122  are arranged to direct the carrier gas substantially horizontally out of the tubular member  226  and above the top surface of the precursor material  202 , laminar flow paths of the carrier gas can be created to flow the vaporized precursor material  202  controllably and evenly to the outlet  110 . As a result, the occurrence of turbulent flowing in the interior volume  107  can be prevented, and solid portions of the precursor material  202  are not carried away when the vaporized precursor material  202  is evacuated by the carrier gas. In one embodiment, the distal end of the tubular member  226  may extend proximate to the bottom of the interior volume  107 . 
     In conjunction with  FIGS. 1A and 2 ,  FIG. 3  illustrates another embodiment of a canister  300  according to one embodiment of the present invention. The canister  300  includes a plurality of baffles  326  and  328 . Though the precursor material  118  is shown in liquid phase, it is understood that the precursor material  118  could also be in a solid phase such as the precursor material  202  shown in  FIG. 2 . 
     The plurality of baffles  326  and  328  may be provided in the interior volume  107  such that the baffles  326  and  328  extend substantially parallel to the tubular member  116 . The baffles  326  may be coupled to the bottom  104 , and the baffles  328  may be coupled to the lid  102 . The baffles  326  and  328  may be made from materials resistant to the process environment of the interior volume  107 , such as ceramics, stainless steel or aluminum. The baffles  326  and  328  are in contact with the precursor material  118  so as to facilitate heat transfer into the precursor material  118 . In addition, the configuration of the baffles  326  and  328  may also provide a greater mean flow path of the carrier gas from the radial holes  122  toward the outlet  110  such that a higher density of vapors may be combined with the carrier gas. Thereafter, the vaporized precursor material  118  could be flowed to the processing chamber  114 . The carrier gas originating from the carrier gas source  112  is introduced into the interior volume  107  by the tubular member  116 . 
     The upper portion  121  of the tubular member  116  is perforated and includes the plurality of radial holes  122 . The radial holes  122  may be distributed in a pattern or randomly on the outer peripheral surface of the tubular member  116 . A portion of the introduced carrier gas may thereby flow out of the tubular member  116  through the radial holes  122  horizontally as shown and in a direction orthogonal and/or approximately parallel to the top surface  323  of the precursor material  118 . The height of the upper portion  121  containing the radial holes  122  may be set so that the radial holes  122  remain constantly above the top surface  323  of the precursor material  118 . In one embodiment, a minimum distance D from the lowermost redial hole  122  to the top surface  323  of the precursor material  118  is about 0.25 inches. With the baffles  326  and  328 , the carrier gas flowed out of the radial holes  122  could be moving in a direction substantially parallel to those baffles  326  and  328 , thus creating a laminar flow along the direction in which the baffles  326  and  328  extend. 
     While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention thus may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.