Abstract:
Methods and apparatus for chemical delivery are provided herein. In some embodiments, a first reservoir holds a first volume of fluid, receives a carrier gas, and outputs the carrier gas together with vapor derived from the first volume of fluid. A second reservoir holds a second volume of fluid and is capable of delivering a part of the second volume of fluid to the first reservoir. A self-regulating tube extends from the first reservoir to a region above the second volume of fluid in the second reservoir.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims benefit of U.S. provisional patent application Ser. No. 62/020,825, filed Jul. 3, 2014, which is herein incorporated by reference in its entirety. 
     
    
     FIELD 
       [0002]    Embodiments of the present disclosure generally relate to fluid chemical delivery and, more particularly, to self-regulating fluid chemical delivery. 
       BACKGROUND 
       [0003]    Chemicals used in, for example, semiconductor device processing, are delivered into a process chamber using a fluid containing ampoule. Such known ampoules typically include a canister that is in fluid communication with an inlet port and an outlet port using a carrier gas that is fed through the ampoule. For example, the carrier gas is fed into a space above the fluid, may flow over the fluid, and carries away vapor from the space above the fluid. As another example, the carrier gas is fed into the fluid using a bubbler tube, saturates the fluid, and carries away some of the fluid. The ampoule may be used until all fluid is removed, at which time the ampoule is refilled or replaced. Alternatively, the ampoule may be refilled periodically based on measurements taken using an in situ level sensor. A refill tank holds chemicals for refilling the ampoule and typically has a much larger volume than the ampoule to enable the ampoule to be repeatedly refilled. 
         [0004]    Some of the processes used in, for example, semiconductor device processing use one or more chemicals supplied to the process at defined temperature and pressure ranges. For example, a film deposition process may maintain temperature and pressure within predefined ranges to attain a repeatable film quality and consistent film thickness. However, as fluid is consumed in the ampoule, temperature and pressure conditions may change and therefore change the concentration of the chemical being delivered which affects the outcome of the process being carried out. 
         [0005]    Accordingly, the inventors have provided improved apparatus and methods for regulating fluid chemical delivery. 
       SUMMARY 
       [0006]    Methods and apparatus for chemical delivery are provided herein. In some embodiments, a chemical delivery apparatus includes: a body having a first reservoir that defines a first volume, the first reservoir including a carrier gas inlet and a carrier gas outlet; a second reservoir disposed in the body above the first reservoir and defining a second volume, the second reservoir having a fill tube fluidly coupling the second reservoir to the first reservoir; and a self-regulating tube extending from the second reservoir to the first reservoir 
         [0007]    In some embodiments, a chemical delivery apparatus includes: a chemical delivery apparatus includes: a body having a first reservoir that defines a first volume, the first reservoir including a carrier gas inlet and a carrier gas outlet; a second reservoir disposed in the body above the first reservoir and defining a second volume, the second reservoir having a fill tube fluidly coupling the second reservoir to the first reservoir; and a first heater disposed at least along sidewalls of the first reservoir that heats a fluid contained in the first volume based on a first detected temperature of a first fluid contained in the first volume, and a second heater disposed along sidewalls of the second reservoir that heats a fluid contained in the second volume based on a second detected temperature of a second fluid contained in the second volume. 
         [0008]    In some embodiments, a chemical delivery apparatus includes: a body having a first reservoir that defines a first volume, the first reservoir including a carrier gas inlet and a carrier gas outlet; and a second reservoir disposed in the body above the first reservoir and defining a second volume, the second reservoir having a fill tube fluidly coupling the second reservoir to the first reservoir; wherein at least one of (a) the first reservoir includes baffles that control a path of cross-flow of the carrier gas or (b) the carrier gas inlet includes a nozzle that controls a path of cross-flow of the carrier gas. 
         [0009]    In some embodiments, a chemical delivery method includes: receiving a carrier gas into a first volume that holds a first fluid; collecting, using the carrier gas, vapor that emanates from the first fluid into the first volume; delivering the carrier gas and the vapor from the first volume, and providing a self-regulating tube that extends from the first reservoir to a region above a second fluid contained in the second volume, the second volume being fluidly coupled with the first volume, wherein when the first fluid held in the first volume extends above a lower end of the self-regulating tube, the first fluid seals off the self-regulating tube, and when the first fluid held in the first volume is below a lower end of the self-regulating tube, the carrier gas and the vapor enter the self-regulating tube and cause the second fluid to be delivered from the second volume into the first volume until the first volume of the fluid again extends above the bottom of the self-regulating tube and seals off the self-regulating tube. 
         [0010]    Other and further embodiments of the present disclosure are described below. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    Embodiments of the present disclosure, briefly summarized above and discussed in greater detail below, can be understood by reference to the illustrative embodiments of the disclosure depicted in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this disclosure and are therefore not to be considered limiting of its scope, for the disclosure may admit to other equally effective embodiments. 
           [0012]      FIG. 1  is a schematic view of an example of a chemical delivery apparatus in accordance with some embodiments of the present disclosure. 
           [0013]      FIG. 2  is a schematic view of another example of a chemical delivery apparatus in accordance with some embodiments of the present disclosure. 
           [0014]      FIG. 3  is a flow chart showing an example of a chemical delivery method carried out in accordance with some embodiments of the present disclosure. 
           [0015]      FIGS. 4A-4C  are side views of further examples of a chemical delivery apparatus in accordance with some embodiments of the present disclosure. 
           [0016]      FIGS. 5A ,  5 C and  5 E are side views of still further examples of a chemical delivery apparatus in accordance with some embodiments of the present disclosure; and  FIGS. 5B and 5D  are cross-sectional views of the examples shown in  FIGS. 5A and 5C , respectively. 
           [0017]      FIG. 6A  is a side view of yet another example of a chemical delivery apparatus in accordance with some embodiments of the present disclosure; and  FIG. 6B  is an enlarged view of a portion of the example shown in  FIG. 6A . 
           [0018]      FIGS. 7A and 7B  are side views of still another example of a chemical delivery apparatus in accordance with some embodiments of the present disclosure. 
       
    
    
       [0019]    To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. The figures are not drawn to scale and may be simplified for clarity. It is contemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation. 
       DETAILED DESCRIPTION 
       [0020]    The present disclosure relates to chemical delivery apparatus and methods in which the level of fluid chemical in an ampoule is advantageously self-regulating. More specifically, the level of fluid in a vapor draw or bubbler functional volume may be self-regulating and the majority of stored fluid may be isolated within a closed volume from the carrier gas. The ampoule may be segregated into two functional volumes, a first volume or lower vapor draw/bubbler volume within a first reservoir, and a second volume or upper refill volume within a second reservoir. The second volume may hold a fluid that is delivered to the first volume. The fluid in the first volume may experience constant flow of carrier gas, whereas the fluid in the second volume may not which may minimize chemical decomposition. The fluid level of the second volume may vary as the chemical is supplied to the first volume. 
         [0021]    The second volume may include a refill tube/isolation valve, a level sensor, and a self-regulating tube. The refill tube/isolation valve may be used to add additional fluid into the second volume via, for example, an external bulk delivery system. The refill activity may be determined by a user utilizing either an integrated level sensor or a known consumption rate. The self-regulating tube may be the control mechanism by which the first reservoir may be refilled. As the fluid is consumed in the first reservoir, the bottom of the self-regulating tube may allow the vapor to be displaced above the fluid level of the first volume and may dispense an equivalent amount of fluid to the first reservoir via the refill tube. The above process may be self-regulating and may result in a constant level of fluid in the first reservoir. 
         [0022]    A carrier gas may flow into the first volume through the gas inlet tube, and the carrier gas may saturate with vapor and carry the vapor to a process chamber via the gas outlet tube. The first volume can be either in a vapor draw configuration or a bubbler configuration. 
         [0023]    In addition to the above, additional features may be included. As an example, one or more vapor spaces may be included and may provide minimum surface contact between the first and second reservoirs which may thermally decouple the two reservoirs. Multi-zone heating of the ampoule may be provided using, for example, two, three or four zone heaters. Adhesiveless bonding of the heaters to the wall of the ampoule may be provided using polyimide heaters. 
         [0024]    Fluid level sensing may be included in one or both of the first and second volumes. In-situ fluid temperature measurement for monitoring temperature and/or controlling temperature of a fluid may be provided for one or both of the first and second volumes. The fluid level sensor may be integral with or separate from the fluid temperature measurement sensor. 
         [0025]    A nozzle may be provided at an end of the gas inlet tube which may improve uniformity of the carrier gas flow in the first volume and increase fluid concentration. Baffles may be added to the first volume which may improve uniformity of the carrier gas flow in the first volume and increase fluid concentration. For example, five or nine baffles may be provided. 
         [0026]    An internal coating may be used on the inner walls and/or bottom of one or both of the first and second reservoirs which may facilitate cleaning of one or both of the reservoirs. The internal coating may be an anti-static friction (anti-stiction) coating. The first and second reservoirs may be separable from each other which may facilitate cleaning of one or both of the reservoirs. 
         [0027]    Ampoule pressure may be measured and may be used to control concentration of process precursors in the fluid of one or both of the first and second volumes. 
         [0028]      FIG. 1  is a schematic diagram showing an example of an ampoule  100  according to some embodiments of the disclosure. The ampoule is divided into two functional reservoirs. Lower, first reservoir  102  can serve as the vapor draw reservoir or as the bubbler reservoir and defines the first volume which contains the fluid. Upper, second reservoir  104  defines the second volume which contains the fluid and can serve as the refill reservoir and deliver fluid from the second reservoir  104  to the first reservoir  102 . For example, the fluid of the first reservoir  102  and the fluid of the second reservoir  104  are of a same fluid. The first reservoir  102  and the second reservoir  104  may be disposed in a common housing or body of the ampoule  100 . 
         [0029]    When an inlet valve  130  and an outlet valve  132  are open, a carrier gas enters the first reservoir  102  through gas inlet tube  108  along, for example, path  120  into the space above the first fluid and collects vapor which has evaporated from the fluid. The carrier gas carrying the vapor then exits the first reservoir  102  along, for example, path  124  through, for example, gas outlet tube  114  and outlet valve  132 . In some embodiments, the carrier gas travels along, for example, cross-flow path  122  and collects vapor along the cross-flow path before exiting along path  124 . 
         [0030]    A self-regulating tube  106 , for example, serves as a control mechanism for controlling refill of the first reservoir  102  (e.g., control of the fluid level in the first reservoir  102 ). The self-regulating tube  106  extends from above the fluid of the second reservoir  104  in the second reservoir  104  down into the first reservoir  102 . Initially, the fluid of the first reservoir  102  extends above the bottom of the self-regulating tube  106  and seals off the self-regulating tube  106 . As the fluid of the first reservoir  102  is consumed, the fluid of the first reservoir  102  falls below the bottom of the self-regulating tube  106  so that carrier gas and vapor are permitted to enter the self-regulating tube  106  and travel up to the second reservoir  104 . The carrier gas and vapor that enter into the second reservoir  104  from the self-regulating tube  106  push on the fluid of the second reservoir  104  and cause fluid to be delivered to the first reservoir  102  along, for example, path  128  through a fill tube  116 . The fill tube  116  extends from, for example, the bottom of the second reservoir to, for example, below the level of the fluid in the first reservoir (e.g., in some embodiments, proximate a bottom of the first reservoir  102 ). The fluid continues to be delivered to the first reservoir  102  until the fluid of the first reservoir  102  again extends above the bottom of the self-regulating tube  106  and seals off the self-regulating tube  106 . In this manner, the volume of fluid in the first reservoir  102  is controlled. 
         [0031]    In an example of the second reservoir  104 , the second reservoir  104  does not refill so that the fluid of the second reservoir  104  decreases as fluid is transferred from the first reservoir  102  to the second reservoir  104 . In some embodiments, a chemical level sensor  112  may be provided to detect the level of fluid of the second reservoir  104  and determine, for example, whether the second reservoir  104  is empty, near empty, or at some other desired level. In some embodiments, the detected fluid level is used to control a fluid input valve  134  to deliver fluid along bulk refill inlet tube  110  into the second reservoir  104  along, for example, path  126  to maintain a constant fluid level in the second reservoir  104 . In some embodiments, the level of fluid of the second reservoir  104  is determined using known chemical consumption rates and determines when to operate the fluid input valve  134 . 
         [0032]      FIG. 2  is a schematic diagram showing an example of an ampoule  200  according to some embodiments of the disclosure. In the example, like reference numerals provide a like function as described in  FIG. 1 .  FIG. 2  shows the bulk refill inlet tube  110  and the fluid input valve  134  as broken lines to indicate that the refill feature of the second reservoir is an alternative feature. Additionally, as a further alternative, in a bubbler configuration, the gas inlet tube  108  extends (as depicted by dashed line  108   a ) to below the level of the fluid of the first reservoir  102  so that the carrier gas passes through the fluid of the first reservoir  102  (e.g., bubbles through the fluid of the first reservoir  102 ). As another alternative, the fill tube  116  may be configured as a fluid driven configuration (as depicted by solid line) or as a siphon (as depicted by dashed line  116   a ). 
         [0033]      FIG. 3  is a flow diagram showing an example of a method according to some embodiments of the disclosure. At  302 , the first and second reservoirs and the self-regulating tube are provided. At  304 , carrier gas is received in the first reservoir  102 , and at  306 , the carrier gas is used to collect vapor. At  306 , the carrier gas and vapor are outputted.  304 ,  306 , and  308  may be carried out repeatedly. 
         [0034]    At  310 , the fluid level drops and no longer seals off the bottom of the self-regulating tube. At  312 , the carrier gas and vapor enter the second reservoir  104  through the self-regulating tube and cause the liquid to be delivered from the second reservoir  104  to the first reservoir  102  through a fluid coupling. At  314 , the fluid level rises and seals off the bottom of the self-regulating tube.  310 ,  312 , and  314  may be carried out repeatedly. 
         [0035]      FIG. 4A-4C  show examples of heater arrangements in accordance with the disclosure.  FIG. 4A  shows an example in which two heaters may be provided. A first heater  402  surrounds the walls and bottom of the first reservoir  102  and a second heater  404  surrounds the walls of the second reservoir  104 .  FIG. 4B  shows an example in which three heaters may be provided. A first heater  412  surrounds the walls of the first reservoir  102 , a second heater  414  surrounds the walls of the second reservoir  104 , and a third heater  416  is disposed at the bottom of the first reservoir  102 .  FIG. 4C  shows an example in which four heaters may be provided. The first heater  412 , second heater  414 , and a third heater  416  correspond to the heaters of like number in  FIG. 4B . A further or fourth heater  420  is located between the top of the first reservoir  102  and the bottom of the second reservoir  104 . 
         [0036]      FIGS. 5A-5D  show examples of baffles incorporated in the first reservoir  102  in accordance with the disclosure.  FIG. 5A  shows a side view of an example in which five baffles  502  may be present in the first reservoir  102 .  FIG. 5B  shows a cross sectional top view of the five baffles  502  which is taken along line B-B of  FIG. 5A .  FIG. 5C  depicts a side view of an example in which nine baffles  504  may be included in the first reservoir  102 .  FIG. 5D  is a cross sectional top view of the nine baffles  504  which is taken along line D-D of  FIG. 5B .  FIG. 5E  shows a side view of an example in which a nozzle  510  may be included at an end of the gas inlet tube  108  (also shown in  FIGS. 1 and 2 ) either alternatively to, or in combination with, the baffles  502  or  504 . 
         [0037]      FIGS. 6A-6B  show examples of thermal barriers disposed between the first and second reservoirs in accordance with some embodiments of the present disclosure.  FIG. 6A  shows gaps  602  which may be located between the top wall of the first reservoir  102  and the bottom wall of the second reservoir  104 .  FIG. 6A  also shows an additional thermal barrier space  604  which may be included between the first reservoir  102  and the second reservoir  104 .  FIG. 6B  shows a region B of  FIG. 6A  in greater detail. 
         [0038]      FIGS. 7A and 7B  show an example in which the first reservoir  102  and the second reservoir  104  may be divisible into separate assemblies in accordance with some embodiments of the present disclosure.  FIG. 7A  shows the two reservoirs coupled together and may be sealed, such as using an O-ring.  FIG. 7B  shows which the first reservoir  102  and the second reservoir  104  separated.  FIGS. 7A and 7B  also show that the self-regulating tube  106  may be separable into a first part  106 A which may be part of the first reservoir  102  and a second part  106 B which may be part of the second reservoir  104 . 
         [0039]    While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof.