Patent Publication Number: US-2022228264-A1

Title: Methods for depositing a transition metal nitride film on a substrate by atomic layer deposition and related deposition apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a Divisional of, and claims priority to and the benefit of, U.S. patent application Ser. No. 15/636,307, filed Jun. 28, 2017 and entitled “METHODS FOR DEPOSITING A TRANSITION METAL NITRIDE FILM ON A SUBSTRATE BY ATOMIC LAYER DEPOSITION AND RELATED DEPOSITION APPARATUS,” which is hereby incorporated by reference herein. 
    
    
     FIELD OF INVENTION 
     The present disclosure generally relates to methods for depositing a transition metal nitride film on a substrate by atomic layer deposition and also to related deposition apparatus for depositing a transition metal nitride film on a substrate by atomic layer deposition. 
     BACKGROUND OF THE DISCLOSURE 
     In the field of atomic layer deposition (ALD), the temperature of the substrate may not be considered to be a critical process parameter since the growth rate of the film is not highly dependent on the temperature of the substrate but rather on the sequential exposure of the substrate to the different reactant pulses. In fact, the relative temperature independence of the process is one of the advantages of ALD. In ALD, the substrate temperature is preferably high enough to prevent condensation of the reactants on the substrate and to allow the reaction to proceed at a sufficiently high rate. On the other hand, the substrate temperature preferably remains below the limit where thermal decomposition of the individual reactants occurs. For many combinations of reactant, such as metal halides and ammonia, the reaction is able to proceed at relatively low temperatures and up to temperatures as high as the thermal decomposition temperature limit for the reactants. Thus, a wide temperature window for atomic layer deposition is available. 
     One method of classifying ALD type reactors is by the temperature at which the chamber walls of the reactor are maintained with respect to the temperature of a substrate within the reaction chamber. 
     In a cold wall reactor, wherein the temperature of the chamber walls are typically at a temperature lower than the substrate temperature, the cold regions of the chamber walls may be particularly harmful for an ALD process. First of all, increased adsorption or even condensation of the reactants on the cold chamber walls can occur. Physisorbed or condensed materials may stick to the chamber walls at low temperature and may not be efficiently removed from the reaction space during the purge between the two reactant pulses; this may result in extra consumption of material and accelerated contamination of the reactor. 
     A hot wall reactor may be advantageous by keeping all of the chemically-wetted reactor surfaces at the same temperature as the substrate. A hot wall reactor may therefore eliminate unwanted chemical vapor deposition type reactions and by-product formation. A hot wall reactor may further enhance the purging cycle by weakening the interaction of the surplus precursor molecules with the chamber walls, i.e., minimizing the residence time of the non-reacted precursor molecules in the reaction space. However, hot wall reactors may result in high chemical consumption and short chamber lifetimes due to film deposition on all the chemically-wetted surfaces. The loading of substrates in hot wall reactors may also be difficult to automate, making hot wall reactors less suitable for high volume production purposes. In addition, a hot wall design may not be appropriate for ALD systems including a showerhead gas injector as film deposition on the showerhead may result in the obstruction of gas outlets. 
     As an alternative, a warm wall reactor configuration may be utilized such that the chamber walls may be at temperature that is below the onset temperature of the film growth but still high enough to ensure rapid desorption. In an “ideal” warm wall reactor there would be no growth on the chambers walls and therefore no need for cleaning of the chamber walls, however current methods and deposition systems utilizing a warm wall configuration are less than ideal and therefore methods and deposition systems are desirable for overcoming such problems. 
     SUMMARY OF THE DISCLOSURE 
     In accordance with at least one embodiment of the disclosure, a method for depositing a transition metal nitride film on a substrate by atomic layer deposition in a reaction space defined by an at least one chamber wall and a showerhead is disclosed. The method may comprise: providing at least one substrate on a substrate support within the reaction space and controlling a temperature of the at least one chamber wall at least at those portions of the at least one chamber wall that is exposed to a vapor phase reactant. The method may also comprise controlling the temperature of the showerhead and alternatively and sequentially feeding at least two vapor phase reactants into the reaction space, wherein the temperature of the showerhead is controlled at a temperature between approximately 80° C. and approximately 160° C. 
     In some embodiments an apparatus for depositing a transition metal nitride film on a substrate by atomic layer deposition in a reaction space defined by an at least one chamber wall and a showerhead is provided. The apparatus may comprise: a substrate support disposed within the reaction space, the substrate support configured for supporting at least one substrate and a temperature control system for controlling a temperature of the at least one chamber wall at those portions of the at least one chamber wall that is exposed to a vapor phase reactant. The apparatus may also comprise a temperature control system for controlling a temperature of the showerhead, wherein the temperature control system for controlling the temperature of the showerhead is configured to control the temperature of the showerhead to a temperature between approximately 80° C. and approximately 160° C. 
    
    
     
       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 drawing, in which: 
         FIG. 1  illustrates exemplary deposition apparatus in accordance with embodiments of the disclosure; 
         FIG. 2  illustrates further exemplary deposition apparatus in accordance with embodiments of the disclosure; 
         FIG. 3  illustrates even further exemplary deposition apparatus in accordance with embodiments of the disclosure; and 
         FIG. 4  is a flowchart illustrating a method for depositing a transitional metal nitride in accordance with at least one embodiment of the invention. 
     
    
    
     It will be appreciated that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help improve understanding of illustrated embodiments of the present 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. 
     As used herein, the term “atomic layer deposition” (ALD) may refer to a vapor deposition process in which deposition cycles, preferably a plurality of consecutive deposition cycles, are conducted in a process chamber. Typically, during each cycle the precursor is chemisorbed to a deposition surface (e.g., a substrate surface or a previously deposited underlying surface such as material from a previous ALD cycle), forming a monolayer or sub-monolayer that does not readily react with additional precursor (i.e., a self-limiting reaction). Thereafter, if necessary, a reactant (e.g., another precursor or reaction gas) may subsequently be introduced into the process chamber for use in converting the chemisorbed precursor to the desired material on the deposition surface. Typically, this reactant is capable of further reaction with the precursor. Further, purging steps may also be utilized during each cycle to remove excess precursor from the process chamber and/or remove excess reactant and/or reaction by products from the process chamber after conversion of the chemisorbed precursor. Further, the term “atomic layer deposition” as used herein, is also meant to include processes designated by related terms such as, “chemical vapor atomic layer deposition”, “atomic layer epitaxy” (ALE), molecular beam epitaxy (MBE), gas source MBE, or organometallic MDA, and chemical beam epitaxy when performed with alternating pulses of precursor composition(s), reactive gas, and purge (e.g., inert carrier) gas. 
     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 “showerhead” may refer to a gas distribution assembly for providing one or more vapor phase reactants into a reaction space. 
     As used herein, the term “reaction space” may refer to a reactor or reaction chamber, or an arbitrarily defined volume therein, in which conditions can be adjusted to effect film deposition over a substrate by ALD. Typically the reaction space includes surfaces subject to all reaction gas pulses from which gases or particles can flow to the substrate, by entrained flow or diffusion, during normal operation. The reaction space can be, for example, the reaction chamber in a single-substrate ALD reactor or the reaction chamber of a batch ALD reactor, where deposition on multiple substrates takes place at the same time. 
     As used herein, the term “transition metal nitride film” may refer to a film that comprises one or more transition metals and nitrogen. 
     The embodiments of the disclosure may include methods and apparatus for the deposition of a transition metal nitride film on a substrate, for example, the methods and apparatus may be utilized for the deposition of titanium nitride films. The methods and systems of the embodiments may allow for not only the deposition of high quality transition metal nitride films but may also allow for the high volume manufacture of such transition metal nitride films by allowing the deposition apparatus to remain free of undesirable contaminants for a longer period of time than previously achieved. The methods and apparatus of the disclosure may prevent the formation of unwanted adducts on the wetted surfaces of the reaction space, for example, on both the chamber walls and the showerhead gas injector, such that unwanted particle formation is substantially prevented and transition metal nitride films with high thickness uniformity are provided. The methods and apparatus may utilize independent temperature control systems for both the chamber walls as well as the showerhead gas injector to enable close control over the thermal condition of the portions of the reaction space in contact with the vapor phase reactants utilized in the deposition of the transition metal nitride films. 
     In some embodiments of the disclosure a deposition apparatus may be provided for depositing a transition metal nitride film on a substrate by atomic layer deposition in a reaction space defined by an at least one chamber wall and a showerhead. In more detail and with reference to  FIG. 1  a non-limiting exemplary deposition apparatus  100  may include a reaction space  102  defined by an at least one chamber wall  104  and a showerhead  106 . The deposition apparatus  100  may comprise at least one chamber wall  104  or may, in some embodiments, comprise multiple chamber walls. The showerhead  106  in  FIG. 1  is illustrated in block form, however, the showerhead  106  may be a relatively complex structure and designed to mix vapor from multiple sources, such as, at least a transition metal source, a nitrogen source and a carrier/purge gas source, prior to distributing the gas mixture to the reaction space  102 . Further, showerhead  106  may be configured to provide vertical or horizontal flow of gas into the reaction space  102 . An exemplary gas distribution system is described in U.S. Pat. No. 8,152,922 the contents of which are hereby incorporated herein by reference, to the extent such contents do not conflict with the present disclosure. 
     The deposition apparatus  100  may also include a substrate support  108  disposed within the reaction space  102 , the substrate support  108  configured for supporting at least one substrate  110 . In some embodiments of the disclosure, the deposition apparatus  100  may comprise a single batch reactor wherein a single substrate may be processed at a time, whereas in other embodiments, the deposition apparatus  100  may comprise a substrate support  108  which can be configured for supporting a plurality of substrates for processing at the same time. The substrate support  108  may also comprise a temperature control system  112  for controlling the temperature of the substrate support  108  and by turn any associated substrates  110  supported by the substrate support  108 . The temperature control system  112  may comprise a temperature sensor  114  which is connected to the temperature control system  112  and provides an input signal to the substrate support heater  116  for controlling the power applied to the substrate support heater  116 . 
     The deposition apparatus  100  may comprise a temperature controller  118  for controlling a temperature of the at least one chamber wall  104  at least at those portions of the at least one chamber wall  104  that is exposed to a vapor phase reactant. In more detail, the temperature control system  118  for controlling a temperature of the at least one chamber  104  may be configured to control the temperature of the at least one chamber wall  104  to a temperature of between approximately 80° C. and approximately 160° C., or to a temperature of between approximately 90° C. and approximately 140° C. Not to be bound by theory, it is believed that the limited temperature range utilized for the at least one chamber wall substantially prevents the formation and desorption of unwanted by-product material during an atomic layer deposition process for depositing titanium nitride utilizing ammonia (NH 3 ) and titanium tetrachloride (TiCl 4 ). For example, controlling the temperature of the at least one chamber wall  104  to a temperature of between approximately 80° C. and approximately 160° C. may prevent the formation and desorption of at least one of TiCl 4 .(NH 3 ) x  and other by-products comprising HCl, TiCl x  and NH 3 . 
     The temperature controller  118  for controlling a temperature of the least at least one chamber wall  104  may also include at least one temperature sensor  120  and at least one heater  122 . It should be appreciated that the deposition apparatus  100  as illustrated in  FIG. 1  illustrates a single temperature sensor and a single heater connected to temperature controller  118  for controlling the temperature of the at least one chamber wall  104 , however, it is should be appreciated that a plurality of temperature sensors and a plurality of heaters may be connected to temperature controller  118  to provide a multitude of zones of temperature control across the at least one chamber wall  104 . The at least one temperature sensor  120  may be utilized to measure the temperature of the at least one chamber wall  104  and provide an input signal to the temperature controller  118  which in turn controls the power to the at least one heater  122  to maintain the temperature of the at least one chamber wall to a temperature of between approximately 80° C. and approximately 160° C., or to a temperature of between approximately 90° C. and approximately 140° C. 
     In embodiments of the disclosure, the at least one heater  122  utilized in controlling the temperature of the at least one chamber wall may comprise a resistive heater as illustrated in  FIG. 1 , however is should be appreciated that the heating apparatus for controlling the temperature of the at least one chamber wall may comprise any heating arrangement able to provide thermal energy to the at least one chamber wall and may comprise at least one of resistive heating, radiative heating, inductive heating or a recirculating fluid (as will be described in further details herein below). 
     The deposition apparatus  100  may also comprise a temperature controller  124  for controlling a temperature of the showerhead  106 . In more detail, the temperature control system  124  for controlling a temperature of the showerhead  106  may be configured to control the temperature of the showerhead  106  to a temperature of between approximately 80° C. and approximately 160° C., or to a temperature of between approximately 90° C. and approximately 140° C. Not to be bound by theory, it is believed that the limited temperature range utilized for the showerhead may substantially prevent the formation and desorption of unwanted by-product material during an atomic layer deposition process for depositing titanium nitride utilizing ammonia (NH 3 ) and titanium tetrachloride (TiCl 4 ). For example, controlling the temperature of the showerhead  106  to a temperature of between approximately 80° C. and approximately 160° C. may prevent the formation and desorption of at least one of TiCl 4 .(NH 3 ) x  and other by-products comprising HCl, TiCl x  and NH 3 . 
     The temperature controller  124  for controlling a temperature of the showerhead  106  may also include at least one temperature sensor  126  and at least one heater  128 . It should be appreciated that the deposition apparatus  100  as illustrated in  FIG. 1  illustrates a single temperature sensor and a single heater connected to temperature controller  124  for controlling the temperature of the showerhead  106 , however, it is should be appreciated that a plurality of temperature sensors and a plurality of heaters may be connected to temperature controller  124  to provide a multitude of zones of temperature control across the showerhead  106 . The at least one temperature sensor  126  may be utilized to measure the temperature of the showerhead  106  and provide an input signal to the temperature controller  124  which in turn controls the power to the at least one heater  128  to maintain the temperature of the showerhead to a temperature of between approximately 80° C. and approximately 160° C., or to a temperature of between approximately 90° C. and approximately 140° C. 
     In embodiments of the disclosure, the at least one heater  128  utilized in controlling the temperature of the showerhead may comprise a resistive heater as illustrated in  FIG. 1 , however is should be appreciated that the heating apparatus for controlling the temperature of the showerhead  106  may comprise any heating arrangement able to provide thermal energy to the showerhead and may comprise at least one of resistive heating, radiative heating, inductive heating or a recirculating fluid (as will be described in further details herein below). 
     As illustrated in  FIG. 1 , deposition apparatus  100  may comprise three separate and independent temperature control systems, namely an independent temperature control system  112  for controlling the temperature of the substrate support  108 , an independent temperature control system  118  for controlling the temperature of the at least one chamber wall  104  and in addition an independent temperature control system  124  for controlling the temperature of the showerhead  106 . It should however be appreciated that although the three separate temperature controllers provide independent temperature control to portions of the deposition apparatus  100  there may also be possible data transfer between the independent temperature controllers  112 ,  118  and  124 . The data transfer between independent temperature control systems  112 ,  118  and  124  may allow the deposition apparatus  100  to share temperature and PID information between the temperature controllers, thus preventing oscillation of the temperature of the substrate support  108 , the at least one chamber wall  104  and the showerhead  106 . 
     In order to maintain independent temperature control between the at least one chamber wall  104  and the showerhead  106 , embodiments of the disclosure may comprise thermally isolating the at least one chamber wall  104  from the showerhead  106 . For example, a thermal isolation material  130  may be disposed between the at least one chamber wall  104  and the showerhead  106  to substantially prevent thermally energy from transferring between the at least one chamber wall  104  to the showerhead  106  and vice versa. In some embodiments of the disclosure the thermal isolation material  130  between the at least one chamber wall and the showerhead may comprise at least one of a ceramic material or a polymer material, such as, for example, polyethylene terephthalate (PET), Mylar® or Kapton®. 
     In some embodiments, the deposition apparatus  100  may be utilized to deposit a transition metal nitride film on at least one substrate  110  utilizing an atomic layer deposition process. In some embodiments, the transition metal nitride film may comprise a titanium nitride film and due to the embodiments of the deposition apparatus provided the titanium nitride film thickness uniformity may have a standard deviation of less than 1% one-sigma. 
       FIG. 2  illustrates a non-limiting exemplary deposition apparatus  200 . Deposition apparatus  200  is substantially similar to deposition apparatus  100  and comprises a reaction space  102  defined by an at least one chamber wall  104  and a showerhead  106  as well as a substrate support  108  within the reaction space, the substrate support  108  configured for supporting at least one substrate  110 . The exemplary deposition apparatus  200  differs from deposition apparatus  100  in that the temperature control for both the at least one chamber wall  104  and the showerhead  106  may be performed utilizing temperature control systems utilizing recirculating fluids. For example, deposition apparatus  200  includes recirculation loop  202  for controlling the temperature of the at least one chamber wall  104  and also includes recirculation loop  204  for controlling the temperature of the showerhead  106 . 
     In more detail, the at least one chamber wall  104  may include at least one channel, i.e., the recirculation loop  202 , through which a fluid may be circulated. The temperature control system for controlling the temperature of the at least one chamber wall  104  may include independent temperature control system  206  and at least one temperature sensor  208 . As previously stated with regarding to deposition apparatus  100 , it should be appreciated that the temperature control system  206  for controlling the temperature of the at least one chamber wall  104  may comprise multiple recirculation loops as well as multiple temperature sensors to enable multi-zone temperature control of the at least one chamber wall  104 . In some embodiments, the temperature control system  206  may include a fluid heater, heating the fluid in the recirculating system, for example, the fluid heating system may heat the fluid to a temperature to range of between approximately 80° C. and approximately 160° C., or to a temperature of between approximately 90° C. and approximately 140° C. It should also be noted that a fluid recirculating system as shown in  FIG. 2 , may provide not only the possibility of heating the at least one chamber wall  104  but may in addition, or alternatively, remove heat from the at least one chamber wall  104  through which the fluid is circulating. In embodiments wherein heat removal is a requirement the natural heat loss of the fluid within the recirculating loop  202  may not be sufficient to maintain a controlled temperature at the desired set point, in which case the temperature control system  206  associated with recirculating loop  202  may be equipped with one or more active cooling elements instead of or in addition to one or more heaters. 
     In some embodiments of the disclosure, the temperature control system for controlling the temperature of the least at one chamber wall may be configured to control the temperature of the least one chamber wall  104  to a temperature between approximately 80° C. and approximately 160° C., or to a temperature between approximately 90° C. and approximately 140° C. 
     The choice of the circulating fluid depends on the maximum and minimum allowed fluid temperature and the intended application. Several possible choices are available including, for example, water, aqueous solutions with ethylene or propylene, organic heat transfer fluids (e.g., DOWTHERM®, GALDEN®) or silicon fluids (e.g., SYLTHERM 800®). 
     In addition to the fluid temperature control of the at least one chamber wall, embodiments of the disclosure may include fluid temperature control of the showerhead  106  in a similar manner to that previous described for the at least one chamber wall. For example, a recirculation loop  204  may disposed in or on the showerhead  106  by providing one or more channels in or on the showerhead  106 . In addition to the recirculation loop  204  the temperature control of the showerhead may be provided utilizing an independent temperature control system  210  and at least one temperature sensor  212 . In addition to providing heat to the showerhead  106  the temperature control system  210  comprising recirculation loop  204 , may also include one or more active cooling element to enable heat removal from the showerhead  106  if required. As in previous embodiments, the temperature control system for the showerhead  106  may include multiple recirculation loops, temperature control systems and temperature sensors to provide multi-zone temperature control to the showerhead  106 . 
     In some embodiments the temperature control system for controlling a temperature of the showerhead is configured to control the temperature of the showerhead to a temperature between approximately 80° C. and approximately 160° C., or to a temperature between approximately 90° C. and approximately 140° C. 
     The deposition apparatus  200  may also include an independent temperature control system for controlling the temperature of the substrate support  108 . For example, the temperature of the substrate support  108  may be controlled utilizing temperature control system  112 , temperature sensor  114  and heater  116 . Although not shown in  FIG. 2 , a recirculating fluid may also be used to control the temperature of the substrate support  108  by the addition of one or recirculating loops though the substrate support  108 . 
     The temperature control system  210  for controlling the temperature of the showerhead  106  and the temperature control system  206  for controlling the temperature of the at least one chamber wall  104  may be independent from another but may communicate with one another as previously described for deposition apparatus  100 . To substantially maintain the temperature independence between the at least one chamber wall  104  and the showerhead  106  a thermal isolation material  130  may be disposed between the at least one chamber wall  104  and the showerhead  106  to substantially prevent thermally energy from transferring between the at least one chamber wall  104  to the showerhead  106  and vice versa. In some embodiments of the disclosure the thermal isolation material  130  between the at least one chamber wall and the showerhead may comprise at least one of a ceramic material or a polymer material, such as, for example, polyethylene terephthalate (PET), Mylar® or Kapton®. 
       FIG. 3  illustrates a non-limiting exemplary deposition apparatus  300 . Deposition apparatus  300  is substantially similar to deposition apparatus  100  and comprises a reaction space  102  defined by an at least one chamber wall  104  and a showerhead  106  as well as a substrate support  108  within the reaction space, the substrate support  108  configured for supporting at least one substrate  110 . The exemplary deposition apparatus  300  differs from deposition apparatus  100  in that the temperature control for both the at least one chamber wall  104  and the showerhead  106  may be performed utilizing temperature control systems utilizing both heaters and recirculating fluids. For example, deposition apparatus  300  includes recirculation loop  302  and heater  304  for controlling the temperature of the at least one chamber wall  104  and also includes recirculation loop  306  and heater  308  for controlling the temperature of the showerhead  106 . 
     In more detail, the at least one chamber wall  104  may include at least one channel, i.e., the recirculation loop  302 , through which a fluid may be circulated, and in addition, the at least one chamber wall may also include at least one heater  304  for providing thermal energy to the least one chamber wall  104 . The combination of the recirculating fluid with the heater may provide a further degree of temperature control over the at least one chamber wall  104  utilizing temperature controller  310 , at least one temperature sensor  312  in combination with recirculation loop  302  and heater  304 . For example, in certain embodiments the temperature sensor  312  may indicate that the temperature of the at least one chamber wall is below the desired set point, at which point the temperature controller  310  may provide more power to the heater  304  to increase the temperature of the least one chamber sidewall. Conversely if the temperature of the at least one chamber wall is above the desired set point, the temperature controller  310  may provide less power to the heater  304  and provide active cooling to the fluid within recirculation loop  302 . Therefore, the combination of both heaters and recirculation fluid may provide for a more rapid response to desired changes in the temperature of the at least one chamber wall  104 . 
     As described previously, deposition apparatus  300  may also include multiple temperature controllers, temperature sensors, recirculation loops and heaters to provide multi-zone temperature control of the at least one chamber wall  104 . In addition, in some embodiments the heaters utilized for temperature control of the at least one chamber wall may comprise one or more of resistive heaters, radiative heaters and inductive heaters which may be embedded within the at least one chamber wall or disposed proximate thereto. 
     The deposition apparatus  300  may also comprise a temperature control system  314  for controlling the temperature of the showerhead  106 , wherein temperature control system  314  utilizes a recirculation loop  306  and at least one heater  308  in conjunction with temperature sensor  316 . The temperature control system  314  for controlling the temperature of the showerhead  106  is substantially similar to that described for the temperature control system  310  for the at least one chamber wall and therefore is not described in detail herein. 
     The deposition apparatus  300  may also include an independent temperature control system for controlling the temperature of the substrate support  108 . For example, the temperature of the substrate support  108  may be controlled utilizing temperature control system  112 , temperature sensor  114  and heater  116 . Although not shown in  FIG. 3 , a recirculating fluid may also be used to control the temperature of the substrate support  108  by the addition of one or recirculating loops though the substrate support  100 . 
     The temperature control system  314  for controlling the temperature of the showerhead  106  and the temperature control system  310  for controlling the temperature of the at least one chamber wall  104  may be independent from another but may communicate with one another as previously described for deposition apparatus  100 . To substantially maintain the temperature independence between the at least one chamber wall  104  and the showerhead  106  a thermal isolation material  130  may be disposed between the at least one chamber wall  104  and the showerhead  106  to substantially prevent thermally energy from transferring between the at least one chamber wall  104  to the showerhead  106  and vice versa. In some embodiments of the disclosure the thermal isolation material  130  between the at least one chamber wall and the showerhead may comprise at least one of a ceramic material or a polymer material, such as, for example, polyethylene terephthalate (PET), Mylar® or Kapton®. 
     The embodiments of the disclosure may also comprise methods for depositing a transition metal nitride film on a substrate by atomic layer deposition in a reaction space defined by at least one chamber wall and a showerhead. The methods of the disclosure may be more fully understood with reference to  FIG. 4  which illustrates method  400  for depositing a transition metal nitride film. The method  400  may include a first step  410  of providing at least one substrate on a substrate support within the reaction space. 
     Upon providing the at least one substrate into the reaction space, or prior to providing the one or more substrate into the reaction space, method  400  may include a second step  420  of controlling the temperature of the at least one chamber wall at least at those portions of the at least one chamber wall that is exposed to a vapor phase reactant. In more detail, the temperature of the at least one chamber wall is controlled between desired set values optimized for the atomic layer deposition of transition metal nitride films on the at least one substrate and in certain embodiments the temperature of the at least one chamber wall is optimized for the atomic layer deposition of titanium nitride films on the one or more substrates disposed within the reaction space. 
     In some embodiments of the disclosure, controlling the temperature of the least one chamber wall may comprise controlling the temperature between approximately 80° C. and approximately 160° C., or between approximately 90° C. and approximately 140° C. For example, it has been found that the temperature control of the at least one chamber wall over a narrow temperature range can prevent chemical vapor deposition type processes and yield a more atomic layer deposition-like process whilst reducing the formation/adsorption of unwanted reaction by-products, e.g., unwanted reaction adducts, from the at least one chamber wall. 
     In some embodiments, controlling the temperature of the at least one chamber wall further comprises controlling the temperature of the at least one chamber wall utilizing at least one of a heater and a recirculating fluid. 
     In greater detail, one or more heaters may be embedded within the at least one chamber wall to enable the heating of the at least one chamber wall to within the desired temperature range. It should however be appreciated that although an example embodiment is presented comprising embedded resistive heaters it should be appreciated that the embodiments of the disclosure are not so limited and other configurations of heaters may also be utilized such as controlled heating plates disposed adjacent to the at least one chamber wall. In alternative embodiments, two or more heating systems can be radiative or inductive, such that they can remotely heat the at least one chamber wall. 
     In other embodiments of the disclosure, the temperature control of the at least one chamber wall may be achieved utilizing a recirculating fluid. In further detail, a fluid recirculating system can be configured to provide temperature control by providing channels within the at least one chamber wall for the passage of a recirculating fluid. In such configurations the recirculating fluid is associated with a corresponding fluid heater and/or fluid cooler capable of bring the recirculating fluid up to the desired temperature range for controlling the temperature of the at least one chamber wall. 
     In some embodiments of the disclosure controlling the temperature of the at least one chamber wall may be achieved utilizing the heater and the recirculating fluid, in other words controlling the temperature of the at least one chamber wall may be achieved by the combination of both the heater and the circulating fluid. For example, the heater, or a plurality of heaters, may be utilized to control the at least one chamber wall at a desired temperature but may not be capable of actively removing heat from the at least one chamber wall. This may be an issue since the heaters for the chamber walls are not the sole source of heat generation within the reaction space, for example, the substrate support comprises an additional heat generation source and the showerhead gas injector comprises a further heat generation source. Therefore, in some embodiments of the disclosure, it may be necessary to control the temperature of the at least one chamber wall within the desired temperature range by actively cooling the at least one chamber wall. In the case of heat removal utilizing the recirculating fluid the system may comprise an active cooling element instead of or in addition to the fluid heater. This is particularly relevant to the case when the temperature of the substrate support is controlled at a temperature greater than the at least one chamber wall and heat is removed from the chamber walls to maintain the at least one chamber wall at the desired temperature range. 
     In addition to the heater, e.g. resistive heaters, and circulating fluid system, the temperature control system for controlling the temperature of the at least one chamber wall may also comprise at least one temperature sensor and at least one control system. The at least one temperature sensor may be required to monitor and record the temperature of the at least one chamber wall during the atomic layer deposition process and the at least one control system may provide closed loop feedback control of the temperature such that the temperature of the at least one chamber wall remains within the desired temperature range. 
     Method  400  may include a third step  430  of controlling the temperature of the showerhead. In more detail, the temperature of the showerhead may be controlled between desired set values optimized for the atomic layer deposition of transition metal nitride films on the at least one substrate and in certain embodiments the temperature of the showerhead is optimized for the atomic layer deposition of titanium nitride films on the one or more substrates disposed within the reaction space. 
     In some embodiments of the disclosure, controlling the temperature of the showerhead may comprise controlling the temperature between approximately 80° C. and approximately 160° C., or between approximately 90° C. and approximately 140° C. For example, it has been found that the temperature control of the showerhead over a narrow temperature range can prevent chemical vapor deposition type processes and yield a more fully atomic layer deposition-like process whilst reducing the formation adsorption of unwanted reaction by-products, e.g., unwanted reaction adducts, from the at least one chamber wall. 
     In some embodiments, controlling the temperature of the showerhead further comprises controlling the temperature of the showerhead utilizing at least one of a heater or a circulating fluid. 
     As described previously in relation to heating the at least one chamber wall, one or more heaters may be embedded within the showerhead to enable the heating of the showerhead to within the desired temperature range. It should however be appreciated that although an example embodiment is presented comprising embedded heaters it should be appreciated that the embodiments of the disclosure are not so limited and other configurations of heaters may also be utilized such as controlled heating plates disposed adjacent to the showerhead. In alternative embodiments, two or more heating systems can be radiative or inductive, such that they can remotely heat the showerhead. 
     In other embodiments of the disclosure, the temperature control of the showerhead may be achieved utilizing a recirculating fluid. In further detail, a fluid recirculating system can be configured to provide temperature control by providing channels within the showerhead for the passage of a recirculating fluid. In such configurations the recirculating fluid is associated with a corresponding fluid heater and/or fluid cooler capable of bringing the recirculating fluid to the desired temperature range for controlling temperature of the showerhead. 
     In some embodiments of the disclosure controlling the temperature of the showerhead may be achieved utilizing a heater and the circulating fluid, in other words controlling the temperature of the showerhead may be achieved by the combination of both the heater and the circulating fluid. For example, the heater, or a plurality of heaters utilized to bring the showerhead to a desired temperature may not be capable of actively removing heat from the showerhead. This may be an issue due to heat generation coming from both the substrate support and also from the at least one chamber wall. Therefore, in some embodiments of the disclosure, it may be necessary to control the temperature of the showerhead within the desired temperature range by actively cooling the showerhead. In the case of heat removal utilizing the circulating fluid, the system may comprise an active cooling element instead of or in addition to the fluid heater. This may be particularly relevant to the case when the temperature of the substrate support may be controlled at a temperature greater than the showerhead and wherein the showerhead is in close proximity to the substrate support and heat is removed from the showerhead to maintain the showerhead at the desired temperature range. 
     In addition to the heater, e.g. heaters and circulating fluid system, the temperature control system for controlling the temperature of the showerhead may also comprise at least one temperature sensor and at least one control system. The at least one temperature sensor may be required to monitor and record the temperature of the showerhead during the atomic layer deposition process and the at least one control system may provide closed loop feedback control of the temperature such that the temperature of the showerhead remains within the desired temperature range. 
     Upon introducing at least one substrate into the reaction space  410 , controlling the temperature of the at least one chamber wall  420  and controlling the temperature of the showerhead  430 , the forth step  440  may comprise alternatively and sequentially feeding two vapor phase reactants into the reaction space. In some embodiments, the forth step  440  may comprise an atomic layer deposition type process for the deposition of a transition metal nitride. 
     In an ALD-type process for depositing transition metal nitride films, one deposition cycle comprises exposing the substrate to a first reactant, removing any unreacted first reactant and reaction byproducts from the reaction space, exposing the substrate to a second reactant, followed by a second removal step. The first reactant may comprise a metal precursor, in particular a transition metal precursor, such as a titanium precursor, and the second reactant may comprise a nitrogen source, such as ammonia. 
     The transition metal precursor or compound may comprise at least one of the transition metals selected from the group comprising, scandium (Sc), yttrium (Y), titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium (V), niobium (Nb), tantalum (Ta), chromium (Cr), molybdenum (Mo), tungsten (W), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), cadmium (Cd) and mercury (Hg). However, as titanium nitride films are exemplified herein, in such embodiments, the metal compound may comprise titanium. 
     As a non-limiting example embodiment, a transition metal halide reactant, such as, e.g., titanium tetrachloride (TiCl 4 ), may be used as the transition metal precursor in ALD processes. 
     Precursors may be separated by inert gases, such as argon (Ar) or nitrogen (N 2 ), to prevent gas-phase reactions between reactants and enable self-saturating surface reactions. In some embodiments, however, the substrate may be moved to separately contact a first metal reactant and a second nitrogen reactant. Because the reactions self-saturate, strict temperature control of the substrates and precise dosage control of the precursors is not usually required. However, the substrate temperature is preferably such that an incident gas species does not condense into monolayers nor decompose on the surface. Surplus chemicals and reaction byproducts, if any, are removed from the substrate surface, such as by purging the reaction space or by moving the substrate, before the substrate is contacted with the next reactive chemical. Undesired gaseous molecules can be effectively expelled from a reaction space with the help of an inert purging gas. A vacuum pump may be used to assist in the purging. 
     According to some embodiments, ALD-type processes are used to form transition metal nitride films, for example, titanium nitride films on at least one substrate, such as an integrated circuit workpiece. Preferably, each ALD cycle comprises two distinct deposition steps or phases. In a first phase of the deposition cycle (“the metal phase”), the substrate surface on which deposition is desired is contacted with a first reactant comprising a transition metal such as titanium (i.e., titanium source material or chemical) which chemisorbs onto the substrate surface, forming no more than about one monolayer of reactant species on the surface of the substrate. 
     In some embodiments, the transition metal (e.g., titanium) source chemical, also referred to herein as the “transition metal compound” (or in some embodiments as the “titanium compound”), is a halide and the adsorbed monolayer is terminated with halogen ligands. In some embodiments, the titanium halide may be titanium tetrachloride (TiCl 4 ). 
     Excess transition metal (e.g., titanium) source material and reaction byproducts (if any) may be removed from the substrate surface, e.g., by purging with an inert gas. Excess transition metal source material and any reaction byproducts may be removed with the aid of a vacuum generated by a pumping system. 
     In a second phase of the deposition cycle (“the nitrogen phase”), the substrate is contacted with a nitrogen containing precursor, such as ammonia. The nitrogen reactant may react with the titanium-containing molecules left on the substrate surface. Preferably, in the second phase nitrogen is incorporated into the film by the interaction of the nitrogen reactant with the monolayer left by the transition metal (e.g., titanium) source material. In some embodiments, reaction between the nitrogen reactant and the chemisorbed transition metal species produces a transition metal nitride thin film over the substrate. 
     Excess second source chemical and reaction byproducts, if any, are removed from the substrate surface, for example by a purging gas pulse and/or vacuum generated by a pumping system. Purging gas is preferably any inert gas, such as, without limitation, argon (Ar), nitrogen (N 2 ) or helium (He). A phase is generally considered to immediately follow another phase if a purge (i.e., purging gas pulse) or other reactant removal step intervenes. 
     In some embodiments, the method  400  may be utilized to deposit a transition metal nitride film on at least one substrate utilizing an atomic layer deposition process. In some embodiments, the transition metal nitride film may comprise a titanium nitride film and due to the embodiments of the disclosure provided the titanium nitride film thickness uniformity may have a standard deviation of less than 1% one-sigma. 
     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.