Abstract:
A method and system for improved delivery of a solid precursor. A chemically inert coating is provided on system components in a precursor delivery line to reduce decomposition of a relatively unstable precursor vapor in the precursor delivery line, thereby allowing increased delivery of the precursor vapor to a processing zone for depositing a layer on a substrate. The solid precursor can, for example, be a ruthenium carbonyl or a rhenium carbonyl. The inert coating can, for example, be a C x F y -containing polymer, such as polytetrafluoroethylene or ethylene-chlorotrifluoroethylene. Other benefits of using an inert coating include easy periodic cleaning of deposits from the precursor delivery line.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to a method and system for thin film deposition, and more particularly to a method and system for improved precursor vapor delivery in a thin film deposition system.  
         [0003]     2. Description of Related Art  
         [0004]     The introduction of copper (Cu) metal into multilayer metallization schemes for manufacturing integrated circuits can necessitate the use of diffusion barriers/liners to promote adhesion and growth of the Cu layers and to prevent diffusion of Cu into the dielectric materials. Barriers/liners that are deposited onto dielectric materials can include refractive materials, such as tungsten (W), molybdenum (Mo), and tantalum (Ta), that are non-reactive and immiscible in Cu, and can offer low electrical resistivity. Current integration schemes that integrate Cu metallization and dielectric materials can require barrier/liner deposition processes at substrate temperature between about 400° C. and about 500° C., or lower.  
         [0005]     For example, Cu integration schemes for technology nodes less than or equal to 130 nm currently utilize a low dielectric constant (low-k) inter-level dielectric, followed by a physical vapor deposition (PVD) TaN layer and Ta barrier layer, followed by a PVD Cu seed layer, and an electrochemical deposition (ECD) Cu fill. Generally, Ta layers are chosen for their adhesion properties (i.e., their ability to adhere on low-k films), and Ta/TaN layers are generally chosen for their barrier properties (i.e., their ability to prevent Cu diffusion into the low-k film).  
         [0006]     As described above, significant effort has been devoted to the study and implementation of thin transition metal layers as Cu diffusion barriers, these studies including such materials as chromium, tantalum, molybdenum and tungsten. Each of these materials exhibits low miscibility in Cu. More recently, other materials, such as ruthenium (Ru) and rhodium (Rh), have been identified as potential barrier layers since they are expected to behave similarly to conventional refractory metals. However, the use of Ru, or Rh can permit the use of only one barrier layer, as opposed to two layers, such as Ta/TaN. This observation is due to the adhesive and barrier properties of these materials. For example, one Ru layer can replace the Ta/taN barrier layer. Moreover, current research is finding that the one Ru layer can further replace the Cu seed layer, and bulk Cu fill can proceed directly following Ru deposition. This observation is due to good adhesion between the Cu and the Ru layers.  
         [0007]     Conventionally, Ru layers can be formed by thermally decomposing a ruthenium-containing precursor, such as a ruthenium carbonyl precursor, in a thermal chemical vapor deposition (TCVD) process. Material properties of Ru layers that are deposited by thermal decomposition of metal-carbonyl precursors (e.g., Ru 3 (CO) 12 ) can deteriorate when the substrate temperature is lowered to below about 400° C. As a result, an increase in the (electrical) resistivity of the Ru layers and poor surface morphology (e.g., the formation of nodules) at low deposition temperatures has been attributed to increased incorporation of CO reaction by-products into the thermally deposited Ru layers. Both effects can be explained by a reduced CO desorption rate from the thermal decomposition of the ruthenium-carbonyl precursor at substrate temperatures below about 400° C.  
         [0008]     Additionally, the use of metal-carbonyls, such as ruthenium carbonyl, can lead to poor deposition rates due to their low vapor pressure and the transport issues associated therewith. For instance, transport issues can include excessive decomposition of the precursor vapor on internal surfaces of the deposition system, such as on the internal surfaces of the vapor delivery system used to transport the vapor from the evaporation system to the process chamber, thus further reducing the amount of precursor vapor that reaches the substrate surface. Overall, the inventor has observed that current deposition systems suffer from such a low rate, making the deposition of such metal films impractical.  
       SUMMARY OF THE INVENTION  
       [0009]     A method and system is provided for improving the transport of precursor vapor in a thin film deposition system.  
         [0010]     In one embodiment of the present invention, a method and system is provided for improving the transport of precursor vapor in a thin film deposition system by applying a coating to one or more internal surfaces of a vapor delivery system exposed to the precursor vapor.  
         [0011]     In a further embodiment of the present invention, a method and system is provided for depositing a metal film from a metal-carbonyl precursor, and periodic cleaning of the coating applied to the internal surfaces is performed using an in-situ cleaning system.  
         [0012]     According to another embodiment, a deposition system for forming a thin film on a substrate is provided comprising: a process chamber having a substrate holder configured to support and to heat the substrate, a vapor distribution system configured to introduce film precursor vapor above the substrate, and a pumping system configured to evacuate the process chamber; a film precursor evaporation system configured to evaporate a film precursor; a vapor delivery system having a first end coupled to an outlet of the film precursor evaporation system and a second end coupled to an inlet of the vapor distribution system of the process chamber; a carrier gas supply system coupled to at least one of the film precursor evaporation system or the vapor delivery system, or both, and configured to supply a carrier gas to transport the film precursor vapor in the carrier gas to the inlet of the vapor distribution system; and a coating applied to one or more internal surfaces vapor delivery system, wherein the coating is configured to reduce decomposition of the film precursor on the one or more internal surfaces.  
         [0013]     According to yet another embodiment, a method for depositing a refractory metal film is provided comprising: applying a coating to at least one internal surface of a vapor delivery system for supplying metal precursor vapor to a process chamber of a deposition system configured to perform thermal chemical vapor deposition (TCVD) from a metal precursor; depositing the refractory metal film on one or more substrates using the deposition system; and cleaning the deposition system following the depositing of the refractory metal film on the one or more substrates using a cleaning composition formed in an in-situ cleaning system coupled to the deposition system.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]     In the accompanying drawings:  
         [0015]      FIG. 1  depicts a schematic view of a deposition system according to an embodiment of the invention;  
         [0016]      FIG. 2  depicts a schematic view of a deposition system according to another embodiment of the invention; and  
         [0017]      FIG. 3  illustrates a method of depositing a thin film on a substrate according to an embodiment of the invention. 
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0018]     In the following description, in order to facilitate a thorough understanding of the invention and for purposes of explanation and not limitation, specific details are set forth, such as a particular geometry of the deposition system and descriptions of various components. However, it should be understood that the invention may be practiced in other embodiments that depart from these specific details.  
         [0019]     Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views,  FIG. 1  illustrates a deposition system  1  for depositing a thin film, such as a ruthenium (Ru) or a rhenium (Re) film, on a substrate according to one embodiment. The deposition system  1  comprises a process chamber  10  having a substrate holder  20  configured to support a substrate  25 , upon which the thin film is formed. The process chamber  10  is coupled to a film precursor evaporation system  50  via a vapor delivery system  40 .  
         [0020]     The process chamber  10  is further coupled to a vacuum pumping system  38  through a duct  36 , wherein the pumping system  38  is configured to evacuate the process chamber  10 , vapor delivery system  40 , and film precursor evaporation system  50  to a pressure suitable for forming the thin film on substrate  25 , and suitable for evaporation of a film precursor  52  in the film precursor evaporation system  50 .  
         [0021]     Referring still to  FIG. 1 , the film precursor evaporation system  50  is configured to store a film precursor  52 , and heat the film precursor  52  to a temperature sufficient for evaporating the film precursor  52 , while introducing vapor phase precursor to the vapor delivery system  40 . The film precursor  52  can, for example, comprise a metal precursor. Additionally, the film precursor  52  can, for example, comprise a solid precursor. Additionally, the film precursor  52  can, for example, comprise a solid metal precursor. Additionally, for example, the metal precursor can include a metal-carbonyl. For instance, the film precursor  52  can include ruthenium carbonyl (Ru 3 (CO) 12 ), or rhenium carbonyl (Re 2 (CO) 10 ). Additionally, for instance, the film precursor  52  can be W(CO) 6 , Mo(CO) 6 , Co 2 (CO) 8 , Rh 4 (CO) 12 , Cr(CO) 6 , or Os 3 (CO) 12 .  
         [0022]     In order to achieve the desired temperature for evaporating the film precursor  52  (or subliming the solid precursor), the film precursor evaporation system  50  is coupled to an evaporation temperature control system  54  configured to control the evaporation temperature. For instance, the temperature of the film precursor  52  is generally elevated to approximately 40° C. or greater in order to sublime, for instance, ruthenium carbonyl. At this temperature, the vapor pressure of the ruthenium carbonyl, for instance, ranges from approximately 1 to approximately 3 mTorr. As the film precursor is heated to cause evaporation (or sublimation), a carrier gas can be passed over the film precursor, by the film precursor, or through the film precursor, or any combination thereof. The carrier gas can include, for example, an inert gas, such as a noble gas (i.e., He, Ne, Ar, Kr, Xe), or a monoxide, such as CO, for use with metal-carbonyls, or a mixture thereof. For example, a carrier gas supply system  60  is coupled to the film precursor evaporation system  50 , and it is configured to, for instance, supply the carrier gas beneath the film precursor  52  via feed line  61 , or above the film precursor  52  via feed line  62 . In another example, carrier gas supply system  60  is coupled to the vapor delivery system  40  and is configured to supply the carrier gas to the vapor of the film precursor  52  via feed line  63  as or after it enters the vapor delivery system  40 . Although not shown, the carrier gas supply system  60  can comprise a gas source, one or more control valves, one or more filters, and a mass flow controller. For instance, the flow rate of carrier gas can range from approximately 5 sccm (standard cubic centimeters per minute) to approximately 1000 sccm. For example, the flow rate of carrier gas can range from about 10 sccm to about 200 sccm. By way of further example, the flow rate of carrier gas can range from about 20 sccm to about 100 sccm.  
         [0023]     Downstream from the film precursor evaporation system  50 , the metal precursor vapor flows with the carrier gas through the vapor delivery system  40  until it enters a vapor distribution system  30  coupled to the process chamber  10 . The vapor delivery system  40  can be coupled to a vapor line temperature control system  42  in order to control the vapor line temperature and prevent decomposition of the film precursor vapor as well as condensation of the film precursor vapor. For example, the vapor line temperature can be set to a value approximately equal to or greater than the evaporation temperature. Additionally, for example, the vapor delivery system  40  can be characterized by a high conductance in excess of about 50 liters/second.  
         [0024]     Referring again to  FIG. 1 , the vapor distribution system  30 , coupled to the process chamber  10 , comprises a plenum  32  within which the vapor disperses prior to passing through a vapor distribution plate  34  and entering a processing zone  33  above substrate  25 . In addition, the vapor distribution plate  34  can be coupled to a distribution plate temperature control system  35  configured to control the temperature of the vapor distribution plate  34 . For example, the temperature of the vapor distribution plate can be set to a value approximately equal to the vapor line temperature. However, it may be less, or it may be greater.  
         [0025]     Once film precursor vapor enters the processing zone  33 , the film precursor vapor thermally decomposes upon adsorption at the substrate surface due to the elevated temperature of the substrate  25 , and the thin film is formed on the substrate  25 . The substrate holder  20  is configured to elevate the temperature of substrate  25  by virtue of the substrate holder  20  being coupled to a substrate temperature control system  22 . For example, the substrate temperature control system  22  can be configured to elevate the temperature of substrate  25  up to approximately 500° C. In one embodiment, the substrate temperature can range from about 100° C. to about 500° C. In another embodiment, the substrate temperature can range from about 300° C. to about 400° C. Additionally, process chamber  10  can be coupled to a chamber temperature control system  12  configured to control the temperature of the chamber wails.  
         [0026]     As described above, for example, conventional systems have contemplated operating the film precursor evaporation system  50 , as well as the vapor delivery system  40 , within a temperature range of approximately 40-45° C. for ruthenium carbonyl in order to limit metal vapor precursor decomposition and metal vapor precursor condensation. For example, ruthenium carbonyl precursor can decompose at elevated temperatures to form by-products, such as those illustrated below: 
 
Ru 3 (CO) 12 *(ad)         Ru 3 (CO) x *(ad)+(12−x)CO(g)  (1) 
 
or, 
 
Ru 3 (CO) x *(ad)         3Ru(s)+xCO(g)  (2) 
 
 wherein these by-products can adsorb (ad), i.e., condense, on the interior surfaces of the deposition system  1 . The accumulation of material on these surfaces can cause problems from one substrate to the next, such as process repeatability. Alternatively, for example, ruthenium carbonyl precursor can condense at depressed temperatures to cause recrystallization, viz. 
 
Ru 3  (CO) 12  (g)         Ru 3 (Co) 12 *(ad)  (3). 
 
         [0027]     The decomposition of metal precursor vapor, or condensation of metal vapor, can occur on one or more internal surfaces within the thin film deposition system  1  that are exposed to the vapor as it is transported from the film precursor evaporation system  50  to the substrate  25 . These internal surfaces include, at a minimum, internal surfaces  41  of the vapor delivery system  40 . In addition, decomposition or condensation may occur on internal surfaces  31  of the vapor distribution system  30 , including surfaces within plenum  32  or on the vapor distribution plate  34  or one or more orifices therein, and on internal surfaces  11  of the process chamber  10  including wall surfaces or surfaces on the substrate holder  20 , as well as surfaces of duct  36 . Within such systems having a small process window, the deposition rate becomes extremely low, due in part to the low vapor pressure of ruthenium carbonyl, as well as excessive decomposition of the precursor vapor on internal surfaces  11 ,  31 ,  41 . For instance, the deposition rate can be as low as approximately 1 Angstrom per minute.  
         [0028]     The inventors have observed that applying a coating to one or more of these internal surfaces  11 ,  31 ,  41  causes a reduction of, for example, vapor precursor decomposition and, as a result, an improvement of the deposition rate. According to one embodiment, a coating is applied to one or more internal surfaces  41  in the vapor delivery system  40 . In a further embodiment, a coating is also applied to one or more of the internal surfaces  11 ,  31  in thin film deposition system  1 . For example, the coating can comprise a C x F y -containing polymer coating, also referred to as a fluorocarbon coating or fluoropolymer, which is chemically inert. By way of further example, the coating can comprise polytetrafluoroethylene, such as Teflon® PTFE from DuPont or Halon® from Allied Chemical Corp., or ethylene-chlorotrifluoroethylene, such as Halar® ECTFE from Solvay Solexis. By way of further example and not limitation, other fluorocarbon coatings include fluorinated ethylene propylene, polyvinylidene fluoride, perfluoroalkoxy, polychlorotrifluoroethylene, ethylene-tetrafluoroethylene, and polyvinylfluoride. As an example,  FIG. 1  illustrates a coating  43  applied to the internal surfaces  41  of the vapor delivery system  40 . The coating  43  can be an adherent coating applied using at least one of spray coating, thermal spray coating, vapor deposition, or dip coating. Furthermore, the coating  43  can be formed by inserting a thin laminate sheet of material that may or may not adhere to the internal surfaces  11 ,  31 ,  41 .  
         [0029]     Thereafter, the deposition system  1  is optionally periodically cleaned using an optional in-situ cleaning system  70  coupled to, for example, the vapor delivery system  40 , as shown in  FIG. 1 . Per a frequency determined by the operator, the in-situ cleaning system  70  can perform routine cleanings of the deposition system  1  in order to remove accumulated residue on internal surfaces  11 ,  31 ,  41  of deposition system  1  and on coatings  43 . The in-situ cleaning system  70  can, for example, comprise a radical generator configured to introduce chemical radical capable of chemically reacting and removing such residue. Additionally, for example, the in-situ cleaning system  70  can, for example, include an ozone generator configured to introduce a partial pressure of ozone. For instance, the radical generator can include an upstream plasma source configured to generate oxygen or fluorine radical from oxygen (O 2 ), nitrogen trifluoride (NF 3 ), O 3 , XeF 2 , CIF 3 , or C 3 F 8  (or, more generally, C x F y ), respectively. The radical generator can include an Astron® reactive gas generator, commercially available from MKS Instruments, Inc., ASTeX® Products (90 Industrial Way, Wilmington, Mass. 01887).  
         [0030]     During operation of a cleaning process, several parameters can be set and optimized for cleaning performance. For example, the operator can set, monitor, adjust, or control the flow rate of the cleaning composition, the vapor line temperature, the temperature of the vapor distribution plate, the temperature of the substrate holder (or “dummy” substrate), the temperature of the process chamber, the pressure in the process chamber, or any combination thereof. The inventors have observed that the application of a coating  43  to one or more internal surfaces  11 ,  31 ,  41  of thin film deposition system  1  permits in-situ cleaning of the thin film deposition system  1  with a reduced risk of damage to deposition system components during cleaning.  
         [0031]     Still referring the  FIG. 1 , the deposition system  1  can further include a control system  80  configured to operate and control the operation of the deposition system  1 . The control system  80  is coupled to the process chamber  10 , the substrate holder  20 , the substrate temperature control system  22 , the chamber temperature control system  12 , the vapor distribution system  30 , the vapor delivery system  40 , the film precursor evaporation system  50 , the carrier gas supply system  60 , and the optional in-situ cleaning system  70 .  
         [0032]     In yet another embodiment,  FIG. 2  illustrates a deposition system  100  for depositing a thin film, such as a ruthenium (Ru) or a rhenium (Re) film, on a substrate. The deposition system  100  comprises a process chamber having a substrate holder  120  configured to support a substrate  125 , upon which the metal film is formed. The process chamber  110  is coupled to a precursor delivery system  105  having film precursor evaporation system  150  configured to store and evaporate a film precursor  152 , and a vapor delivery system  140  configured to transport film precursor vapor. One or more of the internal surfaces in deposition system  100  can include a coating such as one described above.  
         [0033]     The process chamber  110  comprises an upper chamber section  111 , a lower chamber section  112 , and an exhaust chamber  113 . An opening  114  is formed within lower chamber section  112 , where bottom section  112  couples with exhaust chamber  113 .  
         [0034]     Referring still to  FIG. 2 , substrate holder  120  provides a horizontal surface to support substrate (or wafer)  125 , which is to be processed. The substrate holder  120  can be supported by a cylindrical support member  122 , which extends upward from the lower portion of exhaust chamber  113 . An optional guide ring  124  for positioning the substrate  125  on the substrate holder  120  is provided on the edge of substrate holder  120 . Furthermore, the substrate holder  120  comprises a heater  126  coupled to substrate holder temperature control system  128 . The heater  126  can, for example, include one or more resistive heating elements. Alternately, the heater  126  can, for example, include a radiant heating system, such as a tungsten-halogen lamp. The substrate holder temperature control system  128  can include a power source for providing power to the one or more heating elements, one or more temperature sensors for measuring the substrate temperature or the substrate holder temperature, or both, and a controller configured to perform at least one of monitoring, adjusting, or controlling the temperature of the substrate or substrate holder.  
         [0035]     During processing, the heated substrate  125  can thermally decompose the vapor of film precursor  152 , and enable deposition of a thin film on the substrate  125 . According to one embodiment, the film precursor  152  includes a metal precursor. According to another embodiment, the film precursor  152  includes a solid precursor. According to another embodiment, the film precursor  152  includes a solid metal precursor. According to another embodiment, the film precursor  152  includes a metal-carbonyl precursor. According to yet another embodiment, the film precursor  152  can be a ruthenium-carbonyl precursor, for example Ru 3 (CO) 12 . According to yet another embodiment of the invention, the film precursor  152  can be a rhenium carbonyl precursor, for example Re 2 (CO) 10 . As will be appreciated by those skilled in the art of thermal chemical vapor deposition, other ruthenium carbonyl precursors and rhenium carbonyl precursors can be used without departing from the scope of the invention. In yet another embodiment, the film precursor  152  can be W(CO) 6 , Mo(CO) 6 , Co 2 (CO) 8 , Rh 4 (CO) 12 , Cr(CO) 6 , or Os 3 (CO) 12 , or the like. The substrate holder  120  is heated to a pre-determined temperature that is suitable for depositing the desired Ru, Re or other metal layer onto the substrate  125 . Additionally, a heater (not shown), coupled to a chamber temperature control system  121 , can be embedded in the walls of process chamber  110  to heat the chamber walls to a predetermined temperature. The heater can maintain the temperature of the walls of process chamber  110  from about 40° C. to about 150° C., for example from about 40° C. to about 80° C. A pressure gauge (not shown) is used to measure the process chamber pressure.  
         [0036]     Also shown in  FIG. 2 , a vapor distribution system  130  is coupled to the upper chamber section  111  of process chamber  110 . Vapor distribution system  130  comprises a vapor distribution plate  131  configured to introduce precursor vapor from vapor distribution plenum  132  to a processing zone  133  above substrate  125  through one or more orifices  134 .  
         [0037]     Furthermore, an opening  135  is provided in the upper chamber section  111  for introducing a vapor precursor from vapor delivery system  140  into vapor distribution plenum  132 . Moreover, temperature control elements  136 , such as concentric fluid channels configured to flow a cooled or heated fluid, are provided for controlling the temperature of the vapor distribution system  130 , and thereby prevent the decomposition of the film precursor inside the vapor distribution system  130 . For instance, a fluid, such as water, can be supplied to the fluid channels from a vapor distribution temperature control system  138 . The vapor distribution temperature control system  138  can include a fluid source, a heat exchanger, one or more temperature sensors for measuring the fluid temperature or vapor distribution plate temperature or both, and a controller configured to control the temperature of the vapor distribution plate  131  from about 20° C. to about 100° C.  
         [0038]     As illustrated in  FIG. 2 , a film precursor evaporation system  150  is configured to hold film precursor  152  and evaporate (or sublime) the film precursor  152  by elevating the temperature of the film precursor  152 . A precursor heater  154  is provided for heating the film precursor  152  to maintain the film precursor  152  at a temperature that produces a desired vapor pressure of film precursor  152 . The precursor heater  154  is coupled to an evaporation temperature control system  156  configured to control the temperature of the film precursor  152 . For example, the precursor heater  154  can be configured to adjust the temperature of the film precursor  152  (or evaporation temperature) to be greater than or equal to approximately 40° C. Alternatively, the evaporation temperature is elevated to be greater than or equal to approximately 50° C. For example, the evaporation temperature is elevated to be greater than or equal to approximately 60° C. In one embodiment, the evaporation temperature is elevated to range from approximately 60-150° C., and in another embodiment, to range from approximately 60-90° C.  
         [0039]     As the film precursor  152  is heated to cause evaporation (or sublimation), a carrier gas can be passed over the film precursor, by the film precursor, or through the film precursor, or any combination thereof. The carrier gas can include, for example, an inert gas, such as a noble gas (i.e., He, Ne, Ar, Kr, Xe), or a monoxide, such as CO, for use with metal-carbonyls, or a mixture thereof. For example, a carrier gas supply system  160  is coupled to the film precursor evaporation system  150 , and it is configured to, for instance, supply the carrier gas beneath the film precursor, or above the film precursor. Although not shown in  FIG. 2 , carrier gas supply system  160  can also or alternatively be coupled to the vapor delivery system  140  to supply the carrier gas to the vapor of the film precursor  152  as or after it enters the vapor delivery system  140 . The carrier gas supply system  160  can comprise a gas source  161 , one or more control valves  162 , one or more filters  164 , and a mass flow controller  165 . For instance, the flow rate of carrier gas can range from approximately 5 sccm (standard cubic centimeters per minute) to approximately 1000 sccm. In one embodiment, the flow rate of carrier gas can range from about 10 sccm to about 200 sccm. In another embodiment, the flow rate of carrier gas can range from about 20 sccm to about 100 sccm.  
         [0040]     Additionally, a sensor  166  is provided for measuring the total gas flow from the film precursor evaporation system  150 . The sensor  166  can, for example, comprise a mass flow controller, and the amount of film precursor vapor delivered to the process chamber  110  can be determined using sensor  166  and mass flow controller  165 . Alternately, the sensor  166  can comprise a light absorption sensor to measure the concentration of the film precursor in the gas flow to the process chamber  110 .  
         [0041]     A bypass line  167  can be located downstream from sensor  166 , and it can connect the vapor delivery system  140  to an exhaust line  116 . Bypass line  167  is provided for evacuating the vapor delivery system  140 , and for stabilizing the supply of the metal precursor to the process chamber  110 . In addition, a bypass valve  168 , located downstream from the branching of the vapor precursor delivery system  140 , is provided on bypass line  167 .  
         [0042]     Referring still to  FIG. 2 , the vapor delivery system  140  comprises a high conductance vapor line having first and second valves  141  and  142  respectively. Additionally, the vapor delivery system  140  can further comprise a vapor line temperature control system  143  configured to heat the vapor delivery system  140  via heaters (not shown). The temperatures of the vapor lines can be controlled to avoid condensation of the metal precursor in the vapor line. The temperature of the vapor lines can be greater than or equal to 40° C. Additionally, the temperature of the vapor lines can be controlled from about 40° C. to about 150° C., or from about 40° C. to about 90° C. For example, the vapor line temperature can be set to a value approximately equal to or greater than the evaporation temperature.  
         [0043]     Moreover, dilution gases can be supplied from a dilution gas supply system  190 . The dilution gas can include, for example, an inert gas, such as a noble gas (i.e., He, Ne, Ar, Kr, Xe), or a monoxide, such as CO, for use with metal-carbonyls, or a mixture thereof. For example, the dilution gas supply system  190  is coupled to the vapor delivery system  140 , and it is configured to, for instance, supply the dilution gas to the film precursor vapor. The dilution gas supply system  190  can comprise a gas source  191 , one or more control valves  192 , one or more filters  194 , and a mass flow controller  195 . For instance, the flow rate of carrier gas can range from approximately 5 sccm (standard cubic centimeters per minute) to approximately 1000 sccm.  
         [0044]     Mass flow controllers  165  and  195 , and valves  162 ,  192 ,  168 ,  141 , and  142  are controlled by controller  196 , which controls the supply, shutoff, and the flow of the carrier gas, the film precursor vapor, and the dilution gas. Sensor  166  is also connected to controller  196  and, based on output of the sensor  166 , controller  196  can control the carrier gas flow through mass flow controller  165  to obtain the desired film precursor vapor flow to the process chamber  110 .  
         [0045]     Furthermore, as described above, and as shown in  FIG. 2 , an optional in-situ cleaning system  170  is coupled to the precursor delivery system  105  of deposition system  100  through cleaning valve  172 . For instance, the in-situ cleaning system  170  can be coupled to the vapor delivery system  140 . The in-situ cleaning system  170  can, for example, comprise a radical generator configured to introduce chemical radical capable of chemically reacting and removing such residue. Additionally, for example, the in-situ cleaning system  170  can, for example, include an ozone generator configured to introduce a partial pressure of ozone. For instance, the radical generator can include an upstream plasma source configured to generate oxygen or fluorine radical from oxygen (O 2 ), nitrogen trifluoride (NF 3 ), ClF 3 , O 3 , XeF 2 , or C 3 F 8  (or, more generally, C x F y ), respectively. The radical generator can include an Astron® reactive gas generator, commercially available from MKS Instruments, Inc., ASTeX® Products (90 Industrial Way, Wilmington, Mass. 01887).  
         [0046]     As illustrated in  FIG. 2 , the exhaust line  116  connects exhaust chamber  113  to pumping system  118 . A vacuum pump  119  is used to evacuate process chamber  110  to the desired degree of vacuum, and to remove gaseous species from the process chamber  110  during processing. An automatic pressure controller (APC)  115  and a trap  117  can be used in series with the vacuum pump  119 . The vacuum pump  119  can include a turbo-molecular pump (TMP) capable of a pumping speed up to 5000 liters per second (and greater). Alternately, the vacuum pump  119  can include a dry roughing pump. During processing, the carrier gas, dilution gas, or film precursor vapor, or any combination thereof, can be introduced into the process chamber  110 , and the chamber pressure can be adjusted by the APC  115 . For example, the chamber pressure can range from approximately 1 mTorr to approximately 500 mTorr, and in a further example, the chamber pressure can range from about 5 mTorr to 50 mTorr. The APC  115  can comprise a butterfly-type valve or a gate valve. The trap  117  can collect unreacted precursor material, and by-products from the process chamber  110 .  
         [0047]     Referring back to the substrate holder  120  in the process chamber  110 , as shown in  FIG. 2 , three substrate lift pins  127  (only two are shown) are provided for holding, raising, and lowering the substrate  125 . The substrate lift pins  127  are coupled to plate  123 , and can be lowered to below to the upper surface of substrate holder  120 . A drive mechanism  129  utilizing, for example, an air cylinder provides means for raising and lowering the plate  123 . Substrate  125  can be transferred into and out of process chamber  110  through gate valve  200  and chamber feed-through passage  202  via a robotic transfer system (not shown), and received by the substrate lift pins  127 . Once the substrate  125  is received from the transfer system, it can be lowered to the upper surface of the substrate holder  120  by lowering the substrate lift pins  127 .  
         [0048]     Referring again to  FIG. 2 , a controller  180  includes a microprocessor, a memory, and a digital I/O port capable of generating control voltages sufficient to communicate and activate inputs of the processing system  100  as well as monitor outputs from the processing system  100 . Moreover, the processing system controller  180  is coupled to and exchanges information with process chamber  110 ; precursor delivery system  105 , which includes controller  196 , vapor line temperature control system  143 , and evaporation temperature control system  156 ; vapor distribution temperature control system  138 ; vacuum pumping system  118 ; and substrate holder temperature control system  128 . In the vacuum pumping system  118 , the controller  180  is coupled to and exchanges information with the automatic pressure controller  115  for controlling the pressure in the process chamber  110 . A program stored in the memory is utilized to control the aforementioned components of deposition system  100  according to a stored process recipe. One example of processing system controller  180  is a DELL PRECISION WORKSTATION 610™, available from Dell Corporation, Dallas, Tex. The controller  180  may also be implemented as a general-purpose computer, digital signal process, etc.  
         [0049]     Controller  180  may be locally located relative to the deposition system  100 , or it may be remotely located relative to the deposition system  100  via an internet or intranet. Thus, controller  180  can exchange data with the deposition system  100  using at least one of a direct connection, an intranet, or the internet. Controller  180  may be coupled to an intranet at a customer site (i.e., a device maker, etc.), or coupled to an intranet at a vendor site (i.e., an equipment manufacturer). Furthermore, another computer (i.e., controller, server, etc.) can access controller  180  to exchange data via at least one of a direct connection, an intranet, or the internet.  
         [0050]     As described above, for example, conventional systems have contemplated operating the metal precursor evaporation system, as well as the vapor delivery system, within a temperature range of approximately 4045° C. for ruthenium carbonyl in order to limit metal vapor precursor decomposition and metal vapor precursor condensation. However, due to the low vapor pressure of metal-carbonyls, such as ruthenium carbonyl or rhenium carbonyl, at this temperature, the deposition rate of, for example, ruthenium or rhenium, is very low. In order to improve the deposition rate, the evaporation temperature is raised above about 40° C., for example above about 50° C. Following high temperature evaporation of the metal precursor for one or more substrates, the deposition system is periodically cleaned to remove residues formed on internal surfaces of the deposition system.  
         [0051]     Referring now to  FIG. 3 , a method of depositing a refractory metal film on a substrate is described. A flow chart  300  is used to illustrate the steps in depositing the metal film in a deposition system in accordance with the method of the present invention. In  305 , the metal film deposition begins with disposing a coating on one or more surfaces in the deposition system including at least one internal surface of the vapor delivery system. A coating may further be applied to the internal surfaces of the vapor distribution system, which is coupled to the vapor delivery system, and to other surfaces within the process chamber upon which vapor condensate may accumulate. For example, the coating comprises a C x F y -containing polymer coating. By way of further example, the coating may comprise polytetrafluoroethylene. In  310 , a substrate is placed in the deposition system for forming the metal film on the substrate. For example, the deposition system can include any one of the depositions systems described above in  FIGS. 1 and 2 . The deposition system can include a process chamber for facilitating the deposition process, and a substrate holder coupled to the process chamber and configured to support the substrate. Then, in  320 , a metal precursor is introduced to the deposition system. For instance, the metal precursor is introduced to a film precursor evaporation system coupled to the process chamber via a vapor delivery system. Additionally, for instance, the vapor delivery system can be heated.  
         [0052]     In  330 , the metal precursor is heated to form a metal precursor vapor. The metal precursor vapor can then be transported to the process chamber through the vapor delivery system. In  340 , the substrate is heated to a substrate temperature sufficient to decompose the metal precursor vapor, and, in  350 , the substrate is exposed to the metal precursor vapor. Steps  310  to  350  may be repeated successively a desired number of times to deposit a metal film on a desired number of substrates.  
         [0053]     Following the deposition of the refractory metal film on one or more substrates, the deposition system is optionally periodically cleaned in  360  by introducing a cleaning composition from an in-situ cleaning system coupled to the deposition system, and in particular, coupled to at least the vapor delivery system for providing the cleaning composition to the vapor delivery system, and optionally to the process chamber. The cleaning composition can, for example, include a halogen containing radical, fluorine radical, oxygen radical, ozone, or a combination thereof. The in-situ cleaning system can, for example, include a radical generator, or an ozone generator. When a cleaning process is performed, a “dummy” substrate can be utilized to protect the substrate holder. Furthermore, the film precursor evaporation system, the vapor delivery system, the process chamber, the vapor distribution system, or the substrate holder, or any combination thereof can be heated.  
         [0054]     Although only certain exemplary embodiments of this invention have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiments without materially departing from the novel teachings and advantages of this invention. Accordingly, all such modifications are intended to be included within the scope of this invention.