Abstract:
A method for depositing a Ru metal layer on a patterned substrate from a film precursor vapor delivered from a multi-tray film precursor evaporation system. The method comprises providing a patterned substrate in a process chamber of a deposition system, and forming a process gas containing Ru 3 (CO) 12  precursor vapor and a carrier gas comprising CO gas. The process gas is formed by: providing a solid Ru 3 (CO) 12  precursor in a plurality of spaced trays within a precursor evaporation system, wherein each tray is configured to support the solid precursor and wherein the plurality of spaced trays collectively provide a plurality of surfaces of solid precursor; heating the solid precursor in the plurality of spaced trays in the precursor evaporation system to a temperature greater than about 60° C. and maintaining the solid precursor at the temperature to form the vapor; and flowing the carrier gas in contact with the plurality of surfaces of the solid precursor during the heating to capture Ru 3 (CO) 12  precursor vapor in the carrier gas as the vapor is being formed at the plurality of surfaces. The method further includes transporting the process gas from the precursor evaporation system to the process chamber and exposing the patterned substrate to the process gas to deposit a Ru metal layer on the patterned substrate by a thermal CVD.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application is a continuation of co-pending U.S. patent application Ser. No. 10/998,420 entitled “MULTI-TRAY FILM PRECURSOR EVAPORATION SYSTEM AND THIN FILM DEPOSITION SYSTEM INCORPORATING SAME,” filed on Nov. 29, 2004, the content of which is hereby incorporated by reference herein in its entirety. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to a system for thin film deposition, and more particularly to a system for evaporating a film precursor and delivering the vapor to a deposition chamber.  
         [0004]     2. Description of Related Art  
         [0005]     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 temperatures between about 400° C. and about 500° C., or lower.  
         [0006]     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 electro-chemical 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).  
         [0007]     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.  
         [0008]     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.  
         [0009]     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. 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  
       [0010]     The present invention provides a method for depositing a Ru metal layer on a patterned substrate from a film precursor vapor delivered from a multi-tray film precursor evaporation system. To this end, the method comprises providing a patterned substrate in a process chamber of a deposition system, wherein the patterned substrate contains one or more vias or trenches, or combinations thereof, and forming a process gas containing Ru 3 (CO) 12  precursor vapor and a carrier gas comprising CO gas. The process gas is formed by: providing a solid Ru 3 (CO) 12  precursor in a plurality of spaced trays within a precursor evaporation system, wherein each tray is configured to support the solid Ru 3 (CO) 12  precursor and wherein the plurality of spaced trays collectively provide a plurality of surfaces of solid Ru 3 (CO) 12  precursor; heating the solid Ru 3 (CO) 12  precursor in the plurality of spaced trays in the precursor evaporation system to a temperature greater than about 60° C. and maintaining the solid Ru 3 (CO) 12  precursor at the temperature to form the Ru 3 (CO) 12  precursor vapor; and flowing the carrier gas in contact with the plurality of surfaces of the solid Ru 3 (CO) 12  precursor in the precursor evaporation system during the heating to capture Ru 3 (CO) 12  precursor vapor in the carrier gas as the vapor is being formed at the plurality of surfaces. The method further includes transporting the process gas from the precursor evaporation system to the process chamber and exposing the patterned substrate to the process gas to deposit a Ru metal layer on the patterned substrate by a thermal chemical vapor deposition process. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]     In the accompanying drawings:  
         [0012]      FIG. 1  depicts a schematic view of a deposition system according to an embodiment of the invention;  
         [0013]      FIG. 2  depicts a schematic view of a deposition system according to another embodiment of the invention;  
         [0014]      FIG. 3  presents in cross-sectional view a film precursor evaporation system according to an embodiment of the invention;  
         [0015]      FIG. 4  presents in cross-sectional view a bottom tray for use in a film precursor evaporation system according to an embodiment of the invention;  
         [0016]      FIG. 5A  presents in cross-sectional view a stackable upper tray for use in a film precursor evaporation system according to an embodiment of the invention;  
         [0017]      FIG. 5B  presents in perspective view the tray of  FIG. 5A ;  
         [0018]      FIG. 6  presents in perspective view a film precursor evaporation system according to another embodiment of the invention; and  
         [0019]      FIG. 7  illustrates a method of operating a film precursor evaporation system of the invention. 
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0020]     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.  
         [0021]     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) metal 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 precursor delivery system  40 .  
         [0022]     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 precursor 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 (not shown) in the film precursor evaporation system  50 .  
         [0023]     Referring still to  FIG. 1 , the film precursor evaporation system  50  is configured to store a film precursor and heat the film precursor to a temperature sufficient for evaporating the film precursor, while introducing vapor phase film precursor to the vapor precursor delivery system  40 . As will be discussed in more detail below with reference to  FIGS. 3-6 , the film precursor can, for example, comprise a solid film precursor. Additionally, for example, the film precursor can include a solid metal precursor. Additionally, for example, the film precursor can include a metal-carbonyl. For instance, the metal-carbonyl can include ruthenium carbonyl (Ru 3 (CO) 12 ), or rhenium carbonyl (Re 2 (CO) 10 ). Additionally, for instance, the metal-carbonyl can include W(CO) 6 , Mo(CO) 6 , Co 2 (CO) 8 , Rh 4 (CO) 12 , Cr(CO) 6 , or Os 3 (CO) 12 .  
         [0024]     In order to achieve the desired temperature for evaporating the film precursor (or subliming a solid metal 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 is generally elevated to approximately 40 to 45° C. in conventional systems in order to sublime, for example, 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 is passed over the film precursor or by the film precursor. 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 carbon monoxide (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 above the film precursor via feed line  61 . In another example, carrier gas supply system  60  is coupled to the vapor precursor delivery system  40  and is configured to supply the carrier gas to the vapor of the film precursor via feed line  63  as or after it enters the vapor precursor 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.  
         [0025]     Downstream from the film precursor evaporation system  50 , the film precursor vapor flows with the carrier gas through the vapor precursor delivery system  40  until it enters a vapor distribution system  30  coupled to the process chamber  10 . The vapor precursor 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 precursor delivery system  40  can be characterized by a high conductance in excess of about 50 liters/second.  
         [0026]     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.  
         [0027]     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 walls.  
         [0028]     As described above, for example, conventional systems have contemplated operating the film precursor evaporation system  50 , as well as the vapor precursor delivery system  40 , within a temperature range of approximately 40 to 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 )+ x CO( g )  (2) 
 
 wherein these by-products can adsorb, 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) 
 
         [0029]     However, 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. For instance, the deposition rate can be as low as approximately 1 Angstrom per minute. Therefore, according to one embodiment, the evaporation temperature is elevated 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. In an exemplary embodiment of the present invention, the evaporation temperature is elevated to be greater than or equal to approximately 60° C. In a further exemplary embodiment, the evaporation temperature is elevated to range from approximately 60 to 100° C., and for example from approximately 60 to 90° C. The elevated temperature increases the evaporation rate due to the higher vapor pressure (e.g., nearly an order of magnitude larger) and, hence, it is expected by the inventors to increase the deposition rate. It may also be desirable to periodically clean deposition system  1  following processing of one or more substrates. For example, additional details on a cleaning method and system can be obtained from co-pending U.S. patent application Ser. No. 10/______ , filed on even date herewith and entitled “Method and System for Performing In-situ Cleaning of a Deposition System”, which is herein incorporated by reference in its entirety.  
         [0030]     As discussed above, the deposition rate is proportional to the amount of film precursor that is evaporated and transported to the substrate prior to decomposition, or condensation, or both. Therefore, in order to achieve a desired deposition rate, and to maintain consistent processing performance (i.e., deposition rate, film thickness, film uniformity, film morphology, etc.) from one substrate to the next, it is important to provide the ability to monitor, adjust, or control the flow rate of the film precursor vapor. In conventional systems, an operator may indirectly determine the flow rate of film precursor vapor by using the evaporation temperature, and a pre-determined relationship between the evaporation temperature and the flow rate. However, processes and their performance drift in time, and hence it is imperative that the flow rate is measured more accurately. For example, additional details can be obtained from co-pending U.S. patent application Ser. No. 10/______, filed on even date herewith and entitled “Method and System for Measuring a Flow Rate in a Solid Precursor Delivery System”, which is herein incorporated by reference in its entirety.  
         [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 precursor delivery system  40 , the film precursor evaporation system  50 , and the carrier gas supply system  60 .  
         [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) metal 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 thin 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 (not shown), and a vapor precursor delivery system  140  configured to transport film precursor vapor.  
         [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 vapor, such as a metal-carbonyl precursor, and enable deposition of a thin film, such as a metal layer, on the substrate  125 . According to one embodiment, the film precursor includes a solid precursor. According to another embodiment, the film precursor includes a metal precursor. According to another embodiment, the film precursor includes a solid metal precursor. According to yet another embodiment, the film precursor includes a metal-carbonyl precursor. According to yet another embodiment, the film precursor can be a ruthenium-carbonyl precursor, for example Ru 3 (CO) 12 . According to yet another embodiment of the invention, the film precursor 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 can be W(CO) 6 , Mo(CO) 6 , Co 2 (CO) 8 , Rh 4 (CO) 12 , Cr(CO) 6 , or Os 3 (CO) 12 . The substrate holder  120  is heated to a pre-determined temperature that is suitable for depositing, for instance, a 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 pre-determined temperature. The heater can maintain the temperature of the walls of process chamber  110  from about 40° C. to about 100° 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 precursor 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]     Film precursor evaporation system  150  is configured to hold a film precursor, and evaporate (or sublime) the film precursor by elevating the temperature of the film precursor. A precursor heater  154  is provided for heating the film precursor to maintain the film precursor at a temperature that produces a desired vapor pressure of film precursor. The precursor heater  154  is coupled to an evaporation temperature control system  156  configured to control the temperature of the film precursor. For example, the precursor heater  154  can be configured to adjust the temperature of the film precursor (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 to 100° C., and in another embodiment, to range from approximately 60 to 90° C.  
         [0039]     As the film precursor is heated to cause evaporation (or sublimation), a carrier gas can be passed over the film precursor, or by the film precursor. 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 carbon monoxide (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 above the film precursor. Although not shown in  FIG. 2 , carrier gas supply system  160  can also be coupled to the vapor precursor delivery system  140  to supply the carrier gas to the vapor of the film precursor as or after it enters the vapor precursor 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, for instance, the flow rate of carrier gas can range from about 10 sccm to about 200 sccm. In another embodiment, for instance, 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 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 precursor delivery system  140 , and for stabilizing the supply of the film 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 precursor delivery system  140  comprises a high conductance vapor line having first and second valves  141  and  142  respectively. Additionally, the vapor precursor delivery system  140  can further comprise a vapor line temperature control system  143  configured to heat the vapor precursor delivery system  140  via heaters (not shown). The temperatures of the vapor lines can be controlled to avoid condensation of the film precursor in the vapor line. The temperature of the vapor lines can be controlled from about 20° C. to about 100° 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 carbon monoxide (CO), for use with metal-carbonyls, or a mixture thereof. For example, the dilution gas supply system  190  is coupled to the vapor precursor delivery system  140 , and it is configured to, for instance, supply the dilution gas to vapor film precursor. 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 flow to the process chamber  110 .  
         [0045]     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 seed 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 .  
         [0046]     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 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 .  
         [0047]     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  142 , 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.  
         [0048]     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.  
         [0049]     Referring now to  FIG. 3 , a film precursor evaporation system  300  is depicted in cross-sectional view according to an embodiment. The film precursor evaporation system  300  comprises a container  310  having an outer wall  312  and a bottom  314 . Additionally, the film precursor evaporation system  300  comprises a lid  320  configured to be sealably coupled to the container  310 , wherein the lid  320  includes an outlet  322  configured to be sealably coupled to a thin film deposition system, such as the one depicted in  FIG. 1  or  2 . The container  310  and lid  320  form a sealed environment when coupled to the thin film deposition system. The container  310  and lid  320  can, for example, be fabricated from A6061 aluminum, and may or may not include a coating applied thereon.  
         [0050]     Furthermore, the container  310  is configured to be coupled to a heater (not shown) in order to elevate the evaporation temperature of the film precursor evaporation system  300 , and to a temperature control system (not shown) in order to perform at least one of monitoring, adjusting, or controlling the evaporation temperature. When the evaporation temperature is elevated to an appropriate value as described earlier, film precursor evaporates (or sublimes) forming film precursor vapor to be transported through the vapor delivery system to the thin film deposition system. The container  310  is also sealably coupled to a carrier gas supply system (not shown), wherein container  310  is configured to receive a carrier gas for transporting the film precursor vapor.  
         [0051]     Referring still to  FIG. 3 , and also to  FIG. 4 , the film precursor evaporation system  300  further comprises a base tray  330  configured to rest on the bottom  314  of the container  310 , and having a base outer wall  332  configured to retain the film precursor  350  on the base tray  330 . The base outer wall  332  includes a base support edge  333  for supporting upper trays thereon, as discussed below. Furthermore, the base outer wall  332  includes one or more base tray openings  334  configured to flow the carrier gas from the carrier gas supply system (not shown), over the film precursor  350  towards a center of the container  310 , and along a central flow channel  318  to exhaust through the outlet  322  in the lid  320  with film precursor vapor. Consequently, the film precursor level in the base tray  330  should be below the position of the base tray openings  334 .  
         [0052]     Referring still to  FIG. 3 , and also to  FIGS. 5A and 5B , the film precursor evaporation system  300  further comprises one or more stackable upper trays  340  configured to support the film precursor  350 , and configured to be positioned or stacked upon at least one of the base tray  330  or another of the stackable upper trays  340 . Each of the stackable upper trays  340  comprises an upper outer wall  342  and an inner wall  344  configured to retain the film precursor  350  therebetween. The inner walls  344  define the central flow channel  318 . The upper outer wall  342  further includes an upper support edge  343  for supporting an additional upper tray  340 . Thus, a first upper tray  340  is positioned to be supported on base support edge  333  of base tray  330 , and if desired, one or more additional upper trays may be positioned to be supported on the upper support edge  343  of a preceding upper tray  340 . The upper outer wall  342  of each upper tray  340  includes one or more upper tray openings  346  configured to flow the carrier gas from the carrier gas supply system (not shown), over the film precursor  350  towards central flow channel  318  of the container  310 , and exhaust through the outlet  322  in the lid  320  with film precursor vapor. Consequently, inner walls  344  should be shorter than upper outer walls  342  to allow the carrier gas to flow substantially radially to the central flow channel  318 . Additionally, the film precursor level in each upper tray  340  should be at or below the height of the inner walls  342 , and below the position of the upper tray openings  346 .  
         [0053]     The base tray  330  and the stackable upper trays  340  are depicted to be cylindrical in shape. However, the shape can vary. For instance, the shape of the trays can be rectangular, square or oval. Similarly, the inner walls  344 , and thus central upper flow channel  318 , can be differently shaped.  
         [0054]     When one or more stackable upper trays  340  are stacked upon the base tray  330 , a stack  370  is formed, which provides for an annular space  360  between the base outer wall  332  of the base tray  330  and the container outer wall  312 , and between the upper outer walls  342  of the one or more stackable upper trays  340  and the container outer wall  312 . The container  310  can further comprise one or more spacers (not shown) configured to space the base outer wall  332  of the base tray  330  and the upper outer walls  342  of the one or more stackable upper trays  340  from the container outer wall  312 , and thereby ensure equal spacing within the annular space  360 . To state it another way, in one embodiment, the container  310  is configured such that the base outer wall  332  and the upper outer walls  342  are in vertical alignment.  
         [0055]     The number of trays, including both the base tray and the stackable upper trays, can range from two (2) to twenty (20) and, for example in one embodiment, the number of trays can be five (5), as shown in  FIG. 3 . In an exemplary embodiment, the stack  370  includes a base tray  330  and at least one upper tray  340  supported by the base tray  330 . The base tray  330  may be as shown in  FIGS. 3 and 4 , or may have the same configuration as the upper trays  340  as they are shown in  FIGS. 3-5B . In other words, the base tray  330  may have an inner wall. Although, in  FIGS. 3-5B , the stack  370  is shown to comprise a base tray  330  with one or more separatable and stackable upper trays  340 , a system  300 ′ may include a container  310 ′ with a stack  370 ′ that comprises a single unitary piece having a base tray  330  integral with one or more upper trays  340 , as shown in  FIG. 6 , such that the base outer wall  332  and upper outer walls  342  are integral. Integral is understood to include a monolithic structure, such as an integrally molded structure having no discernible boundaries between trays, as well as a permanently adhesively or mechanically joined structure where there is permanent joinder between the trays. Separatable is understood to include no joinder between trays or temporary joinder, whether adhesive or mechanical.  
         [0056]     The base tray  330  and each of the upper trays  340 , whether stackable or integral, are configured to support a film precursor  350 . According to one embodiment, the film precursor  350  includes a solid precursor. According to another embodiment, the film precursor  350  includes a liquid precursor. According to another embodiment, the film precursor  350  includes a metal precursor. According to another embodiment, the film precursor  350  includes a solid metal precursor. According to yet another embodiment, the film precursor  350  includes a metal-carbonyl precursor. According to yet another embodiment, the film precursor  350  can be a ruthenium-carbonyl precursor, for example Ru 3 (CO) 12 . According to yet another embodiment of the invention, the film precursor  350  can be a rhenium carbonyl precursor, for example Re 2 (CO) 10 . In yet another embodiment, the film precursor  350  can be W(CO) 6 , Mo(CO) 6 , Co 2 (CO) 8 , Rh 4 (CO) 12 , Cr(CO) 6 , or Os 3 (CO) 12 .  
         [0057]     As described above, the film precursor  350  can include a solid precursor. The solid precursor can take the form of a solid powder, or it may take the form of one or more solid tablets. For example, the one or more solid tablets can be prepared by a number of processes, including a sintering process, a stamping process, a dipping process, or a spin-on process, or any combination thereof. Additionally, the solid precursor in solid tablet form may or may not adhere to the base tray  330  or upper tray  340 . For example, a refractory metal powder may be sintered in a sintering furnace configured for both vacuum and inert gas atmospheres, and temperature up to 2000° C. and 2500° C. Alternatively, for example, a refractory metal powder can be dispersed in a fluid medium, dispensed on a tray, and distributed evenly over the tray surfaces using a spin coating process. The refractory metal spin coat may then be thermally cured.  
         [0058]     As described earlier, carrier gas is supplied to the container  310  from a carrier gas supply system (not shown). As shown in  FIGS. 3 and 6 , the carrier gas may be coupled to the container  310  through the lid  320  via a gas supply line (not shown) sealably coupled to the lid  320 . The gas supply line feeds a gas channel  380  that extends downward through the outer wall  312  of container  310 , passes through the bottom  314  of container  310  and opens to the annular space  360 .  
         [0059]     Referring again to  FIG. 3 , the inner diameter of the container outer wall  312  can, for example, range from approximately 10 cm to approximately 100 cm and, for example, can range from approximately 15 cm to approximately 40 cm. For instance, the inner diameter of outer wall  312  can be 20 cm. The diameter of the outlet  322  and the inner diameter of the inner walls  344  of the upper trays  340  can, for example, range from approximately 1 cm to 30 cm and, additionally, for example, the outlet diameter and inner wall diameter can range from approximately 5 to approximately 20 cm. For instance, the outlet diameter can be 10 cm. Additionally, the outer diameter of the base tray  330  and each of the upper trays  340  can range from approximately 75% to approximately 99% of the inner diameter of the outer wall  312  of container  310  and, for example, the tray diameter can range from approximately 85% to 99% of the inner diameter of the outer wall  312  of container  310 . For instance, the tray diameter can be 19.75 cm. Additionally, the height of the base outer wall  332  of base tray  330  and of the upper outer wall  342  of each of the upper trays  340  can range from approximately 5 mm to approximately 50 mm and, for example, the height of each is approximately 30 mm. In addition, the height of each inner wall  344  can range from approximately 10% to approximately 90% of the height of the upper outer wall  342 . For example, the height of each inner wall can range from approximately 2 mm to approximately 45 mm and, for example, is approximately 20 mm.  
         [0060]     Referring yet again to  FIG. 3 , the one or more base tray openings  334  and the one or more upper tray openings  346  can include one or more slots. Alternatively, the one or more base tray openings  334  and the one or more upper tray openings  346  can include one or more orifices. The diameter of each orifice can, for example, range from approximately 0.4 mm to approximately 2 mm. For example, the diameter of each orifice can be approximately 1 mm. In one embodiment, the orifice diameter and width of annular space  360  are chosen such that the conductance through annular space  360  is sufficiently larger than the net conductance of the orifices in order to maintain substantially uniform distribution of the carrier gas throughout the annular space  360 . The number of orifices can, for example, range from approximately 2 to approximately 1000 orifices and, by way of further example, can range from approximately 50 to approximately 100 orifices. For instance, the one or more base tray openings  334  can include seventy two (72), orifices of 1 mm diameter, and the one or more stackable tray openings  346  can include seventy two (72) orifices of 1 mm diameter, wherein the width of the annular space  360  is approximately 2.65 mm.  
         [0061]     The film precursor evaporation system  300  or  300 ′ may be used as either film precursor evaporation system  50  in  FIG. 1 , or film precursor evaporation system  150  in  FIG. 2 . Alternatively, system  300  or  300 ′ may be used in any film deposition system suitable for depositing a thin film on a substrate from precursor vapor.  
         [0062]     Referring now to  FIG. 7 , a method of depositing a thin film on a substrate is described. A flow chart  700  is used to illustrate the steps in depositing the thin film in a deposition system of the present invention. The thin film deposition begins in  710  with placing a substrate in the deposition system in succession for forming the thin 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  720 , a film precursor is introduced to the deposition system. For instance, the film precursor is introduced to a film precursor evaporation system coupled to the process chamber via a precursor vapor delivery system. Additionally, for instance, the precursor vapor delivery system can be heated.  
         [0063]     In  730 , the film precursor is heated to form a film precursor vapor. The film precursor vapor can then be transported to the process chamber through the precursor vapor delivery system. In  740 , the substrate is heated to a substrate temperature sufficient to decompose the film precursor vapor, and, in  750 , the substrate is exposed to the film precursor vapor. Steps  710  to  750  may be repeated successively a desired number of times to deposit a metal film on a desired number of substrates.  
         [0064]     Following the deposition of the thin film on one or more substrates, the stack of trays  370  or  370 ′, or one or more of the base or upper trays  330 ,  340 , can be periodically replaced in  760  in order to replenish the level of film precursor  350  in each tray.  
         [0065]     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.