Patent Publication Number: US-8123860-B2

Title: Apparatus for cyclical depositing of thin films

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 11/612,931, filed Dec. 19, 2006, now abandoned which application is a continuation of U.S. patent application Ser. No. 10/352,257, filed Jan. 27, 2003, now U.S. Pat. No. 7,175,713, issued Feb. 13, 2007, which application claims benefit of U.S. Provisional Application Ser. No. 60/351,561, filed Jan. 25, 2002, of which all applications are incorporated by reference herein. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention generally relates to semiconductor processing. More particularly, the invention relates to an apparatus for performing cyclical deposition processes in semiconductor substrate processing systems. 
     2. Description of the Related Art 
     An atomic layer deposition (ALD) process is a cyclical deposition method that is generally used for depositing ultra-thin layers (e.g., mono-layers) over features of semiconductor devices having a high aspect ratio, i.e., a ratio of the depth of a feature to the smallest width of the feature. 
     The ALD process utilizes a chemisorption phenomenon to deposit mono-layers of reactive precursor molecules. During the ALD process, reactive precursors are injected, in the form of pulsed gases, into a deposition chamber in a predetermined cyclical order. Each injection of a precursor provides a new atomic layer on a substrate that is additive to or combines with the previously deposited layers. Injections of individual precursor gases generally are separated by injections of a purge gas or, in other embodiments, the purge gas may be flown continuously into the deposition chamber. The purge gas generally comprises an inert gas, such as argon (Ar), helium (He), and the like or a mixture thereof. During the ALD process, the deposition chamber is also continuously evacuated to reduce the gas phase reactions between the precursors. 
     There are many challenges associated with ALD technique that affect the film properties and costs of operation and ownership. For example, unwanted gas phase reactions between precursors within the process chamber of the prior art may cause contamination of deposited films and require frequent cleaning of the chamber, thus decreasing productivity of the ALD process. 
     Therefore, there is a need for an improved apparatus for cyclical depositing of thin films during fabrication of semiconductor devices. 
     SUMMARY OF THE INVENTION 
     The present invention is an apparatus for cyclical depositing thin films on semiconductor substrates with low film contamination and minimal gas phase reactions between the precursors. The apparatus comprises a process chamber having a gas distribution system facilitating separate paths for process gases and an exhaust system that is synchronized with the valves dosing the process gases. Various embodiments of the apparatus are described. In one application, the invention is used to deposit an aluminum oxide (Al 2 O 3 ) film. 
     In one embodiment, a gas distribution system for providing at least two gases to a processing chamber is described. The gas distribution system includes a lid assembly and a manifold comprising a first isolated flow path and a second isolated flow path, wherein the first isolated flow path includes an outlet in fluid communication with a central gas channel having a diameter that radially expands towards a showerhead coupled to the lid assembly, a first high speed valve coupled to the manifold and in fluid communication with the first isolated flow path and a second high speed valve coupled to the manifold and in fluid communication with the second isolated flow path, and a valved exhaust system in communication with and at least partially synchronized with the operation of at least the first high speed valve. 
     In another embodiment, a gas distribution system for providing at least two gases to a processing region in a processing chamber is described. The gas distribution assembly includes a valve assembly comprising a first high speed valve and a second high speed valve coupled to a manifold, wherein the manifold comprises a first isolated flow path and a second isolated flow path, wherein each of the first and second isolated flow paths comprises at least one precursor gas inlet, a lid assembly, comprising: a showerhead coupled to a lid plate, wherein the showerhead comprises a central region having slotted openings and an outer region having a plurality of apertures, and a central gas channel passing through the lid plate, wherein the central gas channel includes an upper portion and a lower portion having an increasing diameter towards the showerhead, and a valved exhaust system in communication with the operation of the first high speed valve and the second high speed valve, wherein each isolated flow path receives a precursor gas and a carrier gas that is pulsed to the processing region by the first high speed valve and the second high speed valve. 
     In another embodiment, a gas distribution system for providing at least two gases to a processing region in a processing chamber is described. The gas distribution system includes a valve assembly comprising a first high speed valve and a second high speed valve coupled to a manifold, wherein the manifold comprises a first isolated flow path, and a second isolated flow path, wherein each of the first and second isolated flow paths comprises at least one precursor gas inlet, a plasma source coupled to the at least one precursor inlet, a lid assembly, comprising: a showerhead coupled to a lid plate, wherein the showerhead comprises a central region having slotted openings and an outer region having a plurality of apertures, and a central gas channel passing through the lid plate, wherein the central gas channel includes an upper portion and a lower portion having an increasing diameter towards the showerhead, and a valved exhaust system in communication with the operation of the first high speed valve and the second high speed valve, wherein each isolated flow path receives a precursor gas and a carrier gas that is pulsed to the processing region by the first high speed valve and the second high speed valve. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The teachings of the present invention can be readily understood by considering the following detailed description in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a schematic, perspective view of one illustrative embodiment of a semiconductor substrate processing system in accordance with the present invention; 
         FIG. 2  is a schematic, cross-sectional view of a process chamber of the processing system of  FIG. 1 ; 
         FIG. 3  is a schematic, partial cross-sectional view of a lid assembly of the process chamber of  FIG. 2 ; 
         FIG. 4  is a schematic, partial view of a showerhead of the process chamber of  FIG. 2 ; 
         FIG. 5  is a schematic, partial cross-sectional view of another embodiment of the lid assembly of the process chamber of  FIG. 2 ; 
         FIG. 6  is a schematic, partial cross-sectional view of another embodiment of the process chamber of the processing system  FIG. 1 ; 
         FIG. 7  is a schematic, partial cross-sectional view of yet another illustrative embodiment of the process chamber of the processing system  FIG. 1 ; 
         FIG. 8  is a schematic, partial cross-sectional view of one embodiment of a showerhead of the process chamber of  FIG. 7 ; 
         FIG. 9  is a schematic, partial cross-sectional view of another embodiment of the showerhead of the process chamber of  FIG. 7 ; and 
         FIG. 10  is a schematic, plan view of a processing platform integrating the process chambers used in performing cyclical deposition processes of the present invention. 
     
    
    
     To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. 
     It is to be noted, however, that the appended drawings illustrate only exemplary embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments. 
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention is an apparatus for performing cyclical depositing of thin films on semiconductor substrates (for example, using an atomic layer deposition (ALD) process and the like) with low film contamination and minimal gas phase reactions between the reactive precursors. In one application, the apparatus is used to deposit an aluminum oxide (Al 2 O 3 ) film. In other applications, the apparatus may be used to deposit other films that include materials such as aluminum (Al), copper (Cu), titanium (Ti), tantalum (Ta), tungsten (W) films, and the like. 
       FIGS. 1-9  are schematic views of various embodiments of an exemplary processing system  100  and salient portions of the system in accordance with the present invention. The images in  FIGS. 1-9  are simplified for illustrative purposes and are not depicted to scale. 
       FIG. 1  is a schematic, perspective view of one illustrative embodiment of a processing system  100  comprising a process chamber  101 , a controller  70 , a dual exhaust system  50 , and a source  530  of process gases that are used during a cyclical deposition process (for example, ALD process). 
     The process chamber  101  comprises a chamber body  105 , a lid assembly  120 , and an ozonator  170 . In the depicted embodiment, the process chamber  101  has two isolated zones (flow paths) for gaseous compounds that are used during an ALD process. Herein the term “gaseous compound” is collectively used for one or more process gases, such as precursor gases, purge gases, carrier gases, catalytic gases, and the like, as well as for mixtures thereof, and the terms “gas” and “gas mixture” are used interchangeably. The isolated flow paths prevent mixing of gaseous compounds before the compounds reach a reaction region  159  of the process chamber  101 . In other embodiments, the process chamber  101  may comprise more than two isolated flow paths. 
     The lid assembly  120  is disposed on the chamber body  105  and, in a closed position, forms a fluid-tight seal with the chamber body. The lid assembly  120  generally comprises a lid plate  122 , a ring heater  125 , a manifold block  150 , a showerhead  130 , and high-speed valves  155 A,  155 B. Components of the lid assembly  120  are preferably formed from process-compatible materials, such as aluminum, aluminum nitride, stainless steel, graphite, silicon carbide, and the like. The lid assembly  120  further comprises a handle  145  and a hinge assembly  140  used to lift the lid assembly during routine cleaning and maintenance of the process chamber  101 . 
     The chamber body  105  comprises a member  109 , a liner  107 , and a support pedestal  111 . A slit  115  is formed in a sidewall of the chamber body  105  to facilitate transfer of a substrate into and out of the process chamber  101 . One example of a suitable wafer transfer robot (for example, robot  1030  described in reference to  FIG. 10 ) is disclosed in commonly assigned U.S. Pat. No. 4,951,601. 
     The support pedestal  111 , for example, a ceramic support pedestal, comprises a heater  53 A, as well as a thermocouple  50 A that is used to monitor the temperature thereof. A signal from the thermocouple  50 A may be used in a feedback loop that controls power applied to a heater  53 A. The heater  53 A may be a resistive heater or other thermal transfer device embedded in or otherwise coupled to the support pedestal  111 . Optionally, the support pedestal  111  may be heated using a conduit (not shown) carrying a heat transfer fluid. The support pedestal  111  may also comprise channels (not shown) to deliver a purge gas to an edge and/or backside of the substrate. Further, the substrate support  111  is coupled to a lifting mechanism and comprises a chucking device that holds the substrate thereon (both not shown). Examples of suitable chucking devices include a vacuum chuck, an electrostatic chuck, a clamp ring, and the like. One example of the lifting mechanism is described in the commonly assigned U.S. Pat. No. 5,951,776. 
     The liner  107  circumscribes the interior vertical surfaces of the chamber body  105 . Alternatively, the liner  107  covers a bottom of the chamber body  105  (as depicted in  FIG. 2 ) or a separate liner may be used to cover the bottom. The liner  107  may be constructed of any process-compatible material. A purge channel  119  is formed between the liner  107  and the chamber body  105 . The purge gas is flown through the purge channel  119  to confine the gaseous compounds within the reaction region  159 , as well as to minimize unwanted deposition on sidewalls of the chamber and improve heat exchange between the sidewalls and the liner  107 . 
     The member  109  defines gas conductance of a path to the exhaust ports  117 A,  117 B. In one embodiment, the member  109  is an annular ring having a plurality of apertures  109 A. The apertures  109 A facilitate uniform removal of gaseous compounds and by-products out of the process chamber  101 . A diameter, number, and location of the apertures  109 A may be determined based on requirements of a particular ALD process. However, in some embodiments, the member  109  may be omitted and, as such, is considered optional. 
     The ring heater  125  is attached to the lid plate  120  using, for example, conventional fasteners, such as screws and the like. Generally, the ring heater  125  comprises at least one embedded electrical heating element (not shown). During the ALD process, the ring heater  125  defines the temperature (for example, about 90 degrees Celsius or higher) of the lid plate  122  to prevent deposition of gaseous compounds and by-products of the process on the lid plate. 
     The high-speed valves  155 A,  155 B (for example, electronically controlled valves) are mounted on the manifold block  150  such that a fluid-tight seal is provided between the manifold and a valve. The seal may be provided using, for example, a gasket (not shown) that is placed between the upper surface of the manifold block  150  and bottom surface of a high-speed valve and compressed thereafter. Such gasket may be formed from stainless steel or other compressible and process-compatible material. In one embodiment, the manifold block  150  comprises one or more cooling channels (not shown) disposed therein to protect the high-speed valves  155 A,  155 B from exposure to excessive operating temperatures during the ALD process. Generally, the manifold block  150  uses running water as a heat transfer medium. 
     In operation, the high-speed valves  155 A,  155 B repeatedly deliver, in a predetermined order, pulses of gaseous compounds into the process chamber  101 . The on/off periods of the valves are about 100 msec or less. The high-speed valves  155 A,  155 B are controlled by the controller  70  or, alternatively, by an application specific controller (nor shown), such as, for example, described in commonly assigned U.S. patent application Ser. No. 09/800,881, filed on Mar. 7, 2001, which is incorporated herein by reference. 
     In one embodiment, the high-speed valves  155 A,  155 B are three-port valves. For example, the high speed valve  155 A has two intake ports  171 A,  177 A and one outlet port  173 A, and the high speed valve  155 B has two intake ports  171 B,  177 B and one outlet port  173 B. In other embodiments, the process chamber  101  may also comprise more than two high-speed valves. However, in other embodiments, a high-speed valve may have only one intake port or more than two intake ports. Suitable high-speed valves are available from Fujikin Inc., of Japan, and other suppliers. 
     In one exemplary application, one intake port of the valve is coupled to a source of a precursor gas, while the other intake port is coupled to a source of a purge gas and the outlet port is coupled to a respective outlet channel (channels  154 A,  154 B). More specifically, one valve (e.g., valve  155 A) doses a precursor gas (for example, aluminum precursor), the other valve (e.g., valve  155 B) doses an oxidizing gas (for example, ozone), and the purge gas can continuously flow through both valves. 
       FIG. 3  depicts isolated flow paths for individual gaseous compounds. The paths are formed in the lid assembly  120  to separate the compounds within the lid assembly. Generally, each gaseous compound has a dedicated flow path, or, alternatively, the flow path may deliver more than one compound, for example, one precursor or oxidizing gas and one purge gas. For simplicity of description, embodiments of the invention are further described in terms of a three gaseous compound processing system  100  using for example, one precursor gas, one oxidizing gas, and one purge gas. Such processing system comprises at least two isolated flow paths. However, in other embodiments, the processing system  100  may comprise a different number of isolated flow paths and/or use a different number of gaseous compounds. 
     The first flow path comprises an inlet channel  153 A for a first gaseous compound (for example, aluminum precursor, such as at least one of trimethylaluminum (Al(CH 3 ) 3 ), triisopropoxyaluminum (Al(C 3 H 7 ) 3 ), and dimethylaluminumhydride (Al(CH 3 ) 2 H), as well as precursors having a chemical structure Al(R 1 )(R 2 )(R 3 ), where R 1 , R 2 , R 3  may be the same or different ligands, and the like), an inlet channel  124 A for a purge gas (for example, helium (He), argon (Ar), nitrogen (N 2 ), hydrogen (H 2 ), and the like), the high-speed valve  155 A, and an outlet channel  154 A. Similarly, the second flow path comprises an inlet channel  153 B for a second gaseous compound (for example, oxidizing gas, such as, ozone (O 3 ), oxygen (O 2 ), water (H 2 O) vapor, nitrous oxide (N 2 O), nitric oxide (NO), and the like, an inlet channel  124 B for the purge gas, the high-speed valve  155 B, and an outlet channel  154 B. The inlet channels  153 A,  153 B are generally each coupled at a first end thereof to a source (not shown) of an individual gaseous compound, as well as coupled at a second end thereof to the respective valve  155 A,  155 B. The inlet channels  124 A,  124 B similarly transfer one or more purge gases to the valves  155 A,  155 B. In one embodiment, a diameter of the gas channel  154 A increases towards the showerhead  130  to decrease the kinetic energy of the flowing gaseous compound. 
     In operation, in the depicted embodiment, the first gaseous is dosed (pulsed) using the high-speed valve  155 A and then directed to the reaction region  159  through the outlet channel  154 A (in the manifold block  150  and lid plate  122 ) and centrally located slotted openings  131 A,  131 B (discussed in reference to  FIG. 4 ) in the showerhead  130 . Similarly, the second gaseous compound is pulsed using the high-speed valve  155 B and then directed to the reaction region  159  through the outlet channel  154 B (in the manifold block  150  and lid plate  122 ), a sealed cavity  156 , and a plurality of apertures  133  in the showerhead  130 . As such, the first and second gaseous compounds are separated from one another within the lid assembly  120 . The cavity  156  can be sealed using, for example, o-ring seals  139 A,  139 B that are disposed in the channels  129 A,  129 B, respectively. 
     A dispersion plate  132  is disposed near the slotted openings  131 A,  131 B and deflects, both horizontally and vertically, a flow of the gaseous compound from the slotted openings  131 A,  131 B. The plate converts a substantially vertical flow of the compound into the partially horizontal flow and prevents the gaseous compound from impinging directly on the substrate. The dispersion plate  132  may be a part of the showerhead  130  or, alternatively, may be affixed to the showerhead. The dispersion plate  132  re-directs and decreases velocity of the gaseous compound. Without such re-direction, the impinging compound may sweep away (sputter) reactive molecules already disposed on the substrate. Further, the dispersion plate  132  prevents excess deposition onto regions of the substrate that oppose the openings  131 A,  131 B and, as such, facilitates uniform depositing of the film on the substrate. 
       FIG. 4  is a schematic, partial view of a portion of the showerhead  130  taken along an arrow  157  in  FIG. 3 . In one embodiment, the showerhead  130  comprises a plurality of apertures  133  disposed around the slotted openings  131 A,  131 B. In a further embodiment, the apertures  133  comprise nozzles  130 A ( FIG. 5 ) to provide a directional delivery of a gaseous compound to the substrate below. In one embodiment, the nozzles  130 A are angled relative to the upper surface of the support pedestal  111 . The apertures  133  and nozzles  130 A are sized and positioned to provide uniform distribution of the gaseous compound across the substrate. In one embodiment, the apertures  133  are formed on the entire surface of the showerhead  130 . In an alternative embodiment, the apertures  133  are formed substantially within a region opposing the support pedestal  111 . Although the openings  131 A,  131 B are shown having a generally circular form factor, the openings may have any other form factor that provides a desired pattern of a flow of a gaseous compound in the reaction region  159 . Further, in other embodiments, a number of the centrally located openings in the showerhead  130  may be either one or greater than two. 
     The dual exhaust system  50  comprises an exhaust channel  108  formed in the liner  107 , exhaust ports  117 A,  117 B) formed in a sidewall of the process chamber  101 , exhaust pumps  52 A,  52 B, and valves  55 A,  55 B (for example, electronic or pneumatic throttle valves and the like). In one embodiment, operation of the valves  55 A,  55 B is synchronized with operation of the high-speed valves  155 A,  155 B, for example, the valves  55 A,  55 B open and close contemporaneously with such actions of the high-speed valves. During the ALD process, each exhaust pump can be operated independently, and, preferably, is used to remove specific gaseous compounds. In one illustrative embodiment, one pump is used to remove an aluminum precursor and the other pump is used to remove an oxidizing gas, while both pumps are used simultaneously to remove the purge gas. 
     In this embodiment, a gaseous compound dosed into the chamber body  150  using the high-speed valve  155 A is exhausted from the process chamber  101  through the throttle valve  55 A that is open when the throttle valve  55 B is closed. Similarly, the gaseous compound dosed into the process chamber  101  using the high-speed valve  155 B is exhausted from the chamber through the throttle valve  55 B that is open when the throttle valve  55 A is closed. As such, the dual exhaust system  50  reduces mixing of gaseous compounds in the processing system  100 . In a further embodiment, an off-cycle throttle valve (i.e., temporarily closed valve) is not opened to the exhaust port immediately upon initiation of a pulse of a gaseous compound, but instead lags the pulse by a small time delay to reduce cross-contamination of the gaseous compounds within the dual exhaust system  50 . Likewise, once both throttle valves are open during the purge step, the throttle valve not associated with the subsequent pulse of the other gaseous compound is closed just prior to initiation of the pulse of the compound. Such synchronized operation of the dual exhaust system  50  is generally performed by a computer controller  70  or, alternatively, by the application specific controller. 
     The dual exhaust system  50  may further comprise a trap (not shown) disposed between the exhaust pump and throttle valve or between the chamber body  105  and throttle valve. The trap removes by-products of the ALD process from an exhaust stream thereby increasing performance and service intervals of the exhaust pump. The trap may be of any conventional type suited to collection of by-products generated during the ALD process. 
     Although the dual exhaust system is described, in an alternative embodiment, a single exhaust system may also be used. Such exhaust system may utilize, for example, the pump  52 A (or  52 B), the optional trap, and the throttle valve  55 A (or  55 B) coupled to the exhaust port  117 A (or  117 B). In this embodiment, during an ALD process, the exhaust pump is on and the throttle valve is open. 
     The ozonator  170  (i.e., source of ozone) is in fluid communication with a source of the precursor (for example, oxygen), as well as with inlet channels  124 A,  124 B in the manifold block  150 . Preferably, the ozonator  170  is disposed in close proximity to the processing system  100  (as shown in  FIG. 1 ), such that losses associated with delivery of ozone into the process chamber  101  are minimized. Ozonators are available, for example, from ASTeX® Products of Wilmington, Mass. 
     In another embodiment, the oxidizing gas may be produced using, for example, a remote source (not shown), such as a remote plasma generator (for example, DC, radio frequency (RF), microwave (MW) plasma generator, and the like). The remote source produces reactive species, which then are delivered to the process chamber  101 . Such remote sources are available from Advanced Energy Industries, Inc. of Fort Collins, Colo. and others. Alternatively, the oxidizing gas can be produced using a thermal gas break-down technique, a high-intensity light source (for example, UV or x-ray source), and the like. 
       FIG. 5  is a schematic, partial cross-sectional view of an alternative embodiment of the lid assembly  120  comprising the ozonator  170  coupled to the process chamber  101  and to a buffer cavity  520 , through a diverter valve  510 . Generally, the diverter valve  510  couples the ozonator  170  to the process chamber  101  contemporaneously with an open state (with respect to the inlets  124 A,  124 B) of the high-speed valves  155 A,  155 B. Accordingly, the diverter valve  510  couples the ozonator  170  to the buffer cavity  520  when the high-speed valves  155 A,  155 B are in closed state in respect to the inlets  124 A,  124 B. The buffer cavity  520  simulates a second process chamber and, as such, using the diverter valve  510 , ozone and/or other oxidizing gas can be produced continuously during the ALD process. 
     In one embodiment, the source  530  comprises an ampoule  531  containing a liquid aluminum precursor and a vaporizer  532 . The ampoule  531 , the vaporizer  532 , and delivering lines may each be heated (for example, using any conventional method of heating) to assist in vaporization of the liquid phase, as well as in preventing the vaporized precursor from condensing. Alternatively, the precursor may be pre-mixed with a solvent that reduces viscosity of the liquid phase, and then vaporized. A carrier gas, such as argon, helium (He), hydrogen (H 2 ), and the like may also be used to facilitate delivery of the precursor, in a form of a gaseous compound, to the process chamber  101 . 
       FIG. 6  is a schematic, partial cross-sectional view of another embodiment an ALD process chamber  301  comprising a circumferential gas delivery assembly  300  and an upper gas delivery assembly  350 . 
     The circumferential gas delivery assembly  300  is disposed in a chamber body  305  and comprises an annular gas ring  310  having at least two separate gas distribution channels  316 ,  318  to supply at least two separate gaseous compounds into the process chamber  301 . Each gas distribution channel is coupled to a source of a gaseous compound and comprises a plurality of ports adapted for receiving gas nozzles. As such, each gas distribution channel is in fluid communication with a plurality of circumferentially mounted gas nozzles. In one embodiment, alternating ports are connected to one of the gas distribution channels, while the other ports are connected to the other channel. In the depicted embodiment, a gaseous compound from the source  352  is distributed through the nozzles  302  of the gas distribution channel  316 . Similarly, a gaseous compound from the source  358  is distributed through the nozzles  304  of the gas distribution channel  318 . 
     The upper gas delivery assembly  350  is disposed in the lid assembly  320  and comprises a center gas feed  312  and a nozzle  306 . Generally, the center gas feed  312  is in fluid communication with two or more sources  364 ,  370  of other gaseous compounds. 
     Such embodiment provides, through the peripheral gas nozzles  302 ,  304  and the central gas nozzle  306 , three separate passes for the gaseous compounds (for example, metal-containing precursor, oxidizing gas, and inert gas) in the process chamber  101 . Further, different gaseous compounds can be introduced into a reaction volume at select locations within the chamber. In the depicted embodiment, the gaseous compounds are dosed using four high-speed valves  354 A- 354 D each having one intake port and one outlet port. In other embodiments, during a cyclical deposition process, at least one of the gaseous compounds may be flown into the process chamber  101  continuously. In further embodiments, the gas delivery assembly  300  may comprise more than one annular gas ring  310  or the ring may have more than two gas distribution channels, as well as the upper gas delivery assembly  350  may comprise more than one gas nozzle  306 . 
     Generally, the gas distribution ring  310  and the nozzles  302 ,  304 , and  306  are made of a process-compatible material (for example, aluminum, stainless steel, and the like), as well as are supplied with conventional process-compatible fluid-tight seals (not shown), such as o-rings and the like. The seals isolate the gas distribution channels  316 ,  318  from one another. In one embodiment, the nozzles  302 ,  304 , and  306  are threaded in the respective ports to provide fluid-tight couplings therein, as well as means facilitating prompt replacement of the nozzles. A form factor of the restricting orifice of a nozzle can be selected for desired dispersion of gaseous compound within the chamber. 
       FIG. 7  is a schematic, cross-sectional view of still another embodiment of a process chamber  700  for performing the cyclical deposition processes. The process chamber  700  comprises a chamber body  702  and gas distribution system  730 . 
     The chamber body  702  houses a substrate support  712  that supports a substrate  710  in the chamber  700 . The substrate support  712  comprises an embedded heater element  722 . A temperature sensor  726  (for example, a thermocouple) is embedded in the substrate support  712  to monitor the temperature of the substrate support  712 . Alternatively, the substrate  710  may be heated using a source of radiant heat (not shown), such as quartz lamps and the like. Further, the chamber body  702  comprises an opening  708  in a sidewall  704  providing access for a robot to deliver and retrieve the substrate  710 , as well as exhaust ports  717 A,  717 B (only port  717 A is shown) that are fluidly coupled to the dual exhaust system  50  (discussed in reference to  FIG. 1  above). 
     The gas distribution system  730  generally comprises a mounting plate  733 , a showerhead  770 , and a blocker plate  760  and provides at least two separate paths for gaseous compounds into a reaction region  728  between the showerhead  770  and the substrate support  712 . In the depicted embodiment, the gas distribution system  730  also serves as a lid of the process chamber  700 . However, in other embodiments, the gas distribution system  730  may be a portion of a lid assembly of the chamber  700 . The mounting plate  733  comprises a channel  737  and a channel  743 , as well as a plurality of channels  746  that are formed to control the temperature of the gaseous compounds (for example, by providing either a cooling or heating fluid into the channels). Such control is used to prevent decomposing or condensation of the compounds. Each of the channels  737 ,  743  provides a separate path for a gaseous compound within the gas distribution system  730 . 
       FIG. 8  is a schematic, partial cross-sectional view of one embodiment of the showerhead  770 . The showerhead  770  comprises a plate  772  that is coupled to a base  780 . The plate  772  has a plurality of openings  774 , while the base  780  comprises a plurality of columns  782  and a plurality of grooves  784 . The columns  782  and grooves  784  comprise openings  783  and  785 , respectively. The plate  772  and base  780  are coupled such, that the openings  783  in the base align with the openings  774  in the plate to form a path for a first gaseous compound through the showerhead  770 . The grooves  784  are in fluid communication with one another and, together, facilitate a separate path for a second gaseous compound into the reaction region  728  through the openings  785 . In an alternative embodiment ( FIG. 9 ), the showerhead  771  comprises the plate  750  having the grooves  752  and columns  754 , and a base  756  comprising a plurality of openings  758  and  759 . In either embodiment, contacting surfaces of the plate and base may be brazed together to prevent mixing of the gaseous compounds within the showerhead. 
     Each of the channels  737  and  743  is coupled to a source (not shown) of the respective gaseous compound. Further, the channel  737  directs the first gaseous compound into a volume  731 , while the channel  743  is coupled to a plenum  775  that provides a path for the second gaseous compound to the grooves  784 . The blocker plate  760  comprises a plurality of openings  762  that facilitate fluid communication between the volume  731 , plenum  729 , and a plurality of openings  774  that disperse the first gaseous compound into the reaction region  728 . As such, the gas distribution system  730  provides separate paths for the gaseous compounds delivered to the channels  737  and  743 . 
     In one embodiment, the blocker plate  760  and the showerhead  770  are electrically isolated from one another, the mounting plate  733 , and chamber body  702  using insulators (not shown) formed of, for example, quartz, ceramic, and like. The insulators are generally disposed between the contacting surfaces in annular peripheral regions thereof to facilitate electrical biasing of these components and, as such, enable plasma enhanced cyclical deposition techniques, for example, plasma enhanced ALD (PEALD) processing. 
     In one exemplary embodiment, a power source may be coupled, for example, through a matching network (both not shown), to the blocker plate  760  when the showerhead  770  and chamber body  702  are coupled to a ground terminal. The power source may be either a radio-frequency (RF) or direct current (DC) power source that energizes the gaseous compound in the plenum  729  to form a plasma. Alternatively, the power source may be coupled to the showerhead  770  when the substrate support  712  and chamber body  702  are coupled to the ground terminal. In this embodiment, the gaseous compounds may be energized to form a plasma in the reaction region  728 . As such, the plasma may be selectively formed either between the blocker plate  760  and showerhead  770 , or between the showerhead  770  and substrate support  712 . Such electrical biasing schemes are disclosed in commonly assigned U.S. patent application Ser. No. 10/354,214, filed Jan. 27, 2003 (Attorney docket number 7660), which is incorporated herein by reference. 
     In still another embodiment, the blocker plate  760  and showerhead  770  may be coupled to separate outputs of the matching network to produce an electrical field gradient to direct the plasma species through the openings in the showerhead  770  towards the substrate  710 . In yet another alternative embodiment, to produce the electrical field gradient, the blocker plate  760  and showerhead  770  may be individually coupled to separate power sources each using a separate matching network. 
     Referring to  FIG. 1 , the controller  70  comprises a central processing unit (CPU)  123 , a memory  116 , and a support circuit  114 . The CPU  123  may be of any form of a general-purpose computer processor that is used in an industrial setting. The software routines can be stored in the memory  116 , such as random access memory, read only memory, floppy or hard disk drive, or other form of digital storage. The support circuit  114  is coupled to the CPU  123  in a conventional manner and may comprise cache, clock circuits, input/output sub-systems, power supplies, and the like. The software routines, when executed by the CPU  123 , transform the CPU into a specific purpose computer (controller)  70  that controls the reactor  100  such that the processes are performed in accordance with the present invention. The software routines may also be stored and/or executed by a second controller (not shown) that is located remotely from the reactor  100 . 
       FIG. 10  is a schematic, top plan view of an exemplary integrated processing system  1000  configured to form a film stack having an aluminum oxide layer. One such integrated processing system is a CENTURA® system that is available from Applied Materials, Inc. of Santa Clara, Calif. The particular embodiment of the system  1000  is provided to illustrate the invention and should not be used to limit the scope of the invention. 
     The system  1000  generally includes load lock chambers  1022  that protect the vacuumed interior of the system  1000  from contaminants. A robot  1030  having a blade  1034  is used to transfer the substrates between the load lock chambers  1022  and process chambers  1010 ,  1012 ,  1014 ,  1016 ,  1020 . One or more of the chambers is an aluminum oxide chamber, such as the process chambers described above in reference to  FIGS. 1-9 . Further, one or more chambers may be adapted to deposit a material used during fabrication of integrated circuits, as well as be a cleaning chamber (for example, a plasma cleaning chamber) used to remove unwanted products from a substrate. Example of such cleaning chamber is the PRECLEAN II™ chamber available from Applied Materials, Inc. of Santa Clara, Calif. Optionally, one or more of the chambers  1010 ,  1012 ,  1014 ,  1016 ,  1020  may be an annealing chamber or other thermal processing chamber, for example, the RADIANCE™ chamber available from Applied Materials, Inc. of Santa Clara, Calif. Further, the system  1000  may comprise one or more metrology chambers  1018  connected thereto using, for example, a factory interface  1024 . Alternatively, the system  1000  may comprise other types of process chambers. 
     One example of a possible configuration of the integrated processing system  1000  includes a load lock chamber (chamber  1022 ), an aluminum oxide cyclical deposition chamber (chamber  1010 ), a first dielectric deposition chamber (chamber  1012 ), a metal deposition chamber (chamber  1014 ), a second dielectric deposition chamber (chamber  1016 ), and an annealing chamber (chamber  1020 ). 
     The processing system  1000  may be used to deposit with low film contamination and minimal gas phase reactions between the precursors various metal-containing films, for example, aluminum oxide, copper, titanium, tantalum, tungsten films, and the like. In one illustrative application, the processing system  1000  is used to deposit an aluminum oxide film. Various cyclical deposition processes used to deposit the aluminum oxide and other films using the processing system  1000  are described in commonly assigned U.S. patent application Ser. No. 60/357,382, filed Feb. 15, 2002, which is incorporated herein by reference. 
     Although the foregoing discussion referred to the apparatus for performing cyclical deposition processes, other processing apparatuses can benefit from the invention. The invention can be practiced in other semiconductor processing systems wherein the parameters may be adjusted to achieve acceptable characteristics by those skilled in the art by utilizing the teachings disclosed herein without departing from the spirit of the invention. 
     While foregoing is directed to the illustrative embodiment of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.