Patent Publication Number: US-2009233004-A1

Title: Method and system for depositing silicon carbide film using a gas cluster ion beam

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is related to pending U.S. patent application Ser. No. 11/864,330, entitled “METHOD FOR DIRECTIONAL DEPOSITION USING A GAS CLUSTER ION BEAM” (EP-121), filed on Sep. 28, 2007; and pending U.S. patent application Ser. No. 11/864,961, entitled “METHOD FOR DEPOSITING FILMS USING GAS CLUSTER ION BEAM PROCESSING” (EP-142), filed on Sep. 29, 2007. The entire content of these applications is herein incorporated by reference in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a method for performing thin film deposition using a gas cluster ion beam (GCIB), and more particularly to a method for depositing silicon carbide-containing films on a substrate using a GCIB. 
     2. Description of Related Art 
     Gas-cluster ion beams (GCIB&#39;s) are used for etching, cleaning, smoothing, and forming thin films. For purposes of this discussion, gas clusters are nano-sized aggregates of materials that are gaseous under conditions of standard temperature and pressure. Such gas clusters may consist of aggregates including a few to several thousand molecules, or more, that are loosely bound together. The gas clusters can be ionized by electron bombardment, which permits the gas clusters to be formed into directed beams of controllable energy. Such cluster ions each typically carry positive charges given by the product of the magnitude of the electronic charge and an integer greater than or equal to one that represents the charge state of the cluster ion. 
     The larger sized cluster ions are often the most useful because of their ability to carry substantial energy per cluster ion, while yet having only modest energy per individual molecule. The ion clusters disintegrate on impact with the substrate. Each individual molecule in a particular disintegrated ion cluster carries only a small fraction of the total cluster energy. Consequently, the impact effects of large ion clusters are substantial, but are limited to a very shallow surface region. This makes gas cluster ions effective for a variety of surface modification processes, but without the tendency to produce deeper sub-surface damage that is characteristic of conventional ion beam processing. 
     Conventional cluster ion sources produce cluster ions having a wide size distribution scaling with the number of molecules in each cluster that may reach several thousand molecules). Clusters of atoms can be formed by the condensation of individual gas atoms (or molecules) during the adiabatic expansion of high pressure gas from a nozzle into a vacuum. A skimmer with a small aperture strips divergent streams from the core of this expanding gas flow to produce a collimated beam of clusters. Neutral clusters of various sizes are produced and held together by weak inter-atomic forces known as Van der Waals forces. This method has been used to produce beams of clusters from a variety of gases, such as helium, neon, argon, krypton, xenon, nitrogen, oxygen, carbon dioxide, sulfur hexafluoride, nitric oxide, nitrous oxide, and mixtures of these gases. 
     Several emerging applications for GCIB processing of substrates on an industrial scale are in the semiconductor field. Although GCIB processing of a substrate is performed using a wide variety of gas-cluster source gases, many of which are inert gases, many semiconductor processing applications use reactive source gases, sometimes in combination or mixture with inert or noble gases, to form the GCIB. 
     SUMMARY OF THE INVENTION 
     The invention relates to a method for performing thin film deposition using a gas cluster ion beam (GCIB). 
     The invention further relates to a method for depositing silicon carbide-containing films on a substrate using a GCIB. 
     According to one embodiment, a method of, and computer readable medium for, depositing material on a substrate is described. The method comprises maintaining a reduced-pressure environment around a substrate holder for holding a substrate having a surface, and holding the substrate securely within the reduced-pressure environment. Additionally, the method comprises forming a gas cluster ion beam (GCIB) from a pressurized gas comprising a compound having silicon (Si) and carbon (C), accelerating the GCIB to the reduced-pressure environment, and irradiating the accelerated GCIB onto at least a portion of the surface of the substrate to form a thin film containing silicon and carbon, wherein the carbon content is greater than or equal to 10%. Further, the compound may possess a Si—C bond. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the accompanying drawings: 
         FIG. 1  is an illustration of a GCIB processing system; 
         FIG. 2  is another illustration of a GCIB processing system; 
         FIG. 3  is an illustration of an ionization source for a GCIB processing system; and 
         FIG. 4  illustrates a method of depositing material on a substrate according to an embodiment. 
     
    
    
     DETAILED DESCRIPTION OF SEVERAL EMBODIMENTS 
     A method and system for performing material infusion into a substrate using a gas cluster ion beam (GCIB) is disclosed in various embodiments. However, one skilled in the relevant art will recognize that the various embodiments may be practiced without one or more of the specific details, or with other replacement and/or additional methods, materials, or components. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of various embodiments of the invention. Similarly, for purposes of explanation, specific numbers, materials, and configurations are set forth in order to provide a thorough understanding of the invention. Nevertheless, the invention may be practiced without specific details. Furthermore, it is understood that the various embodiments shown in the figures are illustrative representations and are not necessarily drawn to scale. 
     In the description and claims, the terms “coupled” and “connected,” along with their derivatives, are used. It should be understood that these terms are not intended as synonyms for each other. Rather, in particular embodiments, “connected” may be used to indicate that two or more elements are in direct physical or electrical contact with each other while “coupled” may further mean that two or more elements are not in direct contact with each other, but yet still co-operate or interact with each other. 
     Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure, material, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention, but do not denote that they are present in every embodiment. Thus, the appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily referring to the same embodiment of the invention. Furthermore, the particular features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments. Various additional layers and/or structures may be included and/or described features may be omitted in other embodiments. 
     As described above, there is a general need for depositing material on a surface of a substrate using a GCIB, as well as selectively depositing material on only chosen surfaces of a substrate using a GCIB. By adjusting the orientation of the substrate relative to the GCIB, material deposition can proceed on surfaces that are substantially perpendicular to the incident GCIB while material deposition can be avoided or reduced on surfaces that are substantially parallel with the incident GCIB. Moreover, one or more properties of the GCIB, including the beam composition, can be adjusted or alternated in order to directionally deposit successive material films having differing properties from one layer to an adjacent layer. 
     Furthermore, there exists a growing need for depositing silicon carbide-containing films on a substrate. However, the inventors have recognized that conventional gas mixtures for depositing silicon carbide on a substrate produce low carbon content silicon carbide-containing films. For example, silane (SiH 4 ) with methane (CH 4 ) or ethane (C 2 H 6 ) have been found to produce low carbon content silicon carbide-containing films (e.g., ˜5% C). 
     Therefore, according to one embodiment, a method of depositing material on a substrate is described. The method comprises maintaining a reduced-pressure environment around a substrate holder for holding a substrate having a surface, and holding the substrate securely within the reduced-pressure environment. Additionally, the method comprises forming a gas cluster ion beam (GCIB) from a pressurized gas comprising a compound having silicon (Si) and carbon (C), accelerating the GCIB to the reduced-pressure environment, and irradiating the accelerated GCIB onto at least a portion of the surface of the substrate to form a thin film containing silicon and carbon, wherein the carbon content is greater than or equal to 10%. Further, the compound may possess a Si—C bond. 
     According to an embodiment, a GCIB processing system  100  is depicted in  FIG. 1  comprising a vacuum vessel  102 , substrate holder  150 , upon which a substrate  152  to be processed is affixed and around which a reduced-pressure environment is maintained during substrate processing, and vacuum pumping systems  170 A,  170 B, and  170 C. Substrate  152  can be a semiconductor substrate, a wafer, a flat panel display (FPD), a liquid crystal display (LCD), or any other workpiece. GCIB processing system  100  is configured to produce a GCIB for treating substrate  152 . 
     Referring still to GCIB processing system  100  in  FIG. 1 , the vacuum vessel  102  comprises three communicating chambers, namely, a source chamber  104 , an ionization/acceleration chamber  106 , and a processing chamber  108  to provide a reduced-pressure enclosure. The three chambers are evacuated to suitable operating pressures by vacuum pumping systems  170 A,  170 B, and  170 C, respectively. In the three communicating chambers  104 ,  106 ,  108 , a gas cluster beam can be formed in the first chamber (source chamber  104 ), while a gas cluster ion beam can be formed in the second chamber (ionization/acceleration chamber  106 ) wherein the gas cluster beam is ionized and accelerated, and then in the third chamber (processing chamber  108 ) the accelerated gas cluster ion beam may be utilized to treat substrate  152 . 
     As shown in  FIG. 1 , GCIB processing system  100  can comprise one or more gas sources configured to introduce one or more gases or mixture of gases to vacuum vessel  102 . For example, a first gas composition stored in a first gas source  111  is admitted under pressure through a first gas control valve  113 A to a gas metering valve or valves  113 . Additionally, for example, a second gas composition stored in a second gas source  112  is admitted under pressure through a second gas control valve  113 B to the gas metering valve or valves  113 . Furthermore, for example, the first gas composition or the second gas composition or both can comprise a film forming gas composition. Further yet, for example, the first gas composition or second gas composition or both can include a condensable inert gas, carrier gas or dilution gas. For example, the inert gas, carrier gas or dilution gas can include a noble gas, i.e., He, Ne, Ar, Kr, Xe, or Rn. 
     Furthermore, the first gas source  111  and the second gas source  112  may be utilized either alone or in combination with one another to produce ionized clusters. The film forming composition can comprise a film precursor or precursors that include the principal atomic or molecular species of the film desired to be produced on the substrate. Additionally, the film forming composition can include a reducing agent that assists with the reduction of a film precursor on a substrate. For instance, the reducing agent or agents may react with a part of or all of a film precursor on the substrate. Additionally yet, the film forming composition can include a polymerizing agent that may assist with the polymerization of a film precursor on the substrate. 
     The high pressure, condensable gas comprising the first gas composition or the second gas composition or both is introduced through gas feed tube  114  into stagnation chamber  116  and is ejected into the substantially lower pressure vacuum through a properly shaped nozzle  110 . As a result of the expansion of the high pressure, condensable gas from the stagnation chamber  116  to the lower pressure region of the source chamber  104 , the gas velocity accelerates to supersonic speeds and gas cluster beam  118  emanates from nozzle  110 . 
     The inherent cooling of the jet as static enthalpy is exchanged for kinetic energy, which results from the expansion in the jet, causes a portion of the gas jet to condense and form a gas cluster beam  118  having clusters, each consisting of from several to several thousand weakly bound atoms or molecules. A gas skimmer  120 , positioned downstream from the exit of the nozzle  110  between the source chamber  104  and ionization/acceleration chamber  106 , partially separates the gas molecules on the peripheral edge of the gas cluster beam  118 , that may not have condensed into a cluster, from the gas molecules in the core of the gas cluster beam  118 , that may have formed clusters. Among other reasons, this selection of a portion of gas cluster beam  118  can lead to a reduction in the pressure in the downstream regions where higher pressures may be detrimental (e.g., ionizer  122 , and processing chamber  108 ). Furthermore, gas skimmer  120  defines an initial dimension for the gas cluster beam entering the ionization/acceleration chamber  106 . 
     After the gas cluster beam  118  has been formed in the source chamber  104 , the constituent gas clusters in gas cluster beam  118  are ionized by ionizer  122  to form GCIB  128 . The ionizer  122  may include an electron impact ionizer that produces electrons from one or more filaments  124 , which are accelerated and directed to collide with the gas clusters in the gas cluster beam  118  inside the ionization/acceleration chamber  106 . Upon collisional impact with the gas cluster, electrons of sufficient energy eject electrons from molecules in the gas clusters to generate ionized molecules. The ionization of gas clusters can lead to a population of charged gas cluster ions, generally having a net positive charge. 
     As shown in  FIG. 1 , beam electronics  130  are utilized to ionize, extract, accelerate, and focus the GCIB  128 . The beam electronics  130  include a filament power supply  136  that provides voltage V F  to heat the ionizer filament  124 . 
     Additionally, the beam electronics  130  include a set of suitably biased high voltage electrodes  126  in the ionization/acceleration chamber  106  that extracts the cluster ions from the ionizer  122 . The high voltage electrodes  126  then accelerate the extracted cluster ions to a desired energy and focus them to define GCIB  128 . The kinetic energy of the cluster ions in GCIB  128  typically ranges from about 1000 electron volts (1 keV) to several tens of keV. For example, GCIB  128  can be accelerated to 1 to 70 keV. 
     As illustrated in  FIG. 1 , the beam electronics  130  further include an anode power supply  134  that provides voltage V A  to an anode of ionizer  122  for accelerating electrons emitted from filament  124  and causing the electrons to bombard the gas clusters in gas cluster beam  118 , which produces cluster ions. 
     Additionally, as illustrated in  FIG. 1 , the beam electronics  130  include an extraction power supply  138  that provides voltage V E  to bias at least one of the high voltage electrodes  126  to extract ions from the ionizing region of ionizer  122  and to form the GCIB  128 . For example, extraction power supply  138  provides a voltage to a first electrode of the high voltage electrodes  126  that is less than or equal to the anode voltage of ionizer  122 . 
     Furthermore, the beam electronics  130  can include an accelerator power supply  140  that provides voltage V Acc  to bias one of the high voltage electrodes  126  with respect to the ionizer  122  so as to result in a total GCIB acceleration energy equal to about V Acc  electron volts (eV). For example, accelerator power supply  140  provides a voltage to a second electrode of the high voltage electrodes  126  that is less than or equal to the anode voltage of ionizer  122  and the extraction voltage of the first electrode. 
     Further yet, the beam electronics  130  can include lens power supplies  142 ,  144  that may be provided to bias some of the high voltage electrodes  126  with potentials (e.g., V L1  and V L2 ) to focus the GCIB  128 . For example, lens power supply  142  can provide a voltage to a third electrode of the high voltage electrodes  126  that is less than or equal to the anode voltage of ionizer  122 , the extraction voltage of the first electrode, and the accelerator voltage of the second electrode, and lens power supply  144  can provide a voltage to a fourth electrode of the high voltage electrodes  126  that is less than or equal to the anode voltage of ionizer  122 , the extraction voltage of the first electrode, the accelerator voltage of the second electrode, and the first lens voltage of the third electrode. 
     Note that many variants on both the ionization and extraction schemes may be used. While the scheme described here is useful for purposes of instruction, another extraction scheme involves placing the ionizer and the first element of the extraction electrode(s) (or extraction optics) at V acc . This typically requires fiber optic programming of control voltages for the ionizer power supply, but creates a simpler overall optics train. The invention described herein is useful regardless of the details of the ionizer and extraction lens biasing. 
     A beam filter  146  in the ionization/acceleration chamber  106  downstream of the high voltage electrodes  126  can be utilized to eliminate monomers, or monomers and light cluster ions from the GCIB  128  to define a filtered process GCIB  128 A that enters the processing chamber  108 . In one embodiment, the beam filter  146  substantially reduces the number of clusters having 100 or less atoms or molecules or both. The beam filter may comprise a magnet assembly for imposing a magnetic field across the GCIB  128  to aid in the filtering process. 
     Referring still to  FIG. 1 , a beam gate  148  is disposed in the path of GCIB  128  in the ionization/acceleration chamber  106 . Beam gate  148  has an open state in which the GCIB  128  is permitted to pass from the ionization/acceleration chamber  106  to the processing chamber  108  to define process GCIB  128 A, and a closed state in which the GCIB  128  is blocked from entering the processing chamber  108 . A control cable conducts control signals from control system  190  to beam gate  148 . The control signals controllably switch beam gate  148  between the open or closed states. 
     The process GCIB  128 A is accelerated from the ionization/acceleration chamber  106  into the reduced-pressure environment around the substrate holder  150  in processing chamber  108 . A substrate  152 , which may be a wafer or semiconductor wafer, a flat panel display (FPD), a liquid crystal display (LCD), or other substrate to be processed by GCIB processing, is held securely within the reduced-pressure environment and is disposed in the path of the process GCIB  128 A in the processing chamber  108 . Because most applications contemplate the processing of large substrates with spatially uniform results, a scanning system may be desirable to uniformly scan the process GCIB  128 A across large areas to produce spatially homogeneous results. 
     An X-scan actuator  160  provides linear motion of the substrate holder  150  in the direction of X-scan motion (into and out of the plane of the paper). A Y-scan actuator  162  provides linear motion of the substrate holder  150  in the direction of Y-scan motion  164 , which is typically orthogonal to the X-scan motion. The combination of X-scanning and Y-scanning motions translates the substrate  152 , held by the substrate holder  150 , in a raster-like scanning motion through process GCIB  128 A to cause a uniform (or otherwise programmed) irradiation of a surface of the substrate  152  by the process GCIB  128 A for processing of the substrate  152 . 
     The substrate holder  150  disposes the substrate  152  at an angle with respect to the axis of the process GCIB  128 A so that the process GCIB  128 A has an angle of beam incidence  166  with respect to a substrate  152  surface. The angle of beam incidence  166  may be 90 degrees or some other angle, but is typically 90 degrees or near 90 degrees. During Y-scanning, the substrate  152  and the substrate holder  150  move from the shown position to the alternate position “A” indicated by the designators  152 A and  150 A, respectively. Notice that in moving between the two positions, the substrate  152  is scanned through the process GCIB  128 A, and in both extreme positions, is moved completely out of the path of the process GCIB  128 A (over-scanned). Though not shown explicitly in  FIG. 1 , similar scanning and over-scan is performed in the (typically) orthogonal X-scan motion direction (in and out of the plane of the paper). 
     A beam current sensor  180  may be disposed beyond the substrate holder  150  in the path of the process GCIB  128 A so as to intercept a sample of the process GCIB  128 A when the substrate holder  150  is scanned out of the path of the process GCIB  128 A. The beam current sensor  180  is typically a faraday cup or the like, closed except for a beam-entry opening, and is typically affixed to the wall of the vacuum vessel  102  with an electrically insulating mount  182 . 
     As shown in  FIG. 1 , control system  190  connects to the X-scan actuator  160  and the Y-scan actuator  162  through electrical cable and controls the X-scan actuator  160  and the Y-scan actuator  162  in order to place the substrate  152  into or out of the process GCIB  128 A and to scan the substrate  152  uniformly relative to the process GCIB  128 A to achieve desired processing of the substrate  152  by the process GCIB  128 A. Control system  190  receives the sampled beam current collected by the beam current sensor  180  by way of an electrical cable and, thereby, monitors the GCIB and controls the GCIB dose received by the substrate  152  by removing the substrate  152  from the process GCIB  128 A when a predetermined dose has been delivered. 
     In the embodiment shown in  FIG. 2 , the GCIB processing system  200  can be similar to the embodiment of  FIG. 1  and further comprise a X-Y positioning table  253  operable to hold and move a substrate  252  in two axes, effectively scanning the substrate  252  relative to the process GCIB  128 A. For example, the X-motion can include motion into and out of the plane of the paper, and the Y-motion can include motion along direction  264 . 
     The process GCIB  128 A impacts the substrate  252  at a projected impact region  286  on a surface of the substrate  252 , and at an angle of beam incidence  266  with respect to the substrate  252  surface. By X-Y motion, the X-Y positioning table  253  can position each portion of a surface of the substrate  252  in the path of process GCIB  128 A so that every region of the surface may be made to coincide with the projected impact region  286  for processing by the process GCIB  128 A. An X-Y controller  262  provides electrical signals to the X-Y positioning table  253  through an electrical cable for controlling the position and velocity in each of X-axis and Y-axis directions. The X-Y controller  262  receives control signals from, and is operable by, control system  190  through an electrical cable. X-Y positioning table  253  moves by continuous motion or by stepwise motion according to conventional X-Y table positioning technology to position different regions of the substrate  252  within the projected impact region  286 . In one embodiment, X-Y positioning table  253  is programmably operable by the control system  190  to scan, with programmable velocity, any portion of the substrate  252  through the projected impact region  286  for GCIB processing by the process GCIB  128 A. 
     The substrate holding surface  254  of positioning table  253  is electrically conductive and is connected to a dosimetry processor operated by control system  190 . An electrically insulating layer  255  of positioning table  253  isolates the substrate  252  and substrate holding surface  254  from the base portion  260  of the positioning table  253 . Electrical charge induced in the substrate  252  by the impinging process GCIB  128 A is conducted through substrate  252  and substrate holding surface  254 , and a signal is coupled through the positioning table  253  to control system  190  for dosimetry measurement. Dosimetry measurement has integrating means for integrating the GCIB current to determine a GCIB processing dose. Under certain circumstances, a target-neutralizing source (not shown) of electrons, sometimes referred to as electron flood, may be used to neutralize the process GCIB  128 A. In such case, a Faraday cup (not shown) may be used to assure accurate dosimetry despite the added source of electrical charge, the reason being that typical Faraday cups allow only the high energy positive ions to enter and be measured. 
     In operation, the control system  190  signals the opening of the beam gate  148  to irradiate the substrate  252  with the process GCIB  128 A. The control system  190  monitors measurements of the GCIB current collected by the substrate  252  in order to compute the accumulated dose received by the substrate  252 . When the dose received by the substrate  252  reaches a predetermined dose, the control system  190  closes the beam gate  148  and processing of the substrate  252  is complete. Based upon measurements of the GCIB dose received for a given area of the substrate  252 , the control system  190  can adjust the scan velocity in order to achieve an appropriate beam dwell time to treat different regions of the substrate  252 . 
     Alternatively, the process GCIB  128 A may be scanned at a constant velocity in a fixed pattern across the surface of the substrate  252 ; however, the GCIB intensity is modulated (may be referred to as Z-axis modulation) to deliver an intentionally non-uniform dose to the sample. The GCIB intensity may be modulated in the GCIB processing system  200  by any of a variety of methods, including varying the gas flow from a GCIB source supply; modulating the ionizer  122  by either varying a filament voltage V F  or varying an anode voltage V A ; modulating the lens focus by varying lens voltages V L1  and/or V L2 ; or mechanically blocking a portion of the gas cluster ion beam with a variable beam block, adjustable shutter, or variable aperture. The modulating variations may be continuous analog variations or may be time modulated switching or gating. 
     The processing chamber  108  may further include an in-situ metrology system. For example, the in-situ metrology system may include an optical diagnostic system having an optical transmitter  280  and optical receiver  282  configured to illuminate substrate  252  with an incident optical signal  284  and to receive a scattered optical signal  288  from substrate  252 , respectively. The optical diagnostic system comprises optical windows to permit the passage of the incident optical signal  284  and the scattered optical signal  288  into and out of the processing chamber  108 . Furthermore, the optical transmitter  280  and the optical receiver  282  may comprise transmitting and receiving optics, respectively. The optical transmitter  280  receives, and is responsive to, controlling electrical signals from the control system  190 . The optical receiver  282  returns measurement signals to the control system  190 . 
     The in-situ metrology system may comprise any instrument configured to monitor the progress of the GCIB processing. According to one embodiment, the in-situ metrology system may constitute an optical scatterometry system. The scatterometry system may include a scatterometer, incorporating beam profile ellipsometry (ellipsometer) and beam profile reflectometry (reflectometer), commercially available from Therma-Wave, Inc. (1250 Reliance Way, Fremont, Calif. 94539) or Nanometrics, Inc. (1550 Buckeye Drive, Milpitas, Calif. 95035). 
     For instance, the in-situ metrology system may include an integrated Optical Digital Profilometry (iODP) scatterometry module configured to measure process performance data resulting from the execution of a treatment process in the GCIB processing system  200 . The metrology system may, for example, measure or monitor metrology data resulting from the treatment process. The metrology data can, for example, be utilized to determine process performance data that characterizes the treatment process, such as a process rate, a relative process rate, a feature profile angle, a critical dimension, a feature thickness or depth, a feature shape, etc. For example, in a process for directionally depositing material on a substrate, process performance data can include a critical dimension (CD), such as a top, middle or bottom CD in a feature (i.e., via, line, etc.), a feature depth, a material thickness, a sidewall angle, a sidewall shape, a deposition rate, a relative deposition rate, a spatial distribution of any parameter thereof, a parameter to characterize the uniformity of any spatial distribution thereof, etc. Operating the X-Y positioning table  253  via control signals from control system  190 , the in-situ metrology system can map one or more characteristics of the substrate  252 . 
     Control system  190  comprises a microprocessor, memory, and a digital I/O port capable of generating control voltages sufficient to communicate and activate inputs to GCIB processing system  100  (or  200 ) a as well as monitor outputs from GCIB processing system  100  (or  200 ). Moreover, control system  190  can be coupled to and can exchange information with vacuum pumping systems  170 A,  170 B, and  170 C, first gas source  111 , second gas source  112 , first gas control valve  113 A, second gas control valve  113 B, beam electronics  130 , beam filter  146 , beam gate  148 , the X-scan actuator  160 , the Y-scan actuator  162 , and beam current sensor  180 . For example, a program stored in the memory can be utilized to activate the inputs to the aforementioned components of GCIB processing system  100  according to a process recipe in order to perform a GCIB process on substrate  152 . 
     However, the control system  190  may be implemented as a general purpose computer system that performs a portion or all of the microprocessor based processing steps of the invention in response to a processor executing one or more sequences of one or more instructions contained in a memory. Such instructions may be read into the controller memory from another computer readable medium, such as a hard disk or a removable media drive. One or more processors in a multi-processing arrangement may also be employed as the controller microprocessor to execute the sequences of instructions contained in main memory. In alternative embodiments, hard-wired circuitry may be used in place of or in combination with software instructions. Thus, embodiments are not limited to any specific combination of hardware circuitry and software. 
     The control system  190  can be used to configure any number of processing elements, as described above, and the control system  190  can collect, provide, process, store, and display data from processing elements. The control system  190  can include a number of applications, as well as a number of controllers, for controlling one or more of the processing elements. For example, control system  190  can include a graphic user interface (GUI) component (not shown) that can provide interfaces that enable a user to monitor and/or control one or more processing elements. 
     Control system  190  can be locally located relative to the GCIB processing system  100  (or  200 ), or it can be remotely located relative to the GCIB processing system  100  (or  200 ). For example, control system  190  can exchange data with GCIB processing system  100  using a direct connection, an intranet, and/or the internet. Control system  190  can be coupled to an intranet at, for example, a customer site (i.e., a device maker, etc.), or it can be coupled to an intranet at, for example, a vendor site (i.e., an equipment manufacturer). Alternatively or additionally, control system  190  can be coupled to the internet. Furthermore, another computer (i.e., controller, server, etc.) can access control system  190  to exchange data via a direct connection, an intranet, and/or the internet. 
     Substrate  152  (or  252 ) can be affixed to the substrate holder  150  (or substrate holder  250 ) via a clamping system (not shown), such as a mechanical clamping system or an electrical clamping system (e.g., an electrostatic clamping system). Furthermore, substrate holder  150  (or  250 ) can include a heating system (not shown) or a cooling system (not shown) that is configured to adjust and/or control the temperature of substrate holder  150  (or  250 ) and substrate  152  (or  252 ). 
     Vacuum pumping systems  170 A,  170 B, and  170 C can include turbo-molecular vacuum pumps (TMP) capable of pumping speeds up to about 5000 liters per second (and greater) and a gate valve for throttling the chamber pressure. In conventional vacuum processing devices, a 1000 to 3000 liter per second TMP can be employed. TMPs are useful for low pressure processing, typically less than about 50 mTorr. Furthermore, a device for monitoring chamber pressure (not shown) can be coupled to the vacuum vessel  102  or any of the three vacuum chambers  104 ,  106 ,  108 . The pressure-measuring device can be, for example, a capacitance manometer or ionization gauge. 
     Referring now to  FIG. 3 , a section  300  of a gas cluster ionizer ( 122 ,  FIGS. 1 and 2 ) for ionizing a gas cluster jet (gas cluster beam  118 ,  FIGS. 1 and 2 ) is shown. The section  300  is normal to the axis of GCIB  128 . For typical gas cluster sizes (2000 to 15000 atoms), clusters leaving the skimmer aperture ( 120 ,  FIGS. 1 and 2 ) and entering an ionizer ( 122 ,  FIGS. 1 and 2 ) will travel with a kinetic energy of about 130 to 1000 electron volts (eV). At these low energies, any departure from space charge neutrality within the ionizer  122  will result in a rapid dispersion of the jet with a significant loss of beam current.  FIG. 3  illustrates a self-neutralizing ionizer. As with other ionizers, gas clusters are ionized by electron impact. In this design, thermo-electrons (seven examples indicated by  310 ) are emitted from multiple linear thermionic filaments  302   a,    302   b,  and  302   c  (typically tungsten) and are extracted and focused by the action of suitable electric fields provided by electron-repeller electrodes  306   a,    306   b,  and  306   c  and beam-forming electrodes  304   a,    304   b,  and  304   c.  Thermo-electrons  310  pass through the gas cluster jet and the jet axis and then strike the opposite beam-forming electrode  304   b  to produce low energy secondary electrons ( 312 ,  314 , and  316  indicated for examples). 
     Though (for simplicity) not shown, linear thermionic filaments  302   b  and  302   c  also produce thermo-electrons that subsequently produce low energy secondary electrons. All the secondary electrons help ensure that the ionized cluster jet remains space charge neutral by providing low energy electrons that can be attracted into the positively ionized gas cluster jet as required to maintain space charge neutrality. Beam-forming electrodes  304   a,    304   b,  and  304   c  are biased positively with respect to linear thermionic filaments  302   a,    302   b,  and  302   c  and electron-repeller electrodes  306   a,    306   b,  and  306   c  are negatively biased with respect to linear thermionic filaments  302   a,    302   b,  and  302   c.  Insulators  308   a,    308   b,    308   c,    308   d,    308   e,  and  308   f  electrically insulate and support electrodes  304   a,    304   b,    304   c,    306   a,    306   b,  and  306   c.  For example, this self-neutralizing ionizer is effective and achieves over 1000 micro Amps argon GCIBs. 
     Alternatively, ionizers may use electron extraction from plasma to ionize clusters. The geometry of these ionizers is quite different from the three filament ionizer described here but the principles of operation and the ionizer control are very similar. 
     According to an embodiment, a GCIB is utilized to deposit material on a surface of a substrate. For example, the GCIB can be provided using either of the GCIB processing systems ( 100  or  200 , or combinations thereof) depicted in  FIGS. 1 and 2 . By adjusting the orientation of the substrate relative to the GCIB, material deposition can proceed on surfaces that are substantially perpendicular to the incident GCIB while material deposition can be avoided or reduced on surfaces that are substantially parallel with the incident GCIB. Moreover, one or more properties of the GCIB, including the beam composition, can be adjusted or alternated in order to directionally deposit successive material films having differing properties from one layer to an adjacent layer. 
     Referring to  FIG. 4 , a method of depositing material on a substrate using a GCIB is illustrated according to an embodiment. The method comprises a flow chart  500  beginning in  510  with disposing a substrate in a GCIB processing system. The substrate can be positioned on a substrate holder and may be securely held by the substrate holder. The temperature of the substrate may or may not be controlled. For example, the substrate may be heated or cooled during a film forming process. The environment surrounding the substrate is maintained at a reduced pressure, while a GCIB is formed from a pressurized gas mixture comprising one or more film forming species. The GCIB processing system can be any of the GCIB processing systems ( 100  or  200 ) described above in  FIG. 1  or  2 , or any combination thereof. The substrate can include a conductive material, a non-conductive material, or a semi-conductive material, or a combination of two or more materials thereof. Additionally, the substrate may include one or more material structures formed thereon, or the substrate may be a blanket substrate free of material structures. 
     In  520 , film forming gas comprising one or more source gases is introduced to the GCIB to produce a film-forming GCIB. As described above, a pressurized gas is expanded into a reduced pressure environment to form gas-clusters, the gas-clusters are ionized, and the ionized gas-clusters are accelerated and optionally filtered. 
     The pressurized gas comprises a compound having silicon (Si) and carbon (C). The compound contains Si and C in the same molecule. Further, the compound may possess a Si—C bond. For example, the pressurized gas may comprise an alkyl silane, an alkane silane, an alkene silane, or an alkyne silane, or any combination of two or more thereof. Additionally, for example, the pressurized gas may include methylsilane (H 3 C—SiH 3 ), dimethylsilane (H 3 C—SiH 2 —CH 3 ), trimethylsilane ((CH 3 ) 3 —SiH), or tetramethylsilane ((CH 3 ) 4 —Si), or any combination of two or more thereof. Several chemical formulations are provided below to illustrate the Si—C bond. 
     METHYLSILANE 
       H 3 C—SiH 3    
     DIMETHYLSILANE 
     
       
         
         
             
             
         
       
     
     TRIMETHYLSILANE 
     
       
         
         
             
             
         
       
     
     Additionally, for example, the pressurized gas may further include ethylsilane, diethylsilane, triethylsilane, or tetraethylsilane, or any combination of two or more thereof. 
     The pressurized gas may further comprise an inert gas, such as a noble gas. 
     Additionally, the pressurized gas may further comprise a nitrogen-containing gas. For example, the nitrogen-containing gas may include N 2 , NH 3 , NF 3 , NO, N 2 O, or NO 2 , or a combination of two or more thereof. The addition of a nitrogen-containing gas may permit forming a silicon carbonitride film (SiCN) with relatively high carbon content. 
     Additionally yet, the pressurized gas may further comprise another carbon-containing gas. For example, another carbon-containing gas may include CO, CO 2 , a hydrocarbon-containing gas, a fluorocarbon-containing gas, or a hydrofluorocarbon-containing gas, or any combination of two or more thereof. 
     Furthermore, the pressurized gas may further comprise an oxygen-containing gas or a hydrogen-containing gas or both. 
     In  530 , the substrate is exposed to the film-forming GCIB. The film-forming GCIB may be scanned onto at least a portion of the surface of the substrate. Additionally, the GCIB dose may be adjusted as a function of position on the surface of the substrate in order to vary the thickness of the film formed on the surface of the substrate. The desired thickness of the film that is formed on the surface is achieved by selecting a GCIB dose. Furthermore, the orientation of the surface of the substrate relative to the GCIB may be adjusted. 
     In  540 , a film is formed on the substrate, and the impact of multiple gas clusters on one or more surfaces on the substrate cause the formation of a deposited layer. As the gas clusters collide with the surface of the substrate, material is infused in the surface layer of the substrate or the underlying layer formed on the substrate. As the GCIB dose is increased, the infusion of material transitions to the deposition of material on the surface of the substrate. 
     The deposited layer comprises a film containing silicon and carbon, wherein the carbon content is greater than or equal to about 10%. Additionally, the carbon content may be greater than about 20%. Further, the carbon content may be greater than about 30%. 
     The beam energy may be greater than about 30 keV. Alternatively, the beam energy may be greater than about 10 keV. Alternatively yet, the beam energy may be greater than about 5 keV. Alternately yet, the beam energy may be greater than about 1 keV. For example, the beam energy may range from about 1 keV to about 70 keV. 
     Once the film is deposited, the method may further comprise exposing the film to one or more thermal cycles, or annealing the film. 
     According to an example, a silicon carbide-containing film is prepared using two different pressurized source gases. The first silicon carbide-containing film is prepared with a GCIB using silane (SiH 4 ) and methane (CH 4 ) as a film-forming precursor. The second silicon carbide-containing film is prepared with a GCIB using methylsilane as a film-forming precursor. Table 1 provides the elemental composition of each film as determined by X-ray photoelectron spectroscopy (XPS). Each film is irradiated with X-rays, and a spectrum having a series of photoelectron peaks is acquired by measuring the energy of the emitted electrons, wherein the binding energy of the peaks are characteristic of each element present in the film. 
     
       
         
           
               
               
               
               
               
             
               
                 TABLE 1 
               
               
                   
               
               
                 Source 
                   
                 Film composition 
                 Carbon 
                 Carbon content 
               
               
                 gas(es) 
                 Element 
                 (%) 
                 bond 
                 (%) 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
            
               
                 SiH 4  + CH 4   
                 C 
                 5.3 
                 SiC 
                 56 
               
               
                   
                 Si 
                 84.5 
                 C—C, C—H 
                 42 
               
               
                   
                 O 
                 10.2 
                 C—O 
                 2 
               
               
                 H 3 C—SiH 3   
                 C 
                 39.7 
                 SiC 
                 86 
               
               
                   
                 Si 
                 52.7 
                 C—C, C—H 
                 11 
               
               
                   
                 O 
                 5.6 
                 graphitic 
                 3 
               
               
                   
               
            
           
         
       
     
     The inventors have discovered that using a pressurized source gas comprising a compound having silicon (Si) and carbon (C) can lead to a substantial increase in the carbon content in a GCIB deposited film (e.g., about an order of magnitude increase). Moreover, the inventors have discovered that using this source gas can lead to a substantial increase in the SiC content in the GCIB deposited film (e.g., more than an order of magnitude increase). 
     As shown in Table 1, the first film, prepared using silane (SiH 4 ) and methane (CH 4 ) as the source gases, comprises a carbon content of approximately 5%. Therein, about 56% of the carbon content is bonded to silicon (Si) as SiC. Therefore, about 3% of the material deposited in the first film is C bonded to Si as SiC. Furthermore, about 3% (not shown) of the material is Si bonded to C as SiC. As a result, about 6% of the total composition of the material in the first film is silicon carbide (SiC). 
     Further, as shown in Table 1, the second film, prepared using dimethylsilane as the source gas, comprises a carbon content of approximately 39.7%. Therein, about 86% of the carbon content is bonded to silicon (Si) as SiC. Therefore, about 34% of the material deposited in the second film is C bonded to Si as SiC. Furthermore, about 34% (not shown) of the material is Si bonded to C as SiC. As a result, about 68% of the total composition of the material in the first film is silicon carbide (SiC). 
     Although only certain 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 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.