Abstract:
Methods for detecting valve leakage and apparatus for the same are provided. In one embodiment, a method for detecting a valve leakage includes flowing a gas through a diverter valve, determining a pressure in a gas source provided to the diverter valve, comparing the determined pressure value with an expected pressure value, and generating a signal in response to the comparison.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to U.S. Provisional Patent Application Ser. No. 61/798,568, filed on Mar. 15, 2013, which is herein incorporated by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    Embodiments of the present invention generally relate to a method for detecting a valve deviation, and apparatus for same. Additionally, embodiments of the present invention also relate to a method for depositing a film. 
         [0004]    2. Background of the Invention 
         [0005]    In the manufacture of integrated circuits, precise control of various processing parameters is required for achieving consistent results within a substrate, as well as the results that are reproducible from substrate to substrate. As the geometry limits of the structures for forming semiconductor devices are pushed against technology limits, tighter tolerances and precise process control are critical to fabrication success. However, with shrinking geometries, precise critical dimension and process control has become increasingly difficult. 
         [0006]    Conventional deposition processes, such as chemical vapor deposition (CVD), supply reactive gasses (i.e., precursor gasses) to the substrate surface to produce plasma which is deposited as a desired film on the substrate. If the reactive gasses are not precisely controlled, processing results may lead to non-uniform film deposition. For example, gas valve leaks may lead to non-uniform gas delivery resulting in delaminated film on the substrate surface. Although conventional gas panel systems have proven to be robust performers at larger critical dimensions, existing techniques for controlling gas delivery is one area where improvement will contribute to the successful fabrication of semiconductor devices with reduced geometries. 
         [0007]    Therefore, there is a need for an improved method of gas delivery by detecting a valve deviation from a predetermined standard. 
       SUMMARY OF THE INVENTION 
       [0008]    Embodiments of the present invention generally relate to a method for detecting a valve deviation, and using the same. Additionally, embodiments of the present invention also relate to a method for depositing a film. 
         [0009]    Methods for detecting valve leakage and apparatus for the same are provided. In one embodiment, a method for detecting a valve leakage includes flowing a gas through a diverter valve, determining a pressure in a gas source provided to the diverter valve, comparing the determined pressure value with an expected pressure value, and generating a signal in response to the comparison. 
         [0010]    In another embodiment, computer-readable storage medium is provide for detecting valve leakage. The computer-readable storage medium, storing code for execution by a central processing unit (CPU), wherein a code, when executed by a CPU, cause performance of a method for detecting leakage in a valve, the method including flowing a gas through a diverter valve, determining a pressure in a gas source provided to the diverter valve, comparing the determined pressure value with an expected pressure value, and generating a signal in response to the comparison. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical 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. 
           [0012]      FIG. 1  is a schematic representation of a deposition system, according to one embodiment of the present invention; 
           [0013]      FIG. 2  is a schematic representation of a valve assembly; and 
           [0014]      FIG. 3  is a flow diagram of a method for detecting a valve deviation. 
       
    
    
       [0015]    To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation. 
       DETAILED DESCRIPTION 
       [0016]      FIG. 1  is a schematic diagram of one embodiment of a deposition system  100  suitable for depositing a film. A suitable processing chamber  103 , which may be adapted for use with the teachings disclosed herein, includes, for example, the Producer Processing system available from Applied Materials, Inc. of Santa Clara, Calif. Suitable processing chambers include a CVD chamber, a plasma enhanced chemical vapor deposition (PECVD) chamber, a physical vapor deposition (PVD) chamber, etch chamber or other vacuum chambers used for vacuum processing. For clarity and ease of description, a CVD chamber utilizing embodiments of the invention described herein is described below with reference to  FIGS. 1 and 2 . 
         [0017]    The processing chamber  103  includes a chamber body  102  and a lid  104  which encloses an interior volume  106 . The chamber body  102  is typically fabricated from aluminum, stainless steel or other suitable material. The chamber body  102  generally includes sidewalls  108  and a bottom  110 . A substrate support pedestal access port (not shown) is generally defined in the sidewall  108  and selectively sealed by a slit valve to facilitate entry and egress of a substrate  105  from the processing chamber  103 . An exhaust port  126  is defined in the chamber body  102  and couples the interior volume  106  to a pump system  128 . The pump system  128  generally includes one or more pumps and throttle valves utilized to evacuate and regulate the pressure of the interior volume  106  of the processing chamber  103 . 
         [0018]    A gas panel  158  is coupled to the processing chamber  103  to provide process and/or cleaning gases to the interior volume  106  of the processing chamber  103 . The gas panel  158  includes a first precursor gas source  171  and a first carrier gas source  173 . In one embodiment, the first precursor gas source  171  provides a silicon rich precursor. An example of a suitable silicon rich precursor is methyldiethoxsilane (mDEOS), among others. Suitable carrier gases include helium, nitrogen or other suitable non-reactive gas. 
         [0019]    The first precursor gas source  171  and the first carrier gas source  173  are coupled to a first vaporizer  180 . In one embodiment, a first sensor  186  is disposed between the first carrier gas source  173  and the first vaporizer  180  to provide a complete-holistic diagnostic of the health of the flow of the first carrier gas  171  throughout the system  100 . The first sensor  186  may be a pressure sensor, a mass flow meter or other sensor suitable for providing a metric indicative of the flow from the first carrier gas source  173 . The first vaporizer  180  is coupled to a first valve assembly  190 . 
         [0020]    The gas panel  158  includes also includes a second precursor gas source  172  and a second carrier gas source  174 . In one embodiment, the second precursor gas source  172  provides a carbon rich precursor. Examples of a suitable carbon rich precursor include alpha-terpinene (ATRP) and bicyclo [2.2.1]hepta-2,5-diene (BCHD), among others. Suitable carrier gases include helium, nitrogen or other suitable non-reactive gas. 
         [0021]    The second precursor gas source  172  and the second carrier gas source  174  are coupled to a second vaporizer  181 . In one embodiment, a second sensor  188  is disposed between the second carrier gas source  174  and the second vaporizer  181  to provide a complete-holistic diagnostic of the health of the flow of the second carrier gas  174  throughout the system  100 . The second sensor  188  may be a pressure sensor, a mass flow meter or other sensor suitable for providing a metric indicative of the flow from the second carrier gas source  174 . The second vaporizer  181  is coupled to a second valve assembly  192 . 
         [0022]    The gas panel  158  includes also includes an oxygen source  175 . The oxygen source  175  provides an oxidizing gas, such as O 2 , to the processing chamber  103  for mixing with the gas mixtures entering the processing chamber  103  from either or both of the valve assemblies  190 ,  192 . 
         [0023]    The valve assemblies  190 ,  192  are configured as diverter valves as to selectively couple the vaporizers  180 ,  181  to the processing chamber the exhaust port  126  of the processing chamber  103  downstream of a pumping system  128 ) via a by-pass line  198 . Details of the valve assemblies  190 ,  192  will be discussed further below with respect to  FIG. 2 . 
         [0024]    In the embodiment depicted in  FIG. 1 , one or more chamber inlet ports  132  are provided in the lid  104  to allow gases to be delivered from the gas panel  158  to the interior volume  106  of the processing chamber  103 . A showerhead assembly  130  is coupled to an interior surface  114  of the lid  104 . The showerhead assembly  130  includes a plurality of apertures that allow gases to flow through the showerhead assembly  130  from the chamber inlet port  132  into the interior volume  106  of the processing chamber  103  in a predefined distribution across the surface of a substrate support pedestal  148 . 
         [0025]    An RF source power source  143  is coupled through a matching network  141  to the showerhead assembly  130 . The RF source power supply  143  is capable of generating up to about 3000 W at a tunable frequency in a range from about 50 kHz to about 13.56 MHz. 
         [0026]    In one embodiment, the showerhead assembly  130  is configured with a plurality of zones (not shown) that allow for separate control of gas flowing into the interior volume  106  of the processing chamber  103 . In one embodiment the showerhead assembly  130  has an inner zone and an outer zone that are separately coupled to the gas panel  158  through separate inlet ports  132 . 
         [0027]    The substrate support pedestal  148  is disposed in the interior volume  106  of the processing chamber  103  facing the gas distribution showerhead assembly  130 . The substrate support pedestal  148  holds the substrate  105  during processing. The substrate support pedestal  148  generally includes a plurality of lift pins (not shown) disposed there which are configured to lift the substrate  105  from the substrate support pedestal  148  and facilitate exchange of the substrate  105  with a robot (not shown) in a conventional manner. 
         [0028]    The substrate support pedestal  148  may optionally include at least one embedded heater  176 , to control the lateral temperature profile of the substrate support pedestal  148 . The heater  176  is regulated by a power source  178 . In operation, a backside gas is provided at controlled pressure into the gas passages to enhance the heat transfer between an electrostatic chuck (not shown) and the substrate support pedestal  148 . 
         [0029]    The above-described system  100  can be controlled by a processor based system controller such as the controller  150 . The controller  150  includes a programmable central processing unit (CPU)  120  that is operable with a memory  184 , a mass storage device, an input control unit, and a display unit. The system controller further includes well-known support circuits  113  such as power supplies, clocks, cache, input/output (I/O) circuits, and the like, coupled to the various components of the processing chamber  103  to facilitate control of the deposition process. The controller  150  also includes hardware for monitoring substrate processing through sensors in the processing chamber  103 , including the sensors  186 ,  188  monitoring the carrier gas flow. Other sensors that measure system parameters such as substrate temperature, chamber atmosphere pressure and the like, may also provide information to the controller  150 . All of the above elements are coupled to a control system bus  131 . 
         [0030]    To facilitate control of the processing chamber  103  and the gas panel  158 , as described above, the CPU  120  may be one of any form of general purpose computer processor that can be used in an industrial setting, such as a programmable logic controller (PLC), for controlling various chambers and sub-processors. The memory  184  is coupled to the CPU  120 , and is accessible to the system bus  131 . The memory  184  is non-transitory and may be one or more of readily available memory such as random access memory (RAM), read only memory (ROM), floppy disk drive, hard disk, or any other form of digital storage, local or remote. The support circuits  113  are coupled to the CPU  120  for supporting the processor in a conventional manner. The deposition process is generally stored in the memory  184 , typically as a software routine. The software routine may also be stored and/or executed by a second CPU (not shown) that is remotely located from the hardware being controlled by the CPU  120 . 
         [0031]    The memory  184  contains instructions that the CPU  120  executes to facilitate the operation of the system  100 . The instructions in the memory  184  are in the form of program code such as a program that implements the method of the present invention. The program code may conform to any one of a number of different programming languages. In one embodiment, program code controls the delivery of the silicon precursor source  171  and the carrier gas source  173  as well as the carbon precursor  171  and the carrier gas source  173  with the oxygen source  175 . 
         [0032]      FIG. 2  is a schematic representation of the valve assembly  190 . The valve assembly  192  may be similarly configured. In one embodiment, the valve assembly  190  is a diverter valve. The valve assembly  190  includes a gas inlet port  202 , a normally open port  204 , a normally closed port  206 , a first actuation port  208  and a second actuation port  210 . The normally open port  204  is coupled to the processing chamber  103  via the chamber delivery line  197 . The normally closed port  206  is coupled to the foreline  160  via the by-pass line  198 . Pressure applied to first actuation port  208  changes the open/closed state of the normally open port  204 , while pressure applied to second actuation port  210  changes the open/closed state of the normally closed port  206 . 
         [0033]    Referring to  FIGS. 1 and 2 , the gas inlet port  202  of the first valve  190  is coupled by a gas delivery line  212  to the first vaporizer  180 . The precursor and carrier source gas, having been mixed in the first vaporizer  180 , flow into the first valve  190  through the gas inlet port  202  and exit the first valve  190  through the normally open port  204  when the first valve  190  is in a non-actuated state, i.e., no pressure is applied to the actuation ports  208 ,  210 . The normally open port  204  is coupled to the processing chamber  103  by the chamber delivery line  197  and is configured to flow gas directly to the processing chamber  103 . The mixed precursor and carrier source gas flows through the gas inlet port  202  and exits the first valve  190  through the normally closed port  206  when the first valve  190  is in an actuated state, i.e., a threshold pressure is applied to the actuation ports  208 ,  210 . The normally closed-state port  206  is coupled to the foreline  160  via the by-pass line  198 , thus allowing the mixed gases to by-pass the processing chamber  103  while still flowing from the gas panel  158 . Flowing gas from the gas panel  158  directly into the foreline  160  allows the gas flows to fill the gas conduits and stabilize, thus allowing faster switching with less flow ramping when flow is switch from the foreline  160  to the processing chamber  103 . 
         [0034]    As discussed above, the gas flow path (i.e., to the processing chamber  103  or to the exhaust port  126 ) through the first valve  190  is controlled by the application of pressure to the first and second actuation ports  208 ,  210 . The first actuation port  208  is coupled to an actuation fluid source  218  by a first actuation fluid delivery line  214 , and the second actuation port  210  is coupled to the actuation fluid source  218  by a second actuation fluid delivery line  216 . The actuation fluid delivery line  214 ,  216  are joined and coupled to the actuation fluid source  218  via a common control valve  220 . The actuation fluid source  218  is configured to deliver an actuation fluid, such as compressed dry air (CDA), nitrogen gas (N 2 ), or other suitable fluid, to the first and second actuation ports  208 ,  210 . In one embodiment, the control valve  220  is coupled to the controller  150 , as described above, such that the actuation state of the first valve  190  may be selectively controlled to direct the mixed gases to the desired location, i.e., the foreline  160  or processing chamber  103 ). 
         [0035]    The connections and operation of the second valve assembly  192  is substantially identical to that of the first valve assembly  190 , expect for the second valve assembly  192  being configured to control the delivery of carbon rich precursor to the processing chamber  103 . 
         [0036]    Referring back to  FIG. 1 , location of the first and second sensors  186 ,  188  on the carrier source lines between the vaporizers  180 ,  181  and carrier sources  173 ,  174  advantageously isolates the sensors  186 ,  188  from the liquid precursors which may affect the reliability and service life of the sensors  186 ,  188 . Moreover, the position of the sensors  186 ,  188  prior to the vaporizers  180 ,  181  positions the sensors  186 ,  188  in a location that is not heated. That is, the lines leading from the vaporizers  180 ,  181  to the processing chamber  103  and foreline  160 , along with the vaporizers  180 ,  181  themselves are heated to prevent condensation and deposition of the precursor materials within the lines. Fluctuations in the temperature of these lines due to the changes in flow rates and/or material composition of gases flowing through the lines would negatively impact the ability to obtain precise and accurate information from the sensors  186 ,  188 . Thus, the position of the sensors  186 ,  188  upstream of the vaporizers  180 ,  181  in the carrier gas lines reduces any impact on the information from the sensors  186 ,  188  due to temperature issues, thereby increasing the accuracy and reliability of the information obtained from the sensors  186 ,  188 , along with increasing the service life of the sensors  186 ,  188 . 
         [0037]      FIG. 3  is a flow diagram of a method for detecting leakage in a valve. At block  302 , the first precursor gas source  171 , the first carrier gas source  173 , the second precursor gas source  172  and the second carrier gas source  174  flow gas to the first and second diverter valves  190 ,  192 , respectively. The precursor gases from the precursor sources  171 ,  172  and the carrier gases from the carrier gas sources  173 ,  174  mix in their respective vaporizers  180 ,  181  before flowing to the valve assemblies  190 ,  192 . 
         [0038]    In one exemplary mode of operation, the first valve assembly  190  is un-actuated to flow the silicon rich gas mixture to the processing chamber  103  while the second valve assembly  192  is in an actuated state to flow the carbon rich gas mixture to the foreline  160 , by-passing the processing chamber  103 . The silicon rich gas mixture is mixed with oxygen from the oxygen source  175  in the processing chamber  103  and energized to form plasma. The plasma causes the oxygen-silicon rich gas mixture to disassociate and deposit a silicon-based adhesion layer on the substrate  105 . 
         [0039]    Continuing the exemplary mode of operation, the first valve assembly  190  remains un-actuated to flow the silicon rich gas mixture to the processing chamber  103  while the second valve assembly  192  is switched to an un-actuated state to switch the flow of the carbon rich gas mixture from the foreline  160  to the processing chamber  103 . The silicon rich gas mixture is combined with the carbon rich gas mixture, and flows into the processing chamber  103 . The silicon rich/carbon rich gas mixture with is mixed with oxygen from the oxygen source  175  in the processing chamber  103  and energized to form a plasma. The plasma causes the oxygen—silicon rich/carbon rich gas mixture to disassociate and deposit a low-k (i.e., a dielectric constant less than about 4) dielectric layer on the silicon-based adhesion layer. The low-k dielectric layer may a portion proximate the adhesion layer that increases in carbon with distance from the adhesion layer. 
         [0040]    At block  304 , a metric indicative of the flow of carrier gas from the carrier gas sources  173 ,  174  is measured by their respective sensors  186 ,  188 . The metric indicative of flow is provided to the controller  150 . The measurement of the metric indicative of the flow may occur at any point in time in the example given above. Additionally, the metric indicative of the flow of the carrier gas may be obtained by the sensors  186 ,  188  during a non-processing period, for example, when no precursor gases are flowing so as to not waste expensive gases. The carrier gas may be directed through the valve assemblies into the foreline  160  so as not to generate particles or otherwise disrupt activities within the processing chamber  103 . 
         [0041]    The metric provided by the sensors  186 ,  188  may be utilized to determine a complete-holistic diagnostic of the health of the pressure flow of the carrier gases throughout the system  100 . As such, any leaks, deviations or perturbations in the flow of the gas through the valves  190 ,  192  are sensed by the sensors  186 ,  188 , which in response to, the controller  150  would generate a signal indicating the out of spec condition, i.e., leak or fault. 
         [0042]    At block  306 , the metric provided by the sensors  186 ,  188  is analyzed by the controller  150  to determine at least one of if the metric is outside of a predefined process window, above a threshold value, or below a threshold value. In one embodiment, the metric is compared to a predetermined value, for example of the pressure and/or flow rates of the carrier gas. The predetermined value may be determined by simulation, calculation or from test results. The predetermined value may be in the form of a numerical value, range of numerical value or data table. The predetermined value may be associated with a steady state flow condition or a ramping flow condition. The predetermined value may be associated with a steady state condition of the valve assembly or over a period that includes switching the actuation state of the valve. For example, if the valve assembly  192  is un-actuated and allowing flow of carrier gas (optionally having precursor gas mixed therewith) through the normally open port  204  and the valve assembly is actuated to switch the gas flow to the normally closed port  206 , the signature of the metric, i.e., pressures and/or flow signature and be compared with the determined value associated with an expected signature under normal (e.g., expected) operating conditions. If a leak occurs, the metric of carrier gas flow sensed by the sensor and provided to the controller  150  would be outside of or deviate from the predetermined value expected for at those flow conditions. In one embodiment, the following equation may be used to determine the presence of a leak in the valve, wherein P1 is the recorded pressure (i.e., the metric obtained by the sensor) while flowing the carrier gas through the normally closed port  206 , and P2 is the recorded pressure after actuating the flow of the carries gas to the normally open port  204 : 
         [0000]    
       
         
           
             
               
                 
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         [0043]    If the comparative value falls below 3% or above 8%, the controller  150  generates a signal that the valve failure is present at block  308 . If the comparative value does not fall within the above range, normal operations continue. In one embodiment, if the comparative value does not fall within the predefined range, the controller  150  may generate a signal to continue normal operations. 
         [0044]    The above invention is particularly beneficial in the deposition of low-K dielectric film which requires strict control of silicon rich and carbon rich precursors. For example, valve leaks (e.g., leaking carbon precursors to the processing chamber during a processing step that utilizes only silicon precursor) may ruin film quality, and for example, compromise the adhesion of the film and potentially allow future delaminating which may only be found well after deposition and after substantial investment in subsequent fabrication steps. Therefore, the above described invention advantageously allow more robust process control and effectively limits process defects due to valve leakage degradation in film quality. 
         [0045]    While the foregoing is directed to the preferred embodiment of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof. The scope of the invention is determined by the claims which follow.