Abstract:
The present disclosure relates to a semiconductor processing apparatus. The processing chamber includes a chamber body and lid defining an interior volume, a substrate support disposed in the interior volume and a showerhead assembly disposed between the lid and the substrate support. The showerhead assembly includes a faceplate configured to deliver a process gas to a processing region defined between the showerhead assembly and the substrate support and a underplate positioned above the faceplate, defining a first plenum between the lid and the underplate, the having multiple zones, wherein each zone has a plurality of openings that are configured to pass an amount of inert gas from the first plenum into a second plenum defined between the faceplate and the underplate, in fluid communication with the plurality of openings of each zone such that the inert gas mixes with the process gas before exiting the showerhead assembly.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority from U.S. Provisional Application Ser. No. 62/239,547, filed Oct. 9, 2015, which is hereby incorporated by reference in its entirety. 
     
    
     BACKGROUND 
       [0002]    Field 
         [0003]    Embodiments of the present disclosure generally relate to a showerhead assembly for a semiconductor processing apparatus, and more particularly to a showerhead assembly having multiple zones for independent control of fluid passing through the showerhead assembly. 
         [0004]    Description of the Related Art 
         [0005]    Reliably producing sub-half micron and smaller features is one of the key technology challenges for next generation very large scale integration (VLSI) and ultra large scale integration (ULSI) of semiconductor devices. However, as the limits of circuit technology are pushed, the shrinking dimensions of VLSI and ULSI technology have placed additional demands on processing capabilities. Reliable formation of gate structures on the substrate is helpful to VLSI and ULSI success and to the continued effort to increase circuit density. 
         [0006]    As circuit densities increase for next generation devices, the widths of interconnects, such as vias, trenches, contacts, gate structures and other features, as well as the dielectric materials therebetween, decrease to 45 nm and 32 nm dimensions and beyond. In order to enable the fabrication of next generation devices and structures, three dimensional (3D) stacking of features in semiconductor chips is often utilized. In particular, fin field effect transistors (FinFETs) are often utilized to form three dimensional (3D) structures in semiconductor chips. By arranging transistors in three dimensions instead of conventional two dimensions, multiple transistors may be placed in the integrated circuits (ICs) very close to each other. As circuit densities and stacking increase, the ability to selectively deposit subsequent materials on previously deposited materials gains importance. The ability to control fluids delivered to substrates through showerhead assemblies has become increasingly helpful in aiding the successful fabrication of next generation devices. 
         [0007]    Thus, there is a need for an improved showerhead assembly. 
       SUMMARY 
       [0008]    In one embodiment, a showerhead assembly is disclosed herein. The showerhead assembly includes a faceplate and a underplate. The faceplate has a first side and a second side. The faceplate has a plurality of apertures configured to deliver a process gas from the first side to the second side. The underplate is positioned adjacent the first side of the faceplate. The underplate has multiple zones, wherein each zone has a plurality of apertures that are configured to pass inert gas through the underplate into a plenum defined between the faceplate and the underplate. The inert gas mixes with a process gas in the plenum. 
         [0009]    In another embodiment, a showerhead assembly is disclosed herein. The showerhead assembly includes a faceplate and a underplate. The showerhead includes a first side and a second side. The faceplate has a plurality of apertures configured to deliver a process gas from the first side to the second side. The underplate is positioned adjacent the first side of the faceplate defining a plenum between the faceplate and the underplate, wherein the underplate has multiple zones. Each zone includes a conductance controller assembly extending from the underplate into the plenum. The conductance controller assembly is configured to control the conductance of process gas within the plenum. 
         [0010]    In another embodiment, a showerhead assembly is disclosed herein. The showerhead assembly includes a faceplate and a underplate. The showerhead includes a first side and a second side. The faceplate has a plurality of apertures configured to deliver a process gas from the first side to the second side. The underplate is positioned adjacent the first side of the faceplate defining a plenum between the faceplate and the underplate, wherein a plurality of gas lines are formed through the underplate opening into the plenum. The plurality of gas lines form multiple zones in the underplate, wherein each zone is configured to provide a different amount of process gas to the plenum. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, 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 disclosure and are therefore not to be considered limiting of its scope, for the disclosure may admit to other equally effective embodiments. 
           [0012]      FIG. 1  illustrates a processing chamber having a showerhead assembly, according to one embodiment. 
           [0013]      FIG. 2  illustrates a gas delivery system of  FIG. 1 , according to one embodiment. 
           [0014]      FIG. 3  illustrates a processing chamber having a showerhead assembly, according to one embodiment. 
           [0015]      FIG. 4  illustrates a processing chamber having a showerhead assembly, according to one embodiment. 
       
    
    
       [0016]    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. 
         [0017]    It is to be noted, however, that the appended drawings illustrate only exemplary embodiments of this disclosure and are therefore not to be considered limiting of its scope, for the disclosure may admit to other equally effective embodiments. 
       DETAILED DESCRIPTION 
       [0018]      FIG. 1  illustrates a chemical vapor deposition (CVD) processing chamber  100  having a showerhead assembly  112 , according to one embodiment. The processing chamber  100  includes a chamber body  102  having sidewalls  104 , a bottom  105 , and a lid  106 . The sidewalls  104  and lid  106  define an interior volume  108 . A substrate transfer port  110  may be formed in the sidewall  104  for transferring substrates into and out of the interior volume  108 . 
         [0019]    A substrate support assembly  126  is disposed within the interior volume  108  of the processing chamber  100  below the showerhead assembly  112 . The substrate support assembly  126  is configured to support a substrate  101  during processing. The substrate support assembly  126  may include a plurality of lift pins  128  movably disposed therethrough. The lift pins  128  may be actuated to project from a support surface  130  of the substrate support assembly  126 , thereby placing the substrate  101  in a spaced-apart relation to the substrate support assembly  126  to facilitate transfer with a transfer robot (not shown) through the substrate transfer port  110 . 
         [0020]    The showerhead assembly  112  is disposed in the interior volume  108  and is coupled to the lid  106 . The showerhead assembly  112  includes a underplate  114  and a faceplate  118 . The underplate  114  is positioned below the lid  106  such that a first plenum  120  is formed between the underplate  114  and the lid  106 . In one embodiment, the showerhead assembly  112  further includes a diffuser plate  116  positioned between the underplate  114  and the faceplate  118 . The diffuser plate  116  forms a second plenum  124  between the underplate  114  and the diffuser plate  116  and a third plenum  122  between the diffuser plate  116  and the faceplate  118 . 
         [0021]    The first plenum  120  is partitioned into a plurality of zones by the underplate  114 . For example, in the embodiment shown in  FIG. 1 , the first plenum  120  is partitioned into zone Z 2  and zone Z 3 . The first plenum  120  is configured to receive an inert gas from a gas delivery system  180  coupled to an inert gas source  144 . The inert gas may be provided to each zone Z 2  and Z 3 . For example, a greater amount of inert gas may be provided to Z 2  compared to that of Z 3 . In one embodiment, the gas delivery system  180  uses a flow ratio control technique to control the amount of inert gas delivered to zone Z 2  relative to zone Z 3 . In one embodiment, different combinations of pneumatic valves and sized orifices may be used to achieve gas splitting. In another embodiment, using different gas delivery valves, such as piezo and ALD valves, when used in combination can achieve the same gas splitting results to the different zones. 
         [0022]    The underplate  114  is configured to provide the inert gas from the first plenum  120  to the second plenum  124 . The underplate  114  includes a plurality of apertures  132 . The apertures  132  allow for fluid communication between the first plenum  120  and the second plenum  124 . The plurality of apertures  132  are positioned beneath the zones Z 2  and Z 3 , and thus, the apertures  132  are grouped into corresponding zones Z 2 , Z 3  in the underplate  114 . 
         [0023]    The processing chamber  100  further includes a central conduit  138 . The central conduit  138  is formed through the lid  106  and opens into the second plenum  124 . The central conduit  138  is configured to provide a process gas to the second plenum  124  from the process gas source  140 . In the second plenum  124 , the process gas supplied by the central conduit  138  mixes with the inert gas provided from the underplate  114 . Because the amount of inert gas entering the second plenum  124  through each zone of the underplate  114  is different, the ratio of process gas to inert gas is not uniform across the second plenum  124 . Thus, in the second plenum  124  there are three zones (A1, A2, A3) of process gas dilution by the inert gas. A first zone, A1, directly beneath the central conduit  138  in which the process gas is not diluted by the first gas; the second zone A2 beneath Z 2  in the first plenum  120 ; and the third zone A3 beneath Z 3  in the first plenum  120 . Each zone A1-A3 may include a different ratio of inert gas to the process gas. Creating multiple zones of process gas in the plenum  120  allows for a gradient in the distribution of the process gas exiting the faceplate and delivered to the substrate to improve film deposition properties. 
         [0024]    The diffuser plate  116  includes a plurality of apertures  134 . The plurality of apertures  134  allows for fluid communication between the second plenum  124  and the third plenum  122 . The diffuser plate  116  is configured to disperse the gas mixture provided to the third plenum  122 . The third plenum  122  is in fluid communication with a processing region  142  defined between the faceplate  118  and the substrate support assembly  126  through a plurality of apertures  136  formed through the faceplate  118 . The apertures allow for fluid communication between the third plenum  122  and the processing region  142 . 
         [0025]    A controller  190  is coupled to the processing chamber  100 . The controller  190  includes a central processing unit (CPU)  192 , a memory  194 , and support circuits  196 . The controller  190  is utilized to control the amount of inert gas supplied to each zone Z 2 , Z 3  of the first plenum  120 . Controlling the amount of inert gas to each zone allows for gas distribution uniformity exiting the showerhead assembly  112  to be controlled. The CPU  192  may be of any form of a general purpose computer processor that can be used in an industrial setting. The software routines can be stored in the memory  194 , such as random access memory, read only memory, floppy or hard disk drive, or other form of digital storage. The support circuits  196  are conventionally coupled to the CPU  192  and may comprise cache, clock circuits, input/output subsystems, power supplies, and the like. The software routines, when executed by the CPU  192 , transform the CPU  192  into a specific purpose computer (controller)  190  that controls the processing chamber  100  such that the processes are performed in accordance with the present disclosure. The software routines may also be stored and/or executed by a second controller (not shown) that is located remotely from the chamber. 
         [0026]      FIG. 2  illustrates the gas delivery system  180  according to one embodiment. The gas delivery system  180  includes a flow ratio control device  200  coupled to each zone Z 2 , Z 3  of the first plenum  120 . The flow ratio control device  200  includes a supply line  202  coupled to the gas source  144 , a plurality of valves  204   a,    204   b,  a plurality of orifices  206   a,    206   b,  and an outlet line  208 . The supply line  202  delivers an inert gas to each valve  204   a - 204   b.  The valves  204   a - 204   b  are independently controlled, and are configured to open and close to control the amount of inert gas supplied to each respective orifice  206   a - 206   b . Each orifice  206   a - 206   b  may be sized differently, such that each zone may receive a different amount of gas flow. Additional valves and orifices may be added or subtracted based on the number of zones desired in the first plenum  120 . 
         [0027]      FIG. 3  illustrates a CVD processing chamber  300 , according to one embodiment. The processing chamber  300  includes a chamber body  302  having sidewalls  304 , a bottom  305 , and a lid  306 . The sidewalls  304  and lid  306  define an interior volume  308 . A substrate transfer port  310  may be formed in the sidewall  304  for transferring substrates into and out of the interior volume  308 . 
         [0028]    The processing chamber  300  further includes a showerhead assembly  312 . The showerhead assembly  312  includes a underplate  314  and the faceplate  118 . The underplate  314  is positioned below the lid  306  such that a first plenum  320  is formed between the underplate  314  and the lid  306 . In one embodiment, the showerhead assembly  312  further includes the diffuser plate  116  positioned between the underplate  314  and the faceplate  118 . The diffuser plate  116  forms a second plenum  324  between the underplate  314  and the diffuser plate  116  and a third plenum  322  between the diffuser plate  116  and the faceplate  118 . The central conduit  138  is formed through the lid  306  and opens into the second plenum  324 . The central conduit  138  is configured to provide a process gas to the second plenum  324  from the process gas source  140 . An inert gas line  380  is formed through the lid  306  and underplate  314  and opens into the second plenum  324 . The inert gas line  380  is configured to provide an inert gas to the second plenum  324  from the inert gas source  382 , such that the inert gas mixes with the process gas in the second plenum  324 . 
         [0029]    A movable conductance controller assembly  348  is disposed in the first plenum  320  and extends through the underplate  314  into the second plenum  324 . The movable conductance controller assembly  348  is configured to control the conductance through a gap defined between the diffuser plate  116  and the underplate  314  to control the amount of gas flowing through different regions (zones) of the second plenum  324 . The movable conductance controller assembly  348  includes a conductance controller  350  and an actuator  352 . In one embodiment, the conductance controller  350  may include a shaft  354  and a plate  356 . The shaft  354  may extend through the underplate  314  into the second plenum  324  such that the plate  356  is within the second plenum  324 . In one embodiment, an o-ring  358  and bellows  360  may be used to maintain isolation between the first plenum  320  and the second plenum  324 . 
         [0030]    The actuator  352 , such as a motor or cylinder, may be coupled to the conductance controller  350 . In one embodiment, the motor may be mounted to a z-stage  362  disposed in the first plenum  320 . The actuator  352  is configured to move the conductance controller  350  in the z-direction. Raising and lowering the conductance controller  350  controls the amount of flow of the process gas mixture to be distributed to the second plenum  324 . For example, a larger gap between the conductance controller  350  and the diffuser plate  116  allows for a greater amount of process gas mixture within the second plenum  324 . Conversely, a smaller gap between the conductance controller  350  and the diffuser plate  116  allows for a lesser amount of a process gas mixture within the second plenum  324 . Each conductance controller  350  disposed in the first plenum  320  may be controlled independently to define a plurality of zones of process gas mixture in the second plenum  324 . The plurality of apertures  134  are positioned beneath the plurality of zones. The apertures  134  are grouped in corresponding zones in the diffuser plate  116 . Because the concentration of process gas mixture entering the third plenum  322  through each zone in the diffuser plate  116  is different, the concentration of process gas mixture is not uniform across the third plenum  322 . Multiple zones of process gas mixture are defined in the third plenum  322 , allowing for a gradient in the distribution of the process gas mixture exiting the faceplate  118  and delivered to the substrate to improve film deposition properties. 
         [0031]    A controller  390  is coupled to the processing chamber  300 . The controller  390  includes a central processing unit (CPU)  392 , a memory  394 , and support circuits  396 . The controller  390  may be coupled to the actuator  352  to control the conductance controller  350 . Controlling the conductance controller  350  allows for a gradient in the distribution of the process gas in the showerhead assembly  312 . The CPU  392  may be of any form of a general purpose computer processor that can be used in an industrial setting. The software routines can be stored in the memory  394 , such as random access memory, read only memory, floppy or hard disk drive, or other form of digital storage. The support circuits  396  are conventionally coupled to the CPU  392  and may comprise cache, clock circuits, input/output subsystems, power supplies, and the like. The software routines, when executed by the CPU  392 , transform the CPU  392  into a specific purpose computer (controller)  390  that controls the processing chamber  300  such that the processes are performed in accordance with the present disclosure. The software routines may also be stored and/or executed by a second controller (not shown) that is located remotely from the chamber. 
         [0032]      FIG. 4  illustrates a CVD processing chamber  400  according to yet another embodiment. The processing chamber  400  includes a chamber body  402  having sidewalls  404 , a bottom  405 , and a lid  406 . The sidewalls  404  and lid  406  define an interior volume  408 . A substrate transfer port  410  may be formed in the sidewall  404  for transferring substrates into and out of the interior volume  408 . 
         [0033]    The processing chamber  400  further includes a showerhead assembly  412 . The showerhead assembly  412  includes a underplate  414  and the faceplate  118 . The underplate  414  is positioned below the lid  406  such that a plenum  420  is formed between the underplate  414  and the faceplate  118 . A plurality of gas lines  424  coupled to a gas source  440  extend through the lid  406  and underplate  414  to provide process gas to the plenum  420 . Each line  424  may be configured to deliver a different concentration of process gas to the plenum  420 . For example, multiple zones of process gas may be formed in the plenum  420  by diluting the concentration of process gas with an inert gas in the outer gas lines  424  compared to the concentration of the process gas flowing through the inner gas lines  424 . The plurality of apertures  136  are positioned beneath the zones, and thus the apertures  136  are grouped into corresponding zones. Creating multiple zones of process gas concentration in the plenum  420  allows for a gradient in the amount of process gas delivered to the substrate to improve film deposition properties. 
         [0034]    A controller  490  is coupled to the processing chamber  400 . The controller  490  includes a central processing unit (CPU)  492 , a memory  494 , and support circuits  496 . The controller  490  may be coupled to the gas source  440  to control the concentration of process gas supplied to each gas line  424 . Controlling each respective gas line  424  allows for modulation of the gas distribution in the showerhead assembly. The CPU  492  may be of any form of a general purpose computer processor that can be used in an industrial setting. The software routines can be stored in the memory  494 , such as random access memory, read only memory, floppy or hard disk drive, or other form of digital storage. The support circuits  496  are conventionally coupled to the CPU  492  and may comprise cache, clock circuits, input/output subsystems, power supplies, and the like. The software routines, when executed by the CPU  492 , transform the CPU  492  into a specific purpose computer (controller)  490  that controls the processing chamber  400  such that the processes are performed in accordance with the present disclosure. The software routines may also be stored and/or executed by a second controller (not shown) that is located remotely from the chamber. 
         [0035]    While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.