Patent Publication Number: US-2018047542-A1

Title: Inductively coupled plasma chamber having a multi-zone showerhead

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Patent Application No. 62/374,835, filed with the United States Patent Office on Aug. 13, 2016, which is herein incorporated by reference in its entirety. 
    
    
     FIELD 
     Embodiments of the present disclosure generally relate to plasma processing equipment. 
     BACKGROUND 
     Inductively coupled plasma (ICP) process chambers generally form plasmas by inducing current in a process gas disposed within the process chamber via one or more inductive coils disposed outside of the process chamber. The inductive coils may be disposed externally and separated electrically from the chamber by, for example, a dielectric lid. When radio frequency (RF) current is fed to the inductive coils via an RF feed structure from an RF power supply, an inductively coupled plasma can be formed inside the chamber from an electric field generated by the inductive coils. 
     In some reactor designs, the reactor may be configured to have concentric inner and outer inductive coils. RF power from an RF power source may be split between the two coils via a current divider/variable capacitor, or the like. The RF power is coupled from the antenna or electrode to process gases within the reactor to form a plasma that is used for the etching process. The matching network ensures that the output of the RF source is efficiently coupled to the plasma to maximize the amount of energy coupled to the plasma (e.g., referred to as tuning the RF power delivery). 
     Existing reactor designs often flow gas through a nozzle disposed at the center of the dielectric lid. However, the inventors have observed that such a chamber configuration sometimes results in m-shaped deposition on the substrate being processed. 
     Accordingly, the inventors have devised an improved process chamber. 
     SUMMARY 
     Apparatus for plasma processing are provided herein. In some embodiments, a process chamber includes: a chamber body having a processing volume within; a dielectric adapter ring disposed atop the chamber body; a multi-zone showerhead disposed atop the dielectric adapter ring to provide process gas to the processing volume; and an inductively-coupled RF coil disposed about an upper portion of the chamber body to couple RF energy to the processing volume. 
     Other and further embodiments of the present disclosure are described below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the present disclosure, briefly summarized above and discussed in greater detail below, can be understood by reference to the illustrative embodiments of the disclosure depicted in the appended drawings. However, the appended drawings illustrate only typical embodiments of the disclosure and are therefore not to be considered limiting of scope, for the disclosure may admit to other equally effective embodiments. 
         FIG. 1  depicts a process chamber in accordance with some embodiments of the present disclosure. 
     
    
    
     To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. The figures are not drawn to scale and may be simplified for clarity. Elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation. 
     DETAILED DESCRIPTION 
     Apparatus for plasma processing are provided herein. The inventive apparatus includes one or more inductive coils surrounding the processing volume and a multi-zone showerhead which, together, advantageously improve gas distribution and deposition uniformity on the substrate being processed. The configuration of the inventive apparatus advantageously eliminates the m-shaped deposition that results from conventional inductively coupled plasma processing chambers. Due to the increased surface area compared with the conventional central gas nozzle, the multi-zone showerhead provides a more uniform gas distribution in the process chamber. 
       FIG. 1  depicts a schematic side view of an exemplary inductively coupled plasma reactor (reactor  100 ) in accordance with some embodiments of the present disclosure. Although embodiments consistent with the present disclosure are described herein with respect to inductively coupled plasma reactor, embodiments consistent with the present disclosure may be used in conjunction with any chamber with an inductive coupled plasma chamber. 
     The reactor  100  may be utilized alone or, as a processing module of an integrated semiconductor substrate processing system, or cluster tool, such as a CENTRIS™ SYM3™ integrated semiconductor wafer processing system, available from Applied Materials, Inc. of Santa Clara, Calif. Examples of suitable plasma reactors that may advantageously benefit from modification in accordance with embodiments of the present disclosure include inductively coupled plasma etch reactors such as the MESA™, CENTURA® or DPS® line of semiconductor equipment (such as the DPS®, DPS® II, DPS® AE, DPS® G3 poly etcher, DPS® G5, or the like) also available from Applied Materials, Inc. The above listing of semiconductor equipment is illustrative only, and other etch reactors, and non-etch equipment (such as CVD reactors, or other semiconductor processing equipment) may also be suitably modified in accordance with the present teachings. 
     The reactor  100  includes an inductively coupled plasma apparatus  102  disposed about a process chamber  104 . The inductively coupled plasma apparatus includes an RF feed structure for coupling an RF power supply  108  to a one or more RF coils, e.g., RF coil  110 . The RF coil  110  is coaxially disposed about an upper portion of the process chamber  104  and is configured to inductively couple RF power into the process chamber  104  to form a plasma from process gases provided within the process chamber  104 . The RF power supply  108  is coupled to the RF feed structure via a match network  114 . 
     The reactor  100  generally includes the process chamber  104  having a conductive body (wall  130 ) and a dielectric adapter ring  120  on which a multi-zone showerhead  121  is disposed (all of which define a processing volume). The process chamber further includes a substrate support  116  disposed within the processing volume, the inductively coupled plasma apparatus  102 , and a controller  140 . The wall  130  is typically coupled to an electrical ground  134 . In some embodiments, the substrate support  116  may provide a cathode coupled through a matching network  124  to a biasing power source  122 . The biasing power source  122  may illustratively be a source of up to 1000 W at a frequency of approximately 13.56 MHz that is capable of producing either continuous or pulsed power, although other higher or lower frequencies and powers may be provided as desired for particular applications. In other embodiments, the biasing power source  122  may be a DC or pulsed DC source. 
     In some embodiments, a link  185  may be provided to couple the RF power supply  108  and the biasing power source  122  to facilitate synchronizing the operation of one source to the other. Either RF source may be the lead, or master, RF generator, while the other generator follows, or is the slave. The link  185  may further facilitate operating the RF power supply  108  and the biasing power source  122  in perfect synchronization, or in a desired offset, or phase difference. The phase control may be provided by circuitry disposed within either or both of the RF power sources or within the link between the RF power sources. The phase control between the source and bias RF generators (e.g.,  108 ,  122 ) may be provided and controlled independent of the phase control over the RF current flowing in the RF coil coupled to the RF power supply  108 . 
     The inductively coupled plasma apparatus  102  includes the RF coil  110  disposed about an upper portion of the process chamber  104 , specifically, about the dielectric adapter ring  120 . The relative position, diameter of the coil, and/or the number of turns in the coil can each be adjusted as desired to control, for example, the profile or density of the plasma being formed via controlling the inductance on each coil. The RF coil  110  is coupled through the matching network  114  to the RF power supply  108 . The RF power supply  108  may illustratively be capable of producing up to 4000 W at a tunable frequency in a range from 50 kHz to 13.56 MHz, although other higher or lower frequencies and powers may be provided as desired for particular applications. 
     During operation, a substrate  101  (such as a semiconductor wafer or other substrate suitable for plasma processing) may be placed on the substrate support  116  and process gases may be supplied from a gas panel  138  through the multi-zone showerhead  121  to form a gaseous mixture  150  within the process chamber  104 . In some embodiments, the process chamber  104  may also include gas inlet ports  126  disposed in the wall  130  or through the dielectric adapter ring  120  to provide additional process gas into the processing volume from the sides of the chamber. The gaseous mixture  150  may be ignited into a plasma  155  in the process chamber  104  by applying power from the RF power supply  108  to the RF coil  110  and optionally, one or more electrodes (not shown). The size and shape of the dielectric adapter ring  120  may be varied to provide more control of the electric field within the process chamber  104 . For example, the dielectric adapter ring  120  may be dome-shaped to provide a more uniform electric field. 
     In some embodiments, power from the biasing power source  122  may be also provided to the substrate support  116 . The pressure within the interior of the process chamber  104  may be controlled using a throttle valve  127  and a vacuum pump  136 . The temperature of the wall  130  may be controlled using liquid-containing conduits (not shown) that run through the wall  130 . 
     The temperature of the substrate  101  may be controlled by stabilizing a temperature of the substrate support  116 . In one embodiment, helium gas from a gas source  148  may be provided via a gas conduit  149  to channels defined between the backside of the substrate  101  and grooves (not shown) disposed in the substrate support surface. The helium gas is used to facilitate heat transfer between the substrate support  116  and the substrate  101 . During processing, the substrate support  116  may be heated by a resistive heater (not shown) within the substrate support to a steady state temperature and the helium gas may facilitate uniform heating of the substrate  101 . 
     The controller  140  comprises a central processing unit (CPU)  144 , a memory  142 , and support circuits  146  for the CPU  144  and facilitates control of the components of the reactor  100  and, as such, of methods of forming a plasma, such as discussed herein. The controller  140  may be any form of general-purpose computer processor that can be used in an industrial setting for controlling various chambers and sub-processors. The memory, or computer-readable medium,  142  of the CPU  144  may be one or more of readily available memory such as random access memory (RAM), read only memory (ROM), floppy disk, hard disk, or any other form of digital storage, local or remote. The support circuits  446  are coupled to the CPU  144  for supporting the processor in a conventional manner. These circuits include cache, power supplies, clock circuits, input/output circuitry and subsystems, and the like. The method for forming plasma may be stored in the memory  142  as software routine that may be executed or invoked to control the operation of the reactor  100  in the manner described above. 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  144 . The controller  140  controls the RF power supply  108 , the matching network  114 , to provide the desired current through the RF coil  110 . 
     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.