Abstract:
Methods and apparatus for processing semiconductor substrates are described. A processing chamber includes a substrate support with an in-situ plasma source, which may be an inductive, capacitive, microwave, or millimeter wave source, facing the substrate support and a radiant heat source, which may be a bank of thermal lamps, spaced apart from the substrate support. The support may be between the in-situ plasma source and the radiant heat source, and may rotate. A method or processing a substrate includes forming an oxide layer by exposing the substrate to a plasma generated in a process chamber, performing a plasma nitridation process on the substrate in the chamber, thermally treating the substrate using a radiant heat source disposed in the chamber while exposing the substrate to oxygen radicals formed outside the chamber, and forming an electrode by exposing the substrate to a plasma generated in the chamber.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims benefit of U.S. Provisional Patent Application Ser. No. 61/448,102 filed Mar. 1, 2011, which is herein incorporated by reference. 
     
    
     FIELD 
       [0002]    Embodiments described herein relate to semiconductor manufacturing processes and apparatus. More specifically, methods and apparatus for forming and treating material layers on semiconductor substrates are disclosed. 
       BACKGROUND 
       [0003]    The CMOS field-effect transistor is the functional core of most semiconductor devices. Over the past 50 years, Moore&#39;s Law has driven reduction in the size of MOSFETs and closer packing of MOSFETs on smaller chips. As size has been reduced, manufacturing challenges have mounted. 
         [0004]    Typically, a MOSFET includes a gate structure disposed over a channel region. The gate structure controls flow of electricity through the channel region by changing the electronic properties of the channel region when a voltage is applied to the gate structure. The gate structure generally includes a gate electrode and a gate dielectric between the gate electrode and the channel region. When a voltage is applied to the gate electrode, an electric field is established in the gate dielectric and the channel region that changes the flow of charge carriers through the channel region. 
         [0005]    The gate dielectric is typically formed from silicon nitride, silicon oxynitride, metal oxide, metal nitride, or metal silicate. The gate electrode is commonly silicon. Various processes, including plasma CVD, thermal treatment, DPN, RTP, remote plasma processes, and oxidation processes are commonly performed on a substrate to build a MOSFET gate structure. In one process, a layer of silicon oxide is formed on a substrate in a PECVD chamber. The substrate is moved to a DPN chamber for nitridation. The substrate is moved to an RTP chamber for re-oxidation. Then the substrate is moved to a second PECVD chamber for silicon deposition. The chambers are generally coupled to a transfer chamber that moves the substrates from process to process. 
         [0006]    Production platforms such as that described above, and the processes they perform, are expensive and have limited throughput. Pathways for processing substrates must be changed among the various chambers to change processing order, with impacts on throughput. Apparatus and methods of processing substrates using multi-functional chambers would streamline production, increase throughput, and reduce the need for substrate handling. 
         [0007]    Accordingly, there is a continuing need for efficient and cost-effecting methods and apparatus for forming gate structures on substrates. 
       SUMMARY 
       [0008]    A chamber for processing semiconductor substrates is described in one embodiment. The chamber includes a substrate support with an in-situ plasma source facing the substrate support and a radiant heat source spaced apart from the substrate support. The substrate support may be between the in-situ plasma source and the radiant heat source. The radiant heat source may be a bank of thermal lamps. The in-situ plasma source may be an inductive or capacitive plasma source, or a microwave or millimeter wave plasma source. 
         [0009]    The chamber may include a remote plasma source connected to the chamber and disposed through a wall facing the substrate support or adjacent to the substrate support. The remote plasma source may be connected to a gas distributor disposed through the in-situ plasma source. A window may be disposed between the radiant heat source and the substrate support, and the substrate support may rotate. 
         [0010]    In another embodiment, a chamber is described having a high ion density plasma source and a low ion density plasma source, both positioned to expose a substrate disposed on a substrate support to a plasma. A radiant heat source may be included in the chamber, and may be located with the substrate support between the plasma sources and the radiant heat source. 
         [0011]    In another embodiment, a method of processing a substrate in a processing chamber is provided. The method includes forming an oxide layer on the substrate by exposing the substrate to a plasma generated in the chamber, performing a plasma nitridation process on the substrate in the chamber, thermally treating the substrate using a radiant heat source disposed in the chamber while exposing the substrate to oxygen radicals formed outside the chamber, and forming an electrode on the substrate by exposing the substrate to a plasma generated in the chamber. The above steps may be performed without removing the substrate from the chamber. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    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. 
           [0013]      FIG. 1  is a cross-sectional view of a processing chamber according to one embodiment. 
           [0014]      FIG. 2  is a flow diagram summarizing a method according to another embodiment. 
       
    
    
       [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 disclosed in one embodiment may be beneficially utilized on other embodiments without specific recitation. 
       DETAILED DESCRIPTION 
       [0016]    A multi-functional chamber may be configured to perform a variety of material and thermal processes on a substrate without removing the substrate from the chamber.  FIG. 1  is a cross-sectional view of such a chamber  100  according to one embodiment. The chamber of  FIG. 1  is capable of performing various plasma and thermal deposition and treatment processes on a substrate simultaneously, concurrently, or sequentially. The substrate may remain in the chamber while a series of processes is performed on the substrate, or the substrate may be removed at times and returned later to the chamber for subsequent processing. 
         [0017]    The chamber  100  of  FIG. 1  has an enclosure  102  with a first portion  104 , a second portion  106 , and a third portion  108 . The enclosure  102  may be anodized aluminum or quartz, or may be anodized aluminum with a quartz chamber liner, such materials being resistant to most processes performed in manufacturing field-effect transistors. The first, second, and third portions  104 ,  106 , and  108 , may be formed integrally together or removably attached using fasteners (not shown). 
         [0018]    A substrate support  110  is disposed within the enclosure  102 , and extends through the third portion  108  to a control assembly  112 . The control assembly  112  may have a motor rotationally coupled to the substrate support  110 , a thermal control module  114  for providing a thermal control fluid through a conduit  116  in the substrate support, and an electrical unit  118  for providing electrical bias to the substrate support  110  or for electrostatically immobilizing a substrate on the substrate support  110 . 
         [0019]    A plasma source  120  is disposed in the first portion  104  of the enclosure  102  facing the substrate support  110 . The plasma source  120  is an inductive plasma source comprising a plurality of conductive loops  122  energized by one or more RF power sources  124 . A process gas source  160  is fluidly coupled to the chamber  100  by a process gas conduit  126  disposed through the plasma source  120 , with a gas distributor  128  positioned in a central portion of the plasma source  120  facing the substrate support  110 . Process gases to be activated by the plasma source  120  may be provided to the chamber  100  through the gas distributor  128 . An inductive plasma source useful in the chamber  102  is described in commonly assigned U.S. patent application Ser. No. 12/780,531, entitled “Inductive Plasma Source With Metallic Shower Head Using B-Field Concentrator”, filed May 14, 2010, and incorporated herein by reference. 
         [0020]    A heat source  130  is disposed in the enclosure  102 , spaced apart from a surface  132  of the substrate support  110 . The heat source  130  may be a radiant heat source, for example a plurality of heat lamps, which may be arranged in a bank, for example in a honeycomb pattern. A quartz window  134  is disposed between the heat source  130  and the substrate support  110  to control the radiation from the heat source  130 , for example by allowing for filters to be applied to the quartz window to filter desired wavelengths and allow other wavelengths to propagate. The quartz window  134  may protect the heat source  130  from the process environment of the chamber  100 . The substrate support  110  is shown positioned between the heat source  130  and the plasma source  120  for convenience, but such positioning is not required. For example, an annular heat source may be positioned around a periphery of the second part  106  of the enclosure  102  between the substrate support  110  and the plasma source  120 , with a quartz window or shield separating the heat source from the process environment. In the embodiment of  FIG. 1 , the substrate support  110  may comprise a material that is substantially transparent to the radiation from the heat source  130 , enabling thermal processing of a substrate disposed on the surface  132  of the substrate support  110 . 
         [0021]    A source of radicals  136  may be coupled to the chamber  100  through the process gas conduit  126  and gas distributor  128 , or through alternative access points. The source of radicals  136  may be a remote plasma source, which may be energized by RF or microwave power. 
         [0022]    Gases are exhausted from the chamber by coupling a pumping port  150  with a vacuum source  152 . The pumping port  150  may be at any convenient location of the chamber. In the embodiment of  FIG. 1 , the pumping port  150  is a pumping plenum disposed in the second portion  106  of the enclosure  102  near the surface  132  of the substrate support  110 . A substantially continuous opening  162  leads to a channel  154  that circumnavigates the chamber  100  and is connected to a vacuum conduit  156  leading to the vacuum source  152 . The pumping port may also be a round portal formed in the enclosure  102  and coupled to the vacuum source  152  by a conduit. 
         [0023]    The plasma source  120  of  FIG. 1 , as shown and described, is an inductive plasma source. In alternate embodiments, the plasma source  120  may be a capacitive plasma source such as a planar gas distributor disposed facing the substrate support  110  and generally parallel thereto. The planar gas distributor may have gas flow openings disposed through the surface of the gas distributor that faces the substrate support  110 . The gas flow openings will generally communicate with one or more gas plenums formed in the gas distributor to ensure gas flows evenly through all the openings. Thermal control channels may be interspersed with the gas flow plenums to afford heating or cooling of the gas distributor and/or gases flowing through the gas distributor. Electrical power such as RF power is coupled to the planar gas distributor, the substrate support, or both to establish an electric field between the gas distributor and the substrate support. 
         [0024]    In another embodiment, the plasma source  120  of  FIG. 1  may be a microwave or millimeter wave source. A coaxial source of long-wave radiation may be disposed in a configuration facing the substrate support  110 , with a reflector between the coaxial source and the first portion  104  of the enclosure  102  to direct the emitted radiation toward the substrate support  110 . The coaxial source may be one or more coaxial cables arranged in an antenna structure that may be a spiral shape, a boustrophedonic shape, or any desired distributed shape. A magnetron power source is typically coupled to the coaxial antenna structure to establish the radiation field. 
         [0025]    In the embodiment of  FIG. 1 , the substrate support  110  as shown and described is a pedestal-style substrate support. In an alternate embodiment, the substrate may be supported by an support ring extending inward from the second portion  106  of the enclosure between the heat source  130  and the plasma source  120 . Such an arrangement may provide more direct access to the substrate for the heat source  130 . In embodiments wherein the heat source  130  is a lamp array, a plurality of lift pins may be interspersed with the lamps and actuated by a lift pin assembly to engage the substrate and lift it above the support ring for transporation into and out of the chamber  100 . 
         [0026]      FIG. 2  is a flow diagram summarizing a method  200  according to another embodiment. At  202 , a substrate is disposed on a substrate support in a multi-functional chamber, such as the chamber  100  of  FIG. 1 . At  204 , the substrate is exposed to a plasma formed in the multi-functional chamber, and a layer is deposited on the substrate. A plasma source, which may be inductive or capacitive, disposed in the multi-functional chamber is energized with electric power, for example RF power at one or more frequencies between about 300 kHz and about 1,000 MHz, for example about 13.56 MHz. A deposition precursor gas is provided to a reaction space between the plasma source and the substrate support and activated by the plasma source. The activated precursor forms a layer on the substrate. In one embodiment, the deposition precursor is a silicon source such as silane, which forms a layer of silicon on the substrate. In another embodiment, the deposition precursor is a nitrogen source, such as nitrogen gas or ammonia, which may add nitrogen to the surface of the substrate, for example in a DPN process. In another embodiment, the deposition precursor may be a metal source or reducing gas for performing an ALD process. In general, the plasma formed in the chamber is an ion-rich plasma or a plasma having high ion density. 
         [0027]    At  206 , the substrate is exposed to a plasma formed outside the chamber, for example in a microwave or RF chamber remote from the chamber containing the substrate. The plasma is flowed into the chamber containing the substrate, and the substrate is exposed to the plasma. The plasma may be a remote plasma, but is generally a radical-rich plasma or a plasma having high radical density and/or low ion-density. Such a plasma may be provided to perform an oxidation process to repair an oxide layer that has been exposed to an ion-reactive process previously, such as the operation  204 . Such a plasma may also be an nitrogen and fluorine containing plasma provided to perform a cleaning operation on the substrate. In some embodiments, a remote plasma may be provided to the chamber and re-activated by forming an electric field in the chamber, as in the operation  204  described above. 
         [0028]    At  208 , a radiant heat source disposed in the multi-functional chamber is activated to perform a thermal process on the substrate. The thermal process may be performed in the presence of a reactive gas, which may be activated by a plasma source disposed in the chamber, remote from the chamber, or both. In one example, a reoxidation process may be performed by activating the radiant heat source and heating the substrate to a temperature of at least about 600° C. while providing a gas comprising oxygen radicals. Such a reoxidation process may follow a process in which the substrate is exposed to a plasma formed in the chamber, such as the operation  204  described above. In one embodiment, a DPN operation and a subsequent reoxidation operation are performed on a substrate in a single multi-functional chamber such as the chamber  100  of  FIG. 1 . In another embodiment, the thermal process may be a dopant activation process performed following a plasma doping operation. 
         [0029]    At  210 , a second layer is deposited on the substrate by forming a plasma in the multi-functional chamber. The second layer may be any layer typically formed by a plasma deposition process, include a second silicon layer, a metal oxide layer, a doped silicon layer, and the like. 
         [0030]    While the foregoing is directed to embodiments of the invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof.