Abstract:
A method and apparatus for a showerhead is provided. In one embodiment, a showerhead for a semiconductor processing chamber is disclosed. The showerhead includes a body comprising a plurality of plates made of a dieletric material and having a plurality of holes formed therethrough, and a first conductive layer and a second conductive layer disposed in between the plates at different locations in the body.

Description:
BACKGROUND 
       [0001]    Field 
         [0002]    Embodiments of the disclosure generally relate to a semiconductor processing chamber and, more specifically, heated support pedestal for a semiconductor processing chamber. 
         [0003]    Description of the Related Art 
         [0004]    Semiconductor processing involves a number of different chemical and physical processes whereby minute integrated circuits are created on a substrate. Layers of materials which make up the integrated circuit are created by chemical vapor deposition, physical vapor deposition, epitaxial growth, and the like. Some of the layers of material are patterned using photoresist masks and wet or dry etching techniques. The substrate utilized to form integrated circuits may be silicon, gallium arsenide, indium phosphide, glass, or other appropriate material. 
         [0005]    In the manufacture of integrated circuits, plasma processes are often used for deposition or etching of various material layers. Plasma processing offers many advantages over thermal processing. For example, plasma enhanced chemical vapor deposition (PECVD) allows deposition processes to be performed at lower temperatures and at higher deposition rates than achievable in analogous thermal processes. Thus, PECVD is advantageous for integrated circuit fabrication with stringent thermal budgets, such as for very large scale or ultra-large scale integrated circuit (VLSI or ULSI) device fabrication. 
         [0006]    The processing chambers used in these processes typically include a gas distribution plate or showerhead disposed therein to disperse gases during processing. Some of these showerheads may function as an electrode in a plasma process and are typically formed from an electrically conductive material. Spacing between the showerhead and the substrate are tightly controlled in order to promote uniform plasma formation and uniform deposition on the substrate. The conventional showerheads are typically heated by external heating elements to temperatures of about 250 degrees Celsius up to about 300 degrees Celsius. However, the conventional showerheads may bend or deflect (i.e., “droop”) at these temperatures which results in undesirable effects, such as non-uniform deposition and/or non-uniform plasma formation. 
         [0007]    Therefore, what is needed is a showerhead having a heater embedded in a material that resists deflection at operating temperatures. 
       SUMMARY 
       [0008]    A method and apparatus for a showerhead is provided. In one embodiment, a showerhead for a semiconductor processing chamber is provided. The showerhead includes a body comprising a plurality of plates made of a dieletric material and having a plurality of holes formed therethrough, and a first conductive layer and a second conductive layer disposed in between the plates at different locations in the body. 
         [0009]    In another embodiment, a showerhead for a semiconductor processing chamber is provided. The showerhead includes a body comprising a first plate, a second plate and a third plate, each of the plates made of a dieletric material and having a plurality of holes formed therethrough, a first conductive layer disposed between the first and second plates, and a second conductive layer disposed between the second and third plates. 
         [0010]    In another embodiment, a showerhead for a semiconductor processing chamber is provided. The showerhead includes a body comprising a plurality of plates made of a dieletric material and having a plurality of holes formed therethrough, and a first conductive layer and a second conductive layer disposed in between the plates at different locations in the body, wherein the first conductive layer comprises a heater and a radio frequency electrode. 
     
    
     
       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  is a schematic cross sectional view of a portion of a plasma system. 
           [0013]      FIG. 2  is an exploded view of a portion of the showerhead of  FIG. 1 . 
           [0014]      FIG. 3  is a plan view of the showerhead along lines  3 - 3  of  FIG. 2 . 
           [0015]      FIG. 4  is an enlarged plan view of a portion of the showerhead of  FIG. 3 . 
           [0016]      FIG. 5  is a cross sectional view of a portion of another embodiment of a plasma system utilizing embodiments of the showerhead as described herein. 
           [0017]      FIG. 6  is an exploded view of another embodiment of a showerhead that may be used in the plasma system of  FIG. 1  or  FIG. 5 . 
       
    
    
       [0018]    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 
       [0019]    Embodiments of the present disclosure are illustratively described below in reference plasma chambers, such as plasma chambers used for deposition or etch processes. 
         [0020]      FIG. 1  is a schematic cross sectional view of a portion of a plasma system  100 . The plasma system  100  generally comprises a processing chamber body  105  having a sidewall  110 . A slit valve opening  112  is formed in the sidewall for transfer of a substrate (not shown) into and out of a processing volume  115 . A lid plate  120  and a bottom  125 , as well as the sidewall  110 , bound the processing volume  115 . A pedestal (not shown in  FIG. 1 ) is positioned in the processing volume  115  for supporting the substrate therein. 
         [0021]    A lid assembly  130  is disposed on the lid plate  120 . The lid assembly  130  facilitates delivery of processing gas as well as electromagnetic energy delivery to the processing volume  115 . The lid assembly  130  includes one or more of a gas box  135 , a blocker plate assembly  140 , a showerhead interface plate  145  and a showerhead  150 . The lid assembly  130  may also include a first or upper radio frequency (RF) tuner plate  155  and a dielectric isolator ring  160 . The blocker plate assembly  140  may include an upper or first blocker plate  165  and a lower or second blocker plate  170 . A clamp plate  172  may be used to secure the lid assembly  130  to the chamber body  105 . 
         [0022]    The showerhead  150  may be coupled to a power supply  175  for providing power to a heater (shown in  FIG. 2 ) embedded in the showerhead  150 . The showerhead  150  may also be coupled to a RF power source  180  for enabling a plasma in the processing volume  115 . Additionally, the showerhead  150  may be coupled to a temperature control circuit  185  that facilitates closed-loop temperature control of the showerhead  150 . Seals  190 , such as elastomeric O-rings, may be provided at a perimeter of the showerhead  150  to seal the processing volume  115 . 
         [0023]      FIG. 2  is an exploded view of a portion of the showerhead  150  of  FIG. 1 . The showerhead  150  comprises a body  200  having a plurality of plates, such as a first plate  205 , a second plate  210  and a third plate  215 . Each of the plates  205 ,  210  and  215  may be made of one or more layers of a dielectric material or a ceramic material. In one embodiment, the plates  205 ,  210  and  215  comprise one or more layers of aluminum nitride (AlN). A conductive material layer, shown as a first conductive layer  220  and a second conductive layer  225 , is provided between the plates  205 ,  210  and  215 . The first conductive layer  220  may be thermocouple trace (i.e., a wire or wires) and the second conductive layer  225  may be a heater trace (i.e., a wire or wires). Dimensions of the wires of the second conductive layer  225  may be about 0.03 inches wide by about 0.007 inches thick in one embodiment. 
         [0024]    Holes  230  are formed in each of the plates  205 ,  210  and  215  for dispersing gases through the body  200 . The holes  230  may be formed mechanically (i.e., drilled) or with a laser when the plates  205 ,  210  and  215  are in a green state (prior to sintering). The first conductive layer  220  and the second conductive layer  225  are formed around the holes  230  to ensure electrical continuity. Each of the holes  230  may have a diameter of about 0.02 inches to about 0.032 inches, such as about 0.026 inches to about 0.03 inches. In some embodiments, the number of holes  230  is about 9,000 to about 10,000. 
         [0025]    The plates  205 ,  210  and  215  shown in  FIG. 2  are exploded and may be pressed together or fused to each other in a sintering process to embed the first conductive layer  220  and the second conductive layer  225  within the body  200 . The first conductive layer  220  and the second conductive layer  225  may be a conductive metallic material such as copper, aluminum, tungsten, or combinations thereof. The first conductive layer  220  and the second conductive layer  225  may be deposited onto the plates  205 ,  210  and  215  by a silkscreen printing process, or other conventional deposition process. A thickness  235  of each of the plates  205 ,  210  and  215  may be about 1.5 microns (μm) to about 2 μm. In some embodiments, a thickness of the body  200  when the plates  205 ,  210  and  215  contact each other and/or are fused may be about 5.0 μm to about 6.5 μm. 
         [0026]      FIG. 3  is a plan view of the showerhead  150  along lines  3 - 3  of  FIG. 2 . The second conductive layer  225  is shown as a wire or wires on the plate  210 . The second conductive layer  225  may define a heater  300  within the showerhead  150 . Holes  230  are formed through the plate  210  and are concentric with holes on the plate  215  (not shown but below the plate  210 . Terminals  305  may be provided to couple the heater  300  to the power supply  175  (shown in  FIG. 1 ). Additionally, a seal region  310  may be disposed at a perimeter  315  of the showerhead  150 . The seal region may be disposed on the plate  205  (shown in  FIG. 2 ) and the heater  300  may be covered by the plate  205  shown in  FIG. 2 . 
         [0027]    In some embodiments, a diameter  320  of the showerhead  150  (e.g., the outside dimension of the plates  205 ,  210  and  215 ) may be about 16.5 inches to about 17.5 inches. In some embodiments, a width  325  of the seal region  310  may be about 1 inch. 
         [0028]      FIG. 4  is an enlarged plan view of a portion of the showerhead  150  of  FIG. 3 . The holes  230  and the second conductive layer  225  are more clearly shown in this view. The terminals are shown coupled to the power supply  175  and the heater  300  is coupled to the RF power source  180 . Additionally, one or more resistive temperature devices  400  and  405  are shown on the showerhead  150 . The resistive temperature devices  400  and  405  may be thermal sensors or thermocouples that are in electrical communication with the first conductive layer  220  shown in  FIG. 2 . The resistive temperature devices  400  and  405  may be coupled to the temperature control circuit  185  via the first conductive layer  220  in order to control temperature of the heater  300 . The resistive temperature device  400  may be an over-temperature sensor while the resistive temperature device  405  may be a control sensor. 
         [0029]      FIG. 5  is a cross sectional view of a portion of another embodiment of a plasma system  500 . The plasma system  500  generally comprises a processing chamber body  105  having a sidewall  110 , a bottom  125 , and an interior sidewall  505  defining a pair of processing regions  520 A and  520 B. Each of the processing regions  520 A-B is similarly configured, and for the sake of brevity, only components in the processing region  520 B will be described. 
         [0030]    A pedestal  510  is disposed in the processing region  520 B through a passage  515  formed in the bottom wall  516  in the system  500 . The pedestal  510  is adapted to support a substrate (not shown) on the upper surface thereof. The pedestal  510  may include heating elements, for example resistive elements, to heat and control the substrate temperature in a desired process temperature. Alternatively, the pedestal  510  may be heated by a remote heating element, such as a lamp assembly. 
         [0031]    The pedestal  510  is coupled by a stem  526  to a power outlet or power box  525 , which may include a drive system that controls the elevation and movement of the pedestal  510  within the processing region  520 B. The stem  526  also contains electrical power interfaces to provide electrical power to the pedestal  510 . The power box  525  also includes interfaces for electrical power and temperature indicators, such as a thermocouple interface. The stem  526  also includes a base assembly  529  adapted to detachably couple to the power box  525 . A circumferential ring  535  is shown above the power box  525 . In one embodiment, the circumferential ring  535  is a shoulder adapted as a mechanical stop or land configured to provide a mechanical interface between the base assembly  529  and the upper surface of the power box  525 . 
         [0032]    A rod  530  is disposed through a passage  524  formed in the bottom  125  and is utilized to activate substrate lift pins  532  disposed through the pedestal  510 . The substrate lift pins  532  selectively space the substrate from the pedestal to facilitate exchange of the substrate with a robot (not shown) utilized for transferring the substrate into and out of the processing region  520 B through a slit valve opening  112 . 
         [0033]    A lid plate  120  is coupled to a top portion of the chamber body  105 . The lid plate  120  accommodates a lid assembly  130  as described in  FIG. 1 . The lid assembly  130  includes a gas inlet passage  540  which delivers reactant and cleaning gases through a blocker plate assembly  140  and a showerhead  150 , as described herein, into the processing region  520 B. A RF source  180  is coupled to the showerhead  150  as described herein. The RF source  180  powers the showerhead  150  to facilitate generation of a plasma between the showerhead  150  and the heated pedestal  510 . In one embodiment, the RF source  180  may be a high frequency radio frequency (HFRF) power source, such as a 13.56 MHz RF generator. In another embodiment, RF source  180  may include a HFRF power source and a low frequency radio frequency (LFRF) power source, such as a 300 kHz RF generator. The dielectric isolator ring  160  is disposed between the lid plate  120  and the lid assembly  130  to prevent conducting RF power to the lid plate  120 . A shadow ring  544  may be disposed on the periphery of the pedestal  510  that engages the substrate at a desired elevation of the pedestal  510 . 
         [0034]    A chamber liner assembly  546  is disposed within the processing region  520 B in very close proximity to the sidewalls  505 ,  110  of the chamber body  105  to prevent exposure of the sidewalls  505 ,  110  to the processing environment within the processing region  520 B. The liner assembly  546  includes a circumferential pumping cavity  548  that is coupled to a pumping system  550  configured to exhaust gases and byproducts from the processing region  520 B and control the pressure within the processing region  520 B. A plurality of exhaust ports  555  may be formed on the chamber liner assembly  546 . The exhaust ports  555  are configured to allow the flow of gases from the processing region  520 B to the circumferential pumping cavity  548  in a manner that promotes processing within the system  500 . 
         [0035]    In one embodiment, the plasma system  500  is utilized in a plasma enhanced chemical vapor deposition (PECVD) system. Examples of PECVD systems that may be adapted to benefit from the disclosure include a PRODUCER® SE CVD system, a PRODUCER® GT™ CVD system or a DXZ® CVD system, all of which are commercially available from Applied Materials, Inc., Santa Clara, Calif. The Producer® SE CVD system (e.g., 200 mm or 300 mm) has two isolated processing regions that may be used to deposit thin films on substrates, such as conductive films, silanes, carbon-doped silicon oxides and other materials. Although the exemplary embodiment includes two processing regions, it is contemplated that the disclosure may be used to advantage in systems having a single processing region or more than two processing regions. It is also contemplated that the disclosure may be utilized to advantage in other plasma chambers, including etch chambers, ion implantation chambers, plasma treatment chambers, and stripping chambers, among others. It is further contemplated that the disclosure may be utilized to advantage in plasma processing chambers available from other manufacturers. 
         [0036]      FIG. 6  is an exploded view of another embodiment of a showerhead  600  that may be used in the plasma system of  FIG. 1  or  FIG. 5 . The showerhead  600  comprises a body  605  having a plurality of plates, such as the first plate  205 , the second plate  210  and the third plate  215  having the first conductive layer  220  and the second conductive layer  225  disposed therebetween similar to the embodiment of  FIG. 2 . However, the showerhead  600  according to this embodiment includes a fourth plate  610  and a third conductive layer  615 . The third conductive layer  615  may be a metallic material layer such as copper, aluminum, tungsten or another conductive metal. The plate  610  may be a dielectric or ceramic material similar to the plates  205 ,  210  and  215  of  FIG. 2 . The plates  205 ,  210 ,  215  and  610  may have the same thickness as the plates  205 ,  210  and  215  of  FIG. 2 . The third conductive layer  615  may function as a RF electrode while the first conductive layer  220  and the second conductive layer  225  may function as described in  FIG. 2 . The third conductive layer  615  may be coupled to the RF power source  180  as shown in order to facilitate plasma formation with a pedestal (not shown). The third conductive layer  615  may be a mesh or array of wires having dimensions about 0.03 inches wide by about 0.007 inches thick in one embodiment. The third conductive layer  615  may be deposited onto the plate  205  or plate  610  by a silkscreen printing process, or other conventional deposition process. 
         [0037]    The plates  205 ,  210 ,  215  and  610  shown in  FIG. 6  are exploded and may be pressed together or fused to each other in a sintering process to embed the first conductive layer  220 , the second conductive layer  225  and the third conductive layer  615  within the body  605 . In some embodiments, a thickness of the body  605  when the plates  205 ,  210 ,  215  and  610  contact each other and/or are fused may be about 6.0 μm to about 7.5 μm. 
         [0038]    While the foregoing is directed to embodiments of the 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.