Abstract:
A novel heating method and a novel gas inject schemes for a depositing semiconductor layers on wafers with improved disposition uniformity and disposition composition, deposition rates and decreased depletion rates. The novel heating and gas design can be readily changed in size to accommodate the ever increasing demand for larger substrates, increased batch sizes and increased deposition and heating efficiencies. The heating scheme can operate to 1500° C., and has a high resolution capability for tuning the temperature and gas flows for easy of setup and improved control and repeatability of the deposition process. This novel heating and gas inject scheme in conjunction with the unconventional usage of a non-quartz process chamber promises higher throughputs and higher wafer yields and reduced manufacturing costs for the manufacturing of silicon devices, silicon solar cells and white High Brightness LEDs.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to U.S. Provisional Application No. 61/277,624, filed on Sep. 28, 2009 by the same inventor, the contents of which are incorporated by reference as though fully set forth herein. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    This invention relates generally to providing heat and deposition gas control during the deposition of material on a wafer or substrate used for example in the production of High Brightness Light Emitting Diodes (LEDs semiconductor devices), solar cells and other semiconductor devices. 
         [0004]    2. Description of the Related Art 
         [0005]    A typical semiconductor device layer(s) may be elements or compounds such as GaN, InN, AlN or Si deposited on wafers using a deposition system. These layers of elements and or compounds are essential to technologies such as modern microelectronics, solar cells and LED devices. 
         [0006]    It is desirable to increase the growth rate of the semiconductor material during the formation of the semiconductor layer so that more electronic devices and circuits can be formed in a given amount of time. It is desirable to control the uniformity of the semiconductor material allowing a number of identical electronic devices and circuits to be formed. The uniformity of the semiconductor material refers to the uniformity of its composition and the thickness of the layer. It is sometimes desirable to deposit semiconductor material that has the same composition from one location to another on the wafer. For example, it is known that gallium rich volumes are often undesirably formed when depositing gallium nitride. These gallium rich volumes can undesirably degrade the performance of an electronic device formed therewith. 
         [0007]    A heater assembly is often used to heat the wafer in the presence of reactant gases that decompose and or combine chemically depositing a layer of semiconductor materials on wafers. There are many different types of heater assemblies that can be used to heat the wafer, such as those disclosed in U.S. Pat. Nos. 6,331,212 and 6,774,060. Some heater assemblies provide heat through induction heating, and others provide heat through resistance heating. Some heater assemblies, such as the one disclosed in U.S. Pat. No. 4,081,313, provide heat through infrared lamps. 
         [0008]    However, there are several problems with deposition systems. One problem is the difficulty in uniformly heating the wafer(s) so that the semiconductor layers are deposited uniformly with a uniform composition. Another problem is controlling the process gases in order that the heated wafer(s) sees a composition of process gases that decompose and or combine so that the semiconductor layers are deposited uniformly with a uniform composition on the wafer. There is a crucial need in today&#39;s process requirements for epitaxial CVD, for systems with heating methods that provide improved wafer temperature control, uniformity and repeatability and reactant gas control and distribution over the wafer(s) so that semiconductor layers are deposited with improved film uniformity, higher throughput and a much reduced cost per wafer. 
       BRIEF SUMMARY OF THE INVENTION 
       [0009]    The present invention is directed to an apparatus for the chemical vapor deposition of semiconductor films specifically related to a novel heater assembly and gas introduction schemes. The novel features of the invention are set forth with particularity in the appended claims. The invention will be best understood from the following description when read in conjunction with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1   a  is a top view of one embodiment of a heater assembly  100   
           [0011]      FIG. 1   b  is a side view of one embodiment of a heater assembly  100   a  along cut line  1   b - 1   b  of  FIG. 1   a    
           [0012]      FIG. 1   c  is a side view of an embodiment of a heater assembly  100   a  along cut line  1   b - 1   b  of  FIG. 1   a    
           [0013]      FIG. 1   d  is a side view of another embodiment of a heater assembly  100   b  along cut line  1   b - 1   b  of  FIG. 1   a    
           [0014]      FIG. 1   e  is a representative heat/temperature profile of heater assembly  100  of  FIG. 1   b    
           [0015]      FIG. 1   f  is a representative heat/temperature profile along cut line heater assembly  100   a  of  FIG. 1   c    
           [0016]      FIG. 1   g  is a representative heat/temperature profile of a heater assembly 
           [0017]      FIG. 2   a  is a top view of one embodiment of heater plate  110   
           [0018]      FIG. 2   b  is a perspective view of heater plate  110   
           [0019]      FIG. 2   c  is a cut-away side view of heater plate  110   
           [0020]      FIG. 3   a  is a top view of inner segmented heater sub-assembly  120   
           [0021]      FIG. 3   b  is a perspective view of segmented heater sub-assembly  120   
           [0022]      FIG. 3   c  is side view of segmented heater sub-assembly  120   
           [0023]      FIG. 3   d  is a side view of inner segmented heater sub-assembly  120  in a region  129  of  FIG. 3   c    
           [0024]      FIG. 3   e  is a side view of another embodiment of inner segmented heater sub-assembly  120  in region  129   
           [0025]      FIG. 3   f  is a perspective view of heater sub-assembly  120  in region  129 , 
           [0026]      FIG. 4   a  is a top view of one embodiment of intermediate segmented heater sub-assembly  140   
           [0027]      FIG. 4   b  is a perspective view of intermediate segmented heater sub-assembly  140   
           [0028]      FIG. 4   c  is a cut-away side view of intermediate segmented heater sub-assembly  140  in region  149   
           [0029]      FIG. 4   d  is a side view of intermediate segmented heater sub-assembly  140  in region  149   
           [0030]      FIG. 4   e  is a side view of another embodiment of intermediate segmented heater sub-assembly  140  in region  149   
           [0031]      FIG. 4   f  is a perspective view of intermediate segmented heater sub-assembly  140  in region  149 , 
           [0032]      FIG. 5   a  is a top view of one embodiment of outer segmented heater sub-assembly  160   
           [0033]      FIG. 5   b  is a perspective view of outer segmented heater sub-assembly  160   
           [0034]      FIG. 5   c  is a cut-away side view of outer segmented heater sub-assembly  160   
           [0035]      FIG. 5   d  is a side view of outer segmented heater sub-assembly  160  in a region  169   
           [0036]      FIG. 5   e  is a side view of another embodiment of outer segmented heater sub-assembly  160   
           [0037]      FIG. 6  is a top view of one embodiment of a heater assembly  100   a    
           [0038]      FIG. 7  is a top view of one embodiment of coiled heater  110   
           [0039]      FIG. 8   a  is a perspective view of a heater coil  170   
           [0040]      FIG. 8   b  is a top views of a heater coil  170   
           [0041]      FIGS. 9   a  and  9   b  are perspective and top views, respectively, of another embodiment of a heater coil, denoted as heater coil  170   a    
           [0042]      FIGS. 10   a  and  10   b  are top and side views, respectively, of one embodiment of a coiled inner segmented heater assembly  181 . 
           [0043]      FIG. 11   a  and  11   b  are top and side views, respectively, of one embodiment of a coiled intermediate segmented heater assembly  182   
           [0044]      FIGS. 12   a  and  12   b  are top and side views, respectively, of one embodiment of a coiled outer segmented heater assembly  100 . 
           [0045]      FIG. 13   a  is a top view of one embodiment of a heater assembly  100   b    
           [0046]      FIG. 13   b  is a top view of one embodiment of a heater assembly  100   c    
           [0047]      FIG. 13   c  is a top view of one embodiment of a heater assembly  100   d    
           [0048]      FIG. 13   d  is a top view of one embodiment of a heater assembly  100   e    
           [0049]      FIG. 13   e  is a top view of one embodiment of a heater assembly  100   f    
           [0050]      FIG. 14   a  is a cut-away side view of deposition system  200   
           [0051]      FIG. 14   b  is cross sectional view of the interior of the deposition system  200   
           [0052]      FIG. 14   c  is cross sectional plan view along cut line  14   b - 14   b  of  FIG. 14   b    
           [0053]      FIG. 14   d  is a cross section plan view of heater array  100  along cut line  14   b   1 - 14   b   1  of  FIG. 14   b    
           [0054]      FIG. 14   e  is an expanded view of the upper and lower heater assemblies  100  of deposition system  200   
           [0055]      FIG. 14   f  is a thermal comparison of the embodiments herein versus two prior art technologies 
           [0056]      FIG. 15   a  is a side cross-sectional view of reactor chamber and gas system of deposition system  200   a.    
           [0057]      FIG. 15   b  is an expanded cross sectional side view of the gas injection scheme as defined by region  219  of  FIG. 14   b.    
           [0058]      FIG. 15   c  is a pictorial view of the one of the upstream gas inlet ports  226  and one of the downstream gas inlet ports  225 . 
           [0059]      FIG. 15   d  is an expanded view along cut line  15   d - 15   d  of  FIG. 15   c  of the downstream gas inlet port  229   
           [0060]      FIG. 15   e  is a plan view of the upstream gas injection embodiment of deposition system  200   
           [0061]      FIG. 15   f  is a plan view of the downstream gas inject embodiment of deposition system  200   
           [0062]      FIG. 16   a  is a cross sectional view of a vertical gas inject scheme of deposition system  200   b    
           [0063]      FIG. 16   b  is an exploded cross sectional view of a vertical gas inject scheme of deposition system  200   b    
           [0064]      FIG. 16   c  is a plan view of the upper plate of process chamber  204   c  a vertical gas inject scheme 
           [0065]      FIG. 15   d  is comparison of the depletion profile of prior art and the invention 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0066]    Heater assemblies disclosed herein provide heat during the deposition of material on a wafer. The material is deposited using a deposition system, such as a CVD, MBE, HVPE or MOCVD system. The material deposited on the wafer can be of many different types, such as semiconductor material. Electronic devices and circuitry are often formed on the wafer, wherein the electronic device and circuitry utilize the material deposited. 
         [0067]    The heater assemblies disclosed herein uniformly heat the wafer so that the material is deposited uniformly. Further, the material is deposited on the wafer at a faster rate so that more electronic devices and circuits can be formed in a given amount of time. 
         [0068]    The heater assemblies disclosed herein heat the wafer uniformly so that the material being deposited has a more uniform composition. In this way, the material deposited on the wafer is driven to have the same composition at different locations of the wafer. This is useful so that the electronic devices and circuits at different locations of the wafer are driven to be identical. 
         [0069]    The gas control, injection and distribution embodiments disclosed herein distribute process gases over wafer(s) more uniformly and with more control. The gases are distributed over areas of the wafer(s) being heated by the heater assemblies are controlled together so that material is deposited on the wafer more uniformly with a more uniform composition and at a faster rate. 
         [0070]      FIG. 1   a  is a top view of one embodiment of a heater assembly  100 , and  FIG. 1   b  is a cut-away side view of heater assembly  100  taken along a cut-line  1   b - 1   b  of  FIG. 1   a . In this embodiment, heater assembly  100  includes a heater plate sub-assembly  110 , and an inner segmented heater sub-assembly  120  spaced from heater plate sub-assembly  110  by an inner annular gap  105 . Inner annular gap  105  is dimensioned to prohibit the ability of current to flow between heater assemblies  110  and  120 . It is desirable to prohibit the ability of current to flow between heater assemblies  110  and  120  so that different adjustable power signals can be provided to each. The center  103  of heater assembly  100  may be coincident with the center of heater plate sub-assembly  110 . 
         [0071]    It is desirable to provide different adjustable power signals to heater assemblies  110  and  120  so they provide different adjustable amounts of heat. The amount of heat provided by heater assemblies  110  and  120  is adjustable in response to adjusting the corresponding adjustable power signals. It is desirable for heater assemblies  110  and  120  to provide different adjustable amounts of heat so they are thermally decoupled from each other. The thermal coupling between heater assemblies  110  and  120  is adjustable in response to adjusting the corresponding adjustable power signal. It is desirable to thermally decouple heater assemblies  110  and  120  so the uniformity of the heat provided by heater assembly  100  can be better controlled. The uniformity of the heat provided by heater assembly  100  is adjustable in response to adjusting the corresponding adjustable power signal provided to heater assemblies  110  and  120 . 
         [0072]    In this embodiment, heater assembly  100  includes an intermediate segmented heater sub-assembly  140  consisting of intermediate heater segment  140   a  and  140   b , spaced from inner segmented heater sub-assembly  120  by an intermediate annular gap  106 . Intermediate annular gap  106  is dimensioned to inhibit the ability of current to flow between heater assemblies  120  and  140 . It is desirable to inhibit the ability of current to flow between heater assemblies  110  and  120  so that different adjustable power signals can be provided to them. 
         [0073]    It is desirable to provide different adjustable power signals to heater assemblies  120  and  140  so they provide different adjustable amounts of heat. The amount of heat provided by heater assemblies  120  and  140  is adjustable in response to adjusting the corresponding adjustable power signals. It is desirable for heater assemblies  120  and  140  to provide different adjustable amounts of heat so they are thermally decoupled from each other. The thermal coupling between heater assemblies  120  and  140  is adjustable in response to adjusting the corresponding adjustable power signal. It is desirable to thermally decouple heater assemblies  120  and  140  so the uniformity of the heat provided by heater assembly  100  can be better controlled. The uniformity of the heat provided by heater assembly  100  is adjustable in response to adjusting the corresponding adjustable power signal provided to heater assemblies  120  and  140 . 
         [0074]    In this embodiment, heater assembly  100  includes an outer segmented heater sub-assembly  160  consisting of outer heater segment  160   a ,  160   b ,  160   c  and  160   d  spaced from intermediate segmented heater sub-assembly  140  by an outer annular gap  107 . Outer annular gap  107  is dimensioned to inhibit the ability of current to flow between heater assemblies  140  and  160 . It is desirable to prohibit the ability of current to flow between heater assemblies  140  and  160  so that different adjustable power signals can be provided to them. 
         [0075]    It is desirable to provide different adjustable power signals to heater sub-assemblies  140  and  160  so they provide different adjustable amounts of heat. The amount of heat provided by heater sub-assemblies  140  and  160  is adjustable in response to adjusting the corresponding adjustable power signals. It is desirable for heater sub-assemblies  140  and  160  to provide different adjustable amounts of heat so they are thermally decoupled from each other. The thermal coupling between heater sub-assemblies  140  and  160  is adjustable in response to adjusting the corresponding adjustable power signal. It is desirable to thermally decouple heater sub-assemblies  140  and  160  so the uniformity of the heat provided by heater assembly  100  can be better controlled. The uniformity of the heat provided by heater assembly  100  is adjustable in response to adjusting the corresponding adjustable power signal provided to heater sub-assemblies  140  and  160 . 
         [0076]    It should be noted that inner gap  105 , intermediate gap  106  and outer gap  107  are annular gaps because they extend annularly around heater plate sub-assembly  110 , inner segmented heater sub-assembly  120  and intermediate segmented heater sub-assembly  140 , respectively. 
         [0077]    In operation, different power signals are provided to heater plate sub-assembly  110 , inner segmented heater sub-assembly  120 , intermediate heater segment  140   a  and  140   b  of intermediate segmented heater sub-assembly  140  and outer heater sub-assembly  160   a ,  160   b ,  160   c  and  160   d  of outer segmented heater sub-assembly  160 . Heater plate sub-assembly  110 , inner segmented heater sub-assembly  120 , intermediate segmented heater sub-assembly  140  and outer segmented heater sub-assembly  160  provide heat in response to receiving the corresponding power signal. 
         [0078]    In one mode of operation, adjustable power signals are provided to heater plate sub-assembly  110 , inner segmented heater sub-assembly  120 , intermediate heater segment  140   a  and  140   b  of intermediate segmented heater sub-assembly  140  and outer heater segment  160   a ,  160   b ,  160   c  and  160   d  of outer segmented heater sub-assembly  160 , wherein the adjustable power signals are adjusted to regulate the amount of heat provided by heater assembly  100 . 
         [0079]    For example, in one embodiment, the amount of heat provided by heater assembly  100  is adjusted in response to adjusting the phases of the power signals. In one particular embodiment, an alternating current power signal is provided to heater plate sub-assembly  110 , inner segmented heater sub-assembly  120 , intermediate heater segment  140   a  and  140   b  of intermediate segmented heater sub-assembly  140  and outer heater segment  160   a ,  160   b ,  160   c  and  160   d  of outer segmented heater sub-assembly  160 . The phases of the alternating current power signals are adjusted relative to each other to adjust the amount of heat provided by heater assembly  100 . In this way, the amount of heat provided by heater assembly  100  is regulated in response to adjusting the phases of the power signals. 
         [0080]    In another embodiment, the amount of heat provided by heater assembly  100  is adjusted in response to adjusting the amplitudes of the power signals. In one particular embodiment, an alternating current power signal is provided to heater plate sub-assembly  110 , inner segmented heater sub-assembly  120 , intermediate heater segment  140   a  and  140   b  and outer heater segment  160   a ,  160   b ,  160   c  and  160   d  heater sub-assembly  160 . In this embodiment, the alternating current power signals can have different phases. In one embodiment, the alternating current power signals are out of phase by 120 degrees. Alternating current power signals out of phase by 120 degrees are often used in three-phase systems, such as a three-phase motor. In this way, the amount of heat provided by heater assembly  100  is adjusted in response to adjusting the amplitudes of the power signals. 
         [0081]    In one mode of operation, adjustable power signals are provided to heater plate sub-assembly  110 , inner segmented heater sub-assembly  120 , intermediate heater segment  140   a  and  140   b  of intermediate segmented heater sub-assembly  140  and outer heater segment  160   a ,  160   b ,  160   c  and  160   d  of outer segmented heater sub-assembly  160 , wherein the adjustable power signals are adjusted to adjust the thermal coupling between heater plate sub-assembly  110 , inner segmented heater sub-assembly  120 , intermediate segmented heater sub-assembly  140  and outer segmented heater sub-assembly  160 . 
         [0082]    For example, in one embodiment, the thermal coupling between heater plate sub-assembly  110 , inner segmented heater sub-assembly  120 , intermediate segmented heater sub-assembly  140  and outer segmented heater sub-assembly  160  is adjusted in response to adjusting the phases of the power signals. In one particular embodiment, a direct current power signal is provided to heater plate sub-assembly  110 , inner segmented heater sub-assembly  120 , intermediate heater segment  140   a  and  140   b  of intermediate segmented heater sub-assembly  140  and outer heater segment  160   a ,  160   b ,  160   c  and  160   d  of outer segmented heater sub-assembly  160 . The amplitude of the direct current power signals is adjusted relative to each other to adjust the thermal coupling between heater plate sub-assembly  110 , inner segmented heater sub-assembly  120 , intermediate heater segment  140   a  and  140   b  of intermediate segmented heater sub-assembly  140  and outer heater segment  160   a ,  160   b ,  160   c  and  160   d  of outer segmented heater sub-assembly  160 . In this way, the thermal coupling between heater plate sub-assembly  110 , inner segmented heater sub-assembly  120 , intermediate segmented heater sub-assembly  140  and outer segmented heater sub-assembly  160  is adjusted in response to adjusting the amplitude of the power signals. 
         [0083]    In another embodiment, the thermal coupling between heater plate sub-assembly  110 , inner segmented heater sub-assembly  120 , intermediate segmented heater sub-assembly  140  and outer segmented heater sub-assembly  160  is adjusted in response to adjusting the amplitudes of the power signals. In one particular embodiment, a direct current power signal is provided to heater plate sub-assembly  110 , and alternating current power signals are provided to inner segmented heater sub-assembly  120 , intermediate heater segment  140   a  and  140   b  of intermediate segmented heater sub-assembly  140  and outer heater segment  160   a ,  160   b ,  160   c  and  160   d  of outer segmented heater sub-assembly  160 . In this embodiment, the alternating current power signals can have many different phases. In one embodiment, the alternating current power signals are out of phase by 120 degrees. Alternating current power signals out of phase by 120 degrees are often used in three-phase high power systems, such as a three-phase motor. In this way, the thermal coupling between heater plate sub-assembly  110 , inner segmented heater sub-assembly  120 , intermediate heater segment  140   a  and  140   b  of intermediate segmented heater sub-assembly  140  and outer heater segment  160   a ,  160   b ,  160   c  and  160   d  of outer segmented heater sub-assembly  160  is adjusted in response to adjusting the amplitudes of the power signals. 
         [0084]    In one mode of operation, adjustable power signals are provided to heater plate sub-assembly  110 , inner segmented heater sub-assembly  120 , intermediate heater segment  140   a  and  140   b  of intermediate segmented heater sub-assembly  140  and outer heater segment  160   a ,  160   b ,  160   c  and  160   d  of outer segmented heater sub-assembly  160 , wherein the adjustable power signals are adjusted to adjust the uniformity of the heat provided by heater assembly  100 . 
         [0085]    In one particular embodiment, a direct current power signal is provided to heater plate sub-assembly  110 , and alternating current power signals are provided to inner segmented heater sub-assembly  120 , intermediate segmented heater sub-assembly  140  and outer segmented heater sub-assembly  160 . The phases of the alternating current power signals are adjusted relative to each other to adjust the uniformity of the heat provided by heater assembly  100 . In this way, the uniformity of the heat provided by heater assembly  100  is regulated in response to adjusting the phases of power signals. 
         [0086]    In another embodiment, the uniformity of the heat provided by heater assembly  100  is adjusted in response to adjusting the amplitudes of the power signals. In one particular embodiment, a direct current power signal is provided to heater plate sub-assembly  110 , and alternating current power signals are provided to inner segmented heater sub-assembly  120 , intermediate segmented heater sub-assembly  140  and outer segmented heater sub-assembly  160 . In this embodiment, the alternating current power signals can have many different phases. In one embodiment, the alternating current power signals are out of phase by 120 degrees. Alternating current power signals out of phase by 120 degrees are often used in high power electrical systems, such as a three-phase motor. In this way, the uniformity of the heat provided by heater assembly  100  is adjusted in response to adjusting the amplitudes of the power signals. 
         [0087]    It should also be noted that heater assembly  100 , as shown in  FIG. 1   b , has a uniform thickness. Heater assembly  100  of  FIG. 1   b  has a uniform thickness because the thicknesses of heater plate sub-assembly  110 , inner segmented heater sub-assembly  120 , intermediate heater segment  140   a  and  140   b  of intermediate segmented heater sub-assembly  140  and outer heater segment  160   a ,  160   b ,  160   c  and  160   d  of outer segmented heater sub-assembly  160  are the same thickness values between inner gap  105  and the outer periphery of outer segmented heater sub-assembly  160 . 
         [0088]    The thicknesses of heater plate sub-assembly  110 , inner segmented heater sub-assembly  120 , intermediate segmented heater sub-assembly  140  and outer segmented heater sub-assembly  160  are chosen to provide a desired resistance. The resistance of heater plate sub-assembly  110  increases and decreases as its thickness decreases and increases, respectively. The resistance of inner segmented heater sub-assembly  120  increases and decreases as its thickness decreases and increases, respectively. The resistance of intermediate heater segment  140   a  and  140   b  of intermediate segmented heater sub-assembly  140  increases and decreases as its thickness decreases and increases, respectively. The resistance outer heater segment  160   a ,  160   b ,  160   c  and  160   d  of outer segmented heater sub-assembly  160  increases and decreases as its thickness decreases and increases, respectively. It should be noted that, for a given amount of power, the amount of heat provided by a sub-assembly increases and decreases as its resistance increases and decreases, respectively. 
         [0089]      FIG. 1   c  is a side view of a heater assembly  100   a  having a non-uniform thickness. Heater assembly  100   a  has a non-uniform thickness because it includes a sub-assembly having a non-uniform thickness. In this embodiment, heater assembly  100   a  has a non-uniform thickness because the thicknesses of inner segmented heater sub-assembly  120 , intermediate heater segment  140   a  and  140   b  of intermediate segmented heater sub-assembly  140  and outer heater segment  160   a ,  160   b ,  160   c  and  160   d  of outer segmented heater sub-assembly  160  have thickness values that vary between inner gap  105  and the outer periphery of outer segmented heater sub-assembly  160 . In this way, the intermediate heater segment  140   a  and  140   b  of intermediate segmented heater sub-assembly  140  and outer heater segment  160   a ,  160   b ,  160   c  and  160   d  of outer segmented heater sub-assembly  160  each have a non-uniform thickness. 
         [0090]    The thicknesses of heater plate sub-assembly  110 , inner segmented heater sub-assembly  120 , intermediate heater segment  140   a  and  140   b  of intermediate segmented heater sub-assembly  140  and outer heater segment  160   a ,  160   b ,  160   c  and  160   d  of outer segmented heater sub-assembly  160  are chosen to provide a desired resistance. As mentioned above, the resistance of heater plate sub-assembly  110  increases and decreases as its thickness decreases and increases, respectively. 
         [0091]    The resistance of inner segmented heater sub-assembly  120  increases and decreases as its thickness decreases and increases, respectively. In this embodiment, inner segmented heater sub-assembly  120  is thicker proximate to inner gap  105  and thinner proximate to intermediate gap  106 . Inner segmented heater sub-assembly  120  is less resistive proximate to inner gap  105  because it is thicker proximate to inner gap  105 . Further, inner segmented heater sub-assembly  120  is more resistive proximate to intermediate gap  106  because it is thinner proximate to intermediate gap  106 . It is desirable to have inner segmented heater sub-assembly  120  less resistive proximate to inner gap  105  and more resistive proximate to intermediate gap  106  so that inner segmented heater sub-assembly  120  provides less heat proximate to inner gap  105  and more heat proximate to intermediate gap  106 . It is desirable to have inner segmented heater sub-assembly  120  provide less heat proximate to inner gap  105  and more heat proximate to intermediate gap  106  because inner gap  105  is closer to center  103  than intermediate gap  106 . In this way, inner segmented heater sub-assembly  120  provides a more uniform amount of heat. 
         [0092]    The resistance of intermediate segmented heater sub-assembly  140  increases and decreases as its thickness decreases and increases, respectively. The resistance of intermediate segmented heater sub-assembly  140  increases and decreases as its thickness decreases and increases, respectively. In this embodiment, intermediate segmented heater sub-assembly  140  is thicker proximate to intermediate gap  106  and thinner proximate to outer gap  107 . Intermediate segmented heater sub-assembly  140  is less resistive proximate to intermediate gap  106  because it is thicker proximate to intermediate gap  106 . Further, intermediate segmented heater sub-assembly  140  is more resistive proximate to outer gap  107  because it is thinner proximate to outer gap  107 . It is desirable to have intermediate segmented heater sub-assembly  140  less resistive proximate to intermediate gap  106  and more resistive proximate to outer gap  107  so that intermediate segmented heater sub-assembly  140  provides less heat proximate to intermediate gap  106  and more heat proximate to outer gap  107 . It is desirable to have intermediate segmented heater sub-assembly  140  provide less heat proximate to intermediate gap  106  and more heat proximate to outer gap  107  because intermediate gap  106  is closer to center  103  than outer gap  107 . In this way, intermediate segmented heater sub-assembly  140  provides a more uniform amount of heat. 
         [0093]    The resistance of outer segmented heater sub-assembly  160  increases and decreases as its thickness decreases and increases, respectively. The resistance of outer segmented heater sub-assembly  160  increases and decreases as its thickness decreases and increases, respectively. In this embodiment, outer segmented heater sub-assembly  160  is thicker proximate to outer gap  107  and thinner proximate to the outer periphery of heater assembly  100 . Outer segmented heater sub-assembly  160  is less resistive proximate to outer gap  107  because it is thicker proximate to outer gap  107 . Further, outer segmented heater sub-assembly  160  is more resistive proximate to the outer periphery of heater assembly  100  because it is thinner proximate to the outer periphery of heater assembly  100 . It is desirable to have outer segmented heater sub-assembly  160  less resistive proximate to outer gap  107  and more resistive proximate to the outer periphery of heater assembly  100  so that outer segmented heater sub-assembly  160  provides less heat proximate to outer gap  107  and more heat proximate to the outer periphery of heater assembly  100 . It is desirable to have outer segmented heater sub-assembly  160  provide less heat proximate to outer gap  107  and more heat proximate to the outer periphery of heater assembly  100  because outer gap  107  is closer to center  103  than the outer periphery of heater assembly  100 . In this way, outer segmented heater sub-assembly  160  provides a more uniform amount of heat. 
         [0094]      FIG. 1   d  is a side view of a heater assembly  100   b  which includes a segmented heater assembly with a uniform thickness and another segmented heater assembly with a non-uniform thickness. For example, in this embodiment, heater assembly  100   b  includes heater plate  110  and intermediate segmented heater sub-assembly  140 , as shown in  FIG. 1   a . In this embodiment, heater assembly  100   b  includes intermediate segmented heater sub-assembly  140 , wherein intermediate segmented heater sub-assembly  140  has a non-uniform thickness. Intermediate segmented heater sub-assembly  140  is positioned between heater plate  110  and intermediate segmented heater sub-assembly  140 . Further, heater assembly  100   b  includes outer segmented heater sub-assembly  160 , wherein outer segmented heater sub-assembly  160  has a non-uniform thickness. Outer segmented heater sub-assembly  160  is positioned around intermediate segmented heater sub-assembly  140 . 
         [0095]    It should be noted that any of the heater assemblies discussed herein can include many different combinations of uniform and non-uniform segmented heater assemblies, but only a few are shown for simplicity and ease of discussion. The particular combination of uniform and non-uniform segmented heater assemblies depends on many different factors, such as the desired heat profile of the heater assembly. As mentioned above, the uniformity of a semiconductor layer deposited on a wafer increases and decreases as the heat profile of the heater assembly becomes more and less uniform. 
         [0096]      FIG. 1   e  is a representative heat/temperature profile along cut line of  FIG. 1   a  of heater assembly  100  with the heater cross sectional embodiment of  FIG. 1   b  showing the variance temperature measured diametrically across heater  160   d ,  140   b ,  120 ,  110 ,  120 ,  140   a  and  160   b.    
         [0097]      FIG. 1   f  is a representative heat/temperature profile along cut line of  FIG. 1   a  of heater assembly  100   a  with the heater cross sectional embodiment of  FIG. 1   c  showing an improved temperature variance measured diametrically across heater  160   d ,  140   b ,  120 ,  110 ,  120 ,  140   a  and  160   b  as compared to  FIG. 1   e.    
         [0098]      FIG. 1   g  is a representative heat/temperature profile along cut line of  FIG. 1   a  of heater assembly  100   a  with the heater cross sectional embodiment optimally designed as discussed below showing an improved temperature variance measured diametrically across heater  160   d ,  140   b ,  120 ,  110 ,  120 ,  140   a  and  160   b  as compared to  FIG. 1   f.    
         [0099]      FIG. 2   a  is a top view of one embodiment of heater plate  110 ,  FIG. 2   b  is a perspective view of heater plate  110  and  FIG. 2   c  is a cut-away side view of heater plate  110  taken along a cut-line  2   c - 2   c  of  FIG. 2   a . In this embodiment, heater plate sub-assembly  110  includes opposed surfaces  115   a  and  115   b , and is bounded by an outer peripheral surface  113 . Outer peripheral surface  113  extends adjacent to inner gap  105  ( FIG. 1   a ), and faces inner segmented heater sub-assembly  120 . 
         [0100]    In this embodiment, heater plate sub-assembly  110  includes contacts  112   a  and  112   b , which are spaced apart from each other. Heater plate sub-assembly  110  flows heat through opposed surfaces  115   a  and  115   b  in response to a potential difference V 0  established between contacts  112   a  and  112   b . Heater plate sub-assembly  110  flows heat through opposed surfaces  115   a  and  115   b  in response to a current flowing between contacts  112   a  and  112   b  in response to the potential difference established between contacts  112   a  and  112   b  from the adjustable signal applied to these contacts as previously discussed. 
         [0101]      FIG. 3   a  is a top view of one embodiment of inner segmented heater sub-assembly  120 ,  FIG. 3   b  is a perspective view of inner segmented heater sub-assembly  120  and  FIG. 3   c  is a cut-away side view of inner segmented heater sub-assembly  120  taken along a cut-line  3   c - 3   c  of  FIG. 3   a . In this embodiment, inner segmented heater sub-assembly  120  includes opposed surfaces  125   a  and  125   b , and is bounded by an outer peripheral surface  123  and inner peripheral surface  124 . Opposed surfaces  125   a  and  125   b  are gapped surfaces because inner radial slot  126  extends therethrough. Radial slot  126  is dimensioned to inhibit the ability of current to flow between surfaces  128   a  and  128   b.    
         [0102]    Outer peripheral surface  123  extends adjacent to intermediate gap  106  ( FIGS. 1   a  and  1   b ), and faces intermediate segmented heater sub-assembly  140 . Inner peripheral surface  124  extends adjacent to inner gap  105  ( FIGS. 1   a  and  1   b ), and faces inner segmented heater sub-assembly  110 . In this way, inner gap  105  is bounded by outer peripheral surface  113  and inner peripheral surface  124 . Inner gap  105  is dimensioned to inhibit the ability of current to flow between heater assemblies  110  and  120 . Inner segmented heater sub-assembly  120  includes a central opening  121  sized and shaped to receive heater plate sub-assembly  110  ( FIGS. 1   a  and  1   b ). 
         [0103]    In this embodiment, inner segmented heater sub-assembly  120  includes contacts  122   a  and  122   b , which are spaced apart from each other by a radial gap  126 . Inner segmented heater sub-assembly  120  flows heat through opposed surfaces  125   a  and  125   b  in response to a potential difference established between contacts  122   a  and  122   b . Inner segmented heater sub-assembly  120  flows heat through opposed surfaces  125   a  and  125   b  in response to a current flowing between contacts  122   a  and  122   b . It should be noted that the current flows between contacts  122   a  and  122   b  in response to the potential difference established between contacts  122   a  and  122   b  by the adjustable signal applied as discussed above. 
         [0104]    Radial gap  126  is a radial gap because it extends along a radial line  104 , which extends radially outward from a center  103  of heater plate sub-assembly  110  ( FIG. 1   a ). It should be noted that, in this embodiment, center  103  of heater plate sub-assembly  110  corresponds to a center of heater assembly  100 . In this embodiment, radial gap  126  is bounded by opposed radial gap surfaces  127  and  128 . Radial gap surfaces  127  and  128  extend radially outward from center  103  of heater plate sub-assembly  110 , and between outer peripheral surface  123  and inner peripheral surface  124 . 
         [0105]      FIG. 3   d  is a side view of inner segmented heater sub-assembly  120  in a region  129  of  FIG. 3   c . As shown in  FIG. 3   d , inner segmented heater sub-assembly  120  has inner and outer thicknesses t 1  and t 2 . Inner thickness t 1  is the thickness of inner segmented heater sub-assembly  120  proximate to inner peripheral surface  124  and outer thickness t 2  is the thickness of inner segmented heater sub-assembly  120  proximate to outer peripheral surface  123 . 
         [0106]    Inner segmented heater sub-assembly  120  has a uniform thickness when thicknesses t 1  and t 2  are the same, and inner segmented heater sub-assembly  120  has thickness t 1  between outer peripheral surface  123  and inner peripheral surface  124 . Inner segmented heater sub-assembly  120  has a uniform thickness when thicknesses t 1  and t 2  are the same, and inner segmented heater sub-assembly  120  has thickness t 2  between outer peripheral surface  123  and inner peripheral surface  124 . 
         [0107]    Inner segmented heater sub-assembly  120  has a uniform thickness when thicknesses t 1  and t 2  are the same, and opposed surfaces  125   a  and  125   d  are spaced apart from each other by thickness t 1 . Inner segmented heater sub-assembly  120  has a uniform thickness when thicknesses t 1  and t 2  are the same, and opposed surfaces  125   a  and  125   d  are spaced apart from each other by thickness t 2 . In the embodiment in which inner segmented heater sub-assembly  120  has a uniform thickness, opposed surfaces  125   a  and  125   b  are parallel to each other. 
         [0108]      FIG. 3   e  is a side view of another embodiment of inner segmented heater sub-assembly  120  in region  129 , and  FIG. 3   f  is a corresponding perspective view of the embodiment of  FIG. 3   e , wherein inner segmented heater sub-assembly  120  has a non-uniform thickness. Inner segmented heater sub-assembly  120  of  FIGS. 3   e  and  3   f  correspond to inner segmented heater sub-assembly  120  of  FIG. 1   c . In  FIGS. 3   d  and  3   e , inner segmented heater sub-assembly  120  has a non-uniform thickness because thicknesses t 1  and t 2  are unequal, and the thickness of inner segmented heater sub-assembly  120  is non-uniform between inner peripheral surface  124  and outer peripheral surface  123 . In this particular embodiment, thickness t 1  is greater than thickness t 2 . It should be noted, however, that thickness t 2  is greater than thickness t 1  in other embodiments. In the embodiment in which inner segmented heater sub-assembly  120  has a non-uniform thickness, opposed surfaces  125   a  and  125   b  are not parallel to each other. 
         [0109]    Surfaces  125   a  and  125   b  can have many different shapes. For example, in  FIG. 3   d , surfaces  125   a  and  125   b  are flat surfaces which extend parallel to each other because t 1  and t 2  are equal. In  FIGS. 3   e  and  3   f , surfaces  125   a  and  125   b  are flat surfaces which do not extend parallel to each other because t 1  and t 2  are not equal. In some embodiments, surfaces  125   a  and  125   c  are flat surfaces and, in other embodiments, surfaces  125   a  and  125   c  are curved surfaces or combinations thereof. In some embodiments, surfaces  125   a  and  125   c  are curved so they are concave and, in other embodiments, surfaces  125   a  and  125   c  are curved so they are convex. 
         [0110]      FIG. 4   a  is a top view of one embodiment of intermediate segmented heater sub-assembly  140 ,  FIG. 4   b  is a perspective view of intermediate segmented heater sub-assembly  140  and  FIG. 4   c  is a cut-away side view of intermediate segmented heater sub-assembly  140  taken along a cut-line  4   c - 4   c  of  FIG. 4   a . In this embodiment, intermediate segmented heater sub-assembly  140  includes intermediate heater segments  140   a  and  140   b . Intermediate heater segments  140   a  and  140   b  include opposed surfaces  145   a  and  145   b , and are bounded by an outer peripheral surface  143  and inner peripheral surface  144 . Outer peripheral surface  143  extends adjacent to outer gap  107  ( FIGS. 1   a  and  1   b ), and faces outer segmented heater sub-assembly  160 . Inner peripheral surface  144  extends adjacent to intermediate gap  106  ( FIGS. 1   a  and  1   b ), and faces inner segmented heater sub-assembly  120 . In this way, intermediate gap  106  is bounded by outer peripheral surface  123  and inner peripheral surface  144 . Intermediate gap  106  is dimensioned to inhibit the ability of current to flow between heater assemblies  120  and  140 . Intermediate segmented heater sub-assembly  140  includes a central opening  141  sized and shaped to receive inner segmented heater sub-assembly  120  ( FIGS. 1   a  and  1   b ). 
         [0111]    In this embodiment, intermediate segmented heater sub-assembly  140  includes contacts  142   a  and  142   b , which are carried by intermediate heater segment  140   b . In this embodiment, intermediate segmented heater sub-assembly  140  includes contacts  142   c  and  142   d , which are carried by intermediate heater segment  140   a . In this embodiment, contacts  142   b  and  142   c  are spaced apart from each other by a radial gap  146   a . In this embodiment, contacts  142   a  and  142   d  are spaced apart from each other by a radial gap  146   b . Intermediate heater segments  140   a  and  140   b  are spaced apart from each other by radial gaps  146   a  and  146   b.    
         [0112]    Radial gap  146   a  is a radial gap because it extends along radial line  104 , which extends radially outward from center  103  of heater plate sub-assembly  110  ( FIG. 1   a ). In this embodiment, radial gap  146   a  is bounded by opposed radial gap surfaces  147   a  and  148   a . Radial gap surfaces  147   a  and  148   a  extend radially outward from center  103  of heater plate sub-assembly  110 , and between outer peripheral surface  143  and inner peripheral surface  144 . 
         [0113]    Radial gap  146   b  is a radial gap because it extends along a radial line, which extends radially outward from center  103  of heater plate sub-assembly  110 . In this embodiment, radial gap  146   b  is bounded by opposed radial gap surfaces  147   b  and  148   b . Radial gap surfaces  147   b  and  148   b  extend radially outward from center  103  of heater plate sub-assembly  110 , and between outer peripheral surface  143  and inner peripheral surface  144 . Radial slot  146   a  is dimensioned to inhibit the ability of current to flow between surfaces  148   a  and  148   d . Radial slot  145   b  is dimensioned to inhibit the ability of current to flow between surfaces  148   b  and  148   c.    
         [0114]    Intermediate segmented heater sub-assembly  140  flows heat through opposed surfaces  145   a  and  145   b  in response to a potential difference V 2  and V 3  established between contacts  142   a  and  142   b  and between contracts  142   c  and  142   d  respectively. It should be noted that the current flows between contacts  142   a  and  142   b  in response to the potential difference established between contacts  142   a  and  142   b  and between contacts  142   c  and  142   d  in response to the potential difference established between contacts  142   c  and  142   d  by the adjustable signals applied to the contacts as discussed above. 
         [0115]      FIG. 4   d  is a side view of intermediate segmented heater sub-assembly  140  in a region  149  of  FIG. 4   c . As shown in  FIG. 4   d , intermediate segmented heater sub-assembly  140  has inner and outer thicknesses t 3  and t 4 . Inner thickness t 3  is the thickness of intermediate segmented heater sub-assembly  140  proximate to inner peripheral surface  144  and outer thickness t 4  is the thickness of intermediate segmented heater sub-assembly  140  proximate to outer peripheral surface  143 . 
         [0116]    Intermediate segmented heater sub-assembly  140  has a uniform thickness when thicknesses t 3  and t 4  are the same, and intermediate segmented heater sub-assembly  140  has thickness t 3  between outer peripheral surface  143  and inner peripheral surface  144 . Intermediate segmented heater sub-assembly  140  has a uniform thickness when thicknesses t 3  and t 4  are the same, and intermediate segmented heater sub-assembly  140  has thickness t 4  between outer peripheral surface  143  and inner peripheral surface  144 . 
         [0117]    Intermediate segmented heater sub-assembly  140  has a uniform thickness when thicknesses t 3  and t 4  are the same and opposed surfaces  145   a  and  145   d  are spaced apart from each other by thickness t 3 . Intermediate segmented heater sub-assembly  140  has a uniform thickness when thicknesses t 3  and t 4  are the same, and opposed surfaces  145   a  and  145   d  are spaced apart from each other by thickness t 4 . In the embodiment in which intermediate segmented heater sub-assembly  140  has a uniform thickness, opposed surfaces  145   a  and  145   b  are parallel to each other. It should be noted that intermediate heater segments  140   a  and  140   b  have uniform thicknesses when intermediate segmented heater sub-assembly  140  has a uniform thickness. 
         [0118]      FIG. 4   e  is a side view of another embodiment of intermediate segmented heater sub-assembly  140  in region  149 , and  FIG. 4   f  is a corresponding perspective view of the embodiment of  FIG. 4   e , wherein intermediate segmented heater sub-assembly  140  has a non-uniform thickness. Intermediate segmented heater sub-assembly  140  of  FIGS. 4   e  and  4   f  correspond to intermediate segmented heater sub-assembly  140  of  FIG. 1   c . In  FIGS. 4   d  and  4   e , intermediate segmented heater sub-assembly  140  has a non-uniform thickness because thicknesses t 3  and t 4  are unequal, and the thickness of intermediate segmented heater sub-assembly  140  is non-uniform between inner peripheral surface  144  and outer peripheral surface  143 . In this particular embodiment, thickness t 3  is greater than thickness t 4 . It should be noted, however, that thickness t 4  is greater than thickness t 3  in other embodiments. In the embodiment in which intermediate segmented heater sub-assembly  140  has a non-uniform thickness, opposed surfaces  145   a  and  145   b  are not parallel to each other. 
         [0119]    Surfaces  145   a  and  145   b  can have many different shapes. For example, in  FIG. 4   d , surfaces  145   a  and  145   b  are flat surfaces which extend parallel to each other because t 3  and t 4  are equal. In  FIGS. 4   e  and  4   f , surfaces  145   a  and  145   b  are flat surfaces which do not extend parallel to each other because t 3  and t 4  are not equal. In some embodiments, surfaces  145   a  and  145   c  are flat surfaces and, in other embodiments, surfaces  145   a  and  145   c  are curved surfaces or combinations thereof. In some embodiments, surfaces  145   a  and  145   c  are curved so they are concave and, in other embodiments, surfaces  145   a  and  145   c  are curved so they are convex. 
         [0120]      FIG. 5   a  is a top view of one embodiment of outer segmented heater sub-assembly  160 ,  FIG. 5   b  is a perspective view of outer segmented heater sub-assembly  160  and  FIG. 5   c  is a cut-away side view of outer segmented heater sub-assembly  160  taken along a cut-line  5   c - 5   c  of  FIG. 5   a . In this embodiment, outer segmented heater sub-assembly  160  includes outer heater segments  160   a ,  160   b ,  160   c  and  160   d . Outer heater segments  160   a ,  160   b ,  160   c  and  160   d  include opposed surfaces  165   a  and  165   b , and are bounded by an outer peripheral surface  163  and inner peripheral surface  164 . Outer peripheral surface  163  extends adjacent to the outer periphery of heater assembly  100  ( FIGS. 1   a  and  1   b ), and faces the outer periphery of heater assembly  100 . Inner peripheral surface  164  extends adjacent to outer gap  107  ( FIGS. 1   a  and  1   b ), and faces intermediate segmented heater sub-assembly  140 . In this way, outer gap  107  is bounded by outer peripheral surface  143  and inner peripheral surface  163 . Outer gap  107  is dimensioned to inhibit the ability of current to flow between heater assemblies  140  and  160 . Outer segmented heater sub-assembly  160  includes a central opening  161  sized and shaped to receive intermediate segmented heater sub-assembly  140  ( FIGS. 1   a  and  1   b ). 
         [0121]    In this embodiment, outer segmented heater assembly includes contacts  162   a  and  162   b , which are carried by intermediate heater segment  160   a . In this embodiment, outer segmented heater sub-assembly  160  includes contacts  162   c  and  162   d , which are carried by intermediate heater segment  160   d . In this embodiment, outer segmented heater sub-assembly  160  includes contacts  162   e  and  162   f , which are carried by intermediate heater segment  160   c . In this embodiment, outer segmented heater sub-assembly  160  includes contacts  162   g  and  162   h , which are carried by intermediate heater segment  160   b.    
         [0122]    In this embodiment, contacts  162   a  and  162   h  are spaced apart from each other by a radial gap  166   a . Further, outer heater segments  160   a  and  160   b  are spaced apart from each other by radial gap  166   a . In this embodiment, contacts  162   b  and  162   c  are spaced apart from each other by a radial gap  166   c . Further, outer heater segments  160   a  and  160   d  are spaced apart from each other by radial gap  166   c . In this embodiment, contacts  162   d  and  162   e  are spaced apart from each other by a radial gap  166   b . Further, outer heater segments  160   c  and  160   d  are spaced apart from each other by radial gap  166   b . In this embodiment, contacts  162   f  and  162   g  are spaced apart from each other by a radial gap  166   d . Further, outer heater segments  160   b  and  160   c  are spaced apart from each other by radial gap  166   d.    
         [0123]    Radial gap  166   a  is a radial gap because it extends along a radial line, which extends radially outward from center  103  of heater plate sub-assembly  110 . In this embodiment, radial gap  166   a  is bounded by opposed radial gap surfaces  168   a  and  168   h . Radial gap surfaces  168   a  and  168   h  extend radially outward from center  103  of heater plate sub-assembly  110 , and between outer peripheral surface  163  and inner peripheral surface  164 . 
         [0124]    Radial gap  166   b  is a radial gap because it extends along a radial line, which extends radially outward from center  103  of heater plate sub-assembly  110 . In this embodiment, radial gap  166   b  is bounded by opposed radial gap surfaces  168   d  and  168   e . Radial gap surfaces  168   d  and  168   e  extend radially outward from center  103  of heater plate sub-assembly  110 , and between outer peripheral surface  163  and inner peripheral surface  164 . 
         [0125]    Radial gap  166   c  is a radial gap because it extends along a radial line, which extends radially outward from center  103  of heater plate sub-assembly  110 . In this embodiment, radial gap  166   c  is bounded by opposed radial gap surfaces  168   b  and  168   c . Radial gap surfaces  168   b  and  168   c  extend radially outward from center  103  of heater plate sub-assembly  110 , and between outer peripheral surface  163  and inner peripheral surface  164 . 
         [0126]    Radial gap  166   d  is a radial gap because it extends along a radial line, which extends radially outward from center  103  of heater plate sub-assembly  110 . In this embodiment, radial gap  166   d  is bounded by opposed radial gap surfaces  168   f  and  168   g . Radial gap surfaces  168   f  and  168   g  extend radially outward from center  103  of heater plate sub-assembly  110 , and between outer peripheral surface  163  and inner peripheral surface  164 . 
         [0127]    Radial slot  166   a  is dimensioned to inhibit the ability of current to flow between surfaces  168   a  and  168   h . Radial slot  166   b  is dimensioned to inhibit the ability of current to flow between surfaces  168   d  and  168   e . Radial slot  166   c  is dimensioned to inhibit the ability of current to flow between surfaces  168   b  and  168   c . Radial slot  166   d  is dimensioned to inhibit the ability of current to flow between surfaces  168   f  and  168   g.    
         [0128]    Outer segmented heater sub-assembly  160  flows heat through opposed surfaces  165   a  and  165   b  in response to a potential difference V 4 , V 5 , V 6 , and V 7  established between contacts  162   a  and  162   b , between contracts  162   c  and  162   d , between contacts  162   e  and  162   f , between contracts  162   g  and  162   h  respectively. It should be noted that the current flows between contacts  162   a  and  162   b  in response to the potential difference established between contacts  162   a  and  162   b  and between contacts  162   c  and  162   d  in response to the potential difference established between contacts  162   c  and  162   d , and between contacts  162   e  and  162   f  in response to the potential established between contacts  162   e  and  162   f  and between contacts  162   g  and  162   h  in response to the potential established between contacts  162   g  and  162   h  by the adjustable signals applied to the contacts as discussed above. 
         [0129]      FIG. 5   d  is a side view of outer segmented heater sub-assembly  160  in a region  169  of  FIG. 5   c . As shown in  FIG. 5   d , outer segmented heater sub-assembly  160  has inner and outer thicknesses t 5  and t 6 . Inner thickness t 5  is the thickness of outer segmented heater sub-assembly  160  proximate to inner peripheral surface  164  and outer thickness t 6  is the thickness of outer segmented heater sub-assembly  160  proximate to outer peripheral surface  163 . 
         [0130]    Outer segmented heater sub-assembly  160  has a uniform thickness when thicknesses t 5  and t 6  are the same, and outer segmented heater sub-assembly  160  has thickness t 5  between outer peripheral surface  163  and inner peripheral surface  164 . Outer segmented heater sub-assembly  160  has a uniform thickness when thicknesses t 5  and t 6  are the same, and outer segmented heater sub-assembly  160  has thickness t 6  between outer peripheral surface  163  and inner peripheral surface  164 . 
         [0131]    Outer segmented heater sub-assembly  160  has a uniform thickness when thicknesses t 5  and t 6  are the same, and opposed surfaces  165   a  and  165   b  are spaced apart from each other by thickness t 5 . Outer segmented heater sub-assembly  160  has a uniform thickness when thicknesses t 5  and t 6  are the same, and opposed surfaces  165   a  and  165   b  are spaced apart from each other by thickness t 6 . In the embodiment in which outer segmented heater sub-assembly  160  has a uniform thickness, opposed surfaces  165   a  and  165   b  are parallel to each other. It should be noted that outer heater segments  160   a ,  160   b ,  160   c  and  160   d  have uniform thicknesses when outer segmented heater sub-assembly  160  has a uniform thickness. 
         [0132]      FIG. 5   e  is a side view of another embodiment of outer segmented heater sub-assembly  160  in region  169 , and  FIG. 5   f  is a corresponding perspective view of the embodiment of  FIG. 5   e , wherein outer segmented heater sub-assembly  160  has a non-uniform thickness. Outer segmented heater sub-assembly  160  of  FIGS. 5   e  and  5   f  correspond to outer segmented heater sub-assembly  160  of  FIG. 1   c . In  FIGS. 5   d  and  5   e , outer segmented heater sub-assembly  160  has a non-uniform thickness because thicknesses t 5  and t 6  are unequal, and the thickness of outer segmented heater sub-assembly  160  is non-uniform between inner peripheral surface  164  and outer peripheral surface  163 . In this particular embodiment, thickness t 5  is greater than thickness t 6 . It should be noted, however, that thickness t 6  is greater than thickness t 5  in other embodiments. In the embodiment in which outer segmented heater sub-assembly  160  has a non-uniform thickness, opposed surfaces  165   a  and  165   b  are not parallel to each other. 
         [0133]    Surfaces  165   a  and  165   b  can have many different shapes. For example, in  FIG. 5   d , surfaces  165   a  and  165   b  are flat surfaces which extend parallel to each other because t 5  and t 6  are equal. In  FIGS. 5   e  and  5   f , surfaces  165   a  and  165   b  do not extend parallel to each other because t 5  and t 6  are not equal. In some embodiments, surfaces  165   a  and  165   c  are flat surfaces and, in other embodiments, surfaces  165   a  and  165   c  are curved surfaces. In some embodiments, surfaces  165   a  and  165   c  are curved so they are concave and, in other embodiments, surfaces  165   a  and  165   c  are curved so they are convex. 
         [0134]      FIG. 6  is a top view of one embodiment of a heater assembly  100   a . As will be discussed in more detail below, heater assembly  100   a  can be used to heat a wafer. It is desirable to heat the wafer(s) in many different situations, such as when depositing a material thereon. Heater assembly  100   a  can be used in a deposition system to heat the wafer. The wafer is heated to facilitate the ability to deposit material thereon. The material can be of many different types, such as semiconductor material. 
         [0135]    In this embodiment, heater assembly  100   a  includes a coiled heater  110   a , and an inner slotted heater ring  180  spaced from coiled heater sub-assembly  110   a  by inner gap  105 . Heater assembly  100   a  includes intermediate slotted heater sub-assemblies  181   a  and  181   b  spaced from slotted inner heater sub-assembly  180  by intermediate gap  106 . Heater assembly  100   a  includes outer slotted heater sub-assemblies  182   a ,  182   b ,  183   c  and  184   d  spaced from slotted intermediate heater sub-assemblies  181   a  and  181   b  by outer gap  107 . It should be noted that inner gap  105 , intermediate gap  106  and outer gap  107  are annular gaps because they extend annularly around coiled heater sub-assembly  110   a , inner slotted ring heater sub-assemblies  180 , intermediate slotted heaters sub-assemblies  181   a  and  181   b  and outer slotted heater sub-assemblies  182   a ,  182   b ,  183   c  and  184   d  respectively. 
         [0136]    Heater sub-assemblies  110   a ,  180 ,  181   a  and  181   b  and  182   a ,  182   b ,  183   c  and  184   d  can be constructed in many different ways, several of which will be discussed in more detail below. 
         [0137]    It should also be noted that heater assembly  100   a , as shown in  FIG. 6 , has a uniform thickness. Heater assembly  100  of  FIG. 6  has a uniform thickness because the thicknesses of heaters  110   a ,  180 ,  181   a  and  181   b  and  182   a ,  182   b ,  183   c  and  184   d  have the same thickness values between inner gap  105  and the outer periphery of heaters  182   a ,  182   b ,  183   c  and  184   d.    
         [0138]      FIG. 7  is a top view of one embodiment of coiled heater  110   a . In this embodiment, coiled heater  110   a  includes an inner ring  191  having a central opening  192 . In this embodiment, coiled heater  110   a  includes coils  193  and  194  which are connected to opposed sides of inner ring  191 . Inner coils  193  and  194  are spaced apart from each other by gaps  195   a  and  195   b , wherein gaps  195   a  and  195   b  extend between inner coils  193  and  194  and coil ring  191 . 
         [0139]      FIGS. 8   a  and  8   b  are perspective and top views, respectively, of heater coil  170  of one embodiment of a heater. It should be noted that heater coil  170  can be included in a heater assembly, such as the heater assemblies discussed herein. For example, heater coil  170  can be included in heater assemblies  100  and  100   a . Heater coil  170  can be included in a heater assembly in many different ways. In some embodiments, heater coil  170  is included in an inner segmented heater  180  in  FIG. 6 . In some embodiments, heater coil  170  is included in intermediate segmented heater  181   a  and  181   b . In some embodiments, heater coil  170  is included in outer segmented heater  182   a ,  182   b ,  182   c  and  182   d . Several of these embodiments will be discussed in more detail below. 
         [0140]    In  FIGS. 8   a  and  8   b , heater coil  170  includes a plurality of inner and outer radial slots, wherein the inner radial slot faces an inner peripheral surface and the outer radial slot faces an outer peripheral surface. The inner and outer radial slots are radial gaps because they are lengthened along a radial line, such as radial line  104  of  FIGS. 1   a  and  6 , which extends radially outward from a center, such as center  103 . Further, the inner and outer radial slots are radial gaps because they are shortened transversely to the radial line. 
         [0141]    In this embodiment, heater coil  170  includes an inner radial slot  176   a , which faces inner peripheral surface  174 . Inner radial slot  176   a  is a radial gap because it extends along a radial line, such as radial line  104  of  FIGS. 1   a  and  6 . Inner radial slot  176   a  is bounded by a transverse coil segment  172   b  and opposed radial segment  171   b  and  171   c . Transverse segment  172   b  is a transverse segment because it extends transversely to the radial line, such as radial line  104  of  FIGS. 1   a  and  6 . Radial coil segments  171   b  and  171   c  are radial segments because they extend along the radial line, such as radial line  104  of  FIGS. 1   a  and  6 . 
         [0142]    It should be noted that a radial coil segment is lengthened in the radial direction and shortened in the transverse direction. The radial coil segment is lengthened in the radial direction and shorted in the transverse direction because the radial coil segment is longer in the radial direction and shorter in the transverse direction. 
         [0143]    Further, a transverse coil segment is shortened in the radial direction and lengthened in the transverse direction. The transverse coil segment is shortened in the radial direction and lengthened in the transverse direction because the transverse coil segment is shorter in the radial direction and longer in the transverse direction. 
         [0144]    In this embodiment, heater coil  170  includes outer radial slots  177   a  and  177   b , which face outer peripheral surface  173 . Outer radial slot  177   a  is a radial gap because it extends along a radial line, such as radial line  104  of  FIGS. 1   a  and  6 . Outer radial slot  177   a  is bounded by a transverse coil segment  172   a  and opposed radial coil segments  171   a  and  171   b . Transverse coil segment  172   a  is a transverse coil segment because it extends along the radial line, such as radial line  104  of  FIGS. 1   a  and  6 . Radial coil segments  171   a  and  171   b  are radial coil segments because they extend along the radial line, such as radial line  104  of  FIGS. 1   a  and  6 . 
         [0145]    Outer radial slot  177   b  is a radial gap because it extends along a radial line, such as radial line  104  of  FIGS. 1   a  and  6 . Outer radial slot  177   b  is bounded by a transverse coil segment  172   c  and opposed radial coil segments  171   c  and  171   d . Transverse coil segment  172   c  is a transverse coil segment because it extends along the radial line, such as radial line  104  of  FIGS. 1   a  and  6 . Radial coil segments  171   c  and  171   d  are radial coil segments because they extend along the radial line, such as radial line  104  of  FIGS. 1   a  and  6 . 
         [0146]      FIG. 8   b  shows that radial coil segments  171   a  and  171   b  are spaced apart from each other by a distance t 7  proximate to inner peripheral surface  174 . Further, radial coil segments  171   a  and  171   b  are spaced apart from each other by a distance t 8  proximate to outer peripheral surface  173 . In one embodiment, distance t 7  is less than distance t 8 . In another embodiment distance t 7  is the same as distance t 8 . In another embodiment distance t 7  is greater than as distance t 8 . 
         [0147]    In this embodiment, radial coil segments  171   b  and  171   c  are spaced apart from each other by a distance t 9  proximate to outer peripheral surface  173 , as shown in  FIG. 8   b . Further, radial coil segments  171   b  and  171   c  are spaced apart from each other by a distance t 10  proximate to inner peripheral surface  174 . In this embodiment, distance t 10  is less than distance t 9 . In another embodiment distance t 10  is the same as distance t 9 . In another embodiment distance t 10  is greater than as distance t 9 . 
         [0148]    In this embodiment, radial coil segments  171   c  and  171   d  are spaced apart from each other by distance t 7  proximate to inner peripheral surface  174 , as shown in  FIG. 8   b . Further, radial coil segments  171   c  and  171   d  are spaced apart from each other by a distance t 8  proximate to outer peripheral surface  173 . In this embodiment, distance t 7  is less than distance t 8 . In another embodiment distance t 7  is the same as distance t 8 . In another embodiment distance t 7  is greater than as distance t 8 . 
         [0149]    As mentioned above, a heater assembly has a uniform thickness in some embodiments, and a non-uniform thickness in other embodiments. Examples of heater assemblies having uniform and non-uniform thicknesses are shown in  FIGS. 1   b  and  1   c . In  FIGS. 8   a  and  8   b , heater coil  170  has a uniform thickness because the thicknesses of heater coil  170  proximate to and between outer peripheral surface  173  and inner peripheral surface  174  are the same. For example, in this embodiment, heater coil  170  has a thickness t 11  proximate to inner peripheral surface  174  and a thickness t 12  proximate to outer peripheral surface  173 , wherein thicknesses t 11  and t 12  are the same. In this embodiment, the thickness of heater coil  170  between outer peripheral surface  173  and inner peripheral surface  174  is thickness t 11 . Further, the thickness of heater coil  170  between outer peripheral surface  173  and inner peripheral surface  174  is thickness t 12 . In this way, heater coil  170  has a uniform thickness. An example of a heater coil with a non-uniform thickness will be discussed in more detail presently. 
         [0150]      FIGS. 9   a  and  9   b  are perspective and top views, respectively, of another embodiment of a heater coil, denoted as heater coil  170   a . It should be noted that heater coil  170   a  can be included in a heater assembly, such as the heater assemblies discussed herein. For example, heater coil  170   a  can be included in an inner segmented heater  181  in  FIG. 6 . In some embodiments, heater coil  170  is included in intermediate segmented heater  181   a  and  181   b . In some embodiments, heater coil  170  is included in outer segmented heater  182   a ,  182   b ,  182   c  and  182   d . Several of these embodiments will be discussed in more detail below. 
         [0151]    In  FIGS. 9   a  and  9   b , heater coil  170   a  includes a plurality of inner and outer radial slots, wherein the inner radial slot faces an inner peripheral surface and the outer radial slot faces an outer peripheral surface. As mentioned above, the inner and outer radial slots are radial gaps because they are lengthened along a radial line, such as radial line  104  of  FIGS. 1   a  and  6 , which extends radially outward from a center, such as center  103 , of the heater assembly. Further, the inner and outer radial slots are radial gaps because they are shortened transversely to the radial line. 
         [0152]    In this embodiment, heater coil  170   a  includes inner radial slot  176   a , which faces inner peripheral surface  174 . As mentioned above, inner radial slot  176   a  is a radial gap because it extends along a radial line, such as radial line  104  of  FIGS. 1   a  and  6 . Inner radial slot  176   a  is bounded by a transverse coil segment  172   b  and opposed radial coil segments  171   b  and  171   c . Transverse coil segment  172   b  is a transverse coil segment because it extends transversely to the radial line, such as radial line  104  of  FIGS. 1   a  and  6 . Radial coil segments  171   b  and  171   c  are radial coil segments because they extend along the radial line, such as radial line  104  of  FIGS. 1   a  and  6 . 
         [0153]    As mentioned above, a radial coil segment is lengthened in the radial direction and shortened in the transverse direction. The radial coil segment is lengthened in the radial direction and shorted in the transverse direction because the radial coil segment is longer in the radial direction and shorter in the transverse direction. 
         [0154]    Further, a transverse coil segment is shortened in the radial direction and lengthened in the transverse direction. The transverse coil segment is shortened in the radial direction and lengthened in the transverse direction because the transverse coil segment is shorter in the radial direction and longer in the transverse direction. 
         [0155]    In this embodiment, heater coil  170   a  includes outer radial slots  177   a  and  177   b , which face outer peripheral surface  173 . As mentioned above, outer radial slot  177   a  is a radial gap because it extends along a radial line, such as radial line  104  of  FIGS. 1   a  and  6 . Outer radial slot  177   a  is bounded by a transverse coil segment  172   a  and opposed radial coil segments  171   a  and  171   b . Transverse coil segment  172   a  is a transverse coil segment because it extends along the radial line, such as radial line  104  of  FIGS. 1   a  and  6 . Radial coil segments  171   a  and  171   b  are radial coil segments because they extend along the radial line, such as radial line  104  of  FIGS. 1   a  and  6 . 
         [0156]    As mentioned above, outer radial slot  177   b  is a radial gap because it extends along a radial line, such as radial line  104  of  FIGS. 1   a  and  6 . Outer radial slot  177   b  is bounded by a transverse coil segment  172   c  and opposed radial coil segments  171   c  and  171   d . Transverse coil segment  172   c  is a transverse coil segment because it extends along the radial line, such as radial line  104  of  FIGS. 1   a  and  6 . Radial coil segments  171   c  and  171   d  are radial coil segments because they extend along the radial line, such as radial line  104  of  FIGS. 1   a  and  6 . 
         [0157]    As mentioned above, radial coil segments  171   a  and  171   b  are spaced apart from each other by a distance t 7  proximate to inner peripheral surface  174 , as shown in  FIG. 9   b . Further, radial coil segments  171   a  and  171   b  are spaced apart from each other by a distance t 8  proximate to outer peripheral surface  173 . In this embodiment, distance t 7  is less than distance t 8 . In another embodiment distance t 7  is the same as distance t 8 . In another embodiment distance t 7  is greater than as distance t 8 . 
         [0158]    As mentioned above, radial coil segments  171   b  and  171   c  are spaced apart from each other by a distance t 9  proximate to outer peripheral surface  173 , as shown in  FIG. 9   b . Further, radial coil segments  171   b  and  171   c  are spaced apart from each other by a distance t 10  proximate to inner peripheral surface  174 . In this embodiment, distance t 10  is less than distance t 9 . In another embodiment distance t 10  is the same as distance t 9 . In another embodiment distance t 10  is greater than as distance t 9 . 
         [0159]    As mentioned above, radial coil segments  171   c  and  171   d  are spaced apart from each other by distance t 7  proximate to inner peripheral surface  174 , as shown in  FIG. 9   b . Further, radial coil segments  171   c  and  171   d  are spaced apart from each other by a distance t 8  proximate to outer peripheral surface  173 . In this embodiment, distance t 7  is less than distance t 8 . In another embodiment distance t 7  is the same as distance t 8 . In another embodiment distance t 7  is greater than distance t 8 . 
         [0160]    As mentioned above, a heater assembly has a uniform thickness in some embodiments, and a non-uniform thickness in other embodiments. Examples of heater assemblies having uniform and non-uniform thicknesses are shown in  FIGS. 1   b  and  1   c . In  FIGS. 8   a  and  8   b , heater coil  170  has a uniform thickness. In  FIGS. 9   a  and  9   b , however, heater coil  170   a  has a non-uniform thickness. 
         [0161]    Heater coil  170   a  has a non-uniform thickness because the thicknesses of heater coil  170  proximate to and between outer peripheral surface  173  and inner peripheral surface  174  are not the same. For example, in this embodiment, heater coil  170  has a thickness t 13  proximate to inner peripheral surface  174  and a thickness t 14  proximate to outer peripheral surface  173 , wherein thicknesses t 13  and t 14  are not the same. In this embodiment, the thickness of heater coil  170  between outer peripheral surface  173  and inner peripheral surface  174  is not thickness t 13 . Further, the thickness of heater coil  170  between outer peripheral surface  173  and inner peripheral surface  174  is not thickness t 13 . In this way, heater coil  170  has a non-uniform thickness. 
         [0162]      FIGS. 10   a  and  10   b  are top and side views, respectively, of one embodiment of a coiled inner segmented heater assembly  181 . Coiled inner segmented heater assembly  181  is a coiled heater assembly because it includes a heater coil. In this embodiment, coiled inner segmented heater assembly  181  includes heater coil  170  of  FIGS. 8   a  and  8   b , as indicated in a region  179  of  FIG. 10   a . However, in some embodiments, coiled inner segmented heater assembly  181  includes heater coil  170   a  of  FIGS. 9   a  and  9   b . In this way, coiled inner segmented heater assembly  181  is a coiled heater assembly. 
         [0163]    In this embodiment, coiled inner segmented heater assembly  181  includes opposed gapped surfaces  175   a  and  175   b , and is bounded by outer peripheral gapped surface  173  and inner peripheral gapped surface  174 . Outer peripheral gapped surface  173  extends adjacent to intermediate gap  106  ( FIG. 6 ), and inner peripheral gapped surface  174  extends adjacent to inner gap  105  ( FIG. 6 ). In this way, inner gap  105  is bounded by outer peripheral surface  113  and inner peripheral gapped surface  174 . Inner gap  105  is dimensioned to inhibit the ability of current to flow between heater assemblies  180  and  181 . Inner segmented heater assembly  181  includes central opening  121 , which is sized and shaped to receive coiled heater plate  180  ( FIGS. 6 and 7 ). 
         [0164]    Opposed gapped surfaces  175   a  and  175   b  are gapped surfaces because inner radial slot  176  extends therethrough. Opposed gapped surfaces  175   a  and  175   b  are gapped surfaces because outer radial slot  177  extends therethrough. Outer peripheral gapped surface  173  and inner peripheral gapped surface  174  are gapped surfaces because inner radial slot  176  extends therethrough. Outer peripheral gapped surface  173  and inner peripheral gapped surface  174  are gapped surfaces because outer radial slot  177  extends therethrough. Examples of surfaces that are not gapped surfaces are discussed in more detail above. 
         [0165]    In this embodiment, coiled inner segmented heater assembly  181  includes contacts  172   a  and  172   b , which are spaced apart from each other by a radial gap  176 . Coiled inner segmented heater assembly  181  flows heat through opposed surfaces  145   a  and  145   b  in response to a potential difference V 1  established between contacts  172   a  and  172   b . Coiled inner segmented heater assembly  181  flows heat through opposed surfaces  175   a  and  175   b  in response to a current flowing between contacts  172   a  and  172   b . It should be noted that the current flows between contacts  172   a  and  172   b  in response to the potential difference established between contacts  172   a  and  172   b.    
         [0166]    Radial gap  126  is a radial gap because it extends along a radial line  104 , which extends radially outward from a center  103  of heater plate sub-assembly  110  ( FIG. 1   a ). It should be noted that, in this embodiment, center  103  of heater plate sub-assembly  110  corresponds to a center of heater assembly  100 . In this embodiment, radial gap  126  is bounded by opposed radial gap surfaces  128   a  and  128   b . Radial gap surfaces  128   a  and  128   b  extend radially outward from center  103  of heater plate sub-assembly  110 , and between outer peripheral gapped surface  173  and inner peripheral gapped surface  174 . 
         [0167]      FIGS. 11   a  and  11   b  are top and side views, respectively, of one embodiment of a coiled intermediate segmented heater assembly  182 . Coiled intermediate segmented heater assembly  182  is a coiled heater assembly because it includes heater coils. In this embodiment, coiled intermediate segmented heater assembly  182  includes heater coil  170  of  FIGS. 8   a  and  8   b , as indicated in a region  179  of  FIG. 11   a . However, in some embodiments, coiled intermediate segmented heater assembly  182  includes heater coil  170   a  of  FIGS. 9   a  and  9   b . In this way, coiled intermediate segmented heater assembly  182  is a coiled heater assembly. 
         [0168]    In this embodiment, coiled intermediate segmented heater assembly  182  includes opposed gapped surfaces  175   a  and  175   b , and is bounded by outer peripheral gapped surface  173  and inner peripheral gapped surface  174 . Outer peripheral gapped surface  173  extends adjacent to intermediate gap  106  ( FIG. 6 ), and inner peripheral gapped surface  174  extends adjacent to inner gap  105  ( FIG. 6 ). In this way, inner gap  105  is bounded by outer peripheral surface  113  and inner peripheral gapped surface  174 . Inner gap  105  is dimensioned to inhibit the ability of current to flow between heater assemblies  181  and  182 . Intermediate segmented heater assembly  182  includes central opening  121 , which is sized and shaped to receive coiled heater plate  180  ( FIG. 6 ). 
         [0169]    In  FIGS. 11   a  and  11   b  opposed gapped surfaces  142   a  and  142   b  and opposed gapped surfaces  142   c  and  142   d  are gapped surfaces because inner radial slot  146   a  and  146   b  extends therethrough respectively. 
         [0170]    In this embodiment, coiled inner segmented heater assembly  182  includes contacts  142   a  and  142   c  and contacts  142   b  and  142   d , which are spaced apart from each other by a radial gap  146   a  and  146   b . Coiled inner segmented heater assembly  182  flows heat through opposed surfaces  175   a  and  175   b  in response to a potential difference established between contacts  142   a  and  142   c  and a potential difference established between contacts  142   b  and  142   d . Coiled inner segmented heater assembly  182  flows heat through opposed surfaces  175   a  and  175   b  in response to a current flowing between contacts  142   a  and  142   c  and between contacts  142   b  and  142   d.    
         [0171]    Radial gap  146   a  and  146   b  is a radial gap because it extends along a radial line  104 , which extends radially outward from a center  103  of heater plate sub-assembly  110  ( FIG. 1   a ). It should be noted that, in this embodiment, center  103  of heater plate sub-assembly  110  corresponds to a center of heater assembly  100 . In this embodiment, radial gap  146   a  is bounded by opposed radial gap surfaces  148   a  and  148   d  and radial gap  146   b  is bounded by opposed radial gap surfaces  188   b  and  188   c.    
         [0172]    Radial gap surfaces  148   a  and  148   d  and radial gap surfaces  188   b  and  188   c  extend radially outward from center  103  of heater plate sub-assembly  110 , and between outer peripheral gapped surface  173  and inner peripheral gapped surface  174 . 
         [0173]      FIGS. 12   a  and  12   b  are top and side views, respectively, of one embodiment of a coiled outer segmented heater assembly  183 . Coiled outer segmented heater assembly  183  is a coiled heater assembly because it includes heater coils. In this embodiment, coiled outer segmented heater assembly  183  includes heater coil  170  of  FIGS. 8   a  and  8   b , as indicated in a region  179  of  FIG. 12   a . However, in some embodiments, coiled inner segmented heater assembly  183  includes heater coil  170   a  of  FIGS. 9   a  and  9   b . In this way, coiled outer segmented heater assembly  183  is a coiled heater assembly. 
         [0174]    In this embodiment, coiled outer segmented heater assembly  183  includes radial gaps  166   a ,  166   bb ,  166   c  and  166   d  between outer peripheral gapped surface  173  and inner peripheral gapped surface  164 . Inner peripheral gapped surface  174  extends adjacent to inner gap  107  ( FIG. 6 ). In this way, inner gap  107  is bounded by outer peripheral surface  143  and inner peripheral gapped surface  164 . Inner gap  107  is dimensioned to inhibit the ability of current to flow between heater assemblies  182  and  183 . Intermediate segmented heater assembly  183  includes central opening  161 , which is sized and shaped to receive coiled heater plate  181   a  and  181   b  ( FIG. 6 ). 
         [0175]    In this embodiment, coiled outer segmented heater assembly  18   e  includes contacts  162   a  and  162   b , contacts  162   c  and  162   d  and contacts  162   e  and  162   f  which are spaced apart from each other by a radial gap  166   a ,  166   bb ,  166   c  and  166   d . Coiled outer segmented heater assembly  183  flows heat through opposed surfaces  165   a  and  165   b  in response to a potential differences established between contacts  162   a  and  162   b , between contacts  162   c  and  162   d , between contacts  162   e  and  162   f  and between contacts  162   g  and  162   h . Coiled outer segmented heater assembly  183  flows heat through opposed surfaces  162   a  and  162   b  in response to a current flowing between contacts  162   a  and  162   b , between contacts  162   c  and  162   d , between contacts  162   e  and  162   f  and between contacts  162   g  and  162   h , due to a potential difference established between contacts  162   c  and  162   d , a potential difference established between contacts  162   e  and  162   f  and a potential difference established between contacts  162   g  and  162   h . Radial gaps  1661 ,  166   b ,  166   c  and  166   d  are radial gap because it extends along a radial line  104 , which extends radially outward from a center  103  of heater plate sub-assembly  110  ( FIG. 1   a ). It should be noted that, in this embodiment, center  103  of heater plate sub-assembly  110  corresponds to a center of heater assembly  100 . 
         [0176]    It should be noted that a heater assembly can include many different combinations of the components discussed above. For example, the heater assembly can include various combinations of components from heater assembly  100  and  200   a . In this way, the heater assembly can be assembled to provide desired heating properties. Several examples of heater assemblies having different combinations of components will be discussed in more detail presently. 
         [0177]      FIG. 13   a  is a top view of one embodiment of a heater assembly  100   b . In this embodiment, heater assembly  100   b  includes heater plate  110  ( FIG. 2   a ) and coiled inner segmented heater  181  ( FIG. 10   a ). Further, heater assembly  100   b  includes coiled intermediate segmented heater  182  ( FIG. 11   a ) and coiled outer segmented heater  183  ( FIG. 12   a ). It should be noted that heater assembly  100   b  can be of uniform thickness, as shown in  FIG. 1   b , or of non-uniform thickness, as shown in  FIG. 1   c.    
         [0178]      FIG. 13   b  is a top view of one embodiment of a heater assembly  100   c . In this embodiment, heater assembly  100   c  includes heater plate  110  ( FIG. 2   a ) and inner segmented heater sub-assembly  120  ( FIG. 3   a ). Further, heater assembly  100   c  includes coiled intermediate segmented heater  182  ( FIG. 11   a ) and coiled outer segmented heater  183  ( FIG. 12   a ). It should be noted that heater assembly  100   c  can be uniform, as shown in  FIG. 1   b , or non-uniform, as shown in  FIG. 1   c.    
         [0179]      FIG. 13   c  is a top view of one embodiment of a heater assembly  100   d . In this embodiment, heater assembly  100   d  includes heater plate  110  ( FIG. 2   a ) and coiled inner segmented heater  181  ( FIG. 10   a ). Further, heater assembly  100   d  includes intermediate segmented heater sub-assembly  140  ( FIG. 4   a ) and coiled outer segmented heater  183  ( FIG. 12   a ). It should be noted that heater assembly  100   d  can be uniform, as shown in  FIG. 1   b , or non-uniform, as shown in  FIG. 1   c.    
         [0180]      FIG. 13   d  is a top view of one embodiment of a heater assembly  100   e . In this embodiment, heater assembly  100   e  includes heater plate  110  ( FIG. 2   a ) and coiled inner segmented heater  181  ( FIG. 10   a ). Further, heater assembly  100   e  includes coiled intermediate segmented heater  182  ( FIG. 11   a ) and outer segmented heater sub-assembly  160  ( FIG. 5   a ). It should be noted that heater assembly  100   e  can be uniform, as shown in  FIG. 1   b , or non-uniform, as shown in  FIG. 1   c.    
         [0181]      FIG. 13   e  is a top view of one embodiment of a heater assembly  100   f . In this embodiment, heater assembly  100   f  includes heater plate  110  ( FIG. 2   a ) and inner segmented heater sub-assembly  120  ( FIG. 3   a ). Further, heater assembly  100   f  includes intermediate segmented heater sub-assembly  140  ( FIG. 4   a ) and outer segmented heater sub-assembly  160  ( FIG. 5   a ). It should be noted that heater assembly  100   f  can be uniform, as shown in  FIG. 1   b , or non-uniform, as shown in  FIG. 1   c.    
         [0182]    In this embodiment, heater assembly  100   f  ( FIG. 13   e ) includes one or more segmented heater assemblies positioned around outer segmented heater sub-assembly  160 , as indicated by the ellipses of  FIG. 13   e . The number of segmented heater assemblies of heater assembly  100   f  is chosen in response to an area it is desired to heat. In general, the number of segmented heater assemblies of heater assembly  100   f  increases and decreases as the number of wafers increases and decreases, or as the size of the susceptor increases or decreases respectively. 
         [0183]      FIG. 14   a  is a cut-away side view of a deposition system  200 . Deposition system  200  can be of many different types, such as a chemical vapor deposition (CVD) system. In one particular, embodiment, deposition system  200  is a metalorganic chemical vapor deposition (MOCVD) system. Deposition system  200  can be used to deposit many different types of material, such as semiconductor material. One particular type of semiconductor material that can be deposited using deposition system  200  is a semiconductor nitride. There are many different types of semiconductor nitrides that can be deposited using deposition system  200 , such as gallium nitride and alloys thereof. There are many different alloys of gallium nitride, such as indium gallium nitride and aluminum gallium nitride, among others. 
         [0184]    It should be noted that the materials deposited using deposition system can be used in many different types of semiconductor devices, such as electrical devices and optoelectronic devices. Some examples of electrical devices include diodes and transistors, among others. Examples of optoelectronic devices include light emitting diodes, semiconductor lasers, photo-detectors and solar cells, among others. 
         [0185]    In this embodiment deposition system  200  ( FIG. 14   a ) includes:
       a. A reactor housing  204  usually fluid cooled and constructed from materials such as quartz, aluminum or stainless steel,   b. A reactor chamber  204   a  top and  204   b  bottom bounded by housing  204 ,   c. A process zone  108  bounded by process chamber  204   a  and  204   b,      d. A rotatable susceptor  205  of one or more pieces carried by pedestal  213  supporting the wafer(s)  206  in the process zone  108 , further a rotation motor  207  and a susceptor lift/wafer lift  208  are operatively coupled to pedestal(s)  213 ,   e. A heater assembly  100  as in  FIG. 1   a  for example, mounted above and below the reactor chamber  204   a / 204   b  to provide adjustable amounts of heat to the reactor chamber  102 , susceptor  205  and wafers  206 ,   f. A temperature/thermal sensor(s)  203  sensing the wafer(s)  206 , susceptor(s)  205  or heater assembly(ies)  100  or combinations thereof; further, temperature sensors include but are not limited to thermocouples, reflectometers or pyrometers. Purged sealed ports/view ports outside of the reactor chamber environment may be arranged to accommodate temperature/thermal sensor(s)  203  such as thermocouples and or pyrometers. There may also be holes (not shown) in reactor chamber  204   a / 204   b  for the temperature sensor(s)  203 .   g. A system controller  201  and a temperature control system  202  providing adjustable power signals S T  to the heater assembly(ies)  100  via heater terminals  217  and  218 , further temperature controller  202  receives temperature signals S c  from temperature/thermal sensor  203  via system controller  201 . Further, system controller  201  controls the movement of sealed access door  215  to allow loading and unloading the wafer and sealing of the loading port  210 . System controller  201  also controls wafer movement, process gas sequencing and gas flow to reactor chamber  204   a / 204   b , and other functions such as purge flows, process times, cooling flows and safety controls. Further, system controller  201  also controls rotation motor  207  and susceptor lift mechanism  208  via signal S c .   h. Heat shields  209  and heat shield liners  209   a  disposed between the heater assembly(ies)  100  and the reactor housing to minimize heat transfer/loss from the heater assembly(ies)  100  into the reactor housing  204 , and provide reradiating surfaces to heater assembly(ies)  100  and reactor chamber  204   a / 204   b . In an embodiment, reactor chamber  204   a / 204   b , susceptor(s)  205  and heat shield(s)  209  and  209   a  are made of a material such as but not limited to quartz, silicon carbide and silicon carbide coated graphite. Further, liner heat shield  209   a  is arranged to protect the interior surfaces of housing  204 .   i. The amount of heat provided by each heater sub-assembly such as heater  110 ,  120 ,  140  and  160  of the heater assembly  100  is controllable. The amount of heat provided by a heater sub-assembly such as heater  110 ,  120 ,  140  and  160  of the heater assembly  100  is adjustable to adjust the temperature of the reactor chamber  204   a / 204   b , the susceptor  205  and or the wafer(s)  206 . The amount of heat provided by each heater sub-assembly such as heater  110 ,  120 ,  140  and  160  of the heater assembly  100  is adjustable to adjust the temperature of the inlet gas. The amount of heat provided by each heater sub-assembly such as heater  110 ,  120 ,  140  and  160  of the heater assembly  100  is adjustable in response to adjusting a current flow therethrough.   j. The deposition system  200  is capable of operating at pressures above or below atmospheric pressure.       
 
         [0196]    In this embodiment deposition system  200  ( FIG. 14   a ) includes:
       k. A gas inlet and wafer loading duct  214  and a gas exhaust duct  214   a  connected respectively to inlet/loading port  210  and exhaust port  210   a,      l. Upstream and downstream gas inlet conduit(s)  211  and  212  are connected to gas inlet and loading duct  214  to supply process gases to reactor chamber  204   a / 204   b . The gas inlet and loading duct  214  also serves as access for loading and unloading the wafer(s)  206  to and from the reactor chamber  204   a / 204   b  through loading port  210  via the sealed access door  215  controlled by system controller  201 . Gas exhaust duct(s)  214   a  removes exhaust gases from reactor chamber  204   a / 204   b  out exhaust port  210   a . Gas inlet and loading duct(s)  210  and gas exhaust duct(s)  210 , susceptor  205  and reactor chamber  204   a / 204   b  are made of one or more pieces of materials such as but not limited to silicon carbide, and silicon carbide coated graphite.   m. A top and bottom sealed/purged cover box  204   c  is sealed to housing  204  enclosing electrical terminals  217  and  218  which supply adjustable power signals to heater assembly(ies)  100  (only one power signal to the top and bottom heater assembly  100  is shown for simplicity).       
 
         [0200]      FIG. 14   b  is cross sectional view of the heater assemblies  100  such as shown in  FIG. 1   a ,  FIG. 1   b , and  FIG. 1   d  showing heater sub-assemblies  110 ,  120 ,  140  and  160  including process chamber  204   a / 204   b , susceptor  205  and wafers  206  and the gas inlet and loading duct  210 , the upstream gas inlet conduit  211  and the downstream gas inlet conduit  212  and exhaust duct  210   b  of deposition system  200 . In this embodiment the temperature control system  202  is connected to each heater sub-assembly  110 ,  120 ,  140  and  160  of heater assembly  100  top and bottom by heater terminals  217   a  through  217   g  and  218   a  through  218   g  respectively, thereby providing adjustable power signals S T1a  through S T7a  and S T1b  through S T7b  to each heater sub-assembly  110 ,  120 ,  140  and  160  of heater assembly  100  both top and bottom (only one connection is shown for each heater for the sake of simplicity). Each heater sub-assembly  110 ,  120 ,  140  and  160  of top and bottom heater assembly  100  provides adjustable amounts of heat to the top and bottom of the reactor chamber  204   a / 204   b , to susceptor  205  and wafers  206  on susceptor  205  of process zone  108  of disposition system  200 . The proper selection of heater sub-assembly shape and number heater sub-assemblies as previously discussed provides the ability to produce a heat/temperature profile across the susceptor  205  in process zone  108  resulting in a temperature profile as depicted in  FIG. 1   g.    
         [0201]      FIG. 14   c  is cross sectional plan view along cut line  14   b - 14   b  of  FIG. 14   b  of deposition system  200  showing wafer(s)  206  on the rotatable susceptor  205  in process zone  108 . In this embodiment, a plurality of gas(es)  230  and  231  are controlled by gas flow control devices and on/off valve(s)  230   a  through  230   b  and  231   a  through  231   b  that control the flow of the plurality of gases  230  and  231 . The plurality of gas(es)  230  and  231  are then introduced into to the gas inject conduits  211   a  through  211   b  and  212   a  through  212   b  which feed the plurality of gas(es)  230  and  231  gas into the inlet/loading duct  214  and then over the wafers  206  on susceptor  205  at an adjustable heat/temperature as discussed above in process zone  108 . This provides multiple sub-process zones (not shown) of process zone  108  in which the heat/temperature and the gas flow(s) of the sub-process zones are controlled in order to deposit layers of uniform thickness and composition on the wafer  206  on rotating susceptor  205 . Effluent gases exit via exhaust duct  214   a.    
         [0202]      FIG. 14   d  is a cross section plan view of heater array  100  along cut line  14   b   1 - 14   b   1  of  FIG. 14   b  of deposition system  200  showing a representative upper heater assembly  100  (Reference  FIG. 1   a ) consisting of heater sub-assemblies  110 ,  120 ,  140   a  and  140   b  and  160   a ,  160   b ,  160   c  and  160   d . The annular gaps  105 ,  106  and  107  as previously described are also shown. Again, a plurality of gas(es)  230  and  231  are controlled by gas flow control devices and on/off valve(s)  230   a  through  230   b  and  231   a  through  231   b  that control the flow of the gases  230  and  231 . The plurality of gas(es)  230  and  231  are then introduced into the gas inject conduits  211   a  through  211   b  and  212   a  through  212   b  which feed the plurality of gas(es)  230  and  231  gas inlet/loading duct  214 . The gasses then pass through the reactor chamber  240 / 240   a  where the plurality of gasses  230  and  231  are selectively heated by the sub-assembly heaters of heater assembly  100  both top and bottom along with heating the wafers  206  and susceptor  205  of FIG.  14   c  to provide a deposition of uniform thickness and composition on the wafer(s)  205  while minimizing the wafer temperature differential in the vertical and horizontal direction. Effluent gases exit via exhaust duct  214   a.    
         [0203]      FIG. 14   e  is an expanded view of the upper and lower heater arrays  100  of deposition system  200 . Each heater  110 ,  120 ,  130  and  140  has an electrically conductive transitory connection  112 ,  122 ,  142  and  162  designed to minimize heat transfer but maximize electrical conduction in the transition from heater materials to electrical heater terminals  217   a  through  217   g  and  218   a  through  218   g  which are then connected to adjustable power signals S T1a  through S T7a  and S T1b  through S T7b  to each heater sub-assembly  110 ,  120 ,  140  and  160  of heater assembly  100  both top and bottom individually controlled or controlled in groups/zones. This is accomplished by arranging temperature sensor(s)  203  from  FIG. 14   a  and heater sub-assemblies  110 ,  120 ,  140  and  160  to establish independently controlled zones of heat for example, of the front, rear, left, right and center sections (not shown) of the process zone  108  thereby compensating for the different thermal requirement/radiation losses within each zone to produce a uniform temperature across and through the susceptor  205  and wafer(s)  206 . The bottom heater assembly  100  may or may not be parallel and coincident to the top heater assembly  100 . The ability to control the temperatures in general of the individual heater sub-assemblies or in multiple independent groups of heater sub-assemblies is a significant advantage of this invention as can be seen in  FIG. 14   f  which shows a temperature profile  190  of a wafer in a system as describe herein in  FIG. 14   a  versus the temperature profile  191  of a wafer of a induction heated prior art system and a temperature profile  192  of a wafer in an IR lamp heated prior art system. This “new technology” describe herein far exceeds the others with a ±0.5° C. temperate uniformity across a 150 mm wafer versus ±3.1° C. and ±2.4° C. for the induction heated and IR lamp heated system respectively. 
         [0204]      FIG. 15   a  is a side cross-sectional view of reactor chamber  204   a / 204   b  of deposition system  200   a .  FIG. 15   b  is an expanded cross sectional side view of the gas injection scheme as defined by region  219  of  FIG. 14   b . The upstream gas inlet conduits  211  is disposed so as to independently inject/spread an individually controlled flow of a process gas(es) as described in  FIGS. 14   c  and  14   d , being either carrier and or reactant gases  230 , perpendicularly into the interior of gas inlet and loading duct  214  at port  226  being a hole, multiple holes, or slit(s) of a size  228  such that a substantially laminar flow/gas velocity profile  236  of the carrier and or reactant gases is established with an attendant boundary layer  232 . Downstream gas inlet conduit(s)  212  is positioned downstream of the upstream gas inlet conduit  211  in the laminar flow region. Downstream gas inlet port(s)  225 , may be designed as a slit(s) or hole(s) of size  227  with a upstream dimension  227   a  and a downstream dimension  227   b  shaped to inject a process and or carrier gas  238  utilizing the Coanda effect* substantially tangentially into the boundary layer  232  of the laminar flow/gas velocity profile  236  produced by upstream gas inlet port(s)  226  and gas inlet and loading duct  214  such that the gasses injected by downstream gas inlet port(s) substantially attach themselves to the lower inside surface of gas inlet and loading duct  214  and flow in streams closely over and parallel to the inside bottom surface of the gas inlet and loading duct  214  and then over the top surface of wafers  206  on susceptor  205 . The embodiment of this gas introduction scheme maximizes the reaction efficiency of the plurality of process gas(es)  231  with the wafer(s)  206  on susceptor  205  thereby maximizing the deposition rate and conversion efficiency of gas(es)  238  and minimizing reactant gas depletion across the susceptor. This tangential Coanda gas introduction systems is also capability of separately delivering reactant gases  230  and  231  to the process zone  108  (such as ammonia and Trimethylgallium commonly used in manufacturing High Brightness LEDs, these reactant can also be delivered to the process zone  108  via separate Coanda port(s)  225  both methods which eliminate premature gas reactions which result in clogging, plugging, particle generation in the gas delivery system or reactor chamber.
       n. *(The Coanda effect is briefly described as the tendency of a fluid jet to be attracted to a nearby surface [1] . The principle was named after Romanian aerodynamics pioneer Henri Coand{hacek over (a)}, who was the first to recognize the practical application of the phenomenon in aircraft development. Much is published in literature and text books on aeronautical boundary layer injection, the Coanda effect and boundary layer deposition physics).  1 From Wikipedia       
 
         [0206]      FIG. 15   c  is a pictorial view of the one of the upstream gas inlet ports  226  and one of the downstream gas inlet ports  225 . 
         [0207]      FIG. 15   d  is an expanded view along cut line  15   d - 15   d  of  FIG. 15   c  of one the upstream gas inlet port  226  which is fed by gas inlet conduit  211  and the tangential inject port  225  which is fed by gas inlet conduit  212 . 
         [0208]      FIG. 15   e  is a plan view of the upstream gas injection system of deposition system  200 . In this embodiment a plurality of gasses are controlled by a plurality of flow control devices and on off valves  231   a ,  231   b ,  231   c ,  231   d  and  231   e  feeding upstream conduits  211   a ,  211   b ,  211   c ,  211   d  and  211   e  in turn feeding tangential gas injection port assembly  226   a ,  226   b ,  226   c ,  226   d  and  226   e  wherein the gas is injected into inlet gas inlet and loading duct  214  then over the tangential gas injection port assembly  229   a ,  229   b ,  229   c ,  229   d  and  229   e . The plurality of gases then passing over the wafers  206  on susceptor  205  in reactor chamber  204   b  and then out the exhaust duct  210   a.    
         [0209]      FIG. 15   f  is a plan view of the downstream gas inject embodiment of deposition system  200 . In this embodiment a plurality of gasses are controlled by a plurality of flow control devices and on off valves  230   a ,  230   b ,  230   c ,  230   d  and  230   e  feeding downstream conduits  212   a ,  212   b ,  212   c ,  212   d  and  212   e  in turn feeding tangential gas injection port assembly  229   a ,  229   b ,  229   c ,  229   d  and  229   e  wherein the gas is injected into gas inlet and loading duct  214  substantially tangentially out of ports  225   a ,  225   b ,  225   c ,  225   d , and  225   e  then over the wafers  206  on susceptor  205  in reactor chamber  204   b  and then out the exhaust duct  214   a.    
         [0210]    The upstream and downstream gas inlet conduit(s)  211  and  212  are constructed of one or more pieces of a suitable materials such as silicon carbide, silicon carbide coated graphite or graphite or combinations thereof. The number of upstream conduits  211  and downstream conduits  212  can be added or subtracted as determined by the process deposition requirements of the deposition system  200  and the size of the susceptor  205  and wafer(s)  206 . 
         [0211]      FIGS. 16   a ,  16   b  and  16   c  shows a cross sectional view, an exploded cross sectional view and plan view respectively of a vertical gas inject scheme of deposition system  200   b . In this embodiment, a double walled multi gas chamber upper plate  204   d  replaces the upper reactor chamber (plate)  204   a  of  FIG. 14   a . below heater assembly  100   a . A plurality of separate gas inlet conduits  220   a ,  220   b ,  200   c ,  220   d ,  220   d ,  220   e ,  220   f ,  220   g  on the uppermost plate  242   a  each connected to a plurality of gas channel circular segments, circles or rings  245   a ,  245   b ,  245   c ,  245   d ,  245   e ,  245   f ,  245   h  and  245   g  each having a uppermost plate  242  and bottom plate  243  and separators  244  forming a gas cavity/plenum(s)  245   a  and  245   b , for example as shown in  FIG. 16   b , with an array of holes  224   a  and  224   b  in bottom plate  243  for vertically impinging inlet gas(es)  224   c  and  224   d  (C onto the wafers  206  on susceptor  205  or comingling with the horizontal gas flow from ports  226  and or  225 . 
         [0212]    Each gas inlet ports  220   a ,  220   b ,  200   c ,  220   d ,  220   d ,  220   e ,  220   f ,  220   g  are connected to a gas flow control devices such as valves, mass flow controllers and or metering devices (not shown) for independently controlling a plurality of inlet gas(es)  248   a  and  248   b  ( FIG. 16   b ) for example to each cavity/plenum  245   a ,  245   b ,  245   c ,  245   d ,  245   e ,  245   f ,  245   h  and  245   g . The inlet gas(es)  248   a  and  248   b  may be reactant and or carrier gas(es). The cavity/plenum  245   a ,  245   b ,  245   c ,  245   d ,  245   e ,  245   f ,  245   h  and  245   g  can be of various width(s)  237   a ,  237   b ,  237   c  and  237   c  as shown in  FIG. 16   c . The array of holes  224   a  and  224   b  for example, may or may not be uniform in size and spacing, in order to provide a uniform vertical flow of gas(es)  224   c  and  224   d  to the wafer(s)  206  on susceptor  206  from the circular segments. This vertical flow  224   c  and  224   d  for example may comingle with the horizontal gas flow  235  of  FIG. 15   b  in reactor chamber  204   a / 204   b  at the surface of the wafer(s)  206 . This enables increased growth rates of the gas(es) from gas ports  225  and  226 , and or a means to separately introduce reactant gases that need to substantially combine/react only at the surface of wafer  206  to chemically vapor deposit compounds. Adjusting the flow of inlet gas(es)  248   a  and  248   b  can be used to vary and tune the deposition rate of the reactant gases and or those from gas ports  225  and  226 . Another feature of this embodiment is the circular upper heater assembly previously described in  FIG. 14   a  is positioned parallel/close to the uppermost plate  204   c . Heater sub-assemblies  140  and  160  of upper heater assemblies  100  may be associated with for example gas channel segments  245   a  and  245   b  together forming a controlled deposition zone (not shown) in which the temperature and flow can be independently controlled for tuning the deposition rate on the wafer  206 . An additional beneficial effect is that heaters  140  and  160  for example, preheat the inlet gas(es)  248   a  and  248   b  in cavity  245   a  and  245   b  before it arrives at the surface of wafer  206 . This minimizes the thermal impact of a cold gas on the wafer  206  and improving the reaction rate and minimizes the potential of wafer warpage that is a problem with prior art systems. Top plate  204   c  may be constructed of materials such as but not limited to silicon carbide, silicon carbide coated graphite or graphite. 
         [0213]      FIG. 16   d  shows a comparison of the deposition profile across a non-rotating susceptor of a deposited layer for:
       o. a prior art deposition system  250 ,   p. a deposition profile  251  of a deposition system  200   a  as described in  FIGS. 14   a ,  14   b ,  14   c  and  14   d  and  FIGS. 15   a ,  15   b ,  15   c  and  15   d  herein using the heating system discussed herein and the gas injection embodiment of  FIGS. 15   a ,  15   b , and  15   c      q. a deposition profile  252  of depositions system  200   b  as described in  FIG. 16   a ,  FIG. 16   b ,  FIG. 16   c . herein, the gas injections system of  FIG. 15  and the vertical gas introduction technique of  FIG. 16   a ,  FIG. 16   b  and  FIG. 16   c.  
 
This deposition profile is commonly called the “depletion curve” and defines the deposition thickness across the susceptor as the reactant gases are “used-up” or depleted as they travel across the susceptor. As can be seen the technology described herein has a much more favorable depletion curve that results in a more uniform deposition across the susceptor and therefore a more uniform deposition on the wafers  206 .
         
         [0217]    Deposition systems in general all require a cleaning step for removing extraneous deposits on the internal surfaces of the reactor process chamber, the susceptor and gas inlet and exhaust conduits/ducts left behind by the deposition process. In some cases this is an insitu gas phase, high temperature cleaning step. In other cases of prior art, the cleaning step may require a complete reactor shutdown and disassembly to replace and or clean these parts. This removal and cleaning is one of the biggest reasons for reactor internal parts breakage and damage, reactor contamination and downtime. Also, the prior art system&#39;s seals may have be replaced due to damage caused by the high temperatures and exposure to deposition and etchant gases. Every time this cleaning takes place, a requalification of the process is required. This cleaning and requalification can take up to 16 hours which is lost production time. In the case of the MOCVD systems, the gas phase cleaning step of the residual deposits is ineffective and therefore the internal parts of the reactor are removed, cleaned and or replaced with new parts, which is very costly. The heating embodiment of deposition system  200  ( FIG. 14   a ), the materials of construction of the reactor chamber  204 / 204   b , the gas injections systems ( FIG. 15   a, b, c, d  and  FIG. 16   a, b  and  c ) allow for a more effective means of introducing a cleaning gases and or using different etchant/cleaning gases via  230  and  231  ( FIG. 15   e  and  f ) enhancing the effectiveness of the insitu gas phase cleaning (etching) of the deposits left behind thereby improving system uptime. 
         [0218]    It is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting. As such, those skilled in the art will appreciate that the conception, upon which this disclosure is based, may readily be utilized as a basis for the designing of other structures, methods and systems for carrying out aspects of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention. 
         [0219]    Further, the purpose of the foregoing abstract is to enable the U.S. Patent and Trademark Office and the public generally, and especially the scientists, engineers and practitioners in the art who are not familiar with patent or legal terms or phraseology, to determine quickly from a cursory inspection the nature and essence of the technical disclosure of the application. The abstract is neither intended to define the invention of the application, which is measured by the claims, nor is it intended to be limiting as to the scope of the invention in any way.