Patent Publication Number: US-2002007795-A1

Title: Temperature control system for plasma processing apparatus

Description:
BACKGROUND OF THE INVENTION  
       [0001] 1. Field of the Invention  
       [0002] The present invention relates to fabrication of semiconductor integrated circuits and, more particularly, to temperature control of plasma processing systems.  
       [0003] 2. Description of the Related Art  
       [0004] In the fabrication of semiconductor-based devices, e.g., integrated circuits or flat panel displays, layers of materials may alternately be deposited onto and etched from a substrate surface. During the fabrication process, various layers of material, e.g., borophosphosilicate glass (BPSG), polysilicon, metal, etc. are deposited on the substrate. The deposited layers may be patterned with known techniques, e.g., a photoresist process. Thereafter, portions of the deposited layers can be etched away to form various features, e.g., interconnect lines, vias, trenches, and etc.  
       [0005] The process of etching may be accomplished by a variety of known techniques, including plasma-enhanced etching. In plasma-enhanced etching, the actual etching typically takes place inside a plasma processing chamber. To form the desired pattern on the substrate wafer surface, an appropriate mask (e.g., a photoresist mask) is typically provided. With the substrate wafer in the plasma processing chamber, a plasma is then formed from suitable etchant source gas (or gases). The plasma is used to etch areas that are left unprotected by the mask, thereby forming the desired pattern. In this manner, portions of deposited layers are etched away to form interconnect lines, vias, trenches, and other features. The deposition and etching processes may be repeated until the desired circuit is obtained.  
       [0006] To facilitate discussion, FIG. 1 depicts a simplified plasma processing apparatus  100  suitable for fabrication of semiconductor-based devices. The simplified plasma processing apparatus  100  includes a plasma processing chamber  102  having an electrostatic chuck (ESC) or other wafer support  104 . The chuck  104  acts as an electrode and supports a wafer  106  (i.e., substrate) during fabrication. The surface of the wafer  106  is etched by an appropriate etchant source gas that is released into the wafer processing chamber  102 . The etchant source gas can be released through a showerhead  108 . The plasma processing source gas may also be released by other mechanisms such as through holes in a gas distribution plate. A vacuum plate  110  maintains a sealed contact with walls  112  of the wafer processing chamber  102 . Coils  114  provided on the vacuum plate  110  are coupled to a radio frequency (RF) power source (not shown) and used to strike (ignite) a plasma from the plasma processing source gas released through the showerhead  108 . The chuck  104  is also typically RF powered during the etch processes using a RF power supply (not shown). A pump  116  is also included to draw the process gases and gaseous products from the plasma processing chamber  102  through a duct  118 .  
       [0007] As is known by those skilled in the art, in the case of semiconductor processing, such as etch processes, a number of parameters within the wafer processing chamber need to be tightly controlled to maintain high tolerance results. The temperature of the wafer processing chamber is one such parameter. Since the etch tolerance (and resulting semiconductor-based device performance) can be highly sensitive to temperature fluctuations of components in the system, accurate control therefore is required. To further elaborate, the chamber temperature at which etching processes are performed needs to be tightly controlled to achieve desirable etch characteristics. Moreover, as feature sizes of modern integrated circuits continue to be reduced, it becomes increasingly more difficult to process the desired features using conventional plasma processing systems.  
       [0008] In plasma processing apparatus, plasma formed by excited process gasses is used to manufacture semiconductor devices, the excitation of the process gasses to produce the plasma is a high energy operation that causes heating of various components of the plasma processing apparatus. This heating effects the precision and repeatability of the processes performed by the plasma processing device. As feature sizes continue to get smaller, there is an ever increasing need to provide plasma processing apparatus with better temperature control in order to provide consistent and precise fabrication of semiconductor devices.  
       [0009] Conventionally, heating has been provided to plasma processing chambers by providing the plasma processing chambers with heated inner walls or by heating the plasma processing chamber using small heat lamps. Heating is typically used to pre-heat the plasma processing chamber before processing begins. Cooling was often not actively provided, thus cooling was simply passive through convection and radiation. Typically, these thermal solutions were designed for aluminum liners of plasma processing chambers and thus are not well suited for heating or cooling ceramic liners which is a more difficult task. Aluminum lines also lead to significant contamination which is why ceramic liners are considered.  
       [0010] In view of foregoing, there is a need for improved plasma processing systems that provide better temperature control over semiconductor processing equipment.  
       SUMMARY OF THE INVENTION  
       [0011] Broadly speaking, the invention pertains to a temperature management system and method that can achieve very accurate temperature control over a plasma processing apparatus. In one embodiment, the temperature management system and method operate to achieve tight temperature control over surfaces of a plasma processing apparatus which interact with the plasma during fabrication of semiconductor devices. The tight temperature control offered by the invention provides greater process control for the plasma processing apparatus which is becoming more and more important as feature sizes continue to get smaller.  
       [0012] The invention can be implemented in numerous ways, including as a system, apparatus, machine, or method. Several embodiments of the invention are discussed below.  
       [0013] As a plasma processing apparatus, one embodiment of the invention includes at least: a processing chamber having walls and a lid, the walls and the lid both have an internal surface and an exterior surface, the processing chamber being used to process a substrate using a plasma produced by process gases; and a thermal management system thermally coupled to an exterior surface of the processing chamber, the thermal management system including at least one combination heating and cooling block that is controlled to regulate a temperature internal to the processing chamber.  
       [0014] As a semiconductor manufacturing apparatus, one embodiment of the invention includes at least: a plasma processing chamber formed by walls and a bottom surface; a sealing lid removably coupled to a top portion of the walls of the plasma processing chamber; an RF powered electrode provided on an upper surface of the sealing lid; at least one temperature sensor coupled to the sealing lid or the plasma processing chamber; a first heating and cooling unit coupled to the upper surface of the sealing lid; and a second heating and cooling unit coupled to an outer surface of the walls of the plasma processing chamber.  
       [0015] As a method for providing temperature control to a plasma processing chamber of a plasma processing apparatus, the method includes at least the acts of: directly or indirectly measuring temperature internal to the plasma processing chamber; comparing the measured temperature to a target temperature; heating the plasma processing chamber by heating a thermal control block that is thermally coupled to the plasma processing chamber; and cooling the plasma processing chamber by actively cooling the thermal control block.  
       [0016] As a plasma processing apparatus, another embodiment of the invention includes at least: a processing chamber having walls and a lid, the walls and the lid both have an internal surface and an exterior surface, the processing chamber being used to process a substrate using a plasma produced by process gases; and means for regulating a temperature internal to the processing chamber by heating the processing chamber with a heater element when the internal temperature is below a lower target temperature and cooling the processing chamber, through the heater element, with a cooling element when the internal temperature is above an upper target temperature.  
       [0017] As a combination heating and cooling block, according to yet another embodiment of the invention, the combination heating and cooling block has a sandwich construction and includes at least a heater element, a cooling element, and a thermal break element between the heater element and the cooling element.  
       [0018] The advantages of the invention are numerous. Different embodiments or implementations may yield one or more of the following advantages. One advantage of the invention is that the invention allows temperature of plasma processing devices to be controlled with substantially decreased drift.. Another advantage of the invention is that the temperature of the plasma processing devices can be controlled with increased accuracy to enable better device to device matching. Another advantage of the invention is that both heating and cooling are provided through a common thermal interface. Still another advantage of the invention is that by using a common thermal interface, not only can both cooling and heating be provided, but the resulting temperature profile of the surface being temperature controlled is uniform and smooth. Also the temperature profile of the surface being temperature controlled can be invariant in space and time during the transients caused by wafer processing. Yet another advantage of the invention is that it is non-invasive and easily removable.  
       [0019] Other aspects and advantages of the invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings illustrating, by way of example, the principles of the invention. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0020] The present invention will be readily understood by the following detailed description in conjunction with the accompanying drawings, wherein like reference numerals designate like structural elements, and in which:  
     [0021]FIG. 1 depicts a simplified plasma processing apparatus suitable for fabrication of semiconductor-based devices;  
     [0022]FIG. 2A illustrates a heating and cooling unit according to one embodiment of the invention;  
     [0023]FIG. 2B is a block diagram of a temperature control system according to one embodiment of the invention;  
     [0024]FIG. 3 is a cross-sectional diagram of a plasma processing apparatus according to one embodiment of the invention;  
     [0025]FIG. 4 is a cross-sectional diagram of a plasma processing apparatus according to another embodiment of the invention;  
     [0026]FIG. 5 is a top view of a cooling block provided on a vacuum plate as provided by the plasma operating apparatus illustrated in FIG. 4 according to one embodiment;  
     [0027]FIG. 6 illustrates a cross-sectional diagram of a plasma processing apparatus according to another embodiment of the invention;  
     [0028]FIG. 7 is a cross-sectional diagram of a plasma processing apparatus according to yet another embodiment of the invention;  
     [0029]FIG. 8A illustrates a portion of side wall heating and cooling system from a top view having two heating and cooling units thermally coupled to thereto;  
     [0030]FIG. 8B is a diagram of an alternative construction of a chamber wall of a plasma processing apparatus;  
     [0031]FIG. 9 is a top view of a cross-section of a plasma processing chamber according to one embodiment of the invention;  
     [0032]FIG. 10 illustrates a cross-sectional side view of a portion of a plasma processing chamber in which a chamber wall and an outer container wall are provided; and  
     [0033]FIG. 11 is a cross-sectional diagram of a plasma processing apparatus according to still another embodiment of the invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
     [0034] The invention pertains to a temperature management system and method that can achieve very accurate and precise temperature control over a plasma processing apparatus. In one embodiment, the temperature management system and method operate to achieve tight temperature control over surfaces of a plasma processing apparatus which interact with the plasma during fabrication of semiconductor devices. The tight temperature control offered by the invention provides greater process control for the plasma processing apparatus which is becoming more and more important as feature sizes continue to get smaller.  
     [0035] In a plasma processing apparatus which uses plasma formed by excited process gasses to manufacture semiconductor devices, the excitation of the process gasses to produce the plasma is a high energy operation that causes heating of various components of the plasma processing apparatus. The invention pertains to a temperature management system and method that can achieve very accurate temperature control over a plasma processing apparatus. In one embodiment, the temperature management system and method operate to achieve tight temperature control over surfaces of the plasma processing apparatus which interact with the plasma used to fabricate the semiconductor devices.  
     [0036] In one implementation, the temperature control system includes a heating and cooling unit that is coupled to an outer surface of a plasma processing chamber of a plasma processing apparatus to be temperature controlled. The heating and cooling unit serves to couple heat into or away from (i.e., heat or cool) the surface being controlled through the same thermal interface.  
     [0037] Embodiments of the invention are discussed below with reference to FIGS.  2 - 11 . However, those skilled in the art will readily appreciate that the detailed description given herein with respect to these figures is for explanatory purposes as the invention extends beyond these limited embodiments.  
     [0038]FIG. 2A illustrates a heating and cooling unit  200  according to one embodiment of the invention. The heating and cooling unit  200  is used to heat or cool a surface  202 . The surface  202  is assumed to be a surface that requires both heating and cooling. For example, the surface  202  could initially require heating then later require cooling. In any case, temperature of the surface  202  is required to be accurately and precisely controlled. The heating and cooling unit  200  as shown in FIG. 2A includes a conformal thermal interface  204 , a heating block  206 , a thermal break  208 , and a cooling block  210 . The conformal thermal interface is a thin layer of a material, such as metal-impregnated silicone rubber, which has a relatively high effective thermal coefficient because of the thinness of the layer and is easily conformable. Hence, the conformal thermal interface  204  provides high thermal coupling between the surface  202  and the heating block  206 . The heating block  206  is able to generate heat that couples to the surface  202  through the conformal thermal interface  204 . To generate the heat, the heating block  206  can include one or more resistive elements. The resistive elements can heat the heating block  206  through use of a controlled current or voltage. As an example, the heating block  206  is made of a metal material such as aluminum.  
     [0039] The thermal break  208  is sandwiched between the heating block  206  and the cooling block  210 . The thermal break  208  is, for example, a silicone rubber substance. Typically, the thermal conductivity of the thermal break  208  is substantially less than the thermal conductivity of the conformal thermal interface  204  because of the thickness of the layer. The thermal break  208  serves to provide a transition region between the heating block  206  and the cooling block  210  so that both can be provided in the heating and cooling unit  200 . The cooling block  210  is able to cool the surface  202  through the heating block  206  and the conformal thermal interface  204 . The cooling block  210  is itself cooled with a cooling element. In one implementation, the cooling element is a temperature controlled liquid (e.g., water) that flows through the cooling block  210 . The cooling block  210  can, for example, be made of metal, such as aluminum.  
     [0040]FIG. 2B is a block diagram of a temperature control system  250  according to one embodiment of the invention. The temperature control system  250  operates to control the temperature of a surface  252 . For example, the surface  252  can be associated with an external surface of a plasma processing chamber of a plasma processing apparatus.  
     [0041] The temperature control system  250  includes a thermal manager  254  that controls the overall operation of the temperature control system  250  so that the surface  252  is maintained at a suitable temperature. The thermal manager  254  is able to control both heating and cooling of the surface  252  as needed to maintain the desired temperature. The thermal manager  254  obtains a temperature of the surface  252  from a temperature sensor  256  that is coupled to the surface  252 . In accordance with the temperature obtained from the temperature sensor  256 , the thermal manager  254  determines whether the surface  252  requires heating or cooling. When the thermal manager  254  determines that the surface  252  requires heating, the thermal manager  254  can activate a heater element  258  and a heater element  260 . Typically, the heater elements  258  and  260  are simultaneously activated to heat the surface  252  in a similar manner. On the other hand, when the thermal manager determines that the surface  252  requires cooling, the thermal manager  254  can activate a cooling element  262  and a cooling element  264 . Typically, the cooling elements  262  and  264  are simultaneously activated to cool the surface  252  in a similar manner. As shown in FIG. 2B, the cooling elements  262  and  264  are coupled to the surface  252  through the heating elements  258  and  260 , respectively. By coupling the cooling elements to the surface  252  through the heater elements  258  and  260 , a smoother spatial and temporal temperature profile can be provided to the surface  252 , thereby producing a more uniform temperature profile at the surface  252 .  
     [0042] Typically, when the heater elements  258  and  260  are activated, the cooling elements  262  and  264  are not activated and, when the cooling elements  262  and  264  are activated, the heater elements  258  and  260  are deactivated. Nevertheless, in some situations, it may be useful to have respective heating and cooling elements both activated at the same time. In one embodiment, the combination of the heater element  258  and the cooling element  262  and the combination of the heater element  260  and the cooling element  264  can be constructed as is the heating and cooling unit  200  illustrated in FIG. 2A.  
     [0043]FIG. 3 is a cross-sectional diagram of a plasma processing apparatus  300  according to one embodiment of the invention. The plasma processing apparatus  300  includes a heating and cooling plate  302  that is thermally coupled to a plasma processing chamber  304 . The plasma processing chamber  304  has a wafer holding mechanism  306  to support a wafer  308  (i.e., substrate) during fabrication. As an example, the wafer holding mechanism  306  can be an electrostatic chuck (ESC). The surface of the wafer  308  is etched by an appropriate plasma processing source gas that is released into the wafer processing chamber  304 . The plasma processing source gas can be released by a variety of mechanisms, including a showerhead or a gas distribution plate. A vacuum plate  310  maintains a sealed contact with walls  312  of the plasma processing chamber  304 . Coils  314  provided on the vacuum plate  310  are coupled to a radio frequency (RF) power source (not shown) and used to strike (ignite) a plasma from the plasma processing source gas released into the plasma processing chamber  304 . The wafer holding mechanism  306  is also often RF powered during the etch processes using a RF power supply (not shown). A pump  316  is also included to draw the process gases and gaseous products from the plasma processing chamber  304  through a duct  316 .  
     [0044] The heating and cooling plate  302  operates to control the temperature of the vacuum plate  310  of the plasma processing apparatus  300  such that the inner surface of the vacuum plate  310 , which is exposed to the plasma during operation, is maintained at a controlled temperature. The heating and cooling plate  302  is formed by several different layers of material to provide both heating and cooling operations. More particularly, the heating and cooling plate  302  includes a thermal gasket  320  that couples directly against the vacuum plate  310 . The thermal gasket  320  is a soft material that provides a conformal thermal interface with respect to the outer surface of the vacuum plate  310 . The heating and cooling plate  302  also includes a heater block  322  that is provided over the thermal gasket  320 . The heater block  322  includes resistive elements that heat the heater block  322  when they are supplied with electrical current. A thermal break  324  is provided over the heater block  322 . The thermal break  324  provides a thermal separation zone between a hot and cold surface. Over the thermal break  324  is a cooling block  326 . The cooling block  326  includes a plurality of cooling elements that serve to cool the cooling block  326 . Accordingly, the heating and cooling plate  302  can be viewed as a sandwich structure including the thermal gasket  320 , the heater block  322 , the thermal break  324 , and the cooling block  326 . Accordingly, the temperature of the vacuum plate  310  can be controlled through the activation of either the heater elements of the heater block  322  or the cooling elements of the cooling block  326 .  
     [0045]FIG. 4 is a cross-sectional diagram of a plasma processing apparatus  400  according to another embodiment of the invention. The plasma processing apparatus  400  is similar to the plasma processing apparatus  300  illustrated in FIG. 3. The plasma processing apparatus  400  includes a heating and cooling plate  402  that couples against the vacuum plate  310 . The heating and cooling plate  402  is similar to the heating and cooling plate  302  illustrated in FIG. 3 in that is includes a sandwich structure including the thermal gasket  320 , the heating block  322 , the thermal break  324 , and the cooling block  326 . In addition, the heating and cooling plate  402  includes notches  404  in the heater block  322  and notches  406  in the cooling block  326 . Given that the heating and cooling plate  402  is located proximate to the RF coils  314  that serve to activate the plasma within the plasma processing chamber  402 , a large amount of radio frequency (RF) energy can surround the RF coils  314 . As a result, the notches  404  and  406  provided in the heater block  322  and the cooler block  326 , respectively, serve to substantially prevent coupling of the RF energy from the RF coils  314  to either or both the heater block  322  or the cooler block  326 . More particularly, the RF coils  314  can induce circulating currents in the heater block  322  or the cooler block  326  if a conductive loop encircling the RF coils  314  is provided to facilitate the coupling of the electromagnetic energy. In addition, eddy currents that do not encircle the RF coils  314  can also couple energy depending on their area and proximity to the RF coils  314 . However, the notches (or slots) provided in the heater block  322  and the cooler block  326  serve to avoid the presence of conductive loops that would serve to receive coupled energy from the RF coils  314  and to reduce the area for eddy currents. As such, the notches  404  and  406  prevent the RF energy from coupling into the heating and cooling plate  402 . Potentially, the RF energy, if it were allowed to couple to the heating and cooling plate  402 , would serve to damage the heating and cooling plate  402 , interfere with the temperature control, reduce the power available to generate plasma and/or require other costly measures to be taken to minimize the RF coupling.  
     [0046]FIG. 5 is a top view of the cooling block  326  provided on the vacuum plate  310  as provided by the plasma operating apparatus  400  illustrated in FIG. 4 according to one embodiment. The cooling block  326  includes cooling elements that are provided by a cooling tube that circulates through the cooling block  326 . In FIG. 5, the cooling tube has an inlet  500  and an outlet  502  for the cooling liquid. In this embodiment, the cooling liquid can be water (i.e., H 2 O) which is a safe and inexpensive liquid, but other fluids could also be used. The cooling elements are thus provided by the single cooling tube that circulates through the cooling block  326 . As illustrated in FIG. 5, a single cooling tube can be utilized to provide the cooling elements. In other words, in this embodiment, different portions of a cooling tube provided within the cooling block  326  can implement the cooling elements.  
     [0047] In addition, the cooling block  326  also includes cuts  504  and  506  that implement the notches  404  and  406  illustrated in FIG. 4. The patterning of the cuts  504  and  506  serves to prevent conductive loops in the cooling block  326  that would serve to receive RF energy from the coils  314 . In other words, the cuts  504  and  506  are formed in the cooling block  326  to prevent, or at least substantially reduce, any coupling of RF energy into the cooling block  326  of the heating and cooling plate  302 .  
     [0048] While FIG. 5 illustrates a particular pattern for the cooling elements and the cuts  504  and  506  of the cooling block  326 , those skilled in the art will recognize that alternative cooling elements and notches can be utilized. For example, the cooling element could be provided by multiple flow paths instead of a single inlet and outlet for a cooling liquid. Further, the cooling elements and notches (cuts) could be arranged differently to achieve a similar effect by using radial patterns.  
     [0049] While FIG. 5 depicts the cooling plate  326  having the cuts  504  and  506  to substantially reduce any RF coupling from the coils  314 , the heating plate  322  can similarly be patterned with cuts to prevent conductive loops in the heating block  322  that would serve to receive RF energy from the coils  314 . Further, in one embodiment, the cuts in the heating block  322  are patterned the same and positioned over the cuts  504  and  506  of the cooling plate  326 , though separated by the thermal break  324 .  
     [0050] Moreover, although FIGS.  3 - 5  do not illustrate the providing of heating or cooling components on the vacuum plate  310  internal to the RF coils  314 , it should be noted that a smaller heating and cooling plate could be provided internal to the RF coils to provide additional heating and cooling. Such a heating and cooling plate could be arranged and utilized in a similar manner as the heating and cooling plate  302 ,  402 .  
     [0051]FIG. 6 illustrates a cross-sectional diagram of a plasma processing apparatus  600  according to another embodiment of the invention. The plasma processing apparatus  600  is similar to the plasma processing apparatus  300  illustrated in FIGS.  3  or the plasma processing apparatus  400  illustrated in FIG. 4. However, in addition, the plasma processing apparatus  600  includes a cover plate  602  that is provided over the cooling block  326  of the heating and cooling block  302 ,  402 . The cover plate  602  is, for example, made of nylon.  
     [0052] In addition, a support plate  604  having a rigid position can be used to hold the heating and cooling plate  302 ,  402  in proper position against the vacuum plate  310 , yet allow the heating and cooling plate  302 , 402  to be removed for maintenance or reconfiguration of the plasma process apparatus  600 . The plasma processing apparatus  600  includes pins  606  and  608  that guide springs  610  and  612  with respect to the support plate  604 . The springs  610  and  612  serve to press against the cover plate  602  to bias the heating and cooling plate  302 ,  402  against the outer surface of the vacuum plate  310 . Hence, the support plate  604 , the pins  606  and  608 , and the springs  610  and  612  cooperate to hold the heating and cooling plate  302 ,  402  in good thermal contact with the outer surface of the vacuum plate  310 . Further, the heating and cooling plate  302 ,  402  can be removed from the vacuum plate  310  with minimal effort by retracting the pins  606  and  608  and withdrawing the heating and cooling plate  302 , 402 . The easy removeability of the heating and cooling plate  302 ,  402  allow rapid repair, maintenance or reconfiguration and yet allow reassembly for consistent positional and thermal contact.  
     [0053]FIG. 7 is a cross-sectional diagram of a plasma processing apparatus  700  according to yet another embodiment of the invention. The plasma processing apparatus  700  is similar to the plasma processing apparatus  300  illustrated in FIG. 3, but further includes a plurality of side-wall heating and cooling units. In FIG. 7, two of a plurality of side-wall heating and cooling units  702  and  704  are illustrated. Typically, the heating and cooling units will be provided around the periphery of the processing chamber in a uniform manner such as described below with respect to FIG. 9.  
     [0054] The side-wall heating and cooling unit  702  includes a thermal gasket  706 , a heater block  708 , a thermal break  710 , and a cooling block  712 . Similarly, the side-wall heating and cooling unit  704  includes a thermal gasket  714 , a heater block  718 , a thermal break  720 , and a cooling block  722 . Accordingly, the heating and cooling units  702  and  704  have an arrangement similar to the heating and cooling block  200  illustrated in FIG. 2A. The heating and cooling elements  702  and  704  thermally couple against an outer surface of the side walls of the plasma processing chamber  304 . The heating and cooling blocks  702  and  704  are controlled to either heat or cool the side walls of the plasma processing chamber  304 , thereby controlling the temperature of the inner surface of the side walls of the plasma processing chamber  304 .  
     [0055] Although FIG. 7 illustrates the heating and cooling plate  302  provided on the vacuum plate  310 , it should be understood that the heating and cooling plate  302  is optional in this embodiment and that the plasma processing apparatus  700  may operate to provide the plurality of heating and cooling units coupled to the side walls of the plasma processing chamber  304  and may or may not include the heating and cooling plate  302  coupled to the vacuum plate  310 . Nevertheless, if the heating and cooling plate  302  is provided with the plasma processing apparatus  700 , the heating and cooling plate  302  can also include notches  404  and  406  or the support plate  604 , the pins  606  and  608  and the springs  610  and  612  (see FIGS. 4 and 6).  
     [0056] While the heating and cooling unit  702  and  704  are generally designed in accordance with the heating and cooling block  200  illustrated in FIG. 2A, FIG. 8A illustrates a particular embodiment for the side-wall heating and cooling units  702  and  704 .  
     [0057]FIG. 8A illustrates a portion of side wall heating and cooling system  800  from a top view. The heating and cooling system  800  acts to heat or cool an outer surface and, thus the inner surface, of a wall  802  of a plasma processing chamber. In this example, the plasma processing chamber has a circular design and thus the exemplary portion of the wall  802  is shown in FIG. 8A as having a curvature. FIG. 8A also illustrates two heating and cooling units thermally coupled to the exemplary portion of the wall  802 . Each of the heating and cooling units is shown in FIG. 8A from a top, cross-sectional view. The heating and cooling units include a thermal gasket  804  that provides a thin conformal thermal interface. The thermal gasket thus provides good thermal coupling between the heating and cooling units and the outer surface of the wall  802 . The heating and cooling units also include a heater block  806 . Each of the heater blocks  806  includes a resistive element  807  that serves to heat the heater block  806  when a current is directed through the resistive element  807 . The heating and cooling units also include a pair of cooling regions  808  and  810 . These cooling regions respectively include cooling elements  809  and  811 . As an example, the cooling elements  809  and  811  can pertain to a tube through which a cooled liquid flows. The heating and cooling units also include a thermal break  812  between the cooling region  808  and the heating block  806 , and a thermal break  814  between the cooling region  810  and the heating block  806 . The thermal breaks  812  and  814  provide a region through which the temperature differences between the cooling region  808  and  810  and the heating block  806  can be provided with a thermal gradient.  
     [0058] While the wall  802  in FIG. 8A is shown as a single piece, FIG. 8B shows another embodiment where the wall is a sandwich construction  802   d.  The inner wall element  802   a  can be made of particular material as suited to the application of the plasma processing chamber. The outer wall element  802   b  can be any suitable material with physical properties to function as the inner wall support. The outer wall  802   a  and the bonding material  802   c  joining the two wall elements  802   a  and  802   b  must have reasonable thermal conductivities to allow the temperature control of the inner surface of the inner wall element  802   a  with the heating and cooling system  800  shown in FIG. 8. The bonding material  802   c  thickness and composition may be varied to accommodate thermal control performance desired, compensation of mismatches in thermal coefficients of expansion between inner and outer wall materials  802   b,    802   a.  The bonding material  802   c  thickness and composition may also be varied change the electrical conductivity between the inner and outer wall elements thus allowing an electrically floating inner wall if desired while still controlling the temperature. This construction has a number of other advantages in some situations. The material of the inner wall  802   a  may be chosen with less concern for the structural requirements of the wall  802  thus allowing expanded choices for the chemical or electrical properties of the material facing the inner volume of the plasma processing chamber. In addition, this allows choices of materials that may not be available in sizes or shapes desired for the wall, but where the material facing the inner volume of the reactor is important. This tiling of inner wall material can be achieved by appropriate shaping of the tiles and placement as shown by a possible joint  802   e  in FIG. 8B.  
     [0059] The heating and cooling units utilized for the side walls of the plasma processing chamber as shown in FIGS. 7 and 8 do not need to include the notches or slots that were provided in the heating and cooling plate  302 , such as illustrated in FIG. 4, because the heating and cooling units utilized for the side walls of the plasma processing chamber do not receive any significant RF coupling from the coils on the vacuum plate that ignite the plasma.  
     [0060]FIG. 9 is a top view of a cross-section of a plasma processing chamber  900  according to one embodiment of the invention. The plasma processing chamber  900  illustrates a chamber wall  902  and an outer container wall  904 . A series of heating and cooling blocks  906  are thermally coupled to the outer surface of the chamber wall  902 . As shown in FIG. 9, the heating and cooling blocks  906  can be equidistantly spaced around the periphery of the chamber wall  902 . In this embodiment, there are sixteen (16) heating and cooling blocks  906  that are provided to control the temperature of the chamber wall  902 . However, it should be recognized that a different number of heating and cooling blocks could easily be provided, particularly if thermal conductivity of the chamber wall  902  is alter significantly or the surface area of the heating and cooling blocks was enlarged. The chamber wall  902  could also be a sandwich or tiled wall construction as shown in FIG. 8B. Further, each of the heating and cooling blocks  906  is biased against the outer surface of the chamber wall  902  by a spring biased pin  908 . The spring biased pins  908  are spring biased against to the outer container wall  904  to force the heater blocks  906  against the outer surface of the chamber wall  902 . The spring biasing not only improves thermal coupling and repeatability, but also provides easy removability which simplifies repair, maintenance or reconfiguration.  
     [0061]FIG. 10 illustrates a cross-sectional side view of a portion of a plasma processing chamber  1000  in which a chamber wall  1002  and an outer container wall  1004  are provided. As an example, the chamber wall  1002  and the outer container wall  1004  can be provided similar to the chamber wall  902  and the outer container wall  904  illustrated in FIG. 9. Here, the plasma processing chamber  1000  includes a pair of vertically positioned heating and cooling blocks, namely, heating and cooling blocks  1006  and  1008 . Spring biased pins  1010  and  1012  respectively bias, or force, the heating and cooling blocks  1006  and  1008  against the chamber wall  1002 . The spring biased pins  1010  and  1012  act against the outer container wall  1004 . In addition, the spring biased pins  1010  and  1012  are coupled to a handle  1018 . The handle  1018  allows a technician to easily remove the heating and cooling blocks  1006  and  1008  away from the chamber wall  1002  for maintenance, repair, replacement or other operations to the chamber wall  1002  or the heating and cooling blocks  1006  and  1008  themselves. By pulling back the handle  1018  (away from the outer container wall  1004 ), the spring biased pins  1010  and  1012  retracted so that the heating and cooling blocks  1006  and  1008  no longer press against the chamber wall  1002  and allow the parts to move relative to each other without scraping for easy removal or service  
     [0062]FIG. 11 is a cross-sectional diagram of a plasma processing apparatus  1100  according to still another embodiment of the invention. The plasma processing apparatus  1100  is similar to the plasma processing apparatus illustrated in FIG. 3 in that it includes the heating and cooling plate  302 . However, the plasma processing apparatus  1100  includes additional components for cooling other areas of the plasma processing apparatus  1100 . In particular, the plasma processing apparatus  1100  includes a cover plate  1102  that is provided over the cooling block  310  of the heating and cooling plate  302 . The plasma processing apparatus  1100  also includes a support plate  1104  that has a fixed rigid position with respect to the plasma processing chamber  304 . Pins  1106  and  1108  are provided through the support plate  1104  toward the cover plate  1102 . Springs  1110  and  1112  are respectively provided with the pins  1106  and  1108  to bias the heating and cooling plate  302  against the outer surface of the vacuum plate  310 . In other words, the springs  1110  and  1112  are used to provide a force from the support plate  1104  towards the cover plate  1102  to force the heating and cooling plate  302  against the vacuum plate  310 . Still further, the support plate  1104  may also support DC coils  1114  and  1116 . The weight of the DC coils may be sufficient to apply enough force to dispense with the pin  1106 ,  1108  and spring  1110 ,  1112  arrangements if the support plate  1104  and cover plate  1102  are in contact. The DC coils  11   14  and  1116  can be used to alter the plasma distribution within the plasma processing chamber  304  through use of magnetic fields. Additional details on the operation of DC coils and their use with respect to plasma processing apparatus are described in U.S. Application No. ____________ (Attorney Docket No. LAM1P122), filed concurrently herewith, and entitled IMPROVED PLASMA PROCESSING SYSTEMS AND METHODS THEREFOR, which is hereby incorporated by reference. Further, to cool the DC coils or the support plate  1104  that supports the DC coils  1114  and  1116 , the support plate  1104  includes cooling elements  1118  and  1120  that cool the support plate  1104 . In one implementation, the cooling elements  1118  and  1120  can be provided by a tube (channel) through which a cooling liquid flows. In this manner, the temperature at which the DC coils  1114  and  1116  operate can be cooled so that they do not overheat during operation and/or so that their temperature can be generally controlled to provide for more uniform operation. In one implementation, for better cooling of the DC coils  1114  and  1116 , the cooling elements  1118  and  1120  can be provided directly under the DC coils  1114  and  1116 . If the weight of the DC coils  1116 ,  1114  and support plate  1104  is used to press the heating and cooling plate  302  (temperature control sandwich assembly) against the vacuum plate  310  (temperature controlled surface), it is envisioned that it may be possible to thermally and mechanically substitute the cooled support plate  1104  with cooling elements  1118  and  1120  for the cooling block  310  and cover plate  1102 .  
     [0063] The cooling blocks can utilize cooling tubes through which regular water flows to cool the associated surfaces. In one implementation, the temperature of the cooling water is fixed at about 15-20 degrees Celsius and the rate of flow is controlled to increase or decrease the cooling rate by the cooling block.  
     [0064] The thermal break is generally formed of rubber such as silicone rubber. The temperature coefficient for the thermal barrier can be generally in the range of 0.1-2 Watts/m K, and more particularly about 1 Watts/m K. The thermal gasket can also be formed of rubber, such as metal-loaded silicone rubber. However, the thermal gasket is designed to have a higher thermal conductivity (e.g., 4 Watts/m K) so that the heating and cooling plate is better thermally coupled to the surface of the vacuum plate. In this regard, the rubber used for the thermal gasket can be silver loaded to increase its thermal conductivity. The temperature sensors can be provided in numerous places. In one embodiment the temperature sensor is coupled to the outer surface of the vacuum plate for use by the heating and cooling plate, and coupled to the side walls at suitable positions to monitor the temperature for use by the heating and cooling elements.  
     [0065] The present invention is able to control the temperature of the plasma processing chamber on the order of +/−5° Celsius during operation of the plasma processing apparatus. The invention can also provide for smooth spatial temperature distribution about the present processing chamber for use of the appropriately positioned heating and cooling elements.  
     [0066] The plasma processing chamber can be silicon carbide (SiC) which has a good thermal conductivity (e.g., &gt;200 Watts/m K) but is more difficult to heat and cool than metal liners because of thermal expansion issues. The invention is particularly suited to provide temperature control to plasma processing chambers made of silicon carbide. The invention not only supplies the cooling but also supplies heating as needed. The heating and cooling of the plasma processing chamber is beneficially provided from the outside of the plasma processing chamber.  
     [0067] The advantages of the invention are numerous. Different embodiments or implementations may yield one or more of the following advantages. One advantage of the invention is that the invention allows temperature of plasma processing devices to be controlled with substantially increased accuracy and precision. Another advantage of the invention is that both heating and cooling are provided through a common thermal interface. Still another advantage of the invention is that by using a common thermal interface, not only can both cooling and heating be provided, but the resulting temperature profile of the surface being temperature controlled is uniform and smooth. Yet another advantage of the invention is that it is non-invasive and easily removable.  
     [0068] Although only a few embodiments of the present invention have been described in detail, it should be understood that the present invention may be embodied in many other specific forms without departing from the spirit or scope of the invention. Therefore, the present examples are to be considered as illustrative and not restrictive, and the invention is not to be limited to the details given herein, but may be modified within the scope of the appended claims.