Patent Publication Number: US-2010116788-A1

Title: Substrate temperature control by using liquid controlled multizone substrate support

Description:
BACKGROUND 
     Plasma processing apparatuses are used to process substrates by techniques including etching, physical vapor deposition (PVD), chemical vapor deposition (CVD), ion implantation, and resist removal. One type of plasma processing apparatus used in plasma processing includes a reaction chamber containing top and bottom electrodes. An electric field is established between the electrodes to excite a process gas into the plasma state to process substrates in the reaction chamber. Due to shrinking feature sizes and the implementation of new materials, improvement in plasma processing apparatuses to control the conditions of the plasma processing is required. 
     SUMMARY 
     In one embodiment, a substrate support useful in a reaction chamber of a plasma processing apparatus is provided. The substrate support comprises a base member and a heat transfer member overlying the base member. The heat transfer member has multiple zones including at least a first zone with a first flow passage therein and a second zone with a second flow passage therein through which a liquid can be circulated to individually heat and cool the first and second zones of the heat transfer member. An electrostatic chuck overlies the heat transfer member. The electrostatic chuck has a support surface for supporting a substrate in a reaction chamber of the plasma processing apparatus. A source of cold liquid and a source of hot liquid are in fluid communication with the first and second flow passages. A valve arrangement is operable to independently control temperature of the liquid in the first and second zones by adjusting a mixing ratio of the hot liquid to the cold liquid circulating in the first and second flow passages. A controller controls the valve arrangement to independently control the temperature in the first and second zones by adjusting the mixing ratio of the hot liquid to the cold liquid in the first and second flow passages. 
     In another embodiment, a method of controlling a temperature of a semiconductor substrate during plasma processing is provided. The substrate is supported on the substrate support, described above, and in thermal contact with the multiple zones. In the method, liquid flows through the first and second flow passages, a temperature of the first zone is measured, and the temperature of the liquid flowing through the first flow passage is: (a) increased if the temperature of the first zone is below a target temperature by increasing the mixing ratio of the hot liquid to the cold liquid; or (b) decreased if the temperature of the first zone is above the target temperature by decreasing the mixing ratio of the hot liquid to the cold liquid. Likewise, a temperature of the second zone is measured and the temperature of the liquid flowing through the second flow passage is: (a) increased if the temperature of the second zone is below a target temperature by increasing the mixing ratio of the hot liquid to the cold liquid; or (b) decreased if the temperature of the second zone is above the target temperature by decreasing the mixing ratio of the hot liquid to the cold liquid. Preferably, an azimuthal temperature difference within each zone is less than 5° C. 
     In another embodiment, a substrate support useful in a reaction chamber of a plasma processing apparatus is provided. The substrate support comprises a base member and a heat transfer member overlying the base member. The heat transfer member has a first zone with a first flow passage and a second zone with a second flow passage. The flow passages are adapted to circulate a liquid to individually heat and cool each zone of the heat transfer member. A first common line is in fluid communication with the first flow passage and a second common line is in fluid communication with the second flow passage. A first valve is in fluid communication with the first common line and a first supply line from a hot liquid source. The first valve is operable to control an amount of flow of a hot liquid from the hot liquid source through the first common line. A second valve is in fluid communication with the first common line and a second supply line from a cold liquid source. The second valve is operable to control an amount of flow of a cold liquid from the cold liquid source through the first common line. A third valve is in fluid communication with the second common line and the first supply line from the hot liquid source. The third valve is operable to control an amount of flow of the hot liquid through the second common line. A fourth valve is in fluid communication with the second common line and the second supply line from the cold liquid source. The fourth valve is operable to control an amount of flow of the cold liquid through the second common line. A controller is operable to independently control the first valve and the second valve to adjust a first mixing ratio of the hot liquid to the cold liquid to the first flow passage; and the third valve and the fourth valve to adjust a second mixing ratio of the hot liquid to the cold liquid to the second flow passage. An electrostatic chuck overlies the heat transfer member. The electrostatic chuck has a support surface for supporting a substrate in a reaction chamber of the plasma processing apparatus. 
     In another embodiment, a substrate support useful in a reaction chamber of a plasma processing apparatus is provided. The substrate support comprises a base member and a heat transfer member overlying the base member. The heat transfer member has a first zone with a first flow passage therein and a second zone with a second flow passage therein. The flow passages are adapted to circulate a liquid to individually heat and cool each zone of the heat transfer member. A supply line is in fluid communication with the first flow passage and a liquid source. A first heating element is along the supply line. The first heating element is adapted to heat the liquid flowing from the liquid source to a first temperature before the liquid is circulated in the first flow passage. A first transfer line is in fluid communication with the first flow passage and the second flow passage. The first transfer line is adapted to flow the liquid from the first flow passage to the second flow passage. A second heating element is along the first transfer line. The second heating element is adapted to heat the liquid to a second temperature before circulating in the second flow passage. A controller controls each heating element to independently control the temperature of each zone by adjusting power to each heating element. An electrostatic chuck overlies the heat transfer member. The electrostatic chuck has a support surface for supporting a substrate in a reaction chamber of the plasma processing apparatus. 
    
    
     
       BRIEF DESCRIPTION OF FIGURES 
         FIG. 1  is a cross-sectional view of an exemplary embodiment of a plasma processing apparatus. 
         FIG. 2  is a cross-sectional view of an inductively coupled plasma processing apparatus. 
         FIG. 3  is a cross-section view of one embodiment of a substrate support. 
         FIG. 4  is a cross-section view of an additional embodiment of a substrate support including thermal barriers extending through a partial thickness of the heater transfer member. 
         FIG. 5  is a cross-section view of an additional embodiment of a substrate support with no thermal barriers. 
         FIG. 6  is a sectional plan view of the support of  FIG. 3 , taken along sectional line C-C′. 
         FIG. 7  is a partial cross-sectional view of one embodiment of a heat transfer member, including a source of cold liquid, a source of hot liquid, a valve arrangement and a controller. 
         FIG. 8A  is a partial cross-sectional view of another embodiment of a heat transfer member, including a source of cold liquid, a source of hot liquid, a valve arrangement and a controller. 
         FIG. 8B  is a partial cross-sectional view of the embodiment of the heat transfer member of  FIG. 8A , including a return line to the source of cold liquid and/or the source of hot liquid. 
         FIG. 9  is a partial cross-sectional view of another embodiment of a heat transfer member, including a source of liquid, heating elements and transfer lines. 
         FIG. 10  illustrates three exemplary center-to-edge temperature profiles of a semiconductor substrate during plasma processing. 
     
    
    
     DETAILED DESCRIPTION 
     In order to enhance the uniformity of plasma processing of a substrate in a plasma processing apparatus, it is desirable to control the temperature distribution at an exposed surface of the substrate where material deposition and/or etching occurs. In plasma etching processes, variations in the substrate temperature and/or in rates of chemical reaction at the substrate&#39;s exposed surface can cause undesirable variations in the etching rate of the substrate, as well as in etch selectivity and anisotropy. In material deposition processes, such as CVD processes, the deposition rate and the composition and properties of material deposited on the substrate can be significantly affected by the temperature of the substrate during deposition. 
       FIG. 1  illustrates an exemplary semiconductor material plasma processing apparatus  100  for etching. Plasma processing apparatus  100  comprises a reaction chamber  102  containing a substrate support  104  on which a substrate  106  is supported during plasma processing. The substrate support  104  for supporting a substrate  106  in the interior of the reaction chamber  102  can include a clamping device, preferably an electrostatic chuck, which is operable to clamp the substrate  106  on the substrate support  104  during processing. 
     The exemplary plasma process apparatus  100  shown in  FIG. 1  includes a showerhead electrode assembly having a top plate  108  forming a wall of the reaction chamber  102  and a showerhead electrode  110  attached to the top plate  108 . Gas supply  112  supplies process gas to the interior of the reaction chamber  102 , via showerhead electrode  110 . Showerhead electrode  110  includes multiple gas passages  114  extending through the thickness of the showerhead electrode  110  for injecting process gas into a space in a plasma reaction chamber  102  located between showerhead electrode  110  and the substrate support  104 . The gas supply  112  can include inner and outer supply lines feeding the center and outer zones of the showerhead electrode  110  in a dual zone gas feed arrangement. 
     The process gas flows through showerhead electrode  110  and into the interior of the reaction chamber  102 . Next, the process gas is energized into the plasma state in the plasma process apparatus  100  by a power source  116 A, such as an RF source driving showerhead electrode  110 , and/or a power source  116 B at one or more frequencies from about 0.3 to about 600 MHz (e.g., 2 MHz, 13.56 MHz, 60 MHz) driving an electrode in the substrate support  104  at one or more frequencies from about 0.3 to about 600 MHz (e.g., 2 MHz, 13.56 MHz, 60 MHz). The RF power applied to the showerhead electrode  110  can be changed to perform different process steps such as when different gas compositions are supplied into the plasma process apparatus  100 . In another embodiment, showerhead electrode  110  can be grounded. 
     In one embodiment, the plasma can be generated in the interior of plasma process apparatus  100  by supplying RF energy from two RF sources to the showerhead electrode  110  and/or the substrate support  104 , or the showerhead electrode  110  can be electrically grounded and RF energy at a single frequency or multiple frequencies can be supplied to the substrate support  104 . 
     In another embodiment, as illustrated in  FIG. 2 , inductively coupled plasma (ICP) processing apparatus  200  can be used for depositing (e.g., plasma enhanced chemical vapor deposition or PECVD) and plasma etching of materials on substrates by supplying process gas into a vacuum chamber at a low pressure (i.e., below 100 mTorr) and the application of radio-frequency (RF) energy to the gas.  FIG. 2  is a cross-sectional view of an embodiment of an ICP plasma processing apparatus  200 . An example of an ICP plasma processing chamber is the TCP® etch or deposition system, manufactured by Lam Research Corporation, Fremont, Calif. The ICP plasma processing apparatus is also described, for example, in commonly-owned U.S. Pat. No. 4,948,458, which is incorporated by reference in its entirety. Reaction chamber  202  includes a substrate support  204  for supporting the substrate  206  in the interior of the reaction chamber  202 . Dielectric window  208  forms a top wall of reaction chamber  202 . Process gases are injected to the interior of the reaction chamber  202  through a gas distribution member  210 . Examples of gas distribution member  210  include a showerhead, gas injector or other suitable arrangement. A gas supply  212  supplies process gases to the interior of reaction chamber  202  through gas distribution member  210 . 
     Once process gases are introduced into the interior of reaction chamber  202 , they are energized into a plasma state by an energy source  216  supplying energy into the interior of reaction chamber  202 . Preferably, the energy source  216  is an external planar antenna powered by an RF source  218 A and RF impedance matching circuitry  218 B to inductively couple RF energy into reaction chamber  202 . An electromagnetic field generated by the application of RF power to planar antenna energizes the process gas to form a high-density plasma P (e.g., 10 10 -10 12  ions/cm 3 ) above substrate  206 . 
     A dielectric window  208  underlies planar antenna and gas distribution member  210  is placed below dielectric window  208 . Plasma P is generated in the zone between gas distribution member  210  and substrate  206 , for either deposition or etching of substrate  206 . 
     During plasma processing of substrates, the reactive ions of the plasma gas chemically react with portions of material on a face of the semiconductor substrate (e.g., a silicon, gallium arsenide or indium phosphide wafer), resulting in temperature differences of up to 50° C. between the center and edge of the substrate. Local substrate temperature and rate of chemical reaction at each point on the substrate are interrelated such that non-uniform etching or deposition of material over a face of the substrate can result if the temperature of the substrate across its face varies too much. To alleviate this condition, backside gas cooling systems have been used in substrate supports to provide heat transfer between the substrate support and substrates supported on the substrate support. 
     Substrate supports have included coolant flow passages to remove heat from the substrate support during processing. In such cooling systems, coolant at a controlled temperature and a set volumetric flow rate is introduced into the coolant flow passages. Substrate supports have included one supply line and one return line in the cooling system. However, it has been determined that as heat is removed from the substrate support, a significant temperature gradient can develop along the length of the passages, from the inlet to the outlet. As a result, the temperature uniformity at the surface of the substrate support in contact with the heat transfer gas and the substrate is not controlled. Substrate holders also provide a heat sink at the back side of the substrate. Resulting heat transfer from the substrate to the substrate holder has contributed to non-uniformity of temperature across the substrate in known plasma processing apparatuses. 
     The ability to vary the center-to-edge temperature profile (i.e., radial temperature profile) across a wafer or substrate by as much as 40° C., while maintaining an azimuthal (i.e., angular or circumferential) temperature uniformity ≦5° C. is essential for critical dimension uniformity control. Some plasma processing steps require radial temperature profile control for optimal processing to compensate for non-uniformity due to other factors such as etch by-product concentration variation as a function of radial position on the substrate. For example, during the etching of a stack of thin films or a multi-layer structures (e.g., gate oxide/polysilicon/silicide/hardmask/anti-reflective coating stack), the etching of one layer may require a center region hotter than an edge region, whereas the etching of another layer may require a center region colder than an edge region. Thus, a need exists for a substrate support with the ability to achieve an azimuthal temperature uniformity of ≦ 5 C, with the ability vary the center-to-edge temperature profile across a wafer or substrate by as much as 40° C. Preferably, the azimuthal temperature uniformity is ≦1° C.; and more preferably the azimuthal temperature uniformity is ≦0.5° C. 
       FIG. 3  illustrates a cross-section view of one embodiment of substrate support  300 . Substrate  326  provides the ability to more effectively control center-to-edge temperature profile, which can be step-changeable for up to 40° C. center-to-edge temperature profile while maintaining azimuthal temperature uniformity of ≦1° C. Substrate support  300  includes base member  310 , heat transfer member  320  overlying base member  310  and electrostatic chuck  322  overlying heat transfer member  320 . Electrostatic chuck  322  includes a support surface  324  for supporting substrate  326 . Such electrostatic chucks are also described, for example, in commonly-owned U.S. Pat. No. 5,838,529, which is incorporated by reference in its entirety. 
     Heat transfer member  320  is further subdivided into concentric multiple zones  328 A- 328 E. Each zone contains one or more flow passages  330 A- 330 E, through which liquid can be circulated to individually heat and cool each zone  328 A- 328 E of heat transfer member  320 . Heating of the substrate support  300  is achieved by circulating a hot liquid through flow passages  330 A- 330 E, thus eliminating the need for a heating element (e.g., resistive heater or heating tape) embedded in the heat transfer member  320 . The liquid can be water (e.g., deionized water), ethylene glycol, silicon oil, water/ethylene glycol mixtures, FLUOROINERT® refrigerant (i.e., perfluorocarbon cooling fluid, available from Minnesota Mining and Manufacturing (3M) Company), GALDEN® fluids (i.e., low molecular weight perfluoropolyether heat transfer fluid, available from Solvay Solexis) and the like. Although five zones are illustrated in  FIG. 3 , it is understood that the number of zones can be two or more, depending on the degree of temperature controlled desired. 
     In the embodiment of  FIG. 3 , heat transfer member  320  can be composed of a thermally conductive material, such as aluminum or aluminum nitride. To improve control of radial heat transfer (i.e., heat transfer between individual zones) and to achieve a desired temperature profile across a substrate, thermal barriers  332  separate each zone  328 A- 328 E. Thermal barriers  332  can either extend through an entire thickness of heat transfer member  320  (as illustrated in  FIG. 3 ) or through a partial thickness of heat transfer member  320 , as illustrated in  FIG. 4 . Thermal barriers  332  can either be unfilled (i.e., an empty space) or contain a filler material to achieve a thermal conductivity from about 0.1 W/m-K to about 4.0 W/m-K. Examples of filler materials include epoxy or silicone. Thermal conductivity of the filler material can be adjusted using additives such as boron nitride, aluminum nitride, aluminum oxide, silicon oxide, and silicon. 
     In another embodiment, as illustrated in  FIG. 5 , radial heat transfer is controlled by composing heat transfer member  320  of a thermally insulating material. Examples of thermally insulating materials include ceramics such as aluminum oxide or yttrium oxide; or metal alloys with a lower thermal conductivity, such as stainless steel. 
     As illustrated in  FIG. 3 , bonding material  334  can be inserted between heat transfer member  320  and base member  310 . Bonding material  334  can be composed of epoxy or silicone, which can be filled with one or more filler materials  334 A, as illustrated in enlarged region A. Exemplary filler materials  334 A can include aluminum oxide, boron nitride, silicon oxide, aluminum or silicon. In another embodiment, illustrated in enlarged region B, bonding material can be a metallic braze  334 B. Bonding material  334  can be selected to provide a thermal conductivity from about 0.1 W/m-K to about 4 W/m-K and have a thickness from about 1 mil to about 200 mils. 
       FIG. 6  illustrates a sectional plan view of heat transfer member  320  as a circular plate, taken across sectional line C-C′ from  FIG. 3 . From  FIG. 6 , zones  328 A- 328 E are concentrically arranged at different distances relative to the center of a circular plate and flow passages  330 A- 330 E have a spiral-like pattern. Thermal barriers  332  are annular channels separating each zone. 
       FIG. 7  illustrates a partial cross-sectional view of heat transfer member  320 , including a source of hot liquid  336  and a source of cold liquid  338 , both sources being in fluid communication with flow passages  330 A- 330 E. Zones  328 A- 328 E are separated by thermal barriers  332 . Valve arrangement  340  is operable to control the individual temperature in each zone  328 A- 328 E by adjusting a mixing ratio of hot liquid (from source of hot liquid  336 ) to cold liquid (from source of cold liquid  338 ). Controller  342  receives input signals from temperature sensors  344 A- 344 E in each zone  328 A- 328 E to independently direct valve arrangement  340  to adjust the appropriate mixing ratio of hot liquid to cold liquid. In another embodiment, temperature sensors for each zone  328 A- 328 E can be embedded in the electrostatic chuck  322 . 
     During plasma processing, substrate  326  is supported on substrate support  300 , with the substrate  326  in thermal contact with zones  328 A- 328 E. A liquid flows through flow passages  330 A- 330 E, corresponding to zones  328 A- 328 E. The temperature of each individual zone  328 A- 328 E is measured with temperature sensors  344 A- 344 E, which provide input signals to controller  342 . Controller  342  can either: (i) increase the temperature of the liquid flowing through each individual flow passage  330 A- 330 E if the temperature of a zone  328 A- 328 E is below a target temperature by increasing the mixing ratio of hot liquid to cold liquid; or (ii) decrease the temperature of the liquid flowing through each individual flow passage  330 A- 330 E if the temperature of a zone  328 A- 328 E is above a target temperature by decreasing the mixing ratio of hot liquid to cold liquid. During plasma processing, substrate support  300  with heat transfer member  320  and controller  342  provides the ability to independently and dynamically change temperatures of zones  328 A- 328 E during a plasma processing of a single wafer. 
       FIG. 8A  illustrates a partial cross-sectional view for another embodiment of heat transfer member  420 , including zones  428 A- 428 E, each zone having respective flow passage  430 A- 430 E and temperature sensor  444 A- 444 E. Zones  428 A- 428 E are separated by thermal barriers  432 . A source of hot liquid  436  and a source of cold liquid  438  are in fluid communication with flow passages  430 A- 430 E, via common lines  450 A- 450 E, valves  452 A- 452 E′, first supply line  454  and second supply line  456 . First through fifth valves  452 A- 452 E are in fluid communication with common lines  450 A- 450 E and first supply line  454 , which supplies hot liquid from hot liquid source  436 . Additionally, sixth through tenth valves  452 A′- 452 E′ are also in fluid communication with common lines  450 A- 450 E and second supply line  456 , which supplies cold liquid from cold liquid source  438 . 
     Controller  442  receives input signals from temperature sensors  444 A- 444 E to independently control valves  452 A- 452 E and  452 A′- 452 E′ for individually adjusting a mixing ratio of hot liquid flowing from hot liquid source  436  to cold liquid flowing from cold liquid source  438  in each flow passage. For example, controller  442  can control: (i) first valve  452 A and second valve  452 A′ to adjust a first mixing ratio of hot liquid to cold liquid flowing through common line  450 A to flow passage  430 A; (ii) third valve  452 B and fourth valve  452 B′ to adjust a second mixing ratio of hot liquid to cold liquid flowing through common line  450 B to flow passage  430 B; (iii) fifth valve  452 C and sixth valve  452 C′ to adjust a third mixing ratio of hot liquid to cold liquid flowing through common line  450 C to flow passage  430 C; (iv) seventh valve  452 D and eighth valve  452 D′ to adjust a fourth mixing ratio of hot liquid to cold liquid flowing through common line  450 D to flow passage  430 D; and (v) ninth valve  452 E and tenth valve  452 E′ to adjust a fifth mixing ratio of hot liquid to cold liquid flowing through common line  450 E to flow passage  430 E. 
     The  FIG. 8A  embodiment provides the ability to monotonically (i.e., successive increasing or decreasing in temperature) or non-monotonically increase or decrease temperature along a radius of substrate  426  during plasma processing, by controlling the temperature of each individual zone  428 A- 428 E. For example, the temperature in each individual zone  428 A- 428 E can be set such that the radial temperature profile is parabolic or inverse parabolic (i.e. monotonic). However, because the temperature in each zone  428 A- 428 E can be individually controlled, in another example, the radial temperature profile can also be set such that the radial temperature profile is sinusoidal (i.e. non-monotonic). 
     As illustrated in  FIG. 8B , flow passages  430 A- 430 E are in fluid communication with return line  446 , which is in fluid communication with source of hot liquid  436  and/or source of cold liquid  438 . The liquid exiting flow passages  430 A- 430 E can thus be recycled by returning the liquid to the source of hot liquid  436  and/or source of cold liquid  438 . 
     The source of hot liquid  436  maintains the hot liquid at a temperature from about 40° C. to about 150° C.; the source of cold liquid  438  can maintain the cold liquid at a temperature from about −10° C. to about 70° C. Thus, the embodiment of  FIGS. 8A and 8B  has the capability of achieving five different temperatures in each zone  428 A- 428 E, depending upon a desired center-to-edge temperature profile during plasma processing. Although five zones are illustrated in  FIGS. 8A and 8B , it is understood that the number of zones can be two or more, depending on the degree of radial temperature profile control desired. In one example, the source of cold liquid maintains the cold liquid at a temperature ≧−10° C.; and the source of hot liquid maintains the hot liquid at a temperature ≦150° C., with the hot liquid temperature being greater than the cold liquid temperature. 
       FIG. 9  illustrates a partial cross-sectional view for another embodiment of heat transfer member  520 , including zones  528 A- 528 E, each zone having respective flow passages  530 A- 530 E and temperature sensors  544 A- 544 E. Zones  528 A- 528 E are separated by thermal barriers  532 . A source of liquid  536  is in fluid communication with supply line  550 , first through fourth transfer lines  552 A- 552 D and return line  554 . First heating element  538 A is positioned along supply line  550 ; and second through fifth heating elements  538 B- 538 E are positioned along first through fourth transfer lines  552 A- 552 D. First through fifth heating elements  538 A- 538 E control the temperature of the liquid flowing through supply line  550  and first through fourth transfer lines  552 A- 552 D. 
     Controller  542  receives input signals from temperature sensors  544 A- 554 E to independently control heating elements  538 A- 538 E. If a temperature measured by temperature sensors  544 A- 544 E is below a target temperature, controller  542  activates one or more of the appropriate heating elements  538 A- 538 E. First heating element  538 A heats liquid flowing from liquid source  536  to a first temperature before the liquid is circulated in first flow passage  530 A. First transfer line  552 A flows liquid from first flow passage  530 A to second flow passage  530 B; and second heating element  538 B heats liquid flowing along the first transfer line  552 A to a second temperature before circulating in the second flow passage  530 B. Second transfer line  552 B flows liquid from second flow passage  530 B to third flow passage  530 C; and third heating element  538 C heats liquid flowing along the second transfer line  552 B to a third temperature before circulating in the third flow passage  530 C. Third transfer line  552 C flows liquid from third flow passage  530 C to fourth flow passage  530 D; and fourth heating element  538 D heats liquid flowing along the third transfer line  552 C to a fourth temperature before circulating in the fourth flow passage  530 D. Fourth transfer line  552 D flows liquid from fourth flow passage  530 D to fifth flow passage  530 E; and fifth heating element  538 E heats liquid flowing along the fourth transfer line  552 D to a fifth temperature before circulating in the fifth flow passage  530 E. Liquid exiting fifth flow passage is returned to the liquid source  536  along return line  554 . 
     Liquid flowing through first through fourth transfer lines  552 A- 552 D can either flow in a forward direction (as indicated by the arrows in  FIG. 9 ) or a reverse direction (not indicated in  FIG. 9 ). During liquid flow in the forward direction, the first temperature is less than the second temperature, which is less than the third temperature, which is less than the fourth temperature, resulting the highest temperature in zone  528 E (i.e., center region). Likewise, during liquid flow in the reverse direction, the first temperature is greater than the second temperature, which is greater than the third temperature, which is greater than the fourth temperature, resulting the highest temperature in zone  528 A (i.e., edge region). 
     The  FIG. 9  embodiment provides the ability to monotonically increase or decrease temperature along a radius of substrate  326  during plasma processing. For example, the temperature in each individual zone  528 A- 528 E can be set such that the radial temperature profile is parabolic or inverse parabolic (i.e. monotonic). 
     During plasma processing (e.g., plasma etching of semiconductors, metals or dielectrics; or deposition of conductive or dielectric materials) substrate support  300  with heat transfer member  320 / 420 / 520  has the ability to vary the center-to-edge radial temperature profile by up to 40° C., while maintaining an azimuthal temperature uniformity of ≦1° C., more preferably ≦0.5° C. Furthermore, such heat transfer members  320 / 420 / 520  provide the ability for either: (1) uniform temperature distribution; or (2) radially varying temperature distribution (e.g., hot edge or hot center), both of which are useful for step-changeable temperature control during plasma processing, to enable optimal multi-layer processing.  FIG. 10  illustrates radial temperature as a function of radial position on a wafer with radius R for three exemplary center-to-edge temperature profiles during plasma processing with heat transfer members  320 / 420 / 520 : (A) a center region hotter than an edge region; (B) a center region colder than an edge region; and (C) uniform temperature distribution completely across the wafer. 
     While the invention has been described in detail with reference to specific embodiments thereof, it will be apparent to those skilled in the art that various changes and modifications can be made, and equivalents employed, without departing from the scope of the appended claims.