JP5183058B2 - Substrate processing with rapid temperature gradient control - Google Patents

Description

background

  Embodiments of the invention relate to processing a substrate with rapid temperature gradient control across the substrate.

  In processing substrates such as semiconductors and displays, electrostatic chucks are used to process the layers on the substrate while holding the substrate in the chamber. A typical electrostatic chuck comprises an electrode covered by a ceramic. When the electrode is charged, static electricity accumulates on the electrode and the substrate, and the resulting electrostatic force holds the substrate to the chuck. Typically, the temperature of the substrate is controlled by maintaining a helium gas under the substrate to increase the heat transfer rate across the microscopic gap at the interface between the back side of the substrate and the chuck surface. The electrostatic chuck can be supported by a base having a channel through which fluid passes to cool or heat the chuck. When the substrate is securely held in the chuck, process gas is introduced into the chamber and a plasma is formed to process the substrate. The substrate can be processed by CVD, PVD, etching, implant, oxidation, nitridation or other such processes.

  In such conventional substrate fabrication processes, the substrate is maintained at a single temperature during processing. Typically, the substrate is passed through a chamber slit by a wafer blade and deposited on lift pins that extend through the body of the electrostatic chuck. The lift pins are then retracted from the chuck to deposit the substrate on the surface of the chuck. The substrate is abruptly raised in temperature to a preset temperature that is maintained constant by plasma formed in the chuck heater or chamber. The substrate temperature can be further controlled by the temperature and flow rate of the coolant passed through the base channel or below the chuck used to remove heat from the chuck.

  Conventional processing chambers are suitable for maintaining the substrate at a constant single temperature during processing, but do not allow rapid changes in the temperature of the substrate during a single process cycle. In some processes, it is desirable to rapidly increase or decrease the substrate temperature to achieve a specific temperature profile during the process. For example, it may be desirable to allow the etching of different materials on a substrate at different substrate temperatures by having a rapid change in substrate temperature at different stages of the etching process. At these different etching stages, the process gas provided to the chamber can also change composition or have the same composition. As another example, in an etching process, such a temperature profile can be obtained by depositing a sidewall polymer on the sidewalls of the features etched on the substrate, and later increasing the temperature of the etching process in the same etching process. It may be useful to remove, and vice versa. Similarly, in a deposition process, for example, a nucleation layer is first deposited on a substrate and then a first processing temperature that is higher or lower than a second processing temperature to grow a thermal deposition layer on the substrate. Sometimes it is desirable. Conventional substrate processing chambers and their internal components often do not allow a significantly rapid rise and fall in substrate temperature.

  This becomes even more complex when the substrate is subjected to radial non-uniform process conditions across the substrate that result in non-uniform concentric processing bands during processing. Non-uniform processing conditions can arise from the distribution of gas and plasma species in the chamber, which often varies depending on the inertness of the chamber and the location of the exhaust gas port. Mass transfer mechanisms can also change the rate of arrival and dissipation of gas species in different regions of the substrate surface. It can occur as a result of non-uniform processing or non-uniform thermal loading of the chamber, for example caused by non-uniform coupling of energy from the plasma sheath to the substrate or by radiant heat reflected from the chamber walls. Processing bands and other variations across the substrate are undesirable when electronic devices fabricated in different areas of the substrate, eg, the peripheral and central substrate areas, have different characteristics. Accordingly, it is desirable to reduce changes in processing rate and other process characteristics across the substrate surface during substrate processing.

  Accordingly, it is desirable to have a process chamber and components that allow rapid temperature rise and fall of substrates processed in the chamber. It is further desirable to control the temperature of different regions of the processing surface of the substrate to reduce the effects of non-uniform processing conditions in the radial direction across the substrate surface. It is also desirable to control the temperature profile of the entire substrate during processing.

  These features, aspects and advantages of the present invention will become better understood with regard to the following description, appended claims, and accompanying drawings which illustrate examples of the present invention. However, it should be understood that each of the features can generally be used with the present invention, not just in connection with a particular drawing, and the present invention includes combinations of these features.

Description

  An exemplary variation of the chamber 106 capable of etching the substrate 104 is schematically illustrated in FIG. Chamber 106 represents a Decoupled Plasma Source (DPS ™) chamber, which is an inductively coupled plasma etch chamber available from Applied Materials, Inc., Santa Clara, California. The DPS chamber 106 may be used in a CENTURA® integrated processing system commercially available from Applied Materials, Inc., Santa Clara, California. However, other process chambers may also be used in connection with the present invention including, for example, different designs of capacitively coupled parallel plate chambers, magnetically enhanced ion etching chambers, inductively coupled plasma etching chambers, and deposition chambers. Although the apparatus and process are advantageously used in a DPS chamber, the chamber is provided only to illustrate the invention and should not be construed to limit the scope of the invention.

  Referring to FIG. 1, a typical chamber 106 includes a housing 114 that includes an enclosure wall 118 that includes a side wall 120, a bottom wall 122, and a ceiling 124. The ceiling 124 may have a flat shape as shown, for example, “Method of Plasma Etching a Depth Received Feature in a Substitute Usage a Plasma Source Gas Modulated Etch” , 074,723, which has a multi-radial arcuate profile dome shape, which is incorporated herein by reference in its entirety. Wall 118 is typically fabricated from a metal such as aluminum or a ceramic material. The ceiling 124 and / or the sidewall 120 may also have a radiation transmissive window 126 that allows radiation to pass through the chamber and monitor the process performed in the chamber 106. A plasma is formed in a process zone defined by the process chamber 106, the substrate support and the dome-shaped ceiling 124.

  The substrate 25 is held in a chamber 106 on a receiving surface 26 of a substrate support comprising an electrostatic chuck 20 resting on a base 91. The electrostatic chuck 20 includes a ceramic pack 24 having a substrate receiving surface 26 that is the upper surface of the pack 24 and serves to hold a substrate 25 as shown in FIGS. The ceramic pack 24 also has a back side surface 28 opposite the substrate receiving surface 26. The ceramic pack 24 has a peripheral ledge 29 having a first step 31 and a second step 33. The ceramic pack 24 includes at least one of aluminum oxide, aluminum nitride, silicon oxide, silicon carbide, silicon nitride, titanium oxide, zirconium oxide, and mixtures thereof. The ceramic pack 24 may be a ceramic monolith made by hot pressing and sintering ceramic powder and then processing the sintered form to form the final shape of the chuck 24.

  It has been determined that the thickness of the ceramic pack 24 substantially affects the ability to rapidly raise and lower the temperature of the substrate. If the ceramic pack 24 is very thick, the pack 24 will take a very long time to raise and lower the temperature and the temperature of the underlying substrate will take a considerable amount of time accordingly to reach the desired setpoint temperature. Become. Furthermore, it was determined that if the ceramic pack 24 was very thin, it would cause substrate temperature variations during processing without maintaining the substrate at a constant state temperature. Further, the thickness of the ceramic pack 24 affects the operation of the electrode 36 embedded in the ceramic pack 24. If the layer thickness of the ceramic pack 24 immediately above the embedded electrode 36 is very large, the electrode 36 will not effectively couple energy into the plasma formed in the process zone. On the other hand, if the thickness of the ceramic pack 24 around the electrode 36 is very thin, the RF voltage applied to the electrode 36 may discharge into the plasma creation arc and plasma instability. Accordingly, the thickness of the ceramic pack 24 is precisely controlled to be less than about 7 mm, for example, about 4 to about 7 mm, and in one variation, the ceramic pack has a thickness of 5 mm. It was. At these thickness levels, the ceramic pack 24 allowed rapid increases and decreases in substrate temperature, while reducing temperature variations during the process and creating virtually no plasma instability. .

  Electrodes 36 embedded in the ceramic pack 24 generate electrostatic forces, hold the substrate placed on the substrate receiving surface 26, and optionally are used to capacitively couple energy to the plasma formed in the chamber. Is done. The electrode 36 is a conductor such as metal and is formed as a monopolar or bipolar electrode 34. The monopolar electrode has a single conductor, has a single electrical connection to an external power source, and a substrate formed in the chamber to apply an electrical bias across the substrate held by the chuck 20. It works with the charged species of plasma. A bipolar electrode has two or more conductors, each of which is biased with respect to the other to generate an electrostatic force that holds the substrate. The electrode 36 can be formed as a wire mesh or a metal plate with a suitable notch area. For example, the electrode 36 comprising a monopolar electrode may be a single continuous wire mesh embedded in a ceramic pack as shown. One embodiment of electrode 36 comprising a bipolar electrode may be a pair of filled C-shaped plates facing each other over a C-shaped straight leg. The electrode 36 may be made of aluminum, copper, iron, molybdenum, titanium, tungsten, or an alloy thereof. One variation of electrode 36 comprises a molybdenum mesh. The electrode 36 is connected to a terminal post 58 that supplies power to the electrode 36 from an external power source 230, which may include a DC voltage power source and optionally an RF voltage power source.

  Optionally, a plurality of heat transfer gas conduits 38a, b cross the ceramic pack 24 and terminate at ports 40a, b on the substrate receiving surface 26 of the chuck 20 to provide heat transfer gas to the substrate receiving surface 26. For example, a heat transfer gas, which may be helium, is supplied below the back side 34 of the substrate to conduct heat from the base substrate 25 and to the receiving surface 26 of the ceramic pack 24. For example, the first gas conduit 38a can be arranged to supply a heat transfer gas to the central heating zone 42a of the substrate receiving surface 26, and the second gas conduit 38b can be a peripheral heating zone of the substrate receiving surface 26. It can be arranged to supply heat transfer gas to 42b. Corresponding portions of the substrate surface 44 by the center and peripheral heating zones 42a, b of the substrate receiving surface 26 of the ceramic pack 24, for example, the substrate center and peripheral portions 46a, b of the substrate 25, can be maintained at different temperatures, It compensates for non-uniform concentric processing bands that occur on the substrate 25 due to corresponding non-uniform bands of different process conditions.

  The ceramic pack 24 also has an embedded heater for heating the substrate 25. The heater includes a plurality of heater coils 50 and 52, for example, a first heater coil 50 and a second heater coil 52 embedded in the ceramic pack 24. The temperatures of the center and peripheral heating zones 42a, b of the substrate receiving surface 26 of the ceramic pack 24 are controlled using heater coils 50,52 that are radially spaced and concentric with each other. The In one variation, the first heater coil 50 is disposed in the peripheral portion 54 b of the ceramic pack 24, and the second heater coil 52 is disposed in the central portion 54 a of the ceramic pack 24. The first and second heater coils 50, 52 allow independent control of the temperature of the center and peripheral portions 54a, 54b of the ceramic pack 24 and provide the ability to independently control the temperature of the heating zones 42a, b. Thus, different processing rates and features in the radial direction of the processing surface 44 of the substrate 25 are achieved. Accordingly, different temperatures can be maintained in the two heating zones 42a, b, and the variable gas species distribution that occurs during processing of the substrate 25 by affecting the temperature of the substrate center and peripheral portions 46a, b of the substrate 25. And can withstand heat loads. For example, if the gas species in the peripheral portion 46b of the processing surface 44 of the substrate 25 is not as active as the central portion 46b, the temperature of the peripheral heating zone 42b rises above the central heating zone 42a and over the processing surface 44 of the substrate 25. Provides more uniform processing rates and process characteristics. FIG. 8 demonstrates how the change in substrate temperature depends on the precharging of the heater power supplied by the inner and outer heating coils embedded in the chuck 24.

  In one variation, the first and second heater coils 50, 52 each comprise a circular loop of resistive heating elements arranged side by side and may be substantially coplanar. For example, each of the heater coils 50 and 52 may be a continuous concentric loop that gradually spirals radially inward of the main body of the ceramic pack 24. In one variation, the heater comprises a coil having a first loop spaced a first distance and a second loop spaced a second distance greater than the first distance. I have. The second loop is positioned around the lift pinhole of the pack. The heater coils 50, 52 may also be spiral coils that spiral around an axis passing through the center of the coil, such as a bulb filament positioned concentrically over the internal volume of the ceramic pack 24, for example. The resistance heating element may be made of different electrical resistance materials such as tungsten and molybdenum.

  The heater coils 50, 52 have electrical resistances and operating power levels that are selected to increase the rate at which the temperature of the substrate 25 is raised and lowered. In one variation, the heater coils 50, 52 each have a fairly high electrical resistance to rapidly raise and maintain the substrate receiving surface 26 of the ceramic pack 24 to a temperature of about 80 ° C to about 250 ° C. I have. In this variation, the electrical resistance of the coil is about 4 to about 12 ohms. In one example, the first heater coil 50 has an electrical resistance of 6.5 ohms, and the second heater coil 52 has an electrical resistance of 8.5 ohms. In another variation, the first and second heater coils have a total resistance of less than 10 ohms. In one variation, the heater has a resistance of 8.5 ohms. The heater coils 50, 52 are powered on via independent terminal posts 58 a-d that extend through the ceramic pack 24.

  In connection with the heater coils 50, 52, the pressure of the heat transfer gas can also be controlled in the two heating zones 42 a, b to make the substrate processing rate more uniform across the substrate 25. For example, the two zones 42a, b can each be set to hold the heat transfer gas at different equilibrium pressures to provide different heat transfer rates from the back side 34 of the substrate 25. This is accomplished by supplying two different pressure heat transfer gases via two conduits 38a, 38b and exiting at two different locations on the substrate receiving surface 26.

  The backside surface 28 of the ceramic pack 24 may have a plurality of spaced mesa 30 as shown in FIG. In one variation, the mesas 30 are cylindrical mounds that are separated from each other by a plurality of gaps 32. In use, the gap 32 is filled with a gas, such as air, to adjust the heat transfer rate from the backside surface 28 to the base substrate surface. In one embodiment, the mesa 30 includes a cylindrical mound, which can be molded as a post extending up from the surface 28, the post having a rectangular or circular cross-sectional shape. The height of the mesa 30 may be about 10 to about 50 microns, and the diameter of the mesa 30 may be about 500 to about 5000 microns. However, the mesa 30 can also have other shapes and sizes, such as conical or rectangular blocks, and bumps that vary in size. In one variation, the mesa 30 is formed, for example, by bead blasting the backside surface 28 with a suitably small bead size of tens of microns to etch the material of the backside surface 28 by corrosion and intervening gaps 32. Thus, the molded mesa 30 is formed.

  The electrostatic chuck 20 also passes through the holes 62a, b of the ceramic pack 24 and contacts the temperature of the base center and peripheral portions 46a, b of the substrate 25 to accurately measure the temperature sensor 60a, b. Is included. The first sensor 60a is positioned in the central heating zone 42a of the ceramic pack 24 to read the temperature of the central portion 46a of the substrate 25, and the second sensor 60b is correspondingly adjusted to the temperature of the peripheral portion 46b of the substrate 25. Is positioned in the peripheral heating zone 42b of the ceramic pack 24. The optical temperature sensors 60a, 60b are positioned on the chuck 20 so that the sensor tips 64a, b can contact the back side 34 of the substrate 25 held by the chuck 20, and the sensor tips 64a, b are the substrates of the ceramic pack 24. It is flush with the receiving surface 26. The legs 66a, b of the sensors 60a, b extend vertically through the body of the ceramic pack 24.

  In one variation, as shown in FIG. 5, each optical temperature sensor 60 includes a copper cap 70 that is shaped as a close-off cylinder with a side 72 and a dome-shaped upper portion 74 that acts as a tip 64. A sensor probe 68 is provided. The copper cap 70 may be made of an oxygen free copper material. A phosphorus plug 76 is embedded in the upper portion 74 of the copper cap 70 in direct contact therewith. A phosphorus plug 76 embedded in the copper cap 70 provides a quicker and more sensitive thermal response to the thermal sensing probe 68. The tip 64 of the copper cap 70 is a dome-shaped upper portion 74 that allows repeated contact with different substrates 25 without corroding or damaging the substrate. The copper cap 70 has a concave groove 78 for receiving an epoxy 79 for attaching the cap 70 to the sensor probe 68.

  The phosphorus plug 76 converts heat in the form of infrared radiation into photons that are allowed to pass through the optical fiber bundle 80. The optical fiber bundle 80 may be made of borosilicate glass fiber. The optical fiber bundle 80 is encased by a sleeve 82, which is also partially surrounded by a temperature isolation jacket 84 that acts to isolate the temperature sensor from the heat of the base supporting the ceramic pack. The sleeve 82 may be a glass tube to provide better thermal isolation from the surrounding structure, but it may also be made from a metal such as copper. The temperature isolation jacket 84 may be made of PEEK, polyetheretherketone, and Dupont de Nemours Co. Delaware's Teflon® (polytetrafluoroethylene) may also be used.

  A substrate support 90 comprising an electrostatic chuck 20 is fixed to a cooling base 91 that supports and secures the chuck 20 and cools the chuck (FIGS. 1 and 4). Base 91 includes a metal body 92 having an upper surface 94 having a chuck receiving portion 96 and a peripheral portion 98. The chuck receiving portion 96 of the top surface 94 is adapted to receive the backside surface 28 of the ceramic pack 24 of the electrostatic chuck 20. The peripheral portion 98 of the base 91 extends radially outward beyond the ceramic pack 24. The peripheral portion 98 of the base 91 is adaptable to receive a clamp ring 100 that can be secured to the top surface of the peripheral portion of the base. The metal body 92 of the base 91 has a number of passages that run from the bottom surface 104 of the base to the top surface 94 of the base 91, for example, to retain the terminals 58a-d and the feed gas in the gas conduits 38a, b of the ceramic pack 24. 102.

  Base 104 has a cooling channel 110 with an inlet 95 and a distal end 97 for circulating coolant through the channel. The inlet 95 and end 97 of the cooling channel 110 can be positioned adjacent to each other when the cooling channel 110 loops back on itself as shown in FIG. 4B. The coolant may be a fluid such as water or other suitable heat transfer fluid, which is maintained at a preset temperature with a cooler and pumped through a channel in the base 91. A base 91 with circulating cooling fluid acts as a heat exchanger to control the temperature of the chuck 20 to achieve the desired temperature across the processing surface 44 of the substrate 25. The fluid that has passed through the channel 110 can be heated or cooled to increase or decrease the temperature of the chuck 28 and the temperature of the substrate 25 held on the chuck 28. In one variation, the channel 110 is shaped and sized to flow fluid to maintain the base 91 at a temperature of about 0-120 ° C.

  The chuck receiving portion 96 of the upper surface 94 of the base 91 includes one or more grooves 106a, b for holding and flowing air across the back side of the ceramic pack 20. In one embodiment, the chuck receiving portion 96 includes a peripheral groove 106a that cooperates with the plurality of mesas 30 on the backside surface 28 of the ceramic pack 24 and controls the heat transfer rate from the peripheral portion 54b of the ceramic pack 24. ing. In another embodiment, the chuck receiving surface of the base includes a peripheral groove for containing air around a mesa on the back side of the pack. In yet another embodiment, the central groove 106b is used in conjunction with the peripheral groove 106a to regulate heat transfer from the central portion of the ceramic pack 24.

  The grooves 106a, b in the upper surface 94 of the base 91 cooperate with the mesas 30 on the backside surface 28 of the ceramic pack 24 to further adjust the temperature of the entire substrate processing surface 44. The mesas 30 on the back side surface 28 of the ceramic pack 24 can be distributed over the back side surface 28 in a uniform or non-uniform pattern. The shape, size, and spacing of the mesas 30 can control the total heat transfer area of the interface by controlling the total amount of contact surface of the mesa 30 with the top surface 94 of the base 91. In a uniformly spaced pattern, the distance between mesas 30 as represented by the gap 32 remains substantially the same, and in a non-uniform spacing, the gap distance varies across the surface 28.

  Optionally, the back surface 28 of the ceramic pack 24 may be spaced from the first array 39 of mesas 30 adjacent to the inlet of the base cooling channel 111 and the inlet 95 of the channel 111, as shown in FIG. And a second array 41 of mesas 30 adjacent to the end 97 of the cooling channel 111. The second array of mesas 230 has a different gap distance that forms a different pattern than the first array and adjusts the heat transfer rate around the area adjacent to and away from the cooling channel 111. For example, the portion of the ceramic pack 24 above the segment of the cooling channel 111 near the channel inlet 95 that receives fresh coolant is often lower than the portion of the ceramic pack 24 above the segment of the cooling channel 111 near the channel end. Maintained at temperature. This is because the coolant warms as it moves the length of the base channel by capturing heat from the ceramic pack 24. As a result, the temperature profile of the substrate 25 placed on the receiving surface 26 of the ceramic pack 24 is higher in the region below the cooling channel end 97 than in the region above the inlet 95. . This temperature profile includes a first array of mesas 30 around a channel inlet spaced by a first gap distance and a channel 111 spaced by a second gap distance different from the first distance. Compensated by providing a second array of mesas 30 around end 97. If the first distance is greater than the second distance, the heat transfer rate from the portion of the substrate 25 immediately above the first array is from the portion of the substrate 25 immediately above the second array 41. Lower than heat transfer rate. As a result, heat is transferred from the first substrate region at a slower rate than the heat transfer rate from the second substrate region, making the first region warmer than the second region and the inlet of the cooling channel. Compensate and equalize the temperature profile that would have occurred across the substrate surface 44 at 95 and end 97. In one example, the first array of mesas 39 is spaced at a first distance of at least about 5 mm, whereas the second array of mesas 41 is spaced at a second distance of less than about 3 mm. Has been opened.

  The same temperature profile control is obtained by changing the size of the contact area of the first array of mesas 39 relative to the size of the contact area of the second array of mesas 41. For example, the first dimension of the contact area of the first array of mesas 39 may be less than about 2000 microns, while the contact area of the second array of mesas 41 is at least about 3000 microns and Also good. The first and second dimensions may be the diameter of the mesa 30 with a post shape. In one variation, the first dimension is 1000 microns in diameter and the second dimension is 4000 microns in diameter. The smaller the contact area, the higher the temperature of the entire substrate processing surface 44. Also, air is provided between the mesas 30 and the entire backside surface 28 to act as a further temperature regulator.

  Another factor that affects the ability to rapidly raise and lower the temperature of the substrate is the nature of the thermal interface between the ceramic pack 24 and the base 91. An interface with good thermal conductivity is desirable at this interface because it easily removes heat from the ceramic pack 24 by the coolant moving through the base 91. In addition, it is desirable that the interface be soft because a large temperature difference between the ceramic pack 24 and the cooling base 91 results in thermal expansion stress that can cause cracks in the ceramic pack 24 and other thermal stress induced damage. In one variation, a soft layer is used to adhere the back side surface of the ceramic pack 24 to the front surface of the base 91. Although the soft layer is made to provide good thermal conductivity, it is still quite soft to absorb high heat stress. In one variation, the soft layer comprises silicon embedded with aluminum fibers. While silicon materials provide good softness, they still have reasonable thermal conductivity. The thermal conductivity of the silicon material is enhanced by the embedded aluminum fibers. In another variation, the soft layer comprises acrylic with an embedded wire mesh. Also, the acrylic polymer is selected to provide heat stress to the softness, whereas the embedded wire mesh increases the thermal conductivity of the structure.

  Base 91 further includes an electrical terminal assembly 120 for conducting electrical power to electrode 36 of electrostatic chuck 20. The electrical terminal assembly 120 includes a ceramic insulation jacket 124. The ceramic insulating jacket 124 may be aluminum oxide, for example. A plurality of end posts 58 are embedded in the ceramic insulation jacket 124. The terminal posts 58 and 58a to d supply power to the electrode 36 and the heater coils 50 and 52 of the electrostatic chuck 20. For example, the terminal post 58 may include a copper post.

  The ring assembly 170 also reduces the formation of process deposits and corrodes the peripheral region of the substrate support 90 with the electrostatic chuck 20 supported by the base 91, as shown in FIGS. 6A and 6B. Can be provided to protect. The ring assembly 170 includes a clamp ring 100 that is fixed to the peripheral portion 98 of the upper surface 94 of the base 91 by fixing means such as screws and bolts (not shown). The clamp ring 100 has a lip 172 extending transversely and radially inward, an upper surface 174 and an outer side 176. The lip 172 has a lower surface 173 that rests on the first step 31 of the peripheral ledge 29 of the ceramic pack 24 to form a gas tight seal between the ceramic pack 24 and the upper surface 174 and outer side 176. . In one variation, the lower surface 173 includes a polymer layer 179 comprising, for example, polyimide, forming a good gas tight seal. The clamp ring 100 is made of a material that can resist corrosion by plasma, for example, a metal material such as stainless steel, titanium, or aluminum, or a ceramic material such as aluminum oxide.

  The ring assembly also includes an end ring 180 with a band 182 having a foot 184 resting on the upper surface 174 of the clamp ring 100. The end ring also has an annular outer wall 186 that surrounds the outer surface 176 of the clamp ring 100 that is exposed to the processing environment to reduce or entirely eliminate the deposition of sputtering deposits on the clamp ring 100. Yes. The end ring 180 is also a flange that covers the second step 33 of the peripheral ledge 29 of the ceramic pack 29 to form a seal with the edge of the substrate covering the end ring 180 held on the receiving surface of the ceramic pack. 190 is provided. The flange 190 includes a protrusion 194 that terminates below the overhanging end 196 of the substrate 25. The flange 190 defines the inner edge of the ring 190 that surrounds the periphery of the substrate 25 and protects the area of the ceramic pack 24 that is not covered by the substrate 25 during processing. The clamp ring 100 and end ring 180 of the ring assembly 170 work together to reduce the formation of process deposits on the electrostatic chuck 20 supported on the base 91 during processing of the substrate 25 in the process chamber, It also protects against corrosion. The end ring 180 protects the exposed side of the substrate support 90 and reduces corrosion due to energized plasma species. Because the ring assembly 170 can be easily removed to clean deposits from the exposed surfaces of the rings 100, 180, the entire substrate support 90 need not be disassembled for cleaning. The end ring 180 includes, for example, ceramic such as quartz.

  In operation, a gas delivery system 150 that includes a process gas supply 204 that includes a gas source each supplying a conduit 203 having a gas flow control valve 158, such as a mass flow controller, for passing process gas through a set flow rate. Through the chamber 106. The conduit supplies gas to a mixing manifold (not shown) where the gas is mixed to form the desired process gas composition. The mixing manifold supplies a gas distributor (not shown) 162 having a gas outlet to the chamber 106. The gas outlet may pass through the chamber sidewall 120 and terminate at the periphery of the substrate support 20 or may pass through the ceiling 124 and terminate above the substrate 25. Spent process gas and by-products receive one or more exhaust ports 211 that receive the spent process gas and pass the spent gas through a discharge conduit with a throttle valve for controlling the gas pressure in the chamber 106. It is exhausted from the chamber 106 via the exhaust system 210 that contains it. The discharge conduit 172 supplies one or more discharge pumps 218. The exhaust system 210 may also contain a disposal treatment system (not shown) for reducing undesirable gases that are exhausted.

  The process gas is energized to process the substrate 25 by a gas energizer 208 that couples energy to the process gas in the process zone of the chamber 106 or a remote zone (not shown) upstream of the chamber 106. An “energized process gas” will activate or energize the process gas to form one or more of dissociated gas species, non-dissociated gas species, ionic gas species, and natural gas species. . In one variation, the gas energizer 208 includes an antenna 186 that includes one or more inductor coils 188 that may have circular symmetry about the chamber 106. In general, antenna 186 includes a solenoid having from about 1 to about 20 turns, with a central axis coinciding with a longitudinal vertical axis extending through process chamber 106. The appropriate arrangement of solenoids is selected to provide a strong inductive flux link and coupling to the process gas. When the antenna 186 is positioned near the ceiling 124 of the chamber 106, the adjacent portion of the ceiling 124 may be made of a dielectric material, such as silicon dioxide, that is transparent to RF or electromagnetic fields. The antenna 186 is powered on by an antenna current supply (not shown) and the applied power is tuned by the RF matching network 192. The antenna current supply, for example, provides RF power to the antenna 186 at a frequency of typically about 50 kHz to about 60 MHz, more typically about 13.56 MHz, and at a power level of about 100 to about 5000 watts.

  When the antenna 186 is used in the chamber 106, the wall 118 includes a ceiling 124 made from an inductive electromagnetic field transmissive material such as aluminum oxide or silicon dioxide, and the inductive energy from the antenna 186 passes through the wall 118 or the ceiling 124. Allow to penetrate. A suitable semiconductor material is doped silicon. For doped silicon semiconductor ceilings, the temperature of the ceiling 124 is preferably maintained in a range where the material provides semiconductor properties and the carrier electron concentration is fairly constant with temperature. For doped silicon, the temperature range may be from about 100K (below the silicon begins to have dielectric properties) to 600K (below the silicon begins to have metal conductor properties).

  In one variation, the gas energizer 208 is also a pair of electrodes (which may be capacitively coupled to provide plasma initiation energy to the process gas or to provide kinetic energy to the energized gas species. (Not shown). In general, one electrode is on the support 20 below the substrate 20 and the other electrode is a wall, for example, the side wall 120 or the ceiling 124 of the chamber 106. For example, a semiconductor that is sufficiently conductive to be biased or grounded to form an electric field in the chamber 106 while still providing a low impedance to the RF induction field transmitted by the antenna 186 above the ceiling 124. It may be a ceiling 124 made from Suitable semiconductors comprise, for example, silicon doped to have an electrical resistance of less than about 500 cm at room temperature. In general, the electrodes may be mutually electrically biased by a bias voltage supply (not shown) that provides an RF bias voltage to the electrodes to capacitively couple the electrodes to each other. The applied RF voltage is tuned by the RF matching network 202. The RF bias voltage may have a frequency of about 50 kHz to about 60 MHz, or about 13.56 MHz, and the power level of the RF bias current is typically about 50 to about 3000 watts.

  The chamber 106 provides instructions for operating chamber components including the substrate support 20 for raising and lowering the substrate support 20, the gas flow control valve 158, the gas energizer 208 and the throttle valve 174 via the hardware interface 304. It may be operated by a controller 300 comprising a sending computer 302. Process conditions measured by different detectors of the chamber 106 or sent as feedback signals by control devices such as a gas flow control valve 158, pressure monitor (not shown), throttle valve 174, and other such devices, and The parameter is transmitted to the controller 300 as an electrical signal. Although the controller 300 is illustrated as an example of an exemplary single controller device to simplify the description of the present invention, the controller 300 may include multiple controller devices that may be connected to each other and different chambers 106. It should be understood that there may be multiple controller devices that may be connected to a component, and thus the present invention is limited to the example and exemplary embodiments described herein. Should not.

  The controller 300 includes electronic hardware that includes electrical circuitry comprising integrated circuits suitable for operating the chamber 106 and its peripheral components. In general, the controller 300 receives data input, runs algorithms, generates useful output signals, detects data signals from detectors and other chamber components, and monitors process conditions in the chamber 106. Or is adapted to control. For example, the controller 300 may (1) be coupled to a memory 308 including, for example, a removable storage medium 310 such as a CD or floppy drive, and a non-removable storage medium 312 such as a hard drive, ROM and RAM 314, for example, INTEL. A central processing unit (CPU) 306, such as a conventional microprocessor of the company; and (ii) designed for specific tasks such as retrieval of data and other information from the chamber 106 and operation of specific chamber components Interface board used in specific signal processing tasks, including programmed application specific integrated circuits (ASICs), and (iii) analog and digital input and output boards, communication interface boards and motor controller boards, for example 304 and it may include a computer 302 comprising a. For example, the controller interface board 304 may process a signal from the process monitor 210 and provide a data signal to the CPU 306. The computer 302 also has support circuitry that includes, for example, a coprocessor, clock circuit, cache, power supply, and other well-known components in communication with the CPU 306. RAM 314 can be used to store the software implementation of the present invention during process implementation. The instruction set of the code of the present invention is generally stored in the storage media 310, 312 and is called to the primary storage of the RAM 314 when executed by the CPU 306. A user interface between the operator and the controller 300 is possible via, for example, a display 316 and a data input device 318 such as a keyboard and a light pen. To select a particular screen or function, the operator can enter the selection using the data input device 318 and view the selection on the display 316.

  Data signals received and evaluated by the controller 300 may be sent to the factory automation host computer 320. The factory automation host computer 320 evaluates data from several systems, platforms or chambers 106 and for a batch of substrates 104 or for extended periods of time to (i) processes performed on a substrate, (ii) A host software program 322 that identifies statistical process control parameters for characteristics that may change statistical relationships across a single substrate and (iii) characteristics that may change across batches of substrates May be. The host software program 322 may also use data for ongoing in situ process evaluation and control of process parameters. A suitable host software program comprises the WORKSTREAM ™ software program available from Applied Materials, Inc. above. The factory automation host computer 320 may further: (i) identify a particular substrate 25 if, for example, the substrate characteristics are inappropriate or statistically not within a predetermined range of values, or if the process parameters are out of tolerance. Command signals to adjust process conditions when determining (ii) terminating the etch in a particular chamber 106, or (iii) determining inappropriate properties of the substrate 25 or process parameters. It may be adapted to provide. The factory automation host computer 320 may also provide command signals at the beginning or end of etching of the substrate 25 in response to the evaluation of the data by the host software program 322.

In one variation, the controller 300 includes a computer program 330 that is readable by the computer 302 and may be stored in the memory 308 on the non-removable storage medium 312 or the removable storage medium 310, for example. The computer program 330 generally includes process control software with program code for operating the chamber 106 and its components, process monitoring software for monitoring processes performed in the chamber 106, secure system software, and other Control software. The computer program 330 may be written in any conventional programming language such as, for example, assembly language, C ⁺⁺ , Pascal, or Fortran. Appropriate program code is entered into a single file or multiple files using a conventional text editor and stored or embodied in a computer-usable medium in memory 308. If the input code text is in a high level language, the code is compiled and the resulting compiler code is linked with the object code of the precompiled library routine. To execute the linked compiled object code, the user invokes the object code and causes the CPU 306 to read and execute the code to perform the tasks identified in the program.

  In operation, using data input device 318, for example, a user enters a process set and chamber number into computer program 330 in response to a menu or screen on display 316 generated by process selector 332. The computer program 330 includes an instruction set for controlling substrate position, gas flow, gas pressure, temperature, RF power level, and other parameters of a particular process and an instruction set for monitoring the chamber process. . A process set is a predetermined group of process parameters necessary to perform a specified process. Process parameters are process conditions including, without limitation, gas energizer settings such as gas composition, gas flow, temperature, pressure, and RF or microwave power levels. The chamber number reflects the ID of a particular chamber when there is a set of interconnected chambers on the platform.

  Process sequencer 334 includes a set of instructions for receiving chamber numbers and process parameter sets from computer program 330 and process selector 332 and controlling this operation. The process sequencer 334 initiates execution of the process set by passing specific process parameters to a chamber manager 336 that controls a number of tasks in the chamber 106. The chamber manager 336 provides instruction sets such as, for example, a substrate positioning instruction set 340, a gas flow control instruction set 342, a gas pressure control instruction set 344, a temperature control instruction set 348, a gas energizer control instruction set 350, and a process monitoring instruction set 352. May be included. Although described as separate instruction sets for performing a set of tasks, each of these instruction sets may be integrated with each other, or may overlap, and thus is described herein. The chamber controller 300 and computer readable program described are not to be limited to the specific variations of the functional routines described herein.

  The substrate positioning instruction set 340 includes code for controlling the chamber components that are used to load the substrate 25 onto the substrate support 20 and optionally lift the substrate 25 to the desired height of the chamber 106. . For example, the substrate positioning instruction set 340 operates a transfer robot arm (not shown) that transfers the substrate to the chamber, controls lift pins (not shown) extended through the holes of the electrostatic chuck, and controls the robot arm. A cord for coordinating movement and movement of the lift pin can be included.

  The program code also sets the temperature maintained in different regions of the substrate 25, for example by applying different power levels separately to the first and second heater coils 50, 52 in the ceramic pack 24 of the chuck 20. And a temperature control instruction set 348 for controlling. The temperature control instruction set 348 also regulates the flow of heat transfer gas through the conduits 38a, b.

  The temperature control instruction set 348 also includes code for controlling the temperature and flow rate of the cooling fluid that has passed through the cooling channel 110 of the base 91. In one variation, the temperature control command set 348 increases the coolant temperature of the cooler from an initial low level to a higher level, for example for at least about 1 second, immediately before increasing the power level applied to the heater. It has a code. This allows higher temperature coolant to circulate in the cooling channel of the base 91 just before the heater raises the temperature and reduces the heat flow from the ceramic pack 24 to the base 91 if the heater temperature does not rise eventually. Thus, the temperature rise rate of the substrate can be effectively increased. Conversely, program code 348 may set the temperature of the coolant, for example, at least before reducing the power level applied to the heater to accelerate the rate at which heat is transferred from the substrate when the substrate temperature is lowered. Includes an instruction set that lowers about 10 ° C. and lowers the cooler to a lower level. The temperature versus time graph of FIG. 7 depicts the temperature ramp rate of a substrate tilted from 45 ° C. to 75 ° C. with the cooling base maintained at 5 ° C. FIG. 9 depicts a rapid change in the substrate temperature with a graph of the temperature gradient of the electrostatic chuck that holds and applies heat to the substrate. The substrate is maintained at the same temperature as the electrostatic chuck through the use of backside helium pressure. The graph demonstrates how the electrostatic chuck is raised and lowered at predetermined time intervals. The two steep peaks in the graph indicate a rapid rise and fall in temperature, respectively. Such a fast temperature ramp of the electrostatic chuck allows for the etching of materials that were previously incompatible, such as Poly-Si and WSIX, because they anticipate rapid changes in substrate temperature.

  Process feedback control instruction set 352 receives temperature signals from optical temperature sensors 60a, b and applies power to chamber components such as heater coils 50,52 and the flow of heat transfer gas through conduits 38a, b. , Can act as a feedback control loop between temperature monitoring instruction set 348 that regulates fluid flow through channel 110 of base 91 and coolant temperature of the cooler.

  The gas flow control instruction set 342 includes code for controlling the flow rates of the different components of the process gas. For example, the gas flow control instruction set 342 may adjust the opening size of the gas flow control valve 158 to obtain a desired gas flow rate from the gas outlet 203 to the chamber 106. In one variation, the gas flow control instruction set 342 sets a first volume flow rate of the first gas and a second volume flow rate of the second gas to a second process gas in the process gas composition. A code for setting a desired volume flow rate ratio of the first process gas is provided.

  The gas pressure control instruction set 344 includes program code for controlling the pressure in the chamber 106 by adjusting the opening / closing position of the throttle valve 174. The temperature control instruction set 348 may include, for example, code for controlling the temperature of the substrate 104 during etching and code for controlling the temperature of the walls of the chamber 106, such as the temperature of the ceiling. The gas energizer control instruction set 350 includes a code for setting the RF power level applied to the electrode and the antenna 186, for example.

  Although described as separate instruction sets for performing a set of tasks, each of these instruction sets can be integrated with each other, i.e., a set of program code tasks is a desired set of tasks. It should be understood that they are mutually integrated with tasks to perform Thus, the controller 300 and computer program 330 described herein should not be limited to the specific variations of the functional routines described herein, but perform an equivalent set of functions. Any other set of routines or merged program codes that are also within the scope of the present invention. Also, although the controller is illustrated for one variation of chamber 106, it can be used for any chamber described herein.

  The apparatus and process of the present invention provides significant advantages by allowing rapid changes in the temperature of the substrate between different steps of the process performed on the substrate and chamber. Such rapid temperature changes increase the rate at which an etching process having multiple steps can be performed. The system also allows an accurate reproduction of the temperature rise and fall profiles desired for a particular process, such as an etch process that has multiple etching steps required to etch different materials and layers on the substrate. Yet another advantage is that the apparatus allows the substrate to be maintained at a much higher temperature than the cooling base temperature, which also eliminates any substrate temperature drift during the process and results in a higher plasma. Allows power to be applied to the substrate. A large temperature difference between the substrate and the cooling base also allows a good temperature difference between the inner and outer zones of the substrate and can compensate for annular process conditions that vary across the substrate surface.

  Although the present invention has been described in considerable detail with respect to this particular preferred variation, other variations are possible. For example, device components such as substrate supports, cooling bases, and temperature sensors can be used for chambers and processes other than those described herein. Accordingly, the appended claims should not be limited to the description of the preferred variations contained herein.

1 is a schematic side view of an embodiment of a substrate processing chamber comprising an electrostatic chuck. 1 is a schematic cross-sectional side view of an embodiment of an electrostatic chuck. It is a schematic bottom view of the electrostatic chuck of FIG. 1 is a schematic perspective view of the upper part of an embodiment of a base of an electrostatic chuck. 2 is a schematic perspective view of the bottom of an embodiment of a base of an electrostatic chuck. FIG. It is a schematic side view of an optical temperature sensor. 4B is a schematic cross-sectional side view of a ring assembly on the electrostatic chuck of FIGS. 4A and 4B. FIG. 6B is a detail of the ring assembly of FIG. 6A. FIG. 6 is a graph depicting substrate temperature that is ramped at a certain time interval by a constant temperature cooler. FIG. It is a graph which depicts the temperature difference between the electrostatic chuck and the cooler with respect to the precharge of the heater power. It is a graph which draws the temperature gradient of an electrostatic chuck.

Explanation of symbols

DESCRIPTION OF SYMBOLS 104 ... Board | substrate, 106 ... Chamber, 120 ... Side wall, 122 ... Bottom wall, 124 ... Ceiling, 118 ... Enclosure wall, 114 ... Housing, 124 ... Ceiling, 208 ... Gas energizer, 300 ... Controller, 218 ... Exhaust pump.

Claims (20)

A substrate support assembly capable of holding and heating a substrate in a process chamber, comprising:
(A) a ceramic puck, (i) a substrate receiving surface having a plurality of ports for supplying heat transfer gas to the receiving surface; (ii) a central portion; (Iii) an opposing backside surface comprising a plurality of spaced mesa comprising a first group of mesas and a second group of mesas ; iv) an embedded electrode for generating an electrostatic force to hold the substrate placed on the substrate receiving surface; and (v) embedded in the ceramic pack for heating the substrate. A heater comprising a first heater coil disposed in the peripheral portion of the ceramic pack and a second heater coil disposed in the central portion of the ceramic pack. A ceramic pack comprising a motor,
(B) a cooling base comprising a cooling channel for circulating a coolant, wherein the cooling channel comprises an inlet and an end;
(C) a soft layer that bonds the ceramic pack to the cooling base, the soft layer comprising at least one of (i) silicon with embedded aluminum fibers or (ii) acrylic with embedded wire mesh. Prepared,
The heater including the first and second heater coils, the cooling base, and the soft layer cooperate to independently control the temperature of the central portion and the peripheral portion of the ceramic pack, and the temperature of the substrate. Can rise and fall rapidly ,
(I) the first mesas are spaced apart by a first distance that is longer than a second distance between the second mesas;
(Ii) each of the first mesas has a first contact area having a size smaller than that of the second contact area of the second mesa;
assembly.   The support assembly of claim 1, wherein the inlet and end of the cooling channel are adjacent to each other and the cooling channel loops back to itself. Said first mesa is adjacent to the inlet of the cooling channel, the second mesa is away from the inlet of the cooling channel, the support assembly of claim 2. The ceramic pack has the following features:
(I) a thickness of less than about 7 mm;
(Ii) a thickness of about 4 to about 7 mm, or (iii) the ceramic pack is made of aluminum oxide,
The support assembly of claim 1, comprising at least one of:   The support assembly of claim 1, wherein the electrode and heater each comprise either tungsten or molybdenum. The following features:
(I) the first and second heater coils are radially spaced from each other and concentric;
(Ii) the first and second heater coils have a coupling resistance of less than 10 ohms;
(Iii) The first heater coil includes a first loop spaced by a first distance, and the second heater coil is spaced by a second distance that is longer than the first distance. The support assembly of claim 1, comprising at least one of including a second loop.   The support assembly of claim 6, wherein in (iii) the second loop is positioned about a lift pinhole of the ceramic pack. An electrostatic chuck capable of holding and heating a substrate in a process chamber,
(A) (i) a substrate receiving surface having a plurality of ports for supplying a heat transfer gas to the receiving surface; (ii) a central portion and a peripheral portion; and (iii) opposite. A ceramic pack comprising a plurality of spaced apart mesas comprising a first group of mesas and a second group of mesas ;
(B) an electrode embedded in the ceramic pack for generating an electrostatic force to hold a substrate placed on the substrate receiving surface;
(C) a heater embedded in the ceramic pack for heating the substrate received at the substrate receiving surface, the first heater coil disposed in the peripheral portion of the ceramic pack; A heater including a second heater coil disposed in the central portion of the ceramic pack;
(D) a cooling base bonded to the ceramic pack, the cooling base comprising a cooling channel for circulating a coolant;
Equipped with a,
(I) the first mesas are spaced apart by a first distance that is longer than a second distance between the second mesas;
(Ii) each of the first mesas has a first contact area having a size smaller than that of the second contact area of the second mesa;
Electrostatic chuck.   The electrostatic chuck of claim 8, wherein the ceramic pack comprises a thickness of less than 7 mm. (I) the ceramic pack is made of aluminum oxide;
(Ii) The electrostatic chuck according to claim 8, wherein each of the electrode and the heater is made of tungsten or molybdenum. A substrate processing apparatus,
(A) A process chamber in which a substrate support is mounted, wherein the substrate support is
(I) [i] a substrate receiving surface having a plurality of ports for supplying heat transfer gas to the substrate receiving surface; [ii] an opposing back surface; [iii] an electrode; A ceramic pack comprising a heater embedded therein;
(Ii) a cooling base bonded to the backside surface of the ceramic pack under the ceramic pack, the cooling base comprising a cooling channel;
(Iii) a process chamber comprising: a cooler for maintaining the coolant at a cooling temperature that allows the coolant to pass through the cooling channel of the cooling base;
(B) a gas distributor for providing process gas to the process chamber;
(C) a gas energizer for imparting energy to the process gas;
(D) a gas exhaust port for exhausting the process gas from the chamber;
(E) (i) raising the cooling temperature of the cooler to a higher level before raising the power level applied to the heater in the ceramic pack, or (ii) applied to the heater in the ceramic pack A controller comprising a temperature control instruction set comprising code that allows the temperature of the substrate to be raised or lowered at a faster rate by lowering the cooling temperature of the cooler to a lower level before reducing the power level; Prepared,
The temperature control instruction set, at least about 1 second before raising or lowering the power level applied to the heater in the ceramic puck includes code for changing the cooling temperature of the cooler, the device. A substrate processing apparatus,
(A) A process chamber in which a substrate support is mounted, wherein the substrate support is
(I) [i] a substrate receiving surface having a plurality of ports for supplying heat transfer gas to the substrate receiving surface; [ii] an opposing back surface; [iii] an electrode; A ceramic pack comprising a heater embedded therein;
(Ii) a cooling base bonded to the backside surface of the ceramic pack under the ceramic pack, the cooling base comprising a cooling channel;
(Iii) a process chamber comprising: a cooler for maintaining the coolant at a cooling temperature that allows the coolant to pass through the cooling channel of the cooling base;
(B) a gas distributor for providing process gas to the process chamber;
(C) a gas energizer for imparting energy to the process gas;
(D) a gas exhaust port for exhausting the process gas from the chamber;
(E) (i) raising the cooling temperature of the cooler to a higher level before raising the power level applied to the heater in the ceramic pack, or (ii) applied to the heater in the ceramic pack A controller comprising a temperature control instruction set comprising code that allows the temperature of the substrate to be raised or lowered at a faster rate by lowering the cooling temperature of the cooler to a lower level before reducing the power level; Prepared,
The temperature control instruction set comprises code for causing at least about 10 ° C. change the cooling temperature, the device. A substrate processing apparatus,
(A) A process chamber in which a substrate support is mounted, wherein the substrate support is
(I) [i] a substrate receiving surface having a plurality of ports for supplying heat transfer gas to the substrate receiving surface; [ii] an opposing back surface; [iii] an electrode; A ceramic pack comprising a heater embedded therein;
(Ii) by a soft layer comprising at least one of (i) a silicon material having embedded aluminum fibers or (ii) an acrylic having an embedded wire mesh on the backside surface of the ceramic pack, under the ceramic pack . A bonded cooling base comprising a cooling channel;
(Iii) a process chamber comprising: a cooler for maintaining the coolant at a cooling temperature that allows the coolant to pass through the cooling channel of the cooling base;
(B) a gas distributor for providing process gas to the process chamber;
(C) a gas energizer for imparting energy to the process gas;
(D) a gas exhaust port for exhausting the process gas from the chamber;
(E) (i) raising the cooling temperature of the cooler to a higher level before raising the power level applied to the heater in the ceramic pack, or (ii) applied to the heater in the ceramic pack A controller comprising a temperature control instruction set comprising code that allows the temperature of the substrate to be raised or lowered at a faster rate by lowering the cooling temperature of the cooler to a lower level before reducing the power level; Said device.   The support assembly of claim 1, wherein the soft layer comprises silicon or acrylic polymer.   A first heat transfer gas conduit traverses the ceramic pack and terminates at a port on the substrate receiving surface, the conduit being arranged to supply a heat transfer gas to a central heating zone of the substrate receiving surface. The support assembly of claim 1, comprising a gas conduit and a second gas conduit arranged to supply a heat transfer gas to a peripheral heating zone of the substrate receiving surface.   The support assembly of claim 1, comprising an optical temperature sensor for measuring the temperature of overlapping central and peripheral portions of the substrate.   The support assembly of claim 1, wherein the temperature sensor comprises a first sensor disposed in a central portion of the ceramic pack and a second sensor disposed in a peripheral portion of the ceramic pack.   The support assembly of claim 1, wherein the soft layer comprises a silicon material. A substrate support assembly capable of holding and heating a substrate in a process chamber, comprising:
(A) a ceramic pack, (i) a substrate receiving surface, the substrate receiving surface having a plurality of ports for supplying heat transfer gas to the receiving surface; and (ii) an opposing back surface . A ceramic pack comprising a plurality of spaced apart mesas comprising a first group of mesas and a second group of mesas, said opposing backside surface , and (iii) embedded electrodes and heaters When,
(B) a cooling base that is bonded to the back surface of the ceramic pack with a silicon material under the ceramic pack, the cooling base including a cooling channel ;
(I) the first mesas are spaced apart by a first distance that is longer than a second distance between the second mesas;
(Ii) each of the first mesas has a first contact area having a size smaller than that of the second contact area of the second mesa;
assembly.   The ceramic pack includes a central portion and a peripheral portion, and the heater is disposed in the peripheral portion of the ceramic pack, and a second heater coil is disposed in the central portion of the ceramic pack. 20. A support assembly according to claim 19, comprising a heater coil.

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