Abstract:
A support assembly for a semiconductor processing chamber is provided and includes a body comprising a heater, and a puck coupled to the body, the puck comprising a chucking electrode embedded in a dielectric material, wherein, when a radio frequency power of about 13.56 megahertz is applied to a substrate receiving surface of the body, an electrical resistance (R) of the body is about 0.460 Ohms, or less, and an electrical reactance (X) of the body is about 10.9 Ohms, or greater.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims benefit of U.S. Provisional Patent Application Ser. No. 62/342,563, filed May 27, 2016, which is hereby incorporated by reference herein. 
     
    
     BACKGROUND 
     Field 
       [0002]    Embodiments of the disclosure generally relate to an electrostatic chuck having a radio-frequency impedance, and methods and apparatus for determining radio-frequency impedance in an electrostatic chuck, as well as methods for testing and manufacture thereof. 
       Description of the Related Art 
       [0003]    In the manufacture of electronic devices on substrates, such as semiconductor wafers and displays, many vacuum processes are utilized, such as chemical vapor deposition (CVD), physical vapor deposition (PVD), etch, implant, oxidation, nitridation, or other processes, to form the electronic devices. The substrates are typically processed one by one on an electrostatic chuck in a substrate processing chamber. To increase throughput, modern manufacturers often utilize a plurality of these substrate processing chambers operating in parallel (i.e., running a common process recipe). Each of the processing chambers may be the same make and model and are typically configured to process a substrate according to the common recipe. Thus, a plurality of substrates may be processed within the same time period to produce identical products. 
         [0004]    While the processing chambers may be seemingly identical, subtle variations may exist between the processing chambers. The variations may require adjustment of the process parameters on one or more of the processing chambers to obtain “chamber match” or “chamber matching.” One methodology to reduce chamber on-substrate results in processing chambers utilizing radio frequency (RF) induced plasma processes is to modify the RF power parameters of a particular processing chamber to compensate for a chamber-to-chamber variation in order to produce a product that is in tolerance with other products that are processed in other processing chambers according to the common recipe. However, to modify the RF power parameters to obtain chamber matching, additional hardware is typically required. The additional hardware is often costly and typically does not address the root cause of the chamber-to-chamber variation. In addition, the electrostatic chuck plays a role in the deposition of dielectric films in chambers. The chuck has multiple functions and one being providing a return path for the radio-frequency power applied to generate the plasma. Characterizing the RF impedance of the chuck is one way to ensure that the chuck has consistent process performance and to improve chamber matching. 
         [0005]    Accordingly, it is desirable to reduce the chamber-to-chamber variations as well as on-substrate results. 
       SUMMARY 
       [0006]    In one embodiment, a support assembly for a semiconductor processing chamber is provided and includes a body comprising a heater, and a puck coupled to the body, the puck comprising a chucking electrode embedded in a dielectric material, wherein, when a radio frequency power of about 13.56 megahertz is applied to a substrate receiving surface of the body, an electrical resistance (R) of the body is about 0.460 Ohms, or less, and an electrical reactance (X) of the body is about 10.9 Ohms, or greater. 
         [0007]    In another embodiment, a processing tool is provided that includes a plurality of processing chambers configured to run the same recipe on a respective substrate disposed on a support assembly within each of the processing chambers, wherein an impedance (Z) of each of the support assemblies is substantially the same. 
         [0008]    In another embodiment, a testing fixture is provided that includes a ground plate, a conductive plate to electrically couple to a substrate receiving surface of a support assembly, a dielectric spacer sandwiched between the conductive plate and the ground plate, wherein the conductive plate has a center conductor disposed through the dielectric spacer and the ground plate, and an interface that couples with a network analyzer that provides radio frequency power to the conductive plate and the substrate receiving surface 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    So that the manner in which the above-recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this disclosure and are therefore not to be considered limiting of its scope, for the disclosure may admit to other equally effective embodiments. 
           [0010]      FIG. 1  is a partial cross sectional view showing an illustrative processing chamber. 
           [0011]      FIG. 2  is a schematic side view of one implementation of a test fixture disposed on a support assembly that may be used in the processing chamber of  FIG. 1 . 
           [0012]      FIG. 3  shows one embodiment of an equivalent test circuit provided by the fixture shown in  FIG. 2 . 
           [0013]      FIG. 4  is a schematic side view of one embodiment of a measurement jig for determining impedance of a support assembly. 
           [0014]      FIG. 5  is a schematic view of one embodiment of a fixture calibration jig that may be used to test the test fixture of  FIG. 2  or the measurement jig of  FIG. 4 . 
           [0015]      FIG. 6  is a schematic top plan view of a processing tool having support assemblies as described herein. 
       
    
    
       [0016]    To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation. 
       DETAILED DESCRIPTION 
       [0017]    Embodiments described herein generally relate to an electrostatic chuck for use in a vacuum processing chamber. The electrostatic chuck has as one role facilitating transmission of radio frequency (RF) power in the chamber as well as chucking a substrate thereon. This application discloses a fixture for testing the electrical characteristics of an electrostatic chuck as well as methods for manufacture thereof. The methods and apparatus as described herein reduce within substrate variations as well as chamber to chamber variations which enable chamber matching for operating plural processing chambers in parallel. 
         [0018]      FIG. 1  is a partial cross sectional view showing an illustrative processing chamber  100 . In one embodiment, the processing chamber  100  includes a chamber body  102 , a lid assembly  104 , and a support assembly  106 . The lid assembly  104  is disposed at an upper end of the chamber body  102 , and the support assembly  106  is at least partially disposed within the chamber body  102 . The processing chamber  100  and the associated hardware are preferably formed from one or more process-compatible materials, such as aluminum, anodized aluminum, nickel plated aluminum, nickel plated aluminum 6061-T6, stainless steel, as well as combinations and alloys thereof, for example. 
         [0019]    The chamber body  102  includes a slit valve opening  108  formed in a sidewall  110  thereof to provide access to the interior of the processing chamber  100 . The slit valve opening  108  is selectively opened and closed to allow access to the interior of the chamber body  102  by a substrate handling robot (not shown). In one embodiment, a substrate can be transported in and out of the processing chamber  100  through the slit valve opening  108  to an adjacent transfer chamber and/or load-lock chamber, or another chamber within a cluster tool. 
         [0020]    In one or more embodiments, the chamber body  102  includes a channel  112  formed therein for flowing a heat transfer fluid therethrough. The heat transfer fluid can be a heating fluid or a coolant and is used to control the temperature of the chamber body  102  during processing and substrate transfer. The temperature of the chamber body  102  is important to prevent unwanted condensation of the gas or byproducts on the chamber walls. Exemplary heat transfer fluids include water, ethylene glycol, or a mixture thereof. An exemplary heat transfer fluid may also include nitrogen gas. 
         [0021]    The chamber body  102  can further include a liner  114  that surrounds the support assembly  106 . The liner  114  is preferably removable for servicing and cleaning. The liner  114  can be made of a metal such as aluminum, or a ceramic material. However, the liner  114  can be any process compatible material. The liner  114  can be bead blasted to increase the adhesion of any material deposited thereon, thereby preventing flaking of material which results in contamination of the processing chamber  100 . 
         [0022]    In one or more embodiments, the liner  114  includes one or more apertures  116  and a pumping channel  118  formed therein that is in fluid communication with a vacuum system. The apertures  116  provide a flow path for gases into the pumping channel  118 , which provides an egress for the gases within the processing chamber  100 . The apertures  116  allow the pumping channel  118  to be in fluid communication with a processing region  120  within the chamber body  102 . The processing region  120  may be defined by a lower surface  122  of the lid assembly  104  (e.g., a faceplate  124 ) and an upper surface  126  (e.g., a substrate receiving surface) of the support assembly  106 . The processing region  120  may be surrounded by the liner  114 . The apertures  116  may be uniformly sized and evenly spaced about the liner  114 . However, any number, position, size or shape of apertures may be used, and each of those design parameters can vary depending on the desired flow pattern of gas across the substrate receiving surface. 
         [0023]    The vacuum system can include a vacuum pump  128  and a throttle valve  130  to regulate flow of gases through the processing chamber  100 . The vacuum pump  128  is coupled to a vacuum port  132  disposed on the chamber body  102  and therefore, in fluid communication with the pumping channel  118  formed within the liner  114 . 
         [0024]    The support assembly  106  comprises a body  133  that includes an electrostatic chuck with a heater  134  embedded therein. The body  133  may comprise an electrically conductive material such as aluminum or a dielectric material such as a ceramic material. The support assembly  106  includes a puck  136  disposed on the body  133  that may be formed of a dielectric material, such as a ceramic material. The puck  136  (e.g., an electrostatic chuck) comprises a chucking electrode  138  that may be an electrically conductive mesh material adapted to couple with RF power. The chucking electrode  138  may comprise a mesh of a metal or metal alloy that is embedded within the puck  136 . The chucking electrode  138  may be configured as a mono-polar electrode or a bi-polar electrode. The heater  134  may include inner heating elements  135 A and outer heating elements  135 B. The heater  134  may comprise a resistive heating element comprising a metal or metal alloy that is embedded within the body  133  beneath the chucking electrode  138 . 
         [0025]    A shaft  140  of the support assembly  106  may be coupled to an actuator that may vary a distance between the faceplate  124  of the lid assembly  104  and the substrate receiving surface  126  of the support assembly  106 . The shaft  140  may include a heater rod  142  that electrically couples to the heater  134 . The shaft  140  may be at least partially surrounded by a cooling hub  144  that may cool the shaft  140  during operation. Bellows  141  are sometimes utilized to promote sealing of the processing region  120  between the shaft  140  and the chamber body  102 . 
         [0026]    In operation, a substrate (not shown) may be chucked to the substrate receiving surface  126  of the support assembly  106 . RF power from a RF system  126  is applied to the lid assembly  104  which travels to the faceplate  124  of the lid assembly  104 . The support assembly  106  may function as an electrode relative to the faceplate  124  of the lid assembly  104  and any gases between the faceplate  124  and the substrate receiving surface  126  of the support assembly  106  may be excited into a plasma in order to etch the substrate and/or deposit materials thereon. As indicated schematically by arrows, returning RF power travels along one or more surfaces of the support assembly  106 , portions of the chamber body  102 , portions of the shaft  140 , portions of surfaces of the bellows  141 , surfaces of the liner  114 , and surfaces of the cooling hub  144  in order to return to the RF system  146 . 
         [0027]    The support assembly  106  strongly impacts process results in the processing chamber  100 . For example, the support assembly  106  maintains uniform temperature of a substrate thereon, provides RF ground for plasma formation, as well as electrostatically chucking the substrate. The support assembly  106  also provides repeatable, adjustable distances relative to the faceplate  124 . However, one process parameter during RF application includes the impedance of the support assembly  106 . Measuring the impedance of the support assembly  106  may determine operating parameters thereof. In one implementation, a testing apparatus and method is devised to determine impedance of the support assembly  106  and therefore provide a metric of whether the support assembly  106  is acceptable or not fit for service. In another implementation, a support assembly  106  is provided that has acceptable electrical characteristics according to methods described herein. 
         [0028]      FIG. 2  is a schematic side view of one implementation of a test fixture  200  disposed on a support assembly  106  that may be used in the processing chamber  100  of  FIG. 1 . The fixture  200  includes a ground plane  205  that may comprise metallic plate  210 . The metallic plate  210  may be aluminum. The ground plane  205  is couple to the chamber body  102  (sidewall  110 ) by one or more straps  215 . A conductive plate  220  may be disposed on or adjacent to the substrate receiving surface  126  of the support assembly  106 . The conductive plate  220  may be electrically insulated from the ground plane  205  by a dielectric spacer  225 . The dielectric spacer  225  may be made of polymer material such as polytetrafluoroethylene (PTFE) or other suitable polymeric material. A conductor  230 , such as a wire or cable, may be electrically coupled to the metallic plate  210 . The conductor  230  may extend through an opening in the ground plane  205  and the dielectric spacer  225  to be exposed at an interface  235 . A network analyzer  240  may be coupled to the conductor  230  of the fixture at the interface  235 . A RF power is applied to the support assembly  106  by the network analyzer  240  via the conductor  230 . The network analyzer  240  may provide a RF signal between about 10 kHz to about 104 MHz. The heater rod  142  may be shorted to the shaft  140  in order to test the support assembly  106 . 
         [0029]      FIG. 3  shows one embodiment of an equivalent test circuit  300  provided by the fixture  200  shown in  FIG. 2 . Values of inductance (plane (L)  305  and strap (L)  310 ) and capacitance (C)  315  may be determined in order to determine impedance (Z)  320  between the support assembly  106  and the chamber body  102 . The effects of the fixture  200  should be accounted for and excluded to determine  320 . For example, the values of inductance ( 305  and  310 ) and capacitance ( 315 ) may be calculated out of the circuit  300  to determine impedance  320 . In one example, inductance of the plane (L)  305  may be about 5.31 nanohenrys (nH), inductance of the strap (L) may be about 7.86 nH, and capacitance of the dielectric spacer  225  (e.g.,  315 ) may be about 368 picofarads (pF). These values may be excluded to determine impedance ( 320 ). 
         [0030]      FIG. 4  is a schematic side view of one embodiment of a measurement jig  400  for determining impedance of a support assembly  106 . The jig  400  may be used for mounting the support assembly  106  therein after removal from a chamber or before installation of the support assembly  106  into a chamber. The jig  400  includes a body  405  that resembles the chamber body  102  of the processing chamber  100  shown in  FIG. 1 . The body  405  may be made of aluminum or other conductive metal. The body  405  includes sidewalls  410  where the test fixture  200  shown in  FIG. 2  may be fastened (using fasteners  415  such as bolts or screws). The body  405  also includes an opening  420  where the shaft  140  of the support assembly  106  may be inserted. The opening  420  may be sized to match dimensions of the cooling hub  144  similar to the mounting interface shown in  FIG. 1 . 
         [0031]    The network analyzer  240  may be coupled to the conductor  230  of the fixture at the interface  235  and RF power may be applied to the support assembly  106  as described in  FIG. 2 . Impedance of the support assembly  106  may be determined as described above and the support assembly  106  may be approved for service or rated as non-usable within a particular system based on the determined impedance value. According to embodiments disclosed herein, impedance of the support assembly  106  may be determined such that multiple support assemblies having a substantially identical impedance may be provided, and the support assemblies having a substantially identical impedance may be utilized in a respective chamber in a tool. “Substantially identical” in this context is defined as an impedance of multiple support assemblies  106  that is within +/−3%. The substantially identical impedance of the multiple support assemblies may be used to provide chamber matching without the use of additional hardware. 
         [0032]      FIG. 5  is a schematic view of one embodiment of a fixture calibration jig  500  that may be used to test the fixture of  FIG. 2 or 4 . The calibration jig  500  includes a body  505  that may be aluminum, or another conductive metal. An upper surface  510  of the body  505  may make electrical contact with the conductive plate  220  of the fixture  200  in order to test electrical characteristics of the test fixture  200 . For example, the calibration jig  500  may measure short conditions and/or open conditions of the test fixture  200 . 
         [0033]      FIG. 6  is a schematic top plan view of a processing tool  600  according to one implementation. The processing tool  600 , such as a cluster tool as shown in  FIG. 6 , includes a pair of front opening unified pods (FOUPs)  605  for supplying substrates, such as semiconductor wafers, that are received by robotic arms  610  and placed into load lock chambers  615 . A transfer robot  620  is disposed in a transfer chamber  625  coupled to the load lock chambers  615 . The transfer robot  620  is used to transport the substrates from the load lock chamber  615  one or more of a plurality of processing chambers  630 A,  630 B,  630 C,  630 D,  630 E and  630 F coupled to the transfer chamber  625 . 
         [0034]    The processing chambers  630 A,  630 B,  630 C,  630 D,  630 E and  630 F may include one or more system components for depositing, annealing, curing and/or etching a film on the substrate. Each of the processing chambers  630 A,  630 B,  630 C,  630 D,  630 E and  630 F include a support assembly  106  adapted to support a substrate  635  thereon. In one configuration, pairs of the processing chambers (e.g.,  630 A and  630 B,  630 C,  630 D) may be used to deposit a film on a respective substrate utilizing the same recipe to produce an identical product. As such, process conditions should be substantially similar in each of the processing chambers  630 A,  630 B,  630 C,  630 D,  630 E and  630 F. “Substantially” in this context is defined as a match between chambers that is within +/−3%. 
         [0035]    Each support assembly  106  of the processing tool  600  may have a similar impedance as confirmed using the embodiments as disclosed herein. As such, chamber matching is achieved in the processing tool  600  such that a substantially identical product may be provided on each substrate  635  in each of the processing chambers  630 A,  630 B,  630 C,  630 D,  630 E and  630 F. In particular, RF power to each of the processing chambers  630 A,  630 B,  630 C,  630 D,  630 E and  630 F may be substantially the same without the use of additional hardware. “Substantially” in this context is defined as providing RF power to each chamber that is within +/−3%. 
         [0036]    The implementations above provide a manufacturing protocol and/or design parameters for an electrostatic chuck that may be utilized in different chambers running the same recipe with minimal to no variation in product and/or substrate-to-substrate results. Impedance of the support assembly  106  may be determined such that support assemblies may be assessed as “good” or “bad” based on a particular RF power applied thereto based on historical data of “good” support assemblies. For example, a “bad” support assembly may have an impedance that is higher by 4% to 8% at 350 kHz, or lower by 3% at 13.56 MHz. Other indicators of a “bad” support assembly may include a mesh capacitance of 4% to 7% less than “good” meshes. The fixture  200  as described herein may also be modified for other support assemblies having various patterns of RF mesh. For example, radial mesh patterns (zones), concentric mesh patterns (zones), azimuthal mesh patterns (zones) can be matched with similar shapes in the conductive plate ( 220  of  FIG. 2 ) of the fixture  200 . The fixture  200  can also be modified to test different portions of a single RF mesh. For example, the conductive plate  220  of the fixture  200  can be made as the quadrant of a circle and be used to evaluate different quadrants of a circular RF mesh. 
         [0037]    While the foregoing is directed to implementations of the present disclosure, other and further implementations of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.