Patent Document

CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to U.S. Provisional Patent Application Ser. No. 62/047,417, filed on Sep. 8, 2014, and to U.S. Provisional Patent Application Ser. No. 62/128,731, filed Mar. 5, 2015, which herein is incorporated by reference. 
     
    
     BACKGROUND 
       [0002]    1. Field 
         [0003]    Embodiments described herein generally relate to apparatus and methods for improving gas distribution in a semiconductor process chamber. More specifically, embodiments described herein relate to a gas distribution plate. 
         [0004]    2. Description of the Related Art 
         [0005]    In semiconductor processing, various processes are commonly used to form films that have functionality in a semiconductor device. Among those processes are certain types of deposition processes referred to as epitaxy. In an epitaxy process, a gas mixture is typically introduced in a chamber containing one or more substrates on which an epitaxial layer is to be formed. Process conditions are maintained to encourage the vapor to form a high quality material layer on the substrate. 
         [0006]    In an exemplary epitaxy process, a material such as a dielectric material or semiconductor material is formed on an upper surface of a substrate. The epitaxy process grows a thin, ultra-pure material layer, such as silicon or germanium, on a surface of the substrate. The material may be deposited in a lateral flow chamber by flowing a process gas substantially parallel to the surface of a substrate positioned on a support, and by thermally decomposing the process gas to deposit a material from the gas onto the substrate surface. 
         [0007]    Cross-flow gas delivery apparatuses inject gas into the process chamber such that the gas flows laterally across the surface of the substrate while the substrate is rotated. However, the cross-flow delivery apparatus has limited center to edge tunability since all gases first cross the edge of the substrate. The inlet length of the cross-flow delivery apparatus is very long which causes premature cracking of lower temperature gases such as indium. The long flow path across the substrate in the cross-flow delivery apparatus causes gas by-product mixing during deposition/etching on the surface of the substrate. In some cases, the type and number of precursor species that may be introduced via the cross-flow gas delivery apparatus are limited. 
         [0008]    Thus, there is a need in the art for improved gas delivery apparatus. 
       SUMMARY 
       [0009]    Embodiments provided herein generally relate to an apparatus for gas distribution in a semiconductor process chamber. The apparatus may be a honeycomb gas distribution plate that has a plurality of through holes and a plurality of blind holes formed therein. Process gases are provided into a processing volume of the semiconductor process chamber through the through holes of the gas distribution plate. The blind holes can be utilized to control the temperature of the gas distribution plate. 
         [0010]    In one embodiment, a gas distribution plate is disclosed. The gas distribution plate includes a first surface and a second surface. The gas distribution plate further includes a plurality of through holes extending from the first surface to the second surface and a plurality of blind holes partially extending from the first surface. 
         [0011]    In another embodiment, a process chamber is disclosed. The process chamber includes one or more walls defining a processing region, and a gas distribution plate located in the processing region. The gas distribution plate includes a first surface and a second surface. The gas distribution plate further includes a plurality of through holes extending from the first surface to the second surface and a plurality of blind holes partially extending from the first surface. The process chamber further includes a substrate support located in the processing region. 
         [0012]    In another embodiment, a method for controlling a temperature of a gas distribution plate includes flowing a phase change material into a plurality of blind holes formed in the gas distribution plate, and controlling a pressure inside the blind holes so when the temperature of the gas distribution plate reaches a predetermined level, the phase of the phase change material changes. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    So that the manner in which the above recited features of the 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. 
           [0014]      FIGS. 1A-1B  illustrate schematic, cross-sectional views of a process chamber according to various embodiments. 
           [0015]      FIGS. 2A-2B  illustrate cross-sectional views of a gas distribution plate according to another embodiment. 
           [0016]      FIG. 3  illustrates a top view of the gas distribution plate of  FIGS. 2A and 2B . 
       
    
    
       [0017]    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 
       [0018]      FIG. 1A  illustrates a schematic, cross-sectional view of a process chamber  100  according to one embodiment. The process chamber  100  may be used to process one or more substrates, including the deposition of a material on an upper surface  116  of a substrate  108 . The process chamber  100  may include a chamber body  103  that may include a lower wall  114 , a side wall  136  and an upper wall  138 . One or more of walls  114 ,  136 ,  138  may define a processing region  156 . The upper wall  138  may be made of a reflective material or coated with a reflective material. The lower wall  114  may be transmissive to thermal radiation emitted by a heat source  145 , such as a plurality of lamps, and may be transparent to the thermal radiation, defined as transmitting at least  95 % of light of a given wavelength or spectrum. Materials useable for the lower wall  114  include quartz and sapphire. 
         [0019]    In one embodiment, the lower wall  114  is a quartz dome and is transparent to the emission spectrum of the plurality of lamps. A substrate support  106  may be disposed between the upper wall  138  and the lower wall  114 . A lower liner  164  may be coupled to the side wall  136 . The lower liner  164  may be formed from quartz, sapphire, or other materials compatible with processing in the chamber and the various process gases. The lower liner  164  may include a ledge  168  extending inward toward the substrate support  106 . The ledge  168  may have a recess  169  for receiving an edge ring  166 . The edge ring  166  may block a gap between the substrate support  106  and the lower liner  164  to prevent process gases from entering a region  158  defined by the substrate support  106 , the lower liner  164  and the lower wall  114 . 
         [0020]    The substrate  108  may be supported by the substrate support  106 , which is supported by a central shaft  132 . The substrate support  106  may be disposed in the processing region  156 . One or more lift pins  105  may lift the substrate  108  from the substrate support  106  as the substrate support  106  is lowered to a lower position, so the substrate  108  can be moved in and out of the process chamber  100  by a robot (not shown). 
         [0021]    A heat source  145 , such as an array of heat lamps  180  positioned in a lamphead  182 , may be disposed below the lower wall  114  to provide thermal energy to the substrate  108 . Words such as below, above, up, down, top, and bottom described herein do not refer to absolute directions, but to directions relative to a basis of the process chamber  100 . A cooling channel may be formed in the lamphead  182  for cooling the lamps  180 . Each lamp may be positioned in an opening  184  formed in the lamphead  182 , and the side walls  186  of the opening  184  may be coated with a reflective material for focusing and/or directing the thermal radiation emitted by the lamps  180 . 
         [0022]    A pumping ring  170  may be disposed on the lower liner  164 , and one or more exit ports  172  may be formed between the pumping ring  170  and the lower liner  164 . A gas distribution plate  128  may be disposed in the processing region  156 . The gas distribution plate  128  may be disposed on the pumping ring  170  and may be secured to the pumping ring  170  by any suitable fastening device, such as bolts or clamps. The gas distribution plate  128  may be made of a heat-resistant and chemical-resistant material, such as quartz or sapphire. An interface plate  130 , described in more detail below in connection with  FIGS. 2A and 2B , may be disposed on the gas distribution plate  128  for enclosing portions of the gas distribution plate  128 . The interface plate  130  may be bolted to the gas distribution plate  128 . The interface plate  130  may have a surface  109  facing the gas distribution plate  128  and the surface  109  may be coated with a reflective or absorptive coating, such as a dielectric reflective coating. Seals  190 , such as o-rings, may be disposed between the pumping ring  170  and the upper wall  138  and between the lower liner  164  and the lower wall  114 . 
         [0023]    During operation, one or more process gases may be introduced into the process chamber  100  via a gas feed  110 , reaching the upper surface  116  of the substrate  108  through the gas distribution plate  128 , and out of the process chamber  100  via the one or more exit ports  172 . To promote center-to-edge uniformity, the process gases can reach the center and edge of the upper surface  116  of the substrate  108  at the same time by using the gas distribution plate  128 . 
         [0024]      FIG. 1B  illustrates a schematic, cross-sectional view of the process chamber  100  according to one embodiment. Instead of having an upper wall  138  shown in  FIG. 1A , the process chamber  100  may include a structure  111  disposed on the side wall  136  and the pumping ring  170 . The structure  111  may include a plurality of compartments  113 , and each compartment  113  may include a gas feed  115  for introducing one or more process gases into the processing region  156  via the compartments  113  and the gas distribution plate  128 . The structure  111  may be made of a reflective or absorptive material. Alternatively, a surface  117  of the structure  111  facing the gas distribution plate  128  may be coated with a reflective or absorptive material. A single compartment  113  may cover one or more through holes formed in the gas distribution plate  128 . 
         [0025]      FIGS. 2A and 2B  illustrate cross-sectional views of the gas distribution plate  128 . As shown in  FIG. 2A , the gas distribution plate  128  may include a first surface  201  and a second surface  207  opposite the first surface  201 . The gas distribution plate  128  may include a plurality of through holes  202  extending from the first surface  201  to the second surface  207  and a plurality of blind holes  204  that partially extend from the first surface  201  toward the second surface  207 . The opening of each through hole  202  and each blind hole  204  may be circular, hexagonal, or any suitable shape. The opening of each through hole  202  may have the same shape as the opening of each blind hole  204 , or have a different shape as the opening of each blind hole  204 . The process gases flow through the through holes  202  to reach the substrate  108  ( FIG. 1 ). Each blind hole  204  may include side surfaces  203  and a bottom surface  205 . The bottom surface  205  may face the upper surface  116  of the substrate  108 . The side surfaces  203  and the bottom surface  205  of each blind hole  204  may be coated with a reflective or absorptive material to improve temperature control of the gas distribution plate  128 . 
         [0026]    During operation, the gas distribution plate  128  may be heated by the heat source  145  (shown in  FIG. 1 ). The process gases flowing into and out of the blind holes  204  provide temperature control of the gas distribution plate  128 . The gas distribution plate  128  may be formed by boring the through holes  202  and the blind holes  204  in a solid piece of material, such as a solid piece of quartz material. The gas distribution plate  128  may have a shape that corresponds to the shape of the substrate  108 . In one embodiment, the gas distribution plate  128  is circular. The gas distribution plate  128  may have a dimension, such as a diameter, that is greater than the corresponding dimension of the substrate  108 . In one embodiment, the substrate  108  is circular and has a diameter or about 300 mm, and the gas distribution plate  128  is also circular and has a diameter of about 400 to 600 mm. 
         [0027]    The pattern of the through holes  202  and the blind holes  204  may be configured so the process gases are evenly distributed to the upper surface  116  of the substrate  108  and the layer formed on the upper surface  116  of the substrate  108  is uniform. In one embodiment, the through holes  202  alternate with the blind holes  204  along a linear direction, as shown in  FIG. 2A . In one embodiment, the through holes  202  form a plurality of concentric rings, the blind holes  204  form a plurality of concentric rings, and the rings of the through holes  202  and the rings of the blind holes  204  are alternating. One or more temperature sensors, such as pyrometers, (not shown) may be placed inside one or more of the blind holes  204 . 
         [0028]      FIG. 2B  shows the gas distribution plate  128  having the interface plate  130  disposed thereon. The interface plate  130  may be disposed adjacent the first surface  201  of the gas distribution plate  128 , and may be fastened to the gas distribution plate  128  by a fastening device  222 , such as a bolt, as shown in  FIG. 2B . The interface plate  130  may have a plurality of through holes  211 , and each through hole  211  is aligned with a through hole  202  of the gas distribution plate  128 . Two or more openings  212   a,    212   b  may be formed in the interface plate  130  adjacent each blind holes  204 . A phase change material may be flowed into each blind hole  204  via an inlet  214  and a first opening  212   a,  and out of each blind hole  204  via a second opening  212   b  and the outlet  216 . The blind holes  204  may be in fluid communication with each other by a channel (not shown) formed on the interface plate  130  or by a channel formed in the gas distribution plate  128  around the through holes  202 . A pressure control system (not shown) may be employed to control the pressure inside the blind holes  204 . The pressure control system may vary the boiling point of the phase change material within each blind hole  204  in order to control the temperature of the gas distribution plate  128 . For example, the pressure inside the blind holes  204  may be controlled so the phase change material inside the blind holes  204  will change phase at a predetermined temperature. 
         [0029]    As the gas distribution plate  128  reaches the predetermined temperature, the phase change material inside the blind holes  204  changes phase, such as from a liquid to a vapor, which absorbs heat without increase the temperature of the gas distribution plate  128 . In this configuration, multiple set-points for the temperature of the gas distribution plate  128  can be achieved by adjusting the pressure of the phase change material, and agile thermal transients may be enabled within the gas distribution plate  128 . 
         [0030]    Alternatively, a cooling fluid may be circulated through the gas distribution plate  128  via the blind holes  204 . The cooling fluid, such as water or helium gas, may be flowed into the blind holes  204  via the inlet  214  and the first opening  212   a,  and out of the blind holes  204  via the second opening  212   b  and the outlet  216 . The openings  212   a,    212   b  formed in the interface plate  130  may be utilized for fluid communication among the blind holes  204 . In another embodiment, the blind holes  204  are in fluid communication with each other via a channel (not shown) formed in the gas distribution plate  128 . The channel may be connected to one or more openings (not shown) formed in the side surface  203  and/or the bottom surface  205 . A seal  220 , such as an o-ring, may be disposed between the gas distribution plate  128  and the interface plate  130  surrounding each blind hole  204 . 
         [0031]      FIG. 3  is a top view of the gas distribution plate  128  according to one embodiment. The gas distribution plate  128  includes the plurality of through holes  202  and the plurality of blind holes  204 . As shown in  FIG. 3 , each opening of the through holes  202  and blind holes  204  has a circular shape. The opening of the through holes  202  and blind holes  204  may have other suitable shapes, such as hexagonal, or a mixture of circular and hexagonal. 
         [0032]    The through holes  202  and the blind holes  204  may be formed in the gas distribution plate  128  in any suitable arrangement. In one embodiment, as shown in  FIG. 3 , the holes  202 ,  204  have a hexagonal tiling arrangement. The number of holes  202 ,  204  may be maximized by using a closest packing arrangement of the holes  202 ,  204 . The particular arrangement that achieves closest packing depends on the shape and dimension of the holes  202 ,  204 . For circular holes of similar size, as shown in  FIG. 3 , it is believed that a hexagonal tiling arrangement achieves a closest packing arrangement. A ratio of total area of through holes  202  to total area of blind holes  204  may be from about 0.5 to about 3.0, such as between about 0.8 to about 2.0, for example about 1.0, depending on the thermal control capability needed for a particular embodiment. 
         [0033]    The holes  202 ,  204  may have any predetermined sizing and spacing. In the embodiment shown in  FIG. 3 , the holes  202 ,  204  are circular, with diameter of about 0.5 mm to about 10 mm, such that the holes  202  have the same dimension as the holes  204 . The number of holes  202 ,  204  may be maximized by minimizing the thickness of the wall. In one embodiment, the wall thickness separating two adjacent holes  202 ,  204  is about 0.5 mm or more. With holes  202 ,  204  of dimension 1 cm and spacing of about 0.5 mm, a gas distribution plate  128  for processing a 300 mm wafer may have less than 50 to about 300 holes, depending on the size and spacing of the holes, of which 50 to 80% may be through holes  202  and 20 to 50% may be blind holes  204 . It should be noted, that a first plurality of the holes  202 ,  204  may have a first spacing, and a second plurality of the holes  202 ,  204  may have a second spacing different from the first spacing. The through holes  202  and the blind holes  204  may be staggered, i.e., same type of holes are not adjacent to each other, in order to prevent forming a pattern, such as a racetrack pattern, on the rotating substrate from overly radial gas distribution and/or a radial radiative effect associated with concentric rings of the through holes  202 . 
         [0034]    In alternate embodiments, the through holes  202 ,  204  may have different dimensions. For example, providing larger blind holes  204  may enable more robust thermal control of the gas distribution plate  128 . Additionally, the through holes  202  may have different dimensions to influence gas flow in different areas of the gas distribution plate  128 , if desired. Likewise, the blind holes  204  may have different dimensions to provide more or less thermal control in different areas of the gas distribution plate  128 , if desired. Thus, a first plurality of through holes  202  may have a first dimension, while a second plurality of through holes  202  has a second dimension. Similarly, a first plurality of blind holes  204  may have a third dimension and a second plurality of blind holes  204  may have a fourth dimension. In this embodiment, the first, second, third, and fourth dimensions may be the same or different in any desired combination. 
         [0035]    While the foregoing is directed to embodiments of the disclosure, other and further embodiments may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.

Technology Category: 8