Abstract:
Embodiments disclosed herein generally related to a processing chamber, and more specifically a heat modulator assembly for use in a processing chamber. The heat modulator assembly includes a heat modulator housing and a plurality of heat modulators. The heat modulator housing includes a housing member defining a housing plane, a sidewall, and an annular extension. The sidewall extends perpendicular to the housing plane. The annular extension extends outward from the sidewall. The plurality of heat modulators is positioned in the housing member.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority from U.S. application Ser. No. 62/365,742, filed Jul. 22, 2016, which is hereby incorporated in reference in its entirety. 
     
    
     BACKGROUND 
     Field 
       [0002]    Embodiments described herein generally relate to a processing chamber, and more specifically, to a heat modulator assembly for use in a processing chamber. 
       Description of the Related Art 
       [0003]    In the fabrication integrated circuits, deposition processes are used to deposit films of various materials upon semiconductor substrates. These deposition processes may take place in an enclosed process chamber. Epitaxy is a deposition process that grows a thin, ultra-pure layer, usually of silicon or germanium on a surface of a substrate. Forming an epitaxial layer on a substrate with uniform thickness across the surface of the substrate can be challenging. For example, there are often portions of the epitaxial layer, where thickness dips or rises for an unknown reason. These variations in thickness degrade the quality of the epitaxial layer and increase production costs. 
         [0004]    Therefore, there is a need for an improved process chamber that improves substrate temperature profile. 
       SUMMARY 
       [0005]    Embodiments disclosed herein generally related to a processing chamber, and more specifically a heat modulator assembly for use in a processing chamber. The heat modulator assembly includes a heat modulator housing and a plurality of heat modulators. The heat modulator housing includes a housing member defining a housing plane, a sidewall, and an annular extension. The sidewall extends perpendicular to the housing plane. The annular extension extends outward from the sidewall. The plurality of heat modulators is positioned in the housing member. 
         [0006]    In another embodiment, a process chamber is disclosed herein. The process chamber includes a chamber body, a substrate support, an upper inner reflector, and a heat modulator assembly. The chamber body defines an interior volume. The substrate support is disposed in the chamber body. The substrate support is configured to support a substrate for processing. The upper inner reflector is disposed in the chamber body, above the substrate support. The heat modulator assembly is disposed in the upper inner reflector. The heat modulator assembly includes a heat modulator housing and a plurality of heat modulators. The heat modulator housing includes a housing member defining a housing plane, a sidewall, and an annular extension. The sidewall extends perpendicular to the housing plane. The annular extension extends outward from the sidewall. The plurality of heat modulators is positioned in the housing member. 
         [0007]    In another embodiment, a method of processing a substrate is disclosed herein. An epitaxial layer is formed on a surface of the substrate. A plurality of heating lamps heats the substrate. One or more heat modulators tune the rempearture of the substrate in a target area by heating the target area. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    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. 
           [0009]      FIG. 1  illustrates a side sectional view of a process chamber  100 , according to one embodiment. 
           [0010]      FIG. 2  illustrates a side sectional view of an upper light modulator assembly of the process chamber of  FIG. 1 , according to one embodiment. 
           [0011]      FIG. 3  illustrates a top view of the process chamber of  FIG. 1  having a heat modulator assembly, according to one embodiment. 
           [0012]      FIG. 4  illustrates a top view of the process chamber of  FIG. 1  having a heat modulator assembly, according to one embodiment. 
           [0013]      FIG. 5  illustrates a top view of the process chamber of  FIG. 1  having a heat modulator assembly, according to one embodiment. 
           [0014]      FIG. 6  illustrates a cross-sectional view of the heat modulator assembly, according to one embodiment. 
           [0015]      FIG. 7A  illustrates a cross-sectional view of the heat modulator assembly, according to one embodiment. 
           [0016]      FIG. 7B  illustrates a cross-sectional view of the heat modulator assembly, according to one embodiment. 
           [0017]      FIG. 7C  illustrates a cross-sectional view of the heat modulator assembly, according to one embodiment. 
           [0018]      FIG. 8  illustrates a heat modulator of the heat modulator assembly, according to one embodiment. 
           [0019]      FIG. 9  illustrates a heat modulator of the heat modulator assembly, according to one embodiment. 
           [0020]      FIG. 10  illustrates a heat modulator of the heat modulator assembly, according to one embodiment. 
       
    
    
       [0021]    For clarity, identical reference numerals have been used, where applicable, to designate identical elements that are common between figures. Additionally, elements of one embodiment may be advantageously adapted for utilization in other embodiments described herein. 
       DETAILED DESCRIPTION 
       [0022]      FIG. 1  is a side sectional view of a process chamber  100 , according to one embodiment. The process chamber  100  is configured to deposit epitaxial films on a substrate  101  disposed therein. The process chamber  100  includes a chamber body  102  having one or more sidewalls  103 , a bottom  104 , a top  106 , an upper dome  108 , and a lower dome  110 . The chamber body  102  defines an interior volume  111 . 
         [0023]    The process chamber  100  may further include a substrate support  112 , which may be a susceptor, disposed therein. The substrate support  112  is configured to support the substrate  101  during processing. The process chamber  100  further includes one or more lamps  114 . The one or more lamps  114  may be disposed above and/or below the substrate support  112 . In one embodiment, the lamps  114  may be tungsten filament lamps. The lamps  114  are configured to direct radiation, such as infrared radiation, through the lower dome  110  to heat the substrate  101  and/or the substrate support  112 . The lower dome  110  may be made of a transparent material, such as quartz. The process chamber may further include a lower outer reflector  116  and a lower inner reflector  118 . The lower outer reflector  116  is positioned beneath the lower dome  110 , at least partially surrounding the lower inner reflector  118 . The lower outer reflector  116  and the lower inner reflector  118  may be formed of aluminum and plated with a reflective material, such as gold. A temperature sensor  120 , such as a pyrometer, can be installed in the lower inner reflector  118  to detect a temperature of the substrate support  112  or the back side of the substrate  101 . 
         [0024]    The lamps  114  positioned above the substrate support  112  are configured to direct radiation, such as infrared radiation, through the upper dome  108  towards the substrate support  112 . The upper dome  108  may be formed from a transparent material, such as quartz. The process chamber  100  may further include an upper inner reflector  122  and an upper outer reflector  124 . The upper outer reflector  124  may at least partially surround the upper inner reflector  122 . The upper inner reflector  122  and the upper outer reflector  124  may be formed of aluminum and plated with a reflective material, such as gold. In one embodiment, the lamps  114  may be positioned in the upper outer reflector  124  but exterior to the upper inner reflector  122 . 
         [0025]    The process chamber  100  may further include a heat modulator assembly  125  having one or more heat modulators  126 . The heat modulator assembly  125  may be positioned within the upper inner reflector  122 . The heat modulators  126  are configured to increase the temperature of the substrate  101  at certain regions of the substrate  101  by fine tuning the substrate temperature. The heat modulators  126  are able to compensate for cold spots/rings on the substrate  101 , thus resulting in more uniform epitaxial growth. For example the thickness profile of SiP and SEG Si processes suggest cold spots and/or rings are 40-80 mm in width and 1-8 C in magnitude. Three examples of heat modulators  126  (heat modulators  800 ,  900 , and  1000 ) are discussed in more detail below, in conjunction with  FIGS. 8-10 . The three heat modulators are useful for processing different width of the substrate  101 . 
         [0026]    The process chamber  100  may be coupled to one or more process gas sources  130  that can supply the process gas used in the epitaxial depositions. The process chamber  100  can further be coupled to an exhaust device  132 , such as a vacuum pump. In some embodiments, the process gases can be supplied on one side (e.g., the left side of  FIG. 1 ) of the process chamber  100 . Gases may be exhausted from the process chamber  100  on an opposing side (e.g., the right side of  FIG. 1 ) to create a cross flow of process gases above the substrate  101 . The process chamber  100  may also be coupled to a purge gas source  134 . 
         [0027]      FIG. 2  illustrates a cross-sectional view of the heat modulator assembly  125 , according to one embodiment. The heat modulator assembly  125  includes a heat modulator housing  200  defining a housing plane  294 , a sidewall  291 , an annular extension  293 , and one or more heat modulators  126 . The sidewall  291  extends perpendicular to the housing plane  294 . The annular extension extends outward from the sidewall  291 . The heat modulator housing  200  may be positioned in the interior volume of the upper inner reflector  122 . The heat modulator housing  200  is configured to be retrofitted in the upper inner reflector  122 . The retrofit design is configured to extend the current hardware&#39;s capability. In the embodiment shown in  FIG. 2 , the one or more heat modulators  126  are vertical lamps  202 , i.e. the one or more heat modulators  126  have a major axis  299  parallel to the sidewall  291  of the heat modulator housing  200 . The vertical lamps  202  are disposed in the heat modulator housing  200 . In one embodiment, the vertical lamps  202  may be positioned in a tube  204 . The tube  204  may be formed from a reflective material, such as gold. In another embodiment, the tube  204  may include a coating of reflective material. In yet another embodiment, the lower surface of the housing  200  may include a reflective coating as well. The vertical lamps  202  may be positioned near the upper dome  108 . In one embodiment, the vertical lamps  202  may be positioned as close to the upper dome  108  as possible. 
         [0028]    Several factors may affect the tuning capabilities of the vertical lamps  202 . In one embodiment, the spacing, S, between the vertical lamps  202  may impact the area of interest on the substrate  101  that will receive radiation from the lamps  202 . For example, increasing the spacing, S, by about 20% changes. In another embodiment, a diameter, D, of the tube  204  affects the intensity of the radiation directed towards the substrate  101 . For example, decreasing the diameter, D, by about 20% changes. In general, the spacing, S, between vertical lamps may be constant or non-constant. For example, the spacing between the vertical lamps  202  may be closer near a center of the upper inner reflector  122  compared to the spacing between vertical lamps  202  near a periphery of the upper inner reflector. Alternatively, the spacing between the vertical lamps  202  may be closer near the periphery of the upper inner reflector  122  compared to spacing of the vertical lamps  202  near the center of the upper inner reflector  122 . In one embodiment, the spacing between vertical lamps  202  closer to the center of the upper inner reflector  122  is about 2 cm, and the spacing between the vertical lamps  202  near the periphery of the upper inner reflector  122  is about 4 cm. Additionally, the tubes  204  may include similar spacing as the vertical lamps  122 . For example, the spacing between the tubes  204  may be closer near a center of the upper inner reflector  122  compared to the spacing between tubes  204  near a periphery of the upper inner reflector  122 . Alternatively, the spacing between the tubes  204  may be closer near the periphery of the upper inner reflector  122  compared to spacing of the tubes  204  near the center of the upper inner reflector  122 . 
         [0029]    As shown in  FIG. 2 , heating lamps  114  may be positioned about the upper inner reflector  122 . In one embodiment, the vertical lamps  202  may be positioned on a same level as the heating lamps  114 . Positioning of the vertical lamps  202  with respect to the heating lamps  114  may also have an effect on the irradiance profile of the substrate  101 . 
         [0030]    Each vertical lamp  202  generally extends along a longitudinal axis of the tube  204  from a first end of the vertical lamp  202  to a second end thereof. The first end may be 1-10 mm from a corresponding end of the tube  204 , and the second end may be 1-20 mm from the tube opening. Recess depth of the vertical lamps  202  within the tubes  204  may be constant, or may vary according to any pattern or relationship. For example, in one embodiment a first plurality of vertical lamps  202  are recessed a first depth within their respective tubes  204  and a second plurality of vertical lamps  202  are recessed a second depth, different from the first depth, within their respective tubes  204 . In one embodiment, the housing  200  may include a conduit  280  formed therein. The conduit  280  may be configured to flow a cooling fluid through the sidewalls of the housing  200 . In another embodiment, the conduit  280  of the housing may be in fluid communication with a second fluid conduit (not shown) in the housing  200 . Let&#39;s also throw an optional conduit into the housing  200  to flow cooling fluid. They might eventually want that. Fluid goes in and out at the top. Could also flow through the walls of the inner reflector down to the housing  200 . 
         [0031]      FIG. 3  illustrates a top view of the process chamber  100  having the heat modulator assembly  125  according to one embodiment. The lamps  114  are shown horizontally surrounding the upper inner reflector  122 . In one embodiment, the lamps  114  are oriented with a major axis along a chamber radius. The lamps  114  extend between the upper outer reflector  124  and the upper inner reflector  122 . In the embodiment of  FIG. 3 , the upper inner reflector  122  has a circular shape and the upper outer reflector  124  has a sectionally linear shape with corners, thus forming an enclosure around the lamps  114  The heat modulator housing  200  is shown with a single-axis formation  302 . The heat modulator housing  200  houses the heat modulators  126  in the interior of the upper inner reflector  122  along a single-axis in a vertical manner. In one embodiment, the heat modulators  126  are arranged in two rows  322 ,  324  and six columns  326 ,  327 ,  328 ,  329 ,  330 ,  331 , extending in a direction perpendicular to the plane in  FIG. 3 . Three ( 326 - 328 ) of the six columns  326 - 331  are positioned on a first side  334  of the heat modulator housing  200 . Three ( 329 - 331 ) of the six columns  326 - 331  are positioned on a second side  336  of the heat modulator housing  200 . The first column  326  of heat modulators  126  on the first side  334  and the first column  331  of heat modulators  126  on the second side  336  are positioned about 75 mm away from a center, C, of the heat modulator housing  200 . The last column  328  of heat modulators  126  on the first side  334  and the last column  329  of heat modulators  126  on the second side  336  are positioned about 25 mm from the center, C, of the heat modulator housing  200 . The heat modulators  126  may be spaced such that the heat modulators  126  may direct radiation to specific areas of interest on the substrate  101 . For example, as shown in  FIG. 2 , the heat modulators  126  are arranged in two clusters  304 ,  306 . Each cluster  304 ,  306  includes three pairs of heat modulators  126 . In one embodiment, the pairs of heat modulators  126  are spaced about 30 mm apart. The heat modulator housing  200  having the single-axis formation  302  is capable of other light modulator arrangements. 
         [0032]      FIG. 4  illustrates a top view of the process chamber  100 , according to another embodiment. The heat modulator housing  200  has a two-axis formation  400 . The two-axis formation  400  is configured such that heat modulators  126  may be positioned along a first axis  402  and a second axis  404  of the heat modulator housing  200 . The different heat modulator housing  200  shape impacts the irradiance profile generated by the heat modulators  126 . The two-axis formation has four arm structures  412 - 416 , each arm structure  412 - 416  having the same number of heat modulators—in the embodiment of  FIG. 4 , three heat modulators—although the number of heat modulators in each arm structure could be different. In one embodiment, the distance from a center of formation  400  to a first heat modulator  126  in each arm structure may be 75 mm. In one embodiment, the distance from the last heat modulator  126  in each arm structure  410 - 416  (closest to the end of the corresponding arm structure) to the end of the corresponding arm structure is 0.1 mm to 20 mm. 
         [0033]      FIG. 5  illustrates a top view of the process chamber  100 , according to another embodiment. The heat modulator housing  200  has a multi-axis formation  500 . The multi-axis formation  500  is configured such that the heat modulators may be positioned along two or more axes in the interior of the upper inner reflector  122 . In the multi-axis formation  500 , the heat modulators  126  may be spaced about 50 mm apart such that heat modulators  126  positioned in two different axes do not align. As illustrated in the example of  FIG. 5 , the multi-axis formation  500  includes twelve heat modulators  126  arranged in four groups of three. Each group of three is aligned along a spiral curve from a location near a center of the formation  500  to a location near a periphery of the formation  500 . The location near the center is about 40% of the distance from the center to the edge of the upper inner reflector  122 . Each group has innermost  510 , middle  512 , and outermost  514  heat modulators. The innermost heat modulators  510  are arranged in a first square  520  (shown in phantom), the middle heat modulators  512  are arranged in a second square  522  (shown in phantom), and the outermost heat modulators  514  are arranged in a third square  524  (shown in phantom). The first square  520  has a first length and a first width. The second square  522  has a second length and a second width. The third square  524  has a third length and third length. The first length is less than the second length. The first width is less than the second width. The second length is less than the third length. The second width is less than the third width. In one embodiment the first square  520 , second square  522 , and third square  524  share the same center. The second square  522  is rotated relative to the first  520  and third squares  524 . The third square  524  is rotated relative to the first  520  and second  522  squares. In the embodiment of  FIG. 5 , the angle of the second square  522  relative to the first square  520  is about 40°, and the angle of the third square  524  relative to the second square  522  is about 30°. The relative positions of the heat modulators  126  in the formation  500  may be adjusted to achieve any desired spacing or orientation regarding the spiral curves and squares, including making the squares rectangles in some cases. 
         [0034]      FIG. 6  illustrates a cross-sectional view of the heat modulator assembly  125 , according to another embodiment. The heat modulator assembly  125  includes a heat modulator housing  600  and one or more heat modulators  126 . The heat modulator housing  600  is substantially similar to heat modulator housing  200 . In the embodiment shown in  FIG. 6 , the one or more heat modulators  126  are horizontal lamps  602 , i.e. the one or more heat modulators  126  have a major axis  630  that is perpendicular to the sidewall of the heat modulator housing  600 . The horizontal lamps  602  are disposed in the heat modulator housing  600 . In one embodiment, the horizontal lamps  602  are disposed in a tube  604 . One or more horizontal lamps  602  may be disposed in each tube  604 . The tube  604  may be formed from a reflective material, such as gold. The horizontal lamps  602  may be positioned such that the tube  604  is in communication with an opening  606  formed in the heat modulator housing  600 . The tubes  604  may be stacked in the heat modulator housing  600  in a stepped manner. In one embodiment, the tubes  604  may be stacked about a central opening  606 . For example, there may be three tubes  604  stacked on a first side of the central opening  606  and a three tubes  604  stacked on a second side of the central opening  606 . The stepped formation allows each opening to be in fluid communication between a given tube  604  and an exit surface of the heat modulator housing  600 . In one embodiment, each tube  604  is in communication with a single opening  606 . In another embodiment, one or more tubes  604  are in communication with a single opening  606 . The horizontal lamps  602  are configured to direct radiation down the openings  606  towards a surface of the substrate  101 . 
         [0035]      FIG. 7A  illustrates a cross-sectional view of the heat modulator assembly  125 , according to another embodiment. The heat modulator assembly  125  includes a heat modulator housing  700  and one or more heat modulators  126 . The heat modulator housing  700  is substantially similar to heat modulator housings  200  and  600 . The heat modulator housing  700  includes one or more ring shaped openings  704 . The one or more ring shaped openings  704  house the one or more heat modulators  126 . In the embodiment shown in  FIG. 7A , the one or more heat modulators  126  are in the form of linear lamps  702 . The linear lamps  702  may be arranged piecewise about the circumference of each ring shaped opening  704 . As illustrated in  FIG. 7A , the arrangement of linear lamps is axisymmetric. The one or more ring shaped openings  704  include a reflective surface  706 , which may be formed of gold. The ring shaped openings  704  have cross-sectional shape that creates a focus of radiation emitted near the ring shaped openings  704 . The shape may be circular, ellipsoidal, parabolic, hyperbolic, polyganized, or any mixture or intermediate thereof. For example,  FIG. 7B  illustrates a cross-sectional view of the heat modulator assembly  125  having openings  714  which are polyganized. The ring shaped openings  704  may be the same shape, with the same focal characteristics, or may have different shapes with different focal characteristics. For example, the focus of a ring shaped opening  704  may define a line, together with the filament  702  disposed in the ring shaped opening  704 , that is parallel to a side  720  of the upper inner reflector  122 , or that is not parallel to the side  720  of the upper inner reflector  122  according to any extent. The cross-sectional shape of a ring shaped opening  704  may be constant for the entire length thereof, or may vary according to any pattern. The linear lamps  702  may be positioned at different foci in the heat modulator housing  700 . In one embodiment, the filament (not shown) of the linear lamp  702  will be small and the focus is close to the reflective surface  706 . This results in more uniform coverage by locating the filament near the focus of a parabolic trench. For example, the filament will be about 2.5 mm in diameter, and the focus is 5 mm away from the reflective surface  706 . In one embodiment, the linear lamps  702  are positioned at the object plane and the substrate  101  is positioned at the image plane. 
         [0036]    In one embodiment, such as that shown in  FIG. 7C , the heat modulator assembly  125  includes one or more light emitting diode (LED) heat sources  720  positioned in the opening  704 . For example, one or more LED heat sources  720  may be positioned about a cooling tube  212 . 
         [0037]      FIG. 8  illustrates a heat modulator  800 , according to one embodiment. The heat modulator  800  may be used in place of heat modulator  126  in any of the above referenced embodiments. The heat modulator  800  includes a body  802 . The body  802  defines an interior volume  803 . The heat modulator  800  further includes a lamp  804 , a first convex lens  806 , and a second convex lens  808  disposed in the interior volume  803 . The first convex lens  806  is configured to collect and collimate rays from the lamp  804 . The second convex lens  808  is configured to converge the collimated rays on the substrate  101 . The heat modulator  800  is positioned such that the substrate  101  is positioned at the focus of the second convex lens  808 . Because the heat modulator  800  is positioned in a tube reflector, the tube reflector helps dissipate the energy of the rays outside of the collection angle of the first convex lens  806 . The heat modulator  800  is able to deliver low energy to a medium sized area on the substrate  101 . 
         [0038]      FIG. 9  illustrates a heat modulator  900 , according to one embodiment. The heat modulator  900  includes an lamp  902  and an ellipsoid reflector  904 . In one embodiment, the lamp  902  is a rapid thermal processing (RTP) lamp. The lamp  902  and the substrate  101  are positioned such that they lie at the foci of the ellipsoid reflector  904 . The rays emitted from the lamp  902  and collected by the ellipsoid reflector converge at the second focus, i.e., on the substrate  101 . The substrate will receive a portion of direct and scattered irradiation from the lamp  902 , without any focusing. The heat modulator  900  is configured to deliver a high energy to a large are of the substrate  101 . 
         [0039]      FIG. 10  illustrates a heat modulator  1000 , according to one embodiment. The heat modulator  1000  includes a diode laser  1002 , an optical fiber  1004 , and a convex lens  1006 . The diode laser  1002  is delivered through the optical fiber  1004 . The convex lens  1006  is mounted in front of the fiber  1004 . The convex lens is configured to control the laser spot size on the substrate  101 . The heat modulator  1000  is configured to deliver a high energy to a small area of the substrate  101 . 
         [0040]    Any of the heat modulators ( 800 ,  900 ,  1000 ) discussed above in  FIGS. 8-10  may be used in the heat modulator assembly discussed in  FIGS. 1-7 . Additionally, any combination of the heat modulators ( 800 - 1000 ) may be used at well. 
         [0041]    In operation, the process chamber forms an epitaxial layer on the surface of the substrate. The one or more heating lamps  114  are configured to heat at least a top surface of the substrate. In one embodiment, the one or more heating lamps  114  are also configured to heat a bottom surface of the substrate. The heat modulator assembly  125  selectively heats areas of interests on the substrate. For example, the heat modulators are configured to fine tune the substrate temperature such that typical cold spots, which occur during conventional processing, are avoided. 
         [0042]    While the foregoing is directed to specific embodiments, 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.