Patent Publication Number: US-2023154726-A1

Title: Magnetic housing systems

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a divisional application of U.S. patent application Ser. No. 16/671,330, filed Nov. 1, 2019, which claims priority to U.S. Provisional Application Ser. No. 62/755,847, filed on Nov. 5, 2018, and U.S. Provisional Application Ser. No. 62/888,332, filed on Aug. 16, 2019, which herein are incorporated by reference. 
    
    
     BACKGROUND 
     Field 
     Embodiments of the present disclosure generally relate to magnetic housing systems for controlling properties of generated plasma, and plasma enhanced deposition systems having the same. 
     Description of the Related Art 
     Plasma enhanced chemical vapor deposition (PECVD) is generally employed to deposit a film on a substrate, such as a semiconductor wafer. Plasma etching is generally employed to etch a film disposed on a substrate. PECVD and plasma etching are accomplished by introducing one or more gases into a process volume of a process chamber that contains a substrate. The one or more gases mix in a diffuser situated near the top of the chamber and are injected into a process volume through a plurality of holes or nozzles of the diffuser. During PECVD and plasma etching, the mixture of the one or more gases in the process volume are energized (e.g., excited) to generate a plasma by applying radio frequency (RF) energy to the chamber from one or more RF sources coupled to the chamber. An electric filed is generated in the process volume such that atoms of a mixture of the one or more gases present in the process volume are ionized and release electrons. The ionized atoms accelerated to the substrate support in PECVD facilitate deposition of a film on the substrate. The ionized atoms accelerated to the substrate support in plasma etching facilitate etching of a film disposed on the substrate. 
     The plasma generated in the process volume has properties, such as a density profile. A non-uniform density profile may cause non-uniform deposition or etching of the film on the substrate. In particular, the density profile of the plasma affects the deposition thickness or the etch profile of the film across a surface of the substrate. Accordingly, what is needed in the art are systems and a method for controlling the properties of the plasma generated in a process volume of a PECVD chamber. 
     SUMMARY 
     In one embodiment, a system is provided. The system includes a rotational magnetic housing having an upper plate, an outer sidewall, an inner sidewall defining a round central opening, and a lower plate. A plurality of retaining brackets are disposed in the rotational magnetic housing. Each retaining bracket of the plurality of retaining brackets disposed in the rotational magnetic housing with a distance d between each retaining bracket. The plurality of retaining brackets have a plurality of magnets removably disposed therein. Each magnet of the plurality of magnets is retained in a respective retaining bracket with a pitch p between each magnet of the plurality of magnets, and the plurality of magnets are configured to travel in a circular path when the rotational magnetic housing is rotated around the round central opening. 
     In another embodiment, a chamber is provided. The chamber includes a chamber body, a chamber lid having a gas distribution assembly, a substrate support positioned opposite the gas distribution assembly to define a process volume, the process volume having a center axis, a radio frequency (RF) source operable to be coupled to an electrode disposed within substrate support, and a rotational magnetic housing system having a rotational magnetic housing coupled to the chamber. The rotational magnetic housing has an upper plate, an outer sidewall, an inner sidewall defining a round central opening, and a lower plate. A plurality of retaining brackets are disposed in the rotational magnetic housing. Each retaining bracket of the plurality of retaining brackets disposed in the rotational magnetic housing with a distance d between each retaining bracket. The plurality of retaining brackets have a plurality of magnets removably disposed therein. Each magnet of the plurality of magnets is retained in a respective retaining bracket with a pitch p between each magnet of the plurality of magnets, and the plurality of magnets are configured to travel in a circular path when the rotational magnetic housing is rotated 
     In yet another embodiment, a chamber is provided. The chamber includes a chamber body, a chamber lid having a gas distribution assembly, a substrate support positioned opposite the gas distribution assembly to define a process volume, the process volume having a center axis, a radio frequency (RF) source operable to be coupled to an electrode disposed within substrate support, and an electromagnet magnetic housing system. The electromagnet magnetic housing system includes an electromagnet housing coupled to the chamber. The electromagnet housing has an upper plate, an outer sidewall, an inner sidewall defining a round central opening, a lower plate, and two or more conductive wires. Each of the conductive wires are coiled one or more times in respective portions of the electromagnet housing. Each of the conductive wires are operable to be individually connected to a power source. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       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 exemplary embodiments and are therefore not to be considered limiting of its scope, and may admit to other equally effective embodiments. 
         FIG.  1 A  is a schematic cross-sectional view of a plasma-enhanced chemical vapor deposition (PECVD) chamber having a rotational magnetic housing system with a rotational magnetic housing disposed outside of the chamber according to one embodiment. 
         FIG.  1 B  is a schematic top view of a rotational magnetic housing system according to one embodiment. 
         FIG.  1 C  is a schematic cross-sectional view of a PECVD chamber having an electromagnet housing system with an electromagnet magnetic housing disposed outside of the chamber according to one embodiment. 
         FIG.  1 D  is a schematic top view of an electromagnet housing system according to one embodiment. 
         FIG.  1    E is a schematic cross-sectional view of a PECVD chamber having an electromagnet system according to one embodiment. 
         FIG.  2    is a flow diagram of a method of controlling a density profile of plasma formed in a process volume of a PECVD chamber according to one embodiment. 
         FIGS.  3 A and  3 B  are graphs illustrating a density profile of a plasma in a process volume according to an embodiment. 
     
    
    
     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 
     Embodiments described herein provide magnetic and electromagnetic housing systems and a method for controlling the properties of plasma generated in a process volume of a PECVD chamber to affect deposition properties of a film. In one embodiment, a plurality of retaining brackets is disposed in a rotational magnetic housing of the magnetic housing systems. Each retaining bracket of the plurality of retaining brackets is disposed in the rotational magnetic housing with a distance d between each retaining bracket. The plurality of retaining brackets has a plurality of magnets removably disposed therein. Each magnet of the plurality of magnets is retained in a respective retaining bracket with a pitch p between each magnet of the plurality of magnets, and the plurality of magnets are configured to travel in a circular path when the rotational magnetic housing is rotated around the round central opening. 
       FIG.  1 A,  1 C, and  1 E  are schematic cross-sectional views of a plasma-enhanced chemical vapor deposition (PECVD) system  100  according to various embodiments. One example of the system  100  is a PRODUCER® system manufactured by Applied Materials, Inc., located in Santa Clara, Calif. It is to be understood that the system described below is an exemplary chamber and other systems, including systems from other manufacturers, may be used with or modified to accomplish aspects of the present disclosure. The system  100  includes a chamber  101   a  (e.g., first chamber) and a chamber  101   b  (e.g., second chamber). In one embodiment, which can be combined with other embodiments described herein, the chambers  101   a ,  101   b  share resources. For example, the chambers  101   a ,  101   b  may share at least one or more gas sources  144 , a mounting plate  112 , and a pump  150 . The chambers  101   a ,  101   b  are similarly configured. However, it is also contemplated that each of chambers  101   a ,  101   b  have dedicated resources. 
     In the embodiments of  FIG.  1 A , each chamber  101   a ,  101   b  has a rotational magnetic housing system  102  with a rotational magnetic housing  104  disposed outside of the chamber  101   a ,  101   b . In the embodiments of  FIG.  1 C , each chamber  101   a ,  101   b  has an electromagnet housing system  170  with an electromagnet housing  172  disposed outside of the chamber  101   a ,  101   b . In the embodiments of  FIG.  1 E , each chamber  101   a ,  101   b  has an electromagnet system  171  disposed in a spacer  114  of the chamber lid assembly  108 . While aspects of chamber  101   a  are discussed, it is to be understood that chamber  101   b  is similarly equipped. Reference numerals may be omitted on chamber  101   b  for clarity in  FIGS.  1 A , IC, and  1 E. 
     The chamber  101   a ,  101   b  has a chamber body assembly  106  and a chamber lid assembly  108 . The chamber body assembly  106  of the embodiments of  FIGS.  1 A and  1 C  includes a chamber body  110  coupled to a mounting plate  112 . The chamber lid assembly  108  of the embodiments of  FIGS.  1 A and  1 C  includes a spacer  114  having a first flange  118  coupled to the mounting plate  112  and a chamber lid  116  coupled to a second flange  120  of the spacer  114 . The chamber lid assembly  108  of the embodiments of  FIG.  1    E includes the spacer  114  having the first flange  118  coupled to the chamber body  110  and the chamber lid  116  coupled to a second flange  120  of the spacer  114 . The chamber lid  116  includes a gas distribution assembly  122 . The gas distribution assembly  122  is positioned opposite a substrate support assembly  124  defining a process volume  126  therebetween. The process volume  126  of the embodiments of  FIGS.  1 A and  1 C  is further defined by the chamber lid  116 , an interior wall  128  of the spacer  114 , mounting plate  112 , and chamber body  110 . The process volume  126  of the embodiments of  FIG.  1 E  is further defined by the chamber lid  116 , the interior wall  128  of the spacer  114 , and chamber body  110 . 
     The substrate support assembly  124  is disposed within the process volume  126 . The substrate support assembly  124  includes a substrate support  130  and a stem  132 . The substrate support  130  has a support surface  134  for supporting a substrate  165 . The substrate support  130  typically includes a heating element (not shown). The substrate support  130  is movably disposed in the process volume  126  by the stem  132  which extends through the chamber body  110  where the stem  132  is connected to a substrate support drive system  136 . The substrate support drive system  136  moves the substrate support  130  between an elevated processing position (as shown) and a lowered position that facilitates substrate transfer to and from the process volume  126  through a slit valve  138  formed though the chamber body  110 . In one embodiment, which can be combined with other embodiments described herein, the substrate support drive system  136  rotates the stem  132  and the substrate support  130 . 
     In one embodiment, which can be combined with other embodiments described herein, the gas distribution assembly  122  is configured to distribute gases uniformly into the process volume  126  of the chamber  101   a ,  101   b  to facilitate deposition of a film, such as an advanced patterning film, on the substrate  165  positioned on the substrate support  130  of the substrate support assembly  124 . In another embodiment, which can be combined with other embodiments described herein, the gas distribution assembly  122  is configured to distribute gases uniformly into the process volume  126  of the chamber  101   a ,  101   b  to facilitate etching of a film, such as an advanced patterning film, disposed on the substrate  165  positioned on the substrate support  130  of the substrate support assembly  124 . 
     The gas distribution assembly  122  includes a gas inlet passage  140 , which delivers gases from a flow controller  142  coupled to one or more gas sources  144  through a diffuser  146  suspended from a hanger plate  148 . The diffuser  146  includes a plurality of holes or nozzles (not shown) through which gaseous mixtures are injected into the process volume  126  during processing. The pump  150  is coupled to an outlet  152  of the chamber body  110  for controlling the pressure within the process volume  126  and exhausting byproducts from the process volume  126 . The diffuser  146  of gas distribution assembly  122  can be connected to an RF return (or ground) allowing RF energy applied to the substrate support  130  to generate an electric field within the process volume  126 , which is used to generate the plasma for processing of the substrate  165 . 
     A RF source  154  is coupled to the electrode  156  disposed within substrate support  130  through a conductive rod  158  disposed through the stem  132 . In one embodiment, which can be combined with other embodiments described herein, the electrode  156  is connected to the RF source  154  through a match box  163  having a match circuit for adjusting and a sensor for measuring electrical characteristics, such as voltage, current, and impedance, of the electrode  156 . The match circuit may facilitate adjustment of voltage, current, or impedance in response to a signal from the sensor. The diffuser  146  of gas distribution assembly  122 , which is connected to an RF return, and the electrode  156  facilitate formation of a capacitive plasma coupling. The RF source  154  provides RF energy to the substrate support  130  to facilitate generation of a capacitive coupled plasma between the substrate support  130  and the diffuser  146  of the gas distribution assembly  122 . When RF power is supplied to the electrode  156 , an electric filed is generated between the diffuser  146  and the substrate support  130  such that atoms of gases present in the process volume  126  between the substrate support  130  and the diffuser 146  are ionized and release electrons. The ionized atoms accelerated to the substrate support  130  facilitate deposition or etching of the film the substrate  165  positioned on a substrate support  130 . 
     As shown in  FIG.  3 A , the plasma has density profile  301  in the process volume  126 . The density profile  301  corresponds to an ion density  302  (ions/au 3 ) at a position  304  on a horizontal plane  167  in the process volume  126 . The density profile  301  includes a peak  303  corresponding to a maximum  305  of the ion density and a width  307  corresponding to a diameter of the plasma. One of the rotational magnetic housing system  102 , the electromagnet housing system  170 , and the electromagnet system  171  and the method described herein provide for control the density profile  301  the plasma to tune the uniformity and properties of the deposited or etched film. In the embodiments of  FIG.  1 A , rotational speed of the magnets, strength of the magnets (Gauss), and vertical position of the magnets can be adjusted to facilitate a corresponding adjustment in the density profile of the plasma. In the embodiments of  FIG.  1 C , flow of current of the electromagnet, strength of the electromagnet (Gauss), and vertical position of the electromagnet can be adjusted to facilitate a corresponding adjustment in the density profile of the plasma. In the embodiments of  FIG.  1 E , flow of current of the electromagnet and strength of the electromagnet can be adjusted to facilitate a corresponding adjustment in the density profile of the plasma. For example, adjustments can be made to one or more of vertical position of a plasma relative to a substrate, peak position of the density profile, or the value of the ion density at a particular location relative to a substrate. 
     As shown in  FIG.  1 A , a controller  164  coupled to the chamber  101   a ,  101   b  and the rotational magnetic housing system  102  is configured to control aspects of the chamber  101   a ,  101   b  and the rotational magnetic housing system  102  during processing. As shown in  FIG.  1 C , the controller  164  coupled to the chamber  101   a ,  101   b  and the electromagnet housing system  170  is configured to control aspects of the chamber  101   a ,  101   b  and the electromagnet housing system  170  during processing. As shown in  FIG.  1 E , the controller  164  coupled to the chamber  101   a ,  101   b  and the electromagnet system  171  is configured to control aspects of the chamber  101   a ,  101   b  and the electromagnet system  171  during processing. 
     As shown in  FIG.  3 A , the strength of one of the magnets  143  and a core material of the electromagnet (shown in  FIGS.  1 C and  1 E ) compresses the density profile  301  of the plasma in the process volume  126  and extends the sheath of the plasma toward the sidewalls of the chamber body  110 . Compressing the density profile  301  of the plasma results in a more uniform concentration of ions and radicals over the substrate  165  (at a relative height above the substrate) for a uniform deposition profile. Additionally, compression of the density profile  301  extends the plasma sheath radially outward towards the sidewalls of the chamber body  110 . Extending the sheath of the plasma to the sidewalls of the chamber body  110  provides a short and symmetrical path for RF energy to propagate from the sidewalls to a ground. The path for RF energy to propagate from the sidewalls to the ground improves current flow and reduces the amount of current required by the electrode  156  of the substrate support  130  through increased efficiency. The reduction of the amount of current required by the electrode  156  allows for the delivery of increased voltage to electrode  156  through increased efficiency. The increased voltage results in greater ionization of the plasma sheath for increased ion or radical bombardment of the substrate  165 . Increased ion or radical bombardment of the substrate  165  reduces the stress of the film to be deposited or etched. Additionally, the compression of the density profile  301  and the extension of the plasma sheath provides for a substantially uniform distribution of stress vectors of the deposited or etched film. 
       FIG.  1 B  illustrates a schematic top view of the rotational magnetic housing system  102 . Referring to  FIG.  1 A  and  FIG.  1 B , the rotational magnetic housing system  102  includes the rotational magnetic housing  104  configured to rotate about a center axis  103  of the process volume  126  to create static or dynamic magnetic fields. The magnetic fields modify the shape of the plasma, concentration of ions and radicals, and movement of concentration of ions and radicals to control the density profile  301  of the plasma within the process volume  126 . 
     The rotational magnetic housing system  102  with the rotational magnetic housing  104  is disposed outside of the chamber  101   a ,  101   b . The rotational magnetic housing system  102  includes an upper plate  105 , a lower plate  107  disposed opposite to the upper plate  105 , an inner sidewall  109 , an outer sidewall  113  disposed opposite the inner sidewall  109 , a housing lift system  168 , and a housing drive system  115 . The interior side  128  defines a round central opening. In one embodiment, which can be combined with other embodiments described herein, at least one of the upper plate  105 , lower plate  107 , and spacer  114  includes one or more channels (not shown) connected to a heat exchanger (not shown) to control a temperature profile of the rotational magnetic housing  104 . An exterior wall  162  of the spacer  114  includes a polymer material, such as PTFE (polytetrafluoroethylene). In one embodiment, which can be combined with other embodiments described herein, the exterior wall  162  is a sheet of polymer material. The polymer material of the exterior wall  162  of the spacer  114  allows the rotational magnetic housing  104  to rotate around the spacer  114  about the center axis  103  of the process volume  126 . 
     The rotational magnetic housing  104  includes a plurality of retaining brackets  129 . Each retaining bracket of the plurality of retaining brackets  129  is disposed in the rotational magnetic housing  104  with a distance d between each retaining bracket  129 . The plurality of retaining brackets  129  enables a plurality of magnets  143  to be disposed in or removed from the rotational magnetic housing  104 . In one embodiment, each magnet  143  of the plurality of magnets  143  is retained in a retaining bracket  129  with a pitch p between each magnet  143  of the plurality of magnets  143 . The pitch p corresponds to a distance between each adjacent magnet  143  of the plurality of magnets  143 . The pitch p tunes the magnetic fields generated by rotating the rotational magnetic housing  104 . In one embodiment, which can be combined with other embodiments described herein, each of the retaining brackets  129  is coupled to tracks  131 . The retaining brackets  129  are actuated such that each of the retaining brackets  129  are operable to slide along the tracks  131  in a radial direction to vary a horizontal distance  133  from each of the magnets  143  to the center axis  103  of the process volume  126 . 
     As shown in  FIG.  1 C , the electromagnet housing system  170  with the electromagnet housing  172  is disposed outside of the chamber  101   a ,  101   b . The electromagnet housing  172  includes an upper plate  173 , a lower plate  174  disposed opposite to the upper plate  173 , an inner sidewall  176 , an outer sidewall  175  disposed opposite the inner sidewall  176 , and a housing lift system  168 . The interior side  128  defines a round central opening. In one embodiment, which can be combined with other embodiments described herein, at least one of the upper plate  173 , lower plate  174 , and spacer  114  includes one or more channels (not shown) connected to a heat exchanger (not shown) to control a temperature profile of the electromagnet housing  172 . An electrically conductive wire  178  is disposed in the electromagnet housing  172  and is coiled around the spacer  114  one or more times to form a single electromagnet which circumscribes the spacer  114 . A power source  180  is coupled to the conductive wire  178  to flow current in a circular path about the process volume  126 . In one embodiment, which can be combined with other embodiments described herein, at least one turn of the conductive wire  178  coupled to tracks  181 . The tracks  181  are actuated such that each turn of the conductive wire  178  coupled to one of the tracks  181  is operable to slide along the tracks  181  in a radial direction to vary a horizontal distance  133  from the conductive wire  178  to the center axis  103  of the process volume  126 . As shown in  FIG.  1 E , the electrically conductive wire  178  is disposed in the spacer  114  and is coiled about the process volume  126  one or more times. 
     In one embodiment, as shown in  FIG.  1 B , which can be combined with other embodiments described herein, a first half  137  (e.g., encompassing about 180 degrees) of the rotational magnetic housing  104  has the magnets  143  with the north pole  141  oriented toward the process volume  126  and second half  139  (e.g., encompassing about 180 degrees) of the rotational magnetic housing  104  has the magnets  143  with the south pole  145  oriented opposite to the process volume  126 . As shown in  FIG.  3 B , the first half  137  and the second half  139  with opposite oriented magnets  143  provide for shifting of the peak  303  of the density profile  301 . The opposite polarities of the magnets  143  skews the B-field produced via the magnets  143 . The skewing of the B-field shifts the peak  303  of the density profile  301 . The shifting of the peak  303  corresponds to a shifting of the plasma sheath. The rotation of the rotational magnetic housing  104  facilitates a more uniform exposure of the substrate  165  to ions and radicals of the skewed plasma sheath. 
     The rotational magnetic housing  104  is coupled to the housing drive system  115 . The housing drive system  115  includes a belt  147  and a motor  149 . The rotational magnetic housing  104  includes a plurality of grooves  151  formed in an outer sidewall  113  of the rotational magnetic housing  104 . Each groove of the plurality of grooves  151  corresponds to a lug  155  of a plurality of lugs  155  of the belt  161 . The belt  161  is configured to be disposed around the rotational magnetic housing  104  and is coupled to the motor  149 , such as a brushless DC electric motor. The housing drive system  115  is configured to rotate the rotational magnetic housing  104  about the center axis  103  of the process volume  126  at a rotation rate. The rotation rate controls a current of the substrate  165  resulting from the modified magnetic fields. In one example, it is contemplated that each of chambers  101   a ,  101   b  includes individual housing drive systems  115 . In another example, it is contemplated that each of chambers  101   a ,  101   b  share a housing drive system  115 . 
     In some embodiments of  FIGS.  1 C and  1 E , which can be combined with other embodiments described herein, the conductive wire  178  includes at least one of air gaps in the core material of the conductive wire  178 , a varying cross sectional area of the core material, and a varying distance between each turn of the conductive wire  178 . The core material of a first half (e.g., encompassing about 180 degrees) of the conductive wire  204  may have more air gaps than a second half (e.g., encompassing about 180 degrees) of the conductive wire  178 . The core material of the first half of the conductive wire  178  may have a greater cross sectional area than the cross sectional area of the second half of the conductive wire  178 . The distance between each turn of the conductive wire  178  of the first half may be less that than the distance between each turn of the conductive wire  178  of the second half. The adjustment of at least one of the air gaps, cross sectional area, and distance between each turn of the conductive wire  178  skews the B-field produced via the flow current through the conductive wire  178 . The circular flow of current facilitates a more uniform exposure of the substrate  165  to ions and radicals of the skewed plasma sheath. 
     In other embodiments of  FIGS.  1 C  and  FIG.  1 E , which can be combined with other embodiments described herein, the electromagnet housing  172  ( FIG.  1 C ) and the electromagnet system  171  ( FIG.  1 E ) include two or more electrically conductive wires  178 . Each of the conductive wires  178  of the electromagnet housing  172  is disposed in a respective portion of the electromagnet housing  172 . In one embodiment, which can be combined with other embodiments described herein, the conductive wires  178  are equally spaced from each other in the electromagnet housing  172 . Each of the conductive wires  178  of the electromagnet system  171  is disposed in a respective portion of the spacer  110 . In one embodiment, which can be combined with other embodiments described herein, the conductive wires  178  are equally spaced from each other in the spacer  110 . Power sources  180  ( 180   a ,  180   b ,  180   c , and  180   d  as shown in  FIG.  1 D ) are individually coupled to each of the conductive wires  178 . The power sources  180  operable to be electrically are connectable to the controller  164 . The controller  164  is operable to sequentially turn on or off each of the power sources  180  and concurrently turn on or off each of the power sources  180  to control the supply of power to each of the conductive wires  178 . Concurrently turning off each of the power sources  180  enables shunting of magnetic fields produced by the electromagnets. In one example, a first conductive wire is coiled one or more times in a semi-circle and is disposed in a first half of the electromagnet housing  172  ( FIG.  1 C ) or spacer  110  ( FIG.  1 E ) corresponding to a first half of the process volume  126  to form a first electromagnet. A second conductive wire is coiled one or more times in a semi-circle and is disposed in a second half of the electromagnet housing  172  ( FIG.  1 C ) or spacer  110  ( FIG.  1 E ) corresponding to a second half of the process volume  126  to form a second electromagnet. The first and second electromagnets may have opposing polarities. 
     As shown in  FIG.  1 D , a schematic top view of the electromagnet housing system  170 , in one example, a first conductive wire  178   a  is coiled one or more times in a semi-circle having an angular arc of 90 degrees or less and is disposed in a first quadrant  179   a  of the electromagnet housing  172  corresponding to a first quadrant  126   a  of the process volume  126  to form a first electromagnet. A second conductive wire  178   b  is coiled one or more times in a semi-circle having an angular arc of 90 degrees or less and is disposed in a second quadrant  179   b  of the electromagnet housing  172  corresponding to a second quadrant  126   b  of the process volume  126  to form a second electromagnet. A third conductive wire  178   c  is coiled one or more times in a semi-circle having an angular arc of 90 degrees or less and is disposed in a third quadrant  179   c  of the electromagnet housing  172  corresponding to a third quadrant  126   c  of the process volume  126  to form a third electromagnet. A fourth conductive wire  178   d  is coiled one or more times in a semi-circle having an angular arc of 90 degrees or less and is disposed in a fourth quadrant  179   d  of the electromagnet housing  172  corresponding to a fourth quadrant  126   d  of the process volume  126  to form a fourth electromagnet. The first, second, third, and fourth electromagnets may have alternating polarities. 
     The housing drive system  115  and the rotational magnetic housing  104  are coupled to the housing lift system  168 . Coupling the housing drive system  115  and the rotational magnetic housing  104  to the housing lift system  168  facilities vertical adjustment of the rotational magnetic housing  104  relative to a substrate  165 . Coupling the electromagnet housing  172  to the housing lift system  168  facilities vertical adjustment of the electromagnet housing  172  relative to a substrate  165 . For example, a vertical distance  135 , defined by a plane formed through a center of each of the magnets  143  to the substrate  165 , can be increased or decreased to adjust properties of plasma maintained within a corresponding chamber  101   a  or  101   b . For example, a vertical distance  182 , defined by a plane formed through a center of the conductive wire  178 , can be increased or decreased to adjust properties of plasma maintained within a corresponding chamber  101   a  or  101   b . The housing lift system  168  is operable to raise and lower the rotational magnetic housing  104  and the housing drive system  115  simultaneously, however, individual actuation is also contemplated. Raising and lowering a vertical distance  135 ,  182  from the substrate  165  provides adjustment of the distance of the plasma sheath to the substrate  165 , and thus controls the movement of concentration of ions and radicals to control the uniformity and properties, such as stress, of the deposited or etched film. To facilitate vertical actuation, the housing lift system  168  may include one or more actuators, such as electric motors, stepper motors, screw drives with threaded rods, and the like, to facilitate vertical actuation relative to the mounting plate  112 . In one embodiment, which can be combined with other embodiments described herein, the motor  149  is coupled to the housing lift system  168  by a mount  157 . 
     In one embodiment, which can be combined with other embodiments described herein, the outer sidewall  113 ,  175  has a thickness  159 . The materials and the thickness  159  of the outer sidewall  113 ,  175  provide for confinement of the magnetic fields to the process volume  126  by controlling the magnetic permeability of the outer sidewall  113 ,  175 . As shown in  FIG.  1 E , the materials and the thickness of a shield  184  aligned with the conductive wire  178  and coupled to exterior wall  162  of the spacer  114  provide for confinement of the magnetic fields to the process volume  126 . Confinement of the magnetic fields to the process volume  126  mitigates influence of the magnetic fields on nearby process volumes of adjacent process chambers, thus improving process uniformity. In one embodiment, which can be combined with other embodiments described herein, as shown in  FIGS.  1 A and  1 C , the chamber  101   a ,  101   b  includes an actuated shield  186  operable to raise and lower such than an opening  190  of the body  188  of the actuated shield  186  is aligned with one of the conductive wire  178  and the magnets  143 . In another embodiment, which can be combined with other embodiments described herein, as shown in  FIG.  1 E , the chamber  101   a ,  101   b  includes an shield  192  with an opening  196  of the body  194  of the shield  192  aligned with the conductive wire. The materials and the thickness of the actuated shield  186  and the shield  192  provide for confinement of the magnetic fields to the process volume  126 . 
       FIG.  2    is a flow diagram of a method  200  of controlling the density profile  301  of plasma formed in the process volume  126  of a PECVD chamber. To facilitate explanation,  FIG.  2    will be described with reference to  FIGS.  1 A- 1 E . However, it is to be noted that PECVD systems other than the system  100  may be utilized in conjunction with method  200  and it is to be noted that magnetic housing assemblies other than the rotational magnetic housing system  102  may be utilized in conjunction with method  200 . 
     At operation  201 , a substrate  165  is disposed on the support surface  134  of the substrate support  130 . In one embodiment, the substrate is transferred into the chamber  101   a ,  101   b  through the slit valve  138  formed though the chamber body  110  and disposed on the substrate support  130 . The substrate support  130  is then raised by the substrate support drive system  136  to the elevated processing position in the process volume  126 . 
     At operation  202 , one or more gases are provided at a flow rate into the process volume  126  of the chamber  101   a ,  101   b . In one embodiment, the flow controller  142  delivers one or more gases from the one or more gas sources  144  to the diffuser  146 . The one or more gases mix and are injected into the process volume  126  through plurality of holes or nozzles of the diffuser  146 . In one embodiment, the one or more gasses are continuously provided to the diffuser  146 , mixed in the diffuser  146 , and injected into the process volume  126 . In another embodiment, the pump  150  maintains a pressure in the process volume. While pump  150  is shown in  FIG.  1 A  as coupled to both chambers  101   a ,  101   b , it is contemplated that each of chambers  101   a ,  101   b  may utilize a discrete pump  150 . 
     At operation  203 , RF power is applied to the mixture of the one or more gases. In one embodiment, the RF source  154  provides RF energy to the substrate support  130  to facilitate generation of the capacitive coupled plasma between the substrate support  130  and the diffuser  146  of the gas distribution assembly  122 . The RF power is supplied to the electrode  156  and an electric filed is generated between the diffuser  146  and the substrate support  130  such that atoms of gases present in the process volume  126  between the substrate support  130  and the diffuser  146  are ionized and release electrons. The ionized atoms are accelerated to the substrate support  130  to facilitate the deposition of or etching of a film on the substrate  165  positioned on the substrate support  130 . 
     At operation  204 , the density profile  301  of the plasma formed in a process volume  126  is adjusted. In one embodiment, which can be combined with other embodiments described herein, the rotational magnetic housing  104  of the rotational magnetic housing system  102  is rotated via the housing drive system  115  about the center axis  103  of the process volume  126  at the rotation rate. At least one of the rotation rate, the horizontal distance  133  from each of the magnets  143  to the center axis  103 , and the vertical distance  135  of a center of each of the magnets  143  to the substrate  165  may be adjusted during operation  204 . In one embodiment, which can be combined with other embodiments described herein, current is provided to the conductive wire  178  in a circular path. The vertical distance  135  may be adjusted by raising and lowering at least one of the rotational magnetic housing  104  and the substrate support  130 . The rotational magnetic housing  104  creates dynamic magnetic fields. The magnetic fields modify the shape of the plasma, concentration of ions and radicals, and movement of concentration of ions and radicals to control the density profile  301 , the ion density  302 , and the diameter of the plasma. Controlling the density profile  301 , the ion density  302 , and the diameter of the plasma the tunes the uniformity and properties of the deposited film. Each magnetic of the plurality of magnets  143  is retained in a retaining bracket with a pitch p between each magnetic of the plurality of magnets  143 . The pitch p corresponds to a distance between each adjacent magnet of the plurality of magnets  143 . The pitch p tunes the magnetic fields generated by rotating the rotational magnetic housing  104 . Adjusting the vertical distance  135  modifies the distance of the plasma sheath to the substrate, and thus controls the movement of concentration of ions and radicals to control the uniformity and properties, such as stress, of the deposited film. 
     In another embodiment, at least one of the current, power, the horizontal distance  133  from the conductive wire  178  to the center axis  103 , and the vertical distance  182  of a center of each of the conductive wire  178  to the substrate  165  may be adjusted during operation  204 . The vertical distance  182  may be adjusted by raising and lowering at least one of the electromagnet housing  172  and the substrate support  130 . The electromagnet housing  172  creates dynamic magnetic fields. The magnetic fields modify the shape of the plasma, concentration of ions and radicals, and movement of ions and radicals to control the density profile  301 , the ion density  302 , and the diameter of the plasma. Controlling the density profile  301 , the ion density  302 , and the diameter of the plasma the tunes the uniformity and properties of the deposited film. Adjusting the vertical distance  182  modifies the distance of the plasma sheath to the substrate, and thus controls the movement of ions and radicals to control the uniformity and properties, such as stress, of the deposited film. 
     In one embodiment, which can be combined with other embodiments described herein, at operation  204 , the first half  137  and the second half  139  of the rotational magnetic housing  104  have opposite oriented magnets  143 . In another embodiment, which can be combined with other embodiments described herein, at operation  204 , the adjustment of at least one of the air gaps, cross sectional area, and distance between each turn of the conductive wire  178  may be adjusted. In another embodiment, which can be combined with other embodiments described herein, at operation  204 , power is sequentially provided to two or more electromagnets having opposing or alternating polarities. 
     In some embodiments, the substrate support drive system  136  rotates the substrate support  130  about the center axis  103  of the process volume  126  at the rotation rate. The strength of the magnets  143  are selected to position a peak of a plasma profile in desired radial position above a surface of a substrate to be processed. In embodiments that include the opposite oriented magnets  143 , the B-field produced via the magnets  143  is skewed. In embodiments that include adjustment of at least one of the air gaps, cross sectional area, and distance between each turn of the conductive wire  178 , the B-field produced via the flow of current though the conductive wire  178  is skewed. In embodiments that include sequentially providing power to two or more electromagnets having opposing or alternating polarities, the B-field produced via the flow of current though the conductive wires  178  is skewed. The skewing of the B-field shifts the peak of the plasma sheath. However, during processing, the rotation of the magnets  143  and flow current through the conductive wire  178  in a circular path about the process volume  126  facilitates a more uniform exposure of the substrate to ions and radicals of the skewed plasma sheath. In other embodiments, the substrate is rotated, resulting in a uniform deposition profile. In contrast, conventional processes utilize a plasma profile in which the peak is centered above substrate. Such a configuration results in non-uniform deposition (e.g., center-heavy deposition), even with rotation of the substrate, due to the increased ion density at the center of the substrate relative to the radially-outward edges of a substrate. 
     It is contemplated that aspects of the disclosure may be utilized with permanent magnets, electromagnets, or a combination thereof. Additionally, it is contemplated that magnets may be arranged in a configuration of alternating polarities, or magnets of like-oriented polarities may be arranged in groups, such as groups encompassing about 180 degrees. 
     In summation, magnetic and electromagnetic systems and a method of controlling the density profile of plasma formed in a process volume of a PECVD chamber are described herein. In one embodiment, a rotational magnetic housing is configured to rotate about center axis of the process volume to create static or dynamic magnetic fields. The magnetic fields modify the shape of the plasma, concentration of ions and radicals, and movement of concentration of ions and radicals to control the density profile of the plasma. Controlling the density profile of the plasma tunes the uniformity and properties of a deposited or etched film. 
     While the foregoing is directed to examples of the present disclosure, other and further examples of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.