Abstract:
A method and apparatus for launching microwave energy to a plasma processing chamber in which the required magnetic field is generated by a permanent magnet structure and the permanent magnet material effectively comprises one or more surfaces of the waveguide structure. The waveguide structure functions as an impedance matching device and controls the field pattern of the launched microwave field to create a uniform plasma. The waveguide launcher may comprise a rectangular waveguide, a circular waveguide, or a coaxial waveguide with permanent magnet material forming the sidewalls of the guide and a magnetization pattern which produces the required microwave electron cyclotron resonance magnetic field, a uniform field absorption pattern, and a rapid decay of the fields away from the resonance zone. In addition, the incorporation of permanent magnet material as a portion of the waveguide structure places the magnetic material in close proximity to the vacuum chamber, allowing for a precisely controlled magnetic field configuration, and a reduction of the amount of permanent magnet material required.

Description:
BACKGROUND OF THE INVENTION 
     1. Technical Field 
     The present invention relates generally to plasma-producing devices, in particular to electron cyclotron resonance plasma-producing devices. More particularly, the present invention relates to electron cyclotron resonance plasma-producing devices employing a combination of waveguide structures and permanent magnet assemblies. 
     2. Description of the Related Art 
     Plasma-producing devices are commonly employed in microelectronic device fabrication and similar industries requiring formation of extremely small geometries. Plasma-producing devices may be utilized in plasma-assisted processing to etch geometries into a substrate or to deposit a layer or layers of material on the substrate. 
     One class of such plasma-producing devices employs a magnetic field in conjunction with microwave energy. In these devices, plasma is produced from a working gas as a result of the inter-action of a magnetic field with an electric field. A microwave waveguide may be employed to inject microwaves, which have an associated electric field, into an evacuable chamber containing the working gas. The microwaves propagate into the chamber in a direction substantially perpendicular to the surface of the workpiece. The electric field associated with the microwaves is perpendicular to the direction of propagation, radially outward from a line following the direction of propagation of the microwaves. Plasma ions from the working gas are accelerated by the electric field along such radial lines. 
     A magnetic field is provided close to the point of injection in a direction generally aligned with the direction of microwave propagation, causing plasma electrons within the working gas to rotate around the direction of microwave propagation at right angles with the magnetic field. At the plane of resonance, the point at which the electric field associated with the microwave energy and the rotation of plasma electrons are in phase, the microwave electric field constantly accelerates the rotating plasma electrons. The energy of this acceleration dissociates molecules of the working gas into atoms and removes electrons from the atoms, creating ions and additional electrons. The ions then diffuse and impinge upon the exposed surface of the workpiece. 
     The requisite magnetic field may be provided by a single permanent magnet situated above the outlet of the microwave waveguide into the chamber. An adjusting element may be provided to vary the spatial relationship between the magnet and the waveguide opening, thus altering the location of the plane of resonance or “resonance zone” within the chamber. 
     Plasma uniformity across the surface of the workpiece is generally necessary to achieve etched geometries or deposited layers having relatively uniform dimensions from the center to the periphery of the workpiece surface. Prior art attempts to obtain plasma uniformity focusing on achieving a uniform magnetic field require very large and bulky magnets. Another drawback of the use of permanent magnets in plasma-producing devices relates to the necessity of positioning the microwave waveguide between the permanent magnet and the workpiece. This constrains placement of the permanent magnet with respect to the chamber, and as the magnet face is moved further from the chamber, larger, more expensive magnets are required to produce the requisite magnetic field. 
     In these plasma-producing devices, also referred to as electron cyclotron resonance plasma systems, the electron cyclotron resonance absorption occurs in a region of magnetic field strength where the gyromotion of the electrons is resonant with the excitation frequency. A fairly typical drive frequency is 2.45 GHz, which is resonant at a field of 875 G. 
     Microwave energy transmits from a source (at atmosphere) to the plasma (at vacuum) through waveguide structures. A microwave window, transparent to microwave energy, is required to separate the vacuum from atmosphere. This vacuum window is typically made of quartz. During processing, this window is exposed to the plasma process and may be either etched or subject to deposition, depending on the type of processing. Typical waveguide structures used include the standard rectangular or circular cross section waveguides and coaxial structures. 
     Efficient coupling of the microwave energy into the plasma requires that the load be matched to the source. The structure that couples the waveguide to the plasma chamber and plasma is termed a “launcher” or “coupler”. The coupling of the waveguide to the plasma chamber should also provide for a large area of uniform or symmetrical plasma generation. The field distribution coupling from the waveguide to the plasma should control the plasma uniformity to a large extent. This means uniform over an area as large as the workpiece. 
     In practice, the plasma production region connects to or feeds a larger process chamber in which the magnetic field directions or diffusion (perhaps within a magnetic bucket structure) acts to enhance uniformity. In this case, the plasma production region may not need to be of a large area, however uniformity remains a desirable trait. Usually uniformity over a disk region is desired. However, uniformity over an annular region or a region of field with mirror symmetry may be useful. In the case of uniformity over an annular region that produced by a circularly symmetric field distribution, the remaining structures may act to homogenize the annular plasma to a uniform disk at the workpiece. A field distribution with a mirror symmetry may still produce a time averaged circularly symmetric plasma, provided the mirror symmetry plane rotates with time. 
     The launcher is a matching device to efficiently transmit the microwave energy from the source to the vacuum vessel. Once transmitted into the vacuum vessel, the microwave energy will be absorbed by the plasma. For a given frequency (or plasma density) and magnetic field, only certain polarizations of electromagnetic waves will propagate in a plasma. Others will be absorbed or reflected. The electromagnetic waves are required to propagate to the resonance zone. A wave launched from low density and at a low magnetic field can not propagate to the high density. It is essential that the microwaves enter the chamber at a high magnetic field. 
     Generally, different modes will be absorbed and/or reflected by the plasma differently. Launching of modes that are absorbed by plasma enhance the tuning as well. Based on the above, a launcher should 1) send the waves into the chamber at a field greater than that required for resonance; 2) obtain a propagation parallel to the magnetic field in regions of high density; and 3) launches the appropriate field distribution mode. Therefore, it would be advantageous to have an improved electron cyclotron resonance plasma-producing device with an improved launcher for directing microwave energy into plasma in a chamber at a high magnetic field. 
     SUMMARY OF THE INVENTION 
     The present invention provides a method and apparatus for combining the magnetic field generation and microwave coupling or launching functions required for directing electron cyclotron resonance plasma into a single structure. The magnetic field generation and field optimization functions as well as the microwave transmission line, coupling to the vacuum chamber, and microwave wave launch are accomplished in an integrated structure. A magnetic field is generated by a permanent magnet structure and the permanent magnet material comprises one or more surfaces of a waveguide structure. The waveguide structure functions as an impedance matching device and controls the field pattern of the launched microwave field to create a uniform plasma. The waveguide launcher may comprise a rectangular waveguide, a circular waveguide, or a coaxial waveguide with permanent magnet material forming the sidewalls of the guide and a magnetization pattern which produces the required microwave electron cyclotron resonance magnetic field, a region of field strength greater than the critical field into which the microwaves are launched into the vacuum chamber, a uniform field absorption pattern, and a rapid decay of the fields away from the resonance zone. In addition, the incorporation of permanent magnet material as a portion of the waveguide structure allows for a precisely controlled magnetic field configuration, and a reduction of the amount of permanent magnet material required. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The novel features believed characteristic of the invention are set forth in the appended claims. The invention itself however, as well as a preferred mode of use, further objects and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying drawings, wherein: 
     FIG. 1 is a cross-sectional view of a portion of a plasma-producing device in accordance with a preferred embodiment of the present invention; 
     FIGS. 2A and 2B depict a launcher with a coaxial waveguide having an input or inlet; 
     FIGS. 3A and 3B are coaxial launchers with rectangular waveguide coupled to coaxial waveguide in accordance with a preferred embodiment of the present invention; 
     FIG. 4 depicts a launcher with a vacuum rectangular waveguide in accordance with a preferred embodiment of the present invention; 
     FIGS. 5A and 5B are illustrations of a launcher including vacuum coaxial waveguide in accordance with a preferred embodiment of the present invention; 
     FIGS. 6A and 6B are launchers with a mode converter in accordance with a preferred embodiment of the present invention; 
     FIGS. 7A and 7B are launchers with a rectangular waveguide in accordance with a preferred embodiment of the present invention; 
     FIGS. 8A and 8B are launchers with a vacuum waveguide inserted through a magnet in accordance with a preferred embodiment of the present invention; and 
     FIGS. 9A and 9B are launchers including a rectangular waveguide having a dielectric waveguide portion in accordance with a preferred embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION 
     With reference now to the figures, and in particular with reference to FIG. 1, a cross-sectional view of a portion of a plasma-producing device in accordance with a preferred embodiment of the present invention is depicted. For clarity, the components depicted are not drawn to scale and some elements of the total construction of a plasma-producing device are not depicted. Only so much of the structure as is necessary to understand the present invention is shown. 
     The plasma-producing device includes chamber  102  connected to a plasma source also referred to as launcher  104 . Launcher  104  has an output  104   b  connected to chamber  102 , which is an evacuable chamber. Launcher  104  is connected at an input  104   a  to a microwave power generation source and matching network (not shown) and conveys microwave energy produced by the generating source along its length to output  104   b.    
     A support  110  located in the interior of evacuable chamber  102  holds workpiece  112  during processing, and may be electrically biased to create an electric field attracting plasma ions from the resonance zone. Microwave energy exits launcher  104  at output  104   b  and propagates, preferably in a circular transmission mode, within chamber  102  in direction  114  substantially perpendicular to the exposed processing surface  112   a  of workpiece  112 . Close to the resonance zone, magnetic field lines  116  of the magnetic field generated by plasma source  104  are substantially aligned with the direction  114  of microwave energy propagation. That is, a line connecting the poles of the magnetic field is substantially aligned with, and along the same line as, the direction of propagation of the microwave energy. Microwave energy thus propagates from outlet  104   b  of launcher  104  in a direction aligned with a predominant axial magnetic field component produced by magnetic field source within launcher  104 , which extends through launcher  104  and into chamber  102 . A resonance zone is thus formed where the electric field associated with the microwave energy is in phase with the electron cyclotron motion of the plasma electrons. 
     In accordance with a preferred embodiment of the present invention, launcher  104  includes a waveguide and a permanent magnet combined in various configurations as described in further detail in the figures below. This permanent magnet is employed to generate a uniform plasma at the surface of workpiece  112 . Electron cyclotron resonance (ECR) plasma resonance requires a magnetic field determined by the resonance condition ω=eB/m, where ω is the angular frequency of the microwave energy (2πƒ, where ƒ is the frequency in Hertz), e is the well-known constant electronic charge (approximately 1.6×10 −19  C), B is the magnetic field strength in Gauss, and m is electron mass. For microwave energy at 2.45 GHz, a field strength of 875 G is required to create this resonance condition for electrons. Additionally, to achieve high ion density in the source and hence high ion currents at the workpiece, it is preferable to have a plasma density greater than the critical plasma density n c (an “overdense” plasma), where n c  is defined by:        ω   =       4      π                   n   c          e   2       m                            
     where ω is the desired angular frequency for microwave energy to be coupled to the plasma (here, 2π×2.45 GHz). For microwave energy with a frequency of 2.45 GHz, the resonance zone critical density is approximately 7×10 10  cm 3 . 
     Unfortunately, electromagnetic (EM) waves, including microwaves, generally will not propagate through regions of plasma density greater than the critical density. Instead, microwaves are reflected by regions exceeding the critical density and thus will not reach the resonance zone. The consequence is that once the plasma density reaches the critical density, additional power cannot be added to the plasma and the density cannot be increased above the critical density. One exception to this general result is right hand circularly polarized waves, which may propagate through plasma regions exceeding the critical density provided the magnetic field strength is greater than that required for resonance. This is described in many works on plasma physics. In the case of microwave energy at 2.45 GHz as described earlier, this requires a magnetic field strength greater than 875 G. By achieving the launch condition of magnetic field strength in excess of that required for resonance with microwave energy of a given frequency, referred to as high field injection, a resonance zone with a plasma density greater than the critical density may be formed within evacuable chamber  102 . High field injection is therefore a critical aspect of plasma source and launcher design. 
     Plasma uniformity is desirable in most plasma processing systems. There are two general sources of plasma nonuniformity: (1) nonuniformity in the absorption or plasma generating region; and (2) nonuniformity in the transport or movement of the plasma between the generation zone and the workpiece. Uniformity of plasma generation requires that a uniform absorption be achieved, including a uniform microwave field pattern and a uniform magnetic field (resonance zone) or some combination of non-uniformities, leading to a uniform absorption. Since the absorption and field patterns are interrelated, the ability to manipulate and control the magnetic field configurations (position of the resonance zone and local curvature of the resonance zone shape) on a local scale is critical to achieving a highly uniform absorption. “Local scale” refers to lengths smaller than the characteristics size of the permanent magnet. The magnetic field varies relatively slowly across lengths smaller than the characteristic size. The present invention provides a launcher that incorporates a magnetic source, which is a permanent magnet in the depicted example. 
     In practice, it may be extremely difficult to generate a perfectly uniform plasma. Thus, some degree of homogenization of the plasma between the source and the workpiece would be desirable. This would allow local nonuniformities in the source to diffuse out, thus “smearing out” any nonuniformities present in the source region. In a magnetized plasma, however, diffusion of charged particles may be influenced substantially by the magnetic field. In particular, diffusion perpendicular to the magnetic field lines is slowed proportionally to the inverse square of the magnetic field strength. Due to this, it is desirable to achieve as low a magnetic field as possible in the region between the plasma generation (resonance) zone and the workpiece. 
     Plasma variations at the workpiece may also arise from spatial variations in the divergence of the magnetic field. In a collisionless plasma (no cross field diffusion), plasma will travel down the magnetic field lines to the workpiece and the plasma density at any point will be proportional to the field strength at that point and the density at the corresponding position in the source. Assuming the plasma is generated uniformly at the resonance zone (875 G), the plasma density at a point where the field strength is 87.5 Gauss would be {fraction (1/10)}th that achieved at the resonance zone. If the field strength across the workpiece varies, the plasma density will vary commensurately given a uniform density in the resonance zone. At lower magnetic fields, cross field diffusion will be enhanced and the effects of magnetic field strength variations will be minimized. Thus, lower magnetic fields between the plasma generation zone and the workpiece, together with a controlled divergence of the field lines, is desirable. 
     Qualitatively, both electromagnets and permanent magnets have a dipole character at distances greater than the characteristic length scale of the magnet (radius for coil electromagnet, width dimensions for a permanent magnet. The crossover to a low field region thus depends on the magnet field source geometry. 
     Permanent magnet sources provide some advantage in achieving plasma process uniformity by a dense plasma region followed by a low field region. The lateral dimension of a permanent magnet is somewhat smaller than the lateral dimension of an electromagnet having corresponding strength (typically about 4-6 inches in diameter), so that the cross-over to the dipole field regime in the far field occurs somewhat closer to the magnet. Coupling of the microwave energy to a region of magnetic field strength of at least that required for resonance, therefore may occur in the near field, but not directly at the face. The magnetic field should thus fall from fairly high values, approximately 3000-5000 G, to a much smaller field strength at the working surface  112   a  of workpiece  112 . For magnetic field strengths of about 50-100 G at workpiece  112 , the gyro radius of a 3 electron-volts (eV) electron is 1 mm and the magnetic field still has a substantial effect on diffusion of the electron. If the magnetic field strength is lowered to 5 G, the gyro radius increases to 1 cm and the magnetic field has less effect. The larger gyro radius results in better diffusion and better plasma uniformity. 
     A magnetic bucket or multi-polar confinement bucket enhances the uniformity by reducing the stray fields. This can be accomplished by engineering various magnetic structures. Practically this is more easily accomplished when the resonance zone is close to the magnet. The present invention provides an apparatus in which the magnet is placed closer to the resonance zone through an improved launcher. The present invention provides launchers including microwave guides and permanent magnets for use in an electron cyclotron resonance plasma-producing device. Various structures for systems that lead to deposition of microwave absorbing films on the vacuum window are described. Illustrations are provided for structures in which the microwave window is placed in a remote location to minimize deposition on the window. Alternatively, methods of configuring the location of the resonance zone so that films depositing on the microwave window are removed, either during normal operation, or by manipulation of the location of the resonance zone during a “cleaning” process. 
     Turning now to FIG. 2A, a launcher including a coaxial waveguide is depicted in accordance with a preferred embodiment of the present invention. Launcher  104  contains a coaxial waveguide  200  with input  104   a  connected to a microwave source (not shown). FIG. 2B depicts a cross section of coaxial waveguide  200 . Coaxial waveguide  200  in launcher  104  includes permanent magnets  202  and  204 . These permanent magnets form the outer conductor and the inner conductor in which magnet  202  forms the outer conductor of coaxial waveguide  200  in launcher  104 ;and magnet  204  forms the inner conductor of coaxial waveguide  202  in launcher  104 . Permanent magnets  202  and  204  generate magnetism in direction  205 . In this example, permanent magnet material, forming permanent magnets  202  and  204 , actually form the sidewalls of the waveguide structure. In practice, it may be more appropriate to provide a high conductivity coating or inner surface, which is thick relative to the skin depth for microwaves, but thin relative to the magnet dimensions. Permanent magnets  202  and  204  have a magnetization orientation, which provides the requisite field for electron cyclotron resonance. In a preferred embodiment, as in FIG. 2A, the physical location of permanent magnets  202  and  204  close to electron cyclotron resonance region  206  within chamber  102  reduces the amount of magnetic materials required to produce magnetic field  208 . 
     Launcher  104  also includes a microwave window  210 , which is located at output  104   b  of launcher  104 . Microwave window  210  is a vacuum window, which is transparent to microwave energy in the depicted example. In this example, microwave window is located at output  104   b  and provides a barrier to create a vacuum in chamber  102 . Region  211  is not a vacuum region and in the depicted example is at an atmospheric pressure. Microwave window  210  is passes microwave energy and is used to introduce microwave energy from a source, which is typically at atmospheric pressure, to a plasma in chamber  102 , which is typically in a vacuum. In the depicted example, microwave window  210  is a quartz window although other materials may be used that allow passage of microwave energy, but maintain a vacuum for chamber  102  at output  104   b  of launcher  104 . Some other materials that may be used for microwave window  210  include, for example, without limitation, sapphire, alumina, or aluminum oxide. Microwave window  210  also may serve as a matching device between coaxial waveguide  200  and chamber  102 . The source injects the transverse electromagnetic mode in coaxial waveguide  202  that launches a circularly symmetrical microwave field in direction  212  into chamber  102 , which is a circular vacuum vessel in the depicted example. 
     Next with reference to FIGS. 3A and 3B, a coaxial launcher with a rectangular waveguide coupled to coaxial waveguide is illustrated in accordance with a preferred embodiment of the present invention. In FIG. 3A, launcher  104  includes a rectangular waveguide  300  coupled to a coaxial waveguide  302 . A cross-sectional view of coaxial waveguide  302  is illustrated in FIG.  3 B. Launcher  104  includes permanent magnets  304  and  306  with a cross-sectional view of launcher  104 . The output ports of high power microwave sources are usually in the form of rectangular waveguides. Transmission losses through rectangular waveguides are much lower than through a coaxial waveguide that is operating in the transverse electromagnetic mode. Efficient excitation of a coaxial launcher is facilitated by a rectangular waveguide. Launcher  104  in the depicted example has input  104   a  of rectangular waveguide  300  in launcher  104  connected to the source. The microwave energy is directed through rectangular waveguide  300  to coaxial waveguide  302  for transmission along direction  303  into chamber  102 , which is a circular chamber in the depicted example. 
     Permanent magnets  304  and  306  generate magnetic field  307 . These magnets are arranged to keep the field strength greater than 875 G up to 875 G resonance zone  308  within chamber  102 . Microwave window  310  is located between input  104   a  and output  104   b  in launcher  104 . This window may be used to form a vacuum region  311  located between microwave window  310  and output  104   b . Region  313  is not under a vacuum in this example. This window provides a barrier to gases from passing into or out of chamber  102 . Microwave window  310  is located in a remote location from chamber  102 . Microwave window  310  is position such that a line of sight access from to the microwave window  310  from chamber  102 . This positioning of microwave window  310  near input  104   a  within rectangular waveguide  300  in launcher  104  reduces deposition of materials on microwave window  310  during deposition and etching processes performed within chamber  102 . In addition, depletion of microwave window  310  is reduced during etching processes within chamber  102 . 
     Turning now to FIG. 4, a launcher with a vacuum rectangular waveguide in accordance with a preferred embodiment of the present invention. Launcher  104  in this example includes rectangular waveguide  400  machined into a cooled housing  414 . A microwave window  402  in launcher  104  is remotely located away from resonance zone  404 , which is an 875 G resonance zone. Microwave window  402  provides a barrier to gases while allowing microwave energy to pass. Microwave window  402  and output  104   b  define vacuum region  405  within rectangular waveguide  400 . 
     A permanent magnet  406  is located over rectangular waveguide  400  and is used to generate magnetic field  408 . Microwave energy is directed into chamber  102  along direction  410 . The magnetic field strength of magnetic field  408  is maintained at a level greater than 875 G in vacuum region  405  of rectangular waveguide  400  prior to being launched into the resonance vessel. Microwave window  402  is such that a line of sight access to chamber  102  is absent. The advantage of this launcher configuration is the remote location of microwave window  402  is such that deposition on the window is minimized. 
     Further, a cooling system  413  is used to cool launcher  104 . Cooling system  413  includes a recirculating fluid chiller  415 , which circulates cooled fluid through passages within housing  414 . This system allows for controlled temperature on the launcher surfaces and a reduced possibility of arcs and particle generation. 
     With reference now to FIGS. 5A and 5B, illustrations of a vacuum coaxial waveguide coupled in vacuum to a rectangular waveguide are depicted in accordance with a preferred embodiment of the present invention. In FIGS. 5A and 5B, launcher  104  includes a coaxial waveguide  500  in which permanent magnets are incorporated as part of coaxial waveguide  500 . In particular, coaxial waveguide  500  includes permanent magnet  502  and permanent magnet  504 . As can be seen in FIG. 5B, permanent magnet  502  forms an outer conductor while permanent magnet  504  forms an inner conductor of coaxial waveguide  500 . A vacuum region  506  is formed within coaxial waveguide  500  using microwave window  508  near input  104   a  of launcher  104 . Microwave energy is directed through vacuum window  508  into chamber  102  through output  104   b  in direction  510 . Magnets  502  and  504  generate magnetic field  512 , which is launched into resonance zone  514 , an 875 G resonance zone, in chamber  102 . This configuration of launcher  104  places permanent magnets closer to chamber  102  reducing the amount of the permanent magnet required to generate the desired magnetic field. 
     With reference now to FIGS. 6A and 6B, a launcher with a mode converter is depicted in accordance with a preferred embodiment of the present invention. In this embodiment, launcher  104  includes a rectangular waveguide  600  with a microwave window  602 , which defines vacuum region  604  of rectangular waveguide  600 . Rectangular waveguide  600  also includes a cylindrical stub coupler  606  in vacuum region  604 . Stub coupler  606  may be constructed from permanent magnetic material. Microwave energy is directed from a source through input  104   a  through rectangular waveguide  600  to output  104   b  in direction  608  into chamber  102 . Launcher  104  also includes a permanent magnet  610 , which is located above launcher  104 . Permanent magnet  610  generates magnetic field  612 , which is launched into resonance zone  614 , which is an 875 G resonance zone in the depicted example. This configuration of launcher  104  provides an advantage in that microwave window  602  is placed in a location that reduces deposition of materials on microwave window  602  during deposition processes and the depletion of microwave window  602  during etching processes. Specifically, microwave window  602  is located within launcher  104  such that a line of sight access to chamber  102  is absent. 
     Turning now to FIGS. 7A and 7B, a launcher with a rectangular waveguide is depicted in accordance with a preferred embodiment of the present invention. In FIGS. 7A and 7B, launcher  104  includes a permanent magnet  700  with a rectangular waveguide  702  connected to permanent magnet  700 . Alternatively, waveguide  702  may be inserted into permanent magnet  700 , such that waveguide  702  forms an inner wall in permanent magnet  700 . Microwave energy is directed through input  104   a  to output  104   b  in direction  704  into chamber  102 . A microwave window  706  is located at output  104   b  of launcher  104 . Permanent magnet  700  generates a magnetic field  708 , which is launched through output  104   b  into resonance zone  710 , which is an 875 G resonance zone in the depicted example. In this configuration, the amount of magnetic material required to generate the desired magnetic fields is reduced. 
     With reference now to FIGS. 8A and 8B, a launcher with a vacuum waveguide through magnet is depicted in accordance with a preferred embodiment of the present invention. Launcher  104  includes a rectangular waveguide  800  inserted through permanent magnet  802  in which microwave energy is directed through input  104   a  to output  104   b  into chamber  102  in direction  804 . Permanent magnet  802  generates magnetic field  806  that is launched into resonance zone  808 , which is an 875 G resonance zone in the depicted example. Rectangular waveguide  800  and launcher  140  includes vacuum region  810  within launcher  104 , which is defined by microwave window  812  and output  104   b . Optionally a permanent magnet  811  may be added within to launcher  104 . Permanent magnet  811  is placed in contact rectangular waveguide  800 . The configuration of rectangular waveguide  800  through permanent magnet  802  reduces the amount of magnetic material required to generate desired magnetic field  806 . In addition, this configuration also provides an advantage in which microwave window  812  is in a remote location relative to chamber  102  such that deposition of materials on the window is reduced along with minimizing etching through exposure to plasma processing occurring within chamber  102 . 
     With reference next to FIGS. 9A and 9B, a launcher including a rectangular waveguide having a dielectric waveguide portion is depicted in accordance with a preferred embodiment of the present invention. In FIGS. 9A and 9B, launcher  104  includes a rectangular waveguide  900  inserted through a permanent magnet  902  in which microwave energy is directed through input  104   a  to output  104   b  into chamber  102  in direction  904 . Permanent magnet  902  generates a magnetic field  906 , which is launched into resonance zone  908 , which is an 875 G resonance zone in the depicted example. A dielectric waveguide portion  910  is found within rectangular waveguide  900 . Tip  912  of dielectric waveguide portion  910  may be shaped to enhance coupling of desired modes into plasma within chamber  102 . Dielectric waveguide portion  910  may be rectangular or circular. Rectangular to dielectric coupler  911  may include a mode converter to excite the preferred mode within the dielectric (e.g., a right circular polarized mode). A material such as alumina with a high index will decrease the diameter required to support a particular mode. In the depicted example, dielectric waveguide portion  910  renders the use of a microwave window unnecessary within launcher  104 . The insertion of rectangular waveguide through permanent magnet  902  provides a configuration in which the amount of magnetic material required for permanent magnet  902  is reduced. 
     Thus, the present invention provides an improved method and apparatus for producing a uniform plasma within a vacuum chamber. The present invention provides this advantage using a launcher that includes a waveguide structure and magnetic material incorporated within the waveguide structure or in close proximity to the waveguide structure, reducing the amount of magnetic material needed to generate the desired magnetic fields for use in a vacuum chamber for deposition and etching processes involving plasma. The present invention includes an added advantage in which a microwave window may be placed within the launcher in a fashion that reduces deposition of materials on the microwave window during deposition processes and reduces etching of the window during etching processes within the vacuum chamber. 
     The present invention includes an advantage in that deposition and/or etching of the microwave vacuum window may be controlled by several techniques described in the depicted examples. One techniques includes positioning of the window out of the line of sight of the processing chamber and plasma generation region such that the probability of a deposition or window etch species reaching the window is greatly reduced. This possibility is covered in the examples in FIGS. 3-6 and  8 . In this approach, plasma is prevented from being generated in the area immediately adjacent to the window. The magnetic field is generated above that required for resonance in the region through the use of permanent magnets that substantially form one or more surfaces of the waveguide in the depicted examples. This allows the high magnetic fields to be generated without excessive cost in magnetic materials. In another techniques, the window may be maintained clean during operation of the system through proper design of the magnetic fields and location of the resonance zone such as to provide for sufficient ion bombardment to remove any deposition which occurs during operation by a process, such as sputter etching. The relative sputter etch may be manipulated for a given operating regime by controlling the spacing between the resonance zone and the window such as to provide the appropriate degree of ion bombardment. With smaller spacing, higher ion currents will flow to the window surface, while with larger spacing, smaller ion currents will reach the window. 
     The description of the present invention has been presented for purposes of illustration and description, but is not limited to be exhaustive or limited to the invention in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art. A permanent magnet is a material with an oriented macroscopic magnetization. The embodiment was chosen and described in order to best explain the principles of the invention the practical application to enable others of ordinary skill in the art to understand the invention for various embodiments with various modifications as are suited to the particular use contemplated.