Patent Document

FIELD OF THE INVENTION 
       [0001]    The present invention relates to microwave waveguides. 
       BACKGROUND OF THE INVENTION 
       [0002]    Plasma enhanced chemical vapor deposition (PECVD) is a well-known process for depositing thin films on a variety of substrates. Several industries varying from glass manufacturing, to semiconductor manufacturing, to plasma display panel manufacturing, rely on PECVD systems to deposit thin films upon substrates. PECVD systems vary widely in their application, just as the films they deposit vary widely in chemistry and quality. 
         [0003]    Typical PECVD processes can be controlled by varying process parameters such as gas pressure, power, power pulsing frequency, power duty cycle, pulse shape, and several other parameters. Despite this high degree of customization available in PECVD processes, the industry is continually searching for new ways to improve the PECVD process and to gain more control over the process. In particular, the PECVD industry seeks to utilize PECVD over a wider range of process parameters. 
         [0004]    Currently, PECVD can only be used in a limited set of conditions. For other conditions, alternative deposition processes must be used. These alternative deposition processes, such as electron cyclotron resonance (ECR) and sputtering, are not always optimal for many applications. Accordingly, the industry has been searching for ways to extend the application of PECVD into areas traditionally reserved for these alternative deposition methods. 
         [0005]    Additionally, PECVD microwave plasma sources have generally been a limited or unsuitable source for ions or other plasma species. Ions sources have many beneficial uses related to PECVD processes. For example, ion sources are often used to pretreat surfaces, such as polymer substrates, in preparation for deposition of thin films. Ion sources are also used to change the chemistry and structure of thin films during plasma deposition processes. Additionally, ion sources can be used to remove charge buildup from films or to clean surfaces. Although alternative ion sources can be combined with microwave plasma sources in PECVD, the PECVD process itself has been insufficient as its own ion source. 
         [0006]    Ion sources are available from a variety of vendors and are known in the art. But these ion sources typically suffer from several drawbacks. One drawback is that linear ion sources are overly expensive and complicated for many uses. In fact, many applications that would benefit from ion sources forego their use because of the high costs. Another drawback is that current ion sources tend to produce ions with too much energy. Most ion sources produce ions with over 120 eV of energy. In many applications, ions with this much energy can damage the surface being treated or damage the film being deposited. 
         [0007]    Although present devices and methods are functional, they are not sufficiently accurate or otherwise satisfactory. Accordingly, a system and method are needed to address the shortfalls of present technology and to provide other new and innovative features. 
       SUMMARY OF THE INVENTION 
       [0008]    Exemplary embodiments of the present invention that are shown in the drawings are summarized below. These and other embodiments are more fully described in the Detailed Description section. It is to be understood, however, that there is no intention to limit the invention to the forms described in this Summary of the Invention or in the Detailed Description. One skilled in the art can recognize that there are numerous modifications, equivalents and alternative constructions that fall within the spirit and scope of the invention as expressed in the claims. 
         [0009]    The present invention relates to microwave waveguides. In one exemplary embodiment, the present invention can include an integrated microwave waveguide comprising a waveguide block, a first waveguide section in the waveguide block, a second waveguide section in the waveguide block, a first impedance transition section integrated with the first waveguide section in the waveguide block, wherein the first impedance section comprises a first conduit with a first end and a second end, wherein the first conduit is tapered from the first end to the second end, and a second impedance transition section integrated with the second waveguide section in the waveguide block, wherein the second impedance section comprises a second conduit with a third end and a fourth end, wherein the second conduit is tapered from the third end to the fourth end, and wherein the second end of the first impedance transition section and the fourth end of the second impedance transition section are connected. 
         [0010]    As previously stated, the above-described embodiments and implementations are for illustration purposes only. Numerous other embodiments, implementations, and details of the invention are easily recognized by those of skill in the art from the following descriptions and claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    Various objects and advantages and a more complete understanding of the present invention are apparent and more readily appreciated by reference to the following Detailed Description and to the appended claims when taken in conjunction with the accompanying Drawings wherein: 
           [0012]      FIG. 1  is an illustration of an existing PECVD system; 
           [0013]      FIG. 2  is a representation of a waveform of a power pulse into a microwave antenna and the resulting total plasma light emission consistent with existing technology; 
           [0014]      FIG. 3  is a representation of a waveform of a power pulse into a microwave antenna and the resulting total plasma light emission consistent with the present invention; 
           [0015]      FIG. 4  illustrates a system for producing plasma radicals for surface treatment, thin film deposition, and/or film chemistry or structure alteration, constructed in accordance with one embodiment of the present invention; 
           [0016]      FIG. 5  is an illustration a containment shield constructed in accordance with one embodiment of the present invention; 
           [0017]      FIG. 6  illustrates a system for producing plasma radicals for surface treatment, thin film deposition, and/or film chemistry or structure alteration, constructed in accordance with one embodiment of the present invention; 
           [0018]      FIG. 7  illustrates a cross section of a profile of a containment shield constructed in accordance with an embodiment of the present invention; 
           [0019]      FIG. 8  illustrates a cross section of a PECVD array constructed in accordance with one embodiment of the present invention; 
           [0020]      FIG. 9  illustrates a cross section of a PECVD array constructed in accordance with one embodiment of the present invention; 
           [0021]      FIG. 10  is an illustration of a microwave waveguide with cascaded antenna; 
           [0022]      FIG. 11  illustrates a microwave waveguide with impedance transition constructed in accordance with one embodiment of the present invention; and 
           [0023]      FIG. 12  illustrates antenna configured in accordance with one embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0024]    Referring now to the drawings, where like or similar elements are designated with identical reference numerals throughout the several views, and referring in particular to  FIG. 1 , it illustrates a cut away of a typical PECVD system  100  for large-scale deposition and etch processes. This system includes a vacuum chamber  105  of which only two walls are illustrated. The vacuum chamber houses a discharge tube  110 . The discharge tube  110  is formed of an antenna  115  that is configured to carry a microwave signal, or other signals, into the vacuum chamber  105 . This microwave power radiates outward from the antenna  115  and ignites and fractionalizes the surrounding support gas that is introduced through the support gas tube  120 . This ignited gas is a plasma and is generally adjacent to the discharge tube  110 . Radical species generated by the plasma and electromagnetic radiation disassociate the feedstock gas(es)  130  introduced through the feedstock gas tube  125  thereby breaking up the feedstock gas to form new molecules. Certain molecules formed during the disassociation process are deposited on the substrate  135 . The other molecules formed by the fractionalization and disassociation processes are waste and are removed through an exhaust port (not shown)—although these molecules tend to occasionally deposit themselves on the substrate. 
         [0025]    Nonconductive and conductive films deposited utilizing plasma enhanced chemical vapor sources have been achieved with many types of power sources and system configurations. Most of these sources utilize microwaves, HF, VHF energy to generate the plasma and excited plasma species. It has been discovered that it is the average power applied to and discharged from the antenna that is the major contributing factor to the density of radicalized plasma species produced. 
         [0026]    Film properties requirements are achieved by varying the process conditions during deposition, including the power levels, pulsing frequency and duty cycle of the source. To achieve required film properties the structure and structural content of the deposited film must be controlled. The film properties can be controlled by varying the radical species content, (among other important process parameters), and as stated above, the radical density is controlled primarily by the average and peak power levels into the plasma discharge. 
         [0027]    To achieve several important film properties, and promote adhesion to some types of substrates, the films organic content must be finely controlled, or possibly the contents must be in the form of a gradient across the entire film thickness. 
         [0028]    In a typical PECVD process, only a small fraction of the supporting gas is actually fractionalized. For example, as little as 2% of the support gas is typically fractionalized. The amount of gas fractionalized is determined by the pressure of the supporting gas and the amount of power applied to the antenna in the discharge tube. The relationship between pressure, power and configuration is defined by the Paschen curve for any particular supporting gas. 
         [0029]    Most fractionalization of the supporting gas is caused by electrons generated by the power applied to the antenna in the discharge tube. Some fractionalization is also caused by ions and other plasma radicals. The effectiveness of electrons in fractionalizing a supporting gas is directly linked to electron density. In areas of higher electron density, fractionalization rates are higher for the same supporting gas pressures. 
         [0030]    For a typical PECVD process the necessary density of produced radicalized species from the plasma must be greater than that required to fully convert the required amount of feedstock gas. This is because some of the radicalized species from the plasma are consumed not only in the film deposition processes and plasma decomposition processes of the feedstock gas but also in unrelated portions of the deposition process, such as recombination mechanisms and pumping. 
         [0031]    Depending upon the power type, level, and/or configuration and the materials utilized, the required power level can unduly heat the substrate beyond its physical limits, and possibly render the films and substrate unusable. This primarily occurs in polymer material based substrates due to the low melting point of the material. 
         [0032]    To reduce the amount of heat loading of the substrate, a method of high power pulsing into the plasma, with off times in between the pulsing has been used. This method allows the plasma during the short high energy pulses to reach saturation of the radicalized species required for the film deposition process and loss to occur, while reducing the instantaneous and continuous heating of the substrate through the reduction of other forms of electromagnetic radiation. 
         [0033]    However, while pulsed microwave has been proven to benefit the process by reducing the thermal load on the substrate, deposition rates in general are typically lower than that of continuous wave (CW) power sources. This partly is due to the energy lost to the breakdown process of the discharge itself. 
         [0034]    Shown in  FIG. 2  is a representation of a typical waveform of a power pulse  200  into a microwave antenna and the resulting total plasma light emission  210 . As will be recognized by those skilled in the art, the vertical scale for the power pulse  200  and plasma light emission  210  are not the same, and are depicted here for illustration only. In a typical PECVD process, the loss of energy is roughly 20% of the total power. A significant portion of this energy loss is due to the energy required for ignition of the plasma discharge.  FIG. 2  shows the significant loss of power spent igniting and stabilizing the discharge. 
         [0035]    By sustaining a background minimal level of plasma ionization, and preventing the plasma from extinguishing, the loss of power into the plasma required for the initial ignition and stabilization of the plasma discharge is significantly reduced. For example, a background minimal level of plasma ionization could be sustained through modulation of the microwave power source, phasing of pulsed sources, or by the addition of external sources such as AC or RF glow discharge. These methods are exemplary only and not meant to limit the present invention. Modulation of the microwave power source, for example, could include pulsing the power source up from an initial power amplitude, to the full pulse amplitude, and then returning to an initial power amplitude. In one embodiment, the initial power amplitude would be a low power level that is sufficient to sustain a background minimal level of plasma ionization. Those skilled in the art will realize alternative methods and systems consistent with the present invention. 
         [0036]      FIG. 3  depicts a power pulse  200  and plasma light emission  310  consistent with the present invention. As will be recognized by those skilled in the art, the vertical scale for the power pulse  200  and plasma light emission  310  are not the same, and are depicted here for illustration only. It should also be recognized, however, that the peak levels of plasma light emission  310  using the background energy have been tested at around four times the peak levels of plasma light emission  210  when a background energy is not used. Utilizing a small amount of background energy keeps the plasma sustained so that when the power pulse  200  is applied, the energy into the plasma discharge is of a greater amount. Since less energy is used to excite the plasma, more energy is allowed to excite radical species. 
         [0037]    By maintaining a background minimal level of plasma ionization the power into the plasma typically was increased from a level of 75% to 95% due to the ionization efficiency increase gained by not needing energy to ignite a discharge. Referring back to  FIG. 1 , this background minimal level of plasma ionization could be sustained by applying power to the support gas tube  120  or feedstock gas tube  125 . In one embodiment of the present invention, the power applied to either tube could be an RF or AC glow discharge. In another embodiment of the present invention, a bias could be applied to the substrate  135  itself for the purpose of pre-ionization. Other embodiments are disclosed herein, but are exemplary only, as those skilled in the art will be aware of modifications consistent with the present invention. 
         [0038]    Fractionalization efficiency can also be greatly enhanced by utilizing a containment shield near the discharge tube. The benefits of containment shield utilization is discussed in commonly owned and assigned attorney docket number (APPL-012/00US), entitled SYSTEM AND METHOD FOR CONTAINMENT SHIELDING DURING PECVD DEPOSITION PROCESSES, which is incorporated herein by reference. A cross section of an exemplary design of a containment shield  400  that could be utilized in a PECVD process is shown in  FIG. 4 . The containment shield  400  is generally formed of a dielectric material, such as quartz, and provides a volume around the discharge tube  110  into which the supporting gas can be pumped. The exact volume of the containment shield  400  and the distance between the discharge tube  110  and the inner surface of the containment shield  400  can be varied based upon the desired film chemistry, the overall construction of the PECVD system and the desired gas pressures. 
         [0039]    The containment shield  400  acts to contain electrons and other radicalized plasma species that would otherwise escape. By containing electrons, the electron density around the discharge tube  110  can be increased at distances further from the discharge tube  110 . And by increasing electron density, the plasma can be extended further with the same process parameters—meaning that the fractionalization rate can be increased without changing other process parameters. 
         [0040]    The containment shield  400  also helps prevent radicals and ions from escaping. This can help the fractionalization efficiency and prevents generated radicals and ions from being wasted. And by preserving these particles, the PECVD system can be operated over a wider range of operational parameters and operated more efficiently. 
         [0041]    It should be noted that these embodiments are not limited to a PECVD system. Those of skill in the art could extend the concepts of the present invention to cover any type of plasma system. 
         [0042]    Containment shields also advantageously provide better control over supporting gas pressures around the discharge tube  110 . First, containment shields help provide a more uniform supporting gas pressure than was possible without a containment shield. This more uniform pressure allows the fractionalization rate to be better controlled and thus increased. 
         [0043]    Second, containment shields provide the ability to have a different pressure within a containment shield than in the remaining portions of the process chamber. This is advantageous because a higher pressure can be maintained within a containment shield and a lower pressure can be maintained in the remaining portions of the process chamber. The result of this variable pressure allows more radicals to be produced at an overall lower process chamber pressure. This type of control allows PECVD processes to be run at significantly lower process chamber pressures than previously possible. 
         [0044]    Further illustrated in  FIG. 4  are the process chamber  105 , the substrate  135 , the substrate support  410 , the discharge tube  110 , the antenna  115 , the containment shield  400 , a microwave reflector  430 , and a supporting gas tube  120 . The supporting gas tube  120  is located inside the containment shield  400  in this depiction. 
         [0045]    The containment shield  400  includes an aperture  420  nearest the substrate  135 . It is through this aperture  420  that the radicals escape and collide with the feedstock gas. The size of this aperture  420  can be varied either manually or electronically to control the number of radicals escaping from the containment shield  400 . It can also be a fixed-size aperture. 
         [0046]    In some embodiments, the pressure within the containment shield  400  can be higher than the pressure outside the containment shield  400 . Thus, the general PECVD process can be operated at a lower pressure while the plasma enhancement process and the radical production process can be operated at a much higher pressure. As previously discussed, pressure is a key factor in the fractionalization efficiency of the support gas. Up to a certain point, higher pressure enables higher fractionalization efficiencies. Thus, the higher pressure allowed inside a containment shield enhances the fractionalization efficiencies. 
         [0047]    The efficiency of containment shields depends, at least partly, on the shields&#39; effectiveness in properly channeling and preventing the escape of the electrons, ions and radicals. For this reason, the containment shield is generally formed from a dielectric material like quartz. The expense, fragility, and limitations on machinability of dielectric materials such as quartz, however, presents certain restrictions on containment shields. 
         [0048]      FIG. 5  illustrates a containment shield  500  in accordance with one embodiment of the present invention.  FIG. 5  depicts a tube  510  that has been pre-coated with a dielectric coating  520  and placed around a discharge tube  110  so that the volume of gas within the tube  510  can be more fully ionized to achieve greater fractionalization. In this embodiment, the discharge tube  110  is a linear discharge tube with a single antenna  115 . In another embodiment, the containment shield  500  consists of a quartz tube which is wrapped with a conductor (not shown). Instead of a conductor which is pre-coated with a dielectric coating, now a dielectric base material wrapped or coated with a conducting layer is used. All references herein to a dielectric coating  520  on a base material  510  are for illustration only and the construction of a containment shield using a dielectric material coated with a conducting layer is also understood in the present application. Those skilled in the art will be aware of many modifications, including non-linear discharge tubes and split antenna, consistent with the present invention. 
         [0049]    In one embodiment of the present invention, the tube  510  could be coated with alumina in order to form the dielectric coating  520 . Other dielectric materials could be used to form the dielectric coating  520  depending on the requirements of the system. 
         [0050]    Those skilled in the art will be aware of variations consistent with present invention. 
         [0051]    The embodiment in  FIG. 5  also shows slots  530  with variable slot apertures  540 . The variability of the slots  530  can be used to control process parameters such as the density of UV radiation, internal and external pressure differential, and flow into or out of the tube. The slots  530  could also be of a fixed size. The configuration of the shielding could be varied in many ways, including: size, shape, material, number of shields, number of slots, the addition of an outer metal shield to reflect lost electromagnetic radiation back into the plasma pipe volume, etc. For example, the tube  510  could be constructed out of metal. While metal itself will not produce the desired containment effects, by pre-coating the metal with a dielectric material an effective containment shield  500  can be produced. Moreover, the metal would also be able to reflect electromagnetic radiation back toward the discharge tube  110  for increased ionization efficiency. In another embodiment, a dielectric body, such as a quartz tube, is wrapped with a conducting layer, such as metal, to obtain both desired containment effects and reflection of electromagnetic radiation. 
         [0052]    By utilizing containment shields, and by pre-coating a base material with a dielectric coating before the containment shield is used in the PECVD process, there will be a significant reduction in the time the systems will have to be offline for cleaning. This is because the dielectric materials can sustain a high temperature during the PECVD process. At temperatures around 200-300° C. for most processes, the dielectric coating will resist deposition on the surfaces surrounding the discharge tube and eventual flaking. Additionally, utilizing containment shields and pre-coating any base materials with a dielectric coating will greatly reduce any pre-start time for the PECVD system. Typically, a PECVD system has to be pre-started in order to allow for a layer of deposition to form on the surfaces surrounding the discharge tube. This allows the plasma density to stabilize before beginning the deposition process. The current invention allows for plasma densities to be immediately stabilized and therefore reduces pre-start time. 
         [0053]    The exemplary containment shield  500  from  FIG. 5  may also be used as a source of power for sustaining a minimal background level of ionization. By pre-coating the tube  510 , that tube  510  comprised of an electric conductor, with a dielectric coating  520 , all the benefits of a containment shield are retained with the added benefit that the containment shield  500  can act as the power source for pre-ionization of the plasma. In one embodiment, a power source could be applied to the conductive portion of the containment shield  500  in order to sustain a minimal background level of plasma ionization and increase the ionization efficiency. In another embodiment, a conductive material (not shown) could be added to the tube  510  and then both the tube  510  and the conductive material (not shown) could be pre-coated with a dielectric coating  520 . Those skilled in the art will be aware of alternative systems and methods consistent with the present invention. 
         [0054]      FIG. 6  illustrates another embodiment of a containment shield  600  consistent with the present invention. In  FIG. 6  a cross sectional view of a containment shield  600  that could be used in a PECVD process is shown. In this embodiment, a discharge tube  110  and support gas tube  120  are shown partially surrounded by a containment shield  600 . This containment shield  600  is formed using a dielectric coating  520  on a base material  610  such as metal. Here the containment shield  600  is shown with a circular profile, where aperture  420  in the containment shield is nearest the substrate  135 . It should be recognized by those skilled in the art that any profile could be used, and that the circular profile shown here is exemplary only. Alternative profiles could be used to control certain process parameters. For example, a profile that increases the resonance time of the support gas could be used to further increase ionization efficiency. 
         [0055]    As was previously discussed, the dielectric coating  520  that is pre-coated on the base material  610  will heat during the microwave pulsing. The benefits of allowing the dielectric coating  520  to heat have been previously discussed. The heating, however, could potentially cause problems keeping the dielectric coating  520  affixed to the base material  610 . In one embodiment of the present invention, a temperature control system (not shown) can be used to help control the temperature of the base material  610 . The base material  610  could be heated near the dielectric coating  520  and cooled further away. Cooling may be used to keep the base material  610  from affecting exterior portions of the system and to prevent warping. By controlling the thermal gradient across the dielectric coating  520  and through the base material  610  the benefits of a high temperature dielectric coating  520  can be retained without losing adhesion of the dielectric coating  520  itself. 
         [0056]    Further illustrated in  FIG. 6  is a plasma species extraction grid  620  placed over the aperture  420  in the containment shield  600 . This plasma species extraction grid  620  could be used to energize and extract ions, electrons, or other plasma species, from the plasma created around the discharge tube  110 . In one embodiment of the present invention, a DC, RF, or AC potential may be applied to the plasma species extraction grid  620  in order to accelerate and control the direction of ions or other plasma species out of the containment shield  600 . In another embodiment, the potential applied to this plasma species extraction grid  620  could also be used for sustaining a background minimal level of plasma ionization between power pulses. 
         [0057]    In an embodiment consistent with the present invention, a support gas is introduced through the support gas tube  120  in  FIG. 6 . Excitation of the support gas is accomplished by subjecting the gas to microwave power from the antenna  115 . Free electrons gain energy from the imposed microwave field and collide with neutral gas atoms, thereby ionizing those atoms including fractionalizing the supporting gas to form a plasma. This plasma contains partially ionized gas that consists of large concentrations of excited atomic, molecular, ionic, and free radical species. These particles impact the substrate  135 , and depending upon the process employed, clean the substrate  135 , modify the surface, or remove excess electrical charge. It is the interaction of these excited species with solid surfaces placed in or near the plasma that results in the chemical and physical modification of the material surface. 
         [0058]    In most microwave based processes, however, the ions never gain enough energy to reach the substrate  135 . By placing the plasma species extraction grid  620  over the aperture  420  and applying a potential, the ions, or other plasma species, can be accelerated and directed so that they impact the substrate  135 . In one embodiment, the microwave power plasma source could be used as an ion source. Such an ion source could produce high ion densities with various electron voltages, depending on the potential applied to the plasma species extraction grid  620 . 
         [0059]    Although the plasma species extraction grid  620  could be constructed from many materials consistent with the present invention, using etch resistant materials such as Tungsten will help prevent any sputtering effects from the plasma species extraction grid  620  itself. Moreover, by allowing the plasma species extraction grid  620  to heat up, deposition on the plasma species extraction grid  620  itself, and any subsequent flaking, can also be prevented. 
         [0060]    The plasma species extraction grid  620  can be added to many microwave power source systems in accordance with the present invention. The description of the plasma species extraction grid  620  with the current embodiment is by example, and not intended to limit the present invention. For example, in another embodiment the plasma species extraction grid  620  could be added over the apertures  540  from  FIG. 5 . Those skilled in the art will be aware of many systems and methods consistent with the present invention. 
         [0061]    Referring back now to  FIG. 4 , a plasma species extraction grid  620  is shown placed over the aperture  420  of the containment shield  400 . During operation of the exemplary system, a plasma  630  forms around the discharge tube  110 . In this embodiment, the shape of the containment shield  400  and the size of the aperture  420  can assist in directing any escaping ions or other plasma species down toward the substrate. Consistent with an embodiment of the present invention, the plasma species extraction grid  620  can also be used to further control, accelerate, and to energize ions or other plasma species. These extracted plasma species  640  are shown being directed towards the substrate  135 . 
         [0062]      FIG. 7  illustrates a containment shield  700  with an alternative profile consistent with the present invention. The shape of the containment shield  700  can be varied to control surface treatment properties. For example, the shape of the containment shield can be optimized from one application to another for specific energetic species and radical/metastable conditions, to achieve specific deposited or etched material properties. In this embodiment, the containment shield  700  is constructed with more of a triangular profile. The exemplary profile creates an increased baffle for the support gas supplied from the support gas tube  120 . The increased baffle lengthens the resonance time for the support gas. The resonance time is greater because of the increased time it takes for at least some of the gas to pass from the support gas tube  120  out through the aperture  420  in the containment shield  700  and down toward the substrate  135 . The increased resonance time allows for increased ionization efficiency and greater fractionalization of the support gas. Those skilled in the art will be aware of further profiles consistent with the present invention. 
         [0063]    Various profiles can be constructed depending on the specific application. The present invention allows greater flexibility in constructing such profiles. Base materials, with greater machinability and lower cost than dielectric materials, can be used to form profiles of any shape. Consistent with one embodiment of the present invention, these profiles can then be pre-coated with a dielectric coating to form a containment shield. Those skilled in the art will be able to construct many profiles consistent with one embodiment of the present invention. 
         [0064]    In  FIG. 8  there is an illustration of an exemplary embodiment of a containment shield  800  for a static array of discharge tubes  110 .  FIG. 8  shows a cross-sectional view of a containment shield  800  that could be used in a PECVD process consistent with the present invention. In this exemplary embodiment, a static array of discharge tubes  110  and support gas tubes  120  are shown partially surrounded by a containment shield  800 . The containment shield  800 , which is formed using a dielectric coating  520  on a base material  610  such as metal, is placed such that the apertures  420  will guide gas from the support gas tubes  120  out through apertures  420  down toward the substrate  135 . In this exemplary embodiment, the containment shield  800  has slightly oval profiles. As previously discussed, other profiles could be used consistent with the present invention. The present embodiment also uses a consistent profile along the static array of discharge tubes  110 . This is exemplary only. Those skilled in the art will realize many variations and modifications consistent with the present invention. Moreover, it will be realized by those skilled in the art, that a plasma species extraction grid  620  can be placed over the apertures  420  in order to gain the benefits of plasma species directionalization and acceleration that are described herein. 
         [0065]    Depending on the base material in  FIG. 8 , the containment shield  800  can also act to either block energy transfer between antenna  115  or to allow energy transfer between the antenna  115 . The benefits of an energy blocking base material  610  were discussed with respect to  FIG. 5  and the benefits of allowing energy transfer between antenna is discussed with respect to  FIG. 9 . Nothing in the present invention should be read to limit the type of material that could be used as the base material  610 . 
         [0066]    Now referring to  FIG. 9  there is an illustration of another embodiment consistent with the present invention. In this embodiment, a static array of discharge tubes  110  and support gas tubes  120  are shown partially surrounded by a containment shield  900 . The containment shield  900  is formed using dielectric dividers  910  placed between the discharge tubes  110 . By using dielectric dividers  910  positioned between the discharge tubes  110 , energy transfer is allowed between the antenna  115 . This energy transfer can be used to produce the pre-ionization effects required to sustain a plasma around each discharge tube  110  while an antenna  115  is in an off phase of its power cycle. For example, in one embodiment of the present invention, adjacent antenna  110  could be controlled by a timing control that phases the pulsed sources. This phasing could be implemented so that a minimal background level of plasma ionization is sustained due to the energy transferred from the adjacent antenna  115 . 
         [0067]    The dielectric dividers  910  are then connected to a base material  610  such as metal. The base material  610  is pre-coated with a dielectric coating  520  on, at least, any surfaces that are exposed to, and help partially enclose, the discharge tube  110 .  FIG. 9  also shows baffles formed using a dielectric coating  520  that is pre-coated on a baffle material  920  such as metal. The baffle has been added to help increase the resonance time of the gas from the support gas tube  120 . Other shapes and designs could be used to control other process parameters. p In one embodiment of the present invention, the baffle material  920  could be constructed out of a microwave reflecting material like metal, such that some of the energy emitted by the antenna  115  will be reflected back towards the plasma around the discharge tube  110 . Those skilled in the art will realize many modifications to the size, shape, material composition, etc. that can be made consistent with the present invention. For example, the baffle in this embodiment may be removed. Alternatively, the shape and/or orientation of the dielectric divider  910  could be changed so as to create a baffle. 
         [0068]    Referring back to  FIGS. 8 and 9 , each contains a static array of discharge tubes  110 . Within each discharge tube is an antenna  115 . This antenna  115  may be a linear antenna, split antenna, non-linear antenna, etc. The use of a dielectric coating  520  in order to create a containment shield can help to reduce the size of the containment shield and thus reduce spacing required between antenna  115  in a static array. With reduced spacing between antenna  115 , more uniform film properties can be achieved. In small systems, an antenna  115  may be cascaded multiple times as shown in  FIG. 10  and power split between each of the cascaded antenna  1060 . However, given the power limitations for currently used generators, this configuration will not produce effective power densities for larger systems. 
         [0069]    Moreover, in a typical application of coaxial microwave, the microwave generator  1010  is located as close as possible to the antenna stub  1040  and antenna  1050  to minimize power loss.  FIG. 10  shows a microwave waveguide  1020 , impedance transition  1030 , elbow  1070 , and movable plunger  1080  consistent with existing technology. As can be seen in  FIG. 10 , the length of the waveguide  1020  and impedance transition  1030  keeps the microwave generator  1010  away from the antenna stub  1040  and antenna  1050 . Beyond the increased power losses due to the greater distance between the microwave generator  1010  and the antenna stub  1040 , the size of the waveguide  1020  and impedance transition  1030  has made it unwieldy and difficult to construct and house PECVD systems. With existing technology, the manufacture of PECVD systems has been limited by the availability of individual waveguide parts. Integrating the waveguide  1020  and the impedance transition  1030  can decrease the size of the waveguide for both usability and power efficiency. 
         [0070]      FIGS. 11 and 12  illustrate an integrated microwave waveguide with impedance transition  1100  consistent with the present invention. As can be seen in  FIG. 11 , by integrating the waveguide and impedance transition  1110  into a waveguide block  1120  the microwave generator  1010  can be placed closer to the antenna stub  1040  and antenna  1050  to increase power density. While the waveguide block  1120  is depicted in  FIGS. 11 and 12  as a single piece of material, inside of which is the integrated waveguide with impedance transition  1110 , that depiction is in no way intended to limit the present invention. In another embodiment, the waveguide block  1120  could comprise two pieces of material where the integrated waveguide with impedance transition  1110  is connected at the antenna stub  1040 . Those skilled in the art will realize there are many modifications that can be made consistent with the present invention. 
         [0071]    In one embodiment of the present invention, the integrated waveguide with impedance transition  1110  can be machined into a waveguide block  1120  comprised of aluminum, copper, brass, or silver. This could be done by properly machining two tapered conduits into the waveguide block  1120  so that the tapered conduits start at the surface of the waveguide block and end at an antenna stub  1040 . In this embodiment, the microwave signal can be transitioned throughout the waveguide section, fully integrating the waveguide  1020  and impedance transition  1030 . In such an embodiment, the integrated waveguide with impedance transition  1110  essentially eliminates any separate waveguide section. This allows a waveguide block, with an integrated microwave waveguide to be built much smaller than waveguides that have to use separate waveguide sections  1020 , elbows  1070  and impedance transition sections  1030 . 
         [0072]    In another embodiment, two conduits can be machined into the waveguide block  1120  to form waveguide sections. These conduits would form channels from the surface of, and into, the waveguide block  1120 . These channels could then be connected with impedance transition sections to form the integrated waveguide with impedance transition  1110 . In this embodiment, the waveguide section and transition section are partially integrated in order to form the integrated waveguide with impedance transition  1110 . Those skilled in the art will be aware of various modifications and alternatives consistent with the present invention. 
         [0073]    Also illustrated in  FIGS. 11 and 12  is a movable plunger  1080  disposed on a side of the integrated waveguide  1100  opposite the microwave generator  1010  consistent with the present invention. The movable plunger  1080  can be moved in order to tune the waveguide. In  FIGS. 11 and 12 , the movable plunger  1080  can be displaced up or down to move a microwave node to the antenna stub  1040 . 
         [0074]    In addition to minimizing the space for components, it has also been found that by turning the integrated microwave waveguide  1100   90 -degrees as compared to the antenna  1050 , as illustrated in  FIG. 12 , the power density is increased further. In one embodiment, a single cascade power split antenna  1210  could be used with the present invention. As shown in  FIGS. 11 and 12 , the antenna stubs  1040  in the present invention can be located much closer than antenna stubs  1040  in  FIG. 10 . Since the antenna stubs  1040  are located closer together, the antenna  1050  does not have to be power split as many times in order to get to the desired spacing. For larger systems, the present invention makes it possible to achieve effect power densities not previously possible. Those skilled in the art will realize there are many modifications that can be made consistent with the present invention. 
         [0075]    In conclusion, the present invention provides, among other things, a system and method for producing electrons, ions and radicalized atoms and molecules for surface treatment and film chemistry, and film structure, formation and alteration. Those skilled in the art can readily recognize that numerous variations and substitutions may be made in the invention, its use and its configuration to achieve substantially the same results as achieved by the embodiments described herein. Accordingly, there is no intention to limit the invention to the disclosed exemplary forms. Many variations, modifications and alternative constructions fall within the scope and spirit of the disclosed invention as expressed in the claims.

Technology Category: h