Patent Application
20080023146
As mentioned earlier, the present invention includes a variety of aspects; all may be combined in different ways. The following descriptions are provided to list elements and describe some of the embodiments of the present invention. These elements are listed with initial embodiments, however it should be understood that they may be combined in any manner and in any number to create additional embodiments. The variously described examples and preferred embodiments should not be construed to limit the present invention to only the explicitly described systems, techniques, and applications. Further, this description should be understood to support and encompass descriptions and claims of all the various embodiments, systems, techniques, methods, devices, and applications with any number of the disclosed elements, with each element alone, and also with any and all various permutations and combinations of all elements in this or any subsequent application.
At least one embodiment of the inventive technology may be a plasma system 1 that comprises a coil 2 powered by a power source 3 (including but not limited to an RF power source 4) so as to generate or enhance a plasma 5 in a process chamber 6; and a dielectric form 7 that itself is established within the process chamber, has two ends 8 supported by at least one support member 9 at two support sites 10 (e.g., where the dielectric form contacts the support member(s)), and defines an internal volume 11. In such system, at least a portion of the coil is established in the internal volume. Advantages of such a system include but are not limited to the ability to process substrate surfaces having long width and length (e.g., each over 1 meter) while avoiding problems associated with other types of plasma source. Another potential advantage, in addition to those discussed elsewhere, is an ability to process substrates in pure oxygen at “magnetron” pressures of three to ten Torr, where desired.
At least one embodiment of the inventive technology may relate in particular to only those embodiments that process a substrate 12 in some manner, whether to etch, clean, preheat, or deposit material on that substrate. Such system may comprises a coil powered by a power source so as to generate or enhance a plasma in a process chamber; a dielectric form that defines both an internal volume and a form centerline 13; and a substrate support 14 adapted to support a substrate in the process chamber, where the substrate has a process surface 15 defining a process surface plane 16, where at least a portion of the coil is established in the internal volume, and where the form centerline is substantially parallel the process surface plane. Advantages of such a system include but are not limited to the ability to process substrate surfaces having long width and length (e.g., each over 1 meter) while avoiding problems associated with other types of plasma source. Another potential advantage, in addition to those discussed elsewhere, is an ability to process substrates in pure oxygen at “magnetron” pressures of three to ten Torr, where desired. What follows describes aspects of the inventive technology as may relate to any of its primary manifestations (two of which are described above), unless stated otherwise.
The power source 3, whether powering the coil, any magnetron that may exist, or 25 both, may be an AC power source (e.g., an AC power source), such as a RF (radio frequency) generator, and, as but one range, may operate at between 350 KHz to 15 MHz. For reasons related to high impedance of the coil and high capacitance to the ground, particularly good results may be found at a relatively low frequency of 400 kHz. In certain instances, the power source may be DC. Certain embodiments may include an impedance matching network 18 (e.g., that may be connected to an RF power source) in order that the RF power remains as constant as possible during the process, thereby assuring process quality and consistency. The substrate support is any structure—even merely a process chamber floor, as but one example—that is capable of supporting a substrate as intended (whether horizontally, vertically, or in other orientation). It is also noted that the term plasma system is used to reference any type of electrical system in which a plasma is used to achieve a desired effect (including but not limited to processing a substrate surface in an intended manner).
The coil itself may be an induction coil with a plurality of windings. In preferred embodiments, it is operable as a solenoid to inductively couple energy through the dielectric form to a gas in order to generate and sustain, or merely enhance, a plasma of ionized gas particles. It may be a longitudinal coil 19 (a term that includes a coil that has windings that each define a coil centerline that is substantially parallel to the centerline of the dielectric form), or, as but one other example, it may be what will be deemed a transverse coil 20 (see
A transverse coil may be particularly suited where it is desired that the solenoid includes windings that each run along the length of the dielectric form. In those embodiments having a longitudinal coil, the magnetic field 63 established by the coil may indeed be relatively small in the plasma (see
The dielectric form includes but is not limited to a dielectric tube 21 (where the cross-section is circular 60, oval 61, or perhaps even polygonal 62, as but three of many possible examples). It may be made from any dielectric material, including but not limited to glass or quartz. It may have any of a multitude of outer diameters (3″-5″, as but one exemplary range). It may be established so as to provide fluidic communication through the form (e.g., such that a gas may pass through one end of the form, to the other end, and through the other end). In certain embodiments, it may extend along a dimension (e.g., a depth, width, height, or length) of the process chamber. The dielectric form may, inter alia, eliminate exposed metal, and allow plasma generation/maintenance in reactive gases.
The two ends of the dielectric form may be supported by at least one support member at two support sites. Such support member may be a wall(s) 22 of the process chamber itself, or a structure 23 established within the process chamber. Such support may be provided either directly (e.g., where the ends themselves are attached to the at least one support member at the two support sites as shown in
In various embodiments, there may be established within the process chamber one or more dielectric forms, each having a coil established therein (see, e.g.,
The internal volume defined by the dielectric form may be at substantially atmospheric pressure. It may be an internal cavity 34, as where it is filled with only atmospheric or other gases, or perhaps even at vacuum. The internal volume may include potting compound 35 (e.g., RTV, room temperature vulcanizing silicone potting compound and/or cooling fluid 36 such as oil ), perhaps for enhanced cooling. Additionally perhaps, or instead, the dielectric form may include some type of UV protection; such may be provided by a known type of UV protective coating on the dielectric form, or by a material such as a certain type of quartz. As is known, UV rays from the plasma can lead to the generation of ozone, which can degrade plastic or RTV potting compound.
At least one embodiment of the invention may focus on the use of an internal coil in order to enhance a deposition process, whether such deposition is effected by a magnetron 37, ion source 38 or by other process, including but not limited to chemical vapor deposition (as in plasma enhanced chemical vapor deposition). In plasma deposition process, the energized coil creates or enhances a plasma (e.g., one that is often preferably high density and/or uniform) to bombard the surface of a target 71, leading to deposition on the substrate's process surface 15. Further, it should be pointed out that the deposition process may indeed also be reactive sputtering, in which a reactive gas that reacts with the sputtered material is introduced into the process chamber.
Where a magnetron is used, the effect to which the internal coil assists the deposition process may directly relate to its closeness to the magnetron—the closer the two are, the greater the deposition enhancement effect caused by the internal coil, and, perhaps, the less voltage required by magnetron to achieve an intended deposition process. For a general understanding of types of magnetrons that may be used, including balanced and unbalanced magnetrons, and of magnetron sputtering, reference is made to www.pvd-coatings.co.uk/theory-of-pvd-coatings-magnetron.htm, and www.pvd-coatings.co.uk/theory-of-pvd-coatings-magnetron-sputtering.htm, each as appearing on Jul. 11, 2006, and each hereby incorporated herein. It is also of note that the magnetic field created by the often DC-powered magnetron need not reach the substrate, although indeed it may.
An ion source 38, when used, may be used instead of (see, e.g.,
It is also noted that some closed-drift ion sources, such as the LIS series and MCIS series manufactured by Advanced Energy Industries of Fort Collins, Colo., do not require an electron emitter for their operation. Additionally, the ion beams that may be used in the inventive technology include, but are not limited to, the round and linear ion sources disclosed in http://www.advanced-energy.com/upload/SL-ION-230-02.pdf, as appearing on Jul. 11, 2006, said webpages also incorporated herein. Various well-known ion beam source applications, as shown in
Embodiments of the inventive technology may involve use of an ion beam in certain processes (ion beam sources that may be used include but are not limited to those shown in
It is of note that in systems involving a conductive target (e.g., a conductive target of a magnetron), such target may be biased using known bias systems 47 so as to enhance the process (e.g., by increasing the ion bombardment rate). Instead, or in addition, a bias system (e.g., a RF bias system 48), which is well known per se, may operate on a conductive substrate 130 so as to enhance the process, whether it be cleaning, preheating, etching, or deposition.
In embodiments that are designed for deposition (e.g., that include a magnetron, a chemical vapor deposition element 49, or include some other type of deposition element), or that are designed for preheating, etching or cleaning, or indeed any other type of processing of a substrate, there may, as mentioned, be provided a substrate support element. It is also of note that there may be provided some type of continuous feed element 53 (e.g., a conveyor belt system, perhaps with rollers as shown) that is operable to move a substrate responsive thereto (e.g., a substrate lying on top of the belt) at a controlled speed so that a plasma system sized to treat only a portion of the substrate at one time may treat the entire substrate as desired. In some embodiments, the substrate may be fed through a sealed lock 50 (a type of slot, perhaps) so as not to affect the pressure in the process chamber, as the area from which the substrate is fed will typically be at a higher pressure. In other embodiments, the need for a well sealed lock may be eliminated through the use of a pre-chamber 51 (e.g., as shown in
In those embodiments that include a magnetron, the dielectric form and the magnetron may be placed sufficiently close such that they together result in only one plasma (see, e.g.,
As in
As alluded to above, the inventive technology may not only be used for deposition and/or substrate preheating, but also for substrate cleaning and/or etching. In such embodiments, there might not be provided a magnetron or other type of deposition element.
In particular embodiments, at least a portion of the space within the process chamber (e.g., at least that space other than that occupied by the dielectric form(s)) may be held at a vacuum (a term deemed to characterize, e.g., even those situations where a process gas (e.g., a non-reactive gas such as Argon) is introduced into the chamber in appropriate amounts through a gas inlet 65, such that a perfect vacuum does not exist).
Deposition type plasma systems may be a rotating drum batch coating system 52 (see article “A High Rate Reactive Sputtering Process For Batch, In-Line, or Roll Coaters”, by Boling et al., hereby incorporated herein), may involve a continuous feed element 53 (e.g., so as to better coat, etch, preheat or clean large flat panel substrates), or even may involve a substrate that is held stationary during the process (e.g., cleaning, etching, preheating or deposition). In any process type, whether continuous or not, the dielectric form may be substantially horizontal, vertical, off-horizontal, off-vertical, or have other orientation. The dielectric form may have any orientation relative to the substrate, as indeed it may be above the substrate, below the substrate, to the side of the substrate, in front of the substrate, behind the substrate, etc., depending on the particular demands of the processing application. The substrate itself may also be substantially horizontal, vertical, off-horizontal, off-vertical, or have other orientation. Continuous drum rotation systems may involve a pump 120, multiple substrates 121 and targets 122, plasma 123, active gas 124, a microwave plasma applicator 125, and an optical gas controller 127 in a rotating drum system as shown in
Embodiments of the inventive technology may also find application in web coaters (e.g., web coaters, web roll coaters, or other type). In such embodiments (e.g., as shown in
Particular embodiments may include a faraday shield 54 (see, e.g.,
Embodiments of the inventive technology may be particularly suited for process surfaces (surfaces to be processed, e.g., via etching, cleaning, preheating or deposition) that are substantially flat panels (e.g., glass windshields, plastic panels) having at least one long dimension. In processing such panels, a continuous feed element may feed the substrate such that the entire process surface may be treated by the plasma during a processing event. In such systems, often a plasma will be generated such that a relatively thin width strip can be treated at a time; upon moving the substrate along such plasma (e.g., from one end to the other, along its length), perhaps with a type of continuous feed element 53, the entire surface as intended may be treated. Such panel may first be established in a pre-chamber 51 at vacuum and subsequently fed under the plasma; instead, there may be a type of sealed lock 50 through which the substrate may be fed into the process chamber for treatment. Some systems may involve a process chamber large enough to accommodate the entire substrate from the beginning of the process, through a feeding event, to the end of the process.
It is of note that certain measures may be taken in order to preclude problems related to thermal expansion along a longitudinal axis of the dielectric form during plasma processing. Such measures may simply involve provision of an ability of the form to move (e.g., slide) relative to the at least one support, at the support sites. Such may be achieved by well known techniques that provide a slideable seal 59 around dielectric form at the support sites. It is of note, for purposes of clarity, that not every occurrence of every element in the figures is referenced (or “called out”) with that number used in reference to it.
The reader should be aware that the specific discussion may not explicitly describe all embodiments possible; many alternatives are implicit. The specification may not explicitly show how each feature or element can actually be representative of a broader function or of a great variety of alternative or equivalent elements; these are implicitly included in this disclosure.
It should also be understood that a variety of changes may be made without departing from the essence of the invention. Such changes are also implicitly included in the description and still fall within the scope of this invention.
Additionally, when used or implied, the term element is to be understood as encompassing individual as well as plural structures that may or may not be physically connected. This disclosure should be understood to encompass each such variation, be it a variation of an embodiment of any apparatus embodiment, a method or process embodiment, or even merely a variation of any element of these.
