Patent Application
20130298831
The invention relates generally to semiconductor fabrication technology and, more particularly, to cleaning material deposits from interior surfaces of wafer processing systems such as chemical vapor deposition (CVD) apparatus.
In the fabrication of light-emitting diodes (LEDs) and other high-performance devices such as laser diodes, optical detectors, and field effect transistors, a chemical vapor deposition (CVD) process is typically used to grow a thin film stack structure using materials such as gallium nitride over a sapphire or silicon substrate. A CVD tool includes a process chamber, which is a sealed environment that allows infused gases to be deposited upon the substrate (typically in the form of wafers) to grow the thin film layers. An example of a current product line of such manufacturing equipment is the TurboDisc® family of MOCVD systems, manufactured by Veeco Instruments Inc. of Plainview, N.Y.
A number of process parameters are controlled, such as temperature, pressure and gas flow rate, to achieve a desired crystal growth. Different layers are grown using varying materials and process parameters. For example, devices formed from compound semiconductors such as III-V semiconductors typically are formed by growing successive layers of the compound semiconductor using metal organic chemical vapor deposition (MOCVD). In this process, the wafers are exposed to a combination of gases, typically including a metal organic compound as a source of a group III metal, and also including a source of a group V element which flow over the surface of the wafer while the wafer is maintained at an elevated temperature. Typically, the metal organic compound and group V source are combined with a carrier gas which does not participate appreciably in the reaction as, for example, nitrogen. One example of a III-V semiconductor is gallium nitride, which can be formed by reaction of an organo-gallium compound and ammonia on a substrate having a suitable crystal lattice spacing, as for example, a sapphire wafer. Typically, the wafer is maintained at a temperature on the order of 1000-1100° C. during deposition of gallium nitride and related compounds.
In a MOCVD process, where the growth of crystals occurs by chemical reaction on the surface of the substrate, the process parameters must be controlled with particular care to ensure that the chemical reaction proceeds under the required conditions. Even small variations in process conditions can adversely affect device quality and production yield. For instance, if a gallium and indium nitride layer is deposited, variations in wafer surface temperature will cause variations in the composition and bandgap of the deposited layer. Because indium has a relatively high vapor pressure, the deposited layer will have a lower proportion of indium and a greater bandgap in those regions of the wafer where the surface temperature is higher. If the deposited layer is an active, light-emitting layer of an LED structure, the emission wavelength of the LEDs formed from the wafer will also vary to an unacceptable degree.
In a MOCVD process chamber, semiconductor wafers on which layers of thin film are to be grown are placed on rapidly-rotating carousels, referred to as wafer carriers, to provide a uniform exposure of their surfaces to the atmosphere within the reactor chamber for the deposition of the semiconductor materials. Rotation speed is on the order of 1,000 RPM. The wafer carriers are typically machined out of a highly thermally conductive material such as graphite, and coated with a protective layer of a material such as silicon carbide. Each wafer carrier has a set of circular indentations, or pockets, in its top surface in which individual wafers are placed. Typically, the wafers are supported in spaced relationship to the bottom surface of each of the pockets to permit the flow of gas around the edges of the wafer. Some examples of pertinent technology are described in U.S. Patent Application Publication No. 2012/0040097, U.S. Pat. No. 8,092,599, U.S. Pat. No. 8,021,487, U.S. Patent Application Publication No. 2007/0186853, U.S. Pat. No. 6,902,623, U.S. Pat. No. 6,506,252, and U.S. Pat. No. 6,492,625, the disclosures of which are incorporated by reference herein.
The wafer carrier is supported on a spindle within the reaction chamber so that the top surface of the wafer carrier having the exposed surfaces of the wafers faces upwardly toward a gas distribution device. While the spindle is rotated, the gas is directed downwardly onto the top surface of the wafer carrier and flows across the top surface toward the periphery of the wafer carrier. The used gas is evacuated from the reaction chamber through ports disposed below the wafer carrier. The wafer carrier is maintained at the desired elevated temperature by heating elements, typically electrical resistive heating elements disposed below the bottom surface of the wafer carrier. These heating elements are maintained at a temperature above the desired temperature of the wafer surfaces, whereas the gas distribution device typically is maintained at a temperature well below the desired reaction temperature so as to prevent premature reaction of the gases. Therefore, heat is transferred from the heating elements to the bottom surface of the wafer carrier and flows upwardly through the wafer carrier to the individual wafers.
A great deal of effort has been devoted to system design features to minimize temperature and flow variations during processing; however, the problem continues to present many challenges, especially in light of the need to process greater numbers of wafers, and larger-sized wafers, in each batch.
In order to minimize the effect of radiation heat loss and to improve the uniformity of the deposited material over the entire surface of the wafer carrier, a ring-shaped fixture called a flow extender is situated in close proximity surrounding the outer edge of the wafer carrier. During the MOCVD growth process the flow stream of non-reacted gases is redirected by the flow extender along a specific path to the chamber's exhaust. Behind the flow extender is situated a shutter mechanism that isolates the reaction space from the walls of the process chamber. As its name implies, the shutter operates to vent gasses in order to control pressure and flow characteristics in the reaction space.
As an unintended consequence, GaN materials are deposited on the surfaces of the flow extender and shutter. These deposits build up over time and over repeated processing cycles, and tend to adversely affect wafer processing. For example, the material deposited on the flow extender can desorb from the flow extender surface and flow back onto the wafers, resulting in excessive and non-uniform deposition on the wafers. The deposits can also continue to accumulate on the surface of the flow extender and adjacent fixtures, such as the shutter assembly, and cause changes in the gas flow pattern, creating eddy currents, etc., disrupting the intended boundary layer dynamics across the entire wafer carrier. The build-up of deposits further affects heat reflectivity from the coated structures. These effects cause variations in processing results and, ultimately, result in reduced product yields.
Currently, process chambers that utilize a flow extender must be subjected to regular cleanings every 15-30 runs. This frequent cleaning regiment represents an increase in the MOCVD tool preventive maintenance by a factor of four times that of a comparable tool without a flow extender. With each cleaning requiring opening and disassembling portions of the process chamber, the increased cleaning significantly diminishes factory throughput and overall yield, as well as increasing the cost of maintaining the tool.
In view of the above, a practical solution is needed to alleviate the burden of cleaning of material deposition systems.
Aspects of the invention are directed to in situ cleaning of a material deposition tool's process chamber, such as a process chamber of a chemical vapor deposition (CVD) tool. The in-situ cleaning is achieved without having to disassemble the process chamber to perform the cleaning operation. Instead, according to solutions provided in accordance with embodiments of the invention, a cleaning mechanism is deployed that works with existing functionality of the material deposition tool itself.
In one aspect, a method is provided for in-situ cleaning of a process chamber of a material deposition tool that is adapted for use with a removable wafer carrier. The removable wafer carrier has an outer form factor defined based on predefined operational clearances within the process chamber. This method includes loading a specialized cleaning carrier into the process chamber in place of an ordinary wafer carrier. The material deposition tool executes a cleaning process that includes rotation of the cleaning carrier. During the cleaning process, the cleaning carrier deploys a set of deployable and retractable brushes such that at least one cleaning element of each brush contacts an interior surface of the process chamber and the rotation of the cleaning carrier causes that cleaning element to scrub the interior surface to remove material deposits from that surface. At the conclusion of the cleaning process the cleaning carrier retracts the set of brushes such that each of the cleaning elements of each of the brushes ceases contact with the interior surface of the process chamber. The cleaning carrier is then unloaded from the process chamber.
In one embodiment, a cleaning carrier includes a cleaning carrier body formed symmetrically about a central axis and having a geometry generally corresponding to the geometry of the removable wafer carrier such that the cleaning carrier body has outer boundaries within, the same as, or not substantially exceeding, the outer form factor of the removable wafer carrier. The cleaning carrier also includes a tool interface that facilitates mounting of the cleaning carrier body on a portion of the material deposition tool that accepts the removable wafer carrier, such as a spindle, for instance. A set of deployable and retractable brushes are operatively coupled with the cleaning carrier body via a corresponding set of deployment and retraction mechanisms. The brushes are movable between a retracted position and a deployed position such that in the retracted position, the brushes are situated within the outer form factor and, in the deployed position, the brushes protrude beyond the outer form factor.
In a particular embodiment, a process condition, such as rotation of the cleaning carrier, causes deployment of the brushes. In another particular embodiment, the cleaning carrier further includes an anti-slip mechanism constructed to engage and disengage a drive mechanism of the material deposition tool on which the wafer carrier rotates. The engagement with the drive mechanism increases a degree of coupling between the cleaning carrier body and the drive mechanism so as to reduce slippage between the drive mechanism and cleaning carrier during the rotation. In a related embodiment, the anti-slip mechanism is a clamping mechanism that is engaged in response to rotation of the cleaning carrier. Various other embodiments are described herein.
In a related aspect of the invention, a cleaning carrier such as the one described above is provided as part of a CVD apparatus that includes a process chamber, a rotatable spindle disposed inside the process chamber, a wafer carrier for transporting and providing a support for one or more wafers, and a heating element. The cleaning carrier is operated in place of the wafer carrier as part of carrying out a cleaning process.
In another aspect of the invention, a cleaning carrier includes a cleaning carrier body formed symmetrically about a central axis and having a geometry generally corresponding to the geometry of the removable wafer carrier, a tool interface, and at least one cleaning element adapted to clean an interior surface of the process chamber. The tool interface facilitates mounting of the cleaning carrier body on a portion of the material deposition tool that accepts the removable wafer carrier. The tool interface comprises an anti-slip mechanism operatively coupled to the cleaning carrier body and constructed to engage and disengage a drive mechanism of the material deposition tool on which the wafer carrier rotates during operation. The engagement with the drive mechanism increases a degree of coupling between the cleaning carrier body and the drive mechanism so as to reduce slippage between the drive mechanism and cleaning carrier during the rotation.
Likewise, in a related aspect of the invention, a cleaning carrier such as the one described above is provided as part of a greater CVD apparatus.
In other aspects of the invention, the anti-slip mechanism may be used as part of a wafer carrier to improve the coupling between the wafer carrier and the drive mechanism of the process chamber. The anti-slip mechanism may further be used with other specialized carriers, for cleaning, testing, calibration, or otherwise, to improve the coupling to the drive mechanism.
The invention may be more completely understood in consideration of the following detailed description of various embodiments of the invention in connection with the accompanying drawings, in which:
While the invention is amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail. It should be understood, however, that the intention is not to limit the invention to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.
Gas distribution device 12 is connected to sources 14a, 14b, 14c for supplying process gases to be used in the wafer treatment process, such as a carrier gas and reactant gases such as a metalorganic compound and a source of a group V metal. The gas distribution device 12 is arranged to receive the various gases and direct a flow of process gasses generally in the downward direction. The gas distribution device 12 desirably is also connected to a coolant system 16 arranged to circulate a liquid through the gas distribution device so as to maintain the temperature of the gas distribution device at a desired temperature during operation. A similar coolant arrangement (not shown) can be provided for cooling the walls of chamber 8. Chamber 8 is also equipped with an exhaust system 18 arranged to remove spent gases from the interior of the chamber through ports (not shown) at or near the bottom of the chamber so as to permit continuous flow of gas in the downward direction from the gas distribution device.
A spindle 20 is arranged within the chamber so that the central axis 22 of the spindle extends in the upward and downward directions. The spindle is mounted to the chamber by a conventional rotary pass-through device 25 incorporating bearings and seals (not shown) so that the spindle can rotate about axis 22, while maintaining a seal between the spindle and the wall of chamber 8. The spindle has a fitting 24 at its top end, i.e., at the end of the spindle closest to the gas distribution device 12. As further discussed below, fitting 24 is an example of a wafer carrier retention mechanism adapted to releasably engage a wafer carrier. In the particular embodiment depicted, the fitting 24 is a generally frustoconical element tapering toward the top end of the spindle and terminating at a flat top surface. A frustoconical element is an element having the shape of a frustum of a cone. Spindle 20 is connected to a rotary drive mechanism 26 such as an electric motor drive, which is arranged to rotate the spindle about axis 22.
A heating element 70 is mounted within the chamber and surrounds spindle 20 below fitting 24. The chamber is also provided with an entry opening 72 leading to an antechamber 76, and a door 74 for closing and opening the entry opening. Door 74 is depicted only schematically in
The CVD apparatus operates with a wafer carrier 80, illustrates in greater detail in
The body 82 desirably is formed from materials which do not contaminate the process and which can withstand the temperatures encountered in the process. For example, the larger portion of the disc may be formed largely or entirely from materials such as graphite, silicon carbide, or other refractory materials. The body 82 has a generally planar top surface 88 and a bottom surface 90 extending generally parallel to one another and generally perpendicular to the central axis 84 of the disc. Overall, wafer carrier 80 has an outer form factor that corresponds to the process chamber in which it is to be used. The outer form factor has boundaries based on the required operational clearances with respect to interior surfaces and other features within the process chamber that must be maintained according to the particular mechanical design of the tool.
Referring again to
Heaters 70 transfer heat to the bottom surface 90 of the wafer carrier, principally by radiant heat transfer. The heat applied to the bottom surface of the wafer carrier flows upwardly through the body 82 of the wafer carrier to the top surface 88 of the wafer carrier. Heat passing upwardly through the body also passes upwardly through gaps to the bottom surface of each wafer, and upwardly through the wafer to the top surface 126 of the wafer. Heat is radiated from the top surface 88 of the wafer carrier and from the top surfaces 126 of the wafer to other parts of the process chamber such as, for example, to the walls of the process chamber and to the gas distribution device 12. Heat is also transferred from the top surface 88 of the wafer carrier and the top surfaces 126 of the wafers to the process gas passing over these surfaces.
In some embodiments, temperature monitor 94 and temperature profiling system 96 are used as parts of a monitoring system to determine the spatial distribution of heat applied to the surfaces of the wafers during processing.
In a related embodiment, gas inlet structure 12 is heated to increase the temperature of the gas as it enters the process chamber. Higher-temperature gas reduces the thermal gradient in the wafers as most of the heat is applied through their bottom surface. This, in turn, reduces thermally-induced deformation, e.g., bowing, of the wafers. As an unintended consequence, the increased gas temperature results in more of the reactive gasses depositing material on interior surfaces of the wafer chamber, particularly on the flow extender and shutter.
According to one type of embodiment, a cleaning carrier 100 is utilized to clean nearby surfaces. Cleaning carrier 100 is constructed to have a similar size, shape, and mass as an actual wafer carrier 80, and includes tool interface 103 that is similar to that of a wafer carrier 82. These similarities allow the cleaning carrier 100 to be automatically handled by the CVD system in the same manner in which an actual wafer carrier 80 is handled. Thus, for example, cleaning carrier 100 is constructed to be placed on spindle 20 and rotated according to a particular recipe.
The materials from which the body of cleaning carrier 100 is made include aluminum alloy, stainless steel, and any other suitable material (or combination of materials). Factors that may be considered in selecting an appropriate material for a particular application are cost, ease of machining, vacuum/gas compatibility, durability, temperature rating, density, and effect on processing. In one related embodiment, the mass distribution of cleaning carrier 100 is specifically made to differ from wafer carrier 80 in order to increase the moment of inertia of cleaning carrier 100 to smooth out any sudden changes in loading on the drive mechanism possibly caused by operation of the cleaning carrier 100 in a cleaning process.
In terms of dimensions, cleaning carrier 100 has a form factor that corresponds to (i.e., matches, fits within, or does not substantially exceed) the outer form factor of wafer carrier 80 that corresponds to the process chamber in which it is to be used. Thus, cleaning carrier 100 practically respects the required clearances within the process chamber so that cleaning carrier 100 is compatible with the process chamber with which it is to be used.
Instead of having wafer retention sites that an actual wafer carrier 82 has, cleaning carrier 100 includes a set of deployable brushes 102 that can move from a normally retracted position to a deployed position. In one type of embodiment, the deployable brushes 102 are deployed in response to a condition established in the process chamber, such as rotation of the spindle, temperature change, pressure change, etc.
When deployed, brushes 102 protrude beyond the outer form factor that a wafer carrier would ordinarily fit within, and the brushes 102 engage with specific interior surfaces of the process chamber 8. Rotation of the cleaning carrier 100 on spindle 20 causes the brushes to scrub those specific interior surfaces to remove any material deposits. Brushes 102 have a cleaning element, such as a set of bristles, that works to remove deposited material from the surfaces to be cleaned. It should be noted that, in various other embodiments, the cleaning element of the brush may have a structure other than bristles. Examples include a textured surface, an elastomeric surface, a polishing structure, an abrasive structure, or the like. Thus, the term brush as used herein can include any one, or a combination, of a variety of contemplated mechanical cleaning elements for removing material from a surface.
Deployment and refraction mechanism 104 is situated near the outer periphery of cleaning carrier 100. Deployment and retraction mechanism 104 operates to retain the brushes 102 in the retracted position in the absence of a cleaning process, and to deploy the brushes in response to an applied condition by operation of the cleaning process. In one particular embodiment, the condition applied by operation of the cleaning process is rotation of the cleaning carrier 100, which applies centripetal forces to the deployment and retraction mechanism 104 and brush 102.
In a related embodiment, examples of which are described in greater detail below, cleaning carrier 100 includes an anti-slip mechanism 106 that operates to more tightly couple the wafer carrier to the drive mechanism. This feature is useful by itself, or in conjunction with the cleaning brushes, which cause friction with interior surfaces of the process chamber that can, in turn, cause slippage between the drive mechanism and cleaning carrier. In a related embodiment, the anti-slip mechanism is engaged in response to the applied condition by operation of the cleaning process, and to otherwise normally disengage. In a particular embodiment, which is described in detail below, the anti-slip mechanism 106 is in the form of a clamping mechanism that is adapted to grip the spindle of the drive mechanism.
It is also contemplated that in other embodiments (not shown) the brushes may have bifurcated ends such as y-shaped forked arms with a cleaning element at each forked end. More generally, aspects of the invention relate to any brush geometry that can be suitable for cleaning an one or more interior chamber surfaces.
In the embodiment depicted in this example, brush 202 includes a movable arm 210 that is slidably coupled to body 205 via a track. In this particular case, the track is in the form of guide cutout 214, described in greater detail below. In various other embodiments, the track can take other forms, e.g., one or more grooves, rails, bearings, etc. Brush 202 has a cleaning element at its distal end. In the embodiment shown, the cleaning element is in the form of bristles 212 made from a suitable material to provide sufficient cleaning performance without damaging the surface to be cleaned. The location and profile of bristles 212 is designed to correspond to the profile of the surface to be cleaned. Suitable materials for the bristles include, without limitation, metal wire strands, polymer strands, strands made from composite material, or any combination thereof.
In its retracted position, brush 202 is entirely recessed within the boundaries of body 205 according to this particular embodiment, though in other embodiments it may be sufficient for the distal end of brush 202 to be retracted within the form factor ordinarily occupied by a wafer carrier (e.g., so as to not protrude substantially past distal end 207 of body 205).
Brush 202 is normally held in its retracted position due to the operation of biasing member 216, which urges proximal end of arm 210 towards proximal end 209 of body 205. In the particular example depicted, biasing member 216 is in the form of a tension coil spring, though in various other embodiments entirely different biasing members are contemplated. For instance, biasing member may be a compression element that is situated near the distal end 207 of member 205 and pushes, rather than pulls, arm 210. Also, various materials and structures for biasing member 216 are contemplated, such as those made from elastomeric materials.
In operation, the biasing force of biasing member 216 is overcome to reposition brush 202 from its retracted position into its deployed position. In the exemplary embodiment depicted, the rotation of cleaning carrier 200 causes brush 202 to experience a centrifugal force (i.e., towards distal end 207 of body 205). This centrifugal force applied to the mass of brush 202 exceeds the tension force of the tension coil spring biasing member 216, causing brush 202 to slidably deploy outwards, i.e., towards the distal end 207, along guide cutouts 214. In one particular embodiment, the biasing force of biasing member 216 is designed to correspond to a particular minimum rotation speed below which the brushes 202 cannot deploy.
In the absence of rotation, biasing member 316 (which in this example is a compression coil spring) pushes on piston end 317 to retract brush 302b. In operation, centrifugal forces experienced by brush 302b overcome the force of biasing member 316 to cause outward movement of arm 310. Ramp 318 and pivot 320 allow arm 310 to tilt upwards as it move outwards. Stopper 322 butts up against bumper 324 at the set distance when the arm brush 302b is fully deployed.
In related embodiments, other process-induced conditions are utilized to deploy the brushes. In one such embodiment, instead of the centripetal/centrifugal forces applied to deploy the brushes, a reduced pressure in the chamber is employed. In this embodiment, referring to
In another related embodiment, heat-activated materials are used to deploy the brushes. When the temperature is raised in the process chamber, the heat-activated materials change their shape and, either directly, or through a movement magnification mechanism such as a lever, exert an outward force on the brushes so as to deploy them.
In another type of embodiment, the brushes can be deployed using one or more electromechanical actuators that can be controlled to activate and deploy brushes in response to process conditions such as raised temperature, reduced pressure, rotation, etc., or in response to applied electromagnetic signaling, such as RF, IR, etc.
In one particular application, spindle clamping mechanism 406 is used in conjunction with the cleaning brushes in a cleaning carrier 100 to prevent or reduce slippage of the cleaning carrier due to the friction created when scrubbing the surfaces subjected to cleaning with the brushes. Accordingly, in a related embodiment of cleaning carrier 400, brush retention and deployment mechanisms 404 are included.
Clamping mechanism 406 includes a group of rods 440 situated radially, and evenly spaced about central axis 84. At the proximal end of each rod 440 is a clamping surface constructed to engage with the shaft on which cleaning carrier 400 spins. At the distal end of each rod 440 is a movable mass 442 mounted at a first end of lever 444. Lever 444 pivots at fulcrum 446. At the second end of lever 444 is a connection to rod 440.
Movement of mass 442 in the distal direction (such as in response to centrifugal forces felt by mass 442) causes rod 440 to move in the proximal direction, i.e., towards central axis 84. Fulcrum 446 is positioned along the length of lever 444 to increase the force applied to the rod 440. Rod 440 slides along a radially-oriented channel (not shown), which may be in the form of an elongate recess or groove.
Biasing member 448 is arranged to urge clamping mechanism 406 to move to the released position. Therefore, in operation, the process condition applied to cleaning carrier 400 must be sufficient to overcome the biasing force of biasing member 448. In various embodiments, biasing member 448 is in the form of a spring (e.g., compression coil spring, tension coil spring, etc.), or some other suitable resilient or elastic material and structure for applying tension or compression.
In the absence of rotation of the cleaning carrier, there is no centrifugal force experienced by the mass 442, and biasing member 448 urges long arm 444a upwards, which tends to draw rod 440 away from spindle 20.
Importantly, it should be noted that the spindle clamping mechanism described herein, while disclosed in conjunction with a cleaning carrier, may be utilized in applications other than cleaning. For instance, the spindle clamping mechanism embodiments may be used with an actual wafer carrier to improve coupling with the spindle of the drive mechanism. Still other applications are contemplated in which the spindle clamping mechanism is used with “dummy” carriers for other purposes.
At 506, the condition of rotation of the cleaning carrier is initiated. In the cleaning recipe according to one embodiment, the target speed of rotation can be quite different from the rotation speed used in wafer processing. For instance, in a system applying speeds on the order of 1,000 RPM for wafer processing, a slower speed of around 400 RPM may be used in the cleaning recipe. In other embodiments, the cleaning recipe can use similar speeds to those used in material deposition processes, or speeds that are even faster.
In response to the applied condition which, in this example, is rotation of the cleaning carrier, the brushes are deployed by the cleaning carrier at 508. As in some of the embodiments described above, a centrifugal mechanism is used to deploy the brushes, though other deployment mechanisms may also be used in other embodiments as described above, in which the brushes are deployed in response to an environmental change in the process chamber. At 510, in embodiments having a spindle clamp, the clamp engages to grab the spindle. As with the deployment mechanism of the brushes, the spindle clamp engagement mechanism may operate on a centrifugal principle, or based on another process environment change. The deployment of the brushes at 508 and engagement of the spindle clamp at 510 can occur simultaneously, or in any order, depending on the particular configuration of these mechanisms in the cleaning carrier.
At 512, gas flow is provided in the process chamber according to one embodiment. The function of the gas flow is to carry away the removed particulate matter from operation of the brushes to the effluent channel of the process chamber. In one implementation, inert gas is used; whereas in another approach a reactive gas component is used to assist with desorption of the material from the surfaces being cleaned. In another related embodiment, at 514, the process chamber is heated to assist with the removal of material. In this embodiment, a temperature at which the deposited material tends to more easily release from the surface being cleaned is preferably utilized. The order in which the temperature is raised at 514 and gas flow 512 is provided can vary according to different embodiments. Likewise, any of these operations may take place before or after the deployment of brushes and engagement of the spindle clamp at 508 and 510, respectively.
The cleaning operation in which the brushes clean their corresponding surfaces continues for a predetermined time according to the cleaning recipe, or until the occurrence of a certain event indicative of the completion of the cleaning, such as a detection of cessation of particulate material in the effluent channel. Subsequently, at 516, the cleaning process is wound up. Accordingly, rotation of the cleaning carrier is decelerated until the carrier stops, and the supply of gas flow and heating, where used, is ceased. During the deceleration, in the centrifugal embodiments, at 518 and 520, respectively, the cleaning carrier retracts the brushes at 518, and the cleaning carrier disengages the spindle clamp at 510 if the clamp is employed. In the other, non-centrifugal, embodiments, the cessation of environmental conditions which caused deployment of the brushes and engagement of the spindle clamp causes these mechanisms to return to their nominal state of retraction and disengagement. At 522, the cleaning recipe is completed and, at 524, the cleaning carrier is unloaded from the process chamber in similar fashion to the unloading of a wafer carrier.
The embodiments above are intended to be illustrative and not limiting. Additional embodiments are within the claims. In addition, although aspects of the present invention have been described with reference to particular embodiments, those skilled in the art will recognize that changes can be made in form and detail without departing from the scope of the invention, as defined by the claims.
Persons of ordinary skill in the relevant arts will recognize that the invention may comprise fewer features than illustrated in any individual embodiment described above. The embodiments described herein are not meant to be an exhaustive presentation of the ways in which the various features of the invention may be combined. Accordingly, the embodiments are not mutually exclusive combinations of features; rather, the invention may comprise a combination of different individual features selected from different individual embodiments, as will be understood by persons of ordinary skill in the art.
Any incorporation by reference of documents above is limited such that no subject matter is incorporated that is contrary to the explicit disclosure herein. Any incorporation by reference of documents above is further limited such that no claims that are included in the documents are incorporated by reference into the claims of the present Application. The claims of any of the documents are, however, incorporated as part of the disclosure herein, unless specifically excluded. Any incorporation by reference of documents above is yet further limited such that any definitions provided in the documents are not incorporated by reference herein unless expressly included herein.
For purposes of interpreting the claims for the present invention, it is expressly intended that the provisions of Section 112, sixth paragraph of 35 U.S.C. are not to be invoked unless the specific terms “means for” or “step for” are recited in a claim.
