Patent ID: 12242197

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, or examples, for implementing different features of the invention. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. For example, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed between the first and second features, such that the first and second features may not be in direct contact. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The apparatus may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may likewise be interpreted accordingly.

Embodiments will be described with respect to a specific context, namely a wafer baking station utilized in the manufacturing of semiconductor devices. The wafer baking station described herein may be any semiconductor wafer baking apparatus such as a pre-development bake station (e.g., pre-bake station), a post-development station (e.g., post-bake station), a hard bake station, a diffusion bake station, or the like. Features of one embodiment may also be applied and suitably incorporated as features of other embodiments described herein. Other embodiments may also be applied, however, to other manufacturing apparatuses.

With reference now toFIG.1, there is shown a photoresist track system100with a first loadlock chamber102, a coating station101, a pre-bake station103, an exposure station105, a post-bake station107, a developer station109, an optional hard bake station111, a plurality of the transfer stations104, and a second loadlock chamber114. In an embodiment, the photoresist track system100is a track system for processing a substrate201(not illustrated inFIG.1but illustrated and discussed below with respect toFIG.2B), and is a self-enclosed, fully contained system into which the substrate201may be initially placed. Once within the photoresist track system100, the substrate201may be moved from station to station and processed without breaking the interior environment, thereby isolating the substrate201from the ambient environment that may contaminate or otherwise interfere with the processing of the substrate201.

In an embodiment, the photoresist track system100receives the substrate201into the photoresist track system100through, e.g., the first loadlock chamber102. The first loadlock chamber102opens to the exterior atmosphere and receives the substrate201. Once the substrate201is located within the first loadlock chamber102, the first loadlock chamber102can close, isolating the substrate201from the exterior atmosphere. Once isolated, the first loadlock chamber102can then have the remaining exterior atmosphere evacuated in preparation for moving the substrate201into the remainder of the photoresist track system100through, e.g., a transfer station104.

The transfer station104may be one or more robotic arms (not individually illustrated inFIG.1) that can grip, move, and transfer the substrate201from the first loadlock chamber102to, e.g., the coating station101. In an embodiment, the robotic arms may extend into the first loadlock chamber102, grip the substrate201, and transfer the substrate201into the transfer station104. Once inside, the transfer station104may have doors that close to isolate the transfer station104from the first loadlock chamber102so that the first loadlock chamber102may again be opened to the exterior atmosphere without contaminating the remainder of the photoresist track system100. Once isolated from the first loadlock chamber102, the transfer station104may open to the next station, e.g., the coating station101, and the robotic arms, still holding the substrate201, may extend into the next station and place the substrate201for further processing.

In an embodiment, and as illustrated inFIG.1, the transfer station104between the first loadlock chamber102and the coating station101transfers the substrate201directly from the first loadlock chamber102into the coating station101. However, other processing stations (e.g., process chambers) may be located between the first loadlock chamber102and the coating station101. For example, cleaning stations, temperature control stations, or any other type of station which may be used to prepare the substrate201to receive a photoresist211(not illustrated inFIG.1but illustrated and discussed below with respect toFIG.2B) may also be included. Any suitable type or number of stations may be used, and all such stations are fully intended to be included within the scope of the embodiments.

Additionally,FIG.1illustrates a plurality of separate transfer stations104respectively between each of the processing stations (e.g., between the first loadlock chamber102and the coating station101, between the coating station101and the exposure station105, etc.). However, this is intended to be illustrative and is not intended to be limiting upon the embodiments. The precise number of transfer stations will depend at least in part upon the overall structural layout of the various processing stations. For example, if the processing stations are arranged in a linear fashion (as illustrated inFIG.1), then there may be individual transfer stations between each process station of the photoresist track system100. However, in other embodiments in which the various processing stations or groups of processing stations are arranged, e.g., in one or more circles, then a single transfer station may be utilized to move the substrates being processed (e.g., substrate201) into and out of the various process chambers. All such arrangements are fully intended to be included within the scope of the embodiments.

FIG.2Aillustrates a top view of one embodiment of the coating station101into which the transfer station104places the substrate201, andFIG.2Billustrating a cross-sectional view of the substrate201after being processed within the coating station101. In an embodiment, the coating station101is a spin-on station and comprises a rotating chuck202, a dispensing arm204, and a track206. The rotating chuck202receives the substrate201from the transfer station104and holds the substrate201during processing.

The dispensing arm204has a nozzle208in order to dispense photoresist211onto the substrate201. In an embodiment, the dispensing arm204may be moveable relative to the rotating chuck202so that the dispensing arm204can move over the substrate201(illustrated inFIG.2Aby the arrow and dispensing arm illustrated in dashed lines) in order to evenly dispense the photoresist211. The dispensing arm204may move back and forth with the help of the track206, which provides a fixed reference to assist the dispensing arm204in its movement.

During operation, the rotating chuck202, holding the substrate201, can rotate at a speed of about 300 rpms to about 7000 rpms, although any suitable speed may be utilized. While the rotating chuck202is rotating, the dispensing arm204may move over the substrate201and begin dispensing the photoresist211onto the substrate201through the nozzle208. The rotation of the substrate201helps the photoresist211spread evenly across the substrate201, such as to a thickness of between about 10 nm and about 300 nm, such as about 150 nm.

However, the spin-on configuration illustrated inFIG.2Aand described above is intended to be illustrative only and is not intended to limit the embodiments. Rather, any suitable configuration for the coating station101that may be used to apply the photoresist211, such as a dip coating configuration, an air-knife coating configuration, a curtain coating configuration, a wire-bar coating configuration, a gravure coating configuration, a lamination configuration, an extrusion coating configuration, combinations of these, or the like, may also be utilized. All such suitable configurations for the coating station101are fully intended to be included within the scope of the embodiments.

FIG.2Billustrates a semiconductor device200with the substrate201after the dispensing of the photoresist211. Also illustrated as being formed on the substrate201(prior to the application of the photoresist211) are active devices203on the substrate201, an interlayer dielectric (ILD) layer (e.g., the ILD layer205) over the active devices203, metallization layers207over the ILD layer205, and a layer to be patterned209over the ILD layer205. The substrate201may comprise bulk silicon, doped or undoped, or an active layer of a silicon-on-insulator (SOI) substrate. Generally, an SOI substrate comprises a layer of a semiconductor material such as silicon, germanium, silicon germanium, SOI, silicon germanium on insulator (SGOI), or combinations thereof. Other substrates that may be used include multi-layered substrates, gradient substrates, or hybrid orientation substrates.

The active devices203are represented inFIG.2Bas a single transistor for illustration purpose. However, a wide variety of active devices such as capacitors, resistors, inductors and the like may be used to generate the desired structural and functional requirements of the design for the semiconductor device200. The active devices203may be formed using any suitable methods either within or else on the surface of the substrate201.

The ILD layer205may comprise a material such as boron phosphorous silicate glass (BPSG), although any suitable dielectrics may be used for either layer. The ILD layer205may be formed using a process such as PECVD, although other processes, such as LPCVD, may also be used. The ILD layer205may be formed to a thickness of between about 100 Å and about 3,000 Å.

The metallization layers207are formed over the substrate201, the active devices203, and the ILD layer205, and are designed to connect the active devices203to form functional circuitry. While illustrated inFIG.2Bas a single layer, the metallization layers207may be formed of alternating layers of dielectric and conductive material, and may be formed through any suitable process (such as deposition, damascene, dual damascene, etc.). In an embodiment, there may be four to twelve layers of metallization separated from the substrate201by the ILD layer205, but the precise number of metallization layers207is dependent upon the design of the semiconductor device200.

The layer to be patterned209or otherwise processed using the photoresist211is formed over the metallization layers207. The layer to be patterned209may be an upper layer of the metallization layers207, a dielectric layer (such as a passivation layer) formed over the metallization layers207, or may even be the substrate201itself. In an embodiment. in which the layer to be patterned209is a metallization layer, the layer to be patterned209may be formed of a conductive material using processes similar to the processes used for the metallization layers (e.g., damascene, dual damascene, deposition, etc.). Also, if the layer to be patterned209is a dielectric layer, it may be formed of a dielectric material using processes such as deposition, oxidation, or the like.

However, while materials, processes, and other details are described in the embodiments, they are merely intended to be illustrative of embodiments, and are not intended to be limiting in any fashion. Rather, any suitable layer made of any suitable material, by any suitable process, and any suitable thickness, may also be used. All such layers are fully intended to be included within the scope of the embodiments.

The photoresist211is applied to the layer to be patterned209. In an embodiment the photoresist211includes a polymer resin along with one or more photoactive compounds (PACs) in a solvent. Additionally, if desired, other additives, such as cross-linking additives, surfactants, etc. may also be included within the solvent and the photoresist211. Any suitable composition may be utilized.

FIGS.3A-3Hillustrate various views of the pre-bake station103and various views of some components of the pre-bake station103with respect to different cut-lines, according to some embodiments. In particular,FIG.3Aillustrates a cross-sectional view of the pre-bake station103through a first cut-line A-A′,FIG.3Billustrates a top view of a hot plate301of the pre-bake station103, andFIG.3Cillustrates a top view of a trench plate320(e.g., a first cover plate, a vented cover disk, or the like) of the pre-bake station103, respectively.FIGS.3D-3Eillustrate cross-sectional views of the pre-bake station103through a second cut-line B-B′ and through a third cut-line C-C′, respectively.FIGS.3F-3Gillustrate a bottom view of a cover plate340(e.g., a second cover plate, an exhaust cover disk, or the like) of the pre-bake station103and a magnified view of a portion of the bottom view of the cover plate340, respectively.FIG.3Hillustrates an exploded view of an exhaust hood assembly380of the pre-bake station103.

FIG.3Aillustrates the pre-bake station103into which the substrate201with the photoresist211(not specifically illustrated inFIG.3A) thereon, may be moved (through the transfer station104) once the photoresist211has been applied to the substrate201. According to some embodiments, the robotic arm of the transfer station104places the substrate201on the hot plate301of the pre-bake station103in preparation for further processing. The hot plate301raises the temperature of the substrate201and photoresist211in order to cure and dry the photoresist211prior to exposure to finish the application of the photoresist211.

The pre-bake station103may be connected, for example, to intake pipes (not shown) in order to introduce air into the pre-bake station103. The pre-bake station103may also be connected, for example, to one or more exhaust pipes (not shown) and one or more dampers (not shown) to assist in the evacuation and to vary a flow rate of volatile by-products of the pre-bake process300, such as components of the evaporated solvent (illustrated by the directional arrows inFIG.3A), from the pre-bake station103.

The curing and drying of the photoresist211removes the solvent components while leaving behind the polymer resin, the PACs, cross-linking agents, and other chosen additives. In an embodiment, a pre-bake process300may be performed at a temperature suitable to evaporate the solvent(s), such as between about 40° C. and 150° C., although the precise temperature depends at least in part upon the materials chosen for the photoresist211. The pre-bake process300is performed for a time sufficient to cure and dry the photoresist211, such as between about 10 seconds to about 10 minutes, such as about 90 seconds. As the solvent evaporates during the pre-bake process300, the vapor of the evaporated solvent rises (as illustrated inFIG.3Aby the directional arrows) and ultimately escapes through the trench plate320and through the exhaust hood assembly380.

However, as the vapors of the evaporated solvent rise, there is a possibility that the vapors will cool down so much that the vapors will condense before the vapors exhaust from the pre-bake station103. In some cases, these condensed vapors, now becoming liquid again, can either drop onto the wafer currently being processed, drop onto the next semiconductor wafer in the process, or else interfere with the exhaust flow. By falling back down to the substrate201(or subsequent substrates), the condensed liquid can interfere with the desired evaporation and drying process. Such interference can interfere with subsequent processes, thereby causing undesired defects within the manufactured device(s).

To help alleviate or prevent these defects, the exhaust hood assembly can be designed to both minimize the amount of condensation and the undesired effects due to the condensation. In an embodiment, the exhaust hood assembly380secures and suspends the trench plate320over the substrate201during baking processes (e.g., the pre-bake process300). According to some embodiments, the exhaust hood assembly380comprises a retaining ring330, the trench plate320, a cover plate340, an exhaust pipe header350, and an exhaust hood heater360.

The retaining ring330secures the trench plate320to the cover plate340. According to some embodiments, the trench plate320is secured by the retaining ring330to the cover plate340using fasteners (e.g., screws, threaded bolts, and the like). However, any suitable fasteners and/or any suitable way to secure the trench plate320between the retaining ring330and the cover plate340(e.g., clamping, snap-fitting, and the like) may also be used.

In an embodiment, the trench plate320comprises ridges321, trenches325and vent holes323. According to embodiments, the vent holes323are located in the ridges321and extend through the ridges321and the trench plate320from the top of the ridges321to the bottom surface of the trench plate320opposite the top surfaces of the ridges321. In some embodiments, the bottom surface of the trench plate320is substantially planar (within the range of manufacturing deviation); however, any suitable shape may be used. During baking processes (e.g., the pre-bake process300), as vapor forms and rises from the evaporated solvent, the vapor escapes through the vent holes323of the trench plate320and makes its way up towards the cover plate340.

The cover plate340serves as a lid covering the trench plate320with inner sidewalls of the cover plate340, forming a first angle θ1with the upper surface of the trench plate320. According to some embodiments, the first angle θ1is between about 30° and about 90°, such as about 90°. However, any suitable angle may be used. The cover plate340further comprises grooves343and an opening317. During baking processes (e.g., the pre-bake process300), the inner sidewalls of the cover plate340and the grooves343located in the inner sidewalls of the cover plate340aid in directing the vapor escaping through vent holes323of the trench plate320to the opening317in the cover plate340where the exhaust pipe header350is attached. According to some embodiments, the opening317in the cover plate340comprises a first diameter DIA1of between about 20 mm and about 40 mm, such as about 30 mm, and the exhaust pipe header350is sized to fit the opening317of the cover plate340. However, any suitable dimensions may be used for the opening317of the cover plate340and the exhaust pipe header350.

According to embodiments, the exhaust hood assembly380comprises a single pipe for the exhaust pipe header350attached to the opening317in the cover plate340. The opening317and the exhaust pipe header350are of sufficient size to maintain a flow level and exhaust efficiency for evacuating vapor from the exhaust hood assembly380during bake processes. In an embodiment the flow level may be between about 20 Pa and about 500 Pa, such as about 300 Pa. However, any suitable flow level may be utilized.

In an embodiment the exhaust pipe header350may be integrally formed with the cover plate340or may be attached to the cover plate340. According to some embodiments, the exhaust pipe header350comprises the same diameter or substantially the same diameter as the first diameter DIA1and is between about 20 mm and about 40 mm, such as about 30 mm. However, any suitable diameter may be utilized.

The design of the cover plate340and the exhaust pipe header350with a large opening may further facilitate the exhaust flow, because the flow level may be maintained at a high level in order to remove the vapors from the exhaust hood assembly380as quickly as possible. With such a quick removal, it significantly reduces the time for the vapors to cool down before exhausted, thereby reducing the possibility of the vapors condensing. As such, with less condensation, fewer defects from condensing liquids can be achieved in the final manufactured product. In addition, due to the large opening, the condensed vapors at the pipe may not block the opening. For example, because the vapors escape rapidly through the single large opening of the exhaust pipe header350, less vapor accumulates at the surface of the cover plate340as compared to a design having a plurality of exhaust headers with relatively small openings and a restrictive exhaust flow.

Additionally, in an effort to help increase the exhaust flow rate of the vapors out of the exhaust hood assembly before the vapors can condense, in some embodiments, the surfaces of the cover plate340, the exhaust pipe header350, and the trench plate320can be coated with a layer of nonstick coating to help reduce the friction and allow the vapors to flow faster out of the exhaust pipe header350. In an embodiment. the nonstick coating may comprise a non-stick material with a low coefficient of friction as well as hydrophobic properties such as polytetrafluoroethylene (PTFE), fluorinated ethylene propylene (FEP), perfluoroalkoxy (PFA), other fluorocarbons, combinations of these, or the like. However, any suitable material may be utilized.

The low coefficient of friction and hydrophobic properties of the nonstick coating, during bake processes, help reduce the amount of solvent vapor that condenses and wets these surfaces when the chemical solvent vapor comes in contact the cover plate340, the exhaust pipe header350, and the trench plate320. As such, the nonstick coating aids in the evacuation of the vapor through the vent holes323of the trench plate320and through the exhaust hood assembly380, which provides greater exhaust efficiency during bake processes. During the baking process or even after the bake processes, and when the exhaust hood assembly380begins to cool down, the amount of a residue of the evaporated solvent that forms on these inner surfaces is minimized. As such, damages caused by residue falling onto the substrate201during processing or falling onto subsequently processed workpieces during subsequent bake processes are also minimized or are altogether eliminated.

FIG.3Afurther illustrates the exhaust hood heater360being fixed to an outer surface of the cover plate340. In some embodiments, the exhaust hood heater360may be a resistive heating element, and may comprise one or more layers of suitable resistive materials, such as mica, quartz, polyimide, silicone rubber, semiconductor heater materials, metallic alloys, ceramic materials, ceramic metals, a combination thereof, or the like. During bake processes (e.g., the pre-bake process300), the exhaust hood heater360heats the cover plate340and the exhaust pipe header350to suitable temperatures in order to allow the evaporated solvent escape through the trench plate320as a vapor. According to some embodiments, the exhaust hood heater360heats the cover plate340and the exhaust pipe header350to a bake temperature of between about 40° C. and 150° C., although the precise temperature depends upon the thermal characteristics of the materials chosen for the photoresist211. As such, during bake processes, the exhaust hood heater360further aids in the evacuation of the vapor from the exhaust hood assembly380, which increases an exhaust efficiency of the pre-bake station103and further minimizes the amount of residue that forms from the evaporated solvent on the inner surfaces of the cover plate340and the exhaust pipe header350.

FIG.3Aalso illustrates trenches325, which are utilized to further reduce the possibility of the condensed vapors (if any) from reaching the substrate201. In an embodiment, the trenches325are utilized to help capture the condensed vapors therein (instead of simply letting the condensed vapors flow into the vent holes323). In an embodiment, the trenches325comprise substantially (within the range of manufacturing deviation) flat bottoms and angled sidewalls. According to some embodiments, the trenches325have a first width W1of between about 1 mm and about 60 mm, such as about 30 mm, a first depth D1 of between about 1 mm and about 20 mm, such as about 5 mm, and angled sidewalls having second angles θ2of between about 45° and about 90°, such as about 90°. However, any suitable widths, any suitable depths and any suitable angles may be used for the trenches325.

FIG.3Afurther illustrates residue390from the evaporated solvent that forms on the inner surfaces of the cover plate340and the exhaust pipe header350either during the bake processes or after the bake processes are completed, and temperatures within the pre-bake station103begin to cool down. As the residue390condenses and falls towards the trench plate320, the residue390is collected on the upper surfaces of the trench plate320. With the trenches325separating the vent holes323, any residue390that is condensed but not directly over the vent holes323will not flow into/through the vent holes323; instead, it will be collected within the trenches325of the trench plate320. As such, this prevents the residue390from flowing through the vent holes323dripping onto the substrate201, and causing damage to the substrate201.

FIG.3Billustrates a top view of the hot plate301, according to an embodiment. In some embodiments, heating elements305such as resistive heating elements may be located within the hot plate301. The heating elements305raise the temperature of the hot plate301during the bake processes.FIG.3Bfurther illustrates the cutline A-A′ through the hot plate301relative to the cut lines A-A′ illustrated inFIGS.3A and3C.

With reference now toFIG.3C, this figure illustrates a top view of the trench plate320in an embodiment. According to some embodiments, the trench plate320is integrally formed as a single structure with the trenches325being separated from one another by the ridges321. According to some embodiments, the trench plate320(e.g., vented cover disk) is annular in shape (e.g., a circular plate, a disk, or the like) having a second diameter DIA2of between about 180 mm and about 320 mm. However, any suitable shape and any suitable diameter may be used for the trench plate320. According to some embodiments, the vent holes323are aligned radially along centerlines. In some embodiments, the vent holes323have the same size diameters. According to some embodiments, the diameters of the vent holes323are between about 1 mm and about 20 mm. However, any suitable diameters may be utilized.

In other embodiments, the vent holes323may have diameters of different sizes. For example, as illustrated inFIG.3C, the diameters of vent holes323that are radially aligned may increase in size as they are located further distances from a center of the trench plate320. For example, the diameters of the vent holes323may increase between about 10 mm and about 50 mm, such as about 30 mm at each step away from the center. However, any suitable increase or decrease may be utilized.

FIG.3Cfurther illustrates that, according to some embodiments, through holes329are located along an outer edge of the trench plate320and extend through the trench plate320. The trench plate320may have any suitable number (e.g., twelve) of through holes329. In some embodiments, fasteners (e.g., screws, threaded bolts, and the like) are used to extend through the through holes329of the trench plate320to connect the retaining ring330to the cover plate340with the trench plate320secured there between. The through holes329may be any suitable type (e.g., threaded, non-threaded, lined, elongated slots, and the like), any suitable shape, and any suitable size of through holes.

FIG.3Cstill further illustrates the first, second, and third cut-lines A-A′, B-B′ and C-C′, respectively, which correlate to the cross-sectional views of the pre-bake station103inFIGS.3A,3D and3E, respectively. The first cutline A-A′ is taken through a centerline of an aligned series of the vent holes323in two of the ridges321extending radially in opposite directions from one another. The second cutline B-B′ is taken through a centerline of three trenches325of the trench plate320. One of the three trenches325is located in a center region of the trench plate320and separates the other two of the three trenches325, and the other two of the three trenches325extend radially in opposite directions from one another. The third cutline C-C′ is annularly shaped taken through a centerline of six of the vent holes323of six different ones of the ridges321separated by five different ones of the trenches325of the trench plate320, the six of the vent holes323being disposed a same radial distance from the center of the trench plate320.

According to some embodiments, the trenches325comprise a plurality of outer trenches extending from an outer portion of the trench plate320towards an inner portion of the trench plate320and radially surrounding a center trench disposed at a center of the trench plate320. According to some embodiments, the center trench may have a first width W1of between about 1 mm and about 60 mm, such as about 30 mm and the outer trenches may have a second width W2of between about 10 mm and about 60 mm, such as about 50 mm. However, any suitable widths may be utilized. According to some embodiments, the outer trenches325may be separated from the inner trench325by a distance DIS1of between about 1 mm and about 20 mm, such as about 5 mm. However, any suitable distances may be utilized.

FIG.3Dillustrates the cross-sectional view of the pre-bake station103through the second cutline B-B′ including three of the trenches325and four of the ridges321being integrally formed within the trench plate320. In the cross-sectional view ofFIG.3D, none of the vent holes323are shown, because the second cutline B-B′ does not intersect any of the vent holes323which correlates to the second cutline B-B′ illustrated inFIG.3C. However,FIG.3Ddoes illustrate the through holes329located in the outer ring of the trench plate320because the second cutline B-B′ intersects two of the through holes329which correlates to the second cutline B-B′ illustrated inFIG.3C.

FIG.3Eillustrates the cross-sectional view of the pre-bake station103through the annular shaped third cutline C-C′ taken through six of the vent holes323located in six different ones of the ridges321separated by five different ones of the trenches325of the trench plate320. In the cross-sectional view ofFIG.3E, the trench plate320appears to be separated from the cover plate340because the third cutline C-C′ is taken through the pre-bake station103at points located at the same radial distance from the center of the pre-bake station103. As such, the third cutline C-C′ does not intersect any points along the outermost one of the ridges321of the trench plate320at which the cover plate340meets the trench plate320which correlates to the third cutline C-C′ illustrated inFIG.3C. Furthermore, inFIG.3E, the cover plate340and the exhaust hood heater360do not appear to be angled at the first angle θ1as illustrated inFIG.3A, because the cross-section through the annular shape of the third cutline C-C′ intersects points along the cover plate340and intersects points along the exhaust hood heater360at same respective distances above the substrate201which correlates to the third cutline C-C′ illustrated inFIG.3C.

FIGS.3F-3Gillustrate a bottom view of the cover plate340of the pre-bake station103and a magnified bottom view of the exhaust pipe header350of the cover plate340, respectively. According to some embodiments, the cover plate340may have an outer dimension that is shaped and sized to match the outer dimension and shape of the trench plate320. As such, the cover plate340fits over the trench plate320with outer edges of the cover plate340being aligned with the outer edges of the trench plate320. In some embodiments, the cover plate340is annularly shaped with a third diameter DIA3of between about 180 mm and about 320 mm. According to some embodiments, a surface of the cover plate340facing the trench plate320, as illustrated inFIG.3A, may have a slight concave shape with an acute angle for the first angle θ1. However, any suitable shapes, diameters, and angles may be used for the cover plate340.

FIG.3Ffurther illustrates the cover plate340comprising the grooves343on the inner surface of the cover plate340facing the trench plate320. In some embodiments, the grooves343form a radial pattern extending outward from an opening317through the cover plate340and the radial pattern of the grooves343is aligned with the radial pattern of the vent holes323of the trench plate320. In such embodiments, each of the grooves343is aligned with respective ones of the vent holes323of the trench plate320. In some embodiments, the grooves343may help guide evaporated vapors flowing from the vent holes323of the trench plate320to the opening317during baking processes (e.g., the pre-bake process300). According to some embodiments, the opening317of the cover plate340has the first diameter DIA1, as illustrated in the magnified bottom view ofFIG.3G. However, any suitable dimensions of the opening317through the cover plate340may be used.

FIG.3Hillustrates an exploded view of the components of the exhaust hood assembly380of the pre-bake station103, according to some embodiments. The exhaust hood assembly380comprises fasteners331(e.g., threaded bolts), the retaining ring330, the trench plate320over the retaining ring330, the cover plate340over the trench plate320, the exhaust hood heater360over the cover plate340, and the exhaust pipe header350over the exhaust hood heater360. In particular,FIG.3Hillustrates that the components of the exhaust hood assembly380are aligned such that through holes329of the components receive the fasteners331(e.g., threaded bolts) securing the components of the exhaust hood assembly380to one another.FIG.3Hfurther illustrates that the radial pattern of the grooves343in the cover plate340are aligned with the radial pattern of the vent holes323of the trench plate320.

In some embodiments, the exhaust hood heater360comprises a stack of heating elements having an annular shape and a diameter substantially the same as the cover plate340, the exhaust hood heater360conforming to an upper surface of the cover plate340. The exhaust hood heater360comprises an opening317extending through the stack of heating elements at a center of the exhaust hood heater360. In some embodiments, a vertical portion of the exhaust pipe header350extends through the opening317of the exhaust hood heater360and attaches to the opening317of the cover plate340.

FIG.4illustrates an embodiment of an imaging device400of the exposure station105into which the substrate201and the photoresist211may be transferred (e.g., by a transfer station104) after the curing and drying of the photoresist211in the pre-bake station103. The exposure station105will expose the photoresist211to form one or more exposed regions401and one or more unexposed regions403within the photoresist211. In an embodiment the exposure may be initiated by placing the semiconductor device200and the photoresist211, once cured and dried, into the imaging device400for exposure. The imaging device400may comprise a support plate405, an energy source407, a patterned mask409arranged between the support plate405and the energy source407, and optics413. In an embodiment the support plate405is a surface to which the semiconductor device200and the photoresist211may be placed or attached to and which provides support and control to the substrate201during exposure of the photoresist211. Additionally, the support plate405may be movable along one or more axes, as well as providing any desired heating or cooling to the substrate201and photoresist211in order to prevent temperature gradients from affecting the exposure process.

In an embodiment the energy source407supplies energy411such as light to the photoresist211in order to induce a reaction of the PACs, which in turn reacts with the polymer resin to chemically alter those portions of the photoresist211to which the energy411impinges. In an embodiment the energy411may be electromagnetic radiation, such as g-rays (with a wavelength of about 436 nm), i-rays (with a wavelength of about 365 nm), ultraviolet radiation, far ultraviolet radiation, x-rays, electron beams, or the like. The energy source407may be a source of the electromagnetic radiation, and may be a KrF excimer laser light (with a wavelength of 248 nm), an ArF excimer laser light (with a wavelength of 193 nm), a F2 excimer laser light (with a wavelength of 157 nm), or the like, although any other suitable source of energy411, such as mercury vapor lamps, xenon lamps, carbon arc lamps or the like, may also be utilized.

The patterned mask409is located between the energy source407and the photoresist211in order to block portions of the energy411to form a patterned energy415prior to the energy411actually impinging upon the photoresist211. In an embodiment the patterned mask409may comprise a series of layers (e.g., substrate, absorbance layers, anti-reflective coating layers, shielding layers, etc.) to reflect, absorb, or otherwise block portions of the energy411from reaching those portions of the photoresist211which are not desired to be illuminated. The desired pattern may be formed in the patterned mask409by forming openings through the patterned mask409in the desired shape of illumination.

Optics413may be used to concentrate, expand, reflect, or otherwise control the energy411as it leaves the energy source407, is patterned by the patterned mask409, and is directed towards the photoresist211. In an embodiment the optics413comprise one or more lenses, mirrors, filters, combinations of these, or the like to control the energy411along its path. Additionally, while the optics413are illustrated inFIG.4as being between the patterned mask409and the photoresist211, elements of the optics413(e.g., individual lenses, mirrors, etc.) may also be located at any location between the energy source407(where the energy411is generated) and the photoresist211.

In an embodiment the semiconductor device200with the photoresist211is placed on the support plate405. Once the pattern has been aligned to the semiconductor device200, the energy source407generates the desired energy411(e.g., light) which passes through the patterned mask409and the optics413on its way to the photoresist211. The patterned energy415impinging upon portions of the photoresist211induces a reaction of the PACs within the photoresist211. The chemical reaction products of the PACs' absorption of the patterned energy415(e.g., acids/bases/free radicals) then reacts with the polymer resin, chemically altering the photoresist211in those portions that were illuminated through the patterned mask409.

In a specific example in which the patterned energy415is a 193 nm wavelength of light, the PAC is a photoacid generator, and the polymer resin comprises a group to be decomposed which is a carboxylic acid group on the hydrocarbon structure and a cross linking agent is used, the patterned energy415will impinge upon the photoacid generator and the photoacid generator will absorb the impinging patterned energy415. This absorption initiates the photoacid generator to generate a proton (e.g., an H+ atom) within the photoresist211. When the proton impacts the carboxylic acid group on the hydrocarbon structure, the proton will react with the carboxylic acid group, chemically altering the carboxylic acid group and altering the properties of the polymer resin in general. The carboxylic acid group will then react with the cross-linking agent to cross-link with other polymer resins within the photoresist211.

Optionally, the exposure of the photoresist211may occur using an immersion lithography technique. In such a technique an immersion medium (not individually illustrated inFIG.4) may be placed between the imaging device400(and particularly between a final lens of the optics413) and the photoresist211. With this immersion medium in place, the photoresist211may be patterned with the patterned energy415passing through the immersion medium.

In this embodiment, a protective layer (also not individually illustrated inFIG.4) may be formed over the photoresist211in order to prevent the immersion medium from coming into direct contact with the photoresist211and leaching or otherwise adversely affecting the photoresist211. In an embodiment the protective layer is insoluble within the immersion medium such that the immersion medium will not dissolve it and is immiscible in the photoresist211such that the protective layer will not adversely affect the photoresist211. Additionally, the protective layer is transparent so that the patterned energy415may pass through the protective layer without hindrance.

In an embodiment the protective layer comprises a protective layer resin within a protective layer solvent which should be removed. The material used for the protective layer solvent is, at least in part, dependent upon the components chosen for the photoresist211, as the protective layer solvent should not dissolve the materials of the photoresist211so as to avoid degradation of the photoresist211during application and use of the protective layer. In an embodiment the protective layer solvent includes alcohol solvents, fluorinated solvents, and hydrocarbon solvents.

The protective layer resin may, similar to the photoresist211, comprise a polymer with a protective layer repeating unit. In an embodiment the protective layer repeating unit may be an acrylic resin with a repeating hydrocarbon structure having a carboxyl group, an alicyclic structure, an alkyl group having one to five carbon atoms, a phenol group, or a fluorine atom-containing group. However, any suitable protective layer resin may also be utilized.

Prior to application of the protective layer onto the photoresist211, the protective layer resin and any other desired additives are first added to the protective layer solvent to form a protective layer composition. The protective layer solvent is then mixed to ensure that the protective layer composition has a consistent concentration throughout the protective layer composition.

Once the protective layer composition is ready for application, the substrate201with the photoresist211may be returned to the coating station101or may be transferred to another suitable station by the transfer station104for application of the protective layer composition over the photoresist211. In an embodiment the application of the protective layer composition may be performed using a process such as a spin-on coating process, a dip coating method, an air-knife coating method, a curtain coating method, a wire-bar coating method, a gravure coating method, a lamination method, an extrusion coating method, combinations of these, or the like. In an embodiment the protective layer composition may be applied such that it has a thickness over the surface of the photoresist211of about 100 nm.

After the protective layer composition has been applied to the photoresist211, a protective layer pre-bake may be performed in order to remove the protective layer solvent. As such, the transfer station104may return the semiconductor device200with the protective layer over the photoresist211to the pre-bake station103to perform the protective layer pre-bake before further processing. In an embodiment, the protective layer pre-bake may be performed at a temperature suitable to evaporate the protective layer solvent, such as between about 40° C. and 150° C., although the precise temperature depends upon the materials chosen for the protective layer composition. The protective layer pre-bake is performed for a time sufficient to cure and dry the protective layer composition, such as between about 10 seconds to about 5 minutes, such as about 90 seconds.

Once the protective layer pre-bake has been performed, the semiconductor device200with the photoresist211and the protective layer are transferred from the pre-bake station103and placed on the support plate405of the exposure station105, and the immersion medium may be placed between the protective layer and the optics413. In an embodiment the immersion medium is a liquid having a refractive index greater than that of the surrounding atmosphere, such as having a refractive index greater than 1. Examples of the immersion medium may include water, oil, glycerine, glycerol, cycloalkanols, or the like, although any suitable medium may also be utilized.

The placement of the immersion medium between the protective layer and the optics413may be done using, e.g., an air knife configuration of the exposure station105, whereby fresh immersion medium is applied to a region between the protective layer and the optics413and controlled using pressurized gas directed towards the protective layer to form a barrier and keep the immersion medium from spreading. In this embodiment the immersion medium may be applied, used, and removed from the protective layer for recycling so that there is fresh immersion medium used for the actual imaging process.

However, the air knife configuration for the exposure station105described above is not the only configuration which may be used to expose the photoresist211using an immersion method. Any other suitable configuration using an immersion medium, such as immersing the entirety of the substrate201along with the photoresist211and the protective layer or using solid barriers instead of gaseous barriers may also be utilized. Any suitable method for exposing the photoresist211through the immersion medium may be used, and all are fully intended to be included within the scope of the embodiments.

FIG.5illustrates a post-bake process of the semiconductor device, after the photoresist211has been exposed to the patterned energy415in the exposure station105. The semiconductor device200with the photoresist211may be moved via the transfer station104from the exposure station105to the post-bake station107. In some embodiments, the post-bake station107may be separate from but similar to the pre-bake station103illustrated inFIG.3A. In other embodiments, the transfer station104may transfer the semiconductor device200with the photoresist211from the exposure station105to the pre-bake station103to perform the post-bake process. However, any suitable type of heating station such as a furnace or steam-heating station may also be utilized.

Once in the post-bake station107, a first post-exposure bake (PEB) (e.g., PEB501represented inFIG.5by the wavy lines) may be used in order to assist in the generating, dispersing, and reacting of the acid/base/free radical generated from the impingement of the energy411upon the PACs during the exposure in the exposure station105. Such assistance helps to create or enhance chemical reactions which generate chemical differences and different polarities between the one or more exposed regions401and the one or more unexposed regions403within the photoresist211. These chemical differences also cause differences in the solubility between the one or more exposed regions401and the one or more unexposed regions403. In an embodiment the semiconductor device200with the photoresist211may be placed on the hot plate301and the temperature of the photoresist211may be increased to between about 50° C. and about 160° C. for a period of between about 40 seconds and about 120 seconds.

Returning now toFIG.1, the photoresist track system100comprises a developer station109which can be used, if desired, to develop the photoresist211with a positive tone developer or a negative tone developer and which comprises equipment and chemicals which are specific to the development process. In an embodiment the developer station109may be connected to the post-bake station107through, e.g., the transfer station104so that the semiconductor device200and photoresist211may be transferred to the developer station109shortly after the PEB501without breaking the interior environment of the photoresist track system100.

FIGS.6A-6Billustrate a top view and a representative cross-sectional view of an embodiment of the developer station109in which the developer station109uses a spin-on method to apply the developer. In an embodiment the developer station109comprises a rotating developer chuck603attached to a rotating spindle605. A developer dispensing arm607with a developer nozzle608(on a developer track606) is operably connected to a developer storage tank609so that the developer storage tank609provides a fresh supply of the developer611to the developer dispensing arm607.

In an embodiment the substrate201is placed onto the rotating developer chuck603and is held in place using, e.g., a vacuum pressure suctioning the substrate201to the rotating developer chuck603. The rotating spindle605is attached to the rotating developer chuck603and is engaged, thereby rotating the rotating developer chuck603, the substrate201with the photoresist211, at a speed of between about 500 rpm and about 3500 rpm. Once the photoresist211is rotating at the desired speed, the developer dispensing arm607moves over the rotating photoresist211and begins to dispense the developer611out of the developer nozzle608and onto the photoresist211at a rate of between about 0.5 cc/sec and about 20 cc/sec, at a temperature of between about 10° C. and about 50° C., such as about 50° C., for a period of time between about 10 second and about 60 minutes, such as about 30 minutes.

In an embodiment the developer dispensing arm607dispenses a developer611(e.g., a negative tone developer), such as an organic solvent or critical fluid to remove those portions of the photoresist211which were not exposed to the energy411during the exposure process and, as such, retain their original solubility. Specific examples of materials that may be utilized include hydrocarbon solvents, alcohol solvents, ether solvents, ester solvents, critical fluids, combinations of these, or the like.

In an embodiment in which immersion lithography is utilized to expose the photoresist211and the protective layer utilized to protect the photoresist211from the immersion medium, the developer611may be chosen to remove not only those portions of the photoresist211that are desired to be removed, but may also be chosen to remove the protective layer in the same development step. Also, the protective layer may be removed in a separate process, such as by a separate solvent from the developer611or even an etching process to remove the protective layer from the photoresist211prior to development.

However, while the spin-on method and configuration described herein for the developer station109is one suitable method for developing the photoresist211in the developer station109, it is intended to be illustrative and is not intended to limit the embodiment. Rather, the developer station109may comprise any mechanism and chemicals in any configuration for any type of development process, include a dip process configuration, a puddle process configuration, combinations of these, or the like. All such development processes and configuration for the developer station109are fully intended to be included within the scope of the embodiments.

Furthermore, in an embodiment all of the mechanics and other structures that make up the developer station109(e.g., the rotating developer chuck603, the rotating spindle605, the developer dispensing arm607, etc.) are housed within an exterior housing601, which provides support and protection to the internal components of the developer station109. In an embodiment the exterior housing601encloses the developer station109and is accessible through the transfer station104of the photoresist track system100. Additionally, any utilities, such as electricity or fresh raw materials (e.g., fresh developer or fresh rinse water), may come in, if desired, through the exterior housing601.

FIG.6Cillustrates a cross-sectional view of the application of the developer611onto the photoresist211. In an embodiment the developer611will dissolve the unexposed regions403of the photoresist211that were not exposed to the patterned energy415. This dissolving will leave behind the one or more exposed regions401of the photoresist211that had been exposed to the patterned energy415, thereby transferring the pattern of the patterned energy415to the photoresist211. Once finished, the developer611may be removed by stopping the dispensing of the developer611while keeping the substrate201spinning to remove the developer611and performing an optional rinse with, e.g., deionized water.

Returning now toFIG.1, after the photoresist211has been developed in the developer station109, the substrate201and the photoresist211may be transferred by the transfer station104into the optional hard bake station111for further processing. Once the substrate201and the photoresist211are in position, the optional hard bake station111may optionally be used to perform a hard-bake process to help polymerize and stabilize the photoresist211after the development process, and also aids in improving the adhesion of the photoresist211to the layer to be patterned209. In some embodiments the optional hard bake station111may be separate from but similar to the pre-bake station103including the hot plate301(see, e.g.,FIG.3A) and exhaust hood assembly380. In other embodiments, the transfer station104may transfer the substrate201from the developer station109to the pre-bake station103to perform the hard-bake process. However, any suitable type of heating station such as a furnace or steam-heating station may also be utilized.

Turning toFIG.7, once the substrate with the photoresist211is in the optional hard bake station111, a hard bake process701(represented inFIG.7by the wavy lines) may be performed on the substrate201with the photoresist211. During the hard bake process701, the hot plate301and the heating elements305are engaged to raise the temperature of the photoresist211to a process temperature of between about 70° C. to about 130° C. The photoresist may be kept at this process temperature for a time period of between about 1 minute and about 3 minutes.

Once the hard bake has been performed on the photoresist211, and any other processes such as rinsing or drying that may be desired, the substrate201with the photoresist211is ready for further processing and may be removed from the photoresist track system100through the second loadlock chamber114. Similar to the first loadlock chamber102, the second loadlock chamber114allows the substrate201to be removed from the photoresist track system100without exposing the interior stations to the exterior atmosphere.

FIGS.8A-8Cillustrate cross-sectional views of several different profiles of the trench plate320, according to some other embodiments. Although specific shapes and dimensions are illustrated inFIGS.8A-8Cfor the different profiles of the trench plate320, these shapes and dimensions are intended to be illustrative and are not intended to limit the embodiments.

FIG.8Aillustrates the trench plate320comprising a second profile825A having trenches325with substantially (within the range of manufacturing deviation) flat bottoms and substantially (within the range of manufacturing deviation) vertical sidewalls. According to some embodiments, the second profile825A comprises trenches325having a third width W3of between about 1 mm and about 60 mm, such as about 30 mm and a second depth D2 of between about 1 mm and about 20 mm, such as about 5 mm. However, any suitable widths and any suitable depths may be used for the trenches325of the second profile825A.

FIG.8Billustrates the trench plate320comprising a third profile825B having trenches325with rounded bottoms and rounded sidewalls. According to some embodiments, the third profile825B comprises trenches325having a fourth width W4of between about 1 mm and about 60 mm, such as about 30 mm, a third depth D3of between about 1 mm and about 20 mm, such as about 5 mm, and having a first radius R1of the rounded bottoms and rounded sidewalls of between about 1 mm and about 20 mm, such as about 5 mm. However, any suitable widths, any suitable depths, and any suitable radiuses may be used for the trenches325of the third profile825B.

FIG.8Cillustrates the trench plate320comprising a fourth profile825C having trenches325with pointed bottoms and angled sidewalls. According to some embodiments, the fourth profile825C comprises trenches325having a fifth width W5of between about 1 mm and about 60 mm, such as about 30 mm, a fourth depth D4of between about 1 mm and about 20 mm, such as about 5 mm, and angled sidewalls having third angles θ3of between about 120° and about 170°, such as about 135°. However, any suitable widths, any suitable depths and any suitable angles may be used for the trenches325of the fourth profile825C.

FIGS.9A-9Billustrate top views of several different configurations of the trench plate320, according to some embodiments different from the embodiment illustrated inFIG.3C. Although specific shapes and dimensions are illustrated inFIGS.9A-9Bfor the different configurations of the trench plate320, these shapes and dimensions are intended to be illustrative and are not intended to limit the embodiments.

FIG.9Aillustrates the trench plate320, according to another embodiment, comprising a series of raised concentric circles940instead of the ridges321ofFIG.3Cand trenches325arranged alternately between the series of raised concentric circles940. The series of raised concentric circles940comprise vent holes323arranged in a radial pattern across the series of raised concentric circles940and comprise through holes329arranged within an outermost ridge of the series of raised concentric circles940. However, any suitable number of concentric circles and any suitable arrangement of vent holes323within the series of raised concentric circles940may be used.

FIG.9Billustrates the trench plate320, according to yet another embodiment, comprising a plurality of columns950instead of the ridges321ofFIG.3C. The plurality of columns950are disposed in a radial pattern with areas between columns forming a plurality of the trenches325that are integrally connected. The plurality of columns950comprise vent holes323arranged within the corresponding ones of the radial pattern of columns950and comprise through holes329arranged within an outermost circular ridge along a perimeter of the trench plate320. However, any suitable number and any suitable shape of the plurality of columns950and any suitable arrangement of vent holes323within the ridges321may also be used.

While the different profiles and configurations of the trench plate320are illustrated inFIGS.8A-8D and9A-9Bwith specific shapes and specific dimensions suitable for the trench plate320, these are intended to be illustrative and are not intended to limit the embodiments. Rather, the profiles and configurations of the trenches325of the trench plate320may comprise any suitable shapes, any suitable sizes, any suitable dimensions, and in any suitable configuration for collecting the residue390within the trenches325and preventing the residue from dripping onto the semiconductor device200during bake processes. All such profiles and configurations for the trenches325of the trench plate320are fully intended to be included within the scope of the embodiments.

By providing nonstick coatings on inner surfaces of the cover plate340and the exhaust pipe header350of the exhaust hood assembly380, the solvent vapor condensing into the residue390is prevented or minimized from wetting the inner surfaces of the cover plate340and the exhaust pipe header350which aids in the evacuation of the chemical solvent vapor from the exhaust hood assembly380during baking processes. Furthermore, by collecting and trapping any residue390within trenches325of the trench plate320, it is possible to prevent the residue390from dropping onto the substrate201and causing defects on the substrate201.

As such, the exhaust hood assembly380efficiently evacuates solvent vapor during bake processes (e.g., the pre-bake process300), minimizes the chemical solvent vapor from condensing into a residue and wetting inner surfaces of the exhaust hood assembly, and prevents any residue that has formed from dripping onto and causing damage to a wafer. As such, high exhaust efficiency, improved reliability, increased yield, and ultimately reduced manufacturing time and costs are achieved by the apparatus and bake process methods, as described herein.

In accordance with an embodiment, a semiconductor manufacturing apparatus includes: a trench plate comprising a first surface and a second surface opposite the first surface, wherein the trench plate comprises a first trench extending partially through the trench plate from the first surface, wherein the trench plate also comprises a first opening extending fully through the trench plate from the first surface to the second surface, and a second opening extending fully through the trench plate from the first surface to the second surface, the first trench being located between the first opening and the second opening. In accordance with an embodiment the first surface comprises polytetrafluoroethylene. In accordance with an embodiment the first trench is located within a center of the trench plate. In accordance with an embodiment the trench plate further comprises a second trench separated from the first trench by a first distance between about 1 mm and about 20 mm. In accordance with an embodiment the first trench has a width which increases in size as the first trench extends towards an outer perimeter of the trench plate. In accordance with an embodiment the first trench comprises angled sidewalls. In accordance with an embodiment the semiconductor manufacturing apparatus further includes attachment holes located along a perimeter of the trench plate.

In accordance with another embodiment, a semiconductor manufacturing apparatus includes: a trench plate, wherein the trench plate comprises ridges, a trench disposed between the ridges, and a vent hole extending through the ridges and from a first side of the trench plate to a second side of the trench plate; and a cover plate over and attached to the trench plate. In accordance with an embodiment, the semiconductor manufacturing apparatus further includes a single pipe header attached to the cover plate, wherein the single pipe header is the lone pipe header attached to the cover plate. In an embodiment the single pipe header has a diameter of between about 20 mm and about 40 mm. In an embodiment, surfaces of the trench plate and the cover plate comprise a polytetrafluoroethylene coating. In an embodiment the trench comprises angled sidewalls and a substantially flat bottom surface. In an embodiment the trench comprises a substantially flat bottom surface and sidewalls extending in a direction substantially vertical to the substantially flat bottom surface. In an embodiment the trench has a concave profile.

In accordance with yet another embodiment, a method includes: placing a semiconductor wafer with a material disposed thereon within a bake station; and heating the semiconductor wafer with the material disposed thereon, thereby forming an evaporated portion of the material, wherein a first portion of the evaporated portion passes through vent holes of a trench plate and through a cover plate above the trench plate, and wherein a second portion of the evaporated portion passes through the vent holes of the trench plate, condenses, and enters trenches within the trench plate after condensing. In an embodiment the trench plate comprises polytetrafluoroethylene. In an embodiment all of the evaporated portion that does not condense passes through a single opening in the cover plate. In an embodiment the single opening has a diameter of between about 20 mm and about 30 mm. In an embodiment the material is a photoresist. In an embodiment the cover plate has a second trench and the first portion of the evaporated portion enters the second trench.

The foregoing outlines features of several embodiments so that those skilled in the art may better understand the aspects of the present disclosure. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions, and alterations herein without departing from the spirit and scope of the present disclosure.