HIGH FLOW LIQUID PRECURSOR HEAT EXCHANGER

Description

TECHNICAL FIELD

The subject matter disclosed herein relates generally, but not by way of limitation, to heat exchangers used in the production of vapors used, for example, a deposition of thin films in the semiconductor and allied industries.

BACKGROUND

Processes for creating a vapor from a liquid can be accomplished by, for example, heating the liquid to a sufficiently high temperature to cause the liquid to undergo a phase change and become a vapor. To generate vapor at a sufficiently high rate as used in various industries, it is beneficial to supply a sufficient heating energy to the liquid. In many cases, the vapor is preferably created in a relatively short amount of time. The short time-frame may be accomplished by increasing the operating temperature of the vapor generating apparatus or providing a larger heat transfer surface so that heat can be applied more readily and uniformly into the liquid.

For example, in semiconductor fabrication environments, a wide variety of precursor chemicals are available in liquid form. The liquid forms of these chemicals are often converted into vapor forms used for thin film depositions on a substrate by a vapor-phase process. The vapor-phase processes can include, for example, atomic-level deposition (ALD) processes, chemical-vapor deposition (CVD) processes, plasma-enhanced chemical-vapor deposition (PECVDP) processes, metal-organic CVD (MOCVD) processes, and other processes known to a person of ordinary skill in the art.

Some precursor chemicals, such as metal-organic compounds used in MOCVD processes, can decompose at high temperatures, thereby forming undesirable by-products, which can cause process or equipment contamination. For such applications, liquid-heating temperatures should be kept low to avoid thermal decomposition and by-product formation. However, increasing an area of heat transfer surfaces generally causes an overall physical size of the heat-exchanger apparatus to increase, thus making the device less responsive to changing vapor demands in the process. The response speed of the apparatus will thus decrease. As a result, a traditional approach to increasing vaporization rates is not suitable for all applications.

The information described in this section is provided to offer a person of ordinary skill in the art a context for the following disclosed subject-matter and should not be considered as admitted prior art.

SUMMARY

In one exemplary embodiment, the disclosed subject-matter describes a heat-exchanger device that includes a thermal mass and a first number of flow channels formed within the thermal mass in a serpentine arrangement. The first number of flow channels have straight portions with bends between the straight portions fluidically coupling adjacent ones of the straight portions. Adjacent ones of the straight portions are substantially parallel to one another and provide fluidic flow paths in substantially opposite directions in the adjacent ones of the straight portions. A carrier-gas inlet port is coupled to an inlet of the first number of flow channels to receive a carrier gas having liquid droplets contained therein. At least one heater is embedded into the thermal mass in thermal contact with the first number of flow channels. The at least one heater is to heat the carrier gas and vaporize the liquid droplets to form a vapor. A fluid-outlet port, through which the vapor may exit the heat-exchanger device, is coupled to an outlet of the first number of flow channels where the outlet of the first number of flow channels is on an end of the first number of flow channels opposite to the inlet of the first number of flow channels.

In another exemplary embodiment, the disclosed subject-matter describes a heat-exchanger device that includes a thermal mass, a first number of flow channels formed on a first side of the thermal mass in a serpentine arrangement, and a second number of flow channels formed on a second side of the thermal mass in a serpentine arrangement. Each of the first number of flow channels and the second number of flow channels have straight portions with bends between the straight portions fluidically coupling adjacent ones of the straight portions. Adjacent ones of the straight portions are substantially parallel to one another and configured to provide fluidic flow paths in substantially opposite directions in the adjacent ones of the straight portions. A flow-path opening fluidically couples the first number of flow channels with the second number of flow channels. A carrier-gas inlet port, coupled to an inlet end of the first number of flow channels is configured to receive a carrier gas having liquid droplets contained therein. At least one heater is embedded into the thermal mass in thermal contact with the first number of flow channels and the second number of flow channels. The at least one heater is configured to heat the carrier gas and vaporize the liquid droplets to form a vapor. A fluid-outlet port, through which the vapor may exit the heat-exchanger device, is coupled to an outlet end of the second number of flow channels, where the outlet of the second number of flow channels is on an end opposite to the inlet of the first number of flow channels.

In another exemplary embodiment, the disclosed subject-matter describes a heat-exchanger device including a thermal mass and a first number of flow channels formed within the thermal mass in a serpentine arrangement. The first number of flow channels having straight portions with bends between the straight portions fluidically coupling adjacent ones of the straight portions. Adjacent ones of the straight portions are substantially parallel to one another and configured to provide fluidic flow paths in substantially opposite directions in the adjacent ones of the straight portions. A carrier-gas inlet port, coupled to an inlet of the first number of flow channels, is configured to receive a carrier gas having liquid droplets contained therein. A chase-gas inlet port is configured to allow a chase gas into the first number of flow channels to mix with the carrier gas and the liquid droplets. At least one heater is embedded into the thermal mass in thermal contact with the first number of flow channels. The at least one heater is configured to heat the carrier gas and vaporize the liquid droplets to form a vapor. A fluid-outlet port is coupled to an outlet of the first number of flow channels through which the vapor may exit the heat-exchanger device. The outlet of the first number of flow channels being on an end of the first number of flow channels opposite to the inlet of the first number of flow channels.

BRIEF DESCRIPTION OF FIGURES

Various ones of the appended drawings merely illustrate examples of various implementations of the disclosed subject-matter and should not be considered as limiting its scope.

FIG. 1A shows an isometric-view of an exemplary embodiment of a high-flow heat exchanger that may be used with a chase or purge gas, in accordance with various embodiments of the disclosed subject-matter;

FIG. 1B shows an example of a front-view of the high-flow heat exchanger of FIG. 1A, in accordance with various embodiments of the disclosed subject-matter;

FIG. 1C shows an example of a top view of the high-flow heat exchanger of FIG. 1A, in accordance with various embodiments of the disclosed subject-matter;

FIG. 1D shows an example of a cross-sectional-view of the high-flow heat exchanger of FIG. 1B having rectangular flow channels, in accordance with various embodiments of the disclosed subject-matter;

FIG. 1E shows another example of a cross-sectional-view of the high-flow heat exchanger of FIG. 1B having rounded or semi-circular flow channels, in accordance with various embodiments of the disclosed subject-matter;

FIG. 2A shows an exemplary embodiment of an end-view of the high-flow heat exchanger of FIG. 1A, and how a fluidic barrier may be formed over the flow channels of, for example, FIG. 1D;

FIG. 2B shows another exemplary embodiment of a top cross-sectional view of a portion of the high-flow heat exchanger of FIG. 1A and another type of fluidic barrier that may be formed over the flow channels of, for example, FIG. 1E;

FIG. 3A shows an isometric-view of an exemplary embodiment of a high-flow heat exchanger, in accordance with various embodiments of the disclosed subject-matter;

FIG. 3B shows an example of a bottom view of the high-flow heat exchanger of FIG. 3A, in accordance with various embodiments of the disclosed subject-matter; and

FIG. 3C shows an example of a front-view of the high-flow heat exchanger of FIG. 3A, in accordance with various embodiments of the disclosed subject-matter.

DETAILED DESCRIPTION

The following description includes a discussion of figures having illustrations given by way of examples of implementations of the disclosed subject-matter. The drawings should be understood by way of example, and not by way of limitation. As used herein, references to one or more “embodiments” are understood to be describing a particular feature, structure, or characteristic included in at least one implementation of the disclosed subject-matter. Thus, phrases such as “in one embodiment,” “in an exemplary embodiment,” or “in an alternative embodiment” appearing herein describe various embodiments and implementations of the disclosed subject-matter, and do not necessarily all refer to the same embodiment. However, the embodiments are also not necessarily mutually exclusive from one another. To identify easily the discussion of any particular element or act, the most significant digit or digits in a reference number (e.g., element number) refer to the figure (“FIG.”) number in which that element or act is first introduced.

In various embodiments described herein, the disclosed subject-matter describes a system to provide an efficient and timely heat transfer to liquids to produce vapors, in a relatively compact volume. Further, although the disclosed subject-matter refers to a high-flow, liquid-precursor heat exchanger, embodiments of the heat exchanger disclosed herein can be used in a variety of environments outside of the semiconductor industry and related fields.

In various embodiments described herein, the disclosed subject-matter describes an apparatus for vapor generation from various fluids (e.g., precursor chemicals, which are often supplied in liquid form) that allows for a compact-vaporizer, heat-exchanger design, while reducing a maximum temperature to which the liquid and vapor are exposed. A mixture of gas and/or liquid droplets flow through the described heat exchanger for vaporization. The heat exchanger includes multiple surfaces to transfer heat to the gas and/or liquid. The increased surface area in the heat exchanger includes an arrangement of serpentine-flow channels (serpentine-flow paths) to further increase heat transfer and vaporization. The serpentine-flow channels are based on, for example, various shapes of channels and/or tubular passageways. In various ones of the embodiments described herein, dead volumes within the heat exchanger have been reduced, minimized, or eliminated.

Each of these non-limiting embodiments described herein can stand on its own, or can be combined in various permutations or combinations with one or more of the other embodiments.

The disclosed subject-matter will now be described in detail with reference to a few general and specific embodiments as illustrated in various ones of the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the disclosed subject-matter. It will be apparent, however, to a person of ordinary skill in the art upon reading and understanding the disclosed subject-matter, that the disclosed subject-matter may be practiced without some or all of these specific details. In other instances, well-known process steps, construction techniques, or structures have not been described in detail so as not to obscure the disclosed subject-matter.

With reference now to FIG. 1A, an isometric-view of an exemplary embodiment of a high-flow heat exchanger 100 that may be used with a chase or purge gas (described below with reference to FIG. 1C), in accordance with various embodiments of the disclosed subject-matter, is shown. FIG. 1A is shown to include a thermal mass 115 in which a number of flow channels 105 have been formed in a substantially serpentine pattern. The high-flow heat exchanger 100 is also shown to include a carrier-gas inlet 103 and a chase-gas inlet 101.

The carrier-gas inlet 103 can be used to accept a combination of a carrier gas and liquid droplets (e.g., suspended-liquid droplets) formed by an atomizer, which is fluidically coupled to the high-flow heat exchanger 100. The liquid droplets are formed from various types of fluids, such as liquid precursors. The carrier gas provides a fluid to carry the droplets from the atomizer into the high-flow heat exchanger 100. The chase-gas inlet 101 can provide higher flowrates as may be used by fabrication tools coupled to an outlet of the high-flow heat exchanger 100. For example, the combination of the atomized droplets within the carrier gas may provide a flowrate of 8.5 liters per minute (lpm). However, if the fabrication tool uses an inlet flowrate of 12.5 lpm, the chase gas can be input to provide an additional flowrate of 4 lpm. The chase gas may comprise nitrogen, argon, or another inert gas. When a chase gas is used within the high-flow heat exchanger 100, a dead volume within the high-flow heat exchanger 100 may be reduced, minimized, or eliminated. Consequently, there are few, if any, dead volumes in which fluids may collect.

In addition to, or instead of a chase gas, in some embodiments, the chase-gas inlet 101 can also provide an inlet for a purge gas to, for example, clear the high-flow heat exchanger 100 of prior gases before changing to another gas in a subsequent process or to be used for cleaning the high-flow heat exchanger 100. The purge gas may comprise nitrogen, argon, or another inert gas. In other embodiments, no chase gas or purge gas may be used at all for certain applications.

A first region 107 provides volumes within the high-flow heat exchanger 100 in which a chase-gas may be introduced. A second region 109 provides volumes within the high-flow heat exchanger 100 in which a carrier-gas may be introduced. A third region 111 provides volumes within the high-flow heat exchanger 100 in which the chase-gas and the carrier-gas are combined and heated. Each of the first region 107, the second region 109, and the third region 111 are described in more detail below with reference to FIG. 1C, below. An end region 113 is described in more detail with reference to FIG. 2A.

The thermal mass 115 may comprise any of a variety of thermally-conductive materials, the selection of which is at least partially dependent upon a nature of the fluid that will be flowing therethrough. For example, various grades of stainless steel may be selected based on factors such as a resistance of the metal to corrosion and an ability to provide a contaminant-free surface as may be beneficial for a given application. For certain applications, 304-grade stainless steel may be selected for lower-cost applications. Where corrosion resistance is of a higher importance than material cost, 316 stainless steel may be selected over 304-grade stainless steel due to its superior corrosion resistance.

However, although stainless steel is thermally conductive, stainless steel is a relatively poor thermal conductor. Table I shows the thermal conductivity of stainless steel compared with other metals that may be selected. The flow of heat from a heater element (described below with reference to FIG. 1B) to the serpentine-flow channel will be lower when less thermally-conductive materials are used, resulting in an increased response time of the vaporization apparatus.

Further, factors other than thermal conductivity, such as machinability of the material, may influence a choice in the selection of materials from which to fabricate the heat exchanger.

The flow channels 105 may be formed into the thermal mass 115 by a variety of formation techniques, such as milling. For example, a square endmill or a ball endmill may be used to machine the flow channels 105 into the thermal mass 115. Such forming techniques are described in more detail below with reference to FIG. 1D and FIG. 1E.

Straight portions of the flow channels 105 (those portions located before and after the bends within the flow channels 105) may be formed as parallel paths or near-parallel paths. Such paths are described herein as being substantially parallel flow-paths. Adjacent ones of the substantially parallel flow-paths transport the fluid carried therein in substantially opposite directions. Further, a level of heat transfer from heaters embedded within the thermal mass 115, described in more detail with reference to FIG. 1B, below) by forming the flow channels 105 to have non-uniform surfaces formed on walls and/or bottom surfaces of the channels. For example, a width and/or depth of the flow channels 105 may deliberately be varied slightly so as to create non-uniform surfaces. Instead of, or in addition to, varying the surfaces, a texture may be created on the surfaces of the channels. Such variations and/or textures will generally increase a near-surface turbulence of a fluid flowing therethrough. The increased turbulence will reduce or eliminate any boundary-layer issues, thereby allowing more of the fluid to have a higher heat-transfer level with the thermal mass 115.

To further increase a heat-transfer level between the fluid and the thermal mass 115, a person of ordinary skill in the art, upon reading and understanding the disclosed subject-matter, will recognize how to determine a width and depth of the flow channels 105 in relationship with a flowrate for a selected fluid to provide for a desired laminar-flow or turbulent-flow level within the flow channels 105.

FIG. 1B shows an example of a front-view 130 of the high-flow heat exchanger 100 of FIG. 1A, in accordance with various embodiments of the disclosed subject-matter. The front-view 130 of FIG. 1B is shown to include a number of heaters 131 and a thermal sensor 133, each of which is embedded or otherwise mounted within the thermal mass 115. FIG. 1B is also shown to include a flow-path opening 135 and a fluid-outlet port 137, through which precursor-gas vapors may exit the high-flow heat exchanger 100. The fluid-outlet port 137 may be formed within a port connector 143. FIG. 1B is further shown to include chase-gas channels 139 and chase-gas channel plugs 141. Section A-A will be described with reference to FIGS. 1D and 1E, below.

The chase-gas channels 139 form a fluidic path from the chase-gas inlet 101 for entry of the chase gas or purge gas into the first region 107 (see FIG. 1A). In this embodiment, the chase-gas channel plugs 141 provide a blockage to the chase-gas channels 139 after the chase-gas channels 139 have been drilled or otherwise formed into the high-flow heat exchanger 100.

In various embodiments, the flow-path opening 135 may be a location of an outlet from the high-flow heat exchanger 100 (in this particular embodiment, the flow-path opening 135 may be used instead of the fluid-outlet port 137). In other embodiments, the flow-path opening 135 may be a location of a fluid-transfer path on the high-flow heat exchanger 100 from a front-side of the number of flow channels 105 to a back-side number of channels, described in more detail with reference to FIG. 1C through 1E.

The heaters 131 may comprise various types of heaters, such as electrical-resistance heaters or resistive-heating elements. In a specific exemplary embodiment, the heaters 131 comprise electrical-rod heaters. Although three of the heaters 131 are shown, there is no requirement for three heaters. A larger or smaller number of heaters may be used. Further, upon reading and understanding the disclosed subject-matter, a person of ordinary skill in the art will recognize how many of the heaters 131, and their locations, may be needed and how much heat is to be supplied by each heater.

The thermal sensor 133 may comprise various types of thermal-measurement devices, such as, for example, a thermocouple, a resistance-temperature detector, or a thermistor. The thermal sensor 133 provides an electrical output corresponding to a measured temperature of at least a portion of the thermal mass 115. An output of the thermal sensor 133 may be electrically (hardwired or wirelessly) coupled to a control unit in order to control an internal temperature of the high-flow heat exchanger 100.

With reference to FIG. 1C, an example of a top view 150 of the high-flow heat exchanger 100 of FIG. 1A, in accordance with various embodiments of the disclosed subject-matter, is shown. The top view 150 provides an example of how various fluids flow within the high-flow heat exchanger 100.

With concurrent reference to FIG. 1A, a chase gas 151, received from the chase-gas inlet 101 and transported through the chase-gas channels 139, is shown in the first region 107. A carrier gas 153, received from the carrier-gas inlet 103, is shown in the second region 109. A combination 155 of a mixed version of the chase gas 151 and the carrier gas 153 is shown in the third region 111. After flowing through a “back portion” (as shown as the uppermost portion of the top view 150), the combination 155 of the mixed version of the chase gas 151 and the carrier gas 153 continues to be heated by the number of heaters 131 until the mixed and heated version of the gases exits as a vapor through the fluid-outlet port 137.

With concurrent reference now to Section A-A of FIG. 1B, FIG. 1D shows an example of a cross-sectional-view 170 (Section A-A) of the front-view 130 of the high-flow heat exchanger of FIG. 1B. The cross-sectional view 170 is shown to include a number of rectangular versions of the flow channels 105.

With continuing concurrent reference to Section A-A of FIG. 1B, FIG. 1E shows another example of a cross-sectional-view 190 (Section A-A) of the front-view 130 of the high-flow heat exchanger of FIG. 1B. The cross-sectional view 190 is shown to include a number of rounded or semi-circular flow channels 191, in accordance with various embodiments of the disclosed subject-matter. In this embodiment, the semi-circular flow channels 191 may be formed using, for example, a ball endmill on a milling tool (e.g., a computer-based numerically controlled (CNC) machine). A region 193 of flow channels will be described with reference to FIG. 2B, below.

Upon reading and understanding the disclosed subject-matter, a person of ordinary skill in the art will recognize that any shape or combination of shapes of the flow channels may be used with various embodiments of the disclosed subject-matter. Actual shapes and combinations of shapes used in forming the flow channels, locations of the flow channels, as well as a total number of the flow channels, may readily be changes to suit a particular application.

FIG. 2A shows an exemplary embodiment of an end-view 200 of the high-flow heat exchanger 100 of FIG. 1A and how a fluidic barrier may be formed over the flow channels 105 of, for example, FIG. 1D. In this embodiment, a pair of flat plates 201 is used as the fluidic barrier to cover the flow channels 105.

The pair of flat plates 201 may comprise any number of thermally-conductive or non-thermally-conductive materials. Non-thermally-conductive materials (e.g., such as plastics or other dielectric materials) may be used to form the pair of flat plates 201 since no heat is supplied from the pair of flat plates 201 to fluids flowing within the high-flow heat exchanger 100. In various embodiments, it may be desirable to form the pair of flat plates 201 from an insulating material (such as various types of plastics) to retain heat within the high-flow heat exchanger 100. However, in other embodiments, it may be desirable to form the pair of flat plates 201 from materials having a coefficient-of-thermal-expansion (CTE) with a value similar to or substantially the same as the material used to form the high-flow heat exchanger 100. Therefore, the pair of flat plates 201 may be formed from the same material as the material used to form the high-flow heat exchanger 100.

FIG. 2B shows another exemplary embodiment of a top cross-sectional view 210 of a portion (the region 193) of the high-flow heat exchanger 100 of FIG. 1A and another type of fluidic barrier that may be formed over the flow channels 191 of, for example, FIG. 1E. In this embodiment, a left-side fluidic barrier 213L and a right-side fluidic barrier 213R are formed to have cross-section shapes similar or complementary to the number of rounded or semi-circular flow channels 191 as used to form the channels in FIG. 1E. For example, a semi-circular left-side version 211L and a semi-circular right-side version 211R of the flow channels used on the left-side fluidic barrier 213L and the right-side fluidic barrier 213R, when combined with the rounded or semi-circular flow channels 191, form closed circular or elongated (e.g., oval) “tubes.”

As with the fluidic barriers of FIG. 2A, the left-side fluidic barrier 213L and the right-side fluidic barrier 213R may comprise any number of thermally-conductive or non-thermally-conductive materials. Non-thermally-conductive materials (e.g., such as plastics or other dielectric materials) may be used to form the left-side fluidic barrier 213L and the right-side fluidic barrier 213R since no heat is supplied from the pair of fluidic barriers to fluids flowing within the high-flow heat exchanger 100. In various embodiments, it may be desirable to form the left-side fluidic barrier 213L and the right-side fluidic barrier 213R from an insulating material (such as various types of plastics) to retain heat within the high-flow heat exchanger 100. However, in other embodiments, it may be desirable to form the left-side fluidic barrier 213L and the right-side fluidic barrier 213R from materials having a coefficient-of-thermal-expansion (CTE) with a value similar to or substantially the same as the material used to form the high-flow heat exchanger 100. Therefore, the left-side fluidic barrier 213L and the right-side fluidic barrier 213R may be formed from the same material as the material used to form the high-flow heat exchanger 100.

FIG. 3A shows an isometric-view of an exemplary embodiment of a high-flow heat exchanger 300, in accordance with various embodiments of the disclosed subject-matter. In this version of the high-flow heat exchanger 300, there is no chase-gas or purge-gas feature, thus allowing for a more compact design than the high-flow heat exchanger 100 of FIG. 1A. FIG. 3A is shown to include a thermal mass 315 in which a number of channels 305 have been formed. The high-flow heat exchanger 300 is also shown to include a carrier-gas inlet 103.

A carrier-gas region 309 provides volumes within the high-flow heat exchanger 300 in which a carrier-gas may be introduced. A heating region 311 provides volumes within the high-flow heat exchanger 300 in which the carrier-gas is heated.

The carrier-gas inlet 303 can be used to accept a combination of a carrier gas and liquid droplets formed by an atomizer, which is fluidically coupled to the high-flow heat exchanger 300. The liquid droplets are formed from various types of fluids, such as liquid precursors. The liquid droplets formed by the atomizer may be in a size range of, for example, a few microns in diameter to tens of microns. The carrier gas provides a fluid to carry the droplets from the atomizer into the high-flow heat exchanger 300.

FIG. 3A is also shown to include a flow-path opening 335 and a fluid-outlet port 337, through which precursor-gas vapors may exit the high-flow heat exchanger 300. The fluid-outlet port 337 may be formed within a port connector 343.

FIG. 3B shows an example of a bottom-view 330 of the high-flow heat exchanger 300 of FIG. 3A, in accordance with various embodiments of the disclosed subject-matter. The bottom-view 330 of FIG. 3B is shown to include a number of heaters 331, each of which is embedded or otherwise mounted within the thermal mass 315. The number of heaters 331 are shown to include electrical lines coupled thereto.

As described above with reference to FIG. 1B, the heaters 331 may comprise various types of heaters, such as electrical-resistance heaters. In a specific exemplary embodiment, the heaters 331 comprise electrical rod heaters. Although three of the heaters 331 are shown, there is no requirement for three heaters. A larger or smaller number of heaters may be used. Further, upon reading and understanding the disclosed subject-matter, a person of ordinary skill in the art will recognize how many of the heaters 331, and their locations, may be needed and how much heat needs be supplied by each heater. A thermal sensor is not shown explicitly may be placed and used the same as or similarly to the thermal sensor 133 of FIG. 1B.

FIG. 3C shows an example of a front-view 350 of the high-flow heat exchanger 300 of FIG. 3A, in accordance with various embodiments of the disclosed subject-matter. Other than chase-gas or purge-gas feature described above, various aspects and embodiments of the high-flow heat exchanger 100 of FIG. 1A through 1E may also be incorporated into the high-flow heat exchanger 300.

In the context of the disclosed subject-matter contained herein, various embodiments of a high-flow heat exchanger have been shown and described. Further, the description provided herein includes references to the accompanying drawings, which form a part of the detailed description. The drawings show, by way of illustration, specific embodiments in which the invention can be practiced. These embodiments are also referred to herein as “examples.” Such examples can include elements in addition to those shown or described. However, the present inventors also contemplate examples in which only those elements shown or described are provided. Moreover, the present inventors also contemplate examples using any combination or permutation of those elements shown or described (or one or more aspects thereof), either with respect to a particular example (or one or more aspects thereof), or with respect to other examples (or one or more aspects thereof) shown or described herein.

In the event of inconsistent usages between this document and any documents so incorporated by reference, the usage in this document controls. Moreover, in this document, the terms “a” or “an” are used, as is common in patent documents, to include one or more than one, independent of any other instances or usages of “at least one” or “one or more.” In this document, the term “or” is used to refer to a nonexclusive or, such that “A or B” includes “A but not B,” “B but not A,” and “A and B,” unless otherwise indicated. In this document, the terms “including” and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein.” Also, in the following claims, the terms “including” and “comprising” are open-ended, that is, a system, device, article, composition, formulation, or process that includes elements in addition to those listed after such a term in a claim are still deemed to fall within the scope of that claim. Moreover, in the following claims, the terms “first,” “second,” and “third,” etc. are used merely as labels, and are not intended to impose numerical requirements on their objects.

Geometric terms, such as “parallel,” “perpendicular,” “round,” or “square,” are not intended to require absolute mathematical precision, unless the context indicates otherwise. Instead, such geometric terms allow for variations due to manufacturing or equivalent functions. For example, if an element is described as “round” or “generally round,” a component that is not precisely circular (e.g., one that is slightly oblong or is a many-sided polygon) is still encompassed by this description.

As used herein, the term “or” may be construed in an inclusive or exclusive sense. Further, other embodiments will be understood by a person of ordinary skill in the art upon reading and understanding the disclosure provided. Further, upon reading and understanding the disclosure provided herein, the person of ordinary skill in the art will readily understand that various combinations of the techniques and examples provided herein may all be applied in various configurations.

Although various embodiments are discussed separately, these separate embodiments are not intended to be considered as independent techniques or designs. As indicated above, each of the various portions may be inter-related and each may be used separately or in combination with other embodiments discussed herein. For example, although various embodiments of methods, operations, and processes have been described, these methods, operations, and processes may be used either separately or in various combinations.

Consequently, many modifications and variations can be made, as will be apparent to a person of ordinary skill in the art upon reading and understanding the disclosure provided herein. Further, functionally equivalent methods and devices within the scope of the disclosure, in addition to those enumerated herein, will be apparent to the skilled artisan from the foregoing descriptions. Portions and features of some embodiments, materials, and construction techniques may be included in, or substituted for, those of others. Such modifications and variations are intended to fall within a scope of the appended claims. Therefore, the present disclosure is to be limited only by the terms of the appended claims, along with the full scope of equivalents to which such claims are entitled. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting.