FLUORITE-BASED MATERIAL THIN FILM AND SEMICONDUCTOR DEVICE COMPRISING THE SAME
20220169530 · 2022-06-02
Assignee
Inventors
Cpc classification
C04B2235/3296
CHEMISTRY; METALLURGY
H01L29/42392
ELECTRICITY
H01L29/78391
ELECTRICITY
C04B2235/3293
CHEMISTRY; METALLURGY
C04B2235/76
CHEMISTRY; METALLURGY
H10B51/00
ELECTRICITY
C04B2235/3208
CHEMISTRY; METALLURGY
B82Y10/00
PERFORMING OPERATIONS; TRANSPORTING
C04B2235/3206
CHEMISTRY; METALLURGY
C04B2235/3215
CHEMISTRY; METALLURGY
C04B2235/3213
CHEMISTRY; METALLURGY
C04B2235/3225
CHEMISTRY; METALLURGY
C04B2235/3418
CHEMISTRY; METALLURGY
C04B2235/3287
CHEMISTRY; METALLURGY
C04B2235/3232
CHEMISTRY; METALLURGY
C04B2235/3217
CHEMISTRY; METALLURGY
H10B53/00
ELECTRICITY
H01L29/775
ELECTRICITY
C04B2235/3227
CHEMISTRY; METALLURGY
C04B2235/3224
CHEMISTRY; METALLURGY
H01L28/65
ELECTRICITY
C30B29/68
CHEMISTRY; METALLURGY
H01L29/78696
ELECTRICITY
International classification
Abstract
Provided is a fluorite-based material thin film including an orthorhombic crystal structure having a symmetric segment and a non-symmetric segment; and at least two domains having different polarization directions. At least one of, the symmetric segment is not present at a wall between the domains, or at least two symmetric segments are consecutive. Also provided is a semiconductor device including the fluorite-based material thin film having an orthorhombic crystal structure. A polarization direction of the fluorite-based material thin film is configured to be changed by a structural transition between the symmetric segment and the non-symmetric segment.
Claims
1. A fluorite-based material thin film comprising: an orthorhombic crystal structure having a symmetric segment and a non-symmetric segment; and at least two domains having different polarization directions, wherein, (A) the symmetric segment is not present at a wall between the at least two domains, or (B) at least two of the symmetric segment are consecutively adjacent.
2. The fluorite-based material thin film of claim 1, wherein the symmetric segment includes, in a crystal lattice having four oxygen ions and two metal ions, an atomic arrangement structure in which positions of the metal ions and the oxygen ions have symmetry with respect to a polar c-axis.
3. The fluorite-based material thin film of claim 1, wherein the non-symmetric segment includes, in a crystal lattice having four oxygen ions and two metal ions, an atomic arrangement structure in which positions of the metal ions and the oxygen ions have non-symmetry with respect to a polar c-axis.
4. The fluorite-based material thin film of claim 1, wherein each of the at least two domains is a set of adjacent orthorhombic crystal structures having a same polarization direction.
5. The fluorite-based material thin film of claim 1, wherein the fluorite-based material thin film comprises an atomic arrangement represented by U-S.sub.x-D, wherein S is the symmetric segment, x is an integer of 0, 2, 3, 4, or 5, and U and D are domains having different polarization directions from each other.
6. The fluorite-based material thin film of claim 5, wherein U and D have a same chirality.
7. The fluorite-based material thin film of claim 5, wherein each of U and D is a domain with an atomic arrangement in which the non-symmetric segment is arranged adjacent to S.sub.x.
8. The fluorite-based material thin film of claim 1, wherein the orthorhombic crystal structure comprises a material represented by MO.sub.2, wherein M is Hf, Zr, or a combination of Hf or Zr.
9. The fluorite-based material thin film of claim 1, wherein the orthorhombic crystal structure comprises: as a base material, a material represented by MO.sub.2, wherein M is Hf, Zr, or a combination of Hf and Zr; and at least one dopant material selected from the group including C, Si, Ge, Sn, Pb, Al, Y, La, Gd, Mg, Ca, Sr Ba, Ti.
10. The fluorite-based material thin film of claim 9, wherein an amount of the at least one dopant material is greater than 0 at % and less than or equal to 20 at %, the amount with respect to a metal element of the base material.
11. The fluorite-based material thin film of claim 1, wherein the thin film has a thickness greater than 0 nm and less than or equal to 20 nm.
12. The fluorite-based material thin film of claim 1, wherein the fluorite-based material thin film exhibits ferroelectricity.
13. A semiconductor device comprising: a fluorite-based material thin film including an orthorhombic crystal structure having a symmetric segment and a non-symmetric segment, wherein a polarization direction of the fluorite-based material thin film is configured to be changed by a structural transition between the symmetric segment and the non-symmetric segment.
14. The semiconductor device of claim 13, wherein the polarization direction is configured to be changed while at least one of a structural transition of the symmetric segment to the non-symmetric segment or a structural transition of the non-symmetric segment to the symmetric segment occurs according to a direction in which an electric field is applied, the electric field applied from outside of the semiconductor device.
15. The semiconductor device of claim 13, wherein a wall between domains having different polarization directions is configured to propagate while a structural transition of the symmetric segment to the non-symmetric segment or a structural transition of the non-symmetric segment to the symmetric segment occurs, the wall configured to propagate based on a direction in which an electric field is applied, the electric field applied from outside of the semiconductor device.
16. The semiconductor device of claim 13, wherein the fluorite-based material thin film comprises the fluorite-based material thin film of claim 1.
17. The semiconductor device of claim 13, further comprising: a first electrode and a second electrode spaced apart from the first electrode, wherein the fluorite-based material thin film is between the first electrode and the second electrode.
18. The semiconductor device of claim 13, further comprising: a semiconductor substrate including a source and a drain; and a gate electrode opposite to and spaced apart from the semiconductor substrate, wherein the fluorite-based material thin film is between the semiconductor substrate and the gate electrode.
19. The semiconductor device of claim 13, wherein in response to a polarization switching of the fluorite-based material thin film occurring, a local peak appears in 5.0×10.sup.−7 sec or less in a graph of current versus time.
20. An electronic device comprising: the fluorite-based material thin film of claim 1; and at least one active or passive element.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] The above and other aspects, features, and/or advantages of certain embodiments of the disclosure will be more apparent from the following description taken in conjunction with the accompanying drawings, in which:
[0015]
[0016]
[0017]
[0018]
[0019]
[0020]
[0021]
[0022]
[0023]
[0024]
DETAILED DESCRIPTION OF SOME EXAMPLE EMBODIMENTS
[0025] Reference will now be made in detail to some example embodiments, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. In this regard, some example embodiments may have different forms and should not be construed as being limited to the descriptions set forth herein. Accordingly, example embodiments are merely described below, by referring to the figures, to explain aspects. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. Expressions such as “at least one of,” when preceding a list of elements, modify the entire list of elements and do not modify the individual elements of the list.
[0026] In the following description, terms are used only for explaining specific example embodiments while not limiting the scope of some example embodiments. When an element is referred to as being “above” or “on” another element, the element may be directly on an upper, lower, left, or right side of the other element while making contact with the other element or may be above an upper, lower, left, or right side of the other element without making contact with the other element.
[0027] The terms of a singular form may include plural forms unless otherwise mentioned. Unless otherwise mentioned, the terms “comprises” and/or “comprising” used herein specify the presence of stated features, numbers, steps, processes, elements, components, materials, or combinations thereof but do not preclude the presence or addition of one or more other features, numbers, steps, processes, elements, components, materials, or combinations thereof.
[0028] Although terms such as “first,” “second,” and “third” are used to describe various elements, the terms are only used to distinguish one element from other elements, and the features of the elements such as order and type should not be limited by the terms. In addition, terms such as “unit,” “means,” “module,” or “portion” may refer to a unit of a comprehensive structure that has at least one function or operation and may be implemented with hardware, software, or a combination of hardware and software.
[0029] Hereinafter, some example embodiments will be described with reference to the accompanying drawings. In the drawings, like reference numerals refer to like elements, and the sizes of elements (such as the widths and thicknesses of layers or regions) may be exaggerated for clarity of illustration. Some example embodiments described herein are for illustrative purposes only, and various modifications may be made therein.
[0030] Ferroelectrics are materials with ferroelectricity and maintain spontaneous polarization by alignment of internal electric dipole moments even when an external electric field is not applied to the materials. For example, ferroelectrics are materials in which a polarization (or an electric field) remains semi-permanently in the materials even when a certain voltage is applied to the materials and then again the voltage returns to 0V, and the polarization direction may vary according to an external electric field.
[0031] Alternatively or additionally, ferroelectrics may have a negative capacitance in a certain region, and this characteristic may contribute to the low-power operation of semiconductor devices. For example, when a ferroelectric is applied to a transistor, a subthreshold swing value may drop to 60 mV/dec or less, which is the theoretical limit of an existing silicon-based transistor.
[0032] Meanwhile, it is known recently that materials having a fluorite structure/face-centered cubic (FCC) structure, e.g. fluorite-based materials such as a hafnium-based oxide (HfO) materials, have spontaneous polarization in an orthorhombic crystal structure, and may exhibit ferroelectricity. Hafnium-based oxides are expected to be useful for the miniaturization of semiconductor devices because hafnium-based oxides are suitable for application to semiconductor processing and have ferroelectricity even in thin films of a very small thickness of several nanometers.
[0033] However, a fluorite-based material such as a hafnium-based oxide may have a lower polarization switching rate than that of perovskite-based ferroelectrics, such as PbTiO.sub.3, and thus, may have a negative impact on the operation speed of a semiconductor device. Fluorite-based materials may include one or more domains that have a same polarization direction and are defined as a set of orthorhombic crystal structures that are located adjacent each other, and a domain wall may be defined between domains having different polarization directions. The overall polarization direction of fluorite-based materials may change with domain wall propagation. However, fluorite-based materials may have a low polarization switching rate due to high and/or repeating energy barriers during polarization switching.
[0034] According to some example embodiments, a fluorite-based material thin film having a high polarization switching rate and/or a semiconductor device including the same may be provided.
[0035] As described above, the fluorite-based material may have spontaneous polarization in an orthorhombic crystal structure.
[0036]
[0037] In a semiconductor device according to some example embodiments, the polarization direction is changeable through or configured to be changed by a structural transition between the symmetric segment and the non-symmetric segment of the fluorite-based material thin film.
[0038] For example, the fluorite-based material thin film may not include the symmetric segment (s) and/or may include at least two consecutive symmetric segments (s).
[0039] Alternatively or additionally, in the fluorite-based material thin film according to some example embodiments, adjacent domains may have a same chirality, and may maintain the chirality to be the same even after polarization switching (considering a structural change between (a) and (d) of
[0040] The fluorite-based material thin film according to some example embodiments may include an atomic arrangement represented by U-S.sub.x-D. Here, S is the symmetric segment, x is an integer of 0, 2, 3, 4, or 5, and U and D are the domains having different polarizations. Herein, x may not be 1, and may not be more than 5; however, example embodiments are not necessarily limited thereto. For example, in U, which has an atomic arrangement of repeating non-symmetric segments (u) or up and symmetric segments (s), which are denoted by u and s, respectively, the non-symmetric segment (u) may be linked with S.sub.x. Meanwhile, in D, which has an atomic arrangement of repeating non-symmetric segments (d) or down, denoted by d, and symmetric segments (s), the non-symmetric segments (d) may be linked with S.sub.x. Herein, the domains U and D may have the same or different chiralities. For example, the fluorite-based material thin film may include, at the wall between two domains having different polarization directions, an atomic arrangement represented by { . . . usu}{dsd . . . }, . . . usu}ss{dsd . . . }, { . . . usu}sss{dsd . . . }, { . . . usu}ssss{dsd . . . }, { . . . usu}sssss{dsd . . . }, { . . . usu}[dsd . . . ], { . . . usu}ss[dsd . . . ], { . . . usu}sss[dsd . . . ], { . . . usu}ssss[dsd . . . ], or { . . . usu}sssss[dsd . . . ], wherein { . . . } and [ . . . ] represent a right-handed chirality and left-handed chirality, respectively. The propagation of the domain wall of the fluorite-based material thin film may be represented in
[0041] Each of the non-symmetric segments (u) and (d), and each of the symmetric segments (s), may be referred to as a unit cell. The unit cells may be arranged to extend in a first direction.
[0042] The fluorite-based material thin film may have a thickness of about 20 nm or less. For example, the fluorite-based material thin film may have a thickness of greater than 0 nm, about 0.5 nm or greater, about 1 nm or greater, about 1.5 nm or greater, about 2 nm or greater, about 20 nm or less, about 18 nm or less, about 15 nm or less, about 10 nm or less, or about 5 nm or less.
[0043] The fluorite-based material thin film may include a material represented by MO.sub.2, wherein M is Hf, Zr, or a combination of Hf and Zr. In addition, the fluorite-based material thin film may include, as a base material, a material represented by MO.sub.2, wherein M is Hf, Zr, or a combination of Hf and Zr, and may further include one or more dopant materials selected from the group consisting of or including C, Si, Ge, Sn, Pb, Al, Y, La, Gd, Mg, Ca, Sr Ba, Ti, and a combination thereof. The amount of the dopant material may be greater than 0 at %, about 0.2 at % or greater, about 0.5 at % or greater, about 1 at % or greater, about 2 at % or greater, about 3 at % or greater, about 4 at % or greater, about 5 at % or greater, about 20 at % or less, about 18 at % or less, about 15 at % or less, about 12 at % or less, about 10 at % or less, about 8 at % or less, about 7 at % or less, or about 6 at % or less, with respect to the metal element of the base material.
[0044] The orthorhombic crystal structure and/or atomic arrangement of the fluorite-based material thin film may be identified using a method, such as for example, at least one of scanning transmission electron microscopy (STEM), transmission electron microscopy (TEM), grazing incidence X-ray diffraction (GIXRD), and/or the like.
[0045] The fluorite-based material thin film may include an orthorhombic crystal phase including the orthorhombic crystal structure. For example, the fluorite-based material thin film may include various crystal phases such as an orthorhombic crystal phase and a tetragonal crystal phase, but may predominantly include the orthorhombic crystal phase (the largest or highest proportion of all crystal phases, or the crystal phase of a plurality of all crystal phases).
[0046] The fluorite-based material thin film having ferroelectricity may be manufactured or fabricated by forming an amorphous layer including a desired composition, and annealing the same.
[0047] The annealing process may be performed with at least one of a furnace annealing process, a rapid thermal annealing (RTA) process, or a laser annealing (LA) process; however, example embodiments are not limited thereto.
[0048] The amorphous layer including a desired composition may be formed using a deposition process such as at least one of a chemical vapor deposition (CVD) process, an atomic layer deposition (ALD) process, a plasma enhanced chemical vapor deposition (PECVD) process, or a low pressure chemical vapor deposition (LPCVD) process; however, example embodiments are not limited thereto. For example, an atomic layer deposition (ALD) method has advantages in that a uniform layer may be formed at an atomic level and may be performed at a relatively low temperature.
[0049] When the amorphous layer is formed by the ALD method, precursors may be used for a hafnium source, a zirconium source, and an oxygen source. For example, as the hafnium source, at least one selected from the group consisting of Hf(OtBu).sub.4, tetrakis ethylmethylamino hafnium (TEMAH), dimethylamino hafnium (TDMAH), tetrakis diethylamino hafnium (TDEAH), and/or a combination thereof may be used. However, examples of the hafnium source are not limited thereto. In addition, as the zirconium source, at least one selected from the group consisting of or including Zr(OtBu).sub.4, tetrakis ethylmethylamino zirconium (TEMAZ), tetrakis dimethylamino zirconium (TDMAZ), tetrakis diethylamino zirconium (TDEAZ), and a combination thereof may be used. However, examples of the zirconium source are not limited thereto. In addition, as the oxygen source, at least one selected from the group consisting of or including O.sub.3, H.sub.2O, O.sub.2, N.sub.2O, O.sub.2 plasma, and a combination thereof may be used. However, examples of the oxygen source are not limited thereto.
[0050] For the annealing step, any or all of the temperature, time, atmosphere, and the like may be controlled such that the fluorite-based amorphous layer is crystallized with an orthorhombic crystal structure. A thermal budget of the annealing step may be determined in consideration of the composition and/or thickness of the fluorite-based amorphous layer. The annealing may be performed at a temperature of about 400° C. to about 1100° C., but is not limited thereto. The annealing may be performed for a period of time of about 1 nanosecond or greater, about 1 microsecond or greater, about 0.001 seconds or greater, about 0.01 seconds or greater, about 0.05 seconds or greater, about 0.1 seconds or greater, about 0.5 seconds or greater, about 1 second or greater, about 3 seconds or greater, about 5 seconds or greater, about 10 minutes or less, about 5 minutes or less, about 1 minute or less, or about 30 seconds or less, but is not limited thereto. The annealing step may include a first annealing step and a second annealing step. For example, the first annealing step may be performed at a lower temperature and/or for a shorter time than that of the second annealing step. The atmosphere in which the annealing is performed is not particularly limited. For example, the first annealing may be performed under an atmosphere of at least one of H.sub.2O, O.sub.2, O.sub.3, N.sub.2, H.sub.2, and/or NH.sub.3.
[0051] Alternatively or additionally, an electric field having an appropriate magnitude and/or direction may be applied locally, such that the fluorite-based material thin film has a desired atomic arrangement and/or domain arrangement. For example, by applying an external electric field having an appropriate direction and/or magnitude to a local region of the fluorite-based material thin film having the repeating symmetric segments and non-symmetric segments, the fluorite-based material thin film may be controlled such that the corresponding region does not have the symmetric segment, or has consecutive symmetric segments.
[0052] A device according to some example embodiments may be or may include a memory device or non-memory device, for example, may be or may include, but not limited to, a capacitor, an electric field-effect transistor, a diode, or a combination structure thereof.
[0053] The semiconductor device may have an improved or excellent polarization switching rate, as compared with a semiconductor device of a related art.
[0054]
[0055] The substrate 100 may include a semiconductor material. For example, the substrate 100 may include Si, Ge, SiGe, a Group III-V semiconductor, or the like, and may be modified and used in various forms such as a silicon on insulator (SOI).
[0056] The substrate 100 may include the source 120 (121) and the drain 130 (131), and may include a channel 110 (111) electrically connected to or contact or directly contact the sources 120 (121) and the drain 130 (131). The source 120 (121) may be electrically connected to or contact or directly contact one end of the channel 110 (111), and the drain 130 (131) may be electrically connected or contact or directly contact the other end of the channel 110 (111).
[0057] Referring to
[0058] The source 120 and the drain 130 may be implanted with an impurity having a first conductivity, and the channel 110 may be implanted with an impurity having a second polarity, opposite to the first polarity. However, example embodiments are not limited thereto. For example, the source 120 and/or the drain 130 may be implanted with boron, and the channel 110 may be implanted with phosphorus and/or arsenic; however, example embodiments are not limited thereto. Alternatively or additionally, the source 120 and/or the drain 130 may be implanted with phosphorus and/or arsenic, and the channel 110 may be implanted with boron; however, example embodiments are not limited thereto.
[0059] In addition, referring to
[0060] Referring to
[0061] The fluorite-based material thin film 200 may be arranged between the substrate 100 and the gate electrode 300. For example, the fluorite-based material layer 200 may be formed on the channel 110 and 111. For the fluorite-based material thin film 200, the description above may be referred to.
[0062]
[0063] Referring to
[0064] The field-effect transistor may be implemented in various forms, such as a 2-dimensional form or a 3-dimensional form. For example, the field-effect transistor may be of a 1-gate on channel type such as a planar-FET, a 3-gate on channel type such as a fin-FET, or a 4-gate on channel type such as a gate-all-around-FET, such as a multi-bridge channel FET (MBCFET™).
[0065]
[0066]
[0067]
[0068] The first electrode 600 and the second electrode 700 may have a conductivity of about 1 Mohm/square or less; however, example embodiments are not limited thereto, and may include or consist of a same material or different materials. For example, the first electrode 600 and the second electrode 700 may each independently include at least one of TiN, TaN, Ti, Ta, TiCN, TiSiN, WSiN, TiAlN, TaAlN, TiAlCN, TiW, RuTiN, RuCN, Pt, Au, Mo or Al. As a specific example, the first electrode 600 and the second electrode 700 may each independently include TiN and/or Mo. A thickness of the first electrode 600 and the second electrode 700 may be equal to or greater than about 1 nm and less than or equal to about 20 nm, and may be the same as, or different from, one another.
[0069] According to some example embodiments, a semiconductor apparatus including the fluorite-based material thin film and/or semiconductor device as described above may be provided. The semiconductor apparatus may include a plurality of semiconductor devices, and may be in a form in which a field-effect transistor and a capacitor are electrically connected. The semiconductor apparatus may have memory characteristics, and may be, for example, a DRAM that may be volatile or non-volatile.
[0070] The FET D61 may include a substrate 100 including the source 120, the drain 130, and a channel 110, and the gate electrode 300 arranged to face the channel 110. A dielectric layer 410 may be further included between the substrate 100 and the gate electrode 300. Although the FET D61 of
[0071] The arrangement of the capacitor D60 and the FET D61 may be variously modified. For example, the capacitor D60 may be arranged on the substrate 100, or, alternatively, may be buried in the substrate 100.
[0072] The semiconductor device and semiconductor apparatus according to some example embodiments may be applied to various electronic apparatuses. For example, the above-described FET and capacitor, or a combination thereof may be applied as a logic device or a memory device in various electronic apparatuses. The semiconductor device according to some example embodiments has advantages in terms of efficiency, speed, and/or power consumption, and thus may meet or help to meet the demand for miniaturization and/or integration of electronic devices. For example, semiconductor devices and semiconductor apparatuses may be used for arithmetic operations, program execution, temporary data retention, etc. in electronic devices such as mobile devices, computers, notebook computers, sensors, network devices, neuromorphic devices, etc. The semiconductor device and semiconductor apparatus according to some example embodiments may be useful for electronic apparatuses in which the amount of data transmission is large and data transmission is continuously performed.
[0073]
[0074] Referring to
[0075] The electronic device architecture 100 may include at least one additional active device (e.g., a transistor and/or a diode), in addition to one or more of FETs D10, D20, D30, D40, D50 or capacitor D60. Alternatively or additionally, the electronic device architecture 100 may include at least one additional passive device (e.g., a resistor, a capacitor, an inductor, or a memristor), in addition to one or more of FETs D10, D20, D30, D40, D50 or capacitor D60.
[0076] The memory unit 1010, the ALU 1020, and the control unit 1030 may each independently include the semiconductor device (one or more of FETs D10, D20, D30, D40, D50, or capacitor D60, etc.) described above. For example, the ALU 1020 and the control unit 1030 may each independently include the FET described above, and the memory unit 1010 may be the capacitor or FET described above, or a combination thereof. The memory unit 1010 may include both a main memory and a cache memory. The electronic device architecture (chip) 1000 may be or may include an on-chip memory processing unit.
[0077] Referring to
[0078] In some cases, the electronic device architecture 1000 may be implemented in a form in which computing unit devices and memory unit devices are adjacent to each other on a single chip, without division of sub-units.
[0079] .sub.[GH1]The first and second pocket regions 127 and 137 may be doped with, e.g. implanted with, a second impurity. The conductivity type of the second impurity may be different from, or opposite to, the conductivity type of the first impurity.
[0080] As described above, according to the one or more example embodiments, a fluorite-based material thin film having ferroelectricity and/or excellent polarization switching rate may be provided. As described above, according to the one or more example embodiments, a semiconductor device having an improved operation rate and/or high capacitance may be provided. The fluorite-based material thin film and semiconductor element may be applicable to various electronic devices, electronic apparatuses, electronic circuits, and/or the like. Some example embodiments may be applicable to other films, such as other thin-films having an anti-fluorite structure.
[0081] Any of the elements and/or functional blocks disclosed above may include or be implemented in processing circuitry such as hardware including logic circuits; a hardware/software combination such as a processor executing software; or a combination thereof. For example, the processing circuitry more specifically may include, but is not limited to, a central processing unit (CPU), an arithmetic logic unit (ALU), a digital signal processor, a microcomputer, a field programmable gate array (FPGA), a System-on-Chip (SoC), a programmable logic unit, a microprocessor, application-specific integrated circuit (ASIC), etc. The processing circuitry may include electrical components such as at least one of transistors, resistors, capacitors, etc. The processing circuitry may include electrical components such as logic gates including at least one of AND gates, OR gates, NAND gates, NOT gates, etc.
[0082] It should be understood that some example embodiments described herein should be considered in a descriptive sense only and not for purposes of limitation. Descriptions of features or aspects within each example embodiment should typically be considered as available for other similar features or aspects in other embodiments. While one or more example embodiments have been described with reference to the figures, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and/or scope as defined by the following claims.