Patent Application
20060113524
The present invention relates generally to semiconductor transistor devices and, in particular, to polymer-based transistor devices.
Semiconductors have permeated into every aspect of modern society. They are the building blocks used to create everything from the information super-highway to the electronic timer in the family toaster. Generally, any device that is considered “electronic” utilizes semiconductors. These often-unseen components help to reduce the daily workload, increase the safety of our air traffic control systems, and even let us know when it is time to add softener to the washing machine. Modern society has come to rely on these devices in almost every product produced today. And, as we progress further into a technologically dependent society, the demand for increased device speeds, capacity and functionality drive semiconductor manufacturers to push the edge of technology even further.
One common type of semiconductor is the transistor. This device revolutionized the electronics industry after its invention in 1947. Prior to this time, circuits requiring amplification of signals were forced to utilize bulky vacuum tubes for this task. Transistors provided signal amplification at less than a tenth the size of vacuum tubes. This led to new portable devices, such as the transistor radio, that before the transistor could not have been transported easily. Communication devices depend heavily on amplification of signals to operate properly. Big bulky equipment was suddenly reduced in size to handy portable units. Thus, the transistor helped to create a new world of electronic devices that could fit and be utilized in ways never before possible, replacing the fragile and bulky vacuum tubes.
A transistor is a tiny electronic component that changes a small input signal into a large output signal. The process of changing a small signal into a large signal while retaining the integrity of the small signal is known as amplification. For instance, if a weak radio signal is received by an antenna, the signal can be processed by a transistor and amplified such that a human being can hear the transmitted signal. The transistor is typically comprised of three layers of semiconductor material. The amplification process is accomplished by applying the weak signal across the inner layer to one of the outer layers. This creates a duplicate but much stronger signal between the two outer layers. Typically, the transistor is accompanied by other electronic components to aid in creating a transistor type amplification process.
Transistor technology has progressed steadily since 1947 when they were first discovered. Many different types of transistors have been developed such as junction, FET (field-effect transistor), and MOSFET (metal-oxide semiconductor field-effect transistor). Generally speaking, a transistor is comprised of semiconductor materials that interface with common physical boundaries. The semiconductor materials utilized include gallium-arsenide and germanium which are doped with impurities to make them conductive. An “n-type” semiconductor has excess electrons due to the impurities and a “p-type” semiconductor has a deficiency of electrons, and therefore, an excess of holes. Electrons are negative charge carriers and holes are positive charge carriers.
A junction transistor consists of two outer semiconductors separated by a thin layer of an opposing type of semiconductor material. When the electric potentials on one of the outer layers and the thin layer meet a certain threshold, a small current between the layers occurs. This small current creates a large current between the two outer semiconductor layers, producing current amplification. Junction transistors can be N-P-N or P-N-P. Either type operates in the same fashion, but each operates with different polarities. The transistor can also be employed as a switch.
The FET was developed after the junction transistor and draws virtually no power from an input signal, surmounting a major obstacle of the junction transistor. An FET is comprised of a channel of semiconductor material interposed between two electrodes. The electrodes attached to the ends of the channel are called the source and the drain. The channel contains regions of opposing semiconductor material to that which makes up the electrodes (p-type versus n-type or n-type versus p-type). These regions are in proximity to electrodes called gates. A specific threshold potential applied to the gates impedes current flow between the source and the drain. This is normally referred to as a reverse potential or voltage. Changing the value of this reverse potential alters the resistance of the channel, allowing the reverse potential to regulate the current flow between the source and the drain. Altering the type of composition of the semiconductor material allows for the device to operate with reversed polarities.
Another variation of the FET transistor is the MOSFET. This is a single gate device in which the gate is separated from the channel by a layer of dielectric, typically metal oxide. The gate's electric field penetrates through the dielectric layer and into the channel, controlling the resistance of the current through the channel. A potential applied to the gate of the MOSFET can increase the current flow between the source and the drain and also decrease it.
The following is a summary of the invention in order to provide a basic understanding of some aspects of the invention. This summary is not intended to identify key/critical elements of the invention or to delineate the scope of the invention. Its sole purpose is to present some concepts of the invention in a simplified form as a prelude to the more detailed description that is presented later.
The present invention provides semiconductor devices that possess one or more of the following: small size compared to inorganic semiconductor devices, capability to amplify current flow, quick operational response time, lower operating voltages, low cost, high reliability, long life, increased current flow over inorganic semiconductor devices, low temperature processing, light weight, and high density.
One aspect of the present invention relates to a semiconductor transistor device with an annular gate. This increases the amount of channel cross sectional area affected by the annular gate, allowing more current to flow. Thus, for the same given size or density, the present device can amplify (or control) a much greater current, increasing performance and flexibility of the device.
Another aspect of the present invention relates to a semiconductor transistor device containing a channel composed of an organic polymer material. This allows variability in the current handling capabilities of a given device depending upon the current flow characteristics of the polymer material utilized during manufacture, increasing the flexibility of existing manufacturing processes and reducing manufacturing costs.
Organic semiconductor materials (OSM) offer the ability to produce more efficient and enhanced semiconductor devices. Components that were thought to be reaching their molecular limitations as their sizes diminished, are finding new life through the use of OSM. This type of material also allows for smaller and faster semiconductor devices. OSM utilization is allowing the next generation of semiconductor products to advance forward and, at the same time, simplifying the manufacturing process. The combination of inorganic technologies with organic technologies is required to preserve the initial investments facilities have made in semiconductor manufacturing processes, extending their production capabilities.
Yet another aspect of the present invention relates to fabrication of a device utilizing a polymer channel surrounded, at least in part, by an annular gate.
Still yet another aspect of the present invention relates to a system with a means to control (or amplify) current via an annular gate surrounding a channel.
To the accomplishment of the foregoing and related ends, the invention comprises the features hereinafter fully described and particularly pointed out in the claims. The following description and the annexed drawings set forth in detail certain illustrative aspects and implementations of the invention. These are indicative, however, of but a few of the various ways in which the principles of the invention may be employed. Other objects, advantages and novel features of the invention will become apparent from the following detailed description of the invention when considered in conjunction with the drawings.
The present invention is now described with reference to the drawings, wherein like reference numerals are used to refer to like elements throughout. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It may be evident, however, that the present invention may be practiced without these specific details. In other instances, well-known structures and devices are shown in block diagram form in order to facilitate describing the present invention.
As used in this application, the term “computer component” is intended to refer to a computer-related entity, either hardware, a combination of hardware and software, software, or software in execution. For example, a computer component may be, but is not limited to being, a process running on a processor, a processor, an object, an executable, a thread of execution, a program, and/or a computer. By way of illustration, both an application running on a server and the server can be a computer component. One or more computer components may reside within a process and/or thread of execution and a component may be localized on one computer and/or distributed between two or more computers.
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The term annular in the present invention refers to an element with substantially ring-like properties that may or may not entirely encompass another element. For example, the element can possess characteristics of a hexagon, an octagon, a circle and/or even a square and the like. It can also include, but is not limited to, characteristics of a semi-circle, a partial semi-circle, and a horseshoe-shape and the like. The characteristics are not required to be perfectly symmetrical nor unvarying in dimensions. For example, a tear drop shape with tapering thicknesses and the like are within the scope of the present invention. Annular is representative of an element's relationship to another element in its characteristic of attempting to surround the other element, partially or wholly.
Operationally, a voltage applied to the third contact point 120 induces a current to flow between the second contact point 116 and the first contact point 106. A typical device can have a current gain in an approximate range of 10 to 150 based on the inverse of a frequency of a signal. This produces current amplification which is the forte of all transistors. MOSFET type devices and the present invention also amplify voltages as well. Generally, transistors will accurately amplify an input signal as long as it is operated within its parameters. Some of these parameters include a transistor's operational temperature range and frequency of the signals.
The annular gate 118 is typically comprised of polysilicon material such as polycrystalline silicon. The first and second source/drains are comprised of conductive materials. However, it is not necessary for the first and second source/drains 104, 114 to both be composed of the same conductive material. In one aspect of the present invention, the first and second source/drains 104, 114 are comprised of a conductive material such as aluminum, chromium, copper, germanium, gold, magnesium, manganese, indium, iron, nickel, palladium, platinum, silver, titanium, zinc, alloys thereof, indium-tin oxide, polysilicon, doped amorphous silicon, metal silicides, and the like. Exemplary alloys that can be utilized for the conductive material include Hastelloy®, Kovar®, Invar, Monel®, Inconel®, brass, stainless steel, magnesium-silver alloy, and various other alloys. The thicknesses of the first and second source/drains 104, 114 can vary depending on the implementation and the semiconductor device being constructed. However, some exemplary thickness ranges include about 0.01 μm or more and about 10 μm or less, about 0.05 μm or more and about 5 μm or less, and/or about 0.1 μm or more and about 1 μm or less.
The first and second source/drains 104, 114 can be deposited on the substrate 102 and the channel 110, respectively, in any manner suitable for transistor fabrication. This can include chemical vapor deposition (CVD) processes such as atmospheric pressure CVD (APCVD), low pressure CVD (LPCVD), plasma-enhanced CVD (PECVD), photochemical (ultraviolet) (LPCVD), vapor phase epitaxy (VPE), and metalorganic CVD (MOCVD). Additional non-CVD methods such as molecular beam epitaxy (MBE) are also acceptable.
The channel 110 comprises a semiconductor material such as an organic conjugated molecule(s). Such conjugated molecules are characterized in that they have overlapping π orbitals and that they can assume two or more resonant structures. The organic molecules may be cyclic or acyclic. Examples of conjugated organic materials include one or more of polyacetylene (cis or trans); polyphenylacetylene (cis or trans); polydiphenylacetylene; polyaniline; poly (p-phenylene vinylene); polythiophene; polyporphyrins; porphyrinic macrocycles, thiol derivatized polyporphyrins; polymetallocenes such as polyferrocenes, polyphthalocyanines; polyvinylenes; polystiroles; and the like. Additionally, the properties of the polymer can be modified by doping with a suitable dopant (e.g., salt).
The channel 110 can be formed by a number of suitable techniques, some of which are described supra. One suitable technique that can be utilized is a spin-on technique that involves depositing a mixture of the polymer/polymer precursor and a solvent, and then removing the solvent from the first source/drain 104. Another technique is chemical vapor deposition (CVD) optionally including a gas reaction, gas phase deposition, and the like. CVD includes low pressure chemical vapor deposition (LPCVD), plasma enhanced chemical vapor deposition (PECVD), and high density chemical vapor deposition (HDCVD). It is not typically necessary to functionalize one or more ends of the organic molecule in order to attach it to the first and second source/drains 104, 114.
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A gate-channel separation distance 218 defines a thickness for a gate oxide layer (not shown, see
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In order to determine a width of the channel 308, it must be noted that the channel 308 is surrounded by an annular gate (not shown, see
Basic geometry states:
circumference=2πR (Eq. 1)
where the approximate value of π is 3.14 . . . (the decimal continuing forever) and R is the radius of the circle (or, in this case, a channel radius 316 of the channel 308). Thus, the channel width is defined as:
channel width=2πR (Eq. 2)
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Transistors can be PNP (n-doped sandwiched between p-doped regions) or NPN (p-doped sandwiched between n-doped regions) type depending on how they are manufactured and what materials are used. For a PNP transistor, current is carried by holes which are positively charged and are attracted by a negative voltage. For an NPN transistor, current is carried by electrons which are positively charged and are attracted by negative voltage. Generally speaking, the difference between the two types is the reversal of the potentials across the contacts. For this reason, a general discussion of only an NPN type transistor is given.
In a typical example of an NPN type transistor, a source and a drain are identical. However, the manner in which voltages are applied to a transistor's contacts determines which is the source and which is the drain. The source provides the electrons and the drain receives the electrons in this type of transistor. A voltage applied to the gate controls the flow of electrons from the source to the drain. The electrons form a conducting channel between the source and the drain which is known as an inversion layer 422. Because the present invention utilizes an annular gate, its inversion layer 422 is actually a tube-like structure (described infra in
Amplification is accomplished for both voltage and current. Current gain is achieved because no gate current is required to maintain the inversion layer 422 and the resulting current between the drain and the source. This allows the device to have infinite current gain in DC (direct current) applications. Due to the isolation of the gate from the channel, DC input impedance is also very high. This current gain is inversely proportional to its signal frequency. Voltage gain is caused by current saturation at higher drain/source voltages. This allows a small current variation to cause a large drain voltage variation.
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In order to fully understand the operation of the present device, it is helpful to illustrate by example an instance of the present invention for an NPN configuration. A voltage level, VS 622, represents a voltage level of the source 608. A voltage level, VG 624, represents a voltage level of the annular gate 610. A voltage level, VD 626, represents a voltage level of the drain 604. A potential difference between the source 608 and the annular gate 610 is represented by VGS 628. A potential difference between the source 608 and the drain 604 is represented by VDS 630. Since the cylindrical channel 606 is doped, an inversion region 632 is formed within the cylindrical channel 606. A current, ID 634, can flow through the inversion region 632 under certain conditions. The annular gate 610 controls the current, ID 634, by varying the conductance of the inversion region 632 in the cylindrical channel 606. Varying ranges of conductivity can be achieved with the present invention by utilizing different polymers and/or different doping levels. For a given VGS 628, there exists a VDS 630 where ID 634 becomes saturated and can no longer increase.
Threshold voltages play an important part in determining what region a transistor is operating in. A threshold voltage, VT, is a minimum gate voltage, VG 624, required to induce a current, ID 634, in the cylindrical channel 606. Therefore, VGS 628 must be greater than VT for an inversion region 632 to form. Generally speaking, a transistor can operate in different modes such as enhancement mode or depletion mode. Enhancement mode is defined when a transistor is OFF at the same time that VGS 628 is zero and, subsequently, a positive VG 624 is required to create an inversion region 632 in the cylindrical channel 606. This mode, due to its characteristics, can be employed in digital circuitry that requires switching between ON and OFF states. Depletion mode is defined when the cylindrical channel 606 has an existing inversion region 632 when VGS 628 is equal to zero. In this mode, the device 600 operates with both positive and negative levels of VGS 628.
The most common operating mode is the enhancement mode. Its drain characteristics are discussed with reference to
Q(x)=−C*W*(VGS−VT) (Eq. 3)
where C is the capacitance per unit length for a parallel plate capacitor. The capacitance can also be written as:
C=(ΕS*εO)/d (Eq. 4)
where, ε0, is the permittivity in a vacuum (8.85418*10−14 F/cm) and, εS, is the permittivity of a given semiconductor material (F/cm). The electric field between the theoretical plates of the capacitor terminates at the negative charges in the cylindrical channel 606 just beyond the dielectric material layer 612 between the annular gate 610 and the cylindrical channel 606. As long as VDS 630 is greater than zero, the voltage across the inversion region 632 increases with the distance from the source 608. Therefore, the voltage at any point along the annular gate 610 can be given as V(x), where x represents the distance from the source 608. It follows that the charge, Q(x), can be rewritten as a function of distance:
Q(x)=−C*W*[VGS−VTV(x)] (Eq. 5)
Given the drain current, ID, is:
ID=σ*E*A (Eq. 6)
where, E, is the electric field, A, is the cross sectional area of the channel 606, σ, is the conductivity defined as:
σ=n*q*μ (Eq. 7)
and where, μ, is the electron mobility of a given material and, q, is the elementary charge value of 1.60218*10−19 Coulombs. Given the following two equations:
n*q=−Q(x)/A (Eq. 8)
E=dV(x)/dx (Eq. 9)
The current, ID, can be rewritten as:
ID=[μ*C*W[VGS−VT−V(x)]]dV(x)/dx (Eq. 10)
The inversion region 632 is present when VGS−VDS is greater than or equal to VT. Integrating Eq. 10 over the length, L, for ID and from 0 to VDS for the right hand side of Eq. 10 gives:
ID=(μ*C*)/(2*L)*[2*(VGS−VT)*VDS−VDS2] (Eq. 11)
Pinch off and saturation occurs when VGS−VDS is equal to VT and the boundary is defined by:
ID=(μ*C*W)/(2*L)*VDS (Eq. 12)
and in the saturation region VDS is greater than VGS−VT, therefore:
ID=(μ*C*W)/(2*L)*(VGS−VT)=k*(VGS−VT) (Eq. 13)
Therefore, for the present invention:
k=(μ*C*2πR)/(2*L)=(μ*C*πR)/L (Eq. 14)
Thus, for an instance of the present invention with a given VT, the current, ID 634, can be increased by, increasing the radius, R 618, of the cylindrical channel 606 of the device 600. The current, ID 634, can also be increased by decreasing the length, L 616. The mobility, μ, can also be increased to increase the current, ID 634, by utilizing doped polymers with higher mobility values. Increasing the capacitance, C, can also increase the current, ID 634, by decreasing the theoretical plate distance, d, and/or selecting semiconductor material with a higher permittivity value.
One skilled in the art can appreciate that any system with a means to utilize an annular gate to control current through a polymer-based material falls within the scope of the present invention. That is, any system that employs a 360 degree element emanating an electrical field to create an inversion layer in a polymer-based device is an aspect of the present invention. Thus, the geometric shape of the device can vary and still be covered by the present invention scope. In the same light, the material composition of the elements of the device can also vary.
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The present invention semiconductor devices are useful in any device requiring amplification of a signal and/or control of current. For example, the semiconductor devices of the present invention are useful in memory, computers, appliances, industrial equipment, hand-held devices, telecommunications equipment, medical equipment, research and development equipment, transportation vehicles, radar/satellite devices, and the like. Hand-held devices, and particularly hand-held electronic devices, achieve improvements in portability due to the small size and light weight of the polymer-based semiconductor devices. Examples of hand-held devices include cell phones and other two way communication devices, personal data assistants, palm pilots, pagers, notebook computers, remote controls, recorders (video and audio), radios, small televisions and web viewers, cameras, and the like.
In view of the exemplary systems shown and described above, methodologies, which may be implemented in accordance with one or more aspects of the present invention, will be better appreciated with reference to the flow diagrams of
Moreover, not all illustrated blocks may be required to implement a methodology in accordance with one or more aspects of the present invention. It is to be appreciated that the various blocks may be implemented via software, hardware a combination thereof or any other suitable means (e.g. device, system, process, component) for carrying out the functionality associated with the blocks. It is also to be appreciated that the blocks are merely to illustrate certain aspects of the present invention in a simplified form and that these aspects may be illustrated via a lesser and/or greater number of blocks.
In
The first source/drain can be deposited on a substrate in any manner suitable for transistor fabrication. This can include chemical vapor deposition (CVD) processes such as atmospheric pressure CVD (APCVD), low pressure CVD (LPCVD), plasma-enhanced CVD (PECVD), photochemical (ultraviolet) (LPCVD), vapor phase epitaxy (VPE), and metalorganic CVD (MOCVD). Additional non-CVD methods such as molecular beam epitaxy (MBE) are also acceptable.
A channel is then formed on the first source/drain 806. The channel is generally composed of a semiconductor material, such as an organic conjugated molecule(s), that can be doped to allow current control through the material. Such conjugated molecules are characterized in that they have overlapping π orbitals and that they can assume two or more resonant structures. The organic molecules may be cyclic or acyclic. Examples of conjugated organic materials include one or more of polyacetylene (cis or trans); polyphenylacetylene (cis or trans); polydiphenylacetylene; polyaniline; poly (p-phenylene vinylene); polythiophene; polyporphyrins; porphyrinic macrocycles, thiol derivatized polyporphyrins; polymetallocenes such as polyferrocenes, polyphthalocyanines; polyvinylenes; polystiroles; and the like. Additionally, the properties of the polymer can be modified by doping with a suitable dopant (e.g., salt).
The channel can be formed by a number of suitable techniques, some of which are described supra. One suitable technique that can be utilized is a spin-on technique that involves depositing a mixture of the polymer/polymer precursor and a solvent, and then removing the solvent from the first source/drain. Another technique is chemical vapor deposition (CVD) optionally including a gas reaction, gas phase deposition, and the like. CVD includes low pressure chemical vapor deposition (LPCVD), plasma enhanced chemical vapor deposition (PECVD), and high density chemical vapor deposition (HDCVD). It is not typically necessary to functionalize one or more ends of the organic molecule in order to attach it to the first source/drain.
A second source/drain is formed on the channel 808. The second source/drain is a conductive material, such as listed supra for the first source/drain, and may or may not be composed of the same material as the first source/drain. The second source/drain can be deposited on the channel employing the same methods as for the first source/drain listed supra. An annular gate is then formed such that it surrounds at least a portion of the channel and the second source/drain 810, ending the flow 812. The annular gate is generally composed of conductive material capable of producing a current controlling field in the channel such as polycrystalline silicon and the like. Similar methods as listed supra can be utilized for the formation of the gate.
Referring to
The first dielectric material layer is etched selectively 908 to allow a first source/drain to contact the substrate layer. A first source/drain material is deposited in the etched area 910. The first source/drain can be deposited on a substrate in any manner suitable for transistor fabrication. This can include chemical vapor deposition (CVD) processes such as atmospheric pressure CVD (APCVD), low pressure CVD (LPCVD), plasma-enhanced CVD (PECVD), photochemical (ultraviolet) (LPCVD), vapor phase epitaxy (VPE), and metalorganic CVD (MOCVD). Additional non-CVD methods such as molecular beam epitaxy (MBE) are also acceptable.
A second dielectric material layer is then deposited on the first dielectric material layer and the first source/drain material 912. This layer provides isolation of a first source/drain from a gate and is typically a thin layer. This layer can be deposited by the deposition methods stated supra for the first dielectric layer. Gate material is then deposited on the second dielectric material layer 914. The gate material can be deposited utilizing the methods stated supra for the first source/drain deposition. An outer boundary of a gate is patterned on the gate material with photoresist 916. The gate material is then etched 918 to form the outer boundary.
A third dielectric material layer is deposited on the second dielectric material layer and the gate material 920. This layer can be deposited by the deposition methods utilized supra for the previous dielectric material layers. An inner boundary of the gate is patterned on the third dielectric material layer with photoresist 922. A hole is then etched through the third dielectric material layer, the gate material and the second dielectric material layer 924, exposing the first source drain.
A fourth dielectric material layer is then deposited 926 over the exposed surfaces of the first source/drain, a portion of the second dielectric material layer, the gate material, and the third dielectric material layer. This layer provides isolation of a gate from a channel and is typically a thin layer. This layer can be deposited by the deposition methods utilized supra for the previous dielectric material layers. The fourth dielectric material layer is then etched to expose the first source drain material 928. This allows a channel to have electrical contact with a first source/drain. Channel material is then deposited in the hole 930.
The channel material typically does not completely fill the hole, allowing a second source/drain to be formed. The channel is generally composed of a semiconductor material, such as an organic conjugated molecule(s), that can be doped to allow current control through the material. Such conjugated molecules are characterized in that they have overlapping 7 orbitals and that they can assume two or more resonant structures. The organic molecules may be cyclic or acyclic. Examples of conjugated organic materials include one or more of polyacetylene (cis or trans); polyphenylacetylene (cis or trans); polydiphenylacetylene; polyaniline; poly (p-phenylene vinylene); polythiophene; polyporphyrins; porphyrinic macrocycles, thiol derivatized polyporphyrins; polymetallocenes such as polyferrocenes, polyphthalocyanines; polyvinylenes; polystiroles; and the like. Additionally, the properties of the polymer can be modified by doping with a suitable dopant (e.g., salt).
The channel can be formed by a number of suitable techniques, some of which are described supra. One suitable technique that can be utilized is a spin-on technique that involves depositing a mixture of the polymer/polymer precursor and a solvent, and then removing the solvent from the first source/drain. Another technique is chemical vapor deposition (CVD) optionally including a gas reaction, gas phase deposition, and the like. CVD includes low pressure chemical vapor deposition (LPCVD), plasma enhanced chemical vapor deposition (PECVD), and high density chemical vapor deposition (HDCVD). It is not typically necessary to functionalize one or more ends of the organic molecule in order to attach it to the first source/drain.
A second source/drain material is deposited in the hole 932 over the channel material, ending the flow 934. This allows for electrical contact between a second source/drain and a channel. The second source/drain material is comprised of similar conductive materials as listed for the first source/drain supra. Both source/drains can be made of the same material but do not have to be the same material. Deposition of the second source/drain material can utilize the same techniques as described for the first source/drain listed supra.
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What has been described above is one or more aspects of the present invention. It is, of course, not possible to describe every conceivable combination of components or methodologies for purposes of describing the present invention, but one of ordinary skill in the art will recognize that many further combinations and permutations of the present invention are possible. Accordingly, the present invention is intended to embrace all such alterations, modifications and variations that fall within the spirit and scope of the appended claims. In addition, while a particular feature of the invention may have been disclosed with respect to only one of several implementations, such feature may be combined with one or more other features of the other implementations as may be desired and advantageous for any given or particular application. Furthermore, to the extent that the term “includes” is used in either the detailed description or the claims, such term is intended to be inclusive in a manner similar to the term “comprising.”
