CHAMBER MOISTURE CONTROL USING NARROW OPTICAL FILTERS MEASURING EMISSION LINES

Embodiments disclosed herein include a moisture detection module. In an embodiment, the moisture detection module comprises an optical bandpass filter configured to be optically coupled to a light source, where a passband is centered at 309 nm. In an embodiment, the moisture detection module further comprises a detector optically coupled to the optical bandpass filter.

BACKGROUND

Embodiments relate to the field of semiconductor manufacturing and, in particular, modules for detecting moisture content within a chamber using narrow bandpass optical filters.

2) Description of Related Art

During a maintenance event in a semiconductor processing tool, the tool may be opened up to atmosphere. Opening the processing tool may result in moisture entering the processing tool. A high moisture level is a key issue preventing the process from starting after maintenance. For example, moisture can react with SiH4and generate dust that can cause contamination. Accordingly, sophisticated and time-consuming pump down procedures are used to make sure that any remaining moisture will not influence production processes. Typically, pump down procedures are ran for longer than the time frame expected to clear the moisture in order to ensure moisture is properly removed from the chamber. This leads to a longer period of time between a maintenance event and the return to processing production substrates.

Other techniques for monitoring moisture are available, but they are expensive. For example, measurement techniques such as the use of a mass spectrometer or infrared absorption may be used. However, these techniques either are too expensive for use in many tools, or the techniques do not operate at the low pressures present in semiconductor processing tools.

SUMMARY

Embodiments disclosed herein include a moisture detection module. In an embodiment, the moisture detection module comprises an optical bandpass filter configured to be optically coupled to a light source, where a passband is centered at 309 nm. In an embodiment, the moisture detection module further comprises a detector optically coupled to the optical bandpass filter.

Embodiments disclosed herein further comprise a semiconductor processing tool. In an embodiment, the tool comprises a chamber, and a viewport through a wall of the chamber. In an embodiment, a detection module is optically coupled to the viewport. In an embodiment, the detection module comprises an optical bandpass filter with a passband that is up to 10 nm and a detector optically coupled to the optical bandpass filter.

Embodiments disclosed herein also comprise a method for detecting moisture in a chamber. In an embodiment, the method comprises initiating a plasma in the chamber, and passing electromagnetic radiation through a port in the chamber. In an embodiment, the method further comprises filtering the electromagnetic radiation with a bandpass filter with a passband that is 10 nm wide or smaller, and detecting the filtered electromagnetic radiation with a photodiode.

DETAILED DESCRIPTION

Systems described herein include modules for detecting moisture content within a chamber using narrow bandpass optical filters. In the following description, numerous specific details are set forth in order to provide a thorough understanding of embodiments. It will be apparent to one skilled in the art that embodiments may be practiced without these specific details. In other instances, well-known aspects are not described in detail in order to not unnecessarily obscure embodiments. Furthermore, it is to be understood that the various embodiments shown in the accompanying drawings are illustrative representations and are not necessarily drawn to scale.

Maintenance events for semiconductor processing tools are expensive processes. This is because the chamber is often opened up to atmosphere (e.g., during a cleaning process). Opening the chamber to atmospheric conditions often results in moisture being introduced to the chamber. Moisture in the chamber can negatively impact processing of wafers or substrates. For example, the moisture can interact with SiH4and generate dusts that can contaminate wafers or substrates. Processes, such as a pump down, are used in order to clear the moisture from the chamber.

Determining when the moisture is adequately cleared is not a simple process. For example, measurement techniques such as the use of a mass spectrometer or infrared absorption may be used. However, these techniques either are too expensive for use in many tools, or the techniques do not operate at the low pressures present in semiconductor processing tools. Therefore, the pump down process is typically run for durations that are longer than otherwise necessary in order to ensure that the moisture is removed. This longer duration results in more down time, and further increases the expense of running a maintenance event.

Accordingly, embodiments disclosed herein include a moisture detection tool that can be used in combination with the semiconductor processing tool. In an embodiment a light source within the chamber (e.g., a plasma) may be passed through a narrow bandpass filter. The bandpass filter may be centered at a wavelength that is known to correspond with moisture. For example, it has been shown that the wavelength of 309 nm belongs to OH, which is generated by cracking the water molecule. The intensity of this feature can be used as an indicator for the moisture content in the semiconductor processing tool.

The use of a narrow bandpass filter effectively filters out other wavelengths and provides a simple optical signal for processing. For example, the detector may be a simple detector compared to expensive spectrometer solutions. In a particular embodiment, the detector may be a photodiode. Since the other wavelengths are filtered out, the intensity detected by the photodiode can be directly correlated to the moisture content within the semiconductor processing tool.

In yet another embodiments, additional bandpass filters may be used to detect other wavelengths of interest. For example, nitrogen intensity, oxygen intensity, or the like may be detected by setting up a second bandpass filter and a second detector. In some embodiments, a reference signal may also be used. The references signal may be detected by a detector without a bandpass filter between the light source and the detector.

Embodiments disclosed herein may also include various architectures that can be used to improve signal propagation. For example, one or more lenses may be used to focus electromagnetic radiation. Also, fiber optic cables may be used in some embodiments.

Further, embodiments disclosed herein may be used in chambers that do not include a dedicated light source (e.g., a plasma). For example, transfer chambers, load locks, and the like may include sensor solutions. In a particular embodiment, an antechamber may be fluidically coupled to the main chamber. The antechamber may include functionality for forming a plasma. This plasma in the antechamber can be used for moisture detection similar to embodiments described in greater detail above.

Referring now toFIG.1A, a graph of the spectrum of a plasma in a semiconductor processing tool is shown, in accordance with an embodiment. The spectrum may include peaks that indicate the presence of one or more different elements in the chamber. For example, peaks inFIG.1Amay correspond to nitrogen in some embodiments. More particularly, the side peak or shoulder110may correspond to moisture within the chamber. The shoulder110may represent the presence of OH in the chamber, which is generated by the cracking of a water molecule. The shoulder110may be centered at a wavelength of around 309 nm. As such, the increase or the decrease of the intensity of the shoulder110can be used in order to detect the moisture content within the chamber.

However, looking at the entire spectrum results in large amounts of data and complex systems. For example, the entire spectrum can be provided by a spectrometer tool, or the like. Unfortunately, spectrometers and other similar sensing tools are expensive, and may not be cost effectively integrated with a semiconductor processing tool. Further, in cluster tool architectures, each chamber may need its own moisture detection setup. For larger cluster tools, this added functionality quickly increases the cost and complexity of the cluster tool.

Accordingly, embodiments disclosed herein include narrow bandpass filters in order to filter the spectrum to provide only the regions of importance. An example of such a bandpass filter112is shown inFIG.1B. InFIG.1B, the shaded regions are regions of the spectrum that are filtered out. As shown, the bandpass filter112is centered around the wavelength of interest (e.g., 309 nm for the detection of OH). Though, it is to be appreciated that other wavelengths of interest may also be used in some embodiments. The bandpass filter112may have a passband that is approximately 10 nm or less, approximately 5 nm or less, or approximately 1 nm or less. In an embodiment, a full width at half maximum (FWHM) may range from 1 nm to 20 nm. For example, the FWHM is 1 nm, 2 nm, 4 nm, or 10 nm. Due to the narrow passband, a relatively simple detector may be used to determine moisture level. For example, the detector may be a simple photodiode. Since all other wavelengths are filtered out, the intensity detected by the photodiode can be attributed to the wavelength of interest.

Referring now toFIG.1C, a graph of the filtered spectrum is shown, in accordance with an additional embodiment. As shown, multiple bandpass filters are included. For example, a first bandpass filter112may be provided for OH at 309 nm, and a second bandpass filter114may be provided at a different wavelength. For example, the bandpass filter114may be centered at 335 nm. 335 nm may correspond to nitrogen in some embodiments. The first bandpass filter112and the second bandpass filter114may have passbands with a similar width (e.g., 5 nm or less). In other embodiments, the passband of the first bandpass filter112may be wider or narrower than the passband of the second bandpass filter114. While two bandpass filters112and114are shown, it is to be appreciated that any number of bandpass filters can be used to provide readings of different portions of the spectrum. For example, a bandpass filter may be centered at 777 nm in order to detect oxygen content. More generally, bandpass filters can be used to detect air leaks (e.g., O2or N2). For example, bandpass filters can be centered at 244.8 nm, 315.93 nm, 337.13 nm, 357.69 nm, 375.54 nm, 380.49 nm, 399.84 nm, 639.47 nm, 646.85 nm, 654.48 nm, 662.36 nm, 777 nm, 844 nm, 891.24 nm, or 1051.00 nm.

Due to complex interactions between gasses, the use of only bandpass filters may not be enough to determine concentrations of various elements. For example, if clearly separated lines are not present, a more complex algorithm can be used to calculate individual intensities based on several overlapping lines. Possible calculation options may include solving a system of equations, or a calculation based on previously measured characteristic curves.

Referring now toFIG.2A, a cross-sectional illustration of a semiconductor processing tool200is shown, in accordance with an embodiment. In an embodiment, the semiconductor processing tool200may comprise a chamber201. The chamber201may be suitable for supporting sub-atmospheric pressures. That is, the chamber201may be a vacuum chamber. In a particular embodiment, the chamber201may comprise functionality to generate a plasma205within the chamber201.

In an embodiment, the chamber201may include a viewport215. The viewport215may be made of a material that is transparent to the wavelengths of electromagnetic radiation of interest. In a particular embodiment, the viewport215may comprise fused silica or the like. In an embodiment, unfiltered electromagnetic radiation217may be emitted by the plasma205and propagated out of the viewport215. For example, a set of five lines of electromagnetic radiation217are shown to indicate that the electromagnetic radiation217is unfiltered broad band electromagnetic radiation.

In an embodiment, the electromagnetic radiation217is propagated to a narrow bandpass filter220. The bandpass filter220may be similar to any of the bandpass filters described in greater detail above. For example, the bandpass filter220may have a passband with a width of 10 nm or less, 5 nm or less, or 1 nm or less. In a particular embodiment, the passband of the bandpass filter220is centered on a wavelength corresponding to the presence of moisture. For example, the bandpass filter220may be centered on a wavelength of approximately 309 nm in order to detect the presence of OH from cracked water molecules. The bandpass filter220may be any type of optical filter that can have a passband centered at a particular wavelength of electromagnetic radiation.

In an embodiment, the bandpass filter220may be optically coupled to a detector225. As shown, filtered electromagnetic radiation218propagates from the bandpass filter220to the detector225. A single line is shown for the electromagnetic radiation218in order to indicate that it is filtered compared to the wider bandwidth (more lines) of electromagnetic radiation217. In an embodiment, the detector225may be any detector suitable for converting an electromagnetic radiation intensity to an electrical signal. For example, the detector225may be a photodiode or the like. Since the electromagnetic radiation218is filtered, the intensity detected by the photodiode detector225can be correlated to the species of interest (e.g., OH or moisture).

In an embodiment, the light source (e.g., plasma205) is said to be optically coupled to the bandpass filter220, and the bandpass filter220is said to be optically coupled to the detector225. As used herein, “optically coupled” refers to two or more components that are configured to be in a position to have electromagnetic radiation propagate from one component to another component. For example, electromagnetic radiation217propagates from plasma205to the bandpass filter220, and electromagnetic radiation218propagates from the bandpass filter220to the detector225. In the illustrated embodiment, the components do not including any focusing lenses, mirrors, or the like. Though, in other embodiments, two optically coupled components may have one or more lenses and/or one or more mirrors between the two optically coupled components.

Referring now toFIG.2B, a cross-sectional illustration of a semiconductor processing tool200is shown, in accordance with an additional embodiment. In an embodiment, the semiconductor processing tool200inFIG.2Bmay be similar to the semiconductor processing tool200inFIG.2A, with the addition of a second optical path. For example, a first bandpass filter220A and a second bandpass filter220B may be provided. The first bandpass filter220A may be optically coupled to a first detector225A, and the second bandpass filter220B may be optically coupled to a second detector225B.

In an embodiment, the first bandpass filter220A may be centered at a first wavelength, and the second bandpass filter220B may be centered at a second wavelength that is different than the first wavelength. As such, two different peaks of a spectrum can be analyzed at the same time. For example, the first wavelength may be centered at 309 nm (e.g., to look for OH), and the second wavelength may be centered at 335 nm (e.g., to look for N). This provides first filtered electromagnetic radiation218A to the first detector225A and second filtered electromagnetic radiation218B to the second detector225B. While two filtering and detection sets are shown, it is to be appreciated that any number of filtering and detection sets may be used in accordance with embodiments described herein.

Referring now toFIG.2Ca cross-sectional illustration of a semiconductor processing tool200is shown, in accordance with an additional embodiment. The semiconductor processing tool200inFIG.2Cmay be substantially similar to the semiconductor processing tool200inFIG.2B, with the addition of a reference line. The use of a reference line may be used in order to calibrate the signals detected by the other detectors225A and225B. For example, a third detector225C may be directly optically coupled to the viewport215without an intervening bandpass filter. That is, electromagnetic radiation217from the plasma205may pass through the viewport215and be directly provided to the third detector225C.

The use of such a reference signal may be used in order to calibrate readings in order to account for aging of the viewport215. For example, material may be deposited onto the interior surface of the viewport215, which reduces transmission through the viewport215. When the reference signal detected by the third detector225C decreases, the other detectors can be calibrated to account for the lower transmission rates. Otherwise, without calibration, as the viewport215deteriorates (e.g., becomes dirty), the readings at the first detector225A and the second detector225B will be lower. This can lead to misreporting the moisture content within the chamber201.

Referring now toFIG.3A, a cross-sectional illustration of a semiconductor processing tool300is shown, in accordance with an additional embodiment. The semiconductor processing tool300may include a chamber301suitable for generating a plasma305. The plasma305may be optically coupled to a first detector325A and a second detector325B. For example, electromagnetic radiation317may pass through a viewport315and be provided to bandpass filters320A and320B. The filtered electromagnetic radiation318A and318B may then be provided to the detectors325A and325B, respectively.

In an embodiment, the semiconductor processing tool300inFIG.3Amay be substantially similar to the semiconductor processing tool200inFIG.2B, with the exception of the addition of a lens316. In an embodiment, the lens316may be provided outside of the viewport315. The lens316may improve optical coupling between the plasma305and the bandpass filters320A and320B. In some embodiments, lenses (not shown) may also be provided on the bandpass filters320A and320B in order to improve optical coupling with the detectors325A and325B, respectively. Additionally, one or more mirrors may be provided along the optical paths between the plasma305and the detectors325A and325B.

Referring now toFIG.3B, a cross-sectional illustration of a semiconductor processing tool300is shown, in accordance with an embodiment. The semiconductor processing tool300inFIG.3Bmay be substantially similar to semiconductor processing tool300inFIG.3A, with the exception of the lens316. Instead of providing a single lens316between the viewport315and the bandpass filters320A and320B, a first lens316A is provided between the viewport315and the bandpass filter320A, and a second lens316B is provided between the viewport315and the bandpass filter320B. Such a configuration may lead to improved coupling between the plasma305and the bandpass filters320A and320B than when a single lens316is used.

Referring now toFIG.4, a cross-sectional illustration of a semiconductor processing tool400is shown, in accordance with an embodiment. The semiconductor processing tool400may comprise a chamber401suitable for forming a plasma405. In an embodiment, the plasma405is optically coupled to a first detector425A and a second detector425B. A first bandpass filter420A may be provided between the plasma405and the first detector425A. A second bandpass filter420B may be provided between the plasma405and the second detector425B. In an embodiment, the bandpass filters420A and420B may be similar to any of the bandpass filters described in greater detail above.

In an embodiment, the plasma405may emit electromagnetic radiation that passes through a viewport415. The electromagnetic radiation may be optically coupled to a first fiber optic cable421. For example, a lens416A or416B may provide optical coupling into the first fiber optic cables421. The first fiber optic cables421propagate the electromagnetic radiation to the bandpass filters420A and420B. After being filtered, the electromagnetic radiation is propagated to the detectors425A and425B through second fiber optic cables422. In other embodiments, the first fiber optic cables421may be omitted. Alternatively, the second fiber optic cables421may be omitted. Additional lenses may also be provided at the interfaces between the first fiber optic cables421and the bandpass filters420A and420B, at the interfaces between the bandpass filters420A and420B and the second fiber optic cables422, and/or at the interfaces between the second fiber optic cables422and the detectors425A and425B. In some embodiments, lenses416A and416B may be omitted.

In the embodiments described above, the light source is the plasma within the chamber of the semiconductor processing tool. However, embodiments are not limited to semiconductor processing tools that generate plasma. For example, moisture detection may be implemented in thermal chambers, transfer chambers, load locks, and the like. Instead of providing a plasma in the chamber, an antechamber is fluidically coupled to the interior of the chamber. A small plasma may then be struck in the antechamber, and the small plasma can be used as the light source. An example of such an embodiment is shown inFIG.5.

As shown inFIG.5, the semiconductor processing tool500comprises a chamber501and an antechamber504. The antechamber504may be fluidically coupled to the chamber501through a port503. The port503may be any standard vacuum port that is used in various processing tool architectures. In an embodiment, the antechamber504includes functionality to generate a plasma505. In an embodiment, a viewport515may be provided as part of the antechamber504. The viewport515may be a material that is transparent to electromagnetic radiation of interest. For example, the viewport515may comprise fused silica.

In an embodiment, the detection system outside of the viewport515may be similar to any of the detection architectures described in greater detail above. For example, electromagnetic radiation517may pass to bandpass filters520A and520B. The filtered electromagnetic radiation518A and518B may be propagated to detectors525A and525B, respectively. The bandpass filters520A and520B may have narrow passbands in order to isolate various peaks within the spectrum generated by the plasma505. As such, the detectors525A and525B may be simple photodiodes or the like.

Referring now toFIG.6, a cross-sectional illustration of a semiconductor processing tool600is shown, in accordance with an additional embodiment. In an embodiment, the semiconductor processing tool600may comprise a chamber601. In an embodiment, a support632, such as an electrostatic chuck (ESC) or the like, may be provided in the chamber601. The support632may secure a substrate635within the chamber601. The substrate635may be a wafer or any other standard form factor. In an embodiment, a lid631may be provided opposite from the support632. The chamber601may be configured to generate a plasma605between the lid631and the support632.

In an embodiment, a moisture detection module may be optically coupled to the chamber601. For example, electromagnetic radiation617from the plasma605may pass through a viewport615and be propagated towards a bandpass filter620. The bandpass filter620may be a narrow bandpass filter in order to isolate one of the peaks in the spectrum of the electromagnetic radiation617. For example, the passband may be centered at 309 nm in order to isolate the signal from OH that is generated from the cracking of water molecules. The filtered electromagnetic radiation618may then pass to a detector625, such as a photodiode or the like.

In the embodiment shown inFIG.6, a single filter620and detector625are shown. However, embodiments may include a semiconductor processing tool600that includes any of the moisture detection module architectures described in greater detail above. For example, two or more bandpass filters may be used with a similar number of detectors. Also, reference signals may be detected without the use of a filter. Further, any lens configuration, or optical coupling configuration (e.g., using fiber optic cables) may be included as part of the semiconductor processing tool600.

Referring now toFIG.750, a plan view illustration of a cluster tool750is shown, in accordance with an additional embodiment. The cluster tool750may include a factory interface741. The factory interface741may couple front opening unified pods (FOUPs)742to a load lock743. The load lock743couples the factory interface741to a transfer chamber744. A plurality of semiconductor processing tools700may be coupled to the transfer chamber744.

As can be appreciated, the moisture content within the different chambers can be different. As such, each of the chambers may be independently monitored. In the case of semiconductor processing tools700, the tools700may generate a plasma that can be utilized as the light source. As such, moisture detection modules745similar to any of the embodiments described above without an antechamber may be used. In an embodiment, chambers without plasma generation capabilities may be monitored with moisture detection modules740similar to those that include antechambers. For example, moisture detection modules740may be similar to the embodiment described above with respect toFIG.5. It is to be appreciated, that due to the use of low cost components and simple integration, many different moisture detection modules740and/or745may be integrated into the cluster tool750without significant cost increases.

Referring now toFIG.8, a process flow diagram of a process860for monitoring moisture content with a moisture detection module is shown, in accordance with an embodiment. In an embodiment, the process860may begin with operation861which comprises initiating a plasma in a chamber. The plasma may be initiated within the main chamber or within an antechamber fluidically coupled to the main chamber. The process860may continue with operation862, which comprises passing electromagnetic radiation through a port in the chamber. The port may be a viewport that is transparent to electromagnetic radiation emitted by the plasma. For example, the port may comprise fused silica.

In an embodiment, the process860may continue with operation863which comprises filtering the electromagnetic radiation with a bandpass filter. The bandpass filter may be similar to any of the bandpass filters described in greater detail herein. For example, the bandpass filter may be a narrow bandpass filter with a passband that is 10 nm or less, 5 nm or less, or 1 nm or less. In a particular embodiment, the bandpass filter is centered at approximately 309 nm. In an embodiment, the process860may continue with operation864, which comprises detecting the filtered electromagnetic radiation with a photodiode. The detected electromagnetic radiation can then be used in order to determine a moisture content within the chamber.

Referring now toFIG.9, a process flow diagram depicting a process970for certifying a chamber after a maintenance event is shown, in accordance with an embodiment. In an embodiment, the process970may begin with operation971, which comprises bringing a chamber online after a maintenance event. Brining the chamber online may include various operations, such as pumping down the chamber, running dummy wafers, generating a seasoning coating, or the like.

In an embodiment, the process970may continue with operation972, which comprises measuring an intensity of an emission spectrum corresponding to moisture with an optical bandpass filter and a photodiode. The emission spectrum corresponding to moisture may be centered at 309 nm in some embodiments. Though, other narrow bandwidths of the total spectrum may also be monitored for various purposes. In an embodiment, the bandpass filter and the photodiode may be provided in architectures similar to any of those described in greater detail herein. In some embodiments, a reference signal is also used in order to calibrate the system to changes in the transmittance of the viewport.

In an embodiment, the process970may continue with operation973, which comprises certifying the chamber as being ready for production use after the intensity of the emission spectrum corresponding to moisture is below a predetermined level. At the predetermined level the moisture content is low enough that it does not negatively impact the processing within the chamber.

Due to complex interactions between gasses, the use of only bandpass filters may not be enough to determine concentrations of various elements in some embodiments. For example, if clearly separated lines are not present, a more complex algorithm can be used to calculate individual intensities based on several overlapping lines. Possible calculation options may include solving a system of equations, or a calculation based on previously measured characteristic curves.

Referring now toFIG.10, a block diagram of an exemplary computer system1000of a processing tool is illustrated in accordance with an embodiment. In an embodiment, computer system1000is coupled to and controls processing in the processing tool. Computer system1000may be connected (e.g., networked) to other machines in a Local Area Network (LAN), an intranet, an extranet, or the Internet. Computer system1000may operate in the capacity of a server or a client machine in a client-server network environment, or as a peer machine in a peer-to-peer (or distributed) network environment. Computer system1000may be a personal computer (PC), a tablet PC, a set-top box (STB), a Personal Digital Assistant (PDA), a cellular telephone, a web appliance, a server, a network router, switch or bridge, or any machine capable of executing a set of instructions (sequential or otherwise) that specify actions to be taken by that machine. Further, while only a single machine is illustrated for computer system1000, the term “machine” shall also be taken to include any collection of machines (e.g., computers) that individually or jointly execute a set (or multiple sets) of instructions to perform any one or more of the methodologies described herein.

In an embodiment, computer system1000includes a system processor1002, a main memory1004(e.g., read-only memory (ROM), flash memory, dynamic random access memory (DRAM) such as synchronous DRAM (SDRAM) or Rambus DRAM (RDRAM), etc.), a static memory1006(e.g., flash memory, static random access memory (SRAM), etc.), and a secondary memory1018(e.g., a data storage device), which communicate with each other via a bus1030.

System processor1002represents one or more general-purpose processing devices such as a microsystem processor, central processing unit, or the like. More particularly, the system processor may be a complex instruction set computing (CISC) microsystem processor, reduced instruction set computing (RISC) microsystem processor, very long instruction word (VLIW) microsystem processor, a system processor implementing other instruction sets, or system processors implementing a combination of instruction sets. System processor1002may also be one or more special-purpose processing devices such as an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), a digital signal system processor (DSP), network system processor, or the like. System processor1002is configured to execute the processing logic1026for performing the operations described herein.

The computer system1000may further include a system network interface device1008for communicating with other devices or machines. The computer system1000may also include a video display unit1010(e.g., a liquid crystal display (LCD), a light emitting diode display (LED), or a cathode ray tube (CRT)), an alphanumeric input device1012(e.g., a keyboard), a cursor control device1014(e.g., a mouse), and a signal generation device1016(e.g., a speaker).

The secondary memory1018may include a machine-accessible storage medium1032(or more specifically a computer-readable storage medium) on which is stored one or more sets of instructions (e.g., software1022) embodying any one or more of the methodologies or functions described herein. The software1022may also reside, completely or at least partially, within the main memory1004and/or within the system processor1002during execution thereof by the computer system1000, the main memory1004and the system processor1002also constituting machine-readable storage media. The software1022may further be transmitted or received over a network1060via the system network interface device1008. In an embodiment, the network interface device1008may operate using RF coupling, optical coupling, acoustic coupling, or inductive coupling.

In the foregoing specification, specific exemplary embodiments have been described. It will be evident that various modifications may be made thereto without departing from the scope of the following claims. The specification and drawings are, accordingly, to be regarded in an illustrative sense rather than a restrictive sense.