KR20080031957A - Arrays of microcavity plasma devices with dielectric encapsulated electrodes - Google Patents

Abstract

The invention concerns microcavity plasma devices and arrays with thin foil metal electrodes (16, 18) protected by metal oxide dielectric (15, 19). Devices of the invention are amenable to mass production techniques, and may, for example, be fabricated by roll to roll processing. Exemplary devices of the invention are flexible. Embodiments of the invention provide for large arrays of microcavity plasma devices that can be made inexpensively. The structure of preferred embodiment microcavity plasma devices of the invention is based upon thin foils of metal that are available or can be produced in arbitrary lengths, such as on rolls. In a device of the invention, a pattern of microcavities (12) is produced in a metal foil. Oxide is subsequently grown on the foil and within the microcavities (where plasma is to be produced) to protect the microcavity and electrically isolate the foil. A second metal foil is also encapsulated with oxide and is bonded to the first encapsulated foil. For preferred embodiment microcavity plasma device arrays of the invention, no particular alignment is necessary during bonding of the two encapsulated foils. A thin glass layer (25) or vacuum packaging (34), for example, is able to seal the discharge medium into the array.

Description

ARRAYS OF MICROCAVITY PLASMA DEVICES WITH DIELECTRIC ENCAPSULATED ELECTRODES}

The present invention relates to the field of microcavity plasma devices, also known as microdischarge devices or microplasma devices.

Microcavity plasma devices have several distinct advantages over conventional discharges. Microcavity plasma devices with small physical dimensions allow operation at pressures far greater than those available for conventional macroscopic discharges. If the diameter of the cylindrical microcavity plasma device is on the order of 200 to 300 μm or less, for example, the device is operated at a high pressure above atmospheric pressure. In contrast, standard fluorescent lamps operate, for example, at pressures of typically less than 1% of atmospheric pressure. Microcavity plasma devices can be operated using different discharge media (gas or vapor, or mixtures thereof) to provide output in the visible and invisible wavelength ranges (eg, ultraviolet, vacuum, and infrared). . Microcavity plasma devices can generate light more efficiently than other conventional discharge systems and can generate light at microscopic scale.

Microcavity plasma devices developed over the last decade have proven to be very suitable for a variety of applications. An example application for a microcavity plasma device array is a display. For example, because the diameter of a single cylindrical microcavity plasma device is generally less than 400-500 μm, the device or group of devices provides the desired spatial resolution for the pixels in the display. In addition, the efficiency of microcavity plasma devices exceeds the efficiency of conventional plasma display panels such as those used in high definition televisions.

Early microcavity plasma devices had a short lifespan due to sputtering damaging the metal electrodes that were used in earlier DC-driven devices. Polycrystalline silicon and tungsten electrodes have extended lifetimes, but materials are more expensive and difficult to fabricate with current technology.

Research by the present inventors and joint researchers at the University of Illinois has led and developed the latest technology of microdischarge devices. Accordingly, practical devices have been developed that include one or more important features and structures. For example, the microcavity plasma device can be operated continuously at gas pressure above atmospheric pressure with a power load above 100 kW / cm ³ . The ability to interface plasma in the gas or vapor phase using e-h + plasma in semiconductor devices has been demonstrated. The fabrication of devices and arrays employs the MEMs process and the semiconductor process.

Following this study by the inventor and a collaborator of the University of Illinois, an example of a practical device has been developed. For example, an exemplary array of densely packed uniform microcavity plasma devices has been fabricated in accordance with semiconductor fabrication processes. An exemplary array made of silicon placed 250,000 discharge devices in an active area of 25 cm ² . The above-described array has been demonstrated in a manner similar to a plasma display panel but can be used to excite a luminous body at a luminous efficiency level that cannot be achieved using a conventional plasma display panel. Another important device is a microcavity plasma photodetector that exhibits high sensitivity. Fixing the phase of the microcavity plasma device has also been demonstrated. The device was assembled in a ceramic material system.

The following U.S. patents and patent applications describe microcavity plasma devices in accordance with the results of this research effort: Patent application publications (20050148270, microdevices and arrays; 20040160162, microdischarge devices and arrays; Microdischarge photodetectors; 20030132693, microdischarge devices and arrays with tapered microcavities) and patents (6,867,548, microdischarge devices and arrays; 6,828,730, microdischarge photodetectors; 6,815,891, microdischarges 6,695,664, microdischarge devices and arrays; 6,563,257, multilayer ceramic microdischarge devices; 6,541,915, high pressure arc lamp assisted starting devices and methods; 6,194,833, microdischarge lamps and arrays No. 6,139,384, microdischarge lamp forming process 6,027, micro-discharge lamps.

U. S. Patent No. 6,541, 915 discloses an array of microcavity plasma devices in which each device is assembled into an assembly fabricated from a material comprising a ceramic. The metal electrode is exposed to the plasma medium produced in the microcavity and between the electrodes. Further, US Pat. No. 6,194,833 discloses an array of microcavity plasma devices comprising an array in which the substrate is ceramic and silicon and the metal film is formed on the substrate. The electrodes formed on the top and bottom of the cavity as well as the silicon, ceramic or glass microcavities themselves are in contact with the plasma medium. US Patent Application Publication No. 2003/0230983 discloses a microcavity plasma device formed from a low temperature ceramic structure. The cavity is formed by placing and micromachining the laminated ceramic layer, wherein the interposed conductive layer excites the plasma medium. US 2002/0036461 discloses a hollow cathode plasma device in which electrodes are in contact with the plasma / discharge medium.

Examples of additional microcavity plasma devices include U.S. Patent Application Publication No. 2005/0269953, entitled "Phase Microdischarge Array and Microdischarge Excited by AC, RF, or Pulse". US Patent Application Publication No. 2006/0038490, entitled "Microplasma Device Excited by Interlocked Electrodes", entitled "Microdischarge Device with Enclosed Electrodes", filed Oct. 4, 2004 US patent application Ser. No. 10 / 958,174, entitled "Metal / Dielectric Multilayer Microdischarge Devices and Arrays," and US Patent Application No. 10 / 958,175, filed Oct. 4, 2004, and invention are entitled "AC Microcavity Discharge Devices and Methods Excited by US Patent Application No. 11 / 042,228.

1A is a schematic cross-sectional view of an exemplary embodiment of the microcavity plasma device array of the present invention.

1B is a schematic cross-sectional view of an exemplary embodiment of the microcavity plasma device array of the present invention.

FIG. 2 shows luminance as a function of excitation voltage in an exemplary experimental prototype of a microcavity plasma device array operated at neon with pressures of 400 Torr, 500 Torr, 600 Torr and 700 Torr.

3 is a schematic cross-sectional view of another exemplary embodiment of the microcavity plasma device array of the present invention.

FIG. 4 shows the discharge spectra of an exemplary experimental prototype of a 10 × 10 microcavity plasma device array operated in neon with a pressure of 700 Torr.

5 is near the ultraviolet generated by a prototype of a 5 × 5 microcavity plasma device array operated on a mixture of argon and N ₂ with a total pressure of 400 Torr and excited by an AC waveform of 10 kHz with an RMS voltage of 440 V. It is a figure which shows the spectrum of.

FIG. 6 is a diagram illustrating voltage and current waveforms in an experimental example of a large, flexible Al ₂ O ₃ / Al microcavity plasma device array.

7 is a cross-sectional view of an exemplary embodiment of a flat lamp having an integrated microcavity plasma device array.

8 is a dependence of the luminescence intensity on the RMS drive voltage for an experimental embodiment of an Al ₂ O ₃ / Al lamp comprising a microcavity plasma device array (according to FIG. 7) operating in neon with a pressure of 400 to 600 Torr. It is a figure which shows.

FIG. 9 is RMS in an experimental example of an Al ₂ O ₃ / Al lamp comprising a microcavity plasma device array (according to FIG. 7) operating in an Ar / 1% D ₂ gas mixture of 300, 400 and 600 Torr. It is a figure which shows the dependence of UV light emission intensity on driving voltage.

10 is a cross-sectional view of an exemplary embodiment of a flexible lamp that includes a microcavity plasma device array.

The present invention relates to microcavity plasma devices and arrays with thin foil metal electrodes protected by a metal oxide dielectric. The device of the present invention facilitates the application of mass production techniques and can be manufactured, for example, by a roll to roll process. Exemplary devices of the invention are flexible. Embodiments of the present invention provide a large array of microcavity plasma devices that can be inexpensively fabricated.

The structure and material of the microcavity plasma device as a preferred embodiment of the present invention makes it possible to implement any large array. The device of the present invention is based on a metal foil, for example, which may be available or manufactured in any length on a roll. In the device of the present invention, the metal foil having the microcavity of a predetermined pattern forms a predetermined electrode pattern. Oxides on the foil surface and oxides in the microcavity enclose the foil. The oxide protects the foil from the plasma during device operation and confines the plasma generally within the microcavity.

The second metal foil is also encapsulated with an oxide and bonded to the enclosed first foil. In a preferred embodiment of the microcavity plasma device array of the present invention, no specific alignment is required during joining the two encapsulated foils. For example, a thin glass layer can vaccum seal the array.

In the forming method of the present invention, a microcavity of a predetermined pattern is formed in the first metal foil. Subsequently, an oxide grows on the foil including the inner wall of the microcavity (plasma is formed). The oxide protects the microcavity and electrically insulates the foil. The encapsulated second metal foil is then bonded to the first metal foil and the entire array can be fabricated by a roll to roll process.

FIELD OF THE INVENTION The present invention relates to microcavity plasma devices in which thin metal foil electrodes are protected by a metal oxide dielectric and an array of these devices. The device of the present invention facilitates the application of mass production techniques and can be manufactured, for example, by a roll to roll process. Exemplary devices of the invention are flexible. Embodiments of the present invention provide a large array of microcavity plasma devices that can be inexpensively fabricated.

The structure of the preferred embodiment of the microcavity plasma device of the present invention is based on a metal foil that can be available or fabricated in any length on a roll, for example. In the device of the present invention, the microcavity of a predetermined pattern is formed in a metal foil. The oxide then grows on the foil, including inside the microcavity, to form an oxide encapsulated microcavity (plasma is formed therein). The oxide protects the microcavity and electrically insulates the foil, which foil forms the first electrode.

In a preferred embodiment a second metal foil without microcavity is also encapsulated with an oxide and bonded to the encapsulated first foil. The second metal foil forms a second electrode. In a preferred embodiment of the microcavity plasma device array of the present invention, no specific alignment is required during joining the two encapsulated foils. For example, a thin glass layer can seal the completed array.

In a preferred embodiment of the method of fabricating a microcavity plasma array, two foils of Al are both sealed with Al ₂ O ₃ and bonded to each other. Only one of the two enclosed foils has a microcavity (specific dimensions in microns are d). For example in a cylindrical microcavity, the specific dimension is the diameter of the microcavity. These microcavities may have a wide variety of shapes and may or may not extend completely through the enclosed metal foil. Experiments were performed for demonstration of the present invention using diamond shaped microcavities and cylindrical microcavities. Microcavity plasmas can be fabricated at high density, and in an exemplary experiment, surprising levels (greater than 80%) of "charge factor" (ratio of light emitting area of the array to total area) were obtained. What is the gas or vapor in the microcavity, as well as the shape of the microcavity (the geometry and depth of the cross-section) determines the luminous efficiency for the plasma structure and for particular atomic or molecular emitters. The overall thickness of the exemplary microplasma array structure of the present invention is, for example, 200 μm or less, so that the flexibility is large and cheap.

In an exemplary embodiment of the microcavity plasma device array of the present invention, two electrodes simultaneously excite all the microcavity plasma devices in the array. The second electrode may be a simple foil electrode and need not specifically align the second electrode with the first electrode during fabrication. In another exemplary embodiment of the microcavity plasma device array of the present invention, the plurality of second electrode foils is adapted to different portions of a larger first electrode having a plurality of microcavities. In this way, each part of the microplasma device array is excited. Depending on the size of the second electrode foil and the spacing between the second electrode foils, alignment problems during fabrication can also be tolerated.

Another embodiment of the invention independently processes microcavity plasma devices in an array. For example, electrode lines can be formed at both the first screen electrode and the second foil electrode by selective oxidation using simple masking or photolithography methods. After selective oxidation, a second oxidation is performed to seal the electrode, thus sealing the electrode.

The preferred embodiment will now be described with reference to the drawings. The drawings include schematic drawings rather than full scale, and those skilled in the art will fully understand with reference to the related description. Features may be exaggerated for illustrative purposes. Those skilled in the art will recognize from a preferred embodiment a broader aspect of the invention.

1A is a cross-sectional view of an exemplary embodiment of a microcavity plasma device array 10. The microcavity 12 is formed in the metal foil constituting the first electrode 16. Oxide 15 encapsulates the metal foil, including the walls of the microcavity 12. The first electrode 16 in the microcavity plasma device array 10 is a thin layer having a predetermined pattern of microcavities formed therein by any of a variety of techniques, including microdrilling, mechanical punching, laser incisions, or chemical etching. Conductive foil. Since the walls of the microcavity and the surface of the conductive foil are coated with oxide 15, with the inclusion of a thin conductive foil and the microcavity 12 (which may or may not extend completely through the foil) of the foil The metal electrode 16 is thereby protected. The oxide 15 protects the first electrode 16 from sputtering during operation, thereby extending the life of the array 10 and electrically insulating the electrode 16.

Although the microcavity does not need to extend through the metal foil 16, the nominal depth of the microcavity 12 is approximately similar to the thickness of the first electrode 16. The second electrode 18 may be a solid thin conductive foil. The second electrode 18 is also encapsulated in the oxide 19. The discharge medium (gas, vapor, or a combination thereof) is contained within the microcavity. The array may be made of any suitable material that may be fully transmissive to the emission wavelength produced by the microplasma, or that may filter the output wavelength of the microcavity plasma device array 10 to, for example, deliver luminescence only in specific spectral regions. 10) can be sealed.

Plasma (plasma discharge) will be formed in each microcavity 12. The first electrode 16 and the second electrode 18 are located at a distance from the microcavity 12 by at least the thickness of the oxide layer of each electrode. The oxide thus isolates the first electrode 16 and the second electrode 18 from the discharge medium (plasma) contained in the microcavity 12. This arrangement allows time transitions (such as AC, RF, bipolar or pulsed DC) between the electrodes 16, 18 to excite vapor or vapor phase media to generate microplasma in each microcavity 12. It allows the application of potential.

Representative conductive materials for the electrodes 16, 18 and oxides 15, 19 include metal / metal oxide materials such as Al / Al ₂ O ₃ . Another exemplary metal / metal oxide material system is Ti / TiO ₂ . Other conductive material / oxide material systems are apparent to those skilled in the art. Preferred material systems allow for the formation of the microcavity plasma device arrays of the present invention by inexpensive mass production techniques such as roll to roll processes.

Preferred fabrication methods are roll to roll processes. In a preferred method, the first electrode 16 is preformed using a microcavity having a cross section of the desired geometry. Suitable metal foils, such as Al foils, with microcavities in the form of through holes having cross sections of various geometric shapes are also commercially available, for example as may find use in the battery industry. Screen-shaped metal foils, such as Al foils, which have a microcavity and are encapsulated by an oxide and formed in advance, form an electrode pattern, and the metal foil, for example Al, can be bonded to another encapsulated oxide. The second foil can be a solid foil. In a preferred manufacturing method, no specific alignment is necessary between the two metal foils during the joining process. Thus, in the finished device, the oxides enclosing the foils forming the first electrode 16 and the second electrode 18 can be bonded together without any alignment problem. Roll to roll processes can be used. It is also possible to form microcavities in Al ₂ O ₃ coated with Al foil (the invention is incorporated herein by reference and is named “electrode-enclosed micro-discharge device” and filed Oct. 4, 2004). US Patent Application No. 10 / 958,174 and the invention entitled “Metal / Dielectric Multilayer Microdischarge Devices and Arrays” and see US Patent Application No. 10 / 958,175, filed Oct. 4, 2004); It is desirable to provide an array of microcavities encapsulated and form an oxide encapsulated electrode by providing Al (or other conductive foil material) having a cavity and then encapsulating the conductive foil with an oxide. Providing a thin conductive foil with a microcavity may be achieved by forming a cavity in the conductive foil by any of a variety of processes (laser incision, chemical etching, etc.) or obtaining a thin conductive foil with a pre-formed microcavity from a supplier. It includes one of the steps. It is possible to form microcavities of a wide variety of shapes (cross-sectional shapes) within the conductive foil.

Prototype devices according to array 10 of FIG. 1A were fabricated. An exemplary experimental prototype array had a first electrode formed from a thin metal Al foil having a microcavity that was generally diamond shaped and extended through the foil. The porous Al ₂ O ₃ membrane is grown on a first metal foil with microcavity by a multistage wet chemical process that first anodizes Al in 0.1-0.3 M oxalic acid solution at a nominal temperature of 15 ° C. After removing most of the oxide from the chromic acid / phosphate solution, a highly ordered nanopore Al ₂ O ₃ film is grown by a second anodization process in which the dimensions and spacing of the nanopores can be controlled. In the experiments, the final thickness of Al ₂ O ₃ nanoporous membranes was generally in the range of 5 to 30 μm. In general, the thickness of the Al ₂ O ₃ film inside the microcavity was kept at 5 to 20 탆 thinner than the oxide film covering the surface of the foil. The first electrode (with the microcavity array) is then bonded to the encapsulated second electrode. The second electrode was another thin metal foil without a cavity, on which the Al ₂ O ₃ film of the anode was grown. Since the second electrode is free of microcavities, no specific alignment of the first and second electrodes is required during the bonding process, thus simplifying the overall fabrication process. Exemplary experimental arrays operate with Ne / Xe gas mixtures as well as Ne gas with pressures ranging from 400 Torr to 800 Torr. After bonding two encapsulated electrodes together, the array between two sheets of glass by one of several processes, such as anode bonding or glass frit, if the rigidity of the array is acceptable for the intended application Can be sealed. If the flexibility of the array is desired, the array may be sealed between thin sheets of plastic such as those commonly used when sealing food. A thin film of material, such as SiO ₂ , may be attached to the inner surface of the polymer sealing film to minimize gas removal from the polymer to the plasma, which shortens the life of the gas. Regardless of the method of sealing, sealing the array (and thus sealing the gas inside the array) in the presence of the required gas or gas / vapor mixture or filling the array with gas after fabricating and evacuating the entire device It is possible. The latter technique can be accomplished using small diameter tubes connecting the array to the gas handling / vacuum system, which can evacuate the array and later refill it with the required gas.

An optical micrograph of an exemplary array operating at Ne gas at a pressure of 400 Torr shows that the thickness of the Al ₂ O ₃ film on the first electrode 16 is 10 μm and that the Al ₂ O ₃ film on the second electrode 18 is thick. 10 μm. These micrographs were obtained using a CCD camera and an optical microscope pointing downwards on an array where electrodes were placed on top. As observed in the micrographs, the diamond shaped microcavity has a length (from tip to tip) of 500 μm and a width of 250 μm, and under these operating conditions the plasma is observed to be located near the center of each microcavity. . The structure of the microplasma array of this embodiment results in a strong axial electric field (the axial direction refers to the direction perpendicular to the plane of the "diamond" opening of the microcavity at the center of the "diamond").

1B is a cross-sectional view of another exemplary embodiment of a microcavity plasma device, showing the devices in the array. Reference numerals in FIG. 1A are used to refer to the part of the device of FIG. 1B that is being compared. The device of FIG. 1B is similar to the device forming the array of FIG. 1A, but the second electrode has a modified structure. According to the basic concept of a capacitor, the second electrode 18 comprises three layers, two conductive layers 18a and 18b surrounding the dielectric layer 18c. Dielectric layer 18c may be Al ₂ O ₃ , for example, and the conductive layer may be Al, for example. The thickness of the dielectric layer 18c may be selected according to the capacitance required for the particular application. The thickness of the dielectric layer 18c may be several μm to several hundred μm.

FIG. 2 shows luminance as a function of excitation voltage in an exemplary experimental prototype of a microcavity plasma device array operated at neon with pressures of 400 Torr, 500 Torr, 600 Torr and 700 Torr. At all pressures, luminance generally increased as a function of voltage and luminescence was the strongest at 400 Torr due to the size of the diamond shaped microcavity. In the case of smaller microcavities, the highest luminescence will be observed at higher gas pressures.

3 is a cross-sectional view of a portion of another exemplary embodiment of a microcavity plasma device array 22. Device array 22 is similar to array 10 of FIG. 1A. Reference numerals in FIG. 1A are used to refer to the compared portion of the microcavity plasma device array. In this device 22, the pattern of the second electrode (s) 18 is determined using a microcavity having a cavity dimension that is the same as or different from the microcavity in the first electrode (s) 16. Array 22 is sealed using a thin glass or plastic layer 24. If glass or plastic is used, the overall thickness of the array can be small enough so that the array is flexible. In an exemplary embodiment, the overall thickness of the array 22 according to the array 22 of FIG. 3 or the array 10 of FIG. 1 may be less than 100 μm, and the entire device is flexible. 3 also shows an additional thin film 25 of dielectric placed on the oxides 15 and 19. In a preferred embodiment, the additional dielectric thin film 25 is glass. After the nanoporous oxide films 15 and 19 are grown, the final glass film placed on the screen improves the life and performance of the electrode. Such glass layers may be formed from solution by standard deposition processes.

4 shows the discharge spectrum in the visible range for an exemplary experimental prototype of a 10 × 10 microcavity plasma device array operated at neon with a pressure of 700 Torr. Light emission in the 500 to 800 nm wavelength range is observed because the strongest light emission is observed in this range. However, by introducing different gases and gas mixtures into the array, emission of light at a wide variety of different wavelengths can also be observed. As a second example, FIG. 5 shows the emission spectra produced in the region close to ultraviolet rays by an exemplary experimental prototype of a 5 × 5 microcavity plasma device array operated on an argon / nitrogen gas mixture having a total pressure of 400 Torr. Doing. The drive voltage for the array has an RMS voltage of 440 V and a sinusoidal AC waveform of 10 kHz. The current applied to the array is about 68 mA. Other examples of wavelengths available from these arrays include 308 nm (from OH radicals), 193, 248, 308, 351, 222 and 282 nm available from various rare gas-halogen compound molecules, H ₂ or D ₂ Continuous intervals in the 250-400 nm region available from, and 206 nm available from atomic iodine. Many different emission wavelengths can be used from different species.

FIG. 6 shows voltage and current waveforms for an exemplary experimental prototype of a large Al ₂ O ₃ / Al microcavity plasma device array. The array includes about 4800 devices with microcavities having a diamond cross section of 500 μm in length and 250 μm in width, and these waveforms are obtained when operating at Ne of 700 Torr. The IV characteristic associated with the waveform of FIG. 6 is a typical feature of the dielectric barrier discharge (DBD) where the plasma is generated by the capacitive mode.

Fig. 7 shows an example of the vacuum-sealed flat lamp 26 of the present invention. Device 26 is similar to the device of FIG. 1, with reference numerals of FIG. 1 being used to refer to the compared parts of FIG. 7. The lamp 26 uses a window 28 of glass or plastic and an unpatterned second electrode 18. Device 26 is generally not flexible, but only because of the typical thickness of the quartz window (≧ 1 mm). However, the thickness of the lamp (the thickness of the window minus the thickness) is only 170 μm, so that the lamp is flexible if the window 28 itself is flexible. The sealing material 30 ensures that the device is vacuum sealed, and although the exhaust tube 32 is shown, it may be removed or sealed at some of the manufacturing processes. Different materials may be used in the window 28 to achieve the required spectral transmission or filtering and to provide the specific emission wavelength required. As mentioned above, it may be advantageous to encapsulate Al electrodes 16 and 18 using thin glass layers in addition to Al ₂ O ₃ layers 15 and 19 during the lifetime of the array (additional layer to second electrode 18). Is omitted in FIG. 7].

The experimental device according to FIG. 7 consisted of aluminum encapsulated in an Al ₂ O ₃ encapsulation of 10 μm and a glass encapsulation of 5 μm. FIG. 8 shows the dependence of the luminescence intensity on the RMS drive voltage for an Al ₂ O ₃ / Al microcavity plasma array operating at Ne of 400 to 600 Torr. As the applied voltage increases, the luminous intensity rapidly increases.

FIG. 9 shows the ultraviolet (UV) emission intensity from a flat lamp which is square with one side 2 "and vacuum sealed according to FIG. 7 and operated with a gas mixture of 1% D ₂ and Ar. FIG. As with Ne light emission shown in Fig. 8, light emission increases with an increase in voltage and an intensity of up to 1 mW / cm ² is obtained, which is 1 mW / cm ^{2 in} the experimental example of the lamp according to FIG. It should be emphasized that it does not represent the maximum value of the output, but instead this output is the highest value obtained so far in the voltage range of the present experiment The data in Figure 9 shows Ar with a gas mixture pressure between 300 and 600 Torr. / 1% D ₂ , and the resulting luminescence from the microplasma is in the range from 250 to 400 nm.

10 shows another embodiment of a lamp incorporating a microcavity plasma device array. 10 also shows an experimental device for testing a lamp. In the device of FIG. 10, the first electrode 16 and the second electrode 18, one or both of which have a microcavity 12, are previously, for example according to FIG. 1 or 3. A metal foil screen that is formed and subsequently encapsulated in an oxide to form the microcavity plasma device array 10, which can be thin enough (a few hundred microns or less) to be flexible. The enclosed two electrodes 16, 18, either or both of which are screens, are not necessarily bonded but are generally bonded to each other using a polymer adhesive. In order to maintain a high degree of flexibility even after vacuum sealing, the array 10 is packaged in a polymer vacuum packaging 34. In the experimental embodiment, the extensions of the electrodes 16, 18 extend beyond the packaging 34 for connection to the power source / controller 36. The microcavity plasma device array 10 can be operated at atmospheric pressure (or near atmospheric pressure) so that there is only a small pressure difference (even if there is a pressure difference) between the inside and outside of the lamp, thus enabling vacuum sealing in polymer packaging. Do. Experimental examples of vacuum sealed lamps were operated at He of 745 Torr. The light emitting area of the device was 5 cm ² , and the overall thickness of the device (including packaging 34) was about 35 μm. The experimental device was able to bend at an angle of over 40 ° without damaging the lamp.

The array of the present invention has many applications. One application for an array is, for example, as a light source (backlight unit) for a liquid crystal display panel. Embodiments of the present invention provide a light, thin and distributed light source, which is preferred over current embodiments using fluorescent lamps. Distributing light from the lamp in a uniform manner across the entire display requires complex lenses. For example, the array of the invention also applies to sensing devices and detection equipment, such as chromatography devices, and to treatment with phototherapy (including photodynamic therapy). The latter includes treatment of psoriasis, actinic keratosis, and Bowen's disease or basic malignant tumor cells that require about 308 nm of ultraviolet light. Inexpensive arrays, now sealed in glass or plastic, provide patients with the opportunity to dispose of the array after being treated in an environment other than the clinic (i.e. at home). These arrays are also well suited for photocuring polymers that require ultraviolet light emission.

While various embodiments of the invention have been shown and described, it should be understood that other variations, alternatives, or alternatives will be apparent to those skilled in the art. Such modifications, substitutions or alternatives can be made without departing from the spirit and scope of the invention, which is determined from the appended claims.

Various features of the invention are as defined in the following claims.

Claims (20)

A first electrode 16 including a plurality of microcavities 12 therein and a thin conductive foil encapsulated in the oxide 15; A second electrode 18 which is a thin conductive foil encapsulated in oxide 19; And Receiving layers 24, 28, 34 containing discharge medium in the microcavity Including, And the first electrode and the second electrode are bonded to each other but contact between these electrodes is prevented by an oxide. 2. The microcavity plasma device array of claim 1, wherein said first electrode, said second electrode, oxide, and receiving layer are thin enough to make said array flexible. The microcavity plasma device array of claim 1, wherein the first electrode and the second electrode are made of aluminum foil, and the oxide is made of aluminum oxide. The microcavity plasma device array of claim 1, wherein the first electrode and the second electrode are made of titanium foil, and the oxide is made of titanium oxide. The microcavity plasma device array of claim 1, wherein the receiving layer is substantially transparent in the visible spectrum. The microcavity plasma device array of claim 1, wherein the receiving layer comprises an optical filter. 2. The microcavity plasma device array of claim 1, wherein each of the first and second electrodes comprises a microcavity. The microcavity plasma device array of claim 1, wherein the receiving layer comprises glass. 2. The microcavity plasma device array of claim 1, wherein said receiving layer comprises a polymer vacuum packaging and said discharge medium is received in an array at a pressure close to atmospheric pressure. The microcavity plasma device array of claim 1, further comprising a thin film of a first dielectric on the oxide of the first electrode. 11. The microcavity plasma device array of claim 10, further comprising a thin film (25) of a second dielectric on the oxide of the second electrode. 12. The microcavity plasma device array of claim 11, wherein the thin film of the first dielectric and the thin film of the second dielectric are made of glass. 2. The microcavity plasma device array of claim 1, wherein said second electrode comprises capacitors (18a, 18b, 18c). Encapsulating a first conductive foil with a plurality of microcavities in the oxide to form a first electrode; Encapsulating a second conductive foil in the oxide to form a second electrode; Bonding the first electrode and the second electrode together; And Receiving a discharge medium in an array Method of manufacturing a microcavity plasma device array comprising a. 15. The method of claim 14, wherein the method consisting of the steps is a roll to roll process. The method of claim 14, wherein the first conductive foil and the second conductive foil are made of aluminum foil, and the oxide is made of aluminum oxide. 15. The method of claim 14, wherein the first conductive foil and the second conductive foil are made of titanium foil and the oxide is made of titanium oxide. 15. The method of claim 14, wherein the oxides of the first conductive foil and the second conductive foil are further coated using a thin film of dielectric. 19. The method of claim 18, wherein the dielectric thin film is made of glass. 15. The method of claim 14, wherein the step of receiving the discharge medium comprises vacuum packaging the first electrode and the second electrode to receive the discharge medium in the array.