Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
  • H01P1/00—Auxiliary devices
  • H01P1/20—Frequency-selective devices, e.g. filters
  • H01P1/207—Hollow waveguide filters
  • H01P1/208—Cascaded cavities; Cascaded resonators inside a hollow waveguide structure
  • H01P1/2088—Integrated in a substrate
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
  • H01P11/00—Apparatus or processes specially adapted for manufacturing waveguides or resonators, lines, or other devices of the waveguide type
  • H01P11/001—Manufacturing waveguides or transmission lines of the waveguide type
  • H01P11/002—Manufacturing hollow waveguides
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
  • H01P11/00—Apparatus or processes specially adapted for manufacturing waveguides or resonators, lines, or other devices of the waveguide type
  • H01P11/008—Manufacturing resonators
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
  • H01P7/00—Resonators of the waveguide type
  • H01P7/06—Cavity resonators
  • H01P7/065—Cavity resonators integrated in a substrate

Definitions

• the invention relates to the field of resonant filters. More particularly, the invention relates to such resonant filters which are suitable for use in the micro and millimeter wave range, and in particular to those filters which are produced by microtechnical processes. Moreover, the invention relates to a method for producing such filters.
• Filters for separating frequencies are widely used in the art.
• electrical and optical filters are used. These filters have in general the task of limiting a voltage applied to its input wide spectrum of frequencies and / or to transform and provide at its output.
• a good filter blocks as precisely as possible only those frequencies which are outside the desired range, and allows the frequencies within the desired band to pass almost unhindered, that is, without loss.
• the loss factor and the selectivity which can be given simplified by the so-called Q-factor (also quality factor) of the filter, are therefore important distinguishing features of filters. Normally, filters with low losses and high quality are desired.
• resonance filters A frequently used physical principle for the realization of filters is based on resonance; the corresponding filters are accordingly called resonance filters. These are offered, for example, as waveguide or in coaxial design. Although such filters meet the technical requirements of high quality and low losses, but are design-related large, heavy and expensive. Furthermore, such filters are difficult to combine with the planar design conventional circuit technology.
• the cavities of such resonant filters are produced, for example, by etching from silicon wafers.
• the cavities are produced by wet etching of several individual wafers. Thereafter, the processed wafers are placed on each other, positioned exactly to each other and permanently connected. The coupling of the different layers takes place by means of openings in a metal layer covering the wafers.
• the cavities are produced by means of RIE (reactive ion etching). This method additionally allows the production of the coupling openings necessary for the coupling of individual wafers together with the cavities and in the same wafer.
• a disadvantage of the first design is the need to adjust a plurality of (for example, five or more) wafers, which must be placed and positioned exactly on top of each other.
• a disadvantage of the second type is the high cost involved in manufacturing by RIE since, despite the use of silicon as the base material, the advantage of low cost manufacturing by wet etching techniques can not be used.
• WO 2004 045018 A1 overcomes the disadvantages described above by etching cavities by means of wet-chemical methods into at least two silicon wafers and then positioning them one above the other.
• Resonant cavities are formed by cavities, which are present in both wafers.
• the coupling cavities are located in only one of the wafers. Again, precise positioning of the wafers relative to one another is necessary, especially if more than two wafers form a filter, but also because the resonant cavities consist of two halves and show the desired filter properties only when assembled accurately.
• the object of the invention is therefore to avoid the disadvantages described in the prior art, in particular a lack of integrability in planar circuit technology, too large a size, too high a weight and too high costs due to an elaborate production technique.
• the invention is intended to provide a filter with very low losses and high quality.
• a low loss, high Q-factor resonant filter which consists of two layers, of which a first layer carries only resonant cavities and a second layer exclusively coupling cavities.
• a method of making the filter of the invention is also provided.
• the invention relates to a resonant filter which is suitable for use in the micro and millimeter wave range, and can be produced by microtechnical processes. Moreover, the invention relates to a method for producing such filters, which is characterized in particular by the fact that it uses cost-effective production methods from silicon technology. In use, the filter shows low losses and high quality, its design is small and flat, and it can therefore be well integrated into the planar fabrication of microelectronic circuits.
• the resonant filter according to the invention for use in the micro and millimeter wave range consists according to a preferred embodiment of silicon. It has a first layer, which in turn has n adjacent resonance cavities, n being at least 2. Depending on the application, the number of layers can also be greater than 2.
• the resonance cavities are each separated by a partition wall. It also has a second layer with coupling cavities.
• the number of coupling cavities is advantageously at least n-1, since, for example, a coupling cavity couples two resonance cavities together, or two coupling cavities are sufficient to couple three resonance cavities together.
• the cavities of the first layer are formed exclusively as resonance cavities and the cavities of the second layer exclusively as coupling cavity (s). That is, there are no coupling cavities or parts thereof in the first layer and no resonant cavities or parts thereof in the second layer.
• the functional separation of the tasks is also reflected in the layers which can be produced separately from one another, from which, inter alia, the advantage arises that each layer can be produced with a production method optimally adapted to its task.
• Each of the resonance and coupling cavities is only one-sided and particularly preferably open to one of its outer surfaces. Accordingly owns EADS Germany GmbH 6109859
• the second layer is arranged on the first layer such that the individual resonance cavities of the first layer are interconnected by means of the coupling cavity (s) of the second layer.
• the first resonant cavity overlap with the first coupling cavity, this in turn with the second resonant cavity, and so on.
• the coupling cavities thereby bridge the partitions that are located between the resonance cavities, thus creating a continuous connection between the first and the last Resonanzkavtician.
• a particularly exact positioning of the second on the first layer is not necessary, as long as it is ensured that the connection according to the invention between the individual resonance cavities is ensured. In the present invention, this is because the electromagnetic coupling is not very sensitive to positioning tolerances due to the coupling activity.
• the filter is designed as a monolithic component, since both layers are permanently and firmly configured to be connected to one another.
• the permanent and firm connection of the layers with each other is achieved, for example, by thermo-compression bonding of the layers.
• the permanent and hermetic bonding of the layers by anodic bonding, direct silicon bonding, glass-frit bonding, low-temperature bonding or by adhesive bonding, for example, with adhesive or photoresist can take place. If at least one of the layers consists of a material other than silicon, for example of glass, plastic or ceramic, the permanent and hermetic bonding of the layers is adapted to the type of bonding surfaces.
• the filter also has means for coupling and decoupling the signal to be filtered.
• these are in the form of MSLs (microstrip Hnes).
• MSLs microstrip Hnes
• the MSLs have a width in the EADS Germany GmbH 6109859
• the MSLs may also be filled with a dielectric or consist of a better coupling or decoupling of the signal.
• the length of the MSL can be arbitrary.
• the geometries of the filter and in particular of the resonance cavities are preferably dimensioned such that they are designed for the use of the filter in the micro to millimeter wave range. According to another embodiment, the geometries are dimensioned so that the filter is suitable for use in areas of smaller, according to another embodiment, for use in areas of longer wavelengths. This adaptation can preferably be achieved by an enlargement or reduction and in particular an extension or shortening of the resonance cavities.
• the geometries of the resonance cavities are designed such that they can be changed, as a result of which the operating wavelength range likewise becomes variable. In this way, the filter can be adapted to different tasks without having to replace it.
• the filter is configured tunable.
• Such structures may be ferroelectric tuning diodes or capacitance diodes whose capacitance is tunable, for example, by applying a voltage and / or changing the temperature.
• Other means of tuning include components having one or more integrated capacitors whose capacitances may be changed, for example by electro-optic and / or thermo-optic modifications of existing polymers, or by the fact that capacitors consist of a fixed and a movable part, for example of a membrane or a Strips that face each other and are mutually insulated, wherein the displacement of the movable part is electrostatically, piezoelectrically and / or thermally actuated.
• Still other means for tuning the filter include stubs balanced by laser beam-induced material changes.
• At least one of the layers of the filter may be made of a material such as glass, plastic and ceramic instead of silicon.
• a material such as glass, plastic and ceramic instead of silicon.
• the use of a material other than silicon may be useful or necessary.
• the first layer has a thickness in the range of 1200 microns and the second layer has a thickness in the range of 200 microns.
• both layers may be the same thickness.
• both layers may originally consist of a layer which, after the introduction of the corresponding structures (in particular of the cavities) into EADS Germany GmbH 6109859
• the resonant filter accordingly has, in a first, thicker layer, two resonant cavities with a rectangular outline and a trapezoidal cross-section, and also a dividing wall which is arranged so as to separate both resonant cavities. Moreover, it has a coupling cavity arranged in a second, thinner layer and likewise rectangular, but preferably smaller, with a trapezoidal cross-section.
• the lateral dimensions of the coupling cavity are at least so great that it is at least a few micrometers larger than the thickness of the dividing wall.
• the coupling activity is typically about 100 to 500 micrometers beyond the partition.
• the second layer and the first layer are designed such that they can be laid over one another in such a way that the coupling cavity, if it is arranged above the dividing wall, surmounts it symmetrically on both sides in the direction of the resonant cavities, so that it forms a connection between the two resonant cavities.
• the filter further comprises means for coupling and uncoupling in the form of MSLs (microstrip lines), which are each arranged on the outer surface of the second layer and have a position and length, due to which each MSL at least partially above each below.
• This method preferably uses micro-technical production methods for silicon wafers, it being understood that in the case of other filter materials (in particular with regard to the materials of the first and / or second layer), a production method adapted to the material must be selected. Therefore, the embodiments mentioned in the steps enumerated here should not be construed as limiting, but rather as a guideline.
• the method comprises the following steps: EADS Germany GmbH 6109859
• connection gap is hermetically sealed, preferably using methods from microelectronics or microtechnology, such as, for example, wafer bonding or gluing.
• both layers can be masked in parallel and then treated together (eg, etched), wherein the masking and treatment can take place at least parallel in time, but can also be spatially parallelized. That means both layers EADS Germany GmbH 6109859
• the treatment of the layers takes place in particular for the production of the cavities by means of KOH or TMAH etching.
• the silicon layers are metallized and / or patterned on one or both sides before or after their combination. Since gold has high electrical conductivity, can not be oxidized, and can be used in thermocompression bonding, gold is preferably used for the very thin metallization. Other materials which also have good electrical conductivity may also be used for the metallization of the layers, such as e.g. Copper, aluminum or other metal alloys.
• the further structuring of the layers is carried out by conventional spin-coating of photoresist, exposure and subsequent dry and / or wet etching.
• the permanent bonding of the layers takes place by thermal compression bonding of the layers.
• the permanent and hermetic bonding of the layers takes place by anodic bonding, direct silicon bonding, glass-frit bonding, low-temperature bonding or by adhesive bonding, for example with adhesive or photoresists. If at least one of the layers consists of a material other than silicon, the permanent and hermetic bonding of the layers is adapted to the type of interface.
• the production of the cavities takes place by means of E ⁇ ADS Germany GmbH 6109859
• Hot stamping, injection molding or so-called nano-imprint process For small quantities and very high required accuracies, hot stamping is a particularly preferred manufacturing process. For very high volumes and less stringent accuracy requirements, injection molding can be chosen as the manufacturing process. In the case of extremely small geometries (cavity depths of one micron) and also large numbers, the nano-imprint process can preferably be selected for production, in which, for example, by means of a heated roll highly accurate structures are impressed into the plastic.
• glass preferably glass etching techniques or particularly preferably photopatternable glass can be used.
• sintering techniques can be used.
• the sole FIGURE shows a resonant filter 1 of the invention in cross-sectional view.
• the filter 1 is composed of exactly two layers, namely of a first layer 2 and a second layer 3.
• the first layer 2 comprises two resonance cavities 4. These are closed in all directions, except for a direction which lies on the surface of the first layer 2. From this direction, the cavities 4 are generated E ⁇ ADS Germany GmbH 6109859
• the second layer 3 comprises a coupling cavity 5. Also, this is closed in all directions, except for a direction which lies on the surface of the second layer 3. From this direction, the cavity 5 has been produced.
• the two layers 2 and 3 are superimposed in such a way that touch the respective surfaces in which the cavities 4 and 5 are located. Further, the two layers 2 and 3 are positioned one above the other so that the coupling cavity 5 creates a connection between the two resonance cavities 4.
• the filter 1 also comprises an input 6 and an output 7, which in each case adjoins one of the two resonance cavities 4, so that the corresponding signal to be filtered can be fed into or out of the filter.
• the input and / or the output are executed as MSLs, indicated by the thick drawn horizontal lines.

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• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Control Of Motors That Do Not Use Commutators (AREA)
• Piezo-Electric Or Mechanical Vibrators, Or Delay Or Filter Circuits (AREA)

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Publications (2)

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• 2008
  • 2008-04-08 DE DE102008017967.1A patent/DE102008017967B4/de not_active Expired - Fee Related
• 2009
  • 2009-04-07 AT AT09730813T patent/ATE535040T1/de active
  • 2009-04-07 WO PCT/EP2009/002575 patent/WO2009124730A1/fr active Application Filing
  • 2009-04-07 EP EP09730813A patent/EP2266162B1/fr not_active Not-in-force
  • 2009-04-07 US US12/937,049 patent/US8736403B2/en active Active

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