WO2012049373A1

WO2012049373A1 - Changing operation frequency in a lbaw filter

Info

Publication number: WO2012049373A1
Application number: PCT/FI2011/050893
Authority: WO
Inventors: Johanna Meltaus; Tuomas Pensala; Markku Ylilammi
Original assignee: Teknologian Tutkimuskeskus Vtt
Priority date: 2010-10-14
Filing date: 2011-10-14
Publication date: 2012-04-19
Also published as: FI20106059A; FI20106059A0

Abstract

In laterally coupled BAW (LBAW) filters, the center frequency is generally determined by the thin film stack thickness. However, it is possible to affect the operation frequency with the lateral dimensions of electrodes (13), e.g., electrode width (12). Therefore, it is possible to manufacture LBAW components on a single wafer having a general thickness with electrodes (13) of a different width (12). When the different electode widths (12) are based on the specific local thickness of each element and/or the desired center frequency it is possible to manufacture components on a single wafer with accurate and optionally predetermined different center frequencies.

Description

CHANGING OPERATION FREQUENCY IN A LBAW FILTER

FIELD OF INVENTION

The present invention relates generally to a novel method for producing laterally coupled Bulk Acoustic Wave filters (LBAW) as well as novel LBAW components and devices.

BACKGROUND OF INVENTION

Bulk Acoustic Wave (BAW) filters have long been used in electronic applications. Each BAW filer is designed to have a specific center frequency at which it is to operate. In standard applications, the center frequency of a BAW filter is determined by film thicknesses in the thin- film stack of filter.

BAW filters are normally manufactured on wafers having a plurality of similar filters. Therefore in theory, a single wafer has a certain thin film stack with certain thicknesses of thin film layers and produces a plurality of BAW filters with the same center frequency. However, in practice there are often thickness variations in layer thicknesses and overall thickness across a single wafer which produces multiple BAW filters with slightly different center frequencies.

In practice, the variation of center frequencies between multiple BAW filters cut from the same wafer is directly based on the manufacturing tolerances of the manufacturing process and device. Additionally, the variation between the filters is not controllable, i.e. it is impossible to utilize the known manufacturing tolerances to purposefully produce BAW filters on the same wafer with different desired center frequencies based on the film thicknesses of the thin film stack.

In certain applications, such as filter banks, filters operating at different center frequencies are needed. As described above, in BAW components since the film thickness determines the operation frequency, components with different frequencies need to be fabricated on different wafers.

Additionally, it is often necessary to adjust the operation frequency of a filter, or resonator, to compensate for the frequency shift due to thickness variations over the wafer. This is commonly done by adding or removing material from the component. If not compensated for, the frequency shift due to thickness variations reduces yield.

Typically when tuning BAW resonators and filters, a mass load is added onto the resonator, for example by depositing material on the electrodes. This often changes the dispersion properties, i.e. acoustic properties of the component and reduces the electromechanical coupling. Furthermore, because the film thickness varies from one device to another, the amount of added material must be determined through the use of electrical measurements, deposited or removed individually for each component. This process is both slow and expensive. Having to make multiple components on multiple wafers, as well as often needing to modify manufactured components based on manufacturing variations is expensive, time consuming and generally undesirable. Therefore, there exists a need in the art to have a method and device for making BAW components having different predetermined center frequencies on a single wafer. Additionally, there exists a need in the art to have a method and device for compensating for manufacturing variations in film thickness during the manufacturing process.

SUMMARY OF THE INVENTION

It is an object of the present invention to affect the actual frequency response of elements through electrode widths, gaps between electrodes or combinations thereof.

It is an aspect of embodiments of the present invention to provide at least a method, device for making or product which allows for manufacturing an element or a plurality of elements having multiple frequency responses on a single wafer.

It is an aspect of embodiments of the present invention to provide at least a method, device for making or product which is capable of compensation for variations in component thin- film layer thicknesses during manufacturing.

The objects and aspects of embodiments of the present invention are generally achieved by varying the dimensions and arrangement of electrodes during the manufacturing process. Therefore, it is possible to at least partially utilize current manufacturing processes and machinery while providing a product which overcomes at least some of the deficiencies in the prior art.

As an example, in laterally coupled BAW filters (LBAW), the center frequency is generally determined by the layer thicknesses in the thin film stack. However, it is possible to affect the operation frequency with the lateral dimensions of electrodes, e.g. electrode width. Therefore, it is possible to manufacture LBAW components on a single wafer having a layer stack with general thickness and electrodes of different width.

When the different electrode widths are based on the specific local thickness of each element and/or the desired center frequency it is possible to manufacture components on a single wafer with accurate and potentially predetermined different center frequencies.

A method of manufacturing one or more first elements having a first desired frequency response is stated in the characterizing portion of claim 1.

A product according to the claimed method is stated in claim 13.

The invention will now be discussed in more detail with the aid of the figures, examples and description of exemplary embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 shows a generalized schematic of a component.

Figure 2 shows simulated dispersion curves of the component used in simulations. Figure 3 shows simulated electric responses for electrodes with constant width W=8um and varying gaps (1-6).

Figure 4 shows a graph of the simulated effect of varying electrode widths on center frequency.

Figure 5 shows a graph of the measured effect of varying electrode widths on center frequency.

Figure 6 shows simulated electric responses for a filter bank according to the present invention DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

In a laterally coupled BAW filter (LBAW), adjacent resonators are coupled via an evanescent or propagating acoustic waves. In a structure, two resonance modes, even mode and higher-order odd mode, are generated and can form a bandpass response. An example of such a structure is a two finger-like electrodes structure.

The central operating frequency of the structure is mainly determined by the properties of the piezoelectric layer, the electrodes, and the structure beneath the resonator. The structure beneath the resonator can be, for example, an acoustic mirror stack or an air-gap. However, the structure beneath the resonator is usually selected based on the function or application of the structure and is fixed. Therefore, the two variables which can be modified to create a desired central operating frequency are the piezoelectric layer and the electrodes.

Regarding the piezoelectric layer, in BAW components, the operation frequency is determined by the thickness of the piezoelectric layer and the wave velocity in the material. Therefore by selecting an appropriate material and thickness it is possible to obtain a desired center operating frequency. In practice, material composition as well as local layer thickness varies based on manufacturing considerations. Therefore, an actual operating frequency can vary from the desired operating frequency based on, for example, manufacturing tolerances.

Electrodes also affect the operating frequency of BAW components. Therefore

determining factors in determining the operation frequency in BAW resonators is the thickness and material of the piezoelectric layer and the thickness and material of the electrodes. In LBAW components, which are typically composed of closely-spaced, relatively narrow electrodes, the lateral dimensions of the electrodes (electrode width) also affects the operation frequency. It is therefore possible to vary the center operating frequency of LBAW components by varying the electrode widths W of electrodes. Figure 1 shows a generalized schematic showing electrode width W and gap G. Although electrode width W affects the center frequency in LBAW components, the gap between electrodes, G, does not. This makes it possible to control or adjust the operation frequency by adjusting the lateral dimensions of the electrodes of an element such as a LBAW filter. Additionally, LBAW filters with different center frequencies can be fabricated on a single wafer without changing the film thicknesses through varying electrode widths. This leads to a simple manufacturing process and reduced costs.

Adjusting the filter frequencies is possible by either narrowing existing electrodes or fabricating electrodes with specific applicable dimension. Any known technology for narrowing existing electrodes can be used. One exemplary technology is using ion beam etching, i.e. a focused ion beam. Similarly, any known technology for fabricating electrodes can be used.

Figure 1 shows a generalized schematic of a component oriented in the x-y-z coordinate frame depicted with a length 10 extending along the y-axis. The component has two electrodes 13 supported by a piezoelectric layer 14, a lower electrode 15 and a layer structure 16 on top of a substrate 17. The LBAW component has a total thickness 18 consisting of the thicknesses of the supporting layers, the bottom electrode, the piezoelectric layer and the top electrodes. The two top electrodes 13 each have a width 12 and are separated by a gap 11. The area of top electrodes 13 will be called "active" and the areas outlying the top electrodes 13 will be called "outside".

Due to the properties of the component, a thickness-propagating (z-direction) acoustic wave u(z) and laterally propagating (x-direction) acoustic wave u(x) can be generated. Due to the properties of the laterally propagating acoustic wave u(x), it is possible to generate two resonance modes, even and odd, to form a passband response as shown by the area in the graph of Figure 1 between the dashed lines. As will be shown, the width of the passband response is affected in part by the dimensions of the gap 11 and the central location, i.e. central operating frequency, is affected in part by the width 12 of the electrodes. However, the dimensions of the gap 11 do not affect the central operating frequency of the component.

A discrete example of an LBAW component according to the present invention is described with the aid of Figures 2-4 and corresponding Tables 1 and 2. The LBAW component used in the example has a thin- film layer stack made up of several materials. Material properties for the materials used in the stack are shown in Table 1. The actual composition of the thin-film stack is shown in Table 2. Table 1: Materials Parameters Used in Simulations

Table 2: Materials and Layer Thicknesses of the Thin-Film Stack Used in

Simulations

Material Layer Thickness(nm)

Al 110

AIN 1960

Mo 300

Ti 10

Si02 1000

W 550

Si02 621

W 505

Si02 786 The graph in Figure 2 shows the dispersion curves of the structure in the simulations. In the x-axis the lateral wave number k_|| for the laterally propagating waves is shown. In the y-axis the frequency is shown. In the dispersion diagram the imaginary wave numbers, i.e. evanescent acoustic wave, are on the negative x-axis. The real wave numbers, i.e.

propagating acoustic wave, are on the positive x-axis

Curve 22 represents the active (electrode) area wave number and curve 23 represents the outside area wave number. In the LBAW component, acoustic energy is laterally trapped within the structure in the frequency range 24 in which the active area lateral wave number is real, indicating a laterally propagating wave, and the outside area lateral wave number is imaginary, indicating an evanescent lateral wave. In the trapping range the loss of acoustic energy from the device can be kept small, and standing lateral resonances can arise.

Figure 3 is a compilation of simulated electrical frequency responses of LBAW devices according to the example above, where the dimension of the gap 11 is altered in each LBAW component but where the widths of the electrodes 12 remains constant for all LBAW components. In the figure, the width W of each electrode is 8 μιη. Curves 1-6 correspond to components with gaps of 1-6 μιη respectively. The graph of Figure 3 is also representative of the simulated electrical responses expected from a LBAW filter bank.

It is clear from the graph that when all other variables are kept the same and the gap 11 between electrodes is varied that the central operating frequency remains substantially constant but the width of the passband response changes. As the gap 11 between the electrodes increases the passband narrows.

Figure 4 shows the simulated effect of electrode width W to center frequency. In this example, the gap width is a constant G=6 μιη. Frequency change vs W is -6 MHz / μιη and the total change is -30 MHz (1.3% of 1970 MHz). It can be noted from the graph that changing electrode width results in a linear corresponding change in central operating frequency.

In some applications the size of the passband response is not as important as the central frequency of the passband response. Therefore it is possible to add or remove material from existing electrodes of a component to achieve a desired central operating frequency without having to adjust the overall spacing of the electrodes. This is since the gap dimensions do not have a substantial impact on the central operating frequency. In an embodiment of the present invention the operating frequency of a plurality of manufactured components is adjusted to achieve a desired, predetermined central operating frequency. The adjustment can be done on individual components such as LB AW filters. However, there are distinct advantages when the adjustment is done on a plurality of components in sequence or at substantially the same time. An example is when a plurality of components are manufactured on a single wafer.

As discussed above, in known manufacturing methods components with a desired operating frequency are manufactured by building a piezoelectric layer and electrodes with a desired thickness and composition. The electrodes are formed beneath and on the surface of the piezoelectric layer. The design of the electrodes and piezoelectric layer is chosen to give the theoretical desired operating frequency.

However, due to variations in piezoelectric layer thickness and even composition, even when electrodes are manufactured having the perfect desired dimensions the actual operating frequency can be different than the desired operating frequency. Additionally, due to manufacturing tolerances the actual dimensions of the electrodes can vary which additionally distorts the actual operating frequency of the components.

To overcome the problems of the current processes the piezoelectric layer is manufactured with normal manufacturing techniques but the dimensions of the electrodes can be selected as other than the theoretical dimensions for the final desired operating frequency of the component. In other words, if the theoretical necessary electrode width for a given piezoelectric layer, electrode thickness and operating frequency is 4um, and it is either known or possible that there are variations in the piezoelectric layer or there are manufacturing considerations to be taken in to account, then the electrode width for manufacturing is chosen as some width other than 4um. Additionally, the gap dimensions can be taken into consideration here or they can be effectively ignored based on final product requirements.

As described above, electrode width and electrode gap have different and effectively independent effects on the frequency response of LB AW components and devices.

Therefore, one skilled in the art can focus design and manufacturing on either the electrode width or electrode gap dimensions separately. However, it is often important and within the skill of one of ordinary skill in the art to take both in to consideration. In an embodiment where material is to be removed from electrodes then an electrode width of greater than the theoretical required electrode width is chosen. If there is a desired gap dimension then the electrodes with the greater width can be manufactured with the desired gap dimension between them or with a smaller gap which will increase to, or near to, the desired gap upon removal of material of the electrodes.

In an embodiment where material is to be added to electrodes then an electrode width of less than the theoretical required electrode width is chosen. The gap dimension can be chosen with similar considerations as discussed above in context with the removal of material. Once the components have been manufactured, but with altered electrode width, or altered electrode width and gap dimensions, then a determination is made as to how much each electrode needs to be adjusted to give the desired operating frequency. This determination is made by measuring at least part of the electrical response of the electrode and/or the component as a whole. When material is determined to be removed, it can be removed with, for example, ion etching. Other methods of material removal can be used but it is generally important that the piezoelectric layer is not affected by the removal. When material is determined to be added, the component may go back through the same or tertiary electrode manufacturing process where the additional material is added in the desired location. The additional material can be added with the same or a different manufacturing technique as the original manufacturing of the electrodes.

In order to minimize costs for modifying current manufacturing processes, it is desirable to choose greater altered electrode widths that are greater enough to account for all or most of the potential variations in electrical response, but not so great that a large amount of material must be removed from every electrode. When choosing lesser altered electrode widths it is advantageous to select widths that can easily and accurately be modified by the process that is to be used to add material. Such considerations would be to select a lesser altered electrode width whose difference from the theoretical width is greater than the manufacturing considerations of the process which is to be used to add material and/or the process which is used to manufacture the electrode originally. In an example involving the frequency of a laterally coupled BAW filter (LB AW) based on a piezoelectric A1N thin film, altering electrode widths makes possible an 10 MHz / 1 μιη shift at 1920 MHz which is a 0.5% shift but with a total span of 75 MHz, which is 4% of 1920 MHz. Using the information described herein, one of ordinary skill in the art taking into consideration the material disclosed herein would be able to select appropriate altered electrode width dimensions based off of each unique application. Figure 5 shows the measured effect of electrode width on the center frequency.

By utilizing current manufacturing processes there is described herein a generally four- step method, although some steps can be repeated and others added. The steps are generally to select altered electrode width dimensions, manufacture the component with the altered electrode width dimensions, determine the amount of material to be adjusted and adjusting the altered electrode width dimensions to produce a desired response. After adjusting, the component can be re-evaluated and additional adjustments can be made if necessary. Several additional embodiments can be realized utilizing the present invention. Once a components piezoelectric layer is manufactured, such as a wafer for multiple components, the layer and/or wafer can be tested or analyzed to determine thickness and/or composition variations across the surface, layer and/or stack. Once the characteristics of the layer, or wafer, are known then it is possible to use that information to determine the correct necessary electrode dimensions.

If manufacturing considerations for the electrodes, such as tolerances, are negligible or acceptable then the necessary electrode dimensions can be used to manufacture the components without need for further adjustment. However, if manufacturing

considerations for the electrodes are to be considered, then it is possible to use both the necessary electrode dimensions and the known manufacturing considerations to choose altered electrode widths that are close to the necessary electrode dimensions to reduce the necessary material to be removed or added based on the method described above.

Other embodiments are possible by using a combined manufacturing and analyzing process. If the electrical response of the components is done continuously or iteratively during manufacturing then electrodes can be manufactured correctly based not on desired dimensions but on electrical response results. If starting with a blank, or substantially blank layer/wafer then electrodes can be manufactured by adding material as necessary until the desired electrical response is achieved. Conversely, it is possible to start with a wafer or layer completely, or substantially completely covered with an electrode material. Then material can be removed as necessary until the desired electrical response is achieved. Therefore there is no or virtually no gap present between electrodes at the beginning of the process and the gap is created/increased thereby reducing the electrode widths until the desired electrical response is achieved.

Additionally, if the variations of a layer or wafer are known then it is possible to arrange components and electrodes on the layer/wafer in such a way that the electrodes and underlying layer/wafer thickness provide a desired electrical response. For example, if one portion of a wafer is known to have a first thickness, and a second portion of a wafer is known to have a second thickness, then this can be taken in to account when determining where on the wafer to place which LBAW components. If the first thickness is conducive to an LBAW component with a first central operating frequency and the second thickness with second LBAW components with second central operating frequency, then the components can be arranged in the respective preferred locations. Concurrently, the electrode widths and/or gaps between can be manufactured and/or altered as necessary according to the embodiments described above. Often when manufacturing supporting structures, thin- film stacks, wafers, etc. while the general thickness 18 is constant, or substantially constant, the properties of individual locations across the structure vary. For example, when forming the aluminum nitrate layer in the thin- film stack of Table 2, more aluminum nitrate can form towards the edges of a wafer compared to the center of the wafer. While the overall thickness 18 of the final thin- film stack can be adjusted so that it is substantially constant, the layer thickness of the aluminum nitrate layer will be different along or near the edges when compared to at or near the center of the wafer.

As structure materials and composition affect the frequency response of elements, identically manufactured elements, i.e. elements having the same electrode widths and gaps, near the edges of the wafer will have a different frequency response compared to elements near the center as the local layer thickness of at least the aluminum nitrate layer will differ. This issue can be addressed via an embodiment of the present invention. If the electrode width, gap between or combination thereof is determined based off of actual or predicted local layer thicknesses and/or properties then it is possible to accurately and optionally repeatably produce elements which have actual frequency responses closer to or equal to their respective desired frequency responses then if they are merely determined based off of the general thickness or general structure properties. Once appropriate electrode properties, i.e. width, gap, etc., are determined then they can be manufactured using any known manufacturing techniques.

A common method of manufacturing includes producing a lithography mask

corresponding to the desired electrode properties which can be used one or more times. If for instance highly accurate elements are to be manufactured, or for any other reason, then electrode width and/or gap for one or more elements can be determined based off of the actual layer thicknesses or composition of part or all of the specific supporting structure at the specific location, or near to the specific location, where the elements are to be manufactured on the supporting structure. A lithography mask can then be produced by to manufacture the desired elements on the supporting structure.

Similarly, if general variations of a supporting structure are known, or can be assumed, then electrode properties can be determined for one or more elements based on the known or assumed variations. In some situations, such as the aluminum nitrate situation above, the general variation of the aluminum nitrate layer can be taken in to account when determining electrode properties or even element positioning, e.g. location and/or orientation. For example, if the variation is know or expected for multiple supporting structures then determined properties and/or positioning and/or lithography mask can be reused.

In some scenarios, multiple wafers are produced or provided which are to be used as substrates, supporting structures, or both for producing a plurality of the same or similar elements. One or more lithography masks can be made for the plurality of wafers using the methods described above. If the variations of each wafer are known or determined then a lithography mask can be made for each wafer. However, it more economical to create one or more lithography masks that can be used for a plurality of the wafers. When it is known, determined or can be assumed that a plurality of the wafers has similar composition then one lithography mask can be made for the plurality of like wafers. This can be known, for example, by being provided from the manufacturer. It can be determined and or assumed, for example, by selecting one or more wafers from a plurality of wafers, determining local layer thickness, compositions and/or other variations from the selected wafers and either averaging the determined values from the plurality of measured wafers or otherwise using an algorithm or formula for predicting the values of the non- measured wafers.

Variations in supporting structure composition can develop over time during production. For example, the device used to deposit a layer material can, for any number of well known reasons, over time produce a varied layer. Therefore, on the first X number of supporting structures a certain layer can be substantially even. However, after X number of supporting structures, the layer is no longer even as described with the example of the aluminum nitrate. Once the variation is sufficient to alter the frequency response of elements manufactured on the supporting structure then a method in accordance with the present invention can be utilized to produce elements with the desired frequency response.

According to an embodiment, when it is known or suspected that a characteristic, property or layer thickness has changed within a supporting structure from a previous supporting structure, a new lithography mask can be created taking in to account the new variations. Alternatively, an existing lithography mask can be altered to take in to account the new variations and/or new determined electrode properties. Similarly, other manufacturing methods can be used and corresponding modifications can be made in accordance with the present embodiment specific to the manufacturing methods.

Through the use of any of the above mentioned embodiments, or obvious variants thereof which are within the scope of the present invention, it is possible to create one or more novel products. Figure 6 is representative of one novel product, an LBAW filter bank. Because it is possible to alter the center frequency of components on a single piezoelectric layer, or wafer, it is possible to build a filter bank at one time on one common piezoelectric layer/wafer.

Figure 6 shows example electrical responses from a filter bank on a single wafer with six components each having different electrode widths W and gaps G. Similarly, it is possible to fabricate separate filters, components or combinations thereof with different frequency responses with a single process, at the same time, on the same wafer and close to each other if desired. According to an embodiment there is a method for manufacturing one or more filter banks on a single wafer, each filter bank having a plurality of elements with different central operating frequencies, the method comprising the steps of; manufacturing a wafer 14, 15 for supporting a plurality of electrodes 13, the wafer having one or more layers of piezoelectric material 14 and the wafer having a generally constant thickness 16, determining electrode width 11 for elements with each different desired central operating frequency, based on the same general thickness of the wafer, needed to obtain an element with the desired central operating frequency, and manufacturing electrodes on the wafer 14, 15 with the determined electrode widths 11. Furthermore, there is a method as described further including measuring electrical responses of the manufactured filter bank and determining any necessary adjustments of electrode width 11 to obtain the desired central operating frequencies, and adjusting the width 11 of one or more manufactured electrodes based on the determined necessary adjustments. The method can also include adjusting the electrode width includes removing material from necessary electrodes without damaging the wafer.

According to a further embodiment of the present invention there is a method for manufacturing one or more filter banks on a single wafer, each filter bank having a plurality of elements with different central operating frequencies, the method comprising the steps of; manufacturing a, or using a pre-manufactured, wafer 14, 15 for supporting a plurality of electrodes 13, the wafer having one or more layers of piezoelectric material 14 and the wafer having a generally constant thickness 16,characterized by, analyzing the wafer before manufacturing electrodes to determine at least the local thickness for the area where each of the one or more elements or the filter bank is to be manufactured, and determining electrode width 11 for elements with each different desired central operating frequency, based on the local thickness of the wafer where each element is to be manufactured, needed to obtain an element with the desired central operating frequency, and manufacturing electrodes on the wafer 14, 15 with the determined electrode widths 11 at the appropriate local area of the wafer.

The method can further include measuring electrical responses of the manufactured filter bank and determining any necessary adjustments of electrode width 11 to obtain the desired central operating frequencies, and adjusting the width 11 of one or more manufactured electrodes based on the determined necessary adjustments. According to an embodiment of the present invention is disclosed a filter bank

manufactured on a single wafer, the filter bank comprising, a substrate 15 one or more piezoelectric layers 14 supported by the substrate 15, characterized by, the total thickness 16 of the substrate 14 and one or more piezoelectric layers 14 on which electrodes are to be manufactured is generally constant, and a plurality of elements having different center operating frequencies, the elements being formed by electrodes 13 each having a predetermined width 11, wherein the electrode widths 11 of elements are based on the specific center operating frequency for each element.

The filter bank can also be characterized by, the difference between the width of at least two electrodes of different elements is greater than the manufacturing tolerance of the manufacturing process which manufactured the electrodes and/or the one or more piezoelectric layers 14 is a thin-film stack having a generally constant thickness 16 and generally constant composition across the entire filter bank.

According to an embodiment of the present invention there is a method of manufacturing one or more elements having a desired central operating frequency, the method comprising the steps of; on a supporting structure 14, 15, 16 on a substrate 17, for supporting a plurality of electrodes 13, the supporting structure having one or more layers of piezoelectric material 14 and the supporting structure having a generally constant total thickness 18, determining electrode width 11, based on the general thickness 18 of the supporting structure 14, 15, 16, needed to obtain an element with a desired central operating frequency, manufacturing electrodes on the supporting structure 14, 15, 16 with the determined electrode width 11, measuring electrical responses of the manufactured element and determining any necessary adjustments of electrode width 11 to obtain the desired central operating frequency, and adjusting the width 11 of one or more

manufactured electrodes based on the determined necessary adjustments.

The present invention is not limited to the exemplary embodiments and examples described herein. They are meant only to help describe the present invention. Further examples are described in U.S. Provisional application 61/392,955 for which the present application claims priority from and which is herein incorporated by reference in its entirety. Numerous variations in manufacturing processes, number of iterations, types of novel products and more will be recognizable to one of ordinary skill in the art without departing from the scope of the present invention.

Claims

A method of manufacturing one or more first elements having a first desired frequency response, the method comprising the steps of;

- manufacturing a supporting structure (14, 15, 16) on a substrate (17), for

supporting a plurality of electrodes (13), the supporting structure having one or more layers of piezoelectric material (14) and the supporting structure having a generally constant total thickness (18),

CHARACTERIZED by, determining electrode width (12) for each of the first elements, based on the local thickness of at least a portion of the supporting structure (14, 15, 16) at or near the location that each element is to be manufactured, which is needed to obtain an element with the desired first frequency response at said location, and

- manufacturing elements having electrodes on the supporting structure (14, 15, 16) with the determined electrode widths (12).

A method in accordance with claim 1 characterized by, determining electrode width (11) for one or more second elements, based on the local thickness of at least a portion of the supporting structure (14, 15, 16) at or near the location that each element is to be manufactured, which is needed to obtain an element with a second desired frequency response at said location, the second desired frequency response being different from the first desired frequency response.

A method in accordance with claim 1 or 2 characterized by,

- producing a lithography mask based on the determined electrode widths, and

- manufacturing the electrodes on the supporting structure using the produced lithography mask.

A method in accordance with claim 3 characterized by, the lithography mask is produced by altering an existing lithography mask based on the difference between the determined electrode widths and standard electrode widths for elements having the same desired frequency responses and supporting structure but based on the generally constant total thickness (18).

5. A method in accordance with claim 3 or 4 characterized by, the lithography mask is used for manufacturing elements on more than one supporting structures having similar composition.

6. A method in accordance with any of the preceding claims characterized by, selecting the location of each element to be manufactured based on a location having an appropriate local thickness of at least a portion of the supporting structure which is suitable to the elements desired frequency response.

7. A method in accordance with any of the preceding claims characterized by

manufacturing a plurality of elements having a plurality of desired frequency responses on the piezoelectric layer, each element comprising, at least two electrodes, each electrode having a determined electrode width, the at least two electrodes having a predetermined gap between them, and each element having a desired frequency response, wherein the electrode widths and gaps are determined based on the local thickness of at least a portion of the supporting structure (14, 15, 16) at or near the location that each element is to be manufactured, which is needed to obtain the element with a the desired frequency response at said location.

8. A method in accordance with any of the preceding claims, characterized by the supporting structure and/or substrate is a wafer and multiple different elements are to be manufactured on the wafer.

9. A method in accordance with claim 8, characterized by the wafer is pre-made.

10. A method in accordance with any of the preceding claims, characterized by at least one manufactured element is a laterally coupled bulk acoustic wave (LBAW) filter.

11. A method in accordance with any of the preceding claims, characterized by at least one manufactured element is a filter bank.

12. A method in accordance with any of the preceding claims, characterized by two or more of the manufactured elements form a filter bank.

13. A method in accordance with any of the preceding claims, characterized by at least a portion of the supporting structure being a mirror stack.

14. A method in accordance with claim 13, wherein the mirror stack is a thin-film

mirror stack.

15. A method in accordance with any of the preceding claims, wherein determining the electrode width for each of the first elements, first includes determining a local thickness of at least a portion of the supporting structure at or near the location that each element is to be manufactured.

16. A method in accordance with claim 15, wherein determining a local thickness of at least a portion of the supporting structure includes determining a local thickness of one layer of the supporting structure at said local location.

17. A method in accordance with either claim 15 or 16, wherein determining a local thickness of at least a portion of the supporting structure includes determining a local variation in the composition, deposition, thickness or combination thereof of one or more of the layers of the supporting structure at or near said local location.

18. A method in accordance with claim 17, wherein said variation is based on a

variation between the local location and the thickness of the generally constant total thickness (18).

19. A method in accordance with any of claims 15-18, wherein determining a local thickness of at least a portion of the supporting structure includes approximating a local thickness of at least one layer of the supporting structure.

20. A method in accordance with claim 19, wherein said approximation is based on known variances in the manufacturing process.

21. A method in accordance with either claim 19 or 20, wherein said approximation is based on measured variances of thicknesses in one or more locations remote from said local location.

22. A method in accordance with any of claims 15-21, wherein the determination of the local thickness is different from the generally constant total thickness at at least one local location on the supporting structure.

23. A method in accordance with claim 22, wherein said at least one local location having a different local thickness compared to the generally constant total thickness is a local location at which an electrode is to be manufactured.

24. A method in accordance with claim 23, wherein said electrode comprises a portion of said first element.

25. A method in accordance with any of claims 15-23, wherein said determination of a local thickness is a measured determination for at least one local location.

26. A method in accordance with any of claims 15-23, wherein said determination of a local thickness is approximated for at least one local location.

27. A method in accordance with any of claims 15-26, wherein said local thickness is determined prior to determining said electrode width.

28. An element manufactured by any of the preceding method claims.

29. A wafer comprising a plurality of elements manufactured by any of claims 1-27.

30. A method of manufacturing multiple elements having desired frequency responses, the method characterized by the steps of; determining the local thickness of at least a portion of one or more supporting structures (14, 15, 16) on substrates (17), the supporting structures and substrates for supporting a plurality of electrodes (13), each supporting structure having one or more layers of piezoelectric material (14) and each supporting structure having a same or similar generally constant total thickness (18), determining electrode width (11) for a first set of elements, based on the local thickness, or average of determined local thicknesses, of at least a portion of the supporting structure (14, 15, 16) at or near the location that each element is to be manufactured, which is needed to obtain an element with the desired first frequency response at said location, - producing a lithography mask based on the determined electrode widths (11) for use on more than one supporting structure, and manufacturing similar first sets of elements on the more than one supporting structures (14, 15, 16) using the produced lithography mask having the same determined electrode widths (11).

31. A method of manufacturing one or more first elements having a first desired

frequency response, the method comprising the steps of;

- manufacturing a supporting structure (14, 15, 16) on a substrate (17), for

CHARACTERIZED by, determining at least one dimension of the gap between two or more electrodes (11) for each of the first elements, based on the local thickness of at least a portion of the supporting structure (14, 15, 16) at or near the location that each element is to be manufactured, which is needed to obtain an element with the desired first frequency response at said location, and

- manufacturing elements having electrodes on the supporting structure (14, 15, 16) with the determined gap dimension (11) between said electrodes (12). 32. A method of manufacturing one or more first elements having a first desired

frequency response, the method comprising the steps of;

- manufacturing a supporting structure (14, 15, 16) on a substrate (17), for

CHARACTERIZED by, determining electrode width (12) and at least one dimension of the gap between two or more electrodes (11) for each of the first elements, based on the local thickness of at least a portion of the supporting structure (14, 15, 16) at or near the location that each element is to be manufactured, which is needed to obtain an element with the desired first frequency response at said location, and

- manufacturing elements having electrodes on the supporting structure (14, 15, 16) with the determined electrode widths (12) and determined gap dimension (11) between said electrodes (12).

33. A method in accordance with any of claims 31-32, characterized by, determining electrode width and/or gap for one or more second elements, based on the local thickness of at least a portion of the supporting structure (14, 15, 16) at or near the location that each element is to be manufactured, which is needed to obtain an element with a second desired frequency response at said location, the second desired frequency response being different from the first desired frequency response.

34. A method in accordance with any of claims 31-33 characterized by,

- producing a lithography mask based on the determined electrode widths and/or gaps, and

35. A method in accordance with any of claims 31-34 characterized by, the lithography mask is produced by altering an existing lithography mask based on the difference between the determined electrode widths and/or gaps and standard electrode widths and/or gaps for elements having the same desired frequency responses and supporting structure but based on the generally constant total thickness (18).

36. A method in accordance with any of claims 31-35 characterized by, the lithography mask is used for manufacturing elements on more than one supporting structures having similar composition.

37. A method in accordance with any of any of claims 31-36 characterized by, selecting the location of each element to be manufactured based on a location having an appropriate local thickness of at least a portion of the supporting structure which is suitable to the elements desired frequency response.

38. A method in accordance with any of claims 31-37 characterized by manufacturing a plurality of elements having a plurality of desired frequency responses on the piezoelectric layer, each element comprising, at least two electrodes, each electrode having a determined electrode width and/or gaps, the at least two electrodes having a predetermined gap between them, and each element having a desired frequency response, wherein the electrode widths and gaps are determined based on the local thickness of at least a portion of the supporting structure (14, 15, 16) at or near the location that each element is to be manufactured, which is needed to obtain the element with a the desired frequency response at said location.

39. A method in accordance with any of claims 31-38, characterized by the supporting structure and/or substrate is a wafer and multiple different elements are to be manufactured on the wafer.

40. A method in accordance with any of claims 31-39, characterized by the wafer is pre-made.

41. A method in accordance with any of claims 31-40, characterized by at least one manufactured element is a laterally coupled bulk acoustic wave (LBAW) filter.

42. A method in accordance with any of claims 31-41, characterized by at least one manufactured element is a filter bank.

43. A method in accordance with any of claims 31-42, characterized by two or more of the manufactured elements form a filter bank.

44. A method in accordance with any of claims 31-43, characterized by at least a

portion of the supporting structure being a mirror stack.

45. A method in accordance with any of claims 31-44, wherein the mirror stack is a thin- film mirror stack.

46. A method in accordance with any of claims 31-45, wherein determining the electrode width and/or gaps for each of the first elements, first includes determining a local thickness of at least a portion of the supporting structure at or near the location that each element is to be manufactured.

47. A method in accordance with any of claims 31-46, wherein determining a local thickness of at least a portion of the supporting structure includes determining a local thickness of one layer of the supporting structure at said local location.

48. A method in accordance with any of claims 31-47, wherein determining a local thickness of at least a portion of the supporting structure includes determining a local variation in the composition, deposition, thickness or combination thereof of one or more of the layers of the supporting structure at or near said local location.

49. A method in accordance with any of claims 31-48, wherein said variation is based on a variation between the local location and the thickness of the generally constant total thickness (18).

50. A method in accordance with any of claims 31-49, wherein determining a local thickness of at least a portion of the supporting structure includes approximating a local thickness of at least one layer of the supporting structure.

51. A method in accordance with any of claims 31-50, wherein said approximation is based on known variances in the manufacturing process.

52. A method in accordance with any of claims 31-51, wherein said approximation is based on measured variances of thicknesses in one or more locations remote from said local location.

53. A method in accordance with any of claims 31-52, wherein the determination of the local thickness is different from the generally constant total thickness at at least one local location on the supporting structure.

54. A method in accordance with any of claims 31-53, wherein said at least one local location having a different local thickness compared to the generally constant total thickness is a local location at which an electrode is to be manufactured.

55. A method in accordance with any of claims 31-54, wherein said electrode comprises a portion of said first element.

56. A method in accordance with any of claims 31-55, wherein said determination of a local thickness is a measured determination for at least one local location.

57. A method in accordance with any of claims 31-56, wherein said determination of a local thickness is approximated for at least one local location.

58. A method in accordance with any of claims 31-57, wherein said local thickness is determined prior to determining said electrode width and/or gap.

59. An element manufactured by any of the preceding method claims 31-58.

60. A wafer comprising a plurality of elements manufactured by any of claims 31-58.

61. A method of manufacturing one or more first elements having a first desired

frequency response, the method comprising the steps of; determining a local thickness of at least a portion of a supporting structure, said supporting structure having a generally constant total thickness, at or near the location that at least one element is to be manufactured, determining electrode width (12) for each of the first elements, based on the local thickness of at least a portion of the supporting structure (14, 15, 16) at or near the location that each element is to be manufactured, which is needed to obtain an element with the desired first frequency response at said location, and

62. A method of manufacturing one or more first elements having a first desired

frequency response, the method comprising the steps of; determining a local thickness of at least a portion of a supporting structure, said supporting structure having a generally constant total thickness, at or near the location that at least one element is to be manufactured, determining at least one dimension of the gap between two or more electrodes (11) for each of the first elements, based on the local thickness of at least a portion of the supporting structure (14, 15, 16) at or near the location that each element is to be manufactured, which is needed to obtain an element with the desired first frequency response at said location, and

- manufacturing elements having electrodes on the supporting structure (14, 15, 16) with the determined gap dimension (11) between said electrodes (12).

63. A method of manufacturing one or more first elements having a first desired

frequency response, the method comprising the steps of; determining a local thickness of at least a portion of a supporting structure, said supporting structure having a generally constant total thickness, at or near the location that at least one element is to be manufactured, determining electrode width (12) and at least one dimension of the gap between two or more electrodes (11) for each of the first elements, based on the local thickness of at least a portion of the supporting structure (14, 15, 16) at or near the location that each element is to be manufactured, which is needed to obtain an element with the desired first frequency response at said location, and

64. A method in accordance with any of claims 61-63, characterized by, determining electrode width and/or gap for one or more second elements, based on the local thickness of at least a portion of the supporting structure (14, 15, 16) at or near the location that each element is to be manufactured, which is needed to obtain an element with a second desired frequency response at said location, the second desired frequency response being different from the first desired frequency response.

65. A method in accordance with any of claims 61-64 characterized by,

- producing a lithography mask based on the determined electrode widths and/or gaps, and - manufacturing the electrodes on the supporting structure using the produced lithography mask.

66. A method in accordance with any of claims 61-65 characterized by, the lithography mask is produced by altering an existing lithography mask based on the difference between the determined electrode widths and/or gaps and standard electrode widths and/or gaps for elements having the same desired frequency responses and supporting structure but based on the generally constant total thickness (18).

67. A method in accordance with any of claims 61-66 characterized by, the lithography mask is used for manufacturing elements on more than one supporting structures having similar composition.

68. A method in accordance with any of claims 61-67 characterized by, selecting the location of each element to be manufactured based on a location having an appropriate local thickness of at least a portion of the supporting structure which is suitable to the elements desired frequency response.

69. A method in accordance with any of claims 61-68 characterized by manufacturing a plurality of elements having a plurality of desired frequency responses on the piezoelectric layer, each element comprising, at least two electrodes, each electrode having a determined electrode width and/or gaps, the at least two electrodes having a predetermined gap between them, and each element having a desired frequency response, wherein the electrode widths and gaps are determined based on the local thickness of at least a portion of the supporting structure (14, 15, 16) at or near the location that each element is to be manufactured, which is needed to obtain the element with a the desired frequency response at said location.

70. A method in accordance with any of claims 61-69, characterized by the supporting structure and/or substrate is a wafer and multiple different elements are to be manufactured on the wafer.

71. A method in accordance with any of claims 61-70, characterized by the wafer is pre-made.

72. A method in accordance with any of claims 61-71, characterized by at least one manufactured element is a laterally coupled bulk acoustic wave (LBAW) filter.

73. A method in accordance with any of claims 61-72, characterized by at least one manufactured element is a filter bank.

74. A method in accordance with any of claims 61-73, characterized by two or more of the manufactured elements form a filter bank.

75. A method in accordance with any of claims 61-74, characterized by at least a

portion of the supporting structure being a mirror stack.

76. A method in accordance with any of claims 61-75, wherein the mirror stack is a thin- film mirror stack.

77. A method in accordance with any of claims 61-76, wherein determining the

electrode width and/or gaps for each of the first elements, first includes determining a local thickness of at least a portion of the supporting structure at or near the location that each element is to be manufactured.

78. A method in accordance with any of claims 61-77, wherein determining a local thickness of at least a portion of the supporting structure includes determining a local thickness of one layer of the supporting structure at said local location.

79. A method in accordance with any of claims 61-78, wherein determining a local thickness of at least a portion of the supporting structure includes determining a local variation in the composition, deposition, thickness or combination thereof of one or more of the layers of the supporting structure at or near said local location.

80. A method in accordance with any of claims 61-79, wherein said variation is based on a variation between the local location and the thickness of the generally constant total thickness (18).

81. A method in accordance with any of claims 61-80, wherein determining a local thickness of at least a portion of the supporting structure includes approximating a local thickness of at least one layer of the supporting structure.

82. A method in accordance with any of claims 61-81, wherein said approximation is based on known variances in the manufacturing process.

83. A method in accordance with any of claims 61-82, wherein said approximation is based on measured variances of thicknesses in one or more locations remote from said local location.

84. A method in accordance with any of claims 61-83, wherein the determination of the local thickness is different from the generally constant total thickness at at least one local location on the supporting structure.

85. A method in accordance with any of claims 61-84, wherein said at least one local location having a different local thickness compared to the generally constant total thickness is a local location at which an electrode is to be manufactured.

86. A method in accordance with any of claims 61-85, wherein said electrode

comprises a portion of said first element.

87. A method in accordance with any of claims 61-86, wherein said determination of a local thickness is a measured determination for at least one local location.

88. A method in accordance with any of claims 61-87, wherein said determination of a local thickness is approximated for at least one local location.

89. A method in accordance with any of claims 61-88, wherein said local thickness is determined prior to determining said electrode width and/or gap.

90. An element manufactured by any of the preceding method claims 61-89.

91. A wafer comprising a plurality of elements manufactured by any of claims 61-89.