KR20110005232A - Bulk acoustic wave resonator - Google Patents

Abstract

According to an exemplary embodiment, the bulk acoustic wave (BAW) resonator includes a piezoelectric layer located between the upper and lower electrodes, each of the upper and lower electrodes being a high density metal. In one example, the BAW resonator further comprises a controlled thickness region comprising a material segment that is one of a low density metal segment and a dielectric segment, the material segment located adjacent to the piezoelectric layer, wherein the controlled thickness region is controlled electromechanical coupling. Has The controlled thickness area can provide reduced electromechanical coupling to the side mode. In another example, the piezoelectric layer has a disturbing texture area, the disturbing texture area can be located in the controlled thickness area of the BAW resonator, the disturbing texture area can be located at the edge of the BAW resonator, and can extend along the perimeter of the BAW resonator. have.

Description

BAB resonator and BAB resonator formation method {BULK ACOUSTIC WAVE RESONATOR}

TECHNICAL FIELD The present invention relates to the field of electronic devices, and more particularly to a bulk acoustic wave (BAW) resonator.

Due to the small footprint, low profile and high performance, the use of bulk acoustic wave (BAW) filters to provide radio frequency (RF) filtering in mobile electronic devices such as cellular phones as well as other types of electronic devices. It is increasing. The BAW filter may comprise a number of BAW resonators, each BAW resonator typically comprising a layer of piezoelectric material such as aluminum nitride sandwiched between the upper and lower electrodes. When an electric field is applied to the upper and lower electrodes of the BAW resonator, the electric field may cause the piezoelectric material layer to vibrate. Thus, the piezoelectric material can create a number of allowed modes of acoustic wave propagation, including the desired longitudinal mode. However, the excitation of undesirable energy in the mode of wave propagation with high energy loss, such as the side mode, can lead to significant energy loss in the BAW resonator, which undesirably lowers the quality factor Q of the BAW resonator.

Conventional approaches to reducing energy loss in BAW resonators include shaping the profile of the resonator so that energy is best contained and controlled in the desired longitudinal mode. In one typical profile shaping approach, in order to reduce the amount of energy excited at the loss of the wave propagation mode in the BAW resonator, a region shaped near the edge of the BAW resonator, which is a region of high energy loss, may be provided. . However, the shaped regions provided in this conventional approach may also introduce additional unwanted modes, such as side modes contained within the shaped regions that may result in energy loss, such as in a BAW resonator.

Aspects and embodiments relate to bulk acoustic wave (BAW) resonators having controlled thickness regions with reduced energy loss and / or controlled electromechanical coupling.

According to one embodiment, a BAW resonator includes a piezoelectric layer positioned between an upper and lower electrode, each of the upper and lower electrodes comprising a high density metal, and a controlled segment comprising a material segment located adjacent to the piezoelectric layer. A thickness region, wherein the controlled thickness region has a controlled electromechanical coupling, and the material segment comprises one of a low density metal segment and a dielectric segment.

In one example of a BAW resonator, the controlled thickness region provides a reduced electromechanical coupling to the side mode. In another example, the material segment is located between the upper electrode and the piezoelectric layer. The material segment may extend along the circumference of the BAW resonator. In one example, the edge of the upper electrode is self aligned with the outer edge of the material segment. In another example, the edge of the upper electrode overlaps the outer edge of the material segment. The low density metal segment may comprise a metal selected from the group consisting of aluminum and titanium. The dielectric segment may comprise a low k dielectric material. Low k dielectric material is a group consisting of porous silica, fluorinated amorphous carbon, fluoropolymer, parylene, polyarylene, ether, hydrogen silsesquioxane (HSQ), fluorinated silicon dioxide, and diamond shaped carbon Is selected from. In one example, the material segment comprises a dielectric segment, the dielectric segment is located in contact with the piezoelectric layer, and the dielectric segment is confined within the perimeter of the piezoelectric layer. In another example, the dielectric segment is located at the edge of the BAW resonator.

Another embodiment relates to a method of forming a BAW resonator, the method comprising forming a piezoelectric layer over a bottom electrode of a BAW resonator, and forming a material segment over the piezoelectric layer in a controlled thickness region of the BAW resonator The thickness region includes controlled electromechanical coupling, and forming an upper electrode of the BAW resonator over the material segment, the upper electrode comprising a high density metal, wherein forming the material segment comprises a low density metal. Forming a segment and forming a dielectric segment. In one example of the method, the controlled thickness region provides reduced electromechanical coupling to the side mode. In another example, forming the upper electrode includes forming an edge of the upper electrode simultaneously with the outer edge of the material segment.

According to another embodiment, a bulk acoustic wave (BAW) resonator has a piezoelectric layer having a disturbed texture area, the disturbing texture area being located in a controlled thickness area of the BAW resonator, and on the opposite surface of the piezoelectric layer. A lower and upper electrode positioned, the controlled thickness region having a controlled electromechanical coupling.

In one example of a BAW resonator, the controlled thickness region provides a reduced electromechanical coupling to the side mode. In another example, the controlled thickness region is located at the edge of the BAW resonator and extends along the perimeter of the BAW resonator. The controlled thickness region may comprise a material segment located over the upper electrode. In one example, the material segment is selected from the group consisting of metal and dielectric material. The outer edge of the material segment may self align with the edge of the upper electrode. In another example, the BAW resonator may further comprise a thin layer of silicon oxide that lies below the disturbing texture region and is positioned between the lower electrode and the piezoelectric layer. The disturbing texture region is located at the edge of the BAW resonator and extends along the perimeter of the BAW resonator.

According to another embodiment, a method of forming a BAW resonator, the method comprising forming a bottom electrode of a BAW resonator, and forming a piezoelectric side over the bottom electrode—the piezoelectric layer comprises a disturbing texture region; The texture region is located in a controlled thickness region of the BAW resonator, and forming an upper electrode of the BAW resonator over the piezoelectric layer, the controlled thickness region having a controlled electromechanical coupling.

In one example, the method further includes forming a material segment over the upper electrode. Forming the material segment may include forming a material segment selected from the group consisting of metal and dielectric material. The method may further comprise forming a thin layer of silicon oxide over the region of the lower electrode where the disturbing texture region is to be formed prior to forming the piezoelectric layer. In another example, the method may further comprise roughening the region of the lower electrode where the disturbing texture region is to be formed prior to forming the piezoelectric layer.

According to another embodiment, the semiconductor die includes at least one BAW resonator, wherein the at least one BAW resonator comprises a piezoelectric layer and a piezoelectric layer having a disturbed texture region located in a controlled thickness region of the BAW resonator. And a lower and upper electrode located on opposite surfaces of said controlled thickness region with controlled electromechanical coupling. In one example of a semiconductor die, the controlled thickness region provides reduced electromechanical coupling to the side mode. In another example, the controlled thickness region is located at the edge of the BAW resonator and extends along the perimeter of the BAW resonator. In another example, the controlled thickness region includes a material segment located over the upper electrode. Semiconductor dies are used within circuit boards as part of electronic systems, where electronic systems are wired or wireless communication devices, cell phones, switching devices, routers, repeaters, codecs, wired or wireless LANs, WLAN, Bluetooth enabled devices, GPS (Global) Positioning System) devices, computers, monitors, television sets, satellite set top boxes, cable modems, printers, copiers, RF transmitters, and PDAs (Personal Digital Assistants).

In addition, other features, advantages, and characteristics of these exemplary aspects and embodiments are described in detail below. In addition, the foregoing information and the following detailed description are exemplary only of various aspects and embodiments, and are intended to provide an overview and basis for understanding the nature and characteristics of the claimed aspects and embodiments. Any of the embodiments described herein can be combined with any other embodiment in any manner consistent with the objects, goals, and needs described herein, including "embodiments", "some embodiments", Reference to "another embodiment", "various embodiments", "one embodiment", etc., is not necessarily mutually exclusive, and particular features, structures, or characteristics described in connection with the embodiments are included in at least one embodiment. It is to show that it becomes. The appearances of such term herein are not necessarily all referring to the same embodiment.

Various aspects of at least one embodiment are described below with reference to the accompanying drawings, which are not drawn to scale. Technical features in the drawings, the description, or any claims are followed by reference signs, which are included solely for the purpose of enhancing identification of the drawings, detailed description, or claims. Accordingly, reference signs or omissions thereof are not intended to limit the scope of any claims element. In the drawings, each identical or nearly identical component that is illustrated in various figures is represented by a like reference numeral. For clarity, not all components are shown in all the figures. The drawings are provided for purposes of illustration and description and are not intended as a limitation of the invention. In the drawing,
1A is a cross-sectional view of an example of a bulk acoustic wave (BAW) resonator in accordance with aspects of the present invention;
FIG. 1B is a plan view of the exemplary BAW resonator of FIG.
2 is a flowchart illustrating an example of a method of manufacturing a BAW resonator in accordance with an aspect of the present invention;
3A is a cross-sectional view of another example of a bulk acoustic wave (BAW) resonator in accordance with aspects of the present invention;
3 (b) is a plan view of the exemplary BAW resonator of FIG. 3 (a),
4A is a cross-sectional view of another example of a bulk acoustic wave (BAW) resonator in accordance with aspects of the present invention;
4 (b) is a top view of the exemplary BAW resonator of FIG. 3 (a),
5 is a flowchart illustrating another exemplary method of manufacturing a BAW resonator in accordance with an aspect of the present invention.
6 is a diagram of an exemplary electronic system including an example chip or die utilizing a bulk acoustic wave (BAW) resonator in accordance with aspects of the present invention.

Aspects and embodiments of the present invention relate to bulk acoustic wave (BAW) resonators. For example, aspects and embodiments relate to BAW resonators having controlled thickness regions with controlled electromechanical coupling. Other aspects and embodiments relate to BAW resonators with reduced energy losses, as further described below.

Embodiments of the methods and apparatus described herein are not limited to the application of details of arrangement and arrangement of components disclosed in the following detailed description or shown in the accompanying drawings. The method and apparatus may be implemented in other embodiments and may be practiced or carried out in various ways. Examples of specific implementations are provided herein for purposes of illustration only and not limitation. In particular, the actions, elements, and features described in combination with any one or more embodiments are not intended to be excluded from similar roles in any other embodiments.

Also, the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. Any reference to embodiments or elements or acts of systems and methods that are referred to herein as a single can also include embodiments that include a plurality of these elements, and a plurality of embodiments or elements herein Or any reference to an action may also include embodiments that include only one element. Reference to single or plural forms is not intended to limit the presently disclosed systems, methods, components, acts or elements thereof. The use of the terms "comprising", "comprising", "having", "having" and variations thereof herein is meant to include additional items as well as the items listed thereafter and equivalents thereof. Reference to "or" may be constructed as inclusive, such that any term described using "or" includes any of one, more than one, and all of the terms described. Any reference to front and rear, left and right, top and bottom, and top and bottom is for convenience of description and limits the system and method or components thereof of the present invention to any one position or spatial orientation. It is not intended to.

Referring to FIG. 1A, a cross-sectional view of an example of a BAW resonator 100 in accordance with one embodiment of the present invention is shown. BAW resonator 100 includes a lower electrode 102, a piezoelectric layer 104, an upper electrode 106, and a material segment 108. BAW resonator 100 may further include an acoustic mirror that provides acoustic separation from the base substrate. The substrate and acoustic mirror on which the BAW resonator 100 is fabricated are not shown in FIG. 1 (a) so as not to obscure the present invention. In one embodiment, the BAW resonator 100 may be a film bulk acoustic resonator (FBAR) and may be acoustically separated from the base substrate by an air cavity. BAW resonator 100 can be used in a BAW filter and made of a semiconductor die to provide RF filtering in cell phones or other types of semiconductor devices.

As shown in FIG. 1 (a), the lower electrode 102 can be positioned, for example, over an acoustic mirror not shown in FIG. 1 (a), and may be tungsten, molybdenum, or other suitable having high density. Metal (ie, high density metal). Lower electrode 102 has a thickness 110, which may be, for example, between 500.0 kPa and 5000.0 kPa. The lower electrode 102 deposits a layer of high density metal, such as tungsten, molybdenum, on a base material layer (not shown in Figure 1 (a)) using physical vapor deposition (PVD or sputtering or other suitable deposition process). It can be formed by patterning a high density material layer.

In addition, as shown in FIG. 1A, the piezoelectric layer 104 is positioned over the lower electrode 102 and includes a disturbing texture region 109 and a non-disturbed texture region 111 and an upper surface ( 126). The seed layer (not shown in FIG. 1A) may be located between the piezoelectric layer 104 and the lower electrode 102. The piezoelectric layer 104 may include aluminum oxide (AlN) and other suitable piezoelectric materials, and has a thickness 112 that may be, for example, between 0.5 microns and 3.0 microns. The disturbing texture region 109 is located in the controlled thickness region 114 at the edge of the BAW resonator 100 and extends along the entire circumference of the BAW resonator 100. The disturbing texture area 109 has a thickness 116, which can be, for example, between 1.0 micron and 5.0 micron. In the disturbing texture region 109, the crystallinity of the piezoelectric material is disturbed to result in greatly reduced internal electromechanical coupling. The comparison field texture region 111 includes a piezoelectric material that is located adjacent to the disturbance texture region 109 and surrounded by the disturbance texture region 109 and has a conventional crystallinity, that is, a crystallinity that is not intentionally disturbed. The piezoelectric layer 104 may be formed by depositing an aluminum nitride layer over the lower electrode 102 using, for example, PVD or sputtering, CVD, or other suitable deposition process.

Prior to the formation of the piezoelectric layer 104, the surface area to be placed under the disturbing texture region 109 may be sufficiently disturbed to ensure that the texture of the piezoelectric material is disturbed when the piezoelectric layer 104 is formed. For example, a thin layer of material known for disturbing textures, such as silicon oxide, is placed over a thin seed layer (not shown in FIG. 1 (a)) in the surface region of the lower electrode 102 where the disturbing texture region 109 is to be formed. Can be deposited. As another example, an etching process or other suitable treatment may be used to roughen the surface area of the lower electrode 102 where the disturbing texture region 109 is to be formed. In one embodiment, the surface area of the layer (not shown in FIG. 1A) underlying the area of the lower electrode 102 where the material segment 108 is to be formed is roughened prior to forming the lower electrode 102. Can be. The resulting disturbance in the texture of the lower electrode 102 caused by roughening the surface area of the base layer causes the texture of the piezoelectric material to be disturbed in the disturbing texture area 109 when the piezoelectric layer 104 is formed.

In addition, as shown in FIG. 1A, the upper electrode 106 is positioned over the piezoelectric layer 104 and may include tungsten, molybdenum, or other suitable dense metal. Upper electrode 106 has a thickness 120, which may be, for example, between 500.0 kPa and 5000.0 kPa. The upper electrode 106 can be less than the width of the lower electrode 102 and has a width 122 that defines the width of the “active portion” of the BAW resonator 100. The “active portion” of BAW resonator 100 refers to the portion of piezoelectric layer 104 to which an electric field is applied to activate the resonator. In one embodiment, the upper electrode 106 and the lower electrode 102 may be approximately equal in width. Upper electrode 106 may be formed by depositing a dense metal layer, such as tungsten, molybdenum, on piezoelectric layer 104 using PVD or sputtering or other suitable deposition process. The dense metal layer can be appropriately patterned by using an appropriate etching process. In this embodiment, the edge of the upper electrode 106 can self align with the outer edge of the material segment 108 as described below.

In addition, as shown in FIG. 1A, the material segment 108 is located above the upper electrode 106 at the edge of the BAW resonator 100. The material segment 108 is also located in the controlled thickness region 114 and extends along the entire circumference of the BAW resonator 100. Material segment 108 may comprise, for example, a metal, a dielectric material, or a semiconductor material, such as a low or high density metal, and has a thickness 124 and a width 130. For example, the thickness 124 of the material segment 108 may be between 100.0 mm 3 and 3000.0 mm 3. The width of the material segment 108 may be between 1.0 micron and 5.0 micron, for example. In the embodiment of FIG. 1A, the material segment 108 has a uniform cross-sectional thickness. In other embodiments, material segment 108 may have a non-uniform cross-sectional thickness and may have a wedge shape, tear drop shape, or other suitable shape.

Material segment 108 may be formed by depositing a layer of material over upper electrode 106 using PVD or sputtering or CDV processing or other suitable deposition process. The material layer may be suitably patterned by using an appropriate etching process to form the inner edge of the material segment 108. In the embodiment of FIG. 1A, the outer edge of the material segment 108 may be formed simultaneously with the edge of the upper electrode 106 in the same etching process to accurately define the edge of the BAW resonator 100. In one embodiment, the material layer may be suitably patterned by using an appropriate etching process to form the inner and outer edges of the material segment 108. In that embodiment, the material segment 108 may overlap the edge of the upper electrode 106 or be located within that area as a whole.

In addition, as shown in FIG. 1A, the controlled thickness region 114 is located at the edge of the BAW resonator 100, the material segment 108, the disturbing texture region 109 of the piezoelectric layer 104, And a portion of the upper electrode 106 positioned between the material segment 108 and the disturbing texture region 109. In other embodiments, the controlled thickness region 114 may be formed at a location other than the edge of the BAW resonator 100. In addition, as shown in FIG. 1A, the high density metal region 128 is located adjacent to the controlled thickness region 114 and surrounded by the controlled thickness region 114 and the upper electrode 106 is piezoelectric. It includes an area of BAW resonator 100 located above non-disrupted texture area 111 of layer 104.

FIG. 1B is a plan view of the BAW resonator 100, where the cross section of the BAW resonator 100 of FIG. 1A is on line 1A-1A in FIG. 1B. In particular, piezoelectric layer 104, upper electrode 106, material segment 108, disturbing texture region 109, controlled thickness region 114, width 116, 122 and 130, and high density metal region 128. ) Corresponds to the same element of FIGS. 1 (a) and 1 (b). As shown in FIG. 1B, the upper electrode 106 has a depth 132 that defines an appropriate depth of the active region of the BAW resonator 100. In the embodiment of Figures 1 (a) and 1 (b), the BAW resonator 100 has a square shape. In one embodiment, the BAW resonator 100 may have a square shape, where the width 122 may be approximately equal to the depth 132. Advantages may also be provided to round the corners of the BAW resonator 100 and / or to form the BAW resonator 100 such that opposite sides of the BAW resonator 100 are not parallel.

As shown in FIG. 1B, the controlled thickness region 114 is located at the edge of the BAW resonator 100, extends along the perimeter of the resonator, and is defined by the width 116 of the disturbing texture region 109. Has a defined width. In addition, as shown in FIG. 1B, the material segment 108 is located above the top electrode 106 and the disturbing texture region 109 and is also located at the edge of the BAW resonator 100. The material segment 108 is also located in the controlled thickness region 114 and extends along the circumference of the BAW resonator 100.

The operation of the BAW resonator 100 will be described. When an electric field is applied across the piezoelectric layer 104 via the upper electrode 106 and the lower electrode 102, electrical energy is converted into acoustic energy through electromechanical coupling in the piezoelectric layer 104, thereby piezoelectric layer 104. ) To vibrate. Thus, the piezoelectric layer 104 can generate an acoustic waveform that can propagate in the longitudinal mode, ie, in a direction perpendicular to the top surface 126 of the piezoelectric layer 104 in the desired mode. However, depending on the crystal structure of the piezoelectric layer 104, the edge region of the BAW resonator 100, and other factors, many other unwanted waveform propagation modes may also be generated in the piezoelectric layer 104. For example, an undesired mode, such as a side mode, that is, an acoustic waveform propagation mode that occurs in a direction parallel to the top surface 126 of the piezoelectric layer 104 may occur in the piezoelectric layer 104. As described above, large losses in BAW resonators can occur due to energy coupling into unwanted modes such as side mode. In particular, the edge of a BAW resonator, such as BAW resonator 100, is the loss region of the resonator, where coupling to an unwanted loss mode, such as a side mode, may undesirably increase energy loss in BAW resonator 100.

In the BAW resonator 100, the controlled thickness region 114 is a piezoelectric material having disturbed crystallinity with a material segment 108 positioned over the upper electrode 106 to provide thickness shaping at the edge of the BAW resonator 100. It includes a disturbing texture area 109 including a. Thus, electromechanical coupling can be controlled, which can be greatly reduced in the controlled thickness region 114. Thus, coupling to the desired longitudinal mode as well as electromechanical coupling to unwanted modes such as side mode can be greatly reduced in the controlled thickness region 114. However, the overall coupling loss from BAW resonator 100 to longitudinal mode in accordance with the coupling loss in controlled thickness region 114 reduces the BAW resonator by reducing electromechanical coupling from controlled thickness region 114 to unwanted mode. It is significantly less than the overall reduction in energy loss achieved at 100. In addition, the width 130, the thickness 124, and the composition of the material segment 108, and the width 116 of the disturbing texture region 109 of the piezoelectric layer 104, are coupled to an unwanted mode, such as the side mode. It may be appropriately selected to optimize the reduction of.

Thus, by using the disturbing texture region 109 of the piezoelectric layer 104 to reduce the electromechanical coupling in the controlled thickness region 114, embodiments of the BAW resonator 100 can be electromechanical coupled to an unwanted mode. By achieving a significant reduction of, the overall energy loss in the BAW resonator 100 is significantly reduced. By reducing the total energy loss, the present invention advantageously achieves a BAW resonator with increased Q.

From the above description of FIGS. 1 (a) and 1 (b), one of ordinary skill in the art can see that under the disturbing texture area 109 of the piezoelectric layer 104 to achieve similar peaks as described above. And even it will be apparent that the material segment 108 can be formed in other ways under the lower electrode 102 of the BAW resonator 100.

2 shows a flowchart illustrating an exemplary method according to an embodiment of the present invention. Specific details and features are set forth in flowchart 200 which will be apparent to those of ordinary skill in the art given the benefit of this disclosure. For example, as known in the art, a step may consist of one or more accessory steps, or may involve specialized devices or materials. The processing step shown in flowchart 200 is a portion of the processed wafer that includes an acoustic mirror or air cavity, in particular, placed on a substrate, not shown in any of the figures, before step 202 of flowchart 200. It is also understood to be performed for.

In step 202 of flowchart 200, bottom electrode 102 of BAW resonator 100 of FIG. 1A is formed over a substrate (not shown in any drawing). In one embodiment, the lower electrode 102 may be formed over an acoustic mirror (not shown in any drawing) that may be formed over a substrate. In another embodiment, the lower electrode 102 may be formed over an air cavity (not shown in any drawing) that may be formed over the substrate. The lower electrode 102 may comprise a high density metal, such as tungsten, molybdenum, and may be formed by depositing a high density metal layer using PVD or sputtering or other suitable deposition process and appropriately patterning the high density material layer. Can be. In step 204, a piezoelectric layer 104 is formed over the lower electrode 102, where the piezoelectric layer 104 includes a disturbing texture region 109. In the disturbance texture region 109, the crystallinity of the piezoelectric material is disturbed to significantly reduce the electromechanical coupling in the controlled thickness region 114, as described above.

Prior to the formation of the piezoelectric layer 104, the surface area to be placed under the disturbing texture region 109 may be sufficiently disturbed to ensure that the texture of the piezoelectric material is disturbed when the piezoelectric layer 104 is formed. For example, an etching process or other suitable treatment may be used to roughen the surface area of the lower electrode 102 where the disturbing texture region 109 is to be formed. In some cases subsequent disturbance of the texture of the lower electrode will disturb the texture of the piezoelectric material, so this disturbance can be done in other ways before the lower electrode is deposited. In one implementation, the piezoelectric layer 104 may comprise aluminum nitride and may be formed by depositing an aluminum nitride layer over the lower electrode 102 using a PVD process or other suitable deposition process and appropriately patterning the aluminum nitride layer. have. In step 206, the upper electrode 106 of the BAW resonator 100 is formed over the piezoelectric layer 104. For example, the upper electrode 106 may comprise a high density metal such as tungsten, molybdenum, and may deposit a high density metal layer over the piezoelectric layer 104 using PVD or sputtering treatment and apply a high density material layer to it. Can be formed by patterning.

In step 208, a material segment 108 is formed over the upper electrode 106 in the controlled thickness region 114 of the BAW resonator 100. For example, material segment 108 may comprise a metal, dielectric material, or semiconductor material, and may deposit a layer of material over upper electrode 106 in controlled thickness region 114 using CVD or other suitable deposition process. It can be formed by depositing. After deposition, the material layer can be appropriately patterned by using an appropriate etching process. For example, the material layer may be etched simultaneously with a base layer of high density metal that is not patterned such that the outer edge of the material segment 108 is self-aligned with the upper electrode 206.

Thus, as described above, in the examples of FIGS. 1 (a) and 1 (b), an embodiment of the present invention is directed to a material segment for providing thickness forming and a piezoelectric layer for providing controlled electromechanical coupling. And a BAW resonator having a controlled thickness region comprising a disturbed texture region. By using a controlled thickness region in the BAW resonator to reduce the electromechanical coupling, the BAW resonator significantly reduces the electromechanical coupling into an unwanted loss mode compared to a conventional BAW resonator using only profile shaping to reduce energy loss. By reducing, a significant reduction in energy loss is usefully achieved. Thus, the BAW resonator can advantageously achieve higher Q compared to conventional BAW resonators.

3 (a) and 3 (b), another embodiment of a BAW resonator in accordance with aspects of the present invention is shown. 3 (a) shows a cross-sectional view of a BAW resonator 300 including a lower electrode 102, a piezoelectric layer 104, and an upper electrode 106. BAW resonator 100 also includes a low density metal segment 302, as described below. As described above with respect to BAW resonator 100, BAW resonator 300 may further include an acoustic mirror that provides acoustic separation from the base substrate. The substrate and acoustic mirror on which the BAW resonator 100 is manufactured are not shown in FIG. 3 (a). In one embodiment, the BAW resonator 100 may be an FBAR and may be acoustically separated from the base substrate by the air cavity. Like the BAW resonator 100, the BAW resonator 300 can be used in a BAW filter and made of a semiconductor die to provide RF filtering in cell phones or other types of semiconductor devices.

As shown in FIG. 3A, a low density metal segment 302 is located above the piezoelectric layer 104 in the controlled thickness region 114 of the BAW resonator 300. The low density metal segment 302 may comprise aluminum, titanium, or other suitable low density metal, for example, and has a width 304 and a thickness 306. In the example shown in FIG. 3A, the low density metal segment 302 is located at the edge of the BAW resonator 300, extends along the entire circumference of the BAW resonator 300, and has a rectangular cross-sectional shape. In another example, low density metal segment 302 may be located at a location other than the edge of BAW resonator 300. In another example, the low density metal segment 302 has a cross-sectional shape that is not rectangular. Low density metal segment 302 has a width 304 (ie, cross-sectional width) that may be, for example, between 1.0 micron and 5.0 microns. The low density metal segment 302 has a thickness 306, which may be, for example, between 100.0 kPa and 3000.0 kPa. The low density metal segment 302 is shown as thicker than the upper electrode 106 for simplicity of illustration, although the low density metal segment 302 may also be thicker or approximately equal in thickness to the upper electrode 106. It should be noted.

The low density metal segment 302 may be formed by depositing a low density metal layer, such as aluminum or titanium, on the piezoelectric layer electrode 104 using, for example, a PVD or sputtering process or other suitable deposition process. The low density metal layer may be suitably patterned using an appropriate etching process to form the inner edge of the low density metal segment 302 by removing the central portion of the low density metal layer. In one embodiment, the outer edge of the low density metal segment 302 forms the outer edge of the low density metal segment 302 simultaneously with the edge of the upper electrode 106 as described below. Can be aligned with itself. In one embodiment, the low density metal layer may be suitably patterned by using an appropriate etching process to form the inner and outer edges of the low density metal segment 302. In that embodiment, the upper electrode 106 may overlap the outer edge of the low density metal segment 302 or be included entirely within its area.

In the embodiment shown in FIG. 3 (a), the high density metal layer forming the upper electrode 106 is formed of a base layer of low density metal (used to form the low density metal segment 302) in the same etching process. At the same time it can be properly patterned by forming a high density metal layer, providing a precisely defined edge of the BAW resonator 300. Thus, in one embodiment, the edge of the upper electrode 106 may self align with the outer edge of the low density metal segment 302. In one example, the high density metal layer can overlap the previously formed outer edge of the low density metal segment 302 and can be properly patterned using an appropriate etching process.

As described above, the controlled thickness region 114 is located at the edge of the BAW resonator 300 and extends along the edge of the BAW resonator 300. In the example shown in FIG. 3A, the controlled thickness region 114 includes a low density metal segment 302 and a portion 308 of the upper electrode 106 underlying the low density metal segment 302. do. In another embodiment, the controlled thickness region 114 may be formed at a location of the BAW resonator 300 other than the edge of the resonator. In addition, as shown in FIG. 3A, the high density metal region 310 of the BAW resonator 300 is located adjacent to the controlled thickness region 114 and surrounded by the controlled thickness region 114. In the high density metal region 310, the upper electrode 106 is located on the piezoelectric layer 104. Thus, in the high density metal region 310, a low density metal segment, such as the low density metal segment 302, is not located between the upper electrode 106 and the piezoelectric layer 104.

FIG. 3 (b) shows a top view of the structure 300, where the cross section of the BAW resonator 300 of FIG. 3 (a) is on the lines 3A-3A of FIG. 3 (b). In particular, the piezoelectric layer 104, the upper electrode 106, the controlled thickness region 114, the widths 304 and 122 and the high density metal region 310 are the same as in FIGS. 3A and 3B. Corresponds to an element. As shown in FIG. 3B, the upper electrode 106 has a width 312 that defines an appropriate depth of the active region of the BAW resonator 300. In the embodiment of Figures 3 (a) and 3 (b), the BAW resonator 300 has a square shape. In another embodiment, BAW resonator 300 may have a square shape, where width 122 is approximately equal to depth 312. As described above, advantages may also be provided for rounding the corners of the BAW resonator and / or forming the resonator such that opposite sides of the resonator are not parallel. As shown in FIG. 3 (b), the controlled thickness region 114 is located at the edge of the BAW resonator 300, extends along the perimeter of the resonator, and has a low density metal segment 302 (FIG. 3 (b)). It has a width defined by the width 304 of the). Also, as shown in FIG. 3B, the high density metal region 310 of the BAW resonator 300 is located adjacent to the controlled thickness region 114 and surrounded by the controlled thickness region 114.

The operation of BAW resonator 300 will be described. As described above, an unwanted side mode can be generated in the piezoelectric layer 104 during operation of the BAW resonator 300, resulting in significant energy loss in the BAW resonator 300. In one embodiment of the BAW resonator 300, the controlled thickness region 114 is at the edge of the BAW resonator 300 by adding a low density metal segment 302 between the upper electrode 106 and the piezoelectric layer 104. Provide thickness shapes. This increases the thickness at the edge of the resonator, reducing the energy loss to unwanted modes such as side modes by suppressing unwanted modes. Controlled thickness region by using a low density metal, such as aluminum or titanium, to form a low density metal segment 302 having a lower density than the high density metal used to form the upper electrode 106 At 114, electromechanical coupling can be significantly reduced. Thus, electromechanical coupling from the controlled thickness region 114 to an unwanted mode, such as the side mode, can be significantly reduced. Although the coupling to the desired longitudinal axis mode is also reduced, an appropriate overall loss of coupling from the BAW resonator 300 to the longitudinal axis mode is not desired in the controlled thickness region 114 depending on the coupling loss in the controlled thickness region 114. By reducing the electromechanical coupling to the mode is ensured by the reduction of the total energy loss achieved in the BAW resonator 300.

Thus, by reducing the electromechanical coupling to the unwanted mode in the controlled thickness region 114, the significant reduction in energy loss in the BAW resonator 300 is reduced to the unwanted mode, such as the side mode in the BAW resonator 300. By reducing the electromechanical coupling. Also, in the controlled thickness region 114, the width 304 and thickness 306 of the low density metal segment 302, and the thickness 120 of the upper electrode 106 are optimal in the BAW resonator 300. It may be appropriately selected to achieve a reduction in energy loss.

Thus, by controlling the electromechanical coupling in the controlled thickness region 114, the example shown in FIGS. 3 (a) and 3 (b) is a side view compared to conventional BAW resonators using profile shaping to reduce losses. A significant reduction in the amount of energy coupled to the unwanted mode with loss, such as mode, can be achieved. Thus, by reducing energy loss, embodiments of BAW resonator 300 may advantageously provide increased Q (quality factor) compared to conventional BAW resonators.

From the above description of the embodiment of the invention of Figures 3 (a) and 3 (b), a controlled thickness region, such as controlled thickness region 114, is similar to those described above, if one of ordinary skill in the art. It will be apparent that the BAW resonator 300 may be usefully formed between the lower electrode 102 and the piezoelectric layer 104 to achieve the advantage.

4 (a) shows a cross section of another example of a BAW resonator 400 according to one embodiment. BAW resonator 400 may be, for example, an FBAR and may be acoustically separated from the base substrate by an air cavity. BAW resonator 400 may be used in a BAW filter and made of a semiconductor die to provide RF filtering in cell phones or other types of semiconductor devices.

In the example shown in FIG. 4A, the BAW resonator 400 is positioned on the top surface 126 of the piezoelectric layer 104 in the controlled thickness region 114 of the BAW resonator 400. ). Dielectric segment 402 is also confined within the perimeter of piezoelectric layer 104. That is, it does not extend beyond the edge of the piezoelectric layer 104. However, as described below, dielectric segments 402 are positioned on top surface 126 of piezoelectric layer 104 for effective control of electromechanical coupling in controlled thickness regions 114 (in one embodiment). Or (ie, in direct contact) or located on the bottom surface of the piezoelectric layer 104.

Dielectric segment 402 may include, for example, silicon oxide, silicon nitride, or other suitable dielectric material. In one embodiment, dielectric segment 402 comprises porous silica, fluorinated amorphous carbon, fluoropolymer, parylene, polyarylene, ether, hydrogen silsesquioxane (HSQ), fluorinated silicon dioxide, and diamond And " low dielectric constant (low k) dielectric materials ”such as shape carbon. In one application, a "low k dielectric material" is defined as a dielectric material having a dielectric constant lower than that of silicon oxide.

In the example shown in FIG. 4A, the dielectric segment 402 is located at the edge of the BAW resonator 400 and extends along the entire circumference of the BAW resonator 400 and has a rectangular cross-sectional shape. In one embodiment, the dielectric segment 402 may be located very close to the BAW resonator 400. In another example, the dielectric segment 402 may have a cross-sectional shape that is not rectangular. Dielectric segment 402 has a width 404, which may be, for example, between 1.0 and 5.0 microns. Dielectric segment 402 has a thickness 406, which may be, for example, between 100.0 kPa and 3000.0 kPa. While dielectric segment 402 is shown as thicker than upper electrode 106 for simplicity of illustration, it should be noted that dielectric segment 402 may also be thicker or approximately equivalent in thickness to upper electrode 106.

Dielectric segment 402 may be formed by depositing a dielectric material layer, such as silicon oxide, on piezoelectric layer 104 using, for example, a CVD process or other suitable deposition process. The dielectric material layer may be suitably patterned using an appropriate etching process to form the inner edge of the dielectric segment 402 by removing the central portion of the dielectric material. In the embodiment of FIG. 4A, the outer edge of dielectric segment 402 can self align with the edge of upper electrode 106. For example, the upper electrode 106 can be formed by depositing a high density metal layer, such as tungsten or molybdenum, on the piezoelectric layer 104 and the dielectric segment 402 using PVD or sputtering or other suitable deposition process. . The high density metal layer may be usefully patterned by etching the high density metal layer simultaneously with the base layer of the dielectric material used to form the dielectric segment 402 to accurately define the edges of the BAW resonator 400. Thus, in the embodiment of FIG. 4A, the edge of the upper electrode 106 may self align with the outer edge of the dielectric segment 402. In other embodiments, the high density metal layer may overlap the outer edge of the dielectric segment 402 and may be suitably patterned using an appropriate etching process to form the edge of the upper electrode 106. In other embodiments, the dielectric material layer may be suitably patterned by using an appropriate etching process to form the inner and outer edges of the dielectric segment 402. In that embodiment, the upper electrode 106 can overlap the outer edge of the dielectric segment 402 or be included entirely within its area.

As also shown in FIG. 4A, the controlled thickness region 114 is located over the edge of the BAW resonator 400, extends along the edge of the BAW resonator 400, and includes a dielectric segment 402 and a dielectric. A portion 308 of the upper electrode 106 overlying the segment 402 is included. In other embodiments, the controlled thickness region 114 may be formed at another location of the BAW resonator 400 other than the edge of the resonator. In the embodiment of FIG. 4A, the controlled thickness region 114 has a uniform cross-sectional thickness. As described above, in another embodiment, the controlled thickness region 114 may have a non-uniform cross-sectional thickness, such as, for example, a wedge shape, a tear drop shape. Also as shown in FIG. 4A, the high density metal region 408 of the BAW resonator 300 is located adjacent to the controlled thickness region 114 and surrounded by the controlled thickness region 114. In the high density metal region 408, the upper electrode 106 is located on the piezoelectric layer 104. Thus, in high density metal region 408, a dielectric segment, such as dielectric segment 402, is not located between upper electrode 106 and piezoelectric layer 104.

4 (b) shows a top view of the structure 400, wherein the cross section of the BAW resonator 400 of FIG. 4 (a) is on lines 4A-4A of FIG. 4 (b). In particular, the piezoelectric layer 104, the upper electrode 106, the controlled thickness region 114, the widths 404 and 122, and the high density metal region 4080 are identical to those of FIGS. 4A and 4B. Corresponds to an element. As described above, in FIGS. 4A and 4B, the BAW resonator 400 has a square shape, but in contrast, the BAW resonator 400 may have a square shape, where the width 122 ) May be approximately equal to depth 312. As described above, advantages may also be provided for rounding the corners of the BAW resonator and / or forming the resonator such that opposite sides of the resonator are not parallel. As shown in FIG. 4 (b), the controlled thickness region 114 is located at the edge of the BAW resonator 400, extends along the perimeter of the resonator, and is defined by the width 404 of the dielectric segment 402. Has a width. Also, as shown in FIG. 4B, the high density metal region 408 of the BAW resonator 400 is located adjacent to the controlled thickness region 114 and surrounded by the controlled thickness region 114.

The operation of BAW resonator 400 will be described. As described above, unwanted side modes can be generated in the piezoelectric layer 104 during operation of the BAW resonator 400, resulting in significant energy loss in the BAW resonator. In the BAW resonator 400, the controlled thickness region 114 provides thickness shaping at the edge of the BAW resonator 400 by adding a dielectric segment 402 between the upper electrode 106 and the piezoelectric layer 104. Control of electromechanical coupling is also provided by providing a dielectric segment 402 that operates electrically as a series capacitor to reduce the electric field in the controlled thickness region 114. By reducing the electric field in the controlled thickness region 114, the electromechanical coupling in the controlled thickness region 114 can be correspondingly reduced.

By reducing the electromechanical coupling in the controlled thickness region 114, electromechanical coupling to unwanted modes such as the side mode is reduced. Although the coupling to the desired longitudinal mode is also reduced, the appropriate overall loss of coupling from the BAW resonator 400 to the longitudinal mode is undesired in the controlled thickness region 114 depending on the coupling loss in the controlled thickness region 114. By reducing the electromechanical coupling to the mode is ensured by the reduction of the total energy loss achieved in the BAW resonator 400.

Thus, by reducing the electromechanical coupling in the controlled thickness region 114, the significant reduction in energy loss in the BAW resonator 400 reduces the electromechanical coupling to the unwanted mode, such as the side mode in the BAW resonator 400. Can be achieved by In addition, in the controlled thickness region 114, the width 404 and the thickness 346 of the dielectric segment 402, and the thickness 120 of the upper electrode 106 are optimized for energy loss in the BAW resonator 400. It may be appropriately selected to achieve a reduction of.

Thus, by controlling the electromechanical coupling in the controlled thickness region 114, the embodiment of FIGS. 4 (a) and 4 (b) is in lateral mode compared to conventional BAW resonators using profile shaping to reduce losses. A significant reduction in the amount of energy coupled to the unwanted mode of loss may be achieved. Thus, by reducing energy loss, embodiments of the BAW resonator 400 may advantageously provide increased Q (quality factor) compared to conventional BAW resonators.

From the above description of the embodiment of the invention of FIGS. 4 (a) and 4 (b), those skilled in the art have previously described controlled thickness regions, such as controlled thickness regions 114, in other ways. It will be apparent that a dielectric segment such as dielectric segment 402 may be formed between bottom electrode 102 and piezoelectric layer 104 in BAW resonator 400 to achieve similar advantages as described.

Referring to FIG. 5, a flowchart illustrating an example method according to one embodiment is shown. Specific details and features are set forth in flowchart 500 which will be apparent to those of ordinary skill in the art given the benefit of this disclosure. For example, as known in the art, a step may consist of one or more accessory steps, or may involve specialized devices or materials. The processing steps shown in flowchart 500 may be performed prior to step 202 of flowchart 500 to a portion of the processed wafer that includes an acoustic mirror or air cavity, in particular overlying a substrate not shown in any of the figures. It should be noted that the As described above, in step 202, the bottom electrode 102 of the BAW resonator is formed over the substrate. In step 204, a piezoelectric layer 104 is formed over the lower electrode 102.

In step 506, a material segment, such as the low density metal segment 302 of FIG. 3 (a) or the dielectric segment 402 of FIG. 4 (a), is controlled by a BAW resonator such as a controlled thickness region 114. It is formed over the piezoelectric layer 104 in the thickness region. For example, the low density metal segment 302, which may include a low density metal such as aluminum or titanium, may be a piezoelectric layer 104 in the controlled thickness region 114 of the BAW resonator 300 using PVD or sputtering treatment. It can be formed on). For example, the dielectric segment 402, which may include a dielectric material such as silicon oxide, silicon nitride, or a low k dielectric material, may be a controlled thickness region of the BAW resonator 400 using CVD or other suitable deposition process. 114 may be formed over the piezoelectric layer 104.

In step 508, the upper electrode is formed over a material segment, such as low density metal segment 302 or dielectric segment 402, and over piezoelectric layer 104. For example, the upper electrode 106 may comprise a high density metal, such as tungsten or molybdenum, and may be on the low density metal segment 302 or the dielectric segment 402 and the piezoelectric layer 104 using a sputtering process. It can be formed by depositing a high density metal layer thereon and patterning the high density metal layer appropriately. For example, the high density metal layer allows the edge of the upper electrode, such as the upper electrode 106, to self-align with the outer edge of the base segment of the material, such as the low density metal segment 302 or the outer edge of the dielectric segment 402. It can be etched simultaneously with the base layer of material.

Thus, as described above in connection with FIGS. 3 (a) and 3 (b) and 4 (a) and 4 (b), the side and embodiment provide a BAW resonator comprising a controlled thickness region. And the controlled thickness area provides the molded thickness and the controlled electromechanical coupling. By using a controlled thickness region to reduce electromechanical coupling at the edge of the BAW resonator, the BAW resonator avoids electromechanical coupling into an unwanted loss mode compared to conventional BAW resonators that only use profile shaping to reduce energy loss. Significant reduction in energy loss can be usefully achieved by significantly reducing energy consumption. Thus, the BAW resonator can advantageously achieve higher Q compared to conventional BAW resonators.

6 is a diagram of an example electronic system including an example chip or using one or more BAW resonators in accordance with one embodiment. Electronic system 600 includes example modules 602, 604, and 606, IC chips or semiconductor dies 608, and discrete components 610, 612 interconnected through circuit board 614. In one embodiment, the electronic system 600 may include two or more PCBs. IC chip 608 includes circuitry 616 that may include a BAW filter that includes one or more BAW resonators, denoted by reference numeral 618.

As shown in FIG. 6, modules 602, 604, and 606 are mounted on a circuit board 614, for example, a central processing unit (CPU), a graphics controller, a digital signal processor (DSP), an ASIC ( application specific integrated circuits, video processing modules, audio processing modules, RF receivers, RF transmitters, image sensor modules, power control modules, electromechanical motor control modules, field programmable gate arrays, or current electronic circuit boards. It can be any other kind of module. Circuit board 614 may include interconnect modules 602, 604, and 606, anomalous components 610, 612, and multiple interconnect traces (not shown in FIG. 6) for IC chip 608. Can be.

As also shown in FIG. 6, IC chip 608 is mounted on circuit board 614, for example, one or more of the above-described BAW resonators, such as any BAW resonators 100, 300, and 400. It may be any chip using an embodiment. In one embodiment, IC chip 608 may not be mounted on circuit board 614 and may be interconnected with other modules on different circuit boards. As described above, circuit 616 may include a BAW filter located within IC chip 608 and including one or more BAW resonators as indicated by reference numeral 618. In addition, as shown in FIG. 6, the abnormal components 610 and 612 are mounted on the circuit board 614, respectively, for example, a discrete filter including a SAW filter, a power amplifier or an operational amplifier, a transistor, and the like. Or a semiconductor device such as a diode, an antenna element, an inductor, a capacitor, or a resistor.

The electronic system 600 may include, for example, wired or wireless communication device, cell phone, switching device, router, repeater, codec, wired or wireless LAN, WLAN, Bluetooth enabled device, Global Positioning System (GPS) device, computer, Use as monitors, television sets, satellite set top boxes, cable modems, printers, copiers, RF transmitters and personal digital assistants (PDAs), or any other type of system, device, component, or module used in current electronic applications. Can be.

While at least some aspects of one embodiment have been described, it will be apparent to those skilled in the art that various alternatives, modifications, and improvements will readily occur. Such alternatives, modifications, and sections are intended to be part of this disclosure and are within the spirit of the invention. The examples described herein are intended to illustrate some novel features, aspects, and examples of the terms described herein and should not be considered as limiting the scope of the appended claims. Accordingly, the foregoing description and drawings are by way of example only, and the scope of the present invention should be determined from the proper configuration of the appended claims and their equivalents.

Claims (32)

Bulk acoustic wave (BAW) resonator,
A piezoelectric layer located between the upper and lower electrodes, each of the upper and lower electrodes comprising a high density metal;
A region of controlled thickness comprising a material segment located adjacent to the piezoelectric layer,
The controlled thickness region has a controlled electromechanical coupling,
The material segment includes one of a low density metal segment and a dielectric segment
BAW resonator.
The method of claim 1,
The controlled thickness area provides for reduced electromechanical coupling to the side mode.
BAW resonator.
The method of claim 1,
The material segment is located between the upper electrode and the piezoelectric layer.
BAW resonator.
The method of claim 1,
The material segment extends along the circumference of the BAW resonator
BAW resonator.
The method of claim 3, wherein
The edge of the upper electrode is self aligned with the outer edge of the material segment
BAW resonator.
The method of claim 3, wherein
An edge of the upper electrode overlaps an outer edge of the material segment
BAW resonator.
The method of claim 1,
The low density metal segment comprises a metal selected from the group consisting of aluminum and titanium.
BAW resonator.
The method of claim 1,
The dielectric segment comprises a low k dielectric material
BAW resonator.
The method of claim 8,
The low k dielectric material consists of porous silica, fluorinated amorphous carbon, fluoropolymer, parylene, polyarylene, ether, hydrogen silsesquioxane (HSQ), fluorinated silicon dioxide, and diamond shaped carbon Selected from the group
BAW resonator.
The method of claim 1,
The material segment comprises the dielectric segment, the dielectric segment is located in contact with the piezoelectric layer, the dielectric segment being confined within the perimeter of the piezoelectric layer.
BAW resonator.
The method of claim 10,
The dielectric segment is located at the edge of the BAW resonator
BAW resonator.
As a method of forming a BAW resonator,
Forming a piezoelectric layer on the lower electrode of the BAW resonator;
Forming a material segment over said piezoelectric layer in a controlled thickness region of said BAW resonator, said controlled thickness region having controlled electromechanical coupling;
Forming an upper electrode of the BAW resonator over the material segment, wherein the upper electrode comprises a high density metal;
Forming the material segment comprises one of forming a low density metal segment and forming a dielectric segment
How to form a BAW resonator
The method of claim 12,
The controlled thickness area provides for reduced electromechanical coupling to the side mode.
How to form a BAW resonator.
The method of claim 12,
Forming the upper electrode includes forming an edge of the upper electrode simultaneously with an outer edge of the material segment.
How to form a BAW resonator.
Bulk acoustic waveform (BAW) resonator,
A piezoelectric layer having a disrupted texture region, wherein the disturbing texture region is located in a controlled thickness region of the BAW resonator;
Lower and upper electrodes located on opposite surfaces of the piezoelectric layer,
The controlled thickness region has a controlled electromechanical coupling
BAW resonator.
The method of claim 15,
The controlled thickness area provides for reduced electromechanical coupling to the side mode.
BAW resonator.
The method of claim 15,
The controlled thickness region is located at the edge of the BAW resonator and extends along the circumference of the BAW resonator
BAW resonator.
The method of claim 15,
The controlled thickness region includes a material segment located over the upper electrode.
BAW resonator.
The method of claim 18,
The material segment is selected from the group consisting of metal and dielectric material
BAW resonator.
The method of claim 18,
The outer edge of the material segment is self aligned with the edge of the upper electrode
BAW resonator.
The method of claim 15,
And a thin layer of silicon oxide under the disturbing texture region and positioned between the lower electrode and the piezoelectric layer.
BAW resonator.
The method of claim 15,
The disturbing texture region is located at the edge of the BAW resonator and extends along the circumference of the BAW resonator
BAW resonator.
As a method of forming a BAW resonator,
Forming a lower electrode of the BAW resonator;
Forming a piezoelectric layer over the lower electrode, the piezoelectric layer comprising a disturbing texture region, the disturbing texture region being located in a controlled thickness region of the BAW resonator;
Forming an upper electrode of the BAW resonator on the piezoelectric layer,
The controlled thickness region has a controlled electromechanical coupling
How to form a BAW resonator
The method of claim 23,
Forming a material segment over the upper electrode;
How to form a BAW resonator.
The method of claim 24,
Forming the material segment includes forming a material segment selected from the group consisting of metal and dielectric material.
How to form a BAW resonator.
The method of claim 23,
Before forming the piezoelectric layer, further comprising forming a thin layer of silicon oxide over the region of the lower electrode where the disturbing texture region is to be formed.
How to form a BAW resonator.
The method of claim 23,
Roughening a region of the lower electrode on which the disturbing texture region is to be formed before forming the piezoelectric layer.
How to form a BAW resonator.
A semiconductor die comprising at least one BAW resonator,
The at least one BAW resonator,
A piezoelectric layer having a disturbed texture region located in a controlled thickness region of the BAW resonator;
Lower and upper electrodes located on opposite surfaces of the piezoelectric layer,
The controlled thickness region has a controlled electromechanical coupling
Semiconductor die.
29. The method of claim 28,
The controlled thickness area provides for reduced electromechanical coupling to the side mode.
Semiconductor die.
29. The method of claim 28,
The controlled thickness region is located at the edge of the BAW resonator and extends along the circumference of the BAW resonator
Semiconductor die.
29. The method of claim 28,
The controlled thickness region includes a material segment located over the upper electrode.
Semiconductor die.
29. The method of claim 28,
The semiconductor die is used within a circuit board as part of an electronic system, the electronic system being a wired or wireless communication device, cell phone, switching device, router, repeater, codec, wired or wireless LAN, WLAN, Bluetooth enabled device, GPS (Global Positioning System) selected from the group consisting of devices, computers, monitors, television sets, satellite set top boxes, cable modems, printers, copiers, RF transmitters, and personal digital assistants (PDAs).
Semiconductor die.

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