WO2018182657A1

WO2018182657A1 - Compensation for temperature coefficient of resonant frequency using atomic layer deposition materials

Info

Publication number: WO2018182657A1
Application number: PCT/US2017/025219
Authority: WO
Inventors: Kimin JUN; Edris Mohammed; Kevin Lin
Original assignee: Intel Corporation
Priority date: 2017-03-30
Filing date: 2017-03-30
Publication date: 2018-10-04

Abstract

Electronic devices, computing devices, and related methods are disclosed. An electronic device includes an acoustic device on or in a semiconductor structure, and a Temperature Coefficient of resonant Frequency (TCF) compensation material disposed proximate to the resonator material and including an Atomic Layer Deposition (ALD) material having a compensating TCF that at least substantially compensates for a TCF of the resonator material. A method includes disposing a resonator material having a TCF onto or into a semiconductor structure, and disposing, using ALD, an ALD material proximate to the resonator material.

Description

COMPENSATION FOR TEMPERATURE COEFFICIENT OF RESONANT FREQUENCY USING ATOMIC LAYER DEPOSITION MATERIALS

Technical Field

[0001] This disclosure relates generally to devices including acoustic devices that are compensated for Temperature Coefficient of resonant Frequency (TCF) using Atomic Layer Deposition (ALD) materials, and related methods.

Background

[0002] Radio Frequency (RF) filters, duplexers, oscillators, and mechanical sensors are examples of devices that sometimes include acoustic resonators (e.g., Film Bulk Acoustic Resonators (FBARs), Contour Mode Resonators (CMRs), Surface Acoustic Wave (SAW) resonators, etc.). Operation of these devices is often affected by fluctuations in temperature.

Brief Description of the Drawings

[0003] FIG. 1 is a simplified block diagram of an electronic device, according to some embodiments.

[0004] FIG. 2 is a simplified cross-sectional view of an example of the electronic device of FIG. 1 , according to some embodiments.

[0005] FIG. 3 is a simplified cross-sectional view of another example of the electronic device of FIG. 1 , according to some embodiments.

[0006] FIG. 4 is a simplified cross-sectional view of yet another example of the electronic device of FIG. 1 , according to some embodiments.

[0007] FIG. 5 is a simplified cross-sectional view of a further example of the electronic device of FIG. 1 , according to some embodiments.

[0008] FIG. 6 is a simplified cross-sectional view of yet another example of the electronic device of FIG. 1 , according to some embodiments.

[0009] FIG. 7 is a simplified flowchart illustrating a method of manufacturing an electronic device, according to some embodiments.

[0010] FIG. 8 is an interposer, according to some embodiments.

[0011] FIG. 9 is a computing device, according to some embodiments.

Detailed Description of Preferred Embodiments

[0012] Disclosed herein are electronic devices, computing devices, and related methods for acoustic devices that are compensated for TCF using ALD materials. In the following description, various aspects of the illustrative implementations will be described using terms commonly employed by those skilled in the art. It will be apparent, however, to those skilled in the art that embodiments disclosed herein may be practiced with only some of the described aspects. For purposes of explanation, specific numbers, materials and configurations are set forth in order to provide a thorough understanding of the illustrative embodiments. It will be apparent, however, to one skilled in the art that embodiments disclosed herein may be practiced without the specific details disclosed herein. In some embodiments disclosed herein, well-known features are omitted or simplified in order not to obscure the illustrative implementations.

[0013] Various operations will be described as multiple discrete operations, in turn, in a manner that is helpful in understanding the present disclosure. The order, however, of description should not be construed to imply that these operations are necessarily order dependent. In particular, these operations need not be performed in the order of presentation.

[0014]The terms "over," "under," "between," and "on," as used herein, refer to a relative position of one material (e.g., a material layer) or component with respect to other materials or components. For example, one material disposed over or under another material may be directly in contact with the other material or may have one or more intervening materials in between. Moreover, one material disposed between two materials may be directly in contact with the two materials or may have one or more intervening materials. In contrast, a first material "on" a second material is in direct contact with that second material. Similarly, unless explicitly stated otherwise, one feature disposed between two features may be in direct contact with the adjacent features or may have one or more intervening materials or features.

[0015] Embodiments disclosed herein may be formed or carried out on a substrate, such as a semiconductor substrate. In one implementation, the semiconductor substrate may be a crystalline substrate formed using a bulk silicon or a

silicon-on-insulator substructure. In other implementations, the semiconductor substrate may be formed using alternative materials, which may or may not be combined with silicon, that include but are not limited to germanium, indium antimonide, lead telluride, indium arsenide, indium phosphide, gallium arsenide, indium gallium arsenide, gallium antimonide, or other combinations of group lll-V or group IV materials. Although a few examples of materials from which the substrate may be formed are described here, any material that may serve as a foundation upon which a semiconductor device may be built falls within the spirit and scope of the present disclosure.

[0016] Temperature Coefficient of resonant Frequency (TCF) is a material property that indicates resonant frequency shift with respect to temperature. In some devices, acoustic resonators are very precisely designed for operation at precise resonant frequencies with near zero temperature shift. Since no materials have zero intrinsic TCF, there may be a compensation structure. For example, if a resonator material has negative TCF, a second material with positive TCF may be used along with the resonator material to cancel the overall frequency shift as temperature fluctuates.

[0017] Most piezoelectric materials used for radio frequency (RF) resonators have negative TCF, including aluminum nitride (AIN) (about -25 parts per million per degree Kelvin (ppm/K)), lithium tantalate (LT), and lithium niobate (LN) (about -80 ppm/K). Silicon dioxide (S1O2) (about +50 ppm/K) may be used for a TCF

compensation material because of its positive TCF and its well-known fabrication processes. Si0₂, however, does not have a relatively large TCF difference in magnitude from TCFs of piezoelectric materials. As a result, when used as a TCF compensation material, the S 1O2 may be fairly thick (e.g., hundreds of nanometers, which may be disposed using Chemical Vapor Deposition (CVD) or sputtering).

[0018] Thick TCF compensation materials tend to reduce quality of operation because of mass loading. In other words, thick TCF compensation materials add effective mass to resonators, which are otherwise interfaced with air. This mass loading results in frequency shift, which complicates device design. In addition, thick TCF compensation materials increase damping effect, resulting in lower

performance because of energy loss.

[0019] Some materials have a larger positive TCF than S1O2. By way of non-limiting example, titanium dioxide (T1O2) has a TCF of +450 ppm/K, which is much larger than the TCF of +50 ppm/K of S1O2. As the TCF of T1O2 has a much larger magnitude (positive) than negative magnitudes of most piezoelectric materials, the thickness of a TCF compensation material having T1O2 may be much thinner than a TCF compensation material having S1O2. The thickness of TCF compensation materials including T1O2 should, however, be precisely controlled (e.g., on the order of one nanometer). Sputtering (Physical Vapor Deposition (PVD)) and CVD processes do not, however, provide this precision of control. [0020] Disclosed herein are devices and methods utilizing TCF compensation materials including ALD materials having TCFs that compensate for TCFs of resonator materials or piezoelectric materials.

[0021] The terms "resonator material" and "piezoelectric material" may be used interchangeably herein to refer to materials that are used in acoustic devices (e.g., FBARs, CMRs, SAW resonators, etc.). For example, an acoustic device may include a resonator material or piezoelectric material and one or more electrodes. Resonator materials and piezoelectric materials may generate electrical charge or electric potential (e.g., on electrodes) responsive to mechanical displacement or force, and mechanical displacement or force responsive to electric potentials or fields (e.g., applied to electrodes).

[0022] As used herein, the term "ALD material" refers to a material that has been deposited using ALD. Although ALD is generally considered a form of CVD, ALD is more controllable in its ability to deposit materials at very specific thicknesses as compared to other forms of CVD. Also, ALD can cover under-layers, and surfaces in air cavities or undercut regions, providing integration flexibility. This controllability is on the order of about one nanometer (1 nm) resolution. Accordingly, ALD materials may be about ten (10) or less nanometers thick, if desired. As a result, ALD materials having high magnitude (e.g., positive magnitude) TCF and low thickness (e.g., about 10 nanometers or less) may be deposited on resonator materials having negative TCF without significantly mass-loading the resonator materials. For example, an ALD material may include titanium dioxide (T1O2), silicon oxide, silicon dioxide, aluminum oxide, hafnium oxide, other materials, or combinations thereof, each of which has a TCF that may cancel the TCF of resonator materials.

[0023] FIG. 1 is a simplified block diagram of an electronic device 100, according to some embodiments. The electronic device includes a semiconductor structure 1 10 (e.g., a semiconductor substrate), an acoustic device 120 on or in the semiconductor structure 1 10, and a TCF compensator 130 including an ALD material disposed proximate to (e.g., on) the acoustic device 120. The acoustic device 120 includes a resonator material having a TCF, and the ALD material has a compensating TCF that at least substantially compensates for the TCF of the resonator material. As used herein, the phrase "at least substantially compensates" acknowledges that perfect compensation of the TCF of the resonator material may not always be achieved in practice, but that at least substantial (e.g., 75%, 80%, 85%, 90%, 95%, or even more) compensation may be practical within the scope of the disclosure. Since the TCF compensator 130 includes an ALD material, the thickness of the ALD material may be sufficiently small (e.g., about 10 nm or less) to prevent significant mass loading of the acoustic device 120. Also, ALD materials may be more conformal to surfaces they are deposited to than materials deposited using PVD or other forms of CVD.

[0024] In some embodiments, the ALD material includes titanium dioxide (Ti0₂). T1O2 has a TCF with a significantly high positive magnitude to compensate for the TCF of the resonator material of the acoustic device 120 without significantly mass-loading the acoustic device 120. Other materials that the ALD material may include are silicon oxide (SiO), silicon dioxide (SiO₂), aluminum oxide (AI₂O₃), and hafnium oxide (HfO2). One advantage of ALD materials is easiness of material composition control. Either by precursor choice or by cyclic programming, various compositions are possible. Dielectric films such as Si, Ti, Al, and Hf oxides can easily be compounded, and make arbitrary ALD materials that are customized to specifications. Accordingly, the ALD material may include only one of SiO, S1O2, AI2O3, and HfO2, or even two or more of SiO, S1O2, AI2O3, and HfO2. In some embodiments, the ALD material conforms to the acoustic device 120 (e.g., with a higher degree of conformity than that of PVD or other CVD materials).

[0025] In some embodiments, the acoustic device 120 includes a resonator. By way of non-limiting example, the acoustic device 120 may include an FBAR, a CMR, or a SAW resonator. In some embodiments, the resonator material of the acoustic device 120 may include AIN, LT, LN, other piezoelectric materials, or combinations thereof.

[0026] As previously discussed, the TCF of the ALD material of the TCF

compensator compensates for the TCF of the resonator material of the acoustic device 120. In some embodiments, the TCF of the resonator material of the acoustic device 120 is negative and the TCF of the ALD material is positive. In some embodiments, the TCF of the resonator material is positive and the TCF of the ALD material is negative.

[0027] FIG. 2 is a simplified cross-sectional view of an example of the electronic device 100 of FIG. 1 , according to some embodiments. An electronic device 200 includes an FBAR disposed on or in a semiconductor substrate 210. The electronic device 200 includes a resonator material 222 between two electrodes 224, an air gap 212 between at least a portion of the FBAR and the substrate 210, and an ALD material 230 deposited proximate to (e.g., on) an electrode 224 of the FBAR. The ALD material 230 compensates for a TCF of the resonator material 222.

[0028] FIG. 3 is a simplified cross-sectional view of another example of the electronic device 100 of FIG. 1 , according to some embodiments. An electronic device 300 includes a CMR disposed on or in a semiconductor substrate 310. The electronic device 300 includes a resonator material 322, electrodes 324, an air gap 312 between at least a portion of the resonator material 322 and the substrate 310, and an ALD material 330 deposited over the resonator material 322 and the electrodes 324. The ALD material 330 compensates for a TCF of the resonator material 322.

[0029] FIG. 4 is a simplified cross-sectional view of yet another example of the electronic device 100 of FIG. 1 , according to some embodiments. An electronic device 400 includes a SAW resonator including a piezoelectric substrate 422, electrodes 424, and an ALD material 430 deposited over the piezoelectric substrate 422 and the electrodes 424. The ALD material 430 compensates for a TCF of the piezoelectric substrate 422.

[0030] One advantage of ALD materials lies in their conformal nature and gentle process. In case of FBAR or CMR (FIGS. 5 and 6, respectively), which may include undercut air cavities, the ALD material may be deposited within an undercut region proximate to the acoustic device. This ALD deposition may occur even after membrane process with minimal risk on devices. This gives great flexibility on integration. In some embodiments, undercut is achieved by vapor hydrogen fluoride (VHF). Since S1O2 and other compensation materials are attacked by VHF, the compensation material should be well encapsulated during undercut if deposited before VHF. This complicates the process and encapsulating structures aggravates device performance. ALD simplifies these complexities by enabling deposition after VHF, as illustrated in FIGS. 5 and 6.

[0031] FIG. 5 is a simplified cross-sectional view of a further example of the electronic device 100 of FIG. 1 , according to some embodiments. An electronic device 500 includes an FBAR disposed on or in a semiconductor substrate 510. The electronic device 500 includes a resonator material 522 disposed between electrodes 524, an air gap 512 between a bottom electrode 524 and the substrate 510, and an ALD material 530 disposed conformably over the FBAR and on surfaces defining the air gap 512. [0032] FIG. 6 is a simplified cross-sectional view of yet another example of the electronic device 100 of FIG. 1 , according to some embodiments. An electronic device 600 includes a CMR disposed on or in a semiconductor substrate 610. The electronic device 600 includes a resonator material 622, electrodes 624 on the resonator material 622, an air gap 612 between the resonator material 622 and the substrate 610, and an ALD material 630 disposed conformably over the FBAR and on surfaces defining the air gap 612.

[0033] FIG. 7 is a simplified flowchart illustrating a method 700 of manufacturing an electronic device (e.g., the electronic device 100, 200, 300, 400, 500, or 600 of FIGS. 1 -6), according to some embodiments. Referring to FIGS. 1 and 7 together, the method 700 includes disposing 710 a resonator material having a TCF onto or into a semiconductor structure 1 10. The method 700 also includes disposing 720, using ALD, an ALD material proximate to the resonator material. The ALD material has a compensating TCF that compensates for the TCF of the resonator material. In some embodiments, disposing 720 an ALD material includes disposing the ALD material on at least one electrode of an acoustic device 120 including the resonator material.

[0034] In some embodiments, the method further includes forming an undercut region (e.g., undercut region 212, 312, 512, or 612) between the resonator material and the semiconductor structure 1 10. In such embodiments, disposing 720 an ALD material may include disposing the ALD material in the undercut region (e.g., on surfaces defining the undercut regions) after forming the undercut region. In some embodiments, forming an undercut region between the resonator material and the semiconductor structure 1 10 includes forming the undercut region using VHF.

[0035] FIG. 8 illustrates an interposer 1000, according to some embodiments. The interposer 1000 is an intervening substrate used to bridge a first substrate 1002 to a second substrate 1004. The first substrate 1002 may be, for instance, an integrated circuit die. The second substrate 1004 may be, for instance, a memory module, a computer motherboard, or another integrated circuit die. In some embodiments, one of the first substrate 1002 or the second substrate 1004 may include the electronic device 100 of FIG. 1 . Generally, the purpose of an interposer 1000 is to spread a connection to a wider pitch or to reroute a connection to a different connection. For example, an interposer 1000 may couple an integrated circuit die to a ball grid array (BGA) 1006 that can subsequently be coupled to the second substrate 1004. In some embodiments, the first and second substrates 1002/1004 are attached to opposing sides of the interposer 1000. In other embodiments, the first and second substrates 1002/1004 are attached to the same side of the interposer 1000. And in further embodiments, three or more substrates are interconnected by way of the interposer 1000.

[0036] The interposer 1000 may be formed of an epoxy resin, a fiberglass-reinforced epoxy resin, a ceramic material, or a polymer material such as polyimide. In further implementations, the interposer may be formed of alternate rigid or flexible materials that may include the same materials described above for use in a semiconductor substrate, such as silicon, germanium, and other group lll-V and group IV materials.

[0037] The interposer may include metal interconnects 1008 and vias 1010, including but not limited to through-silicon vias (TSVs) 1012. The interposer 1000 may further include embedded devices 1014, including both passive and active devices. Such devices include, but are not limited to, capacitors, decoupling capacitors, resistors, inductors, fuses, diodes, transformers, sensors, and electrostatic discharge (ESD) devices. More complex devices such as radio-frequency (RF) devices, power amplifiers, power management devices, antennas, arrays, sensors, and MEMS devices may also be formed on the interposer 1000.

[0038] In accordance with embodiments disclosed herein, apparatuses or processes disclosed herein may be used in the fabrication of interposer 1000.

[0039] FIG. 9 illustrates a computing device 1200, according to some embodiments. The computing device 1200 may include a number of components. In one embodiment, these components are attached to one or more motherboards. In an alternate embodiment, some or all of these components are fabricated onto a single system-on-a-chip (SoC) die, such as an SoC used for mobile devices. The components in the computing device 1200 include, but are not limited to, an integrated circuit die 1202 and at least one communications logic unit 1208. In some implementations the communications logic unit 1208 is fabricated within the integrated circuit die 1202 while in other implementations the communications logic unit 1208 is fabricated in a separate integrated circuit chip that may be bonded to a substrate or motherboard that is shared with or electronically coupled to the integrated circuit die 1202. In some embodiments, the communications logic unit 1208 may include the electronic device 100. By way of non-limiting example, the communications logic unit 1208 may include an RF filter, duplexer, or oscillator including the acoustic device 120 of FIG. 1 . The integrated circuit die 1202 may include a Central Processing Unit (CPU) 1204 as well as on-die memory 1206, often used as cache memory, that can be provided by technologies such as embedded DRAM (eDRAM), SRAM, or spin-transfer torque memory (STT-MRAM).

[0040] Computing device 1200 may include other components that may or may not be physically and electrically coupled to the motherboard or fabricated within an SoC die. These other components include, but are not limited to, volatile memory 1210 (e.g., DRAM), non-volatile memory 1212 (e.g., ROM or flash memory), a graphics processing unit 1214 (GPU), a digital signal processor 1216, a crypto processor 1242 (e.g., a specialized processor that executes cryptographic algorithms within hardware), a chipset 1220, at least one antenna 1222 (in some implementations two or more antenna may be used), a display or a touchscreen display 1224, a

touchscreen controller 1226, a battery 1228 or other power source, a power amplifier (not shown), a voltage regulator (not shown), a global positioning system (GPS) device 1230, a compass, a motion coprocessor or sensors 1232 (that may include an accelerometer, a gyroscope, and a compass), a microphone (not shown), a speaker 1234, a camera 1236, user input devices 1238 (such as a keyboard, mouse, stylus, and touchpad), and a mass storage device 1240 (such as hard disk drive, compact disk (CD), digital versatile disk (DVD), and so forth). The computing device 1200 may incorporate further transmission, telecommunication, or radio functionality not already described herein. In some implementations, the computing device 1200 includes a radio that is used to communicate over a distance by modulating and radiating electromagnetic waves in air or space. In further implementations, the computing device 1200 includes a transmitter and a receiver (or a transceiver) that is used to communicate over a distance by modulating and radiating electromagnetic waves in air or space.

[0041] The communications logic unit 1208 enables wireless communications for the transfer of data to and from the computing device 1200. The term "wireless" and its derivatives may be used to describe circuits, devices, systems, methods, techniques, communications channels, etc., that may communicate data through the use of modulated electromagnetic radiation through a non-solid medium. The term does not imply that the associated devices do not contain any wires, although in some embodiments they might not. The communications logic unit 1208 may implement any of a number of wireless standards or protocols, including but not limited to Wi-Fi (IEEE 802.1 1 family), WiMAX (IEEE 802.16 family), IEEE 802.20, long term evolution (LTE), Ev-DO, HSPA+, HSDPA+, HSUPA+, EDGE, GSM, GPRS, CDMA, TDMA, DECT, Infrared (IR), Near Field Communication (NFC), Bluetooth, derivatives thereof, as well as any other wireless protocols that are designated as 3G, 4G, 5G, and beyond. The computing device 1200 may include a plurality of communications logic units 1208. For instance, a first communications logic unit 1208 may be dedicated to shorter range wireless communications such as Wi-Fi, NFC, and Bluetooth and a second communications logic unit 1208 may be dedicated to longer range wireless communications such as GPS, EDGE, GPRS, CDMA, WiMAX, LTE, Ev-DO, and others.

[0042] In some embodiments, the processor 1204 of the computing device 1200 includes one or more devices, such as the acoustic device 120, the TCF

compensator 130, and the semiconductor structure 1 10, which are formed in accordance with embodiments disclosed herein. By way of non-limiting example, the processor 1204 may include an RF filter, a duplexer, or an oscillator including the acoustic device 120. The term "processor" may refer to any device or portion of a device that processes electronic data from registers and/or memory to transform that electronic data into other electronic data that may be stored in registers and/or memory.

[0043] The communications logic unit 1208 may also include one or more devices, such as RF filters, duplexers, or oscillators, that are formed in accordance with embodiments of the disclosure. By way of non-limiting example, an RF filter, a duplexer, or an oscillator may include the electronic device 100 of FIG. 1 .

[0044] In further embodiments, another component housed within the computing device 1200 may contain one or more devices, such as RF filters, duplexers, oscillators, or mechanical sensors including the electronic device 100 of FIG. 1 , which are formed in accordance with implementations of the disclosure.

[0045] In various embodiments, the computing device 1200 may be a laptop computer, a netbook computer, a notebook computer, an ultrabook computer, a smartphone, a dumbphone, a tablet, a tablet/laptop hybrid, a personal digital assistant (PDA), an ultra mobile PC, a mobile phone, a desktop computer, a server, a printer, a scanner, a monitor, a set-top box, an entertainment control unit, a digital camera, a portable music player, or a digital video recorder. In further implementations, the computing device 1200 may be any other electronic device that processes data.

[0046] A plurality of transistors, such as metal-oxide-semiconductor field-effect transistors (MOSFET or simply MOS transistors), may be fabricated on or in a substrate. In various embodiments, the MOS transistors may be planar transistors, nonplanar transistors, or a combination of both. Nonplanar transistors include FinFET transistors such as double-gate transistors and tri-gate transistors, and wrap-around or all-around gate transistors such as nanoribbon and nanowire transistors.

[0047] Each MOS transistor includes a gate stack formed of at least two layers, a gate dielectric layer and a gate electrode layer. The gate dielectric layer may include one layer or a stack of layers. The one or more layers may include silicon oxide, silicon dioxide (S1O₂) and/or a high-k dielectric material. The high-k dielectric material may include elements such as hafnium, silicon, oxygen, titanium, tantalum, lanthanum, aluminum, zirconium, barium, strontium, yttrium, lead, scandium, niobium, and zinc. Examples of high-k materials that may be used in the gate dielectric layer include, but are not limited to, hafnium oxide, hafnium silicon oxide, lanthanum oxide, lanthanum aluminum oxide, zirconium oxide, zirconium silicon oxide, tantalum oxide, titanium oxide, barium strontium titanium oxide, barium titanium oxide, strontium titanium oxide, yttrium oxide, aluminum oxide, lead scandium tantalum oxide, and lead zinc niobate. In some embodiments, an annealing process may be carried out on the gate dielectric layer to improve its quality when a high-k material is used.

[0048] The gate electrode layer is formed on the gate dielectric layer and may include at least one P-type workfunction metal or N-type workfunction metal, depending on whether the transistor is to be a PMOS or an NMOS transistor. In some implementations, the gate electrode layer may include a stack of two or more metal layers, where one or more metal layers are workfunction metal layers and at least one metal layer is a fill metal layer. Further metal layers may be included for other purposes, such as a barrier layer.

[0049] For a PMOS transistor, metals that may be used for the gate electrode include, but are not limited to, ruthenium, palladium, platinum, cobalt, nickel, and conductive metal oxides, e.g., ruthenium oxide. A P-type metal layer will enable the formation of a PMOS gate electrode with a workfunction that is between about 4.9 eV and about 5.2 eV. For an NMOS transistor, metals that may be used for the gate electrode include, but are not limited to, hafnium, zirconium, titanium, tantalum, aluminum, alloys of these metals, and carbides of these metals such as hafnium carbide, zirconium carbide, titanium carbide, tantalum carbide, and aluminum carbide. An N-type metal layer will enable the formation of an NMOS gate electrode with a workfunction that is between about 3.9 eV and about 4.2 eV.

[0050] In some implementations, when viewed as a cross-section of the transistor along the source-channel-drain direction, the gate electrode may consist of a

U-shaped structure that includes a bottom portion substantially parallel to the surface of the substrate and two sidewall portions that are substantially perpendicular to the top surface of the substrate. In another implementation, at least one of the metal layers that form the gate electrode may simply be a planar layer that is substantially parallel to the top surface of the substrate and does not include sidewall portions substantially perpendicular to the top surface of the substrate. In further

embodiments, the gate electrode may consist of a combination of U-shaped structures and planar, non-U-shaped structures. For example, the gate electrode may consist of one or more U-shaped metal layers formed atop one or more planar, non-U-shaped layers.

[0051] In some embodiments, a pair of sidewall spacers may be formed on opposing sides of the gate stack that bracket the gate stack. The sidewall spacers may be formed from a material such as silicon nitride, silicon oxide, silicon carbide, silicon nitride doped with carbon, and silicon oxynitride. Processes for forming sidewall spacers are well known in the art and generally include deposition and etching process steps. In an alternate implementation, a plurality of spacer pairs may be used, for instance, two pairs, three pairs, or four pairs of sidewall spacers may be formed on opposing sides of the gate stack.

[0052] As is well known in the art, source and drain regions are formed within the substrate adjacent to the gate stack of each MOS transistor. The source and drain regions are generally formed using either an implantation/diffusion process or an etching/deposition process. In the former process, dopants such as boron, aluminum, antimony, phosphorous, or arsenic may be ion-implanted into the substrate to form the source and drain regions. An annealing process that activates the dopants and causes them to diffuse further into the substrate typically follows the ion implantation process. In the latter process, the substrate may first be etched to form recesses at the locations of the source and drain regions. An epitaxial deposition process may then be carried out to fill the recesses with material that is used to fabricate the source and drain regions. In some implementations, the source and drain regions may be fabricated using a silicon alloy such as silicon germanium or silicon carbide. In some implementations the epitaxially deposited silicon alloy may be doped in situ with dopants such as boron, arsenic, or phosphorous. In further embodiments, the source and drain regions may be formed using one or more alternate semiconductor materials such as germanium or a group lll-V material or alloy. And in further embodiments, one or more layers of metal and/or metal alloys may be used to form the source and drain regions.

[0053] One or more interlayer dielectrics (ILD) are deposited over the MOS

transistors. The ILD layers may be formed using dielectric materials known for their applicability in integrated circuit structures, such as low-k dielectric materials.

Examples of dielectric materials that may be used include, but are not limited to, silicon dioxide (SiO₂), carbon doped oxide (CDO), silicon nitride, organic polymers such as perfluorocyclobutane or polytetrafluoroethylene, fluorosilicate glass (FSG), and organosilicates such as silsesquioxane, siloxane, or organosilicate glass. The ILD layers may include pores or air gaps to further reduce their dielectric constant.

Examples

[0054] A non-exhausted list of example embodiments follows. Not all of these example embodiments are expressly indicated herein as being combinable with others of the example embodiments in the list and other embodiments disclosed hereinabove. It is contemplated herein, however, that such embodiments are combinable unless expressly indicated otherwise or unless it would be understood by one of ordinary skill in the art that such embodiments are not combinable.

[0055] Example 1 : An electronic device, comprising: a semiconductor structure; an acoustic device on or in the semiconductor structure, the acoustic device including a resonator material having a Temperature Coefficient of resonant Frequency (TCF); and a TCF compensation material disposed proximate to the resonator material and including an Atomic Layer Deposition (ALD) material having a compensating TCF that at least substantially compensates for the TCF of the resonator material, the ALD material having a thickness that is less than or equal to about ten nanometers (10 nm). [0056] Example 2: The electronic device of Example 1 , wherein the ALD material includes titanium dioxide (T1O2).

[0057] Example 3: The electronic device according to any one of Examples 1 and 2, wherein the ALD material includes at least one material selected from the group consisting of silicon oxide (SiO), silicon dioxide (S1O2), aluminum oxide (AI2O3), and hafnium oxide (HfO2).

[0058] Example 4: The electronic device according to any one of Examples 1 -3, wherein the ALD material includes at least two materials selected from the group consisting of titanium dioxide (T1O2), silicon oxide (SiO), silicon dioxide (S1O2), aluminum oxide (AI2O3), and hafnium oxide (HfO2).

[0059] Example 5: The electronic device according to any one of Examples 1 -4, wherein the ALD material conforms to the acoustic device.

[0060] Example 6: The electronic device according to any one of Examples 1 -5, wherein at least a portion of the ALD material is disposed in an undercut region proximate to the acoustic device.

[0061] Example 7: The electronic device according to any one of Examples 1 -6, wherein the acoustic device includes a Film Bulk Acoustic Resonator (FBAR).

[0062] Example 8: The electronic device according to any one of Examples 1 -7, wherein the acoustic device includes a Surface Acoustic Wave (SAW) resonator.

[0063] Example 9: The electronic device according to any one of Examples 1 -8, wherein the acoustic device includes a Contour Mode Resonator (CMR).

[0064] Example 10: The electronic device according to any one of Examples 1 -9, wherein the TCF of the resonator material is negative and a TCF of the ALD material is positive.

[0065] Example 1 1 : The electronic device according to any one of Examples 1 -10, wherein the resonator material includes one of aluminum nitride (AIN), lithium tantalate (LT), or lithium niobate (LN).

[0066] Example 12: A method of forming an electronic device, the method

comprising: disposing a resonator material having a Temperature Coefficient of resonant Frequency (TCF) onto or into a semiconductor structure; and disposing, using Atomic Layer Deposition (ALD), an ALD material proximate to the resonator material, the ALD material having a compensating TCF that compensates for the TCF of the resonator material. [0067] Example 13: The method of Example 12, further comprising forming an undercut region between the resonator material and the semiconductor structure, wherein disposing an ALD material includes disposing the ALD material in the undercut region after forming the undercut region.

[0068] Example 14: The method of Example 13, wherein forming an undercut region between the resonator material and the semiconductor structure comprises forming the undercut region using vapor hydrogen fluoride (VHF).

[0069] Example 15: The method according to any one of Examples 12-14, wherein disposing an ALD material includes disposing the ALD material on at least one electrode of an acoustic device including the resonator material.

[0070] Example 16: A computing device, comprising: a communication unit including: a semiconductor structure; an acoustic device including a piezoelectric material and at least one electrode disposed on or in the semiconductor structure; and an Atomic Layer Deposition (ALD) material having a thickness of about ten nanometers (10 nm) or less disposed proximate to the acoustic device, the ALD material configured to compensate for a Temperature Coefficient of resonant Frequency (TCF) of the piezoelectric material.

[0071] Example 17: The computing device of Example 16, further comprising: a processor mounted on a substrate; a memory unit capable of storing data; a graphics processing unit; an antenna within the computing device; a display on the computing device; a battery within the computing device; a power amplifier within the processor; and a voltage regulator within the processor.

[0072] Example 18: The computing device of Example 16, further comprising a processor including the communication unit.

[0073] Example 19: The computing device according to any one of Examples 16-18, wherein the ALD material includes titanium dioxide (T1O2).

[0074] Example 20: The computing device according to any one of Examples 16-19, wherein the acoustic device includes one of a Film Bulk Acoustic Resonator (FBAR), a Contour Mode Resonator (CMR), or a Surface Acoustic Wave (SAW) resonator.

[0075] Example 21 : A method of manufacturing an electronic device, the method comprising: disposing an acoustic device on or in a semiconductor structure, the acoustic device including a resonator material having a Temperature Coefficient of resonant Frequency (TCF); and disposing a TCF compensation material proximate to the resonator material using Atomic Layer Deposition (ALD), the TCF compensation material including an ALD material having a compensating TCF that at least substantially compensates for the TCF of the resonator material, the ALD material having a thickness that is less than or equal to about ten nanometers (10 nm).

[0076] Example 22: The method of Example 21 , wherein disposing a TCF

compensation material including an ALD material includes disposing titanium dioxide (Ti0₂) using ALD.

[0077] Example 23: The method according to any one of Examples 21 and 22, wherein disposing a TCF compensation material including an ALD material includes disposing at least one material selected from the group consisting of silicon oxide (SiO), silicon dioxide (Si0₂), aluminum oxide (AI20₃), and hafnium oxide (Hf0₂) using ALD.

[0078] Example 24: The method according to any one of Examples 21 -23, wherein disposing a TCF compensation material including an ALD material includes disposing at least two materials selected from the group consisting of titanium dioxide (T1O2), silicon oxide (SiO), silicon dioxide (S1O2), aluminum oxide (AI2O3), and hafnium oxide (HfO2) using ALD.

[0079] Example 25: The method according to any one of Examples 21 -24, wherein disposing a TCF compensation material including an ALD material includes conforming the ALD material to the acoustic device.

[0080] Example 26: The method according to any one of Examples 21 -25, wherein disposing a TCF compensation material including an ALD material includes disposing at least a portion of the ALD material disposed in an undercut region proximate to the acoustic device using ALD.

[0081] Example 27: The method according to any one of Examples 21 -26, wherein disposing an acoustic device includes disposing a Film Bulk Acoustic Resonator (FBAR).

[0082] Example 28: The method according to any one of Examples 21 -27, wherein disposing an acoustic device includes disposing a Surface Acoustic Wave (SAW) resonator.

[0083] Example 29: The method according to any one of Examples 21 -28, wherein disposing an acoustic device includes disposing a Contour Mode Resonator (CMR).

[0084] Example 30: The method according to any one of Examples 21 -29, wherein disposing an acoustic device includes disposing a material having a negative TCF, and disposing a TCF compensation material including an ALD material includes disposing a material having a positive TCF.

[0085] Example 31 : The method according to any one of Examples 21 -30, wherein disposing an acoustic device including a resonator material includes disposing at least one of aluminum nitride (AIN), lithium tantalate (LT), or lithium niobate (LN).

[0086] Example 32: An electronic device comprising: a resonator material having a Temperature Coefficient of resonant Frequency (TCF) on or in a semiconductor structure; and an Atomic Layer Deposition (ALD) material proximate to the resonator material, the ALD material having a compensating TCF that compensates for the TCF of the resonator material.

[0087] Example 33: The electronic device of Example 32, wherein at least a portion of the ALD material is disposed in an undercut region between the resonator material and the semiconductor structure.

[0088] Example 34: The electronic device of Example 33, wherein the undercut region between the resonator material and the semiconductor structure is formed using vapor hydrogen fluoride (VHF).

[0089] Example 35: The electronic device according to any one of Examples 32-34, wherein the ALD material is disposed on at least one electrode of an acoustic device including the resonator material.

[0090] Example 36: A method of operating a computing device, the method

comprising: operating a communication unit including: a semiconductor structure; an acoustic device including a piezoelectric material and at least one electrode disposed on or in the semiconductor structure; and an Atomic Layer Deposition (ALD) material having a thickness of about ten nanometers (10 nm) or less disposed proximate to the acoustic device, the ALD material configured to compensate for a Temperature Coefficient of resonant Frequency (TCF) of the piezoelectric material.

[0091] Example 37: The method of Example 36, further comprising: operating a processor mounted on a substrate; operating a memory unit capable of storing data; operating a graphics processing unit; operating an antenna within the computing device; operating a display on the computing device; operating a battery within the computing device; operating a power amplifier within the processor; and operating a voltage regulator within the processor.

[0092] Example 38: The method of Example 16, wherein operating a communication unit includes operating a processor including the communication unit. [0093] Example 39: The method according to any one of Examples 16-18, wherein operating a communication unit includes operating the communication unit wherein the ALD material includes titanium dioxide (Ti0₂).

[0094] Example 40: The method according to any one of Examples 16-18, wherein operating a communication unit includes one of a Film Bulk Acoustic Resonator (FBAR), a Contour Mode Resonator (CMR), or a Surface Acoustic Wave (SAW) resonator.

[0095] Example 41 : A means for performing at least a portion of the method according to any one of Examples 12-15, 21 -31 , and 36-40.

Conclusion

[0096] The above description of illustrated embodiments, including what is described in the Abstract, is not intended to be exhaustive or to limit the disclosure to the precise forms disclosed. While specific implementations, embodiments, and examples are described herein for illustrative purposes, various equivalent modifications are possible within the scope of the disclosure, as those skilled in the relevant art will recognize.

Claims

1 . An electronic device, comprising:

a semiconductor structure;

an acoustic device on or in the semiconductor structure, the acoustic device including a resonator material having a Temperature Coefficient of resonant

Frequency (TCF); and

a TCF compensation material disposed proximate to the resonator material and including an Atomic Layer Deposition (ALD) material having a compensating TCF that at least substantially compensates for the TCF of the resonator material, the ALD material having a thickness that is less than or equal to about ten

nanometers (10 nm).

2. The electronic device of claim 1 , wherein the ALD material includes titanium dioxide (T1O2).

3. The electronic device of claim 1 , wherein the ALD material includes at least one material selected from the group consisting of silicon oxide (SiO), silicon dioxide (S1O2), aluminum oxide (AI2O3), and hafnium oxide (HfO2).

4. The electronic device of claim 1 , wherein the ALD material includes at least two materials selected from the group consisting of titanium dioxide (T1O2), silicon oxide (SiO), silicon dioxide (S1O2), aluminum oxide (AI2O3), and hafnium oxide (Hf0₂).

5. The electronic device according to any one of claims 1 -4, wherein the ALD material conforms to the acoustic device.

6. The electronic device according to any one of claims 1 -4, wherein at least a portion of the ALD material is disposed in an undercut region proximate to the acoustic device.

7. The electronic device according to any one of claims 1 -4, wherein the acoustic device includes a Film Bulk Acoustic Resonator (FBAR).

8. The electronic device according to any one of claims 1 -4, wherein the acoustic device includes a Surface Acoustic Wave (SAW) resonator.

9. The electronic device according to any one of claims 1 -4, wherein the acoustic device includes a Contour Mode Resonator (CMR).

10. The electronic device according to any one of claims 1 -4, wherein the TCF of the resonator material is negative and a TCF of the ALD material is positive.

1 1 . The electronic device according to any one of claims 1 -4, wherein the resonator material includes one of aluminum nitride (AIN), lithium tantalate (LT), or lithium niobate (LN).

12. A method of forming an electronic device, the method comprising:

disposing a resonator material having a Temperature Coefficient of resonant

Frequency (TCF) onto or into a semiconductor structure; and

disposing, using Atomic Layer Deposition (ALD), an ALD material proximate to the resonator material, the ALD material having a compensating TCF that compensates for the TCF of the resonator material.

13. The method of claim 12, further comprising forming an undercut region between the resonator material and the semiconductor structure, wherein disposing an ALD material includes disposing the ALD material in the undercut region after forming the undercut region.

14. The method of claim 13, wherein forming an undercut region between the resonator material and the semiconductor structure comprises forming the undercut region using vapor hydrogen fluoride (VHF).

15. The method according to any one of claims 12-14, wherein disposing an ALD material includes disposing the ALD material on at least one electrode of an acoustic device including the resonator material.

16. A computing device, comprising:

a communication unit including:

a semiconductor structure;

an acoustic device including a piezoelectric material and at least one electrode disposed on or in the semiconductor structure; and

an Atomic Layer Deposition (ALD) material having a thickness of about ten nanometers (10 nm) or less disposed proximate to the acoustic device, the ALD material configured to compensate for a Temperature Coefficient of resonant Frequency (TCF) of the piezoelectric material.

17. The computing device of claim 16, further comprising:

a processor mounted on a substrate;

a memory unit capable of storing data;

a graphics processing unit;

an antenna within the computing device;

a display on the computing device; a battery within the computing device;

a power amplifier within the processor; and

a voltage regulator within the processor.

18. The computing device of claim 16, further comprising a processor including the communication unit.

19. The computing device according to any one of claims 16-18, wherein the ALD material includes titanium dioxide (Ti0₂).

20. The computing device according to any one of claims 16-18, wherein the acoustic device includes one of a Film Bulk Acoustic Resonator (FBAR), a Contour Mode Resonator (CMR), or a Surface Acoustic Wave (SAW) resonator.