Patent Description:
A variety of different types of sensors are being used in portable, mobile devices and computing devices in general. Conventional approaches for temperature sensors include substrate temperature measurement techniques including resistance temperature detectors (RTDs). Those sensors tend to consume relatively large areas (~ <NUM> mm2) which limits the quantity of RTDs that can be deployed, and in some cases eliminates the possibility of including any RTDs in products where form factor is very constrained. Another approach includes electromagnetic transduction which requires assembly of components such as permanent magnets to a substrate. Documents <CIT> and <CIT> describe known temperature sensing devices.

Described herein are piezoelectric package integrated temperature sensing devices. In the following description, various aspects of the illustrative implementations will be described using terms commonly employed by those skilled in the art to convey the substance of their work to others skilled in the art. However, it will be apparent to those skilled in the art that the present invention 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 implementations. However, it will be apparent to one skilled in the art that the present invention may be practiced without the specific details. In other instances, well-known features are omitted or simplified in order to not obscure the illustrative implementations.

Various operations will be described as multiple discrete operations, in turn, in a manner that is most helpful in understanding the present invention. However, the order 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.

The present design includes an architecture that allows in-situ fabrication of temperature sensing devices in a compact form factor on package substrates using organic panel-level (e.g., approximately <NUM> x <NUM> sized panels) high volume manufacturing technology, without requiring the assembly of external bulky components or expensive Si MEMS fabrication.

The present design provides thin, low cost temperature sensors that are manufactured as part of an organic package substrate traditionally used to route signals between the CPU or other die and the board. These temperature sensors can be made very compact and hence can be placed in multiple substrate locations to provide a spatial temperature map of the substrate. The sensors can be used to enhance thermal management and also for the calibration of other kinds of sensors that are temperature sensitive, such as accelerometers and gyroscopes.

In one example, the temperature sensor package has a z-axis height that is significantly less than conventional approaches. Moreover, since these temperature sensors are built using organic panel-level substrate technology, they can be manufactured more cost effectively than using a silicon-based wafer approach. The present design also eliminates the need for a magnet which is required for some electromagnetic transduction approaches for temperature sensors.

In one example, the present design includes package-integrated structures to act as temperature sensing devices. Those structures are manufactured as part of the package layers and are made free to vibrate or move by removing the dielectric material around them. The structures include piezoelectric stacks that are deposited and patterned layer-by-layer into the package. The present design includes creating temperature sensing devices in the package on the principle of suspended and vibrating structures. Etching of the dielectric material in the package occurs to create cavities. Piezoelectric material deposition (e.g., <NUM> to <NUM> deposition thickness) and crystallization also occurs in the package substrate during the package fabrication process. An annealing operation at a substrate temperature range (e.g., up to <NUM> C) that is lower than typically used for piezoelectric material annealing allows crystallization of the piezoelectric material (e.g., lead zirconate titanate (PZT), potassium sodium niobate (KNN), aluminum nitride (AlN), zinc oxide (ZnO), etc) to occur during the package fabrication process without imparting thermal degradation or damage to the substrate layers. In one example, laser pulsed annealing occurs locally with respect to the piezoelectric material without damaging other layers of the package substrate (e.g., organic substrate) including organic layers.

Referring now to <FIG>, a view of a microelectronic device <NUM> having package-integrated piezoelectric temperature sensing devices is shown, according to an embodiment. In one example, the microelectronic device <NUM> includes multiple devices <NUM> and <NUM> (e.g., die, chip, CPU, silicon die or chip, radio transceiver, etc.) that are coupled or attached to a package substrate <NUM> with solder balls <NUM>-<NUM>, <NUM>-<NUM>. The package substrate <NUM> is coupled or attached to the printed circuit board (PCB) <NUM> using, for example, solder balls <NUM> through <NUM>.

The package substrate <NUM> (e.g., organic substrate) includes organic dielectric layers <NUM> and conductive layers <NUM>-<NUM>, <NUM>, <NUM>, <NUM>, and <NUM>. Organic materials may include any type of organic material such as flame retardant <NUM> (FR4), resin-filled polymers, prepreg (e.g., pre impregnated, fiber weave impregnated with a resin bonding agent) polymers, silica-filled polymers, etc. The package substrate <NUM> can be formed during package substrate processing (e.g., at panel level). The panels formed can be large (e.g., having in-plane (x, y) dimensions of approximately <NUM> meter by <NUM> meter, or greater than <NUM> meter, etc.) for lower cost. A cavity <NUM> is formed within the packaging substrate <NUM> by removing one or more layers (e.g., organic layers, dielectric layers, etc.) from the packaging substrate <NUM>. The cavity <NUM> includes a lower member <NUM> and sidewalls <NUM>-<NUM>. In one example, a piezoelectric vibrating device <NUM> (e.g., temperature sensing device <NUM>) is formed with input transducer <NUM>, output transducer <NUM>, and base structure <NUM> (e.g., beams, traces, etc.). The input transducer <NUM> includes a conductive structure <NUM>, piezoelectric material <NUM>, and a region <NUM> of the base structure that contacts the piezoelectric material <NUM>. The three structures <NUM>, <NUM>, and <NUM> form a piezoelectric stack. The conductive structure <NUM> can act as a first electrode and the region <NUM> of the conductive movable base structure <NUM> can act as a second electrode of the input transducer. The output transducer <NUM> includes a conductive structure <NUM>, piezoelectric material <NUM>, and a region <NUM> of the base structure that contacts the piezoelectric material <NUM>. The three structures <NUM>, <NUM>, and <NUM> form a piezoelectric stack. The conductive structure <NUM> can act as a first electrode and the region <NUM> of the conductive movable base structure <NUM> can act as a second electrode of the output transducer. The cavity <NUM> can be air filled or vacuum filled. The conductive base structure <NUM> is anchored by package connections <NUM> and <NUM> (e.g., anchors, vias) which may serve as both mechanical anchors as well as electrical connections to the rest of the package. The conductive structures <NUM> and <NUM> are anchored by package connections <NUM> and <NUM> (e.g., anchors, vias), respectively, which may serve as both mechanical anchors as well as electrical connections to the rest of the package.

The base structure <NUM> is released by removing the dielectric material surrounding it to allow the base structure to move. The piezoelectric material <NUM> and <NUM> are used to form two electromechanical transducers <NUM> and <NUM> that are mechanically coupled to the base structure <NUM>. The input transducer <NUM> is excited by applying a time varying (e.g., AC) voltage to the piezoelectric material <NUM> which causes it to deform. This causes vibrations of the base structure <NUM> that are transmitted to the output transducer <NUM>, generating an electrical output signal. By using a feedback loop (e.g., phase locked loop located in a main die of the package substrate, a separate die, etc.), a mechanical resonant frequency of the temperature sensing device <NUM> can be determined. When an ambient temperature changes, the base structure experiences induced thermomechanical stresses which change the mechanical resonant frequency of the device <NUM>. This shift in frequency is detected in the output electrical signals of the transducer <NUM> and is used to correlate with an amount of temperature change.

<FIG> illustrates a top view of a package substrate having a package-integrated piezoelectric temperature sensing device, according to an embodiment. In one example, the package substrate <NUM> may be coupled or attached to multiple devices (e.g., die, chip, CPU, silicon die or chip, RF transceiver, etc.) and may also be coupled or attached to a printed circuit board (e.g., PCB <NUM>). The package substrate <NUM> (e.g., organic substrate) includes organic dielectric layers <NUM> and conductive layers <NUM>-<NUM>, <NUM>, <NUM>, and <NUM>. The package substrate <NUM> can be formed during package substrate processing (e.g., at panel level). A cavity <NUM> is formed within the packaging substrate <NUM> by removing one or more layers (e.g., organic layers, dielectric layers, etc.) from the packaging substrate <NUM>. In one example, a piezoelectric vibrating device (e.g., temperature sensing device) is formed with input transducer <NUM>, output transducer <NUM>, and base structure <NUM> (e.g., beams, traces, etc.).

<FIG> illustrates a side view of a package substrate having a package-integrated piezoelectric device (e.g., temperature sensing device), according to an embodiment. The package substrate <NUM> (e.g., organic substrate) includes organic dielectric layers <NUM> (or layers <NUM>) and conductive layers <NUM>-<NUM>, <NUM>, <NUM>, and <NUM>. The package substrate <NUM> can be formed during package substrate processing (e.g., at panel level). The package substrate <NUM> may be a cross-sectional view AA of the package substrate <NUM>.

In one example, the package substrate <NUM> may be coupled or attached to multiple devices (e.g., die, chip, CPU, silicon die or chip, RF transceiver, etc.) and may also be coupled or attached to a printed circuit board (e.g., PCB <NUM>). A cavity <NUM> is formed within the packaging substrate <NUM> by removing one or more layers (e.g., organic layers, dielectric layers, etc.) from the packaging substrate <NUM>. In one example, a piezoelectric vibrating device <NUM> (e.g., temperature sensing device <NUM>) is formed with input transducer <NUM>, output transducer <NUM>, and base structure <NUM> (e.g., beams, traces, etc.). In one example, the base structure includes a beam length of <NUM> to <NUM> and a beam width of <NUM> to <NUM>. The input transducer <NUM> includes a conductive structure <NUM>, piezoelectric material <NUM>, and a region <NUM> of the base structure that contacts the piezoelectric material <NUM>. The three structures <NUM>, <NUM>, and <NUM> form a piezoelectric stack <NUM>. The conductive structure <NUM> can act as a first electrode and the region <NUM> of the conductive movable base structure <NUM> can act as a second electrode of the input transducer. The output transducer <NUM> includes a conductive structure <NUM>, piezoelectric material <NUM>, and a region <NUM> of the base structure that contacts the piezoelectric material <NUM>. The three structures <NUM>, <NUM>, and <NUM> form a piezoelectric stack <NUM>. The conductive structure <NUM> can act as a first electrode and the region <NUM> of the conductive movable base structure <NUM> can act as a second electrode of the output transducer. The cavity <NUM> can be air filled or vacuum filled. The conductive base structure <NUM> is anchored by package connections <NUM> and <NUM> (e.g., anchors, vias) which may serve as both mechanical anchors as well as electrical connections to the rest of the package. The conductive structures <NUM> and <NUM> are anchored by package connections <NUM> and <NUM> (e.g., anchors, vias), respectively, which may serve as both mechanical anchors as well as electrical connections to the rest of the package.

In one embodiment, the piezoelectric transducers <NUM> and <NUM> are deposited and patterned such that they are mechanically coupled to the base structure <NUM>. Each stack <NUM> and <NUM> includes a piezoelectric material such as PZT, KNN, ZnO, or other materials sandwiched between conductive electrodes. The base structure <NUM> itself can be used as one of the electrodes in each stack as shown in <FIG>, or alternatively, a separate conductive material (e.g., electrodes <NUM>, <NUM>) can be used for that lower electrode after depositing an insulating layer (e.g., <NUM>, <NUM>) to electrically decouple this lower electrode from the base structure <NUM> as illustrated in <FIG> illustrates a side view of a package substrate having a package-integrated piezoelectric device (e.g., temperature sensing device), according to another embodiment. The package substrate <NUM> (e.g., organic substrate) includes organic dielectric layers <NUM> (or layers <NUM>) and conductive layers. A cavity <NUM> is formed within the packaging substrate <NUM> by removing one or more layers (e.g., organic layers, dielectric layers, etc.) from the packaging substrate <NUM>. In one example, a piezoelectric vibrating device <NUM> (e.g., temperature sensing device <NUM>) is formed with input transducer <NUM>, output transducer <NUM>, and base structure <NUM> (e.g., beams, traces, etc.). The input transducer <NUM> includes a conductive structure <NUM>, piezoelectric material <NUM>, and a conductive structure <NUM> that is electrically isolated from the base structure <NUM> with insulating layer <NUM>. The three structures <NUM>, <NUM>, and <NUM> form a piezoelectric stack. The conductive structure <NUM> can act as a first electrode and the conductive structure <NUM> of the conductive movable base structure <NUM> can act as a second electrode of the input transducer <NUM>. The output transducer <NUM> includes a conductive structure <NUM>, piezoelectric material <NUM>, and a conductive structure <NUM> that is electrically isolated from the base structure <NUM> with insulating layer <NUM>. The three structures <NUM>, <NUM>, and <NUM> form a piezoelectric stack. The conductive structure <NUM> can act as a first electrode and the conductive structure <NUM> of the conductive movable base structure <NUM> can act as a second electrode of the input transducer <NUM>.

Although piezoelectric films typically require very high crystallization temperatures that are not compatible with organic substrates, the present design includes a process that allows the deposition and crystallization of high quality piezoelectric films without heating the organic layers to temperatures that would cause their degradation. This novel process enables the integration of piezoelectric films directly in the package substrate.

Other embodiments include using a base structure that is not a straight beam in order to attain a different range for the central frequency of the device and/or the temperature sensitivity, or to improve the reliability of the structure. Some examples of alternative embodiments are shown in <FIG> (meandered base) and <FIG> (tapered base).

<FIG> illustrates a top view of a package substrate having a package-integrated piezoelectric temperature sensing device with a meandered base structure design, according to an embodiment. In one example, the package substrate <NUM> may be coupled or attached to multiple devices (e.g., die, chip, CPU, silicon die or chip, RF transceiver, etc.) and may also be coupled or attached to a printed circuit board (e.g., PCB <NUM>). The package substrate <NUM> (e.g., organic substrate) includes organic dielectric layers <NUM> and conductive layers <NUM>, <NUM>, and <NUM>. The package substrate <NUM> can be formed during package substrate processing (e.g., at panel level). A cavity <NUM> is formed within the packaging substrate <NUM> by removing one or more layers (e.g., organic layers, dielectric layers, etc.) from the packaging substrate <NUM>. In one example, a piezoelectric vibrating device <NUM> (e.g., temperature sensing device <NUM>) is formed with input transducer <NUM>, output transducer <NUM>, and base structure <NUM> (e.g., beams, traces, etc.) with meandering beam portion <NUM> having an increased length in comparison to a straight line beam structure. The increased length of the beam structure can help improve the sensitivity of the device.

<FIG> illustrates a top view of a package substrate having a package-integrated piezoelectric temperature sensing device with a tapered base structure design, according to an embodiment. In one example, the package substrate <NUM> may be coupled or attached to multiple devices (e.g., die, chip, CPU, silicon die or chip, RF transceiver, etc.) and may also be coupled or attached to a printed circuit board (e.g., PCB <NUM>). The package substrate <NUM> (e.g., organic substrate) includes organic dielectric layers <NUM> and conductive layers <NUM>, <NUM>, and <NUM>. The package substrate <NUM> can be formed during package substrate processing (e.g., at panel level). A cavity <NUM> is formed within the packaging substrate <NUM> by removing one or more layers (e.g., organic layers, dielectric layers, etc.) from the packaging substrate <NUM>. In one example, a piezoelectric vibrating device <NUM> (e.g., temperature sensing device <NUM>) is formed with input transducer <NUM>, output transducer <NUM>, and base structure <NUM> (e.g., beams, traces, etc.) with tapered beam portions <NUM> and <NUM>.

In an alternative embodiment, the input and output transducers can be manufactured on opposite sides of the base structure in a vertical direction, as shown in <FIG> illustrates a side cross-sectional view of a package substrate having a package-integrated piezoelectric temperature sensing device with a base structure being a common electrode for input and output transducers, according to an embodiment. In one example, the package substrate <NUM> may be coupled or attached to multiple devices (e.g., die, chip, CPU, silicon die or chip, RF transceiver, etc.) and may also be coupled or attached to a printed circuit board (e.g., PCB <NUM>). The package substrate <NUM> (e.g., organic substrate) includes organic dielectric layers <NUM> and conductive layers <NUM>, <NUM>, and <NUM>. The package substrate <NUM> can be formed during package substrate processing (e.g., at panel level). A cavity <NUM> is formed within the packaging substrate <NUM> by removing one or more layers (e.g., organic layers, dielectric layers, etc.) from the packaging substrate <NUM>. In one example, a piezoelectric vibrating device <NUM> (e.g., temperature sensing device <NUM>) is formed with input transducer <NUM>, output transducer <NUM>, and base structure <NUM> (e.g., beams, traces, etc.) which functions as common electrode for the input and output transducers. The input transducer <NUM> includes an input electrode <NUM>, a piezoelectric material <NUM>, and common electrode <NUM>. The output transducer <NUM> includes an output electrode <NUM>, a piezoelectric material <NUM>, and common electrode <NUM>. In this common electrode example, a larger area of the electrodes contacts the piezoelectric material <NUM> and <NUM> in comparison to other embodiments that do not have a common electrode. Thus, the base structure can be actuated with smaller input signals.

<FIG> illustrates a method of operating a package-integrated temperature sensing device in accordance with one embodiment. At operation <NUM>, a temperature sensing device (e.g., temperature sensor, temperature sensing devices <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, etc.) of the present design operates initially with an input transducer being excited by applying a time varying (e.g., AC) voltage between the input electrodes, which causes the piezoelectric material between the electrodes to deform. In response to this deformation, induce vibrations in the base structure that are transmitted to an output transducer at operation <NUM>. Due to the piezoelectric material in the output transducer, those transmitted vibrations generate an output electrical signal between the output electrodes of the output transducer at block <NUM>. A feedback loop (e.g., phase locked loop, control circuitry) can be used to determine a mechanical resonant frequency of the temperature sensing device, for example, by applying input signals with different frequencies to the input transducer and monitoring output signals of the output transducer to determine a maximum amplitude of generated output signal at operation <NUM>. A frequency of the input signals that corresponds to the maximum amplitude of the output signals indicates a mechanical resonant frequency of the temperature sensing device. Then, when a local ambient temperature changes at operation <NUM>, the mechanical resonant frequency of the temperature sensing device changes because of induced thermomechanical stresses (e.g., a beam structure expands or contracts in response to a change in temperature). At operation <NUM>, a change in resonant frequency is measured using the electrical signals as described above (e.g., operations <NUM>, <NUM>) and the change in resonant frequency is used to determine the corresponding temperature change.

The components (e.g., structures, base structures, cavities, etc.) illustrated in various figures of the present design generally have rectangular shapes though it is appreciated that these components can have any type of shape or configuration.

It will be appreciated that, in a system on a chip example not forming part of the claimed invention, the die may include a processor, memory, communications circuitry and the like. Though a single die is illustrated, there may be none, one or several dies included in the same region of the microelectronic device.

In one example not forming part of the claimed invention, the microelectronic device may be a crystalline substrate formed using a bulk silicon or a silicon-on-insulator substructure. In other examples not forming part of the claimed invention, the microelectronic device may be formed using alternate 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 III-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 can be used.

According to an example not forming part of the claimed invention, the microelectronic device may be one of a plurality of microelectronic devices formed on a larger substrate, such as, for example, a wafer. In an embodiment, the microelectronic device may be a wafer level chip scale package (WLCSP). In certain embodiments, the microelectronic device may be singulated from the wafer subsequent to packaging operations, such as, for example, the formation of one or more piezoelectric vibrating devices.

One or more contacts may be formed on a surface of the microelectronic device. The contacts may include one or more conductive layers. By way of example, the contacts may include barrier layers, organic surface protection (OSP) layers, metallic layers, or any combination thereof. The contacts may provide electrical connections to active device circuitry (not shown) within the die. Embodiments of the invention include one or more solder bumps or solder joints that are each electrically coupled to a contact. The solder bumps or solder joints may be electrically coupled to the contacts by one or more redistribution layers and conductive vias.

<FIG> illustrates a computing device <NUM> in accordance with one embodiment of the invention. The computing device <NUM> houses a board <NUM>. The board <NUM> may include a number of components, including but not limited to a processor <NUM> and at least one communication chip <NUM>. The processor <NUM> is physically and electrically coupled to the board <NUM>. In some implementations the at least one communication chip <NUM> is also physically and electrically coupled to the board <NUM>. In further implementations, the communication chip <NUM> is part of the processor <NUM>.

Depending on its applications, computing device <NUM> may include other components that may or may not be physically and electrically coupled to the board <NUM>. These other components include, but are not limited to, volatile memory (e.g., DRAM <NUM>, <NUM>), non-volatile memory (e.g., ROM <NUM>), flash memory, a graphics processor <NUM>, a digital signal processor, a crypto processor, a chipset <NUM>, an antenna <NUM>, a display, a touchscreen display <NUM>, a touchscreen controller <NUM>, a battery <NUM>, an audio codec, a video codec, a power amplifier <NUM>, a global positioning system (GPS) device <NUM>, a compass <NUM>, a piezoelectric device <NUM> (e.g., a piezoelectric temperature sensing device), a gyroscope, a speaker, a camera <NUM>, and a mass storage device (such as hard disk drive, compact disk (CD), digital versatile disk (DVD), and so forth).

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 nonsolid medium. For instance, a first communication chip <NUM> may be dedicated to shorter range wireless communications such as Wi-Fi, WiGig and Bluetooth and a second communication chip <NUM> may be dedicated to longer range wireless communications such as GPS, EDGE, GPRS, CDMA, WiMAX, LTE, Ev-DO, <NUM>, and others.

Claim 1:
An organic package substrate (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) comprising:
a cavity (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) formed within the organic package substrate (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>); and
a package-integrated piezoelectric temperature sensing device (<NUM>), comprising:
a base structure (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) that is positioned in proximity to the cavity (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>);
an input transducer (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) coupled to the base structure (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>), the input transducer (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) having a first piezoelectric material (<NUM>, <NUM>, <NUM>) to generate vibrations which are transmitted on the base structure (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) in response to input signals being applied to the input transducer (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>); and
an output transducer (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) coupled to the base structure (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>), wherein the output transducer (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) has a second piezoelectric material (<NUM>, <NUM>, <NUM>) to receive the vibrations and to generate output signals which are used to determine a change in ambient temperature.