Patent Description:
Document <CIT> discloses a power semiconductor module including a power semiconductor chip arranged between a first substrate and a second substrate and electrically coupled to the substrates, and a temperature sensor arranged between the substrates and laterally besides the power semiconductor chip such that a first side of the temperature sensor faces the first substrate and a second side of the temperature sensor faces the second substrate. A first electrical contact of the temperature sensor is arranged on the first side and electrically coupled to the first substrate. A second electrical contact of the temperature sensor is arranged on the second side and electrically coupled to the second substrate.

Document <CIT> discloses a semiconductor device provided with first and second substrates. The first and second substrates are facing each other by having a predetermined gap therebetween. A plurality of semiconductor elements are mounted on a first substrate surface facing the second substrate. A plurality of temperature detection elements are mounted on a second substrate surface facing the first substrate, and are thermally in contact with the semiconductor elements.

Document <CIT> discloses a power semiconductor module including: a carrier; a plurality of semiconductor dies attached to a first side of the carrier and electrically connected to form a circuit or part of a circuit; a cooling device at a second side of the carrier opposite the first side; a clamping device attached to the cooling device and pressing the carrier toward the cooling device such that the second side of the carrier is in thermal contact with the cooling device without having an intervening base plate between the carrier and the cooling device; and a first sensor device embedded in the clamping device or attached to an interior surface of the clamping device.

Power modules include elements that generate a substantial amount of heat during operation. For example, power semiconductor transistor dies may operate at temperatures of at least <NUM>, <NUM>, <NUM> or more. Other components power modules such as passive elements may also operate at these high temperatures during operation. It may be beneficial to incorporate temperature monitoring functionality into a power module that measures the temperature of the heat generating elements. Temperature monitoring can be used to prevent acute device failure and/or preserve the useful life of a power module. Current temperature sensing solutions in power modules suffer from drawbacks including increased area requirements, cost, complexity, and inaccuracy.

Thus, there is a need for improved temperature monitoring solutions in electronics applications such as power module applications.

A semiconductor module is disclosed. According to an embodiment, the semiconductor module comprises a first circuit carrier comprising one or more heat generating elements mounted on an upper surface of the first circuit carrier, a second circuit carrier mounted over the first circuit carrier and being vertically spaced apart from the upper surface of the first circuit carrier, a temperature sensor that is fixedly attached to the second circuit carrier and is arranged in a vertical space between the lower surface of the second circuit carrier and the upper surface of the first circuit carrier, and a plurality of elements extending from the upper surface of the first circuit carrier towards the second circuit carrier, and supporting the second circuit carrier, wherein the temperature sensor is arranged in sufficient proximity to a first one of the heat generating elements to obtain a direct temperature measurement from the first one of the heat generating elements, and wherein the semiconductor module further comprises a dielectric material that fills a space between the temperature sensor and the first one of the heat generating elements, wherein the dielectric material is a potting compound that encapsulates each of the one or more heat generating elements.

A method of operating a semiconductor module is disclosed. According to an embodiment, the method comprises providing a semiconductor module comprising a first circuit carrier comprising one or more heat generating elements mounted on an upper surface of the first circuit carrier; a second circuit carrier mounted over the first circuit carrier and being vertically spaced apart from the upper surface of the first circuit carrier; one or more temperature sensors that are fixedly attached to the second circuit carrier and arranged in a vertical space between the lower surface of the second circuit carrier and the upper surface of the first circuit carrier; a plurality of elements extending from the upper surface of the first circuit carrier towards the second circuit carrier, and supporting the second circuit carrier; and a dielectric material that fills a space between the temperature sensor and the first one of the heat generating elements, wherein the dielectric material is a potting compound that encapsulates each of the one or more heat generating elements; and obtaining a direct temperature measurement of a first one of the heat generating elements using a first one of the temperature sensors.

The features of the various illustrated embodiments can be combined unless they exclude each other. Embodiments are depicted in the drawings and are detailed in the description which follows.

Embodiments of a semiconductor module with an advantageous temperature monitoring arrangement are described herein. The semiconductor module comprises a stacked arrangement of circuit carriers, with a lower circuit carrier and an upper circuit carrier that is mounted over and vertically spaced apart from the lower circuit carrier. The heat generating elements of the semiconductor module, including power semiconductor dies and passive elements, are mounted on the lower circuit carrier. Meanwhile, the upper circuit carrier accommodates the mounting of one or more temperature sensors that are positioned to measure a temperature of the heat generating elements. The temperature sensors can be configured to perform a direct temperature measurement of the heat generating elements. The upper circuit carrier can accommodate a controller element that receives and processes the temperature measurement temperature sensors. This arrangement eliminates the need for other types of temperature sensing elements, such as temperature sensing diodes, shunt elements, and integrated temperature sensing circuitry on the lower circuit carrier, and thus reduces size and cost of the semiconductor module in comparison to these module configurations.

Referring to <FIG>, a semiconductor module <NUM> comprises a first circuit carrier <NUM>. The first circuit carrier <NUM> comprises a structured metallization layer <NUM> disposed on an electrically insulating substrate <NUM>. The structured metallization layer <NUM> comprises a plurality of pads that are electrically isolated from one another. The pads are dimensioned to accommodate the mounting of semiconductor dies or passive elements thereon. Additionally, the pads can form part of an electrical interconnect structure that connects two or more devices together. The first circuit carrier <NUM> may additionally comprise a second metallization layer <NUM> disposed on a rear side of the first circuit carrier <NUM>. The second metallization layer <NUM> may be a continuous layer that is used to thermally couple the semiconductor module <NUM> to a cooling apparatus, such as a heat sink. The first structured metallization layer <NUM> and the second metallization layer <NUM> may comprise or be plated with any or more of Cu, Ni, Ag, Au, Pd, Pt, NiV, NiP, NiNiP, NiP/Pd, Ni/Au, NiP/Pd/Au, or NiP/Pd/AuAg.

According to an embodiment, the first circuit carrier <NUM> is a power electronics substrate. For example, the first circuit carrier <NUM> may be a Direct Copper Bonding (DCB) substrate, a Direct Aluminum Bonding (DAB) substrate, an Active Metal Brazing (AMB) substrate, or an Insulated Metal Substrate (IMS). In a power electronics substrate, the electrically insulating substrate <NUM> may comprise ceramic material such as Al<NUM>O<NUM> (Alumina) AIN (Aluminum Nitride), etc., or may comprise filled materials such as epoxy resin or polyimide, e.g., in the case of an IMS. Alternatively, the first circuit carrier <NUM> may be a printed circuit board (PCB). In that case, the electrically insulating substrate <NUM> may comprise a resin or epoxy resin material such as FR-<NUM>.

One or more heat generating elements <NUM> are mounted on an upper surface of the first circuit carrier <NUM>. As shown, the heat generating elements <NUM> mounted on the first circuit carrier <NUM> comprise a semiconductor die <NUM>. More generally, the heat generating elements <NUM> can comprise any electrical element that generates heat by electrical current flowing through the element. Examples of heat generating elements <NUM> include active devices, e.g., discrete transistor dies, controllers, etc., passive devices, e.g., discrete diodes, capacitors, inductors, etc., and electrical interconnect elements, e.g., metal clips, bond wires, ribbons, etc..

The semiconductor die <NUM> may be a power transistor die, such as a thyristor, diode, MOSFET or IGBT. In an embodiment, the semiconductor module <NUM> is configured as a power module, wherein the semiconductor die <NUM> is a power transistor die that is configured to conduct a load voltage of the power converter circuit, such as a high-side switch or a low-side switch of a half-bridge circuit. The power module may additionally comprise other devices such as driver dies that control a switching operation of the half-bridge circuit mounted on an upper surface of the first circuit carrier <NUM>.

The semiconductor module <NUM> comprises terminal connectors <NUM> extending from the first circuit carrier <NUM> to an externally accessible location. The terminal connectors <NUM> may be soldered to or otherwise attached to the first circuit carrier <NUM>. The terminal connectors <NUM> may be electrically conductive structures formed from, e.g., copper, aluminum, alloys thereof, etc. The terminal connectors <NUM> form external points of electrical contact to the devices mounted on the carrier. As shown, the terminal connectors <NUM> are configured as press-fit connectors that are designed to form a forcefitting connection with an external device, such as a PCB socket. More generally, these terminal connectors <NUM> may have a variety of different configurations and may be adapted to mate with a particular receptacle design, e.g., through force fitting or soldered connections.

The semiconductor module <NUM> comprises a housing <NUM> that surrounds an interior volume over the first circuit carrier <NUM>. The housing <NUM> in combination with the first circuit carrier <NUM> may form an enclosure. To this end, the housing <NUM> comprises sidewalls that are affixed to and/or in contact with the first circuit carrier <NUM> and a cover section extending over the interior volume. The housing <NUM> may be formed from a plastic material, for example.

The semiconductor module <NUM> comprises an encapsulant material <NUM> that fills the interior volume defined by the housing <NUM> and the first circuit carrier <NUM>. The encapsulant material <NUM> protects the components arranged inside the housing <NUM> and in particular encapsulates the semiconductor die <NUM> and associated electrical connection elements, thereby protecting these elements from environmental conditions and mechanical breakage. Generally speaking, the encapsulant can comprise any of a wide variety of materials that are used in electronics applications to protect semiconductor dies. The encapsulant may be a dielectric material that electrically isolates the components from one another. According to an embodiment, the encapsulant material <NUM> is a curable encapsulant material, such as a dielectric gel. More particularly, the encapsulant material <NUM> may be potting compound, such as a silicone-based potting compound.

The semiconductor module <NUM> comprises a second circuit carrier <NUM> arranged within the interior volume. The second circuit carrier <NUM> is mounted over the first circuit carrier <NUM> such that a lower surface <NUM> of the second circuit carrier <NUM> is vertically spaced apart from the upper surface of the first circuit carrier <NUM>. The upper surface of the first circuit carrier <NUM> refers to the surface of the structured metallization layer <NUM> that faces the second circuit carrier <NUM> or the surface of the electrically insulating substrate <NUM> that is exposed from the structured metallization layer <NUM>. Thus, a three-dimensional volume exists between the first circuit carrier <NUM> and the second circuit carrier <NUM>. The semiconductor module <NUM> may comprise support structures <NUM> that facilitate the arrangement of the second circuit carrier <NUM>. The support structures <NUM> may be similar structures as the previously described terminal connectors <NUM>, e.g., metal posts comprising copper, aluminum, etc. and may be affixed to the structured metallization layer <NUM> by an adhesive, e.g., solder, sinter, glue, etc. As shown, the semiconductor module <NUM> comprises dedicated support structures <NUM> that are separate from the terminal connectors <NUM>. Alternatively, the support structures <NUM> can be part of the terminal connectors <NUM>, and the second circuit carrier <NUM> can form electrical connections thereto (if desired) or can be electrically isolated from these support structures <NUM> (if desired). In still other embodiments, the second circuit carrier <NUM> is supported by an element that is attached to the electrically insulating substrate <NUM> of the first circuit carrier <NUM> and/or to the housing <NUM>.

According to an embodiment, the second circuit carrier <NUM> is a printed circuit board (PCB). In combination, the first circuit carrier <NUM> may be a power electronics substrate, e.g., DCB substrate, DAB substrate, AMB substrate, or an IMS substrate. In this way, the second circuit carrier <NUM> can be a relatively less expensive component than a power electronics substrate without any detrimental impact in performance, as any elements mounted on the second circuit carrier <NUM>, such as the controller <NUM> to be described in further detail below, do not require the electrical and heat performance properties of a power electronics substrate. Meanwhile, the heat generating elements <NUM> that generate significant amounts of heat during operation are mounted on a power electronics substrate that is well-suited for heat extraction and electrical isolation of these components. Alternatively, the second circuit carrier <NUM> may be a power electronics substrate such as a DCB, substrate, DAB substrate, AMB substrate, an IMS substrate or other type of electronics carrier, e.g., if needed to meet performance requirements.

The semiconductor module <NUM> further comprises a temperature sensor <NUM>. The temperature sensor <NUM> is arranged in the vertical space between the lower surface <NUM> of the second circuit carrier <NUM> and the upper surface of the first circuit carrier <NUM>. The temperature sensor <NUM> is fixedly attached to the second circuit carrier <NUM>. This attachment may be done by a fastening mechanism, e.g., screw, bolt, etc., or by an adhesive, for example. Separately or in combination, the temperature sensor <NUM> may comprise leads that are inserted into and retained by the second circuit carrier <NUM>.

The temperature sensor <NUM> can be any sensory device that is configured to perform a direct temperature measurement. In this context, a direct temperature measurement refers to a measurement of the temperature of the heat generating element <NUM> itself or the temperature of surrounding material or environment of the heat generating element <NUM>. By contrast, an indirect temperature measurement is a measurement of some other operating parameter of the heat generating element <NUM> besides temperature, e.g., current, magnetic field, voltage, etc., that is used to extrapolate the temperature of the heat generating element <NUM> according to a known relationship. Examples temperature sensor <NUM> embodiments that can configured to perform a direct temperature measurement include semiconductor-based temperature sensors, including analog and digital temperature sensors, thermistors, thermocouples, resistance temperature detectors and infrared-temperature sensors.

The temperature sensor <NUM> is arranged in sufficient proximity to a first one of the heat generating elements <NUM> mounted on the first circuit carrier <NUM> to obtain a direct temperature measurement of the first one of the heat generating elements <NUM>. In the embodiment of <FIG>, the semiconductor die <NUM> corresponds to the first one of the heat generating elements <NUM> that is in sufficient proximity to the temperature sensor <NUM>. The proximity necessary to obtain a direct temperature is dependent upon a variety of factors, such as the type of temperature sensor <NUM>, type of heat generating element <NUM>, and medium between the temperature sensor <NUM> and heat generating elements <NUM>. Generally speaking, the temperature sensor <NUM> can be disposed at a distance of between <NUM> and <NUM>, with respect to required electrical isolation distances between the surface of <NUM> and the temperature sensor <NUM>, from the heat generating element <NUM> to obtain a direct temperature measurement. In the depicted embodiment, the temperature sensor <NUM> is disposed directly over the semiconductor die <NUM>. While this arrangement may be advantageously space efficient, it is not necessary. In other embodiments, the temperature sensor <NUM> can be laterally offset from the heat generating element <NUM> to which it is assigned to obtain a direct measurement from. In the case of an infrared based measurement sensor device, the temperature sensor <NUM> may be arranged to be in direct line of sight with the heat generating element <NUM>. Otherwise, line of sight may not be necessary.

According to an embodiment, the temperature sensor <NUM> is galvanically isolated from the first one of the heat generating elements <NUM>. That is, the electrical currents and associated magnetic fields that exist in the first one of the heat generating elements <NUM> do not influence the operation of the temperature sensor <NUM> and vice-versa. Galvanic isolation may result from a dielectric medium, which may include ambient air, a dielectric compound, or both. As shown, the encapsulant material <NUM> serves a dual role as encapsulant that protects the devices mounted on the first circuit carrier <NUM> and as a dielectric medium that fills the space between the temperature sensor <NUM> and the semiconductor die <NUM>. Thus, the material for the encapsulant material <NUM> and the spacing between the temperature sensor <NUM> and the first one of the heat generating elements <NUM> may be selected to ensure proper electrical isolation.

The semiconductor module <NUM> may comprise a controller <NUM> mounted on an upper surface of the second circuit carrier <NUM>. The controller <NUM> receives a measurement signal from the temperature sensor <NUM> and determines a temperature of the first one of the heat generating elements <NUM> based on the temperature signal. For example, the controller <NUM> can receive a digital output from the temperature sensor <NUM>, e.g., in the case of a digital device or analog signal, e.g., current, frequency, etc., e.g., in the case of a thermistors, thermocouple, resistance temperature detector, etc. The signal can be transmitted between the controller <NUM> and the temperature sensor <NUM> by a signal connection <NUM>, which may comprise a combination of conductive traces in the second circuit carrier <NUM> and interconnect elements. The controller <NUM> can be a logic device such as an ASIC (application specific integrated circuit), FPGA (field gate programmable array), etc., that is configured to perform some action based on the ascertained temperature signal. For example, the controller <NUM> may be used to turn off or adjust the operation of the elements mounted on the first circuit carrier <NUM>, including the first one of the heat generating elements <NUM>.

Referring to <FIG>, a semiconductor module <NUM> is shown, according to another embodiment. In this embodiment, the semiconductor module <NUM> comprises a plurality of the temperature sensors <NUM> fixedly attached to the second circuit carrier <NUM> and arranged in the vertical space between the lower surface <NUM> of the second circuit carrier and the upper surface of the first circuit carrier <NUM>. Each of the temperature sensors <NUM> in the plurality can have any of the above-described configurations.

According to an embodiment, each of the temperature sensors <NUM> in the plurality are digital temperature sensors. The controller <NUM> can receive a measurement signal from each of the temperature sensors <NUM> and therefore ascertain a temperature measurement at different locations of the semiconductor module <NUM>. According to one concept, the temperature sensors <NUM> and the controller <NUM> are arranged to perform a sequential measurement wherein the controller <NUM>. The controller <NUM> can read each one of the temperatures sequentially, i.e., receives a measurement from each one of the temperature sensors <NUM> according to a periodic or predictable sequence.

Additionally, the semiconductor module <NUM> comprises plurality of the heat generating elements <NUM> mounted on the upper surface of the first circuit carrier <NUM>. As shown, the plurality of the heat generating elements <NUM> comprises a first one of the heat generating elements <NUM> and a second one of the heat generating elements <NUM>, wherein the first one of the heat generating elements <NUM> corresponds to the semiconductor die <NUM> and the second one of the heat generating elements <NUM> is a passive element <NUM>. More particularly, the second one of the heat generating elements <NUM> is a shunt resistor that is connected between to separate pads of the structured metallization layer <NUM>. The shunt resistor may be configured to sense a current of the semiconductor module <NUM>, such as a current flowing through the switching device of a power converter or power inverter circuit.

The temperature sensors <NUM> may be arranged to be in sufficient proximity to obtain a direct temperature measurement from more than one of the heat generating elements <NUM>. For example, as shown, a first centrally located one of the temperature sensors <NUM> is arranged laterally in between the first and second ones of the heat generating elements <NUM>, i.e., the semiconductor die <NUM> and the passive element <NUM>. The first centrally located one of the temperature sensors <NUM> may be in sufficient proximity to obtain a direct temperature measurement from the semiconductor die <NUM> and the passive element <NUM>. The measurement information received from the first centrally located one of the temperature sensors <NUM> may be processed in combination with the measurement information received from the other temperature sensors <NUM> arranged on either side of the semiconductor die <NUM> and the passive element <NUM> to obtain a differential temperature reading that can be processed by the controller <NUM>. More generally, the controller <NUM> can determine a temperature of each of the heat generating elements <NUM> based on the signals from each of the temperature sensors <NUM>, by performing a differential analysis as described above or by direct measurement from a temperature sensor <NUM> that is dedicated to a particular heat generating element <NUM>. For example, the number of temperature sensors <NUM> may be less than the number of heat generating elements <NUM>, wherein the above-described concept is used to perform a temperature measurement for at least some of the heat generating elements <NUM>. Alternatively, the same number or a greater number of temperature sensors <NUM> than the heat generating elements <NUM> may be provided, e.g., for greater accuracy.

A power semiconductor die refers to a single die that is rated to accommodate voltages of at least <NUM> V (volts), and more typically voltages of <NUM> V, <NUM> V or more and/or is rated to accommodate currents of at least 1A, and more typically currents of 10A, 50A, 100A or more. Examples of power semiconductor dies include discrete power diodes and discrete power transistor dies, e.g., MOSFETs (Metal Oxide Semiconductor Field Effect Transistors), IGBTs (Insulated Gate Bipolar Transistors), and HEMTs (High Electron Mobility Transistors), etc. At least one of the heat generating elements <NUM> may comprise.

The semiconductor dies disclosed herein can be formed in a wide variety of device technologies that utilize a wide variety of semiconductor materials. Examples of such materials include, but are not limited to, elementary semiconductor materials such as silicon (Si) or germanium (Ge), group IV compound semiconductor materials such as silicon carbide (SiC) or silicon germanium (SiGe), binary, ternary or quaternary III-V semiconductor materials such as gallium nitride (GaN), gallium arsenide (GaAs), gallium phosphide (GaP), indium phosphide (InP), indium gallium phosphide (InGaPa), aluminum gallium nitride (AlGaN), aluminum indium nitride (AllnN), indium gallium nitride (InGaN), aluminum gallium indium nitride (AIGalnN) or indium gallium arsenide phosphide (InGaAsP), etc..

The semiconductor dies disclosed herein may be configured as a vertical device, which refers to a device that conducts a load current between opposite facing main and rear surfaces of the die. Alternatively, the semiconductor dies may be configured as a lateral device, which refers to a device that conducts a load current parallel to a main surface of the die.

Spatially relative terms such as "under," "below," "lower," "over," "upper" and the like, are used for ease of description to explain the positioning of one element relative to a second element. These terms are intended to encompass different orientations of the device in addition to different orientations than those depicted in the figures. Further, terms such as "first," "second," and the like, are also used to describe various elements, regions, sections, etc. and are also not intended to be limiting. Like terms refer to like elements throughout the description.

Claim 1:
A semiconductor module (<NUM>), comprising:
a first circuit carrier (<NUM>) comprising one or more heat generating elements (<NUM>) mounted on an upper surface of the first circuit carrier (<NUM>);
a second circuit carrier (<NUM>) mounted over the first circuit carrier (<NUM>) and being vertically spaced apart from the upper surface of the first circuit carrier (<NUM>);
a temperature sensor (<NUM>) that is fixedly attached to the second circuit carrier (<NUM>) and is arranged in a vertical space between the lower surface of the second circuit carrier (<NUM>) and the upper surface of the first circuit carrier (<NUM>); and
a plurality of elements (<NUM>, <NUM>) extending from the upper surface of the first circuit carrier (<NUM>) towards the second circuit carrier (<NUM>), and supporting the second circuit carrier (<NUM>),
wherein the temperature sensor (<NUM>) is arranged in sufficient proximity to a first one of the heat generating elements (<NUM>) to obtain a direct temperature measurement from the first one of the heat generating elements (<NUM>), and
wherein the semiconductor module (<NUM>) further comprises a dielectric material (<NUM>) that fills a space between the temperature sensor (<NUM>) and the first one of the heat generating elements (<NUM>), wherein the dielectric material (<NUM>) is a potting compound that encapsulates each of the one or more heat generating elements (<NUM>).