Junction temperature integral optical thermometer

Abstract

The invention provides a junction temperature integral optical thermometer. The invention relates to a silicon-based power device with an integrated optical-mechanical temperature sensing system. In some examples, the device includes a silicon die in which a photonic crystal cavity, a photodiode, and a photodetector are integrally embedded. A photodiode positioned at an end of the photonic crystal cavity emits photons, while a photodetector detects photon intensity. A silicon-based mechanical component located within the cavity deforms in response to a temperature change to modulate reflection of the photons. This deformation allows the junction temperature to be measured by analyzing the intensity of the reflected photons.

Description

Junction temperature integral optical thermometer Technical Field

[0001] This disclosure relates to power semiconductor devices. Background Technology

[0002] Silicon carbide (SiC) power devices are constructed using silicon carbide, a compound semiconductor material composed of silicon and carbon atoms arranged in a crystalline structure. SiC belongs to a class of materials known as wide-bandgap semiconductors, with a significantly larger energy bandgap than conventional silicon. This wider bandgap is a characteristic that enables SiC devices to perform well in high-voltage, high-temperature, and high-frequency applications. Summary of the Invention

[0003] A silicon-based power device includes a silicon die in which a photonic crystal cavity, a photodiode, and a photodetector are integrally embedded. The photodiode and the photodetector are positioned at the ends of the photonic crystal cavity. Additionally, a silicon-based mechanical component is located within the photonic crystal cavity. This mechanical component is designed to deform in response to temperature changes within the silicon die, thereby modulating the behavior of light transmitted through the cavity.

[0004] A method for measuring the junction temperature of a silicon-based power device involves applying a voltage to a photodiode embedded within a silicon die. This causes the photodiode to emit photons into a photonic crystal cavity, also embedded in the silicon die, which contains silicon-based mechanical components. The photons travel through the cavity and are reflected by the mechanical components, which deform in response to temperature fluctuations. The method generates an output signal by detecting the intensity of the photons reflected from the mechanical components, where the intensity corresponds to the junction temperature.

[0005] An integrated junction temperature gauge includes an integrated circuit embedded in a silicon die, the integrated circuit comprising both a photodiode and a photodetector. These components are operatively connected via a photonic crystal cavity within the die. The cavity contains silicon-based mechanical components designed to deform in response to temperature changes within the silicon die, thereby enabling the detection and measurement of the junction temperature via changes in the intensity of photons reflected within the cavity. Attached Figure Description

[0006] Figure 1A is a plan view of a SiC power device.

[0007] Figure 1B is a cross-sectional side view of the SiC power device in Figure 1A.

[0008] Figure 2 is a partial schematic diagram of the SiC power device in Figure 1A.

[0009] Figure 3 is a plan view of another SiC power device. Detailed Implementation

[0010] This document describes embodiments. However, it should be understood that the disclosed embodiments are merely examples and other embodiments may take various and alternative forms. The drawings are not necessarily drawn to scale. Some features may be enlarged or minimized to show details of specific components. Therefore, the specific structural and functional details disclosed herein should not be construed as limiting, but merely as a representative basis for teaching those skilled in the art.

[0011] The various features shown and described with reference to any of the accompanying drawings may be combined with features shown in one or more other drawings to produce embodiments not explicitly shown or described. The combinations of features shown provide representative embodiments for typical applications. However, for a particular application or implementation, various combinations and modifications of features consistent with the teachings of this disclosure may be desired.

[0012] The components of SiC power devices are semiconductor junctions, which are typically formed through a process called doping. Doping involves introducing impurities into the SiC lattice to create regions with different electrical properties. For SiC devices, n-type regions are created by doping SiC with donor atoms, while p-type regions are formed by doping with acceptor atoms. These doped regions together form a pn junction, which is responsible for the core switching behavior of the device. SiC power devices are typically fabricated as diodes (rectifiers) or transistors, with metal-oxide-semiconductor field-effect transistors (MOSFETs) being widely used in power conversion systems, such as those used in vehicles, due to their high-efficiency switching capabilities.

[0013] Like other semiconductor devices, the basic operation of SiC devices revolves around controlling the flow of electrons across the pn junction. For example, in a SiC MOSFET, when a voltage is applied to the gate terminal, it generates an electric field in the semiconductor, thereby modulating the conductivity of the SiC channel between the source and drain terminals. This process allows or blocks current from flowing through the device. The wide bandgap of SiC allows these devices to maintain much higher electric fields without breakdown, enabling them to operate at significantly higher voltages and temperatures compared to silicon-based MOSFETs.

[0014] SiC power devices are known for their ability to operate under extreme conditions. This resilience is attributed to the strong covalent bonds between silicon and carbon atoms in the crystal lattice, which imparts excellent thermal conductivity. Therefore, SiC devices can operate at junction temperatures much higher than their silicon counterparts. However, this same robust lattice structure makes it more difficult to integrate features such as on-die temperature sensors, posing challenges to real-time thermal management, especially under dynamic operating conditions.

[0015] The fabrication of SiC devices requires specialized manufacturing techniques. SiC wafers are typically produced by growing high-purity single-crystal SiC ingots using methods such as physical vapor transport (PVT) or chemical vapor deposition (CVD). Once the ingots are grown, they are sliced ​​into thin wafers, which undergo various processing steps, including ion implantation, etching, and metallization, to form the desired device structures, such as pn junctions, contacts, and gates.

[0016] In addition to diodes and MOSFETs, SiC power devices can also be manufactured in other configurations, including junction field-effect transistors (JFETs) and bipolar junction transistors (BJTs). Each device type offers unique advantages suitable for specific applications. For example, SiC Schottky barrier diodes (SBDs) are preferred for efficient rectification due to their low forward voltage drop and fast switching speed. On the other hand, SiC MOSFETs are favored in high-voltage switching applications where minimal switching losses and high voltage handling are desired.

[0017] Despite the advantages of SiC devices, most currently available SiC chips do not include an integrated on-die temperature sensor capable of directly measuring the junction temperature. This limitation necessitates the use of indirect methods for temperature monitoring. Typically, external sensors are used to estimate the junction temperature, or it is inferred through algorithmic models based on device operation; however, these methods can lack accuracy, especially during periods of rapid temperature fluctuations.

[0018] The lack of a precise temperature measurement mechanism can impact the performance and efficiency of SiC power devices. Inaccurate temperature readings can lead to suboptimal power derating, where power output is unnecessarily reduced. This inefficiency can also affect chip size optimization during the design process, as designers may increase chip size to account for uncertain thermal behavior. Furthermore, inaccurate temperature measurements can cause device wear.

[0019] This disclosure presents a system that allows direct measurement of junction temperature in SiC devices without increasing chip size. By incorporating on-die temperature sensing technology, these arrangements provide real-time, accurate temperature monitoring, which enables better power control and enhanced device reliability.

[0020] The component of the temperature sensing system is a photonic crystal cavity that transmits photons. The optical cavity can be fabricated monolithically from silicon during the same photolithography process used to form the SiC die. As a nanostructure, the optical cavity can be placed at various locations on the SiC die or distributed across multiple locations to achieve comprehensive temperature sensing. Its mechanical design provides inherent resistance to external vibrations, allowing stable operation even in high-stress environments. The optical cavity operates based on photonic resonance and intensity modulation rather than the current and voltage fluctuations used in conventional resistance thermometers. This makes the system less susceptible to electromagnetic interference, even in environments with high electrical noise.

[0021] The system includes a photodetector, also made of silicon, which is sensitive to photons and uses photon thermometry to analyze the spectral characteristics of the SiC chip. Specifically, the photodetector measures the intensity of photons emitted by a photodiode, which are reflected from mechanical components and transmitted through an optical cavity. This process provides direct information about the junction temperature of the SiC die. The photodetector then converts the photon intensity into an electrical signal, which is transmitted to a central control board for real-time system monitoring and management.

[0022] Mechanical elements are responsible for modulating the intensity of reflected photons based on thermal expansion and contraction. These elements are designed from materials such as silicon or silicon nitride, which exhibit predictable mechanical deformation at varying temperatures. Positioned within the optical cavity, the mechanical elements deform in response to temperature fluctuations within the SiC die, thereby altering the photon reflection angle and intensity.

[0023] This system can be extended to measure temperature at multiple locations on a SiC die. Combining temperature sensors at several points across the die allows for high-resolution thermal mapping, providing data for optimizing thermal management. Furthermore, multi-point temperature sensing can identify patterns that enable predictive maintenance.

[0024] As shown in Figure 1A, the optomechanical temperature sensor system 10 is integrated within the SiC die 12 and includes a photodiode 14, an optical cavity 16, mechanical components 18, a photodetector 20, and a direct-bonded copper (DBC) layer 22. These components are integrally embedded in the SiC die 12, thereby facilitating real-time temperature monitoring and addressing the challenges associated with conventional indirect temperature measurement methods.

[0025] Photodiodes 14 located near certain areas of the SiC die 12 emit photons that are transmitted through optical cavities 16. These optical cavities 16, made of silicon, act as waveguides for the photons. The photons are guided toward a mechanical element 18, which modulates the photon intensity based on temperature-induced deformation.

[0026] As shown in Figure 1B, a mechanical element 18 is placed within an optical cavity 16 and is designed to deform in response to temperature changes within the SiC die 12. This deformation alters the reflective properties of cavity 16, thereby modulating the intensity and angle of the reflected photons. As shown in Figure 2, a photodetector 20 located at one end of an optical cavity within optical cavity 16 detects the modulated photons and converts the changes in photon intensity into electrical signals. These signals, transmitted as signal output 24 to an external control system, provide real-time data regarding the junction temperature.

[0027] The circuit system responsible for this detection and conversion includes resistors R1 and R2, photodiode 14, and photodetector 20, which are arranged to realize light emission, detection, and signal processing.

[0028] The focus of the circuit is the interaction between photodiode 14 and photodetector 20. Photodiode 14 emits light when powered by the supply voltage VCC. This emitted light travels through optical cavity 16, is reflected by mechanical element 18, and then travels back through optical cavity 16 to be captured by photodetector 20. The function of photodetector 20 is to detect the reflected light and convert its intensity into an electrical signal.

[0029] R1 and R2 are positioned in the circuit to control the current and voltage levels, thereby providing appropriate bias and operating conditions for both photodiode 14 and photodetector 20. R2 is typically placed in series with photodiode 14 to control the current flowing through it. R1 is typically connected to photodetector 20 to control the voltage and sensitivity of the detection process, thereby ensuring that the photodetector operates within its optimal range.

[0030] The power supply voltage VCC provides power to the circuit, thus delivering the necessary voltage for both the light emission of photodiode 14 and the light detection of photodetector 20. Ground GND serves as a reference point for the circuit, thereby providing a return path for the current.

[0031] An output voltage Vout is generated based on the intensity of light detected by photodetector 20. As more light is reflected and detected by photodetector 20, the output voltage Vout changes accordingly, thus providing a signal 24 corresponding to the amount of reflected light. This signal 24 can then be processed for further analysis.

[0032] The DBC layer 22, positioned beneath the SiC die 12, provides both conductivity, insulation, and effective heat dissipation. The DBC layer 22 may include a ceramic core sandwiched between two copper layers, thereby providing mechanical stability and a platform for the electrical connections of the SiC die, as well as a mechanical platform for the photodiode 14, photodetector 20, and other components of the system 10.

[0033] As depicted in Figure 3, system 110 can be scaled to support multi-point temperature sensing across the SiC die 112. This extended configuration involves multiple sets of photodiodes 114, optical cavities 116, mechanical elements 118, and photodetectors 120 distributed across the die 112. This arrangement allows for the detection of temperature gradients across the SiC chip, thereby improving the accuracy of over-temperature control mechanisms and enabling thermal mapping of the device.

[0034] While exemplary embodiments have been described above, these embodiments are not intended to describe all possible forms covered by the claims. Furthermore, the language used in this specification is descriptive rather than restrictive, and it should be understood that various changes may be made without departing from the spirit and scope of this disclosure. Any reference to a single element includes the possibility of multiple elements, and any reference to multiple elements includes the possibility of a single element.

[0035] As previously described, features of various embodiments can be combined to form other embodiments of the invention that may not be explicitly described or shown. While various embodiments may have been described as offering advantages or preferences over other embodiments or prior art implementations in terms of one or more desired characteristics, those skilled in the art will recognize that one or more features or characteristics may be compromised to achieve desired overall system properties, depending on the specific application and implementation. These properties may include, but are not limited to: strength, durability, marketability, appearance, packaging, size, serviceability, weight, manufacturability, ease of assembly, etc. Therefore, embodiments described as less desirable than other embodiments or prior art implementations in terms of one or more characteristics are not outside the scope of this disclosure and may be desirable for a particular application.

[0036] According to the present invention, a silicon power device is provided, comprising: a silicon-based die; a photonic crystal cavity, a photodiode, and a photodetector integrally embedded in the silicon-based die such that the photodiode and the photodetector are located at the ends of the photonic crystal cavity; and silicon-based mechanical elements in the photonic crystal cavity, the silicon-based mechanical elements being configured to deform in response to temperature changes associated with the silicon-based die.

[0037] According to an embodiment, the invention is further characterized by a circuit system in which the photodiode and the photodetector are arranged and configured to generate an output signal indicating the temperature of the silicon die.

[0038] According to an embodiment, the output signal is a voltage signal.

[0039] According to an embodiment, the photonic crystal cavity is configured to transmit photons emitted by the photodiode and reflected by the silicon-based mechanical element to the photodetector.

[0040] According to an embodiment, the silicon-based mechanical element includes silicon nitride.

[0041] According to an embodiment, the silicon-based die is a silicon carbide die.

[0042] According to the present invention, a method for measuring the junction temperature of a silicon-based power device includes: applying a voltage to a photodiode integrally embedded in a silicon-based die, such that the photodiode emits photons into a photonic crystal cavity, the photonic crystal cavity being integrally embedded in the silicon-based die and having silicon-based mechanical elements therein, and the photons being reflected from the silicon-based mechanical elements; and generating an output signal based on the intensity of the photons reflected by the silicon-based mechanical elements.

[0043] In one aspect of the invention, the application further causes the photons reflected by the silicon-based mechanical element to be detected by a photodetector configured to measure the intensity.

[0044] According to the present invention, an integral junction thermometer is provided, comprising: a circuit system including a photodiode and a photodetector; and a photonic crystal cavity integrated with a silicon-based die, the photonic crystal cavity being operatively arranged together with the photodiode and the photodetector, and including a silicon-based mechanical element configured to deform in response to temperature changes associated with the silicon-based die.

[0045] According to an embodiment, the photodiode and the photodetector are integrated with the silicon-based die.

[0046] According to an embodiment, the photodiode is configured to emit photons in response to a voltage applied thereto.

[0047] According to an embodiment, the photonic crystal cavity is configured to transmit photons emitted by the photodiode.

[0048] According to an embodiment, the silicon-based mechanical element is configured to reflect the photons transmitted by the photonic crystal cavity.

[0049] According to an embodiment, the photodetector is configured to detect the photons reflected by the silicon-based mechanical element.

[0050] According to an embodiment, the silicon-based mechanical element includes silicon nitride.

[0051] According to an embodiment, the circuit system is configured to output a signal indicating the junction temperature of the silicon-based die.

[0052] According to an embodiment, the signal is a voltage signal.

Claims

1. A silicon power device, comprising: Silicon-based die; A photonic crystal cavity, a photodiode, and a photodetector, the photonic crystal cavity, the photodiode, and the photodetector being integrally embedded in the silicon die such that the photodiode and the photodetector are located at the ends of the photonic crystal cavity; and silicon-based mechanical elements in the photonic crystal cavity, the silicon-based mechanical elements being configured to deform in response to temperature changes associated with the silicon die.

2. The silicon power device of claim 1, further comprising a circuit system arranged together with the photodiode and the photodetector, the circuit system being configured to generate an output signal indicating the temperature of the silicon die.

3. The silicon power device of claim 2, wherein the output signal is a voltage signal.

4. The silicon power device of claim 1, wherein the photonic crystal cavity is configured to transmit photons emitted by the photodiode and reflected by the silicon-based mechanical element to the photodetector.

5. The silicon power device of claim 1, wherein the silicon-based mechanical element comprises silicon nitride.

6. The silicon power device of claim 1, wherein the silicon-based die is a silicon carbide die.

7. A method for measuring the junction temperature of a silicon-based power device, comprising: A voltage is applied to a photodiode integrally embedded in a silicon die, causing the photodiode to emit photons into a photonic crystal cavity, which is integrally embedded in the silicon die and has silicon-based mechanical elements therein, and the photons are reflected from the silicon-based mechanical elements; and an output signal is generated based on the intensity of the photons reflected by the silicon-based mechanical elements.

8. The method of claim 7, wherein the application further causes the photons reflected by the silicon-based mechanical element to be detected by a photodetector configured to measure the intensity.

9. An integral junction thermometer, comprising: The circuit system includes a photodiode and a photodetector; The photonic crystal cavity is integrated with a silicon-based die, the photonic crystal cavity is operatively arranged together with the photodiode and the photodetector, and includes silicon-based mechanical elements configured to deform in response to temperature changes associated with the silicon-based die.

10. The integral junction thermometer of claim 9, wherein the photodiode and the photodetector are integrated with the silicon die.

11. The integral junction thermometer of claim 10, wherein the photodiode is configured to emit photons in response to a voltage applied thereto.

12. The integral junction thermometer of claim 11, wherein the photonic crystal cavity is configured to transmit the photons emitted by the photodiode.

13. The integral junction thermometer of claim 12, wherein the silicon-based mechanical element is configured to reflect the photons transmitted through the photonic crystal cavity.

14. The integral junction thermometer of claim 13, wherein the photodetector is configured to detect the photons reflected by the silicon-based mechanical element.

15. The integral junction thermometer of claim 9, wherein the circuitry is configured to output a signal indicating the junction temperature of the silicon die.

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