Adjustable Transfer End Thermometer

Abstract

A temperature sensor, a semiconductor device, and a method for measuring the temperature of a sample will be described. One embodiment of the temperature sensor can include a probe circuit, and the probe circuit has a certain thermal operating range. The temperature sensor can further include a thermal resistor that separates the probe circuit from the sample. The temperature sensor can further include a heating circuit configured to maintain the probe circuit within the thermal operating range.

Description

Technical Field

[0001] The present disclosure relates to temperature measurement, and more specifically, to a temperature measurement system and method having a wide range and high sensitivity.

[0002] Integrated ultra-high sensitivity temperature sensors are used in many state-of-the-art technologies in the fields of quantum sensors and devices operating at cryogenic temperatures (e.g., quantum cryptographic transmitters); neuromorphic hardware based on oscillatory neural networks; phase change or resistive change type memories (Resistive Random-Access Memory: RRAM (registered trademark)) computer memories; conventional complementary metal-oxide-semiconductors (CMOS) and III-V group electronic devices (e.g., InP, InAs, GaAs, GaN, AlSb, GaSb, and InSb); and terahertz (THz) and / or infrared (IR) imaging, such as metrology, precision chemistry, and medical technology. Most of these sensors measure the electrical resistance that depends on temperature. The detection sensitivity of the device can be given using the temperature coefficient (TCR).

Summary of the Invention

[0003] According to an embodiment of the present disclosure, the temperature sensor includes a probe circuit having a thermal operating range. The temperature sensor may further include a thermal resistor that separates the probe circuit from the sample. The temperature sensor may further include a heating circuit configured to maintain the probe circuit within the thermal operating range.

[0004] According to an embodiment of the present disclosure, a semiconductor device includes a substrate and a contact thermometer attached to the substrate. The contact thermometer may have a probe circuit, and the probe circuit may include a thermal operating range. The contact thermometer may further include a thermal resistor that separates the probe circuit from the substrate. The contact thermometer may further include a heating circuit configured to maintain the probe circuit within the thermal operating range.

[0005] According to an embodiment of the present disclosure, a method for measuring the temperature of a sample includes heating a sensor element to a temperature within the thermal operating range of the sensor. The method may further include measuring the amount of electrical power applied to maintain the sensor element at the temperature. The method may further include converting the measured amount of electrical power into a sample temperature. The method may further include outputting the sample temperature.

[0006] The above summary is not intended to describe every illustrated embodiment or every implementation of the present disclosure.

Brief Description of the Drawings

[0007] The drawings included in this application are incorporated herein and form a part hereof. They illustrate embodiments of the present disclosure and, together with the description, serve to explain the principles of the present disclosure. The drawings illustrate only some embodiments and do not limit the present disclosure.

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[0016] The present invention is applicable to various modifications and alternative forms, specific examples of which are shown in the drawings as examples and will be described in detail. However, it should be understood that the intention is not to limit the present invention to the specific embodiments described. On the contrary, it is intended to embrace all modifications, equivalents, and alternatives included within the spirit and scope of the present invention.

Embodiments for Carrying Out the Invention

[0017] Aspects of the present disclosure relate to temperature measurement; more specific aspects relate to temperature measurement systems and methods having a wide range and high sensitivity. The present disclosure is not necessarily limited to such applications, but various aspects of the present disclosure can be understood through consideration of various examples using this context.

[0018] Generally, there is a trade-off between the sensitivity of a sensor and the operating range of the sensor. For example, a common PT100 (platinum 100) resistance thermometer can measure temperature over a wide range (e.g., several hundred Kelvin (K) degrees), but it cannot accurately measure small changes in temperature at these temperatures (i.e., it has relatively poor sensitivity and / or a low TCR). On the other hand, transition-edge thermometers can be extremely sensitive; some can measure the heat generated by a single photon. However, transition-edge thermometers have conventionally been limited to a narrow operating range (e.g., typically an operating range of less than 1 K degree).

[0019] Accordingly, one aspect of the present disclosure is a contact temperature sensor, also referred to herein as a contact thermometer, that has both a wide operating range and high detection sensitivity to temperature changes in a sample. Additionally, some embodiments may enable highly sensitive measurements of a sample at relatively high temperatures (e.g., above room temperature). Another aspect of the present disclosure is a temperature sensor that is capable of self-calibration, i.e., a device that does not require a separate calibration operation prior to use. Another aspect of the present disclosure is a method of measuring the temperature of a sample. In some embodiments, the method may include time-resolved measurements that reduce the thermal impact on the sample.

[0020] One of the features and advantages of some embodiments is that they can be easily integrated into existing integrated circuit (IC) design and manufacturing processes to provide an integrated temperature measurement solution, specifically, they can be integrated into many complementary metal-oxide-semiconductor (CMOS) semiconductor devices and associated manufacturing processes. This feature and advantage may be particularly desirable, for example, in neuromorphic and quantum devices where the operating temperature is typically very low and clearly defined and specified. Another feature and advantage of some embodiments is that they may enable measurement of radiation and / or conduction to and / or from the sample.

[0021] Figure 1 is a schematic diagram of a first temperature sensor 100 that conforms to some embodiments. The sensor 100 may include a resistor 120 having a thermal resistance Rth, a probing circuit 130, and a heating circuit 140. Further, the probing circuit 130 can include a transition edge material (TEM) such as a phase change material 134, which is electrically coupled to a circuit for measuring its electrical resistance, for example, a first current source 136 and a voltmeter 138. The heating circuit 140 can include a Joule heat dissipation resistor 144 electrically coupled to a second adjustable current source 146 and a voltmeter 148 (or an adjustable voltage source with an ammeter, not shown). That is, the sensor 100 includes a phase change material 134 that provides a transition edge, an adjustable heat source (e.g., the Joule heat dissipation resistor 144 of the heating circuit 140), and a combination of resistors that link the phase change material 134 to the sample 150.

[0022] During operation, the phase change material 134 can provide a transition edge, which can be detected using the adjustable current source 136 and the voltmeter 138. The heating circuit 140 can be controlled to maintain the temperature of the phase change material 134 within its operating range (i.e., at or near the critical temperature Tc). The thermal resistor 120 can make it possible to maintain the temperature difference between the phase change material 134 and the sample 150 by the heating circuit 140. Thus, when the sample 150 is below the critical temperature Tc, the phase change material 134 can be actively heated to its operating range by applying heating power "P" to the heating circuit 140 and then maintained within that operating range. The amount of electrical power "P" required to maintain that temperature is measured via the voltage drop "V" across the resistor 144 and the current "I" through the resistor 144, and in this case, can be calculated using Equation 1: P = V * I. Further, the temperature of the sample 150 can be calculated from the calculated P using Equation 2. Equation 2: T センサ - T サンプル = R th * P Since Joule heating is used as described in Equation 1, T センサIt can be higher than T サンプル However, those skilled in the art will recognize that in circuit 140, negative power P may be obtained using the Peltier effect. This latter embodiment is also within the scope of the present disclosure.

[0023] The phase change material 134 can be any material that undergoes a phase change under an external stimulus such as heat. This phase change may be associated with a change in another physical or electrical property that can be measured to indicate the phase of the material. In the example given in FIG. 1, the state of the phase change material is measured through its electrical resistance. However, other types of measurements of the state of the phase change material may be applied and are within the scope of the present disclosure. For example, the optical or mechanical properties of the phase change material may be probed. There are many forms of phase change materials (PCMs). For example, some materials can switch between two states with different electrical conductivities by changing their crystallographic state, which can be achieved by heating the phase change material. Specifically, the phase change material 134 within the sensor 100 can be a PCM material having a simple transition end at a temperature (Tc). One such suitable material is a micro-piece of a metallic superconductor (e.g., niobium (Nb)) with a diameter of about 1 micron. However, other superconducting and non-superconducting phase change materials, and / or TEMs are also within the scope of the present disclosure.

[0024] The thermal resistor 120 may be any material and / or physical configuration that allows the two to maintain different temperatures while still maintaining the thermal relationship between the phase change material 134 and the sample 150 (e.g., by enabling a predictable heat flux). One such suitable thermal resistor 120 is an insert or beam made of a dielectric material such as SiO2, silicon nitride, or Al2O3, having a length of about 100 microns and a diameter of 100 nanometers (nm). In some embodiments, the exact thermal resistance (Rth) of the thermal resistor 120 can be determined by calibration, but it can be on the order of Rth = 10^6 - 10^8 K / W depending on TEM and the temperature of the sample 150. However, other thermal resistors 120 are included within the scope of the present disclosure, and other values of Rth may be selected according to the application.

[0025] In some embodiments, the electrical resistor 144 may comprise any ordinary conductive material that does not undergo a transition during the expected operation (e.g., an ordinary metal with a lower Tc than the phase change material 134, or an ordinary metal without a Tc). In other embodiments, the phase change material 134 itself may function as the electrical resistor 144. In the latter embodiments, a relatively high voltage may be applied to the probe circuit 130 such that the phase change material 134 self-heats or partially self-heats. The latter embodiments may be desirable in some applications due to their simplicity and / or reliability.

[0026] FIG. 2A is a schematic diagram of a second sensor 200 that is consistent with some embodiments. Similar to sensor 100, sensor 200 can include a thermal resistor 220 having a thermal resistance value that is Rth; a probing circuit 230 comprising a TEM such as a phase change material 234, an adjustable current source 236, and a first voltmeter 238; and a heating circuit 240 comprising a Joule heat dissipation electrical resistor 244 electrically coupled to a second adjustable current source 246 and a second voltmeter 248.

[0027] In sensor 200, the phase change material 234 may exhibit hysteresis. That is, the transition temperature of the phase change material 234 may depend on the direction of the temperature ramp, where the higher transition temperature is Tc1 and the lower transition temperature is Tc2. Examples of phase change materials 234 that exhibit the hysteresis effect include, but are not limited to, vanadium dioxide (VO2). VO2 can be integrated into conventional CMOS integrated circuit designs and, because of its high transition temperature, embodiments using VO2 may be desirable. Other suitable metals and superconducting materials that exhibit the hysteresis effect can be found in Reviews of Modern Physics, Vol. 70, No. 4, October 1998, 0034 - 6861 / 98 / 70(4) / 1039(225), and their operating temperatures can range from several tens of K to several hundreds of K. By using this embodiment of sensor 200, any sample temperature below Tc1 can be measured.

[0028] During operation, the power P supplied to the heating circuit 240 can be increased and decreased such that the transition points Tc1 and Tc2 are alternatively triggered (i.e., the supplied P in sensor 200 is a function of time), and the power P can be independently measured at each transition point. Then, for both measurement values of the resulting power P, Equation 1 can be solved simultaneously. Further, this can potentially enable the calculation of both the temperature of sample 150 and the accurate value of Rth. That is, one of the features and advantages of sensor 200 is that self - calibration is possible. FIGS. 2B, 2C, and 2D are examples for the description of a second sensor 200 during operation. Specifically, FIGS. 2B and 2C show resistance and P(t) curves in an example for illustration, and FIG. 2D shows two equations (e.g., Equations 3 - 4) including two unknowns (i.e., R th and T サンプル ) that can be used for self - calibration. Equation 3: T サンプル = T c1 - R th P1 Equation 4: T サンプル = T c2 - Rth P2 Equation 5: R th =(T c1 -T c2 ) / (P1 - P2) Equation 6: T サンプル =T c1 -P1(T c1 -T c2 ) / (P1 - P2)

[0029] Figure 3 is a schematic diagram of a third sensor 300 that is consistent with some embodiments. Similar to sensor 200, sensor 300 can include a thermal resistor 320 having a temperature resistance value of Rth; a probing circuit 330 including one or more current sources 336 and a voltmeter 338; and a heating circuit 340 including a Joule heat dissipation electrical resistor 344 electrically coupled to a second adjustable current source 346 and a second voltmeter 348. Additionally, sensor 300 can include two TEMs, such as two phase change materials 334a and 334b having different critical temperatures. Phase change materials 334a and 334b can each be of the single transition end type discussed with reference to FIG. 1, or of the hysteresis type discussed with reference to FIG. 2A. As shown in FIG. 3, phase change materials 334a, 334b can be separated from sample 150 by the same (i.e., single) thermal resistor 320. However, embodiments in which phase change materials 334a, 334b also have their own independent thermal resistors 320 are also within the scope of the present disclosure. In FIG. 3, the two TEMs can be integrated into the probing circuit as parallel resistors. Depending on the specific TEMs selected, it may be advantageous to configure the series resistors, or to divide the probing circuit 330 into one of two circuits for each TEM. These latter embodiments are also included in the present disclosure.

[0030] Advantageously, the different phase change materials 334a and 334b within the sensor 300 can be selected such that they have significantly different critical temperatures (e.g., in the hysteresis type, such that both Tc1 and Tc2 of material 334a are lower than Tc1 and Tc2 of material 334b). In this way, a relatively wider temperature range can be made available to the sensor 300 with high accuracy. Additionally, embodiments of the sensor 300 can collect two independent measurements for P from the two transition end materials 334a and 334b, and thus may be desirable in applications where self-calibration is desired in a single transition end TEM. Then, as described with reference to sensor 200, Equation 2 can be solved simultaneously to calculate both the sample temperature and Rth. FIG. 4 is a schematic diagram of a fourth sensor 400 that is consistent with some embodiments. Similar to sensor 200, sensor 400 can include a thermal resistor 420 having a temperature resistance value that is Rth; a probing circuit 430 including a TEM such as a phase change material 434, a first adjustable current source 436, and a voltmeter 438; and a heating circuit 440 including a Joule heat release electrical resistor 444 electrically coupled to a second adjustable current source 446 and a second voltmeter 448. In operation, in some applications, the temperature of the sample 150 can change significantly (e.g., depending on the coupling to the thermal environment and its heat capacity) due to the heat P generated during the measurement process, and thus this fourth sensor 400 can power its heating circuit 440 dynamically / intermittently. That is, for each temperature measurement T by the sensor 400, the power P applied to the heating circuit 440 can ramp from zero (0) to P1 (i.e., the measured power when the phase change material 434 is at Tc1), and then immediately ramp downward back to zero power. Some embodiments can also measure P2 (i.e., the measured power when the phase change material 434 is at Tc2), as described with reference to FIG. 2B. In still other embodiments, the sensor 400 can measure the time (t1) until the critical temperature Tc1 is reached at a known heating rate (p), and then use Equation 7 to infer the measured value of the power P. Equation 7: P(tx) = p × tx Thus, when p is known, the measured value of the voltage can be replaced by the measured value of the time Tx until reaching TC1.

[0031] FIG. 5 is a schematic representation of a scanning electron micrograph of a first sample temperature sensor 500 that is consistent with some embodiments. This first sample sensor 500 is a MEMS-based device (where MEMS represents microelectromechanical system) comprising a heater 534, a phase change material 540, and electrical conductors 560a and 560b. This sensor can measure the temperature of a chip, or other sample of interest. In this sensor 500, the thermal resistance element (described above) can comprise two electrical conductors 560a and 560b. Since the lengths of these conductors 560a and 560b are substantially longer than their diameters, their physical configuration limits the thermal conductivity along the length dimension, resulting in an effective thermal resistance (Rth) of about 10^7 K / W. The heater 540 within the sensor 500 can comprise a platinum thin film resistor 534 that is electrically connected by conductor 560B. The phase change material 530 within the sensor 500 can be VO2.

[0032] Figure 6 is a schematic representation of a scanning electron micrograph of a second sample temperature sensor 600 that is consistent with some embodiments. This second sample sensor 600 is an integrated CMOS semiconductor device that includes a plurality of stacked layers on a substrate 650. These layers may be closely connected to each other. As used herein, the term "closely connected" may be used to describe the connection between two components, specifically components that are directly connected or in contact with each other and / or components that should be directly connected except for, for example, an oxide layer therebetween. Starting from the substrate 650 and proceeding in the distal direction, these layers may include a thermal resistor layer 620, a first conductor 660a, a phase change material 634, and a second conductor 644. In this CMOS-based embodiment, exemplary choices of materials include VO2 for the phase change material 634, SiO2 for the thermal resistor layer 620, and a Ni / Pt alloy for the electrical conductors 644 and 660a. Embodiments that use VO2 for the phase change material 634 may be desirable because VO2 can be integrated into CMOS integrated circuit designs.

[0033] Sensor 600 is relatively simpler than sensor 500 and can better withstand damage due to G-forces, so it may be desirable for use in general CMOS applications. Additionally, the wiring process (back end of line: BEOL) dielectric or silicon oxide layer is a relatively good thermal insulator, so it is possible to reach a thermal resistance of about >10^6 K / W using submicron sensors, and the power dissipated by sensor 600 is usually not a major concern in such applications, so sensor 600 may be desirable for on-chip temperature measurement. Since the chip design of a VO2-based oscillatory neural network specifies a well-controlled chip temperature, sensor 600 may also be desirable in a VO2-based oscillatory neural network.

[0034] FIG. 7 is a flowchart showing a method 700 for measuring the temperature of a sample that is consistent with some embodiments. Specifically, method 700 can be used with one or more of the sensors described with reference to FIGS. 1-6. In operation 705, the sensor can be physically attached to the sample. The sensor can include a sensor element having an operating range, a thermal resistor separating the sensor element from the sample, and a heating circuit configured to maintain the sensor element within the operating range. The sensor element can include a phase change material. In operation 710, the sensor element can be heated to a temperature within its operating range. In some embodiments, heating the sensor element to its operating range can include applying an amount of electrical power to the heating circuit; in other embodiments, it can include applying an amount of electrical power to the sensor element. In some embodiments, hysteresis in the transition in the phase change material can be periodically induced by a time change in the amount of electrical power applied to the sensor element.

[0035] Next, in operation 720, the amount of electrical power applied to maintain the sensor element at a certain temperature can be measured. In some embodiments, this can include measuring a first amount of electrical power applied to the sensor element at a first critical temperature of the phase change material, measuring a second amount of electrical power applied to the sensor element at a second critical temperature of the phase change material, and calibrating the sensor element and the thermal resistor using the measured first and second amounts of electrical power. In operation 730, the measured amount of electrical power can be converted to the temperature of the sample, and in operation 740, the converted temperature can be output. In operation 750, the amount of electrical power applied to heat the sensor element can be removed, which can enable the sample to be cooled. Operations 710-750 can be repeated to dynamically apply and reduce the amount of dissipated electrical power. General

[0036] The description of various embodiments of the present disclosure has been presented for illustrative purposes, but it is not intended to be exhaustive or limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terms used herein are selected to explain the principles of the embodiments, practical applications, or technological improvements to the technology found in the market, or to enable other skilled artisans to understand the embodiments disclosed herein.

[0037] Accordingly, it is desired that the embodiments described herein be considered illustrative rather than restrictive in all respects, and that the scope of the invention be determined with reference to the appended claims.

Claims

1. A probe circuit, the probe circuit having a thermal operating range; A thermal resistor separating the probe circuit from a sample; and A heating circuit configured to maintain the probe circuit within the thermal operating range A temperature sensor comprising.

2. The temperature sensor according to claim 1, wherein the heating circuit has a Joule dissipation resistor electrically coupled to a second current source and a second voltmeter.

3. The temperature sensor according to claim 1, wherein the probe circuit has a transfer gate sensor element electrically coupled to a first current source and a first voltmeter.

4. The temperature sensor according to claim 3, wherein the heating circuit and the thermal resistor are connected in a proximal direction with respect to the transfer gate sensor element.

5. The temperature sensor according to claim 3, wherein the transfer gate sensor element includes a first phase change material.

6. The first phase change material contains vanadium dioxide (VO ２ ), and the temperature sensor according to claim 5.

7. The temperature sensor according to claim 5, wherein the first phase change material has a first critical temperature when heated and a second critical temperature when cooled.

8. The temperature sensor according to claim 7, wherein the temperature sensor self-calibrates.

9. The temperature sensor according to claim 5, wherein the transfer gate sensor element further includes a second phase change material, and the critical temperature of the first phase change material is higher than the critical temperature of the second phase change material.

10. The temperature sensor according to claim 5, wherein the heating circuit has the first phase change material electrically coupled to the first current source and the first voltmeter.

11. The temperature sensor according to claim 3, wherein the thermal resistor has a metal beam portion, and the metal beam portion is configured to conduct current to the transfer gate sensor element.

12. A substrate; and A contact thermometer attached to the substrate, the contact thermometer A probe circuit, the probe circuit including a thermal operating range; A thermal resistor separating the probe circuit from the substrate; and A heating circuit configured to maintain the probe circuit within the thermal operating range Having A semiconductor device comprising.

13. Heating a sensor element to a temperature within the thermal operating range of the sensor; Measuring the amount of electrical power applied to maintain the sensor element at the temperature; and Converting the measured amount of electrical power to a sample temperature; and Outputting the sample temperature A method for measuring the temperature of a sample comprising.

14. The method according to claim 13, wherein the sensor element includes a phase change material.

15. The method according to claim 14, further comprising the step of separating the phase change material from the sample using a thermal resistor.

16. The method according to claim 15, wherein the hysteresis of the transition in the phase change material is periodically induced by a temporal change in the amount of electric power applied to the sensor element.

17. Measuring a first amount of electric power applied to the sensor element at a first critical temperature of the phase change material; Measuring a second amount of electric power applied to the sensor element at a second critical temperature of the phase change material; and Calibrating the sensor element and the thermal resistor using the measured first and second amounts of electric power The method according to claim 16, further comprising the steps of:

18. The method according to claim 13, wherein the step of heating the sensor element to its thermal operating range includes applying the amount of electric power to a heating circuit.

19. The method according to claim 13, wherein the step of heating the sensor element includes applying the amount of electric power to the sensor element.

20. The method according to claim 13, wherein the amount of electric power applied to heat the sensor element is repeatedly applied and removed.

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