Highly sensitive silicon carbide integrated temperature sensor

Abstract

The object of the present invention is to provide a highly sensitive silicon carbide integrated temperature sensor. [Solution] The present invention relates to a highly sensitive silicon carbide integrated temperature sensor, belonging to the technical field of power semiconductor devices. In the temperature sensor of the present invention, the voltage drops on the N-type and P-type silicon carbide semiconductors have positive and negative temperature coefficients, respectively, so the difference in voltage drops on the two electrodes is amplified with the rate of change of temperature. The temperature sensor of the present invention has a wide temperature measurement range, high temperature sensitivity, and can be monolithically integrated into a silicon carbide power semiconductor, ensuring compatibility with manufacturing processes. The temperature sensor is electrically isolated from a master device via a P-type region, so the operating states of the temperature sensor and the master device are not affected by each other. Furthermore, because the currents in the P-type and N-type semiconductors are small, the currents in the N-type and P-type semiconductors are also not affected by each other.

Description

[Technical field]

[0001] The present invention relates to the technical field of power semiconductor devices, and in particular to a highly sensitive silicon carbide integrated temperature sensor. [Background technology]

[0002] SiC, a wide bandgap semiconductor material, is an ideal material for the manufacture of high-voltage power devices. Compared with Si materials, it has advantages such as high dielectric breakdown field strength (4×10 6 V / cm), high carrier saturation drift velocity (2×10 7 cm / s), high thermal conductivity, and good thermal stability, making it particularly suitable for high-power, high-voltage, high-temperature, and radiation-resistant electronic devices.

[0003] SiC VDMOS is a commonly used device in SiC power devices, which has better frequency characteristics and lower switching losses compared to bipolar devices due to the absence of charge storage effect, while the wide band gap of SiC material allows the operating temperature of SiC VDMOS to be increased by up to 300°C.

[0004] However, SiC VDMOS has a relatively prominent problem, namely, the carrier mobility on the device surface is very low, which is due to the existence of a large amount of unsaturated bonds and other defects at the SiC / SiO2 interface, which makes the state of the SiC / SiO2 interface severe, which leads to a large surface resistance (channel resistance), and the power consumption of the channel under this influence is even comparable to the power consumption of the drift region. SiC VDMOS often operates at a large current, so the heating of the device becomes very serious, and if the temperature is too high, it will reduce some of the performance of the device and even cause functional failure. Up to now, the main factors limiting SiC VDMOS have been the packaging technology and the lack of information on the temperature of the safe operating area, especially the effect of temperature on the reliability of the gate oxide.

[0005] Those skilled in the art can obtain the temperature information of the device by measuring the package temperature, but because the temperature inside the device is closely related to the resistance of each part of the device, there will also be a difference between the temperature inside the device and the package temperature. In monitoring the device temperature, a temperature sensor can be integrated separately from the master device in the package, but this method cannot obtain the temperature information of the device most directly and quickly, and the measured temperature is not accurate. If the channel resistance Rch or the JFET region resistance RJFET is large, the power consumption on the surface of the device will be large, and the surface temperature will also be high, and the high temperature on the surface will most likely reduce the reliability of the gate oxide layer of the device, so there is an urgent need to establish a new method for monitoring the surface temperature of the device so that the fastest and most accurate temperature information can be obtained. Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention has been made in consideration of the problems of the conventional technology, and provides a highly sensitive silicon carbide integrated temperature sensor in the context of the need to measure the junction temperature of a power semiconductor and the inaccuracy and low sensitivity of the temperature measurement of conventional temperature sensors. [Means for solving the problem]

[0007] In order to solve the above technical problems, an embodiment of the present invention provides a semiconductor device including a first PAD region 1, a second PAD region 2, a third PAD region 3, a P-type well region 4, an N-type well region 5, a first metal 6, a second metal 7, a third metal 8, a first ohmic contact region 9, a second ohmic contact region 10, and a third ohmic contact region 11; the N-type well region 5 and the second ohmic contact region 10 are located in the P-type well region 4 with a gap therebetween, the first ohmic contact region 9 is in the N-type well region 5, and the third ohmic contact region 11 is in the P-type well region 4 and is connected to the P-type well region 4 and the N-type well region 5; The third ohmic contact region 11 extends from the first metal 6 to the first PAD region 1, the first ohmic contact region 9 extends from the second metal 7 to the second PAD region 2, and the second ohmic contact region 10 extends from the third metal 8 to the third PAD region 3, providing a highly sensitive silicon carbide integrated temperature sensor.

[0008] Based on the above technical means, the present invention can also be improved as follows.

[0009] Furthermore, the P-type well region 4 is formed by aluminum ion implantation.

[0010] Furthermore, the N-type well region 5 is formed by phosphorus ion implantation.

[0011] Furthermore, the doping concentration of the P-type well region 4 is in the range of 1e15 cm-3 to 1e20 cm-3 and / or the doping concentration of the N-type well region 5 is in the range of 1e15 cm-3 to 1e19 cm-3.

[0012] Furthermore, the implantation depth of the P-type well region 4 is deeper than that of the N-type well region 5 .

[0013] Furthermore, the second ohmic contact region 10 is formed by the same ion implantation type as that of the P-type well region 4 .

[0014] Furthermore, the doping concentration of the second ohmic contact region 10 is in the range of 1e18 cm-3 to 1e21 cm-3.

[0015] Furthermore, the first ohmic contact region 9 is formed by the same ion implantation type as that of the N-type well region 5 .

[0016] Furthermore, the doping concentration of the first ohmic contact region 9 is in the range of 1e18 cm-3 to 1e22 cm-3.

[0017] Furthermore, the first metal 6, the second metal 7 and the third metal 8 are made of aluminum. Effect of the Invention

[0018] Compared with the prior art, the advantages of the present invention include: 1. The N-type implant and P-type implant can be completed simultaneously with other manufacturing processes of the master device, so that the temperature sensor can be integrated into the power semiconductor if it is compatible with the manufacturing process; 2. The high sensitivity silicon carbide integrated temperature sensor of the present invention and the master device are sufficiently electrically insulated and isolated through the P-type well region 4, and their operating states do not affect each other; 3. When the doping concentration is constant, the sensitivity is fixed regardless of whether N-type silicon carbide or P-type silicon carbide is used. The present invention proposes a method of using the surface and volume resistance of N-type silicon carbide and P-type silicon carbide in parallel to measure temperature, and when a constant current is applied to each of the two resistance regions, the voltage drop on N-type silicon carbide has a positive temperature coefficient, and the voltage drop on P-type silicon carbide has a negative temperature coefficient. Therefore, when the temperature is expressed by the difference in the voltage drop on these two resistors, the sensitivity of the temperature sensor of the present invention is the sensitivity of N-type silicon carbide plus the sensitivity of P-type silicon carbide, which is higher than the sensitivity of the volume resistance of any single-conductivity type silicon carbide. Therefore, the high-sensitivity silicon carbide integrated temperature sensor of the present invention has high sensitivity, and its sensitivity is higher than any conventional silicon carbide temperature sensor that measures temperature through volume resistance. [Brief description of the drawings]

[0019] [Figure 1] FIG. 1 is a schematic diagram of a highly sensitive silicon carbide integrated temperature sensor according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic diagram of a well region in a highly sensitive silicon carbide integrated temperature sensor according to an embodiment of the present invention. [Diagram 3] 3 is a cross-sectional view of a well region taken along line AA′ in FIG. 2. [Figure 4] 3 is a cross-sectional view of a well region taken along line BB' in FIG. 2. [Diagram 5] FIG. 1 is a schematic diagram of an equivalent circuit of a highly sensitive silicon carbide integrated temperature sensor according to an embodiment of the present invention (i.e., a schematic diagram of the temperature measurement principle). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] The principles and features of the present invention will now be described with reference to the accompanying drawings, in which: The given examples are intended to aid in the explanation of the invention, but are not intended to limit the scope of the invention in any way. EXAMPLES

[0021] As shown in FIGS. 1 to 4, the high sensitivity silicon carbide integrated temperature sensor provided by the first embodiment of the present invention includes a first PAD region 1, a second PAD region 2, a third PAD region 3, a P-type well region 4, an N-type well region 5, a first metal 6, a second metal 7, a third metal 8, a first ohmic contact region 9, a second ohmic contact region 10, and a third ohmic contact region 11; the N-type well region 5 and the second ohmic contact region 10 are located in the P-type well region 4 with a gap therebetween, the first ohmic contact region 9 is in the N-type well region 5, and the third ohmic contact region 11 is in the P-type well region 4 and is connected to the P-type well region 4 and the N-type well region 5; The third ohmic contact region 11 extends from the first metal 6 to the first PAD region 1, the first ohmic contact region 9 extends from the second metal 7 to the second PAD region 2, and the second ohmic contact region 10 extends from the third metal 8 to the third PAD region 3.

[0022] The working principle of this invention: An equivalent circuit diagram of the temperature sensor is shown in Figure 5. By applying a constant small current I1 to the second PAD region 2, a voltage drop V1 occurs in the N-type silicon carbide, and by applying a constant small current I2 to the third PAD region 3, a voltage drop V2 occurs in the P-type silicon carbide. In N-type silicon carbide, lattice scattering increases rapidly with increasing temperature, and the mobility decreases, which increases the resistance, so V1 increases with increasing temperature.

[0023] In addition, impurities in P-type silicon carbide are not completely ionized at room temperature, and as the temperature increases, the impurities that become ionized increase the effective doping concentration of the P-type silicon carbide, decreasing its resistance, so that V2 decreases with increasing temperature.

[0024] If the rate of change of V1 with temperature is expressed as S1, then S1 = dV1 / dT, where S1 is positive, and if the rate of change of V2 with temperature is expressed as S2, then S2 = dV2 / dT, where S2 is negative. By measuring the voltages across ports 1 and 2, V = V1-V2 is obtained, which gives a linear approximation between the potential difference V and temperature T. After fitting and calibration, the operating temperature of the device can be obtained by fitting to the following equation:

[0025] (Number 1) T = a × V + b where a and b are fitting parameters, and the sensitivity of the temperature sensor is expressed as follows and is the sum of the sensitivities of the two semiconductor regions:

[0026] (Number 2) S = dV / dT = S1-S2 = |S1|+|S2|

[0027] Optionally, the P-type well region 4 is formed by aluminum ion implantation.

[0028] Optionally, said N-type well region 5 is formed by phosphorus ion implantation.

[0029] Optionally, the doping concentration of the P-type well region 4 is in the range of 1e15 cm-3 to 1e20 cm-3 and / or the doping concentration of the N-type well region 5 is in the range of 1e15 cm-3 to 1e19 cm-3.

[0030] Optionally, the implantation depth of said P-type well region 4 is deeper than said N-type well region 5 .

[0031] Optionally, the second ohmic contact region 10 is formed by the same ion implantation type as the P-type well region 4 .

[0032] Optionally, the doping concentration of the second ohmic contact region 10 is in the range of 1e18 cm −3 to 1e21 cm −3 .

[0033] Optionally, the first ohmic contact region 9 is formed by the same ion implantation type as the N-type well region 5 .

[0034] Optionally, the doping concentration of the first ohmic contact region 9 is in the range of 1e18 cm −3 to 1e22 cm −3 .

[0035] Optionally, said first metal 6, said second metal 7 and said third metal 8 are made of aluminium.

[0036] The temperature sensor of the present invention has three electrodes, the first electrode consisting of the first PAD region covers the P-type region and the N-type region at the same time, the second electrode consisting of the second PAD region is connected to the P-type region, and the third electrode consisting of the third PAD region is connected to the N-type region. The first electrode of the temperature sensor is generally shorted to the source or cathode of the master device, and a small current is applied to the second electrode and the third electrode, respectively, at this time, the voltage difference between the second electrode and the third electrode and the temperature satisfy a linear approximation relationship, and through fitting and calibration, the operating temperature of the device can be represented by measuring the voltage difference between the second electrode and the third electrode. Since the voltage drop on the silicon carbide N-type semiconductor has a positive temperature coefficient and the voltage drop on the P-type semiconductor has a negative temperature coefficient, the difference in the voltage drop on the two electrodes is amplified with the rate of change of temperature. The temperature sensor of the present invention has a wide temperature measurement range, high temperature measurement sensitivity, and can be monolithically integrated into a silicon carbide power semiconductor and is compatible with the manufacturing process. The temperature sensor is electrically isolated from the master device through the P-type region, so that the operating states of the temperature sensor and the master device do not affect each other, and the currents in the N-type and P-type semiconductors do not affect each other because the currents in the P-type or N-type semiconductors are small.

[0037] In the drawings of the present specification, the frame lines corresponding to each component are only used to distinguish different components and have no structural meaning.

[0038] It should be noted that in the description of the present invention, the terms "first" and "second" are used merely for descriptive purposes and should not be understood as indicating or suggesting a relative importance or implicitly indicating the number of technical features shown. Thus, the feature to which "first" and "second" are applied expressly or imply includes one or more of said features. Furthermore, in the present invention, unless otherwise stated, "plurality" means at least two, e.g., two, three, etc.

[0039] In the description of this specification, a description referring to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in combination with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the definitions given to the above terms are not necessarily directed to the same embodiment or example. In addition, the specific features, structures, materials, or characteristics described can be combined in any suitable manner in any one or more embodiments or examples. It should be noted that, if not mutually inconsistent, a person skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples.

[0040] In addition, although the preferred embodiments of the present invention have been disclosed as above, they are not intended to limit the present invention in any way. Modifications, equivalent replacements, improvements, etc. made without departing from the spirit and principles of the present invention are equally included in the protection scope of the present invention. [Explanation of symbols]

[0041] 10 Second Ohmic Contact Region 1 1st PAD area 11 Third ohmic contact region 2 2nd PAD area 3 3rd PAD area 4 P-type well region 5 N-type well region 6 First metal 7 Second metal 8 Third metal 9 First Ohmic Contact Region

Claims

[Claim 1] A highly sensitive silicon carbide integrated temperature sensor comprising a first PAD region (1), a second PAD region (2), a third PAD region (3), a P-type well region (4), an N-type well region (5), a first metal (6), a second metal (7), a third metal (8), a first ohmic contact region (9), a second ohmic contact region (10), and a third ohmic contact region (11); The N-type well region (5) and the second ohmic contact region (10) are located in the P-type well region (4) with a gap therebetween, the first ohmic contact region (9) is in the N-type well region (5), and the third ohmic contact region (11) is in the P-type well region (4) and is connected to the P-type well region (4) and the N-type well region (5); The first metal (6) connects the third ohmic contact region (11) and the first PAD region (1), the second metal (7) connects the first ohmic contact region (9) and the second PAD region (2), and the third metal (8) connects the second ohmic contact region (10) and the third PAD region (3); A first electrode formed of the first PAD region is simultaneously connected to the P-type well region (4) and the N-type well region (5) through the first metal (6) and the third ohmic contact region (11), a second electrode formed of the second PAD region is connected to the N-type well region (5) through the second metal (7) and the first ohmic contact region (9), and a third electrode formed of the third PAD region is connected to the P-type well region (4) through the third metal (8) and the second ohmic contact region (10). A small current is applied to the second electrode and the third electrode, respectively, and a voltage difference between the second electrode and the third electrode and a temperature satisfies a linear approximation relationship, and the operating temperature of the device can be represented by measuring the voltage difference between the second electrode and the third electrode through fitting and calibration. A highly sensitive silicon carbide integrated temperature sensor.

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