High-temperature reverse bias test method, electrostatic discharge protection structure and electronic equipment

Abstract

The invention relates to the technical field of semiconductors, in particular to a high-temperature reverse bias test method, an electrostatic discharge protection structure and electronic equipment, and the method comprises the steps: providing the electrostatic discharge protection structure; determining an initial leakage current at the initial voltage, and determining an initial breakdown voltage at the initial current; heating the electrostatic discharge protection structure for a preset time at a preset temperature and a preset voltage, and determining a target leakage current of the heated electrostatic discharge protection structure under the initial voltage and a target breakdown voltage of the heated electrostatic discharge protection structure under the initial current; performing current change analysis on the initial leakage current and the target leakage current to obtain a current change result, and performing voltage change analysis on the initial breakdown voltage and the target breakdown voltage to obtain a voltage change result; and according to the current change result and the voltage change result, generating a high-temperature reverse bias test result of the electrostatic discharge protection structure. According to the invention, the reliability of the electrostatic discharge protection structure can be accurately evaluated.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of semiconductor manufacturing, and in particular, to a high-temperature reverse bias test method, an electrostatic discharge protection structure, and an electronic device. BACKGROUND

[0002] The electrostatic discharge protection (ESD) structure based on PNP includes two structures of shallow trench isolation (STI) and a blocking layer (SAB), but the area of the STI structure is twice that of the SAB, and therefore, the SAB structure is increasingly widely used.

[0003] However, the SAB PNP ESD fails in the high temperature and humidity test (HAST) and the high and low temperature aging (HTOL) process, and the failure mechanism is that the surface junction of the SAB degrades. The related technology usually uses a transmission line pulse (TLP) to detect the ESD level, but there are the following limitations for the TLP test of the ESD circuit: there are many parasitic bipolar transistors (BJT) paths in the high-voltage ESD device, and the error of using the TLP test to measure the human body discharge model (HBM) of the device will increase. The related technology also uses an IV loop test to determine the low-voltage ESD level, but since there is no standard to evaluate it, it cannot be predicted that the breakdown voltage (BV) will degrade below the operating voltage (Vop), resulting in the failure of the test method.

[0004] Therefore, it is particularly important to provide a high-temperature reverse bias test method to accurately evaluate the reliability of the SAB PNP ESD structure. SUMMARY

[0005] The present application provides a high-temperature reverse bias test method, an electrostatic discharge protection structure, and an electronic device to at least solve the above problems in the related art.

[0006] To solve the above technical problems, the technical solutions of the present application are as follows:

[0007] According to a first aspect of an embodiment of the present application, a high-temperature reverse bias test method for an electrostatic discharge protection structure is provided, and the method comprises:

[0008] An electrostatic discharge protection structure is provided, and the electrostatic discharge protection structure comprises a PNP structure and a blocking layer, and the blocking layer is used to isolate the PNP structure;

[0009] An initial leakage current of the electrostatic discharge protection structure is determined at an initial voltage, and an initial breakdown voltage of the electrostatic discharge protection structure is determined at an initial current;

[0010] in the case that the initial leakage current and the initial breakdown voltage satisfy respective preset conditions, heating the electrostatic discharge protection structure at a preset temperature and a preset voltage for a preset time, and determining a target leakage current of the heated electrostatic discharge protection structure at the initial voltage and a target breakdown voltage of the heated electrostatic discharge protection structure at the initial current;

[0011] performing current variation analysis on the initial leakage current and the target leakage current to obtain a current variation result of the electrostatic discharge protection structure, and performing voltage variation analysis on the initial breakdown voltage and the target breakdown voltage to obtain a voltage variation result of the electrostatic discharge protection structure;

[0012] generating a high-temperature reverse bias test result of the electrostatic discharge protection structure according to the current variation result and the voltage variation result.

[0013] In an optional embodiment, the PNP structure includes a base, a collector and an emitter, and the initial voltage includes a voltage between the emitter and the base and a collector voltage; and the determining of the initial leakage current of the electrostatic discharge protection structure at the initial voltage includes:

[0014] determining the initial leakage current of the electrostatic discharge protection structure in the case that the collector voltage is 0 V and the voltage between the emitter and the base is 1.1 times to 1.4 times of a working voltage at room temperature.

[0015] In an optional embodiment, the determining of the initial breakdown voltage of the electrostatic discharge protection structure at the initial current includes:

[0016] determining the initial breakdown voltage of the electrostatic discharge protection structure in the case that the initial current is 1E -7 A to 1E -10 A at room temperature.

[0017] In an optional embodiment, the PNP structure includes a base, a collector and an emitter, and the initial voltage includes a voltage between the emitter and the base and a collector voltage; and the heating of the electrostatic discharge protection structure at a preset temperature and a preset voltage for a preset time and the determining of a target leakage current of the heated electrostatic discharge protection structure at the initial voltage and a target breakdown voltage of the heated electrostatic discharge protection structure at the initial current include:

[0018] heating the electrostatic discharge protection structure for a preset time in the case that the preset temperature is 125℃ to 175℃ and the voltage between the emitter and the base is 1.1 times to 1.4 times of a working voltage;

[0019] determining a target leakage current of the electrostatic discharge protection structure after heating at room temperature, when the collector voltage is 0V and the voltage between the emitter and the base is 1.1 times the working voltage to 1.4 times the working voltage, and determining a target breakdown voltage of the electrostatic discharge protection structure after heating at room temperature, when the initial current is 1E -7 A~1E -10 A.

[0020] In an optional embodiment, the PNP structure includes a base, a collector and an emitter, the initial voltage includes a voltage between the emitter and the base and a collector voltage; the heating the electrostatic discharge protection structure at a preset temperature and a preset voltage for a preset time, and determining a target leakage current of the electrostatic discharge protection structure after heating at the initial voltage and a target breakdown voltage of the electrostatic discharge protection structure after heating at the initial current, includes:

[0021] heating the electrostatic discharge protection structure at a preset temperature of 125℃ to 175℃ and a voltage between the emitter and the base of 1.1 times the working voltage to 1.4 times the working voltage for a first time to obtain a first electrostatic discharge protection structure;

[0022] determining a first candidate leakage current of the first electrostatic discharge protection structure at room temperature, when the collector voltage is 0V and the voltage between the emitter and the base is 1.1 times the working voltage to 1.4 times the working voltage, and determining a first candidate breakdown voltage of the first electrostatic discharge protection structure at room temperature, when the initial current is 1E -7 A~1E -10 A.

[0023] In a case where the current change result determined based on the first candidate leakage current and the voltage change result determined based on the first candidate breakdown voltage are not abnormal, continuing to heat the first electrostatic discharge protection structure at a preset temperature of 125℃ to 175℃ and a voltage between the emitter and the base of 1.1 times the working voltage to 1.4 times the working voltage for a second time to obtain a second electrostatic discharge protection structure;

[0024] determining a second candidate leakage current of the second electrostatic discharge protection structure at room temperature, when the collector voltage is 0V and the voltage between the emitter and the base is 1.1 times the working voltage to 1.4 times the working voltage, and determining a second candidate breakdown voltage of the second electrostatic discharge protection structure at room temperature, when the initial current is 1E -7 A~1E -10 A.

[0025] In a case where the current change result determined based on the second candidate leakage current and the voltage change result determined based on the second candidate breakdown voltage are not abnormal, the second electrostatic discharge protection structure is continuously heated for a third time under a condition that a preset temperature is 125℃-175℃ and a voltage between the emitter and the base is 1.1 times working voltage-1.4 times, to obtain a third electrostatic discharge protection structure;

[0026] determining a third candidate leakage current of the third electrostatic discharge protection structure under a condition that a room temperature is 25℃, the collector voltage is 0V, and a voltage between the emitter and the base is 1.1 times working voltage-1.4 times working voltage, and determining a third candidate breakdown voltage of the third electrostatic discharge protection structure under the condition that the room temperature is 25℃, the initial current is 1E -7 A-1E -10 A;

[0027] determining the third candidate leakage current as the target leakage current, and determining the third candidate breakdown voltage as the target breakdown voltage;

[0028] wherein a sum of the first time, the second time and the third time is equal to the preset time.

[0029] In an optional embodiment, the current change analysis on the initial leakage current and the target leakage current to obtain the current change result of the electrostatic discharge protection structure comprises:

[0030] determining a current difference between the initial leakage current and the target leakage current;

[0031] performing current change analysis on the current difference and the initial leakage current to obtain the current change result.

[0032] In an optional embodiment, the voltage change analysis on the initial breakdown voltage and the target breakdown voltage to obtain the voltage change result of the electrostatic discharge protection structure comprises:

[0033] determining a voltage difference between the initial breakdown voltage and the target breakdown voltage;

[0034] performing voltage change analysis on the voltage difference and the initial breakdown voltage to obtain the voltage change result.

[0035] In an optional embodiment, the generating of the high-temperature reverse bias test result of the electrostatic discharge protection structure according to the current change result and the voltage change result comprises:

[0036] providing a current change threshold and a voltage change threshold;

[0037] In a case that the current change result is less than or equal to the current change threshold value, and the voltage change result is less than or equal to the voltage change threshold value, it is determined that the high-temperature reverse bias test result of the electrostatic discharge protection structure is a test qualified result.

[0038] In a case that the current change result is greater than the current change threshold value, and / or the voltage change threshold value is greater than the voltage change threshold value, it is determined that the high-temperature reverse bias test result of the electrostatic discharge protection structure is a test unqualified result.

[0039] In an optional embodiment, before the determining the target leakage current of the heated electrostatic discharge protection structure at the initial voltage, and the target breakdown voltage of the heated electrostatic discharge protection structure at the initial current, the method further comprises:

[0040] performing an alternating voltage reduction and temperature reduction treatment on the heated electrostatic discharge protection structure until the voltage of the heated electrostatic discharge protection structure is 0V and the temperature of the heated electrostatic discharge protection structure is room temperature;

[0041] The determining the target leakage current of the heated electrostatic discharge protection structure at the initial voltage, and the target breakdown voltage of the heated electrostatic discharge protection structure at the initial current comprises:

[0042] determining the target leakage current of the electrostatic discharge protection structure at the initial voltage, and the target breakdown voltage of the electrostatic discharge protection structure at the initial current, in which the voltage of the electrostatic discharge protection structure is 0V and the temperature of the electrostatic discharge protection structure is room temperature.

[0043] In an optional embodiment, the providing the electrostatic discharge protection structure comprises:

[0044] providing an initial semiconductor structure;

[0045] cutting the initial semiconductor structure based on a laser cutting mode to obtain a cut structure;

[0046] encapsulating the cut structure by a large exposed-back heat sink and heat-conductive silver glue based on a preset encapsulation mode to obtain the electrostatic discharge protection structure;

[0047] The size of the electrostatic discharge protection structure corresponds to the size allowed by the preset encapsulation mode.

[0048] In an optional embodiment, the determining the initial leakage current of the electrostatic discharge protection structure at the initial voltage, and the initial breakdown voltage of the electrostatic discharge protection structure at the initial current comprises:

[0049] performing a preset number of breakdown voltage tests on the electrostatic discharge protection structure under the same current condition to obtain a preset number of breakdown voltage test results;

[0050] If the difference between the results of the predetermined number of breakdown voltage tests is less than a predetermined difference threshold, the initial leakage current of the electrostatic discharge protection structure is determined at the initial voltage, and the initial breakdown voltage of the electrostatic discharge protection structure is determined at the initial current.

[0051] In an optional embodiment, the method further includes:

[0052] If the difference between the results of the preset number of breakdown voltage tests is greater than or equal to a preset difference threshold, the size of the electrostatic discharge protection structure is adjusted to obtain the adjusted electrostatic discharge protection structure.

[0053] Under the same current conditions, the adjusted electrostatic discharge protection structure is subjected to a preset number of breakdown voltage tests to obtain the preset number of adjusted breakdown voltage test results.

[0054] If the difference between the breakdown voltage test results after the preset number of adjustments is less than a preset difference threshold, the initial leakage current of the electrostatic discharge protection structure is determined at the initial voltage, and the initial breakdown voltage of the electrostatic discharge protection structure is determined at the initial current.

[0055] In an optional embodiment, the PNP structure includes a P-well, an N-well, and a P-well located within the N-well. + The injection region, a deep P-well located at the bottom of the P-well; the adjustment of the dimensions of the electrostatic discharge protection structure includes:

[0056] Adjust the lateral dimension of the deep P-well to be smaller than the lateral dimension of the P-well, and / or increase the inner wall of the N-well relative to the P-well. + The lateral distance between the outer walls of the injection zone.

[0057] In an optional embodiment, the increase in the inner wall of the N-well and the P + The lateral distance between the outer walls of the injection zone includes:

[0058] Decrease the P + The size of the injection region in the lateral direction, and / or, increasing the size of the N-well in the lateral direction, and / or, decreasing the size of the P-well in the lateral direction.

[0059] A second aspect of this application provides an electrostatic discharge (ESD) protection structure, wherein the ESD protection structure is subjected to a high-temperature reverse bias test method as described in any of the above embodiments, and the ESD protection structure includes:

[0060] P-type substrate; the p-type substrate includes a buried N+ layer;

[0061] Deep N-well located on the surface of both ends of the buried N+ layer; N-well bottom embedded in the top of the deep N-well, N+ injection region located on the top surface of the N-well;

[0062] Deep P-well located inside between two deep N-wells, and the bottom of the deep P-well is higher than the surface of the buried N+ layer; the top of the deep P-well is provided with a P-well, and a P+ injection region is located on the top surface of the P-well;

[0063] N-well located between two deep P-wells; P+ injection region located on the top surface of the N-well, and a barrier layer located on the top surface of the target P-well and the top surface of the part containing the N-well between the two deep P-wells; the target P-well is the P-well provided on the top of the deep P-well;

[0064] P-well located outside the deep N-well, and a P+ injection region is located on the top surface of the P-well located outside the deep N-well.

[0065] In an optional embodiment, the size of the deep P-well in the lateral direction is smaller than the size of the P-well provided on the top of the deep P-well in the lateral direction, and the distance between the inner wall of the N-well and the outer wall of the P+ injection region located in the N-well in the lateral direction is greater than a preset distance threshold.

[0066] The third aspect of the embodiments of the present application provides an electronic device, which comprises the electrostatic discharge protection structure according to any one of the above embodiments.

[0067] The technical scheme provided by the embodiments of the present application at least brings the following beneficial effects:

[0068] The high-temperature reverse bias test method of the electrostatic discharge protection structure provided by the embodiment of the application comprises the following steps: determining an initial leakage current of the electrostatic discharge protection structure at an initial voltage and determining an initial breakdown voltage of the electrostatic discharge protection structure at an initial current; in the case that the initial leakage current and the initial breakdown voltage meet respective preset conditions, heating the electrostatic discharge protection structure at a preset temperature and a preset voltage for a preset time, and determining a target leakage current of the heated electrostatic discharge protection structure at the initial voltage and a target breakdown voltage of the heated electrostatic discharge protection structure at the initial current; performing current change analysis on the initial leakage current and the target leakage current to obtain a current change result of the electrostatic discharge protection structure, and performing voltage change analysis on the initial breakdown voltage and the target breakdown voltage to obtain a voltage change result of the electrostatic discharge protection structure; and generating a high-temperature reverse bias test result of the electrostatic discharge protection structure according to the current change result and the voltage change result, so as to accurately detect the leakage current and the breakdown voltage from the three dimensions of voltage, temperature and time, determine the current change result and the voltage change result based on the detected leakage current and breakdown voltage, and accurately evaluate the reliability of the electrostatic discharge protection structure based on the current change result and the voltage change result, so that the electrostatic discharge protection structure can meet the actual application requirements.

[0069] It should be understood that the foregoing general description and the following detailed description are only exemplary and explanatory and are not restrictive of the application. BRIEF DESCRIPTION OF DRAWINGS

[0070] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the application and, together with the description, serve to explain the principles of the application, and, do not limit the application.

[0071] Figure 1 is a structure diagram of a SAB PNP ESD in the related art.

[0072] Figure 2 is a flowchart of a high-temperature reverse bias test method of an electrostatic discharge protection structure according to an exemplary embodiment Figure 1 .

[0073] Figure 3 is a PNP structure diagram according to an exemplary embodiment.

[0074] Figure 4 is a test result diagram obtained by performing three breakdown voltage tests on different types of SAB ESD PNP Figure 1 .

[0075] Figure 5is a breakdown voltage test of three times on the different types of SAB ESD PNP after adjustment, and the test results are shown in Figure 2 .

[0076] Figure 6 is a breakdown voltage test of three times on the different types of SAB ESD PNP after adjustment, and the test results are shown in Figure 3 .

[0077] Figure 7 is a breakdown voltage test of three times on the different types of SAB ESD PNP after adjustment, and the test results are shown in Figure 4 .

[0078] Figure 8 is a high temperature reverse bias test method of an electrostatic discharge protection structure according to an exemplary embodiment Figure 2 .

[0079] Figure 9 is a voltage change result diagram of different types of SAB ESD PNP according to an exemplary embodiment. DETAILED DESCRIPTION

[0080] The following detailed description is presented in terms of a number of different embodiments or examples thereof. A specific example of elements and configurations is described and illustrated herein in one practice. Of course, those of ordinary skill in the art will recognize that various elements and configurations can be selected from a wide variety of alternatives, all of which are contemplated herein. The detailed description is not to be understood as limiting the application as there is a plurality of alternative embodiments and configurations not described herein. For example, the formation of one feature over the other feature in the following description or drawing is intended to encompass a formation of the one feature over the other feature as well as a formation of the one feature in a location that is otherwise adjacent to the other feature.

[0081] In addition, spatially relative terms, such as "beneath", "below", "lower", "above", "upper", "front", "back", "behind", and the like, can be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientations depicted in the figures.

[0082] Figure 1 is a structure diagram of SAB PNP ESD in the related art, as Figure 1As shown, the SAB PNP ESD includes a p-substrate, the p-type substrate includes a buried N+ layer (BNP);

[0083] Deep N-wells located on both ends of the surface of the buried N+ layer, N-well bottom embedded in the top of the deep N-well, N+ implantation region located on the top surface of the N-well;

[0084] Deep P-wells located inside between two deep N-wells, and the bottom of the deep P-well is higher than the surface of the buried N+ layer; P-well bottom embedded in deep P-well top; P+ implantation region located on the top surface of the P-well;

[0085] N-well located between two deep P-wells; P+ implantation region located on the top surface of the N-well, and a barrier layer located on the top surface of the portion containing the N-well between the P-well embedded on the top of the deep P-well and the two deep P-wells;

[0086] P-well located outside the deep N-well, P+ implantation region located on the top surface of the P-well.

[0087] However, the SAB PNP ESD is poor in surge resistance, has a withstand voltage problem, and occurs irreversible damage and leakage under long-time conditions. The failure reason is that the effective base region (NW enclosure PP, referred to as NW package) window is insufficient, and under test conditions, the pulse wave frequency multiple is more, so that the ESD is repeatedly turned on, and higher heat / energy is generated in the repeated turning-on process, combined with the degradation of the SAB surface junction under stress, which will cause the effective area of the base region to change irreversibly due to the change of the interface charge, thereby reducing the NW package, thereby causing PNP breakdown and leakage.

[0088] High temperature reverse bias test (HTRB) is one of the methods for evaluating SAB ESD PNP structure, but there is no related evaluation method and judgment standard (SPEC) for SAB ESD PNP structure in the current international standard. Based on this, the present application implements the standard, mainly in three aspects of voltage, temperature and time, and monitors the changes of off-state current (Ioff) and breakdown voltage (BV) through HTRB test, so as to accurately evaluate the SAB ESD PNP structure.

[0089] Figure 2 A high temperature reverse bias test method of an electrostatic discharge protection structure according to an example embodiment Figure 1 As shown in Figure 2 The high temperature reverse bias test method of the electrostatic discharge protection structure includes:

[0090] S11. Provide an electrostatic discharge protection structure; the electrostatic discharge protection structure comprises a PNP structure and a barrier layer, and the barrier layer is used to isolate the PNP structure.

[0091] Optionally, the electrostatic discharge protection structure comprises a PNP structure and a barrier layer, wherein the PNP structure is a triode composed of one N-type semiconductor sandwiched between two P-type semiconductors, and the barrier layer is used to isolate the device in the PNP structure. Illustratively, the barrier layer can be a silicide barrier layer.

[0092] S12. Determine the initial leakage current of the electrostatic discharge protection structure at an initial voltage, and determine the initial breakdown voltage of the electrostatic discharge protection structure at an initial current.

[0093] In this embodiment, first, the test in the Pre Test stage is performed. In the Pre Test stage, the initial leakage current of the electrostatic discharge protection structure can be tested at a fixed initial voltage, and the initial breakdown voltage of the electrostatic discharge protection structure can be determined at a fixed initial current.

[0094] Optionally, the initial voltage and the initial current can be set according to actual business needs, which are not specifically limited.

[0095] Optionally, the leakage current can refer to the off-state current (Ioff).

[0096] It should be noted that the test in the Pre Test stage is mainly to detect whether the electrostatic discharge protection structure is a good product. If it is a good product, subsequent detection operations are performed. If it is not a good product, subsequent detection operations are not performed.

[0097] S13. In the case where the initial leakage current and the initial breakdown voltage meet the respective preset conditions, the electrostatic discharge protection structure is heated at a preset temperature and a preset voltage for a preset time, and the target leakage current of the heated electrostatic discharge protection structure at the initial voltage and the target breakdown voltage at the initial current are determined.

[0098] In this embodiment, in the case where the initial leakage current and the initial breakdown voltage meet the respective preset conditions, it indicates that the electrostatic discharge protection structure is a good product, and then the subsequent HAST test can be performed, i.e., the electrostatic discharge protection structure is heated at a preset temperature and a preset voltage for a preset time, wherein the HAST test can be considered as an accelerated aging test. After the aging test, the test in the Post Test stage is performed, i.e., the target leakage current of the heated electrostatic discharge protection structure at the fixed initial voltage and the target breakdown voltage at the fixed initial current are determined.

[0099] Optionally, the preset condition corresponding to the initial leakage current and the preset condition corresponding to the initial breakdown voltage can be set according to actual business requirements, and no specific limitation is made thereto. For example, a leakage current threshold and a breakdown voltage threshold for the PreTest stage can be set in advance. In the case where the difference between the initial leakage current and the leakage current threshold is less than a preset difference threshold, and the difference between the initial breakdown voltage and the breakdown voltage threshold is less than a preset difference threshold, it is determined that the initial leakage current and the initial breakdown voltage satisfy the respective corresponding preset conditions.

[0100] Optionally, the preset temperature, the preset voltage, and the preset time can be set according to actual business requirements, and no specific limitation is made thereto.

[0101] It should be noted that, if the initial leakage current does not satisfy the corresponding preset condition, and / or the initial breakdown voltage does not satisfy the respective corresponding preset condition, it indicates that the electrostatic discharge protection structure is not a good product, and then the subsequent aging test and the Post Test stage test are not performed.

[0102] S14. Current change analysis is performed on the initial leakage current and the target leakage current to obtain a current change result of the electrostatic discharge protection structure, and voltage change analysis is performed on the initial breakdown voltage and the target breakdown voltage to obtain a voltage change result of the electrostatic discharge protection structure.

[0103] Optionally, after obtaining the target leakage current and the target breakdown voltage, current change analysis can be performed based on the difference between the initial leakage current and the target leakage current to obtain the current change result of the electrostatic discharge protection structure, and voltage change analysis can be performed based on the difference between the initial breakdown voltage and the target breakdown voltage to obtain the voltage change result of the electrostatic discharge protection structure.

[0104] S15. According to the current change result and the voltage change result, a high-temperature reverse bias test result of the electrostatic discharge protection structure is generated.

[0105] Optionally, the reliability of the electrostatic discharge protection structure can be evaluated according to the current change result and the voltage change result to obtain the high-temperature reverse bias test result of the electrostatic discharge protection structure.

[0106] Therefore, the leakage current and the breakdown voltage are accurately detected from the three dimensions of voltage, temperature, and time. Based on the detected leakage current and breakdown voltage, the current change result and the voltage change result are determined, and the reliability of the electrostatic discharge protection structure is accurately evaluated based on the current change result and the voltage change result, so that the electrostatic discharge protection structure can meet the actual application requirements.

[0107] In an optional embodiment, in the step S11, the electrostatic discharge protection structure can be provided by:

[0108] An initial semiconductor structure is provided.

[0109] The initial semiconductor structure is cut based on a laser cutting method to obtain a cut structure.

[0110] The cut structure is packaged by a large-exposed-back heat sink and a high-thermal-conductivity silver paste based on a preset packaging method to obtain the electrostatic discharge protection structure. The size of the electrostatic discharge protection structure corresponds to the size allowed by the preset packaging method.

[0111] In actual application, the cut structure is packaged to obtain the electrostatic discharge protection structure to be tested before HTRB. In order to avoid the heat generated by the cutting and packaging from causing HTRB test failure, the embodiment of the present application can improve the cutting and packaging method.

[0112] On the one hand, the initial semiconductor structure can be cut by the laser cutting method. Since the width of the cutting by the laser cutting method is narrow and the stress is small, the stress damage can be reduced, and the delamination caused by physical impact can be avoided, so that the heat generated by the cutting and packaging can be avoided to cause HTRB test failure to a certain extent.

[0113] On the other hand, heat, plasma and the like will enter the semiconductor structure during the cutting process, and cracks, delamination and the like will also be generated. If the cutting size is large, the size of the reserved area around the cut structure will be larger. If the size of the reserved area around the cut structure is large, the heat, plasma and the like can be blocked to avoid entering the core area of the semiconductor structure. Therefore, the size of the electrostatic discharge protection structure obtained by cutting and packaging corresponds to the size allowed by the preset packaging method. Further, the size of the electrostatic discharge protection structure obtained by cutting and packaging can be the maximum size allowed by the preset packaging method. For example, if the preset packaging method is SOP8, the size of the electrostatic discharge protection structure after cutting and packaging can be 2800*1800um.

[0114] Thirdly, in the packaging process, the large-exposed-back heat sink and the high-thermal-conductivity silver paste can be used for packaging. Since the large-exposed-back heat sink is more conducive to heat conduction, if the heating temperature in the aging stage is high, the electrostatic discharge protection structure is easy to generate heat when powered on, and will be overheated when heated at 125℃-175℃, which will cause burning. The large-exposed-back heat sink can avoid this problem. In addition, the use of the high-thermal-conductivity silver paste can quickly transfer the heat. It should be noted that the type of the high-thermal-conductivity silver paste is not limited in the embodiment of the present application. For example, it can be 8068T high-thermal-conductivity silver paste.

[0115] In an optional embodiment, in the step S21, the determining the initial leakage current of the ESD protection structure at the initial voltage and the determining the initial breakdown voltage of the ESD protection structure at the initial current can comprise:

[0116] performing a preset number of breakdown voltage tests on the ESD protection structure under the same current condition to obtain a preset number of breakdown voltage test results;

[0117] determining the initial leakage current of the ESD protection structure at the initial voltage and the initial breakdown voltage of the ESD protection structure at the initial current in the case that the difference between the preset number of breakdown voltage test results is less than a preset difference threshold.

[0118] In this embodiment, in order to further improve the test accuracy of HTRB, thereby improving the reliability of performance evaluation of the ESD protection structure, and reducing the test cost and time, a preliminary screening process can be added after the package cutting and before the HTRB test, which can be used to preliminarily judge whether the ESD protection structure to be tested is a qualified sample, if yes, the subsequent HTRB test is performed, if not, the subsequent HTRB test is not performed.

[0119] Optionally, the preliminary screening process can comprise: performing a preset number of breakdown voltage tests on the ESD protection structure under the same current condition to obtain a preset number of breakdown voltage test results.

[0120] Then, it is judged whether the difference between the preset number of breakdown voltage test results is less than a preset difference threshold. For example, it can be judged whether the overlap degree of the preset number of breakdown voltage test results is good, if yes, it means that the difference is less than the preset difference threshold, if not, it means that the difference is greater than the preset difference threshold.

[0121] In the case that the difference between the preset number of breakdown voltage test results is less than the preset difference threshold, it means that the ESD protection structure is a qualified sample, then the subsequent HTRB test can be performed, otherwise, the subsequent HTRB test is not performed.

[0122] For example, the breakdown voltage test is measured 3 times continuously on the ESD protection structure under the same current condition to obtain 3 breakdown voltage test results, if the overlap degree of the 3 breakdown voltage test results is good, the subsequent HTRB test is performed, otherwise, the subsequent HTRB test is not performed.

[0123] In an optional embodiment, the method can further comprise:

[0124] In a case where the difference between the preset number of breakdown voltage test results is greater than or equal to a preset difference threshold, the size of the electrostatic discharge protection structure is adjusted to obtain an adjusted electrostatic discharge protection structure.

[0125] In a case where the difference between the preset number of adjusted breakdown voltage test results is less than the preset difference threshold, an initial leakage current of the electrostatic discharge protection structure is determined at an initial voltage, and an initial breakdown voltage of the electrostatic discharge protection structure is determined at an initial current.

[0126] In a case where the difference between the preset number of breakdown voltage test results is greater than or equal to a preset difference threshold, the size of the electrostatic discharge protection structure is adjusted to obtain an adjusted electrostatic discharge protection structure.

[0127] Optionally, if the difference between the preset number of breakdown voltage test results is greater than or equal to a preset difference threshold, indicating that the electrostatic discharge protection structure is not a qualified sample, the electrostatic discharge protection structure can be adjusted to obtain an adjusted electrostatic discharge protection structure. And continue to perform the preset number of breakdown voltage tests on the adjusted electrostatic discharge protection structure under the same current condition to obtain the preset number of adjusted breakdown voltage test results

[0128] Then, it is judged whether the difference between the preset number of adjusted breakdown voltage test results is less than the preset difference threshold. Exemplarily, it can be judged whether the overlap degree of the preset number of adjusted breakdown voltage test results is good. If the overlap degree of the preset number of adjusted breakdown voltage test results is good, it indicates that the difference is less than the preset difference threshold, otherwise, it indicates that the difference is greater than the preset difference threshold.

[0129] In a case where the difference between the preset number of adjusted breakdown voltage test results is less than the preset difference threshold, indicating that the adjusted electrostatic discharge protection structure is a qualified sample, subsequent HTRB test can be performed, otherwise, subsequent HTRB test is not performed.

[0130] Therefore, after determining that the electrostatic discharge protection structure is an unqualified sample, the structure of the unqualified sample can be adjusted, and it is further judged whether the adjusted electrostatic discharge protection structure is a qualified sample by whether the difference between the preset number of breakdown voltage test results is greater than or equal to the preset difference threshold. If yes, HTRB test is performed, so that the electrostatic discharge protection structure can be fully utilized and the test cost can be saved.

[0131] In an optional embodiment, the PNP structure described above includes a P well, an N well, a P +The injection region, and the deep P-well located at the bottom of the P-well; the above-mentioned adjustment of the dimensions of the electrostatic discharge protection structure includes:

[0132] Adjust the lateral dimension of the deep P-well to be smaller than the lateral dimension of the P-well located at the top of the deep P-well, and / or increase the inner wall of the N-well and the P-well located within the N-well. + The lateral distance between the outer walls of the injection zone.

[0133] Figure 3 This is a schematic diagram of a PNP structure according to an exemplary embodiment, such as... Figure 3 As shown, the structure includes a P-well (PW), an N-well (NW), a P+ injection region (P+) located within the N-well, and a deep P-well (PWHT) located at the bottom of the P-well. That is, the BJT composition of the SABESD PNP is: P+ / PW / PWHT / NW / P+. When the trigger level (Vtrig) is low, if the lateral dimension (h1) of the PWHT is the same as the lateral dimension (h2) of the PW located on top of the PWHT, junction breakdown will first occur at the PWHT / NW, creating a resistive region and slowing down the conduction speed. Based on this, the lateral dimension (h1) of the PWHT can be designed to be smaller than the lateral dimension (h2) of the PW located on top of the PWHT, ensuring that the WN / WP junction is depleted first.

[0134] In addition, continue as Figure 3 As shown, in order to avoid the degradation of the SAB structure caused by insufficient effective base region window, which in turn leads to PNP leakage problem, the window size of the effective base region (NW cladding) can be increased, that is, the lateral distance between the inner wall of the N well and the outer wall of the P+ injection region located in the N well can be increased.

[0135] In an optional embodiment, the aforementioned increase in the inner wall of the N-well and the P located within the N-well + The lateral distance between the outer walls of the injection zone can include:

[0136] Decrease the lateral dimension of the P+ injection region located within the N-well, and / or increase the lateral dimension of the N-well, and / or decrease the lateral dimension of the P-well located on top of the PWHT.

[0137] In this embodiment, the effective base region refers to the inner wall of the N-well and the P-well. + The lateral distance between the outer walls of the injection region, in order to increase the window size of the effective base region, can be reduced on the one hand by decreasing the P located in the N-well. +The size of the P+ implant region in the lateral direction, and / or, the size of the N-well in the lateral direction, and / or, the size of the P-well on top of the PWHT in the lateral direction, can be adjusted. For example, the size of the P+ implant region in the lateral direction can be reduced by 0.06um, and / or, the size of the N-well in the lateral direction can be increased by 0.03um, and / or, the size of the P-well on top of the PWHT in the lateral direction can be reduced by 0.08um. + The size of the P+ implant region in the lateral direction is reduced by 0.06um, and / or, the size of the N-well in the lateral direction is increased by 0.03um, to modify the size of the N-well in the lateral direction to 2.06um, and / or, the size of the P-well on top of the PWHT in the lateral direction is reduced by 0.08um.

[0138] Thus, by reducing the size of the P+ implant region in the lateral direction, and / or, increasing the size of the N-well in the lateral direction, and / or, reducing the size of the P-well in the lateral direction, the window size of the active base region can be effectively increased, and the degradation of the SAB structure caused by insufficient window size of the active base region can be avoided, thereby improving the accuracy of the evaluation of the ESD structure. + The size of the P+ implant region in the lateral direction, and / or, the size of the N-well in the lateral direction, and / or, the size of the P-well on top of the PWHT in the lateral direction, can be adjusted. For example, the size of the P+ implant region in the lateral direction can be reduced by 0.06um, and / or, the size of the N-well in the lateral direction can be increased by 0.03um, and / or, the size of the P-well on top of the PWHT in the lateral direction can be reduced by 0.08um.

[0139] Figure 4 is a schematic diagram of the test results of three breakdown voltage tests on different types of SAB ESD PNP Figure 1 . Figure 5 is a schematic diagram of the test results of three breakdown voltage tests on different types of SAB ESD PNP Figure 2 . Figure 6 is a schematic diagram of the test results of three breakdown voltage tests on different types of SAB ESD PNP Figure 3 . Figure 7 is a schematic diagram of the test results of three breakdown voltage tests on different types of SAB ESD PNP Figure 4 . Among them, Figure 5 The adjustment in loop 1 means that the size of the P+ implant region in the N-well in the lateral direction is reduced by 0.06um. Figure 6 The adjustment in loop 2 means that the size of the P+ implant region in the N-well in the lateral direction is reduced by 0.06um, and the size of the N-well in the lateral direction is increased by 0.03um. Figure 7 The adjustment in loop 3 means that the size of the P+ implant region in the N-well in the lateral direction is reduced by 0.06um, the size of the N-well in the lateral direction is increased by 0.03um, and the size of the P-well on top of the PWHT in the lateral direction is reduced by 0.08um. Figure 5 to Figure 7 Loop 1, loop 2 and loop 3 in the table mean three different breakdown voltage test curves.

[0140] As shown in Figure 4As shown, without adjustment, the overlap of loop 1, loop 2 and loop 3 of 28V ESD PNP and 40V ESD PN is better than that of other types of ESD PNP. This is because the NW wrapping of 28V ESD PNP and 40V ESD PN is 0.55um, while the NW wrapping of other types is 0.35um.

[0141] Based on this, the structure of the SAB ESD PNP was adjusted. First, the lateral dimension of the P+ injection region was reduced by 0.06µm. Then, the adjusted SAB ESD PNP underwent three breakdown voltage tests to obtain... Figure 5 The test results diagram shown is as follows: Figure 5 As shown, after reducing the lateral size of the P+ injection region located within the N-well, the overlap of the loop1, loop2, and loop3 curves is greater than that of the loop3 curves. Figure 4 The better overlap in the loops indicates that reducing the lateral size of the P+ injection region within the N-well can improve the stability of the SAB ESD PNP structure. Furthermore, while the overlap of loops 1, 2, and 3 in the 28V ESD PNP and 40V ESD PN is good, it is still worse than the overlap of other types of ESD PNPs. This is because the NW wrapping of the 28V ESD PNP and 40V ESD PN is 0.55µm, while the NW wrapping of other types is 0.35µm.

[0142] Figure 6 The lateral dimension of the P+ injection region within the N-well is reduced by 0.06 μm, while the lateral dimension of the N-well is increased by 0.03 μm. Then, three breakdown voltage tests are performed on the adjusted SAB ESD PNP. The resulting schematic diagram is shown below. Figure 6 As shown, after reducing the lateral dimension of the P+ injection region within the N-well by 0.06 μm and increasing the lateral dimension of the N-well by 0.03 μm, the overlap of the loop1, loop2, and loop3 curves is greater than that of the loop3 curves. Figure 5 The better overlap in the loops indicates that reducing the lateral dimension of the P+ injection region within the N-well and increasing the lateral dimension of the N-well can further improve the stability of the SABESD PNP structure. Furthermore, while the overlap of loops 1, 2, and 3 in the 28V ESD PNP and 40V ESD PN is good, it is still worse than the overlap of other types of ESD PNPs. This is because the NW wrapping of the 28V ESD PNP and 40V ESD PN is 0.55µm, while the NW wrapping of other types is 0.35µm.

[0143] Figure 7 The lateral dimension of the P+ injection region within the N-well is reduced by 0.06 μm, the lateral dimension of the N-well is increased by 0.03 μm, and the lateral dimension of the P-well at the top of the PWHT is reduced by 0.08 μm. Then, three breakdown voltage tests are performed on the adjusted SABESD PNP. The resulting test results are illustrated in the diagram below. Figure 7 As shown, the lateral dimension of the well at the top of the PWHT was reduced by 0.08µm. After three breakdown voltage tests on the adjusted SAB ESD PNP, the overlap of the loop1, loop2, and loop3 curves was greater than that of the PWHT PNP ... Figure 6 The better overlap in the loops indicates that reducing the lateral dimension of the P+ injection region within the N-well and increasing the lateral dimension of the N-well can further improve the stability of the SAB ESD PNP structure. Furthermore, while the overlap of loops 1, 2, and 3 in the 28V ESD PNP and 40V ESD PN is good, it is still worse than the overlap of other types of ESD PNPs. This is because the NW wrapping of the 28V ESD PNP and 40V ESD PN is 0.55µm, while the NW wrapping of other types is 0.35µm.

[0144] It should be noted that the process of determining the initial leakage current and initial breakdown voltage in step S12 above can be achieved in a variety of ways, and no specific limitation is made.

[0145] In an optional embodiment, the PNP structure includes a base (b), a collector (c), and an emitter (e), and the initial voltage includes the voltage (V) between the emitter and the base. eb ), collector voltage (V c In step S12 above, determining the initial leakage current of the electrostatic discharge protection structure under the initial voltage and the initial breakdown voltage of the electrostatic discharge protection structure under the initial current may include:

[0146] Determine the initial leakage current of the electrostatic discharge protection structure under the conditions of room temperature, a collector voltage of 0V, and a voltage between the emitter and base of 1.1 to 1.4 times the operating voltage.

[0147] In this embodiment, the initial voltage can be set to include V. c and V eb and set V c 0V, V eb It operates at 1.1 to 1.4 times the operating voltage (Vop). And at room temperature, V c 0V, V ebFor the case of 1.1 times working voltage (Vop) to 1.4 times working voltage (Vop), the initial leakage current of the electrostatic discharge protection structure is detected.

[0148] Optionally, the room temperature can be in the range of 20-25°C.

[0149] In other embodiments, the difference between the collector voltage and 0V can be less than a preset difference threshold, for example, 0.01V, 0.02V, etc.

[0150] In other embodiments, the voltage between the emitter and the base can be gradually added from 0V to 1.1 times working voltage (Vop) to 1.4 times working voltage at room temperature and 0V collector voltage, and then the initial leakage current is measured.

[0151] Thus, the initial leakage current can be accurately detected from the two dimensions of voltage and temperature. Since the PNP structure includes the base, the collector and the emitter, the initial leakage current of the electrostatic discharge protection structure can be accurately and quickly measured at a fixed collector voltage and voltage between the emitter and the base.

[0152] In an optional embodiment, in the step S12, determining the initial breakdown voltage of the electrostatic discharge protection structure at the initial current includes:

[0153] At room temperature and 1E -7 A to 1E -10 A initial current, the initial breakdown voltage of the electrostatic discharge protection structure is determined.

[0154] In this embodiment, the initial current can be set to 1E -7 A to 1E -10 A, and the initial breakdown voltage of the electrostatic discharge protection structure is detected at room temperature.

[0155] Optionally, the room temperature can be in the range of 20-25°C.

[0156] In other embodiments, the voltage between the emitter and the base can be gradually added at room temperature, and the leakage current is measured at each step. When the leakage current reaches 1E -7 A to 1E -10 A, the breakdown voltage at this time is recorded to obtain the initial breakdown voltage. Assuming that when the breakdown voltage is added to 30V, it is found that the leakage current reaches 1E -8 A, then 30V is the initial breakdown voltage.

[0157] Therefore, the initial breakdown voltage can be quickly and accurately detected from two dimensions of voltage and temperature under the condition of fixing an initial current.

[0158] Figure 8 A flowchart of a high-temperature reverse bias test method of an electrostatic discharge protection structure according to an exemplary embodiment Figure 2 As shown in Figure 8 In an optional embodiment, the PNP structure includes a base, a collector and an emitter, the initial voltage includes a voltage between the emitter and the base and a collector voltage, and in step S13, under the condition that the initial leakage current and the initial breakdown voltage meet respective preset conditions, the electrostatic discharge protection structure is heated at a preset temperature and a preset voltage for a preset time, and a target leakage current of the heated electrostatic discharge protection structure at the initial voltage and a target breakdown voltage of the heated electrostatic discharge protection structure at the initial current are determined.

[0159] S131. In the case that the preset temperature is 125℃-175℃ and the voltage between the emitter and the base is 1.1 times the working voltage-1.4 times the working voltage, the electrostatic discharge protection structure is heated for a preset time.

[0160] S133. A target leakage current of the electrostatic discharge protection structure heated for the preset time at room temperature, the collector voltage being 0V and the voltage between the emitter and the base being 1.1 times the working voltage-1.4 times the working voltage is determined, and a target breakdown voltage of the heated electrostatic discharge protection structure at room temperature and the initial current being 1E-12A-1E-9A is determined. -7 A~1E -10 A.

[0161] Optionally, step S131 can be considered as an accelerated aging test. In the accelerated aging test, the voltage between the emitter and the base of the electrostatic discharge protection structure to be tested can be set to 1.1 times the working voltage-1.4 times the working voltage, and the electrostatic discharge protection structure is placed in a test device with a temperature of 125℃-175℃ and heated for a preset time. It should be noted that the preset time can be set according to actual needs, and no specific limitation is made thereto, for example, the preset time can be 500h, 1000h, etc.

[0162] Optionally, the step S133 can be considered as a Post Test stage. It should be noted that after the accelerated aging test, the electrostatic discharge protection structure can be removed from the test device and subjected to cooling and pressure reduction treatment, and then the test in the Post Test stage is performed. In the Post Test stage, the target leakage current of the heated electrostatic discharge protection structure under the fixed initial voltage and the target breakdown voltage of the heated electrostatic discharge protection structure under the fixed initial current can be determined. Further, the initial voltage includes the voltage between the emitter and the base and the collector voltage, and then the target leakage current can be tested under the condition that the room temperature, the collector voltage is 0V, and the voltage between the emitter and the base is 1.1 times the working voltage to 1.4 times the working voltage, and the target breakdown voltage can be tested under the condition that the room temperature, the initial current is 1E-6A to 1E-5A, and the initial voltage is 0V. -7 A~1E -10 A.

[0163] Optionally, the temperature range of the room temperature can be 20℃ to 25℃.

[0164] Since 1.1 times the working voltage to 1.4 times the working voltage is the voltage that can be used in actual application, and the aging temperature of 125℃ to 175℃ is the temperature that can be used in actual application, the aging test of heating the electrostatic discharge protection structure for a preset time under the condition that the preset temperature is 125℃ to 175℃ and the voltage between the emitter and the base is 1.1 times the working voltage to 1.4 times the working voltage makes the electrostatic discharge protection structure meet the actual application requirements; in addition, since the PNP structure includes the base, the collector and the emitter, the target leakage current and the target breakdown voltage of the electrostatic discharge protection structure can be accurately and quickly measured under the condition that the fixed collector voltage is 0V and the voltage between the emitter and the base is 1.1 times the working voltage to 1.4 times the working voltage, so as to accurately detect the leakage current and the breakdown voltage from the three dimensions of voltage, temperature and time, and to accurately evaluate the reliability of the electrostatic discharge protection structure, thereby making the electrostatic discharge protection structure meet the actual application requirements.

[0165] In another optional embodiment, the PNP structure includes the base, the collector and the emitter, and the initial voltage includes the voltage between the emitter and the base and the collector voltage, and then in the step S13, the heating of the electrostatic discharge protection structure for a preset time under the preset temperature and the preset voltage and the determination of the target leakage current of the heated electrostatic discharge protection structure under the initial voltage and the target breakdown voltage under the initial current under the condition that the initial leakage current and the initial breakdown voltage meet the respective preset conditions can include:

[0166] In the case that the preset temperature is 125℃-175℃, the voltage between the emitter and the base is 1.1 times working voltage-1.4 times working voltage, the first time is heated to the electrostatic discharge protection structure, and the first electrostatic discharge protection structure is obtained.

[0167] The first candidate leakage current of the first electrostatic discharge protection structure under the condition that the room temperature is 0V, the voltage between the emitter and the base is 1.1 times working voltage-1.4 times working voltage, and the initial current is 1E -7 A-1E -10 The first candidate breakdown voltage under A.

[0168] In the case that the current change result determined based on the first candidate leakage current and the voltage change result determined based on the first candidate breakdown voltage are not abnormal, the second time is continued to heat the first electrostatic discharge protection structure under the condition that the preset temperature is 125℃-175℃, the voltage between the emitter and the base is 1.1 times working voltage-1.4 times working voltage, and the second electrostatic discharge protection structure is obtained.

[0169] The second candidate leakage current of the second electrostatic discharge protection structure under the condition that the room temperature is 0V, the voltage between the emitter and the base is 1.1 times working voltage-1.4 times working voltage, and the initial current is 1E -7 A-1E -10 The second candidate breakdown voltage under A.

[0170] In the case that the current change result determined based on the second candidate leakage current and the voltage change result determined based on the second candidate breakdown voltage are not abnormal, the third time is continued to heat the second electrostatic discharge protection structure under the condition that the preset temperature is 125℃-175℃, the voltage between the emitter and the base is 1.1 times working voltage-1.4 times working voltage, and the third electrostatic discharge protection structure is obtained.

[0171] The third candidate leakage current of the third electrostatic discharge protection structure under the condition that the room temperature is 0V, the voltage between the emitter and the base is 1.1 times working voltage-1.4 times working voltage, and the initial current is 1E -7 A-1E -10 The third candidate breakdown voltage under A.

[0172] The third candidate leakage current is determined as the target leakage current, and the third candidate breakdown voltage is determined as the target breakdown voltage.

[0173] wherein the sum of the first time, the second time, and the third time is equal to the preset time.

[0174] In this embodiment, a preset number of time points can be taken within the time period corresponding to the preset time, for example, a first time point, a second time point, and a third time point are taken within the time period corresponding to the preset time.

[0175] In the accelerated aging test, the voltage between the emitter and the base of the electrostatic discharge protection structure to be tested can be set to 1.1 times the working voltage to 1.4 times the working voltage, the electrostatic discharge protection structure is placed in a test device with a temperature of 125°C to 175°C, and heated for a first time to perform the aging test to obtain a first electrostatic discharge protection structure. It should be noted that the first time can be set according to actual needs, and no specific limitation is made thereto, for example, the first time can be 168h.

[0176] It should be noted that after the accelerated aging test of 168h, the electrostatic discharge protection structure can be taken out of the test device and subjected to cooling and pressure reduction treatment, and then subjected to Post Test stage testing. In the Post Test stage, the leakage current can be tested to obtain a first candidate leakage current under the condition that the room temperature, the collector voltage is 0V, and the voltage between the emitter and the base is 1.1 times the working voltage to 1.4 times the working voltage, and the breakdown voltage can be tested to obtain a first candidate breakdown voltage under the condition that the room temperature, the initial current is 1E -7 A to 1E -10 A.

[0177] Then, current change analysis is performed based on the first candidate leakage current and the initial leakage current to obtain a current change result. Illustratively, the difference between the first candidate leakage current and the initial leakage current can be calculated, and the current change analysis is performed on the difference and the initial leakage current to obtain the current change result. Specifically, the ratio between the difference and the initial leakage current can be calculated to obtain the current change result. At the same time, voltage change analysis is performed based on the first candidate breakdown voltage and the initial breakdown voltage to obtain the voltage change result of the electrostatic discharge protection structure. Illustratively, the difference between the first candidate breakdown voltage and the initial breakdown voltage can be calculated, and the voltage change analysis is performed on the difference and the initial breakdown voltage to obtain the voltage change result. Specifically, the ratio between the difference and the initial breakdown voltage can be calculated to obtain the voltage change result.

[0178] Then, it is determined whether the current change result and the voltage change result are abnormal, and in the case of non-abnormality, subsequent tests are performed. Alternatively, the current change result can be compared with a current change threshold value, and the voltage change result can be compared with a voltage change threshold value, and in the case that the current change result is less than or equal to the current change threshold value and the voltage change result is less than or equal to the voltage change threshold value, it is determined that the current change result determined based on the first candidate leakage current and the voltage change result determined based on the first candidate breakdown voltage are non-abnormal, and then subsequent tests are performed. In the case that the current change result is greater than the current change threshold value and / or the voltage change threshold value is greater than the voltage change threshold value, it is determined that the current change result determined based on the first candidate leakage current and the voltage change result determined based on the first candidate breakdown voltage are abnormal, and then subsequent tests are not performed. In this way, in the case that the aging test result at the first time is non-abnormal, subsequent tests are performed, and the accuracy and reliability of evaluating the performance of the electrostatic discharge protection structure are improved.

[0179] Then, the voltage between the emitter and the base of the electrostatic discharge protection structure to be tested can be set to 1.1 times the working voltage to 1.4 times the working voltage, the first electrostatic discharge protection structure is placed in a test device with a temperature of 125°C to 175°C, and the aging test is continued for a second time to obtain a second electrostatic discharge protection structure. It should be noted that the second time can be set according to actual needs, and is not specifically limited, for example, the second time can be 332h, and the sum of the first time and the second time is 500h.

[0180] It should be noted that after the accelerated aging test of 332h is continued, the second electrostatic discharge protection structure can be taken out of the test device and subjected to cooling and pressure reduction, and then the test in the Post Test stage is performed. In the Post Test stage, the leakage current can be tested to obtain a second candidate leakage current under the condition that the room temperature, the voltage between the collector and the base is 0V, and the voltage between the emitter and the base is 1.1 times the working voltage to 1.4 times the working voltage, and the breakdown voltage can be tested to obtain a second candidate breakdown voltage under the condition that the room temperature, the initial current is 1E -7 A to 1E -10 A.

[0181] Then, the current change result is obtained by performing current change analysis on the second candidate leakage current and the initial leakage current. For example, the difference between the second candidate leakage current and the initial leakage current can be calculated, and the current change analysis is performed on the difference and the initial leakage current to obtain the current change result. Specifically, the ratio between the difference and the initial leakage current can be calculated to obtain the current change result. Meanwhile, the voltage change result of the electrostatic discharge protection structure is obtained by performing voltage change analysis on the second candidate breakdown voltage and the initial breakdown voltage. For example, the difference between the second candidate breakdown voltage and the initial breakdown voltage can be calculated, and the voltage change analysis is performed on the difference and the initial breakdown voltage to obtain the voltage change result. Specifically, the ratio between the difference and the initial breakdown voltage can be calculated to obtain the voltage change result.

[0182] Then, it is determined whether the current change result and the voltage change result are abnormal. If not, subsequent tests are performed. Alternatively, the current change result can be compared with a current change threshold, and the voltage change result can be compared with a voltage change threshold. If the current change result is less than or equal to the current change threshold, and the voltage change result is less than or equal to the voltage change threshold, it is determined that the current change result determined based on the second candidate leakage current and the voltage change result determined based on the second candidate breakdown voltage are not abnormal, and then subsequent tests are performed. If the current change result is greater than the current change threshold, and / or the voltage change threshold is greater than the voltage change threshold, it is determined that the current change result determined based on the second candidate leakage current and the voltage change result determined based on the second candidate breakdown voltage are abnormal, and then subsequent tests are not performed. In this way, subsequent tests are only performed when the aging test result at the second time is not abnormal, thereby improving the accuracy and reliability of evaluating the performance of the electrostatic discharge protection structure.

[0183] Then, the voltage between the emitter and the base of the second electrostatic discharge protection structure is set to 1.1 times the working voltage to 1.4 times the working voltage, and the second electrostatic discharge protection structure is placed in a test device with a temperature of 125°C to 175°C, and continues to be heated for a third time to perform an aging test, to obtain a third electrostatic discharge protection structure. It should be noted that the third time can be set according to actual needs, and is not specifically limited, for example, the third time can be 500h, and the sum of the first time, the second time and the third time is 1000h.

[0184] It should be noted that after the third time accelerated aging test is continued, the third electrostatic discharge protection structure can be taken out from the test device and be cooled and depressurized, and then the test in the Post Test stage is performed. In the Post Test stage, the leakage current is tested to obtain a third candidate leakage current under the condition that the room temperature is, the collector voltage is 0V, and the voltage between the emitter and the base is 1.1 times the working voltage to 1.4 times the working voltage, and the breakdown voltage is tested to obtain a third candidate breakdown voltage under the condition that the room temperature is, the initial current is 1E -7 A, and the target current is 1E -10 A. The third candidate leakage current is determined as the target leakage current, and the third candidate breakdown voltage is determined as the target breakdown voltage.

[0185] Therefore, the preset time of the aging stage can be divided into multiple time periods, the aging test and the test in the Post Test stage are performed for each time period, and the test in the next stage is performed only when the current change result in each stage and the voltage change result based on the first candidate breakdown voltage are not abnormal, and the test in the next stage is not performed when the current change result in each stage and the voltage change result based on the first candidate breakdown voltage are abnormal. Not only the time for evaluating the performance of the electrostatic discharge protection structure is saved, but also the accuracy and reliability of the evaluation of the performance of the electrostatic discharge protection structure are improved.

[0186] In an optional embodiment, in the step S14, the current change analysis on the initial leakage current and the target leakage current to obtain the current change result of the electrostatic discharge protection structure can include:

[0187] determining a current difference between the initial leakage current and the target leakage current.

[0188] performing current change analysis on the current difference and the initial leakage current to obtain the current change result.

[0189] In this embodiment, after the target leakage current is obtained, a current difference between the initial leakage current and the target leakage current can be calculated, and the current difference can represent the current change in the Pre Test stage and the Post Test stage.

[0190] Then, current change analysis is performed on the current difference and the initial leakage current obtained in the Pre Test stage to obtain the current change result. For example, the ratio of the absolute value of the current difference to the initial leakage current is calculated, and the ratio is determined as the current change result. For example, the initial leakage current is 3E -8 A, the target leakage current is 3.7E -8 A, and the current difference is 3.7E-8 A-3E -8 A = 0.7E -8 A, current change result = 0.7E -8 A / 3E -8 A = 23.3%.

[0191] In other embodiments, the ratio between the target leakage current and the initial leakage current can also be directly calculated to obtain the current change result. For example, the initial leakage current is 3E -8 A, the target leakage current is 3.7E -8 A, the current change result = 3.7E -8 A / 3E -8 A = 1.23, i.e., the current changes by 1.23 times after the Post Test phase.

[0192] Since the current difference can represent the current change situation of the Pre Test phase and the Post Test phase, the current change analysis according to the current change situation and the initial leakage current can accurately and efficiently calculate the current change result, thereby improving the accuracy and efficiency of evaluating the performance of the electrostatic discharge protection structure.

[0193] In an optional embodiment, in the step S14, the voltage change analysis on the initial breakdown voltage and the target breakdown voltage to obtain the voltage change result of the electrostatic discharge protection structure includes:

[0194] determining a voltage difference between the initial breakdown voltage and the target breakdown voltage;

[0195] performing voltage change analysis on the voltage difference and the initial breakdown voltage to obtain the voltage change result.

[0196] In this embodiment, after obtaining the target breakdown voltage, the voltage difference between the initial breakdown voltage and the target breakdown voltage can be calculated, and the voltage difference can represent the voltage change situation of the Pre Test phase and the Post Test phase.

[0197] Then, voltage change analysis is performed on the voltage difference and the initial breakdown voltage obtained in the Pre Test phase to obtain the voltage change result. For example, the ratio of the absolute value of the voltage difference to the initial breakdown voltage can be calculated, and the ratio is determined as the voltage change result. For example, the initial breakdown voltage is 42.4V, the target breakdown voltage is 42.6V, the voltage difference is 42.6V-42.4V = 0.2A, and the voltage change result = 0.2V / 42.4V = 0.47%.

[0198] In other embodiments, the ratio between the target breakdown voltage and the initial breakdown voltage can also be directly calculated to obtain the voltage change result. For example, if the initial breakdown voltage is 42.4V and the target breakdown voltage is 42.6V, then the voltage change result = 42.6V / 42.4V = 1, i.e., the voltage has changed by 1 times after the Post Test phase.

[0199] Since the voltage difference value can represent the voltage change situation in the Pre Test phase and the Post Test phase, and the current change analysis is performed according to the voltage change situation and the initial breakdown voltage, the voltage change result can be accurately and efficiently calculated, thereby improving the accuracy and efficiency of evaluating the performance of the electrostatic discharge protection structure.

[0200] In an optional embodiment, in the step S14, the generating the high-temperature reverse bias test result of the electrostatic discharge protection structure according to the current change result and the voltage change result can include:

[0201] providing a current change threshold and a voltage change threshold.

[0202] In a case where the current change result is less than or equal to the current change threshold, and the voltage change result is less than or equal to the voltage change threshold, determining that the high-temperature reverse bias test result of the electrostatic discharge protection structure is a test qualified result.

[0203] In a case where the current change result is greater than the current change threshold, and / or the voltage change result is greater than the voltage change threshold, determining that the high-temperature reverse bias test result of the electrostatic discharge protection structure is a test unqualified result.

[0204] Optionally, a current change threshold and a voltage change threshold can be provided in advance, and an evaluation standard for the SAB ESD PNP structure can be formulated according to the current change threshold and the voltage change threshold. The current change threshold and the voltage change threshold can be set according to actual needs, and are not specifically limited. For example, the current change threshold can be 100x (100 times), the voltage change threshold can be 10%, and the evaluation standard can be: in a case where the current change result is less than or equal to the current change threshold, and the voltage change result is less than or equal to the voltage change threshold, determining that the high-temperature reverse bias test result of the electrostatic discharge protection structure is a test qualified result, and in a case where the current change result is greater than the current change threshold, and / or the voltage change result is greater than the voltage change threshold, determining that the high-temperature reverse bias test result of the electrostatic discharge protection structure is a test unqualified result.

[0205] Then, the current change result is compared with the current change threshold value, and the voltage change result is compared with the voltage change threshold value. If the current change result is less than or equal to the current change threshold value, and the voltage change result is less than or equal to the voltage change threshold value, it is considered that the high-temperature reverse bias test result of the electrostatic discharge protection structure meets the pre-established evaluation standard, that is, the high-temperature reverse bias test result of the electrostatic discharge protection structure is considered to be a test qualified result. If the current change result is greater than the current change threshold value, and / or the voltage change threshold value is greater than the voltage change threshold value, it is considered that the high-temperature reverse bias test result of the electrostatic discharge protection structure does not meet the pre-established evaluation standard, that is, the high-temperature reverse bias test result of the electrostatic discharge protection structure is considered to be a test unqualified result.

[0206] For example, the current change result is 20%, the voltage change result is 2%, the current change result is less than the current change threshold value, and the voltage change result is less than the voltage change result. The high-temperature reverse bias test result of the electrostatic discharge protection structure is a test qualified result. For another example, the current change result is 1000 times, the voltage change result is greater than 90%, the current change result is greater than the current change threshold value, and the voltage change result is greater than the voltage change result. The high-temperature reverse bias test result of the electrostatic discharge protection structure is a test unqualified result.

[0207] Therefore, the current change threshold value and the voltage change threshold value can be provided in advance, and an evaluation standard can be established in advance based on the current change threshold value and the voltage change threshold value. The performance of the electrostatic discharge protection structure is evaluated according to the current change result, the voltage change result and the evaluation standard, and the evaluation accuracy and reliability of the SAB ESD PNP structure are improved.

[0208] Figure 9 is a voltage change result diagram of a different type of SAB ESD PNP according to an exemplary embodiment. As shown in a of Figure 9 , the voltage change result is greater than 90%, as shown in b of Figure 9 , the voltage change result is less than 2%, as shown in c of Figure 9 , the voltage change result is less than 1%. It can be seen that the high-temperature reverse bias test result of the 24V ESD is a test unqualified result. In the case that the current change result of the 28V ESD is less than 100x, the high-temperature reverse bias test result of the 28V ESD is a test qualified result. In the case that the current change result of the 32V ESD is less than 100x, the high-temperature reverse bias test result of the 32V ESD is a test qualified result.

[0209] In an optional embodiment, before the above-mentioned determining the target leakage current of the heated electrostatic discharge protection structure under the initial voltage and the target breakdown voltage under the initial current, the above-mentioned method can further comprise:

[0210] The heated electrostatic discharge protection structure is subjected to alternating voltage reduction and temperature reduction until the voltage of the heated electrostatic discharge protection structure is 0 V and the temperature is room temperature.

[0211] In actual application, if the leakage current and breakdown low voltage of the heated electrostatic discharge protection structure are directly read, the electrostatic discharge protection structure will be broken down. In order to prevent the electrostatic discharge protection structure from being broken down, the heated electrostatic discharge protection structure can be subjected to alternating voltage reduction and temperature reduction until the voltage of the heated electrostatic discharge protection structure is 0 V and the temperature is room temperature.

[0212] Suppose the preset temperature is 150℃ and the voltage between the emitter and the base is 1.1 times the working voltage. After the heated electrostatic discharge protection structure is taken out of the test device, it can be subjected to alternating temperature reduction and voltage reduction, for example, the voltage is reduced from 1.1 times the working voltage to 1 times the working voltage, and the temperature is reduced from 150℃ to 140℃. Then the voltage is reduced from 1 times the working voltage to 0.9 times the working voltage, and the temperature is reduced from 140℃ to 130℃. Then the voltage is reduced from 0.9 times the working voltage to 0.8 times the working voltage, and the temperature is reduced from 130℃ to 120℃. And so on, until the voltage between the emitter and the base is 0 V and the temperature is room temperature.

[0213] Correspondingly, the above-mentioned determination of the target leakage current of the heated electrostatic discharge protection structure at the initial voltage and the target breakdown voltage at the initial current can include:

[0214] Determination of the target leakage current of the electrostatic discharge protection structure at the initial voltage and the target breakdown voltage at the initial current when the voltage is 0 V and the temperature is room temperature.

[0215] In this embodiment, after the voltage of the heated electrostatic discharge protection structure is 0 V and the temperature is room temperature, the target leakage current can be tested at the initial voltage, and the target breakdown voltage can be tested at the initial current. This not only effectively avoids the breakdown of the electrostatic discharge protection structure, but also improves the reading accuracy of the target leakage current and the target breakdown voltage.

[0216] Next, the high-temperature reverse bias test method of the above-mentioned electrostatic discharge protection structure is described in its entirety.

[0217] I. Improve the packaging method to avoid the heat generated by cutting packaging from causing HTRB test failure:

[0218] Provide an initial semiconductor structure;

[0219] Cut the initial semiconductor structure based on a laser cutting method to obtain a cut structure;

[0220] The electrostatic discharge protection structure is obtained by packaging the cutting structure through a large back heat dissipation sheet and a heat-conductive silver glue based on a preset packaging mode, wherein the size of the electrostatic discharge protection structure corresponds to the size allowed by the preset packaging mode.

[0221] For example, the SOP8 is packaged by a preset packaging mode through a laser cutting method, and the packaging size is 2800*1800 um. In addition, a large back heat dissipation sheet and 8068T high-thermal-conductivity silver glue are used in the packaging process.

[0222] II. Design process improvement of the initial semiconductor structure

[0223] The electrostatic discharge protection structure is subjected to a preset number of breakdown voltage tests under the same current condition, and a preset number of breakdown voltage test results are obtained.

[0224] In a case where the difference between the preset number of breakdown voltage test results is less than a preset difference threshold, an initial leakage current of the electrostatic discharge protection structure is determined at an initial voltage, and an initial breakdown voltage of the electrostatic discharge protection structure is determined at an initial current. In a case where the difference between the preset number of breakdown voltage test results is greater than or equal to the preset difference threshold, the size of the electrostatic discharge protection structure is adjusted, and an adjusted electrostatic discharge protection structure is obtained.

[0225] The adjusted electrostatic discharge protection structure is subjected to a preset number of breakdown voltage tests under the same current condition, and a preset number of adjusted breakdown voltage test results are obtained.

[0226] In a case where the difference between the preset number of adjusted breakdown voltage test results is less than a preset difference threshold, an initial leakage current of the electrostatic discharge protection structure is determined at an initial voltage, and an initial breakdown voltage of the electrostatic discharge protection structure is determined at an initial current.

[0227] The adjustment of the size of the electrostatic discharge protection structure comprises:

[0228] The size of the deep P well in the lateral direction is adjusted to be less than the size of the P well arranged at the top of the deep P well in the lateral direction, and / or the distance between the inner wall of the N well and the outer wall of the P + implantation region in the lateral direction is increased.

[0229] The distance between the inner wall of the N well and the outer wall of the P + implantation region in the lateral direction is increased.

[0230] The distance between the inner wall of the N well and the outer wall of the P +The size of the implant region in the lateral direction, and / or, increasing the size of the N-well in the lateral direction, and / or, decreasing the size of the P-well disposed on top of the deep P-well in the lateral direction.

[0231] For example, the P-well located within the N-well is increased in size in the lateral direction by 0.06um, the N-well is increased in size in the lateral direction by 0.03um, the P-well disposed on top of the deep P-well is decreased in size in the lateral direction by 0.08um. + The size of the implant region in the lateral direction is decreased by 0.06um, the size of the N-well in the lateral direction is increased by 0.03um, the size of the P-well disposed on top of the deep P-well in the lateral direction is decreased by 0.08um.

[0232] III. HTRB Test

[0233] 1) Pre Test Phase:

[0234] The initial leakage current of the ESD protection structure is determined at room temperature, with the collector voltage at 0V, and the voltage between the emitter and the base at 1.1 times the working voltage to 1.4 times the working voltage; the initial breakdown voltage of the ESD protection structure is determined at room temperature, with the initial current at 1E-12A to 1E-10A. -7 A to 1E-10A. -10 A.

[0235] 2) Aging Test Phase

[0236] The ESD protection structure is heated at a preset temperature of 125℃ to 175℃, with the voltage between the emitter and the base at 1.1 times the working voltage to 1.4 times the working voltage, for a preset time.

[0237] 3) Post Test Phase

[0238] The target leakage current of the ESD protection structure after being heated for the preset time is determined at room temperature, with the collector voltage at 0V, and the voltage between the emitter and the base at 1.1 times the working voltage to 1.4 times the working voltage; the target breakdown voltage of the ESD protection structure after being heated is determined at room temperature, with the initial current at 1E-12A to 1E-10A. -7 A to 1E-10A. -10 A.

[0239] At the same time, a test standard is set: if the change result of the leakage current is >100x, and / or the change result of the breakdown voltage is >10%, the test is unqualified; if the change result of the leakage current is ≤100x, and / or the change result of the breakdown voltage is ≤10%, the test is qualified.

[0240] 4) performing current variation analysis on the initial leakage current and the target leakage current to obtain a current variation result of the electrostatic discharge protection structure, and performing voltage variation analysis on the initial breakdown voltage and the target breakdown voltage to obtain a voltage variation result of the electrostatic discharge protection structure; and generating a high-temperature reverse bias test result of the electrostatic discharge protection structure according to the current variation result and the voltage variation result.

[0241] The embodiment of the present application further provides an electrostatic discharge protection structure, which is subjected to the high-temperature reverse bias test method according to any one of the above-mentioned embodiments, and the electrostatic discharge protection structure comprises:

[0242] a P substrate; the P substrate comprises a buried N+ layer;

[0243] deep N wells located on two end surfaces of the buried N+ layer; an N well bottom is embedded in a top of the deep N well, and an N+ implantation region is located on a top surface of the N well;

[0244] a deep P well located inside between two deep N wells, and a bottom of the deep P well is higher than a surface of the buried N+ layer; a P well is arranged on a top of the deep P well, and a P+ implantation region is located on a top surface of the P well;

[0245] an N well located between two deep P wells; a P+ implantation region is located on a top surface of the N well, and a barrier layer is located on a top surface of a target P well and on a top surface of a portion between the two deep P wells containing the N well; the target P well is a P well arranged on the top of the deep P well;

[0246] a P well located outside the deep N well, and a P+ implantation region is arranged on a top surface of the P well located outside the deep N well.

[0247] Continuing as shown in Figure 3 , the P+ / PW / PWHT / NW / P+ forms a PNP structure, and the SAB is used to isolate devices in the PNP structure.

[0248] If a size (h1) of the PWHT in a lateral direction and a size (h2) of the PW in the lateral direction are the same, a position of junction breakdown occurs first in the PWHT / NW and generates a resistance zone, and a conduction speed is slowed down. Based on this, the size (h1) of the PW HT in the lateral direction can be designed to be smaller than the size (h2) of the PW arranged on the top of the deep P well, so as to ensure that the WN / WP junction is exhausted first.

[0249] In an optional embodiment, a distance between an inner wall of the N well and an outer wall of the P+ implantation region located in the N well in a lateral direction is greater than a preset distance threshold.

[0250] In this embodiment, as shown in Figure 3 To avoid the degradation of SAB structure caused by insufficient window size of effective base region, and the resulting PNP leakage problem, the window size of effective base region (NW package edge) can also be increased, i.e., the distance between the inner wall of N well and the outer wall of P+ implantation region located in N well in the lateral direction is increased, so that the window size of effective base region is greater than a preset distance threshold.

[0251] Optionally, the preset distance threshold can be set according to actual needs, for example, the preset distance threshold can be 0.5um.

[0252] In some embodiments, the embodiments of the present application also provide an electronic device, which includes a processor and a memory, the memory stores at least one instruction or at least one program, the at least one instruction or the at least one program is loaded and executed by the processor to implement the method for forming the semiconductor structure as described in the above embodiments.

[0253] In some embodiments, the embodiments of the present application also provide a computer readable storage medium, which stores at least one instruction or at least one program, the at least one instruction or the at least one program is loaded and executed by a processor to implement the method for forming the semiconductor structure as described in the above embodiments.

[0254] Other embodiments of the present application will be apparent to those skilled in the art from consideration of the specification and practice of the application disclosed herein. The application is intended to cover any variations, uses or adaptations of the application following, in general, the principles of the application and including such departures from the present disclosure as come within known or customary practice in the art to which the application pertains. The specification and examples are to be regarded as exemplary only, and the true scope and spirit of the application are indicated by the following claims.

[0255] It should be understood that the application is not limited to the precise construction that has been described above and shown in the accompanying drawings, and that various modifications and changes can be made by those skilled in the art without departing from the scope of the application. The scope of the application is limited only by the appended claims.

Claims

1. A high-temperature reverse-bias test method for an electrostatic discharge protection structure, characterized in that, The method includes: An electrostatic discharge protection structure is provided; the electrostatic discharge protection structure includes a PNP structure and a barrier layer, the barrier layer being used to isolate the PNP structure; The initial leakage current of the electrostatic discharge protection structure is determined under the initial voltage, and the initial breakdown voltage of the electrostatic discharge protection structure is determined under the initial current. When the initial leakage current and the initial breakdown voltage meet their respective preset conditions, the electrostatic discharge protection structure is heated for a preset time at a preset temperature and a preset voltage, and the target leakage current of the heated electrostatic discharge protection structure at the initial voltage and the target breakdown voltage at the initial current are determined. The current change analysis of the initial leakage current and the target leakage current is performed to obtain the current change result of the electrostatic discharge protection structure; the voltage change analysis of the initial breakdown voltage and the target breakdown voltage is performed to obtain the voltage change result of the electrostatic discharge protection structure. Based on the current change results and the voltage change results, the high-temperature reverse bias test results of the electrostatic discharge protection structure are generated.

2. The method according to claim 1, characterized in that, The PNP structure includes a base, a collector, and an emitter; the initial voltage includes the voltage between the emitter and the base, and the collector voltage; determining the initial leakage current of the electrostatic discharge protection structure under the initial voltage includes: Determine the initial leakage current of the electrostatic discharge protection structure under the conditions of room temperature, a collector voltage of 0V, and a voltage between the emitter and base of 1.1 to 1.4 times the operating voltage.

3. The method according to claim 1, characterized in that, Determining the initial breakdown voltage of the electrostatic discharge protection structure under the initial current includes: At room temperature, the initial current is 1E. -7 A~1E -10 Under case A, determine the initial breakdown voltage of the electrostatic discharge protection structure.

4. The method according to claim 1, characterized in that, The PNP structure includes a base, a collector, and an emitter. The initial voltage includes the voltage between the emitter and the base, and the collector voltage. Heating the electrostatic discharge protection structure at a preset temperature and preset voltage for a preset time, and determining the target leakage current of the heated electrostatic discharge protection structure at the initial voltage, and the target breakdown voltage at the initial current, includes: The electrostatic discharge protection structure is heated for a preset time at a preset temperature of 125℃~175℃ and a voltage between the emitter and base of 1.1 times to 1.4 times the working voltage. The target leakage current of the electrostatic discharge protection structure after a preset heating time is determined under the following conditions: room temperature, collector voltage of 0V, and voltage between emitter and base of 1.1 to 1.4 times the operating voltage. The target leakage current of the electrostatic discharge protection structure after heating is also determined under the following conditions: room temperature, initial current of 1E. -7 A~1E -10 Target breakdown voltage under condition A.

5. The method according to claim 1, characterized in that, The PNP structure includes a base, a collector, and an emitter. The initial voltage includes the voltage between the emitter and the base, and the collector voltage. Heating the electrostatic discharge protection structure at a preset temperature and preset voltage for a preset time, and determining the target leakage current of the heated electrostatic discharge protection structure at the initial voltage, and the target breakdown voltage at the initial current, includes: Under the conditions of a preset temperature of 125℃~175℃ and a voltage between the emitter and base of 1.1 times to 1.4 times the working voltage, the electrostatic discharge protection structure is heated for a first time to obtain a first electrostatic discharge protection structure. The first candidate leakage current of the first electrostatic discharge protection structure is determined under the following conditions: room temperature, collector voltage of 0V, and voltage between emitter and base of 1.1 to 1.4 times the operating voltage. The initial current of the first electrostatic discharge protection structure at room temperature is also determined. -7 A~1E -10 The first candidate breakdown voltage under A; If the current change result determined based on the first candidate leakage current and the voltage change result determined based on the first candidate breakdown voltage are not abnormal, under the preset temperature of 125℃~175℃ and the voltage between the emitter and the base of 1.1 times to 1.4 times the working voltage, the first electrostatic discharge protection structure is heated for a second time to obtain the second electrostatic discharge protection structure. The second candidate leakage current of the second electrostatic discharge protection structure was determined at room temperature, with the collector voltage at 0V and the voltage between the emitter and base at 1.1 to 1.4 times the operating voltage. The second electrostatic discharge protection structure was also determined at room temperature, with the initial current at 1E. -7 A~1E -10 The second candidate breakdown voltage under A; If the current change results determined based on the second candidate leakage current and the voltage change results determined based on the second candidate breakdown voltage are not abnormal, under the preset temperature of 125℃~175℃ and the voltage between the emitter and the base of 1.1 times to 1.4 times the working voltage, the second electrostatic discharge protection structure is heated for a third time to obtain the third electrostatic discharge protection structure. The third candidate leakage current of the third electrostatic discharge protection structure was determined at room temperature, with the collector voltage at 0V and the voltage between the emitter and base at 1.1 to 1.4 times the operating voltage. The third candidate leakage current of the third electrostatic discharge protection structure was also determined at room temperature and with an initial current of 1E. -7 A~1E -10 The third candidate breakdown voltage under A; The third candidate leakage current is determined as the target leakage current, and the third candidate breakdown voltage is determined as the target breakdown voltage; Wherein, the sum of the first time, the second time, and the third time is equal to the preset time.

6. The method according to claim 1, characterized in that, The current change analysis of the initial leakage current and the target leakage current to obtain the current change results of the electrostatic discharge protection structure includes: Determine the current difference between the initial leakage current and the target leakage current; The current change is analyzed by examining the current difference and the initial leakage current to obtain the current change result.

7. The method according to claim 1, characterized in that, The voltage change analysis of the initial breakdown voltage and the target breakdown voltage to obtain the voltage change results of the electrostatic discharge protection structure includes: Determine the voltage difference between the initial breakdown voltage and the target breakdown voltage; Voltage variation analysis is performed on the voltage difference and the initial breakdown voltage to obtain the voltage variation result.

8. The method according to claim 1, characterized in that, The step of generating high-temperature reverse-bias test results for the electrostatic discharge protection structure based on the current change results and the voltage change results includes: Provide current change threshold and voltage change threshold; If the current change result is less than or equal to the current change threshold and the voltage change result is less than or equal to the voltage change threshold, the high-temperature reverse bias test result of the electrostatic discharge protection structure is determined to be a qualified test result. If the current change result is greater than the current change threshold, and / or the voltage change threshold is greater than the voltage change threshold, the high-temperature reverse bias test result of the electrostatic discharge protection structure is determined to be a test failure result.

9. The method according to claim 1, characterized in that, Before determining the target leakage current of the heated electrostatic discharge protection structure at the initial voltage, and the target breakdown voltage at the initial current, the method further includes: The heated electrostatic discharge protection structure is subjected to alternating voltage and temperature reduction treatments until the voltage of the heated electrostatic discharge protection structure is 0V and the temperature is room temperature. The determination of the target leakage current of the heated electrostatic discharge protection structure under the initial voltage, and the target breakdown voltage under the initial current, includes: Determine the target leakage current of the electrostatic discharge protection structure at the initial voltage (0V) and room temperature, and the target breakdown voltage at the initial current.

10. The method according to claim 1, characterized in that, The electrostatic discharge protection structure includes: Provides the initial semiconductor structure; The initial semiconductor structure is cut using a laser cutting method to obtain a cut structure; Based on a preset encapsulation method, the cut structure is encapsulated with a large exposed back heat sink and thermally conductive silver paste to obtain the electrostatic discharge protection structure. The dimensions of the electrostatic discharge protection structure correspond to the dimensions allowed by the preset packaging method.

11. The method according to claim 1, characterized in that, The steps of determining the initial leakage current of the electrostatic discharge protection structure under an initial voltage and determining the initial breakdown voltage of the electrostatic discharge protection structure under an initial current include: Under the same current conditions, the electrostatic discharge protection structure is subjected to a preset number of breakdown voltage tests to obtain the preset number of breakdown voltage test results. If the difference between the results of the predetermined number of breakdown voltage tests is less than a predetermined difference threshold, the initial leakage current of the electrostatic discharge protection structure is determined at the initial voltage, and the initial breakdown voltage of the electrostatic discharge protection structure is determined at the initial current.

12. The method according to claim 11, characterized in that, The method further includes: If the difference between the results of the preset number of breakdown voltage tests is greater than or equal to a preset difference threshold, the size of the electrostatic discharge protection structure is adjusted to obtain the adjusted electrostatic discharge protection structure. Under the same current conditions, the adjusted electrostatic discharge protection structure is subjected to a preset number of breakdown voltage tests to obtain the preset number of adjusted breakdown voltage test results. If the difference between the breakdown voltage test results after the preset number of adjustments is less than a preset difference threshold, the initial leakage current of the electrostatic discharge protection structure is determined at the initial voltage, and the initial breakdown voltage of the electrostatic discharge protection structure is determined at the initial current.

13. The method according to claim 12, characterized in that, The PNP structure includes a P-well, an N-well, and a P-well located within the N-well. + Injection region, deep P-well located at the bottom of the P-well; The adjustment of the dimensions of the electrostatic discharge protection structure includes: Adjust the lateral dimension of the deep P-well to be smaller than the lateral dimension of the P-well, and / or increase the inner wall of the N-well relative to the P-well. + The lateral distance between the outer walls of the injection zone.

14. The method according to claim 13, characterized in that, The increase in the inner wall of the N-well and the P + The lateral distance between the outer walls of the injection zone includes: Decrease the P + The size of the injection region in the lateral direction, and / or, increasing the size of the N-well in the lateral direction, and / or, decreasing the size of the P-well in the lateral direction.

15. An electrostatic discharge protection structure, characterized in that, The electrostatic discharge protection structure is subjected to a high-temperature reverse bias test using the method described in any one of claims 1 to 14, and the electrostatic discharge protection structure comprises: P-type substrate; the p-type substrate includes a buried N+ layer; Deep N-wells are located on both ends of the buried N+ layer; the bottom of the N-well is embedded in the top of the deep N-well, and the N+ injection area is located on the top surface of the N-well; A deep P-well is located inside the two deep N-wells, and the bottom of the deep P-well is higher than the surface of the buried N+ layer; a P-well is provided on the top of the deep P-well, and the P+ injection area is located on the top surface of the P-well. An N-well is located between the two deep P-wells; a P+ injection region is located on the top surface of the N-well, and a barrier layer is located on the top surface of the target P-well and on the top surface of the portion containing the N-well between the two deep P-wells; the target P-well is a P-well that is positioned on top of the deep P-wells. The P-well located outside the deep N-well has a P+ injection region on its top surface.

16. The electrostatic discharge protection structure according to claim 15, characterized in that, The lateral dimension of the deep P-well is smaller than the lateral dimension of the P-well located on top of the deep P-well, and the lateral distance between the inner wall of the N-well and the outer wall of the P+ injection region located within the N-well is greater than a preset distance threshold.

17. An electronic device, characterized in that, The electronic device includes an electrostatic discharge protection structure as described in any one of claims 15 to 16.

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