Method for regulating breakover voltage of power device

Abstract

The invention provides a method for adjusting breakover voltage of a power device, and relates to the technical field of semiconductors. The method comprises the following steps: measuring the actual breakover voltage of the power device; and performing proton irradiation treatment and annealing treatment on the power device based on the actual breakover voltage to change the doping concentration of a buffer region in the power device so as to adjust the actual breakover voltage of the power device. According to the method, regulation and control of the actual breakover voltage of the power device can be realized, so that the inter-chip consistency of the breakover voltage of the power device can be improved.

Description

Technical Field

[0001] This disclosure relates to the field of semiconductor technology, and in particular to a method for regulating the turnaround voltage of a power device. Background Technology

[0002] For power devices such as FRD (Fast Recovery Diode), IGBT (Insulated Gate Bipolar Transistor), GTO (Gate Turn-Off Thyristor), and IGCT (Integrated Gate-Commutated Thyristor), the breakover voltage is a crucial characteristic determining the device's application range and reliability. However, due to limitations imposed by chip manufacturing processes such as uniformity, stability, and contamination control, devices may break down at defect locations, leading to issues like degraded breakover voltages in some devices and inconsistent breakdown voltages between wafers. For wafer-level devices like GTOs and IGCTs, surface defects and dangling bonds often result in weak points in the chip's breakdown voltage at the edges. After failure, the ceramic casing experiences significant thermal stress, easily leading to casing cracking and cascading failures of other system components, threatening the operation of the entire valve assembly.

[0003] In recent years, applications such as modular multilevel circuits have demanded high breakdown voltage consistency in power electronic devices to protect other components in the module, such as capacitors and diodes, from breakdown due to overvoltage. Low inter-chip consistency in break-in voltage means that the protection circuits and components required for use with the same batch of chips need to be adjusted according to the break-in voltage of each chip, which is detrimental to modular production. Summary of the Invention

[0004] One technical problem addressed by this disclosure is the low inter-chip consistency of the break-off voltage of power devices in related technologies.

[0005] According to one aspect of this disclosure, a method for adjusting the break-off voltage of a power device is provided, comprising: measuring the actual break-off voltage of the power device; and performing proton irradiation and annealing treatments on the power device based on the actual break-off voltage to change the doping concentration of a buffer in the power device, thereby adjusting the actual break-off voltage of the power device.

[0006] In some embodiments, performing proton irradiation on the power device includes: determining process parameters for the proton irradiation treatment, the process parameters including irradiation energy and irradiation dose.

[0007] In some embodiments, determining the process parameters of the proton irradiation treatment includes: determining an irradiation depth based on the depth of the buffer, wherein the irradiation depth is the depth of the center position of the Bragg peak formed by doping through the proton irradiation treatment; determining a first edge depth and a second edge depth of the Bragg peak based on the irradiation depth and a doping depth value corresponding to the energy dissipation parameter of the proton irradiation system; and determining the irradiation energy based on the first edge depth, the second edge depth, and the correspondence between the first edge depth, the second edge depth, and the irradiation energy.

[0008] In some embodiments, the first edge depth is y1-y2, and the second edge depth is y1+y2, where y1 is the irradiation depth and y2 is the doping depth value corresponding to the energy dissipation parameter.

[0009] In some embodiments, during the determination of the irradiation energy, the depth of the second edge is less than or equal to the depth of the boundary between the base region of the power device and the buffer zone, wherein the base region is the region adjacent to the buffer zone.

[0010] In some embodiments, determining the process parameters of the proton irradiation treatment includes: calculating the actual doping concentration of the buffer in the power device based on the actual breakover voltage, and calculating the design value of the doping concentration of the buffer in the power device based on the design value of the breakover voltage of the power device; calculating the absolute value of the difference between the doping concentration design value and the actual doping concentration; and calculating the irradiation dose of the proton irradiation treatment based on the absolute value of the doping concentration difference.

[0011] In some embodiments, the irradiation dose of the proton irradiation treatment for Where ΔN is the doping concentration difference, K T The doping coefficient is related to the substrate material of the power device and the annealing temperature of the annealing process.

[0012] In some embodiments, with the same substrate material, different annealing temperatures correspond to different doping coefficients.

[0013] In some embodiments, the actual doping concentration N′ of the buffer in the power device Dbuffer for Where U1 is the actual breakover voltage of the power device, ε sLet x be the dielectric constant of the substrate material of the power device, x1 be the width of the first region of the power device, x2 be the width of the buffer of the power device, E1 be the electric field strength at the boundary between the first region and the second region of the power device under the breakdown voltage, and q be the unit charge. The first region is located between the buffer and the second region, the conductivity type of the first region is the same as that of the buffer, and the conductivity type of the second region is opposite to that of the buffer.

[0014] In some embodiments, the design value N of the doping concentration of the buffer in the power device Dbuffer for Among them, U set ε is the design value for the breakover voltage of the power device. s Let x be the dielectric constant of the substrate material of the power device, x1 be the width of the first region of the power device, x2 be the width of the buffer of the power device, E1 be the electric field strength at the boundary between the first region and the second region of the power device under the breakdown voltage, and q be the unit charge. The first region is located between the buffer and the second region, the conductivity type of the first region is the same as that of the buffer, and the conductivity type of the second region is opposite to that of the buffer.

[0015] In some embodiments, the first region is a first base region and the second region is a second base region; or the first region is a base region and the second region is a collector region.

[0016] In some embodiments, the power device includes the buffer, a first region, and a second region, wherein the first region is located between the buffer and the second region; if the conductivity type of the buffer is n-type, the conductivity type of the first region is n-type, and the conductivity type of the second region is p-type, and the actual breakover voltage of the power device is less than the design value of the breakover voltage of the power device, then the actual breakover voltage of the power device is increased by performing proton irradiation treatment and annealing treatment on the power device.

[0017] In some embodiments, the power device includes the buffer, a first region, and a second region, wherein the first region is located between the buffer and the second region; when the conductivity type of the buffer is p-type, the conductivity type of the first region is p-type, and the conductivity type of the second region is n-type, if the actual breakover voltage of the power device is greater than the design value of the breakover voltage of the power device, the actual breakover voltage of the power device is reduced by performing proton irradiation treatment and annealing treatment on the power device.

[0018] In some embodiments, the power device includes the buffer, a first region, and a second region, wherein the first region is located between the buffer and the second region, the conductivity type of the buffer is n-type, the conductivity type of the first region is n-type, and the conductivity type of the second region is p-type; the method further includes: during the measurement of the actual break-through voltage of the power device, determining the location with the highest temperature in the buffer using a thermal imager, the location with the highest temperature being the actual breakdown location in the buffer; and if the actual breakdown location is not a predetermined breakdown location in the buffer, performing proton irradiation and annealing treatment on the actual breakdown location in the buffer, so that the break-through voltage at the actual breakdown location is greater than the break-through voltage at the predetermined breakdown location.

[0019] In some embodiments, the power device includes the buffer, a first region, and a second region, wherein the first region is located between the buffer and the second region, the conductivity type of the buffer is p-type, the conductivity type of the first region is p-type, and the conductivity type of the second region is n-type; the method further includes: during the measurement of the actual break-through voltage of the power device, determining the location with the highest temperature in the buffer using a thermal imager, the location with the highest temperature being the actual breakdown location in the buffer; and if the actual breakdown location is not a predetermined breakdown location in the buffer, performing proton irradiation and annealing treatment on the predetermined breakdown location in the buffer, so that the break-through voltage at the predetermined breakdown location is less than the break-through voltage at the actual breakdown location.

[0020] In the above method, the actual break-off voltage of the power device is measured, and based on the actual break-off voltage, proton irradiation and annealing are performed on the power device to change the doping concentration of the buffer zone in the power device, thereby adjusting the actual break-off voltage of the power device. This method can achieve the regulation of the actual break-off voltage of the power device after it has been fabricated or formed, thereby improving the inter-chip consistency of the break-off voltage of the power device.

[0021] Other features and advantages of this disclosure will become clear from the following detailed description of exemplary embodiments with reference to the accompanying drawings. Attached Figure Description

[0022] The accompanying drawings, which form part of this specification, illustrate embodiments of this disclosure and, together with the specification, serve to explain the principles of this disclosure.

[0023] This disclosure will become clearer with reference to the accompanying drawings and the following detailed description, wherein:

[0024] Figure 1This is a flowchart illustrating a method for adjusting the turnaround voltage of a power device according to some embodiments of the present disclosure;

[0025] Figure 2 This is a cross-sectional schematic diagram illustrating a stage of the manufacturing process of an IGCT device according to some embodiments of the present disclosure;

[0026] Figure 3 This is a cross-sectional schematic diagram illustrating the structure of another stage in the manufacturing process of an IGCT device according to some embodiments of the present disclosure;

[0027] Figure 4 This is a cross-sectional schematic diagram illustrating the structure of another stage in the manufacturing process of an IGCT device according to some embodiments of the present disclosure;

[0028] Figure 5 This is a cross-sectional schematic diagram illustrating the structure of another stage in the manufacturing process of an IGCT device according to some embodiments of the present disclosure;

[0029] Figure 6 This is a cross-sectional schematic diagram illustrating the structure of another stage in the manufacturing process of an IGCT device according to some embodiments of the present disclosure;

[0030] Figure 7 This is a schematic cross-sectional view of an IGCT device according to some embodiments of the present disclosure;

[0031] Figure 8 This is a schematic diagram showing the structure and electric field distribution of an IGCT device according to some embodiments of the present disclosure before proton irradiation treatment;

[0032] Figure 9 This is a schematic diagram showing the structure and electric field distribution of an IGCT device according to some embodiments of the present disclosure after proton irradiation treatment;

[0033] Figure 10 This is a schematic diagram illustrating the execution of proton irradiation treatment according to some embodiments of the present disclosure;

[0034] Figure 11 This is a cross-sectional schematic diagram showing the structure of a stage in the manufacturing process of a transistor according to some embodiments of the present disclosure;

[0035] Figure 12 This is a cross-sectional schematic diagram illustrating the structure of another stage in the manufacturing process of a transistor according to some embodiments of the present disclosure;

[0036] Figure 13 This is a cross-sectional schematic diagram illustrating the structure of another stage in the manufacturing process of a transistor according to some embodiments of the present disclosure;

[0037] Figure 14This is a cross-sectional schematic diagram illustrating the structure of another stage in the manufacturing process of a transistor according to some embodiments of the present disclosure;

[0038] Figure 15 This is a schematic diagram showing the structure of a transistor according to some embodiments of the present disclosure before proton irradiation and its electric field distribution;

[0039] Figure 16 This is a schematic diagram showing the structure and electric field distribution of a transistor according to some embodiments of the present disclosure after proton irradiation;

[0040] Figure 17 This is a schematic diagram illustrating the execution of proton irradiation treatment according to other embodiments of the present disclosure;

[0041] Figure 18 This is a cross-sectional schematic diagram showing a portion of the structure of an IGCT device according to other embodiments of the present disclosure;

[0042] Figure 19 This is a schematic diagram showing the structure and electric field distribution of an IGCT device in related technologies;

[0043] Figure 20 This is a schematic diagram illustrating the structure and electric field distribution of an IGCT device according to other embodiments of the present disclosure.

[0044] It should be understood that the dimensions of the various parts shown in the accompanying drawings are not drawn to actual scale. Furthermore, the same or similar reference numerals denote the same or similar components. Detailed Implementation

[0045] Various exemplary embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. The descriptions of the exemplary embodiments are merely illustrative and are in no way intended to limit the present disclosure or its application or use. The present disclosure may be implemented in many different forms and is not limited to the embodiments described herein. These embodiments are provided so that the present disclosure will be thorough and complete, and will fully express the scope of the disclosure to those skilled in the art. It should be noted that, unless specifically stated otherwise, the relative arrangement of components and steps, the composition of materials, numerical expressions, and values ​​set forth in these embodiments should be interpreted as exemplary only and not as limiting.

[0046] The terms "first," "second," and similar words used in this disclosure do not indicate any order, quantity, or importance, but are merely used to distinguish different parts. Words such as "including" or "contains" mean that the element preceding the word encompasses the element listed after it, and do not exclude the possibility of encompassing other elements as well. Terms such as "above," "below," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, this relative positional relationship may also change accordingly.

[0047] In this disclosure, when a specific device is described as being located between a first device and a second device, an intermediary device may or may not be present between the specific device and the first or second device. When a specific device is described as being connected to other devices, the specific device may be directly connected to the other devices without an intermediary device, or it may be not directly connected to the other devices but have an intermediary device.

[0048] All terms used in this disclosure (including technical or scientific terms) have the same meaning as understood by one of ordinary skill in the art to which this disclosure pertains, unless otherwise specifically defined. It should also be understood that terms defined in a general dictionary, such as a dictionary, should be interpreted as having a meaning consistent with their meaning in the context of the relevant art, and not as having an idealized or highly formalized meaning, unless expressly defined herein.

[0049] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and equipment should be considered part of the specification.

[0050] Figure 1 This is a flowchart illustrating a method for adjusting the turnaround voltage of a power device according to some embodiments of the present disclosure. Figure 1 As shown, the method includes steps S110 to S120.

[0051] In step S110, the actual breakover voltage of the power device is measured.

[0052] For example, the actual breakover voltage of a power device can be measured using methods such as the volt-ampere scanning method and the pulse test method. Here, the methods known to those skilled in the art can be used to measure the breakover voltage, and therefore will not be described in detail here.

[0053] In step S120, based on the actual breakover voltage, proton irradiation and annealing are performed on the power device to change the doping concentration of the buffer in the power device, thereby adjusting the actual breakover voltage of the power device.

[0054] Here, proton irradiation technology can locally create hydrogen-related defects in the longitudinal direction of a device (or chip). After annealing, these defects exhibit n-type doping characteristics. Due to the light mass of protons, by controlling the irradiation energy, protons can be controlled to a specific location and width within the longitudinal direction of the device (or chip). By controlling the irradiation dose, the local doping concentration can be controlled.

[0055] Proton irradiation can be used to vertically and locally dope within a device (or chip) to form a doped layer with a higher doping concentration than the substrate layer. This doped layer can serve as a field cutoff layer during device breakdown, reducing the likelihood of punch-through and thus regulating the breakdown voltage. For example, it can increase the breakdown voltage in some cases. This technique can be applied to power devices.

[0056] For example, if measurements reveal that the transition voltage of one or more power devices differs from that of other normal power devices among multiple power devices formed, proton irradiation technology can be used to alter the doping concentration of the buffer zones in these power devices, thereby adjusting their transition voltages to match those of the other normal power devices. This improves the inter-device consistency of the transition voltages of power devices.

[0057] Therefore, a method for adjusting the break-off voltage of a power device according to some embodiments of the present disclosure is provided. The method includes: measuring the actual break-off voltage of the power device; and, based on the actual break-off voltage, performing proton irradiation and annealing treatments on the power device to change the doping concentration of the buffer zone in the power device, thereby adjusting the actual break-off voltage of the power device. This method can achieve regulation of the actual break-off voltage of the power device after it has been fabricated or formed, thereby improving the inter-chip consistency of the break-off voltage of the power device.

[0058] In addition to controlling the turnaround voltage of power devices, the above methods can also reduce process difficulty, improve process yield and controllability.

[0059] In some embodiments, performing proton irradiation on a power device includes determining process parameters for the proton irradiation process, including irradiation energy and irradiation dose. That is, during proton irradiation, the process is primarily achieved by controlling these two parameters: irradiation energy and irradiation dose. This allows for a corresponding change in the doping concentration of the buffer zone within the power device, thereby adjusting the breakover voltage of the power device.

[0060] In some embodiments, determining the process parameters for proton irradiation treatment, for the irradiation energy, may include: determining the irradiation depth based on the depth of the buffer zone, wherein the irradiation depth is the depth of the center position of the Bragg peak formed by proton irradiation doping; determining the first edge depth and the second edge depth of the Bragg peak based on the irradiation depth and the doping depth value corresponding to the energy dissipation parameter of the proton irradiation system; and determining the irradiation energy based on the first edge depth, the second edge depth, and the correspondence between the first edge depth, the second edge depth, and the irradiation energy.

[0061] Here, in proton irradiation technology, "energy spread" refers to "proton beam energy spread," often simply called "energy spread." It is defined as the degree to which the energy of each particle in a proton beam bombarding a target or sample deviates from the nominal energy. Typically, for a proton beam with a nominal energy of E0, the possible energy of a single proton can be expressed as E = E0 ± ΔE, where ΔE is the energy spread parameter. For example, in the embodiments of this disclosure, the possible energy value of a single proton can be 1.2 MeV (megaelectron volts) ± 0.1 MeV, where 0.1 MeV is the energy spread parameter. After obtaining the energy spread parameter, the corresponding doping depth value y2 can be obtained, for example, the doping depth value corresponding to 0.1 MeV.

[0062] In the above embodiments, the depth of the buffer zone of the power device is known. Since proton irradiation is used to change the doping concentration of the buffer zone, the irradiation depth is essentially consistent with the depth of the buffer zone. Here, the irradiation depth is the depth of the center position of the Bragg peak formed by proton irradiation treatment. Since the Bragg peak has a certain width, the first edge depth and the second edge depth of the Bragg peak can be determined based on the irradiation depth and the doping depth value corresponding to the energy dissipation parameter of the proton irradiation system. Here, after obtaining the energy dissipation parameter of the proton irradiation system, since this energy dissipation parameter also causes the proton doping depth, the doping depth value corresponding to the energy dissipation parameter can be obtained. Therefore, the first edge depth and the second edge depth of the Bragg peak can be determined based on the irradiation depth and the doping depth value corresponding to the energy dissipation parameter. For example, the first edge depth is y1-y2, and the second edge depth is y1+y2, where y1 is the irradiation depth and y2 is the doping depth value corresponding to the energy dissipation parameter.

[0063] The correspondence between the first edge depth, the second edge depth, and the irradiation energy can be obtained in advance through experiments. For example, a table showing the correspondence between different first edge depths, different second edge depths, and different irradiation energies can be obtained through multiple experiments. Therefore, based on the previously calculated first and second edge depths and the pre-obtained correspondence between the two edge depths and the irradiation energy, the irradiation energy corresponding to the calculated first and second edge depths can be determined. In this way, the purpose of determining the irradiation energy for proton irradiation treatment is achieved, thereby facilitating the implementation of a suitable proton irradiation process.

[0064] In some embodiments, proton irradiation can be performed on the power device from its back side. This facilitates the implementation of the proton irradiation technique.

[0065] In determining the irradiation energy, the depth of the second edge is made less than or equal to the depth of the boundary between the base region and the buffer region of the power device, where the base region is the area adjacent to the buffer region. That is, since proton irradiation is performed on the power device from the back side, by ensuring the depth of the second edge is less than or equal to the depth of the boundary between the base region and the buffer region, a more suitable irradiation energy can be obtained. This allows the dopant (i.e., protons) to be doped as far as the boundary between the base region and the buffer region when performing proton irradiation using this energy, thus enabling precise control of the doping depth.

[0066] In some embodiments, determining the process parameters for proton irradiation treatment, specifically the irradiation dose, includes: calculating the actual doping concentration of the buffer in the power device based on the actual transition voltage, and calculating the designed doping concentration of the buffer in the power device based on the designed transition voltage of the power device; calculating the absolute value of the difference between the designed doping concentration and the actual doping concentration; and calculating the irradiation dose of the proton irradiation treatment based on the absolute value of the doping concentration difference. In other words, the actual doping concentration and the designed doping concentration of the buffer are first calculated based on the transition voltage (actual transition voltage and designed transition voltage), then the absolute value of the difference between the designed doping concentration and the actual doping concentration is calculated, and the irradiation dose is calculated based on this absolute value. This achieves the goal of calculating the irradiation dose based on the transition voltage, thereby obtaining a suitable irradiation dose.

[0067] In some embodiments, the actual doping concentration N′ in the buffer of the power device is... Dbuffer for

[0068]

[0069] Where U1 is the actual breakover voltage of the power device (which can be obtained through measurement), ε s Let x be the dielectric constant of the substrate material of the power device, x1 be the width of the first region of the power device, x2 be the width of the buffer zone of the power device, E1 be the electric field strength at the boundary between the first region and the second region of the power device under the breakdown voltage, and q be the unit charge. The first region is located between the buffer zone and the second region, and the conductivity type of the first region is the same as that of the buffer zone, while the conductivity type of the second region is opposite to that of the buffer zone. For example, the first region can be a first base region, and the second region can be a second base region; or the first region can be a base region, and the second region can be a collector region.

[0070] In some embodiments, the design value N of the doping concentration in the buffer of the power device is... Dbuffer for

[0071]

[0072] Among them, U set ε is the design value for the breakover voltage of the power device (this design value can be pre-designed). s Let x be the dielectric constant of the substrate material of the power device, x1 be the width of the first region of the power device, x2 be the width of the buffer zone of the power device, E1 be the electric field strength at the boundary between the first region and the second region of the power device under the breakdown voltage, and q be the unit charge. The first region is located between the buffer zone and the second region, and the conductivity type of the first region is the same as that of the buffer zone, while the conductivity type of the second region is opposite to that of the buffer zone. For example, the first region can be a first base region, and the second region can be a second base region; or the first region can be a base region, and the second region can be a collector region.

[0073] The absolute value of the difference in doping concentration ΔN between the designed doping concentration and the actual doping concentration is calculated as follows:

[0074] |△N|=|N Dbuffer -N′ Dbuffer |, (3)

[0075] Here, when the actual breakover voltage of the power device is less than the design value of the breakover voltage of the power device, the doping concentration difference ΔN is a positive value, and the absolute value can be omitted here; if we consider the case where the actual breakover voltage of the power device is greater than the design value of the breakover voltage, the doping concentration difference ΔN is a negative value, and the absolute value can be retained.

[0076] For example, when it is necessary to replenish the doping concentration of the buffer, ΔN is the required doping concentration.

[0077] In some embodiments, the irradiation dose of proton irradiation treatment for

[0078]

[0079] Where ΔN is the doping concentration difference, K T K represents the doping coefficient, which is related to the substrate material of the power device and the annealing temperature of the annealing process. T The known coefficients can be obtained based on the substrate material of the power device and the annealing temperature of the annealing process. Here, the doping coefficient K... T The doping coefficient is the ratio of doping concentration to irradiation dose, and it is typically a constant for a given material and annealing temperature.

[0080] For example, with the same substrate material, different annealing temperatures correspond to different doping coefficients. Conversely, at the same annealing temperature, different substrate materials can correspond to different doping coefficients.

[0081] In some cases, the design value U of the breakover voltage of power devices set satisfy:

[0082]

[0083] E2 is the electric field strength at the boundary between the first region (e.g., the base region) and the buffer zone of the power device.

[0084] Therefore, by substituting the above relations (1)-(3) and (5) into relation (4), we can obtain

[0085]

[0086] This allows us to obtain the irradiation dose for proton irradiation treatment.

[0087] In some embodiments, the power device includes a buffer, a first region, and a second region, wherein the first region is located between the buffer and the second region. When the conductivity type of the buffer is n-type, the conductivity type of the first region is n-type, and the conductivity type of the second region is p-type, if the actual breakover voltage of the power device is less than its design breakover voltage, the actual breakover voltage of the power device is increased by performing proton irradiation and annealing treatments. This achieves the goal of improving the inter-chip consistency of the breakover voltage of power devices in some cases by increasing the breakover voltage of a particular device.

[0088] The following describes some embodiments of the methods disclosed herein, using an IGCT device as a power device. Although an IGCT device is used as an example here, other power devices can be substituted in actual applications. Here, the description is based on an example of an n-buffer, an n-base region, and a p-base region.

[0089] Figures 2 to 6 This is a cross-sectional schematic diagram illustrating the structure of several stages in the manufacturing process of an IGCT device according to some embodiments of the present disclosure.

[0090] First, such as Figure 2 As shown, n-type single-crystal silicon is used as the substrate, which has an n-base region 201. Here, the n-base region 201 is the first region mentioned above.

[0091] Next, as Figure 3 As shown, boron ion implantation at different concentrations and depths is performed twice on the front side of the substrate, followed by further implantation to form p-based region 202 and p+ based region 203. The doping concentration of p+ based region 203 is greater than that of p-based region 202. For example, the depth of the p-based region ranges from 100 micrometers to 200 micrometers, and the doping concentration of the p-based region ranges from 5 × 10⁻⁶. 12atoms / cm 3 Up to 1×10 16 atoms / cm 3 The depth of the p+ base region ranges from 40 micrometers to 80 micrometers, and the doping concentration of the p+ base region ranges from 1 × 10⁻⁶. 15 atoms / cm 3 Up to 1×10 19 atoms / cm 3 The p-base region 202 here is the second region mentioned above.

[0092] Next, as Figure 4 As shown, full-area phosphorus ion implantation and propagation are performed at the anode to form an n-buffer layer (also called a buffer layer) 204. For example, the doping concentration of the n-buffer layer ranges from 1 × 10⁻⁶. 13 atoms / cm 3 Up to 1×10 16 atoms / cm 3 The depth of the n-buffer ranges from 5 micrometers to 50 micrometers. The n-buffer here refers to the buffer described earlier.

[0093] Next, as Figure 5 As shown, phosphorus pre-deposition is performed on the front side of the substrate. The pre-deposited phosphorus region is patterned (wet etching) to form a comb-like structure, which is then advanced to form the n+ emitter 205. The doping concentration of this n+ emitter 205 is greater than that of the n-base region. The doping concentration of this n+ emitter ranges from 1 × 10⁻⁶. 18 atoms / cm 3 Up to 1×10 21 atoms / cm 3 The depth range of the n+ emitter is 5 micrometers to 30 micrometers.

[0094] Next, as Figure 6 As shown, boron ion implantation and high-temperature annealing are performed on the back side of the substrate to form a p+ emitter 206. For example, the doping concentration of the p+ emitter 206 ranges from 1 × 10⁻⁶. 17 atoms / cm 3 Up to 1×10 21 atoms / cm 3 The depth range of the p+ emitter 206 is 0.1 micrometers to 10 micrometers.

[0095] Next, as Figure 6 As shown, the final processing of a device (or chip) includes processes such as rounding, corner grinding, cleaning and etching, edge passivation, and applying red glue. For example, as... Figure 6 As shown, silicone is applied to the semiconductor structure to protect the device.

[0096] In addition, such as Figure 7 As shown, the steps for forming a power device also include the formation of an anode 211, a cathode 212, and gate electrodes 213 and 214. These are all known forming processes and will not be described in detail here. This results in the formation of a device as shown in the diagram. Figure 7 The IGCT device shown. Figure 7 This is a schematic cross-sectional view illustrating an IGCT device according to some embodiments of the present disclosure. Figure 7 It can be seen that there are three pn junctions in this IGCT device, namely, the J1 junction, the J2 junction, and the J3 junction.

[0097] In embodiments of this disclosure, such as Figure 10 As shown, after forming the IGCT device 20, the back surface of the IGCT device 20 can be subjected to full-surface proton irradiation treatment. For example, the process requirements for this proton irradiation treatment are as follows: (1) Irradiation energy: 0.2 MeV (megaelectron volts) to 2.0 MeV, corresponding to a depth of 2.0 micrometers to 45 micrometers; (2) Irradiation dose: 1 × 10⁻⁶ 11 atoms / cm 2 Up to 1×10 15 atoms / cm 2 For example, irradiation energy can be confirmed by combining device structure design with proton irradiation SRIM simulation, and irradiation dose can be designed by combining device structure and design objectives with pre-irradiation blocking capability.

[0098] Table 1. SRIM Simulation Proton Irradiation Energy-Depth Relationship

[0099]

[0100]

[0101] In addition, the annealing process includes: annealing temperature of 300℃ to 500℃, time of 2h to 10h, and nitrogen atmosphere.

[0102] The schematic diagrams of the device structure and electric field distribution before and after proton irradiation are shown below. Figure 8 and Figure 9 As shown. Figure 8 This is a schematic diagram showing the structure and electric field distribution of an IGCT device according to some embodiments of the present disclosure before proton irradiation treatment. Figure 9 This is a schematic diagram illustrating the structure and electric field distribution of an IGCT device according to some embodiments of the present disclosure after proton irradiation treatment. Figure 9 In this context, the n-buffer zone represents the region that has been irradiated by protons.

[0103] like Figure 8As shown, before proton irradiation, the electric field is just cut off at the J1 junction. If the voltage continues to increase at this time, the electric field will penetrate through the J1 junction into the p+ emitter region, and the depletion region will not be able to continue to be established, and the device will experience punch-through breakdown. However, after proton irradiation, due to the increase in the equivalent doping concentration of the n buffer, the electric field will not extend to the boundary of the J1 junction at the same voltage. Further increases in voltage will not cause the electric field to penetrate to the p+ emitter, thereby increasing the device's breakover voltage.

[0104] In the above embodiments, the transition voltage of the device can be controlled by proton irradiation treatment. This can be applied to all power devices. For the case where the transition voltage is insufficient due to electric field punch-through during withstand voltage, it can be improved by forming a field cutoff layer through proton irradiation.

[0105] In the above embodiments, with Figure 7 Taking the IGCT shown as an example, if the actual break-off voltage of the device is less than the design value of the break-off voltage, the doping concentration of the n buffer of the device needs to be increased in order to improve the actual break-off voltage. As can be seen from the above description, the actual break-off voltage of the device can be improved by performing proton irradiation treatment and annealing treatment on the device.

[0106] In other embodiments, the power device includes a buffer, a first region, and a second region, wherein the first region is located between the buffer and the second region. When the conductivity type of the buffer is p-type, the conductivity type of the first region is p-type, and the conductivity type of the second region is n-type, if the actual breakover voltage of the power device is greater than its design breakover voltage value, the actual breakover voltage of the power device is reduced by performing proton irradiation and annealing treatments. This achieves, in some cases, the goal of improving the inter-chip consistency of the breakover voltage of the power device by reducing the breakover voltage of a particular device.

[0107] The following describes some embodiments of the methods disclosed herein, using an NPN transistor as a power device. Although an NPN transistor is used as an example here, other power devices can be substituted in actual applications. Here, the description is based on an example where the buffer is a p-buffer, the first region is a p-base region, and the second region is an n+ collector.

[0108] Figures 11 to 14 This is a cross-sectional schematic diagram illustrating the structure of several stages in the manufacturing process of a transistor according to some embodiments of the present disclosure.

[0109] First, such as Figure 11 As shown, p-type single-crystal silicon is used as the substrate. This substrate has a p-based region 301. This p-based region is the first region mentioned above.

[0110] Next, as Figure 12As shown, phosphorus ion implantation is performed on the front side of the substrate, followed by advancement to form an n+ collector 302. For example, the depth of this n+ collector ranges from 10 micrometers to 80 micrometers, and the doping concentration of this n+ collector ranges from 1 × 10⁻⁶. 15 atoms / cm 3 Up to 1×10 19 atoms / cm 3 The n+ collector 302 is the second region mentioned above.

[0111] Next, as Figure 13 As shown, boron ion implantation and propagation are performed on the back side of the substrate to form a p-buffer (or buffer layer) 304. For example, the doping concentration of this p-buffer ranges from 1 × 10⁻⁶. 13 atoms / cm 3 Up to 1×10 16 atoms / cm 3 The depth of this p-buffer ranges from 5 micrometers to 50 micrometers. This p-buffer is the buffer mentioned earlier.

[0112] Next, as Figure 14 As shown, phosphorus ion implantation and high-temperature annealing are performed on the back side of the substrate to form an n+ emitter 306. For example, the doping concentration of this n+ emitter ranges from 1 × 10⁻⁶. 17 atoms / cm 3 Up to 1×10 21 atoms / cm 3 The depth range of the n+ emitter is 0.1 micrometers to 10 micrometers.

[0113] Next, the entire front surface of the device was subjected to proton irradiation. Schematic diagrams of the device structure and electric field distribution before and after proton irradiation are shown below. Figure 15 and Figure 16 As shown. Figure 15 This is a schematic diagram showing the structure of a transistor and its electric field distribution before proton irradiation according to some embodiments of the present disclosure. Figure 16 This is a schematic diagram illustrating the structure and electric field distribution of a transistor according to some embodiments of the present disclosure after proton irradiation. Figure 16 In this context, the p buffer is the region that has been irradiated with protons.

[0114] like Figure 15 As shown, before proton irradiation, the electric field is cut off inside the p buffer zone, and at the same voltage, the electric field will not penetrate to the n+ emitter, resulting in a higher transition voltage; however, after proton irradiation, as... Figure 16As shown, the electric field is just cut off at the pn junction between the p buffer and the n+ emitter. If the voltage continues to increase at this time, the electric field will pass through the pn junction and enter the region of the n+ emitter, and the device will undergo punch-through breakdown, which is equivalent to reducing the device's breakover voltage.

[0115] After proton irradiation, the p-buffer buffer is equivalent to the simultaneous generation of p-type and n-type doping, ultimately exhibiting a higher doping concentration. For the p-buffer buffer to retain its blocking capability after irradiation, the equivalent n-type doping concentration generated by irradiation needs to be lower than the p-buffer concentration (the concentration of p-type doping). Specific irradiation and annealing process requirements are the same as or similar to those in the previous embodiments. In other words, proton irradiation of the p-buffer buffer, since the proton irradiation is n-type doping, is equivalent to using n-type doping to offset a portion of the p-type doping, thereby reducing the equivalent concentration of p-type doping and consequently lowering the breakover voltage. This is particularly applicable to power devices that include an n-buffer buffer, a p-base region, and an n-collector, where the actual breakover voltage of the power device is greater than its design value. By performing proton irradiation and annealing on a power device to reduce its actual breakover voltage, the inter-chip consistency of the power device's breakover voltage can be improved.

[0116] The above method can be applied to all power devices. For cases where the breakover voltage is too high due to electric field punch-through in the P-type region during breakdown voltage, proton irradiation can be used to improve the situation.

[0117] In some embodiments, proton irradiation can not only regulate the break-through voltage but also change the breakdown position of power devices. This can be applied to power devices that require control of the breakdown position. For example, taking CP-IGCT (Controlled Punch-through-Integrated Gate-Commutated Thyristor) as an example, in the CP-IGCT of related technologies, the device uses photolithography and implantation processes to process the n-buffer in the asymmetric IGCT into a patterned buffer. The patterned buffer includes a small n-buffer region (which can be called the first sub-buffer region) and a large n+-buffer region (which can be called the second sub-buffer region). Here, the doping concentration of the first sub-buffer region is less than that of the second sub-buffer region.

[0118] As mentioned earlier, for whole-wafer devices, the uniformity and consistency of chip and terminal processes often result in poor terminal withstand voltage, which in turn leads to poor inter-wafer withstand voltage consistency. Therefore, CP-IGCT controls the controllable punch-through area in the center of the chip. On the one hand, it can change the withstand voltage bottleneck from the chip terminal to the inside of the chip, thereby improving inter-wafer consistency. On the other hand, it can reduce the impact of breakdown on the package and valve assembly.

[0119] Figure 19 This is a schematic diagram showing the structure and electric field distribution of an IGCT device in related technologies. Figure 20 This is a schematic diagram illustrating the structure and electric field distribution of an IGCT device according to other embodiments of the present disclosure. Figure 19 This is a schematic diagram of the unit cell structure of the asymmetric IGCT PNP region in related technologies. Figure 20 The middle n-buffer has a lower doping concentration than the n+ buffer. Controlled breakdown can be achieved by controlling the concentration in this region. This vertical region is called the controlled breakdown region.

[0120] This embodiment achieves modulation of the break-off voltage of the CP-IGCT device through proton irradiation. The fabrication process of the CP-IGCT device is similar to that described above, and the specific steps are as follows:

[0121] First, n-type single-crystal silicon is used as the substrate.

[0122] Next, boron ion implantation with different concentrations and depths is performed twice on the front side of the substrate, followed by further implantation to form p-based and p+ based regions.

[0123] Next, full-area phosphorus ion implantation and propulsion are performed at the anode to form an n-buffer zone. For example, the design breakdown voltage (i.e., the design value of the power device's breakover voltage) is U. set The width of the n-base region (i.e., the width of the first region of the power device) is x1, and the doping concentration is N. Dbase The width of the n-buffer (i.e., the width of the buffer for the power device) is x2, and the doping concentration is N. Dbuffer The electric field strength at the boundary between the n-base region and the p-base region (i.e., the second region of the power device) under the breakdown voltage is E1, and the electric field strength at the boundary between the n-base region and the n-buffer zone is E2. We approximate that the doping in each region is uniform.

[0124] Design principles are met:

[0125]

[0126] Equation (6) applies to the design of controlled-breakdown IGCTs. For ordinary IGCTs, it is necessary to ensure that the actual width of the n-buffer is greater than x2 in the above equation to prevent device breakdown. In equation (6), the first term represents the voltage borne by the n-base region, and the second term represents the voltage borne by the n-buffer. In the actual electric field strength, the width of the portion of the p-base region that bears the electric field strength is very small, that is, the voltage borne by the p-base region is very small. For ease of calculation, the voltage borne by the p-base region can be ignored. Therefore, in the calculation, only the voltage borne by the n-base region and the voltage borne by the n-buffer can be considered.

[0127] doping concentration N of the n-bufferDbuffer for:

[0128]

[0129] Where, ε si The dielectric constant of the silicon substrate material (ε is the dielectric constant of the substrate material for the power devices mentioned above). s (An example), where q is the unit charge.

[0130] Since subsequent irradiation processes can increase but not decrease the doping concentration of the n-buffer, the doping concentration of the buffer in this step can be taken as a predetermined percentage (e.g., 80%) of the design doping concentration value, in order to provide a margin for the regulation of the breakover voltage.

[0131] Next, phosphorus pre-deposition is performed on the front side of the substrate. The pre-deposited phosphorus area is patterned (wet etching) to form a comb structure, and then the process is advanced to form an n+ emitter.

[0132] Next, boron ion implantation and high-temperature annealing are performed on the back side of the substrate to form a p+ emitter.

[0133] Next, the chip (i.e. the device) undergoes final processing, including processes such as rounding, grinding, cleaning and etching, edge passivation, and applying red glue.

[0134] Next, the back of the chip (i.e., the device) undergoes localized proton irradiation. The localized proton irradiation area is the region outside the CP region. The horizontal and vertical schematic diagrams of the proton irradiation process are shown below. Figure 17 and 18 As shown.

[0135] like Figure 17 As shown, regions 430 and 450 of the wafer are blocked regions and are not irradiated. Region 450 is the edge termination region. Region 440 of the wafer is irradiated with protons. After the localized proton irradiation process, the longitudinal structure of the device is as follows. Figure 18 As shown, the n+ buffer 214 is the second sub-buffer mentioned earlier, and the n buffer is the first sub-buffer mentioned earlier. The n+ buffer can be formed by proton irradiation, and the doping concentration of the n+ buffer ranges from 1×10⁻⁶. 14 atoms / cm 3 Up to 1×10 18 atoms / cm 3 The depth of the n+ buffer ranges from 5 micrometers to 50 micrometers. The n buffer corresponds to... Figure 17 Region 430, which was not irradiated by protons, is an n+ buffer formed by high concentrations of hydrogen (H)-related defect doping after proton irradiation and annealing.

[0136] In some embodiments, the process requirements for proton irradiation are as follows:

[0137] (1) Baffle requirements: ① Number of baffles: 1, the shape and area of ​​the baffle correspond to the CP area; ② Baffle material: metal / alloy, plastic sheet, etc.; ③ Baffle requirements: flat upper surface, thickness ≥ 0.5 mm, lateral dimension accuracy ≤ 0.1 mm (in the IGCT proton irradiation process, the proton energy is usually ≤ 4.0 MeV, and the penetration ability of materials such as metal is ≤ 200 μm, so the baffle area can block all protons).

[0138] (2) Process requirements: ① Irradiation energy: 0.2MeV to 2.0MeV, corresponding to a depth of 2.0μm to 45μm; ② Irradiation dose: 1×10 11 atoms / cm 2 Up to 1×10 15 atoms / cm 2 .

[0139] In addition, the process requirements for annealing include: annealing temperature of 250℃ to 350℃, time of 2h to 10h, and nitrogen atmosphere.

[0140] The selection of irradiation energy is related to the energy dissipation parameters of the proton irradiation system. Since the irradiation depth is the depth of the center of the Bragg peak formed by irradiation doping, assuming it to be y1, if the doping depth corresponding to the energy dissipation parameters is y2, then the actual depths on both sides of the Bragg peak edge are [y1-y2, y1+y2] μm. When selecting the irradiation energy, the depth of the peak depth side, i.e., y1+y2, can be made the same as the boundary depth between the n-buffer and n-base regions. This prevents the depth of the n+buffer from further increasing, thus avoiding impacting other chip characteristics.

[0141] Based on the previously obtained measured data, when single-crystal silicon is selected as FZ (Floating Zone), NTD (Neutron Transmutation Doping), n-type doped, and has a resistivity of 470 Ω·cm, the corresponding y1 and y2 for each irradiation energy are shown in Table 2.

[0142] Table 2

[0143] Serial Number Irradiation energy / MeV <![CDATA[y1(μm)]]> <![CDATA[y2(μm)]]> 1 0.2 2 1.2 2 1.2 20 8 3 2.0 45 15 4 3.0 100 20

[0144] Table 2 shows the correspondence between the first edge depth, the second edge depth and the irradiation energy mentioned above.

[0145] Referring to the table above, for different device structures, the corresponding y1 and y2 are different, and interpolation can be used to obtain the irradiation energy required for different y1 and y2.

[0146] The irradiation dose is related to the annealing process, and the process scheme is as follows.

[0147] First, determine the annealing temperature. When proton irradiation is used for n-doping, the typical annealing temperature is 300℃ to 500℃. However, since the irradiation process is performed after the GCT chip fabrication process is completed, it includes surface PI (polyimide), terminal red glue, and metallization processes. In the GCT process, PI and red glue require subsequent process temperatures ≤350℃, and the metallization process requires subsequent annealing temperatures ≤450℃. Therefore, the irradiation annealing process needs to be compatible with the temperature requirements of the aforementioned processes. Specifically, adjustments can be made based on the brand and model of the corresponding PI and terminal red glue.

[0148] Effective doping concentration N D With radiation dose and doping coefficient K T Related, that is Doping coefficient K T The doping coefficient K is related not only to temperature but also to irradiation energy and substrate material (single crystal type, doping concentration). Based on pre-obtained measured data, the doping coefficient K at various annealing temperatures was determined under the conditions of using FZ, NTD, and n-type doped silicon single crystals with a resistivity of 470 Ω·cm and an irradiation energy of 3.0 MeV. T As shown in Table 3.

[0149] Table 3

[0150]

[0151] For example, as can be seen from Table 3, when the irradiation dose is 1×10 13 atoms / cm 2 When the annealing temperature is 300℃, the effective doping concentration is 1.8×10⁻⁶. 13 atoms / cm 3 .

[0152] With increasing annealing temperature, the effective doping concentration formed by the same irradiation dose shows a significant upward trend. Studies show that when the annealing temperature is between 400℃ and 450℃, the doping coefficient K... T To reach the maximum value. Therefore, when selecting the irradiation dose and annealing temperature, a reasonable annealing temperature can be selected by combining the properties of silicon material, chip design, and the temperature requirements of previous processes, so as to make this step compatible with other processes and minimize the dose and process cost of the irradiation step.

[0153] The chip's blocking capability was tested after proton irradiation. If the chip's breakover voltage U1 is lower than the design value U... set This indicates that the doping concentration in the controllable breakdown region is too low. The doping concentration N' of the n-buffer zone can then be calculated. Dbuffe for:

[0154]

[0155] The required doping concentration ΔN = N Dbuffer -N' Dbuffe At this point, the doping concentration difference ΔN is positive and can be used as the absolute value of the doping concentration difference. Combining this with the aforementioned relationship between irradiation dose and doping concentration, the required supplemental irradiation dose can be calculated.

[0156]

[0157] Referring to equation (9) above, the dose parameters of proton irradiation can be obtained based on the measured transition voltage U1.

[0158] In some cases, practical experience shows that the dosage selection can satisfy the following condition: the equivalent doping concentration of the irradiated region (i.e., the n+ buffer) after irradiation is ≥ a predetermined multiple × the doping concentration of the non-irradiated region (i.e., the controlled breakdown region, the n buffer). For example, the predetermined multiple is 5. If the requirement is still not met after adjustment, the irradiation process can be repeated until the chip breakover voltage meets the requirements.

[0159] In some embodiments, the power device includes a buffer, a first region, and a second region, wherein the first region is located between the buffer and the second region, the buffer is of n-type conductivity (e.g., an n-buffer), the first region is of n-type conductivity (e.g., an n-base region), and the second region is of p-type conductivity (e.g., a p-base region).

[0160] In such a case, the above method may further include: during the measurement of the actual break-in voltage of the power device, determining the location with the highest temperature in the buffer using a thermal imager, wherein the location with the highest temperature is the actual breakdown location in the buffer; and if the actual breakdown location is not the predetermined breakdown location in the buffer, performing proton irradiation and annealing on the actual breakdown location in the buffer, so that the break-in voltage at the actual breakdown location is greater than the break-in voltage at the predetermined breakdown location.

[0161] For example, after proton irradiation, the chip's blocking capability is tested. If the hot spot at the chip's transition point (determined by a thermal imager as the location with the highest temperature in the buffer zone) shifts from the predetermined breakdown location to another location (denoted as point A, which is the actual breakdown location), it indicates that the transition voltage at point A is lower than the transition voltage at the predetermined breakdown location. In this case, proton irradiation and annealing can be performed again at point A to increase the transition voltage, ensuring that the hot spot at the chip's transition point remains at the predetermined breakdown location. That is, the chip breaks down at the predetermined breakdown location during the transition. This changes the actual breakdown location to conform to the pre-designed predetermined breakdown location. For example, this method can be applied to... Figure 7The power device shown.

[0162] In other embodiments, the power device includes a buffer, a first region, and a second region, wherein the first region is located between the buffer and the second region, the buffer is of p-type conductivity (e.g., a p-buffer), the first region is of p-type conductivity (e.g., a p-base region), and the second region is of n-type conductivity (e.g., an n+ collector).

[0163] In such a case, the above method may further include: during the measurement of the actual break-in voltage of the power device, determining the location with the highest temperature in the buffer using a thermal imager, wherein the location with the highest temperature is the actual breakdown location in the buffer; and if the actual breakdown location is not the predetermined breakdown location in the buffer, performing proton irradiation and annealing on the predetermined breakdown location in the buffer, so that the break-in voltage at the predetermined breakdown location is less than the break-in voltage at the actual breakdown location.

[0164] For example, after proton irradiation, the chip's blocking capability is tested. If the hot spot at the chip's transition point (the location with the highest temperature in the buffer determined by a thermal imager) shifts from the predetermined breakdown location to another location (denoted as point A, which is the actual breakdown location), it indicates that the transition voltage at point A is lower than the transition voltage at the predetermined breakdown location. In this case, proton irradiation and annealing can be performed again at the predetermined breakdown location to reduce the transition voltage there, ensuring that the hot spot at the chip's transition point remains at the predetermined breakdown location. That is, the chip still breaks down at the predetermined breakdown location during the transition. This changes the actual breakdown location to conform to the pre-designed predetermined breakdown location. For example, this method can be applied to... Figure 14 The power device shown.

[0165] In the method of this disclosure embodiment, the breakover voltage and breakdown position of the power device can be controlled by proton irradiation. Although this objective can be achieved by photolithography + partitioned ion implantation / thermal diffusion in related technologies, the processes of these technologies have the following drawbacks:

[0166] (1) The high-temperature propulsion process involves multiple steps, and the ultra-high temperature process above 1200℃ increases the risk of contamination. In addition, the process time is long and the process efficiency is low.

[0167] (2) If it is necessary to control the breakdown area, patterned doping is required in conjunction with photolithography, which makes the process relatively complex.

[0168] (3) Low process controllability. After the high-temperature propulsion process is completed, other processes such as doping and metallization will be carried out. The process temperature of each step is different. For example, the metallization temperature is only 500℃ to 600℃. Therefore, if the chip indicators do not meet the requirements, it is impossible to adjust the doping of the corresponding area again.

[0169] Compared with methods in related technologies, the method of this disclosure has the following advantages:

[0170] (1) Reduce the high temperature of the chip manufacturing process, reduce the risk of contamination during the high temperature process, and improve the yield and efficiency of the chip fabrication.

[0171] (2) It can reduce photolithography processes and simplify the process flow.

[0172] (3) Improve process controllability and flexibility. If the controllable breakdown voltage of the chip after irradiation is lower than the design value, the entire surface can be irradiated with protons again to increase the doping concentration of the n buffer and improve the overall controllable breakdown voltage.

[0173] (4) The process is easy to implement and highly feasible.

[0174] The embodiments of this disclosure have now been described in detail. To avoid obscuring the concept of this disclosure, some details known in the art have not been described. Those skilled in the art can fully understand how to implement the technical solutions disclosed herein based on the above description.

[0175] While specific embodiments of this disclosure have been described in detail by way of examples, those skilled in the art should understand that the examples are for illustrative purposes only and not intended to limit the scope of this disclosure. Those skilled in the art should understand that modifications can be made to the above embodiments or equivalent substitutions can be made to some technical features without departing from the scope and spirit of this disclosure. The scope of this disclosure is defined by the appended claims.

Claims

1. A method for regulating the break-off voltage of a power device, characterized in that, include: Measure the actual breakover voltage of the power device; and Based on the actual breakover voltage, proton irradiation and annealing are performed on the power device to change the doping concentration of the buffer in the power device, thereby adjusting the actual breakover voltage of the power device.

2. The method according to claim 1, characterized in that, Performing proton irradiation on the power device includes: determining the process parameters of the proton irradiation treatment, the process parameters including: irradiation energy and irradiation dose.

3. The method according to claim 2, characterized in that, Determining the process parameters for the proton irradiation treatment includes: The irradiation depth is determined based on the depth of the buffer zone, wherein the irradiation depth is the depth of the center position of the Bragg peak formed by the proton irradiation treatment. The first and second edge depths of the Bragg peak are determined based on the irradiation depth and the doping depth value corresponding to the energy dissipation parameter of the proton irradiation system; and The irradiation energy is determined based on the first edge depth, the second edge depth, and the correspondence between the first edge depth, the second edge depth, and the irradiation energy.

4. The method according to claim 3, characterized in that: The depth of the first edge is y1-y2. The second edge depth is y1+y2. Where y1 is the irradiation depth and y2 is the doping depth value corresponding to the energy dissipation parameter.

5. The method according to claim 4, characterized in that, In determining the irradiation energy, the depth of the second edge is less than or equal to the depth of the boundary between the base region of the power device and the buffer zone, wherein the base region is the area adjacent to the buffer zone.

6. The method according to claim 2, characterized in that, Determining the process parameters for the proton irradiation treatment includes: The actual doping concentration of the buffer in the power device is calculated based on the actual breakover voltage, and the design value of the doping concentration of the buffer in the power device is calculated based on the design value of the breakover voltage of the power device. Calculate the absolute value of the difference between the designed doping concentration and the actual doping concentration; and The irradiation dose of the proton irradiation treatment is calculated based on the absolute value of the difference in doping concentration.

7. The method according to claim 6, characterized in that, The irradiation dose of the proton irradiation treatment for Where ΔN is the doping concentration difference, K T The doping coefficient is related to the substrate material of the power device and the annealing temperature of the annealing process.

8. The method according to claim 7, characterized in that, With the same substrate material, different annealing temperatures correspond to different doping coefficients.

9. The method according to claim 6, characterized in that, The actual doping concentration N′ in the buffer of the power device Dbuffer for Where U1 is the actual breakover voltage of the power device, ε s Let x be the dielectric constant of the substrate material of the power device, x1 be the width of the first region of the power device, x2 be the width of the buffer of the power device, E1 be the electric field strength at the boundary between the first region and the second region of the power device under the breakdown voltage, and q be the unit charge. The first region is located between the buffer and the second region, the conductivity type of the first region is the same as that of the buffer, and the conductivity type of the second region is opposite to that of the buffer.

10. The method according to claim 6, characterized in that, The design value N of the doping concentration in the buffer of the power device Dbuffer for Among them, U set ε is the design value for the breakover voltage of the power device. s Let x be the dielectric constant of the substrate material of the power device, x1 be the width of the first region of the power device, x2 be the width of the buffer of the power device, E1 be the electric field strength at the boundary between the first region and the second region of the power device under the breakdown voltage, and q be the unit charge. The first region is located between the buffer and the second region, the conductivity type of the first region is the same as that of the buffer, and the conductivity type of the second region is opposite to that of the buffer.

11. The method according to claim 9 or 10, characterized in that: The first region is a first base region, and the second region is a second base region; or The first region is the base region, and the second region is the collector region.

12. The method according to claim 1, characterized in that: The power device includes the buffer, a first region, and a second region, wherein the first region is located between the buffer and the second region; When the conductivity type of the buffer is n-type, the conductivity type of the first region is n-type, and the conductivity type of the second region is p-type, if the actual break-off voltage of the power device is less than the design value of the break-off voltage of the power device, the actual break-off voltage of the power device is increased by performing proton irradiation treatment and annealing treatment on the power device.

13. The method according to claim 1, characterized in that: The power device includes the buffer, a first region, and a second region, wherein the first region is located between the buffer and the second region; When the conductivity type of the buffer is p-type, the conductivity type of the first region is p-type, and the conductivity type of the second region is n-type, if the actual break-off voltage of the power device is greater than the design value of the break-off voltage of the power device, the actual break-off voltage of the power device is reduced by performing proton irradiation treatment and annealing treatment on the power device.

14. The method according to claim 1, characterized in that: The power device includes the buffer, a first region, and a second region, wherein the first region is located between the buffer and the second region, the conductivity type of the buffer is n-type, the conductivity type of the first region is n-type, and the conductivity type of the second region is p-type. The method further includes: During the measurement of the actual breakover voltage of the power device, a thermal imager is used to determine the location with the highest temperature in the buffer zone; this location with the highest temperature is the actual breakdown location within the buffer zone. If the actual breakdown location is not the predetermined breakdown location in the buffer, then proton irradiation and annealing are performed on the actual breakdown location in the buffer so that the breakover voltage at the actual breakdown location is greater than the breakover voltage at the predetermined breakdown location.

15. The method according to claim 1, characterized in that: The power device includes the buffer, a first region, and a second region, wherein the first region is located between the buffer and the second region, the conductivity type of the buffer is p-type, the conductivity type of the first region is p-type, and the conductivity type of the second region is n-type. The method further includes: During the measurement of the actual breakover voltage of the power device, a thermal imager is used to determine the location with the highest temperature in the buffer zone; this location with the highest temperature is the actual breakdown location within the buffer zone. If the actual breakdown location is not the predetermined breakdown location in the buffer, then proton irradiation and annealing are performed on the predetermined breakdown location in the buffer so that the breakover voltage at the predetermined breakdown location is less than the breakover voltage at the actual breakdown location.

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