Super junction transistor device

Abstract

A super junction transistor device is disclosed. The transistor device includes a semiconductor body, a plurality of transistor cells each at least partially integrated in the semiconductor body, a drain region of a first doping type arranged in the semiconductor body, a super junction region arranged in the semiconductor body and comprising a plurality of first regions of the first doping type and a plurality of second regions of a second doping type complementary to the first doping type. Each of the first regions and the second regions extends in a first direction between the transistor cells and the drain region, each first region comprises a first end section facing the drain region, and each second region comprises a second end section facing the drain region. In a pair of adjacent first region and second region, the first end section comprises a first effective amount of dopant atoms of the first type, and the second end section comprises a second effective amount of dopant atoms of the second type, wherein the second effective amount is at least 1.1 times the first effective amount.

Description

Technical Field

[0001] This disclosure generally relates to superjunction transistor devices, and more specifically, to silicon carbide (SiC) superjunction devices. Background Technology

[0002] A superjunction transistor device includes a superjunction region having a first doping type (conductivity type) and multiple first regions coupled to a drain node, and multiple second regions having a second doping type (conductivity type) complementary to the first doping type and coupled to a source node. The first regions are often referred to as drift regions, and the second regions are often referred to as compensation regions.

[0003] The superjunction transistor device also includes a transistor cell coupled between the source node and the superjunction region, wherein the transistor cell can operate in either a conduction state (on state) or a blocking state (off state). In the conduction state, the superjunction device is operated such that current can flow through the first region between the source node and the drain node. In the blocking state, the superjunction device is operated such that the pn junction between the first and second regions is reverse biased, causing the depletion region (space charge region) to extend in the first and second regions.

[0004] The voltage blocking capability of a superjunction transistor is limited by the maximum voltage that can be applied between the drain and source nodes without causing avalanche breakdown. The on-resistance of a superjunction transistor is the resistance between the source and drain nodes when the transistor is in the on-state. The on-resistance depends significantly on the resistance of the first region.

[0005] The on-resistance needs to be reduced without compromising the voltage blocking capability. Summary of the Invention

[0006] One example relates to a transistor device. The transistor device includes: a semiconductor body; a plurality of transistor cells, each transistor cell being at least partially integrated in the semiconductor body; a drain region of a first doped type disposed in the semiconductor body; and a superjunction region disposed in the semiconductor body and including a plurality of first regions of the first doped type and a plurality of second regions of a second doped type complementary to the first doped type. Each of the first and second regions extends between the transistor cell and the drain region in a first direction, each of the first regions including a first end segment facing the drain region, and each of the second regions including a second end segment facing the drain region. In a pair of adjacent first and second regions, the first end segment includes a first effective amount of first type dopant atoms, and the second end segment includes a second effective amount of second type dopant atoms, wherein the second effective amount is at least 1.1 times the first effective amount.

[0007] Another example relates to a transistor device. The transistor device includes: a semiconductor body; a plurality of transistor cells, each transistor cell being at least partially integrated in the semiconductor body; a drain region of a first doped type disposed in the semiconductor body; and a superjunction region disposed in the semiconductor body and including a plurality of first regions of the first doped type and a plurality of second regions of a second doped type complementary to the first doped type. Each of the first and second regions extends between the transistor cell and the drain region in a first direction, each of the first regions including a third end segment facing the transistor cell, and each of the second regions including a fourth end segment facing the transistor cell. In a pair of adjacent first and second regions, the third end segment includes a third effective amount of first-type dopant atoms, and the fourth end segment includes a fourth effective amount of second-type dopant atoms, wherein the fourth effective amount is at least 1.1 times the third effective amount. Attached Figure Description

[0008] The following explanations are based on the accompanying drawings. The drawings are intended to illustrate certain principles, showing only the aspects necessary for understanding these principles. The drawings are not drawn to scale. In the drawings, the same reference numerals denote the same features.

[0009] Figure 1 A vertical cross-sectional view of a superjunction device according to an example is shown, wherein the transistor device includes a superjunction having a first region and a second region and a plurality of transistor cells;

[0010] Figure 2 It shows according to Figure 1 Modification of transistor devices in the process;

[0011] Figures 3A-3B A transistor cell based on an example is shown;

[0012] Figures 4A-4B A transistor cell according to another example is shown;

[0013] Figures 5A-5D An example of a method for generating a superjunction region is shown;

[0014] Figures 6A-6B Another example of a method for generating a superjunction region is shown;

[0015] Figure 7 A pair of adjacent first and second regions of the superjunction region are shown in more detail;

[0016] Figure 8 The doping distribution of adjacent first and second regions is illustrated schematically according to an example;

[0017] Figure 9 It shows having, as Figure 8The electric field in the superjunction transistor device with the shown doping distribution;

[0018] Figure 10 A pair of adjacent first and second regions of the superjunction region are shown in more detail;

[0019] Figure 11 The doping distribution of adjacent first and second regions is illustrated schematically according to an example;

[0020] Figure 12 The doping distribution of the second region is schematically shown according to an example;

[0021] Figure 13 A schematic top view of a transistor device according to an example is shown;

[0022] Figure 14 A schematic top view of a transistor device according to another example is shown;

[0023] Figure 15 A schematic horizontal cross-sectional view of a transistor device according to an example is shown; and

[0024] Figure 16 A transistor device according to another example is illustrated schematically. Detailed Implementation

[0025] In the following detailed description, reference is made to the accompanying drawings. The drawings form part of the specification and, for illustrative purposes, illustrate examples of how the invention can be used and practiced. It should be understood that, unless otherwise specifically stated, features of the various embodiments described herein can be combined with each other.

[0026] Figure 1 and Figure 2 Each schematically illustrates a superjunction transistor device. More specifically, Figure 1 and Figure 2 Each of these schematically shows a cross-sectional view of a segment of the semiconductor body 100, in which the semiconductor region integrating the corresponding superjunction transistor device is located.

[0027] refer to Figure 1 and Figure 2 The transistor device includes a superjunction region 10 disposed in a semiconductor body 100, and includes a plurality of first regions 11 of a first doping type (conductivity type) and a plurality of second regions 12 of a second doping type (conductivity type) complementary to the first doping type. The first regions 11 and second regions 12 extend in a first direction z of the semiconductor body 100 and are alternately arranged in a second direction x of the semiconductor body 100. According to one example, the second direction x is perpendicular to the first direction z.

[0028] According to one example, the transistor device is a silicon carbide (SiC) transistor device. In this example, the semiconductor body 100 comprises single-crystal SiC. According to one example, the semiconductor body 100 comprises 6H polytype or 4H polytype SiC.

[0029] according to Figure 1 As shown in one example, adjacent first zone 11 and second zone 12 can be adjacent to each other. According to... Figure 2 In another example shown, adjacent first regions 11 and second regions 12 are spaced apart from each other in the second direction x. The region of the semiconductor body 100 disposed between the first regions 11 and the second regions 12 has a doping concentration lower than that of each of the first regions 11 and the second regions 12, for example, less than 0.2 (2E-1) times, less than 0.15 times, or less than 0.1 times the doping concentration of each of the first regions 11 and the second regions 12.

[0030] refer to Figure 1 and Figure 2 The transistor device also includes a drain region 13 of a first doped type electrically coupled to each first region 11. According to one example, the transistor device includes a buffer 14 of the first doped type, disposed between the superjunction region 10 and the drain region 13 and adjacent to both the superjunction region 10 having the first region 11 and the drain region 14 having the second region 12. In this example, the drain region 13 is electrically coupled to the first region 11 through the buffer 14. According to one example, the doping concentration of the buffer 14 is lower than the doping concentration of the drain region 13 and higher than the maximum doping concentration of the first region 11. According to another example (not shown), the drain region 13 is adjacent to the first region 11 for electrical coupling to the first region 11.

[0031] As an example, the doping concentration of buffer 14 is 1E15cm. -3 With 1E19cm -3 Between. Buffer 14 may have a lower doped portion and a higher doped portion disposed between the lower doped portion and drain region 13. The lower doped portion may have a diameter of 1E15cm. -3 With 1E17cm -3 The doping concentration can be within the range of 1E18cm, and the higher doping concentration can have a doping concentration of 1E18cm. -3 With 1E19cm -3 The doping concentration is within the range between [a certain value].

[0032] Optionally (and in) Figure 1 and Figure 2(Seen in dashed lines), the transistor device also includes a drift region 15. The drift region 15 is adjacent to the superjunction region 10 and disposed between the superjunction region 10 and the buffer region 14. Optionally, the drift region 15 has a first doping type and a doping concentration lower than that of the first region 11 and the drain region 13 of the superjunction region 10. According to one example, the doping concentration of the drift region 15 is lower than that of the buffer region 14. According to one example, the doping concentration of the drift region 15 is at 1E15cm⁻¹. -3 With 5E17cm -3 Within the range between, and the doping concentration of buffer 14 is at 1E17cm -3 With 1E19cm -3 Within the range between.

[0033] The total length of the superjunction region 10 and the drift region 15 essentially defines the voltage blocking capability of the transistor device. The total length is given by the sum of the length d10 of the superjunction region 10 and the length d15 of the drift region 15. The length of the superjunction region 10 is its dimension in the vertical z-direction, and the length d15 of the drift region 15 is its dimension in the vertical z-direction.

[0034] According to specific embodiments, the voltage blocking capability of the transistor device is, for example, between 650V and 6.5kV. In a SiC-based transistor device with a voltage blocking capability of 650V, the total length is, for example, between 4 micrometers (μm) and 6 micrometers; and in a SiC-based transistor device with a voltage blocking capability of 1.2kV, the total length is, for example, between 8 and 10 μm.

[0035] According to one example, the length d10 of the superjunction region 10 is between 30% and 70% of the total length (d10+d15) of the superjunction region 10 and the drift region 15.

[0036] Drain region 13 is connected to drain node D or the drain node D forming the transistor device. Furthermore, each second region 12 of the superjunction region 10 is connected to the source node S of the transistor device. The connection between the second region 12 and the source node S is only... Figure 1 and Figure 2 The diagram is schematically shown. An example of connecting the second region 12 to the source node S is further explained below. The drain node D and the source node S are circuit nodes or terminals of the transistor device, configured to receive the load path voltage and load current when the transistor device is operating. This is essentially known in superjunction transistor devices and therefore requires no further explanation.

[0037] refer to Figure 1 and Figure 2The transistor device also includes a plurality of transistor units 2. Each transistor unit 2 is coupled between the source node S and at least one first region 11 of the superjunction region 10. Furthermore, each transistor unit 2 is configured to control the conductive channel between the source node S and the corresponding first region 11. Figure 1 and Figure 2 Transistor unit 2 is not shown in detail. Instead, in Figure 1 and Figure 2 In this diagram, each transistor unit 2 is represented by an electronic switch with a parallel diode. A detailed example of transistor unit 2 is explained further below.

[0038] refer to Figure 1 and Figure 2 The drain region 13 is spaced apart from the transistor cell in the first direction z, wherein the superjunction region 10 is arranged between the transistor cell 2 and the drain region 13. Figure 1 and Figure 2 In the example shown, the transistor device is a vertical transistor device. In this type of transistor device, the drain region 13 is spaced apart from the transistor cell 2 in the vertical direction of the semiconductor body 100. Therefore, in Figure 1 and Figure 2 In the example shown, the first direction z is the vertical direction of the semiconductor body 100. The “vertical direction” of the semiconductor body 100 is a direction that is substantially perpendicular to the first and second (main) surfaces 101, 102 of the semiconductor body 100. According to one example, the transistor cell 2 is at least partially integrated in the semiconductor body 100 below the first surface 101, and the drain region 13 is arranged adjacent to the second surface 102.

[0039] exist Figure 1 and Figure 2 In the illustrated vertical transistor device, the second direction x is the direction in which the first region 11 and the second region 12 of the superjunction region 10 are arranged alternately. The second direction x is the lateral direction of the semiconductor body 100 and is referred to hereinafter as the first lateral direction. In the second lateral direction y, which is perpendicular to the first lateral direction x, the first region 11 and the second region 12 of the superjunction region 10 can be elongated. Examples of elongated first regions 11 and 12 are further explained below.

[0040] Transistor unit 2 can operate in either an ON (conducting) or OFF (blocking) state. The operating state of the transistor unit controls the operating state of the transistor device, ensuring that the transistor device is ON when the transistor unit is ON and OFF when the transistor unit is OFF. In the ON state, transistor unit 2 provides a conductive channel between the source node S and the first region 11. In the ON state, current can flow between the drain node D and the source node S via the drain region 13, the optional buffer 14, the first region 11 of the superjunction region 10, and the conductive channel provided by transistor unit 2. In the OFF state, transistor unit 2 interrupts the conductive channel between the source node S and the first region 11. In the OFF state, current flow between the drain node D and the source node S is blocked.

[0041] Typically, each transistor cell 2 includes an integrated diode that bypasses a conductive channel controlled by the corresponding transistor cell 2. When forward biased, these integrated diodes allow current to flow through the transistor device between the drain node D and the source node S, regardless of the operating state of the transistor cell 2. The operating state of the transistor device with the integrated diode turned on can be referred to as the diode state. As used herein, "on state" and "off state" refer to the operating states of the transistor device with the integrated diode reverse biased. That is, the drain-source voltage applied between the drain node D and the source node S in the on or off state has the opposite polarity to that which forward biases the integrated diode.

[0042] Each transistor unit 2 includes a gate electrode connected to the gate node G of the transistor device. Figure 1 (Not shown in detail). Transistor cell 2 is configured to operate in an on-state or off-state depending on the voltage applied between the gate node G and the source node S (gate-source voltage). More specifically, for example, transistor cell 2 is in the on-state when the gate-source voltage has a voltage level higher than the threshold voltage of the transistor device; and in the off-state, for example, when the gate-source voltage has a voltage level lower than the threshold voltage.

[0043] Figures 3A-3B A transistor cell based on an example is shown. More specifically, Figure 3A A vertical cross-sectional view of several transistor units 2 is shown, and Figure 3B Showing more details Figure 3A A transistor unit of the type shown. (Reference) Figures 3A-3BEach transistor cell includes: a source region 21 having a first doping type and connected to the source node S; a body region 22 having a second doping type and adjacent to the source region 21; and a gate electrode 23 adjacent to the body region 22 and dielectrically insulated from the semiconductor body 100 by a gate dielectric 24. The gate electrode 24 is connected to the gate node G and is conventionally configured to control a conductive channel in the body region 22 between the source region 21 and a corresponding first region 11 of the superjunction region 10. When the gate electrode 23 of the transistor cell 2 forms a conductive channel in the body region 22, the transistor device is in a conducting state; and when the conductive channel is interrupted, the transistor device is in a turning state. Figures 3A-3B The connection between gate electrode 23 and gate G is not shown. An example of connecting gate electrode 23 to gate node G is explained further below.

[0044] The gate electrode 23 is disposed in a trench extending from the first surface 101 into the semiconductor body 100. However, this is only an example. It is also possible to implement a transistor cell 2 having a planar gate electrode formed above the first surface 101.

[0045] refer to Figure 3A The source node S is formed by or connected to the source electrode 31. The source electrode 31 is formed above the first surface 101 of the semiconductor body 100, connected to the source region 21, and insulated from the gate electrode 23. Furthermore, according to one example, the body region 22 of each transistor cell 2 is connected to the source electrode 31. For this purpose, the source electrode 31 may include a conductive via 32 extending through the source region 21 to reach or enter the body region 22. The source electrode 31 comprises a conductive material, such as a metal or highly doped polysilicon.

[0046] Referring to the above, transistor cell 2 controls the conductive channel between the source region 21 and the first region 11 of the superjunction region 10. According to an example (not shown), the first region 11 of the superjunction region 10 is adjacent to the body region 22. Figures 3A-3B In another example shown, a current extension region 25 of the first doping type is arranged between the body region 22 and the first region 11. According to one example, the current extension region 25 has a higher doping concentration than the first region 11. According to another example, the current extension region 25 has substantially the same doping concentration as the first region 11, and may even have a lower doping concentration than the first region 11.

[0047] A PN junction is formed between body region 22 and current extension region 25 (or, alternatively, first region 11). These PN junctions form the integrated body diode of transistor unit 2. When the conductive channel in body region 22 is interrupted and a voltage is applied between drain node D and source node S (which reverse-biases the PN junction between current extension region 25 and body diode 22), the transistor device is in the off state.

[0048] According to one example, each transistor unit 2 also includes a second-doped shielding region 26 electrically connected to the source node S. Figures 3A-3B In the example shown, each shielding region 26 is adjacent to the body region 22 and connected to the source node S via the body region 22.

[0049] refer to Figure 3A The shielding region 26 and the current spreading region 25 are arranged alternately in the first lateral direction x. Furthermore, a PN junction is formed between each shielding region 26 and an adjacent current spreading region 25. The shielding region 26 and the current spreading region 25 form a JFET (Junction Field-Effect Transistor) structure that protects the gate dielectric 24 from high electric fields when the transistor device is in the off state. More specifically, when the transistor device is in the off state, the shielding region 26 coupled to the source node S depletes the charge carriers in the current spreading region 25 coupled to the drain node D via the first region 11. The depleted current spreading region 25 protects the gate dielectric 24 from high electric fields. According to one example, the doping concentration of the shielding region 26 is such that the shielding region 26 cannot completely deplete the charge carriers, such that when the transistor device is in the off state, at least a portion of the shielding region 26 has a potential substantially equal to the potential of the source node S.

[0050] Referring to the above, the second region 12 of the superjunction region 10 is electrically coupled to the source node S. In Figures 3A-3B In the example shown, each second region 12 is adjacent to the corresponding shielding region 26, such that each second region 12 is coupled to the source node S via the shielding region 26, and the body region 22 is adjacent to the shielding region 26.

[0051] exist Figures 3A-3B In the example shown, the gate electrodes 23 of two adjacent transistor cells 2 are formed by a common electrode, wherein the body region 22 of the respective transistor cell is adjacent to each of the two opposing trench sidewalls of each gate trench including the common electrode. Furthermore, in Figures 3A-3B In the example shown, the body regions 22 of the two transistor cells 2 are formed by a single doped region, the current extension regions 25 of the two adjacent transistor cells are formed by a single doped region, and each first region 11 of the superjunction region 10 is coupled to the source node S via the two adjacent transistor cells 2. However, implementing the transistor cells 2 in this way is merely an example. Another example of the transistor cells 2 is... Figures 4A-4B As shown in the image.

[0052] Figure 4A A vertical cross-sectional view of several transistor units 2 is shown, and Figure 4B It shows Figure 4A An enlarged view of one of the transistor cells of the type shown. Figures 4A-4BThe transistor unit 2 shown is... Figures 3A-3B The difference in the transistor cells shown is that each shielding region 26 extends downward from the first surface 101 along the first trench sidewall of the gate trench in which the gate electrode 23 is disposed to a corresponding second region 12 of the superjunction region 12. Furthermore, the body region 22 of the transistor cell 2 is adjacent only to the opposing second trench sidewall of the gate trench. In this example, the electrode formed in the gate trench forms the gate electrode 23 of only one transistor cell. Furthermore, each first region 11 is connected to the source node S only via one transistor cell of the transistor cell 2.

[0053] Transistor devices can be implemented as N-type or P-type transistor devices. In an N-type transistor device, the doped region of the first doping type is an N-type region, and the doped region of the second doping type is a P-type region. In a P-type transistor device, the doped region of the first doping type is a P-type region, and the doped region of the second doping type is an N-type region. Referring to the above, the transistor device is a SiC transistor device. For example, the N-type dopant in SiC is nitrogen (N), phosphorus (P), or arsenic (As) atoms. For example, the P-type dopant in SiC is boron (B), aluminum (Al), or gallium (Ga) atoms.

[0054] As an example, the doping concentration of source region 21 is higher than 1E19cm. -3 According to one example, the doping concentration of body region 22 is higher than 1E17cm. -3 .

[0055] For example, when the drain-source voltage is positive, an N-type transistor can operate in either the on or off state. When the drain-source voltage is negative, the N-type transistor is in diode mode.

[0056] Figures 5A-5D An example of a method for forming a superjunction region 10 having a first region 11 and a second region 12 is shown. Figures 5A-5D Each of these shows a cross-sectional view of a portion of the semiconductor body 100 during the manufacturing process.

[0057] refer to Figure 5AThe method includes providing a carrier on which a superjunction region 10 will be formed. According to one example, the carrier includes a first semiconductor layer 130 forming a drain region 13 in the finished device and a second semiconductor layer 140 forming a buffer 14 in the finished device, wherein the second semiconductor layer 140 is formed on top of the first semiconductor layer 130. According to one example, the first semiconductor layer 130 is a semiconductor substrate with a doping concentration equal to the desired doping concentration of the drain region 13, and the second semiconductor layer 140 is an epitaxial layer formed on top of the substrate during an epitaxial growth process. According to one example, the second semiconductor layer 140 is in-situ doped during the epitaxial growth process to obtain the desired doping concentration of the buffer 14. Referring to the foregoing, the buffer 14 may include two or more differently doped portions. This can be achieved by forming two or more epitaxial layers with different doping concentrations stacked layer by layer. Alternatively, the buffer 14 is formed based on a single semiconductor layer that is in-situ doped, such that the doping concentration is reduced during the epitaxial growth process.

[0058] The optional drift region 15 can be formed by another epitaxial layer grown on top of the epitaxial layer forming the buffer 14.

[0059] refer to Figure 5A The method further includes forming a third semiconductor layer 110 on top of the second semiconductor layer 140. According to one example, the third semiconductor layer 110 is intrinsic or has a thickness below 1E16 cm⁻¹. -3 The background doping concentration.

[0060] The method also includes forming a first region 11 and a second region 12 in the third semiconductor layer 110. (See reference...) Figure 5B Forming the first region 11 includes implanting first-type dopant atoms into the third semiconductor layer 110. (See reference...) Figure 5C Forming the second region 12 includes implanting second type dopant atoms into the third semiconductor layer 110.

[0061] refer to Figure 5BImplanting first-type dopant atoms involves using a first implantation mask 201, which covers a first portion of the surface of the third semiconductor layer 110, leaving a second portion of the surface uncovered. First-type dopant atoms are implanted into the surface of the third semiconductor layer 110 through the first implantation mask 201, such that the first-type dopant atoms are substantially implanted only into those segments of the surface not covered by the first implantation mask 201. The region of the third semiconductor layer 110 implanted with first-type dopant atoms is hereinafter referred to as the first implantation region 11'. The first implantation mask 201 defines the location and size of the first implantation region 11' in the lateral direction of the third semiconductor layer 110. The "lateral direction" of the third semiconductor layer 110 is a direction substantially perpendicular to the direction in which the first semiconductor layer 130, the second semiconductor layer 140, and the third semiconductor layer 110 are stacked layer by layer.

[0062] refer to Figure 5C Implanting second-type dopant atoms involves using a second implantation mask 202, which covers a third portion of the surface of the third semiconductor layer 110, leaving a fourth portion of the surface uncovered. (See reference...) Figure 5C Second type dopant atoms are implanted into the surface of the third semiconductor layer 110 through the second implantation mask 201, such that the second type dopant atoms are implanted essentially only into those sections of the surface not covered by the second implantation mask 202. The region of the third semiconductor layer 110 implanted with second type dopant atoms is hereinafter referred to as the second implantation region 11'. The second implantation mask 202 defines the position and size of the second implantation region 12' in the lateral direction of the third semiconductor layer 110.

[0063] According to one example, the portion of the third surface covered by the second injection mask 202 substantially corresponds to... Figure 5B The process shown involves implanting first-type dopant atoms into the second portion of the surface. Furthermore, the fourth surface portion not covered by the second implantation mask 202 substantially corresponds to the portion in... Figure 5B The first portion is covered during the implantation process shown. In this example, in the finished device, the first region 11 and the second region 12 are substantially adjacent to each other.

[0064] According to another example, the first injection mask 201 and the second injection mask 202 are formed such that the surface portion of the third semiconductor layer 110 is... Figure 5B The implantation process shown is for implanting first-type dopant atoms and Figure 5C The implantation process shown is covered in the implantation of second-type dopant atoms. In this example, the first region 11 and the second region 12 in the completed device are spaced apart from each other.

[0065] Figure 5BThe process of implanting first-type dopant atoms into the third semiconductor layer 110 can include only one implantation process, wherein the first-type dopant atoms are implanted using essentially only one implantation energy. According to another example, the process of implanting first-type dopant atoms includes two or more implantation processes using different implantation energies. Essentially, the higher the implantation energy, the deeper the dopant atoms are implanted into the third semiconductor layer 110.

[0066] Similarly, implanting second-type dopant atoms into Figure 5C The process in the third semiconductor layer 110 shown may include only one implantation process, wherein a second type of dopant atom is implanted using essentially only one implantation energy. According to another example, the process of implanting the second type of dopant atom includes two or more implantation processes using different implantation energies.

[0067] To form the first region 11 and the second region 12 based on the first implantation region 11' and the second implantation region 12', the method further includes an annealing process. In the annealing process, the implanted first and second type dopant atoms are activated. Figure 5D The diagram schematically illustrates the first semiconductor layer 130, the second semiconductor layer 140, and the third semiconductor layer 110 after an annealing process that forms the first region 11 and the second region 12 in the third semiconductor layer 110. It should be noted that the annealing process is not necessarily performed directly after the implantation of dopant atoms of the first and second types. Instead, the annealing process can be performed in subsequent stages, for example, after one or more additional epitaxial layers have been formed on top of the third layer 110 and after dopant atoms for forming the transistor unit 2 have been implanted.

[0068] Furthermore, it should be noted that in the SiC semiconductor body, the first and second type dopant atoms implanted during the annealing process essentially do not diffuse. Therefore, the size and location of the first region 11 and the second region 12 are essentially determined by the... Figure 5B and Figure 5C The dimensions and positions of the first injection region 11' and the second injection region 12' formed during the injection process are defined.

[0069] Forming the superjunction region 10 may include: (a) forming an epitaxial layer on top of the second layer 140; (b) in Figure 5B Implanting a first type of dopant in at least one implantation process of the type shown; and (c) in Figure 5C Second-type dopant atoms are implanted in at least one implantation process of the type shown. According to Figures 4A-6B In another example shown, forming the superjunction region 10 includes forming two or more epitaxial layers 1101-110 stacked layer by layer on top of the carriers 130, 140. N And with reference Figures 5B-5CThe same method is explained and in the formation of two or more epitaxial layers 1101-110 N The next step involves implanting type 1 and type 2 dopant atoms into two or more epitaxial layers 1101-110. N In each of them. For illustrative purposes only, Figures 6A-6B The diagram shows three epitaxial layers 1101-110 formed by stacking them layer by layer. N .

[0070] Figure 6A This illustrates the formation of epitaxial layers 1101-110 on the top of carriers 130 and 240. N Then, first and second type dopant atoms were implanted into the epitaxial layers 1101-110. N In each of the layers 1101-110, the epitaxial layer is used. N The apparatus following the formation of portions of the first and second injection regions 11', 12' in each of them. (See reference) Figure 6A The portion of the first region 11' can be formed by stacking layers one after another, and the portion of the second region 12' can be formed by stacking layers one after another, such that there are two or more epitaxial layers 1101-110 N The device includes a plurality of first injection regions 11' and a plurality of second injection regions 12' arranged alternately in a first lateral direction x.

[0071] In addition to forming Figure 6A In addition to the first and second injection regions 11' and 12' shown, the formation of the first region 11 and the second region 12 also includes an annealing process. Figure 6B The apparatus after the annealing process is shown, wherein the first implantation region 11 and the second implantation region 12 are formed based on the first implantation region 11' and the second implantation region 12'. It should be noted that in the finished semiconductor device, the respective epitaxial layers 1101-110... N There is no visible boundary between them. This is for illustrative purposes only. Figures 6A-6B The dashed lines in the middle indicate the various epitaxial layers 1101-110. N The boundary between them.

[0072] In the above example, forming the first region 11 includes at least one implantation process using at least one implantation mask, and forming the second region 12 includes at least one implantation process using at least one other implantation mask. However, this is merely an example. According to another example, one or more third semiconductor layers 110, 1101-110 N This is achieved by forming a background doping concentration corresponding to the desired doping concentration of the first region 11 (or the second region 12). In this example, this is achieved by implanting corresponding second-type (or first-type) dopant atoms into the third semiconductor layer 110, 1101-110. NThe second region 12 (or the first region 11) is formed in the middle, wherein a third semiconductor layer 110, 1101-110 is formed after at least one implantation process. N Those regions with the lowest background doping concentration form the first region 11 (or the second region 12).

[0073] Referring to the above, the first region 11 of the superjunction region 10 is electrically coupled to the drain region 13 and the drain node D, and the second region 12 is electrically coupled to the source node S. Since the first region 11 and the second region 12 are complementary doped regions, a PN junction is formed between the first region 11 and the second region 12. When the transistor device is in the off state and a drain-source voltage lower than the voltage blocking capability of the transistor device is applied between the drain node D and the source node S, a space charge region (depletion region) expands in the first region 11 and the second region 12 of the transistor device, and the dopant charge contained in the second region 12 compensates for the "dopant charge" in the first region 11. This makes it possible to achieve a first region 11 with a higher doping concentration than a transistor device with the same voltage blocking capability but without a second region (compensation region), thereby reducing the on-resistance of the transistor device containing the superjunction region compared to conventional transistor devices.

[0074] Typically, in a superjunction transistor device (which is a transistor device having a superjunction region 10), the first region 11 and the second region 12 of the superjunction region 10 are balanced. This includes the following: in a pair of two adjacent first regions 11 and second regions 12, each of the first region 11 and the second region 12 has substantially the same amount of dopant charge at each vertical location of the superjunction region 10. In this way, at each vertical location, the dopant charge (dopant atoms) contained in the first region 11 has a corresponding amount of dopant charge (dopant atoms) contained in the adjacent second region 12.

[0075] The first region 11 and the second region 12 of the superjunction region 10 are balanced, meaning that adjacent first regions 11 and second regions 12 have the same doping distribution in a first direction. In a vertical transistor device, the first direction corresponds to the vertical direction z of the semiconductor body 100.

[0076] However, some imbalance in the doping distribution may help to improve the voltage blocking capability for a given on-resistance, or reduce the on-resistance for a given voltage blocking capability. Adjacent first regions 11 and second regions 12 that do not have substantially the same doping distribution are referred to below as unbalanced first regions 11 and second regions 12.

[0077] The following is for reference. Figure 7 and Figure 8 An example to explain the imbalance between adjacent first zone 11 and second zone 12. Figure 7The diagram shows a vertical cross-sectional view of two adjacent first zones 11 and second zones 12, and... Figure 8 An example of the doping distribution of adjacent first region 11 and second region 12 is shown.

[0078] refer to Figure 1 The first region 11 and the second region 12 each include end sections 41 and 42 facing the drain region 13. Hereinafter, end section 41 of the first region 11 is referred to as the first end section 41, and the end section of the second region 12 is referred to as the second end section 42. Figure 7 In the example shown, the transistor device includes a buffer 14 between the drain region 13 and the superjunction region 10. In this example, a first end segment 41 and a second end segment 42 are each adjacent to the buffer 14. According to another example (not shown), the transistor device does not have a buffer 14. In this example, a first end segment 41 and a second end segment 42 are each adjacent to the drain region 13.

[0079] The first end segment 41 (which is the end segment of the first region 11) has a first effective amount N41 of first-type dopant atoms. The first end segment 41 may include a certain amount of second-type dopant atoms, wherein the amount of first-type dopant atoms is dominant. "Effective amount N41 of first-type dopant atoms" is the difference between the total amount of first-type dopant atoms and the total amount of second-type dopant atoms in the first end segment 41.

[0080] Similarly, the second end segment 42 (which is the end segment of the second region 12) has a second effective amount N42 of second-type dopant atoms. The second end segment 42 may include a certain amount of first-type dopant atoms, wherein the amount of second-type dopant atoms is dominant. "Effective amount N42 of second-type dopant atoms" is the difference between the total amount of second-type dopant atoms in the second end segment 42 and the total amount of first-type dopant atoms.

[0081] exist Figure 7 and Figure 8 In the superjunction region 10 shown, the doping distribution of the first region 11 and the second region 12 is unbalanced. In this example, the unbalanced doping distribution includes: the second effective amount N42 of the second type of dopant atoms in the second end segment 42 is at least 1.1 times the first effective amount N41 of the first type of dopant atoms in the first end segment 41.

[0082] N42>1.1∙N41 (1)

[0083] This ensures that the ratio between the second effective quantity N42 and the first effective quantity N41 is at least 1.1, where N42 / N41 ≥ 1.1. According to one example, this ratio is at least 1.2 or at least 1.5.

[0084] According to one example, the first end segment 41 and the second end segment 42 have at least approximately the same dimensions in a first direction of the semiconductor body, the first direction being... Figure 7 In the example shown, the direction is vertical (z). Therefore, d41 ≈ d42, where d41 represents the size of the first end segment 41 and d42 represents the size of the second end segment 42 in the first direction (z). In the first direction (z), the sizes d41 and d42 of the first and second end segments are, for example, in the range of 0.2 micrometers to 0.4 micrometers.

[0085] Furthermore, the first end segment 41 and the second end segment 42 may have at least approximately the same dimensions in a third direction perpendicular to the first direction z and the second direction x. Referring to the above, the second direction x is the direction in which the first segment 11 and the second segment 12 are arranged alternately, and therefore is the direction in which adjacent first segments 11 and second segments 12 are arranged adjacent to each other. Figure 7 In the example shown, the second direction is the first lateral direction x. Therefore, the third direction is the second lateral direction y.

[0086] In the second direction x, the first region 11 and the second region 12 can have the same dimensions. That is, the width w11 of the first region 11 can be equal to the width w12 of the second region 12. However, this is only an example. It is also possible to implement adjacent first regions 11 and second regions 12 with different widths w11 and w12. For example, the widths of the first region 11 and the second region 12 are selected from a range between 0.5 micrometers (μm) and 1 micrometer.

[0087] Figure 8 The doping distribution of adjacent first region 11 and second region 12 is shown. This doping distribution is unbalanced, such that the second end segment 42 has a second type of dopant atoms with a second effective amount N42, which is at least 1.1 times the first effective amount N41 of the first type of dopant atoms in the first end segment 41. Figure 8 In the diagram, curve p11 shows a specific effective amount of first-type dopant atoms at the vertical position between the first vertical position z0 and the second vertical position z1 in the first region 11, and curve p12 shows a specific effective amount of second-type dopant atoms at the vertical position between the first vertical position z0 and the second vertical position z1 in the second region 12.

[0088] The first vertical position z0 represents the location of the interface between the superjunction region 10 and the transistor cell, and the second vertical position z1 represents the location of the interface between the superjunction region 10 and the buffer region 14 or the drain region 13. The "specific effective quantity of first-type dopant atoms" is the effective quantity of first-type dopant atoms at a certain vertical position in the first region 11, and the "specific effective quantity of second-type dopant atoms" is the effective quantity of second-type dopant atoms at a certain vertical position in the second region 12. The first effective quantity of first-type dopant atoms in the first end segment 41 is given by the integral of the specific effective quantity of first-type dopant atoms over the dimension d41 of the first end segment 41 in the first direction z, and the second effective quantity of second-type dopant atoms in the second end segment 42 is given by the integral of the specific effective quantity of second-type dopant atoms over the dimension of the second end segment 42 in the first direction z.

[0089] from Figure 8 It can be seen that the specific effective amount of the first type of dopant atoms in the first region 11 indicated by distribution p11 and the specific amount of the second type of dopant atoms in the second region 12 indicated by distribution p12 can vary along the first direction z of the superjunction region 12. This variation in the effective amount of the first and second types of dopant atoms can be caused by a manufacturing process of the type explained earlier herein, wherein dopant atoms are implanted into at least one epitaxial layer in at least one implantation process. Figure 8 The doping distribution shown is based on an example where two semiconductor layers have been stacked one on top of the other and dopant atoms have been implanted into each of the two semiconductor layers at different implantation energies. According to one example, a first end segment 41 is formed by one implantation process, and a second end segment is formed by another implantation process. The imbalance in doping concentration between the first end segment and the second end segments 41, 42 can be achieved by appropriately adjusting the implantation dose in the two implantation processes.

[0090] The first end segment 41 has an adjacent first intermediate segment 51 in the first region 11, wherein the first intermediate segment 51 has at least approximately the same size as the first end segment 41 in the first direction z. According to one example, the first intermediate segment 51 has the same size as the first end segment 41 in every direction. That is, the first intermediate segment 51 has the same size as the first end segment 41 in the first direction (vertical direction) z, the second direction (first lateral direction) x, and the third direction (second lateral direction) y. The first intermediate segment 51 has an effective amount N51 of first-type dopant atoms.

[0091] Similarly, the second end segment 42 has an adjacent second intermediate segment 51 in the second direction 12, wherein the second intermediate segment 52 has at least approximately the same size as the second end segment 42 in the first direction z. According to one example, the second intermediate segment 52 has the same size as the second end segment 42 in every direction. That is, the second intermediate segment 52 has the same size as the second end segment 42 in the first direction z, the second direction x, and the third direction y. The second intermediate segment 52 has an effective amount N52 of second-type dopant atoms.

[0092] Referring to the above, the effective amount N42 of the second type of dopant atoms in the second end segment 42 is higher than the effective amount N41 of the first type of dopant atoms in the first end segment 41. Different examples exist regarding the relationship between the effective amount N42 of the second type of dopant atoms in the second end segment 42 and the effective amount N52 of the second type of dopant atoms in the second intermediate segment 52, and the relationship between the effective amount N41 of the first type of dopant atoms in the first end segment 41 and the effective amount N51 of the first type of dopant atoms in the first intermediate segment 51.

[0093] According to the first example, the effective amount N41 of the first type of dopant atoms in the first end segment 41 is at least approximately equal to the effective amount N51 of the first type of dopant atoms in the first intermediate segment 51, and the effective amount N42 of the second type of dopant atoms in the second end segment 42 is higher than the effective amount N52 of the second type of dopant atoms in the second intermediate segment 52, such that...

[0094] N41≈N51 (2a)

[0095] N42>N52 (2b).

[0096] According to the second example, the effective amount of first-type dopant atoms in the first end segment 41 is lower than the effective amount N51 of first-type dopant atoms in the first intermediate segment 51, and the effective amount N42 of second-type dopant atoms in the second end segment 42 is at least approximately equal to the effective amount N52 of second-type dopant atoms in the second intermediate segment 52, such that...

[0097] N41 <N51 (3a)

[0098] N42≈N52 (3b).

[0099] According to the third example, the effective amount of first-type dopant atoms in the first end segment 41 is higher than the effective amount N51 of first-type dopant atoms in the first intermediate segment 51, and the effective amount N42 of second-type dopant atoms in the second end segment 42 is higher than the effective amount of second-type dopant atoms in the second intermediate segment 52, such that...

[0100] N41>N51 (4a)

[0101] N42>N52 (4b).

[0102] In each example, the effective amount N51 of the first type of dopant atoms in the first intermediate segment 51 is at least approximately equal to the effective amount N52 of the second type of dopant atoms in the second intermediate segment 52, such that

[0103] N51≈N52 (5).

[0104] When the transistor device is in the off state, the increased doping in the second end section 42 compared to the first end section 41 causes an increase in the peak value of the electric field in the second region 12 of the superjunction region 10. This increased peak value of the electric field results in increased voltage blocking capability without increasing the on-resistance. Figure 9 The diagram shows the electric fields in the first region 11 and the second region 12 when the transistor device is in the off state.

[0105] exist Figure 9 In the diagram, when the transistor device is in the off state, curve E11 shows the magnitude of the electric field |E| in the first region 11, and curve E12 shows the magnitude of the electric field |E| in the second region 12. From Figure 9 It can be seen that the electric field in the second region 12 has a peak value. Basically, the greater the imbalance in the doping distribution, that is, the greater the effective amount N42 of the second type of dopant atoms in the second end section 42 relative to the effective amount N41 of the first type of dopant atoms in the first end section 41, the higher the peak value of the electric field in the second region 12, and the greater the increase in voltage blocking capability.

[0106] The following is for reference. Figure 10 and Figure 11 Another example to explain the imbalance between adjacent first zone 11 and second zone 12. Figure 10 The diagram shows a vertical cross-sectional view of two adjacent first zones 11 and second zones 12, and... Figure 11 An example of the doping distribution of adjacent first region 11 and second region 12 is shown. Figure 10 The optional drift region is not shown.

[0107] refer to Figure 1 Each of the first region 11 and the second region 12 includes a transistor-oriented unit 2 ( Figure 10(Not shown in the diagram) and the end segments 43 and 44 are away from the drain region 13. In the following text, the end segment 43 of the first region 11 is referred to as the third end segment 43, and the end segment 44 of the second region 12 is referred to as the fourth end segment 44. The third end segment 43 has a third effective amount of N43 of first-type dopant atoms, and the fourth end segment 44 has a fourth effective amount of second-type dopant atoms.

[0108] exist Figure 10 and Figure 11 In the superjunction region 10 shown, the doping distribution in the first region 11 and the second region 12 is unbalanced. In this example, the unbalanced doping distribution includes: the fourth effective amount N44 of the second type dopant atoms in the fourth end segment 44 is at least 1.1 times the first effective amount N43 of the first type dopant atoms in the third end segment 43.

[0109] N44≥1.1∙N43 (6)

[0110] This ensures that the ratio between the fourth effective quantity N44 and the third effective quantity N43 is at least 1.1, with N44 / N43 ≥ 1.1. According to one example, this ratio is at least 1.2 or at least 1.4.

[0111] According to one example, the third end segment 43 and the fourth end segment 44 have at least approximately the same dimensions in a first direction of the semiconductor body, the first direction being... Figure 10 The example shown is in the vertical direction z. Furthermore, the third end segment 43 and the fourth end segment 44 may have at least approximately the same size in the third direction, which is in... Figure 10 The example shown is in the second lateral direction y. In the first direction z, the dimensions d43 and d44 of the third and fourth end segments are, for example, in the range of 0.2 micrometers to 0.4 micrometers.

[0112] The size of the superjunction region 1 in the first direction depends on the desired voltage blocking capability of the device, and is, for example, in the range of 4 micrometers to 50 micrometers.

[0113] Figure 11 The doping distribution of adjacent first regions 11 and second regions 12 is shown, which is unbalanced, such that the fourth end segment 44 has a fourth effective amount N44 of second-type dopant atoms, the fourth effective amount N44 being at least 1.1 times the third effective amount N43 of the first-type dopant atoms in the third end segment 43. Figure 11In the diagram, curve p11 shows a specific effective amount of first-type dopant atoms at a vertical position starting from the first vertical position z0 in the first region 11, and curve p12 shows a specific effective amount of second-type dopant atoms at a vertical position starting from the first vertical position z0 in the second region 12. The first vertical position z0 represents the location of the interface between the superjunction region 10 and the transistor unit 2. "Specific effective amount of first-type dopant atoms" refers to the effective amount of first-type dopant atoms at a certain vertical position in the first region 11, and "specific effective amount of second-type dopant atoms" refers to the effective amount of second-type dopant atoms at a certain vertical position in the second region 12.

[0114] The third effective quantity N43 of the first type of dopant atoms in the third end segment 43 is given by the integral of the specific effective quantity of the first type of dopant atoms in the third end segment 43 over the dimension d43 in the first direction z, and the fourth effective quantity N44 of the second type of dopant atoms in the fourth end segment 44 is given by the integral of the specific effective quantity of the second type of dopant atoms in the dimension d44 in the first direction z.

[0115] The increase in the amount of second-type dopant atoms in the fourth end segment 44 compared to the amount of first-type dopant atoms in the third end segment 43 can be achieved by injecting a higher dose of second-type dopant atoms into the fourth end segment 44 compared to the dose of first-type dopant atoms injected into the third end segment 43.

[0116] The third end segment 43 has an adjacent third intermediate segment 53 in the first region 11, wherein the third intermediate segment 53 has at least approximately the same size as the third end segment 43. That is, the third intermediate segment 53 has the same size as the third end segment 43 in the first direction (vertical direction) z, the second direction (first lateral direction) x, and the third direction (second lateral direction) y. The third intermediate segment 53 has an effective amount N53 of first-type dopant atoms. Similarly, the fourth end segment 44 has an adjacent fourth intermediate segment 54 in the second region 12, wherein the fourth intermediate segment 54 has at least approximately the same size as the fourth end segment 44. That is, the fourth intermediate segment 54 has the same size as the fourth end segment 44 in the first direction z, the second direction x, and the third direction y. The fourth intermediate segment 54 has an effective amount N54 of second-type dopant atoms.

[0117] Referring to the above, the effective amount N44 of the second type dopant atoms in the fourth end segment 44 is higher than the effective amount N43 of the first type dopant atoms in the third end segment 43. According to one example, the effective amount N43 of the first type dopant atoms in the third end segment 43 is at least approximately equal to the effective amount N53 of the first type dopant atoms in the third intermediate segment 53, and the effective amount N44 of the second type dopant atoms in the fourth end segment 44 is higher than the effective amount N54 of the second type dopant atoms in the fourth intermediate segment 54, such that...

[0118] N43≈N53 (7a)

[0119] N44>N54 (7b).

[0120] In this example, the doping in the second region 12 is locally increased in the fourth end segment 44, while the doping in the first region 11 is not increased in the third end segment 43.

[0121] The localized increase in doping in the fourth end segment 44 of the third region 12 allows for an increase in the doping concentration of the current extension region 25 of the transistor cell without reducing the voltage blocking capability of the transistor device. However, increasing the doping concentration of the current extension region 25 reduces the on-resistance of the transistor device.

[0122] According to one example, the transistor device includes the two types of imbalance explained earlier herein. In this example, adjacent first region 11 and second region 12: (a) include a first end segment 41 and a second end segment 42, wherein the second end segment 42 has an effective amount of dopant atoms higher than the first end segment 41; and (b) include a third end segment 43 and a fourth end segment 44, wherein the fourth end segment 42 has an effective amount of dopant atoms higher than the third end segment 43. Figure 12 The effective amount of second-type dopant atoms in the second region 12 according to this example is shown.

[0123] Referring to the above, the gate electrode 23 of the transistor cell is connected to the gate node G of the transistor device. Figure 13 An example is shown for connecting the gate electrode 23 of a transistor cell to the gate node G.

[0124] Figure 13 A top view of a vertical transistor device according to an example is shown. More specifically, Figure 13A top view of the first surface 101 of the semiconductor body 100 is shown, wherein a source electrode 31 is disposed above the first surface 101. In addition to the source electrode 31, the transistor device also includes a gate pad 33 disposed above the first surface 101 of the semiconductor body 100 and at least one gate trace 34, wherein the at least one gate trace 34 is connected to the gate pad 33. The gate pad 33 forms a gate node G or is connected to a gate node G of the transistor device.

[0125] The transistor cell with gate electrode 23 is arranged below the first surface 101, and can be configured according to... Figures 4A-4B or Figures 5A-5B Implemented using any of the examples shown. For illustrative purposes, the location of the gate electrode of some transistor cells is... Figure 13 The middle part is represented by a thick line.

[0126] from Figure 13 It can be seen that the gate electrode 23 protrudes from the source electrode 31 and extends below the gate trace 34 in the second lateral direction y. Figure 13 In the example shown, gate electrode 23 protrudes from source electrode 31 at its opposite end, such that each of the two opposite longitudinal ends of each gate electrode 23 lies below a corresponding gate trace of the two gate traces 34. Furthermore, each longitudinal end of each longitudinal gate electrode 23 is connected to a corresponding gate trace 34. Figure 13 The connection between gate electrode 23 and gate trace 34 is not shown. Such a connection may include a conductive via extending down from gate trace 34 to gate electrode 23.

[0127] It should be noted that implementing a transistor device with two gate traces 34 such that each longitudinal end of each gate electrode 23 is connected to the corresponding gate trace 34 is merely an example. According to another example (not shown), the transistor device includes only one gate trace 34 such that only one longitudinal end of each gate electrode 23 is connected to the gate trace 34.

[0128] exist Figure 13 In the example shown, the gate pad 33 is located essentially in the middle between the two gate traces 34. However, this is just an example.

[0129] according to Figure 14 In another example shown, the gate pad 33 can be arranged substantially in one corner of the semiconductor body 100, and thus can be at a distance from one of the two gate traces 34 less than at the other of the two gate traces 34.

[0130] Figure 15A schematic horizontal cross-sectional view of the semiconductor body 100 of a vertical transistor device of the type explained earlier herein is shown. Reference Figure 15 The semiconductor body 100 includes an inner region 110 and an edge region 120, wherein the edge region 120 surrounds the inner region 110 in the lateral direction. Transistor unit 2 (in...) Figure 15 (Not shown in the image) is integrated in the internal region 110 of the semiconductor body 100. Furthermore, the source electrode 31 (in...) Figure 15 (Not shown in the image) is basically arranged above the internal region 110. Gate pad 33 and at least one gate trace 34 (in...) Figure 15 (Not shown in the image) can be arranged above the edge area 120.

[0131] According to one example, first and second end segments 41, 42 and / or third and fourth end segments 43, 44 with unbalanced doping are arranged in the inner region 110 of the transistor device. A portion of the superjunction region 10 may also be arranged in the edge region 120. According to one example, the first and second regions 11 and 12 of the superjunction region 10 arranged in the edge region 120 are balanced with respect to their doping. That is, adjacent first regions 11 and second regions 12 arranged in the edge region 120 may have substantially the same doping distribution.

[0132] In the example explained earlier in this document, the transistor device was a vertical transistor device, in which transistor cell 2 and drain region 13 are spaced apart from each other in the vertical direction z of semiconductor body 100. However, a transistor device with a superjunction region 10 having an unbalanced first region 11 and second region 12 is not limited to being implemented as a vertical transistor device. Instead, the transistor device may also be implemented as a lateral transistor device, in which transistor cell 2 and drain region 13 are spaced apart from each other in the lateral direction (e.g., the first lateral direction x) of semiconductor body 100. Figure 16 An example of a lateral transistor device is shown schematically.

[0133] The examples below, with their reference numbers, briefly outline some of the aspects explained above.

[0134] Example 1. A transistor device comprising: a semiconductor body; a plurality of transistor cells, each transistor cell being at least partially integrated in the semiconductor body; a drain region of a first doped type disposed in the semiconductor body; a superjunction region disposed in the semiconductor body and comprising a plurality of first regions of the first doped type and a plurality of second regions of a second doped type complementary to the first doped type, wherein each of the first and second regions extends in a first direction between the transistor cells and the drain region, wherein each of the first regions includes a first end segment facing the drain region, wherein each of the second regions includes a second end segment facing the drain region, wherein in a pair of adjacent first and second regions, the first end segment includes a first effective amount of first type dopant atoms, and the second end segment includes a second effective amount of second type dopant atoms, and wherein the second effective amount is at least 1.1 times the first effective amount.

[0135] Example 2. According to the transistor device of Example 1, the second effective quantity is at least 1.2 times or at least 1.5 times the first effective quantity.

[0136] Example 3. A transistor device according to Example 1 or 2, wherein the dimension of each of the first end segment and the second end segment in a first direction is between 0.2 micrometers and 0.4 micrometers.

[0137] Example 4. A transistor device according to any one of Examples 1 to 3, wherein, in a pair of first regions and second regions, the first region includes a first intermediate segment adjacent to a first end segment and having substantially the same dimensions as the first end segment in a first direction, and wherein the first end segment includes a first type of dopant atoms in an effective amount higher than that of the first intermediate segment.

[0138] Example 5. A transistor device according to any one of Examples 1 to 3, wherein, in a pair of first regions and second regions, the first region includes a first intermediate segment adjacent to a first end segment and having substantially the same dimensions as the first end segment in a first direction, and wherein the first end segment includes an effective amount of at least approximately the same type of dopant atoms as the first intermediate segment.

[0139] Example 6. A transistor device according to any one of Examples 1 to 3, wherein, in a pair of first regions and second regions, the first region includes a first intermediate segment adjacent to a first end segment and having substantially the same dimensions as the first end segment in a first direction, and wherein the first end segment includes a first type of dopant atoms in an effective amount lower than that of the first intermediate segment.

[0140] Example 7. A transistor device according to any one of Examples 1 to 6, wherein, in a pair of first and second regions, the second region includes a second intermediate segment adjacent to a second end segment and having substantially the same dimensions as the second end segment in a first direction, and wherein the second end segment includes a second type of dopant atoms in an effective amount higher than that of the second intermediate segment.

[0141] Example 8. A transistor device according to any one of Examples 1 to 6, wherein, in a pair of first and second regions, the second region includes a second intermediate segment adjacent to a second end segment and having substantially the same dimensions as the second end segment in a first direction, and wherein the second end segment includes an effective amount of at least approximately the same type of dopant atoms as the second intermediate segment.

[0142] Example 9. A transistor device according to any one of Examples 4 to 8, wherein the effective amount of a first type of dopant atoms in the first intermediate segment is at least approximately equal to the effective amount of a second type of dopant atoms in the second intermediate segment.

[0143] Example 10. A transistor device according to any one of Examples 1 to 9, wherein each of the first regions includes a third end segment facing the transistor cell, wherein each of the second regions includes a fourth end segment facing the transistor cell, wherein in a pair of adjacent first and second regions, the third end segment includes a third effective amount of first type dopant atoms, and the fourth end segment includes a fourth effective amount of second type dopant atoms, wherein the fourth effective amount is at least 1.1 times the third effective amount.

[0144] Example 11. According to the transistor device of Example 10, the fourth effective quantity is at least 1.2 times or at least 1.4 times the third effective quantity.

[0145] Example 12. A transistor device comprising: a semiconductor body; a plurality of transistor cells, each transistor cell being at least partially integrated in the semiconductor body; a drain region of a first doped type disposed in the semiconductor body; a superjunction region disposed in the semiconductor body and comprising a plurality of first regions of the first doped type and a plurality of second regions of a second doped type complementary to the first doped type, wherein each of the first and second regions extends in a first direction between the transistor cell and the drain region, wherein each of the first regions includes a third end segment facing the transistor cell, wherein each of the second regions includes a fourth end segment facing the transistor cell, wherein in a pair of adjacent first and second regions, the third end segment includes a third effective amount of first type dopant atoms, and the fourth end segment includes a fourth effective amount of second type dopant atoms, and wherein the fourth effective amount is at least 1.1 times the third effective amount.

[0146] Example 13. A transistor device according to Example 12, wherein the fourth effective quantity is at least 1.2 times or at least 1.4 times the third effective quantity.

[0147] Example 14. A transistor device according to Example 12 or 13, wherein the dimension of each of the third end segment and the fourth end segment in a first direction is between 0.2 micrometers and 0.4 micrometers.

[0148] Example 15. A transistor device according to any one of Examples 12 to 14, wherein, in a pair of first regions and second regions, the first region includes a third intermediate segment adjacent to a third end segment and having substantially the same dimensions as the third end segment in a first direction, and wherein the third end segment includes an effective amount of first type dopant atoms at least approximately the same as the third intermediate segment.

[0149] Example 16. A transistor device according to any one of Examples 10 to 13, wherein, in a pair of first and second regions, the second region includes a fourth intermediate segment adjacent to a fourth end segment and having substantially the same dimensions as the fourth end segment in a first direction, and wherein the fourth end segment includes a higher effective amount of a second type of dopant atoms than the fourth intermediate segment.

[0150] Example 17. A transistor device according to any one of Examples 1 to 16, wherein each transistor cell includes: a source region of a first doped type; a body region of a second doped type; a current spreading region of the first doped type; and a gate electrode arranged adjacent to the body region and dielectrically insulated from the body region by a gate dielectric, wherein the body region is arranged between the source region and the current spreading region, and wherein the current spreading region is adjacent to at least one first region of the superjunction region.

[0151] Example 18. A transistor device according to any one of Examples 1 to 17, wherein the semiconductor body comprises single-crystal SiC.

[0152] Example 19. A transistor device according to any one of Examples 1 to 18 further includes: a drift region of a first doping type, the drift region being adjacent to the superjunction region and disposed between the superjunction region and the drain region.

[0153] Example 20. A transistor device according to Example 19, wherein the length of the superjunction region is between 30% and 70% of the total length of the superjunction region and the drift region.

Claims

1. A transistor device, comprising: Semiconductor body (100); A plurality of transistor units (2), each of which is at least partially integrated in the semiconductor body (100); A first doped drain region (13) is arranged in the semiconductor body (100); A superjunction region (10) is disposed in the semiconductor body (100) and includes a plurality of first regions (11) of a first doping type and a plurality of second regions (12) of a second doping type complementary to the first doping type. Each of the first region (11) and the second region (12) extends in a first direction (z; x) between the transistor unit (2) and the drain region (13). Each of the first regions (11) includes a first end section (41) facing the drain region (13). Each of the second regions (12) includes a second end segment (42) facing the drain region (13). In a pair of adjacent first regions (11) and second regions (12), the first end segment (41) includes a first effective amount (N41) of first-type dopant atoms, and the second end segment (43) includes a second effective amount (N42) of second-type dopant atoms. The second effective amount is at least 1.1 times the first effective amount.

2. The transistor device according to claim 1, in, The second effective amount (N42) is at least 1.2 times or at least 1.5 times the first effective amount (N41).

3. The transistor device according to claim 1 or 2, in, The dimensions of each of the first end segment (41) and the second end segment (42) in the first direction (z; x) are between 0.2 micrometers and 0.4 micrometers.

4. The transistor device according to any one of claims 1 to 3, in, In the pair of first regions (11) and second regions (12), the first region (11) includes a first intermediate segment (51) that is adjacent to the first end segment (41) and has substantially the same dimensions as the first end segment (41) in the first direction (z; x). The first end segment (41) includes a first type of dopant atoms in an effective amount higher than that in the first middle segment (51).

5. The transistor device according to any one of claims 1 to 3, in, In the pair of first regions (11) and second regions (12), the first region (11) includes a first intermediate segment (51) that is adjacent to the first end segment (41) and has substantially the same dimensions as the first end segment (41) in the first direction (z; x). The first end segment (41) includes an effective amount of at least approximately the same type of first dopant atoms as the first middle segment (51).

6. The transistor device according to any one of claims 1 to 3, in, In the pair of first regions (11) and second regions (12), the first region (11) includes a first intermediate segment (51) that is adjacent to the first end segment (41) and has substantially the same dimensions as the first end segment (41) in the first direction (z; x). The first end segment (41) includes a first type of dopant atoms in an effective amount lower than that in the first middle segment (51).

7. The transistor device according to any one of claims 1 to 6, in, In the pair of first regions (11) and second regions (12), the second region (12) includes a second intermediate segment (52) that is adjacent to the second end segment (42) and has substantially the same dimensions as the second end segment (42) in the first direction (z; x). The second end segment (42) includes a second type of dopant atoms in a higher effective amount than the second middle segment (51).

8. The transistor device according to any one of claims 1 to 6, in, In the pair of first regions (11) and second regions (12), the second region (12) includes a second intermediate segment (52) that is adjacent to the second end segment (42) and has substantially the same dimensions as the second end segment (42) in the first direction (z; x). The second end segment (42) includes an effective amount of at least approximately the same type of dopant atoms as the second intermediate segment (51).

9. The transistor device according to any one of claims 4 to 8, in, The effective amount (N51) of the first type of dopant atoms in the first intermediate segment (51) is at least approximately equal to the effective amount (N52) of the second type of dopant atoms in the second intermediate segment (52).

10. The transistor device according to any one of claims 1 to 9, in, Each of the first regions (11) includes a third end segment (43) facing the transistor unit (2). Each of the second regions (12) includes a fourth end segment (44) facing the transistor unit (2). In a pair of adjacent first regions (11) and second regions (12), the third end segment (43) includes a third effective amount (N43) of first-type dopant atoms, and the fourth end segment (44) includes a fourth effective amount (N44) of second-type dopant atoms. The fourth effective quantity (N44) is at least 1.1 times the third effective quantity (N43).

11. The transistor device according to claim 10, in, The fourth effective amount is at least 1.2 times or at least 1.4 times the third effective amount.

12. A transistor device, comprising: Semiconductor body (100); A plurality of transistor units (2), each of which is at least partially integrated in the semiconductor body (100); A first doped drain region (13) is arranged in the semiconductor body (100); A superjunction region (10) is disposed in the semiconductor body (100) and includes a plurality of first regions (11) of a first doping type and a plurality of second regions of a second doping type complementary to the first doping type. Each of the first region (11) and the second region (12) extends in a first direction (z; x) between the transistor unit (2) and the drain region (13). Each of the first regions (11) includes a third end segment (43) facing the transistor unit (2). Each of the second regions (12) includes a fourth end segment (44) facing the transistor unit (2). In a pair of adjacent first regions (11) and second regions (12), the third end segment (43) includes a third effective amount (N43) of first-type dopant atoms, and the fourth end segment (44) includes a fourth effective amount (N44) of second-type dopant atoms. The fourth effective quantity (N44) is at least 1.1 times the third effective quantity (N43).

13. The transistor device according to claim 12, in, The fourth effective amount (N44) is at least 1.2 times or at least 1.4 times the third effective amount (N43).

14. The transistor device according to claim 12 or 13, in, The dimensions of each of the third end segment (43) and the fourth end segment (44) in the first direction are between 0.2 micrometers and 0.4 micrometers.

15. The transistor device according to any one of claims 12 to 14, in, In the pair of first regions (11) and second regions (12), the first region (11) includes a third intermediate segment (53), which is adjacent to the third end segment (43) and has substantially the same dimensions as the third end segment (43) in the first direction (z; x). The third end segment (43) includes an effective amount of first type dopant atoms that is at least approximately the same as that of the third intermediate segment (53).

16. The transistor device according to any one of claims 10 to 13, in, In the pair of first regions (11) and second regions (12), the second region (12) includes a fourth intermediate segment (54), which is adjacent to the fourth end segment (44) and has substantially the same dimensions as the fourth end segment (44) in the first direction. The fourth end segment (44) includes a second type of dopant atoms in an effective amount higher than that in the fourth intermediate segment (54).

17. The transistor device according to any one of claims 1 to 16, in, Each transistor unit (2) includes: The source region of the first doping type (21); The second type of doped body region (22); The first doped type of current extension region (25); and A gate electrode (23) is arranged adjacent to the body region (22) and dielectrically insulated from the body region (22) by a gate dielectric (24). The body region (22) is arranged between the source region (21) and the current extension region (25), and The current extension region (25) is adjacent to at least one first region (11) of the superjunction region (10).

18. The transistor device according to any one of claims 1 to 17, in, The semiconductor body (100) comprises single-crystal SiC.

19. The transistor device according to any one of the preceding claims, further comprising: The first doped type of drift region (15) is adjacent to the superjunction region (10) and is arranged between the superjunction region (10) and the drain region (13).

20. The transistor device according to claim 19, in, The length (d10) of the superjunction region (10) is between 30% and 70% of the total length of the superjunction region (10) and the drift region (15).

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