Semiconductor devices and methods for manufacturing them

Abstract

Semiconductor device (100; 200; 300; 400; 500), comprising: a semiconductor body (102) with a first principal surface (101); and a trench (110) formed in the semiconductor body (102), wherein the trench (110) extends from the first main surface (101) into the semiconductor body (102) along a first direction (z), wherein the trench comprises a field electrode (124) and a field dielectric (126), wherein the trench (110) has an upper area (110 u ), a lower range (110 l ) and an intermediate range (110 i )) includes, which between the upper area (110 u ) and the lower range (110 l ) is arranged, where the intermediate range (110 i )) is arranged between a first distance (d1) from the first main surface (101) and a second distance (d2) from the first main surface (101), where the difference between the second distance (d2) and the first distance (d1) along the first direction (z) is at most 20% of a total height (h) fp ) of the field electrode (124) is, wherein the field electrode (124) is separated from the upper area (110) u ) into the lower range (110 l ) of the trench (110) and the field electrode (124) extends at least between the first distance (d1) from the first main surface (101) and the second distance (d2) from the first main surface (101), wherein the field dielectric (126) is arranged between the field electrode (124) and the semiconductor body (102), wherein a thickness (t) of the field dielectric (124) increases along the first direction (z) from a first thickness (t1) at the first distance (d1) from the first main surface (101) to a second thickness (t2) at the second distance (d2) from the first main surface (101), where the second thickness (t2) is at least 1.1 times the first thickness (t1), wherein the semiconductor body (102) comprises a drift region (106), wherein the drift region (106) comprises a doping profile (1000) along the first direction (z), wherein a slope of the doping profile (1000) changes along the first direction between the first distance (d1) and the second distance (d2) from the first main surface (101), where the slope (S1) of the doping profile (1000) at the first distance (d1) is greater than the slope (S2) of the doping profile (1000) at the second distance (d2).

Description

BACKGROUND

[0001] Transistor devices used in power electronics applications are frequently fabricated using silicon (Si) semiconductor materials. Common transistor devices for power applications include Si cool MOSOs, Si power MOSFETs, and Si insulated-gate bipolar transistors (IGBTs).

[0002] A transistor device for power applications can be based on the charge compensation principle and can comprise an active cell field containing a plurality of trenches, each containing a field electrode for charge compensation. In some embodiments, the trenches and the mesas formed between adjacent trenches each have an elongated striped structure. In some other embodiments, the trenches and the field electrodes each have a columnar, needle-like shape.

[0003] Further improvements would be desirable to further enhance the performance of transistor devices, for example by reducing the on-resistance RDS(on)*Area or by improving other quality factors such as Rds(on)*Qg and Rds(on)*Qgd.

[0004] US 2022 / 0013665A1 discloses a vertical power semiconductor transistor device comprising a drift region and a drain region of a first conductivity type, and a body region of a second conductivity type. The drift region has a generally linearly graduated first doping profile that increases from the body region to the bottom of a trench containing a field electrode, and a graduated second doping profile that increases from one end of the first doping profile toward the drain region at a higher rate than the first doping profile.

[0005] US 2022 / 0262946A1 discloses a power device with a field electrode formed in a field electrode trench extending vertically into the drift region. The field electrode comprises a first and a second field electrode structure. The first field electrode structure is capacitively coupled to a first section of the drift region, and the second field electrode structure is capacitively coupled to a second section of the drift region, which is arranged vertically above the first section.

[0006] US 2022 / 0384587A1 discloses a semiconductor device comprising at least one first and one second electrode. The first electrode has several successive sections in a first direction. The several sections comprise a first section having a first width in a second direction, a second section located closer to the second electrode in the first direction than the first section and having a second width smaller than the first width in the second direction, and a third section adjacent to the second section, located closer to the second electrode than the second section in the first direction, and having a third width larger than the second width in the second direction.

[0007] EP 4 443 512 A1, published after the filing date of the present disclosure, discloses a transistor device comprising a semiconductor substrate with a first main surface and one or more transistor cells. The transistor cells comprise a columnar trench formed in the semiconductor substrate, a columnar field plate arranged in the columnar trench, and a mesa arranged around the columnar trench. The columnar trench consists of a field dielectric, a base, and a side wall. The side wall extends from the base to the first main surface, and the field dielectric lines the base and the side wall of the columnar trench. A first thickness of the field dielectric at a first distance from the base is less than a second thickness of the field dielectric at a second distance from the base, the first distance being greater than the second distance.The first circumference of the columnar field plate at the first distance is larger than the second circumference of the columnar field plate at the second distance.

[0008] It is therefore the object of the present invention to provide an improved semiconductor device with a doping profile and corresponding methods for manufacturing it.

[0009] This problem is solved by the subject matter of the independent claims. Preferred embodiments are defined by the dependent claims. SUMMARY

[0010] According to one embodiment, a semiconductor device comprises a semiconductor body with a first primary surface. A trench is formed in the semiconductor body. The trench extends from the first primary surface into the semiconductor body along a first direction. The trench includes a field electrode and a field dielectric. The trench comprises an upper region, a lower region, and an intermediate region located between the upper and lower regions. The intermediate region is located between a first distance from the first primary surface and a second distance from the first primary surface. The difference between the second distance and the first distance along the first direction is at most 20% of the total height of the field electrode. The field electrode extends from the upper region into the lower region of the trench.The field electrode extends at least between the first distance from the first principal surface and the second distance from the first principal surface. The field dielectric is located between the field electrode and the semiconductor body. The thickness of the field dielectric increases along the first direction from a first thickness at a first distance from the first principal surface to a second thickness at a second distance from the first principal surface. The second thickness is at least 1.1 times the first thickness. The semiconductor body includes a drift region. The drift region includes a doping profile along the first direction. The slope of the doping profile is greater at the first distance than at the second distance.

[0011] According to one embodiment, a method for manufacturing a semiconductor device comprising a semiconductor body with a first principal surface includes growing a first portion of a drift region of the semiconductor body over a substrate of the semiconductor body for a first period. The growth of the first portion comprises changing the concentration of dopants over the first period at a first rate. The method further comprises growing a second portion of the drift region of the semiconductor body over the first portion of the drift region for a second period. The growth of the second portion comprises changing the concentration of dopants over the second period at a second rate, the second rate being greater than the first rate. The method further comprises forming a trench in the semiconductor body. The trench extends from the first principal surface into the semiconductor body along a first direction.The method further comprises forming a field dielectric in the trench. The thickness of the field dielectric increases along the first direction from a first thickness at a first distance from the first main surface to a second thickness at a second distance from the first main surface. The first distance borders the second part of the drift region. The second distance borders the first part of the drift region. The second thickness is at least 1.1 times the first thickness. The method further comprises forming a field electrode on the field dielectric, the field electrode extending at least between the first and second distances.

[0012] According to one embodiment, a method for manufacturing a transistor device comprising a semiconductor body with a first principal surface includes implanting dopants into a first part of a drift region of the semiconductor body, such that a doping profile in the first part of the drift region comprises at least one first slope. The method further comprises implanting dopants into a second part of the drift region, which is arranged above the first part of the drift region, such that a doping profile in the second part of the drift region comprises at least one second slope. The at least one first slope is smaller than the at least one second slope. The method further comprises forming a trench in the semiconductor body. The trench extends from the first principal surface into the semiconductor body along a first direction. The method further comprises forming a field dielectric in the trench.The thickness of the field dielectric increases along the first direction from a first thickness at a first distance from the first main surface to a second thickness at a second distance from the first main surface, the first distance being adjacent to the second part of the drift region, and the second distance being adjacent to the first part of the drift region. The second thickness is at least 1.1 times the first thickness. The method further comprises forming a field electrode on the field dielectric, the field electrode extending at least between the first and second distances.

[0013] According to one embodiment, a semiconductor device comprises a semiconductor body with a first principal surface. The semiconductor further comprises a trench formed in the semiconductor body. The trench extends from the first principal surface into the semiconductor body along a first direction. The trench includes a field electrode and a field dielectric arranged between the field electrode and the semiconductor body. The field dielectric comprises a first thickness over a first height h1 of the field electrode and a second thickness over a second height h2 of the field electrode. The field electrode has a total height h fp on, where 0.1 < h1 / h fp < 0.8, 0.1 < h2 / h fp < 0.8 and (h1 + h2) / h fp< 0.9. The semiconductor body includes a drift region. The drift region comprises a doping profile along the first direction. The slope of the doping profile changes along the first direction between the first and second distances from the first main surface. The slope of the doping profile at the first distance is greater than the slope of the doping profile at the second distance. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The present disclosure is illustrated by way of example and without limitation in the figures of the accompanying drawings, in which the same reference numerals refer to similar or identical elements. The elements of the drawings are not necessarily to scale relative to one another. The features of the various illustrated examples may be combined, provided they are not mutually exclusive. Fig. Figure 1A illustrates a partial cross-sectional view of a semiconductor device according to embodiments of the present disclosure. Fig. Figure 1B illustrates a partial cross-sectional view of a semiconductor device according to embodiments of the present disclosure. Fig. 1C illustrates a partial top view of the [unclear text] in the Fig. Semiconductor device shown in 1A-1B. Fig. Figure 2A illustrates a partial cross-sectional view of another embodiment of a semiconductor device. Fig. Figure 2B illustrates a partial cross-sectional view of yet another embodiment of a semiconductor device. Fig. 2C illustrates a partial top view of the [unclear text] in the Fig. Semiconductor device shown in 2A-2B. Fig. Figure 3 illustrates a partial cross-sectional view of another embodiment of a semiconductor device. The Fig. Figures 4A-4C illustrate different embodiments of aspects of the Fig. 1A-1C, Fig. 2A-2C and Fig. 3 illustrated semiconductor device. Fig. Figure 5 illustrates an embodiment for producing the components described in the Fig. 1A-1C, Fig. 2A-2C and Fig. 3 illustrated semiconductor devices. Fig. Figure 6 illustrates another embodiment for producing the components described in the Fig. 1A-1C, Fig. 2A-2C and Fig. 3 illustrated semiconductor devices. DETAILED DESCRIPTION

[0015] The following detailed description refers to the accompanying drawings, which form part thereof and illustrate specific embodiments in which the invention can be implemented. In this context, directional terminology such as "top," "bottom," "front," "back," "leading," "trailing," etc., is used with reference to the orientation of the described figure(s). Since components of the embodiments can be arranged in a number of different orientations, the directional terminology is used for illustrative purposes and is in no way limiting. It is understood that other embodiments can be used and structural or logical modifications can be made without departing from the scope of the present invention.The following detailed description is not to be understood in a restrictive sense, and the scope of the present invention is defined by the attached claims.

[0016] A number of exemplary embodiments are described below. In this case, identical structural features are indicated by identical or similar reference numerals in the figures. In the context of this description, "lateral" or "lateral direction" is to be understood as a direction or extent that generally runs parallel to the lateral extent of a semiconductor material or semiconductor substrate. The lateral direction thus generally extends parallel to these surfaces or sides. In contrast, the term "vertical" or "vertical direction" is to be understood as a direction that generally runs perpendicular to these surfaces or sides and thus to the lateral direction. The vertical direction therefore runs in the thickness direction of the semiconductor material or semiconductor substrate.

[0017] As used in this description, when an element such as a layer, area, or substrate is described as being "on" or "extending" onto another element, it may be located directly on or extending directly onto the other element, or there may be intervening elements. In contrast, when an element is described as being "directly on" or extending "directly" onto another element, there are no intervening elements.

[0018] As used in this description, when an element is described as "connected" or "coupled" to another element, it may be directly connected or coupled to that other element, or there may be intervening elements. In contrast, when an element is described as "directly connected" or "directly coupled" to another element, there are no intervening elements.

[0019] As used herein, various device types and / or doped semiconductor regions may be of n-type or p-type, but this is merely for the sake of simplicity of description and is not intended to be restrictive, and such a designation may be replaced by the more general description of a 'first conductivity type' or a 'second, opposite conductivity type', the first type being either n-type or p-type and the second type then being either p-type or n-type.

[0020] The figures illustrate relative doping concentrations by indicating "-" or "+" next to the doping type "n" or "p". For example, "n-" indicates a doping concentration lower than that of an "n" doped region, while an "n+" doped region has a higher doping concentration than an "n" doped region. Doped regions with the same relative doping concentration do not necessarily have the same absolute doping concentration. For example, two different "n" doped regions can have the same or different absolute doping concentrations.

[0021] According to embodiments, the semiconductor device is a transistor device (such as a power transistor device) and may be a MOSFET (metal-oxide-semiconductor field-effect transistor) device, a superjunction transistor device, or an insulated-gate bipolar transistor device (IGBT device). The transistor device may be a vertical transistor device with a drift path extending substantially perpendicular to the main surfaces of the device.

[0022] The regions and terminals of the transistor device are referred to herein as source, drain, and gate regions / terminals. As used herein, these terms may also include the functionally equivalent regions / terminals of other types of transistor devices, such as an insulated-gate bipolar transistor (IGBT).For example, as used herein, the term “source” region / terminal can include not only a source region / terminal of a MOSFET device and a superjunction device, but also an emitter region / terminal of an insulated-gate bipolar transistor device (IGBT device); the term “drain” region / terminal can include not only a drain of a MOSFET device or a superjunction device, but also a collector of an insulated-gate bipolar transistor device (IGBT device) and a collector of a BJT device; and the term “gate” region / terminal can include not only a gate of a MOSFET device or a superjunction device, but also a gate of an insulated-gate bipolar transistor device (IGBT device).

[0023] Some embodiments are described next with reference to the figures. Each example is provided to illustrate the revelation.

[0024] Fig. Figure 1A illustrates a partial cross-sectional view of a semiconductor device 100 according to embodiments of the present disclosure. Fig. Figure 1B illustrates a partial cross-sectional view of another embodiment of a semiconductor device 200. Fig. Figure 1C illustrates a partial top view of the vertical power semiconductor transistor devices 100, 200, which are located in the Fig. 1A-B are shown. The partial cross-sectional view in the Fig. 1A-1B is taken along the line that is in Fig. 1C is labelled AA'.

[0025] The in Fig. Figure 1A, illustrated semiconductor device 100, differs from the one in Figure 100. Fig. Figure 1B illustrates the semiconductor device 200 only with respect to the shape of the trench 110, the shape of the field electrode 124, and the shape of the field dielectric 126. Optionally, the shape of the gate electrode 112 and the gate dielectric 114 can also differ between those shown in Fig. 1A illustrated semiconductor device 100 and the one in Fig. 1B illustrated semiconductor device 200 (not shown) differ.

[0026] The semiconductor device 100, 200 comprises a semiconductor body 102. The semiconductor body can comprise a semiconductor material, such as silicon or silicon carbide (e.g., be made of it). The semiconductor body 102 can contain a (in the Fig. 1A and Fig. 1B (not shown) comprise a drain region of a first conductivity type, a body region 104 of a second conductivity type opposite to the first conductivity, a drift region 106 of the first conductivity type separating body region 104 from the drain region, and a source region 108 of the first conductivity type separated from drift region 106 by body region 104. In the case of an n-channel device, the first conductivity type is n-type and the second conductivity type is p-type. In the case of a p-channel device, the first conductivity type is p-type and the second conductivity type is n-type. For ease of illustration only, the first conductivity type is denoted as n-type (e.g., 'n', 'n+') and the second conductivity type is denoted as p-type (e.g., 'p', 'p+'). The designations 'n', 'n+', 'p' and 'p+' in Fig. 1A-1B indicate general relative dopant concentration relationships between different regions of the same doping type and are not intended to be restrictive with respect to specific doping concentrations, ranges, or profiles. For example, a region labeled 'n+' indicates that the region is more heavily doped than a region labeled 'n'.

[0027] A trench 110 extends through the source region 108 and the body region 104 and into the drift region 106. The trench 110 includes a gate electrode 112, which is insulated from the surrounding semiconductor material by a gate dielectric 114. The gate electrode 112 can orient itself longitudinally (direction 'x' in the Fig. 1C) extend in stripes and / or form part of a grid. Directions 'x' and 'y' in Fig. 1A-1C are lateral (horizontal) directions that are perpendicular to each other and parallel to a first main surface 101 of the semiconductor device 100, 200, whereas direction 'z' is a vertical direction that extends in depth into the semiconductor device 100, 200 and is perpendicular to the first main surface 101 of the device 100.

[0028] The semiconductor device 100, 200 can also include a source electrode 116 to provide a source potential ('S') to the body region 104 and the source region 108 of the semiconductor device 100, 200. The body region 104 can include a heavily doped body contact region 118 to ensure an ohmic contact between the source electrode 116 and the body region 104. A drain electrode (not shown) on the opposite side of the semiconductor device 100 provides a drain potential to the heavily doped drain region (not shown) of the semiconductor device 100. A conductive channel region can be formed in the body region 104 under suitable bias of the source electrode 116, the drain electrode, and the gate electrode 112 of the device 100.

[0029] According to the in the Fig. In the embodiments illustrated in Figures 1A-1C, the semiconductor device 100, 200 also includes a field electrode 124, which is arranged in the same trench 110 as the gate electrode 112. The field electrode 124 is insulated from the gate electrode 112 and the surrounding semiconductor material by a field dielectric 126, which may be of the same material as the gate dielectric 114 (e.g., an oxide or a nitride) or of another insulating material. The field electrode 124 may be biased to the source (S) potential, another potential, or be at no potential.

[0030] The semiconductor device 100, 200 comprises a semiconductor body 102 with a first main surface 101. The trench 110 is formed in the semiconductor body 102. The trench 110 extends from the first main surface 101 into the semiconductor body 102 along a first direction z. The trench 110 includes a field electrode 124 and a field dielectric 126, which is arranged between the field electrode 124 and the semiconductor body 102.

[0031] Trench 110 can have an upper area of ​​110 u , a lower range 110 l and an intermediate range of 110 i include the area between the upper range 110 u and the lower range 110 l is arranged. The upper area 110 u can be compared to the intermediate range of 110 i and the lower range 110 l closer to the first main surface 110. The intermediate area 110 iThe field electrode 124 can be positioned between a first distance d1 and a second distance d2 (where, for example, the thickness of the field dielectric 126 changes from the first thickness t1 to the second thickness t2). The distances d1 and d2 are measured from the first main surface 101 of the semiconductor body, where d2 can be larger than d1. In other words, d2 can extend deeper into the semiconductor body 102 than d1. The field electrode 124 can extend from the upper region 110 u into the lower range 110 l of the ditch (110).

[0032] The thickness t of the field dielectric 126 increases along the first direction z from a first thickness t1 at the first distance d1 from the first main surface 101 to a second thickness t2 at the second distance d2 from the first main surface 101. This can be observed in the intermediate region 110. iof the trench 110. In one embodiment, a difference d between the second distance d2 and the first distance d1 along the first direction z is at most 20% of a total height h. fp of the field electrode 124, and the second thickness t2 is at least 1.1 times the first thickness t1. In other examples, a difference d between the second distance d2 and the first distance d1 along the first direction z is at most 15% of a total height h. fp of the field electrode 124, and the second thickness t2 is at least 1.2 times the first thickness t1. In other examples, a difference d between the second distance d2 and the first distance d1 along the first direction z is at most 10% of a total height h. fp of the field electrode 124, and the second thickness t2 is at least 1.15 times the first thickness t1.

[0033] In other words, the field dielectric 126 can comprise a section in which the thickness t of the field dielectric 126 changes from the first thickness t1 at the first distance d1 to the second thickness t2 at the second distance d2. In this section, the field dielectric 126 can have a step-like shape, as shown in Fig. 1A illustrates. The field dielectric can also take on various forms in this section, as in relation to the Fig. 4A-4C illustrated below.

[0034] The semiconductor body 102 can further comprise a drift region 106. The drift region 106 comprises a doping profile 1000 along the first direction z. The slope of the doping profile 1000 changes along the first direction z between the first distance d1 and the second distance d2 from the first main surface 101. In other words, the slope of the doping profile can change over the same distance (between d1 and d2 from the first main surface 101) where the thickness of the field dielectric 126 changes from the first thickness t1 to the second thickness t2.

[0035] According to embodiments, the height h along the first direction z is ur the field electrode 124 in the upper area 110 i more than 25% of the total height h fp the field electrode 124, and a height h lr the field electrode 124 in the lower area 110 i amounts to more than 25% of the total height h fp the field electrode 124.

[0036] The field electrode 124 can reach a height h ir in the intermediate area 110 i of the trench 110 (measured along the z-direction). The field dielectric 126 can have a thickness t from the first thickness t1 to the second thickness t2 adjacent to the field electrode 124 in the intermediate region 110. i of the trench 110. In some embodiments, the section of the field dielectric 126 in which the thickness t changes from the first thickness t1 to the second thickness t2 (such as the section of the field electrode 124, which has the height h) can be ir exhibits), in which trench 110 are arranged such that 10% or 20% of a total height h fpThe field electrode 124 is arranged above the section of the field dielectric 126 in which the thickness t changes from the first thickness t1 to the second thickness t2. In other embodiments, the section of the field dielectric 126 in which the thickness t changes from the first thickness t1 to the second thickness t2 (such as the section of the field electrode 124 that has the height h) can be ir exhibits), in which trench 110 is arranged such that 80% or 70% of a total height h fp The field electrode 124 is arranged above the section of the field dielectric 126 in which the thickness t changes from the first thickness t1 to the second thickness t2. In one embodiment, the section of the field dielectric 126 in which the thickness t changes from the first thickness t1 to the second thickness t2 (such as the section of the field electrode 124 that has the height h) can be ir exhibits), in the trench 110 be arranged such that a height h lrthe field electrode 124 in the lower area 110 i and a height h ur the field electrode 124 in the upper area 110 i are essentially the same (if processing variations, such as + / - 1 or 2%, are taken into account). In this case, 0.1 < h1 / h fp < 0.8, 0.1 < h2 / h fp < 0.8 and (h1 + h2) / h fp < 0.9 applies.

[0037] Generally speaking, the second thickness t2 of the field dielectric 126 can depend on the voltage class of the semiconductor device 100, 200. For example, t2 can be 5 nm / V times the voltage class + / - 50%. The first thickness t1 can also depend on the voltage class of the semiconductor device 100, 200 and additionally on the height h. ur the field electrode 124 in the upper area 110 i as well as from the total height h fp depend on the field electrode 124. For example, t1 can be greater than or equal to 0.5 times 5 nm / V times voltage class times (h ur / h fp). This may reflect the fact that if the transition from the first thickness t1 to the second thickness t2 becomes deeper, t1 must become thicker due to an increase in the electric field.

[0038] With reference to Fig. In 1A, the thickness of the field electrode 124 decreases along the first direction z from a first thickness of the field electrode 124 at the first distance d1 to a second thickness of the field electrode 124 at the second distance d2. Typical ratios of the first thickness w1 of the field electrode at the first distance d1 to the second thickness w2 of the field electrode at the second distance d2 can be 1.5 ≤ w1 / w2 ≤ 4. In an embodiment where the voltage class of the semiconductor device is 100, 200, or 60 V, the ratio w1 / w2 can be approximately 2, such as 1.75 ≤ w1 / w2 ≤ 2.25.

[0039] With reference to Fig. 1B The thickness of the field electrode 124 increases along the first direction z from a first thickness of the field electrode 124 at the first distance d1 to a second thickness of the field electrode 124 at the second distance d2. A typical relationship between the first thickness w1 of the field electrode at the first distance d1 and the second thickness w2 of the field electrode at the second distance d2 can be 1.1 ≤ w1 ≤ w2. With reference to Fig. 1C shows that for both in the Fig. In embodiments 1A-1B shown, the trench 110 can be elongated along a second direction (x) and the trench 110 can further comprise a gate electrode 112 arranged above the field electrode 124.

[0040] As discussed above, a doping profile 1000 of the semiconductor body can have a slope along the first direction z that changes along the first direction z between the first distance d1 and the second distance d2 from the first main surface 101. For example, the slope of the doping profile can change over the same distance (between d1 and d2 from the first main surface 101) where the thickness of the field dielectric 126 changes from the first thickness t1 to the second thickness t2. In some embodiments, the slope of the doping profile 1000 changes between the first distance d1 and the second distance d2 approximately proportionally to a ratio between the first thickness t1 of the field dielectric 126 and the second thickness t2 of the field dielectric 126.

[0041] Fig. 2A illustrates a partial cross-sectional view of another embodiment of a semiconductor device 300. Fig. 2B illustrates a partial cross-sectional view of yet another embodiment of a semiconductor device 400. Fig. 2C illustrates a partial top view of the [unclear text] in the Fig. Semiconductor devices 300, 400 shown in 2A-2B. The partial cross-sectional views in the Fig. 2A- Fig. 2B are along the in Fig. 2C with line labeled B-B' taken..

[0042] The in Fig. 2A illustrated semiconductor device 300 differs from the one in Fig. 2B illustrated semiconductor device 400 only with respect to the shape of the trench 110, the shape of the field electrode 124 and the shape of the field dielectric 126. Same reference numerals in the Fig. 2A-2C and in the Fig. 1A-1C refer to identical or similar components and are not used again in relation to the Fig. 2A-2C are described, but for the sake of brevity, reference is made to the description above in relation to the Fig. 1A-1C was made.

[0043] The in the Fig. The embodiments illustrated in 2A-2C are similar to those shown in the Fig. The embodiments illustrated in Figures 1A-1C differ, however, in that the field electrode 124 is located in a different trench 110 than the gate electrode 112, which is located in the trench 202, and the field electrode 124 has a column-like shape (similar to a needle shape) in a longitudinal extension (direction 'z' in the Fig. 2A-2C) of the field electrode 124. The term "pillar-like" or "needle-like," as used herein, describes an electrode structure with a small or narrow circumference or width proportional to its height / depth in a semiconductor material, as opposed to a strip-shaped electrode structure that is longer than it is deep, as in the Fig. 1A- Fig. Figure 1C shows this. Of course, the width of trench 110 can vary along the vertical direction (z) or the lateral directions (x, y), but any width is smaller than the height / depth of trench 110.

[0044] In the Fig. In the embodiment illustrated in Figure 2C, the column-like field electrode trenches 110 are shown in plan view as having an octagonal lateral shape. However, the column-like trench 110 can have other lateral shapes in plan view. For example, the column-like or needle-like trench 110 can have a circular, square, or hexagonal shape in plan view. Additionally, the following is illustrated: Fig. 2C, that the trenches 110 are arranged in a square pattern, with the trenches 110 being arranged at the corners of the square. Other patterns are also considered by the present disclosure, such as hexagonal or triangular patterns. In cross-section, the columnar trenches 110 can have the same structure, regardless of the pattern of arrangement or the lateral shape of the columnar trench 110 and the columnar field electrode 124.

[0045] The gate trenches 202 can be configured as a grid, e.g. as in Fig. 2C shown, or as stripes, e.g. as in Fig. 1C shown. In both cases, the use of columnar field plate trenches 110 can be advantageous, since the remaining silicon mesa area 204 surrounding each field electrode trench 110 and defined by the adjacent gate trenches 202 is smaller compared to those shown in Fig. The trench strip structures shown in 1C may be larger, allowing for a lower on-resistance.

[0046] With reference to Fig. 2A (which is similar to Fig. 1A is) the thickness of the field electrode 124 decreases along the first direction z from a first thickness of the field electrode 124 at the first distance d1 to a second thickness of the field electrode 124 at the second distance d2.

[0047] With reference to Fig. 2B (which is similar to Fig. 1B) the thickness of the field electrode 124 increases along the first direction z from a first thickness of the field electrode 124 at the first distance d1 to a second thickness of the field electrode 124 at the second distance d2. In some embodiments (in Fig. (2B not shown) the thickness of the field electrode 124 between the first distance d1 and the second distance d2 can remain the same.

[0048] Once again, a doping profile 1000 of the semiconductor body 102 can have a slope along the first direction z that changes along the first direction z between the first distance d1 and the second distance d2 from the first main surface 101. For example, the slope of the doping profile can change over the same distance (between d1 and d2 from the first main surface 101) where the thickness of the field dielectric 126 changes from the first thickness t1 to the second thickness t2. In some embodiments, the slope of the doping profile 1000 changes between the first distance d1 and the second distance d2 approximately proportionally to a ratio between the first thickness t1 of the field dielectric 126 and the second thickness t2 of the field dielectric 126.

[0049] In the Fig. 1A-1C and Fig. Figures 2A-2C show the doping profile 1000 as a function of the depth (along the z direction) of the semiconductor body 101. The doping profile 1000 can have at least one first slope s1 in the drift region 106 adjacent to a region of the field dielectric 126 located above the region where the thickness t of the field dielectric 126 changes from the first thickness t1 to the second thickness t2. In other words, the doping profile 1000 can have at least one first slope s1 in the drift region 106 that is a smaller distance from the first principal surface 101 than the first distance d1 when measured along the z direction.The doping profile 1000 can have at least one second slope s2 in the drift region 106, adjacent to a region of the field dielectric 126 located below the region where the thickness t of the field dielectric 126 changes from the first thickness t1 to the second thickness t2. In other words, the doping profile 1000 can have at least one second slope s2 in the region of the drift region 106 that is located at a greater distance from the first principal surface 101 than the second distance d2 when measured along the z-direction. In some examples, a ratio between the first slope s1 and the second slope s2 can be approximately proportional to a ratio between the second thickness t2 and the first thickness t1. However, this should not be interpreted restrictively, and other choices for the slopes s1 and s2 are considered by the present disclosure. As in the . Fig. 1A-1B and the Fig. As can be seen in 2A-2B, the slope of the doping profile 1000 changes between the first distance d1 and the second distance d2. In some embodiments, the second slope s2 is smaller than the first slope s1.

[0050] In some embodiments, the portion of the drift region 106 that is closer to the first main surface 101 than the first distance d1 (when measured along the z-direction) generally exhibits a linearly graduated first doping profile (such as with a generally constant slope s1), and the portion of the drift region 106 that is closer to the first main surface 101 than the second distance d2 (when measured along the z-direction) generally exhibits a linearly graduated second doping profile (such as with a generally constant slope s2). Thus, both the first and second doping profiles of the drift region 106 may exhibit one or more regions of localized nonlinearity due to process variations, material defects, etc., but overall they increase in a straight line.

[0051] The absolute levels of the doping profile 1000 can vary depending on the voltage class of the device (100, 200, 300, 400). For example, in the case of a 100 V device, the drift region 106 can have a doping level around the pn junction with the body region 104 of approximately 1 e16 cm⁻³, increasing to a level between 1 e16 and 5 e16 cm⁻³ at the first distance d1. The doping level of the drift region 106 may increase only slightly between the first distance d1 and the second distance d2, such that the doping level at distance d2 is less than or equal to 1.2 times the doping level at distance d1. The doping level of the drift area 106 can further increase from the second distance d2 to a depth of the trench 110 to 2 e16 to 2 e17 cm-3.

[0052] Fig. Figure 3 illustrates another embodiment of a semiconductor device 500 according to the present disclosure. The semiconductor device 500 is similar to the one in Fig. Figure 1A illustrates the semiconductor device 100 and differs in that the field dielectric 126 comprises an additional region in which the thickness t of the field dielectric changes from a third thickness t3 at a distance d3 from the first main surface 101 to a fourth thickness t4 at a fourth distance d4 from the first main surface 101. It is understood that the Fig. 1B, Fig. 2A, Fig. 2B illustrated semiconductor devices 200, 300, 400 may have an additional region in which the thickness t of the field dielectric is similar to that described in relation to Fig. 3 semiconductor device shown changes. Same reference numerals in Fig. 3 and in the Fig. 1A-2C refer to identical or similar components and are not used again in relation to Fig. 3 described, but for the sake of brevity, reference is made to the description given above in relation to the Fig. 1A-2C was made.

[0053] As in Fig. As can be seen in Figure 3, the semiconductor device 500 can comprise a thickness t of the field dielectric 126 that increases along the first direction z from a third thickness t3 at a third distance d3 from the first principal surface 101 to a fourth thickness t4 at a fourth distance d4 from the first principal surface 101. In particular, the third thickness t3 can be equal to or greater than the second thickness t2. The fourth distance d4 is greater than the third distance d3, which is greater than the second distance d2 when measured along the z-direction. A difference d between the fourth distance d4 and the third distance d3 along the first direction z can be at most 20% of the total height h. fpThe field electrode 124. The fourth thickness t4 can be at least 1.1 times the third thickness t3. In other examples, a difference d between the fourth distance d4 and the third distance d3 along the first direction z is at most 15% of a total height h. fp of the field electrode 124, and the fourth thickness t4 is at least 1.2 times the third thickness t3. In other examples, a difference d between the fourth distance d4 and the third distance d3 along the first direction z is at most 10% of a total height h. fp of the field electrode 124, and the fourth thickness t4 is at least 1.15 times the third thickness t3.

[0054] Trench 110 can have an upper area of ​​110 u , a lower range 110 l , a medium range 110 m and a first and a second intermediate area 110 i1 , 110 i2 include those between the upper range of 110 uand the middle range 110 m and between the middle range 110 m and the lower range 110 l are arranged. The middle area 110 m can be compared to the second intermediate range of 110 i2 and the lower range 110 l closer to the first main surface 110. The first intermediate area 110 i1 can be arranged between a first distance d1 and a second distance d2 (where, for example, the thickness of the field dielectric 126 changes from the first thickness t1 to the second thickness t2). The second intermediate region 110 i2can be arranged between a third distance d3 and a fourth distance d4 (where, for example, the thickness of the field dielectric 126 changes from the third thickness t3 to the fourth thickness t4). The distances d1, d2, d3, and d4 are measured from the first main surface 101 of the semiconductor body 102, where d4 can be larger than d3, which can be larger than d2, which can be larger than d1. The field electrode 124 can extend from the upper region 110 u into the lower range 110 l of the ditch (110).

[0055] In embodiments, the field electrode 124 and / or the field dielectric 124 can be arranged such that a height h ur the field electrode 124 in an upper area 110 u of the ditch 110, a height h mr the field electrode 124 in a middle area 110 m of the ditch 110 and a height h lr the field electrode 124 in a lower area 110 uThe dimensions of trench 110 are essentially the same (within approximately + / - 5%).

[0056] In other words, the field dielectric 126 can comprise at least two sections, in which the thickness t of the field dielectric changes: a first section in which the thickness changes from the first thickness t1 at the first distance d1 to the second thickness t2 at the second distance d2, and a second section in which the thickness changes from the third thickness t3 at the third distance d3 to the fourth thickness t4 at the fourth distance d4. In the first and the second sections, the field dielectric 126 can have a step-like shape, as shown in Fig. Figure 3 illustrates that the field dielectric 126 can also have different forms in the first and second sections, as shown in relation to the Fig. 4A-4C illustrated below.

[0057] In Fig. 3. The thickness of the field electrode 124 decreases along the first direction z from a first thickness of the field electrode 124 at the first distance d1 to a second thickness of the field electrode 124 at the second distance d2, and further decreases along the first direction z from a third thickness of the field electrode 124 at the third distance d3 to a fourth thickness of the field electrode 124 at the fourth distance d4. However, the thickness of the field electrode 124 can also increase along the first direction over the first and second sections, similar to those described above. Fig. 1B illustrated embodiments. Likewise, the embodiments relating to the Fig. The embodiments shown in 2A-2C also have several sections in which the thickness of the field dielectric 126 and the field electrode 124 changes.

[0058] The doping profile 1000 of the semiconductor body 102 can include a slope that changes along the first direction z between the third distance d3 and the fourth distance d4 from the first main surface 101 (i.e., in the region adjacent to the trench 110 where the field dielectric 126 changes from the third thickness t3 to the fourth thickness t4). For example, the doping profile 1000 can have at least one second slope s2 in the drift region 106, adjacent to a region of the field dielectric 126 located above the region where the thickness t of the field dielectric 126 changes from the third thickness t3 to the fourth thickness t4. The doping profile 1000 can have at least one third slope s3 in the drift region 106, which borders a region of the field dielectric 126 that is located below the region in which the thickness t of the field dielectric 126 changes from the third thickness t3 to the fourth thickness t4.In some examples, the ratio between the second slope s2 and the third slope s3 may be approximately proportional to the ratio between the fourth thickness t4 and the third thickness t3. However, this should not be interpreted restrictively, and other choices for the slopes s2 and s3 are considered by the present disclosure. In some embodiments, the third slope s3 is smaller than the second slope s2.

[0059] The foregoing has been described in relation to two “stages” in the field dielectric 126, but it is also considered that even more “stages” in the field dielectric with corresponding changes in the slope of the doping profile (such as three, four, five, six and so on) may be considered and covered by the present disclosure.

[0060] Fig. Figure 4A illustrates an enlarged view of a section of the trench 110, comprising a field electrode 124 and a field dielectric 126, according to another embodiment. This embodiment of the field dielectric 126 and the field electrode 124 can be found in the figures shown in the Fig. 1A-1C, Fig. 2A-2C, Fig. The semiconductor devices 100, 200, 300, 400, and 500 illustrated in Figure 3 can be used instead of, or as part of, the field dielectric 126 and the field electrode 124 shown therein. For example, the devices shown in relation to the Fig. In embodiments 4A-4C, various forms of the transition of the field dielectric 125 from one thickness (such as the first thickness t1 or the third thickness t3 discussed above) to another thickness (such as the second thickness t2 or the fourth thickness t4 discussed above) are shown.

[0061] About the height of the intermediate area h irAt the field electrode 124, the thickness of the field dielectric 126 changes from the first thickness t1 at distance d1 from the first main surface 101 to the second thickness t2 at the second distance d2 from the first main surface 101. In the respect of Fig. In the embodiment shown in Figure 4A, the field dielectric 126 can be edgeless. In other words, the field dielectric 126 does not have a sharp, abrupt change in thickness at the second distance d2 from the first main surface 101. Instead, the field dielectric 126 has a curved shape at the second distance d2. The surface of the field dielectric 126 can be considered to have a concave shape at the first distance d1 and a convex shape at the second distance d2. In other embodiments, the field dielectric 126 can change substantially linearly between the first distance d1 and the second distance d2 from the first main surface 101, as shown in Figure 4A. Fig. 4B can be seen. In other embodiments, the field dielectric 126 can have a "step-like" shape, as exemplified in the above. Fig. 1A-2C and Fig. Figure 3 shows that the field dielectric may exhibit a rather abrupt change in thickness at the second distance d2. An abrupt change can be considered as having an angle α of approximately 90° formed between the field dielectric 126 located below the second distance d2 and the field dielectric 126 located above the second distance d2. Although on Fig. Reference was made to Figure 4A-C to illustrate profiles for the transition of the field dielectric 126 from one thickness to another; other profiles are also considered and are included in the present disclosure.

[0062] Next, embodiments for manufacturing the components described in the Fig. 1A-1C, Fig. 2A-2C, Fig. 3 and Fig. 4A-4C illustrated semiconductor devices 100, 200, 300, 400, 500 described.

[0063] Fig. Figure 5 illustrates an embodiment for producing the components described in the Fig. 1A-1C, Fig. 2A-2C, Fig. 3 and Fig. Figures 4A-4C illustrated semiconductor devices 100, 200, 300, 400, and 500. According to this embodiment, a first part of a drift region 106 of a semiconductor body 102 is grown over a substrate of the semiconductor body for a first period 610. The step of growing the first part 610 comprises changing the concentration of dopants over the first period at a first rate. For example, the first part of the drift region 106 can be grown using an epitaxial growth process, wherein the concentration of dopants present during the epitaxial growth process changes (such as decreases) over the first period at the first rate. In some embodiments, the first rate can be constant over the first period.

[0064] Subsequently, a second part of the drift region 106 can be grown over the first part of the drift region 610 for a second period 620. The step of growing the second part 620 involves changing the concentration of dopants over the second period at a second rate, where the second rate is greater than the first rate. For example, the second part of the drift region 106 can be grown using an epitaxial growth process, wherein the concentration of dopants present during the epitaxial growth process changes (e.g., decreases) over the second period at the second rate. In some embodiments, the second rate can be constant over the second period.

[0065] Subsequently, at least one trench 110 is formed in the semiconductor body 102 630. The at least one trench 110 extends from the first main surface 101 into the semiconductor body 102 along a first direction z.

[0066] Then, the process 600 continues the formation 640 of a field dielectric 126 in the trench 110. The thickness t of the field dielectric 124 can increase along the first direction z from a first thickness t1 at a first distance d1 from the first main surface 101 to a second thickness t2 at a second distance d2 from the first main surface 101, as described above with respect to the Fig. 1A-1C, Fig. 2A-2C, Fig. 3 and Fig. 4A-4C discussed. The first distance d1 can adjoin the second part of the drift region 106 (grown in step 620), and the second distance d2 can adjoin the first part of the drift region 106 (grown in step 610). In some embodiments, a difference d between the second distance d2 and the first distance d1 along the first direction z is at most 20% of a total height h. fp of the field electrode 124, and the second thickness t2 is at least 1.1 times the first thickness t1. In other examples, a difference d between the second distance d2 and the first distance d1 along the first direction z is at most 15% of a total height h. fp of the field electrode 124, and the second thickness t2 is at least 1.2 times the first thickness t1. In other examples, a difference d between the second distance d2 and the first distance d1 along the first direction z is at most 10% of a total height h. fpof the field electrode 124, and the second thickness t2 is at least 1.15 times the first thickness t1.

[0067] Fig. Figure 6 illustrates another embodiment for producing the components described in the Fig. 1A-1C, Fig. 2A-2C, Fig. 3 and Fig. Figures 4A-4C illustrated semiconductor devices 100, 200, 300, 400, and 500. According to this embodiment, dopants are implanted into a first part of a drift region 106 of a semiconductor body 102 710 such that a doping profile in the first part of the drift region 106 includes at least one first slope (such as s2). For example, the implantation 710 could comprise the implantation of dopants into the first part of the drift region 106 using a first implantation energy (e.g., a first implantation energy sufficiently high to reach into a deeper part of the drift region 106). Alternatively, implantation of 710 could be performed after only an initial part of the drift region 106 has been grown (e.g., via epitaxial growth), and the remainder of the drift region 106 could be grown after the implantation of 710 step has been performed.

[0068] Subsequently, dopants are implanted into a second part of the drift region 106, which is positioned above the first part of the drift region 106, such that a doping profile in the second part of the drift region 106 includes at least one second slope (such as s1), wherein the at least one first slope is smaller than the at least one second slope. For example, the implantation 720 could involve implanting dopants into the second part of the drift region 106 using a second implantation energy that is lower than the first implantation energy used to implant dopants 710 into the first part of the drift region (e.g., a second implantation energy that is high enough to reach the second part of the drift region 106 but low enough not to reach the first part of the drift region 106).Alternatively, implantation 720 could be performed after the second part of the drift region 106 has been grown (e.g. via epitaxial growth) and a remainder of the semiconductor body 102 could be grown after the implantation 720 step has been performed.

[0069] Subsequently, at least one trench 110 is formed in the semiconductor body 102 730. The at least one trench 110 extends from the first main surface 101 into the semiconductor body 102 along a first direction z.

[0070] Then, the process 700 continues the formation 740 of a field dielectric 126 in the trench 110. The thickness t of the field dielectric 124 can increase along the first direction z from a first thickness t1 at a first distance d1 from the first main surface 101 to a second thickness t2 at a second distance d2 from the first main surface 101, as above with respect to the Fig. 1A-1C, Fig. 2A-2C, Fig. 3 and Fig. 4A-4C discussed. The first distance d1 can be adjacent to the second part of the drift region 106 (where dopants were implanted in step 720), and the second distance d2 can be adjacent to the first part of the drift region 106 (where dopants were implanted in step 710). In some embodiments, a difference d between the second distance d2 and the first distance d1 along the first direction z is at most 20% of a total height h. fp of the field electrode 124, and the second thickness t2 is at least 1.1 times the first thickness t1. In other examples, a difference d between the second distance d2 and the first distance d1 along the first direction z is at most 15% of a total height h. fpof the field electrode 124, and the second thickness t2 is at least 1.2 times the first thickness t1. In other examples, a difference d between the second distance d2 and the first distance d1 along the first direction z is at most 10% of a total height h. fp of the field electrode 124, and the second thickness t2 is at least 1.15 times the first thickness t1.

[0071] Although the present revelation is not limited to this, the following numbered examples illustrate one or more aspects of the revelation.

[0072] Example 1: Semiconductor device comprising: a semiconductor body with a first principal surface; and a trench formed in the semiconductor body, the trench extending from the first principal surface into the semiconductor body along a first direction, the trench comprising a field electrode and a field dielectric arranged between the field electrode and the semiconductor body, the thickness of the field dielectric increasing along the first direction from a first thickness at a first distance from the first principal surface to a second thickness at a second distance from the first principal surface, the difference between the second distance and the first distance along the first direction being at most 20% of the total height of the field electrode, the second thickness being at least 1.1 times the first thickness, the semiconductor body comprising a drift region.wherein the drift region comprises a doping profile along the first direction, wherein a slope of the doping profile along the first direction changes between the first distance and the second distance from the first main surface.

[0073] Example 2: Semiconductor device according to Example 1, wherein the difference between the second distance and the first distance along the first direction is at most 15% of the total height of the field electrode, wherein the second thickness is at least 1.2 times the first thickness.

[0074] Example 3: Semiconductor device according to Example 1, wherein the difference between the second distance and the first distance along the first direction is at most 10% of the total height of the field electrode, wherein the second thickness is at least 1.15 times the first thickness.

[0075] Example 4: Semiconductor device according to Example 1, wherein the trench comprises an upper region, a lower region and an intermediate region arranged between the upper region and the lower region, wherein the intermediate region is arranged between the first distance and the second distance, and wherein the field electrode extends from the upper region into the lower region of the trench.

[0076] Example 5: Semiconductor device according to Example 4, wherein the ratio of the second thickness of the field dielectric to the first thickness of the field dielectric is in a range between 1.5 and 2.5, and wherein the height of the field electrode in the upper region is between 0.75 times and 1.25 times the height of the field electrode in the lower region.

[0077] Example 6: Semiconductor device according to Example 4, wherein along the first direction the height of the field electrode in the upper region is more than 10% of the total height of the field electrode, and wherein along the first direction the height of the field electrode in the lower region is more than 10% of the total height of the field electrode.

[0078] Example 7: Semiconductor device according to Example 5, wherein along the first direction the height of the field electrode in the upper region is more than 25% of the total height of the field electrode, and wherein along the first direction the height of the field electrode in the lower region is more than 25% of the total height of the field electrode.

[0079] Example 8: Semiconductor device according to any one of Examples 1 to 7, wherein the trench is elongated along a second direction, and wherein the trench further comprises a gate electrode arranged above the field electrode.

[0080] Example 9: Semiconductor device according to one of Examples 1 to 8, wherein the thickness of the field electrode decreases along the first direction from a first thickness of the field electrode at the first distance to a second thickness of the field electrode at the second distance.

[0081] Example 10: Semiconductor device according to any of Examples 1 to 8, wherein the thickness of the field electrode increases or remains constant along the first direction from a first thickness of the field electrode at the first distance to a second thickness of the field electrode at the second distance.

[0082] Example 11: Semiconductor device according to any of Examples 1 to 7, wherein the trench has a column-like shape, and wherein the thickness of the field electrode decreases along the first direction from a first thickness of the field electrode at the first distance to a second thickness of the field electrode at the second distance.

[0083] Example 12: Semiconductor device according to any of Examples 1 to 7, wherein the trench has a column-like shape, and wherein the thickness of the field electrode increases or remains constant along the first direction from a first thickness of the field electrode at the first distance to a second thickness of the field electrode at the second distance.

[0084] Example 13: Semiconductor device according to one of Examples 1 to 12, wherein the slope of the doping profile between the first distance and the second distance changes approximately proportionally to a ratio between the first thickness of the field dielectric to the second thickness of the field dielectric.

[0085] Example 14: Semiconductor device according to any one of Examples 1 to 13, wherein the thickness of the field dielectric increases along the first direction from a third thickness at a third distance from the first main surface to a fourth thickness at a fourth distance from the first main surface, wherein the difference between the fourth distance and the third distance along the first direction is at most 20% of the total height of the field electrode, wherein the fourth thickness is at least 1.1 times the third thickness, and wherein the slope of the doping profile changes along the first direction between the third distance and the fourth distance from the first main surface.

[0086] Example 15: Semiconductor device according to Example 14, wherein the slope of the doping profile between the third distance and the fourth distance changes approximately proportionally to a ratio between the third thickness of the field dielectric to the fourth thickness of the field dielectric.

[0087] Example 16: Method for manufacturing a semiconductor device comprising a semiconductor body with a first principal surface, the method comprising: growing a first part of a drift region of the semiconductor body over a substrate of the semiconductor body for a first period, wherein the growth of the first part comprises changing a concentration of dopants over the first period at a first rate; growing a second part of the drift region of the semiconductor body over the first part of the drift region for a second period, wherein the growth of the second part comprises changing a concentration of dopants over the second period at a second rate, the second rate being greater than the first rate; forming a trench in the semiconductor body, wherein the trench extends from the first principal surface into the semiconductor body along a first direction;and forming a field dielectric in the trench, wherein the thickness of the field dielectric increases along the first direction from a first thickness at a first distance from the first main surface to a second thickness at a second distance from the first main surface, wherein the first distance is adjacent to the second part of the drift region and wherein the second distance is adjacent to the first part of the drift region, the second thickness being at least 1.1 times the first thickness.

[0088] Example 17: A method for manufacturing a transistor device comprising a semiconductor body with a first principal surface, the method comprising: implanting dopants into a first part of a drift region of the semiconductor body, such that a doping profile in the first part of the drift region comprises at least a first slope; implanting dopants into a second part of the drift region, which is arranged above the first part of the drift region, such that a doping profile in the second part of the drift region comprises at least a second slope, wherein the at least one first slope is less than the at least one second slope; forming a trench in the semiconductor body, wherein the trench extends from the first principal surface into the semiconductor body along a first direction;and forming a field dielectric in the trench, wherein the thickness of the field dielectric increases along the first direction from a first thickness at a first distance from the first main surface to a second thickness at a second distance from the first main surface, wherein the first distance is adjacent to the second part of the drift region and wherein the second distance is adjacent to the first part of the drift region, the second thickness being at least 1.1 times the first thickness.

[0089] Example 18: Semiconductor device comprising: a semiconductor body with a first principal surface; and a trench formed in the semiconductor body, the trench extending from the first principal surface into the semiconductor body along a first direction, the trench comprising a field electrode and a field dielectric arranged between the field electrode and the semiconductor body, the field dielectric comprising a first thickness over a first height h1 of the field electrode and a second thickness over a second height h2 of the field electrode, and the field electrode having a total height h fp includes, where 0.1 < h1 / h fp < 0.8, 0.1 < h2 / h fp < 0.8 and (h1 + h2) / h fp< 0.9, wherein the semiconductor body includes a drift region, wherein the drift region includes a doping profile along the first direction, wherein a slope of the doping profile along the first direction changes between the first distance and the second distance from the first main surface.

[0090] Terms like "first," "second," and the like are used to describe different elements, regions, sections, etc., and are not intended to be restrictive. The same terms refer to the same elements throughout the description.

[0091] As used herein, the terms "possessing," "containing," "including," "comprising," and the like are open terms that indicate the presence of specified elements or features but do not exclude additional elements or features. The articles "a," "an," and "the" are intended to include both the plural and the singular unless the context clearly indicates otherwise.

Claims

[1] Semiconductor device (100; 200; 300; 400; 500), comprising: a semiconductor body (102) with a first principal surface (101); and a trench (110) formed in the semiconductor body (102), wherein the trench (110) extends from the first main surface (101) into the semiconductor body (102) along a first direction (z), wherein the trench comprises a field electrode (124) and a field dielectric (126), wherein the trench (110) has an upper area (110 u ), a lower range (110 l ) and an intermediate range (110 i )) includes, which between the upper area (110 u ) and the lower range (110 l ) is arranged, where the intermediate range (110 i )) is arranged between a first distance (d1) from the first main surface (101) and a second distance (d2) from the first main surface (101), where the difference between the second distance (d2) and the first distance (d1) along the first direction (z) is at most 20% of a total height (h) fp ) of the field electrode (124) is, wherein the field electrode (124) is separated from the upper area (110) u ) into the lower range (110 l ) of the trench (110) and the field electrode (124) extends at least between the first distance (d1) from the first main surface (101) and the second distance (d2) from the first main surface (101), wherein the field dielectric (126) is arranged between the field electrode (124) and the semiconductor body (102), wherein a thickness (t) of the field dielectric (124) increases along the first direction (z) from a first thickness (t1) at the first distance (d1) from the first main surface (101) to a second thickness (t2) at the second distance (d2) from the first main surface (101), where the second thickness (t2) is at least 1.1 times the first thickness (t1), wherein the semiconductor body (102) comprises a drift region (106), wherein the drift region (106) comprises a doping profile (1000) along the first direction (z), wherein a slope of the doping profile (1000) changes along the first direction between the first distance (d1) and the second distance (d2) from the first main surface (101), where the slope (S1) of the doping profile (1000) at the first distance (d1) is greater than the slope (S2) of the doping profile (1000) at the second distance (d2). [2] Semiconductor device (100; 200; 300; 400; 500) according to claim 1, where the difference between the second distance (d2) and the first distance (d1) along the first direction (z) is at most 15% of a total height (h) fp ) of the field electrode (124) is, where the second thickness (t2) is at least 1.2 times the first thickness (t1). [3] Semiconductor device (100; 200; 300; 400; 500) according to claim 1, where the difference between the second distance (d2) and the first distance (d1) along the first direction (z) is at most 10% of a total height (h) fp ) of the field electrode (124) is, where the second thickness (t2) is at least 1.15 times the first thickness (t1). [4] Semiconductor device (100; 500) according to claim 1, wherein the ratio of the second thickness (t2) of the field dielectric (126) to the first thickness (t1) of the field dielectric (126) is in a range between 1.5 and 2.5, and where a height (h ur ) of the field electrode (124) in the upper region (110 i ) between 0.75 times and 1.25 times a height (h lr ) of the field electrode (124) in the lower area (110 i )) lies. [5] Semiconductor device (100; 200; 300; 400; 500) according to claim 1, where a height (h) is defined along the first direction (z). ur ) of the field electrode (124) in the upper region (110 i ) more than 10% of the total height (h fp ) of the field electrode (124) is, and where a height (h) is defined along the first direction (z). lr ) of the field electrode (124) in the lower area (110 i ) more than 10% of the total height (h fp ) of the field electrode (124). [6] Semiconductor device (100; 200; 300; 400; 500) according to claim 4, where a height (h) is defined along the first direction (z). ur ) of the field electrode (124) in the upper region (110 i ) more than 25% of the total height (h fp ) of the field electrode (124) is, and where a height (h) is defined along the first direction (z). lr ) of the field electrode (124) in the lower area (110 i ) more than 25% of the total height (hfp ) of the field electrode (124). [7] Semiconductor device (100; 200; 500) according to any one of claims 1 to 6, wherein the trench (110) is elongated along a second direction (x), and wherein the trench (110) further comprises a gate electrode (112) which is arranged above the field electrode (124). [8] Semiconductor device (100; 500) according to any one of claims 1 to 7, wherein the thickness of the field electrode (124) decreases along the first direction (z) from a first thickness of the field electrode (124) at the first distance (d1) to a second thickness of the field electrode (124) at the second distance (d2). [9] Semiconductor device (200; 500) according to any one of claims 1 to 7, wherein the thickness of the field electrode (124) increases or remains constant along the first direction (z) from a first thickness of the field electrode (124) at the first distance (d1) to a second thickness of the field electrode (124) at the second distance (d2). [10] Semiconductor device (300; 400; 500) according to any one of claims 1 to 6, wherein the trench (110) has a column-like shape, and wherein the thickness of the field electrode (124) decreases along the first direction (z) from a first thickness of the field electrode (124) at the first distance (d1) to a second thickness of the field electrode (124) at the second distance (d2). [11] Semiconductor device (300; 400; 500) according to any one of claims 1 to 6, wherein the trench (110) has a column-like shape, and wherein the thickness of the field electrode (124) increases or remains constant along the first direction (z) from a first thickness of the field electrode (124) at the first distance (d1) to a second thickness of the field electrode (124) at the second distance (d2). [12] Semiconductor device (100; 200; 300; 400; 500) according to any one of claims 1 to 11, wherein the slope of the doping profile (1000) between the first distance (d1) and the second distance (d2) changes approximately proportionally to a ratio between the first thickness (t1) of the field dielectric (126) to the second thickness (t2) of the field dielectric (126). [13] Semiconductor device (100; 200; 300; 400; 500) according to any one of claims 1 to 12, wherein a thickness (t) of the field dielectric (124) increases along the first direction (z) from a third thickness (t3) at a third distance (d3) from the first main surface (101) to a fourth thickness (t4) at a fourth distance (d4) from the first main surface (101), where a difference (d) between the fourth distance (d4) and the third distance (d3) along the first direction (z) is at most 20% of the total height (h) fp ) of the field electrode (124) is, where the fourth thickness (t4) is at least 1.1 times the third thickness (t3), wherein a slope of the doping profile (1000) changes along the first direction between the third distance (d3) and the fourth distance (d4) from the first main surface (101). [14] Semiconductor device (100; 200; 300; 400; 500) according to claim 12, wherein the slope of the doping profile (1000) between the third distance (d3) and the fourth distance (d4) changes approximately proportionally to a ratio between the third thickness (t3) of the field dielectric (126) to the fourth thickness (t4) of the field dielectric (126). [15] Method (600) for manufacturing a semiconductor device (100; 200; 300; 400; 500) comprising a semiconductor body (102) with a first principal surface (101), the method comprising: Growth (610) of a first part of a drift region of the semiconductor body (102) over a substrate of the semiconductor body for a first period, wherein the growth of the first part comprises changing a concentration of dopants over the first period at a first rate; Growth (620) of a second part of the drift region of the semiconductor body (102) over the first part of the drift region for a second period, wherein the growth of the second part comprises changing a concentration of dopants over the second period at a second rate, wherein the second rate is greater than the first rate; Forming (630) a trench (110) in the semiconductor body (102), wherein the trench (110) extends from the first principal surface (101) into the semiconductor body (102) along a first direction (z); Forming (640) a field dielectric (126) in the trench (110), wherein a thickness (t) of the field dielectric (124) increases along the first direction (z) from a first thickness (t1) at a first distance (d1) from the first main surface (101) to a second thickness (t2) at a second distance (d2) from the first main surface (101), wherein the first distance (d1) borders the second part of the drift region and wherein the second distance (d2) borders the first part of the drift region, wherein the second thickness (t2) is at least 1.1 times the first thickness (t1); and Forming a field electrode (124) on the field dielectric, wherein the field electrode (124) extends at least between the first distance (d1) and the second distance (d2). [16] Method (700) for manufacturing a transistor device (100; 200; 300; 400; 500) comprising a semiconductor body (102) with a first principal surface (101), the method comprising: Implanting (710) dopants into a first part of a drift region of the semiconductor body (102) such that a doping profile in the first part of the drift region includes at least one first slope; Implanting (720) dopants into a second part of the drift region, which is arranged above the first part of the drift region, such that a doping profile in the second part of the drift region comprises at least one second slope, wherein the at least one first slope is less than the at least one second slope; Forming (730) a trench (110) in the semiconductor body (102), wherein the trench (110) extends from the first principal surface (101) into the semiconductor body (102) along a first direction (z); Forming (740) a field dielectric (126) in the trench (110), wherein a thickness (t) of the field dielectric (124) increases along the first direction (z) from a first thickness (t1) at a first distance (d1) from the first main surface (101) to a second thickness (t2) at a second distance (d2) from the first main surface (101), wherein the first distance (d1) adjoins the second part of the drift region and wherein the second distance (d2) adjoins the first part of the drift region, the second thickness (t2) being at least 1.1 times the first thickness (t1); and Forming a field electrode on the field dielectric, wherein the field electrode (124) extends at least between the first distance (d1) and the second distance (d2). [17] Semiconductor device (100; 200; 300; 400; 500), comprising: a semiconductor body (102) with a first principal surface (101); and a trench (110) formed in the semiconductor body (102), wherein the trench (110) extends from the first main surface (101) into the semiconductor body (102) along a first direction (z), wherein the trench comprises a field electrode (124) and a field dielectric (126) arranged between the field electrode (124) and the semiconductor body (102), wherein the field dielectric (126) comprises a first thickness (t1) over a first height h1 of the field electrode (124) and a second thickness (t2) over a second height h2 of the field electrode, wherein the field electrode (124) has a total height h fp exhibits where 0.1 < h1 / h fp < 0.8, 0.1 < h2 / h fp < 0.8 and (h1+h2) / h fp < 0.9, wherein the semiconductor body (102) comprises a drift region (106), wherein the drift region (106) comprises a doping profile (1000) along the first direction (z), wherein a slope of the doping profile (1000) changes along the first direction between the first distance (d1) and the second distance (d2) from the first main surface (101), and where the slope (S1) of the doping profile (1000) at the first distance (d1) is greater than the slope (S2) of the doping profile (1000) at the second distance (d2).

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