Semiconductor chip with vertical transistor device

Abstract

The application relates to a semiconductor chip (1) with a semiconductor body (10), wherein the semiconductor chip (1) comprises a vertical transistor device (20) and a current sensing transistor device (40), wherein the current sensing transistor device (40) is configured to detect an electric current through the vertical transistor device (20), and wherein an additional resistor (60) is integrated into the semiconductor chip (1) and is arranged on a drain side (40.2) of the current sensing transistor device (40).

Description

TECHNICAL AREA The present disclosure relates to a semiconductor chip with a semiconductor body comprising a vertical transistor device. BACKGROUND A vertical transistor device can have a source region on one side and a drain region on a second side of the semiconductor body. The semiconductor chip can additionally include a current-sensing transistor device, and the vertical transistor device and the current-sensing transistor device can be connected as a current mirror. In this circuit, the current is mirrored from one device to the other, e.g., a load current IL from the vertical transistor device to a sensing current IS in the current-sensing transistor device. The sensing current can be proportional to the load current, with a proportionality factor being given by a ratio between a dimension of the vertical transistor device and a dimension of the current-sensing transistor device.This size ratio can be equivalent to a ratio between the respective number of transistor cells and / or a ratio between the transistor areas. DE 10 2013 200 335 A1 relates to a circuit arrangement with a load transistor and a measuring transistor. SUMMARY Examples of the present application are directed to an advantageous semiconductor chip. In one embodiment, a semiconductor chip comprises a vertical transistor device having a source region and a drain region on opposite sides of a semiconductor body. The semiconductor chip further comprises a current-sensing transistor device having a sensing source region and a sensing drain region within the semiconductor body. The semiconductor chip further comprises an additional resistor integrated into the semiconductor chip and located on a drain side of the current-sensing transistor device. The additional resistor can maintain the vertical and current-sensing transistors in a balanced manner, for example, by improving the matching between the proportionality factor and the current ratio. The current ratio, i.e., IL / IS, is also known as the kILIS factor, which, in an ideal case, describes a predefined proportionality between the load current IL and the sensing current IS. However, the proportionality factor can vary, for example, due to current propagation within the current-sensing transistor device. The additional resistor can compensate for this current propagation within the sensing transistor, which may occur, for instance, in its drift region and / or substrate. The additional resistance on the drain side can enable stabilized compensation, for example, across different operating conditions. By comparison, compensation implemented on the source side might, in some cases, exhibit a stronger dependence on, for example, the temperature, gate voltage, or current level (the latter with a minor effect). Generally, the deviation of the current-to-size ratio can increase as the size of the current-sensing transistor decreases relative to the size of the vertical transistor device. Consequently, the compensation achieved with the additional resistance can enable increased accuracy and / or a smaller layout or size of the current-sensing transistor device, for example, to reduce losses associated with current measurement. Further embodiments and features are provided in the claims and throughout the entire disclosure. The individual features are to be disclosed independently of any specific claim category. The disclosure covers aspects of the device and components, as well as aspects of the process and use. For example, if a chip manufactured in a specific way is described, this also constitutes a disclosure of the corresponding manufacturing process, and vice versa. In general terms, embodiments of the present application aim to provide a current-sensing transistor device with an additional resistor on its drain side. The additional resistor can increase the resistance of the current-sensing transistor device by, for example, at least 5%. Possible upper limits are, for example, at most 200%, 100%, 50%, or 20%. The additional resistance is integrated into the semiconductor chip, e.g., into the semiconductor body and / or into a layer or layer stack arranged on the semiconductor body. With reference to the outer circumference of the semiconductor chip, the additional resistance can be located within it. In a current sensing transistor device, the drain side can begin at a transition from a drift region of the current sensing transistor to the sensing drain region, or at a transition from the body region of the current sensing transistor to the drift region of the current sensing transistor. For example, the drain side can begin at one end (e.g., the bottom end) of the body region of the current sensing transistor. The end (e.g., the bottom end) of the body region can be adjacent to the sensing drain region or have another region in between, such as a drift region of the current sensing transistor (the "sensing drift region," see below). In some embodiments, the "drain side" can be the point from which the drain region of the current-sensing transistor device extends within the semiconductor body (e.g., vertically downwards in the case of a vertical current-sensing transistor device). In other words, the "drain side" can be the top of the drain region and / or it can be located at a transition from a body region (of the current-sensing transistor device) or drift region (of the current-sensing transistor device) to the drain region (of the current-sensing transistor device). The current-sensing transistor device is configured to detect an electric current through the vertical transistor device, for example, by being connected as a current mirror or being configured (e.g., within the package) as a current mirror. The gate electrode of the vertical transistor device and the gate electrode of the current-sensing transistor device may be electrically connected within the chip (generally, they could be externally connected), for example, within the semiconductor body and / or in a layer or stack of layers on the semiconductor body. The drain region of the vertical transistor device and the detection drain region may be electrically connected via the additional resistance within the semiconductor chip, for example, within the semiconductor body and / or in a layer or stack of layers on it. The source and drain regions of the vertical transistor device are located on vertically opposite sides of the semiconductor body, with the "first side" also being referred to as the front and the "second side" as the back. A channel can be formed in a body region of the vertical transistor device by applying a voltage to the gate electrode. Although the transistor device as a whole is considered "vertical" due to its vertically opposite source and drain regions, a lateral channel is generally conceivable, for example, in the case of a gate region located on top of the body region (and a source region laterally adjacent to the latter). This is also intended to be included in the term "vertical transistor device."In certain embodiments, however, the gate area is arranged laterally next to the body area and the channel extends vertically next to a trench, see below for details. "Vertical" or "vertical" refers to the vertical direction, for example, perpendicular to a surface of the chip, such as the surface of a substrate or an epitaxial layer formed on the substrate. "Lateral" or "lateral" refers to the lateral directions perpendicular to the vertical direction, such as the orientation of the chip surface. An insulating layer may be placed on the first side of the semiconductor body, upon which one or more metallization layers may be formed. In detail, the additional resistance can be located at different points on the semiconductor chip / body and implemented in different ways, which is discussed in detail below. In one embodiment, at least a portion of the additional resistance is integrated into the semiconductor body beneath the drain side of the current-sensing transistor device. The semiconductor body may comprise a semiconductor substrate and optionally one or more epitaxial semiconductor layers formed on the semiconductor substrate. Referring to the "drain side" as discussed above, at least a portion of the resistance may be located in the drain region, for example, in the sensing drain region. In other words, at least a portion of the additional resistance may be formed within the semiconductor substrate. In one embodiment, the current-sensing transistor device includes a sensing drift region. In some examples, the sensing drift region may be formed in an epitaxial layer on the semiconductor substrate, such as the same epitaxial layer that may, for instance, include a drift region of the vertical transistor device. Increased resistance in the sensing drift region may be combined with increased resistance in the sensing drain region or the semiconductor substrate. In other words, a portion of the additional resistance may be added to each of the drift region and the drain region of the current-sensing transistor device. In one embodiment, at least part of the additional resistance is achieved by reducing the conductivity in the semiconductor body through the removal of current flow lines. For example, in a vertical cross-section through the current sensing transistor device, a current flow field can be observed on the drain side, i.e., a current flow field in the sensing drift and / or sensing drain region. As discussed above, a deviation in the proportionality factor or a mismatch of the devices can result from current propagation, such as a divergence of the current flow lines from the channel of the sensing device to the other side of the semiconductor body. Removing current flow lines from the current flow field reduces the conductivity and thereby adds additional resistance.Various options for removing current flow lines are discussed below, such as reducing conductivity by “cutting out” central and / or peripheral current flow lines. In one embodiment, the semiconductor chip comprises a backside metallization arranged on the second side of the semiconductor body. The backside metallization has a contact surface facing the second side of the semiconductor body, where an electrical contact is formed between the semiconductor body and the metallization. In one embodiment, the contact surface has a break beneath the current-sensing transistor device. Where the break is located, current flow lines can be removed or "cut out," as illustrated in Fig. 2. In other words, the break in the contact surface can "cut out" a direct vertical path downwards to the other side of the semiconductor body. From another perspective, to compensate for a potential mismatch resulting from current propagation, the current propagation can even be increased (thus lengthening the current path and resistance). The interruption, viewed in a vertical cross-section, may, for example, extend over at least 10% of the lateral width of the current-sensing transistor device. Further lower limits may be at least 50%, 100%, or 200%, and the interruption may extend over or even beyond the entire lateral width of the current-sensing transistor device. Considering a current-sensing transistor device that has a gate trench or trenches, the plane of this cross-sectional view may be perpendicular to a longitudinal direction of the gate trench(s). The lateral width may be taken across the active cells of the current-sensing transistor device. In one embodiment, the semiconductor chip includes an insulating element located on the second side of the semiconductor body, where the contact surface has the discontinuity. The insulating element can be formed in a single layer or a single layer stack deposited on the second side and structured to form the insulating element. Alternatively or additionally, the backside metallization can be structured, i.e., locally discontinuous, to form the discontinuous contact surface. In one embodiment, however, the backside metallization extends continuously over the insulating element, and the contact area is interrupted by the insulating element. In other words, the insulating element can be formed in a structured insulating layer or stack of structured insulating layers, over which the backside metallization can extend continuously, for example, to cover the entire backside. In the interrupted area, the insulating element can be continuous or structured. In other words, the interruption of the contact area can be a continuous region or it can also be structured. In one embodiment, the semiconductor chip comprises deep trench insulation. The deep trench insulation can extend from the first side of the semiconductor body into the semiconductor body, e.g., from the first side to the second side of the semiconductor body. An insulating trench of the deep trench insulation can be provided with an insulating filler or an insulating lining, for example, an insulating lining in combination with a filler that can be non-conductive or conductive (e.g., a silicon oxide lining and a polysilicon filler). The deep trench insulation can be arranged laterally between the vertical transistor device and the current-sensing transistor device. Viewed in a vertical cross-section, with the sectioning plane perpendicular to, for example, a gate trench or trenches of the devices, a first insulating trench can be arranged on a first lateral side of the current-sensing transistor device, and a second insulating trench can be arranged on a laterally opposite second side of the current-sensing transistor device. In other words, the current-sensing transistor device can be embedded in a cell array of the vertical transistor device, for example, with an insulating trench on each side between the current-sensing transistor device and the cell array. With reference to streamline removal, as discussed above, the deep trench insulation can cut away laterally propagating streamlines, for example,the outermost or lateral streamlines, see Fig. 5 for illustration. In one embodiment, the current-sensing transistor is laterally embedded by the deep trench insulation and vertically embedded by the insulating element. In other words, the deep trench insulation, together with the insulating element (i.e., backside insulation), forms an insulating basin. Viewed in a vertical cross-section, with the section plane, for example, perpendicular to a gate trench or trenches of the device, a first insulating trench may be arranged on one side of the current-sensing transistor device, and a second insulating trench may be arranged on the laterally opposite side of the current-sensing transistor device, with the insulating element extending the entire distance between the insulating trenches. In an alternative embodiment, although laterally embedded in the deep trench insulation, the drain region of the current-sensing transistor device can be contacted by a backside metallization on the second side of the semiconductor body within the current-sensing transistor device region. Laterally outside the current-sensing transistor device region, the same backside metallization can make electrical contact with the drain region of the vertical transistor device. In other words, the drain regions of the vertical and current-sensing transistor devices can be connected via the backside metallization, with the deep trench insulation adding the additional resistance. In this embodiment, an insulating element can extend beneath the deep trench insulation but have an opening beneath the current-sensing transistor device. Viewed in a vertical cross-section, the lateral width of this opening can be smaller than the lateral distance between the deep trenches enclosing the current-sensing transistor device. This lateral width of the opening can be used to adjust the additional resistance. Alternatively or additionally, the opening, and conversely, a contact surface formed within the opening, can be structured, for example, into a plurality of sub-openings (with a regular or irregular pattern). In one embodiment, the sensing source region is arranged on the first side of the semiconductor body, and the sensing drain region is arranged on the second side of the semiconductor body. In other words, the current sensing transistor device can be a vertical device. It can additionally include a sensing gate trench extending from the first side into the semiconductor body. A sensing body region can be arranged adjacent to the sensing gate trench, with a sensing gate electrode located in the sensing gate trench and capacitively coupled to a channel region formed in the body region. Below the sensing body region, the current sensing transistor device can include a sensing drift region.It can further comprise a detection field electrode that capacitively couples with the detection drift area, the detection field electrode being arranged, for example, in the detection gate trench below the detection gate electrode. The sensing gate electrode can have an elongated shape, for example, forming a striped pattern as seen in a vertical top view. The sensing field electrode can also have a striped shape, i.e., be a field plate located below the sensing gate electrode or in a separate trench. Alternatively, the sensing field electrode can have a column or needle shape, for example, arranged in a needle-shaped trench. Regardless of these details, the current sensing transistor device and the vertical transistor device can have the same cell design, for example, being manufactured in concurrent process steps. Providing the devices with essentially the same design can allow for improved device customization. In one embodiment, the semiconductor chip comprises a first vertical contact element located in a region of the current-sensing transistor device and extending from the first side into the semiconductor body. The first vertical contact element can establish electrical contact with the sensing drain region and connect it to the first side of the semiconductor body. In other words, current can be conducted along an additional vertical current path through the semiconductor body, forming at least part of the additional resistance. The first vertical contact element can be combined with the isolation tray discussed above, for example, by being arranged laterally within the isolation tray. In addition to the source and drain regions located on opposite sides of the semiconductor body, the vertical transistor device may include a body region below the source region. A gate trench may extend into the semiconductor body from the first side, with a gate electrode located in the gate trench and capacitively coupled to a channel region formed in the body region. A drift region may be located below the body region, with the vertical device, for example, including a field electrode that capacitively couples to the drift region. As discussed above for the current-sensing transistor device, the field electrode may have an elongated or needle / pillar shape. In the exemplary embodiments, an elongated field plate is located in the gate trench below the elongated gate electrode. In one embodiment, at least part of the additional resistance is integrated into the drift region of the vertical transistor device. This can, for example, be an additional current path extending through the drift region to the drain region of the vertical device. In other words, the drain region of the current-sensing transistor device can be electrically connected to the drain region of the vertical transistor device via the drift region of the vertical transistor device. In one embodiment, the semiconductor chip comprises a second vertical contact element located in the region of the vertical transistor device and extending from the first side into the semiconductor body. The first and second vertical contact elements can be electrically connected to each other on the first side of the semiconductor body, for example, via a front-side metallization. The drain regions of the transistor devices can be electrically connected to each other via the vertical contact elements, with the first vertical contact element establishing electrical contact with the drain region of the current-sensing transistor device and the second vertical contact element establishing electrical contact with the drain region of the vertical transistor device. In one embodiment, a vertical contact element or the vertical contact elements comprise a sink implantation. The sink implantation can override a body implantation that covers the entire front face. For example, the sink can have the same doping type as the drift region of the vertical transistor device, i.e., the same polarity. It can also have a higher doping concentration than the drift region of the vertical transistor device, e.g., at least 10 times greater (with a possible upper limit of 1000 times). Regardless of these details, the sink implantation can form a lower section of the respective vertical contact element, e.g., in combination with a contact plug that cuts an insulating layer located on the first side of the semiconductor body and forms an upper section of the vertical contact element. In one embodiment, a vertical contact element or the vertical contact elements comprise a source doping. The body doping may be interrupted where the source doping is located. The source doping may consist of the same doping type as the source region of the vertical device and / or the sensing source region, e.g., a first doping type. The source doping may form a portion of the respective vertical contact element, e.g., in combination with a contact plug that penetrates an insulating layer located on the first side of the semiconductor body and forms another portion of the vertical contact element. The source doping may be shallower than the contact plug, such that the contact plug penetrates the source doping vertically. In one embodiment, the additional resistor has a first vertical section adjacent to the current-sensing transistor device, for example, in the drift region next to it. It can further comprise a second vertical section adjacent to the vertical transistor device, for example, in the drift region next to it. It can also comprise a horizontal section, which may be located in the semiconductor substrate. The first vertical section can extend through an epitaxial layer that encompasses the drift region of the current-sensing transistor device, and the second vertical section can extend through an epitaxial layer that encompasses the drift region of the vertical transistor device and may additionally extend through the substrate of the vertical transistor device. The drift regions of the devices can be formed in the same epitaxial layer.A deep trench isolation can be arranged laterally between the first and second vertical sections, see above for details. In one embodiment, the semiconductor chip comprises a backside metallization arranged on the second side of the semiconductor body. The backside metallization can be structured, i.e., it can have a discontinuity in a region of the current-sensing transistor device. A lateral edge of the backside metallization, which laterally defines the discontinuity, can be arranged with a lateral offset relative to the current-sensing transistor device, for example, to a deep trench insulation in which the current-sensing transistor device is laterally embedded. The lateral offset between the side edge of the backside metallization and the deep trench insulation can cause the second vertical section of the additional resistance to exhibit a diagonal component within the semiconductor body. In other words, a lateral component is added to the vertical component, which can (further) lengthen the current path. Increasing the lateral offset can increase the lateral component, while decreasing the lateral offset can decrease it, thus allowing for appropriate adjustment of the additional resistance. In one embodiment, a method for designing a semiconductor chip includes arranging the transistor devices and adding the additional resistance on the drain side of the current-sensing transistor device. As discussed in detail above, the additional resistance can compensate for current propagation in the current-sensing transistor device, for example, to set a desired proportionality factor. In one embodiment, a method for fabricating the semiconductor chip comprises forming the vertical transistor device, forming the current-sensing transistor device, and forming the additional resistor. As described in detail above, the process steps can be performed simultaneously, at least to some extent. For example, the vertical transistor device and the current-sensing transistor device can be formed concurrently. Prior to fabricating the semiconductor chip, the additional resistor can be selected or adjusted as described above. BRIEF DESCRIPTION OF THE DRAWINGS The semiconductor chip with the vertical transistor device and the current-sensing transistor device is explained in more detail below using exemplary embodiments. The individual features can also be relevant in different combinations. Fig. 1 shows a vertical transistor device and a current-sensing transistor device connected as a current mirror; Fig. 2 shows a cross-section through a semiconductor chip comprising a vertical transistor device and a current-sensing transistor device; Fig. 3 shows a schematic vertical top view of the semiconductor chip of Fig. 2; Fig. 4 illustrates another semiconductor chip with a vertical transistor device and a current-sensing transistor device in a vertical cross-section; Fig. 5 shows another semiconductor chip with a vertical transistor device and a current-sensing transistor device in a vertical cross-section; Fig.Figure 6 shows a schematic vertical top view of the semiconductor chip of Figure 5; Figure 7 shows another semiconductor chip with a vertical transistor array and a current sensing transistor array in a vertical cross-section; Figure 8 shows a schematic vertical top view of the semiconductor chip of Figure 7; Figure 9 shows another semiconductor chip with a vertical transistor array and a current sensing transistor array in a vertical cross-section; Figure 10 shows another semiconductor chip with a vertical transistor array and a current sensing transistor array in a vertical cross-section; Figure 11 shows another semiconductor chip with a vertical transistor array and a current sensing transistor array in a vertical cross-section; Figure 12 summarizes some design and manufacturing steps. DETAILED DESCRIPTION Fig. 1 shows a circuit diagram with a vertical transistor device 20 and a current sensing transistor device 40 connected as a current mirror. A gate terminal 31.1 of the vertical transistor device 20 is connected to a sensing gate terminal 51.1 of the current sensing transistor device 40, e.g., to the same gate pad 231. Furthermore, the vertical transistor device 20 and the current sensing transistor device 40 are connected at their respective drain sides 20.2 and 40.2 to a common drain contact 220. When a current IL flows through the vertical transistor device 20, i.e., between a source pad 221 and the drain pad 220, a corresponding sensing current IS is mirrored to the current sensing transistor device 40. The sensing current IS can be detected at a sensing source pad 241 (which is a source contact of the current sensing transistor device 40). The current ratio IL / IS, also known as the kILIS factor, is essentially determined by the size ratio of the vertical transistor device 20 and the current sensing transistor device 40. However, the proportionality factor can vary, for example, due to current expansion in the current sensing transistor device 40. To compensate for this, an additional resistor 60 is arranged on the drain side 40.2 of the current sensing transistor device 40, i.e., between the drain side 40.2 and the drain contact 220. In the illustrated embodiment, all circuit elements are integrated into a semiconductor chip 1. The vertical cross-section of Fig. 2 illustrates the vertical transistor device 20 and the current sensing transistor device 40, which are integrated into the same semiconductor chip 1. The vertical transistor device 20 comprises a source region 21, which is arranged on a first side 10.1 of a semiconductor body 10, and a drain region 22, which is arranged on a second side 10.2 of the semiconductor body 10. Below the source region 21, a body region 23 is arranged laterally next to a gate groove 30. A gate electrode 31 is arranged in the gate groove 30 and is capacitively coupled to the body region 23. A drift region 24 is arranged vertically between the body region 23 and the drain region 22. The drift region 24 is made of the same doping type as the drain region 22, but with a lower doping concentration. The source region 21, the drift region 24, and the drain region 22 can be made of a first doping type, while the body region 23 is made of a second doping type. In the example shown, the first type is n-type and the second type is p-type. A field electrode 35 is arranged in the gate trench 30 below the gate electrode 31 and is capacitively coupled to the drift region 24. The current sensing transistor device 40 comprises a sensing source region 41, located on the first side 10.1, and a sensing drain region 42, located on the second side 10.2 of the semiconductor body 10. A sensing body region 43 is located laterally adjacent to a sensing gate trench 50 below the sensing source region 41. A sensing gate electrode 51 is located in the sensing gate trench 50 and is capacitively coupled to the sensing body region 43. A sensing drift region 44 is located vertically between the sensing body region 43 and the sensing drain region 42. In the example shown, the capture source area 41, the capture drift area 44 and the capture drain area 42 are made from a first doping type, wherein the capture body area 43 is made from a second doping type, where the first type can be n-type and the second type can be p-type.In the detection gate trench 50, a detection field electrode 55 is arranged below the detection gate electrode 51, wherein the detection field electrode 55 couples capacitively with the detection drift area 44. A backside metallization 80 is arranged on the second side 10.2 of the semiconductor body 10. It has a contact surface 85 facing the semiconductor body 10. In the illustrated embodiment, the contact surface 85 has an open section 86 beneath the current sensing transistor device 40. The open section 86 adds the additional resistance 60 to the drain side 40.2 of the current sensing transistor device 40. The drain side (40.2) can begin at a transition from a drift region (44) of the current sensing transistor device (40) to the sensing drain region (42) or at a transition from the body region (43) of the current sensing transistor device (40) to the drift region (44) of the current sensing transistor device (40). Taking into account a flux field with current flux lines 70.1, 70.2 in the semiconductor body 10, only the outer current flux lines 70.2 extend to the backside metallization 80, whereas the inner current flux lines 70.1 are cut off by the interruption 86 (shown as dashed lines). In the embodiment of Fig. 2, the interruption 86 extends over and across the entire lateral width w of the current sensing transistor device 40. By adjusting the lateral extent of the interruption 86, the additional resistance 60 can be adjusted; it can be increased by increasing the extent of the interruption 86. Fig. 3 illustrates a current sensing transistor device 40 embedded in a vertical transistor device 20 in a schematic top view. For the current sensing transistor device 40, the current sensing grooves are illustrated as parallel strips. Apart from the different number of grooves, this embodiment corresponds to the cross-section of Fig. 2, see section plane AA. At one lateral end of the sensing gate grooves 50, the respective sensing gate electrodes (not shown here) are connected to the gate pad 231 via the sensing gate terminal 51.1 (which is a vertical connection). At the opposite lateral end, the sensing field electrodes are connected to the source pad 221 via a sensing field electrode terminal 55.1 (the vertical connection contacts the respective sensing field electrode next to the sensing gate electrode). A respective sensing source terminal 41 is also provided.1 the sensing source areas (labeled in Fig. 2) are each connected to the current sensing pad 241 (the sensing source connection 41.1 is also labelled in Fig. 2). The vertical cross-section of Fig. 4 illustrates a vertical transistor device 20 and a current-sensing transistor device 40 integrated into the same semiconductor chip 1. The design is essentially the same as that discussed in detail with reference to Fig. 2. In general, throughout this disclosure, the same reference numerals denote the same elements or elements with the same function. Reference is also made to the descriptions of the other figures, and the following description mainly highlights the differences. The additional resistance 60 is again added by a break 86 in the contact surface 85, which interrupts the internal current flow lines 70.1. In the embodiment of Fig. 4, the break 86 is realized by an insulating element 90, which is arranged on the second side 10.2 of the semiconductor body 10. The insulating element 90 is deposited and structured prior to the deposition of the backside metallization 80, thereby locally interrupting the contact surface 85. The backside metallization 80 itself can extend uninterrupted, i.e., as an unstructured continuous layer. In the embodiment of Fig. 5, the outer current flow lines 70.2 are cut out, whereas the inner current flow lines 70.1 extend to the backside metallization 80. This is achieved with a deep trench insulation 100, comprising a first insulation trench 101 and a second insulation trench 102. The insulation trenches 101, 102 each extend from the first side 10.1 to the second side 10.2 of the semiconductor body 10. They are filled with a non-conductive lining 101.1, 102.1 and a conductive filler 101.2, 102.2, with an insulating element 90.1, 90.2 arranged under each insulation trench 101, 102. Within the semiconductor body 10, the vertical transistor device 20 and the current sensing transistor device 40 are isolated from each other by the deep trench insulation 100, but the backside metallization 80 electrically connects the drain region 22 and the sensing drain region 42. Fig. 6 shows an embodiment with a deep trench insulation 100 between the vertical transistor device 20 and the current sensing transistor device 40 in a schematic vertical top view. Except for the number of sensing gate trenches 50, it corresponds to the sectional view of Fig. 5, see section plane BB. The deep trench insulation 100 is arranged laterally between the vertical transistor device 20 and the current sensing transistor device 40. Viewed from a vertical top view, the deep trench insulation 100 can surround the current sensing transistor device 40, i.e., enclose it on each side. For further connection details of the current sensing transistor device 40, reference is made to Fig. 3. In the embodiment of Fig. 7, a deep trench insulation 100 is combined with an insulating element 90, which is arranged on the second side 10.2 of the semiconductor body 10. The current sensing transistor device 40 is embedded laterally and vertically in this insulation trench; the sensing drain area 42 is not connected to the backside metallization 80 in the area of ​​the current sensing transistor device 40. The current path is extended on the drain side 40.2 of the current sensing transistor device 40. The additional resistor 60 has a first horizontal section 170 in the sensing drain area 42, i.e., in the semiconductor substrate 11. It further has a first vertical section 171 adjacent to the current sensing transistor device 40, i.e., between the sensing drain area 42 and a first vertical contact element 110. It also has a second vertical section 172 adjacent to the vertical transistor device 20, i.e., between a second vertical contact element 120 and the drain area 22 or the backside metallization 80. The first vertical contact element 110 is arranged inside the insulation tray, specifically in a region 240 of the current sensing transistor device 40. The second vertical contact element 120 is arranged outside the insulation tray, i.e., in a region 220 of the vertical transistor device 20. In the embodiment of Fig. 7, the vertical contact elements 110, 120 each comprise a sink implantation 115, 125. Via a respective contact plug 116, 126, they are connected to a terminal pad 127, which electrically connects the first and second vertical sections 171, 172 of the additional resistor 60. Fig. 8 illustrates such an embodiment in a schematic vertical top view, with the section plane CC of Fig. 7 indicated. The connection pad 127 is arranged between the area 220 of the vertical transistor device and the area 240 of the current sensing transistor device 40, with the deep trench insulation 100 extending beneath the connection pad 127. For further connection details, reference is made to Fig. 3. The embodiment of Fig. 9 corresponds essentially to that discussed with reference to Fig. 7 (and Fig. 8). It differs in that the backside metallization 80 is structured, namely provided with a break 81 in the region 240 of the current sensing transistor device 40. A lateral edge 80.1 of the backside metallization 80 is arranged with a lateral offset 83 to the deep trench insulation 100. Consequently, the second vertical section 172 of the additional resistor 60 has a diagonal component in the semiconductor body 10. In other words, it has a lateral component in addition to the vertical component, which further extends the current path. The embodiment shown in Fig. 10 corresponds essentially to that shown in Fig. 7, and the embodiment shown in Fig. 11 corresponds essentially to that shown in Fig. 9. They differ in the design of the vertical contact elements 110, 120. In Figs. 10 and 11, the vertical contact elements 110, 120 each comprise a source doping 111, 121 into which the respective contact plug 116, 126 extends. The body doping is interrupted where each source doping 111, 121 is located. Fig. 12 summarizes some design and fabrication steps in a flowchart. A method for designing the semiconductor chip may include arranging 300 the vertical transistor device, arranging 301 the current sensing transistor device, and adding 302 the additional resistor to the drain side of the current sensing transistor device. A subsequent method for fabricating the semiconductor chip may include forming 400 the vertical transistor device, forming 401 the current sensing transistor device, and forming 403 the additional resistor. Although illustrated as a sequence, the respective process steps can occur concurrently, for example, in the case of device cells that have the same design and are monolithically integrated into the same chip.

Claims

Semiconductor chip (1) with a semiconductor body (10), wherein the semiconductor chip (1) comprises: a vertical transistor device (20), the vertical transistor device (20) comprising: a source region (21) on a first side (10.1) of the semiconductor body (10) and a drain region (22) on a second side (10.2) of the semiconductor body (10); a current sensing transistor device (40), the current sensing transistor device (40) comprising: a sensing source region (41) and a sensing drain region (42) in the semiconductor body (10); an additional resistor (60) integrated into the semiconductor chip (1); wherein the current sensing transistor device (40) is configured to sensing an electric current through the vertical transistor device (20), and wherein the additional resistor (60) is arranged on a drain side (40.2) of the current sensing transistor device (40). Semiconductor chip (1) according to claim 1, wherein at least a part of the additional resistance (60) is integrated into the semiconductor body (10) below the drain side (40.2) of the current sensing transistor device (40). Semiconductor chip (1) according to claim 1 or 2, wherein at least a part of the additional resistance (60) is integrated into the semiconductor body (10) in a sensing drift region (44) of the current sensing transistor device (40). Semiconductor chip (1) according to claim 2 or 3, wherein at least part of the additional resistance (60) is realized by a reduced conductivity in the semiconductor body (10) due to a removal of current flow lines in the semiconductor body (10). Semiconductor chip (1) according to one of the preceding claims, wherein the drain side (40.2) begins at a transition from a drift region (44) of the current sensing transistor device (40) to the sensing drain region (42); or wherein the drain side (40.2) begins at a transition from the body region (43) of the current sensing transistor device (40) to the drift region (44) of the current sensing transistor device (40). Semiconductor chip (1) according to one of the preceding claims, comprising: a backside metallization (80); wherein the backside metallization (80) is arranged on the second side (10.2) of the semiconductor body (10) and has a contact surface (85) to the semiconductor body (10), wherein the contact surface (85) has an interruption (86) under the current sensing transistor device (20). Semiconductor chip (1) according to claim 6, wherein the interruption (86), viewed in a vertical cross-section, extends over at least 10% of a lateral width (w) of the current sensing transistor device (40). Semiconductor chip (1) according to claim 6 or 7, comprising: an insulating element (90); wherein the insulating element (90) is arranged on the second side (10.2) of the semiconductor body (10), where the contact surface (85) has the interruption (86). Semiconductor chip (1) according to claim 8, wherein the backside metallization (80) extends continuously over the insulating element (90), wherein the contact surface (85) is interrupted by the insulating element (90). Semiconductor chip (1) according to one of the preceding claims, comprising: a deep trench insulation (100), wherein the deep trench insulation (100) is arranged laterally between the vertical transistor device (20) and the current measuring transistor device (40). Semiconductor chip (1) according to claim 10 in combination with claim 8 or 9, wherein, viewed in a vertical cross-section, the current sensing transistor device (40) is embedded laterally and vertically by the deep trench insulation (100) and the insulating element (90). Semiconductor chip (1) according to claims 9 and 10, wherein the insulating element (90) extends below the deep trench insulation (100) but has an opening (95) below the current sensing transistor device (40). Semiconductor chip (1) according to one of the preceding claims, wherein the sensing source region (41) is arranged on the first side (10.1) of the semiconductor body (10) and the sensing drain region (42) is arranged on the second side (10.2) of the semiconductor body (10), wherein the current sensing transistor device (40) further comprises: a sensing gate trench (50) extending from the first side (10.1) into the semiconductor body (10); a sensing body region (43) adjacent to the sensing gate trench (50). Semiconductor chip (1) according to claim 13 in combination with claim 11, comprising: a first vertical contact element (110) extending in a region (240) of the current sensing transistor device (40) from the first side (10.1) into the semiconductor body (10); wherein the first vertical contact element (110) establishes electrical contact with the sensing drain region (42) and connects the sensing drain region (42) with the first side (10.1) of the semiconductor body (10). Semiconductor chip (1) according to one of the preceding claims, wherein at least a part of the additional resistance (60) is integrated into a drift region (24) of the vertical transistor device (20). Semiconductor chip (1) according to claims 14 and 15, comprising: a second vertical contact element (120) extending from the first side into the semiconductor body (10) in a region (220) of the vertical transistor device (20); wherein the first vertical contact element (110) and the second vertical contact element (120) are electrically connected to each other, and wherein the second vertical contact element (120) establishes electrical contact with the drain region (22) of the vertical transistor device (20) and electrically connects it to the sensing drain region (42). Semiconductor chip (1) according to claim 14 or 16, wherein at least one vertical contact element (110, 120) comprises a sink implantation (115, 125). Semiconductor chip (1) according to claim 14 or 16, wherein at least one vertical contact element (110, 120) comprises a source doping (111, 121). Semiconductor chip (1) according to one of the preceding claims, wherein the additional resistance (60) between the drain region (22) of the vertical transistor device (20) and the drain side (40.2) of the current sensing transistor device (40) comprises: - a first horizontal section (170) in a semiconductor substrate (11); - a first vertical section (171) adjacent to the current sensing transistor device (40); - a second vertical section (172) adjacent to the vertical transistor device (20). Semiconductor chip (1) according to claim 19 in combination with claim 10, comprising: a backside metallization (80); wherein the backside metallization (80) has a break (81) in a region (240) of the current sensing transistor device (40), wherein a lateral edge (80.1) of the backside metallization (80) defining the break (81) is arranged with a lateral offset (83) to the deep trench insulation (100), wherein the second vertical section (172) of the resistor (60) has a diagonal component in the semiconductor body (10). Method for designing the semiconductor chip (1) according to one of the preceding claims, wherein the method comprises: - arranging the vertical transistor device (20); - arranging the current sensing transistor device (40); - adding the additional resistor (60) on the drain side (40.2) of the current sensing transistor device (40). Method for manufacturing the semiconductor chip (1) according to any one of claims 1 to 20, wherein the method comprises: - forming the vertical transistor device (20); - forming the current sensing transistor device (40); - forming the additional resistor (60).

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