Semiconductor transistor device and manufacturing method thereof

Abstract

The present invention relates to a semiconductor transistor device (1), comprising: a source region (2); a body region (3), which includes a vertical channel region (3.1); a drain region (4); a gate region (6), which is laterally located next to the channel region (3.1); a body contact region (7) formed by doping; a diffusion barrier layer (20.1); and a conductive region (8) formed of a conductive material, wherein the body contact region (7) electrically contacts the body region (3), the diffusion barrier layer (20.1) is arranged between them, and wherein the doping of the body contact region (7) has the same conductivity type as the doping of the body region (3) but has a higher concentration, and wherein the conductive region (8) has a contact region (8.1) which forms an electrical contact with the body contact region (7), the contact region (8.1) of the conductive region (8) being arranged vertically above the upper end (25.1) of the channel region (3.1).

Description

Technical Field

[0001] The present invention relates to a semiconductor transistor device, comprising a vertical channel region formed in a body region and a gate region laterally located beside the channel region. Background Art

[0002] In a vertical field-effect transistor, a vertical channel region is formed in the body region. A gate region, comprising a gate interlayer dielectric and a gate electrode, is laterally arranged adjacent thereto. In this channel region, a channel electrically connecting the source and drain regions is formed or can be formed, which can be controlled by applying a voltage to the gate electrode. To avoid a floating body region, it is electrically contacted. For example, the body region can be short-circuited to the source region to eliminate intrinsic parasitic npn transistors, particularly in power devices. Summary of the Invention

[0003] An object of the present application is to provide a vertical transistor device with improved characteristics and a method of manufacturing such a device.

[0004] This object is achieved by the device of claim 1 and, in addition, by the method of claim 10. The device includes a body contact region formed by doping of the same conductivity type as the body region but with a higher concentration. The body region can be electrically contacted via the body contact region, with a diffusion barrier layer disposed between these regions. This can limit outdiffusion of high-dose implants, thereby allowing, for example, relatively precise positioning of the body contact region relative to the body region, for example, close to the channel region. This can be advantageous in terms of device characteristics, as will be described in detail below.

[0005] In addition, the device includes a conductive region formed by a conductive material, such as a metal material filler, such as a tungsten plug. An electrical contact is formed with the body contact region via a contact region of the conductive region. The contact region is arranged vertically above the upper end of the channel region. Simply put, the conductive region is arranged above the body contact region and does not extend downward into the body region. Vice versa, the body contact region arranged below the conductive region may have a certain vertical extension, for example, at least the height of the vertical channel region. This may be advantageous, for example, in terms of contact formation between the conductive region and the body contact region, i.e., allowing reliable contact while avoiding leakage, as detailed below.

[0006] Further embodiments and features are provided in the present description and in the dependent claims. Wherein individual features will be disclosed independently of a particular claim class, the present disclosure relates to apparatus and device aspects, but also to method and use aspects. For example, if a device manufactured in a particular way is described, this is also a disclosure of the corresponding manufacturing process, and vice versa. In general, the idea of ​​the present application is to provide a semiconductor device, in particular a field effect transistor, wherein a body contact region has a higher doping concentration than the body region, the body contact region being defined by a diffusion barrier structure comprising one or more diffusion barrier layers.

[0007] The source region and the drain region of the device are of a first conductivity type, and the body region and the body contact region are of a second conductivity type opposite to the first conductivity type. As a power device, the transistor may include a drift region vertically between the body region and the drain region, wherein the drift region has the same first conductivity type as the drain region, but has a lower doping than the drain region. In the embodiment shown, the first conductivity type is n-type and the second conductivity type is p-type. The dopant concentration in the body contact region may be significantly greater than the dopant concentration in the body region, for example, greater than at least one order of magnitude, with typical values ​​being, for example, 2-3 orders of magnitude. The doping concentration in the body contact region may be, for example, at least 1E19 cm³, in particular at least 5E19 cm³ or 1E20 cm³, with possible upper limits being, for example, 1E21 cm³ or 5E20 cm³.

[0008] As mentioned above, the conductive region can be, for example, a metal filler. This filler can be deposited into a contact hole etched into the interlayer dielectric covering the body contact region, see below. Over its vertical extension, the conductive region can be formed from the same continuous material (bulk material), for example, as a tungsten plug. The bulk material of the conductive region forms the contact region, i.e., at the lower end of the conductive region. In particular, the lower end of the tungsten plug can form the contact region. The contact region forms an electrical contact toward the body contact region and does not have to rest directly adjacent to the body contact region. To ensure low-ohmic contact, a silicide layer can be arranged between them, for example. However, the vertical distance between the contact region and the body contact region will remain relatively small, with a possible upper limit of, for example, no more than 100 nm, 80 nm, 60 nm, or 30 nm (with a lower limit of, for example, at least 5 nm or 10 nm).

[0009] The gate region includes a gate electrode and a gate dielectric, in particular a gate oxide, such as silicon oxide. The gate electrode is the conductive portion of the gate region that is capacitively coupled to the channel region via the gate dielectric. The gate electrode can be made of, for example, metal or polysilicon. The gate region can be arranged in a gate trench etched into the silicon material (the gate dielectric can be formed at the sidewalls of the trench, and the gate electrode can be deposited into the trench, thereby at least partially filling it). Optionally, a field plate can be arranged in the gate trench below the gate electrode (split gate), isolated from it by an interlayer dielectric.

[0010] As an alternative or supplement to such a separate gate, the device can include a field electrode region that extends vertically into the drift region and is formed in a field electrode trench (separated from the gate trench). As can be seen in the cross-sectional view, the field electrode and gate trenches can alternate in the horizontal direction. The field electrode trenches can be a strip-like structure extending parallel to the gate trenches. Alternatively, the field electrode trenches can be needle-shaped trenches, with the field electrode region having a mirror or columnar shape. In this case, the gate trenches can form a cross or lattice pattern as seen in the top view, with the needle-shaped trenches arranged in the spaces between them.

[0011] The "vertical" direction is at right angles to the surface of a layer of the device, such as the surface of a silicon substrate and / or the surface of an epitaxial layer (deposited on a substrate) and / or the surface of an interlayer dielectric on which the front side metallization is deposited and / or the surface of the front side metallization itself. The horizontal / lateral direction is at right angles to the vertical direction, such as accessing the device / chip area laterally / horizontally. "Up" and "down" refer to the vertical direction, with vertical trenches extending, for example, from the upper surface downwards into the silicon material in the vertical direction. "Vertically above / below" means being at a higher level / lower level relative to the vertical direction (generally, this should not imply alignment in the vertical direction).

[0012] At the front side of the device, above the source / drain / channel region, a front side metallization, such as a combined source / body contact, may be provided. The drain contact may be provided at the back side of the device. Alternatively, the drain connection may be made by vertical conduction, such as via n + The sinker region is routed from the bottom of the drift region to the front side of the device. In this case, a separate front-side metal contact is provided. As a power device, the transistor may have a breakdown voltage of at least 10V, 20V, 30V, or 40V, with possible upper limits not exceeding 800V, 600V, 400V, 200V, or 100V, for example.

[0013] In one embodiment, a contact region of the conductive region forming an electrical contact toward the body contact region is arranged at the upper end of the source region. In this case, the conductive region can be formed above the body / source region without etching into the body contact region material (e.g., epitaxially grown silicon, see below) deposited after forming the diffusion barrier layer. Even though the diffusion barrier layer and body contact region formation may involve prior etching of a body contact trench, this may provide better or easier position control than etching a relatively narrow trench into the body contact region later. The vertical distance between the contact region and the upper end of the source region may, for example, be no greater than 50 nm or 20 nm (they may also be located at exactly the same height).

[0014] In one embodiment, the contact region of the conductive region lies entirely in a horizontal plane. In other words, the contact region is flat and extends horizontally. The horizontal plane is vertically above the upper end of the channel region, particularly at the upper end of the source region. However, in general, the contact region may also extend over a step created, for example, by deposition of body contact material.

[0015] In one embodiment, the body contact region is laterally positioned adjacent to the body region having a vertical channel region. Consequently, the diffusion barrier layer disposed between the body region and the body contact region extends vertically (as seen in vertical cross-section). Nevertheless, the diffusion barrier structure as a whole can include a horizontal diffusion barrier layer, as will be seen in detail below. By positioning the body contact region laterally adjacent to the body / channel region, high-dose implants can be placed close to the channel, which can be advantageous in terms of shielding it from the high potential of the drain. Conversely, the defined lateral positioning achieved by the diffusion barrier layer can help maintain a minimum distance to prevent channel pinch-off, which could, for example, lead to a strong dependence of the threshold voltage.

[0016] At least a lower portion of the body contact region is located adjacent to the channel region; depending on the height of the body contact region, its upper portion may extend further upward. In one embodiment, the diffusion barrier layer and the body contact region, i.e., at least its lower portion, extend vertically across the entire height of the channel region. In other words, the body contact region electrically contacts the body region (with the diffusion barrier layer interposed therebetween) across the entire height of the channel region.

[0017] In one embodiment, the diffusion barrier layer is arranged at a lateral distance of no more than 80 nm from the channel region, with a further possible upper limit of no more than 70 nm, 60 nm, or even only 55 nm. A possible lower limit of the lateral distance is, for example, at least 35 nm, 40 nm, or 45 nm. The channel region can, for example, have a vertical height of a maximum of 100 nm, with further possible upper limits being, for example, no more than 90 nm, 80 nm, 70 nm, or 60 nm. A possible lower limit of the vertical channel height is, for example, at least 30 nm or 35 nm.

[0018] As already mentioned, the diffusion barrier layer can be part of a diffusion barrier structure that also delimits the body contact region in other directions. Assuming that the diffusion barrier layer between the body region and the body contact region extends vertically, i.e., is arranged laterally alongside the body region, the diffusion barrier structure can include an additional barrier layer that extends horizontally and delimits the body contact region vertically downward. In particular, this horizontal diffusion barrier layer can be formed directly on the upper surface of the drift region. In other words, the body region does not extend below the body contact region, and the body contact region is located above the drift region (with the horizontal barrier layer in between). The horizontal barrier layer can prevent high-concentration dopants from out-diffusion into the underlying structures.

[0019] As seen in a vertical cross-section, a cell with a body / source region can generally have a symmetrical design (the cross-section plane can lie perpendicular to the lateral extent of the body contact trench). A second body region comprising a second channel region can be arranged laterally opposite a first body region comprising a first channel region. The second body region can be contacted by the same body contact region, with a layer of a diffusion barrier structure arranged therebetween. Thus, the body contact region can be defined by a first vertical barrier layer in a first horizontal direction toward the first body region, and it can also be defined by a second vertical barrier layer in a second horizontal direction opposite the first. Furthermore, it can be defined vertically downward by a horizontal barrier layer, such that the body contact region is contained within a trench formed by the barrier layer. Even when the barrier layers are mentioned separately when discussing their position and orientation, they can be deposited in the same process step (they can be formed simultaneously at the bottom and sidewalls of the body contact trench, see below).

[0020] In one embodiment, one or more layers of the diffusion barrier structure include alternating sublayers of silicon and oxygen-doped silicon. The oxygen-doped silicon sublayers can each have a thickness in the atomic range (e.g., one or a few atoms thick) or in the nanometer range to ensure sufficient crystallographic information for growing the silicon. The oxygen concentration in the oxygen-doped silicon sublayers can be relatively low, e.g., less than 5E14 cm³. The alternating sublayers can be formed, for example, by silicon epitaxy with oxygen absorption at different steps. Alternatively, the barrier layer(s) can be formed, for example, by co-implantation of a carbon component.

[0021] The present application also relates to a method for manufacturing a semiconductor transistor device, comprising the following steps:

[0022] i) forming a diffusion barrier,

[0023] ii) doping the body contact region with the same conductivity type but at a higher concentration than the body region,

[0024] iii) depositing conductive material to form conductive regions and contact regions.

[0025] The doping of the body contact region can be, for example, the doping of a previously formed silicon region, such as epitaxial silicon previously deposited without any doping at all (see below). Alternatively or additionally, the silicon material can also be doped in situ during deposition, in particular during epitaxial growth. For example, a previously etched body contact trench can already be refilled with a high doping concentration, such as a high concentration of boron, during overgrowth.

[0026] Before forming the diffusion barrier layer in step i), a body contact trench can be etched into the silicon region. In the manufactured device, the body region and the source region are arranged in this silicon region. When etching the body contact trench, the body and source implants can already be in place. Alternatively, as explained in detail below, the body and / or source implants can be performed after the body contact trench is etched. Independently of these details, one or more layers of the diffusion barrier structure are deposited or formed after the body contact trench is etched. They can be formed at the sidewalls of the trench, in particular at each sidewall thereof that is horizontally opposite to each other. In the same process step, a horizontal barrier layer can be formed at the bottom of the trench.

[0027] After forming the diffusion barrier structure in the body contact trench, the trench can be filled with epitaxially grown silicon. The mask used to define the body contact trench etch can remain in place during the formation of the diffusion barrier structure, and it can also remain in place later when the trench is filled with silicon again. The mask for the body contact trench etch can include a photoresist and a hard mask formed of an interlayer dielectric material below. In particular, the gate interlayer dielectric material previously deposited for forming the gate region in the gate trench can be used as a hard mask for the body contact trench etch. This can reduce the total number of process steps. Alternatively, a separate hard mask can be deposited for the body contact trench etch.

[0028] After refilling the body contact trench, the epitaxially grown silicon can protrude vertically above the upper ends of the body contact trench sidewalls, i.e., above the silicon region into which the trench has been etched. In the case where a photolithographic mask is in place during epitaxial growth, the epitaxial silicon can even protrude above the hard mask. Some of the epitaxial silicon can thereafter be removed by planarization, such as by chemical mechanical polishing (CMP).

[0029] During planarization, the hard mask previously used for the body contact trench etch can remain in place. This can, for example, protect other device structures such as the gate region or the field electrode region. Thereafter, the hard mask can be etched back, allowing, for example, the deposition of a defined screen oxide for subsequent implantation (see below). Thus, a vertical step can remain, i.e., between the silicon region laterally disposed between the diffusion barrier and the gate region and the silicon refill of the body contact trench. The height of the step can correspond to the thickness of the previously used hard mask, in particular to the thickness of the gate interlayer dielectric deposited.

[0030] In one embodiment, the body contact trench is refilled with undoped, deposited epitaxially grown silicon. The body contact region is then formed by implantation into this epitaxial silicon. Prior to implantation, a screen oxide (see above) may be deposited to suppress channeling during implantation.

[0031] Typically, the body and source regions can be formed before the body contact trench is etched so that the trench will be etched into p- and n-doped silicon material. In this case, combined with in-situ doping refill of the body contact trench, no implantation is required after refill.

[0032] In an alternative embodiment, the body and source regions are implanted after the body contact trench has been etched and the diffusion barrier structure has been formed. The trench can be refilled with or without in-situ doping, with the body and source regions formed after refilling. In cases where the body contact region is doped after refilling (e.g., undoped refill), this high-dose implant can be performed specifically after the body doping and optionally also after the source doping. Having a high-dose implant at the end can, for example, save an intervening thermal anneal.

[0033] The body implant can be performed without a mask, and for the source implant, a source mask (e.g., photolithography) can be used that shields the central portion of the body contact trench from the source implant, thereby limiting the source implant to the region adjacent to the gate trench (where the source pocket is formed). In particular, the source region so defined can extend laterally across the step discussed above. The central portion shielded from the source implant can, for example, have a width of approximately 100 nm (using photolithography alone, which can be narrowed, for example, by an additional oxide layer below the shielding oxide). As an alternative to a photoresist layer, for example, an oxide plug can be formed above the central portion of the trench to avoid implantation below the plug. If the body contact region is implanted after refilling, the body contact mask (e.g., photolithography) can limit the implant to a portion of the body contact trench, thereby maintaining a certain lateral distance from the vertical layer of the diffusion barrier structure so that the high-dose implant continues inside the diffusion barrier structure.

[0034] Regardless of the detailed order, all implants can be performed before depositing the interlayer dielectric, on which the front-side metallization is subsequently placed. Before depositing the front-side metallization, contact holes can be etched into the interlayer dielectric to contact the body contact region and the source region. Another contact hole can be etched to contact the gate electrode and, if applicable, the field electrode. One or more contact holes can be filled with a metallic material fill (e.g., tungsten). To ensure good electrical contact, a silicide layer can be formed beneath the metallic material fill. For this purpose, a silicide-forming layer is deposited before the metallic material fill (the silicide can be formed by diffusing metal atoms from this layer).

[0035] For example, to form titanium silicide, the silicide-forming layer can be a titanium or titanium / titanium nitride layer deposited, for example, by sputtering. During subsequent thermal processing, silicide will form where the silicide-forming layer contacts silicon (doped silicon or polysilicon). Consequently, a silicide layer will form at the upper surface of the body contact region. As silicide formation progresses, this silicide layer will increasingly extend into the body contact region. In this regard, the placement of the contact region above the upper end of the channel region (which ensures a sufficient height for the underlying body contact region material (see above)) can allow for a stable process window. This allows for a sufficiently thick silicide layer to be formed for electrical contact purposes while preventing the silicide from penetrating downward into the drift region. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The transistor device and its manufacture are explained in further detail below by means of exemplary embodiments, wherein the individual features may also be relevant to the present application in different combinations.

[0037] Figure 1 A transistor device having a body contact region according to the present disclosure is shown in cross-section;

[0038] Figure 2 shows a body contact region of a device according to the present disclosure in a more detailed view;

[0039] Figure 3a -h shows the different process steps for manufacturing Figure 1 devices;

[0040] Figure 4 The fabrication of a transistor device is shown in a block diagram. DETAILED DESCRIPTION

[0041] Figure 1A semiconductor transistor device 1 is shown, comprising a source region 2, a body region 3, a drain region 4, and a gate region 6. The gate region 6 is arranged laterally adjacent to the body region 3 and comprises a gate electrode 6.1 and a gate dielectric 6.2. The gate dielectric 6.2 (e.g., a gate oxide) capacitively couples the gate electrode 6.1 to the body region 3. By applying a voltage to the gate electrode 6.1, a channel can be formed in the channel portion 3.1 of the body region 3, see also Figure 2 .

[0042] A drift region 13 is arranged vertically between the body region 3 and the drain region 4. It is doped to the same conductivity type as the drain region 4 but at a lower concentration. In this example, the source region 2, the drift region 13 and the drain region 4 are n-type regions, while the body region 3 is a p-type region. In order to contact the body region 3, a body contact region 7 is provided, which is formed by doping (in situ during deposition or after, see below). The body contact region 7 has the same conductivity type as the body region 3 but a higher doping, in this example a high-dose boron doping. In order to avoid outdiffusion of this high-dose implant, it is included in a diffusion barrier structure 20, see in detail. Figure 2 .

[0043] The diffusion barrier structure 20 comprises a vertical diffusion barrier 20.1 arranged between the body contact region 7 and the body region 3. It prevents outdiffusion in a first horizontal direction 28. Furthermore, it comprises a horizontal diffusion barrier 20.2, thereby preventing outdiffusion vertically downward into the drift region 13 (in a vertical direction 29), and it comprises another vertical diffusion barrier 20.3 horizontally delimiting the body contact region 7 in the opposite direction. Figure 2 The cross-sectional view of FIG1 shows a symmetrical arrangement in the active region of the device 1, laterally opposite the body region 3, a further body region 30 and a further source region 31 are formed. They are arranged at a gate region 32 comprising a gate electrode 32.1 and a gate dielectric 32.2.

[0044] exist Figure 1 In the figure, a field electrode region 35 is also shown which is arranged in the field electrode trench 36. The field electrode region 35 comprises a field electrode 35.1, for example formed of polysilicon, and an interlayer dielectric 35.2 isolating it from the drift region 13. The field electrode region 35 may, for example, allow field shaping, such as controlling the position of the peak electric field and preventing avalanche or hot carrier generation. The field electrode region 35 may also serve as an edge termination for the active region of the laterally defined device 1. In this case, typically no source region 2 will be formed adjacent to the field electrode trench 36 (unlike shown in the figure). The active region extends between an edge termination field region on one lateral side of the device 1 and another edge termination field region on the opposite side, which is, for example, formed by a Figure 2However, the field electrode regions 35 may also be arranged inside the active area of ​​the device 1 , alternating with the gate regions 6 in the lateral direction 28 (seen in a vertical section through the active area).

[0045] like Figure 1 As shown, the gate region 6 is formed in the gate trench 37. In the example shown here, a field plate region 38 is arranged in the gate trench 37 below the gate region 6. The field plate region 38 includes a field plate electrode 38.1, for example made of polysilicon, and an interlayer dielectric 38.2 that isolates it from the drift region 13 and the gate region 6. Like the field electrode region 35, the field plate region 38 can allow field shaping.

[0046] Reference again Figure 2 , the figure shows that the lower portion 7.1 of the body contact region 7 is arranged laterally next to the body region 3. Since the body contact region 7 is contained in the diffusion barrier structure 20, it can be placed close to the channel region 3.1. The lateral distance 27 between the diffusion barrier layer 20.1 and the channel region 3.1 is only about 50 nm, which can be beneficial with regard to shielding high drain potentials.

[0047] In this case, the body contact region 7 is in contact with a conductive region 8 made of tungsten. The conductive region 8 has a contact region 8.1 that forms an electrical contact toward the body contact region 7. In order to ensure a good electrical connection to the body contact region 7 and also to the source region 2, a silicide layer 40 is arranged between the contact region 8.1 and the body contact region 7 and between the body contact region 7 and the source region 2. The contact region 8.1 is located vertically above the upper end 25.1 of the channel region 3.1; it is arranged at the upper end 2.1 of the source region 2. Therefore, there is enough body contact material below, which allows stable processing, see the general description for details. The channel region 3.1 extending between the upper end 25.1 and the lower end 25.2 has a vertical height 26 of approximately 50 nm.

[0048] refer to Figure 3a -h, the processing of the device 1, in particular the body contact region 7, is explained in more detail. Figure 3a In the illustrated case, field electrode trenches 36 and gate trenches 37 have already been etched into drift region 13. Trenches 36, 37 have been refilled, field electrode regions 35 and field plate regions 38 have been formed, and gate region 6 has been formed in gate trench 37. From this previous process step, i.e., from the deposition of interlayer dielectric 6.2, a layer of interlayer dielectric material 44 remains at surface 13.1 of drift region 13. This layer 44 (e.g., an oxide layer) subsequently serves as a hard mask 45 (alternatively, a short low-temperature oxide can also be deposited). If necessary, a thin layer or oxide can be added to layer 44 to adjust the thickness of the hard mask for trench etching.

[0049] This is Figure 3b, where a photoresist layer 46 has been deposited on layer 44 and structured by photolithography. After etching through layer 44, a body contact trench 50 is etched into the drift region 13, with layer 44 serving as a hard mask 45. (The photoresist layer 46 can be removed before etching into the drift region 13; due to the selectivity between oxide and silicon, the trench will be etched). If the topology is critical, the trenches 36 and 37 can be refilled with oxide in combination with planarization, such as CMP. When the body contact trench 50 has been etched, the diffusion barrier structure 20 is formed at the sidewalls 50.1, 50.3 and bottom 50.2 of the trench 50.

[0050] As schematically shown in the enlarged view, the diffusion barrier structure 20 is formed from alternating silicon sublayers 51.1 and oxygen-doped silicon sublayers 51.2. A silicon buffer layer 52 may be disposed between the silicon substrate forming the drift region 13 and the alternating sublayers 51.1, 51.2. Furthermore, a capping layer 53 of epitaxially grown silicon may be placed on the alternating sublayers 51.1, 51.2 (before the trenches are fully filled with epitaxial silicon, see below). This can provide high carrier mobility in this region. The silicon buffer layer 52 can be relatively thin, for example, in the range of 2 to 5 nm thick. Both the silicon buffer layer 52 and the capping layer 53 are optional. In addition to limiting dopant outdiffusion, the oxygen-doped silicon sublayers 51.2 of the barrier structure 20 can also improve carrier mobility within the channel region 3.1 of the device 1.

[0051] The oxygen-doped silicon sublayers 51.2 of the diffusion barrier structure 20 can be formed by introducing partial monolayers of oxygen into the silicon lattice. The oxygen atoms are interstitially placed to minimize disruption of the silicon lattice. Silicon sublayers 51.1 of silicon atoms separate adjacent partial monolayers of oxygen (oxygen-doped silicon sublayers 51.2). The alternating sublayers 51.1 and 51.2 can be formed by silicon epitaxy with oxygen absorption at different steps. For example, temperature and gaseous conditions can be controlled during the epitaxy process to form the oxygen-doped silicon sublayers 51.2, i.e., partial oxygen monolayers. Oxygen can be introduced / incorporated between the epitaxial layers of silicon (silicon sublayers 51.1), for example, by controlled introduction of an oxygen precursor into the epitaxy chamber. The resulting diffusion barrier structure 20 includes oxygen-doped silicon sublayers 51.2, which primarily comprise silicon but have a certain doping level or concentration of oxygen alternating with standard oxygen-free silicon epilayers (i.e., silicon sublayers 51.1).

[0052] Then, see Figure 3c , body contact trench 50 is filled with epitaxially grown silicon 55. In the case shown there, photoresist layer 46 is removed again, and epitaxial silicon 55 protrudes vertically. By planarization (e.g., CMP), the protruding silicon can be removed so that epitaxial silicon 55 is flush with upper surface 45.1 (dashed line) of layer 44.

[0053] exist Figure 3d In the process step shown, the layer 44 used as hard mask 45 has been removed, resulting in a step 56 formed of epitaxial silicon. As discussed in detail in the general description, the epitaxial silicon 55 can also be doped in situ during growth. In the example shown here, it is deposited undoped and a high-dose implant is introduced later. Prior to this, implants for the body region 3 and the source region 2 are performed. The body implant can be introduced without a mask, Figure 3e A source mask 60 for the subsequent source implant is shown. Screen oxide 59 has been deposited for the subsequent implantation before depositing and structuring the source mask 60. The source mask 60 shields the central portion 50.4 of the body contact trench 50 from the source implantation, thereby defining the source region 2 at the edge.

[0054] After removing the source mask 60, a body contact mask 61 is formed for high dose implantation 63, see Figure 3f The mask 61 defines a specific lateral distance 62 between the high-dose implant 63 and the diffusion barrier structure 20 . In a subsequent activation step (eg thermal annealing), the high-dose implant 63 extends up to the diffusion barrier structure 20 .

[0055] Figure 3g The process steps are shown after the body contact mask 61 has been removed and the interlayer dielectric 65 has been deposited (after the removal of the screen oxide 59). On top of the interlayer dielectric 65, a mask 66 is formed, defining the locations of the contact holes 67-69 etched through the interlayer dielectric 65. After removing the mask 66, a titanium or titanium / titanium nitride layer 70 is deposited (see FIG. Figure 1 ). In the contact holes 67-69, this layer serves as a silicide forming layer, and silicide formation is achieved through subsequent heat treatment. Figure 3h As shown, a metallic filling 66 can be deposited into the contact holes 67-69 to form respective electrical contacts via the respective silicide layers 40, 70, 71. In the case of the body contact region 7, the metallic filling 66 forms a conductive region 8 and a contact region 8.1 located in a horizontal plane 75.

[0056] Figure 4 A flowchart provides an overview of some of the process steps, starting with etching 80 of the body contact trench 50. After forming 81 the diffusion barrier structure 20 at the bottom 50.2 and sidewalls 50.1 and 50.3, the body contact trench 50 is filled 82 with epitaxially grown silicon 55. Subsequently, the body region 3 and the source region 2 are formed 83 by implantation (see above for details). After doping 84 the epitaxially grown silicon 55 to form the body contact region 7, a silicide layer 40 is formed 85. Subsequently, a metallic filler 66 is deposited 86 to form the conductive region 8.

[0057] Reference Symbols List:

[0058] Semiconductor transistor device 1

[0059] Source region 2

[0060] Upper 2.1

[0061] Body area 3

[0062] Channel region 3.1

[0063] Drain region 4

[0064] Gate region 6

[0065] Gate electrode 6.1

[0066] Gate dielectric 6.2

[0067] Body contact area 7

[0068] Lower part 7.1

[0069] Conductive area 8

[0070] Contact area 8.1

[0071] Drift Zone 13

[0072] Surface 13.1

[0073] Diffusion barrier structure 20

[0074] Vertical diffusion barrier 20.1

[0075] Horizontal diffusion barrier 20.2

[0076] Another vertical diffusion barrier 20.3

[0077] The end portion 25 of the channel region

[0078] Upper end 25.1

[0079] Lower end 25.2

[0080] Vertical height 26

[0081] Lateral distance 27

[0082] First horizontal direction 28

[0083] Vertical direction 29

[0084] Other main body area 30

[0085] Other source regions 31

[0086] Other gate regions 32

[0087] Gate electrode 32.1

[0088] Gate dielectric 32.2

[0089] Field electrode region 35

[0090] Field electrode 35.1

[0091] Interlayer dielectric 35.2

[0092] Field electrode trench 36

[0093] Gate trench 37

[0094] Field board area 38

[0095] Field plate electrode 38.1

[0096] Interlayer dielectric 38.2

[0097] Silicide layer 40

[0098] Layer 44

[0099] Hard mask 45

[0100] Upper surface 45.1

[0101] Photoresist layer 46

[0102] Area trench 50

[0103] Side walls 50.1, 50.3

[0104] Bottom 50.2

[0105] Center section 50.4

[0106] Buffer layer 52

[0107] Covering layer 53

[0108] Epitaxially grown silicon 55

[0109] Step 56

[0110] Shielding oxide 59

[0111] Source mask 60

[0112] Contact mask 61

[0113] A certain lateral distance of 62

[0114] Dose injection 63

[0115] Interlayer dielectric 65

[0116] Mask 66

[0117] Contact holes 67-69

[0118] Titanium nitride layer 70

[0119] Silicide layer 71

[0120] Horizontal plane 75

[0121] Etch (body contact trench) 80

[0122] Formation (diffusion barrier structure) 81

[0123] Fill (body contact groove) 82

[0124] Formation (body and source) 83

[0125] Doping (epitaxial silicon) 84

[0126] Formation (silicide layer) 85

[0127] Deposition (metal filling) 86.

Claims

1. A semiconductor transistor device comprising: source region, a body region including a vertical channel region, drain region, a gate region, laterally adjacent to the channel region, The body contact region is formed by doping. diffusion barrier, and A conductive area formed of a conductive material, in, The body contact region electrically contacts the body region, the diffusion barrier layer being arranged therebetween, and wherein the doping of the body contact region has the same conductivity type but a higher concentration than the doping of the body region, and wherein the conductive region has a contact region forming an electrical contact toward the body contact region, the contact region of the conductive region being arranged vertically above an upper end of the channel region, The diffusion barrier layer includes alternating sub-layers of Si and oxygen-doped Si.

2. The semiconductor transistor device according to claim 1, wherein The contact region of the conductive region is arranged at an upper end of the source region.

3. The semiconductor transistor device according to claim 1 or 2, wherein: The contact area of ​​the conductive area is entirely located in a horizontal plane.

4. The semiconductor transistor device according to claim 1 or 2, wherein: At least a lower portion of the body contact region is arranged laterally beside the body region.

5. The semiconductor transistor device according to claim 4, wherein The lower portion of the body contact region and the diffusion barrier layer extend vertically over an entire vertical height of the channel region.

6. The semiconductor transistor device according to claim 4, wherein The diffusion barrier layer is arranged at a lateral distance of no more than 80 nm from the channel region.

7. The semiconductor transistor device according to claim 1 or 2, wherein: The channel region has a vertical height of maximum 100 nm.

8. The semiconductor transistor device according to claim 1 or 2, comprising an additional diffusion barrier layer defining the body contact region vertically downwards, wherein the additional diffusion barrier layer is formed at an upper surface of a drift region arranged between the body region and the drain region.

9. The semiconductor transistor device according to claim 8, wherein The additional diffusion barrier layer comprises alternating sub-layers of Si and oxygen-doped Si.

10. A method for manufacturing a semiconductor transistor device according to any one of the preceding claims, the method comprising the steps of: i) forming a diffusion barrier layer; ii) doping the body contact region with the same conductivity type as the body region but at a higher concentration; iii) Depositing conductive material to form conductive areas and contact areas.

11. The method according to claim 10, wherein: Before forming the diffusion barrier layer, a body contact trench is etched into the silicon region, and thereafter the diffusion barrier layer is formed at the sidewalls of the body contact trench.

12. The method according to claim 11, wherein Prior to etching the body contact trenches, the gate region is formed, including deposition of a gate interlayer dielectric material that serves as a hard mask for subsequent etching of the body contact trenches.

13. The method according to claim 11 or 12, wherein: After forming the diffusion barrier layer, the body contact trench is filled with undoped deposited epitaxially grown silicon, after which the body contact region is formed by implantation into the epitaxially grown silicon.

14. The method according to claim 11 or 12, wherein: After etching the body contact trench and forming the diffusion barrier layer, the body region and the source region are formed by implantation.

15. The method according to claim 13, wherein: After the implantation for forming the body region and the source region, an implantation into the epitaxially grown silicon for forming the body contact region is performed.

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