Patent Publication Number: US-9847390-B1

Title: Self-aligned wrap-around contacts for nanosheet devices

Description:
BACKGROUND 
     Technical Field 
     The present disclosure relates to semiconductor design, and more particularly to forming wrap-around contacts for nanosheet transistor devices. 
     Related Art 
     A nanosheet transistor refers to a type of field-effect transistor (FET) that includes a plurality of stacked nanosheets extending between a pair of source/drain regions. A FET typically includes doped source/drain regions that are formed in a semiconductor substrate and separated by a channel region. A gate insulation layer is positioned above the channel region and a conductive gate electrode is positioned above the gate insulation layer. The gate insulation layer and the gate electrode together may be referred to as the gate stack for the device. By applying an appropriate voltage to the gate electrode, the channel region becomes conductive and current is allowed to flow from the source region to the drain region. 
     To improve the operating speed of the FETs, and to increase the density of FETs on an integrated circuit (IC), designers have greatly reduced the physical size of FETs over the years. More specifically, the channel length of FETs can be scaled down significantly, which can improve the switching speed of the FETs. A number of challenges arise as feature sizes of FETs and ICs get smaller. For example, significant downsizing of traditional planar FETs leads to electrostatic issues and electron mobility degradation. Scaled-down planar FETs have shorter gate lengths that make it more difficult to control the channel. New device architectures such as “gate-all-around” nanowire or nanosheet structures allow further scaling of ICs, in part because the gate wraps around the channel and provides better control with lower leakage current, faster operations, and lower output resistance. 
     In nanosheet FETs, a wrap-around contact (WAC) may be formed over the entire outer surface of source/drain regions in order to reduce resistance in the nanosheet FET. In previous methods, in order to ensure that the WAC is formed around the entire outer surface of the source/drain regions, a large contact area is etched over the source/drain regions such that each outer surface of the source/drain regions are exposed, even in a worst-case misalignment scenario. In order to ensure that the WAC is formed around the entire outer surface of the source/drain regions at the worst-case alignment scenario using previous methods, the contact area is made significantly wider than the nanosheets. The large contact area limits the device scaling because the space between individual nanosheet stacks is limited by the width of the contact area used to form the WAC. 
     SUMMARY 
     A first aspect of the disclosure provides a method including: forming a nanosheet structure on a substrate, the nanosheet structure including a gate disposed on a plurality of alternating first sacrificial layers and nanosheets; forming a raised source/drain (S/D) region on the substrate adjacent to the nanosheet structure such that the nanosheets extend between the raised S/D region, and the raised S/D region has a continuous outer surface that includes an upper surface and a side surface; forming an etch-stop layer on the continuous outer surface of the raised S/D region; forming a second sacrificial layer over the etch-stop layer, the etch-stop layer including a different material than the second sacrificial layer; depositing a dielectric layer over the second sacrificial layer; removing an upper portion of the dielectric layer to expose a portion of the second sacrificial layer; removing the second sacrificial layer selective to the etch-stop layer; and depositing a conductor in the removed upper portion of the dielectric layer to form a wrap-around contact over the etch-stop layer and a second contact above the wrap-around contact. 
     A second aspect of the disclosure provides a method of forming a wrap-around contact on a nanosheet transistor, the method including: forming an etch-stop layer over a continuous outer surface of a raised source/drain (S/D) region of the nanosheet transistor; forming a sacrificial layer over the etch-stop layer, the etch-stop layer including a different material than the sacrificial layer; depositing a dielectric layer over the sacrificial layer; removing an upper portion of the dielectric layer to expose a portion of the sacrificial layer; removing the sacrificial layer selective to the etch-stop layer; and depositing a conductor in the removed upper portion of the dielectric layer to form a wrap-around contact and a second contact. 
     A third aspect of the disclosure provides an apparatus including: a nanosheet stack disposed on a substrate; a metal gate disposed on the nanosheet stack; a raised source/drain (S/D) region disposed on the substrate and adjacent to the nanosheet stack such that the nanosheets extend between the source/drain region; a silicon etch-stop layer disposed on the raised S/D region; a wrap-around contact wrapped around the silicon etch-stop layer; and a second contact disposed on the wrap-around contact, wherein a widest portion of the second contact is narrower than a widest portion of the wrap-around contact. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The embodiments of this disclosure will be described in detail, with reference to the following figures, wherein like designations denote like elements, and wherein: 
         FIG. 1  shows a plan view of a plurality of nanosheet stacks and adjacent source/drain regions in accordance with the present disclosure. 
         FIG. 2A  shows a cross-sectional view, along line X-X in  FIG. 1 , of source/drain regions formed on a substrate in accordance with the present disclosure. 
         FIG. 2B  shows a cross-sectional view, along line Y-Y in  FIG. 1 , of nanosheet stacks and adjacent source/drain regions formed on the substrate in accordance with the present disclosure. 
         FIG. 3A  shows a cross-sectional view, along line X-X in  FIG. 1 , of forming an etch-stop layer on the source/drain regions in accordance with the present disclosure. 
         FIG. 3B  shows a cross-sectional view, along line Y-Y in  FIG. 1 , of forming the etch-stop layer on the source/drain regions in accordance with the present disclosure. 
         FIG. 4A  shows a cross-sectional view, along line X-X in  FIG. 1 , of forming a sacrificial layer on the etch-stop layer in accordance with the present disclosure. 
         FIG. 4B  shows a cross-sectional view, along line Y-Y in  FIG. 1 , of forming the sacrificial layer on the etch-stop layer in accordance with the present disclosure. 
         FIG. 5A  shows a cross-sectional view, along line X-X in  FIG. 1 , of replacing dummy gates with metal gates in accordance with the present disclosure. 
         FIG. 5B  shows a cross-sectional view, along line Y-Y in  FIG. 1 , of replacing the dummy gates with metal gates in accordance with the present disclosure. 
         FIG. 6A  shows a cross-sectional view, along line X-X in  FIG. 1 , of exposing a top portion of the sacrificial layer in accordance with the present disclosure. 
         FIG. 6B  shows a cross-sectional view, along line Y-Y in  FIG. 1 , of exposing the top portion of the sacrificial layer in accordance with the present disclosure. 
         FIG. 7A  shows a cross-sectional view, along line X-X in  FIG. 1 , of removing the sacrificial layer selective to the etch-stop layer in accordance with the present disclosure. 
         FIG. 7B  shows a cross-sectional view, along line Y-Y in  FIG. 1 , of removing the sacrificial layer selective to the etch-stop layer in accordance with the present disclosure. 
         FIG. 8A  shows a cross-sectional view, along line X-X in  FIG. 1 , of forming a wrap-around contact (WAC) over the etch-stop layer in accordance with the present disclosure. 
         FIG. 8B  shows a cross-sectional view, along line Y-Y in  FIG. 1 , of forming the wrap-around contact (WAC) over the etch-stop layer in accordance with the present disclosure. 
         FIG. 9A  shows a cross-sectional view, along line X-X in  FIG. 1 , of optionally removing the etch-stop layer selective to the source/drain region in accordance with the present disclosure. 
         FIG. 9B  shows a cross-sectional view, along line Y-Y in  FIG. 1 , of optionally removing the etch-stop layer selective to the source/drain region in accordance with the present disclosure. 
         FIG. 10A  shows a cross-sectional view, along line X-X in  FIG. 1 , of forming the wrap-around contact (WAC) over the source/drain region in accordance with the present disclosure. 
         FIG. 10B  shows a cross-sectional view, along line Y-Y in  FIG. 1 , of forming the wrap-around contact (WAC) over the source/drain region in accordance with the present disclosure. 
       It is noted that the drawings of the disclosure are not to scale. The drawings are intended to depict only typical aspects of the disclosure, and therefore should not be considered as limiting the scope of the disclosure. In the drawings, like numbering represents like elements between the drawings. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of the present disclosure provide methods for forming self-aligned wrap-around contacts (WAC) for nanosheet transistor devices that may be utilized in integrated circuits (IC). A nanosheet transistor refers to a transistor with a gate disposed on a nanosheet stack between a pair of source/drain regions, and a plurality of nanosheets extending between the pair of source/drain regions. The nanosheets are spaced apart vertically by sacrificial layers. A wrap-around contact (WAC) refers to a contact layer formed around the outer surface of each of the source/drain regions. The WAC being wrapped around the outer surface of the source/drain regions enables a lower resistance in the resulting nanosheet transistor device due to a large area of contact between the WAC and the source/drain region. In previous methods, in order to ensure that the WAC is formed around the outer surface of the source/drain region, a large contact area is etched over the source/drain region such that each outer surface of the source/drain region is exposed, even in a worst-case misalignment scenario. In order to ensure a sufficiently formed WAC at the worst-case alignment scenario using previous methods, the contact area is formed significantly wider than the nanosheets. The previous methods limit the device scaling because the space between individual nanosheet stacks is limited by the width of the contact area. 
     The present disclosure provides a method of forming a self-aligned WAC that uses a much smaller contact such that the size of the contact may not limit the device scaling. The wrap-around contact and second (upper) contact of the present disclosure may allow for better scaling while reducing contact resistance and spreading resistance. The resulting ICs may be made smaller due to more densely packed nanosheet transistors, while maintaining reliability in manufacturing. This may be accomplished by reducing the area of second (upper) contacts while ensuring that the wrap-around contact is formed around the outer surface of the source/drain regions in a worst-case alignment scenario. 
     It is to be understood that the present disclosure will be described in terms of a given illustrative architecture having a silicon substrate, however other architectures, structures, substrate materials, and process features and steps may be varied within the scope of the present disclosure. 
     It will also be understood that when an element such as a lay, region, or substrate is referred to as being “on” or “over” another element, it may be directly on the other element or intervening elements may also be present. In contrast, when an element is referred to as being “directly on” or “directly over” another element, there may are no intervening elements present. It will also be understood that when an element is referred to as being “connected” or “coupled” to another element, it may be directly connected or coupled to the other element or intervening elements may be present. In contrast, when an element is referred to as being “directly connected” or “directly coupled” to another element, there are no intervening elements present. 
     Methods as described herein may be used in the fabrication of integrated circuit (IC) chips. The resulting integrated circuit chips may be integrated with other chips, discrete circuit elements, and/or other signal processing devices as part of either (a) an intermediate product, such as a motherboard, or (b) an end product. The end product can be any product that includes integrated circuit chips. 
     Reference in the specification to “one embodiment” or “an embodiment” of the present disclosure, as well as other variations thereof, means that a particular feature, structure, characteristic, and so forth described in connection with the embodiment is included in at least one embodiment of the present disclosure. Thus, the phrases “in one embodiment” or “in an embodiment,” as well as any other variations appearing in various places throughout the specification are not necessarily all referring to the same embodiment. 
     It is to be appreciated that the use of any of the following “/”, “and/or”, and “at least one of”, for example, in the cases of “A/B”, “A and/or B” and “at least one of A and B”, is intended to encompass the selection of the first listed option (a) only, or the selection of the second listed option (B) only, or the selection of both options (A and B). As a further example, in the cases of “A, B, and/or C” and “at least one of A, B, and C”, such phrasing is intended to encompass the first listed option (A) only, or the selection of the second listed option (B) only, or the selection of the third listed option (C) only, or the selection of the first and the second listed options (A and B), or the selection of the first and third listed options (B and C) only, or the selection of the second and third listed options (B and C) only, or the selection of all three options (A and B and C). This may be extended, as readily apparent by one of ordinary skill in the art, for as many items listed. 
     Referring now to the drawings in which like numerals represent the same or similar elements and initially to  FIG. 1  showing a plan view of a plurality of nanosheet stacks  104  and adjacent source/drain regions  102 .  FIG. 1  shows cross-section line Y-Y which extends along nanosheets  106  and parallel to nanosheets  106 .  FIG. 1  also shows cross-section line X-X which extends perpendicular to nanosheets  106  along source/drain regions  102 . 
       FIGS. 2A and 2B  show a step of forming a plurality of nanosheet stacks  104  on a substrate  108 . Each of the plurality of nanosheet stacks  104  may include a plurality of alternating sacrificial layers  114  and nanosheets  106 . A gate  116  may be disposed on each of the nanosheet stacks  104 .  FIG. 2A  shows a cross-section of the step along line X-X in  FIG. 1 .  FIG. 2B  shows a cross-section of the step along line Y-Y in  FIG. 1 . This orientation carries through the drawings. In one embodiment, sacrificial layers  114  may include silicon germanium (SiGe). Nanosheets  106  may include a semiconducting material including but not limited to silicon, germanium, silicon germanium, silicon carbide, and those consisting essentially of one or more III-V compound semiconductors having a composition defined by the formula Al X1 Ga X2 In X3 As Y1 P Y2 N Y3 Sb Y4 , where X1, X2, X3, Y1, Y2, Y3, and Y4 represent relative proportions, each greater than or equal to zero and X1+X2+X3+Y1+Y2+Y3+Y4=1 (1 being the total relative mole quantity). Other suitable substrates include II-VI compound semiconductors having a composition Zn A1 Cd A2 Se B1 Te B2 , where A1, A2, B1, and B2 are relative proportions each greater than or equal to zero and A1+A2+B1+B2=1 (1 being a total mole quantity). In one particular embodiment, nanosheets  106  may include silicon. In one embodiment, nanosheets  106  may include silicon (Si). In one embodiment, nanosheet stacks  104  may include alternating layers of SiGe sacrificial layers  114  and Si nanosheets  106 . Nanosheet stacks  104  may include at least one nanosheet  106 . In one embodiment, nanosheet stacks  104  include three nanosheets  106 . Substrate  108  may include a buried insulator layer  110  over a bulk semiconductor layer  112 . Buried insulator layer  110  may include, for example, silicon oxide, and semiconductor layer  112  may include any semiconductor material listed for nanosheets  106 .  FIGS. 2A and 2B  also show a step of forming a plurality of raised source/drain (S/D) regions  102  on substrate  108 . A raised S/D region  102  may be formed adjacent to a nanosheet stack  104  such that nanosheets  106  extend between portions of an adjacent raised S/D region  102 . Nanosheets  106  are shown in phantom in  FIG. 2A  for positional reference and clarity, however it should be understood that nanosheets  106  do not extend through S/D regions  102 . In one embodiment, nanosheets  106  extend between adjacent S/D regions  102  and do not extend through S/D regions  102 . Each S/D region may have a continuous outer surface  118  that may include an upper surface(s)  120  and side surface(s)  122 . In one embodiment, S/D regions  102  may be epitaxially grown. The terms “epitaxial growth” and “epitaxially formed and/or grown” mean the growth of a semiconductor material on a deposition surface of a semiconductor material, in which the semiconductor material being grown may have the same crystalline characteristics as the semiconductor material of the deposition surface. In an epitaxial growth process, the chemical reactants provided by the source gases are controlled and the system parameters are set so that the depositing atoms arrive at the deposition surface of the semiconductor substrate with sufficient energy to move around on the surface and orient themselves to the crystal arrangement of the atoms of the deposition surface. Therefore, an epitaxial semiconductor material may have the same crystalline characteristics as the deposition surface on which it may be formed. For example, an epitaxial semiconductor material deposited on a {100} crystal surface may take on a {100} orientation. In some embodiments, epitaxial growth processes may be selective to forming on semiconductor surfaces, and may not deposit material on dielectric surfaces, such as silicon dioxide or silicon nitride surfaces. In one particular embodiment, S/D regions  102  may be formed by epitaxially growing heavily doped silicon (Si) or silicon germanium (SiGe). Spacers  124  may be formed over gates  116  using any now known or later developed techniques, e.g., deposition of silicon nitride (SiN). For example, in one embodiment, an upper spacer  126  may include a hard mask material, such as SiN, deposited on gate  116 . In such an embodiment, offset spacers  128  may be formed by removing a portion of sacrificial layers  114  selective to nanosheets  106 , and depositing SiN to replace the removed portions of sacrificial layers  114 . Formation of spacers  124  may include a spacer pull-down formation process, sidewall image transfer, atomic layer deposition (ALD), reactive ion etching (RIE), or any other now known or later developed techniques. 
       FIGS. 3A and 3B  show a step of forming an etch-stop layer  200  on continuous outer surface  118  of raised S/D region  102 . Etch-stop layer  200  may be formed of a different material than raised S/D region  102 . In one embodiment, etch-stop layer  200  may be formed to a thickness of 1-3 nanometers. The etch-stop layer may be made of undoped silicon (Si). In one embodiment, etch-stop layer  200  may be epitaxially grown over the continuous outer surface  118  of raised S/D region  102 . 
       FIGS. 4A and 4B  show a step of forming a sacrificial layer  300  over of etch-stop layer  200 . Etch-stop layer  200  may be formed of a different material than sacrificial layer  300  such that sacrificial layer  300  may later be removed while leaving etch-stop layer  200  intact. In one embodiment, etch-stop layer  200  and sacrificial layer  300  may have a different etch selectivity. In one embodiment, sacrificial layer  300  may be formed to a thickness of 5-15 nanometers. In one embodiment, sacrificial layer  300  may be epitaxially grown over etch-stop layer  200 . In one embodiment, sacrificial layer  300  may be formed of silicon germanium (SiGe). In one embodiment, sacrificial layer may include SiGe with a germanium percentage of 25% -50% (SiGe25). While shown as one layer, sacrificial layer  300  may include a number of layers. 
       FIGS. 5A and 5B  show a step of depositing a dielectric layer  400  over sacrificial layer  300 . Dielectric layer  400  may include a flowable oxide. In one embodiment, dielectric layer  400  may be formed by chemical vapor deposition (CVD), high-density plasma chemical vapor deposition (HDP-CVD), or a high-aspect ratio process (HARP). Dielectric layer  400  may include any interlevel or intralevel dielectric material including inorganic dielectric materials, organic dielectric materials, or combinations thereof. Suitable dielectric materials include carbon-doped silicon dioxide materials; fluorinated silicate glass (FSG); organic polymeric thermoset materials; silicon oxycarbide; SiCOH dielectrics; fluorine doped silicon oxide; spin-on glasses; silsesquioxanes, including hydrogen silsesquioxane (HSQ), methyl silsesquioxane (MSQ) and mixtures or copolymers of HSQ and MSQ; benzocyclobutene (BCB)-based polymer dielectrics, and any silicon-containing low-k dielectric. Examples of spin-on low-k films with SiCOH-type composition using silsesquioxane chemistry include HOSP™ (available from Honeywell), JSR 5109 and 5108 (available from Japan Synthetic Rubber), Zirkon™ (available from Shipley Microelectronics, a division of Rohm and Haas), and porous low-k (ELk) materials (available from Applied Materials). Examples of carbon-doped silicon dioxide materials, or organosilanes, include Black Diamond™ (available from Applied Materials) and Coral™ (available from Lam Research). An example of an HSQ material is FOx™ (available from Dow Corning). In one embodiment, dielectric layer  400  may include an oxide. In one embodiment, the present method may include planarization of dielectric layer  400 . Planarization of dielectric layer  400  may occur by chemical mechanical polishing (CMP). In a particular embodiment, planarization of dielectric layer  400  may occur by poly-open CMP (POC). The present method may optionally include a replacement-metal-gate (RMG) process. In such an embodiment, original gate  116  may be a dummy gate  416  formed of a semiconducting material. During the optional RMG process, dummy gate  416  and sacrificial layers  114  may be removed and replaced with a metal gate  516  having a high dielectric constant (high-k). In one embodiment, metal gate  516  may have a dielectric constant of 3.9 or higher. Dummy gate  416  may be removed by an etch selective to nanosheets  106 . In one embodiment, dummy gate  416  includes amorphous silicon (a-Si) disposed on a thin silicon dioxide (SiO 2 ) layer. In such an embodiment, removal of dummy gate  416  may include removing the a-Si selective to SiO 2  followed by a brief SiO 2  removal to expose nanosheets  106  and at least one of sacrificial layers  114 . In one embodiment, the a-Si may be removed selective to SiO 2  by a wet hot ammonia etch, or a tetramethylammonium hydroxide (TMAH) wet etch. The thin SiO 2  layer may be removed by a dilute hydrofluoric acid (DHF) etch. Sacrificial layers  114  may be removed by a selective SiGe removal process now known or later developed, such as a wet etch or a dry etch. Metal gate  516  may be formed by atomic layer deposition (ALD), thermal atomic layer deposition, or any other method of depositing a high-k metal now known or later developed. The present method may also include formation of self-aligned contact (SAC) caps  402  over gate  116 ,  516 . SAC caps  402  may be formed of a material resistant to an etch chemistry used for dielectric layer  400 . In one embodiment where dielectric layer  400  includes silicon dioxide (SiO 2 ), SAC caps  402  may include silicon nitride (SiN), siliconborocarbonitride (SiBCN), silicon oxycarbide (SiCO), or silicon oxycarbonitride (SiOCN). 
       FIGS. 6A and 6B  show a step of removing an upper portion  500  of dielectric layer  400  to expose a portion of sacrificial layer  300 . Upper portion  500  of dielectric layer  400  may be removed by a patterned etch using a mask or any other method of selectively removing an oxide that is now known or later developed. In one embodiment, the removed upper portion  500  of dielectric layer  400  may be misaligned with underlying sacrificial layer  300 . However, as will be described, some misalignment can occur. 
       FIGS. 7A and 7B  show a step of removing sacrificial layer  300  selective to etch-stop layer  200 . In one embodiment, sacrificial layer  300  may be removed by an etch process selective to etch-stop layer  200 , or any other method of selectively removing material now known or later developed. As will be discussed in further detail below, etch-stop layer  200  may optionally be removed with a separate etch that is selective to S/D region  102 . 
       FIGS. 8A and 8B  show a step of depositing a wrap-around contact  600  over each etch-stop layer  200 . In this embodiment, etch-stop layer  200  may not be removed prior to forming wrap-around contact  600 . The process shown also forms a second contact  602  over wrap-around contact  600  in dielectric layer  400 . In one embodiment, wrap-around contact  600  and second contact  602  may formed of the same material in a single step. In another embodiment, wrap-around contact  600  may be formed of a different material than second contact  602 . In one embodiment, wrap-around contact  600  may include a silicide formed by depositing a thin metal liner (not shown) over the semiconducting material of etch-stop layer  200  (or over the semiconducting material of S/D region  102  in an embodiment where etch-stop layer  200  is removed prior to forming wrap-around contact  600 , as shown in  FIGS. 10A and 10B ). The thin metal liner may include titanium (Ti), platinum-doped nickel (NiPt), NiPtTi alloy, platinum (Pt), titanium aluminide (TiAl), or titanium carbide (TiC). In one embodiment, the thin metal liner forms a silicide with the semiconducting material on which it is deposited. The thin metal liner may sometimes be referred to as a liner silicide. In such an embodiment, the silicide may form as a result of the thermal budget from depositing the bulk metal  604  of the wrap-around contact  600  on the thin metal liner. Bulk metal  604  of wrap-around contact  600  may include tungsten (W), ruthenium (Ru), cobalt (Co), copper (Cu), or aluminum (Al). In such an embodiment, second contact  602  may be formed of the same bulk metal  604  as the wrap-around contact  600 . 
     In a different embodiment, forming wrap-around contact  600  may include forming a silicide by chemical vapor deposition (CVD) of a metal, e.g., titanium (Ti) followed by an anneal to form silicide with the underlying semiconductor material and then removal of the metal, or may include atomic layer deposition (ALD) of tantalum silicide (TaSi). Wrap-around contact  600  may then also include deposition of a refractory metal liner (not shown) inside of dielectric layer  400  and deposition of a conductor. Refractory metal liner may include ruthenium; however, other refractory metals such as tantalum (Ta), titanium (Ti), tungsten (W), iridium (Ir), rhodium (Rh) and platinum (Pt), etc., or mixtures of thereof, may also be employed. Second contact  602  may be formed by, for example, deposition of a refractory metal liner followed by a conductor. For example, it may be formed by atomic layer deposition (ALD) of ruthenium (Ru) followed by chemical vapor deposition (CVD) of fluorine-free tungsten (FFW) or cobalt (Co). In one embodiment, second contact  602  may constitute what is referred to as a trench silicide (TS) contact. 
       FIGS. 9A and 9B  show the optional step of removing etch-stop layer  200  prior to depositing wrap-around contact  600  (after the step shown in  FIGS. 7A and 7B ). As discussed above, etch-stop layer  200  may be removed by an etch selective to S/D region  102 . In one embodiment, etch-stop layer  200  may be removed by an isotropic etch such as wet silicon trimming, or a Frontier process. 
       FIGS. 10A and 10B  show a step of depositing wrap-around contact  600  after the optional step of removing etch-stop layer  200 . The steps shown in  FIGS. 10A and 10B  are described above regarding  FIGS. 8A and 8B , with the exception that in this embodiment, etch-stop layer  200  is removed prior to forming wrap-around contact  600 . As a result, wrap-around contact  600  may be formed directly on S/D/region  102 . 
     The present method provides a plurality of nanosheet transistors  700 . Each of the nanosheet transistors  700  includes nanosheet stack  104  disposed on substrate  108 . Metal gate  116  ( 516 ) may be disposed on nanosheet stack  104 . An S/D region  102  is disposed on substrate  108  adjacent to nanosheet stack  104  such that nanosheets  106  extend between portions of S/D region  102 . A silicon etch-stop layer  200  may be disposed on the S/D region  102 . Wrap-around contact  600  may be wrapped around silicon etch-stop layer  200 . In one embodiment, particularly in the case of a PFET, S/D region  102  may include silicon germanium (SiGe). In such an embodiment, silicon etch-stop layer  200  may be formed on SiGe S/D region  102 , and wrap-around contact  600  may be formed on silicon etch-stop layer  200 . Second contact  602  may be disposed on wrap-around contact  600 . Second contact  602  may be contained within a span  800  of wrap-around contact  600 . Such a configuration enables device scaling that may not be limited by a width of second contact  602 . Even in a situation where second contact  602  is misaligned with wrap-around contact  600  in a worst-case scenario misalignment, second contact  602  may be contained within a span  800  of wrap-around contact  600 . In one embodiment, a widest portion  802  of second contact  602  may be narrower than a widest portion  804  of wrap-around contact. In one embodiment, an interface  806  between wrap-around contact  600  and second contact  602  may be narrower than a width  808  of one of the S/D regions  102 . 
     The description of the present disclosure has been presented for purposes of illustration and description, but is not intended to be exhaustive or limited to the disclosure in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the disclosure. The embodiment was chosen and described in order to best explain the principles of the disclosure and the practical application, and to enable others of ordinary skill in the art to understand the disclosure for various embodiments with various modifications as are suited to the particular use contemplated.