Abstract: A method for fabricating a metal silicide interconnect in a stacked 3D non-volatile memory array. A stack of alternating layers of undoped/lightly doped polysilicon and heavily doped polysilicon is formed on a substrate. Memory holes are etched in cell areas of the stack while an interconnect area is protected. Slits are etched in the cell areas and the interconnect areas. A wet etch is performed via the slits or the memory holes in the cell area to remove portions of the undoped/lightly doped polysilicon layers in the cell area, and dielectric is deposited. Silicidation transforms portions of the heavily doped polysilicon layers in the cell area to metal silicide, and transforms portions of the heavily doped and undoped/lightly doped polysilicon layers in the interconnect area to metal silicide. The metal silicide interconnect can be used for routing power and control signals from below the stack to above the stack.

Abstract: A method of forming a semiconductor structure includes providing a substrate; forming a low-k dielectric layer over the substrate; embedding a conductive wiring into the low-k dielectric layer; and thermal soaking the conductive wiring in a carbon-containing silane-based chemical to form a barrier layer on the conductive wiring. A lining barrier layer is formed in the opening for embedding the conductive wiring. The lining barrier layer may comprise same materials as the barrier layer, and the lining barrier layer may be recessed before forming the barrier layer and may contain a metal that can be silicided.

Abstract: The interlayer connection of the substrate is formed by a contact-hole filling (4) of a semiconductor layer (11) and metallization (17) of a recess (16) in a reverse-side semiconductor layer (13), wherein the semiconductor layers are separated from each other by a buried insulation layer (12), at whose layer position the contact-hole filling or the metallization ends.

Abstract: Provided is a method of manufacturing a semiconductor device. In the method, after a thin liner is formed on a substrate on which a lower interconnection is formed, a silicon source is supplied to form a silicide layer under the liner by a reaction between the silicon source and the lower interconnection, and the silicide layer is nitrided and an etch stop layer is formed. Therefore, the lower interconnection is prevented from making contact with the silicon source, variations of the surface resistance of the lower interconnection can be prevented, and thus high-speed devices can be fabricated.

Abstract: A buried local interconnect and method of forming the same counterdopes a region of a doped substrate to form a counterdoped isolation region. A hardmask is formed and patterned on the doped substrate, with a recess being etched through the patterned hardmask into the counterdoped region. Dielectric spacers are formed on the sidewalls of the recess, with a portion of the bottom of the recess being exposed. A metal is then deposited in the recess and reacted to form silicide at the bottom of the recess. The recess is filled with fill material, which is polished. The hardmask is then removed to form a silicide buried local interconnect.

Abstract: A MOS solid-state imaging device having: a semiconductor substrate provided with a pair of source and drain regions in a pixel area, the pair of source and drain regions constituting part of a transistor in the pixel area; an insulating film formed over the semiconductor substrate; a wiring layer formed over the insulating film; and a contact plug penetrating through the insulating film to connect either one of the pair of source and drain regions with the wiring layer, wherein a surface area of said one of the pair of source and drain regions is silicided, the surface area contacting with the contact plug, and a width of the surface area is equal to a width of the contact plug.

Abstract: The embodiments of methods described in this disclosure for trimming back nitride spacers for replacement gates allows the hard mask layers (or hard mask) to protect the polysilicon above the high-K dielectric during trim back process. The process sequence also allows determining the trim-back amount based on the process uniformity (or control) of nitride deposition and nitride etchback (or trimming) processes. Nitride spacer trim-back process integration is critical to avoid creating undesirable consequences, such as silicided polyisicon on top of high-K dielectric described above. The integrated process also allows widening the space between the gate structures to allow formation of silicide with good quality and allow contact plugs to have sufficient contact with the silicide regions. The silicide with good quality and good contact between the contact plugs and the silicide regions increase the yield of contact and allows the contact resistance to be in acceptable and workable ranges.

Abstract: A semiconductor device comprises insulating layer including damascene patterns and formed over a semiconductor substrate, conductive line formed higher than the insulating layer within the respective damascene patterns, and interference-prevention grooves formed within the damascene patterns between sidewalls of the conductive line and the insulating layer.

Abstract: A cap layer for a copper interconnect structure formed in a first dielectric layer is provided. In an embodiment, a conductive layer is located within a dielectric layer and a top surface of the conductive layer has either a recess, a convex surface, or is planar. An alloy layer overlies the conductive layer and is a silicide alloy having a first material from the conductive layer and a second material of germanium, arsenic, tungsten, or gallium.

Abstract: A method is provided for forming an interconnect in a semiconductor memory device. The method includes forming a pair of source select transistors on a substrate. A source region is formed in the substrate between the pair of source select transistors. A first inter-layer dielectric is formed between the pair of source select transistors. A mask layer is deposited over the pair of source select transistors and the inter-layer dielectric, where the mask layer defines a local interconnect area between the pair of source select transistors having a width less than a distance between the pair of source select transistors. The semiconductor memory device is etched to remove a portion of the first inter-layer dielectric in the local interconnect area, thereby exposing the source region. A metal contact is formed in the local interconnect area.

Abstract: A method of forming a semiconductor device includes forming a lower conductive pattern on a substrate, forming an insulating layer over the lower conductive pattern, forming a contact hole through the insulating layer to expose the lower conductive pattern, forming a first spacer along sides of the contact hole, and then forming a contact plug in the contact hole. The contact plug is formed so as to contact the lower conductive pattern.

Abstract: Methods for fabricating a semiconductor device are disclosed. A metal-rich silicide and/or a mono-silicide is formed on source/drain (S/D) regions. A millisecond anneal is provided to the metal-rich silicide and/or the mono-silicide to form a di-silicide with limited spikes at the interface between the silicide and substrate. The di-silicide has an additive which can lower the electron Schottky barrier height.

Abstract: The semiconductor structure is provided that has entirely self-aligned metallic contacts. The semiconductor structure includes at least one field effect transistor located on a surface of a semiconductor substrate. The at least one field effect transistor includes a gate conductor stack comprising a lower layer of polysilicon and an upper layer of a first metal semiconductor alloy, the gate conductor stack having sidewalls that include at least one spacer. The structure further includes a second metal semiconductor alloy layer located within the semiconductor substrate at a footprint of the at least one spacer.

Abstract: A method is provided for forming an interconnect in a semiconductor memory device. The method includes forming a pair of source select transistors on a substrate. A source region is formed in the substrate between the pair of source select transistors. A first inter-layer dielectric is formed between the pair of source select transistors. A mask layer is deposited over the pair of source select transistors and the inter-layer dielectric, where the mask layer defines a local interconnect area between the pair of source select transistors having a width less than a distance between the pair of source select transistors. The semiconductor memory device is etched to remove a portion of the first inter-layer dielectric in the local interconnect area, thereby exposing the source region. A metal contact is formed in the local interconnect area.

Abstract: Reliability of a semiconductor element and its product yield are improved by reducing variations in the electrical characteristic of a metal silicide layer. After forming a nickel-platinum alloy film over a semiconductor substrate, by carrying out a first thermal treatment at a thermal treatment temperature of 210 to 310° C. using a heater heating device, the technique causes the nickel-platinum alloy film and silicon to react with each other to form a platinum-added nickel silicide layer in a (PtNi)2Si phase. After removing unreacted nickel-platinum alloy film, the technique carries out a second thermal treatment having the thermal treatment temperature higher than that of the first thermal treatment to form the platinum-added nickel silicide layer in a PtNiSi phase. The temperature rise rate of each thermal treatment is set to 10° C./s or more.

Abstract: A method of forming a semiconductor structure includes providing a substrate; forming a low-k dielectric layer over the substrate; embedding a conductive wiring into the low-k dielectric layer; and thermal soaking the conductive wiring in a carbon-containing silane-based chemical to form a barrier layer on the conductive wiring. A lining barrier layer is formed in the opening for embedding the conductive wiring. The lining barrier layer may comprise same materials as the barrier layer, and the lining barrier layer may be recessed before forming the barrier layer and may contain a metal that can be silicided.

Abstract: A method of manufacturing a microelectronic device including forming a dielectric layer surrounding a dummy feature located over a substrate, removing the dummy feature to form an opening in the dielectric layer, and forming a metal-silicide layer conforming to the opening. The metal-silicide layer may then be annealed.

Abstract: Electromigration behavior in complex metallization systems of semiconductor devices may be enhanced at critical areas between a metal line and a via by locally forming a copper/silicon compound. In some illustrative embodiments, the formation of the copper/silicon compound may be combined with other treatments for cleaning the exposed surface areas and/or modifying the molecular structure thereof.

Abstract: Methods for forming cobalt silicide materials are disclosed herein. In one example, a method for forming a cobalt silicide material includes exposing a substrate having a silicon-containing material to either a wet etch solution or a pre-clean plasma during a first step and then to a hydrogen plasma during a second step of a pre-clean process. The exemplary method further includes depositing a cobalt metal layer on the silicon-containing material by a CVD process, heating the substrate to form a first cobalt silicide layer comprising CoSi at the interface of the cobalt metal layer and the silicon-containing material during a first annealing process, removing any unreacted cobalt metal from the first cobalt silicide layer during an etch process, and heating the substrate to form a second cobalt silicide layer comprising CoSi2 during a second annealing process.

Abstract: Silicide films with high quality are formed with treatment of laser light irradiation, so that miniaturization and higher performance is achieved in a field-effect transistor that is formed over an insulating substrate and has little variation in electric characteristics. An island-shaped semiconductor film including a pair of impurity regions and a channel formation region is formed over an insulating substrate, a first metal film is formed on the pair of impurity regions, and a second metal film that functions as a reflective film is formed over a gate electrode located over the channel formation region with a gate insulating film interposed therebetween. The first metal film is irradiated with laser light and a region where the second metal film is formed reflects the laser light, so that the island-shaped semiconductor film and the first metal film selectively react with each other in the pair of impurity regions.

Abstract: A semiconductor device with improved roll-off resistivity and reliability are provided. The semiconductor device includes a gate dielectric overlying a semiconductor substrate, a gate electrode overlying the gate dielectric, a gate silicide region on the gate electrode, a source/drain region adjacent the gate dielectric, and a source/drain silicide region on the source/drain region, wherein the source/drain silicide region and the gate silicide region have different metal compositions.

Abstract: Methods for manufacturing buried silicide lines are described herein, along with high density stacked memory structures. A method for manufacturing an integrated circuit as described herein includes forming a semiconductor body comprising silicon. A plurality of trenches are formed in the semiconductor body to define semiconductor lines comprising silicon between adjacent trenches, the semiconductor lines having sidewalls. A silicide precursor is deposited within the trenches to contact the sidewalls of the semiconductor lines, and a portion of the silicide precursor is removed to expose upper portions of the sidewalls and leave remaining strips of silicide precursor along the sidewalls. Silicide conductors are then formed by inducing reaction of the strips of silicide with the silicon of the semiconductor lines.

Abstract: To provide a semiconductor device which can reduce an electrical resistance between a plug and a silicide region, and a manufacturing method thereof. At least one semiconductor element having a silicide region, is formed over a semiconductor substrate. An interlayer insulating film is formed over the silicide region. A through hole having an inner surface including a bottom surface comprised of the silicide regions is formed in the interlayer insulating film. A Ti(titanium) film covering the inner surface of the hole is formed by a chemical vapor deposition method. At least a surface of the Ti film is nitrided so as to form a barrier metal film covering the inner surface. A plug is formed to fill the through hole via the barrier metal film.

Abstract: A semiconductor device includes a semiconductor substrate, a first insulating film provided on the semiconductor substrate, a charge storage layer provided on the first insulating film, a second insulating film comprising a plurality of insulating films provided on the charge storage layer and comprising a nitride film as an uppermost layer, and a single-layer control gate electrode provided on the second insulating film and comprising metal silicide.

Abstract: A method of manufacturing a semiconductor device includes forming a gate electrode, a source region and a drain region, forming a first metal layer, forming silicide layers by first annealing, removing a remainder of the first metal layer after the first annealing, performing a second annealing, forming a second metal layer, performing a third annealing, and removing a remainder of the second metal layer.

Abstract: A method of forming the conductive lines of a semiconductor memory device comprises forming a first polysilicon layer over an underlying layer, forming first polysilicon patterns by patterning the first polysilicon layer, filling the space between the first polysilicon patterns with an insulating layer, etching a top portion of the first polysilicon patterns to form recess regions, forming spacers on the sidewalls of the recess regions, filling the recess regions with a second polysilicon layer to form second polysilicon patterns, and performing a metal silicidation process to convert the second polysilicon patterns to metal silicide patterns.

Abstract: A method for fabricating a contact of a semiconductor device includes the steps of forming a dielectric layer having a contact hole on a semiconductor substrate, forming an out-gassing barrier layer comprising a poly-silicon layer to cover at least inner walls of the contact hole in order to prevent undesired out-gassing from the dielectric layer, and depositing an aluminum layer on the out-gassing barrier layer. The contact structure of the semiconductor device includes the aluminum layer filled in the contact layer formed on the semiconductor substrate, and the out-gassing barrier layer formed under the aluminum layer to prevent out-gassing from the dielectric layer. A fine contact can be formed along with the aluminum layer, thereby realizing the contact structure of a lower contact resistance. As a result, it is possible to realize stabilization of an overall contact resistance of the semiconductor device.

Abstract: The invention relates to a method for selective deposition of Si or SiGe on a Si or SiGe surface. The method exploits differences in physico-chemical surface behavior according to a difference in doping of first and second surface regions. By providing at least one first surface region with a Boron doping of a suitable concentration range and exposing the substrate surface to a cleaning and passivating ambient atmosphere in a prebake step at a temperature lower or equal than 800° C., a subsequent deposition step of Si or SiGe will not lead to a layer deposition in the first surface region. This effect is used for selective deposition of Si or SiGe in the second surface region, which is not doped with Boron in the suitable concentration range, or doped with another dopant, or not doped. The method thus saves a usual photolithography sequence required for selective deposition of Si or SiGe in the second surface region according to the prior art.

Abstract: A cap layer for a copper interconnect structure formed in a first dielectric layer is provided. In an embodiment, the cap layer may be formed by an in-situ deposition process in which a process gas comprising germanium, arsenic, tungsten, or gallium is introduced, thereby forming a copper-metal cap layer. In another embodiment, a copper-metal silicide cap is provided. In this embodiment, silane is introduced before, during, or after a process gas is introduced, the process gas comprising germanium, arsenic, tungsten, or gallium. Thereafter, an optional etch stop layer may be formed, and a second dielectric layer may be formed over the etch stop layer or the first dielectric layer.

Abstract: The embodiments of methods described in this disclosure for trimming back nitride spacers for replacement gates allows the hard mask layers (or hard mask) to protect the polysilicon above the high-K dielectric during trim back process. The process sequence also allows determining the trim-back amount based on the process uniformity (or control) of nitride deposition and nitride etchback (or trimming) processes. Nitride spacer trim-back process integration is critical to avoid creating undesirable consequences, such as silicided polyisicon on top of high-K dielectric described above. The integrated process also allows widening the space between the gate structures to allow formation of silicide with good quality and allow contact plugs to have sufficient contact with the silicide regions. The silicide with good quality and good contact between the contact plugs and the silicide regions increase the yield of contact and allows the contact resistance to be in acceptable and workable ranges.

Abstract: To provide a technique capable of improving the reliability of a semiconductor element and its product yield by reducing the variations in the electrical characteristic of a metal silicide layer. After forming a nickel-platinum alloy film over a semiconductor substrate 1, by carrying out a first thermal treatment at a thermal treatment temperature of 210 to 310° C. using a heater heating device, the technique causes the nickel-platinum alloy film and silicon to react with each other to form a platinum-added nickel silicide layer in a (PtNi)2Si phase. Subsequently, after removing the unreacted nickel-platinum alloy film, the technique carries out a second thermal treatment having the thermal treatment temperature higher than that of the first thermal treatment to form the platinum-added nickel silicide layer in a PtNiSi phase. The temperature rise rate of the first thermal treatment is set to 10° C./s or more (for example, 30 to 250° C.

Abstract: A semiconductor structure includes a semiconductor substrate; a gate dielectric over the semiconductor substrate; a gate electrode over the gate dielectric; a source/drain region adjacent the gate dielectric; a silicide region on the source/drain region; a metal layer on top of, and physical contacting, the silicide region; an inter-layer dielectric (ILD) over the metal layer; and a contact opening in the ILD. The metal layer is exposed through the contact opening. The metal layer further extends under the ILD. The semiconductor structure further includes a contact in the contact opening.

Abstract: A hard mask is formed on an interconnect structure comprising a low-k material layer and a metal feature embedded therein. A block polymer is applied to the hard mask layer, self-assembled, and patterned to form a polymeric matrix of a polymeric block component and containing cylindrical holes. The hard mask and the low-k material layer therebelow are etched to form cavities. A conductive material is plated on exposed metallic surfaces including portions of top surfaces of the metal feature to form metal pads. Metal silicide pads are formed by exposure of the metal pads to a silicon containing gas. An etch is performed to enlarge and merge the cavities in the low-k material layer. The metal feature is protected from the etch by the metal silicide pads. An interconnect structure having an air gap and free of defects to surfaces of the metal feature is formed.

Abstract: The present invention relates to a method for producing a vertical interconnect structure, a memory device and an associated production method, in which case, after the formation of a contact region in a carrier substrate a catalyst is produced on the contact region and a free-standing electrically conductive nanoelement is subsequently formed between the catalyst and the contact region and embedded in a dielectric layer.

Abstract: The invention included to methods of forming CoSi2, methods of forming field effect transistors, and methods of forming conductive contacts. In one implementation, a method of forming CoSi2 includes forming a substantially amorphous layer comprising MSix over a silicon-containing substrate, where “M” comprises at least some metal other than cobalt. A layer comprising cobalt is deposited over the substantially amorphous MSix-comprising layer. The substrate is annealed effective to diffuse cobalt of the cobalt-comprising layer through the substantially amorphous MSix-comprising layer and combine with silicon of the silicon-containing substrate to form CoSi2 beneath the substantially amorphous MSix-comprising layer. Other aspects and implementations are contemplated.

Abstract: Methods and structures are provided for full silicidation of recessed silicon. Silicon is provided within a trench. A mixture of metals is provided over the silicon in which one of the metals diffuses more readily in silicon than silicon does in the metal, and another of the metals diffuses less readily in silicon than silicon does in the metal. An exemplary mixture includes 80% nickel and 20% cobalt. The silicon within the trench is allowed to fully silicide without void formation, despite a relatively high aspect ratio for the trench. Among other devices, recessed access devices (RADs) can be formed by the method for memory arrays.

Abstract: A method of forming a semiconductor structure includes providing a substrate; forming a low-k dielectric layer over the substrate; embedding a conductive wiring into the low-k dielectric layer; and thermal soaking the conductive wiring in a carbon-containing silane-based chemical to form a barrier layer on the conductive wiring. A lining barrier layer is formed in the opening for embedding the conductive wiring. The lining barrier layer may comprise same materials as the barrier layer, and the lining barrier layer may be recessed before forming the barrier layer and may contain a metal that can be silicided.

Abstract: A method for fabricating a semiconductor device includes forming electrode patterns over a substrate, wherein the electrode patterns include a hard mask, forming a passivation layer on the electrode patterns, forming an insulation layer on the passivation layer, filling a space between the electrode patterns, planarizing the insulation layer until shoulder portions of the hard mask are planarized, forming a mask pattern on a resultant structure, and etching a portion of the insulation layer to form a contact hole.

Abstract: A method is provided for forming an interconnect in a semiconductor memory device. The method includes forming a pair of source select transistors on a substrate. A source region is formed in the substrate between the pair of source select transistors. A first inter-layer dielectric is formed between the pair of source select transistors. A mask layer is deposited over the pair of source select transistors and the inter-layer dielectric, where the mask layer defines a local interconnect area between the pair of source select transistors having a width less than a distance between the pair of source select transistors. The semiconductor memory device is etched to remove a portion of the first inter-layer dielectric in the local interconnect area, thereby exposing the source region. A metal contact is formed in the local interconnect area.

Abstract: Methods of forming metal silicide layers. The methods include: forming a silicon-rich layer between dielectric layers; contacting the silicon-rich layer with a metal layer and heating the silicon rich-layer and the metal layer to diffuse metal atoms from the metal layer into the silicon layer to form a metal silicide layer.

Abstract: Silicide films with high quality are formed with treatment of laser light irradiation, so that miniaturization and higher performance is achieved in a field-effect transistor that is formed over an insulating substrate and has little variation in electric characteristics. An island-shaped semiconductor film including a pair of impurity regions and a channel formation region is formed over an insulating substrate, a first metal film is formed on the pair of impurity regions, and a second metal film that functions as a reflective film is formed over a gate electrode located over the channel formation region with a gate insulating film interposed therebetween. The first metal film is irradiated with laser light and a region where the second metal film is formed reflects the laser light, so that the island-shaped semiconductor film and the first metal film selectively react with each other in the pair of impurity regions.

Abstract: The present disclosure relates to a microelectronic structure and the manufacture of the microelectronic structure. Specifically, the disclosure relates to an interconnect barrier layer between a rhodium contact structure and a copper interconnect structure in a microelectronic structure. The microelectronic structure provides for low resistance in microelectronic devices.

Abstract: A method for manufacturing a semiconductor device includes forming an insulation layer having a contact hole on a semiconductor substrate. A metal silicide layer is deposited on a surface of the contact hole and the insulation layer to have a concentration gradient that changes from a silicon-rich composition to a metal-rich composition, with the lower portion of the metal silicide layer having the silicon-rich composition and the upper portion of the metal silicide layer having the metal-rich composition. The metal silicide layer is then annealed so that the compositions of metal and silicon in the metal silicide layer become uniform.

Abstract: Semiconductor devices and methods of fabricating semiconductor devices are disclosed. A disclosed semiconductor device includes a silicon substrate, a source region and a drain region. A gate electrode is formed on the silicon substrate. Also, a metal silicide layer is formed on each of the gate electrode, the source region, and the drain region. The metal silicide layer has a thickness uniformity of about 1˜20%. A disclosed fabrication method includes forming a metal layer on a silicon substrate having a gate electrode, a source region, and a drain region; performing a plasma treatment on the metal layer; forming a protective layer on the metal layer; and heat treating the silicon substrate on which the protective layer is formed to thereby form a metal silicide layer. A gas that includes nitrogen is used as a plasma gas during the plasma treatment.

Abstract: A method for fabricating metal-oxide transistors is disclosed. First, a semiconductor substrate having a gate structure is provided, in which the gate structure includes a gate dielectric layer and a gate. A source/drain region is formed in the semiconductor substrate, and a cleaning step is performed to fully remove native oxides from the surface of the semiconductor substrate. An oxidation process is conducted to form an oxide layer on the semiconductor substrate and the oxide layer is then treated with fluorine-containing plasma to form a fluorine-containing layer on the surface of the semiconductor substrate. A metal layer is deposited on the semiconductor substrate thereafter and a thermal treatment is performed to transform the metal layer into a silicide layer.

Abstract: By performing a silicidation process on the basis of a patterned dielectric layer, such as an interlayer dielectric material, the respective metal silicide portions may be provided in a highly localized manner at the respective contact regions, while the overall amount of metal silicide may be significantly reduced. In this way, a negative influence of the stress of metal silicide on the channel regions of field effect transistors may be significantly reduced, while nevertheless maintaining a low contact resistance.

Abstract: A method of manufacturing a semiconductor device includes forming a first conductive film on a semiconductor substrate via a first insulating film; forming a second conductive film on the first conductive film via a second insulating film; patterning the first and the second conductive films and the second insulating film to form a plurality of gate electrodes; filling a third insulating film between the plurality of gate electrodes; exposing an upper portion of the second conductive film by removing the third insulating film; covering surfaces of the exposed upper portion of the second conductive film with fluoride (F) or carbon (C) or oxygen (O); and forming a metal film on an upper surface of the second conductive film; and forming silicide layers on the upper portion of the second conductive films by thermally treating the metal film.

Abstract: A buried local interconnect and method of forming the same counterdopes a region of a doped substrate to form a counterdoped isolation region. A hardmask is formed and patterned on the doped substrate, with a recess being etched through the patterned hardmask into the counterdoped region. Dielectric spacers are formed on the sidewalls of the recess, with a portion of the bottom of the recess being exposed. A metal is then deposited in the recess and reacted to form silicide at the bottom of the recess. The recess is filled with fill material, which is polished. The hardmask is then removed to form a silicide buried local interconnect.

Abstract: A method of manufacturing a microelectronic device including forming a dielectric layer surrounding a dummy feature located over a substrate, removing the dummy feature to form an opening in the dielectric layer, and forming a metal-silicide layer conforming to the opening by a metal deposition process employing a target which includes metal and silicon. The metal-silicide layer may then be annealed.

Abstract: A processing layer, such as silicon, is formed on a metal silicide contact followed by a metal layer. The silicon and metal layers are annealed to increase the thickness of the metal silicide contact. By selectively increasing the thickness of silicide contacts, Rs of transistors in iso and nested regions can be matched.