Patent Publication Number: US-2022238518-A1

Title: Semiconductor device and method of fabricating the same

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This U.S. nonprovisional application is a continuation of U.S. application Ser. No. 16/825,030, filed on Mar. 20, 2020, which claims priority under 35 U.S.C § 119 to Korean Patent Application No. 10-2019-0094554, filed on Aug. 2, 2019, in the Korean Intellectual Property Office, the disclosures of which are incorporated by reference herein in their entirety. 
    
    
     TECHNICAL FIELD 
     The present inventive concept relates to a semiconductor device and a method of fabricating the same, and more particularly, to a semiconductor device including a fin field effect transistor and a method of fabricating the same. 
     DISCUSSION OF RELATED ART 
     Metal oxide semiconductor field effect transistors (MOSFETs) are widely used semiconductor devices in very large scale integrated circuits. As the semiconductor devices become increasingly integrated with the advancement of the electronic industry, the MOSFETs have been scaled down in accordance with the reduced design rule of the semiconductor devices. The scale down of MOSFETs may deteriorate operating characteristics of the semiconductor devices. Accordingly, a variety of research has been conducted to develop methods of fabricating semiconductor devices having superior performance while overcoming issues associated with high integration of the semiconductor devices. 
     SUMMARY 
     Example embodiments of the present inventive concept provide a semiconductor device with enhanced reliability, and also provide a method of fabricating the semiconductor device, in which the method can increase yield. 
     According to an example embodiment of the present inventive concept, a semiconductor device may include: a first gate pattern and a second gate pattern that are spaced apart from each other in a first direction on a substrate, each of the first gate pattern and the second gate pattern extending in the first direction; a separation pattern disposed between and being in direct contact with the first gate pattern and the second gate pattern, the separation pattern extending in a second direction that intersects the first direction; a third gate pattern spaced apart in the second direction from the first gate pattern, the third gate pattern extending in the first direction; and an interlayer dielectric layer disposed between the first gate pattern and the third gate pattern. The separation pattern may include a material different from a material of the interlayer dielectric layer. A bottom surface of the separation pattern may have an uneven structure. 
     According to an example embodiment of the present inventive concept, a semiconductor device may include: a first active fin and a second active fin that protrude from a substrate and are spaced apart from each other; a device isolation layer that covers a top surface of the substrate and exposes a top surface and a lateral surface of the first active fin and a top surface and a lateral surface of the second active fin; a first gate pattern that covers the top surface and the lateral surface of the first active fin; a second gate pattern that is spaced apart in a first direction from the first gate pattern and covers the top surface and the lateral surface of the second active fin; a first interlayer dielectric layer that covers a lateral surface of the first gate pattern; and a first separation pattern disposed on the device isolation layer between the first gate pattern and the second gate pattern, the first separation pattern being in direct contact with the first gate pattern and the second gate pattern. The first separation pattern may include a material different from a material of the first interlayer dielectric layer. The first separation pattern may include: a first separation segment disposed between the first gate pattern and the second gate pattern; and a first part that extends from the first separation segment and is positioned outside one sidewall of the first gate pattern. 
     According to an example embodiment of the present inventive concept, a semiconductor device may include: a first gate pattern and a second gate pattern that are spaced apart from each other in a first direction on a substrate; a first interlayer dielectric layer being in contact with a sidewall of the first gate pattern; a separation pattern disposed between the first gate pattern and the second gate pattern and being in direct contact with the first gate pattern and the second gate pattern; a first source/drain pattern positioned adjacent to the first gate pattern; a second source/drain pattern positioned adjacent to the second gate pattern; and a contact plug being in direct contact with top surfaces of the first and second source/drain patterns. The separation pattern may include a material different from a material of the first interlayer dielectric layer. A bottom surface of the contact plug may have an uneven structure. 
     According to an example embodiment of the present inventive concept, a method of fabricating a semiconductor device may include: preparing a substrate that includes a separation mask opening region extending in a first direction and a contact region intersecting the separation mask opening region, the separation mask opening region including a separation region and an overlapping region that overlaps the contact region; forming a preliminary gate pattern on the substrate, the preliminary gate pattern running across the separation region on a side of the contact region; forming an interlayer dielectric layer that is on the contact region and covers a sidewall of the preliminary gate pattern; removing the preliminary gate pattern from the separation region and etching a portion of the interlayer dielectric layer to form a first gate pattern and a second gate pattern and simultaneously to form a separation trench on the separation mask opening region; forming a separation pattern that fills the separation trench, the separation pattern including a material different from a material of the interlayer dielectric layer; replacing at least a portion of the separation pattern with a buried dielectric pattern on the overlapping region; forming a contact hole by removing the interlayer dielectric layer from the contact region and removing the buried dielectric pattern from the overlapping region; and forming a contact plug in the contact hole. 
     According to an example embodiment of the present inventive concept, a method of fabricating a semiconductor device may include: preparing a substrate that includes a separation mask opening region extending in a first direction and a contact region intersecting the separation mask opening region, the separation mask opening region including a separation region and an overlapping region that overlaps the contact region; forming a preliminary gate pattern on the substrate, the preliminary gate pattern running across the separation region on a side of the contact region; forming an interlayer dielectric layer that is on the contact region and covers a sidewall of the preliminary gate pattern; removing the preliminary gate pattern from the separation region and etching a portion of the interlayer dielectric layer to form a first gate pattern and a second gate pattern and simultaneously to form a separation trench on the separation mask opening region; forming a sacrificial pattern in the separation trench on the separation region; forming a buried dielectric pattern in the separation trench on the overlapping region; and replacing the sacrificial pattern with a separation pattern. The separation pattern may include a material different from a material of the interlayer dielectric layer. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other aspects and features of the present inventive concept will become more apparent by describing in detail example embodiments thereof with reference to the accompanying drawings, in which: 
         FIG. 1A  illustrates a plan view showing a semiconductor device according to an example embodiment of the present inventive concept; 
         FIG. 1B  illustrates a cross-sectional view taken along lines A-A′, B-B′, and C-C′ of  FIG. 1A , according to an example embodiment of the present inventive concept; 
         FIG. 1C  illustrates a cross-sectional view taken along line D-D′ of  FIG. 1A , according to an example embodiment of the present inventive concept; 
         FIGS. 2A to 8A  illustrate plan views showing a method of fabricating the semiconductor device of  FIG. 1A ; 
         FIGS. 2B to 8B  illustrate cross-sectional views showing a method of fabricating the semiconductor device of  FIG. 1B ; 
         FIG. 9A  illustrates a plan view showing a semiconductor device according to an example embodiment of the present inventive concept; 
         FIG. 9B  illustrates a cross-sectional view taken along lines A-A′, B-B′, and C-C′ of  FIG. 9A , according to an example embodiment of the present inventive concept; 
         FIG. 10  illustrates a cross-sectional view taken along lines A-A′, B-B′, and C-C′ of  FIG. 9A , according to an example embodiment of the present inventive concept; 
         FIGS. 11A to 11E  illustrate cross-sectional views showing a method of fabricating the semiconductor device of  FIG. 9B or 10 ; 
         FIG. 12A  illustrates a plan view showing a semiconductor device according to an example embodiment of the present inventive concept; 
         FIG. 12B  illustrates a cross-sectional view taken along lines A-A′, B-B′, and C-C′ of  FIG. 12A , according to an example embodiment of the present inventive concept; 
         FIG. 13A  illustrates a plan view showing a semiconductor device according to an example embodiment of the present inventive concept; 
         FIG. 13B  illustrates a cross-sectional view taken along lines A-A′, B-B′, and C-C′ of  FIG. 13A , according to an example embodiment of the present inventive concept; 
         FIG. 14  illustrates a cross-sectional view taken along lines A-A′, B-B′, and C-C′ of  FIG. 13A , according to an example embodiment of the present inventive concept; 
         FIG. 15A  illustrates a plan view showing a semiconductor device according to an example embodiment of the present inventive concept; 
         FIG. 15B  illustrates a cross-sectional view taken along lines A-A′, B-B′, and C-C′ of  FIG. 15A , according to an example embodiment of the present inventive concept; 
         FIG. 16A  illustrates a plan view showing a semiconductor device according to an example embodiment of the present inventive concept; 
         FIG. 16B  illustrates a cross-sectional view taken along lines A-A′, B-B′, and C-C′ of  FIG. 16A , according to an example embodiment of the present inventive concept; 
         FIG. 17  illustrates a cross-sectional view taken along lines A-A′, B-B′, and C-C′ of  FIG. 16A , according to an example embodiment of the present inventive concept; 
         FIG. 18A  illustrates a plan view showing a semiconductor device according to an example embodiment of the present inventive concept; 
         FIG. 18B  illustrates a cross-sectional view taken along lines A-A′, B-B′, and C-C′ of  FIG. 18A , according to an example embodiment of the present inventive concept; 
         FIG. 19A  illustrates a plan view showing a semiconductor device according to an example embodiment of the present inventive concept; 
         FIG. 19B  illustrates a cross-sectional view taken along lines A-A′, B-B′, and C-C′ of  FIG. 19A , according to an example embodiment of the present inventive concept; and 
         FIG. 20  illustrates a cross-sectional view taken along lines A-A′, B-B′, and C-C′ of  FIG. 9A , according to an example embodiment of the present inventive concept. 
     
    
    
     Since the drawings in  FIGS. 1-20  are intended for illustrative purposes, the elements in the drawings are not necessarily drawn to scale. For example, some of the elements may be enlarged or exaggerated for clarity purpose. 
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Example embodiments of the present inventive concept will now be described in detail with reference to the accompanying drawings to aid in clearly explaining the present inventive concept. 
       FIG. 1A  illustrates a plan view showing a semiconductor device according to an example embodiment of the present inventive concept.  FIG. 1B  illustrates a cross-sectional view taken along lines A-A′, B-B′, and C-C′ of  FIG. 1A , according to an example embodiment of the present inventive concept.  FIG. 1C  illustrates a cross-sectional view taken along line D-D′ of  FIG. 1A , according to an example embodiment of the present inventive concept. In  FIG. 1A , there is an illustration that may correspond to a portion of a static random-access memory (SRAM) device or to a portion of a logic/peripheral circuit region. 
     Referring to  FIGS. 1A to 1C , a substrate  1  may be provided. The substrate  1  may be, for example, a single-crystalline silicon wafer or a silicon-on-insulator (SOI) substrate. Alternatively, the substrate  1  may be a silicon substrate including silicon (Si), for example, single crystalline silicon (Si), polycrystalline silicon (Si), amorphous silicon (Si), or a combination thereof, and/or may include other materials such as silicon germanium (SiGe), silicon germanium on insulator (SGOI), indium antimonide (InSb), a lead tellurium compound (PbTe), gallium phosphide (GaP), indium arsenide (InAs), indium phosphide (InP), gallium arsenide (GaAs), or gallium antimonide (GaSb). The substrate  1  may include a separation mask opening region SMR and a contact region CR 1  and CR 2 . When viewed in plan view, the separation mask opening region SMR may have a bar shape that extends in a first direction x. The contact region CR 1  and CR 2  may include a first contact region CR 1  and a second contact region CR 2  that are spaced apart from each other in the first direction x. When viewed in plan view, the first and second contact regions CR 1  and CR 2  may each have a bar shape that extends in a second direction y intersecting the first direction x. When viewed in plan view, the separation mask opening region SMR may overlap the contact region CR 1  and CR 2 . A first overlapping region OR 1  may be defined to indicate an area where the separation mask opening region SMR overlaps the first contact region CR 1 . A second overlapping region OR 2  may be defined to indicate an area where the separation mask opening region SMR overlaps the second contact region CR 2 . 
     A first active fin AF 1  and a second active fin AF 2  may protrude from a top surface of the substrate  1 . When viewed in plan view, the first active fin AF 1  and the second active fin AF 2  may each have a linear shape that extends in the first direction x, and may be spaced apart from each other in the second direction y. The first active fin AF 1  and the second active fin AF 2  may be arranged in parallel to each other. A device isolation layer  3  may cover the top surface of the substrate  1  and lower lateral surfaces of the first and second active fins AF 1  and AF 2 , and thus may surround and define the first and second active fins AF 1  and AF 2 . The device isolation layer  3  may have a single-layered or multi-layered structure including one or more selected from, for example, a silicon oxide (SiO 2 ) layer, a silicon nitride (Si 3 N 4 ) layer, and a silicon oxynitride (SiON) layer. The device isolation layer  3  may have a top surface lower than those of the first and second active fins AF 1  and AF 2 . 
     Gate patterns GP 0  to GP 5  may each run across the first active fin AF 1  and/or the second active fin AF 2 . A zeroth gate pattern GP 0  and a fifth gate pattern GP 5  that are spaced apart from each other in the first direction x may each run across all of the first and second active fins AF 1  and AF 2 . A first gate pattern GP 1  and a second gate pattern GP 2  may be positioned between the zeroth gate pattern GP 0  and the fifth gate pattern GP 5 , and may be spaced apart from each other in the second direction y. A third gate pattern GP 3  may be disposed between the first gate pattern GP 1  and the fifth gate pattern GP 5 . A fourth gate pattern GP 4  may be disposed between the second gate pattern GP 2  and the fifth gate pattern GP 5 . The third gate pattern GP 3  and the fourth gate pattern GP 4  may be spaced apart from each other in the second direction y. The first gate pattern GP 1  and the third gate pattern GP 3  may each run across the first active fin AF 1 . The second gate pattern GP 2  and the fourth gate pattern GP 4  may each run across the second active fin AF 2 . The gate patterns GP 0  to GP 5  are arranged neither on the separation mask opening region SMR, nor on the first and second contact regions CR 1  and CR 2 . 
     Each of the gate patterns GP 0  to GP 5  may include a gate dielectric layer GO, a gate electrode MG, and a gate capping pattern CAP. The gate dielectric layer GO may include one or more selected from, for example, a silicon oxide (SiO 2 ) layer and a high-k dielectric layer whose dielectric constant is greater than that of a silicon oxide (SiO 2 ) layer. The high-k dielectric layer may include a metal oxide layer, such as, for example, a hafnium oxide (HfO 2 ) layer, a lanthanum oxide (La 2 O 3 ) layer, a zirconium oxide (ZrO 2 ) layer, a tantalum oxide (Ta 2 O 5 ) layer, a titanium oxide (TiO 2 ) layer, or an aluminum oxide (Al 2 O 3 ) layer. The gate electrode MG may include one or more selected from, for example, an impurity-doped polysilicon (p-Si) layer, a metal nitride layer such as, for example, a titanium nitride (TiN) layer, a tungsten nitride (WN) layer, a molybdenum nitride (MoN) layer, and a tantalum nitride (TaN) layer, and a metal layer such as, for example, a tungsten (W) layer, a copper (Cu) layer, a titanium (Ti) layer, a tantalum (Ta) layer, a molybdenum (Mo) layer, and an aluminum (Al) layer. The gate capping pattern CAP may include a silicon nitride (Si 3 N 4 ) layer. 
     A separation pattern SP may be interposed between the first and second gate patterns GP 1  and GP 2  to separate the first and second gate patterns GP 1  and GP 2 , and between the third and fourth gate patterns GP 3  and GP 4  to separate the third and fourth gate patterns GP 3  and GP 4 . The separation pattern SP may be positioned on the separation mask opening region SMR of the substrate  1 . The separation pattern SP may be placed on the device isolation layer  3  between neighboring first and second active fins AF 1  and AF 2 . The separation pattern SP may be in contact with the device isolation layer  3 . For example, a portion of the separation pattern SP sandwiched between the first and second gate patterns GP 1  and GP 2  may be in contact with the device isolation layer  3  to electrically isolate the first and second gate patterns GP 1  and GP 2 , and a portion of the separation pattern SP sandwiched between the third and fourth gate patterns GP 3  and GP 4  may be in contact with the device isolation layer  3  to electrically isolate the third and fourth gate patterns GP 3  and GP 4 . The separation pattern SP may have a top surface at a height the same as that of those of the gate patterns GP 0  to GP 5 . 
     The separation pattern SP may include a first protrusion segment P 1 , a first separation segment S 1 , a second protrusion segment P 2 , a second separation segment S 2 , and a third protrusion segment P 3 . The first separation segment S 1  may be positioned between and in direct contact with the first gate pattern GP 1  and the second gate pattern GP 2 . The first separation segment S 1  may also be in direct contact with the device isolation layer  3 , so that the formation of a gate-bridge between the first gate pattern GP 1  and the second gate pattern GP 2  may be prevented. The second separation segment S 2  may be positioned between and in direct contact with the third gate pattern GP 3  and the fourth gate pattern GP 4 . The second separation segment S 2  may also be in direct contact with the device isolation layer  3 , so that the formation of a gate-bridge between the third gate pattern GP 3  and the fourth gate pattern GP 4  may be prevented. The first separation segment S 1  may be placed on a first separation region SR 1  of the substrate  1 . The second separation segment S 2  may be placed on a second separation region SR 2  of the substrate  1 . 
     The first protrusion segment P 1  may be connected to the first separation segment S 1  and may protrude toward the first overlapping region OR 1 . The second protrusion segment P 2  may be disposed between and may connect the first separation segment S 1  and the second separation segment S 2 . The first separation segment S 1  may be disposed between and may connect the first protrusion segment P 1  and the second protrusion segment P 2 . The third protrusion segment P 3  may be connected to the second separation segment S 2  and may protrude toward the second overlapping region OR 2 . The second separation segment S 2  may be disposed between and may connect the second protrusion segment P 2  and the third protrusion segment P 3 . The first protrusion segment P 1  may be positioned on the first overlapping region OR 1  of the substrate  1 . The third protrusion segment P 3  may be positioned on the second overlapping region OR 2  of the substrate  1 . On the substrate  1 , the second protrusion segment P 2  may be positioned on a middle region MR between the first separation region SR 1  and the second separation region SR 2 . The separation mask opening region SMR may include the first and second overlapping regions OR 1  and OR 2 , the first and second separation regions SR 1  and SR 2 , and the middle region MR. 
     The first separation segment S 1 , the second protrusion segment P 2 , and the second separation segment S 2  may have their top surfaces at the same height, for example, being coplanar. The first and third protrusion segments P 1  and P 3  may have their top surfaces lower than those of the first separation segment S 1 , the second protrusion segment P 2 , and the second separation segment S 2 . The first and second separation segments S 1  and S 2  may have their bottom surfaces at the same height, and may be in contact with the device isolation layer  3 . The first, second, and third protrusion segments P 1 , P 2 , and P 3  may have their bottom surfaces at the same height. The bottom surfaces of the first, second, and third protrusion segments P 1 , P 2 , and P 3  may be higher than those of the first and second separation segments S 1  and S 2 . For example, the second protrusion segment P 2  may extend from the first separation segment S 1  in a direction away from the first protrusion segment P 1 , and the top surface of the second protrusion segment P 2  may be coplanar with a top surface of the first separation segment S 1 . For example, the third protrusion segment P 3  may extend from the second separation segment S 2  in a direction away from the second protrusion segment P 2 , and the third protrusion segment P 3  may have a thickness the same as a thickness of the first protrusion segment P 1 . The thickness of the second protrusion segment P 2  may be larger than a thickness of the third protrusion segment P 3 . The thickness is measured in a third direction z. 
     The gate patterns GP 0  to GP 5  may have their sidewalls covered with spacers SC. The spacer SC may have a single-layered or multi-layered structure including one or more selected from, for example, a silicon oxide (SiO 2 ) layer, a silicon nitride (Si 3 N 4 ) layer, and a silicon oxynitride (SiON) layer. Source/drain patterns SD 1  and SD 2  may be disposed on the active fins AF 1  and AF 2  on sides of the gate patterns GP 0  to GP 5 . First source/drain patterns SD 1  may be placed on the first active fin AF 1 , and second source/drain patterns SD 2  may be placed on the second active fin AF 2 . The first and second source/drain patterns SD 1  and SD 2  may each include a semiconducting material selected from one of, for example, silicon (Si), germanium (Ge), silicon germanium (SiGe), silicon carbide (SiC), gallium arsenide (GaAs), etc. doped with n-type or p-type impurities. The first and second source/drain patterns SD 1  and SD 2  may have a hexagonal shape, but the present inventive concept is not limited thereto. 
     Spaces among the gate patterns GP 0  to GP 5  may be filled with a first interlayer dielectric layer IL 1 . The first interlayer dielectric layer IL 1  may be formed of a material, such as silicon oxide (SiO 2 ), having an etch selectivity with respect to a material of the gate capping pattern CAP. The first interlayer dielectric layer IL 1  may cover the source/drain patterns SD 1  and SD 2 . As shown in  FIG. 1C , above the first source/drain pattern SD 1 , the first interlayer dielectric layer IL 1  may be disposed between the first gate pattern GP 1  and the third gate pattern GP 3 . A second interlayer dielectric layer IL 2  may cover the gate patterns GP 0  to GP 5 , the separation pattern SP, and the first interlayer dielectric layer IL 1 . The second interlayer dielectric layer IL 2  may be formed of a material, such as silicon oxide (SiO 2 ), having an etch selectivity with respect to a material of the gate capping pattern CAP. In an example embodiment of the present inventive concept, the first and second interlayer dielectric layers IL 1  and IL 2  may be formed of the same material such as silicon oxide (SiO 2 ). However, the present inventive concept is not limited thereto. 
     On the first contact region CR 1 , a first contact plug CT 1  may penetrate the first and second interlayer dielectric layers IL 1  and IL 2 , and may be in contact with one of the first source/drain patterns SD 1  and also with one of the second source/drain patterns SD 2 . On the second contact region CR 2 , a second contact plug CT 2  may penetrate the first and second interlayer dielectric layers IL 1  and IL 2 , and may be in contact with another of the first source/drain patterns SD 1  and also with another of the second source/drain patterns SD 2 . A buried dielectric pattern FL may be interposed between the second interlayer dielectric layer IL 2  and an upper lateral surface of the first contact plug CT 1 . The buried dielectric pattern FL may include, for example, a silicon oxide (SiO 2 ) layer. The first interlayer dielectric layer IL 1 , the second interlayer dielectric layer IL 2 , and the buried dielectric pattern FL may be formed of the same material, and thus may have the same etch rate for ease of creating contact holes CH in the process of forming the first and second contact plugs CT 1  and CT 2 . The first contact plug CT 1  may be formed next to the first separation segment S 1 . For example, the first contact plug CT 1  may extend in the second direction y and may adjoin the first separation segment S 1  of the separation pattern SP. 
     The first protrusion segment P 1  of the separation pattern SP may be in contact with a bottom surface of the first contact plug CT 1 . For example, the separation pattern SP may extend in the first direction x, with a portion (e.g., the first protrusion segment P 1 ) being in contact with the bottom surface of the first contact plug CT 1 . The third protrusion segment P 3  of the separation pattern SP may be in contact with a bottom surface of the second contact plug CT 2 . The first protrusion segment P 1  may have one sidewall that is spaced apart from one sidewall of the first contact plug CT 1  adjacent to the first protrusion segment P 1 . A width of the first contact plug CT 1  in the first direction x may be larger a width of the first protrusion segment P 1  in the first direction x. The third protrusion segment P 3  may have one sidewall that is spaced apart from one sidewall of the second contact plug CT 2  adjacent to the third protrusion segment P 3 . A width of the second contact plug CT 2  in the first direction x may be larger a width of the third protrusion segment P 3  in the first direction x. 
     A bottom surface SPS of the separation pattern SP may have an uneven structure. Between the first and second gate patterns GP 1  and GP 2 , the bottom surface SPS of the separation pattern SP may have a first depth DP 1  from a bottom surface of the second interlayer dielectric layer IL 2 . For example, the first depth DP 1  may be measured in the third direction z from a top surface of the first separation segment S 1  to a bottom surface of the first separation segment S 1 . Below the first contact plug CT 1 , the bottom surface SPS of the separation pattern SP may have a second depth DP 2  from the bottom surface of the second interlayer dielectric layer IL 2 . For example, the second depth DP 2  may be measured in the third direction z from the top surface of the first separation segment S 1  to a bottom surface of the first protrusion segment P 1 . The first depth DP 1  may be greater than the second depth DP 2 . The first protrusion segment P 1 , the second protrusion segment P 2 , and the third protrusion segment P 3  may be respectively called a first part P 1 , a second part P 2 , and a third part P 3 . 
     A semiconductor device according to an example embodiment of the present inventive concept may have neither gate-bridges on the separation regions SR 1  and SR 2  nor contact-connection failure on the overlapping regions OR 1  and OR 2 , which may result in an increase in reliability of the semiconductor device. For example, no gate-bridges may be formed between the first and second gate patterns GP 1  and GP 2  on the first separation region SR 1 , and between the third and fourth gate patterns GP 3  and GP 4  on the second separation region SR 2 . Respectively on the overlapping regions OR 1  and OR 2 , the first and second contact plugs CT 1  and CT 2  may each be connected without failure to the first and second source/drain patterns SD 1  and SD 2 . The gate patterns GP 0  to GP 5 , the active fins AF 1  and AF 2 , and the source/drain patterns SD 1  and SD 2  may constitute a plurality of fin field effect transistors (FinFETs). 
       FIGS. 2A to 8A  illustrate plan views showing a method of fabricating the semiconductor device of  FIG. 1A .  FIGS. 2B to 8B  illustrate cross-sectional views showing a method of fabricating the semiconductor device of  FIG. 1B .  FIGS. 2B to 8B  illustrate cross-sectional views taken along lines A-A′, B-B′, and C-C′ of  FIGS. 2A to 8A , respectively. 
     Referring to  FIGS. 2A and 2B , a substrate  1  may be prepared. The substrate  1  may be, for example, a single-crystalline silicon (Si) wafer or a silicon-on-insulator (SOI) substrate. Alternatively, the substrate  1  may be a silicon substrate including silicon (Si), for example, single crystalline silicon (Si), polycrystalline silicon (Si), amorphous silicon (Si), or a combination thereof, and/or may include other materials such as silicon germanium (SiGe), silicon germanium on insulator (SGOI), indium antimonide (InSb), a lead tellurium compound (PbTe), gallium phosphide (GaP), indium arsenide (InAs), indium phosphide (InP), gallium arsenide (GaAs), or gallium antimonide (GaSb). The substrate  1  may include a separation mask opening region SMR, a first contact region CR 1 , and a second contact region CR 2 . The separation mask opening region SMR may include first and second overlapping regions OR 1  and OR 2  that respectively overlap the first and second contact regions CR 1  and CR 2 , first and second separation region SR 1  and SR 2  that are respectively adjacent to the first and second overlapping regions OR 1  and OR 2 , and a middle region MR positioned between the first and second separation regions SR 1  and SR 2 . The substrate  1  may be etched to form a first active fin AF 1  and a second active fin AF 2 . A device isolation layer  3  may be formed on the substrate  1  and may be etched to have a top surface lower than those of the first and second active fins AF 1  and AF 2 . Thus, the device isolation layer  3  may cover the top surface of the substrate  1  and lower lateral surfaces of the first and second active fins AF 1  and AF 2 , and thus may surround and define the first and second active fins AF 1  and AF 2 . When viewed in plan view, each of the first and second active fins AF 1  and AF 2  may be formed to have a linear shape that extends in a first direction x. The separation mask opening region SMR may be positioned between the first and second active fins AF 1  and AF 2 . Each of the first and second contact regions CR 1  and CR 2  may have a bar shape that extends in a second direction y, and may intersect the first and second active fins AF 1  and AF 2 . 
     Referring to  FIGS. 3A and 3B , a dielectric layer, a conductive layer, and a capping layer may be sequentially formed on the substrate  1  and thereafter may be patterned to form dummy gate patterns DGP 0 , DGP 1 , DGP 2 , and DGP 3  each of which includes a dummy gate dielectric layer DGO, a dummy gate electrode DG, and a dummy gate capping pattern DCP that are sequentially stacked. Each of the dummy gate patterns DGP 0 , DGP 1 , DGP 2 , and DGP 3  may have a linear shape that extends in the second direction y to cross over the first and second active fins AF 1  and AF 2 . The dummy gate dielectric layer DGO may include, for example, a silicon oxide (SiO 2 ) layer. The dummy gate electrode DG may include, for example, a polysilicon (p-Si) layer. The dummy gate capping pattern DCP may include, for example, a silicon nitride (Si 3 N 4 ) layer. Spacers SC may be formed to cover corresponding sidewalls of the dummy gate patterns DGP 0 , DGP 1 , DGP 2 , and DGP 3 . Each of the spacers SC may have a single-layered or multi-layered structure including one or more selected from, for example, a silicon oxide (SiO 2 ) layer, a silicon nitride (Si 3 N 4 ) layer, and a silicon oxynitride (SiON) layer. The first and second active fins AF 1  and AF 2  may be exposed at their top surfaces and upper sidewalls on sides of the spacers SC between the dummy gate patterns DGP 0 , DGP 1 , DGP 2 , and DGP 3 . The dummy gate patterns DGP 0 , DGP 1 , DGP 2 , and DGP 3  may intersect the first and second active fins AF 1  and AF 2  to cover the top surfaces and upper sidewalls of the first and second active fins AF 1  and AF 2 . 
     Referring to  FIGS. 4A and 4B , upper portions of the first and second active fins AF 1  and AF 2  exposed between the dummy gate patterns DGP 0 , DGP 1 , DGP 2 , and DGP 3  may be removed to reduce heights of the top surfaces of the first and second active fins AF 1  and AF 2 . The first and second active fins AF 1  and AF 2  may thus have their top surfaces at heights similar to that of the top surface of the device isolation layer  3 . A selective epitaxial growth (SEG) process may be performed to form first and second source/drain patterns SD 1  and SD 2 , respectively, on the first and second active fins AF 1  and AF 2 . The first and second source/drain patterns SD 1  and SD 2  may have a pentagonal shape, but the present inventive concept is not limited thereto. The first and second source/drain patterns SD 1  and SD 2  may each include a semiconducting material selected from one of, for example, silicon (Si), germanium (Ge), silicon germanium (SiGe), silicon carbide (SiC), gallium arsenide (GaAs), etc. The first and second source/drain patterns SD 1  and SD 2  may be doped with impurities whose conductivity types are the same or different from each other. For example, the first and second source/drain patterns SD 1  and SD 2  may be doped with n-type impurities or p-type impurities during the SEG process, or may be separately doped with the n-type impurities or the p-type impurities through an ion implantation process. A first interlayer dielectric layer IL 1  may be formed on the substrate  1 , and a chemical mechanical polishing (CMP) process or an etch-back process may be performed to expose top surfaces of the dummy gate patterns DGP 0 , DGP 1 , DGP 2 , and DGP 3 . The first interlayer dielectric layer IL 1  may thus have a top surface coplanar with those of the dummy gate patterns DGP 0 , DGP 1 , DGP 2 , and DGP 3 . The dummy gate patterns DGP 0 , DGP 1 , DGP 2 , and DGP 3  may be classified into a zeroth dummy gate pattern DGP 0 , a first dummy gate pattern DGP 1 , a second dummy gate pattern DGP 2 , and a third dummy gate pattern DGP 3 . 
     Referring to  FIGS. 4A, 4B, 5A, and 5B , the dummy gate patterns DGP 0 , DGP 1 , DGP 2 , and DGP 3  may be removed to expose inner sidewalls of the spacers SC, the device isolation layer  3  between the exposed inner sidewalls of the spacers SC, and the top surfaces and the upper sidewalls of the active fins AF 1  and AF 2  between the exposed inner sidewalls of the spacers SC. A dielectric layer may be conformally formed on the substrate  1  such that the dielectric layer may cover the inner sidewalls of the spacers SC, the device isolation layer  3  between the exposed sidewalls of the spacers SC, and the top surfaces and the upper sidewalls of the active fins AF 1  and AF 2  between the exposed sidewalls of the spacers SC. A conductive layer may be formed to fill spaces between the spacers SC, and thereafter, an etch-back process may be performed on the conductive layer and the dielectric layer. Thus, a gate dielectric layer GO and a gate electrode MG may be formed between the spacers SC. A gate capping layer may be formed, and then an etch-back process may be performed to form a gate capping pattern CAP on the gate dielectric layer GO and the gate electrode MG. The materials used to form the gate capping pattern CAP, the gate dielectric layer GO and the gate electrode MG may be the same as those described above with reference to  FIGS. 1A through 1C . Therefore, the zeroth dummy gate pattern DGP 0  may be changed into a zeroth gate pattern GP 0 , and the third dummy gate pattern DGP 3  may be changed into a fifth gate pattern GP 5 . The first dummy gate pattern DGP 1  may be changed into a first preliminary gate pattern PGP 1 , and the second dummy gate pattern DGP 2  may be changed into a second preliminary gate pattern PGP 2 . The zeroth gate pattern GP 0 , the first preliminary gate pattern PGP 1 , the second preliminary gate pattern PGP 2 , and the fifth gate pattern GP 5  may have the same structure. 
     Referring to  FIGS. 5A, 5B, 6A, and 6B , a separation mask pattern SM may be formed on the first interlayer dielectric layer IL 1 . The separation mask pattern SM may be formed by a photolithography process. The separation mask pattern SM may include a separation mask opening SMO. The separation mask opening SMO may be positioned coincident with the separation mask opening region SMR. 
     The separation mask opening SMO may be formed to run across the first and second preliminary gate patterns PGP 1  and PGP 2 . The separation mask opening SMO may expose the first and second preliminary gate patterns PGP 1  and PGP 2  on the first and second separation regions SR 1  and SR 2 , and also expose a portion of the first interlayer dielectric layer IL 1  on sides of the first and second preliminary gate patterns PGP 1  and PGP 2 . The separation mask pattern SM may cover the zeroth and fifth gate patterns GP 0  and GP 5 . 
     An etching process, such as isotropic/anisotropic etching, may be performed to remove the first and second preliminary gate patterns PGP 1  and PGP 2  that are exposed to the separation mask opening SMO. In this case, the first interlayer dielectric layer IL 1  may also be partially etched. Since the zeroth and fifth gate patterns GP 0  and GP 5  are covered by the separation mask pattern SM, they may not be etched during the etching process. A separation trench ST may therefore be formed to expose the device isolation layer  3  on the first and second separation regions SR 1  and SR 2 . The first interlayer dielectric layer IL 1  may partially remain on the first and second overlapping regions OR 1  and OR 2  and the middle region MR. For example, portions of the first and second preliminary gate patterns PGP 1  and PGP 2  on the first and second separation regions SR 1  and SR 2  may be completely removed. Due to etch rate difference, the first interlayer dielectric layer IL 1  on the first and second overlapping regions OR 1  and OR 2  and the middle region MR may not be completely etched. A bottom surface of the separation trench ST may have an uneven structure. The separation trench ST may cause the zeroth and fifth gate patterns GP 0  and GP 5  to have their sidewalls that are not exposed but covered with a portion of the first interlayer dielectric layer IL 1 . The portion of the first interlayer dielectric layer IL 1  covering the sidewalls of the zeroth and fifth gate patterns GP 0  and GP 5  may be positioned at an area not exposed by the separation mask opening SMO, and thus may not be etched during the formation of the separation trench ST. 
     Because the first and second preliminary gate patterns PGP 1  and PGP 2  are removed from the first and second separation regions SR 1  and SR 2 , the first preliminary gate pattern PGP 1  may be divided into first and second gate patterns GP 1  and GP 2  that are spaced apart from each other in the second direction y, and the second preliminary gate pattern PGP 2  may be divided into third and fourth gate patterns GP 3  and GP 4  that are spaced apart from each other in the second direction y. The separation mask pattern SM may be removed to expose the first interlayer dielectric layer IL 1 . For example, a gate-cutting process may be applied here to separate the first preliminary gate pattern PGP 1  into the first and second gate patterns GP 1  and GP 2 , and to separate the second preliminary gate pattern PGP 2  into the third and fourth gate patterns GP 3  and GP 4 . 
     In consideration of process margin due to misalignment, the separation mask opening SMO may be formed not only on the first and second separation regions SR 1  and SR 2 , but also on the first and second overlapping regions OR 1  and OR 2  and the middle region MR. Even though misalignment is slightly produced, the first and second preliminary gate patterns PGP 1  and PGP 2  may be exposed on the first and second separation regions SR 1  and SR 2  of the substrate  1 . For example, the first and second preliminary gate patterns PGP 1  and PGP 2  may be completely removed to reach the device isolation layer  3  in the separation trench ST. Accordingly, the first and second gate patterns GP 1  and GP 2  may be completely separated by the separation trench ST on the first separation region SR 1 . Also, the third and fourth gate patterns GP 3  and GP 4  may be completely separated by the separation trench ST on the second separation region SR 2 . As a result, it may be possible to prevent gate-bridge where the first and second gate patterns GP 1  and GP 2  are partially connected to each other or the third and fourth gate patterns GP 3  and GP 4  are partially connected to each other. 
     Referring to  FIGS. 7A and 7B , a dielectric layer may be formed on the substrate  1  to fill the separation trench ST, and then an etch-back process may be performed to form a separation pattern SP in the separation trench ST and simultaneously to expose the top surface of the first interlayer dielectric layer IL 1 . Thus, the separation pattern SP may have a top surface coplanar with that of the first interlayer dielectric layer IL 1 . A bottom surface of the separation pattern SP may have an uneven structure, and may be in contact with the device isolation layer  3  on the first and second separation regions SR 1  and SR 2  of the substrate  1 . The separation pattern SP may be formed of a material, such as silicon nitride (Si 3 N 4 ), having an etch selectivity with respect to a material of the first interlayer dielectric layer IL 1 . 
     Referring to  FIGS. 8A and 8B , a second interlayer dielectric layer IL 2  may be formed on the substrate  1  on which the separation pattern SP is formed. The second interlayer dielectric layer IL 2  may include a material, such as silicon oxide (SiO 2 ), having an etch selectivity with respect to a material of the separation pattern SP. A mask pattern may be separately formed on the second interlayer dielectric layer IL 2 , and the mask pattern may be used to etch the second interlayer dielectric layer IL 2 . At least a portion of the separation pattern SP may be removed from the first and second overlapping regions OR 1  and OR 2 , and thus first and second recesses RC 1  and RC 2  may be formed on the separation pattern SP. The separation pattern SP may partially remain on bottom surfaces of the first and second recesses RC 1  and RC 2 . A buried dielectric layer may be formed to fill the first and second recesses RC 1  and RC 2 , and then an etch-back process may be performed to expose a top surface of the second interlayer dielectric layer IL 2  and simultaneously to form buried dielectric patterns FL in the first and second recesses RC 1  and RC 2 . The buried dielectric patterns FL may be formed of a material, such as silicon oxide (SiO 2 ), the same as or similar to that of the first interlayer dielectric layer IL 1 . 
     A mask pattern may be separately formed on the second interlayer dielectric layer IL 2  and the buried dielectric patterns FL, and the mask pattern may be used to etch the buried dielectric patterns FL and the first interlayer dielectric layer IL 1 . Subsequently, referring to  FIGS. 1A and 1B , on the first and second overlapping regions OR 1  and OR 2 , the buried dielectric patterns FL and the first interlayer dielectric layer IL 1  may be etched to form contact holes CH. In this case, upper portions of the source/drain patterns SD 1  and SD 2  may also be removed. A conductive layer may be formed on an entire surface of the substrate  1  so as to fill the contact holes CH, and then an etch-back process or a chemical mechanical polishing (CMP) process may be performed to form contact plugs CT 1  and CT 2 . A semiconductor device may thus be fabricated as shown in  FIGS. 1A and 1B . 
     In a method of fabricating a semiconductor device according to an example embodiment of the present inventive concept, at least a portion of the separation pattern SP may be previously removed to form the recesses RC 1  and RC 2  on the overlapping regions OR 1  and OR 2 , and the recesses RC 1  and RC 2  may be filled with the buried dielectric patterns FL including a material identical or similar to that of the first interlayer dielectric layer IL 1 , which may solve issues associated with etching difficulty in forming the contact holes CH. 
     When at least a portion of the separation pattern SP is not previously removed from the overlapping regions OR 1  and OR 2 , the separation pattern SP may be present on the overlapping regions OR 1  and OR 2  when the contact holes CH are formed, with the result that the contact plugs CT 1  and CT 2  may each be disconnected. In this case, each of the contact plugs CT 1  and CT 2  may not connect the first and second source/drain patterns SD 1  and SD 2 , which may result in the occurrence of process defects such as contact-connection failure. In contrast, according to the present inventive concept, because at least a portion of the separation pattern SP is previously removed from the overlapping regions OR 1  and OR 2 , it may be possible to avoid the problems mentioned above and to increase yield. However, if the portion of the separation pattern SP removed from the overlapping regions OR 1  and OR 2  is too small, each of the contact plugs CT 1  and CT 2  may not connect or may weakly connect the first and second source/drain patterns SD 1  and SD 2 . It is desirable to have sufficient amount of the separation pattern SP removed from the overlapping regions OR 1  and OR 2  to increase yield. For example, in an example embodiment of the present inventive concept, the separation pattern SP may be removed from the first and second overlapping regions OR 1  and OR 2  to an extent that at least the lowermost portions of the first and second recesses RC 1  and RC 2  are lower than the uppermost portions of the first and second source/drain patterns SD 1  and SD 2 . Thus, even some portion of the separation pattern SP may be present on the first and second overlapping regions OR 1  and OR 2 , the first and second contact plugs CT 1  and CT 2  formed in the contact holes CH which include upper portions of the source/drain patterns SD 1  and SD 2  removed may each be connected to the first and second source/drain patterns SD 1  and SD 2 . Accordingly, the contact-connection failure on the overlapping regions OR 1  and OR 2  may be prevented, and reliability of the semiconductor device may increase. 
       FIG. 9A  illustrates a plan view showing a semiconductor device according to an example embodiment of the present inventive concept.  FIG. 9B  illustrates a cross-sectional view taken along lines A-A′, B-B′, and C-C′ of  FIG. 9A , according to an example embodiment of the present inventive concept. 
     Referring to  FIGS. 9A and 9B , a semiconductor device according to the present example embodiment may be configured such that the separation pattern SP may not include the first protrusion segment P 1  and the third protrusion segment P 3  that are shown in  FIGS. 1A and 1B . For example, in the process of forming the first and second recesses RC 1  and RC 2 , the separation pattern SP may not remain on the bottom surfaces of the first and second recesses RC 1  and RC 2 , or in the process of forming the contact holes CH, the first protrusion segment P 1  and the third protrusion segment P 3  may be removed. The separation pattern SP may include the first separation segment S 1 , the second separation segment S 2 , and the second protrusion segment P 2  that connects the first and second separation segments S 1  and S 2 . The first and second separation segments S 1  and S 2  may have their bottom surfaces in direct contact with the device isolation layer  3 . Thus, no gate-bridges may be formed on the separation regions SR 1  and SR 2 . The contact plugs CT 1  and CT 2  may have their bottom surfaces in direct contact with the first interlayer dielectric layer IL 1 . The separation pattern SP may be absent on the overlapping regions OR 1  and OR 2  of the substrate  1 . As shown in the cross-sectional view taken along line C-C′ of  FIG. 9B , the bottom surface of the first contact plug CT 1  may have an uneven structure. For example, a portion of the first contact plug CT 1  may protrude downwardly between the first and second source/drain patterns SD 1  and SD 2 . The bottom surface of the second contact plug CT 2  may also have an uneven structure. A lowermost end of the bottom surface of the first contact plug CT 1  may have a height H 2  the same as a height H 1  of a bottom surface of the second protrusion segment P 2 , in which heights H 1  and H 2  are measured in the third direction z from the top surface of the substrate  1 . Other configurations may be identical or similar to those discussed with reference to  FIGS. 1A to 1C . 
     The semiconductor device of  FIGS. 9A and 9B  may be fabricated by completely removing the separation pattern SP from the overlapping regions OR 1  and OR 2  when the separation pattern SP is etched as illustrated in  FIGS. 8A and 8B , and then performing subsequent processes. Moreover, the contact hole CH may be formed to have a bottom surface that is crooked due to a difference in etch rate between the first interlayer dielectric layer IL 1  and the source/drain patterns SD 1  and SD 2 . Therefore, the first contact plug CT 1  may be altered in shape. With the altered shape, the first contact plug CT 1  may have larger contact area with the source/drain patterns SD 1  and SD 2 , and thus may be less likely to have contact-connection failure. Other process steps may be identical or similar to those discussed above. 
       FIG. 10  illustrates a cross-sectional view taken along lines A-A′, B-B′, and C-C′ of  FIG. 9A , according to an example embodiment of the present inventive concept. 
     Referring to  FIGS. 9A and 10 , a semiconductor device according to the present example embodiment may not include the first protrusion segment P 1  and the third protrusion segment P 3  that are shown in  FIGS. 1A and 1B . The buried dielectric patterns FL may remain below the contact plugs CT 1  and CT 2  on the overlapping regions OR 1  and OR 2 . The buried dielectric patterns FL may be in direct contact with bottom surfaces of the contact plugs CT 1  and CT 2 . Other configurations may be identical or similar to those discussed with reference to  FIGS. 1A to 1C . 
     The semiconductor device of  FIG. 10  may be fabricated by completely removing the separation pattern SP from the overlapping regions OR 1  and OR 2  when the separation pattern SP is etched as shown in  FIGS. 8A and 8B , partially leaving the buried dielectric pattern FL on a bottom surface of the contact hole CH when the contact hole CH is formed, and then performing subsequent processes. Other process steps may be identical or similar to those discussed above. With the processes described above, the first interlayer dielectric layer IL 1  may be disposed between the first contact plug CT 1  and the device isolation layer  3  over the substrate  1 , between the second contact plug CT 2  and the device isolation layer  3  over the substrate  1 , and between the second protrusion segment P 2  and the device isolation layer  3  over the substrate  1 . A different interlayer dielectric layer may be formed to replace the first interlayer dielectric layer IL 1  in these areas. In an example embodiment of the present inventive concept, the second protrusion segment P 2  may be adjacent to one sidewall of the first gate pattern GP 1 , the first contact plug CT 1  may be adjacent to another sidewall of the first gate pattern GP 1  and spaced apart from the second protrusion segment P 2 , a third interlayer dielectric layer may be disposed between the second protrusion segment P 2  and the substrate  1  and between the first contact plug CT 1  and the substrate  1 , and the buried dielectric pattern FL may be disposed between the first contact plug CT 1  and the third interlayer dielectric layer, in which the bottom surface of the buried dielectric pattern FL may be at a height the same as a height of a bottom surface of the second protrusion segment P 2 . The third interlayer dielectric layer may be replaced with the first interlayer dielectric layer IL 1 , or may contain a material different from that of the first interlayer dielectric layer IL 1 . 
     The following will describe a method of fabricating the semiconductor device of  FIG. 9B  or  FIG. 10 . 
       FIGS. 11A to 11E  illustrate cross-sectional views showing a method of fabricating the semiconductor device of  FIG. 9B  or  FIG. 10 . 
     Referring to  FIG. 11A , a sacrificial layer  20  may be formed on the entire surface of the substrate  1  in the state of  FIG. 6B , with the result that the sacrificial layer  20  may fill the separation trench ST. The sacrificial layer  20  may be, for example, a spin-on-hardmask (SOH) layer or a spin-on-carbon (SOC) layer. A first mask pattern  22  may be formed on the sacrificial layer  20 , and may have openings  22   o  that overlap the overlapping regions OR 1  and OR 2 . 
     Referring to  FIG. 11B , the first mask pattern  22  may be used as an etching mask to etch the sacrificial layer  20 , such that the sacrificial layer  20  may be removed from the overlapping regions OR 1  and OR 2  and a sacrificial pattern  20   a  may be formed. In the separation trench ST, the sacrificial pattern  20   a  may be positioned on the separation regions SR 1  and SR 2  and the middle region MR. 
     Referring to  FIGS. 11B and 11C , a buried dielectric layer may be formed on the entire surface of the substrate  1 , and thus the buried dielectric layer may fill an area where the sacrificial pattern  20   a  is absent in the separation trench ST. A chemical mechanical polishing (CMP) process or an etch-back process may be performed such that the sacrificial pattern  20   a , the first mask pattern  22 , and the buried dielectric layer located above the separation mask pattern SM may be removed. In this case, a reduced sacrificial pattern  20   a  may remain in the separation trench ST, and the buried dielectric patterns FL may be formed in the separation trench ST. In the separation trench ST, the buried dielectric patterns FL may be disposed on the overlapping regions OR 1  and OR 2 , and the sacrificial pattern  20   a  may be disposed on the separation regions SR 1  and SR 2  and the middle region MR. 
     Referring to  FIGS. 11C and 11D , the sacrificial pattern  20   a  may be removed from the separation trench ST. For example, the sacrificial pattern  20   a  may contain a spin-on-hardmask (SOH) layer or a spin-on-carbon (SOC) layer, and may be easily removed through an oxygen etch or any other suitable etching process. Therefore, the device isolation layer  3  may be exposed on the separation regions SR 1  and SR 2 , and the first interlayer dielectric layer IL 1  may be exposed on the middle region MR. A second trench ST 2  may be defined to indicate an area where the sacrificial pattern  20   a  is removed. 
     Referring to  FIGS. 11D and 11E , a dielectric layer may be formed on the substrate  1  to fill the second separation trench ST 2 , and then an etch-back process may be performed to form the separation pattern SP in the second separation trench ST 2 . 
     The separation mask pattern SM may become the second dielectric layer (see IL 2  of  FIG. 8B ). Subsequently, referring to  FIG. 9B , the buried dielectric patterns FL and the first interlayer dielectric layer IL 1  may be etched to form the contact holes CH, and the contact holes CH may be filled with a conductive layer to form the contact plugs CT 1  and CT 2 . The semiconductor device of  FIG. 9B  may be eventually fabricated. When the buried dielectric patterns FL are partially left during the formation of the contact holes CH and then subsequent processes are performed, the semiconductor device of  FIG. 10  may be fabricated. Other process steps may be identical or similar to those discussed above. The process described above with reference to  FIGS. 11A to 11E  may be provided as an alternative way of fabricating the semiconductor device of  FIG. 9B  or  FIG. 10  by using the large etch difference between the carbon rich spin-on-hardmask (SOH) material (or spin-on-carbon (SOC) material) for the sacrificial pattern  20   a  and the silicon containing silicon oxide (SiO 2 ) material for the buried dielectric pattern FL. 
       FIG. 12A  illustrates a plan view showing a semiconductor device according to an example embodiment of the present inventive concept.  FIG. 12B  illustrates a cross-sectional view taken along lines A-A′, B-B′, and C-C′ of  FIG. 12A , according to an example embodiment of the present inventive concept. 
     Referring to  FIGS. 12A and 12B , a semiconductor device according to the present example embodiment may be configured such that the substrate  1  may include a third contact region CR 3  disposed between and spaced apart from the first and second contact regions CR 1  and CR 2 . The separation mask opening region SMR may intersect all of the first, second, and third contact regions CR 1 , CR 2 , and CR 3 . The separation mask opening region SMR may thus include a third overlapping region OR 3  in addition to the first and second overlapping regions OR 1  and OR 2 . The third overlapping region OR 3  may be positioned between the first overlapping region OR 1  and the second overlapping region OR 2 . The first separation region SR 1  may be positioned between the first overlapping region OR 1  and the third overlapping region OR 3 . The second separation region SR 2  may be positioned between the second overlapping region OR 2  and the third overlapping region OR 3 . The third overlapping region OR 3  may be positioned at the middle region MR of  FIG. 1B . For example, the middle region MR of  FIG. 1B  may be replaced with the third overlapping region OR 3  in  FIG. 12B . 
     The separation pattern SP may include the first, second, and third protrusion segments P 1 , P 2 , and P 3 , and may also include the first and second separation segments S 1  and S 2  between the first, second, and third protrusion segments P 1 , P 2 , and P 3 . The first, second, and third protrusion segments P 1 , P 2 , and P 3  may have the same thickness and height. For example, the second protrusion segment P 2  may laterally extend from the first separation segment S 1  in a direction away from the first protrusion segment P 1 , a top surface of the second protrusion segment P 2  may be coplanar with a top surface of the first protrusion segment P 1 , and a bottom surface of the second protrusion segment P 2  may be higher than a bottom surface of the first separation segment S 1 . For example, the third protrusion segment P 3  may extend from the second separation segment S 2  in a direction away from the second protrusion segment P 2 , and the third protrusion segment P 3  may have a thickness the same as a thickness of the first protrusion segment P 1 . The first, second, and third protrusion segments P 1 , P 2 , and P 3  may be thinner than the first and second separation segments S 1  and S 2 . The semiconductor device may further include a third contact plug CT 3  between the first and second separation segments S 1  and S 2 . The first, second, and third protrusion segments P 1 , P 2 , and P 3  may be in contact with bottom surfaces of the first, third, and second contact plugs CT 1 , CT 3 , and CT 2 , respectively. Other configurations may be identical or similar to those discussed with reference to  FIGS. 1A to 1C . 
     The fabrication of the semiconductor device shown in  FIGS. 12A and 12B  may include forming a third recess by etching the separation pattern SP on the middle region MR when the first and second recesses RC 1  and RC 2  are formed as illustrated in  FIG. 8B , performing subsequent processes, and forming the third contact plug CT 3  on the middle region MR of  FIG. 1B . For example, the third contact plug CT 3  may be formed on the third overlapping region OR 3  of  FIG. 12B . Accordingly, similar to  FIGS. 1A and 1B , no gate-bridges may be formed between the first and second gate patterns GP 1  and GP 2  on the first separation region SR 1 , and between the third and fourth gate patterns GP 3  and GP 4  on the second separation region SR 2 . Respectively on the first, second and third overlapping regions OR 1 , OR 2  and OR 3 , the first, second and third contact plugs CT 1 , CT 2  and CT 3  may each be connected without failure to the first and second source/drain patterns SD 1  and SD 2 . For example, the first, second and third contact plugs CT 1 , CT 2  and CT 3  formed on the first, second, and third contact regions CR 1 , CR 2 , and CR 3 , with each of the first, second and third contact plugs CT 1 , CT 2  and CT 3  connecting the first source/drain pattern SD 1  and second source/drain pattern SD 2 , may not have connection failure on the first, second and third overlapping regions OR 1 , OR 2  and OR 3 , respectively. 
       FIG. 13A  illustrates a plan view showing a semiconductor device according to an example embodiment of the present inventive concept.  FIG. 13B  illustrates a cross-sectional view taken along lines A-A′, B-B′, and C-C′ of  FIG. 13A , according to an example embodiment of the present inventive concept. 
     Referring to  FIGS. 13A and 13B , a semiconductor device according to the present example embodiment may be configured such that the separation pattern SP may include a first separation pattern SP 1  and a second separation pattern SP 2  that are spaced apart from each other. The first separation pattern SP 1  may be disposed on the first separation region SR 1  and interposed between the first gate pattern GP 1  and the second gate pattern GP 2 . The second separation pattern SP 2  may be disposed on the second separation region SR 2  and interposed between the third gate pattern GP 3  and the fourth gate pattern GP 4 . The first, second, and third protrusion segments P 1 , P 2 , and P 3  of  FIG. 12B  may be absent on the first, second, and third overlapping regions OR 1 , OR 2 , and OR 3 . Other configurations may be identical or similar to those discussed with reference to  FIGS. 12A and 12B . 
     The fabrication of the semiconductor device shown in  FIGS. 13A and 13B  may be analogous to that of the semiconductor device shown in  FIGS. 12A and 12B . For example, the fabrication of the semiconductor device shown in  FIGS. 13A and 13B  may include, when the first and second recesses RC 1  and RC 2  are formed as illustrated in  FIG. 8B , forming the third recess together with the first and second recesses RC 1  and RC 2  by completely removing the separation pattern SP from the first, second, and third overlapping regions OR 1 , OR 2 , and OR 3  to leave none of the first, second, and third protrusion segments P 1 , P 2 , and P 3 , and then performing subsequent processes. Accordingly, similar to  FIGS. 12A and 12B , no gate-bridges may be formed between the first and second gate patterns GP 1  and GP 2  on the first separation region SR 1 , and between the third and fourth gate patterns GP 3  and GP 4  on the second separation region SR 2 . Respectively on the first, second and third overlapping regions OR 1 , OR 2  and OR 3 , the first, second and third contact plugs CT 1 , CT 2  and CT 3  may each be connected without failure to the first and second source/drain patterns SD 1  and SD 2 . 
       FIG. 14  illustrates a cross-sectional view taken along lines A-A′, B-B′, and C-C′ of  FIG. 13A , according to an example embodiment of the present inventive concept. 
     Referring to  FIGS. 13A and 14 , a semiconductor device according to the present example embodiment may further include buried dielectric patterns FL in contact with corresponding bottom surfaces of the first, second, and third contact plugs CT 1 , CT 2 , and CT 3 . Other configurations may be identical or similar to those discussed with reference to  FIG. 13B . For example, the separation pattern SP may include a first separation pattern SP 1  and a second separation pattern SP 2  that are spaced apart from each other, and the first, second, and third protrusion segments P 1 , P 2 , and P 3  may be absent on the first, second, and third overlapping regions OR 1 , OR 2 , and OR 3 . The fabrication of the semiconductor device shown in  FIG. 14  may be analogous to that of the semiconductor device shown in  FIG. 10 . Accordingly, similar to  FIGS. 13A and 13B , no gate-bridges may be formed between the first and second gate patterns GP 1  and GP 2  on the first separation region SR 1 , and between the third and fourth gate patterns GP 3  and GP 4  on the second separation region SR 2 . Respectively on the first, second and third overlapping regions OR 1 , OR 2  and OR 3 , the first, second and third contact plugs CT 1 , CT 2  and CT 3  may each be connected without failure to the first and second source/drain patterns SD 1  and SD 2 . 
       FIG. 15A  illustrates a plan view showing a semiconductor device according to an example embodiment of the present inventive concept.  FIG. 15B  illustrates a cross-sectional view taken along lines A-A′, B-B′, and C-C′ of  FIG. 15A , according to an example embodiment of the present inventive concept. 
     Referring to  FIGS. 15A and 15B , a semiconductor device according to the present example embodiment may be configured such that the substrate  1  may not include the second contact region CR 2  of  FIGS. 12A and 12B . In addition, the semiconductor device may not include the second contact plug CT 2  of  FIGS. 12A and 12B . The second overlapping region OR 2  of  FIGS. 12A and 12B  may be renamed as an edge region ER in  FIGS. 15A and 15B . The separation pattern SP may include the third protrusion segment P 3  on the edge region ER, and the third protrusion segment P 3  may have a top surface coplanar with those of the first and second separation segments S 1  and S 2 . The third protrusion segment P 3  may be thicker than the first and second protrusion segments P 1  and P 2 . Other configurations may be identical or similar to those discussed with reference to  FIGS. 12A and 12B . Accordingly, similar to  FIGS. 12A and 12B , no gate-bridges may be formed between the first and second gate patterns GP 1  and GP 2  on the first separation region SR 1 , and between the third and fourth gate patterns GP 3  and GP 4  on the second separation region SR 2 . Respectively on the first and third overlapping regions OR 1  and OR 3 , the first and third contact plugs CT 1  and CT 3  may each be connected without failure to the first and second source/drain patterns SD 1  and SD 2 . 
       FIG. 16A  illustrates a plan view showing a semiconductor device according to an example embodiment of the present inventive concept.  FIG. 16B  illustrates a cross-sectional view taken along lines A-A′, B-B′, and C-C′ of  FIG. 16A , according to an example embodiment of the present inventive concept. 
     Referring to  FIGS. 16A and 16B , a semiconductor device according to the present example embodiment may be configured such that the separation pattern SP may include the first separation pattern SP 1  and the second separation pattern SP 2  that are spaced apart from each other. The first separation pattern SP 1  may be disposed on the first separation region SR 1  and interposed between the first gate pattern GP 1  and the second gate pattern GP 2 . The second separation pattern SP 2  may include the second separation segment S 2  disposed on the second separation region SR 2 , and also include the third protrusion segment P 3  disposed on the edge region ER and connected to the second separation segment S 2 . The first and third contact plugs CT 1  and CT 3  may have their bottom surfaces in direct contact with the first interlayer dielectric layer IL 1 . The separation pattern SP may not include the first protrusion segment P 1  and the second protrusion segment P 2  that are shown in  FIGS. 15A and 15B . Other configurations may be identical or similar to those discussed with reference to  FIGS. 15A and 15B . Accordingly, similar to  FIGS. 15A and 15B , no gate-bridges may be formed between the first and second gate patterns GP 1  and GP 2  on the first separation region SR 1 , and between the third and fourth gate patterns GP 3  and GP 4  on the second separation region SR 2 . Respectively on the first and third overlapping regions OR 1  and OR 3 , the first and third contact plugs CT 1  and CT 3  may each be connected without failure to the first and second source/drain patterns SD 1  and SD 2 . 
       FIG. 17  illustrates a cross-sectional view taken along lines A-A′, B-B′, and C-C′ of  FIG. 16A , according to an example embodiment of the present inventive concept. 
     Referring to  FIG. 17 , the first and third contact plugs CT 1  and CT 3  may have their bottom surfaces in direct contact with the buried dielectric patterns FL. The buried dielectric patterns FL on the first and third overlapping regions OR 1  and OR 3  may have their bottom surfaces at a height the same as that of a bottom surface of the third protrusion segment P 3  of the second separation pattern SP 2  on the edge region ER. Other configurations may be identical or similar to those discussed with reference to  FIG. 16B . Accordingly, similar to  FIGS. 16A and 16B , no gate-bridges may be formed between the first and second gate patterns GP 1  and GP 2  on the first separation region SR 1 , and between the third and fourth gate patterns GP 3  and GP 4  on the second separation region SR 2 . Respectively on the first and third overlapping regions OR 1  and OR 3 , the first and third contact plugs CT 1  and CT 3  may each be connected without failure to the first and second source/drain patterns SD 1  and SD 2 . 
       FIG. 18A  illustrates a plan view showing a semiconductor device according to an example embodiment of the present inventive concept.  FIG. 18B  illustrates a cross-sectional view taken along lines A-A′, B-B′, and C-C′ of  FIG. 18A , according to an example embodiment of the present inventive concept. 
     Referring to  FIGS. 18A and 18B , a semiconductor device according to the present example embodiment may be configured such that the substrate  1  may not include the third contact region CR 3  of  FIGS. 15A and 15B . In addition, the semiconductor device may not include the third contact plug CT 3  of  FIGS. 15A and 15B . The third overlapping region OR 3  of  FIGS. 15A and 15B  may be renamed back as a middle region MR in  FIGS. 18A and 18B . The separation pattern SP may include the second protrusion segment P 2  and the third protrusion segment P 3  respectively on the middle region MR and the edge region ER, and the second and third protrusion segments P 2  and P 3  may have their top surfaces coplanar with those of the first and second separation segments S 1  and S 2 . The second and third protrusion segments P 2  and P 3  may be thicker than the first protrusion segment P 1 . Other configurations may be identical or similar to those discussed with reference to  FIGS. 15A and 15B . Accordingly, similar to  FIGS. 15A and 15B , no gate-bridges may be formed between the first and second gate patterns GP 1  and GP 2  on the first separation region SR 1 , and between the third and fourth gate patterns GP 3  and GP 4  on the second separation region SR 2 . On the first overlapping region OR 1 , the first contact plug CT 1  may be connected without failure to the first and second source/drain patterns SD 1  and SD 2 . 
       FIG. 19A  illustrates a plan view showing a semiconductor device according to an example embodiment of the present inventive concept.  FIG. 19B  illustrates a cross-sectional view taken along lines A-A′, B-B′, and C-C′ of  FIG. 19A , according to an example embodiment of the present inventive concept. 
     Referring to  FIGS. 19A and 19B , a semiconductor device according to the present example embodiment may be configured such that the separation pattern SP may not include the first protrusion segment P 1  of  FIGS. 18A and 18B . The first contact plug CT 1  may have a bottom surface at a height the same as that of bottom surfaces of the second and third protrusion segments P 2  and P 3 . Other configurations may be identical or similar to those discussed with reference to  FIGS. 18A and 18B . Accordingly, similar to  FIGS. 18A and 18B , no gate-bridges may be formed between the first and second gate patterns GP 1  and GP 2  on the first separation region SR 1 , and between the third and fourth gate patterns GP 3  and GP 4  on the second separation region SR 2 . On the first overlapping region OR 1 , the first contact plug CT 1  may be connected without failure to the first and second source/drain patterns SD 1  and SD 2 . 
       FIG. 20  illustrates a cross-sectional view taken along lines A-A′, B-B′, and C-C′ of  FIG. 9A , according to an example embodiment of the present inventive concept. 
     Referring to  FIG. 20 , a residual sacrificial pattern  20   r  may be interposed between the separation pattern SP and the device isolation layer  3  of  FIG. 9B . For example, the residual sacrificial pattern  20   r  may be interposed between the device isolation layer  3  and the first separation segment S 1  of the separation pattern SP and between the device isolation layer  3  and the second separation segment S 2  of the separation pattern SP. The residual sacrificial pattern  20   r  may include a material different from that of the separation pattern SP. The residual sacrificial pattern  20   r  may include a material having an etch selectivity with respect to the separation pattern SP. The residual sacrificial pattern  20   r  may include, for example, a spin-on-hardmask (SOH) layer or a spin-on-carbon (SOC) layer. Thus, the residual sacrificial pattern  20   r  (or the sacrificial pattern  20   a ) may include a material having an etch selectivity with respect to a material of the first interlayer dielectric layer IL 1 . 
     The residual sacrificial pattern  20   r  may be called a subsidiary separation pattern. For example, the residual sacrificial pattern  20   r  may assist in dividing the gate patterns GP 1 , GP 2 , GP 3 , and GP 4 . Alternatively, the residual sacrificial pattern  20   r  and the separation pattern SP may be integrally connected to form a separation pattern as a whole. In this case, the residual sacrificial pattern  20   r  may be called a first separation pattern, and the separation pattern SP may be called a second separation pattern. Other configurations may be identical or similar to those discussed with reference to  FIG. 9B . Accordingly, similar to  FIGS. 9A and 9B , no gate-bridges may be formed between the first and second gate patterns GP 1  and GP 2  on the first separation region SR 1 , and between the third and fourth gate patterns GP 3  and GP 4  on the second separation region SR 2 . Respectively on the first and second overlapping regions OR 1  and OR 2 , the first and second contact plugs CT 1  and CT 2  may each be connected without failure to the first and second source/drain patterns SD 1  and SD 2 . 
     The fabrication of the semiconductor device of  FIG. 20  may include, when the sacrificial pattern  20   a  is removed in the step of  FIGS. 11C and 11D , leaving a portion of the sacrificial pattern  20   a  to form the residual sacrificial pattern  20   r , and performing subsequent processes. Other process steps may be identical or similar to those discussed with reference to  FIGS. 11A to 11E . 
     The residual sacrificial pattern  20   r  may be interposed between the separation pattern SP and the device isolation layer  3  in the examples shown in  FIGS. 13B, 16B, and 19B . 
     According to the present inventive concept, a semiconductor device may increase in reliability. 
     In a method of fabricating a semiconductor device according to the present inventive concept, at least a portion of a separation pattern may be previously removed from an overlapping region and a buried dielectric pattern is formed of a material similar to that of interlayer dielectric layers, and therefore, it may be possible to prevent process defects such as contact-connection failure. As a result, a yield may increase. 
     Although the present inventive concept has been described in connection with some specific example embodiments of the present inventive concept illustrated in the accompanying drawings, it will be understood by those skilled in the art that various changes and modifications may be made to the example embodiments without departing from the spirit and scope of the present inventive concept as defined in the appended claims.