Patent Publication Number: US-2023163214-A1

Title: Integrated circuits and methods of manufacturing the same

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This is a continuation of U.S. patent application Ser. No. 17/320,617 filed May 14, 2021, which is a continuation of U.S. patent application Ser. No. 16/747,870 filed Jan. 21, 2020, now U.S. Pat. No. 11,024,741 issued on Jun. 1, 2021, both of which are hereby incorporated by reference in their entirety. 
     This application claims priority under 35 U.S.C. § 119 to Korean Patent Application No. 10-2019-0071768 filed on Jun. 17, 2019 in the Korean Intellectual Property Office, the disclosure of which is hereby incorporated by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     Example embodiments of the present disclosure relate to integrated circuits and methods of manufacturing the same, and more specifically, to integrated circuits including multi-gate structure transistors and methods of manufacturing the same. 
     DISCUSSION OF RELATED ART 
     Due to development of electronic techniques integrated circuits are highly integrated and are down-scaled. As the integrated circuits are down-scaled, reliability of the integrated circuits are lowered by occurrence of a short channel effect. To reduce the short channel effect, multi-gate integrated circuits such as nanosheet transistors have been proposed. 
     SUMMARY 
     According to example embodiments, an integrated circuit may include a substrate, a fin active region protruding from the substrate and extending in a first direction, a plurality of semiconductor patterns on an upper surface of the fin active region, a gate electrode surrounding the plurality of semiconductor patterns and extending in a second direction perpendicular to the first direction, the gate electrode including a main gate part and a plurality of sub gate parts, the main gate part disposed on an uppermost one of the plurality of semiconductor patterns, each of the plurality of sub gate parts between two corresponding patterns among the plurality of semiconductor patterns, a spacer structure on a sidewall of the main gate part, and a source/drain region disposed at a side of the gate electrode and connected to the plurality of semiconductor patterns, the source/drain region contacting a bottom surface of the spacer structure. A top portion of the uppermost semiconductor pattern may have a first width in the first direction. A bottom portion of the uppermost semiconductor pattern may have a second width smaller than the first width in the first direction. The main gate part may include a bottom portion having a sloped sidewall. 
     According to example embodiments, an integrated circuit may include a substrate, a fin active region protruding from the substrate and extending in a first direction, a plurality of semiconductor patterns on an upper surface of the fin active region, a gate electrode surrounding the plurality of semiconductor patterns and extending in a second direction perpendicular to the first direction, the gate electrode including a main gate part and a plurality of sub gate parts, the main gate part disposed on an uppermost one of the plurality of semiconductor patterns, each of the plurality of sub gate parts disposed between two corresponding patterns among the plurality of semiconductor patterns, a spacer structure on a sidewall of the main gate part, and a source/drain region disposed at a side of the gate electrode and connected to the plurality of semiconductor patterns, the source/drain region contacting a bottom surface of the spacer structure. A top portion of the uppermost semiconductor pattern may have a first width in the first direction. A bottom portion of the uppermost semiconductor pattern may have a second width smaller than the first width in the first direction. A bottom portion of the main gate part may have a third width in the first direction. An intermediate portion of the main gate part may have a fourth width different from the third width in first direction. 
     According to example embodiments, an integrated circuit may include a substrate, a fin active region protruding from the substrate, a plurality of semiconductor patterns on an upper surface of the fin active region, each of the plurality of semiconductor patterns including a channel region, a gate electrode surrounding the plurality of semiconductor patterns and including a main gate part and a plurality of sub gate parts, the main gate part disposed on an uppermost one of the plurality of semiconductor patterns, each of the plurality of sub gate parts disposed between two corresponding patterns among the plurality of semiconductor patterns, a spacer structure on a sidewall of the main gate part, and a source/drain region at a side of the gate electrode and connected to the plurality of semiconductor patterns, the source/drain region contacting a bottom surface of the spacer structure. A bottom portion of the uppermost semiconductor pattern may be wider than a top portion of the uppermost semiconductor pattern. At least a portion of the main gate part may be sloped. The sidewall of the main gate part may be at least partially vertically overlapped with the spacer structure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a layout view illustrating an integrated circuit according to example embodiments. 
         FIG.  2    is a cross-sectional view taken along line A 1 -A 1 ′ of  FIG.  1   . 
         FIG.  3    is a cross-sectional view taken along line B 1 -B 1 ′ of  FIG.  1   . 
         FIG.  4    is an enlarged view of portion CX 1  of  FIG.  2   . 
         FIG.  5    is a cross-sectional view illustrating an integrated circuit according to example embodiments. 
         FIG.  6    is a cross-sectional view illustrating an integrated circuit according to example embodiments. 
         FIG.  7    is a cross-sectional view illustrating an integrated circuit according to example embodiments. 
         FIGS.  8 ,  9 A,  9 B,  10 A,  10 B,  11 ,  12 ,  13 ,  14 A,  14 B,  15 A,  15 B,  16 A,  16 B,  17 A , and  17 B are cross-sectional views illustrating a method of manufacturing an integrated circuit according to example embodiments.  FIGS.  8 ,  9 A,  10 A,  11 ,  12 ,  13 ,  14 A,  15 A,  16 A , and  17 A are cross-sectional views taken along line A 1 -A 1 ′ of  FIG.  1   .  FIGS.  9 B,  10 B,  16 B,  17 B  are cross-sectional views taken along line B 1 -B 1 ′ of  FIG.  1   .  FIGS.  14 B and  15 B  are horizontal sectional views at a first vertical level LV 1  of  FIGS.  14 A and  15 B . 
         FIGS.  18 ,  19 A, and  19 B  are cross-sectional views illustrating a method of manufacturing an integrated circuit according to example embodiments.  FIGS.  18  and  19 A  are cross-sectional views taken along line A 1 -A 1 ′ of  FIG.  1   .  FIG.  19 B  is a horizontal sectional view at a first vertical level LV 1  of  FIG.  19 A . 
         FIGS.  20  and  21    are cross-sectional views illustrating a method of manufacturing an integrated circuit according to example embodiments. 
         FIGS.  22 ,  23 , and  24    are cross-sectional views illustrating a method of manufacturing an integrated circuit according to example embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     Various example embodiments will now be described more fully hereinafter with reference to the accompanying drawings. Like reference numerals may refer to like elements throughout this application. 
       FIG.  1    is a layout view illustrating an integrated circuit according to example embodiments.  FIG.  2    is a cross-sectional view taken along line A 1 -A 1 ′ of  FIG.  1   .  FIG.  3    is a cross-sectional view taken along line B 1 -B 1 ′ of  FIG.  1   .  FIG.  4    is an enlarged view of portion CX 1  of  FIG.  2   . 
     Referring to  FIGS.  1  to  4   , in an integrated circuit  100  according to example embodiments, a substrate  110  may include a fin active region FA in a device region DR. The fin active region FA may be used to form a transistor TR, for example, an NMOS transistor or a PMOS transistor. 
     The substrate  110  may include a semiconductor material, such as Si or Ge, or a compound semiconductor material, such as SiGe, SiC, GaAs, InAs, or InP. In some embodiments, the substrate  110  may include a group III-V material and/or a group IV material. The group III-V material may be a binary or ternary, or quaternary compound including at least one group III material and a least one group V material. The group III-V material may include a compound including at least one element of In, Ga, and Al as the Group III material and including at least one element of As, P, and Sb as the group V material. For example, the group III-V material may include at least one of InP, InzGa 1-z As (0≤z≤1), and AlzGa 1-z As (0≤z≤1). The binary compound may be, for example, one of InP, GaAs, InAs, InSb, and GaSb. The ternary compound may be, for example, one of InGaP, InGaAs, AlInAs, InGaSb, GaAsSb, and GaAsP. The group IV material may be Si or Ge. However, the group III-V material and the group IV material are not limited to those described above. 
     In some embodiments, the group III-V material and the group IV material such as Ge may be used as a channel material for fabricating a low power and high speed transistor. A high performance CMOS transistor may be formed by using a semiconductor substrate including the group III-V material, for example, GaAs, having higher electron mobility than a silicon substrate, and a semiconductor substrate including a semiconductor material, such as Ge, having a higher hole mobility than the silicon substrate. In some embodiments, when the NMOS transistor is formed on the substrate  110 , the substrate  110  may include one of the group materials described above. In some embodiments, when the PMOS transistor is formed on the substrate  110 , at least a portion of the substrate  110  may include Ge. In some embodiments, the substrate  110  may have a silicon on insulator (SOI) structure. The substrate  110  may include a conductive region, such as an impurity doped well or and impurity doped structure. 
     The fin active region FA may extend in a first direction X, and may protrude in a third direction Z from an upper surface  110 M of the substrate  110 . The first direction may be parallel to the upper surface  110 M of the substrate  110 . The third direction may be perpendicular to the upper surface  110 M of the substrate  110 . A device isolation trench  114 T may be formed in the substrate  110  to define the fin active region FA. A device isolation layer  114  may be disposed in the device isolation trench  114 T. In some embodiments, the device isolation layer  114  may include a device isolation liner conformally formed on an inner surface of the device isolation trench  114 T and a gap fill insulation layer disposed on the device isolation liner and filling the device isolation trench  114 T. An upper surface of the device isolation layer  114  may be located at the same level as an upper surface of the fin active region FA. In some embodiments, the upper surface of the device isolation layer  114  may be located at a lower level than the upper surface of the fin active region FA, such that lower sidewalls of the fin active region FA may be covered by the device isolation layer  114 . The device isolation liner and the gap fill insulation layer may include silicon oxide, silicon nitride, or a combination thereof. 
     A plurality of semiconductor patterns NS may be disposed on the fin active region FA to be vertically spaced apart from the upper surface  110 M of the substrate  110 . The plurality of semiconductor patterns NS may include the same material as the substrate  110 . For example, the plurality of the semiconductor patterns NS may include a semiconductor material, such as Si or Ge, or a compound semiconductor material, such as SiGe, SiC, GaAs, InAs, or InP. Each of the plurality of semiconductor patterns NS may include a channel region. 
     The plurality of semiconductor patterns NS may include a first semiconductor pattern NS 1 , a semiconductor pattern NS 2 , and a third semiconductor pattern NS 3  that are sequentially stacked on the upper surface  110 M of the substrate  110 . Each of the plurality of semiconductor patterns NS may have a relatively large width in a second direction Y and a relatively small thickness in the third direction Z. Each of the plurality of semiconductor patterns NS may have a nanosheet shape, for example. The second direction Y may be parallel to the upper surface  110 M of the substrate  110  and perpendicular to the first direction X. For example, the first semiconductor pattern NS 1  may have a first thickness t 11  of about 1 nm to 10 nm, the second semiconductor pattern NS 2  may have a second thickness t 12  of about 1 nm to 10 nm, and the third semiconductor pattern NS 3  may have a third thickness t 13  of about 1 nm to 20 nm. As shown in  FIG.  3   , the third thickness t 13  of the third semiconductor pattern NS 3  may be greater than the first thickness t 11  of the first semiconductor pattern NS 1  and the second thickness t 12  of the second semiconductor pattern NS 2 , but embodiments are not limited thereto. In some embodiments, each of the plurality of the semiconductor patterns NS may have a width of about 5 nm to 100 nm in the first direction X or the second direction Y, but embodiments are not limited thereto. 
     As shown in  FIG.  2   , the plurality of semiconductor patterns NS may be spaced apart from each other. However, embodiments are not limited thereto. For example, spacing distances between the plurality of semiconductor patterns NS may be different from each other. The number of the plurality of semiconductor patterns NS may be limited to that shown in  FIGS.  2  to  4   . 
     A gate electrode  120  may extend in the fin active region FA in the second direction Y. The gate electrode  120  may surround the plurality of semiconductor patterns NS and may extend on the fin active region FA and the device isolation layer  114 . 
     The gate electrode  120  may include a main gate part  120 M and a plurality of sub gate parts  120 S. The main gate part  120 M may cover an uppermost semiconductor pattern NS (e.g., an upper surface of the third semiconductor pattern NS 3 ). The plurality of sub gate parts  120 S may respectively be disposed between the fin active region FA and a lowermost semiconductor pattern NS and between the plurality of semiconductor patterns NS. For example, the plurality of sub gate parts  120 S may be respectively disposed between the fin active region FA and the first semiconductor pattern NS 1 , between the first semiconductor pattern NS 1  and the second semiconductor pattern NS 2 , and between the second semiconductor pattern NS 2  and the third semiconductor pattern NS 3 . The main gate part  120 M may be disposed on the upper surface of the third semiconductor pattern NS 3  and the device isolation layer  114 , and may be connected to the plurality of sub gate parts  120 S. 
     The main gate part  120 M have a sloped sidewall  120 SI that is inclined along the third direction Z (or that is not perpendicular to the upper surface  110 M of the substrate  110 ) at a bottom portion of the main gate part  120 M. A sidewall  120 SW of the main gate part  120 M may include the sloped sidewall  120 SI that extends to a predetermined height from a bottom surface of the main gate part  120 M. For example, a height of the sloped sidewall  120 SI of the main gate part  120 M in the third direction Z may be about 1% to 20% of a height of the main gate part  120 M on the uppermost semiconductor pattern NS. 
     The gate electrode  120  may include a work function conductive layer and a buried conductive layer. The work function conductive layer may be disposed on the upper surface of the plurality of semiconductor patterns NS, and the buried conductive layer may be disposed on the work function conductive layer. In some embodiments, the work function conductive layer may include Al, Cu, Ti, Ta, W, Mo, TaN, NiSi, CoSi, TiN, WN, TiAl, TiAlC, TiAlN, TaCN, TaC, TaSiN, or a combination thereof, but embodiments are not limited thereto. The buried conductive layer may include Al, Cu, Ti, Ta, W, Mo, TaN, NiSi, CoSi, TiN, WN, TiAl, TiAlC, TiAlN, TaCN, TaC, TaSiN, or a combination thereof. However, embodiments are not limited thereto. 
     A gate insulation layer  128  may be disposed between the gate electrode  120  and each of the plurality of semiconductor patterns NS. The gate insulation layer  128  may be conformally disposed on surfaces of the plurality of semiconductor patterns NS. The gate insulation layer  128  may be disposed on the upper surface of the fin active region FA, and may extend onto the device isolation layer  114 . 
     In some embodiments, the gate insulation layer  128  may have a stack structure of an interfacial layer and a high dielectric layer. The interfacial layer may function to cure interfacial defects between the high dielectric layer and surfaces of the plurality of the semiconductor patterns NS and between the high dielectric layer and the upper surface of the fin active region FA. 
     The interfacial layer may include a low dielectric material having a dielectric constant of about 9 or less, for example, silicon oxide, silicon oxynitride, germanium oxide, gallium oxide, or a combination thereof. In some embodiments, the interfacial layer may include silicate, a combination of silicate and silicon oxide, or a combination of silicate and silicon oxynitride. In some embodiments, the interfacial layer may be omitted. 
     The high dielectric layer may include a material having a higher dielectric constant than that of silicon oxide. For example, the high dielectric layer may have a dielectric constant of about 10 to 25. The high dielectric layer may include, for example, hafnium oxide, hafnium oxynitride, hafnium silicon oxide, lanthanum oxide, lanthanum aluminum oxide, zirconium oxide, zirconium silicon oxide, tantalum oxide, titanium oxide, barium strontium titanium oxide, barium titanium oxide, strontium titanium oxide, yttrium oxide, aluminum oxide, lead scandium tantalum oxide, lead zinc niobate, or a combination thereof, but embodiments are not limited thereto. The high dielectric layer may be formed by atomic layer deposition (ALD), chemical vapor deposition (CVD), or physical vapor deposition (PVD). The high dielectric layer may have a thickness of about 10˜40 Å, but embodiments are not limited thereto. 
     A spacer structure  130  may be disposed on each of opposite sidewalls of the gate electrode  120 . The gate insulation layer  128  may be interposed between the gate electrode  120  and the spacer structure  130 . The spacer structure  130  may include a first spacer  132  and a second spacer  134  that are sequentially disposed on the sidewall  120 SW of the main gate part  120 M. 
     As shown in  FIG.  4   , the first spacer  132  may be conformally disposed on the sidewall  120 SW of the main gate part  120 M and on the third semiconductor pattern NS 3  adjacent to the main gate part  120 M. A bottom portion of the first spacer  132  may extend in a horizontal direction (e.g., the first direction X) on the upper surface of the third semiconductor pattern NS 3 , and may be disposed between the second spacer  134  and the third semiconductor pattern NS 3 . The first and second spacers  132  and  134  may include silicon nitride or silicon oxynitride, but are not limited thereto. 
     A recess region RS 1  may be formed in the fin active region FA at each of opposite sides of the plurality of semiconductor patterns NS. A source/drain region  140  may fill the recess region RS 1 . The source/drain region  140  may be connected to one ends of the plurality of semiconductor patterns NS. 
     The source/drain region  140  may include a first semiconductor layer  142 , a second semiconductor layer  144 , a third semiconductor layer  146 , and a fourth semiconductor layer  148  that are sequentially stacked on an inner surface of the recess region RS 1 . The first to fourth semiconductor layers  142 ,  144 ,  146 , and  148  may be grown from the fin active region FA and the plurality of semiconductor patterns NS by a selective epitaxial growth (SEG) process. 
     In some embodiments, the first semiconductor layer  142  may be formed to a predetermined thickness in the inner surface of the recess region RS 1 , and may contact the plurality of semiconductor patterns NS. The second semiconductor layer  144  may be conformally formed to a relatively small thickness on the first semiconductor layer  142 . The third semiconductor layer  146  may be formed to fill a lower portion of the recess region RS 1 . The fourth semiconductor layer  148  may be formed on the third semiconductor layer  146  and the second semiconductor layer  144  to fill an upper portion of the recess region RS 1 . A portion of an upper surface of the fourth semiconductor layer  148  may contact a bottom surface of the spacer structure  130 . Another portion of the upper surface of the fourth semiconductor layer  148  may protrude to a higher level than the bottom surface of the spacer structure  130 . Thus, the fourth semiconductor layer  148  may fill the upper portion of the recess region RS 1 , and an edge portion of the fourth semiconductor layer  148  may extend below the spacer structure  130  to be overlapped with the spacer structure  130 . 
     The first to fourth semiconductor layers  142 ,  144 ,  146 , and  148  may include at least one of an epitaxial Si layer, an epitaxial SiGe layer, an epitaxial SiP layer. In some embodiments, all the first to fourth semiconductor layers  142 ,  144 ,  146 , and  148  may include a Si layer, and impurity concentrations of the first to fourth semiconductor layers  142 ,  144 ,  146 , and  148  may be different from each other. In some embodiments, all the first to fourth semiconductor layers  142 ,  144 ,  146 , and  148  may include a SiGe layer, and Ge contents of the first to fourth semiconductor layers  142 ,  144 ,  146 , and  148  may be different from each other. In some embodiments, at least one of the first to fourth semiconductor layers  142 ,  144 ,  146 , and  148  may include a Si layer, and at least another one of the first to fourth semiconductor layers  142 ,  144 ,  146 , and  148  may include a SiGe layer. However, embodiments are not limited thereto. In some embodiments, at least one of the first to fourth semiconductor layers  142 ,  144 ,  146 , and  148  may be omitted. In some embodiments, at least one additional semiconductor layer may be formed between adjacent two layers of the first to fourth semiconductor layers  142 ,  144 ,  146 , and  148 . 
     As shown in  FIG.  4   , the recess region RS 1  may have a greater width at an intermediate portion than at an upper portion. Thus, a width of the source/drain region  140  in the recess region RS 1  may be greater at an uppermost portion than at an intermediate portion, such that at least a portion of the plurality of semiconductor patterns NS contacting the source/drain region  140  may have a sloped sidewall. 
     The source/drain region  140  may have a sloped sidewall, and thus the uppermost semiconductor pattern NS (or the third semiconductor pattern NS 3 ) may have a pair of sloped sidewalls NSSW conforming to a profile of the sloped sidewall of the source/drain region  140 . For example, each of the pair of sloped sidewalls NSSW may contact the first semiconductor layer  142  of the source/drain region  140 . A top portion of the uppermost semiconductor pattern NS (or the third semiconductor pattern NS 3 ) may have a first width W 11  in the first direction X, and a bottom portion of the uppermost semiconductor pattern NS (or the third semiconductor pattern NS 3 ) may have a second width W 12  smaller than the first width in the first direction X. 
     The uppermost semiconductor pattern (or the third semiconductor pattern NS 3 ) may include a tail portion NSTL adjacent to (or below) the spacer structure  130  at each of opposite edge portions thereof in the first direction X. The tail portion NSTL may indicate a portion of the uppermost semiconductor pattern NS (or the third semiconductor pattern NS 3 ) vertically overlapped with the spacer structure  130 . The tail portion NSTL may project outward in the first direction X with respect to the sidewall  120 SW of the main gate part  120 M. For example, an edge of the tail portion NSTL may be disposed spaced apart from the sidewall  120 SW in the first direction X. As a portion of the plurality of the semiconductor patterns NS include the tail portion NSTL, a portion of the plurality of semiconductor patterns NS may have a reverse trapezoidal shape. The tail portion NSTL may be disposed inward with respect to an outer sidewall of the spacer structure  130  (e.g., one sidewall of the spacer structure  130  opposite to another sidewall of the spacer structure  130  contacting the main gate part  120 M), and may be disposed spaced apart from the outer sidewall of the spacer structure  130  in the first direction X. 
     The bottom portion of the main gate part  120 M may have a third width W 21  in the first direction X, and an intermediate portion of the main gate part  120 M may have a fourth width W 22  greater than the third width W 21  in the first direction X. The first spacer  132  may fill a space defined by the sloped sidewall  120 S 1  of the bottom portion of the main gate part  120 M and the upper surface of the uppermost semiconductor pattern NS (or the third semiconductor pattern NS 3 ). For example, the first spacer  132  may include a protrusion  132 P at the bottom portion of the first spacer  132 , and the protrusion  132 P may fill the space defined by the sloped sidewall  120 SI of the bottom portion of the main gate part  120 M and the upper surface of the uppermost semiconductor pattern NS (or the third semiconductor pattern NS 3 ). The gate insulation layer  128  may be interposed between the sloped sidewall  120 S 1  of the main gate part  120 M and the protrusion  132 P of the first spacer  132 . The sloped sidewall  120 SI of the main gate part  120 M may vertically overlapped with a portion of the spacer structure  130 , e.g., the protrusion  132 P of the first spacer  132 . 
     As described above, the uppermost semiconductor pattern NS (e.g., the third semiconductor pattern NS 3 ) may have a reverse trapezoidal shape. The first width W 11  of the top portion of the uppermost semiconductor pattern NS (or the third semiconductor pattern NS 3 ) may be greater than the third width W 21  of the bottom portion of the main gate part  120 M. Since the protrusion  132 P of the first spacer  132  is disposed between the bottom portion of the main gate part  120 M and the source/drain region  140 , the spacing distance between the source/drain region  140  and the main gate part  120 M may be relatively increased compared to a structure in which the main gate part  120 M has a vertical sidewall at a bottom portion thereof. Accordingly, a leakage current between the source/drain region  140  and the main gate part  120 M may be prevented or reduced. In addition, in a process of forming the source/drain region  140  or a process of removing a dummy gate structure (see DG of  FIG.  15 A ) and forming the gate electrode  120 , a process defect, such as an undesired connection between the dummy gate structure DG and the source/drain region  140  or between the gate electrode  120  and the source/drain region  140 , may be prevented. 
     A gate insulation liner  152  and an inter-gate insulation layer  154  may be sequentially disposed on a sidewall of the spacer structure  130 , the source/drain region  140 , and the device isolation layer  114 . An upper insulation layer  162  may be disposed on the gate electrode  120  and the inter-gate insulation layer  154 . A contact plug  166  may be disposed in a contact hole  166 H that penetrates the upper insulation layer  162  and exposes an upper surface of the source/drain region  140 . A metal silicide layer  168  may be disposed between the contact plug  166  and the source/drain region  140 . For example, the metal silicide layer  168  may include titanium silicide or cobalt silicide, but is not limited thereto. 
     Although not shown in the drawings, vias and interconnection layers may be disposed on the upper insulation layer  162  to be connected the contact plug  166  and the gate electrode  120 . 
     In general, the dummy gate structure (see DG of  FIG.  15 A ) may be formed on the plurality of semiconductor patterns NS, the recess region RS 1  may be formed by removing portions of the semiconductor patterns NS at each of opposite sides of the dummy gate structure DG, and the source/drain region  140  may be formed in the recess region RS 1 . However, since a spacing distance between the recess region RS 1  and the dummy gate structure DG may be relatively small at an edge portion of the semiconductor patterns NS, a process defect, such as an undesired connection between the dummy gate structure DG and the source/drain region  140  or between the gate electrode  120  and the source/drain region  140 , may be generated. Accordingly, a leakage current may be generated between the gate electrode  120  and the source/drain region  140   
     According to example embodiments, a portion of the plurality of semiconductor patterns NS may have the reverse trapezoidal shape, and the uppermost semiconductor pattern NS may have a tail portion NSTL at each of opposite edges thereof. Thus, a relatively great spacing distance between the source/drain region  140  and the dummy gate structure DG or the source/drain region  140  and the gate electrode  120  may be obtained, such that the process defect, such as an undesired connection between the dummy gate structure DG and the source/drain region  140  or between the gate electrode  120  and the source/drain region  140 , may be prevented. Accordingly, a leakage current between the source/drain region  140  and the main gate part  120 M may be prevented or reduced. 
       FIG.  5    is a cross-sectional view illustrating an integrated circuit according to example embodiments. In  FIG.  5   , the same numerals are used to denote the same elements shown in  FIGS.  1  to  4   . 
     Referring to  FIG.  5   , in an integrated circuit  100 A according to example embodiments, a spacer structure  130 A may include a first spacer  132 A and a second spacer  134 A that are sequentially disposed on a sidewall of the gate electrode  120 . A bottom portion of the first spacer  132 A and a bottom portion of the second spacer  134 A may extend in the horizontal direction on an upper surface of the plurality of semiconductor patterns NS. The second spacer  134 A may include a lateral extension  134 W that extends outward from a sidewall of the first spacer  132 A. The bottom portion of the first spacer  132 A may be interposed between the lateral extension  134 W and the uppermost semiconductor pattern NS (the third semiconductor pattern NS 3 ). The lateral extension  134 W may be vertically overlapped with the tail portion NSTL of the uppermost semiconductor pattern NS (or the third semiconductor pattern NS 3 ). 
     As the lateral extension  134 W is disposed over the upper surface of the uppermost semiconductor pattern NS, in a process of etching the semiconductor patterns NS to form a recess region RS 1 A, the upper surface of the uppermost semiconductor pattern NS may be covered by the spacer structure  130 A, and thus the uppermost semiconductor pattern NS may have a sloped sidewall NSSW tilted at a relatively large angle. A spacing distance between a source/drain region  140 A and the main gate part  120 M may be relatively large. 
     A first width W 11 A of the top portion of the uppermost semiconductor pattern NS in the first direction X may be greater than a second width W 12 A of the bottom portion of the uppermost semiconductor patterns NS in the first direction X. For example, the first width W 11 A of the top portion of the uppermost semiconductor pattern NS in the first direction X may be greater than the first width W 11  of the top portion of the uppermost semiconductor pattern NS described with reference to  FIGS.  1  to  4   , but embodiments are not limited thereto. 
     In a manufacturing process according to example embodiments, a first spacer layer (see  132 L of  FIG.  18   ), a second spacer layer (see  134 L of  FIG.  18   ), and a cover spacer layer (see  136 LA of  FIG.  18   ) may be formed on the dummy gate structure (see DG of  FIG.  18   ), and an anisotropic etching process may be performed on the first spacer layer  132 L, the second spacer layer  134 L, and the cover spacer layer  136 LA to form the spacer structure  130 A. When the cover spacer layer  136 LA has a relatively great thickness, a portion of the second spacer layer  134 L extending in the horizontal direction from the dummy gate structure (see DG of  FIG.  18   ) on the plurality of the semiconductor patterns NS may be relatively less etched due to the cover spacer layer  136 LA in the anisotropic etching process, such that the lateral extension  134 W may remain. 
     According to the integrated circuit  100 A, since a spacing distance between the source/drain region  140 A and the main gate part  120 M is relatively great, a leakage current between the source/drain region  140 A and the main gate part  120 M may be prevented or reduced. A process defect, such as an undesired connection between the dummy gate structure DG and the source/drain region  140  or between the gate electrode  120  and the source/drain region  140 , may be prevented. 
       FIG.  6    is a cross-sectional view illustrating an integrated circuit according to example embodiments. In  FIG.  6   , the same numerals are used to denote the same elements shown in  FIGS.  1  to  5   . 
     Referring to  FIG.  6   , in an integrated circuit  100 B according to example embodiments, a bottom portion of a main gate part  120 MB may have a third width W 21 B, and an intermediate portion of the main gate part  120 MB may have a fourth width W 22 B smaller than the third width W 21 B. The bottom portion of the main gate part  120 MB may have a sloped sidewall  120 SIB. The sloped sidewall  120 SIB may have a positive slope (or may downwardly and outwardly extend). A portion of the main gate part  120 MB adjacent to the sloped sidewall  120 SIB of the main gate part  120 MB may refer to a protrusion  120 MP. The protrusion  120 MP of the main gate part  120 MB may protrude outward toward a spacer structure  130 B at the bottom portion of the main gate part  120 MB. 
     A spacer structure  130 B may include a first spacer  132 B and a second spacer  134 B. A portion of the first spacer  132 B adjacent to the protrusion  120 MP of the main gate part  120 MB may have a relatively thin thickness. 
     In a manufacturing process according to example embodiments, an etching process may be performed on a sidewall (see DGI_OS of  FIG.  10 A ) of a dummy gate insulation layer (see DGI of  FIG.  10 A ) under the dummy gate structure (see DG of  FIG.  10   ), such that the dummy gate insulation layer (see DGI of  FIG.  11   ) is formed to have a recessed sidewall (see DGI_IS of  FIG.  11   ). Thereafter, the spacer structure (see  130  of  FIG.  13   ) may be formed on the dummy gate structure (see DG of  FIG.  13   ). In addition, the recess region RS 1  may be formed at each of opposite sides of the dummy gate structure DG, and a source/drain region  140 B may be formed in the recess region RS 1 . After a process of removing the dummy gate structure DG is performed, a portion of a bottom portion of the first spacer  132 B on an upper surface of the exposed semiconductor pattern NS may be removed. In this case, since a spacing distance between the dummy gate structure DG and the source/drain region  140  is relatively great, the source/drain region  140  may be prevented from being exposed to an etching environment, in the removal process of the dummy gate structure DG. 
     The source/drain region  140 B may include a first semiconductor layer  142 B, a second semiconductor layer  144 B, a third semiconductor layer  146 B, and a fourth semiconductor layer  148 B that are sequentially disposed in the recess region RS 1 . The first semiconductor layer  142 B may have a relatively great thickness. An upper surface of the first semiconductor layer  142 B may contact a bottom surface of the spacer structure  130 B. 
     In some embodiments, all the first, second, third, fourth semiconductor layers  142 B,  144 B,  146 B, and  148 B may include a Si layer, impurity concentrations of the first to fourth semiconductor layers  142 B,  144 B,  146 B, and  148 B may differ from each other. In some embodiments, all the first to fourth semiconductor layers  142 B,  144 B,  146 B, and  148 B may include a SiGe layer, and Ge contents of the first to fourth semiconductor layers  142 B,  144 B,  146 B, and  148 B may be different from each other. For example, the first semiconductor layer  142 B may have a relatively low impurity concentration or a relatively low Ge content, and the third semiconductor layer  146 B and the fourth semiconductor layer  148 B may have a relatively high impurity concentration or a relatively high Ge content. In this case, a spacing distance between the third semiconductor layer  146 B and the main gate part  120 MB or between the fourth semiconductor layer  148 B and the main gate part  120 MB may be relatively great, and a leakage current between the source/drain region  140 B (e.g., the third semiconductor layer  146 B and the fourth semiconductor layer  148 B of the source/drain region  140 B) and the main gate part  120 M may be prevented or reduced. 
       FIG.  7    is a cross-sectional view illustrating an integrated circuit according to example embodiments. In  FIG.  7   , the same numerals are used to denote the same elements shown in  FIGS.  1  to  4   . 
     Referring to  FIG.  7   , in an integrated circuit  100 C according to example embodiments, an inner spacer  172  may be disposed between the source/drain region  140  and the gate electrode  120 . The inner spacer  172  may be disposed between each of a plurality of sub gate parts  120 S and the source/drain region  140 , and the gate insulation layer  128  may be disposed between each of the plurality of sub gate parts  120 S and the inner spacer  172 . For example, the inner spacer  172  may include silicon nitride or silicon oxynitride. 
     In the integrated circuit  100 C according to example embodiments, since a spacing distance between the source/drain region  140  and the main gate part  120 M is relatively great, a leakage current between the source/drain region  140  and the main gate part  120 M may be prevented or reduced. 
       FIGS.  8 ,  9 A,  9 B,  10 A,  10 B,  11 ,  12 ,  13 ,  14 A,  14 B,  15 A,  15 B,  16 A,  16 B,  17 A , and  17 B are cross-sectional views illustrating a method of manufacturing an integrated circuit according to example embodiments.  FIGS.  8 ,  9 A,  10 A,  11 ,  12 ,  13 ,  14 A,  15 A,  16 A , and  17 A are cross-sectional views taken along line A 1 -A 1 ′ of  FIG.  1   .  FIGS.  9 B,  10 B,  16 B,  17 B  are cross-sectional views taken along line B 1 -B 1 ′ of  FIG.  1   .  FIGS.  14 B and  15 B  are horizontal sectional views at a first vertical level LV 1  of  FIGS.  14 A and  15 B . 
     Referring to  FIG.  8   , sacrificial layers  210  and channel semiconductor layers PNS may be repeatedly and alternately formed on the upper surface  110 M of the substrate  110  to form a sacrificial stack  210 S. The sacrificial layers  210  and the channel semiconductor layers PNS may be formed by an epitaxial process. 
     In some embodiments, the sacrificial layers  210  and the channel semiconductor layers PNS may be formed of materials having different etch selectivities. For example, the sacrificial layers  210  and the channel semiconductor layers PNS may be formed of a group IV semiconductor single crystal layer, a group IV-IV compound semiconductor single crystal layer, or a group III-V compound semiconductor single crystal layer. For example, the sacrificial layers  210  may be formed of a different material form the channel semiconductor layers PNS. In some embodiments, the sacrificial layers  210  may be formed of silicon germanium (SiGe), and the channel semiconductor layers PNS may be formed of crystal silicon. 
     In some embodiments, the epitaxial process may include a chemical vapor deposition (CVD) process, such as vapor-phase epitaxy (VPE), or ultra-high vacuum CVD (UHV-CVD), a molecular beam epitaxy, or a combination thereof. In the above epitaxial process, a liquid or vapor precursor may be used to form the sacrificial layers  210  and the channel semiconductor layers PNS. 
     Referring to  FIGS.  9 A and  9 B , after a hard mask pattern extending in the first direction X to a predetermined length is formed on an uppermost one of the channel semiconductor layers PNS, the sacrificial layers  210 , the channel semiconductor layers PNS, and the substrate  110  may be etched using the hard mask pattern as an etch mask to form a sacrificial pattern  210 P and a device isolation trench  114 T. 
     After the device isolation trench  114 T is filled with an insulating material, the insulating material may be planarized to form the device isolation layer  114  filling the device isolation trench  114 T. The fin active region FA may be defined in the substrate  110  by the device isolation layer  114 . 
     The hard mask pattern remaining on the sacrificial pattern  210 P may be removed, and then the device isolation layer  114  may be removed by a predetermined thickness by a recess process. In some embodiments, the recess process may be performed until an upper surface of the device isolation layer  114  is located at the same level as the upper surface  110 M of the substrate  110 . In some embodiments, the recess process may be performed until an upper surface of the device isolation layer  114  is located at a lower level than the upper surface  110 M of the substrate  110 , such that a portion of a sidewall of the fin active region FA may be exposed. 
       FIGS.  10 A and  10 B , the dummy gate structure DG may be formed on the sacrificial pattern  210 P and the device isolation layer  114 . The dummy gate structure DG may include a dummy gate insulation layer DGI, a dummy gate line DGL, and a dummy gate capping layer DGC. 
     For example, the dummy gate line DGL may be formed of polysilicon. The dummy gate capping layer DGC may be formed of silicon nitride. The dummy gate insulation layer DGI may be formed of a material having an etch selectivity with respect to the dummy gate line DGL and may be formed of, for example, one of thermal oxide, silicon oxide, and silicon nitride. 
     The dummy gate insulation layer DGI may have a sidewall DGI_OS protruding outward from a sidewall of the dummy gate structure DG. For example, when a height of the dummy gate structure DG is relatively high, a portion of the dummy gate insulation layer DGI may remain without being removed under an etching environment, such that the sidewall DGI_OS of the dummy gate insulation layer DGI may protrude outward from the sidewall of the dummy gate line DGL. 
     Referring to  FIG.  11   , an additional etching process for removing a portion of the sidewall DGI_OS of the dummy gate insulation layer DGI may be performed, such that the dummy gate insulation layer DGI may have a recessed sidewall DGI_IS. The recessed sidewall DGI_IS of the dummy gate insulation layer DGI may be a portion recessed inward from the sidewall of the dummy gate line DGL. 
     Referring to  FIG.  12   , the first spacer layer  132 L, the second spacer layer  134 L, and the cover spacer layer  136 L may be sequentially formed on the dummy gate structure DG. For example, the first spacer layer  132 L, the second spacer layer  134 L may be formed of silicon nitride or silicon oxynitride, and the cover spacer layer  136 L may be formed of silicon oxide. However, embodiments are not limited thereto. 
     The first spacer layer  132 L may be conformally formed on the recessed sidewall DGI_OS of the dummy gate insulation layer DGI. Thus, a portion of the first spacer layer  132 L contacting the recess sidewall DGI_IS of the dummy gate insulation layer DGI may correspond to the protrusion  132 P of the first spacer  132  shown in  FIG.  4   . 
     Referring to  FIG.  13   , an anisotropic etching process may be performed on the first spacer layer  132 L, the second spacer layer  134 L, and the cover spacer layer  136 L to form the spacer structure  130  on each of opposite sidewalls of the dummy gate structure DG. 
     In the anisotropic etching process, the cover spacer layer  136 L on an upper surface of the dummy gate structure DG and an upper surface of the sacrificial pattern  210 P may also be removed. The spacer structure  130  may include the first spacer  132  and the second spacer  134  that are sequentially disposed on each of the sidewalls of the dummy gate structure DG. A bottom surface of the second spacer  134  may be covered by the first spacer  132 . As shown in  FIG.  13   , the cover spacer layer  136 L may be completely removed, and thus a sidewall of the second spacer  134  may not be covered by the cover spacer layer  136 L. However, in some embodiments, a portion of the cover spacer layer  136 L may remain on a portion of the sidewall of the second spacer  134 . In this case, an additional etching process may be further performed to remove the cover spacer layer  136 L. In some embodiments, the additional etching process for removing the cover spacer layer  136  may not be performed, and the remaining portion of the cover spacer layer  136 L may be removed in a subsequent process for forming the recess region RS 1 . 
     Referring to  FIGS.  14 A and  14 B , portions of the sacrificial pattern  210 P and the substrate  110  at opposite sides of the dummy gate structure DG and the spacer structure  130  may etched to form the recess region RS 1  at each of the opposite sides of the dummy gate structure DG. As the recess region RS 1  is formed, the sacrificial pattern  210 P may be separated into a plurality of semiconductor patterns NS. For example, the plurality of semiconductor patterns NS may include the first, second, and third semiconductor patterns NS 1 , NS 2 , and NS 3  spaced apart from each other by the sacrificial layers  210 . 
     In some embodiments, in the process of forming the recess region RS 1 , the uppermost semiconductor pattern NS overlapped with the spacer structure  130  may not be removed (or a portion of the third semiconductor pattern NS 3  may not be removed, but the other semiconductor pattern NS (e.g., the second semiconductor pattern NS 2  or the first semiconductor pattern NS 1 ) overlapped with the spacer structure  130  may be removed). A width of an intermediate portion of the recess region RS 1  may greater than a width of an upper portion of the recess region RS 1 . The plurality of sacrificial layers  210  may include a tail portion  210 TL overlapped with the spacer structure  130 . The plurality of semiconductor patterns NS may include the tail portion (see e.g., NSTL of  FIG.  4   ) overlapped with the spacer structure  130 , similar to the tail portion  210 TL of the plurality of sacrificial layers  210 . 
     As described above, since, in the formation process of the spacer structure  130 , the surface of the second spacer layer  134 L is covered by the cover spacer layer  136 L, the spacer structure  130  remaining after the anisotropic etching process may have a relatively great width d 11  in the first direction X. For example, when the width d 11  of the spacer structure  130  in the first direction X is relatively great, in the formation process of the recess region RS 1 , portions of the sacrificial layers  210  adjacent to the spacer structure  130  may be less exposed to the etching environment, and thus the tail portion  210 TL of each of the sacrificial layers  210  may be formed. In addition, since the first spacer  132  includes the protrusion  132 P, a spacing distance between the recess region RS 1  and the dummy gate structure DG may be relatively increased. 
     Referring to  FIGS.  15 A and  15 B , the first semiconductor layer  142 , the second semiconductor layer  144 , the third semiconductor layer  146 , and the fourth semiconductor layer  148  may be sequentially formed to form the source/drain region  140 . For example, the first to fourth semiconductor layers  142 ,  144 ,  146 , and  148  may be formed by epitaxially growing a semiconductor material from the plurality of semiconductor patterns NS, the sacrificial layers  210 , and the substrate  110  exposed on an inner surface of the recess region RS 1 . The first to fourth semiconductor layers  142 ,  144 ,  146 , and  148  may include at least one of a Si layer, a SiC layer, a SiGe layer, and a SiP layer that are epitaxially grown. 
     Thereafter, the gate insulation liner  152  and the inter-gate insulation layer  154  may be sequentially formed on the sidewall of the spacer structure  130 , the source/drain region  140 , and the device isolation layer  114 . Upper portions of the dummy gate structure DG, the gate insulation liner  152 , and the inter-gate insulation layer  154  may be planarized to remove the dummy gate capping layer DGC of the dummy gate structure DG, such that an upper surface of the dummy gate line DGL may be exposed. 
     Referring to  FIGS.  16 A and  16 B , the dummy gate line DGL and the dummy gate insulation layer DGI exposed by the inter-gate insulation layer  154  may be removed to form a gate space GS. 
     Thereafter, the plurality of sacrificial layers  210  remaining on the fin active region FA may be removed through the gate space GS to expose the plurality of semiconductor patterns NS and a portion of an upper surface of the fin active region FA. Accordingly, a sub gate space GSS may be formed between each of the plurality of semiconductor patterns NS and between a lowermost one of the plurality of semiconductor patterns NS and the fin active region FA. The removal process of the plurality of sacrificial layers  210  may be performed by a wet etching process using a difference in an etch selectivity between the plurality of sacrificial layers  210  and the plurality of semiconductor patterns NS. 
     As described above, since the width d 11  of the spacer structure  130  in the first direction X is relatively great and the first spacer  132  includes the protrusion  132 P, in the removal process of the dummy gate line DGL, the upper surface of the source/drain region  140  may not be exposed. For example, when a spacing distance between the source/drain region  140  and the dummy gate line DGL is relatively small, in the removal process of the dummy gate line DGL, an edge portion of the source/drain region  140  may also be exposed to the etching environment. Thus, a process failure in which the source/drain region  140  may be etched or a gate electrode material may be filled in the removed region of the source/drain region  140  may be generated. However, since the width d 11  of the spacer structure  130  in the first direction X is relatively great and the first spacer  132  includes the protrusion  132 P, the process defect may not be generated in the removal process of the dummy gate line DGL. 
     Referring to  FIGS.  17 A and  17 B , the gate insulation layer  128  may be formed on inner surfaces of the gate space GS and the sub gate space GSS. The gate electrode  120  may be formed on the gate insulation layer  128  to fill the gate space GS and the sub gate space GSS. For example, after a work function conductive layer is conformally formed on the inner surfaces of the gate space GS and the sub gate space GSS, a buried conductive layer may be formed on the work function conductive layer to fill the gate space GS and the sub gate space GSS. Thereafter, an upper portion of the buried conductive layer may be planarized until an upper surface of the inter-gate insulation layer  154  is exposed, such that the gate electrode  120  may be formed. In some embodiments, the work function conductive layer may be formed of Al, Cu, Ti, Ta, W, Mo, TaN, NiSi, CoSi, TiN, WN, TiAl, TiAlC, TiAlN, TaCN, TaC, TaSiN, or a combination thereof. The buried conductive layer may be formed of Al, Cu, Ti, Ta, W, Mo, TaN, NiSi, CoSi, TiN, WN, TiAl, TiAlC, TiAlN, TaCN, TaC, TaSiN, or a combination thereof. 
     Referring again to  FIG.  2   , after the upper insulation layer  162  is formed and then a contact hole  166 H penetrating the upper insulation layer  162  is formed, the contact hole  166 H may be filled with a conductive material to form the contact plug  166 . 
     According to the aforementioned method of manufacturing the integrated circuit  100 , as the second spacer layer  134 L is covered by the cover spacer layer  136 L in the formation process of the spacer structure  130 , the width d 11  of the spacer structure  130  in the first direction X may be relatively great. In addition, as the etching process for forming the recess sidewall DGI_IS of the dummy gate insulation layer DGI is performed, the first spacer  132  may include the protrusion  132 P. Thus, since the spacing distance between the source/drain region  140  and the dummy gate structure DG is relatively increased, the upper surface of the source/drain region  140  may not exposed by the gate space GS. The exposure and removal of the source/drain region  140  may not occur in the aforementioned removal process of the dummy gate line DGL. 
       FIGS.  18 ,  19 A, and  19 B  are cross-sectional views illustrating a method of manufacturing an integrated circuit according to example embodiments.  FIGS.  18  and  19 A  are cross-sectional views taken along line A 1 -A 1 ′ of  FIG.  1   .  FIG.  19 B  is a horizontal sectional view at a first vertical level LV 1  of  FIG.  19 A . 
     Referring to  FIG.  18   , the first spacer layer  132 L, the second spacer layer  134 L, and a cover spacer layer  136 LA may be sequentially formed on an upper surface and sidewalls of the dummy gate structure DG. The cover spacer layer  136 LA may have a thickness that is relatively great. 
     Referring to  FIGS.  19 A and  19 B , an anisotropic etching process may be performed on the first spacer layer  132 L, the second spacer layer  134 L, and the cover spacer layer  136 LA to form a spacer structure  130 A. In the anisotropic etching process, the second spacer  134 A may be formed to include the lateral extension  134 W extending in the horizontal direction. 
     As shown in  FIG.  19 A , the cover spacer layer  136 LA may be completely removed, such that the sidewall of the second spacer  134 A may not be covered. However, in some embodiments, a portion of the cover spacer layer  136 LA may remain on at least a portion of the sidewall of the second spacer  134 A. In this case, an additional etching process may be performed to remove the cover spacer layer  136 LA. In some embodiments, the additional etching process for removing the cover spacer layer  136 LA may not be performed, and the remaining portion of the cover spacer layer  136 LA may also be removed in a subsequent process for forming a recess region RS 1 A. 
     Thereafter, portions of the sacrificial pattern  210 P and the substrate  110  at opposite sides of the dummy gate structure DG and the spacer structure  130 A may be etched to form the recess region RS 1 A at each of the opposite sides of the dummy gate structure DG. 
     As described above, in the formation process of the spacer structure  130 A, as the second spacer layer  134 L is covered by the relatively thick cover spacer layer  136 LA, the spacer structure  130 A remaining in the anisotropic etching process may have a relatively great width d 12  in the first direction X. For example, when the width d 12  of the spacer structure  130 A in the first direction X is relatively great, in the formation process of the recess region RS 1 A, portions of the sacrificial layers  210  adjacent to the spacer structure  130 A may not be less exposed to the etching environment. Thus, the tail portion  210 TL of each of the sacrificial layers  210  may be formed. 
     Thereafter, the processes described with reference to  FIGS.  15 A to  17 B  may be performed to form an integrated circuit  100 A. 
       FIGS.  20  and  21    are cross-sectional views illustrating a method of manufacturing an integrated circuit according to example embodiments. 
     First, the process described with reference to  FIGS.  16 A and  16 B , may be performed. That is, the dummy gate line DGL and the dummy gate insulation layer DGI that are exposed by the inter-gate insulation layer  154  may be removed to form the gate space GS, and the sacrificial layers  210  exposed through the gate space GS may be removed to form the sub gate space GSS between each of the plurality of semiconductor patterns NS and between the lowermost semiconductor pattern NS and the fin active region FS. At that time, the first spacer  132  may include the protrusion  132 P at the bottom portion thereof, and thus, in the removal process of the dummy gate line DGL, a relatively great spacing distance may be secured between the source/drain region  140  and the gate space GS. 
     Referring to  FIG.  20   , a portion of a bottom portion of the first spacer  132  exposed in the gate space GS may be removed. Thus, a width of a bottom portion of the gate space GS may be greater than a width of an intermediate portion of the gate space GS. 
     Referring to  FIG.  21   , the gate insulation layer  128  and the gate electrode  120  may be formed on inner surfaces of the gate space GS and the sub gate space GSS. The main gate part  120 MB may be formed to include the protrusion (see  120 MP of  FIG.  6   ) filling an edge of the bottom portion of the gate space GS. 
     According to the aforementioned method, in the removal process of the dummy gate structure DG, since the relatively great spacing distance is obtained between the dummy gate structure DG and the source/drain region  140 , the source/drain region  140  may not be exposed to an etch environment in the removal process of the dummy gate structure DG. 
       FIGS.  22 ,  23 , and  24    are cross-sectional views illustrating a method of manufacturing an integrated circuit according to example embodiments. 
     Referring to  FIG.  22   , in the structure in which the recess region RS 1  is formed, portions of the sacrificial layers  210  exposed in the recess region RS 1  may be removed by an isotropic etching process to form an indent region RSE between each of the plurality of semiconductor patterns NS. In some embodiments, a wet etching process using a difference in the etch selectivity between the plurality of sacrificial layers  210  and the plurality of semiconductor patterns NS may be performed to form the indent region RSE. For example, in the wet etching process, the sacrificial layers  210  including SiGe may be more rapidly etched than the plurality of semiconductor patterns NS including Si, thus forming the indent region RSE. 
     Referring to  FIG.  23   , an inner spacer layer  172 L may be conformally formed on an upper surface of the dummy gate structure DG, a sidewall of the spacer structure  130 , an inner surface of the recess region RS 1 , and an inner surface of the indent region RSE. The inner spacer layer  172 L may be formed to a sufficient thickness to fill the indent region RSE. 
     Referring to  FIG.  24   , an anisotropic etching process may be performed on the inner spacer layer  172 L, such that an inner spacer  172  may remain in the indent region RSE. In the anisotropic etching process, the inner spacer layer  172 L on the dummy gate structure DG and the sidewall of the spacer structure  130 , and in the recess region RS 1  may be removed. 
     Thereafter, the process described with reference to  FIGS.  15 A to  17 B  may be performed to form an integrated circuit  100 C. 
     While example embodiments have been shown and described, it will be understood by those of ordinary skill in the art that various changes in form and details may be made thereto without departing from the spirit and scope of the present invention as set forth by the following claims.