Patent Publication Number: US-2021175242-A1

Title: Semiconductor memory device and manufacturing method of the semiconductor memory device

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application claims priority under 35 U.S.C. § 119(a) to Korean patent application number 10-2019-0162380 filed on Dec. 9, 2019, the entire disclosure of which is incorporated herein by reference. 
     BACKGROUND 
     1. Technical Field 
     The present disclosure generally relates to a semiconductor memory device and a manufacturing method of the semiconductor memory device, and more particularly, to a three-dimensional semiconductor memory device and a manufacturing method of the three-dimensional semiconductor memory device. 
     2. Related Art 
     A semiconductor memory device includes memory cells capable of storing data. 
     According to a method of storing data and a method of retaining data, the semiconductor memory device may be classified into a volatile semiconductor memory device and a nonvolatile semiconductor memory device. The volatile semiconductor memory device is a memory device in which stored data disappears when the supply of power is interrupted, and the nonvolatile semiconductor memory device is a memory device in which stored data is retained even when the supply of power is interrupted. 
     Recently, as portable electronic devices are increasingly used, nonvolatile semiconductor memory devices have been increasingly used, and the high integration and large capacity of semiconductor memory devices have been required to achieve portability and large capacity. In order to achieve the portability and large capacity, there have been proposed three-dimensional semiconductor memory devices. 
     SUMMARY 
     In accordance with an aspect of the present disclosure, there is provided a method of manufacturing a semiconductor memory device, the method may include: forming sacrificial patterns and insulating patterns, which are alternately stacked on a source structure; forming channel structures penetrating the sacrificial patterns and the insulating patterns; forming a first trench and a second trench, which penetrate the sacrificial patterns and the insulating patterns; replacing the sacrificial patterns with conductive patterns through the first and second trenches; and forming gate isolation layers, which penetrate some of the conductive patterns and some of the insulating patterns, and are located between the first trench and the second trench, wherein the insulating patterns include a second insulating pattern and first insulating patterns between the second insulating pattern and the source structure, wherein lowermost portions of the gate isolation layers are located in the second insulating pattern, wherein the second insulating pattern has a thickness thicker than those of the first insulating patterns. 
     In accordance with another aspect of the present disclosure, there is provided a semiconductor memory device which may include: a stack structure including conductive patterns and insulating patterns, which are alternately stacked; first and second slit structures spaced apart from each other with the stack structure interposed between the first and second slit structures; a first gate isolation layer penetrating a portion of the stack structure, the first gate isolation layer being disposed between the first slit structure and the second slit structure; a second gate isolation layer penetrating a portion of the stack structure, the second gate isolation layer being disposed between the first slit structure and the second slit structure; and first channel structures penetrating the stack structure, the first channel structures being disposed between the first gate isolation layer and the second gate isolation layer, wherein the insulating patterns include a second insulating pattern in contact with lowermost portions of the first and second gate isolation layers and first insulating patterns spaced apart from the first and second gate isolation layers, wherein the second insulating pattern has a thickness thicker than those of the first insulating patterns. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Examples of embodiments will now be described more fully hereinafter with reference to the accompanying drawings; however, they may be embodied in different forms and should not be construed as limited to the embodiments set forth herein. 
       In the drawing figures, dimensions may be exaggerated for clarity of illustration. It will be understood that when an element is referred to as being “between” two elements, it can be the only element between the two elements, or one or more intervening elements may also be present. Like reference numerals refer to like elements throughout. 
         FIG. 1A  is a plan view of a semiconductor memory device in accordance with a first embodiment of the present disclosure. 
         FIG. 1B  is a sectional view taken along line A-A′ shown in  FIG. 1A . 
         FIG. 1C  is an enlarged view of region B shown in  FIG. 1B . 
         FIG. 2A  is a sectional view of a semiconductor memory device in accordance with a second embodiment of the present disclosure. 
         FIG. 2B  is an enlarged view of region C shown in  FIG. 2A . 
         FIGS. 3A, 3B, 3C, 3D, and 3E  are sectional views illustrating a manufacturing method of the semiconductor memory device in accordance with the first embodiment of the present disclosure. 
         FIG. 4  is a block diagram illustrating a configuration of a memory system in accordance with an embodiment of the present disclosure. 
         FIG. 5  is a block diagram illustrating a configuration of a computing system in accordance with an embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     The specific structural or functional description disclosed herein is merely illustrative for the purpose of describing embodiments according to the concept of the present disclosure. The embodiments according to the concept of the present disclosure can be implemented in various forms, and cannot be construed as limited to the embodiments set forth herein. 
     It will be understood that, although the terms first, second, third etc. may be used herein to describe various elements, patterns, components, regions, layers and/or sections, these elements, patterns, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, pattern, component, region, layer or section from another region, layer or section. Thus, a first element, pattern, component, region, layer or section discussed below could be termed a second element, pattern, component, region, layer or section without departing from the teachings of the present disclosure. 
     Embodiments provide a semiconductor memory device capable of improving operational reliability and a manufacturing method of the semiconductor memory device. 
       FIG. 1A  is a plan view of a semiconductor memory device in accordance with a first embodiment of the present disclosure.  FIG. 1B  is a sectional view taken along line A-A′ shown in  FIG. 1A .  FIG. 1C  is an enlarged view of region B shown in  FIG. 1B . 
     Referring to  FIGS. 1A to 1C , the semiconductor memory device in accordance with these embodiments may include a substrate  100 . The substrate  100  may have the shape of a plate expanding along a plane defined by a first direction D 1  and a second direction D 2 . A direction protruding from the plane may be defined as a third direction D 3 . In an example, the third direction D 3  may be perpendicular to the plane. The first to third directions D 1 , D 2 , and D 3  may intersect one another. 
     The substrate  100  may include a first isolation region DR 1 , a first stack region SR 1 , a second isolation region DR 2 , a second stack region SR 2 , and a third isolation region DR 3 . The first isolation region DR 1 , the first stack region SR 1 , the second isolation region DR 2 , the second stack region SR 2 , and the third isolation region DR 3  may be sequentially arranged along the first direction D 1 . The first stack region SR 1  may be disposed between the first and second isolation regions DR 1  and DR 2 , and the second stack region SR 2  may be disposed between the second and third isolation regions DR 2  and DR 3 . 
     The substrate  100  may be a single crystalline semiconductor substrate. For example, the substrate  100  may be a bulk silicon substrate, a silicon on insulator substrate, a germanium substrate, a germanium on insulator substrate, a silicon-germanium substrate, or an epitaxial thin film formed through a selective epitaxial growth process. 
     A source structure SL may be provided on the first and second stack regions SR 1  and SR 2  and the second isolation region DR 2 . The source structure SL may include a conductive material. In an example, the source structure SL may include poly-silicon. 
     Although not shown in the drawings, a peripheral circuit structure and a connection structure may be provided between the source structure SL and the substrate  100 . The peripheral circuit structure may include NMOS transistors, PMOS transistors, a resistor, and a capacitor. The NMOS transistors, the PMOS transistors, the resistor, and the capacitor may be used as elements constituting a row decoder, a column decoder, a page buffer circuit, and an input/output circuit. The connection structure may include a contact plug and a line. 
     In an example, as shown in the drawings, the source structure SL may include first to third source layers SL 1 , SL 2 , and SL 3 . In another example, unlike as shown in the drawings, the source structure SL may be configured in a single layer. Hereinafter, although a case where the source structure SL includes the first to third source layers SL 1 , SL 2 , and SL 3  is described as an example, the structure of the source structure SL may not be limited thereto. 
     The first source layer SL 1  may have the shape of a plate expanding along a plane defined by the first direction D 1  and the second direction D 2 . 
     The second source layers SL 2  may be provided on the first source layer SL 1 . The second source layers SL 2  may have the shape of a plate expanding along a plane defined by the first direction D 1  and the second direction D 2 . Each of the second source layers SL 2  may be provided on the first stack region SR 1  or the second stack region SR 2 . 
     The third source layers SL 3  may be provided on the second source layers SL 2 , respectively. The third source layers SL 3  may have the shape of a plate expanding along a plane defined by the first direction D 1  and the second direction D 2 . 
     A first slit structure SS 1  may be provided on the first isolation region DR 1 , a second slit structure SS 2  may be provided on the second isolation region DR 2 , and a third slit structure SS 3  may be provided on the third isolation region DR 3 . The first to third slit structures SS 1 , SS 2 , and SS 3  may extend in the second direction D 2  and the third direction D 3 . The first to third slit structures SS 1 , SS 2 , and SS 3  may be in contact with the source structure SL. The second and third source layers SL 2  and SL 3  may be provided between the first and second slit structures SS 1  and SS 2 . The second and third source layers SL 2  and SL 3  may be provided between the second and third slit structures SS 2  and SS 3 . 
     At least one of the first to third slit structures SS 1 , SS 2 , and SS 3  may include an insulating material. In an example, the insulating material may include silicon oxide. At least one of the first to third slit structures SS 1 , SS 2 , and SS 3  may include a common source line and source insulating layers. The source insulating layers may be spaced apart from each other in the first direction D 1  with the common source line interposed therebetween. The source insulating layers may electrically isolate the common source line from conductive patterns CP which will be described later. The common source line may be in contact with the first source layer SL 1  and the second source layer SL 2 . The common source line may include a conductive material. In an example, the common source line may include at least one of tungsten and doped poly-silicon. In an example, the source insulating layers may include silicon oxide. 
     A first stack structure SST 1  may be provided on the first stack region SR 1 , and a second stack structure SST 2  may be provided on the second stack region SR 2 . The first stack structure SST 1  may be provided between the first and second slit structures SS 1  and SS 2 , and the second stack structure SST 2  may be provided between the second and third slit structures SS 2  and SS 3 . The first and second stack structures SST 1  and SST 2  may be spaced apart from each other in the first direction D 1  by the second slit structure SS 2 . In other words, the first and second stack structures SST 1  and SST 2  may be isolated from each other by the second slit structure SS 2 . The first and second slit structures SS 1  and SS 2  may be spaced apart from each other in the first direction D 1  with the first stack structure SST 1  interposed therebetween. The second and third slit structures  552  and SS 3  may be spaced apart from each other in the first direction D 1  with the second stack structure SST 2  interposed therebetween. 
     The first to third slit structures SS 1 , SS 2 , and SS 3  and the first and second stack structures SST 1  and SST 2  may constitute one memory block MB. An erase operation of the semiconductor memory device may be performed in a unit of the memory block MB. 
     Each of the first and second stack structures SST 1  and SST 2  may include first to fifth insulating patterns IP 1 , IP 2 , IP 3 , IP 4 , and IP 5  and the conductive patterns CP. 
     In each of the first and second stack structures SST 1  and SST 2 , the first to fifth insulating patterns IP 1 , IP 2 , IP 3 , IP 4 , and IP 5  may be sequentially arranged to be space apart from each other along the third direction D 3 . Among the first to fifth insulating patterns IP 1 , IP 2 , IP 3 , IP 4 , and IP 5 , the first insulating patterns IP 1  may be arranged along the third direction D 3  from a lowermost portion to an intermediate portion of the first stack structure SST 1  or the second stack structure SST 2 , and the fifth insulating patterns IP 5  may be disposed at an uppermost portion of the first stack structure SST 1  or the second stack structure SST 2 . The second to fourth insulating patterns IP 2 , IP 3 , and IP 4  may be disposed between the first and fifth insulating patterns IP 1  and IP 5 . The first insulating patterns IP 1  may be disposed under the second insulating pattern IP 2 , the third insulating patterns IP 3  may be disposed above the second insulating pattern IP 2 , and the fourth insulating patterns IP 4  may be disposed above the third insulating patterns IP 3 . The first insulating patterns IP 1  may be disposed between the second insulating pattern IP 2  and the substrate  100  or between the second insulating pattern IP 2  and the source structure SL. 
     The conductive patterns CP may be alternately stacked with the first to fifth insulating patterns IP 1 , IP 2 , IP 3 , IP 4 , and IP 5 . 
     In an example, the first to fifth insulating patterns IP 1 , IP 2 , IP 3 , IP 4 , and IP 5  may include silicon oxide. The conductive patterns CP may include a gate conductive layer. In an example, the gate conductive layer may include at least one of a doped silicon layer; a metal silicide layer, tungsten, nickel, and cobalt, and be used as a word line connected to a memory cell or a select line connected to a select transistor. The conductive patterns CP may further include a gate barrier layer surrounding the gate conductive layer. In an example, the gate barrier layer may include at least one of titanium nitride and tantalum nitride. 
     Gate isolation layers DL penetrating an upper portion of the first stack structure SST 1  or the second stack structure SST 2  may be provided. The gate isolation layers DL may penetrate some of the first to fifth insulating patterns IP 1 , IP 2 , IP 3 , IP 4 , and IP 5  and some of the conductive patterns CR The conductive patterns CP may include select lines SP 1 , SP 2 , SP 3 , and SP 4 , and include word lines. The select lines SP 1 , SP 2 , SP 3 , and SP 4  may be penetrated by the gate isolation layers DL. The word lines may not be penetrated by the gate isolation layers DL. 
     The gate isolation layers DL may be provided in the first stack structure SST 1  or the second stack structure SST 2 . The gate isolation layers DL may extend in the second direction D 2 . 
     A plurality of gate isolation layers DL may penetrate an upper portion of one stack structure SST 1  or SST 2 . In other words, the plurality of gate isolation layers DL may be disposed between the first and second slit structures SS 1  and SS 2  or between the second and third slit structures SS 2  and SS 3 . For example, the gate isolation layers DL penetrating the first stack structure SST 1  may include first to third gate isolation layers DL 1 , DL 2 , and DL 3 . The first to third gate isolation layers DL 1 , DL 2 , and DL 3  may be arranged to be spaced apart from each other in the first direction D 1 . The first to third gate isolation layers DL 1 , DL 2 , and DL 3  may be disposed between the first and second slit structures SS 1  and SS 2 . 
     The gate isolation layer DL may penetrate an upper portion of a channel structure CST which will be described later. In an example, the gate isolation layer DL may include silicon oxide. 
     A lowermost portion DL_L of the gate isolation layer DL may be in contact with the second insulating pattern IP 2 . The lowermost portion DL_L of the gate isolation layer DL may be located in the second insulating pattern IP 2 . A level of the lowermost portion DL_L of the gate isolation layer DL may be lower than that of an upper surface IP 2 _T of the second insulating pattern IP 2 , and be higher than that of a lower surface IP 2 _B of the second insulating pattern IP 2 . The lowermost portion DL_L of the gate isolation layer DL may be located between the upper surface IP 2 _T and the lower surface IP 2 _B of the second insulating pattern IP 2 . The second insulating pattern IP 2  may surround the lowermost portion DL_L of the gate isolation layer DL. 
     The level of the lowermost portion DL_L of the gate isolation layer DL may be higher than that of a lower surface SS 1 _B of the first slit structure  551 , and be higher than that of a lower surface SS 2 _B of the second slit structure SS 2 . 
     The gate isolation layer DL may isolate the third insulating patterns IP 3  from each other in the first direction D 1 , isolate the fourth insulating patterns IP 4  from each other in the first direction D 1 , and isolate the fifth insulating patterns IP 5  from each other in the first direction D 1 . The third insulating patterns IP 3  may be spaced apart from each other in the first direction D 1  with the gate isolation layer DL interposed therebetween. The fourth insulating patterns IP 4  may be spaced apart from each other in the first direction D 1  with the gate isolation layer DL interposed therebetween. The fifth insulating patterns IP 5  may be spaced apart from each other in the first direction D 1  with the gate isolation layer DL interposed therebetween. 
     The first insulating patterns IP 1  may be spaced apart from the gate isolation layer DL. The second to fifth insulating patterns IP 2  to IP 5  may be in contact with the gate isolation layer DL. 
     Some of the conductive patterns CP may be isolated from each other in the first direction D 1  by the gate isolation layers DL. The conductive patterns CP isolated from each other in the first direction D 1  by the gate isolation layers DL may be defined as first to fourth select lines SP 1 , SP 2 , SP 3 , and SM. 
     The first select line SP 1  may be disposed between the first slit structure SS 1  and the first gate isolation layer DL 1 , the second select line SP 2  may be disposed between the first gate isolation layer DL 1  and the second gate isolation layer DL 2 , the third select line SP 3  may be disposed between the second gate isolation layer DL 2  and the third gate isolation layer DL 3 , and the fourth select line SP 4  may be disposed between the third gate isolation layer DL 3  and the second slit structure SS 2 . 
     The first and second select lines SP 1  and SP 2  may be electrically isolated from each other by the first gate isolation layer DL 1 , the second and third select lines SP 2  and SP 3  may be electrically isolated from each other by the second gate isolation layer DL 2 , and the third and fourth select lines SP 3  and SP 4  may be electrically isolated from each other by the third gate isolation layer DL 3 . 
     A length of the first insulating pattern IP 1  in the third direction D 3  may be defined as a first length L 1 , a length of the second insulating pattern IP 2  in the third direction D 3  may be defined as a second length L 2 , a length of the third insulating pattern IP 3  in the third direction D 3  may be defined as a third length L 3 , a length of the fourth insulating pattern IP 4  in the third direction D 3  may be defined as a fourth length L 4 , and a length of the fifth insulating pattern IP 5  in the third direction D 3  may be defined as a fifth length L 5 . 
     The second to fourth lengths L 2 , L 3 , and L 4 , respectively, may be greater than the first length L 1 . The second to fourth lengths L 2 , L 3 , and L 4  may be the same. The fifth length L 5  may be greater than the second to fourth lengths L 2 , L 3 , and L 4 , respectively. 
     The second insulating pattern IP 2  may have a thickness thicker than that of the first insulating patterns IP 1 . The second to fourth lengths L 2 , L 3 , and L 4  may have the same thickness. The fifth insulating pattern IP 5  may have a thickness thicker than that of the second insulating pattern IP 2 . 
     Channel structures CST penetrating the first stack structure SST 1  or the second stack structure SST 2  may be provided. The channel structures CST may penetrate the first to fifth insulating patterns IP 1 , IP 2 , IP 3 , IP 4 , and IP 5  and the conductive patterns CR The channel structures CST may have the shape of a circular pillar. The channel structures CST may penetrate the second and third source layers SL 2  and SL 3 . The channel structures CS may extend in the third direction D 3 . A lowermost portion of each of the channel structures CST may be located in the first source layer SL 1 . 
     Each of the channel structures CST may be disposed between the first slit structure SS 1  and the first gate isolation layer DL 1 , between the first and second gate isolation layers DL 1  and DL 2 , between the second and third gate isolation layers DL 2  and DL 3 , or between the third gate isolation layer DL 3  and the second slit structure SS 2 . 
     Each of the channel structures CST may include a filling layer FL, a conductive pad PA on the filling layer FL, a channel layer CL surrounding the filling layer FL and the conductive pad PA, and a memory layer ML surrounding the channel layer CL. The filling layer FL and the channel layer CL may penetrate the second source layer SL 2 . The second source layer SL 2  may penetrate the memory layer ML and be in contact with a sidewall of the channel layer CL. The channel layer CL and the common source line may be electrically connected to each other by the second source layer SL 2 . 
     In an example, the filling layer FL may include silicon oxide. In an example, the channel layer CL may include doped poly-silicon or undoped poly-silicon. The memory layer ML may include a tunnel layer in contact with the channel layer CL, a storage layer surrounding the tunnel layer, and a blocking layer surrounding the storage layer. The tunnel layer may include oxide through which charges can tunnel. The storage layer may include a material in which charges can be trapped. The blocking layer may include a material capable of blocking movement of charges. In an example, the conductive pad PA may include doped poly-silicon. 
     As shown in the drawings, in these embodiments, the channel layer CL may have the shape of a cylinder. Unlike as shown in the drawings, in an embodiment apart from these embodiments, the channel layer CL may have the shape of a circular pillar. The filling layer FL may not be provided in the channel layer CL. 
     Although not shown in the drawings, bit lines extending in the first direction D 1  may be provided on the first and second stacks structures SST 1  and SST 2 . The bit lines may be electrically connected to the channel structures CST. 
     According to the structure described above, one memory block MB may include a plurality of slit structures SS 1 , SS 2 , and SS 3  and a plurality of stack structures SST 1  and SST 2 . One stack structure SST 1  or SST 2  may include a plurality of gate isolation layers DL. In addition, select lines SP 1 , SP 2 , SP 3 , and SP 4  located at the same level may be isolated from each other by the gate isolation layers DL. 
     In addition, the second to fourth insulating patterns IP 2 , IP 3 , and IP 4  may have thickness thicker than the first insulating pattern IP 1 . Thus, although the gate isolation layers DL are formed to a non-uniform depth due to a limitation in a process, the lowermost portions of the gate isolation layers DL can be located in the second insulating pattern IP 2 . Accordingly, a word line can be prevented from being damaged by the gate isolation DL, or the select lines SP 1 , SP 2 , SP 3 , and SP 4  can be prevented from not being isolated from each other. 
       FIG. 2A  is a sectional view of a semiconductor memory device in accordance with a second embodiment of the present disclosure.  FIG. 2B  is an enlarged view of region C shown in  FIG. 2A . 
     The semiconductor memory device in accordance with these embodiments may be similar to the semiconductor memory devices shown in  FIGS. 1A to 1C , except portions described below. 
     Referring to  FIGS. 2A and 2B , each of a first stack structure SST 1  and a second stack structure SST 2  of the semiconductor memory device in accordance with these embodiments may include first to fifth insulating patterns IP 1 , IP 2 , IP 3 , IP 4 , and IP 5 . 
     A length of the first insulating pattern IP 1  in a vertical direction (i.e., a third direction D 3 ) may be defined as a sixth length L 6 , a length of the second insulating pattern IP 2  in the vertical direction may be defined as a seventh length L 7 , a length of the third insulating pattern IP 3  in the vertical direction may be defined as an eighth length L 8 , a length of the fourth insulating pattern IP 4  in the vertical direction may be defined as a ninth length L 9 , and a length of the fifth insulating pattern IP 5  in the vertical direction may be defined as a tenth length L 10 . 
     The seventh length L 7  may be greater than the sixth length L 6 . The seventh length L 7  may be greater than the eighth and ninth lengths L 8  and L 9 , respectively. The sixth, eighth, and ninth lengths L 6 , L 8 , and L 9  may be the same. The tenth length L 10  may be greater than the seventh length L 7 . 
     The second insulating pattern IP 2  may have a thickness thicker than those of the third and fourth insulating patterns IP 3  and IP 4 . The third and fourth insulating patterns IP 3  and IP 4  may have thicknesses equal to those of the first insulating patterns IP. 
     According to the structures described above, the second insulating pattern IP 2  may have a thickness thicker than those of the first insulating pattern IP 1  and the third and fourth insulating patterns IP 3  and IP 4 . The thickness of the fifth insulating pattern IP 5  may be greater than the second insulating pattern IP 2 . Thus, although the gate isolation layers DL are formed to a non-uniform depth due to a limitation in a process, lowermost portions of the gate isolation layers DL can be located in the second insulating pattern IP 2 . Further, the thickness of the second insulating pattern IP 2  is selectively increased, so that an increase in height of the stack structures SST 1  and SST 2  can be minimized. 
       FIGS. 3A to 3E  are sectional views illustrating a manufacturing method of the semiconductor memory device in accordance with the first embodiment of the present disclosure. 
     For convenience of description, components identical to those described with reference to  FIGS. 1A to 1C  are designated by like reference numerals, and overlapping descriptions will be omitted. 
     The manufacturing method described below is merely one embodiment of the manufacturing method of the semiconductor memory device shown in  FIGS. 1A to 1C , and the manufacturing method of the semiconductor memory device shown in  FIGS. 1A to 1C  may not be limited to that described below. 
     Referring to  FIG. 3A , a source structure SL may be formed on a substrate  100 . The source structure SL may include a first source layer SL 1 , a source sacrificial layer SFL, and a third source layer SL 3 . 
     The first source layer SL 1  may be formed on the substrate  100 , the source sacrificial layer SFL may be formed on the first source layer SL 1 , and the third source layer SL 3  may be formed on the source sacrificial layer SFL. In an example, the source sacrificial layer SFL may include a poly-silicon layer and a silicon oxide layer. 
     Subsequently, a stack structure SST may be formed on the source structure SL. The stack structure SST may be formed by alternately stacking first to fifth insulating patterns IP 1 , IP 2 , IP 3 , IP 4 , and IP 5  and sacrificial patterns FR The second insulating pattern IP 2  may have a thickness thicker than those of the first insulating patterns IP 1 . The third and fourth insulating patterns IP 3  and IP 4  may respectively have thicknesses thicker than that of the second insulating pattern IP 2 . The fifth insulating pattern IP 5  may have a thickness thicker than those of the second to fourth insulating patterns IP 2 , IP 3 , and IP 4 , respectively. In an example, the sacrificial patterns FP may include silicon nitride. 
     Channel structures CST may be formed, which penetrate the first to fifth insulating patterns IP 1 , IP 2 , IP 3 , IP 4 , and IP 5 , the sacrificial patterns FP, the source sacrificial layer SFL, and the third source layer SL 3 . The process of forming the channel structures CST may include a process of forming holes penetrating the first to fifth insulating patterns IP 1 , IP 2 , IP 3 , IP 4 , and IP 5 , the sacrificial patterns FP, the source sacrificial layer SFL, and the third source layer SL 3  and a process of sequentially filling the holes with a memory layer ML, a channel layer CL, a filling layer FL, and a conductive pad PA. 
     Referring to  FIG. 3B , a first trench TR 1  and a second trench TR 2  may be formed, which extend in a second direction D 2 . The first trench TR 1  may be formed on a first isolation layer DR 1 , and the second trench TR 2  may be formed on a second isolation layer DR 2 . 
     The first and second trenches TR 1  and TR 2  may penetrate the stack structure SST. The stack structure SST may be isolated into first and second stack structures SST 1  and SST 2  by the first and second trenches TR 1  and TR 2 . The first stack structure SST 1  may be provided between the first and second trenches TR 1  and TR 2 . The first and second trenches TR 1  and TR 2  may penetrate the first to fifth insulating patterns IP 1 , IP 2 , IP 3 , IP 4 , and IP 5  and the sacrificial patterns FP. 
     The source structure SL may be exposed by the first and second trenches TR 1  and TR 2 . The source sacrificial layer SFL may be replaced with a second source layer SL 2  through the first and second trenches TR 1  and TR 2 . For example, after the channel layer CL is exposed by removing the source sacrificial layer SFL and etching the memory layer ML, the second source layer SL 2  may be formed. The second source layer SL 2  may penetrate the memory layer ML and be in contact with the channel layer CL. 
     The sacrificial patterns FP exposed through the first and second trenches TR 1  and TR 2  may be removed. An echant may be introduced into the stack structures SST 1  and SST 2  through the first and second trenches TR 1  and TR 2 , and the sacrificial patterns FP may be removed. When the sacrificial patterns FP are removed, empty spaces AS may be formed between the first to fifth insulating patterns IP 1 , IP 2 , IP 3 , IP 4 , and IP 5 . Since the sacrificial patterns FP are removed before a gate isolation layer DL is formed, the empty spaces AS may be formed up to the inside of the stack structures SST 1  and SST 2 . 
     Referring to  FIG. 3C , the empty spaces AS between the first to fifth insulating patterns IP 1 , IP 2 , IP 3 , IP 4 , and IP 5  may be filled with conductive patterns CP. The sacrificial patterns FP between the first to fifth insulating patterns IP 1 , IP 2 , IP 3 , IP 4 , and IP 5  may be replaced with the conductive patterns CP through the first and second trenches TR 1  and TR 2 . Subsequently, a first slit structure SS 1  may be formed in the first trench TR 1 , and a second slit structure SS 2  may be formed in the second trench TR 2 . 
     Referring to  FIG. 3D , a plurality of third trenches TR 3  penetrating upper portions of the first and second stack structures SST 1  and SST 2  may be formed. The plurality of third trenches TR 3  may be formed between the first and second trenches TR 1  and TR 2 . The plurality of third trenches TR 3  may be formed between the first and second slit structures SS 1  and SS 2 . 
     The third trenches TR 3  may extend in the second direction D 2 . The third trenches TR 3  may penetrate some of the conductive patterns CP, the third insulating pattern IP 3 , the fourth insulating pattern IP 4 , and the fifth insulating pattern IP 5 . Each of the third to fifth insulating patterns IP 3 , IP 4 , and IP 5  may be isolated into a plurality of insulating patterns by the third trenches TR 3 . Each of the conductive patterns CP between the second to fifth insulating patterns IP 2 , IP 3 , IP 4 , and IP 5  may be isolated into a plurality of insulating patterns by the third trenches. 
     The third trench TR 3  may penetrate upper portions of some of the channel structures CST. A bottom surface of the third trench TR 3  may be located in the second insulating pattern IP 2 . The bottom surface of the third trench TR 3  may have a level higher than those of a bottom surface TR 1 _B of the first trench TR 1  and a bottom surface TR 2 _B of the second trench TR 2 . 
     The process of forming the third trenches TR 3  may include a process of forming a mask pattern MP including an opening on the first and second stack structures SST 1  and SST 2  and a process of patterning the first and second stack structures SST 1  and SST 2  through the opening. After the first and second stack structures SST 1  and SST 2  are patterned, the remaining mask pattern MP may be removed. 
     Referring to  FIG. 3E , gate isolation layers DL may be formed in the third trenches TR 3 . Select lines SP 1 , SP 2 , SP 3 , and SP 4  located at the same level may be isolated from each other by the gate isolation layers DL. Lowermost portions DL_L of the gate isolation layers DL may be located in the second insulating pattern IP 2 . 
     In accordance with the manufacturing method described above, a plurality of gate isolation layers DL are formed in one stack structure SST 1  or SST 2 . Therefore, an isolated region IR exists between adjacent gate isolation layers DL. When gate isolation layers DL are formed before the sacrificial patterns FP are replaced with the conductive patterns CP, sacrificial patterns FP between the gate isolation layers DL are isolated. The etchant introduced through the first trench TR 1  and the second trench TR 2  cannot reach the isolated sacrificial patterns FP, and the isolated sacrificial pattern FP cannot be replaced with the conductive patterns CR Therefore, the select lines SP 1 , SP 2 , SP 3 , and SP 4  cannot be formed between the gate isolation layers DL. On the other hand, in accordance with these embodiments of the present disclosure, the gate isolation layers DL are formed after the sacrificial patterns FP are replaced with the conductive patterns CP, thereby solving this problem. 
     Meanwhile, since the gate isolation layers DL are formed after the sacrificial patterns FP are replaced with the conductive patterns CP, the third trench TR 3  is formed by repeatedly etching the conductive patterns CP and the second to fifth insulating patterns IP 2 , IP 3 , IP 4 , and IP 5 . However, an etch selectivity between the conductive patterns CP including tungsten, etc. and the second to fifth insulating patterns IP 2 , IP 3 , IP 4 , and IP 5  including oxide, etc. is small, and hence it is difficult to control the depth of the third trench TR 3 . Thus, in accordance with these embodiments of the present disclosure, the thickness of the second insulating pattern IP 2  located at an etch stop level is increased. Accordingly, the thickness of a specific insulating pattern is increased, so that an etch margin can be secured without changing any process condition. Further, the third trenches TR 3  can be prevented from being formed to a sufficient depth, or conductive patterns under the third trenches TR 3  can be prevented from being damaged as the third trenches TR 3  penetrate the second insulating pattern IP 2 . 
       FIG. 4  is a block diagram illustrating a configuration of a memory system in accordance with an embodiment of the present disclosure. 
     Referring to  FIG. 4 , the memory system  1100  in accordance with the embodiments of the present disclosure includes a memory device  1120  and a memory controller  1110 . 
     The memory device  1120  may include the structures described with reference to  FIGS. 1A to 1C or 2A and 2B . The memory device  1120  may be a multi-chip package configured with a plurality of flash memory chips. 
     The memory controller  1110  is configured to control the memory device  1120 , and may include a Static Random Access Memory (SRAM)  1111 , a Central Processing Unit (CPU)  1112 , a host interface  1113 , an Error Correction Code (ECC) circuit  1114 , and a memory interface  1115 . The SRAM  1111  is used as an operation memory of the CPU  1112 , the CPU  1112  performs overall control operations for data exchange of the memory controller  1110 , and the host interface  1113  includes a data exchange protocol for a host connected with the memory system  1100 . The ECC circuit  1114  detects and corrects an error included in a data read from the memory device  1120 , and the memory interface  1115  interfaces with the memory device  1120 . In addition, the memory controller  1110  may further include an ROM for storing code data for interfacing with the host, and the like. 
     The memory system  1100  configured as described above may be a memory card or a Solid State Disk (SSD), in which the memory device  1120  is combined with the controller  1110 . For example, when the memory system  1100  is an SSD, the memory controller  1100  may communicated with the outside (e.g., the host) through one among various interface protocols, such as a Universal Serial Bus (USB) protocol, a Multi-Media Card (MMC) protocol, a Peripheral Component Interconnection (PCI) protocol, a PCI-Express (PCI-E) protocol, an Advanced Technology Attachment (ATA) protocol, a Serial-ATA (SATA) protocol, a Parallel-ATA (DATA) protocol, a Small Computer Small Interface (SCSI) protocol, an Enhanced Small Disk Interface (ESDI) protocol, and an Integrated Drive Electronics (IDE) protocol. 
       FIG. 5  is a block diagram illustrating a configuration of a computing system in accordance with an embodiment of the present disclosure. 
     Referring to  FIG. 5 , the computing system  1200  in accordance with the embodiments of the present disclosure may include a CPU  1220 , a random access memory (RAM)  1230 , a user interface  1240 , a modem  1250 , and a memory system  1210 , which are electrically connected to a system bus  1260 . When the computing system  1200  is a mobile device, a battery for supplying an operation voltage to the computing system  1200  may be further included, and an application chip set, a Camera Image Processor (CIS), a mobile D-RAM, and the like may be further included. 
     The memory system  1200  may be configured with a memory device  1212  and a memory controller  1211  as described with reference to  FIG. 4 . 
     In the semiconductor memory device in accordance with the present disclosure, a length of an insulating pattern surrounding a lowermost portion of a gate isolation layer in a vertical direction can be relatively large. Accordingly, the operational reliability of the semiconductor memory device can be improved. 
     While the present disclosure has been shown and described with reference to various embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present disclosure as defined by the appended claims and their equivalents. Therefore, the scope of the present disclosure should not be limited to the above-described embodiments but should be determined by not only the appended claims but also the equivalents thereof. 
     In the above-described embodiments, all steps may be selectively performed or part of the steps and may be omitted. In each embodiment, the steps are not necessarily performed in accordance with the described order and may be rearranged. The embodiments disclosed in this specification and drawings are only examples to facilitate an understanding of the present disclosure, and the present disclosure is not limited thereto. That is, it should be apparent to those skilled in the art that various modifications can be made on the basis of the technological scope of the present disclosure. 
     Meanwhile, the embodiments of the present disclosure have been described in the drawings and specification. Although specific terminologies are used here, those are only to explain the embodiments of the present disclosure. Therefore, the present disclosure is not restricted to the above-described embodiments and many variations are possible within the spirit and scope of the present disclosure. It should be apparent to those skilled in the art that various modifications can be made on the basis of the technological scope of the present disclosure in addition to the embodiments disclosed herein.