Patent Publication Number: US-2022230961-A1

Title: Stacked semiconductor device architecture and method of manufacturing the same

Description:
CROSS-REFERENCE TO THE RELATED APPLICATION 
     This application is based on and claims benefit to U.S. Provisional Application No. 63/138,596 filed on Jan. 18, 2021 in the U.S. Patent and Trademark Office, the disclosure of which is incorporated herein in its entirety by reference. 
    
    
     BACKGROUND 
     1. Field 
     Example embodiments of the present disclosure relate to a stacked semiconductor device architecture and a method of manufacturing the same, and more particularly to a stacked semiconductor device architecture including a power rail provided between the stacked semiconductor devices and a method of manufacturing the same. 
     2. Description of Related Art 
     Generally, a non-stacked semiconductor device architecture requires a large area due to a p-type metal-oxide semiconductor (PMOS) devices and an n-type metal-oxide semiconductor (NMOS) devices being provided on a same plane. In addition, in a non-stacked semiconductor device architecture, power rails connected to the PMOS device and the NMOS device are both provided above or below the PMOS device and the NMOS device. Technologies to reduce a total area of a semiconductor architecture have been developed. For example, stacked semiconductor device architecture in which a PMOS device and an NMOS device in a metal-oxide-semiconductor field-effect transistor (MOSFET) based cell are stacked in a vertical direction has been developed. 
     However, in a related stacked semiconductor device architecture, power rails are provided above the stacked PMOS device and NMOS device, or power rails are buried in a substrate that is provided below the stacked PMOS device and NMOS device. Accordingly, a height of a vertical contact that connects one of the PMOS device or the NMOS device that is provided at a vertical distance further away from the power rail increases. An increase in a height of the vertical contact increases a resistance of the power connection in the stacked semiconductor device architecture. Accordingly, a degradation in performance of the stacked semiconductor device architecture may occur. 
     Information disclosed in this Background section has already been known to the inventors before achieving the embodiments of the present application or is technical information acquired in the process of achieving the embodiments. Therefore, it may contain information that does not form the prior art that is already known to the public. 
     SUMMARY 
     One or more example embodiments provide a stacked semiconductor device architecture and a method of manufacturing the same. 
     One or more example embodiments also provide a stacked semiconductor device architecture including a power rail provided between the semiconductor devices, and a method of manufacturing the same. 
     According to an aspect of an example embodiment, there is provided a semiconductor architecture having a metal-oxide-semiconductor field-effect transistor (MOSFET) cell, the semiconductor architecture including a substrate, a first semiconductor device provided on the substrate, a second semiconductor device provided on the substrate, the second semiconductor device being provided below the first semiconductor device, a first power rail configured to supply power to the first semiconductor device, and a second power rail configured to supply power to the second semiconductor device, wherein the first semiconductor device and the second semiconductor device are included in the MOSFET cell, wherein at least one of the first power rail and the second power rail is provided at a vertical level between the first semiconductor device and the second semiconductor device. 
     According to another aspect of an example embodiment, there is provided a semiconductor architecture having a metal-oxide-semiconductor field-effect transistor (MOSFET) cell, the semiconductor architecture including a wafer, a p-type metal-oxide semiconductor (PMOS) device provided on the wafer, an n-type metal-oxide semiconductor (NMOS) device provided at a vertical level different from the PMOS device on the wafer, a first power rail configured to supply power to the PMOS device, and a second power rail configured to supply power to the NMOS device, wherein the PMOS device and the NMOS device are included in the MOSFET cell, and wherein at least one of the first power rail and the second power rail is provided at a vertical level between the PMOS device and the NMOS device. 
     According to another aspect of an example embodiment, there is provided a semiconductor architecture having a metal-oxide-semiconductor field-effect transistor (MOSFET) cell, the semiconductor architecture including a first semiconductor device included in the MOSFET cell, a second semiconductor device included in the MOSFET cell, the second semiconductor device being provided above the first semiconductor device, a first power rail configured to supply power to the first semiconductor device, the first power rail being provided a vertical level between the first semiconductor device and the second semiconductor device, and a second power rail configured to supply power to the second semiconductor device, the second power rail being provided at a vertical level different from the first semiconductor device and the second semiconductor device. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and/or other aspects, features, and advantages of example embodiments of the disclosure will be more apparent from the following description taken in conjunction with the accompanying drawings, in which: 
         FIGS. 1A and 1B  illustrate perspective views of general non-stacked semiconductor device architectures; 
         FIG. 2A  illustrates a cross-sectional view of the non-stacked semiconductor device architecture as illustrated in  FIG. 1A , and  FIG. 2B  illustrates a cross-sectional view of the non-stacked semiconductor device architecture as illustrated in  FIG. 1B ; 
         FIG. 3  illustrates a top plan view of the non-stacked semiconductor device architecture as illustrated in  FIG. 1A ; 
         FIGS. 4A and 4B  illustrate stacked semiconductor device architectures according to related embodiments; 
         FIG. 5A  is a cross-sectional view of the stacked semiconductor device architecture as illustrated in  FIG. 4A , and  FIG. 5B  is a cross-sectional view of the stacked semiconductor device architecture as illustrated in  FIG. 4B ; 
         FIG. 6A  is a top plan view of the stacked semiconductor device architecture as illustrated in  FIG. 4A , and  FIG. 6B  is a top plan view of the stacked semiconductor device architecture as illustrated in  FIG. 4B ; 
         FIG. 7  illustrates a stacked semiconductor device architecture according to an example embodiment; 
         FIG. 8A  is a cross-sectional view of the stacked semiconductor device architecture as illustrated in  FIG. 7 ; 
         FIG. 8B  illustrates a top plan view of the stacked semiconductor device architecture as illustrated in  FIG. 7 ; 
         FIG. 9  illustrates a stacked semiconductor device architecture according to another example embodiment; 
         FIG. 10A  is a cross-sectional view of the stacked semiconductor device architecture as illustrated in  FIG. 9 ; 
         FIG. 10B  illustrates a top plan view of the stacked semiconductor device architecture as illustrated in  FIG. 9 ; 
         FIG. 11  illustrates a perspective view of a stacked semiconductor device architecture according to example embodiments; 
         FIG. 12  illustrates a semiconductor device that may incorporate the stacked semiconductor device architectures according to example embodiments; and 
         FIG. 13  illustrates a schematic block diagram of an electronic system according to an example embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     The example embodiments described herein are examples, and thus, the present disclosure is not limited thereto, and may be realized in various other forms. Each of the example embodiments provided in the following description is not excluded from being associated with one or more features of another example or another example embodiment also provided herein or not provided herein but consistent with the present disclosure. For example, even if matters described in a specific example or example embodiment are not described in a different example or example embodiment thereto, the matters may be understood as being related to or combined with the different example or embodiment, unless otherwise mentioned in descriptions thereof. 
     In addition, it should be understood that all descriptions of principles, aspects, examples, and example embodiments are intended to encompass structural and functional equivalents thereof. In addition, these equivalents should be understood as including not only currently well-known equivalents but also equivalents to be developed in the future, that is, all devices invented to perform the same functions regardless of the structures thereof. 
     It will be understood that when an element, component, layer, pattern, structure, region, or so on (hereinafter collectively “element”) of a semiconductor device is referred to as being “over,” “above,” “on,” “below,” “under,” “beneath,” “connected to” or “coupled to” another element the semiconductor device, it can be directly over, above, on, below, under, beneath, connected or coupled to the other element or an intervening element(s) may be present. In contrast, when an element of a semiconductor device is referred to as being “directly over,” “directly above,” “directly on,” “directly below,” “directly under,” “directly beneath,” “directly connected to” or “directly coupled to” another element of the semiconductor device, there are no intervening elements present. Like numerals refer to like elements throughout this disclosure. 
     Spatially relative terms, such as “over,” “above,” “on,” “upper,” “below,” “under,” “beneath,” “lower,” “top,” and “bottom,” and the like, may be used herein for ease of description to describe one element&#39;s relationship to another element(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of a semiconductor device in use or operation in addition to the orientation depicted in the figures. For example, if the semiconductor device in the figures is turned over, elements described as “below” or “beneath” other elements would then be oriented “above” the other elements. Thus, the term “below” can encompass both an orientation of above and below. The semiconductor device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly. 
     As used herein, expressions such as “at least one of,” when preceding a list of elements, modify the entire list of elements and do not modify the individual elements of the list. For example, the expression, “at least one of a, b, and c,” should be understood as including only a, only b, only c, both a and b, both a and c, both b and c, or all of a, b, and c. Herein, when a term “same” is used to compare a dimension of two or more elements, the term may cover a “substantially same” dimension. 
     It will be understood that, although the terms “first,” “second,” “third,” “fourth,” etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. Thus, a first element discussed below could be termed a second element without departing from the teachings of the present disclosure. 
     It will be also understood that, even if a certain step or operation of manufacturing an apparatus or structure is described later than another step or operation, the step or operation may be performed later than the other step or operation unless the other step or operation is described as being performed after the step or operation. 
     Example embodiments are described herein with reference to cross-sectional illustrations that are schematic illustrations of the example embodiments (and intermediate structures). As such, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances, are to be expected. Thus, the example embodiments should not be construed as limited to the particular shapes of regions illustrated herein but are to include deviations in shapes that result, for example, from manufacturing. For example, an implanted region illustrated as a rectangle will, typically, have rounded or curved features and/or a gradient of implant concentration at its edges rather than a binary change from implanted to non-implanted region. Likewise, a buried region formed by implantation may result in some implantation in the region between the buried region and the surface through which the implantation takes place. Thus, the regions illustrated in the figures are schematic in nature and their shapes are not intended to illustrate the actual shape of a region of a device and are not intended to limit the scope of the present disclosure. Further, in the drawings, the sizes and relative sizes of layers and regions may be exaggerated for clarity. 
     For the sake of brevity, general elements to semiconductor devices may or may not be described in detail herein. 
       FIGS. 1A and 1B  illustrate perspective views of general non-stacked semiconductor device architectures. 
     Referring to  FIG. 1A , a non-stacked semiconductor architecture  1000  may include a metal-oxide-semiconductor field-effect transistor (MOSFET) based cell including a PMOS device  1120   a  and an NMOS device  1120   b  provided on a same plane of a substrate  1100 . The substrate  1100  may be a wafer including silicon (Si). A horizontal interconnect  1112   a  may be connected to the PMOS  1120   a . The horizontal interconnect  1112   a  may be connected to an epitaxial layer of the PMOS  1120   a . A top vertical contact  1111   a  may be provided on the horizontal interconnect  1112   a  and extend upwards. A top power rail  1131   a  configured to supply power to the PMOS  1120   a  may be provided on the top vertical contact  1111   a . The top power rail  1131   a  may be provided above the PMOS  1120   a  in a vertical direction and spaced apart from the PMOS  1120   a  in a horizontal direction. 
     Similarly, a horizontal interconnect  1112   b  is connected to the NMOS  1120   b . The horizontal interconnect  1112   b  may be connected to an epitaxial layer of the NMOS  1120   b . A top vertical contact  1111   b  may be provided on the horizontal interconnect  1112   b  and extend upwards. Another top power rail  1131   b  configured supply power to the NMOS  1120   b  may be provided on the top vertical contact  1111   b . The top power rail  1131   b  may be provided above the NMOS  1120   b  in a vertical direction and spaced apart from the NMOS  1120   b  in a horizontal direction. 
     Referring to  FIG. 1B , a non-stacked semiconductor architecture  1000 ′ may include a MOSFET cell including a PMOS  1120   a  and an NMOS  1120   b  provided on a same plane of a substrate  1100 . A horizontal interconnect  1112   a  may be connected to the PMOS  1120   a . The horizontal interconnect  1112   a  may be connected to an epitaxial layer of the PMOS  1120   a . A bottom vertical contact  1110   a  may be provided on the horizontal interconnect  1112   a  and extend downwards. A bottom power rail  1132   a  configured to supply power to the PMOS  1120   a  may be provided on the bottom vertical contact  1110   a . The bottom power rail  1132   a  may be provided below the PMOS  1120   a  in a vertical direction and spaced apart from the PMOS  1120   a  in a horizontal direction. 
     Similarly, a horizontal interconnect  1112   b  is connected to the NMOS  1120   b . The horizontal interconnect  1112   b  may be connected to an epitaxial layer of the NMOS  1120   b . A bottom vertical contact  1110   b  may be provided on the horizontal interconnect  1112   b  and extend downwards. Another bottom power rail  1132   b  configured to supply power to the NMOS  1120   b  may be provided on the bottom vertical contact  1110   b . The bottom power rail  1132   b  may be provided below the NMOS  1120   b  in a vertical direction and spaced apart from the NMOS  1120   b  in a horizontal direction. 
       FIG. 2A  illustrates a cross-sectional view of the non-stacked semiconductor device architecture as illustrated in  FIG. 1A , and  FIG. 2B  illustrates a non-stacked semiconductor device architecture as illustrated in  FIG. 1B . 
     Referring to  FIG. 2A , in the MOSFET cell, a PMOS  1120   a  and an NMOS  1120   b  are provided on a same plane of a substrate  1100 . Horizontal interconnects  1112   a  and  1112   b  are connected to an epitaxial layer of the PMOS  1120   a  and an epitaxial layer of the NMOS  1120   b , respectively. The horizontal interconnects  1112   a  and  1112   b  may extend in a horizontal direction away from the PMOS  1120   a  and the NMOS  1120   b . Top vertical contacts  1111   a  and  1111   b  are provided on the horizontal interconnects  1112   a  and  1112   b , respectively, and top power rails  1131   a  and  1131   b  are provided on the top vertical contacts  1111   a  and  1111   b  at a vertical level above the PMOS  1120   a  and the NMOS  1120   b . In addition, metal layers  1140  configured to route signals may be provided between the top power rails  1131   a  and  1131   b  on a same vertical level as the top power rails  1131   a  and  1131   b.    
     Referring to  FIG. 2B , in the MOSFET cell, a PMOS  1120   a  and an NMOS  1120   b  are provided on a same plane of a substrate  1100 . Horizontal interconnects  1112   a  and  1112   b  are connected to an epitaxial layer of the PMOS  1120   a  and an epitaxial layer of the NMOS  1120   b , respectively. The horizontal interconnects  1112   a  and  1112   b  may extend in a horizontal direction away from the PMOS  1120   a  and the NMOS  1120   b . Bottom vertical contacts  1110   a  and  1110   b  may be provided on the horizontal interconnects  1112   a  and  1112   b , respectively, and extend downwards. Bottom power rails  1132   a  and  1132   b  are provided on a lower surface of the bottom vertical contacts  1110   a  and  1110   b , respectively, at a vertical level below the PMOS  1120   a  and the NMOS  1120   b . In addition, metal layers  1140  configured to route signals may be provided above the PMOS  1120   a  and the NMOS  1120   b  in a vertical direction. 
     As illustrated in  FIGS. 2A and 2B , as the PMOS  1120   a  and the NMOS  1120   b  are provided on a same plane, a total area of the non-stacked semiconductor device architectures  1000  and  1000 ′ may be relatively large in a horizontal direction, resulting in an increased area and size of the non-stacked semiconductor device architectures  1000  and  1000 ′. 
       FIG. 3  illustrates a top plan view of the non-stack semiconductor device architecture as illustrated in  FIG. 1A . 
     Referring to  FIG. 3 , a width W 1  of the MOSFET cell of the non-stack semiconductor device architecture is relatively large because the PMOS  120   a  and NMOS  120   b  are provided on a same plane. Thus, a size of the non-stack semiconductor device architecture may increase. 
       FIGS. 4A and 4B  illustrate stacked semiconductor device architectures according to related embodiments. 
     Referring to  FIG. 4A , a stacked semiconductor device architecture  2000  according to a related embodiment includes a MOSFET cell including a PMOS  2120   a  provided on a first level of a substrate  2100  and an NMOS  2120   b  provided below the PMOS  2120   a  on a second level of the substrate  2100 . The NMOS  2120   b  may be provided on a first level of a substrate  2100  and the PMOS  2120   a  may be provided below the NMOS  2120   b  on a second level of the substrate  2100 . A horizontal interconnect  2112   a  is connected to the PMOS  2120   a . The horizontal interconnect  2112   a  may be connected to an epitaxial layer of the PMOS  2120   a . A top vertical contact  2111   a  may be provided on the horizontal interconnect  2112   a  and extend upwards to a vertical level above the PMOS  2120   a . A top power rail  2131   a  configured to supply power to the PMOS  2120   a  is provided on an upper surface of the top vertical contact  2111   a . The top power rail  2131   a  may be provided above the PMOS  2120   a  and the NMOS  2120   b  in a vertical direction. 
     The NMOS  2120   b  is connected to a horizontal interconnect  2112   b . The horizontal interconnect  2112   b  may be connected to an epitaxial layer of the NMOS  2120   b . A top vertical contact  2111   b  is connected to the horizontal interconnect  2112   b . A top power rail  2131   b  is provided on an upper surface of the top vertical contact  2111   b  above the PMOS  2120   a  and the NMOS  2120   b  in a vertical direction. 
     As illustrated in  FIG. 4A , a height of the top vertical contact  2111   b  is increased compared to top vertical contacts  1111   a  and  1111   b  and bottom vertical contacts  1110   a  and  1110   b  as illustrated in  FIGS. 1A and 1B , which increases an aspect ratio of the top vertical contact  2111   b . Accordingly, a resistance may increase which may lead to a degradation in the performance of the stacked semiconductor device architecture  2000 . 
     Referring to  FIG. 4B , a stacked semiconductor device architecture  2000 ′ according to another related embodiment includes a MOSFET cell including a PMOS  2120   a  provided on a first level of a substrate  2100  and an NMOS  2120   b  is provided below the PMOS  2120   a  on a second level of the substrate  2100 . A horizontal interconnect  2112   a  is connected to the PMOS  2120   a . The horizontal interconnect  2112   a  may be connected to an epitaxial layer of the PMOS  2120   a . A bottom vertical contact  2110   a  is provided on the horizontal interconnect  2112   a  and extends downwards to a vertical level below the NMOS  2120   b . A bottom power rail  2132   a  configured to supply power to the PMOS  2120   a  is provided on a lower surface of the bottom vertical contact  2110   a . The bottom power rail  2132   a  may be provided at a vertical level below the PMOS  2120   a  and the NMOS  2120   b . The bottom power rail  2132   a  may be a buried power rail that is buried in the substrate  2100 . 
     The NMOS  2120   b  is connected to a horizontal interconnect  2112   b . The horizontal interconnect  2112   b  may be connected to an epitaxial layer of the NMOS  2120   b . A bottom vertical contact  2110   b  is connected to the horizontal interconnect  2112   b  and extends downwards. A bottom power rail  2132   b  is provided on a lower surface of the bottom vertical contact  2110   b . The bottom power rail  2132   b  may be provided at a vertical level below the PMOS  2120   a  and the NMOS  2120   b . The bottom power rail  2132   b  may be a buried power rail that is buried in the substrate  2100 . 
     As illustrated in  FIG. 4B , a height of the bottom vertical contact  2110   a  is increased compared to the top vertical contacts  1111   a  and  1111   b  and bottom vertical contacts  1110   a  and  1110   b  as illustrated in  FIGS. 1A and 1B . Accordingly, an aspect ratio of the bottom vertical contact  2110   a  may increase and a resistance may increase leading to a degradation in the performance of the stacked semiconductor device architecture  2000 ′. 
       FIG. 5A  is a cross-sectional view of the stacked semiconductor device architecture as illustrated in  FIG. 4A , and  FIG. 5B  is a cross-sectional view of the stacked semiconductor device architecture as illustrated in  FIG. 4B . 
     Referring to  FIG. 5A , a PMOS  2120   a  is provided on a first level of a substrate  2100  and an NMOS  2120   b  is provided below the PMOS  2120   a  on a second level of the substrate  2100 . Dielectric material  2101  may be included between the PMOS  2120   a  and the NMOS  2120   b . A horizontal interconnect  2112   a  is connected to the PMOS  2120   a . The horizontal interconnect  2112   a  may be connected to an epitaxial layer of the PMOS  2120   a . A top vertical contact  2111   a  is provided on the horizontal interconnect  2112   a  and extends upwards to a vertical level above the PMOS  2120   a . A top power rail  2131   a  configured to supply power to the PMOS  2120   a  is provided on an upper surface of the top vertical contact  2111   a . The top power rail  2131   a  is provided at a vertical level above the PMOS  2120   a  and the NMOS  2120   b.    
     The NMOS  2120   b  is connected to a horizontal interconnect  2112   b . The horizontal interconnect  2112   b  may be connected to an epitaxial layer of the NMOS  2120   b . A top vertical contact  2111   b  is provided on the horizontal interconnect  2112   b . A top power rail  2131   b  is provided on an upper surface of the top vertical contact  2111   b  at a vertical level above the PMOS  2120   a  and at a vertical level same as an adjacent top power rail  2131   a.    
     In addition, metal layers  2140  configured to route signals may be provided between the adjacent top power rails  2131   a  and  2131   b  at a same vertical level. 
     As illustrated in  FIG. 5A , a height of the top vertical contact  2111   b  is increased compared to top vertical contacts  1111   a  and  1111   b  and bottom vertical contacts  1110   a  and  1110   b  illustrated in  FIGS. 2A and 2B . Accordingly, an aspect ratio of the top vertical contact  2111   b  may increase and a resistance may increase leading to a degradation in the performance of the stacked semiconductor device architecture  2000 . 
     Referring to  FIG. 5B , stacked semiconductor device architecture  2000 ′ includes a PMOS  2120   a  is provided on a first level of a substrate  2100  and an NMOS  2120   b  is provided below the PMOS  2120   a  on a second level of the substrate  2100 . Dielectric material  2101  may be included between the PMOS  2120   a  and the NMOS  2120   b . A horizontal interconnect  2112   a  is connected to the PMOS  2120   a . The horizontal interconnect  2112   a  may be connected to an epitaxial layer of the PMOS  2120   a . A bottom vertical contact  2110   a  is provided on the horizontal interconnect  2112   a  and extends downwards to a vertical level below the NMOS  2120   b . A bottom power rail  2132   a  configured to supply power to the PMOS  2120   a  is provided on a lower surface of the bottom vertical contact  2110   a . The bottom power rail  2132   a  is provided at a vertical level below the PMOS  2120   a  and the NMOS  2120   b.    
     The NMOS  2120   b  is connected to a horizontal interconnect  2112   b . The horizontal interconnect  2112   b  may be connected to an epitaxial layer of the NMOS  2120   b . A bottom vertical contact  2110   b  is connected to the horizontal interconnect  2112   b  and extends downwards. A bottom power rail  2132   b  is provided on a lower surface of the bottom vertical contact  2110   b . The bottom power rail  2132   b  is provided at a vertical level below the PMOS  2120   a  and the NMOS  2120   b.    
     In addition, metal layers  2140  configured to route signals may be provided above the PMOS  2120   a  and the NMOS  2120   b.    
     As illustrated in  FIG. 5B , a height of the bottom vertical contact  2110   a  is increased compared to top vertical contacts  1111   a  and  1111   b  and bottom vertical contacts  1110   a  and  1110   b  as illustrated in  FIGS. 2A and 2B . Accordingly, an aspect ratio of the bottom vertical contact  2110   a  may increase and a resistance may increase leading to a degradation in the performance of the stacked semiconductor device architecture  2000 ′. 
       FIG. 6A  is a top plan view of the stacked semiconductor device architecture as illustrated in  FIG. 4A , and  FIG. 6B  is a top plan view of the stacked semiconductor device architecture as illustrated in  FIG. 4B . 
     As illustrated in  FIGS. 6A and 6B , as the PMOS  120   a  and the NMOS  120   b  are stacked in a vertical direction to overlap with each other, the width W 2  of the MOSFET cell in the stacked semiconductor device architectures  2000  and  2000 ′ may be reduced compared to the width W 1  of a MOSFET cell in the non-stacked semiconductor device architecture  1000  as illustrated in  FIG. 3 . Accordingly, an area and a size of the semiconductor device architecture may be reduced. 
     However, due to the increased height of a vertical contact such as, for example, the top vertical contact  2111   b  as illustrated in  FIG. 5A  or the bottom vertical contact  2110   a  as illustrated in  FIG. 5B , a power connection resistance may increase which may lead to a performance degradation of the stacked semiconductor device architecture according to a related embodiment. 
       FIG. 7  illustrates a stacked semiconductor device architecture according to an example embodiment. 
     Referring to  FIG. 7 , the stacked semiconductor device architecture  10  according to an example embodiment includes a MOSFET cell including a PMOS  120   a  provided on a first level of a substrate  100  and an NMOS  120   b  is provided below the PMOS  120   a  on a second level of the substrate  100 . However, embodiments are not limited thereto. For example, the PMOS  120   a  may be provided at the second level and the NMOS  120   b  may be provided at a first level. 
     A horizontal interconnect  112   a  is connected to the PMOS  120   a . The horizontal interconnect  112   a  may be connected to an epitaxial layer of the PMOS  120   a . A bottom vertical contact  110   a  is provided on a lower surface of the horizontal interconnect  112   a  and extends downwards to a level between the PMOS  120   a  and the NMOS  120   b  in a vertical direction. However, embodiments are not limited thereto. For example, a bottom vertical contact  110   a  may be provided on the PMOS  120   a . A middle power rail  133   a  configured to supply power to the PMOS  120   a  is provided on a lower surface of the bottom vertical contact  110   a . The middle power rail  133   a  is provided at a vertical level between the PMOS  120   a  and the NMOS  120   b , and is not provided at a same vertical level of as the PMOS  120   a  and the NMOS  120   b.    
     The NMOS  120   b  is connected to a horizontal interconnect  112   b . The horizontal interconnect  112   b  may be connected to an epitaxial layer of the NMOS  120   b . A top vertical contact  111   b  is provided on an upper surface of the horizontal interconnect  112   b . However, embodiments are not limited thereto. For example, a top vertical contact  111   b  may be provided on the NMOS  120   b . Another middle power rail  133   b  is provided on an upper surface of the top vertical contact  111   b  at a vertical level between the PMOS  120   a  and the NMOS  120   b . The middle power rail  133   b  is provided at a vertical level between the PMOS  120   a  and the NMOS  120   b , and is not provided at a same vertical level of as the PMOS  120   a  and the NMOS  120   b.    
     The top vertical contact  111   b  and the bottom vertical contact  110   a  may include a metal material with a relatively low resistivity such as, for example, tungsten, cobalt, and ruthenium. However, materials of the top vertical contact  111   b  and the bottom vertical contact  110   a  are not limited thereto. 
     As illustrated in  FIG. 7 , as the middle power rails  133   a  and  133   b  are provided at a level between the PMOS  120   a  and the NMOS  120   b  included in a MOSFET cell, the height of the top vertical contact  111   b  and the bottom vertical contact  110   a  may be less than the height of the top vertical contact  2111   b  and bottom vertical contact  2110   a  as illustrated in  FIGS. 4A and 4B . The height of the top vertical contact  111   b  and the bottom vertical contact  110   a  may be less than a distance between the PMOS  120   a  and the NMOS  120   b  in the vertical direction. For example, the top vertical contact  111   b  and the bottom vertical contact  110   a  may have a height that is less than around 50 nm. However, embodiments are not limited thereto. 
     In addition, as the middle power rails  133   a  and  133   b  are provided at a vertically different level from the PMOS  120   a  and the NMOS  120   b , stress that may be caused on the PMOS  120   a  and the NMOS  120   b  devices by power rails may be reduced compared to a semiconductor architecture in which the power rails are provided on a vertically same level as the PMOS  120   a  and the NMOS  120   b.    
     As the middle power rails  133   a  and  133   b  are provided within the MOSFET cell and at a vertically different level from the metal layers  140 , additional space to provide metal layers  140  for signal routing may be available above the PMOS  120   a  and the NMOS  120   b . Such additional space may facilitate manufacturing process of the metal layers  140 . In addition, as the middle power rails  133   a  and  133   b  are provided at a same or similar vertical level, the manufacturing process may be more simplified. 
       FIG. 8A  is a cross-sectional view of the stacked semiconductor device architecture as illustrated in  FIG. 7 . 
     As illustrated in  FIG. 8A , a MOSFET cell includes a PMOS  120   a  is provided on a first level of a substrate  100  and an NMOS  120   b  is provided below the PMOS  120   a  on a second level of the substrate  100 . However, embodiments are not limited hereto. For example, the PMOS  120   a  may be provided at the second level and the NMOS  120   b  may be provided at a first level. A dielectric layer  101  may be provided between the PMOS  120   a  and the NMOS  120   b.    
     A horizontal interconnect  112   a  is connected to the PMOS  120   a . The horizontal interconnect  112   a  may be connected to an epitaxial layer of the PMOS  120   a . A bottom vertical contact  110   a  is provided on a lower surface of the horizontal interconnect  112   a  and extends downwards to a vertical level between the PMOS  120   a  and the NMOS  120   b . A middle power rail  133   a  configured to supply power to the PMOS  120   a  is provided on a lower surface of the bottom vertical contact  110   a . The middle power rail  133   a  is provided at a vertical level between the PMOS  120   a  and the NMOS  120   b , and is not provided as a same vertical level as the PMOS  120   a  and the NMOS  120   b.    
     The NMOS  120   b  is connected to a horizontal interconnect  112   b . The horizontal interconnect  112   b  may be connected to an epitaxial layer of the NMOS  120   b  and extend in a horizontal direction away from the NMOS  120   b . A top vertical contact  111   b  is connected to an upper surface of the horizontal interconnect  112   b  and extends upwards to a vertical level between the PMOS  120   a  and the NMOS  120   b . Another middle power rail  133   b  is provided on an upper surface of the top vertical contact  111   b  at a vertical level between the PMOS  120   a  and the NMOS  120   b , and is not provided as a same vertical level as the PMOS  120   a  and the NMOS  120   b.    
     In addition, metal layers  140  configured to route signals may be provided at a vertical level above the PMOS  120   a  and the NMOS  120   b.    
     As illustrated in  FIGS. 7 and 8A , the heights of the top vertical contact  111   b  and the bottom vertical contact  110   a  are less than the heights of the top vertical contact  2111   b  and the bottom vertical contact  2110   a  as illustrated in  FIGS. 4A and 4B . Thus, the power connection resistance may be lowered. Further, as the middle power rails  133   a  and  133   b  are provided at a level between the PMOS  120   a  and the NMOS  120   b , and do not protrude to a level below or level above the stacked PMOS  120   a  and NMOS  120   b , more space may be available above and below the stacked PMOS  120   a  and NMOS  120   b.    
       FIG. 8B  illustrates a top plan view of the stacked semiconductor device architecture as illustrated in  FIG. 7 . 
     Referring to  FIG. 8B , as the PMOS  120   a  and the NMOS  120   b  are stacked in a vertical direction, the width W 2  of the stacked semiconductor device architecture  10  according to an example embodiment may be reduced compared to a width W 1  of a non-stacked semiconductor device architecture  1000  as illustrated in  FIG. 3 . As illustrated in  FIG. 8B , the PMOS  120   a  and NMOS  120   b  are stacked to overlap each other in a vertical direction. 
       FIG. 9  illustrates a stacked semiconductor device architecture according to another example embodiment. 
     Referring to  FIG. 9 , the stacked semiconductor device architecture  10 ′ according to another example embodiment includes a PMOS  120   a  is provided on a first level of a substrate  100  and an NMOS  120   b  is provided below the PMOS  120   a  on a second level of the substrate  100 . However, embodiments are not limited thereto. For example, the PMOS  120   a  may be provided at a vertical level that is lower than the NMOS  120   b.    
     A horizontal interconnect  112   a  is connected to the PMOS  120   a . The horizontal interconnect  112   a  may be connected to an epitaxial layer of the PMOS  120   a . A bottom vertical contact  110   a  is provided on a lower surface of the horizontal interconnect  112   a  and extends downwards to a vertical level between the PMOS  120   a  and the NMOS  120   b . However, embodiments are not limited thereto. For example, a bottom vertical contact  110   a  may be provided on the PMOS  120   a . A middle power rail  133   a  configured to supply power to the PMOS  120   a  is provided on a lower surface of the bottom vertical contact  110   a . The middle power rail  133   a  is provided at a vertical level between the PMOS  120   a  and the NMOS  120   b , and is not provided as a same vertical level as the PMOS  120   a  and the NMOS  120   b.    
     The NMOS  120   b  is connected to a horizontal interconnect  112   b . The horizontal interconnect  112   b  may be connected to an epitaxial layer of the NMOS  120   b . A bottom vertical contact  110   b  is connected to a lower surface of the horizontal interconnect  112   b  and extends downwards. However, embodiments are not limited thereto. For example, the bottom vertical contact  110   b  may be provided on the NMOS  120   b . A bottom power rail  132   b  configured to supply power to the NMOS  120   b  is provided on a lower surface of the bottom vertical contact  110   b . The bottom power rail  132   b  is provided at a vertical level lower than the PMOS  120   a  and the NMOS  120   b , and is not provided as a same vertical level as the PMOS  120   a  and the NMOS  120   b . The bottom power rail  132   b  may be a buried power rail that is buried in the substrate  100 . 
     The bottom vertical contacts  110   a  and  110   b  may include a metal material with a relatively low resistivity such as, for example, tungsten, cobalt, and ruthenium. However, materials of the bottom vertical contacts  110   a  and  110   b  are not limited thereto. 
     As illustrated in  FIG. 9 , as a middle power rail  133   a  is provided at a level between the PMOS  120   a  and the NMOS  120   b  included in a MOSFET cell and a bottom power rail  132   b  is provided at a vertical level below the NMOS  120   b , the height of the bottom vertical contacts  110   a  and  110   b  may be less the height of the top vertical contact  2111   b  and the bottom vertical contact  2110   a  as illustrated in  FIGS. 4A and 4B . The height of the bottom vertical contacts  110   a  and  110   b  may be less than a distance between the PMOS  120   a  and the NMOS  120   b  in the vertical direction. For example, the bottom vertical contacts  110   a  and  110   b  may have a height that is less than around 50 nm. However, embodiments are not limited thereto. 
     In addition, as the middle power rail  133   a  and the bottom power rail  132   b  are provided at vertically different levels from the PMOS  120   a  and the NMOS  120   b , stress that may be caused on the PMOS  120   a  and the NMOS  120   b  devices by power rails may be reduced compared to a semiconductor architecture in which the power rails are provided on a vertically same level as the PMOS  120   a  and the NMOS  120   b.    
     As the middle power rail  133   a  is provided between the PMOS  120   a  and the NMOS  120   b , and the bottom power rail  132   b  is provided below the NMOS  120   b , additional space to provide metal layers  140  for signal routing may be available above the PMOS  120   a  and the NMOS  120   b . Such additional space may facilitate the manufacturing process of the metal layers  140 . 
       FIG. 10A  is a cross-sectional view of the stacked semiconductor device architecture as illustrated in  FIG. 9 . 
     As illustrated in  FIG. 10A , a PMOS  120   a  is provided on a first level of a substrate  100  and an NMOS  120   b  is provided on a second level of the substrate  100  that is lower than the first level. However, embodiments are not limited hereto. For example, the PMOS  120   a  may be provided at the second level and the NMOS  120   b  may be provided at a first level. A dielectric layer  101  may be provided between the PMOS  120   a  and the NMOS  120   b.    
     A horizontal interconnect  112   a  is connected to the PMOS  120   a . The horizontal interconnect  112   a  may be connected to an epitaxial layer of the PMOS  120   a . A bottom vertical contact  110   a  is provided on a lower surface of the horizontal interconnect  112   a  and extends downwards to a vertical level between the PMOS  120   a  and the NMOS  120   b . A middle power rail  133   a  configured to supply power to the PMOS  120   a  is provided on a lower surface of the bottom vertical contact  110   a . The middle power rail  133   a  is provided at a vertical level between the PMOS  120   a  and the NMOS  120   b , and is not provided as a same vertical level as the PMOS  120   a  and the NMOS  120   b.    
     The NMOS  120   b  is connected to a horizontal interconnect  112   b . The horizontal interconnect  112   b  may be connected to an epitaxial layer of the NMOS  120   b  and extend in a horizontal direction away from the NMOS  120   b . A bottom vertical contact  110   b  is connected to a lower surface of the horizontal interconnect  112   b  and extends downwards to a vertical level below the NMOS  120   b . A bottom power rail  132   b  configured to supply power to the NMOS  120   b  is provided on a lower surface of the bottom vertical contact  110   b . The bottom power rail  132   b  is provided at a vertical level below the PMOS  120   a  and the NMOS  120   b , and not provided on a same vertical level as the PMOS  120   a  and the NMOS  120   b.    
     In addition, metal layers  140  configured to route signals may be provided at a vertical level above the PMOS  120   a  and the NMOS  120   b.    
     As illustrated in  FIGS. 9 and 10A , the heights of the bottom vertical contacts  110   a  and  110   b  are less than the height of the top vertical contact  2111   b  and the height of the bottom vertical contact  2110   a  as illustrated in  FIGS. 4A and 4B . For example, the height of the bottom vertical contacts  110   a  and  110   b  may be less than around 50 nm. However, embodiments are not limited thereto. 
     As the heights of the bottom vertical contacts  110   a  and  110   b  are reduced, the power connection resistance may be reduced. Further, as the middle power rail  133   a  and bottom power rail  132   b  are provided within or below the PMOS  120   a  and the NMOS  120   b  in a vertical direction, additional space to provide metal layers  140  for signal routing may be available above the PMOS  120   a  and the NMOS  120   b . Such additional space may facilitate the manufacturing process of the metal layers  140 . 
       FIG. 10B  illustrates a top plan view of the stacked semiconductor device architecture as illustrated in  FIG. 9 . 
     Referring to  FIG. 10B , as the PMOS  120   a  and the NMOS  120   b  are stacked in a vertical direction, the width W 2  of the stacked semiconductor device architecture  10 ′ may be reduced compared to a width W 1  of a non-stacked semiconductor device architecture  1000  as illustrated in  FIG. 3 . In  FIG. 10B  the PMOS  120   a  and NMOS  120   b  are illustrated as being provided at different locations in a horizontal direction. However, embodiments are not limited thereto, and the PMOS  120   a  and the NMOS  120   b  may be stacked to overlap each other in a vertical direction as illustrated in  FIG. 10A . 
       FIG. 11  illustrates a perspective view of a stacked semiconductor device architecture according to example embodiments. 
     As illustrated in  FIG. 11 , a semiconductor device architecture may include a substrate  100  and a stacked semiconductor device architecture  10  provided on a first surface of the substrate  100 . The stacked semiconductor device architecture  10  may incorporate the stacked semiconductor device architecture according to example embodiments. For example,  FIGS. 8A and 10A  may be cross-sectional views taken along line I-I′ of  FIG. 11 . 
     The substrate  100  may be a wafer including, for example, a Si substrate, a glass substrate, a sapphire substrate, etc. However, embodiments are not limited thereto. As illustrated in  FIG. 11 , the substrate  100  may be a circular panel, but the shape of the substrate  100  is not limited thereto. For example, the substrate  100  may be a tetragonal panel. The substrate  100  may include a single layer or multiple layers. 
       FIG. 12  illustrates a semiconductor device that may incorporate the stacked semiconductor device architectures according to example embodiments. 
     Referring to  FIG. 12 , a semiconductor package  200  according to an example embodiment may include a processor  2200  and semiconductor devices  2300  that are mounted on a substrate  2100 . The processor  2200  and/or the semiconductor devices  2300  may include one or more of the stacked semiconductor device architecture described in the above example embodiments. 
       FIG. 13  illustrates a schematic block diagram of an electronic system according to an example embodiment. 
     Referring to  FIG. 13 , an electronic system  3000  in accordance with an embodiment may include a microprocessor  3100 , a memory  3200 , and a user interface  3300  that perform data communication using a bus  3400 . The microprocessor  3100  may include a central processing unit (CPU) or an application processor (AP). The electronic system  3000  may further include a random access memory (RAM)  3500  in direct communication with the microprocessor  3100 . The microprocessor  3100  and/or the RAM  3500  may be implemented in a single module or package. The user interface  3300  may be used to input data to the electronic system  3000 , or output data from the electronic system  3000 . For example, the user interface  3300  may include a keyboard, a touch pad, a touch screen, a mouse, a scanner, a voice detector, a liquid crystal display (LCD), a micro light-emitting device (LED), an organic light-emitting diode (OLED) device, an active-matrix light-emitting diode (AMOLED) device, a printer, a lighting, or various other input/output devices without limitation. The memory  3200  may store operational codes of the microprocessor  3100 , data processed by the microprocessor  3100 , or data received from an external device. The memory  3200  may include a memory controller, a hard disk, or a solid state drive (SSD). 
     At least the microprocessor  3100 , the memory  3200  and/or the RAM  3500  in the electronic system  3000  may include stacked semiconductor device architecture as described in the above example embodiments. 
     It should be understood that example embodiments described herein should be considered in a descriptive sense only and not for purposes of limitation. Descriptions of features or aspects within each example embodiment should typically be considered as available for other similar features or aspects in other embodiments. 
     While example embodiments have been described with reference to the figures, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope as defined by the following claims.