Abstract:
Provided are a semiconductor device and a method for manufacturing the same. Since an additional space for forming a shield line is unnecessary, the critical dimension of metal lines is reduced, thereby improving data transfer characteristics, signaling characteristics and noise characteristics of the metal lines. The semiconductor device includes: a plurality of metal lines disposed on the semiconductor device; a plurality of insulation layers disposed on the metal lines; and a plurality of shield lines disposed between the insulation layers.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application claims priority to Korean patent application number 10-2010-0002411, filed on Jan. 11, 2010, which is incorporated by reference in its entirety. 
     BACKGROUND OF THE INVENTION 
     The present invention relates to a semiconductor device and a method for manufacturing the same. More particularly, the present invention relates to a semiconductor device including a metal line and a method for manufacturing the same. 
     Semiconductor devices are manufactured to operate according to their assigned purposes through depositing/etching material on a silicon wafer and doping of impurities into a predetermined region within a silicon wafer. A representative example of a semiconductor device is a semiconductor memory device. The semiconductor memory device includes a large number of elements (e.g., transistors, capacitors, and resistors) in order to perform an assigned purpose. The respective elements are coupled together through conductive layers to exchange data or signals. 
     As the fabrication technologies of semiconductor devices have been developed, many efforts have been made to manufacture a larger number of chips on a wafer by increasing the integration density of semiconductor devices. Accordingly, a critical dimension (CD) in a design rule is gradually reduced in order to increase the integration density. Furthermore, semiconductor devices are increasingly required to operate at a higher speed and reduce power consumption. 
     In order to increase the integration density, it is necessary to reduce the sizes of elements inside the semiconductor devices and reduce the lengths and widths of interconnections which couple the elements together. Moreover, the resistances of interconnections must be small so that electric signals can be transferred with minimal loss within the semiconductor devices through interconnections having narrow widths. 
     Generally, in a semiconductor device, metal lines are formed on various layers in order to electrically couple elements or interconnections. A contact plug is then formed in order to couple an upper metal line to a lower metal line. Recent studies have been conducted to use copper (Cu), which has a low resistance, as a metal line material, or reduce a pattern density of a metal line itself. 
     BRIEF SUMMARY OF THE INVENTION 
     Various embodiments of the invention are directed to providing a semiconductor device and a method for manufacturing the same, in which, since a shield line is formed between metal lines by a self-aligned process, an additional space for forming the shield line is unnecessary and thus the CD of the metal line is reduced, thereby improving data transfer characteristics, signaling characteristics and noise characteristics of the metal lines. 
     In an embodiment of the present invention, a semiconductor device includes: a plurality of metal lines disposed on a semiconductor device; a plurality of insulation layers disposed on the metal lines; and a plurality of shield lines disposed between the insulation layers. Accordingly, since an additional space for forming the shield line is unnecessary, the CD of the metal line is reduced, thereby improving data transfer characteristics, signaling characteristics and noise characteristics of the metal lines. 
     The shield line may include tungsten (W), and the insulation layer may include a nitride film. The metal line may include: a metal film formed of aluminum (Al) or copper (Cu); and barrier metal films formed of titanium nitride (TiN) under and above the metal film. 
     The semiconductor device may further include: an interlayer dielectric layer disposed under the metal line; an etch stop layer disposed on the interlayer dielectric layer; and an oxide film disposed on the etch stop layer. Accordingly, oxide patterns having a predetermined thickness can be easily formed under the metal lines. 
     The thickness of the oxide film may be substantially equal to the thickness of the insulation layer. Accordingly, the metal line and the shield line can be formed to have the substantially equal height. 
     Ends of the plurality of shield lines may be coupled together and coupled to a ground contact plug. Accordingly, the plurality of shield lines are easily grounded, thereby improving the shield effect on the metal lines. 
     In another embodiment of the present invention, a method for manufacturing a semiconductor device includes: forming a plurality of metal lines in a semiconductor device; forming a plurality of insulation layers on an entire surface of the semiconductor device including the metal lines; and forming a plurality of shield lines between the respective insulation layers. Accordingly, since an additional space for forming the shield line is unnecessary, the CD of the metal line is reduced, thereby improving data transfer characteristics, signaling characteristics and noise characteristics of the metal lines. 
     The forming of the metal lines may include: forming a lower barrier metal film, a metal film, and an upper barrier metal film in the semiconductor device; and etching the upper barrier metal film, the metal film, and the lower barrier metal film by using a photolithography process. 
     The upper barrier metal film and the lower barrier metal film may include a titanium nitride film, and the metal film may include a tungsten film. 
     The forming of the shield lines may include: depositing a shield line material on an entire surface of the semiconductor device including the metal lines; etching an upper portion of the deposited shield line material; and forming an interlayer dielectric layer on the metal lines and the shield lines. Accordingly, the shield lines are formed by a self-aligned process, without performing a separate photolithography process. 
     The etching of the upper portion of the shield line material may include: planarizing the upper portion of the shield line material by a chemical mechanical polishing (CMP) process; and etching the upper portion of the remaining shield line material by an etch-back process. Before depositing the shield line material, the method may further include forming a barrier metal film formed of titanium nitride on an entire surface of the semiconductor device including the metal lines. The height of the shield line may be substantially equal to the height of the metal line. 
     Before forming the metal lines, the method may further include: forming an interlayer dielectric layer in the semiconductor device; forming an etch stop layer on the interlayer dielectric layer; and forming an oxide film on the etch stop layer. 
     The thickness of the oxide film may be substantially equal to the thickness of the insulation layer. Accordingly, the lower height of the metal line may be substantially equal to the lower height of the shield line. 
     The forming of the shield lines may include coupling ends of the respective shield lines together and coupling the ends of the respective shields lines to a ground contact plug. Accordingly, the shield effect on the metal lines can be improved. 
     The insulation layers may be formed on the top surface and sidewalls of the metal lines and the top surface of the etch stop layer. 
     The forming of the insulation layers may be performed using a low pressure chemical vapor deposition (LP-CVD) process, and the forming of the insulation layer may include adjusting the critical dimension of the shield line by adjusting the thickness of the insulation layer. 
     The CD of the shield line and the thickness of the insulation layer may be approximately ⅓ of the critical dimension of the metal line. Accordingly, the shield line can be formed while maintaining the CD of the metal line to the existing level. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1A and 1B  are a plan view and a cross-sectional view of a semiconductor device according to an embodiment of the present invention, respectively. 
         FIGS. 2A to 2F  are cross-sectional views illustrating a method for manufacturing a semiconductor device according to an embodiment of the present invention. 
         FIG. 3  is a plan view of the semiconductor device according to the embodiment of the present invention. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Description will now be made in detail in reference to the embodiments of the present invention and accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like elements. 
       FIGS. 1A and 1B  are a plan view and a vertical cross-sectional view of a semiconductor device according to an embodiment of the present invention. Specifically,  FIG. 1B  is a cross-sectional view taken along line A-A′ of  FIG. 1A . Referring to  FIG. 1A , the semiconductor device according to the embodiments of the present invention includes a plurality of metal lines  10  formed in line and space patterns.  FIG. 1A  shows the metal lines  10  for references, though the metal lines  10  are below the insulation layers  30 . In an embodiment, the semiconductor device is a semiconductor memory device, e.g., a DRAM, NAND, or NOR device. In an embodiment, the metal lines  10  are interconnects formed over memory cells, e.g., transistors (not shown), to connect one part of the semiconductor device to another part of the semiconductor. The metal lines  10  include aluminum, copper, or tungsten depending on implementation. Insulation layers  30  having a predetermined width are formed on sidewalls of the metal lines  10 . A shield line  20  is formed in a space defined by the insulation layers  30  between the metal lines  10 . 
     The metal lines  10  electrically couple elements or interconnections and serve as data lines through which data are transmitted. The shield line  20  is formed between the metal lines  10  in order to prevent a fatal malfunction caused by coupling, interference or noise between the adjacent metal lines  10 . If the shield line  20  is formed among all the metal lines  10 , the area of the semiconductor device would significantly increase. Therefore, the shield line  20  is formed among the important metal lines  10  in an embodiment of the present invention. 
     Referring to  FIG. 1B , the metal line  10  may include a metal film  12  and barrier metal films  14  and  16  disposed under and above the metal film  12 . The metal film  12  may include aluminum (Al) or copper (Cu), and the barrier metal films  14  and  16  may include titanium nitride (TiN). An oxide film  46  is formed under the metal line  10 . The oxide film  46  is formed to have a thickness substantially equal to that of the insulation layer  30 . Consequently, the height of the metal line  10  may coincide with the height of the shield line  20 . 
     An interlayer dielectric layer  42  and an etch stop layer  44  are formed under the metal line  10 . The interlayer dielectric layer  42  may include an oxide, and the etch stop layer  44  may include a nitride. 
     The insulation layer  30  is deposited on the entire surface of the metal line  10 , including the sidewalls and the top surface. The insulation layer  30  insulates the adjacent metal lines  10  from each other, provides a space where the shield line  20  is to be formed between the adjacent metal lines  10 , and insulates the adjacent metal lines  10  from the shield line  20 . The insulation layer  30  may be formed of nitride. The thickness of the insulation layer  30  may be formed approximately ⅓ of the CD of the metal line  10 . In this case, the shield line  20  can be formed to have a CD corresponding to approximately ⅓ of a CD of the metal line  10  so that a device space size between lines, i.e., the metal line  10 , is substantially the same as the line size. However, each of the insulation layer  30  and the shield line  20  does not necessarily have a width ⅓ of the metal line  10  so long as the space, where the insulation layer  30  and the shield line  20  are formed, has substantially the same width as the metal line  10 . An additional element can be further formed in the line area or in the space according to implementation. 
     After the insulation layer  30  is deposited, the shield line  20  fills a space between the insulation layer  30 . The shield line  20  may include tungsten (W). When the height of the shield line  20  is substantially equal to the height of the metal line  10 , coupling, interference or noise between the adjacent metal lines  10  can be significantly reduced. 
       FIGS. 2A to 2F  are cross-sectional views illustrating a method for manufacturing a semiconductor device according to an embodiment of the present invention. A method for manufacturing the semiconductor device having the above-described structure will be described below with reference to  FIGS. 2A to 2F . 
     Referring to  FIG. 2A , an interlayer dielectric layer  42 , an etch stop layer  44 , and an oxide film  46  are sequentially deposited in order to form a lower interlayer material of a metal line. The interlayer dielectric layer  42  and the oxide film  46  may be formed of oxide, and the etch stop layer  44  may include a nitride film having a different etch selectivity from the oxide film and can be formed ith a thickness of approximately 100 Å. The oxide film  46  may be formed to a thickness corresponding to approximately ⅓ of a CD of a metal line  10 . 
     A metal line  10  is formed on the oxide film  46 . The metal line  10  includes a lower barrier metal film  16 , a metal film  12 , and an upper barrier metal film  14  sequentially formed on the oxide film  46 . The metal film  14  may include aluminum (Al) or copper (Cu), and the barrier metal films  14  and  16  may include titanium nitride (TiN). 
     In a case where the metal film  12  is formed of aluminum (which can be easily etched), a metal line pattern may be formed by sequentially stacking a TiN film, an Al film, and a TiN film and etching the three material films using a photolithography process. In a case where the metal film  12  is formed of copper (which is not easily etched), a Damascene process may be used. Specifically, an interlayer dielectric layer (not shown) is formed to a thickness corresponding to a thickness of the metal line  10 , and the interlayer dielectric layer is etched to form a recess (not shown) where the metal line  10  is to be formed. Then, the barrier metal film  14 , the metal film  12 , and the barrier metal film  16  are sequentially formed within the recess. 
     The metal line  10  is formed in a line and space pattern. In this case, a line to space ratio may be 1:1. 
     Referring to  FIG. 2B , the oxide film  46  under the metal line  10  is etched and removed in a space between the metal lines  10 . The etching process may use a reactive ion etch (RIE) process and may be targeted to the etch stop layer  44 . 
     Referring to  FIG. 2C , an insulation layer  30  is deposited on the entire pattern including the metal lines  10  and the oxide film  46 . The insulation layer  30  may include a nitride film and can be deposited on the entire surface, including the top surfaces and sidewalls of the metal lines  10 , sidewalls of the oxide film  46 , and the surface of the etch stop layer  44 . The thickness of the insulation layer  30  may be formed substantially equal to the thickness of the oxide film  46 , and the insulation layer  30  may be formed to have a thickness corresponding to approximately ⅓ of a line CD, i.e., the width of the metal line  10 , so that the recess  35  having a width that is a third of the line CD, i.e., the width of the metal line  10 , is formed between the insulation layers  30 . In the process of depositing the insulation layer  30 , the insulation layer  30  may be formed of a lining pattern having substantially the same thickness over the metal line  10  by using a low pressure chemical vapor deposition (LP-CVD) process. 
     Referring to  FIG. 2D , the recess  35  is filled by depositing a shield line material between the insulation layer  30 . The shield line material is formed of a conductive material, e.g., tungsten (W), aluminum, (Al), copper (Cu), doped polysilicon, or the like. Although not shown, titanium nitride (TiN) approximately 50-Å thick may be deposited as a barrier metal between the shield line  20  and the insulation layer  30 . 
     In an embodiment, the recess  35  is formed between the insulation layers  30  and the shield line  20  is provided within the recess  35  using a self-aligned process, i.e., a separate photolithography mask is not required. Since an additional expensive photolithography process is not needed, the manufacturing cost of a semiconductor device can be reduced. 
     Referring to  FIG. 2E , the shield line material on the insulation layer  30  is planarized by a chemical mechanical polishing (CMP) process or an etch-back process targeted to the insulation layer  30 . 
     Referring to  FIG. 2F , an etch-back process is performed on the shield line material so that the height of the shield line  20  coincides with the height of the metal line  10 . An interlayer insulation layer  48  is deposited over the shield line  20  and the metal line  10 . Consequently, the process of forming a 1-layer metal line  10  is completed. Another metal line may be formed on the metal line  10 , and the above-described processes may be equally applied. 
     In the method for manufacturing the semiconductor device according to an embodiment of the present invention, the insulation layers  30  are formed on the surfaces of the metal interconnects  10 , and the shield line  20  is formed between the insulation layers  30 . Therefore, the width of the shield line  20  may be adjusted by the width of the insulation layer  30 . 
     Meanwhile,  FIG. 3  is a horizontal cross-sectional view of the semiconductor device according to the embodiment of the present invention as shown in  FIG. 1A . Referring to  FIG. 3 , ends of the plurality of shield lines  20  are coupled together to form a joining pattern  22 . The joining pattern  22  may be electrically coupled to a ground contact plug  24 . The ground contact plug  24  is electrically coupled to a ground voltage. The shield line  20  performs no data transmission and serves to shield the metal lines  10  from one another. Thus, if a plurality of shield lines  20  are grounded together, the shield effect for the metal lines  10  can be further improved. In an embodiment, the shield line  20  is employed to reduce interference between metal lines  10 , but the shield line  20  may be used to reduce interference between other lines. 
     The above embodiments of the present invention are illustrative and not limitative. Various alternatives and equivalents are possible. The invention is not limited by the embodiment described herein. Nor is the invention limited to any specific type of semiconductor device. Other additions, subtractions, or modifications are obvious in view of the present disclosure and are intended to fall within the scope of the appended claims.