Abstract:
A method for forming a metal line in a semiconductor device and an associated apparatus. The method includes at least one of (1) Depositing a metal line layer and a metal contact layer over a semiconductor substrate. (2) Patterning the metal contact layer and the metal line layer to form a primarily formed contact portion and a lower metal line. (3) Patterning the primarily formed contact portion to form a secondarily formed contact portion. (4) Forming an insulating film on the semiconductor substrate including the secondarily formed contact portion and the lower metal line. (5) Planarizing the insulating film such that the secondarily formed contact portion is exposed. (6) Forming an upper metal line over the planarized insulating film to be in electrical contact with the secondarily formed contact portion.

Description:
[0001]    The present application claims priority under 35 U.S.C. §119 to Korean Patent Application No. 10-2011-0146421 (filed on Dec. 29, 2011), which is hereby incorporated by reference in its entirety. 
       BACKGROUND 
       [0002]      FIGS. 1A to 1D  are cross-sectional views illustrating a method for forming a metal line in a semiconductor device, in accordance with the related art. As illustrated in  FIG. 1A , insulating film  20  may be formed on/over semiconductor substrate  10 . A photo-resist pattern for defining a contact formation area may be formed on/over insulating film  20 . Contact hole  60  may be formed in the contact formation area of insulating film  20  by a patterning process using a photo-resist pattern. 
         [0003]    As illustrated in  FIG. 1B , multiple barrier metal layers  30  and  40  may be formed inside contact hole  60  and on/over insulating film  20 . Metal may be filled in to contact hole  60  with barrier metal layers  30  and  40  to form contact metal layer  50 . As illustrated in  FIG. 1C , semiconductor substrate  10  with contact metal layer  50  may be planarized until insulating film  20  is exposed by chemical mechanical polishing (CMP) (or similar process), thereby forming a contact. As illustrated in  FIG. 1D , glue layer  70 , metal line layer  80 , and/or anti-reflective coating layer  90  may be sequentially deposited and patterned to form a metal line. 
         [0004]    In a related art method of forming a metal line, with reference to examples illustrated in  FIGS. 1A to 1D , a contact is formed by the process of forming a contact hole, forming barrier metal layers inside the contact hole, and filing in metal inside the contact hole. Because related art semiconductors may be highly integrated with relatively high aspect ratios, breakage of the barrier metal layers may occur because of poor step coverage when the barrier metal layers are formed inside the contact hole. 
         [0005]    The relatively high aspect ratio of related art semiconductor devices, creates difficulties in filling aluminum in a contact hole by sputtering methods when a contact metal layer is buried in the contact hole. In the related art, to avoid breakage of the barrier metal layers, tungsten may be filled in the contact hole by chemical vapor deposition (CVD) to use the tungsten as a plug. However, tungsten has a higher resistivity than aluminum, which may lead to higher contact resistance. In the related art, electro-migration (EM) characteristics may be deteriorated or degraded at a joined region of the contact and the contact metal layer (i.e. an interface between the aluminum and the tungsten plug). Also, in the related art, the use of borderless vias may have the limitation of a high probability of defects caused by misalignment when a metal line is formed on top of the contact. 
       SUMMARY 
       [0006]    Embodiments relate to a method of forming a metal line in a semiconductor device, in which the metal line is formed by depositing and patterning a metal layer without forming and burying a contact hole. 
         [0007]    Embodiments relate to a method of forming a metal line in a semiconductor device by stacking and patterning a metal layer without forming and burying a contact hole. Embodiments may simplify the formation of a metal line because the process of forming a barrier metal layer inside a contact hole is eliminated. Accordingly, embodiments may eliminate, reduce, and/or mitigate various types of problems that may occur when the barrier metal layer is formed inside the contact hole. 
         [0000]    In accordance with embodiments, a method of forming a metal line in a semiconductor device includes at least one of the following: (1) Depositing a metal line layer and a metal contact layer on/over a semiconductor substrate. (2) Patterning the metal contact layer and the metal line layer to form a primarily formed contact portion and a lower metal line. (3) Patterning the primarily formed contact portion to form a secondarily formed contact portion. (4) Forming an insulating film on/over the semiconductor substrate including the secondarily formed contact portion and the lower metal line. (5) Planarizing the insulating film such that the secondarily formed contact portion is exposed. (6) Forming an upper metal line on/over the planarized insulating film so as to be in contact with the secondarily formed contact portion. 
         [0008]    In embodiments, the secondarily formed contact portion has a polygonal or circular cross-section. In embodiments, before patterning the formed contact portion to form a secondarily formed contact portion, a passivation film is formed to cover a sidewall of the lower metal line. In embodiments, an anti-reflective coating layer is formed on either an interface between the metal line layer and the metal contact layer, the top surface of the metal contact layer, and/or the top surface of the upper metal line. In embodiments, a barrier metal film is formed on/over an interface between the semiconductor substrate and the metal line layer. In embodiments, the metal line layer, the metal contact layer, and the upper metal line are formed of aluminum. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    The above and other objects and features of embodiments will become apparent from the following description of embodiments, given in conjunction with the accompanying drawings, in which: 
           [0010]      FIGS. 1A to 1D  are cross-sectional views illustrating a method for forming a metal line in a semiconductor device, in accordance with the related art. 
           [0011]      FIGS. 2A to 2L  are cross-sectional views illustrating a method of forming a metal line in a semiconductor device, in accordance with embodiments. 
       
    
    
     DETAILED DESCRIPTION 
       [0012]      FIGS. 2A to 2L  are cross-sectional views illustrating a method of forming a metal line of a semiconductor device, in accordance with embodiments.  FIG. 2L  illustrates a semiconductor device structure resulting from the method illustrated in  FIGS. 2A-2K  for forming a metal line, in accordance with embodiments. 
         [0013]    In a semiconductor device according to embodiments, barrier metal layer  110  may be deposited on/over semiconductor substrate  100 . Lower metal line layer  120  may be deposited and patterned on/over barrier metal layer  110 , in accordance with embodiments. For example, in embodiments, barrier metal layer  110  may be made of a single film of titanium (Ti), titanium nitride (TiN), a compound of titanium and tungsten (TiW), tantalum (Ta), tantalum nitride (TaN), or a single film including any combination of these materials. In embodiments, lower metal line layer  120  may be formed of aluminum. 
         [0014]    First anti-reflective coating layer  130  may be deposited on/over lower metal line layer  120 . A metal contact layer  140  may be deposited and patterned on/over first anti-reflective coating layer  130  and may be used as a contact portion. Second anti-reflective coating layer  150  may be deposited on/over metal contact layer  140 . In embodiments, one or both of first anti-reflective coating layer  130  and second anti-reflective coating layer  150  may be made of a single film of titanium (Ti), titanium nitride (TiN), a compound of titanium and tungsten (TiW), tantalum (Ta), tantalum nitride (TaN), or a single film made of a combination of materials. In embodiments, metal contact layer  140  may be formed of aluminum. 
         [0015]    In embodiments, lower metal line layer  120 , first anti-reflective coating layer  130 , and metal contact layer  140  may be isolated and protected from the surroundings by being enclosed by insulating film  180 . In embodiments, insulating film  180  may be made of an oxide film such as a silicon oxide film (SiO 2 ). 
         [0016]    In embodiments, upper metal line layer  190  may be patterned on/over the insulating film  180  and used as upper wiring. Upper metal line layer  190  may be deposited to be electrically connected to metal contact layer  140  via second anti-reflective coating layer  150 . Third anti-reflective coating layer  200  may be deposited on/over upper metal line layer  190 . In embodiments, upper metal line layer  190  may be formed of aluminum. In embodiments, third anti-reflective coating layer  200  may be formed as a single film using a film made of titanium (Ti), titanium nitride (TiN), a compound of titanium and tungsten (TiW), tantalum (Ta), tantalum nitride (TaN), or as a single film using a film made of a combination of these materials. In embodiments, third anti-reflective coating layer  200  may be formed as a combined film using multiple films. 
         [0017]    In accordance with embodiments, barrier metal layer  110 , first anti-reflective coating layer  130 , second anti-reflective coating layer  150 , third anti-reflective coating layer  200 , and/or may be selectively omitted depending on embodiments. 
         [0018]    A method of forming a metal line in accordance with embodiments is illustrated in example  FIGS. 2A to 2L . As illustrated in  FIG. 2A , lower metal line layer  120  and metal contact layer  140  are deposited on/over semiconductor substrate  100 , in accordance with embodiments. In embodiments, barrier metal layer  110  may be formed on/over an interface between semiconductor substrate  100  and lower metal line layer  120 . In embodiments, first anti-reflective coating layer  130  may be formed on/over an interface between lower metal line layer  120  and metal contact layer  140 . In embodiments, second anti-reflective coating layer  150  may be formed on/over the top surface of metal contact layer  140 . Lower metal line layer  120 , first anti-reflective coating layer  130 , metal contact layer  140 , and/or second anti-reflective coating layer  150  may be formed in-situ. 
         [0019]    For example, in embodiments, lower metal line layer  120  and metal contact layer  140  may be formed of aluminum. Barrier metal layers  110 , first anti-reflective coating layer  130 , and/or second anti-reflective coating layer  150  may be formed of a single film titanium (Ti), titanium nitride (TiN), a compound of titanium and tungsten (TiW), tantalum (Ta), tantalum nitride (TaN), or a single film that is a combination of these materials. In embodiments, a single film or a combined film may be deposited and formed by a sputtering method, a CVD method, and/or a similar method. 
         [0020]    As illustrated in  FIG. 2B , first pattern film  160  may be formed on top of the second anti-reflective coating layer  150  and may define the shape of metal contact layer  140  and second anti-reflective coating layer  150 , in accordance with embodiments. In embodiments, first pattern film  160  may be formed using a photo-resist. 
         [0021]    As illustrated in  FIG. 2C , first pattern film  160  may be used to pattern second anti-reflective coating layer  150 , metal contact layer  140 , first anti-reflective coating layer  130 , lower metal line layer  120 , and/or barrier metal layer  110 , in accordance with embodiments. In embodiments, a lower metal line may be formed using lower metal line layer  120 . During this process, in embodiments, metal contact layer  140  may be patterned in the shape of a metal line, thereby primarily forming a contact portion connecting the lower metal line and the upper metal line (to be formed subsequently). 
         [0022]    As illustrated in  FIG. 2D , first pattern film  160  may be removed, in accordance with embodiments. 
         [0023]      FIG. 2E  is a three dimensional depiction of the structure illustrated in  FIG. 2D , in accordance with embodiments.  FIG. 2F  illustrates the structure shown in  FIG. 2D , when viewed orthogonally in a lengthwise direction of the lower metal line formed by lower metal line layer  120 , in accordance with embodiments. 
         [0024]    As illustrated in  FIG. 2F , second pattern film  170  may be formed on top of second anti-reflective coating layer  150  and may define the shape of the contact portion, in accordance with embodiments. In embodiments, second pattern film  170  may be formed using a photo-resist. In embodiments, second pattern film  170  may be formed in such a shape as to cover a sidewall of the lower metal line formed by lower metal line layer  120 . 
         [0025]    As illustrated in  FIG. 2G , second pattern film  170  may be used to pattern second anti-reflective coating layer  150  and metal contact layer  140  until first anti-reflective coating layer  130  is opened, in accordance with embodiments. In embodiments, first anti-reflective coating layer  130  may be used as an etch stop film. In embodiments, the contact portion may be secondarily formed using metal contact layer  140 . In embodiments, second pattern film  170  may be formed in such a shape as to cover a sidewall of the lower metal line formed using lower metal line layer  120 . In embodiments, second pattern film  170  may serve as a passivation film for protecting the lower metal line during a contact portion patterning process. 
         [0026]    As illustrated in  FIG. 2H , second pattern film  170  may be removed, in accordance with embodiments. 
         [0027]      FIG. 2I  is a three dimensional depiction of the structure illustrated in  FIG. 2H , in accordance with embodiments. Although a contact portion secondarily formed using metal contact layer  140  has been illustrated to have a rectangular cross-sectional shape in  FIG. 2I , the secondarily formed contact portion may be formed to have a polygonal or circular cross-section, in accordance with embodiments. 
         [0028]    As illustrated in  FIG. 2J , insulating film  180  may be formed on/over the semiconductor structure in which the contact portion is secondarily formed using metal contact layer  140 . For example, insulating film  180  may be formed by depositing an oxide film by CVD, in accordance with embodiments. 
         [0029]    As illustrated in  FIG. 2K , planarization process (e.g. chemical mechanical polishing, overall etching using plasma, and/or a similar process) may be performed on insulating film  180  until second anti-reflective coating layer  150  is exposed, in accordance with embodiments. In embodiments that do not include second anti-reflective coating layer  150 , a planarization process may be performed until metal contact layer  140  forming a secondarily formed contact portion is exposed. 
         [0030]    As illustrated in  FIG. 2L , upper metal line layer  190  may be formed on top of insulating film  180 , in accordance with embodiments. In embodiments, upper metal line layer  190  may be in contact with the secondarily formed contact portion. In embodiments, third anti-reflective coating layer  200  may be formed on top of upper metal line layer  190 . A third pattern film may be formed on top of the third anti-reflective coating layer  200  and may define the shape of the upper metal line, in accordance with embodiments. In embodiments, the third pattern film may be used to pattern third anti-reflective coating layer  200  and upper metal line layer  190  until insulating film  180  is exposed. As a result, the upper metal line may be formed using upper metal line layer  190 . 
         [0031]    In embodiments, a metal line may be formed by depositing and patterning a metal layer without forming and burying a contact hole, thereby simplifying the formation of the metal line because the process of forming a barrier metal layer inside the contact hole is omitted. In embodiments, various types of problems such as breakage of the barrier metal layer or similar problems may be substantially eliminated, minimized, and/or reduced due to the formation process of the barrier metal layer because forming the barrier metal layer in the contact hole is omitted. In embodiments, the contact may be as long as desired by employing the process of depositing and patterning a metal layer. 
         [0032]    In embodiments, it is possible to prevent deterioration (e.g. degradation) of the EM characteristics of an interface between aluminum and a tungsten plug in the related art because a metal line and a plug may be both formed of aluminum and contact resistance may be improved compared to that in a related art tungsten plug structure. In embodiments, the problem of misalignment of a borderless via structure may be prevented because a metal line layer and a contact portion (contact) metal layer may be formed together. 
         [0033]    While embodiments have been shown and described, embodiments are not limited thereto. It will be understood by those skilled in the art that various changes and modifications may be made without departing from the scope of the embodiments as defined in the following claims.