Patent Publication Number: US-2005142872-A1

Title: Method of forming fine pattern for semiconductor device

Description:
BACKGROUND OF THE INVENTION  
      (a) Field of the Invention  
      The present invention relates to a method of manufacturing a semiconductor device, and more particularly to a method of forming a fine pattern for a semiconductor device.  
      (b) Description of the Related Art  
      In fabricating a semiconductor device, a conductive layer pattern or an insulating layer pattern is generally formed by a deposition process, a photolithography process and an etching process. The photolithography process generally includes coating a photoresist layer, exposing the photoresist layer and developing the exposed photoresist layer, to form a photoresist pattern. The critical dimension (CD) of this photoresist pattern has effect on the CD of the conductive layer pattern or the insulating layer pattern.  
      Accordingly, for the purpose of obtaining the CD of a fine pattern corresponding to a high integration density device, a light source of a short wavelength such as KrF (λ=248 nm) or ArF (λ=193 nm) instead of I-line (λ=365 nm) light source must be employed in an exposure apparatus. However, in case of using the light source of the short wavelength, there is a problem in that fabrication cost is very expensive owing to employing a new exposure apparatus and a new photoresist.  
      To overcome this problem, a double exposure method exposing a photoresist layer by double exposure while applying a conventional exposure apparatus employing an I-line (λ=365 nm) or a G-line (λ=436 nm) light source to form a fine photoresist pattern has been used. However, this method has problems in that it is difficult to obtain the minimum line width of the photoresist pattern due to wave motion of the exposure beam and collapse of the photoresist pattern occurs.  
     SUMMARY OF THE INVENTION  
      An object of the present invention is to provide a method that is capable of easily forming a fine pattern corresponding to a high integration and/or high density device, without using a new exposure apparatus.  
      The object of the present invention as noted above is accomplished by a method of forming a pattern for a semiconductor device, that includes: etching a second insulating layer to expose a portion of an underlying first insulating layer on a semiconductor substrate; forming a third insulating layer on the entire surface of the substrate; etching the third insulating layer and the first insulating layer using the second insulating layer as an etch barrier, to define a pattern region; forming a layer of material on the entire surface of the substrate so as to fill the pattern region; and planarizing so as to expose the first insulating layer.  
      Furthermore, the first insulating layer and the third insulating layer respectively have a high etching selectivity to the second insulating layer. Preferably, the first insulating layer and the third insulating layer comprise an oxide layer, and the second insulating layer comprises a nitride layer. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      A further understanding of nature and advantage of the present invention will become apparent by reference to the remaining portions of the specification and drawings, in which:  
       FIGS. 1A-1F  are cross-sectional views describing a method of forming a fine pattern for a semiconductor device according to an embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which a preferred embodiment of the invention is shown. The present invention may, however, be embodied in many different forms, and should not be construed as being limited to the embodiment set forth herein.  
      A method of forming a fine pattern for a semiconductor device according to an embodiment of the present invention will be described with reference to  FIGS. 1A-1F .  
      As shown in  FIG. 1A , a first insulating layer  11  is formed on a semiconductor substrate  10 , and a second insulating layer  12  having high etching selectivity to the first insulating layer  11  is then formed on the first insulating layer  11 . Preferably, the first insulting layer  11  is formed of an oxide layer such as a silicon oxide (SiO 2 ) and the second insulating layer  12  is formed of a nitride layer such as a silicon nitride (SiN). More preferably, the oxide layer is formed by thermal oxidation process and the nitride layer is formed by Chemical Vapor Deposition (CVD), Low Pressure (LP)-CVD or Plasma Enhanced (PE)-CVD.  
      Thereafter, a first photoresist layer is coated on the second insulating layer  12 , is exposed by a conventional exposure apparatus employing an I-line light source, and is developed, to form a first photoresist pattern  13  exposing the portion of the second insulating layer  12 . Here, an anti-reflective coating (ARC or ARC layer) may be formed under the first photoresist pattern  13  (not shown in  FIG. 1A ).  
      As shown in  FIG. 1B , the exposed portion of the second insulating layer  12  is etched by an etching process using the first photoresist pattern  13  as an etch mask and the first insulating layer  11  as an etch barrier, to expose the portion of the first insulating layer  11 . The first photoresist  13  is then removed by a well-known method.  
      As shown in  FIG. 1C , a third insulating layer  14  having high etching selectivity to the second insulating layer  12  is formed on the entire surface of the substrate. Preferably, the third insulating layer  14  is formed of an oxide layer such as silicon oxide (SiO 2 ), the same as the first insulating layer  11 . At least a portion of the third insulating layer  14  has a lower surface that is substantially coplanar with a lower surface of the second insulating layer  12 .  
      As shown in  FIG. 1D , a second photoresist layer is coated on the third insulating layer  14 , is exposed by a conventional exposure apparatus employing an I-line light source, and is developed, to form a second photoresist pattern  15  exposing the portion of the third insulating layer  14 . Here, an Anti-Reflective Coating (ARC) layer may be formed under the first photoresist pattern  15  (not shown in  FIG. 1D ).  
      As shown in  FIG. 1E , the third insulating layer  14  and the first insulating layer  11  are etched by an etching process using the second photoresist pattern  15  as an etch mask and the second insulating layer as an etch barrier so as to expose the portion of the substrate  10 . Generally, all of the portion(s) of the third insulating layer  14  that overlie the second insulating layer  12  are removed, leaving only portion(s) of the third insulating layer  14  that are substantially coplanar with the second insulating layer  12 . As a result, a pattern region  16  having a fine width W is defined. The fine width W is smaller than a minimum width that can be formed by the conventional exposure apparatus employing an I-line light source.  
      As shown in  FIG. 1F , the second photoresist pattern  15  is removed by a well-known method. A copper (Cu) layer as a material layer for use as a metallization structure is then deposited on the entire surface of the substrate so as to fill the pattern region  16 . Thereafter, a planarization process is performed by Chemical Mechanical Polishing (CMP) so as to expose the first insulating layer  11 , thereby forming a copper pattern  17  having the fine width W. For example, a single, non-selective CMP process can planarize the fill material and both of the second and third insulating layers  12  and  14 , in which case disappearance of the second insulating layer  12  can serve as an endpoint. Alternatively, planarizing may comprise multiple steps; for example, the fill material may be removed from regions or areas outside the pattern region  16  by CMP, second and third insulating layers  12  and  14  may be removed by selective etching (in which case third insulating layer  14  comprises a material different from first insulating layer  11 ), and the fill material may be made substantially coplanar with first insulating layer  11  by a second CMP step.  
      In the present invention as described above, the copper pattern having the fine width is formed by the conventional exposure apparatus using the I-line light source. As a result, the present invention can easily fabricate a high integration density device. Furthermore, the present invention can lower fabrication cost as there is no need to use a new exposure apparatus. Furthermore, the present invention can prevent collapse of a photoresist pattern as there is no need to use a double exposure method, to improve yield and reliability of a device.  
      While the present invention has been described in detail with reference to the preferred embodiments, it is to be understood that the invention is not limited to be disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.