Abstract:
A method for repairing photomask pattern defects includes patterning a target layer on a transparent substrate, thereby forming first patterns, detecting a defect die including a defect pattern by inspecting the first patterns; forming a mask layer on the transparent substrate, forming a mask pattern that selectively exposes the defect die by performing an exposure process and a development process on the mask layer; etching the target layer of the exposed defect die using the mask pattern as an etching mask to expose the transparent substrate, depositing a target layer on the exposed defect die of the transparent substrate, and patterning the deposited target layer, thereby forming a second pattern on the defect die.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     Priority to Korean patent application number 10-2006-0095712, filed on Sep. 29, 2006, the disclosure of which is incorporated by reference in its entirety, is claimed. 
     BACKGROUND OF THE INVENTION 
     The invention relates to a method for manufacturing a photomask, and more particularly to a method for repairing photomask pattern defects. 
     A photolithography process, which is one process for manufacturing semiconductor devices, uses a photomask having a pattern to be transcribed on a wafer. The photomask has circuit and design patterns of the semiconductor devices The circuit and design patterns of the photomask are transcribed on the wafer by an exposure process. In the exposure process and development process performed to manufacture the photomask, particles may be generated and remain on the surface of a light blocking layer formed on the photomask. The particles remaining on the surface of the light blocking layer may cause defects such as a bridge between patterns of the light blocking layer in the subsequent etching process. Such defects may be transcribed on the wafer in the photolithography process, thereby causing a photomask defect and also forming a defect pattern on a semiconductor substrate. 
     When the defect pattern is formed in a photomask manufacturing process, a process of repairing the defect pattern is performed. However, as the line width of the semiconductor device becomes smaller, defects occur more easily, and it is difficult to completely eliminate pattern defects. Further, the defect pattern can be repaired into a normal pattern by repeating the steps of repairing the defect pattern, cleaning and inspecting. However, if there is a large defect in the defect pattern, the entire photomask is rejected and a new photomask should be reproduced. Thus, a method of completely eliminating the residue defects caused by the particles in the photomask manufacturing process has been studied. 
     BRIEF SUMMARY OF THE INVENTION 
     The invention provides a method for repairing photomask pattern defects including: forming first patterns on a transparent substrate; detecting a defect die including a defect pattern by inspecting the first patterns; forming a mask pattern that selectively exposes the defect die on the transparent substrate; removing the defect pattern of the defect die using the mask pattern as an etching mask; forming a material layer for forming a second pattern on the defect die of the transparent substrate; removing the mask pattern; and forming the second pattern on the defect die by patterning the material layer. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other objects, features, and advantages of the invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: 
         FIGS. 1 to 9  illustrate a method for repairing photomask pattern defects according to the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Preferred embodiments of the invention are described in detail with reference to the accompanying drawings. These embodiments are used only for illustrative purposes, and the invention is not limited thereto. 
     First, a pattern to be transcribed on a wafer is formed on a mask substrate. Specifically, from bottom to top, a molybdenum silicon nitride (MoSiON) layer, a chromium (Cr) layer and a resist layer are sequentially formed on a transparent quartz substrate. A resist layer pattern is formed by performing an exposure process generally using an electron beam (e-beam) and a development process. The chromium (Cr) layer is etched through an etching mask of the resist layer pattern to form a chromium (Cr) layer pattern, and the resist layer pattern is removed. 
     A molybdenum silicon nitride (MoSiON) layer pattern is formed by using the chromium (Cr) layer pattern as an etching mask. Meanwhile, align keys may be formed at edges of the mask substrate for exact patterning. The resist layer pattern, the chromium (Cr) layer pattern and the molybdenum silicon nitride (MoSiON) layer pattern can be exactly formed using align keys as a reference point. Although a phase shift mask is used for the photomask In this embodiment, the embodiment of the invent-on may be applied to a binary mask. 
     When patterning the resist layer, a residue of the resist layer may be formed on the surface of the chromium (Cr) layer, whereby a defect pattern may be generated and a pattern may not be formed due to process abnormalities and the like. Further, a phase shift effect may not be obtained due to a residue of the chromium (Cr) layer formed on the surface of the molybdenum silicon nitride (MoSiON) layer, thereby causing a minimal line width difference and a bridge defect. In order to detect the defect pattern, a die including the defect pattern is detected by a die-to-die inspection method for comparing each die with a corresponding die on the same phase shift mask. 
     Referring to  FIG. 1 , a number of fields are formed on a transparent substrate  100  and each field may include a number of dies. The die including the defect pattern is detected by the die-to-die inspection method for comparing respective dies. Reference numeral  200  denotes defect dies including the defect pattern and reference numeral  300  denotes normal dies which are normally patterned. In this case, patterns formed on the normal dies  300  may be formed by patterning the molybdenum silicon nitride (MoSiON) layer and the chromium (Cr) layer. 
     Referring to  FIG. 2A , a resist layer  400  is coated on the transparent substrate  100  and then the defect dies  200  are selected. A photolithography process is performed to form a pattern of the resist layer  400  exposing the defect dies  200 . The molybdenum silicon nitride (MoSiON) layer and the chromium (Cr) layer patterns formed on the exposed defect dies  200  are etched using the pattern of the resist layer  400  exposing the defect dies  200  as an etching mask. This step is illustrated in  FIG. 2B , a cross-section through the top two defect dies  200  of the transparent substrate  100  (see  FIG. 2A ), shown after the defect dies  200  have been etched. When the defect dies  200  are detected between the normal dies  300 , as shown in  FIG. 2B , the patterns of the molybdenum silicon nitride (MoSiON) layer  210  and the chromium (Cr) layer  220  formed on the normal dies  300  are protected by the pattern of the resist layer  400  and only the defect dies  200  on the transparent substrate  100  are exposed. 
     Referring to  FIG. 3 , a molybdenum silicon nitride (MoSiON) layer  230  is redeposited on the transparent substrate  100  exposed by the pattern of the resist layer  400  by partial sputtering. Referring to  FIG. 4A , a chromium (Cr) layer  240  is redeposited on the molybdenum silicon nitride (MoSiON) layer  230  exposed by the pattern of the resist layer  400 . This is illustrated in  FIG. 4B , a cross sectional view analogous to  FIG. 2B . 
       FIG. 5  illustrates the partial sputtering process. The transparent substrate  100  is loaded into a chamber  500  of a sputtering device. Then, argon (Ar) gas is introduced into the chamber  500 . A mask  410  for selectively exposing the transparent substrate  100  is formed on the transparent substrate  100 . A chromium (Cr) target is sputtered in Ar plasma while rotating the transparent substrate  100 , thereby forming the chromium (Cr) layer  240  on the exposed transparent substrate  100 . 
     Referring to  FIG. 6 , the resist layer pattern  400  exposing the defect dies  200  is removed. The resist layer may be removed in, for example, oxygen plasma during an ashing process, thereby exposing the normal dies  300  in which normal patterns are formed on the transparent substrate  100  and the chromium (Cr) layer  240  redeposited on the defect dies  200 . Before the chromium (Cr) layer pattern  240  is formed on the transparent substrate  100 , the align key may be formed on the transparent substrate  100  for exact patterning. 
     Meanwhile, when a mask layer is coated for the following patterning process, the mask layer may be also coated on a region in which the align key is formed. In this case, the align key would be undesirably obscured in the subsequent patterning step. Thus, as shown in  FIG. 7 , blocking bars  610  are formed to protect align keys  600  disposed at a specified region, for example, the corners of the transparent substrate  100 . The blocking bars  610  serve to protect the align keys  600  for exactly aligning the redeposited molybdenum silicon nitride (MoSiON) layer  230  and chromium (Cr) layer  240  when the mask layer is coated. For example, each blocking bar  610  may be formed of plastic in a bar shape having a height of about 5 mm around each align key  600  on the transparent substrate  100 . 
     Referring to  FIG. 8 , a mask layer  700  is coated over the entire surface of the transparent substrate  100  using a spin coating method. In this case, the blocking bars  610  formed around the align keys  600  can prevent the align keys  600  from being coated with the mask layer  700 . 
     Referring to  FIG. 9A , a mask layer pattern is formed by performing the exposure process using the electron beam (e-beam) and the development process. A normal pattern  300  is formed by patterning the molybdenum silicon nitride (MoSiON) layer  230  and the chromium (Cr) layer  240  formed on the defect dies  200 , and the mask layer  700  is removed. In the exposure process using the e-beam, the pattern may be formed at an exact position without being tilted based on the align keys. This is illustrated in  FIG. 9B , a cross sectional view analogous to  FIG. 2B . As shown in  FIG. 9B , the molybdenum silicon nitride (MoSiON) layer  230  and the chromium (Cr) layer  240  formed on the defect dies  200  are patterned using the align keys  600  as a reference, thereby forming the same pattern as that formed on the normal dies  300 . 
     Although preferred embodiments of the invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as defined in the accompanying claims.