Marker structure and method of forming the same

Abstract

The invention relates to a marker structure for optical alignment of a substrate and provided thereon. The marker structure has a first reflecting surface at a first level and a second reflecting surface at a second level. A separation between the first level and the second level determines a phase depth condition. The marker structure further has an additional structure. The additional structure is arranged to modify the separation during manufacture of the marker structure. The invention further relates to a method of forming such a marker structure.

1 - 30 . (canceled) 
     
     
         31 . A method of alignment of a substrate in a lithographic projection apparatus including a support structure configured to support a patterning device that serves to impart a beam of radiation with a pattern in its cross-section, a substrate table configured to hold a substrate, a projection system configured to expose the patterned beam on the substrate, a substrate alignment system comprising at least one light source, a sensor device, and a processor, the substrate alignment system being configured to detect a position of the substrate relative to a position of the patterning device, wherein the method is performed by the substrate alignment system and comprises:
 generating at least one alignment beam of radiation aimed at a marker structure comprising:
 a first reflecting surface at a first level; 
 a second reflecting surface at a second level, a separation between the first level and a second level determining a phase depth condition; and 
 an additional structure, constructed and arranged to modify the separation during manufacture of said marker structure; 
   detecting an optical signal reflected from the marker structure;   determining alignment information from the optical signal, the alignment information comprising information relating a position of the substrate to the sensor device.   
     
     
         32 . The method according to claim  1 , wherein said additional structure comprises a layer of filler material positioned at one side of both the first reflecting surface and the second reflecting surface. 
     
     
         33 . The method according to claim  2 , wherein the filler material comprises tungsten. 
     
     
         34 . The method according to claim  1 , wherein the additional structure is positioned at a level between the first reflecting surface and the second reflecting surface. 
     
     
         35 . The method according to claim  4 , wherein the additional structure is positioned such that it is covered by the second reflecting surface. 
     
     
         36 . The method according to claim  4 , wherein the additional structure comprises a plurality of spaced cavities filled with filler material. 
     
     
         37 . The method according to claim  4 , wherein the additional structure comprises at least one of tungsten and poly-silicon. 
     
     
         38 . The method according to claim  4 , wherein the first reflecting surface corresponds to a surface of the substrate on which the marker structure is provided. 
     
     
         39 . The method according to claim  4 , wherein on top of the second reflecting surface an additional layer is provided, on top of which a functional layer is provided. 
     
     
         40 . The method according to claim  9 , wherein the additional layer is a storage node dielectric, and the functional layer is a hard mask layer. 
     
     
         41 . The method according to claim  10 , wherein the hard mask layer is an amorphous carbon mask layer. 
     
     
         42 . The method according to claim  9 , wherein the additional layer is an additional contact layer, and the functional layer is a color filter. 
     
     
         43 . The method according to claim  12 , wherein the color filter is substantially transparent for radiation with a wavelength between  620  nm and  780  nm. 
     
     
         44 . A method of forming a marker structure on a substrate, the method comprising:
 forming a first layer on a substrate and creating a first pattern therein, the first pattern including a periodic structure including a series of lines with interposed trenches;   forming a second layer on top of the first pattern in the first layer, and polishing the second layer until the series of lines in said first layer appears; and   forming a third layer on top of the second layer, the third layer being reflective for radiation of a certain wavelength, wherein a thickness of said second layer being selected such that a certain separation between a surface of said third layer on top of said series of lines and a surface of said third layer at the bottom of said interposed trenches is established.   
     
     
         45 . The method according to claim  14 , wherein the first pattern further comprises a plurality of holes and the method further comprises, before providing the second layer, filling the plurality of holes with a filler material. 
     
     
         46 . A method of forming a marker structure on a substrate, the method comprising:
 providing a substrate with a surface reflective for radiation with a certain wavelength, the surface of the substrate comprising a first reflecting surface of the marker structure;   providing a first layer on the reflective surface of said substrate, the first layer comprising an electrically insulating layer;   forming an additional structure in the first layer;   forming a second layer on top of the first layer, the second layer comprising a filler material;   polishing the second layer until the additional structure appears, so as to form a substantially plain surface;   forming a third layer on top of the substantially plain surface, and forming a first pattern therein, the first pattern comprising a periodic structure comprising elements reflective for radiation with the certain wavelength and comprising a second reflecting surface of said marker structure.   
     
     
         47 . The method according to claim  16 , wherein the reflective elements of the periodic structure are positioned such that they substantially cover the additional structure. 
     
     
         48 . The method according to claim  16 , wherein the additional structure comprises at least one filled cavity. 
     
     
         49 . The method according to claim  16 , wherein the additional structure comprises at least one of tungsten and poly-silicon. 
     
     
         50 . The method according to claim  16 , wherein the method further comprises forming a fourth layer as additional contact layer on top of the third layer provided with the first pattern, and forming a functional layer as fifth layer on the fourth layer.