2  US 7,129,023 B2  1  PHOTORESIST POLYMER AND  PHOTORESIST COMPOSITION  CONTAINING THE SAME  BACKGROUND  Photoresist polymers and photoresist compositions con› taining the same are disclosed that can improve profile of a  photoresist pattern, without the need for any dummy pat› terns and which improve etch resistance during pattern  formation.  As manufacturing processes of semiconductor devices  become more complicated and the degree of integration  increases, methods for forming fine patterns are needed.  Since it is difficult to obtain a fine pattern with conventional  photolithography using KrF (248 nm), photolithography  using far-infrared light source such as ArF (193 nm) has  been developed. However, photoresist materials that have  been used in ArF photolithography are more difficult to use  than conventional photoresist materials. Specifically, as the  critical dimension CD has been decreased by the high  integration of semiconductor devices, the aspect ratio of a  pattern is increased which can cause collapse the photoresist  pattern  12  on the semiconductor substrate  11  as shown in  FIG.  1.  There are many processes for forming layers of semicon› ductors. As the size of a pattern becomes smaller, a pattern  in the outer region of a field or a block becomes remarkably  smaller because the pattern in the outer region receives a  relatively larger amount of light energy in comparison with  the inside of the field of the block where patterns are  arranged more uniformly and densely.  In order to prevent the outer portions of the pattern from  being reduced in size, the amount of energy or an exposure  condition of lens has been regulated. However, this conven› tional method does not solve the problem.  In addition, problems arise when the margins of DOF  (Depth of Focus) and EL (Energy Latitude) become smaller  as the pattern becomes smaller. However, these problems  carmot be solved by using the change of exposure condi› tions. Also, it is difficult to secure etching resistance because  the thickness of the photoresist film is reduced to prevent  pattern collapse.  Disclosed herein are photoresist polymers and photoresist  compositions comprising the same that can improve a profile  of an outer region of a field or a block which receives a  relatively large amount of light when a pattern is formed.  The disclosed photoresist polymers and compositions also  enhance etching resistance.  Disclosed herein is a method for forming a phtoresist  pattern using the disclosed photoresist composition. Also,  disclosed herein is a semiconductor device obtained by the  disclosed method.  For a more complete understanding of this disclosure,  reference should be made to the following detailed descrip› tion and accompanying drawings, wherein:  FIG.  1  is a diagram illustrating a pattern formed using a  conventional photoresist polymer; and  In the disclosed photoresist polymer, a monomer consti› tuting the repeating unit "a" has a long chain by introducing  linear or branched C$_{3}$-C$_{10 }$ alkylene structure to prevent  steric hindrance between end groups, thereby facilitating  polymerization of polymers. Also, the monomer of the  repeating unit "a" contains a large percentage of silicon and  carbon to improve hardness of photoresist. Additionally,  increase of etching resistance due to introduction of a silicon  group allows a photoresist film having a lower thickness to  serve as an etching mask in an etching process using a CF  4  plasma gas.  FIG.  2  is a diagram illustrating a process for obtaining an  improved pattern profile of an outer region of a field using  a disclosed photoresist polymer.  DETAILED DESCRIPTION OF THE  PRESENTLY PREFERRED EMBODIMENTS  wherein Ri, R$_{2 }$ and R$_{3 }$ are individually Hor CH$_{3}$ ;  R$_{4 }$ is linear or branched C$_{3}$-C$_{10 }$ alkylene group;  R$_{5}$ , R$_{6 }$ and R$_{7 }$ are individually C$_{1}$-C$_{3 }$ alkoxy group;  R$_{8}$ ,  R$_{9 }$ and R$_{10 }$are individually H or CH$_{3}$ ;  R$_{11 }$ is linear or branched C$_{1}$-C$_{3 }$ alkyl group; R$_{12 }$ 1s  hydrogen; and,  a ratio of a:b:c:d falls within a range of 20-40 mo!  %:20-35 mo! %:15-25 mo! %:15-20 mo!%.  The polymer has a molecular weight ranging from 1,000  to 10,000, preferably from 1,500 to 4,000.  Preferably, the polymerization repeating unit represented  by Formula 1 is represented by Formula la:  Formula la  A disclosed photoresist polymer comprises a polymeriza› tion repeating unit represented by Formula  1:  °  Formula 1  BRIEF DESCRIPTION OF THE DRAWINGS  SUMMARY OF THE DISCLOSURE  1.  Technical Field  2. Description of the Related Art  $^{0 }$\ $_{R11 }$ Formula 1  0  Formula la  0  s•  H3CO/ j"ocH3  OCH3 