Jan. 13,  2011  6  US 2011/0008728 Al  -continued  (al"-2)  -continued  (al"-6)  (al"-3)  (al"-4)  (al"-5)  (pl)  [Chemical Formula 4]  In the formulas, R represents a hydrogen atom, an alkyl group  of 1 to 5 carbon atoms or a halogenated alkyl group of 1 to 5  carbon atoms; and R $^{15 }$and R $^{16 }$each independently represent  an alkyl group (which may be linear or branched, and pref› erably has 1 to 5 carbon atoms).  [0098]  In general formulas (al"-1) to (al"-6) above, the  alkyl group or halogenated lower alkyl group for R are the  same as the alkyl group of 1 to 5 carbon atoms or halogenated  alkyl group of 1 to 5 carbon atoms which can be bonded to the  a-position of the aforementioned acrylate ester.  [0099]  An "acetal-type acid dissociable, dissolution inhib› iting group" generally substitutes a hydrogen atom at the  terminal of an alkali-soluble group such as a carboxy group or  hydroxyl group, so as to be bonded with an oxygen atom.  When acid is generated upon exposure, the generated acid  acts to break the bond between the acetal-type acid disso› ciable, dissolution inhibiting group and the oxygen atom to  which the acetal-type, acid dissociable, dissolution inhibiting  group is bonded.  [0100]  Examples of acetal-type acid dissociable, dissolu› tion inhibiting groups include groups represented by general  formula (pl) shown below.  In the formula, R 11  and R 21  each independently represent a  hydrogen atom or an alkyl group of 1 to 5 carbon atoms; n  represents an integer of Oto 3; and Y represents an alkyl group  of 1 to 5 carbon atoms or an aliphatic cyclic group.  [0101]  In general formula (pl) above, n is preferably an  integer of Oto 2, more preferably O or 1, and most preferably  0.  [0102]  As the alkyl group ofl to 5 carbon atoms for R$^{11 }$and  R 21 , the same alkyl groups of 1 to 5 carbon atoms as those  described above for R can be used, although a methyl group or  ethyl group is preferable, and a methyl group is particularly  desirable.  [0103]  In the present invention, it is preferable that at least  one ofR $^{11 }$and R $^{21 }$be a hydrogen atom. That is, it is preferable  O=C  I  0  Rl5  Rl6  RI’  I  -c-o+cHrt,;-Y  I  R2’  O=C  I  0  Rl5  Rl6 