US 9,097,971 B2  200  199  Examples of suitable organic carboxylic acids include ace› tic acid, malonic acid, citric acid, malic acid, succinic acid,  benzoic acid, and salicylic acid.  Examples of phosphorus oxo acids or derivatives thereof  include phosphoric acid, phosphonic acid and phosphinic  acid. Among these, phosphonic acid is particularly desirable.  Examples of phosphorous oxo acid derivatives include  esters in which a hydrogen atom within the above-mentioned  phosphorous oxo acids is substituted with a hydrocarbon  group. Examples of the hydrocarbon group include an alkyl  group of 1 to 5 carbon atoms and an aryl group of 6 to 15  carbon atoms.  Examples of phosphoric acid derivatives include phospho- ric acid esters such as di-n-butyl phosphate and diphenyl  phosphate.  Examples of phosphonic acid derivatives include phospho› nic acid esters such as dimethyl phosphonate, di-n-butyl  phosphonate, phenyl phosphonate, diphenyl phosphonate  and dibenzyl phosphonate.  Examples of phosphinic acid derivatives include phe› nylphosphinic acid and phosphinic acid esters.  As the component (E), salicylic acid is particularly desir- able.  As the component (E), one type may be used alone, or two  or more types may be used in combination.  The component (E) is typically used in an amount within a  range from 0.01 to 5.0parts by weight, relative to l00parts by  weight of the component (A).  Furthermore, in the resist composition of the present inven› tion, for preventing any deterioration in sensitivity, and  improving the resist pattern shape and the post exposure  stability of the latent image formed by the pattern-wise expo- sure of the resist layer, at least one compound (E) (hereafter  referred to as the component (E)) selected from the group  consisting of an organic carboxylic acid, or a phosphorus oxo  acid or derivative thereof can be added.  The resist composition may further include a fluorine addi› tive (hereafter, referred to as "component (F)") for imparting  water repellency to the resist film. As the component (F), for  example,  a  fluorine-containing  polymeric  compound  described in Japanese Unexamined Patent Application, First  Publication No. 2010-002870.  Specific examples of the component (F) include polymers  having a structural unit (fl) represented by general formula  (fl-1) shown below. As such polymer, a polymer (homopoly- mer) consisting of a structural unit (fl); a copolymer of a  structural unit represented by formula (fl-1) shown below  and the aforementioned structural unit (al); and a copolymer  of a structural unit represented by the formula (fl-1) shown  below, a structural unit derived from acrylic acid or meth› acrylic acid and the aforementioned structural unit (al) are  preferable. As the structural unit (al) to be copolymerized  with a structural unit represented by formula (fl-1) shown  below, a structural unit represented by the aforementioned  formula (al-1) is preferable, and a structural unit represented  by the aforementioned formula (al-1-32) is particularly  desirable.  When the component (F) is a fluorine-containing poly› meric compound (polymeric compound), the weight average  molecular weight (Mw) (the polystyrene equivalent value  determined by gel permeation chromatography) of the com› ponent (F) is not particularly limited, but is preferably 1,000  Among these, as R  2 ",  a fluorinated hydrocarbon group of 1  to 5 carbon atoms is particularly preferable, and a methyl  group, -CH$_{2}$-CF$_{3}$ ,  ----CH$_{2}$----CF$_{2}$----CF$_{3}$ ,  ----CH(CF$_{3}$ ) 2 ,  ----CH$_{2}$----CH$_{2}$----CF $_{3}$ ,  and  -CH$_{2}$-CH$_{2}$-CF  $_{2}$----CF $_{2}$ - CF $_{2}$-CF  3  are most preferable.  It is preferable that the hydrocarbon group having a fluo› rine atom has 25% or more of the hydrogen atoms within the  hydrocarbon group fluorinated, more preferably 50% or  more, and most preferably 60% or more, as the hydrophobic- ity of the resist film during immersion exposure is enhanced.  The hydrocarbon group containing a fluorine atom may be  linear, branched or cyclic, and preferably has 1 to 20 carbon  atoms, more preferably 1 to 15 carbon atoms, and most pref› erably 1 to 10 carbon atoms.  In formula (fl-1), R "  represents an organic group contain› ing a fluorine atom, and is preferably a hydrocarbon group  containing a fluorine atom.  In formula (fl-1), al represents an integer of 1 to 5, pref- erably an integer of 1 to 3, and more preferably 1 or 2.  2 In formula (fl-1), examples of the halogen atom for R 51  and R$^{52 }$include a fluorine atom, a chlorine atom, a bromine  atom and an iodine atom, and a fluorine atom is particularly  desirable. Examples of the alkyl group of 1 to 5 carbon atoms  for R$^{51 }$and R$^{52 }$include the same alkyl group of 1 to 5 carbon  atoms for R defined above, and a methyl group or an ethyl  group is preferable. Specific examples of the halogenated  alkyl group ofl to 5 carbon atoms represented by R$^{51 }$andR 52  include groups in which part or all of the hydrogen atoms of  the aforementioned alkyl groups of 1 to 5 carbon atoms have  been substituted with halogen atoms. Examples of the halo› gen atom include a fluorine atom, a chlorine atom, a bromine  atom and an iodine atom, and a fluorine atom is particularly  desirable. Among these, as R $^{51 }$and  R 52 ,  a hydrogen atom, a  fluorine atom or an alkyl group of 1 to 5 carbon atoms is  preferable, and a hydrogen atom, a fluorine atom, a methyl  group or an ethyl group is more preferable.  <Component (E)>  <Component (F)>  In formula (fl-1), R is the same as defined above. As R, a  hydrogen atom or a methyl group is preferable.  In the formula, R is the same as defined above; R$^{51 }$and R 52  each independently represents a hydrogen atom, a halogen  atom, an alkyl group of 1 to 5 carbon atoms or a halogenated  alkyl group of 1 to 5 carbon atoms, provided that the plurality  ofR$^{51 }$and R$^{52 }$may be the same or different; al represents an  integer of 1 to 5; and R 2 "  represents an organic group con- taining a fluorine atom.  [Chemical Formula 101]  (fl-1)  /  al  O=C  \  0  I  R2• 