Jan. 13, 2011  64  US 2011/0008728 Al  [0762]  The alkyl group preferably has 1 to 15 carbon atoms,  and more preferably 1 to 10 carbon atoms, because the coat› ability of the resist composition becomes satisfactory. Spe› cific examples include an ethyl group, a propyl group, an  isopropyl group, an n-butyl group, an isobutyl group, an  n-pentyl group, an isopentyl group, a cyclopentyl group and a  hexyl group, and an n-butyl group and an isopentyl group are  particularly desirable.  [0763]  The halogen atom, with which hydrogen atoms of  the alkyl group may be substituted, is preferably a fluorine  atom.  [0764]  The aryl group for R$^{73 }$and R$^{74 }$is not particularly  limited. For example, an aryl group having 6 to 12 carbon  atoms may be used in which part or all of the hydrogen atoms  of the aryl group may or may not be substituted with alkyl  groups, alkoxy groups, halogen atoms, or the like.  [0765]  The aryl group is preferably an aryl group having 6  to 10 carbon atoms because it can be synthesized at a low cost.  Specific examples thereof include a phenyl group, a benzyl  group and a naphthyl group.  [0766]  The alkyl group, with which hydrogen atoms of the  aryl group may be substituted, is preferably an alkyl group  having 1 to 5 carbon atoms, and more preferably a methyl  group, an ethyl group, a propyl group, an n-butyl group, or a  tert-butyl group.  [0767]  The alkoxy group, with which hydrogen atoms of  the aryl group may be substituted, is preferably an alkoxy  group having 1 to 5 carbon atoms, and more preferably a  methoxy group or an ethoxy group.  [0768]  The halogen atom, with which hydrogen atoms of  the aryl group may be substituted, is preferably a fluorine  atom.  [0769]  Alternatively, in general formula (sl’-1), R 73  and  R$^{74 }$may be bonded to each other to form a ring.  [0770]  In this case, R$^{73 }$and R$^{74 }$each independently repre› sents a linear or branched alkylene group (preferably an alky› lene group of 1 to 10 carbon atoms) and the terminal ofR 73  and the terminal of R$^{74 }$are bonded to each other to form a  ring. Further, a carbon atom of the alkylene group may be  substituted with an oxygen atom.  [0771]  Specific examples of such ether-based organic sol› vents include 1,8-cineole, tetrahydrofuran and dioxane.  [0772]  The boiling point (at normal pressure (atmospheric  pressure)) of the component (S2) is preferably within a range  from 30 to 300°  C., more preferably from 100 to 200°  C., and  still more preferably from 140 to 180°  C. When the boiling  point of the component (S2) is at least as large as the lower  limit of the above-mentioned temperature range, the compo› nent (S) hardly evaporates during the spin coating process  when applying the resist composition of the present inven› tion, thereby suppressing coating irregularities and improv› ing the resulting coating properties. On the other hand, when  the boiling point of the component (S2) is no more than the  upper limit of the above-mentioned temperature range, the  component (S) is satisfactorily removed from the resist film  by a prebake (PAB) treatment, thereby improving formability  of the resist film. Further, when the boiling point of the  component (S2) is within the above-mentioned temperature  range, the effect of reducing the thickness loss of the resist  patterns and the stability of the composition upon storage are  further improved. The above-mentioned temperature range  for the boiling point of the component (S2) is also preferable  from the viewpoints of the heating temperature required in the  PAB step and/or PEB step.  [0773]  Specific examples of the component (S2) include  1,8-cineole (boiling point: 176°  C.), dibutyl ether (boiling  point: 142°  C.), diisopentyl ether (boiling point: 171 °  C.),  dioxane (boiling point: 101 °  C.), anisole (boiling point: 155°  C.), ethylbenzyl ether (boiling point: 189°  C.), diphenyl ether  (boiling point: 259°  C.), dibenzyl ether (boiling point: 297°  C.), phenetole (boiling point: 170°  C.), butylphenyl ether,  tetrahydrofuran (boiling point: 66° C.), ethylpropyl ether  (boiling point: 63°  C.), diisopropyl ether (boiling point: 69°  C.), dihexyl ether (boiling point: 226°  C.), dipropyl ether  (boiling point: 91 °  C.), and cresylmethyl ether.  [077 4]  These components (S2) can be used either alone, or  in combinations of two or more different solvents.  [0775]  In the present invention, the component (S2) is pref› erably a cyclic or chain-like, ether-based organic solvent  because the effect of reducing the thickness loss of the resist  patterns becomes satisfactory, and it is particularly desirable  that the component (S2) be at least one member selected from  the group consisting of 1,8-cineole, dibutyl ether and diiso› pentyl ether.  [0776]  [Component (S3)]  [0777]  In addition to the component (S 1 ), or in addition to  the components (Sl) and (S2), the component (S) may also  include an organic solvent other than the components (Sl)  and (S2) (hereafter, referred to as "component (S3)"), as long  as the effects of the present invention are not impaired.  [0778]  The component (S3) may be any organic solvent  which can dissolve the resist materials to give a uniform  solution, and any one or more kinds of organic solvents can be  appropriately selected from those which have been conven› tionally known as solvents for a chemically amplified resist.  [0779]  By further including the component (S3), the solu› bility of the components (A), (B) and the like, and other  properties can be adjusted.  [0780]  Examples of the component (S3) include lactones  such as y-butyrolactone; ketones such as acetone, methyl  ethyl ketone, cyclohexanone, methyl-n-pentyl ketone, methyl  isopentyl ketone, and 2-heptanone; polyhydric alcohols, such  as ethylene glycol, diethylene glycol, propylene glycol and  dipropylene glycol; compounds having an ester bond, such as  ethylene glycol monoacetate, diethylene glycol monoacetate,  propylene glycol monoacetate, and dipropylene glycol  monoacetate; polyhydric alcohol derivatives including com› pounds having an ether bond, such as a monoalky !ether (e.g.,  monomethylether,  monoethylether,  monopropylether or  monobutylether) or monophenylether of any of these polyhy› dric alcohols or compounds having an ester bond (among  these, propylene glycol monomethyl ether acetate (PGMEA;  boiling point: 146°  C.) and propylene glycol monomethyl  ether (PGME; boiling point: 120°  C.) are preferable); esters  such as methyl lactate, ethyl lactate (EL), methyl acetate,  ethyl acetate, butyl acetate, methyl pyruvate, ethyl pyruvate,  methyl methoxypropionate, and ethyl ethoxypropionate; aro› matic organic solvents such as ethylbenzene, diethylbenzene,  pentylbenzene, isopropylbenzene, toluene, xylene, cymene  and mesitylene; dimethyl sulfoxide (DMSO); and alcohol› based organic solvents having a boiling point of less than  150°  C. (hereafter, referred to as "component (S3a)"), such as  n-pentyl alcohol (boiling point: 138.0°  C.), s-pentyl alcohol  (boiling point: 119.3°  C.), t-pentyl alcohol (boiling point:  101.8° C.), isopentyl alcohol (boiling point: 130.8° C.),  isobutanol (also called isobutyl alcohol or 2-methyl-1-pro› panol) (boiling point: 108°  C.), isopropyl alcohol (boiling  point: 82.3°  C.), 2-ethylbutanol (boiling point: 147°  C.), neo-