US 9,235,123 B2  72  71  -continued  [Chemical formula 33]  In the formula, R"’ is the same as that described above.  The constituent unit (a4) which the component (Al) has  may be either one kind or two or more kinds.  In the case where the component (Al) has the constituent  unit (a4), a proportion of the constituent unit (a4) is preferably  1 mo! % to 30 mo! %, and more preferably 3 mo! % to 20  mo! % relative to a total sum of all of the constituent units  constituting the component (Al).  When the proportion of the constituent unit (a4) is the  preferred lower limit value or more, the effects due to the fact  that the constituent unit (a4) is contained are sufficiently  obtained, and when the proportion of the constituent unit ( a4)  is not more than the preferred upper limit value, a balance  with other constituent units is easily taken.  In the resist composition ofthis aspect, the component (A)  contains the high-molecular weight compound (Al) having  the constituent unit (a0), and specific examples of the com- ponent (Al) include a high-molecular weight compound  composed of a repeating structure of the constituent unit ( a0),  the constituent unit (al), and the constituent unit (a2).  A mass average molecular weight (Mw) ( as converted into  polystyrene by means of gel permeation chromatography  (GPC)) of the component (Al) is not particularly limited, but  it is preferably 1,000 to 50,000, more preferably 1,500 to  30,000, and most preferably 2,000 to 20,000.  When the Mw of the component (Al) is not more than the  preferred upper limit value of the foregoing range, sufficient  solubility in a resist solvent for the use as a resist is exhibited,  and when it is the preferred lower limit value of the foregoing  range or more, good dry etching resistance is obtained and the  resist pattern has a good cross-sectional shape.  A degree of dispersion (Mw/Mn) of the component (Al) is  not particularly limited, and is preferably 1.0 to 5.0, more  preferably 1.0 to 4.0, and most preferably 1.0 to 3.0. It is to be  noted that Mn represents a number average molecular weight.  The component (Al) may be used alone, or in combination  of two or more kinds thereof.  A proportion of the component (Al) in the component (A)  is preferably 25 mass % or more, more preferably 50 mass %  or more, and still more preferably 75 mass% or more relative  to a total mass of the component (A), and it may even be 100  (a4-1)  Ra  ~o  0  (a4-2)  Ra  ~o  0  lQ  (a4-3)  Ra  ~o  0  (a4-4)  Ra  ~o  0  (a4-5)  Ra  ~o  ij  (a4-6)  Ra  ~o  N  0  (a4-7)  Ra  ~o  0 