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residual monomers and oligomer components in the resin (Ab) is preferably from Oto 10% by mass, more preferably from Oto 5% by mass and further preferably from Oto 1 % by mass. When these conditions are satisfied, a resist composi› tion free from time course change of foreign substances in a liquid or sensitivity or the like can be obtained. 

The weight average molecular weight (Mw) of the resin (Ab) is each preferably in the range of 1,000 to 200,000. In views of the dissolution rate in an alkali and the sensitivity of $_{10 }$ the resin itself it is preferably 200,000 or less. The degree of dispersion (Mw/Mn) of the resin (Ab) is preferably from 1.0 to 3.0, more preferably from 1.0 to 2.5 and particularly pref› erably from 1.0 to 2.0. 

The weight average molecular weight (Mw) of the resin is 15 more preferably in a range of from 1,000 to 100,000, particu› larly preferably in a range of from 1,000 to 50,000 and most preferably in a range of from 1,000 to 25,000. 

Here, the weight average molecular weight is defined in terms of a polystyrene equivalent value by gel permeation chromatography (carrier: tetrahydrofuran (THF)). Specifi› cally, the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the resin (Ab) may be obtained by using, for example, an HLC-8120 (manufac- tured by Tosoh Corporation) using TSK gel Multipore HXL-M colurmis (manufactured by Tosoh Corporation, 7.8 mm IDx30.0 cm) and THF (tetrahydrofuran) as an eluent. 

The resin (Ab) having a dispersity of 2.0 or less can be synthesized by carrying out radical polymerization using an azo-based polymerization initiator. More preferably, the resin (Ab) having a dispersity of 1.0 to 1.5 can be synthesized by, for example, living radical polymerization. 

The resin (Ab) is preferably polymerized by a known anion polymerization method, a radical polymerization method, or the like. For example, the resin (Ab) can be synthesized by using a method disclosed in JP2010-13428A. 

Specific examples of the resin (Ab) are shown below, but the present invention is not limited thereto. 

[Chem. 32-1] 

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<img src='content_image/892969.jpg'>

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