US 9,551,933 B2  266  265  TABLE 2-continued  Isolated  Space  Photoacid  Basic  Solvent  Space  Width  Resin  Generator  Compound  (mass  Surfactant  Rinsing Sensitivity Resolution Roughness  (mass%)  (mass%)  (mass%)  ratio)  (mass%)  Developer Solution (µC/cm 2 )  (nm)  (nm)  Comparative  C-1  z115  N-6  Sl/S2  Example 1-1  77.99  20  2  80/20  Comparative  C-2  z115  N-6  Sl/S2  Example 1-2  77.99  20  2  80/20  Comparative  C-3  z115  N-6  Sl/S2  Example 1-3  77.99  20  2  80/20  Comparative  C-4  z115  N-6  Sl/S2  Example 1-4  77.99  20  2  80/20  Comparative  C-5  z115  N-6  Sl/S2  Example 1-5  77.99  20  2  80/20  Comparative  C-6  z115  N-6  Sl/S2  Example 1-6  77.99  20  2  80/20  W-4  0.01  W-4  0.01  W-4  0.01  W-4  0.01  W-4  0.01  W-4  0.01  SG-3  34.5  100  8.2  SG-3  35.5  100  8  SG-3  NR  SG-3  NR  SG-3  37.5  100  8.1  SG-3  33  87.5  7.8  NR: not resolved  As apparent from Table 2 above, in Comparative  Examples 1-1 and 1-2 using Resins C-1 and C-2 (corre› sponding to Polymers A-4 and A-8 described in JP-A-8- 101507), Comparative Example 1-5 using Resin C-5 (cor› responding to the polymer of Example 11 described in  JP-A-2000-29215), and Comparative Example 1-6 using  Resin C-6 (corresponding to Resin (Al-1) described in  JP-A-2010-217784), the sensitivity, resolution and space  width roughness performance in the isolated space pattern  formation were poor. This is considered to result because the  resin does not contain a repeating unit having an acid› decomposable group with an acetal protection of carboxylic  acid or even if the repeating unit is contained, the molar  proportion thereof is less than 35 mo! %.  This is considered to occur because in the resin (A) for use  in the present invention, the repeating unit with an acetal  protection of carboxylic acid represented by formula (1-1) is  low in the deprotection activation energy (Ea) and the molar  proportion thereof is 35 mo!  % or more, leading to high  sensitivity and high contrast, as a result, high resolution and  excellent space width roughness performance could be  obtained.  Incidentally, the same excellent results as in Examples  above are obtained also in the case of not performing the  rinsing step.  In Comparative Examples 1-3 and 1-4 using Resins C-3  and C-4 (corresponding to PolymersA-1 andA-10 described  in JP-A-8-101507), an isolated space pattern could not be  resolved and also, the sensitivity and space width roughness  could not be measured. This is considered to result because  the resin containing a hydroxystyrene repeating unit having  a methyl group on the a-position readily undergoes depo- lymerization and is unstable or the resin containing an  acrylic acid repeating unit having an acid-decomposable  group with an acetal protection is low in the Tg and allows  for easy diffusion of the generated acid and for such a  reason, an isolated space pattern could not be resolved.  On the other hand, in Examples 1-1 to 1-59, an isolated  space pattern could be formed with high sensitivity, high  resolution and excellent space width roughness perfor› mance, as compared with Comparative Examples 1-1 to 1-6.  (4) Preparation of an actinic ray-sensitive or radiation› sensitive resin composition, pattern formation and evalua› tion of resist pattern were performed in the same manner as  in Examples 1-1 to 1-59 and Comparative Examples 1-1 to  1-6 except that the resist film was irradiated with an electron  beam by inverting the lithography region, the development  was performed using an aqueous alkali solution (TMAH; an  aqueous 2.38 mass  % tetramethylammonium hydroxide  solution) in place of the organic developer, and the rinsing  solution was changed to water.  Electron Beam (EB) Exposure, Positive  Development with an Aqueous Alkali Solution,  Evaluation of Isolated Space  Examples 2-1 to 2-59 and Comparative Examples  2-1 to 2-5  TABLE 3  Photoacid  Resin  Generator  (mass%)  (mass%)  Example 2-1  P-1  z115  77.99  20  Example 2-2  P-2  z115  77.99  20  Example 2-3  P-3  z115  77.99  20  Example 2-4  P-4  z115  77.99  20  Example 2-5  P-5  z112  77.99  20  Example 2-6  P-6  z113  77.99  20  Isolated  Space  Basic  Space  Width  Compound  Solvent  Surfactant Sensitivity Resolution Roughness  (mass%)  (mass ratio)  (mass%)  (µC/cm 2 )  (nm)  (nm)  N-6  Sl/S2  W-4  30  87.5  6.7  2  80/20  0.01  N-6  Sl/S2  W-4  24.2  87.5  6.1  2  80/20  0.01  N-6  Sl/S2  W-4  18.5  62.5  5.1  2  80/20  0.01  N-6  Sl/S2  W-4  19.8  62.5  5.1  2  80/20  0.01  N-8  Sl/S2  W-2  21.5  75  5.6  2  80/20  0.01  N-9  Sl/S2  W-4  21.8  75  5.5  2  60/40  0.01 