333  US 9,285,679 B2  334  -continued  Basic compounds (Bl to B6) are as shown before.  Dl: 2-Hydroxy-3-naphthoic acid  D2: 2-Naphthoic acid  D3: Benzoic acid  The resist coating solution was coated on the 6-inch wafer  by using a spin coater, Mark 8, manufactured by Tokyo Elec› tron Ltd. and dried at 110°  C. for 90 seconds on a hot plate to  obtain a resist film having a thickness of 100 run. That is, a  resist-coated mask blanks was obtained.  This resist film was patternwise irradiated using an elec› tron beam lithography apparatus (ELS-7500, manufactured  by Elionix Inc., accelerating voltage: 50 keV). After the irra- diation, the resist film was heated at 120°  C. for 90 seconds on  a hot plate, dipped in an aqueous 2.38 mass % tetramethy› lammonium hydroxide (TMAH) solution for 60 seconds,  rinsed with water for 30 seconds and dried.  The obtained pattern was evaluated for the sensitivity, reso› lution, pattern profile, line edge roughness (LER), dry etching  resistance, scum and aging stability by the following meth› ods.  The cross-sectional profile of the pattern obtained was  observed using a scanning electron microscope (S-4300,  manufactured by Hitachi, Ltd.), and the exposure dose (dose  of electron beam irradiation) when resolving a resist pattern  with a line width of 100 run (line:space=l: 1) was taken as the 60  sensitivity. A smaller value indicates higher sensitivity.  [Resolution]  The limiting resolution (the minimum line width below  which the line and the space (line:space=l:1) were not sepa› rated and resolved) at the exposure dose ( dose of electron  beam irradiation) giving the sensitivity above was taken as the  resolution (run).  The cross-sectional profile of a line pattern (LIS= 1/1) with  a line width of 100 run at the exposure dose ( dose of electron  beam irradiation) giving the sensitivity above was observed  using a scanning electron microscope (S-4300, manufactured  by Hitachi, Ltd.). The cross-sectional profile of the line pat› tern was rated "reverse tapered" when the ratio represented by  [line width in the top part (surface part) of line pattern/line  width in the middle ofline pattern (at the position of half the  height of line pattern)] is 1.5 or more, rated "slightly reverse  tapered" when the ratio above is from 1.2 to less than 1.5, and  rated "rectangular" when the ratio is less than 1.2.  A line pattern (LIS= 1/1) having a line width of! 00 run was  formed with the irradiation dose ( dose of electron beam irra- diation) giving the sensitivity above. At arbitrary 30 points  included in its longitudinal 50 µm  region, the distance from  the reference line where the edge should be present was  measured using a scanning electron microscope (S-9220,  manufactured by Hitachi, Ltd.). The standard deviation of  measured distances was determined, and  3a  was computed. A  smaller value indicates better performance.  A resist film formed by performing entire surface irradia› tion with the irradiation dose ( dose of electron beam irradia› tion) giving the sensitivity above was subjected to  dry  etching  for 30 seconds by using anAr/C$_{4}$FiO 2  gas (a mixed gas in a  volume ratio of 100/4/2) in HITACHI U-621. Thereafter, the  residual resist film ratio was measured and used as an indica› tor of dry etching resistance.  Very good: Residual film ratio of95% or more.  Good: Less than 95% and 90% or more.  Bad: Less than 90%.  A line pattern was formed by the same method as in [Pat› tern Profile] above. Thereafter, its cross-sectional SEM was  obtained using S4800 (manufactured by Hitachi High-Tech› nologies Corporation), and the scum in the space portion was  observed and rated as follows.  C: Scum was observed and patterns were partially con› nected.  B: Scum was observed but patterns were not connected.  A: Scum was not observed.  Each composition was stored at room temperature over 1  month, and the degree of variation in the sensitivity (the  sensitivity measured in [Sensitivity] above) between before  and after the storage was evaluated. This evaluation was per› formed based on the following criteria.  A (Good): The variation in sensitivity was less than  µC/cm2.  B (Fair): The variation in sensitivity was 1 µC/cm 2  or more  and 3 µC/cm 2  or less.  Surfactants (W-1 to W-3) are as shown before.  Solvents (Sl to S7) are as shown before.  [Surfactant]  [Solvent]  [Sensitivity]  [Pattern Profile]  [Line Edge Roughness (LER)]  [Dry Etching Resistance]  [Evaluation of Scum]  [Aging Stability]  (Criteria)  MeO  OH  OMe  CL-4  \  0  HO  0  I  I  0  OH  0  \  CL-5  [Chem. 178]  [Basic Compound]  [Organic Carboxylic Acid]  (3) Formation of Resist Film  ( 4) Production of Negative Resist Pattern  (5) Evaluation of Resist Pattern 