158  US 8,900,791 B2  157  10 µC/cm 2 ,  and the exposed film was baked at 110°  C. for 90  seconds. Thereafter, using a 2.38 mass  % aqueous tetram› ethylammonium hydroxide (TMAH) solution, the dissolu› tion rate at each of the exposure intensities was measured,  thereby obtaining a sensitivity curve.  It is apparent from the results of Table 4 that the photosen› sitive composition of the present invention exhibits excellent  performance as a negative resist composition employed in  KrF excimer laser exposure.  The sensitivity was defined as the exposure intensity at  which the dissolution rate of the resist was saturated on the  sensitivity curve. Dissolution contrast (y value) was calcu- lated from the gradient of the straight line portion of the  sensitivity curve. The larger they value, the greater the excel› lence in dissolution contrast.  <Preparation of Resist>  [Line Edge Roughness]  At arbitrary 30 points in a 50 µm  region in the longitudinal  direction of a 150 nm line pattern at the exposure intensity  realizing the above sensitivity, the distance from a reference  line on which edges were to be present was measured by  means of a scanning electron microscope (model S-9220,  manufactured by Hitachi, Ltd.). The standard deviation of  measurements was determined, and  3a  was computed.  [Outgas Performance: Ratio of Change in Film Thickness  by Exposure]  Referring to Table 5 below, with respect to each of the  resists, the individual components were dissolved in the sol› vent and passed through a polytetrafluoroethylene filter of0.1  µm  pore size, thereby obtaining a positive resist solution of 12  mass  % solid content.  <Evaluation of Resist>  Each of the obtained positive resist solutions was uni› formly applied onto a silicon substrate having undergone a  hexamethyldisilazane treatment by use of a spin coater, and  heated and dried on a hot plate at 120°  C. for 60 seconds,  thereby obtaining a 0.3 µm  resist film.  The obtained resist film was exposed by use of an electron  beams projection lithography equipment manufactured by  Nikon Corporation ( accelerating voltage 100 ke V). Immedi› ately after the exposure, the resist film was heated on a hot  plate at 110°  C. for 90 seconds. Thereafter, the resist film was  developed with a 2.38 mass % aqueous tetramethylammo› nium hydroxide solution at 23 °  C. for 60 seconds, rinsed with  pure water for 30 seconds and dried. The thus obtained line  and space patterns were evaluated in the same manner as in  Exposure was carried out at the exposure intensity equal to  2.0 times the exposure intensity (µC/cm 2 )  at the sensitivity  determined by performing a surface exposure by electron  beams. The film thickness after the exposure (before post› bake) was measured, and the ratio of change from the film  thickness before the exposure was calculated by the following  formula.  Ratio of change in film thickness (%)~[(film thickness  before exposure-film thickness after exposure)/  (film thickness before exposure)]xl00  The evaluation results are given in Table 5.  Surface exposure was carried out while changing the expo› sure intensity by 0.1 µC/cm $^{2 }$at a time within the range of Oto  ExampleE  Examples 1E to 1 SE and Comparative Examples 1E  and2E  Sensitivity, Resolving Power (y)  Example A  TABLES  Electron beam ositive ex osure  (A2)  (F)  (G)  (H)  (Al)  Acid  Basic  Surfactant Solvent  Acid  generator (B)  compound  (0.1  (mass  Sensitivity Resolving Roughness Outgas  generator  (0.1 g)  Resin  (0.02 g)  mass%)*  ratio)  (µC/cm 2 )  powery  (nm)  (%)  Ex. IE  Al-1  R-18 (H)  C-1  W-1  Al/Bl  3.5  5.6  4.1  5.8  (0.3 g)  (10 g)  (6/4)  Ex. 2E  Al-2  R-18 (H)  C-1  W-1  A2/B2  3.5  5.4  5.0  1.8  (0.3 g)  (10 g)  (6/4)  Ex. 3E  Al-3  R-18 (H)  C-1  W-2  A3/Bl  3.0  6.0  4.1  1.2  (0.3 g)  (10 g)  (6/4)  Ex.4E  Al-4  R-18 (H)  C-1  W-3  A4/Bl  3.5  5.0  4.1  5.9  (0.3 g)  (10 g)  (6/4)  Ex. 5E  Al-5  R-18 (H)  C-1  W-1  Al/B2  3.5  5.0  5.0  5.8  (0.3 g)  (10 g)  (6/4)  Ex. 6E  Al-6  R-18 (H)  C-1  W-1  Al/Bl  3.5  5.0  4.1  5.8  (0.3 g)  (10 g)  (6/4)  Ex. 7E  Al-7  R-18 (H)  C-1  W-4  Al/Bl  3.5  6.0  3.5  5.8  (0.3 g)  (10 g)  (6/4)  Ex. SE  Al-8  R-18 (H)  C-1  W-2  Al/Bl  3.5  5.6  4.1  5.9  (0.3 g)  (10 g)  (6/4)  Ex. 9E  Al-9  R-18 (H)  C-1  W-3  Al/Bl  3.3  5.6  4.1  4.0  (0.3 g)  (10 g)  (6/4)  Ex. !OE  Al-1  R-2  C-1  W-1  Al/Bl  3.5  5.6  4.5  5.4  (0.3 g)  (10 g)  (6/4)  Ex. llE  Al-1  z  R-8  C-1  W-1  Al/Bl  4.0  5.0  4.5  5.4  (0.2 g)  (10 g)  (6/4)  Ex.12E  Al-1  z  R-14  C-1  W-1  Al/Bl  4.0  5.0  4.5  5.3  (0.2 g)  (10 g)  (6/4)  Ex.13E  Al-1  z  R-17  C-1  W-2  Al/Bl  4.0  5.0  4.5  5.4  (0.2 g)  (10 g)  (6/4) 