Jan.  13, 2011  79  US 2011/0008728 Al  component, which have a boiling point within a range from 70  to 180°  C. and preferably from 80 to 160°  C. A fluorine-based  inert liquid having a boiling point within the above-men› tioned range is advantageous in that the removal of the  immersion medium after the exposure can be conducted by a  simple method.  [0996]  As a fluorine-based inert liquid, a perfluoroalkyl  compound in which all of the hydrogen atoms of the alkyl  group are substituted with fluorine atoms is particularly desir› able. Examples of these perfluoroalkyl compounds include  perfluoroalkylether compounds and perfluoroalkylamine  compounds.  [0997]  Specifically, one example of a suitable perfluoro› alkylether compound is perfluoro(2-butyl-tetrahydrofuran)  (boiling point 102°  C.), and an example of a suitable perfluo› roalkylamine compound is perfluorotributylamine (boiling  point 174°  C.).  [0998]  As the immersion medium, water is preferable in  terms of cost, safety, environment and versatility.  [0999]  The PEB treatment is conducted at a bake tempera› ture which changes (increases or decreases) the solubility of  the first resist film in an alkali developing solution.  [1000]  Specifically, for example, when the first resist film is  composed of a chemically amplified resist composition, by  conducting PEB treatment after exposure, diffusion of acid  generated from the acid-generator component within the  resist film and change (increase or decrease) in solubility of  the resist film in an alkali developing solution by the action of  the acid proceed.  [1001]  More specifically, the first resist film is selectively  exposed through a photomask having a defined pattern, and  then, post exposure bake (PEB) is conducted at a temperature  of 80 to 150°  C. for 40 to 120 seconds, preferably 60 to 90  seconds.  [1002]  After the PEB treatment, alkali developing is con› ducted to form a first resist pattern.  [1003]  The alkali developing can be conducted by a con› ventional method, for example, using a tetramethylammo› nium hydroxide (TMAH) solution having a concentration of  0.1 to 10% by weight. By the alkali development, the exposed  portions of the first resist film are removed, thereby forming  a first resist pattern.  [1004]  After the alkali developing, a rinse treatment using  water or the like can be conducted.  [1005]  Further, after the alkali developing, post bake treat› ment may be conducted. Post bake (which is performed in  order to remove water content after the alkali developing and  rinsing) is generally conducted at about 100°  C. preferably for  30 to 90 seconds.  [1006]  [Film Forming Step (2)]  [1007]  Next, the resist composition of the present invention  is applied to the substrate having a first resist pattern formed  thereon, to thereby form a second resist film. For example,  when the first resist pattern is a line and space pattern (here› after, referred to as "LS pattern"), the second resist film can be  formed in the same manner as in the first resist film by a  conventional method to fill the space portions formed  between the plurality of LS patterns.  [1008]  The film thickness of the second resist film is at least  as thick as the first resist pattern and is preferably thicker. In  other words, when the substrate is viewed from the second  resist film side, it is preferable that the substrate surface be  flat.  [1009]  [Patterning Step (2)]  [1010]  Next, the second resist film is subjected to selective  exposure, followed by alkali development to form a resist  pattern.  [1011]  Specifically, for example, the second resist film is  selectively exposed through a photomask at portions different  from where the plurality of resist patterns have been formed,  followed by PEB treatment and alkali developing, thereby  forming a resist pattern.  [1012]  Accordingly, the exposed portions of the second  resist film when the resist composition of the present inven› tion is a positive type and the unexposed portions of the  second resist film when the resist composition of the present  invention is a negative type are removed, and between a  plurality of resist patterns formed previously, a plurality of  resist patterns is newly formed in the LS pattern. As a result,  a resist pattern is formed on the substrate which is composed  of a plurality of resist patterns formed in the previous step,  and a plurality of resist patterns newly formed on the second  resist film.  [1013]  In the present invention, when a first resist pattern is  formed on a substrate, any region within the substrate which  does not completely overlap with a region where the first  resist pattern is formed is referred to as "region other than the  region where the first resist pattern is formed". In other words,  the expression includes a region which does not overlap at all  with the region where the first resist pattern is formed, and  also includes a region which only partially overlaps with the  region where the first resist pattern is formed.  [1014]  In the present invention, when forming a resist pat› tern so as to ultimately form a line and space pattern, it is  preferable that the region where the first resist pattern is  formed and the region exposed selectively in the patterning  step (2) do not overlap at all.As a result, a resist pattern can be  formed with a pitch smaller than that of the first resist pattern  formed in the patterning step (1 ).  [1015]  The selective exposure of the second film can be  conducted, for example, by slightly shifting the exposing  position of the photomask used in the patterning step (1).  Alternatively, at this time, a photomask different from that  used in the patterning step (1) may be used.  [1016]  The position of the resist pattern formed from the  second resist film may be completely non-overlapping the  position of first resist pattern, or partially overlapping the first  resist pattern. However, it is preferable that the position of the  resist pattern formed from the second resist film be com› pletely non-overlapping the position of first resist pattern. As  a result, a resist pattern can be formed with a pitch smaller  than that of the first resist pattern formed in the patterning step  (1 ).  [1017]  For example, a line and space pattern may be formed  in the patterning step (1) using a photomask for forming a line  and space pattern, in which a plurality of lines are arranged  with a constant pitch; and then a line pattern may be formed  in intermediate regions between the adjacent line patterns  formed in the patterning step (1) by changing the position of  the photomask in the patterning step (2). Accordingly, a line  and space pattern ( dense pattern) can be newly formed which  has a pitch smaller than that of the previously formed line and  space resist pattern (isolated pattern).  [1018]  The "isolated pattern" is preferably a line and space  pattern in which the space width is large so that the ratio of the  line width to the space width (i.e., line width:space width) is  1 :at least 2. 