Positive resist composition

#The present invention relates to a positive resist composition suitably used in a microlithography process, for example, the production of VLSI and high capacity microtips, and in other photofabrication processes. More particularly, the present invention relates to a positive resist composition capable of forming a highly precise pattern using a vacuum ultraviolet ray of not more than 160 nm as a light source for exposure.

#The degree of integration of integrated circuits has recently become much higher, and the processing of ultra-fine patterns having a line width of a quarter micron or below is required in the production of semiconductor substrate, for example, VSLI. It is known to make an exposure light source for use in the production of resist pattern shorter as one means for the formation of fine pattern.

#For instance, in the production of semiconductor device having the degree of integration up to 64 Mbits, an i-line (365 nm) of high pressure mercury lamp has been employed as the light source. As a positive resist corresponding to the light source, a large number of compositions containing a novolak resin and a naphthoquinone diazide compound as a photosensitive substance have been developed. These compositions have achieved full success in the processing of linewidth up to about 0.3 μm. Also, in the production of semiconductor device having the degree of integration of 256 Mbits or more, a KrF excimer laser beam (248 nm) is employed as the light source in place of the i-line.

#FIG. 1 is a view showing a footing profile of resist pattern for the evaluation in the present invention.

#The present invention also includes the following preferred embodiments.

#(2) The positive resist composition as described in item (1) above, wherein the fluorine group-containing resin of (A) is a resin containing at least one moiety selected from a perfluoroalkylene group and a perfluoroarylene group in the main chain of polymer skeleton or a resin containing at least one moiety selected from a perfluoroalkyl group, a perfluoroaryl group, a hexafluoro-2-propanol group and a group obtained by protecting the hydroxy group of hexafluoro-2-propanol group in the side chain of polymer skeleton.

#(3) The positive resist composition as described in item (1) or (2) above, wherein the fluorine group-containing resin of (A) has at least one of repeating units represented by the following formulae (I) to (X): 1 2