Photoacid generators, photoresist compositions containing the same and pattering method with the use of the compositions

#The present invention relates to a photoacid generator, a photoresist composition containing the same and a pattering method using the composition. More particularly, it relates to a photoacid generator suitable for photolithography using a far UV ray, typically represented by an ArF excimer laser, as a ray of light for exposing, a photoresist composition containing the photoacid generator, and a pattering method using the composition.

#In manufacture of semiconductor devices such as typical LSIs (Large Scale Integrated circuits), photolithography technology is necessarily used to pattern insulating films such as silicon oxide and silicon nitride films formed on a semiconductor substrate into desired shapes. It is also used to pattern conductive films such as aluminum alloy and copper alloy films and a work itself including the semiconductor substrate.

#In the photolithography, a UV-sensitive photoresist is applied on the work to form a photoresist film, to which a UV ray is radiated (which is exposed to a UV ray) through a mask pattern to turn a UV-radiated region into a soluble one (positive type) or an insoluble one (negative type). The photoresist film is then subjected to a developing process to partially remove the soluble one with a solvent for forming a resist pattern. Then, using the resist pattern as a mask, the work is selectively etched for patterning.

#FIG. 1 is a diagram showing relations between transmittance and contents of photoacid generators in photoresist compositions obtained in examples of the present invention.

#Presumptions:

#Prior to description of embodiments according to the present invention, the presumptions for the present invention will be described generally.

#The inventors have intensively studied to achieve the above-mentioned objects and finally completed the present invention. Namely, according to the present invention, a photoacid generator (sulfonium salt compound) is obtained, which has high transparency to the ArF excimer laser and thermal stability at about 150° C. or above even in resinous films. Specifically, the present invention is based on the finding that the above-mentioned subject can be solved by a photoacid generator consisting of a new alkylsulfonium salt compound with a structure disclosed below, a photoresist composition containing the photoacid generator as a component and a method of patterning in which patterning is carried out by light radiation using the photoresist composition.