| abstract |
A nonpolymeric silsesquioxane is provided wherein at least one silicon atom of the silsesquioxane is directly or indirectly bound to an acid-cleavable substituent R CL . The silsesquioxane has a glass transition temperature T g of greater than 50° C, and the R CL substituent can be cleaved from the silsesquioxane at a temperature below T g , generally at least 5 ° C. below T g . The remainder of the silicon atoms within the silsesquioxane structure may be bound to additional acid-cleavable groups, acid-inert polar groups R P , and/or acid-inert nonpolar groups R NP . The nonpolymeric silsesquioxane can be a polyhedral silsesquioxane optionally having one to three open vertices, such that the polyhedron appears to be a “partial cage” structure, or a macromer of two to four such polyhedral silsesquioxanes. Photoresist compositions containing the novel nonpolymeric silsesquioxanes are also provided, as is a method for using the compositions in preparing a patterned substrate. |