Horst Binder

A new environmentally stable protective group for deep UV resists: Methoxy(tetrahydropyranyl) ether

Deep UV photoresists are designed to be used in the manufacturing of highly integrated chips (>16 Mbit). They differ from the conventional photoresists in their principal chemistry. The vast majority of positive deep UV resists are based on protected poly(hydroxystyrene) resins and photochemical acid generators (PAG). They rely on photochemically induced acid-catalyzed reactions (chemical amplification) to generate the desired pattern and meet the high-sensitivity requirements. It turned out that the type of the acid labile protective group is of paramount importance for the performance of the resists. It has to be stable enough not to be cleaved by the weakly acidic phenol at room temperature, but has to be labile enough to be cleaved readily even at the top of the resist where portions of the generated acid may be neutralized by airborne bases. Selection criteria for useful groups and the performance of the very well suited protective group methoxy(tetrahydropyran) are described in this paper.

Deep-UV resists with improved delay capabilities

In this paper, we present our approaches to solve the delay problem, i.e., the formation of T- tops during the delay time between exposure and post-exposure bake. We investigated the distribution of the photoacid generator in the resist layer and the influence of basic contaminations in the formulation. T-topped patterns can be avoided by using appropriate developers. The incorporation of additives make the resist less sensitive to basic contaminations. Some formulations show no T-top formation under severe conditions for a considerable amount of time.

Robust and environmentally stable deep UV positive resist: optimization of SUCCESS ST2

By optimization of SUCCESS ST2 an environmentally stable and robust deep UV positive resist has been derived where the generally encountered problems related to chemical amplification resists, the formation of T-tops and linewidth changes during delay have been solved. The previously reported chemistry, protected poly-p-hydroxystyrene and SUCCESS type sulfonium salts, has been proven to be insensitive to airborne contaminations. In this paper the optimization of processing conditions, based on thermal analysis is reported. With the derived conditions linewidth changes during delays could be minimized and excellent performance obtained. At the IBM lithography test center in Boblingen an integrated photosector, consisting of equipment, materials, process and control philosophy, was balanced and 0.25 micrometers pattern can routinely be resolved using an ASM-L DUV stepper (NA 0.5).