Dirk Funhoff

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.

Photoconductivity in Discotic Liquid Crystals: A New Class of High-Mobility Materials

Abstract Using a time-of-flight technique, different transport mechanisms, deep trapping, multiple shallow trapping and Gaussian transport, can be observed in the different temperature and phase regions of the liquidcrystalline (LC) photoconductor hexapentyloxytriphenylene (HPT). Transient photocurrents and carrier mobilities for various temperatures, electric fields, and sample histories were examined. The ideal intrinsic Gaussian transport, observed for holes in the mesophase, puts HPT into a new class of highmobility materials with both hole mobilities on the order of 1.10−3cm2/Vs and a steplike current decay. These features result from the fact that there is obviously neither a positional disorder nor an energetic disorder, which would impair efficient charge transport. This is probably achieved by special molecular packing mechanisms in combination with the dynamical processes of the LC phase and due to favourable properties of the HPT molecule, which has a rigid and conjugated core, a symmetric stru...