We have designed and synthesized a series of novel non-acrylic nortricyclene polymer and copolymers containing various structural units for use in both 193 and 248 nm lithography. These polymers and copolymers are prepared using a free- radical cyclopolymerization process that is very versatile and allows use of a great variety of comonomers. The resulting materials exhibit outstanding dry-etch resistance, good adhesion to silicon, good transparency at 193 nm and, unlike many poly(norbornenes), they are not contaminated by metal catalysts. In preliminary 193 nm testing a resist formulated with a suitable photoacid generator afforded alkali-developed positive-tone images with sub-0.15 micrometer L/S resolution. Although a large array of copolymers are possible due to the ease with which the free-radical copolymerization reaction proceeds, copolymers based exclusively on functionalized norbornadiene and maleic anhydride-derived components have shown great promise. In particular, it is possible to tune their properties through simple variations in structure and composition.
Based on previous work on gold-catalyzed hydroamination reactions by the same group (Angew. Chem. Int. Ed. 2010, 49, 598), the corresponding gold-catalyzed intramolecular aminoarylation reaction of N-sulfonylalkenes with boronic acids has been shown to lead to N-protected pyrrolidines and piperidines. [dppm(AuBr)2] in combination with Selectfluor® as an oxidative agent was found to catalyze the formation of pyrrolidines at room temperature in good yields while the formation of piperidines required heating at 40-60 ˚C. The reaction is proposed to proceed via a redox cycle involving the initial oxidation of gold(I) into gold(III) by Selectfluor®. Based on studies of competitive reactions using Ph-AuPPh3 and ArB(OH)2 the incorporation of the Ar moiety was demonstrated, thus suggesting that the C-C bond formation does not proceed through a reductive elimination from a phenylgold(III) species but through a bimolecular reductive elimination process.
Pecora and Carroll 1 have shown how two nonautonomous chaotic circuits driven by periodic forcing can be synchronized using the master-slave driving principle. However, in their scheme, the periodic forcing in both circuits needs to be phase-locked through some additional circuitry for the system to synchronize. In this paper, we show two ways in which this can be avoided. In the first scheme, the two circuits are connected in a master-slave driving configuration and the periodic forcing is included in the driving signal such that it eliminates the need for the slave circuit to have an external periodic forcing signal. In addition, we can recover the periodic forcing signal at the slave circuit. In the second scheme, the two circuits are connected in a mutual coupling configuration. The two circuits will synchronize regardless of what the periodic forcing signals of the two circuits are. In particular, the two periodic forcing signals could have different phases, different frequencies, or different shapes. We discuss two interpretations of these synchronization schemes. First, we consider them as communication systems when the periodic forcing signal is replaced by a properly encoded information signal. We illustrate this in a physical circuit implementation. Second, we consider them as synchronization schemes for nonidentical systems by considering the external forcing signal as an error signal due to the difference between the two systems.
