We propose the application of carbon films as resist masks for practical nanometer lithography involving reactive ion etching (RIE). Amorphous carbon films prepared by room-temperature plasma chemical vapor deposition show a very high resistance against RIE, the etching rates being less than 1/2 of that of a novolak-based conventional photoresist. The carbon films can be finely patterned by O2 RIE in a bilayer resist process using a high-resolution silicone-based negative resist. Nanometer patterns as small as 40 nm are fabricated on a thick solid substrate, and can be transferred into the substrate layer directly by RIE.
ABSTRACT:The electrochemical polymerization of pyrrole on an electrode covered with an insulating polymer film ·produces conducting polymer alloy films of polypyrrole (PPy) and insulating polymer. By using vinylidene fiuoride-trifiuoroethylene copolymer (P(VDF-TrFE)) as an insulating polymer, very flexible and stretchable conducting films were obtained. The mechanical properties of the alloy films were studied by measuring tensile strength and dynamic modulus of elasticity. The excellent mechanical properties of P(VDF-TrFE) did not change by the incorporation of PPy up to a charge density of 0.5 C em-2 . A further increase of charge density caused a reduction of dynamic moduli of the alloy films. The alloy films with the charge density of 0.5 C em -2 extended more than 100% and their surface resistance was almost constant up to 50% elongation. The elongation more than 60% resulted in a large increase of surface resistance, because inhomogeneous fracture occurs from the electrode side of the film. A comparison of the mechanical properties between P(VDF-TrFE)-PPy and other alloy films based on poly( vinyl chloride) were also studied.KEY Many efforts have concentrated on the improvement of the film quality of PPy. Iwata et al. 4 obtained the flexible pure PPy with high conductivity more than 300 S em -1 by polymerizing pyrrole at a low temperature about -30°C.The most attractive feature of this electrochemical polymerization is the capability of forming various hybrid conducting materials with different types of polymers. By using polymeric anions as electrolyte, PPy-polymer anion complexes can be easily prepared, and flexible polymeric anions can improve the mechanical properties of PPy. Bates et a!. 5 reported that PPy-sulphonated styrene-(hydrogenated) butadiene tri-block copolymer complex becomes flexible and can be extended up to 400%. However, the electrical conductivity of PPy-polyanion becomes less than lO-2 S em -1 , which is lower by 4 orders of magnitude compared with PPy single film.Another type of hybrid material can be prepared by the electrochemical polymer-1293
In the subtractive X-ray mask fabrication process, suppressing distortions introduced in the bulk-Si etching step is of the utmost importance. Influences of absorber and membrane stresses on mask distortions were investigated in order to obtain good position accuracy. The required stress conditions in order to suppress absorber- and membrane-stress-induced distortions are <2×108 dyn/cm2 for Ta, and <5×108 dyn/cm2 for SiN with a thickness of 2 µm. A five-level mask-to-mask overlay accuracy of <0.085 µm (3σ) was obtained by applying these conditions to actual device mask fabrication. Distortions induced in the bulk-Si etching step were drastically suppressed below 0.058 µm (3σ) in these masks. Absorber patterns with linewidths down to 0.14 µm were successfully fabricated. Pattern position shifts occurring in the frame-mounting step are dominant in our X-ray mask fabrication process.
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