Lutetium diphthalocyanine can be electrolyzed reversibly in dimethylformamide to give four different colored solutions: violet, blue, green, and yellow‐red. Two of these solutions, the violet and the green, also exhibit electron paramagnetic resonance (EPR) signals indicative of organic‐free radicals. The blue and the yellow‐red solutions are EPR silent. The oxidation state of the phthalocyanine nucleus is responsible for the electrochromism of this rare‐earth complex. The EPR signal of the violet form, which is produced by electrolytic reduction and which is probably the anion radical of the complex, has a
g‐normalvalue of 2.003
. The signal of the green form, which is the initially prepared material and which is probably a salt containing the cation radical of the complex, has a
g‐normalvalue of 2.0022
. The optical absorption spectra and extinction coefficients of three of the forms are also reported.
The lithographic performance of a chemically amplified resist is severely degraded by vapor from organic bases. This effect is very pronounced and can be observed when the coated wafers stand for only a few minutes in air containing parts per billion (ppb) levels of an organic base. In resist systems derived from poly[4-((tert-butyloxycarbonyl)oxy)styrenel, the contamination induced effect takes two general forms. When processed in the negative tone, the UV exposure dose required to obtain the correct linewidth increases. When processed in the positive tone, a "skin" forms a t the resist-air interface. Both effects are caused by the photogenerated acid being neutralized by the airborne organic base. A wide variety of commonly used materials liberate trace amounts of volatile amines and degrade resist performance. We have quantified the incorporation of one such airborne contaminant, N-methylpyrollidone (NMP), by thin polymer films. NMP labeled with 14C was introduced a t a concentration of 10 ppb into a stream of purified air and the films of interest were allowed to stand in the airstream for a predetermined time under controlled conditions. This method allows for determining NMP uptake rate, correlating lithographic performance with absorbed NMP content, and studying the effects of film thickness or composition on absorption rates.
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