ISSN:
0032-3888
Keywords:
Chemistry
;
Chemical Engineering
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
,
Physics
Notes:
Polystyrenes with narrow molecular weight distributions have been chlorinated with only slight broadening of molecular weight distributions to yield materials that are five to six times more sensitive to electron-beam irradiation. The chlorinated polystyrenes are useful negative resists for electron-beam lithography. At molecular weights of 3-4 × 105g/mole, their threshold sensitivities to 20 keV electrons are 1-2μC/cm2. Their lithographic contrasts are ≥ 1.5; in fact, 〉 2.0 for the narrowest molecular weight distributions. They compare favorably in these regards to polystyrenes of similar molecular weight characteristics. Lithographic relief images that are 80% of the original thickness of the polymer film can be formed at three to four times the threshold dose.The degree of chlorination ranged from 0.65-0.76 Cl/monomer unit. The infrared spectra of the chlorinated materials resemble the spectrum for poly(4-chlorostyrene). Elemental analysis indicated, however that some addition of chlorine had occurred. More extensive chlorination or chlorination of the higher molecular weight starting materials broadened the molecular weight distributions.The chlorinated material, a kind of poly(4-chlorostyrene-costyrene), is less sensitive than poly(4-chlorostyrenc) prepared by addition polymerization by almost a factor of four.
Additional Material:
9 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pen.760201604
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