Electron-beam lithography (EBL) is an integrated circuit production technique which utilizes a polymer resist to delineate circuit patterns for monolithic circuits. Where the e-beam is impinged upon the resist coated circuit substrate, the e-beam resist either degrades or crosslinks depending upon the intrinsic nature of the resist. If the polymer degrades, it is a positive acting e-beam resist. If it crosslinks, it is a negative acting resist. By using the e-beam resist it is possible to pattern the desired circuit pattern upon the circuit substrate as for example, a silicon wafer with an oxide top layer.
Poly(methyl methacrylate) (PMMA) is the state-of-the-art positive e-beam resist material. It is capable of high resolution but is not sensitive enough for commercial device production using direct-write e-beam lithography. The e-beam sensitivity of PMMA is 2.times.10.sup.-4 (20 keV) or 5.6.times.10.sup.-5 (10 keV) Coulombs per cm.sup.2, while sensitivities in the 10.sup.-5 -10.sup.-6 range are desirable for EBL production; resolution, however, cannot be sacrificed for sensitivity. Resolution is stipulated by the minimum obtainable linewidth and line space for the resist. In this connection, PMMA is capable of resolving 1 micron lines and spaces.
In Ser. No. 051,263, there is disclosed and claimed a method of patterning a substrate in which the positive acting e-beam resist is characterized by increased sensitivity without a sacrifice in resolution. That result is obtained by using poly(methyacrylonitrile) (PMCN) as the positive action e-beam resist.