US 4,289,845 AGranted

Fabrication based on radiation sensitive resists and related products

AssigneeBell Telephone Laboratories, Incorporated

InventorsMurrae J. S. Bowden, Larry F. Thompson

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Abstract

A phase compatibile polymer blend serves as a radiation sensitive lithographic resist in the fabrication of circuits and circuit elements. Radiation sensitivity is due to inclusion of a "modifier". Resist properties, notably stability to agents and ambients to be masked are attributed largely to a second component, the "matrix polymer". In an exemplary embodiment in which the blend is positive acting, fabrication including dry processing is dependent upon use of a resist blend of a vapor developing polysulfone and a novolac. The novolac, inherently soluble in alkaline media is rendered insoluble in the blend. Radiation initiated depolymerization results in volatilization of the modifier to render the irradiated portions of the resist soluble in alkaline developers. Modifier may function in other manner; for example, it may undergo radiation initiated polymerization so as to insolubilize the blend in irradiated regions, so resulting in a negative acting resist. Effective isolation of lithographic from masking functions permits design of blends with high lithographic sensitivity, as well as good processing stability. The latter is sufficient to permit use in many dry processing procedures as practiced in direct writing, as well as in mask fabrication of large scale integrated silicon circuits.

Process for fabrication of an article comprising an operation during which the article undergoing fabrication comprises an article surface and an overlying actinic processing layer, said processing layer comprising a phase compatible blend including polymeric material, said process including the steps of (1) selectively exposing portions of the said processing layer to patterning actinic radiation whereby a difference in ease of removal of exposed portions relative to unexposed portions of the said processing layer by a developing agent is effected;

(2) developing by treating the said processing layer with said developing agent to selectively remove material, thereby producing a patterned processing layer said pattern being defined by regions of the said processing layer within which material is selectively removed;
(3) treating the article undergoing fabrication with an altering agent which preferentially alters regions of the said article surface corresponding with said regions of the patterned processing layer, relative to regions of the said article surface corresponding with the remainder of the said patterned processing layer, CHARACTERIZED IN THAT the said phase compatible blend comprises a "matrix polymer" determinative of the characteristics of the said remaining regions of the patterned processing layer together with a modifier which is the part of the blend primarily responsive to actinic radiation which responds to radiation primarily via a self-propagating reaction initiated by the said radiation to effect the said relative ease of removal, in which the blend is positive acting so that self-propagating reaction initiated by the said radiation increases relative ease of removal and in which the modifier is a polymer which is less soluble in the said developing agent than is the matrix polymer so that the blend, in turn, is less soluble in the developing agent wherein actinic radiation results in depolymerization to permit selective removal of modifier in irradiated portions of the said processing layer.

Abstract

Claims29