Aromatic bisazides

A modification of these systems involving replacement of poly (4-vinylphenol) with poly(methyl isopropenyl ketone) (PMIPK) was reported by Nakane and co-workers (41). Although PMIPK is a positive-acting singlecomponent resist in the deep UV, it functions as a negative resist when mixed with an aromatic bisazide such as 2,6 di(4-azidobenzylidene)-4-... 

A higher contrast material was described being a mixture of poly(methyl iso-propenyl ketone) and aromatic bisazides Exposure to UV light results in the formation of nitrenes, which insert into C—H bonds of the polymer. After exposure, a difference in etch rate in an oxygen plasma is observed but this difference increases considerably upon baking. The reported etch rates after baking are 100 nm/min for exposed material and 600 nm/min for unexposed material. 

Iwayanagi (40) recently extended this system into the mid-UV range by changing the sensitizer to an aromatic monoazide compound (4-azidochalcone). Insolubilization of this mid-UV resist does not result in a cross-linked matrix as occurs with the bisazide sensitized MRS. The primary reaction appears to be insertion of the reactive nitrene into a C-H bond on the ring, forming a secondary amine. 

---