Laser Micromachining of Chemically Altered Polymers

During the last decade laser processing of polymers has become an impoxtant field of applied and fundamental research. One of the most promising proposal, to use laser ablation as dry etching technique in photolithography, has not yet becume an industrial application. Many disadvantages of laser ablation, compared to conventional photolithography, are the result of the use of standard polymers. These polymers are designed for totally differeat applications, but are ampared to the highly specialiied photoresist. A new approach to laser polymer ablation will be the development of polymers, specially designed far high resolution laser ablation. These polymers have photolabile groups in tbe polymer backbone, which decmpse upon laser inadiation or standaad polymers are modified for ablation at a specific irradiation wavelength. The absorption maximum can be tailored for specific laser emission lines, e.g. 351,308 and 248 nm lines of excimer lasers. We will show that with this approach many problems associated with the application of laser ablation for photolithography can be solved. The mechanism of ablation for these photopolymers is photochemical, whereas for most of the standard polymers this mechanism is photothermal. The photochemical decomposition mechanism results in high resolution ablation with no thermal damage at the edges of tbe etched structures. In addition there are no &posited ablation products or surftce modifications of the polymer after ablation.