Post-exposure curing

Methods 1 and 3 have been utilized in dry developed resist systems. To our knowledge, there are no resist systems commercially available that depend on post-exposure treatment other than the post-curing effect in negative electron beam resists mentioned earlier. Since such systems are still largely in the research phase we will not discuss them here but rather refer the reader to the literature for more detailed descriptions (44-50). 

Lithographic Evaluation. Films were spin-coated onto silicon substrates from 10% solutions in chlorobenzene and prebaked at temperatures between 90 °C and 100°C for 1 hour to ensure solvent removal. The thickness of each film was about 5000 A. Electron beam exposures were performed on the AT T Bell Laboratories electron beam exposure system (EBES-I) operating at 20 kV with a beam adress and spot size both equal to 0.25 . A minimal cure time was required since there is no post-exposure reaction (4,16). 

In the vulcanisation of rubber products, aftercure is the amount of cure received after the termination of the cure proper, e.g., the cure effect resulting from the heat remaining in the product after removal from the mould or autoclave. The term is also applied to the continuation of the curing effect that results from exposure of the article to heat in use, or from accelerated ageing. See Post Cure. 

To complete these tests, four new samples were prepared and cured as described in earlier sections. The first sample was held in reserve as the post cure control. The remaining samples were heated to 1400" C for 1, 2, and 4 hr. The 1400°C temperature was selected because nearly half of the room temperature fluorescence was emitted for this TSP in the previous test series. A separate sample was used in each duration test. The resulting emission spectra (ultraviolet excitation) for Y2O3 Eu in a Resbond 793 binder with varied thermal cycling duration are shown in Eig. 5. After a 1-hr exposure, there is a noticeable decrease in fluorescence intensity. In fact, the decrease in intensity in the first hour of the test is surprising, as the previous results... 

The first method, which provides quantitative and reliable information on the extent of cure, is a time-consuming technique. In addition, there is certain error included in the measurement owing to the post-polymerization reaction, which occurs during the lapse of time between the end of exposure and the measurements... 

To minimize such effects, low heating rates should be adopted in DMA tests. In this way, however, material time dependent behavior may become more significant because of the longer thermal exposure, as well as any post-curing effects during the thermal exposure. 

Cationically cured UV laminating adhesives based on cycloaliphatic epoxies are emerging as an alternative to solvent-hased adhesives. The dark cure of cationics allows UV exposure and post lamination in hne. This process does not require UV exposure through the plastic barrier material. 

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