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Not only are amorphous oxide semiconductor thin film transistors (TFTs) extremely sensitive to the processing of the active layer, but subsequent layer processing can also impact the performance. Due to this sensitivity, many surface treatments and passivation techniques for the active layer have been developed, but the influence of the etching of the active layer itself has not been explored extensively. These etch steps are especially critical in the manufacture of flexible microelectronics, for which process conditions are inherently limited by thermal stability of the plastic (

The spatial distribution of polymer photoresist and deuterium labeled base developer highlights a fraction of the line edge that swells but does not dissolve. This residual swelling fraction remains swollen during both the in situ aqueous hydroxide dissolution (development) and water rinse steps uncovering that the final lithographic feature is resolved by a collapse mechanism during the drying step. These new insights into the mechanism of lithographic feature formation were enabled by contrast variant neutron reflectivity methods with nanometer resolution.

The effects of amine base quencher on the photoacid catalyzed deprotection reaction-diffusion front in model photoresists were measured by combination of neutron reflectivity and Fourier transform infrared spectroscopy. Modulation in the location of the base with respect to the diffusing photoacid catalyst changes the spatial reaction extent and illuminates the complex role of the base on the shape of the reaction-diffusion front. Despite similar total extents of reaction, a comparison between uniform base and model photodegradable base distributions demonstrates distinct reaction time and base concentration effects on the deprotection profile shape. These differences arise from the modification of the initial deprotection extent due to both the neutralization of the photoacid and the influence of the changing photoresist composition on the reaction-diffusion process. The use of the model photodegradable base results in a sharper front due to these effects. Lastly, aqueous hydroxide development of these l...

The effect of exposure dose on the latent image deprotection profile in a model extreme ultraviolet (EUV) photoresist polymer, poly(hydroxystyrene-co-d9-tert-butyl acrylate), is measured with neutron reflectometry. As the photoacid concentration is increased by exposure dose, the spatial extent of propagation increases but eventually becomes self-limited by the products of the reaction. A long-range deprotection path occurs with diffusion length between 10 and 100A, while an additional subnanometer short-range deprotection length scale proceeds monotonically with dose. These measurements show that the photoacid diffusion length into unexposed regions of a photoresist is limited even in the absence of base quencher additives. These fundamental data can be used to highlight materials effects on photoresist processing and to improve quantitative models for EUV photoresists needed at the sub-32‐nm half pitch lithography.