Abstract
As the memory capacity of dynamic random access memory (DRAM) device is increased continuously, there are demands on a new electrode material to decrease a leakage current and a new material with a high dielectric constant to increase memory capacity. In order to apply these materials in DRAM device, a new submicron cleaning method must be used to remove the photoresist (PR) and polymer. A new approach in removing the I-line PR and metallic-polymer generated by a reaction of the I-line PR and ruthenium during reactive ion etching (RIE) of a storage node, using a dry laser cleaning technology, was investigated in this study. A KrF excimer laser with a wavelength of 248 nm was used as the light source to remove the I-line PR and metallic-polymer on the bottom and sidewall of the storage node electrode. The I-line PR and metallic-polymer were removed perfectly with three laser pulses at a laser fluence of 130 mJ/cm 2 without a damage of ruthenium used as storage node electrode. The extent of removal of the I-line PR and metallic-polymer was determined by scanning electron microscope (SEM). To solve a non-uniformity of the Gaussian profile, a homogenizer was used to provide a uniform beam profile and we obtained the uniform result in the total area of storage node cells. The various mechanisms to remove the I-line PR and metallic-polymer were discussed by considering the photochemical and photothermal effects.
Published Version
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