Papers by Keyword: Photoresist Removal

Abstract: Removal of highly ion-implanted photoresist on the trench-structured GaAs was conducted by mixtures of organic solvents with additives. The ion implanted KrF photoresist on trench-structured GaAs was completely removed at 30 °C when an additive was added to the DMSO+ acetonitrile (AcN) solution. In addition, the removal rate of the implanted photoresist could be increased in DMSO+AcN+additive solution. It was also observed that the DMSO+AcN+additive solution did not cause significant material loss on the GaAs surface during the photoresist removal process.

Abstract: We investigated an alternative technology to conventional organic material removal that replaces sulfuric acid and hydrogen peroxide (SPM). We assumed that the removal model of organic material by ozone gas was absorption of oxygen radicals, generated by thermal decomposition of ozone, on a surface and subsequent reaction with organic materials. Then we characterized the correlation between removal rate and process parameter, and the validity of the model was verified. It also showed that this method is effective for high dose, ion-implanted photoresists.

Abstract: Approximately 20% of the processing steps in integrated circuit (IC) fabrication involve surface cleaning and removal of photoresist and plasma etch residues. Continuous device minimization requires the use of thin films (<20 nm), closely spaced features, and ultra shallow junctions (<50nm); as a result, the challenges associated with effective surface cleaning are intensified. In addition, to insure high device performance, incorporation of alternate materials such as copper, ruthenium, and molybdenum, porous low dielectric constant SiO2-based insulators, and hafnium or zirconium oxides or silicates into device structures is taking place. Integration of these materials into working devices requires precise control of surface properties. In order to eliminate damage to films or substrates, avoid modification of surfaces, promote contaminant removal rates and enhance process control, approaches such as use of downstream plasmas, liquid cleaning with low concentrations of reactive chemicals, mechanical agitation, and liquid or particle jets have been implemented [1].

Abstract: The introduction of metal gates and high-k dielectrics in FEOL and porous ULK dielectrics in BEOL presents severe issues [1] and leads to the requirement of new chemistries and processes. A major challenge in cleaning is the removal of photoresist (PR) in both FEOL and BEOL. In current semiconductor device fabrication flow, the photoresist strip process in FEOL is mostly achieved by applying a sequence of plasma ashing followed by a wet-clean step with sulfuric-peroxide mixture (SPM). But in general, ashing leads to strong oxidation or etching of silicon substrate. Hence, several approaches for ashless PR strip have been reported, such as hot SPM [2] and the combination of a pre-treatment using high velocity CO2 aerosol [3].

Abstract: Stripping high-dose ion-implanted (HDI) photoresists is considered as one of the most challengeable processes in the semiconductor manufacturing due to the difficulty of both removing crust (or carbonized layer) formed during the ion implantation and preventing the silicon recess after subsequent cleaning. The HDI photoresists are conventionally removed by using a two-step process, low-pressure plasma ashing in a single-wafer tool followed by SPM-based wet stripping in a batch immersion tool. Alternative HDI-resist strip methods have been proposed, such as a combination of physical-force pretreatments followed by more traditional wet cleaning steps [1], a SPM-based all-wet process at extremely high temperature (≥ 200°C) [2], and supercritical CO2 combined with chemical additive formulations [3].