Papers by Keyword: SC1

Abstract: This paper offers a preliminary study for the analysis of metallic contamination on front-end patterned wafers obtained by two different techniques based on the etching of the whole patterns, LPD-Bulk and VPD-Bulk coupled with an ICPMS. To elaborate the analysis of patterned wafers, methods were first verified and optimised on reference Si wafers. Both techniques are complementary methods for the etching of wafers. LPD-Bulk enables a fast etching of several micrometres of Si but with less precision than VPD-Bulk, which is more adapted for the etching of layers thinner than 1 micrometre. The intentional contamination in SC1 and H₂O bath of monitoring wafers showed that contamination in H₂O is better controlled due to the absence of chemical reactions, competition between oxidation and etching processes occurring during SC1. And diffusion of contaminants at the tested temperatures from 20°C to 80°C, does not occur. Heat treatment should be applied to allow the diffusion of metallic contaminants in the bulk of the wafers.

Abstract: The definition of sub-20 nm electronic devices for the newest generation of smart phones, computer and automotive is calling for very innovative FEOL wet chemical cleans. The electronic properties are very sensitive, in respect of the surface morphology on a Si-wafer. Most of the modern wet cleans are based on the RCA-clean [1]. Innovative cleans, like for example the IMEC-clean [2] and modified RCA clean were developed, using ozone-DIW mixture (O₃-DIW), in order to improve the cleaning performance [3], [4]. Since several years electrolyzed water (EW) is used in semiconductor manufacturing [5]. An electrochemical reaction is induced by an electrode and a small amount of ammonia hydroxide (NH₄OH) or ammonia sulfate and DIW [7].

Abstract: RCA clean has evolved since 1965 [1]. Typically used before critical thermal steps, depositions/etches, or after strip operations, these solutions are robust and reliable. Stringent semiconductor demands of shrinking feature size, increased contamination sensitivity and cost pressure have led to cleaning projects that improve performance and reduce chemical usage. One of the sources of contamination is the process chemicals themselves, where wafers are exposed to chemicals for etching or cleaning. Concerns over contamination are compounded in wet benches where chemical baths are re-circulated for periods up to 24 hours. Metal impurities can arise from insufficiently pure chemicals or water, tanks, carriers, plumbing components, chemical containers, incoming wafers and handling equipment. Strict chemical, DIW and material specifications as well as dilute chemistry and reduced temperature have benefited the industry as a whole. Trends such as lower temperature/concentration SC1, and higher temperature/concentration SC2 have reached a point of diminishing returns for metal contamination reduction. In the same way, chemical and water purity are well below detection, so improvements are difficult to quantify.[2]

Abstract: In back-end of line processing (BEOL), the polymer deposited on the dielectric sidewalls during the etch process must be removed prior to subsequent processing steps to achieve high adhesion and good coverage of materials deposited in the etched features [1, . Typically, this is done by a combination of a short plasma treatment and a diluted wet clean, or by wet cleans alone. On the one hand, for porous dielectric stacks, a mild plasma treatment that preserves the integrity of the low-k dielectrics would not be sufficient to effectively remove this residue. With regard to wet clean, diluted aqueous solutions (e.g. HF-based) are not efficient for polymer removal without etching the underlying dielectric to lift off the polymer, leading to unacceptable critical dimension (CD) loss. In addition, analytical techniques available for direct characterization of sidewall residues are limited. For a fast screening of potential chemistries capable of dissolving/removing polymer residues generated during the low-k etch, a model fluoropolymer was deposited on a blanket, checkerboard low-k substrate. The present study mainly focused on the characterization of model polymer after deposition (as-deposited) and after immersion in aqueous and solvent-based cleaning solutions. The polymer removal efficiency was influenced/ improved by UV treatments prior to wet clean processes. In the second part of the study, selected UV treatment conditions and cleaning solutions were applied to low-k patterned structures using Angle-resolved X-ray photoelectron spectroscopy (AR-XPS) to characterize the dielectric sidewall before and after UV modification and the subsequent cleaning process.