Detection and Identification of Organic Contamination on Silicon Substrates

Roche, Agnès; Marthon, S.; Ple, J. F.; Rochat, N.; Danel, Adrien; Olivier, Michel; Juhel, M.; Tardif, François J.

doi:10.4028/www.scientific.net/ssp.76-77.111

Cited by 8 publications

(4 citation statements)

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“…The level of these contaminants significantly increased if the samples were stored in open boxes with laminar airflow over them. Similarly, Roche et al, using a variety of different methods [i.e., ellipsometry, water contact angle, infrared spectroscopy, thermal desorption coupled with ion mobility spectroscopy, thermal desorption coupled with gas chromatography/mass spectrometry, and time-of-flight secondary ion mass spectroscopy (ToF-SIMS)] demonstrated that storage in closed containers reduces the contamination compared with the use of open ones. The ToF-SIMS results presented by Roche et al also allowed the identification of the fragments of the molecular species adsorbed on silicon surfaces (i.e., SiC 3 H 9 + , C 8 H 5 O 3 + , Cl – , F – , and SO 4 2– ).…”

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confidence: 99%

“…In particular, for carbon-based materials previously exposed to air, their carbon K-edge NEXAFS spectra, even when corrected using any of the approaches outlined by Watts et al 52 , are a convolution of the spectrum of the sample of interest and the spectrum of the adventitious carbon contamination on its surface since the thickness of the latter (typically <2 nm 55 ) is smaller than the information depth at the carbon K-edge ( Figure 1). While the thickness of the adventitious carbon contamination has been shown to depend on the sample preparation procedure and history 55,56 , no comprehensive characterization of its composition and structure has yet been published. A previous study by Storm et al 57 contamination layer (topmost layer).…”

Section: Introductionmentioning

confidence: 99%

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Accounting for Nanometer-Thick Adventitious Carbon Contamination in X-ray Absorption Spectra of Carbon-Based Materials

et al. 2014

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Near-edge X-ray absorption fine structure (NEXAFS) spectroscopy is a powerful technique for characterizing the composition and bonding state of nanoscale materials and the top few nanometers of bulk and thin film specimens. When coupled with imaging methods like photoemission electron microscopy, it enables chemical imaging of materials with nanometerscale lateral spatial resolution. However, analysis of NEXAFS spectra is often performed under the assumption of structural and compositional homogeneity within the nanometer-scale depth probed by this technique. This assumption can introduce large errors when analyzing the vast majority of solid surfaces due to the presence of complex surface and near-surface structures such as oxides and contamination layers. An analytical methodology is presented for removing the contribution of these nanoscale overlayers from NEXAFS spectra of two-layered systems to provide a corrected photo-absorption spectrum of the substrate. This method relies on the subtraction of the NEXAFS spectrum of the overlayer adsorbed on a reference surface from the spectrum of the two-layer system under investigation, where the thickness of the overlayer is independently determined by X-ray photoelectron spectroscopy (XPS). This approach is applied to NEXAFS data acquired for one of the most challenging cases: air-exposed hard carbon-based materials with adventitious carbon contamination from ambient exposure. The contribution of the adventitious carbon was removed from the as-acquired spectra of ultrananocrystalline diamond (UNCD) and hydrogenated amorphous carbon (a-C:H) to determine the intrinsic photoabsorption NEXAFS spectra of these materials. The method alters the calculated fraction of sp 2 -hybridized carbon from 5 to 20%, and reveals that the adventitious contamination can be

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confidence: 99%

Section: Introductionmentioning

confidence: 99%

Accounting for Nanometer-Thick Adventitious Carbon Contamination in X-ray Absorption Spectra of Carbon-Based Materials

et al. 2014

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“…In this regard, it will be interesting to explore surface-sensitive techniques that can provide detailed structural information. Time-of-flight secondary ion mass spectrometry (TOF-SIMS) and thermal desorption coupled with ion mobility spectrometry (TD-IMS) have been shown to be effective in determining the chemical structure of organic contaminants on a silicon wafer. It will be interesting to explore these technologies for 2D materials.…”

Section: Discussionmentioning

confidence: 99%

Effect of Environmental Contaminants on the Interfacial Properties of Two-Dimensional Materials

et al. 2022

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Metrics & MoreArticle Recommendations CONSPECTUS:The surface of 2D materials can spontaneously adsorb and react with molecules in the environment during their processing and storage. This effect, while having a significant impact on many properties of 2D materials, is not always recognized and accounted for in the research involving them. This Account summarizes our recent work in understanding how the ambient environment impacts the properties of 2D materials and its mitigation strategies. We highlight graphene and hydrocarbons in our discussion and complement it with selected studies involving other 2D materials as well as water and oxygen.When graphene and graphite are exposed to air and water, their surfaces adsorb the residue hydrocarbons, typically at part-pertrillion to part-per-billion levels, in the environment. The adsorption of hydrocarbons reduces the surface energy of graphene and graphite and creates a barrier between them and the electrolyte. As a result, the wettability and electrochemical properties of graphene and graphite can be significantly altered by mere exposure to the ambient environment. These changes can be very significant yet highly variable depending on the local environment: several hours of air exposure can increase the water contact angle of graphene by up to 40°and reduce the double-layer capacitance of graphite by up to 50%! The high hydrophobicity and poor electrochemical performance of pristine graphitic carbons, once believed to be intrinsic properties of these materials, are largely due to unintentional surface contamination. The same type of hydrocarbon adsorption was reported for many other 2D materials, such as MoS 2 , hexagonal BN, and mica. In the case of mica, which is highly ionic in nature, the adsorption of hydrocarbons disrupts its interaction with ionic liquid and alters the self-assembly structure of ionic liquid at the mica surface. Similarly, water also impacts the surface properties of graphene in several ways. Water vapor can compete with hydrocarbons for adsorption onto the surface of graphene, thus reducing the rate of hydrocarbon contamination. Water can intercalate between graphene and some of its supporting substrate, altering their interactions. Finally, water enhances the doping of 2D materials by O 2 by promoting an electrochemical doping mechanism involving the O 2 /H 2 O redox couple.Reducing and reversing the surface contamination of 2D materials can greatly enhance material and device performances. While completely stopping the contamination is still challenging, a high-humidity environment is shown to reduce the rate of contamination, as mentioned above. For samples already contaminated by airborne hydrocarbons, their surface properties can be partially restored by treatment in high-vacuum, high-temperature, or mildly oxidative environments.

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“…It is thus natural to consider TOFSIMS as a good candidate for the analysis of organic contamination. This approach has already been studied by several groups [8][9][10]. This method is used, for instance, in the analysis of the presence of organic contamination or residue after post-CMP cleaning.…”

Section: Cleaning Of Silicon and Drying Technologymentioning

confidence: 99%

Advanced Material Characterization by TOFSIMS in Microelectronic

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Materials for Information Technology

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Detection and Identification of Organic Contamination on Silicon Substrates

Cited by 8 publications

References 0 publications

Accounting for Nanometer-Thick Adventitious Carbon Contamination in X-ray Absorption Spectra of Carbon-Based Materials

Accounting for Nanometer-Thick Adventitious Carbon Contamination in X-ray Absorption Spectra of Carbon-Based Materials

Effect of Environmental Contaminants on the Interfacial Properties of Two-Dimensional Materials

Advanced Material Characterization by TOFSIMS in Microelectronic

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