Metal films contamination control

TXRF is frequently used for contamination control and ultrasensitive chemical analysis, in particular in relation to materials used in semiconductor manufacturing [278,279], and metallic impurities on resin surfaces, as in PFA sheets [279,280], TXRF has been used by Simmross et al. [281] for the quantitative determination of cadmium in the four IRMM polyethylene reference materials (VDA-001 to 004). Microsamples (20-100 ig) from each reference material were transferred by hot pressing at 130 °C as 3 xm thin films straight on to quartz glass discs commonly used for TXRF analysis. The results obtained were quite satisfactory (Table 8.50). Other reports of the forensic application to plastic materials by TXRF have appeared [282], including a study of PE films by elemental analysis [283],... 

A general criterion for optimizing the metal CMP process is the controlled regulation of material removal, while simultaneously securing the processed surface from various CMP-related defects like scratches, dishing, delamination, erosion, contamination, line deformation, and galvanic corrosion (Baneijee and Rhoades, 2008 Choi and Korach, 2009). The considerations for improving material removal rates (MRRs) are mostiy relevant in the context of bulk Cu CMP, but are relatively less critical for the thin (<5 nm) diffusion barrier metal films. However, the requirement for defect control continues to remain a major issue in essentially all cases of metal CMP (Chandrasekaran et al., 2004). 

Passive films. Austenitic stainless steels and hardenable stainless steels such as martensitic, precipitation hardening, and maraging stainless steels are seldom coated, but their corrosion resistance depends on the formation of naturally occurring transparent oxide films. These films may be impaired by surface contaminants such as organic compoimds or metallic or inorganic materials. Treatments are available for these materials to clean and degrease surfaces and produce imiform protective oxide films under controlled conditions. These usually involve immersion in an aqueous solution of nitric acid and a dichromate solution. 

Prange et al. [809,810] carried out multielement determinations of the stated dissolved heavy metals in Baltic seawater by total reflection X-ray fluorescence (TXRF) spectrometry. The metals were separated by chelation adsorption of the metal complexes on lipophilised silica-gel carrier and subsequent elution of the chelates by a chloroform/methanol mixture. Trace element loss or contamination could be controlled because of the relatively simple sample preparation. Aliquots of the eluate were then dispersed in highly polished quartz sample carriers and evaporated to thin films for spectrometric measurements. Recoveries (see Table 5.10), detection limits, and reproducibilities of the method for several metals were satisfactory. 

Foreign contamination is typically first discovered by quality control checks of the finished product or by the loss of the web for film processes. If a melt filtration system is installed downstream of the extruder, the larger size particles will be collected. After the contaminants are collected they must be analyzed for composition. Some types of contaminants are easily identified using a microscope or hand lens and include paper and cloth fibers, dirt, and metal fragments. Other contaminants such as gels or foreign resins are not as easily identified, and their identification often requires advanced analytical procedures. Many resin manufacturers offer these types of services to their customers. After the contaminant is identified, the source must be determined and then eliminated. Elimination of the source can be simple for common contaminants but can be a challenge for contaminants that exist at a very low level. 

Tacticity is required for the synthesis of crystalline thin polysilane films used for optical and semiconductor devices. Modern synthetic routes allow control over the conformation and tacticity of polysilane molecules used as precursors for thin layers of photoresists, photoconductors and nonlinear optical phases in complex semiconductor and (opto)electronic devices. These properties can be exploited only if the synthesis method ensures a minimal level of contamination, especially with oxygen and metals, and special care is taken to limit electronic-grade polysilanes to a level of contamination on the order of a few ppm in the case of oxygen and in the ppb range for metals. The reactivity of polysilane toward oxygen has forced placing the devices in a helium environment during measurement procedures.36... 

In certain applications of plasma polymerization, the incorporation of electrode material, particularly in a controlled and designed manner, is extremely useful and becomes a great asset in LCVD. For instance, a thin layer of plasma polymer of methane with a tailored gradient of copper has been shown to improve the adhesion of the thin layer to a copper substrate as well as the adhesion of metal to a polymer film [3,4]. In general applications of LCVD, in which the metal contamination should be avoided, it is important to select the electrode material that has low sputtering yield. Titanium has been used successfully in such cases. 

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