Papers by Keyword: TXRF

Abstract: Chemical Mechanical Planarization (CMP) is a key process for IC manufacturers. Tungsten (W) is an important material for connecting logic elements and for connecting memory elements, thanks to its excellent planarization, filling, mechanical and electromigration properties. W slurries are developed to remove high amounts of W via an abrasive, in conjunction with an oxidizer. After the polishing process, the planarized surface is contaminated with abrasive particles, organic residue, pad debris and metal cations through covalent or hydrogen-bonding, electrostatic and Van der Waals attractions. Post-CMP cleaning is required to remove all these contaminants while exhibiting low galvanic and chemical corrosion. Formulated cleans are needed to meet all these requirements. The performance of formulated W/TiN post-CMP cleaners for N10 and N7 has been evaluated. The newly developed formulations show a factor 4 reduction in metal surface contamination (from ~2 x 10¹² atoms/cm² to ~ 5 x 10¹¹ atoms/cm²), which is important to prevent dielectric breakdown. Very low particulate and organic residue defectivity was additionally confirmed by different surface characterization techniques: XPS, FTIR, contact angle/surface energy.

Abstract: We have found that to the detection sensitivity of Total reflection X-ray fluorescent spectrometry (TXRF), the total volume of trace particles generated by vapor phase treatment (VPT) must be increased and metal atoms need to be included in the particles. The detection sensitivity for Cu is enhanced by assisting Cu ionization in the liquid drops condensed form the vapor. We consider that since incident and reflected X-rays resonate 30nm from the surface, the total reflection intensity of metals included in the particles is enhanced.

Abstract: We studied the detection by TXRF of several transition metals on the surface of III-V materials for high mobility channel. It has been found that the lower limits of detection of some transition metals on the surface of III-V materials become higher than that on the Si surface because the sum peaks or Raman scattering peaks as well as the fluorescent X-ray main signals from the materials themselves partially cover those from the transition metals

Abstract: Silicon solar cells are the dominating technology in photovoltaics (PV) industry and have a market share of more than 85% of the modules produced for roof top installations.

Abstract: High-k gate dielectrics and metal gate electrodes have become essential for emerging device technologies because they enable the continuous scaling down of devices while maintaining a high performance [. However, since they are composed of novel metallic elements that have never before been used in conventional processes, special care must be taken when handling these materials in the production line. In particular, cross-contamination that occurs due to transporting contamination via processed wafers can cause serious problems such as deterioration of device properties and yield loss [. The process of cleaning the backside and bevel of a wafer is now increasingly important for avoiding these problems. To date, there has been no detailed evaluation of contamination removal on various films performed for elements such as hafnium, which is one of the key elements in high-k/metal gate technologies. In this study, we evaluated hafnium contamination on three types of wafer surface after the cleaning process and investigated the cause of different residual amounts of hafnium contamination on the different wafers.

Abstract: In this article, we report a new cleaning method for silicon carbide (SiC) wafers. We found that the dipping treatment in hydrogen fluoride (HF) solution damages the SiC in the “RCA cleaning process”, so we have designed a new cleaning method that does not use HF and reduced the cleaning process to three steps. The characteristic factor of this new method is using a transition metal complex. Generally, no metals have been used for wafer cleaning, but we deliberately used metal and found it could clean the wafer surface very well. After cleaning, the atomic force microscope (AFM) and “Candela” images showed that the particles on most parts of the SiC surface had been removed and the contact angle for ultra-pure water became very low.

Abstract: In the last years several projects have been developed for treatment of fly ash with the aim of their reuse. A final target of these researches is to evaluate the real performance of the new materials obtained by the treatment and the actual and, if the case, potential markets for the foreseen products. Indeed, the use of a recycled inert would reduce the consumption of natural resources and this is one of the main environmental EU target. Examples are clinkering, road asphaltation and some construction work where specific performances are requested. Moreover, the reuse of inerted fly ash will obtain a reduction of carbon dioxide produced by the necessary treatments of primary materials, as limestone in concrete production. At the University of Brescia (Italy) a new process, based on colloidal silica medium, has been developed to inertise fly ashes, containing heavy metals. This approach appears to be quite promising for industrial application in view of the easiness that can be foreseen in applying it to existing plants treating industrial fly ash. The obtained inert product is a powder, that can be employed as a filler in several application. In this work we present first results about characterization of this new powder material, that can be applied as a filler.

Abstract: The formation of self-assembled monolayers (SAMs) by specific organic molecules with appropriate anchor groups on semiconductor surfaces may be used to probe the chemical state and quality of the surface or to achieve surface passivation. Molecules with thiol anchor groups are able to bond to hydrogen-terminated germanium surfaces (Ge-S bond). We have prepared SAMs of alkylthiols with different head groups on germanium. Since the surface preparation of germanium is neither well understood nor developed, the controlled preparation of an oxide-free completely H-terminated surface which is a prerequisite for SAM formation of alkylthiols turned out to be a major challenge. Several approaches have been studied. The characterization of the germanium surface prior to and after SAMs formation has been performed by AFM, XPS, Synchrotron-TXRF and -NEXAFS.

Abstract: In the semiconductor industry, the edge exclusion of processed wafers is decreasing to accommodate more integrated circuits. With this trend, there is a higher risk of detrimental contamination at the wafer edge and bevel making the monitoring for metallic contamination in these areas critical. Cross contamination from the edge and bevel can occur at many processing steps. For example, metals can spread from the wafer edge, bevel and backside to the wafer’s surface in a wet cleans process. In immersion lithography, the water drop that is scanned across the wafer could transport contamination from the edge and deposit it across the wafer surface. Contamination on wafer edge and bevel can have many origins; handling systems in every process tool, reaction products in etching, and residuals of new materials in high-k for CVD and PVD, for example. To know what metallic contamination is present, and to investigate the causes are essential for wafer edge control.