Papers by Author: Matthias Müller

Abstract: The continuing shrinking of the component dimensions in ULSI technology requires junction depths in the 20-nm regime and below to avoid leakage currents. These ultra shallow dopant distributions can be formed by ultra-low energy (ULE) ion implantation. However, accurate measurement techniques for ultra-shallow dopant profiles are required in order to characterize ULE implantation and the necessary rapid thermal annealing (RTA) processes.

Abstract: Thin films of high-k material are becoming more and more used for semiconductor devices. A further shrinking of the devices requires also a further reduction of the high-k film thickness. With this reduction of the high-k thickness down to just a few nanometers two technical challenges have to be addressed. The first one is the ALD process for the deposition of the high-k material. Usually the ALD process can be well controlled by tuning the number of process cycles. But it is theoretically predicted [1] that the growth-per-cycle of the first cycles can be different than the steady growth-per-cycle which is obtained for high cycle numbers. This effect is caused by a not fully covered initial surface during the first cycles. Only when the deposited material forms a closed surface and the surface probabilities are the same for each following cycle the deposition rate will be constant. The second challenge is that the electrical properties of thin films with a thickness of a few nanometers are significantly determined by the quality of the interface between the film and the substrate.

Abstract: Reference samples were produced for development, benchmarking and comparison of analytical techniques based on mass spectroscopy as TD-GCMS and TOF-SIMS and x-ray analysis as TXRF-NEXAFS. Organic contaminants representing plasticizers, disinfectants and flame retardants were chosen. The contaminants were selected with respect to reliable detection using the above analytical techniques. The stability of the reference samples produced with dethylphtalate, triclosane, and tetrabrombisphenol A on silicon stripes or wafers with a diameter of 200 mm was found to be approx. 10 days. The comparison of the techniques showed that the mass spectroscopy methods allowed reliable qualification of organic surface contamination. TD-GCMS quantifies and identifies the volatile organic compounds whereas TXRF quantifies the carbon contamination, especially the non-volatile, on sample surfaces.

Abstract: The European Integrated Activity of Excellence and Networking for nanoand Micro-Electronics Analysis (ANNA), www.ANNA-i3.net, has addressed the further development and assessment of methodologies for the detection of low concentration inorganic contaminants on and in silicon as well as for novel materials. The comparison of various analytical techniques available to the ANNA partners helped to identify the degree of comparableness of results revealed at different installations. The assessment of improved methodologies as well as the reliability of quantification and calibration procedures of specific analytical techniques such as Total-Reflection X-ray Fluorescence (TXRF) analysis has been of particular interest.

Abstract: The last decennia, a lot of effort has been made to introduce new channel materials in a Si process flow. High mobility materials such as Ge need a good gate stack passivation in order to ensure optimal MOSFET operation. Several routes for passivating the Ge gate stack have been explored in the last years. We present here the S-passivation of the Ge gate stack: (NH₄)₂S is used to create a S-terminated Ge surface. In this paper the S-treatment is discussed. The S-terminated Ge surface is not chemically passive but can still react with air. After gate oxide deposition, the Ge-S bonds are preserved and an adequate passivation is found for pMOS operation.

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: As the detection of inorganic contaminants is of steadily increasing importance for the improvement of yields in microelectronic applications, the aim of one of the joint research activity within the European Integrated Activity of Excellence and Networking for Nano- and Micro-Electronics Analysis (ANNA, site: www.ANNA-i3.org) is the development and assessment of new methodolo¬gies and metrologies for the detection of low concentration inorganic contaminants in silicon and in novel materials. A main objective consist in the benchmarking of various analytical techniques avail¬able in the laboratories of the participating ANNA partners, including the improvement of the res¬pective detection limits as well as the quantitation reliablity of selected analytical techniques such as total-reflection x-ray fluorescence (TXRF) analysis.

Abstract: The continuous dimensional reduction drives the development of metrology, analysis and characterization for nano and micro electronics. An enormous worldwide R&D effort focuses on the understanding and controlling materials properties and dimensions at atomic level. Crucial for groundbreaking new developments is the availability of appropriate analytical infrastructures providing techniques with information depths well adapted to the nanoscaled objects of interest. This requires widely accessible, independent complementary metrology, analytical techniques, and characterization. For example new materials and the demand of improved detection sensitivities for contaminants provide huge challenges for the capabilities of current analysis equipment and expertise. At the same time, the availability of complementary competences is crucial for advancement of analytical methodologies through cross-comparison, round-robin, and benchmarking of results. This paper describes the formation of an independent analytical infrastructure within Europe having the expertise and competence to solve metrology problems for development of nanotechnologies. Furthermore, a strategy is shown to establish independently operating ‘Golden Laboratories’ for complementary and reliable metrology, analysis, and characterization adapted to the requirements of industrial partners.