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The manufacture of ultra-large scale integration technology can impose significant strain within the constituent metallization because of the mismatch in coefficients of thermal expansion between metallization and its surrounding environment. The resulting stress distributions can be large enough to induce voiding within Cu-based metallization, a key reliability issue that must be addressed. The interface between the Cu and overlying capping layers is a critical location associated with void formation. By combining conventional and glancing-incidence X-ray diffraction, depth-dependent stress distributions that develop in Cu films and patterned features are investigated. In situ annealing and as-deposited measurements reveal that strain gradients are created in capped Cu structures, where an increased in-plane tensile stress is generated near the Cu/cap interface. The interplay between plasticity in Cu and the constraint imposed by capping layers dictates the extent of the observed gradients. Cu films possessing caps deposited at temperatures where Cu experienced only elastic deformation did not exhibit depth-dependent stress distributions. However, all capped Cu samples exposed to temperatures that induce plastic behavior developed greater tensile stress at the Cu/cap interface than in the bulk Cu film after cooling, representing a clear concern for the mitigation of metallization voiding.
Glancing-incidence X-ray diffraction (GIXRD) has been applied to the investigation of depth-dependent stress distributions within electroplated Cu films due to overlying capping layers. 0.65 μm thick Cu films plated on conventional barrier and seed layers received a CVD SiCxNyHz cap, an electrolessly-deposited CoWP layer, or a CoWP layer followed by a SiCxNyHz cap. GIXRD and conventional X-ray diffraction measurements revealed that strain gradients were created in Cu films possessing a SiCxNyHz cap, where a greater in-plane tensile stress was generated near the film / cap interface. The constraint imposed by the SiCxNyHz layer during cooling from the cap deposition temperature led to an increase in the in-plane stress of approximately 180 MPa from the value measured in the bulk Cu. However, Cu films possessing a CoWP cap without a SiCxNyHz layer did not exhibit depth-dependent stress distributions. Because the CoWP capping deposition temperature was much lower than that employed in SiCxNyHz deposition, the Cu experienced elastic deformation during the capping process. Cross-sectional transmission electron microscopy indicated that the top surface of the Cu films exhibited extrusions near grain boundaries for the samples undergoing the thermal excursion during SiCxNyHz deposition. The conformal nature of these caps confirmed that the morphological changes of the Cu film surface occurred prior to capping and are a consequence of the thermal excursions associated with cap deposition.
Glancing-incidence x-ray diffraction (GIXRD) has been applied to the investigation of depth-dependent stress distributions within electroplated Cu films due to overlying capping layers. Cu films, 0.65 μm thick, plated on conventional barrier and seed layers received a chemical vapor deposited (CVD) SiCxNyHz cap, an electrolessly deposited CoWP layer, or a CoWP layer followed by a SiCxNyHz cap. GIXRD and conventional x-ray diffraction measurements revealed that strain gradients were created in Cu films possessing a SiCxNyHz cap, where a greater in-plane tensile stress of approximately 180 MPa was generated near the film/cap interface as a result of constraint imposed by the SiCxNyHz layer during cooling from the cap deposition temperature. Although Cu films possessing a CoWP cap without a SiCxNyHz layer did not exhibit depth-dependent stress distributions, subsequent annealing introduced stress gradients and increased the bulk Cu stress. However, a thermal excursion to liquid-nitrogen temperatures significantly reduced tensile stresses in the Cu films.
New knowledge which shapes and supports technological advance continually emerges in the academic institutions. It is a result of publicly financed, scientific problem-solving. As such, its generation is not (primarily) guided by application interests. However, such knowledge usually carries some commercial business potential. National economies differ substantially both in their capacity to exploit the opportunities and in the pace of doing so. These differences have been found to be a major source of competitive advantages in global markets (Porter 1990). New production technologies and products drive the process of economic growth and allow innovation rents to be appropriated. In recent years, one question has therefore attracted increasing interest both in economic research and in politics (Nelson 1993, Edquist and McKelvey 2000, Salter and Martin 2001). How does new knowledge from scientific research find its way into the commercial part of the innovation system? How does it support technological advance?
In this chapter it is argued that the transfer is essentially an entrepreneurial process. On the one hand, to understand that process, it is necessary to recognize the kind of actions and services involved in the entrepreneurial reshaping of the division of labor. In general, entrepreneurship requires command over suitable resources. In the case of knowledge-based entrepreneurship, these are, in particular, resources enabling the access to, and the exploitation of, new technological knowledge. Therefore, an essential part of entrepreneurial activity here is the organization of the knowledge transfer from academic research to commercial production and marketing activities.
On the other hand, the entrepreneurial process cannot fully be grasped without recognizing the constraints under which it operates.
A biphasic outbreak of methicillin-resistant Staphylococcus aureus in intensive-care units of a German tertiary-care hospital afflicted 89 patients within 4 years. The spread of the outbreak most likely was facilitated by the contamination of mobile radiograph equipment. The outbreak was controlled by measures of hospital hygiene.
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