Residual stress within nanoscale metallic multilayer systems during thermal cycling
Residual stress within nanoscale metallic multilayer systems during thermal cycling
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DOI：
10.1016/j.msea.2015.09.082
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发表时间：
2015-11
期刊：
影响因子：
6.4
通讯作者：
D. R. Economy;M. Cordill;E. A. Payzant;M. S. Kennedy
中科院分区：
文献类型：
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作者：
D. R. Economy;M. Cordill;E. A. Payzant;M. S. Kennedy
纳米级金属多层膜的预期应用将包括宽的温度范围。由于薄膜残余应力已被称为改变系统的可靠性，在新的膜结构与高界面密度的应力发展应确定潜在的长期性能障碍的特点。为了理解纳米级金属多层膜中热应力演变的因素，根据在25°C和400°C之间循环期间收集的曲率测量值计算了粘附到Si衬底的Cu/Nb系统中的应力。此外，在每种类型的组件层内的应力计算从主峰位置的位移从原位加热的X射线衍射。跟踪了金属多层膜中膜结构（层厚度）和层顺序的影响，并与单片Cu和Nb膜（总厚度为1 μm）进行了比较。分析表明，纳米级金属多层膜（具有20 nm和100 nm的单个层厚度）的热弹性斜率取决于热膨胀失配，组件的弹性模量，以及界面密度。层厚度（即界面密度）影响热弹性斜率大小（20 nm Cu/Nb为−1.23±0.09 MPa/°C，100 nm Cu/Nb为−0.89±0.03 MPa/°C），而层顺序对初始热循环后的应力响应影响最小（100 nm Cu/Nb为−0.82±0.07 MPa/°C）。当将单片Cu和Nb膜的应力响应与Cu/Nb系统的应力响应进行比较时，纳米级金属多层在高于200°C时显示出与Nb单片膜相似的应力增加，表明Nb组分在应力发展中比Cu起更大的作用。相特定的应力计算（Cuvs.Nb）从X-射线衍射峰位移在20 nm的Cu/Nb在加热过程中收集显示，在一个多层膜内的组件层响应类似于他们的单片对应。
Projected applications for nanoscale metallic multilayers will include wide temperature ranges. Since film residual stress has been known to alter system reliability, stress development within new film structures with high interfacial densities should be characterized to identify potential long-term performance barriers. To understand factors contributing to thermal stress evolution within nanoscale metallic multilayers, stress in Cu/Nb systems adhered to Si substrates was calculated from curvature measurements collected during cycling between 25°C and 400°C. Additionally, stress within each type of component layers was calculated from shifts in the primary peak position fromin-situheated X-ray diffraction. The effects of both film architecture (layer thickness) and layer order in metallic multilayers were tracked and compared with monolithic Cu and Nb films (1 µm total thickness). Analysis indicated that the thermoelastic slope of nanoscale metallic multilayer films (with 20 nm and 100 nm individual layer thicknesses) depends on thermal expansion mismatch, elastic modulus of the components, and also interfacial density. The layer thickness (i.e. interfacial density) affected thermoelastic slope magnitude (−1.23±0.09 MPa/°C for 20 nm Cu/Nbvs.−0.89±0.03 MPa/°C for 100 nm Cu/Nb) while layer order had minimal impact on stress responses after the initial thermal cycle (−0.82±0.07 MPa/°C for 100 nm Cu/Nb). When comparing stress responses of monolithic Cu and Nb films to those of the Cu/Nb systems, the nanoscale metallic multilayers show a similar increase in stress above 200°C to the Nb monolithic films, indicating that Nb components play a larger role in stress development than Cu. Phase specific stress calculations (Cuvs.Nb) from X-ray diffraction peak shifts in 20 nm Cu/Nb collected during heating reveal that the component layers within a multilayer film respond similarly to their monolithic counterparts.