Thermomechanical stress and deformation effects in reactive Al/Ni multilayers for debonding

第一个项目阶段的目的是确定机械和热机械应力和约束的转变反应和相形成的Ni/Al多层膜的影响。这包括由机械载荷引起的内在和外在应力以及由几何约束引起的应力，例如多层膜上的钝化层。结果表明，外加应力对Al/Ni反应多层膜体系的反应行为及其相形成没有显著影响。然而，在调查期间，结果表明，在反应之后/期间，对于某些衬底，特别是单晶硅，发生RMS的裂纹形成或分层。此外，以这种方式改变反应速度和温度。因此，在反应期间和反应之后的内在热机械应力比外在应力重要得多。下一个项目阶段将考虑这些内在应力，并旨在利用这些内在应力来“按下按钮”选择性地剥离薄膜。因此，必须表征相应的热机械性能，并针对剥离过程进行定制。在微系统技术领域，剥离和分层应用对于拆卸和回收极其重要。单个组件只能从整个系统中分离出来，这很困难，或者不经济，因此可以更换，这严重损害了可持续性和循环经济（资源节约）。在应用领域，将RMS集成到微电子系统中将是必要的。除了应力引起的分层，长期稳定性的详细调查是必要的。RMS是否发生老化以及RMS在系统中可以保持活跃的时间-温度状态，即。e.保持自蔓延高温合成。 此外，RMS在这种情况下可以被视为功能连接，其需要测量层结构的热导率和电导率、机械性能以及在与低熔点焊料（电镀沉积或通过磁控溅射沉积）或在接合过程中单独添加的接合连接的情况下的兼容性。随后，将研究与低熔点焊料的兼容性（连接部分）。它是进一步研究是否理想的第二个RMS可以用于连接过程中最后，调查将在整个系统的可靠性和可行性方面进行。

The first project phase aimed at identifying the effects of mechanical and thermomechanical stresses and constraints on the transformation reaction and phase formation in Ni/Al multilayers. This included intrinsic and extrinsic stresses resulting from mechanical loading as well as stresses caused by geometrical confinements, such as passivation layers on multilayer films. So far, it could be shown that extrinsically applied stresses have no significant influence on the reaction behavior of the Al/Ni reactive multilayer system (RMS) and their phase formation. During the investigations, however, it was shown that after/during the reaction, crack formation, or delamination of the RMS takes place for certain substrates, especially on single-crystalline silicon. In addition, the reaction speed and temperature was changed that way. Thus, the intrinsic thermomechanical stresses during and after the reaction are much more important than extrinsic stresses. The next project phase will consider these intrinsic stresses and aims to exploit these intrinsic stresses for selective delamination of the films "at the push of a button", Therefore, the corresponding thermomechanical properties have to be characterized, and the tailored for debonding processes. Debonding and delamination applications are extremely important for dismantling and recycling in the field of microsystem technology. Individual components can only be separated from the overall system with difficulty or not economically and can thus be replaced, which strongly impairs sustainability and circular economy (resource saving). In the field of application, the integration of the RMS into a microelectronic system will be necessary. Besides the stress-induced delamination, detailed investigations of the long-term stability are necessary. Does aging of the RMS takes place and which time-temperature regimes the RMS can remain active in the system, i. e. maintain a self-propagating high-temperature synthesis. Furthermore, the RMS can be regarded as a functional connection in this case, which entails measurements of the thermal as well as electrical conductivity, mechanical properties of the layer structure as well as the compatibility in the context of a joining connection with low-melting solders (deposited galvanically or by magnetron sputtering) or separately added during the joining process. Subsequently, compatibility with low-melting solders will be investigated (joining part). It is further investigated whether ideally a second RMS can be used for the joining process Finally, investigations will be carried out on the complete system with regard to reliability and feasibility.