Intrinsic stress measurement by FIB ion milling becomes an industrial-strength method

Intrinsic stresses in semiconductor and MEMS devices significantly affect functional behaviour and reliability. Trusted knowledge on stress amount and sign is a basic need developing new products. Electronics and MEMS devices often demand an extremely high spatial resolution of stress states. Only a few methods, like X-ray / electron diffraction [1, 2] and microRaman spectroscopy [3, 4] have been established as indirect stress measurement tools. Even finite element simulation reaches its limits to predict reliably mechanical stresses, if systems are rather complex and material laws are insufficiently known [5, 6]. Stress measurement by means of FIB based ion milling and subsequent quantification of stress relief pattern is a new approach, published first, 10 years ago [7]. In the meanwhile the method has been utilized and strengthened by several research labs [8-10]. Currently an extensive European program is realized to qualify this method for commercialization and to apply it under industrial conditions [11]. This contribution gives an overview on the measurement method, the current state-of-art on the method qualification, on measurement capabilities and limits. For example, typical research lab applications on thin layer stacks and 3D integration components like TSVs are demonstrated as well.