Adhesion–delamination phenomena at the surfaces and interfaces in microelectronics and MEMS structures and packaged devices

Abstract

Physico-chemical mechanisms of adhesion and debonding at the various surfaces and interfaces of semiconductor devices, integrated circuits and microelectromechanical systems are systematically examined, starting from chip manufacturing and traversing the process stages to the ultimate finished product. Sources of intrinsic and thermal stresses in these devices are pointed out. Thin film ohmic contacts to the devices call for careful attention. The role of an adhesion layer in multilayer metallization schemes is highlighted. In packaged devices, sites facing potential risks of delamination are indicated. As MEMS devices incorporate moving parts, there are additional issues due to adhesion of suspended structures to surfaces in the vicinity, both during chip fabrication and their subsequent operation. Proper surface treatments for preventing adhesion together with design considerations for overcoming stiction pave the way to reliable functioning of these devices. Adhesion–delamination issues in microelectronics and MEMS continue to pose significant challenges to both design and process engineers. This paper is an attempt to survey the adhesion characteristics of materials, their compatibilities and limitations and look at future research trends. In addition, it addresses some of the techniques for improved or reduced adhesion, as demanded by the situation. The paper encompasses fundamental aspects to contemporary applications.

Correlation of surface roughness and surface energy of silicon-based materials with their priming reactivity

“…Generally, adhesion can be described by one of six theoretical models or combinations thereof: mechanical interlocking, electronic theory, theory of boundary layers and interfaces, adsorption (thermodynamic) theory, diffusion theory, and chemical bonding theory [6]. The strength of the connection correlates with the properties of the surfaces used, for example surface roughness, wetting characteristics, cleanliness, and the adhesion mechanisms involved [7][8][9][10]. With the development of a wet-chemical cleaning procedure for semiconductor substrates in 1970, Kern and Puotinen [11,12] significantly affected semiconductor technology as it became the most effective cleaning method for siliconbased substrates.…”

Effects of temperature and voids on the interfacial fracture of Si/a‐Si3N4 bilayer systems

“…To validate the appropriateness of an interface separation of 2 Å for the interface formation between the Si and a‐Si 3 N 4 layers, the interfacial energy is first calculated. The interfacial energy for a given film/substrate pair is constant, e.g., for metals on ceramic, it is typically a small value of ∼0.5–2 J m −2 . The interfacial energy of the Si/a‐Si 3 N 4 system can be calculated from where , , and are the total energies of the isolated Si layer, a‐Si 3 N 4 layer, and the combined Si/a‐Si 3 N 4 bilayer, respectively, and is the interface area.…”

“…3 Results and discussion To validate the appropriateness of an interface separation of 2 Åfor the interface formation between the Si and a-Si 3 N 4 layers, the interfacial energy is first calculated. The interfacial energy for a given film/substrate pair is constant, e.g., for metals on ceramic, it is typically a small value of $0.5-2 J m À2 [34]. The interfacial energy of the Si/a-Si 3 N 4 system can be calculated from [35]…”

Gamma-irradiation effect on material properties behaviour of semiconductor package

“…The silicon die (thin film) is more sensitive to thermomechanical stresses as compared to the bulk material. The large differences in a coefficient of thermal expansion between the materials create an interfacial stress which provides the driving force for the occurrence of delamination [28]. This stress initiated microcrack near an interface.…”