Coupled Nanoscratch and 4-Point Bending Evaluations of Adhesion in SiCN/Cu/Ta/TaN/SiO 2 /Si Stacked Layers
- PDF / 1,025,400 Bytes
- 5 Pages / 612 x 792 pts (letter) Page_size
- 46 Downloads / 154 Views
1086-U08-14
Coupled Nanoscratch and 4-Point Bending Evaluations of Adhesion in SiCN/Cu/Ta/TaN/SiO2/Si Stacked Layers Kouji Yoneda, Satoshi Shimizu, Nobuo Kojima, Chikai Sato, and Jiping Ye Material Science Group, NISSAN ARC, LTD., 1,Natsushima-cho, Yokosuka, 237-0061, Japan ABSTRACT Nanoscratch test used for small area measurements and four-point bending test applied for quantitative measurements were coupled to evaluate the adhesive strengths of SiCN/Cu/Ta,/TaN/SiO2/Si stacked layers. The similarities and differences of the two methods concerning adhesion, position of the delamination interface, and plastic deformation of the delaminated film were estimated. It was found that the nanoscratch test gave similar adhesion properties when the delamination interface was the same as that formed by the four-point bending test. The four-point bending test displayed clearer results compared to the nanoscratch test because energy for delamination was not used in plastic deformation and the crack could propagate further. These results suggest that coupling the nanoscratch and four-point bending tests is powerful way to estimate and understand adhesion of thin film materials.
INTRODUCTION Cu/low-k films with low mechanical strength tend to have poor interfacial adhesion and are more susceptible to debonding of the low-k layer in the interconnect structure, resulting in lower reliability. In previous studies, many methods for estimating film adhesion has been reported, such as the tape test, stud-pull test, four-point bending test, modified edge-liftoff test (m-ELT), and nanoscratch test[1-3]. The quantitative estimation method most widely used is the four-point bending test, in which normal tensile stress is applied to propagate crack growth. The interface fracture energy is quantitatively estimated by detecting the crack extension resistance[4]. The nanoscratch test is a very effective method for estimation of local small areas. The fracture strength is characterized on the basis of the critical normal load at the first point where the friction coefficient abruptly decreases in the nanoscratch process. Therefore, both methods have their merits and demerits, showing differences in quantitative/qualitative estimations and detecting areas. It is important to investigate the interrelation and to understand the difference between these two methods when applying them to evaluate adhesive or cohesive strengths, for the sake of optimizing process conditions. In this work, we have coupled the nanoscratch and four-point bending tests to evaluate the adhesive strengths of SiCN/Cu/Ta,/TaN/SiO2/Si stacked layers. We evaluate the similarities and differences of the two methods concerning adhesion, position of the delamination interface, and plastic deformation of the delaminated film, and show that the two methods can be used together to evaluate adhesion of thin films.
EXPERIMENT Figure 1a) shows two specimens type A0 and type A1 having the same thickness distributions but different He pretreatment on the Cu layers before the SiCN depo
Data Loading...
