Soo-Jung Hwang

Stress Relaxation during Isothermal Annealing at Elevated Temperatures in Electroplated Cu Films

Deformation mechanisms of electroplated Cu thin films on TaN/SiO 2 /Si were investigated by performing isothermal annealing above 200 °C. Stress relaxation behavior during isothermal annealing was analyzed by curve fitting using exponential decay equations. During heating, fast relaxation and subsequent slow relaxation processes were observed. In contrast, during cooling, only slow relaxation process was observed. Among possible mechanisms for stress relaxation, diffusion creep was found to be the most plausible mechanism based on the obtained values of the activation energy. It was suggested that the slow relaxation process observed both in the heating and in the cooling processes was attributed to a grain-boundary diffusion creep. On the other hand, the fast relaxation process observed during heating was attributed to a surface-diffusion controlled mechanism. The surface diffusion mechanism was considered to be characteristic to Cu thin films that did not form stable surface oxide.

Failure Mechanisms of W/TiN/Ti Metal Lines under High Current Stressing

Current-induced morphological changes of W/TiN/Ti metal lines under voltage stressing in the range of 1.2–20 V were studied for 50- and 100-nm-wide lines. The relationship between the median time to failure and current density showed a power law dependence with two different exponent values depending on the applied current density level, irrespective of the line width. Self-heating-assisted electromigration, and melting and agglomeration are suggested as the dominant mechanisms in the low- and high-current-density regions, respectively.

Al 박막의 힐록 형성에 미치는 Mo 하부층의 영향에 관한 실시간 분석

【The in-situ scanning electron microscopy observation of real-time hillock evolution in pure hi thin films on glass substrate during Isothermal annealing was analyzed quantitatively to understand the compressive stress relaxation mechanism by focusing on the effect of Mo interlayer between Al film and glass substrate. There is a good correlation between the hillock-induced stress relaxation by in-situ scanning electron microscopy observation ana the measured stress relaxation by wafer curvature method. It is also clearly shown that the existence of Mo interlayer plays an important role in hillock formation probably due to the large difference in interfacial diffusivity of Al films.】

In-situ Study on Effects of Annealing Temperature and Mo Interlayer on Stress Relaxation Behaviors of Pure Al Films on Glass Substrates

The in-situ SEM observation of real-time hillock evolution in pure Al thin films on glass substrate during isothermal annealing at 194°C was analyzed quantitatively to understand the compressive stress relaxation mechanism by focusing on the effect of Mo interlayer between Al film and glass substrate. There is a good correlation between the hillock-induced stress relaxation and the measured stress relaxation by wafer curvature method. It is also clearly shown that the existence of Mo interlayer plays an important role in hillock formation probably due to the large difference in interfacial diffusivity of Al films.