Comparative Study of Al Metallization Degradation in Power Diodes Under Passive and Active Thermal Cycling

Abstract

Degradation of Al metallization on Si-based semiconductor chips under operation is a reliability problem known for many years but the mechanisms of this phenomenon are not fully understood. To quantify contributions of different possible effects, a passive thermal cycling setup has been developed allowing for accelerated tests by varying the device temperature on a short time scale without applying electrical power. The setup is also capable of testing devices in different atmospheres. The results obtained by the thermal tests of diode chips are compared to those from power cycled diodes with focus on degradation of the top metallization layer. The data on structural and electrical characterization of the samples show that the passive thermal cycling induces metallization degradation very similar to that found for the power cycled devices. Thus, it can be concluded that the thermal-induced stresses are the dominating mechanisms for the metallization fatigue and following failure. The role of oxidation and corrosion effects is also studied in the experiments on passive thermal cycling using different environmental conditions. It is suggested that the formation of self-passivating aluminum oxide under ordinary atmospheric conditions can play a positive role in limiting the structural, and electrical degradation of the metallization layers. The obtained results represent a considerable contribution into understanding of major failure mechanisms related to metallization fatigue and reconstruction.

The role of power device technology in the electric vehicle powertrain

“…Likewise, there are several publications that analyze how to improve reliability in relation to this topic where the main causes that can produce a failure mechanism of this type are, among others, thermal fatigue due to high current flow, mechanical stress in the bond wire due to improper bonding, and cracks at the interface between the bond wire and die 78,257,262 Metallization ‐ Figure 16②a: these faults arise due to the electromigration of the material (usually aluminum) in the direction of current flow, due to high electric fields; alloy breakdown, due to electrical overvoltage caused by high currents; metal corrosion and wear caused by welding; and improper deposition, and mounding and cracking of the metal at the contact surfaces 263,264 Semiconductor ‐ Figure 16②b: in addition to stress‐related failures when operating above the maximum ratings of current, voltage, and temperature, the main causes of failure of the semiconductor device can be diffusion problems during its manufacturing process, defects in the semiconductor crystal, or the presence of impurities and contaminants in the material 265,266 .…”

Degradation Processes in the Ai-Ti-Si System Under Thermal Shock

“…Mastery of new semiconductor devices and structures cannot be made without solving the problems of metallization and contact systems (Pedersen et al, 2015). The point is that the role of metallization in modern structures of micro-and nanoelectronics is becoming a key (Chang and Chang, 2010;Okabe et al, 2014;Brincker et al, 2018a;Brincker et al, 2018b;Zhao et al, 2019).…”

Comparative study of wire bond degradation under power and mechanical accelerated tests

“…In line with this approach, there are tendencies to develop novel types of accelerated tests allowing to justify contributions of particular failure modes and to limit the analysis to one or very few degradation parameters. One of them is a passive thermal cycling, where the components of power modules are subjected to varying temperature on a short time scale without applying electric power [13,14], thus, mimicking active power cycling but only in terms of thermalinduced stresses. Another approach suggests to utilize mechanical cycling of wire bonds in order to originate the stresses similar to those caused by the thermal-induced ones [15][16][17].…”