Electromigration Reliability of the Contact Hole in SiC Power Devices Operated at Higher Junction Temperatures

Abstract

Abstract. It is strongly desired to operate SiC power devices at higher junction temperatures (T j ), but that often entails problems because they contain a variety of materials with thermal activity or weakness. An example of such troubles is the steep increase in resistance of the Al electrode in the source (or emitter) contact holes, caused by electromigration (EM). In this work, EM reliability of the contact hole in SiC power devices was evaluated for an improved Al electrode sandwiched between thin TaN layers. An estimated mean time to failure (MTTF) of approximately 3400 years was achieved under conditions of T j = 300°C and J = 10 4 A/cm 2 .

A Review of the Study on the Electromigration and Power Electronics

“…Which is more significant for ULSI development so that a reliable interconnect system can be built as ULSI technology is advancing and the demand for ULSI in term of speed and functionality are ever increasing [14] [29]. Another recent work [15], where EM reliability of the contact hole in SiC power devices was evaluated for an improved Al electrode sandwiched between thin TaN layers. They showed that Al electrode demonstrated long-term reliability even at higher junction temperatures.…”

“…As a result voids will be formed on some parts of the interconnection [14] and hillock due to the accumulation of the metal atoms will be formed on different parts of the interconnection [5]. The presence of voids will increase the resistance [15] [16] of the interconnection or even open, while increased mechanical stress may result in dielectric fractures and leakage between adjacent interconnects in Figure 3 and Figure 4. On the other hand, the presence of hillock will cause short circuit between the adjacent interconnections if the hillock is developed side-way, and short circuit between the different levels of interconnections if it is developed vertically and punch through the inter-metal dielectric.…”

250 °C-Operated sandwich-structured all-SiC power module

“…SiC power devices are expected to be operate at higher temperatures and with higher-speed switching characteristics than conventional Si power devices. [1][2][3] A number of investigations aimed at power inverters have been carried out using SiC power modules. [4][5][6][7][8] Conventional power modules with sandwich structures have been proposed to improve the cooling performance and to lower the parasitic inductance and the resistance.…”