Silicon integrated RC snubbers for applications up to 900V with reduced mechanical stress and high manufacturability

Passive snubber networks are especially needed in fast switching power modules to prevent overvoltage from hard switching and to minimize electromagnetic interference [1]. In a half-bridge circuit as shown in Fig. 1 (a) dissipative RC snubber networks are beneficial over single pulse capacitors as they do not generate a resonant pole in the impedance spectrum, which can be seen in Fig. 1 (b). As only a small capacitance (e.g. 4 nF) is needed to reduce the overvoltage (Fig. 1 (c)), a monolithically integrated RC snubber can be realized on a silicon chip and packaged directly on the power module substrate. An improved module performance was already demonstrated for chip snubbers with 200 V operating voltage [2]. This work shows how the device design was enhanced for high manufacturability and reliable operations in a voltage range from 600 V to 900 V.