Outstanding reliability performances of Silicon capacitors for 200°C automotive applications

In the race of miniaturization, manufacturers of automotive devices always require smaller electronic components. To save space and in the same time improve performances, some sensors are placed directly `Under the hood' and are directly exposed to harsh environment, such as braking systems, oil, exhaust gaz, cooling liquids and so on. These requirements drive the increasing demand for reliable capacitors that can withstand temperatures up to 200°C. Murata has developed a unique capacitor technology in silicon as well as integrated passive devices based on 3D trenches with high aspect ratio. This paper reports the reliability of automotive grade silicon capacitors for high temperature applications up to 200°C. The development of a range of Silicon capacitors, with an operating temperature from -55°C up to +200°C will be presented here. The manufacturing process optimizations and the design rules (Design for Reliability) implemented to prevent failure mechanisms when exposed to such a high temperature will be described. The solutions to avoid top to bottom metal short (TBMS), electromigration (EM), intermetallic compound formation (IMC) and to enhance time-dependent dielectric breakdown (TDDB) will be depicted. The products have been qualified according to automotive electronic standard AEC-Q100, but exceeding by 65°C the grade 0, which is defined as the most severe conditions of the standard. The results of the reliability qualification both at wafer level and product level will be presented in details. The long-term stability of key electrical parameters of the Silicon capacitors is a main differentiator versus standard capacitor technologies for the `under the hood' automotive market.