High-temperature trench capacitors, using thin-film ALD dielectrics
High-temperature passive electronic becomes more and more important, e.g. in the field of deep drilling, aerospace or in automobile industry. For these applications, capacitors are needed, which are able to withstand temperatures up to 300 °C, which exhibit a low leakage current at elevated temperatures, a breakdown voltage above the intended operating voltage and a high capacitive density value. In this paper, investigations of 3D-integration and atomic layer deposition (ALD) techniques to achieve these features are presented. A highly n-doped Si-substrate acts as a bottom electrode. Medium- and high-k dielectrics represent the insulator and the upper electrode consists of Ru, TiN or TiAlCN. The materials can be used at elevated temperatures. At room temperature, the leakage current is less than 10 pA/mm2 without showing a soft-breakdown up to ± 15 V, indicating the absence of Fowler-Nordheim tunneling. At 300 °C and at 3 V the leakage current amounts about 1 nA/mm2 and at 5 V a soft-breakdown is detected.