RF Characteristics of Two Generations of RFeSI HR-SOI Substrates Over Temperature

RF losses and nonlinearities of the commercially available Soitec radio frequency enhanced signal integrity (RFeSI) high-resistivity silicon-on-insulator substrates are investigated through investigation of 50-
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coplanar waveguide lines manufactured on them. It is shown that the losses of the RFeSI substrates are very small. They have a temperature minimum value at around 70 °C. The generated second- and third-harmonic powers, due to the nonlinearities of the substrates, also have a similar temperature minimum value. The results indicate that the RFeSI substrates present a good RF performance over a temperature range from 0 °C to 115 °C. The RF performance of the two generations of RFeSI substrates is also compared. The losses of the two RFeSI substrates remain the same over the explored temperature range, whereas the harmonic performance of generation 2 (RFeSI 90) is better than that of generation 1 (RFeSI 80). This stems from the increased effective resistivity.