Silicon integrated circuit (IC) technologies have evolved significantly to provide high levels of integration, reduced sizes and costs, improved yields and reliability, and sophisticated tools for design, simulation, production, and testing; however, standard Silicon IC technologies have limitations in terms of operating voltages, frequencies, and power levels. Therefore, a number of applications, such as RF switches, RF amplifiers, and other RF circuitry, use other IC technologies, such as Gallium Arsenide, to overcome the limitations of Silicon. Some RF switch designs use multiple RF switches coupled in series to increase voltage ratings and improve linearity during both an ON state and an OFF state; however, each RF switch needs to be isolated from the other RF switches. Traditional silicon processes may have substrate P-N or N-P junctions between a substrate of a wafer and devices, such as RF switches, formed adjacent to the substrate; therefore, RF switch isolation may not be possible.
A Silicon technology that may provide device isolation is silicon-on-insulator (SOI) technology, as illustrated in FIG. 1 according to the prior art. A silicon handle wafer section 10 provides a substrate 12. An insulator layer 14 is formed over the substrate 12, and a silicon device layer 16 is formed over the insulator layer 14. The insulator layer 14 is typically of a non-conducting material, such as Silicon Dioxide, to electrically isolate the silicon device layer 16 from the substrate 12; therefore, multiple isolated devices may be formed on a single Silicon wafer. However, SOI technology has its own limitations. By isolating individual devices, a problem called the floating body effect may occur. Each isolated device may have a bias voltage applied to its body to remove excess carriers from the P-N junction regions; however, if operating voltages are high enough, the depletion regions between the drain and the source may reach the insulator layer 14 and introduce non-linearities and other anomalies. As a result, special design, simulation, fabrication, and testing tools, methods, and processes may be required.
Thus, there is a need for a Silicon technology that can provide the advantages of Silicon, including many different types of components, low costs, small sizes, improved yields and reliability, and which uses standard tools, methods, and processes, and can overcome the shortcomings of Silicon technology by solving the floating body problem and meeting the operating voltage, operating frequency, and linearity requirements of RF applications.