A large number of semiconductor technologies can be used to integrate microelectronics circuits. Some of these technologies are:
Technologies to in the above list are mainly used for implementing high temperature electronic devices which is not applicable to our demonstration device. Bipolar technology is one of the early technologies, but for technological reasons (related to low integration and complex fabrication processes) CMOS now has superseded Bipolar for both digital and analog design. CMOS provides favoured characteristics for high density integration such as low power, negligible static power dissipation and large noise margins. However, CMOS devices have a low driving current, which is a drawback for high speed applications. As a result, a new technology that combines the benefits of Bipolar and CMOS technologies into one, called BiCMOS, has been developed.
GaAs is a fairly old technology, which has dominated high power microwave and high speed systems applications, and is characterised by high driving current and low parasitics. The main drawback of GaAs technology is its high static power dissipation and low integration density. However, a new technology developed by Motorola, called CGaAs , is expected to have a significant impact on the microelectronics area, because it combines the low power and the high density integration aspects of CMOS with the high driving current of GaAs. Even though CGaAs sounds very promising, it is still in the development stage.
However, most of the above technologies are unsuitable for 3D packaging packaging for the following reasons:
The most suitable technology appears to be CMOS which indeed is the most popular with the 3D packaging foundries. It may be noted that 3D-Plus have had some experience with stacking GaAs devices.