Integrated circuit operating temperatures

Instruments based on the contact principle can further be divided into two classes mechanical thermometers and electrical thermometers. Mechanical thermometers are based on the thermal expansion of a gas, a liquid, or a solid material. They are simple, robust, and do not normally require power to operate. Electrical resistance thermometers utilize the connection between the electrical resistance and the sensor temperature. Thermocouples are based on the phenomenon, where a temperature-dependent voltage is created in a circuit of two different metals. Semiconductor thermometers have a diode or transistor probe, or a more advanced integrated circuit, where the voltage of the semiconductor junctions is temperature dependent. All electrical meters are easy to incorporate with modern data acquisition systems. A summary of contact thermometer properties is shown in Table 12.3. 

The glass transition temperature must be > 400°C. The encapsulant must keep its structural integrity during use. The high temperatures at which microelectronic circuits operate place a restriction on T. / > 10 n-cm... 

In semiconductor technology ultrapure silicon has largely supplanted germanium because it forms denser etchable protective layers (integrated circuits) and can operate at higher temperatures (15()°C)... 

SixNy and SiOx are commonly used as passivation layers [40]. It is known from experience with integrated circuit devices that alkali cations (e.g., sodium) diffuse into SiOx [41], which may be the origin of reliability problems that occur during operation at high temperatures and high voltages. In addition, SixNy shows higher resistance to humidity. Therefore, SixNy is superior to SiOx as a passivation layer. The thickness is typically 300-600 nm. 

All in all, SiC technology is progressing. A summary of contacts to the various polytypes is listed in TABLES 1 to 3. As mentioned above, the problem of reliable high temperature low resistance ohmic contacts is the most important problem to be solved. A second issue is the development of semi-insulating SiC for microwave and/or integrated circuits. SiC is now the prime candidate for commercial applications in high temperature devices and circuits and for devices and circuits operating in a harsh environment. 

Different types of SiC Field Effect Transistors, Metal Oxide Semiconductor Transistors (MOSFETs), Metal Semiconductor Field Effect Transistors (MESFETs), and Junction Field Effect Transistors (JFETs) compete for future applications in high temperature and harsh environment electronics. This Datareview details these various types of FETs, the structures used and the performances obtained. Interesting recent developments and potential applications, such as FET integrated circuits, a hybrid operational amplifier and an inverter circuit are also outlined. 

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