Hot-wall furnace for semiconductor processing

Hot-wall furnace reactors are used in semiconductor fabrication to grow layers of semiconductor materials on wafers. An important aspect is to grow the layers with a crystal structure that matches that of the wafer substrate. This is called epitaxial growth and is a key technology for the fabrication of electronic devices. For silicon carbide (a wide-bandgap semiconductor), epitaxial growth is one of the great challenges towards manufacturing reliable devices.

The layer growth takes place with the wafers sitting in graphite susceptors (wafer holders) at very high temperatures. The susceptors are heated with radio-frequency (RF) coils at power levels in the 10 kW range. The design of the reactor chamber is crucial for maintaining a uniform temperature, efficient heating, and control of high-temperature regions. It is especially important that the quartz tube surrounding the susceptor remains at moderate temperatures.

This model examines a simple furnace design that heats a graphite susceptor using an 8-kW RF signal at 20 kHz. It determines the temperature distribution over the wafer along with the temperature on the outer quartz tube. At these temperatures, the heat flux is dominated by radiation, which is also simulated in this multiphysics model.

Inductance of a power inductor

Power inductors are a central part of many low-frequency power applications such as switched power supplies and DC-DC converters. The relatively low voltage and high power consumption they operate under put high demands on the design of such inductors.

A power inductor usually has a magnetic core to increase its inductance value, reducing the demands for a high frequency while keeping the component size small. The magnetic core also reduces electromagnetic interference with other devices. Computer simulations or measurements are necessary in the design of such as often only crude analytical or empirical formulas are available for calculating their impedances.

The model shows an inductance calculation on a large 3D geometry using higher-order vector elements and memory-efficient iterative solver settings.

Inductor in an amplifier circuit

Modern electronic systems are very complex and depend heavily on computer aided design in the development and manufacturing process. Common tools for such calculations are based on the SPICE format, which consists of a standardized set of models for describing electrical devices—especially semiconductor devices such as transistors, diodes, and resistors. SPICE also includes a simple, easy-to-read text format for circuit netlists and model parameter specifications.

When an engineer is designing a new electronic component, like a capacitor or an inductor, the SPICE parameters for that device are not known. They are either extracted from finite element tools, such as COMSOL Multiphysics, or from measurements on a prototype. To speed up the design process, it can be convenient to include the finite element model in the SPICE circuit simulation, modeling the device behavior in an actual circuit.

This model takes a simple amplifier circuit and exchanges one of its components with a finite element model of an inductor with a magnetic core. COMSOL Multiphysics calculates the transient behavior of the entire system.

Simulation of a generator

This example shows how the circular motion of a rotor with permanent magnets can be simulated while taking the rotation into account. The generated voltage is calculated as a function of time during the rotation. The model also shows the influence of material parameters, rotation velocity, and the number of turns in the winding on the calculated voltage.

In particular, the Rotating Machinery Multiphysics Coupling is introduced in this example. This allows sliding mesh to be simulated and gives a true calculation of the electromagnetic field as a function of time.