Trench gate field-stop
A distinguishing feature of ST in the silicon chip industry is its continued research and investment in all the principal categories of power semiconductor products. These include silicon-based MOSFET and insulated gate bipolar transistors (IGBT), as well as silicon carbide (SiC) and gallium nitride (GaN) products based on wide-bandgap (WBG) materials.
The IGBT combination of two devices in one
The IGBT combines a metal oxide semiconductor field effect transistor (MOSFET) on the input and a bipolar transistor on the output. The resulting structure forms a voltage-driven device with high input impedance, high current density, and low ON-state voltage drop (VCEsat).
The bipolar structure of the IGBT induces tail current during turn-off. It is an undesired phenomenon caused by minority carrier recombination.
Trench gate field-stop (TGFS) architecture
The first IGBT devices with planar technology offered relatively low performance. This limited their scope to low frequency applications such as motor control.
Introduction of the field-stop (FS) layer
The introduction of a field-stop (FS) layer effectively generated a more regular electric field through the chip and allowed it to sustain a higher breakdown voltage. The field-stop layer also reduced the recombination time of charges, resulting in better control of dynamic behavior.
Introduction of trench gate electrodes
The next breakthrough was the introduction of etched trenches for the gate electrodes. These vertical gates reduced the distance between active cells and increased current density, which allowed a lower saturation voltage for virtually the same breakdown voltage level.
State-of-the-art at STMicroelectronics
Not all semiconductor manufacturers are capable engineering the highest manufacturing standards required to achieve optimal IGBT performance and reliability.
ST IGBT devices with trench gate field-stop (TGFS) architecture exhibit structural uniformity measured in fractions of micrometers. They remain free of residues left from the various lithography, deposition, etching, metallization, and related phases.
The resulting devices offer greater balance between conduction and switching loss and far more robustness in terms of short-circuit withstand time and maximum junction temperature.
Advanced IGBT packaging for major markets
The current ST IGBT portfolio represents an ongoing effort to integrate our advanced trench gate field-stop architecture in smaller and more advanced packages and integrated modules.