Bench Talk

(Source: Infineon Technologies)

The saying goes: “The battle is won in the trenches.” It means that people on the front line of the action determine the final winning outcome by their collective hard work and effort. In the following, we’ll review how design engineers involved in power-management applications operate “in the trenches” and what it takes for them to win.

Wide bandgap (WBG) semiconductors are one key to the next step toward an energy-efficient world. WBG semiconductors allow for greater power efficiency, smaller size, less mass, and lower overall cost.

Infineon Technologies is offering the broadest product and technology portfolio of silicon (such as SJ MOSFETs, IGBTs), silicon carbide (such as Schottky diodes and MOSFETs) and gallium-nitride-based (e-mode HEMT, Integrated Power Stage) devices. As the leading power supplier with more than two decades of heritage in silicon carbide (SiC) technology development, Infineon Technologies caters to the need for smarter, more efficient energy generation, transmission, and consumption. Their experts understand what is needed to reduce system complexity, leading to decreased system cost and size in mid- to high-power systems.

Infineon’s goal is to combine the low R_DS(ON) offered by silicon carbide metal-oxide-semiconductor field-effect transistor (MOSFETs) with a gate drive mode device that operates in the safe oxide field-strength conditions. Infineon determined to focus on trench-based devices moving away from planar double-diffused metal-oxide-semiconductor (DMOS) devices with high defect density toward more favorable surface orientations. Trench-based devices enable low channel resistance at low oxide fields. These boundary conditions are the baseline for transferring quality-assurance methodologies established in the silicon power semiconductor world to guarantee failures in time (FIT) rates expected in industrial and even automotive applications. It was out of this work that CoolSiC^™ products were born.

SiC devices operate at much higher drain-induced electric fields in the blocking mode than their Si counterparts (MV instead of kV). Thus, high electric fields in the oxide in the on-state and off-state can accelerate the wear-out. For off-state stress, protection by deep p-regions is adopted. For on-state, a thick oxide is used to circumvent the limits to screen remaining extrinsic oxide defects for thin oxides. CoolSiC^™ products offer unmatched reliability, quality, variety, and system benefits.

CoolSiC^™ MOSFETs trench concepts and benefits include:

• Low channel resistance
• A safe electric operating field in the gate oxide
• Suppresses parasitic turn on
• Enables hard commutation and increases surge current robustness
• JFET region limits short circuit current
• R_ON eases parallel operation
• R_g controls and allows independent switching speed

Infineon’s lineup of 650V, 1200V, and 1700V CoolSiC^™ MOSFET devices are ideally suited for hard- and resonant-switching topologies (Figure 1). CoolSiC^™ MOSFETs are built on a state-of-the-art trench semiconductor process optimized to allow for both the lowest losses in the application and highest reliability in operation. The discrete portfolio in TO- and SMD-housings offers on-resistance ratings from 27mΩ up to 1000mΩ. CoolSiC^™ trench technology enables a flexible parameter-set, which is used to implement application-specific features in respective product portfolios, such as gate-source voltages, avalanche specification, short-circuit capability, or internal body diode rated for hard commutation.

Figure 1: 650V CoolSiC™ MOSFET in TO-247 package and 1200V CoolSiC™ MOSFET in D²PAK-7L (Source: Infineon Technologies)

CoolSiC^™ MOSFETs in discrete packages are ideal for both hard- and resonant-switching such as power factor correction (PFC) circuits, bi-directional topologies, and DC-DC converters or DC-AC inverters. An excellent immunity against unwanted parasitic turn-on effects creates a benchmark in low dynamic loss, even at zero volt turn-off voltage in bridge topologies. The transistor outline (TO-) and surface mount devices (SMD) also come with Kelvin-source pins for optimized switching performance.

Infineon CoolSiC^™ Schottky Diodes provide a relatively high on-state resistance and leakage current (Figure 2). In SiC material, Schottky diodes can reach a much higher breakdown voltage. The Infineon portfolio of SiC Schottky products covers 600V and 650V to 1200V Schottky diodes. Combining a fast silicon-based switch with a CoolSiC™ Schottky diode is often termed a hybrid solution.

Figure 2: Automotive qualified CoolSiC^™ Schottky diode. (Source: Infineon Technologies)

Power modules with CoolSiC^™ MOSFET open up new opportunities for inverter designers to realize never-before-seen efficiency and power density levels (Figure 3). Also, Silicon Carbide (SiC) tailors to application needs by different available topologies from 45mΩ to 2mΩ R_DS(ON) per switch. Available in various configurations such as 3-level including ANPC, dual, four-pack, six-pack, or a booster, the SiC MOSFET modules offer superior gate oxide reliability enabled by state-of-the-art trench design, best-in-class switching, and conduction losses.

Figure 3: CoolSiC™ MOSFET Easy1B and Easy2B  (Source: Infineon Technologies)

SiC MOSFETs have two distinct structure types: trench MOS and planar DMOS. Infineon is pushing superior trench technology for easy usage in all applications and low-power losses while maintaining reliability. Infineon’s CoolSiC^™ excels in performance and is a benchmark for performance and quality balance. Infineon’s gate-oxide screening process ensures product reliability.

Infineon’s Silicon Carbide CoolSiC^™ MOSFETs and diodes provide a portfolio that addresses the need for smarter, more efficient energy generation, transmission, and consumption. The CoolSiC^™ portfolio addresses customers’ needs for reduced system size and costs in mid- to high-power systems while meeting the highest quality standards, long system lifetime, and guaranteed reliability. With CoolSiC™, customers will reach the most stringent efficiency targets while seeing a drop in operational system cost. Win by being in the trenches—utilize Infineon Technologies CoolSiC^™ solutions.