Month: November 2024

Wafer probe stations can be used to test and characterise devices for a wide range of applications. One such application of interest is high-power probing of devices on wafers and as packaged die.

Rapid developments in a range of industries, such as automotive or large-scale photovoltaics, result in increasingly high demand for energy-efficient power semiconductor devices. The commercialisation of devices based on wide-bandgap semiconductors, typically silicon carbide (SiC) or gallium nitride (GaN), has offered significant performance gains over silicon (Si) based technologies. They can operate at higher temperatures, frequencies and voltages, while reducing energy losses.

The performance standards of high-power technologies need dedicated electrical testing equipment which can address a spectrum of specific challenges related to handling and distributing high voltages, device protection and the safety of the user. To meet these challenges, SemiProbe offers a range of probers, based on its modular Probe System for Life™ (PS4L) platform.

The typical voltage and current levels at which the high-power probers operate are:

• Voltage in the range 3 to 10 kV; and
• Current up to 500 A (pulsed).

In order to operate with high-power loads, special manipulators and cabling must be used. These have to be interfaced to dedicated test instruments.

To ensure user safety when handing the high-power equipment, the risk of the user being exposed to the high  voltage must be minimised. SemiProbe high-power systems are equipped with:

• Physical barriers;
• Laser light curtains;
• Safety interlocks; and
• Shielding and grounding solutions.

The occurrence of high voltages (above 1 kV) during a measurement may lead to electrical discharges between the probe needles, between devices, between the device and other test pads, or between the device and the surrounding probe station. This is due to arcing, a breakdown of gas that produces plasma and results in a current flow through normally nonconductive media, such as air. Arcing can affect the quality of the measurement or even damage the probing instruments. This can be avoided by changing the measurement environment through:

• Immersing the device under test in fluorinert;
• Testing in vacuum; or
• Introducing gas streams (argon, nitrogen).

In addition to general challenges related to operating at high voltages, the requirements for equipment and accessories will also vary depending on the device type (MEMS, optical emitters, sensors, etc.) and operation conditions (e.g. elevated temperatures or light-tight environment). SemiProbe PS4L systems are configured to operate at voltages in the range of kVs and are customised to perform application-specific testing. The probers are available in manual, semi-automatic and fully automatic configurations and can be flexibly equipped with required instrumentations, such as thermal chucks, environmental chambers, and light-tight dark boxes. To explore examples of wafer probing systems designed for application-specific high-power probing, visit SemiProbe Application Case Studies.