The Metal-Oxide Semiconductor Field Effect Transistor (MOSFET) is a switching device, commonly used in power supplies and industrial applications. The device is switched to the on-state by applying a bias voltage to the gate, and switched off by removing the gate bias or shorting the gate to the source.

Typical production tests for a power MOSFET are:

• Breakdown and leakage tests
• On-state active region tests
• Transient thermal tests
• Avalanche test (UIS, UIL, ruggedness)
• Dynamic switching tests
• Other tests performed

Device characteristics

Typical MOSFET characteristics curves:

Breakdown & Leakage tests

Breakdown and leakage tests are performed using the ipTEST High Voltage (HV) test generator. The test generator either forces a voltage and measures the leakage current or forces a current and measures the breakdown voltage.

For a power MOSFET, the main drain-source junction leakage current (I_DSS) and breakdown voltage (V_(BR)DSS) are measured together with the gate-source junction leakage current (I_GSS).

On-state tests

On-state and active region tests are performed on the ipTEST Low Voltage (LV) generator. To turn a MOSFET to the on-state, a gate bias is supplied from the LV gate drive and a high current is supplied from the LV Drain generator.

Active tests V_GS(TH) and g_fs measure the transition state between on and off, and bias the device in the active region confirm the transconductance of the device

Transient Thermal tests

Transient thermal tests and forward biased safe operating area (FBSOA) are measured on the ipTEST Rth (FB) test generator. Transient thermal tests are designed to verify the integrity of the mount down bonding process in a packaged device. A poor bond will restrict the heat flow and cause the junction temperature to rise after a power pulse. The on-state voltage of the body-drain diode V_SD has a temperature coefficient of -2mV/K, this is measured before and after a power pulse, and the difference in voltage (dV_SD) is measured to show the success of the mount down.

Avalanche Energy tests

Avalanche or Unclamped Inductive Switching (UIS, UIL) tests are performed on the ipTEST UIS test generator or the Dynamic Switch (DS) test generator. The test is a basic Go/No-go test for ruggedness and any devices with silicon defects will fail in the high current, high voltage avalanche test. ipTEST also offers waveform capture to allow the avalanche energy to be measured directly, and provides an energy-cut off mode if a specific avalanche energy is required.

Additional waveform analysis recall test modes are available to measure maximum and minimum currents, voltages, time between points, and perform custom energy calculations as required.

Dynamic Switching tests

Dynamic switching tests are performed on the ipTEST Dynamic Switching (DS) test generator. For dynamic switch testing, the reduction of parasitic inductance and capacitance is important for ensuring waveform quality, so all the test electronics is mounted in a compact test head on the handler / prober contacts. The switching tests are typically performed with a resistive load.

Additional waveform analysis recall test modes are available to measure maximum and minimum currents, voltages, time between points, and perform custom energy calculations as required.

Additional test capability

• Isolation testing (for FullPack devices and modules)
• Gate resistance test (for Trench MOSFETs)
• Capacitance test
• Multi-chip modules

Please contact ipTEST for more information.