Capacitor soft breakdown detection

What is soft-breakdown in MOS?

The application of an electrical stress to an ultra-thin (<5 nm) gate oxide in a MOS structure can lead to the appearance of a failure conduction mode known as soft-breakdown.

What should a DCR analyst do if a cap fails?

The analyst should be careful to limit the voltage and current the CAP is exposed to during DCR measurements, as it could alter the CAP. In the absence of any external or internal anomalies detected by optical and X-ray examination, thermal imaging could be helpful in determining the location of failure site.

What is soft breakdown (SBD)?

Introduction Recently, a new failure mode occurring in MOS devices has been reported 1, 2. This conduction state, known as soft breakdown (SBD), has only been detected in ultra-thin oxides (<5 nm) and exhibits a conduction level which is between the direct tunneling and the final breakdown regime.

How can a simple capacitor have high capacitance in a small volume?

A simple capacitor consists of a dielectric between two conductive materials. One way of having high capacitance in a small volume is to increase the dielectric-electrodes surface area in a given volume, which is done using different types of constructions, as listed in Table 1.

How to regain capacitance loss in MLCC?

The capacitance loss can be regained by a de-aging heat-treatment, typically above 150°C. The failure analyst needs to be aware of this before performing any kind of destructive analysis, as it will not show any problem with the MLCC.

What causes a capacitor to leak?

For capacitors, typically high leakage or short condition results from either dielectric compromise or bridging across the positive and negative terminals, what causes this and how it occurs varies for the different CAPS.