Methods and apparatuses for testing electrical connections of a substrate

An apparatus for testing electrical connections of a substrate, comprising:

• (a) vacuum chamber that houses a stage for placement of a substrate;
• a first electron source configured to generate a first electron beam having a first electron energy;
• a second electron source configured to generate a second electron beam having a second electron energy different from the first electron energy;
• and a controller configured to control the apparatus such that:
• in a discharging phase (a), the first electron beam is focused and deflected on a first surface contact to discharge the first surface contact;
• in a charging phase (b), the second electron beam is focused and deflected on the first surface contact to charge the first surface contact;
• and
• a first electrical connection connected to the first surface contact is inspected by detecting signal electrons emitted by the substrate with an electron detector during or after the charging phase (b).

An apparatus for testing electrical connections of a substrate, comprising:

• a vacuum chamber that houses a stage for placement of a substrate;
• a. first electron source configured to generate a first electron beam having a first electron energy;
• a second electron source configured to generate a second electron beam having
• a second electron energy different from the first electron energy;
• a focusing lens arrangement configured to focus the first electron beam on the substrate in a discharging phase and to focus the second electron beam on the substrate in a charging phase;
• a beam deflector arrangement configured to deflect the first electron beam on a first surface contact of the substrate to discharge the first surface contact in the discharging phase and to deflect the second electron beam on the first surface contact to charge the first surface contact in the charging phase;
• an electron detector for detecting signal electrons emitted from the substrate;
• and an analysis unit for inspecting a first electrical connection extending from the first surface contact based on the signal electrons.