Method for measuring the electrical potential in a semiconductor element

A method of measuring an electrical potential distribution in a semiconductor element, comprising the steps of:

• (a) applying a voltage over said semiconductor element;
• (b) placing a conductor in contact with said semiconductor element in a region of said semiconductor element with a known electrical potential using a scanning proximity microscope while injecting a substantially zero current in said semiconductor element with said conductor;
• (c) monitoring the electrical potential on said conductor;
• (d) monitoring the contact force between said conductor and said semiconductor element;
• (e) increasing contact force between said conductor and said semiconductor element until a first substantial change in said contact force is recorded and until a first substantial change in said electrical potential is recorded, the monitored electrical potential attaining thereby substantially the same value as said known electrical potential and the contact force corresponding to said first substantial change being a calibrated contact force;
• thereafter
• (f) changing the position of said conductor while applying said calibrated contact force on said conductor;
• (g) measuring the electrical potential on said conductor while injecting a substantially zero current in said semiconductor element with said conductor;
• and
• (h) repeating steps (f) and (g).