Microprobing

Microprobing, or simply probing, is a failure analysis technique used to achieve electrical contact with or access to a point in the active circuitry of the die. It employs a special piece of equipment known as a microprobing station, which is also commonly referred to as a 'probe station' (see Fig. 1).

Electrical contact is made by dropping fine-tipped probe needles directly on the point of interest, or on an area to which the point of interest is connected.  The size of the tip of the needle used is chosen based on the electrical contact needed and on how large the probing area is. Each of these needles is held by a micromanipulator (see Fig. 2), which is the accessory controlled by the analyst to land the needle on the die precisely.

During circuit analysis by microprobing, the analyst employs the same thought process as when troubleshooting a full-size circuit. Microprobing is only a tool for the analyst to access critical nodes on the microscopic die circuit while analyzing the behavior of the various parts of the circuit.  The process of electrically pinpointing the failure site is known as failure isolation, which requires the analyst to identify abnormal voltages and/or currents on the die.  

Voltage and current measurements are performed by the electrical measurement instruments attached to the probe needle through the micromanipulator.  Common instruments attached to the probe station are voltmeters, curve tracers, oscilloscopes,and the like.  Circuit excitation from voltage supplies, waveform generators, and the like may also be supplied to the die circuit in the same manner.                        

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See Also:  Failure Analysis;  All FA Techniques;  Curve Tracing; 

Decapsulation;  Microthermography;  LEM;  Die Deprocessing;  SEM/TEM

FA Lab Equipment;  Basic FA Flows;  Package Failures;  Die Failures