Laser Decapsulation – Making Light Work of Failure Analysis
The decapsulation stage is one of the most crucial parts of any failure investigation. Decapsulation, in which the die is taken out of its protective plastic shell so that failure analysts can reach the intricate circuitry inside, marks the transition between non-destructive analysis and riskier operations. Wet-etch techniques are typically used for decapsulation, which involves dissolving the plastic encapsulant material of an IC package using a range of various acids or solvents. The drawback of this strategy is that it calls for substantial safety precautions like fume hoods and other kinds of personal protective equipment when working with these potentially dangerous substances. Furthermore, even though they are quite common, the chemicals that are most frequently used for decapsulation are still expensive and can add up to a sizable expenditure depending on the quantity and kind of parts that need to be decapsulated. The most crucial benefit of chemical decapsulation is that it frequently prevents component failure; in extreme circumstances, such as when working with GaAs or other III-V semiconductors, the decapsulation chemicals may even entirely dissolve the integrated circuit! Fortunately, there is an experimental substitute for chemical decapsulation; one of the most exciting emerging technologies is laser decapsulation.
A powerful laser is used in laser decapsulation to remove the plastic encasing material from a gadget. The possibility of unintentionally removing or washing away a flaw with decapsulation chemicals is removed by vaporising the encapsulant material as opposed to dissolving it. Additionally, because the laser decapsulation system is controlled by precise stepper motors, it is feasible to decapsulate objects that would be extremely difficult to expose chemically; small or unusually shaped objects can be attacked with a laser with the same ease as a more common object. Reducing the requirement for chemical consumables is another advantage of laser decapsulation.
Although there is less of a need for chemical consumables, laser decapsulation still requires a wet-etch step because allowing the laser to drill through to the die would invariably harm the delicate circuitry there. Laser decapsulation is still in its infancy and has several significant flaws. Also, if configured incorrectly, the laser can break bond wires and produce a pyrolyzed mould compound that is virtually impossible to remove, chemically or otherwise.
Read more: IC Decapsulation: Exposing Semiconductor Devices for Analysis
To prepare a sample for chemical decapsulation, laser decapsulation is currently only useful as a “pre-decap” step. This is still an improvement because it reduces the number of consumables utilised and the amount of chemicals the device is exposed to. Yet, it is nearly a given that this technology will advance further, possibly to the point where wet etch decapsulation can be consigned to failure analysis history.
