Any electronic system, since it is born, has to carry a load like the rest of living beings since we are born. The degradation of organisms has its alter ego in electronics with the so-called electromigration, which for many is a great unknown. But what exactly is it producing and how is it possible for a chip to end up degrading over time?
Last week we already saw what electromigration was as a general concept, where the migration of the material was the key to everything. But the what produces it and above all the how we leave it for this article, something more technical and specific that can put a bit of calm to certain users who fear to do, for example, overclock.
Current flows are key for it to occur
Obviously, the entire electromigration process corresponds to current flows and to the current itself. A current flow in a semiconductor produces two forces to which metal ions are exposed as a common conductor.
One of these forces is known as electrostatics, which is logically caused by the electric field produced by the metallic interconnection. In it, the positive and negative ions are “protected” from each other, where both respect the qualities and space of the other.
The second force is generated by the transfer of impulse between the conduction electrons and the metal ions, which acts in the direction of current flow and which is ultimately directly responsible for the well-known electromigration. If a chip were designed in a completely homogeneous way in terms of its internal wiring, there would be no problems with current flows, since the same amount of material and ions would be replenished from one place to another.
But this is far from a real practice, since the chips, processors or GPUs are far from being homogeneous, since there are leaks between the different layers, different densities, tolerances in the engraving or manufacture of the wafers, gradients of mechanical tension in any of the processes and so a long etc.
The perfection of a chip does not exist, it will always tend to electromigration
The inhomogeneities are the main culprits for the electromigration to occur, since they cause divergences in the diffusion flow, degrading certain metals in a process that is called “exhaustion”.
The exhaustion of the metal causes over time that there are interconnections with errors and interruptions in the current flow, mainly due to the growth of a series of filaments in the form of small hairs on the surface of the metal at the microscopic level that can cause small short circuits .
This type of problem is known as line exhaustion and is closely linked to the current density of the metal. A high current density at the same time causes a transverse degradation which is what causes an increase in temperature due to Joule heating, as we saw in the original article.
In short, a higher voltage (higher current), higher temperature and, to a lesser extent, higher humidity, facilitate or accelerate the electromigration process, something from which no chip is saved while running power.