Direct measurements of circuit node signals without changing the performance of the circuitry are essential in modern FA but often impossible for recent IC technologies. This paper shows new methods, based on FIB backside circuit edit, allowing access to every existing circuit node at the device level, and discusses options for probing and discrete characterization.

One method of dynamic probing in modern integrated circuits (ICs) is performed through the backside of the device. The established techniques are limited in lateral resolution because they use infrared (IR) light. This paper demonstrates how state of the art FIB circuit edit (CE) processes enable the application of E-Beam probing through chip backside on current and future IC technologies with low risk of device performance degradation.

We evaluated laser ablation and sandblasting as preparation methods for package related failures and for backside analysis of ICs. With laser ablation we uncovered gold wedges on an internal board of a PLFBGA package without damage of the gold wires and the board metallization. This was possible by optimization of the laser pulse energy and the pulse repetition rate and by limitation of the ablation area. Sandblasting showed to be a gentle way for backside thinning down to 60 μm silicon thickness. For a surface smoothness sufficient for IR imaging a subsequent planarization treatment is necessary.