Leakage Locating Methods

Published on：2019-02-25 Author：ceshi

Summary of chip leakage location methods
Chip leakage is the most common failure analysis case. Finding the leakage potential is the premise to find out the cause of failure. LCD leakage location, EMMI (CCD InGaAs), laser induction and other means are often used by engineers. Over the years, there has been a misunderstanding in China's semiconductor industry that laser induction means is OBIRCH. Today's edition is about laser scanning Microscope.
At present, there are three methods widely used in laser induction function in the industry. These three methods have been applied for special Most people in China think that only OBIRCH is laser induced. In fact, TIVA and VBA are the same technology as OBIRCH. In the case of laser scanning chip surface, the impedance of which position has obvious change can be detected, which position may be leakage potential. Detecting impedance changes is reflected by voltage and current. Here are three technical principles:

                  1、OBIRCH和TIVA

As shown above, the leakage circuit of a device, R1 represents the impedance of the leakage point, I1 represents the current of the circuit, and V represents the voltage of the circuit.
OBIRCH; voltage V devices with a loop, and then let the laser scanning on the surface of the chip, and monitor the change of loop current of I1.
TIVA: Add a tiny current I1 to the circuit of the device, then let the laser scan the chip surface, and monitor the change of the circuit voltage V.
2. VBA Technology

As shown above, the leakage circuit of a device, R1 represents the impedance of the leakage point, I1 represents the circuit current, V1 represents the voltage on the circuit, R2 is a load connected in series in the circuit, and V2 represents the voltage at both ends of R2.
OBIRCH; add a voltage V1 to the circuit of the device, and then let the laser scan on the chip surface, while monitoring the change of V2 (V2/R2=I1, in fact, monitoring the change of I1), so you can see that VBA is actually OBIRCH, but reasonably avoided the NEC specialty #benefit.