Laser Assisted Device Alteration (LADA) is a laser-based timing analysis technique used in the failure analysis of semiconductor devices. The laser is used to temporarily alter the operating characteristics of transistors on the device.[1]
Theory of operation
The LADA technique targets a continuous wave (CW) laser at specific device transistors. The device being tested is electrically stimulated and the device output is monitored. This technique is applied to the back side of the semiconductor device, thereby allowing direct access of the laser to the device active diffusion regions. The effect of the laser on the active transistor region is to generate a localized photocurrent. This photocurrent is a temporary effect and only occurs during the time that the laser is stimulating the target region. The creation of this photocurrent alters the transistor operating parameters, which may be observed as a change in function of the device. The effect of this change in parameters may be to speed up or slow down the operation of the device. This makes LADA a suitable technique for determining critical timing paths within a semiconductor circuit. [2]
Notes
References
- Kong, C. H & E. P Castro (2006), "Application of LADA for Post-Silicon Test Content and Diagnostic Tool Validation", Proceedings of the 32nd International Symposium for Testing and Failure Analysis (ASM International): 431-7, ISBN 0-871170-844-2.
- Rowlette, J & T Eiles (2003), "Critical Timing Analysis in Microprocessors Using Near-IR Laser Assisted Device Alteration (LADA)", International Test Conference 2003 Proceedings (International Test Conference): 264-73, ISBN 0-7803-8106-8.
