Laser probing of advanced microprocessors - technology trending to Moore's law

Laser probing (LP) has been used extensively to acquire timing waveforms from transistors inside integrated circuits (ICs). To meet various challenges in silicon process and design technology, several enhancements to the basic system were made. These include the addition of a specialized interferometer for phase-detection capability and a liquid-immersion objective-lens to increase both signal strength and imaging resolution. These have allowed the laser probing system to keep pace with Moore's Law over several process generations - currently the system is being used to probe 90 nm process geometry ICs at voltages of 1.2 V. Unfortunately, nonlinear effects in the Si substrate limit the effectiveness of the dual laser noise cancellation scheme. These nonlinear effects cause a small, but significant mismatch in the way that continuous wave (CW) and mode-locked (ML) lasers measure vibration of the IC. To overcome this problem, a new time-differential probing (TDP) scheme is developed.