Location

Williamsburg, VA

Start Date

1-1-1988 12:00 AM

Description

We report using a 1.3µm(silicon-sub-bandgap) optical probing system to detect electrical signals in silicon integrated circuits. Free carriers within integrated active devices perturb the index of refraction of the material, and we have used a Nomarski interferometer to sense this perturbation. Typical charge-density modulation in active devices produces a substantial index perturbation, and because of this, we have used an InGaAsP semiconductor laser to experimentally observe real-time 0.8V digital signals applied to a bipolar transistor. These signals were detected with a signal-to-noise ratio of 20dB in a system detection bandwidth of over 200MHz.

Since the free-carrier-induced refractive-index perturbation is present in all semiconductor materials, in the future, we expect to be able to detect signals in integrated circuits fabricated in GaAs or any other material, and by taking advantage of the high spatial and temporal resolution of this system, we should be able to observe free-carrier dynamics within most active devices.

Book Title

Review of Progress in Quantitative Nondestructive Evaluation

Volume

7B

Chapter

Chapter 6: Electronic Materials and Devices

Pages

1161-1166

DOI

10.1007/978-1-4613-0979-6_34

Language

en

File Format

application/pdf

Share

COinS
 
Jan 1st, 12:00 AM

A Noninvasive Optical Probe for Detecting Electrical Signals in Silicon IC’s

Williamsburg, VA

We report using a 1.3µm(silicon-sub-bandgap) optical probing system to detect electrical signals in silicon integrated circuits. Free carriers within integrated active devices perturb the index of refraction of the material, and we have used a Nomarski interferometer to sense this perturbation. Typical charge-density modulation in active devices produces a substantial index perturbation, and because of this, we have used an InGaAsP semiconductor laser to experimentally observe real-time 0.8V digital signals applied to a bipolar transistor. These signals were detected with a signal-to-noise ratio of 20dB in a system detection bandwidth of over 200MHz.

Since the free-carrier-induced refractive-index perturbation is present in all semiconductor materials, in the future, we expect to be able to detect signals in integrated circuits fabricated in GaAs or any other material, and by taking advantage of the high spatial and temporal resolution of this system, we should be able to observe free-carrier dynamics within most active devices.