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Electronic Circuit Monitoring Using Optical Beam-Induced Current

IP.com Disclosure Number: IPCOM000102558D
Original Publication Date: 1990-Dec-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 2 page(s) / 54K

Publishing Venue

IBM

Related People

Coutu, PT: AUTHOR

Abstract

By generating a test current or voltage in a diffusion on a semiconductor chip by means of a scanning light beam, several test structures on a semiconductor circuit chip may be tested while having only one or two external connections to circuitry on the chip. When test structures deviate from normal, i.e., do not perform correctly as designed, a rastered scan and normal optical beam-induced current (OBIC) gray scale observation usually calls attention to the failure.

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Electronic Circuit Monitoring Using Optical Beam-Induced Current

       By generating a test current or voltage in a diffusion on
a semiconductor chip by means of a scanning light beam, several test
structures on a semiconductor circuit chip may be tested while having
only one or two external connections to circuitry on the chip.  When
test structures deviate from normal, i.e., do not perform correctly
as designed, a rastered scan and normal optical beam-induced current
(OBIC) gray scale observation usually calls attention to the failure.

      Referring to Fig. 1, diffusion 10 in a semiconductor substrate
is used to generate a test current or voltage which is detected as a
voltage difference at the ends of diffusion 10 by differential
amplifier 12.  Test points T1 through T9 are wired to diffusion 10
along its length.

      Referring to Fig. 2, output OUT from amplifier 12 is plotted
vertically and position of a light beam is plotted horizontally as it
is moved along the length of diffusion 10.  The plot shown is typical
when diffusion 10 is uniform dimensionally, doping level is uniform
along its length, and test points T1 through T9 are not
interconnected.  An OBIC rastered scan of diffusion 10 under these
conditions, wherein an oscilloscope electron beam intensity is
proportional to voltage OUT and x and y position of the electron beam
is driven in proportion to movement of the optical beam in the plane
of the integrated circuit, causes the diffusion...