US 4,755,874 A · Emission microscopy system

Abstract

An optical emission microscopy system with a macro optic system having a high numerical aperture for obtaining global views of an integrated circuit Device Under Test (DUT). The DUT is subjected to illumination and stimulation conditions, and images are obtained to form a "global difference" image in which defects, wherever located in the chip, can be discerned by the system operator. The operator can select apparent "defect bright spots" to be further inspected, and zoom in with the higher magnification micro optics system to repeat the image formation steps. "Difference images" are processed to further eliminate noise spots using an improved two-stage filtering operation. The system may be operated under manual or automatic control, and may be interfaced to various data input, storage, and output devices as desired.

Claims27

Dependent claims

Emission microscopy means for detecting light emitted from defects in dielectric layers of integrated circuit devices in response to test vector signals applied to the input and output terminals of the integrated circuit device, comprising:

mounting means for holding the device under test to be inspected;
optical means including macro optic means having a high numerical aperture for obtaining global optical images of said device under test and including micro optic means for alternatively obtaining micro optical images of sub-areas of said device under test;
primary camera means for converting said optical images into analog electronic signals, said camera means including light intensifier means and being capable of integrating the analog electronic signals;
video image signal processing means for processing said analog electronic signals;
and
video image display means for displaying signals processed by said video image processing means.

3 more elements

A method of detecting light emitted from defects in dielectrics located at unknown coordinates in an integrated circuit device comprising the steps of:

obtaining a reference image of said device;
forming a background image of collectable noise;
applying electrical voltages to selected terminals of the integrated circuit device so as to cause light to be emitted at the locations of defects contained therein;
forming an emitted light image of said integrated circuit including the light emitted from defects contained therein;
forming a difference light image of said integrated circuit by subtracting said background image from said emitted image;
processing said difference image to remove noise and to produce a processed macro difference image;
superimposing said processed macro difference image onto said reflected image to form a superimposed image;
identifying defect bright spots on said superimposed image;
compiling a list of coordinates of said bright spots;
replacing said macro lens with a micro lens;
moving the axis of said micro lens over a first set of coordinates from said list;
forming a difference image of the local area in a window around said set of coordinates;
processing said difference image to remove noise and to produce a processed micro difference image;
superimposing said processed difference image over said micro reflected image;
and
comparing said superimposed image to a reference image of said integrated circuit to locate coordinates of said defect, more precisely relative to said integrated circuit.

13 more elements

Dependencies are inferred from the claim text.

Emission microscopy system

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Emission microscopy system

Life of this patent

Abstract

Claims27