US 6,188,785 B1 · Pattern inspecting apparatus and inspecting method

Abstract

An image signal of a large number of patterns of the same shape on an LSI wafer obtained by an image sensor is held in a memory circuit, by using a CMOS image sensor chip incorporating a one-dimensional CMOS photodiode array, an analog-to-digital conversion circuit, a memory circuit and a processing circuit. Then, the image signal and one-cycle and two-cycle displaced image signals cyclically displaced from the image signal by the processing circuit are algebraically processed by a defect detection algorithm in the processing circuit of the CMOS image sensor. By this processing, a defect image is extracted without using a normal inspection pattern. Thus, a high-speed processing, a simplification of a configuration of an apparatus and a miniaturization of the apparatus become possible.

Claims6

Dependent claims

A pattern inspecting apparatus for performing a surface inspection of an LSI wafer which contains a plurality of individual chips thereon, in order to identify fine or minute defects in a surface pattern of said chips, wherein the same surface pattern is repeated on each of said chips, said pattern inspecting apparatus comprising:

a moving stage for supporting a specimen to be inspected thereon, said moving stage being movable for positioning said specimen;
a stage control unit for driving said moving stage and for outputting positional information;
a light source for providing an irradiation beam over a predetermined area for projection onto said specimen to be inspected;
a microscopic optical system for projecting the irradiation beam onto said specimen and for directing a reflected irradiation beam onto a sensor;
a CMOS image sensor chip comprising:
a one-dimensional photodiode array for receiving the reflected beam from said microscopic optical system and for producing an analog image signal, wherein a one dimensional image of the predetermined area on the specimen is detected at once and a two-dimensional image of the predetermined area on the specimen is obtained by moving said moving stage to enable inspection of an entire surface of the specimen;
an analog-to-digital conversion circuit for converting the analog image signal into a digital image signal;
a memory circuit for storing the digital image signal;
an image processing section for cyclically displacing the digital image signal;
a processing circuit for processing the image signal to detect a defect therefrom;
and
display means for displaying a result of the inspection.

9 more elements

A minute pattern inspecting method for performing a surface inspection of an LSI wafer which contains a plurality of individual chips thereon, in order to discover a defect in a surface pattern of said chips, wherein the same surface pattern is repeated on each of said chips, comprising the steps of:

(a) moving a specimen for inspection to a predetermined position defined by position information;
(b) projecting an irradiation beam over a predetermined area of said LSI wafer;
(c) receiving, on light receiving elements laid out in one dimension, a beam reflected from said LSI wafer, wherein a one dimensional image of the predetermined area on the LSI wafer is detected at once and a two-dimensional image of the predetermined area of the LSI wafer is obtained by moving said moving stage to enable inspection of the entire surface of the LSI wafer;
(d) converting the received beam into an analog signal string;
(e) converting the analog signal string into a digital signal string;
(f) storing the digital signal string as an original digital signal string;
(g) cyclically displacing the repeated patterns stored as an original digital signal string by a first cycle and a second cycle, respectively, to obtain first and second displaced signal strings corresponding to the original digital signal string;
(h) storing the first and second displaced signal strings;
(i) inverting the first and second displaced signal strings;
(j) storing the inverted first and second displaced signal strings;
(k) algebraically processing the stored first cycle displaced digital signal string, the stored second cycle displaced digital signal string, the stored inverted first and second displaced signal strings, and the stored original digital string to extract a defect image;
and
(l) generating and displaying defect information of said inspected specimen from the defect image obtained in step (k) and positional information of step (a).

10 more elements

A minute pattern inspecting method for performing an appearance inspection of a defect in a large number of repeated patterns of the same shape within individual chips formed on an LSI wafer, comprising the steps of:

moving a specimen to be inspected to a predetermined position;
projecting an irradiation beam over a predetermined area to minute pattern elements with repeated same patterns formed on the specimen to be inspected;
receiving a reflected beam by light receiving elements laid out in one dimension and converting the received beam into an analog signal string, wherein a one dimensional image of the predetermined area on the specimen is detected at once and a two-dimensional image of the predetermined area of the specimen is obtained by moving said moving stage to enable inspection of the entire surface of the specimen;
converting the analog signal string obtained into a digital signal string and
storing it as an original digital signal string;
cyclically displacing the stored original digital signal string to obtain one-cycle and two-cycle displaced signal strings of repeated cycles of patterns respectively, which correspond to the original digital signal string, and storing the displaced signal strings;
algebraically processing the stored one-cycle displaced digital signal string and two-cycle displaced digital signal string and the stored original digital string to extract a defect image;
generating and displaying defect information of the specimen to be inspected from the defect image obtained and positional information of the minute pattern elements inspected,
wherein said algebraic processing step for extracting a defect image comprises the steps of:
generating a first combined image by combining the original digital signal string and an inverted digital signal string having the original digital signal string displaced by one cycle;
generating a second combined image by combining the one-cycle displaced digital string and an inverted digital signal string having a the original digital signal string displaced by two cycles cycle;
comparing respective absolute values of the first combined image and the second combined image at the same position and selecting a smaller absolute value including zero;
and
extracting, as a defect image, a corresponding minute pattern element of the one-cycle displaced digital signal string at a position having an absolute value other than zero.

11 more elements

A recording medium having recorded a control program for performing a surface inspection of an LSI wafer which contains a plurality of individual chips thereon, in order to discover a minute defect in a surface pattern of said chips, wherein the same surface pattern is repeated on each of said chips, said recording medium being readable by a machine to execute the procedures of:

(a) moving a moving stage having loaded thereon a specimen to be inspected through a stage control unit, and positioning said specimen at a predetermined position defined by position information;
(b) projecting an irradiation beam irradiated from a light source over a predetermined area onto said LSI wafer;
(c) receiving, on light receiving elements laid out in one dimension, a reflected beam from said LSI wafer, wherein a one dimensional image of the predetermined area on the specimen is detected at once and a two-dimensional image of the predetermined area of the specimen is obtained by moving said moving stage to enable inspection of the entire surface of the specimen;
(d) converting the received reflected beam into an analog signal string;
(e) converting the analog signal string into a digital signal string by an analog-to-digital converting circuit;
(f) storing the converted signal in a memory circuit as an original digital signal string;
(g) cyclically displacing, in a processing circuit, the repeated patterns stored as an original digital signal string into a first cycle and a second cycle, respectively, to obtain first and second displaced signal strings which correspond to the original digital signal string;
(h) storing the first and second displaced signal strings in a memory circuit;
(i) inverting the first and second displaced signal strings;
(j) storing the inverted first and second displaced signal strings;
(k) algebraically processing the stored first cycle displaced digital signal string, the stored second cycle displaced digital signal string, the stored inverted first and second displaced signal strings, and the stored original digital signal string by said processing circuit to extract a defect image;
and
(l) generating defect information of said inspected specimen by a system controller from the defect information obtained by said processing circuit in step (k) and positional information of the inspected minute pattern elements from the stage control unit of step (a), and displaying the defect information using display means.

10 more elements

Dependencies are inferred from the claim text.

Pattern inspecting apparatus and inspecting method

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Pattern inspecting apparatus and inspecting method

Life of this patent

Abstract

Claims6