Method and apparatus for processing pattern image data by SEM

• US 5,887,080 A
• Filed: 01/27/1995
• Issued: 03/23/1999
• Est. Priority Date: 01/28/1994
• Status: Expired due to Fees

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Motoki, Hiroshi, Komatsu, Fumio, Tsubusaki, Koji
• Primary Examiner(s): Kelley, Christopher S.
• Application Number:
  US08/379,962
• Time in Patent Office: 1,516 Days
• Field of Search: 382/108, 382/172, 382/181, 382/144, 382/147, 382/149, 382/264, 382/257, 382/270, 382/273, 382/291, 382/282
• US Class Current: 382/172
• CPC Class Codes: G06T 2207/10061 from scanning electron microscope
• CPC Class Codes: G06T 2207/30148 Semiconductor; IC; Wafer
• CPC Class Codes: G06T 7/11 Region-based segmentation
• CPC Class Codes: G06V 20/695 Preprocessing, e.g. image segmentation
• CPC Class Codes: G06V 2201/06 Recognition of objects for industrial automation

Abstract

Analog image data a SEM are converted into digital data, and are processed by a spatial filtering processing, histogram processing, threshold value setting, three-valued image data processing, noise reduction and the like. Area of a pattern in the three-valued image data is calculated by a labelling and calculation processing, and a pattern is sequentially detected by comparing the area of the pattern with a reference area value. The comparison and detection of the same or similar patterns repeated in the SEM image are performed by using the area of the pattern, and are not performed by a shape of the pattern, thereby resulting a precise detection at high speed by using a microprocessor. Since it is possible to perform a pattern recognition from the area value even though the pattern does not have a characteristic, it is possible to precisely detect and recognize a pattern image in high speed.

Claims

1. An apparatus for processing a pattern image, comprising:

analog-digital conversion means for converting into digital data from analog image data including a repetitive pattern such as contact holes which are made through a semiconductor substrate and which are obtained by a scanning electron microscope (SEM);

spatial filtering processing means for performing a spatial filtering processing with respect to said digital image data of the contact holes by a predetermined filter coefficient so as to obtain smoothed spatial filtering image data about each of said contact holes;

histogram processing means for classifying a histogram of pixel data constituting said smoothed spatial filtering image data corresponding to a gray scale level degree;

threshold value set means for detecting and setting a slice of a threshold value as a gray level value;

three-valued processing means for performing a three-valued processing with respect to said image data by using said slice level of the threshold value set by said threshold set means so as to obtain three-valued image data of a pattern surface region, a pattern taper region and a pattern bottom region;

noise reduction means for reducing noises and pseudo patterns in said three-valued image data processed by said three-valued processing means by means of a repetition of a contraction and expansion;

pattern area calculation means for calculating a respective area of a pattern one by one by means of a selection by a labeling processing, said pattern which is shown by a specified density and included in said repetitive pattern included in said three-valued image data in which said noises and said pseudo pattern are reduced by said noise reduction means;

reference image storage means for storing as a reference area value an area of a reference image in one pattern constituting said repetitive pattern as a detected object; and

pattern comparison and detection means for detecting a pattern having a most approximate area value within an entire area of a plurality of contact holes as patterns after comparing said area value of each pattern obtained by said pattern area calculation means with said reference area value of said reference image stored in said reference image storage means.

2. An apparatus for processing a pattern image including at least one contact hole made through a semiconductor substrate, comprising:

an analog-digital converter converting into digital data from analog image data including a repetitive pattern of the at least one contact hole made through the semiconductor substrate and which is obtained by a scanning electron microscope (SEM);

a spatial filter performing a spatial filtering processing with respect to said digital image data of the at least one contact hole by a predetermined filter coefficient so as to obtain smoothed spatial filtering image data of each of said contact holes;

a histogram processor classifying a histogram of pixel data constituting said smoothed spatial filtering image data corresponding to a gray scale level degree;

a threshold value set circuit detecting and setting a slice of a threshold value as a gray level value;

a three-valued processor performing a three-valued processing with respect to said image data by using said slice level of the threshold value set by said threshold set circuit so as to obtain three-valued image data of a pattern surface region, a pattern taper region and a pattern bottom region;

a noise reducer reducing noises and pseudo patterns in said three-valued image data processed by said three-valued processor by means of a repetition of a contraction and expansion;

a pattern area calculation circuit calculating a respective area of a pattern one by one by means of a selection by a labeling processing, said pattern which is shown by a specified density and included in said repetitive pattern included in said three-valued image data in which said noises and said pseudo pattern are reduced by said noise reducer;

a reference image storage circuit storing as a reference area value an area of a reference image in one pattern constituting said repetitive pattern as a detected object; and

a pattern comparison and detection circuit detecting a pattern having a most approximate area value within an entire area of a plurality of contact holes as patterns after comparing said area value of each pattern obtained by said pattern area calculation circuit with said reference area value of said reference image stored in said reference image storage circuit.