Method And Apparatus For Integrated Circuit Pattern Inspection With Automatically Set Inspection Areas
A method of setting inspection areas capable of reducing pattern inspection time of integrated circuit patterns by selecting areas where systematic defects are likely to occur. The method includes: extracting multiple pattern types from design data by grouping patterns contained in the design data in accordance with shape; selecting one type of pattern from the multiple pattern types; searching design data to identify patterns having same shape as the selected type of pattern; and registering positions of identified patterns as sampling points.
1 . A method of setting inspection areas in a pattern inspection apparatus, comprising:
extracting a plurality of types of polygons from design data by grouping polygons contained in the design data in accordance with shapes of the polygons;
selecting a first type of polygon from the plurality of types of polygons;
searching the design data to identify polygons having the same shape as that of the selected first type of polygons; and
registering positions of the identified polygons as sampling points.
2 . The method according to claim 1 , wherein said selecting the first type of polygon comprises:
comparing minimum line widths of the plurality of types of polygons with a line width threshold value; and
selecting the first type of polygon as a polygon having minimum line width smaller than the line width threshold value.
3 . The method according to claim 2 , wherein said selecting the first type of polygon further comprises selecting a polygon having a maximal vertex count of polygons having a particular minimum line width.
4 . The method according to claim 2 , wherein said selecting the first type of polygon comprises:
comparing perimeters of the plurality of types of polygons with a perimeter threshold value; and
selecting a first type of polygon having a perimeter greater than the perimeter threshold value from the plurality of types of polygons.
5 . The method according to claim 1 , further comprising:
covering the sampling points with masks, respectively;
calculating a proportion of a total area of the masks to an area of a design diagram that constitutes the design data; and
if the proportion is smaller than a covering threshold value, repeating said selecting a first type of polygon, said identifying polygons, said registering sampling points, and said covering sampling points with masks.
6 . The method according to claim 1 , wherein, if differences between vertexes of the first type of polygon and corresponding vertexes of a second polygon to be compared are smaller than a preset value after transposing the second polygon onto the first type of polygon, the polygon to be compared is determined to have the same shape as that of the one type of polygon.
7 . A pattern inspection apparatus comprising a processor and a scanning electron microscope, wherein the processor comprises machine readable instructions configured to:
input integrated circuit design data comprising a plurality of polygons;
set inspection areas by:
extracting a plurality of types of polygons from design data by grouping polygons contained in the design data in accordance with a shape of each polygon;
selecting a first type of polygon from the plurality of types of polygons;
searching the design data to identify polygons having the same shape as that of the selected first type of polygon; and
registering positions of the identified polygons as sampling points;
obtain scanning electron microscope images of the inspection areas in a pattern to be inspected; and
comparing shapes of the obtained scanning electron microscope images with the design data in the inspection areas.
8 . The apparatus according to claim 7 , wherein the machine readable instructions for said selecting a first type of polygon comprise instructions configured to:
compare minimum line widths of the plural types of polygons with a line width threshold value; and
select the first type of polygon as a polygon having a minimum line width smaller than the line width threshold value from the plurality of types of polygons.
9 . The apparatus according to claim 7 , wherein the machine readable instructions for selecting a first type of polygon comprise instructions configured to:
compare the number of vertexes of each of the plurality of types of polygons with a vertex threshold value; and
select the first type of polygon as a polygon having a number of vertexes greater than the vertex threshold value from the plurality of types of polygons.
10 . The apparatus according to claim 7 , wherein the machine readable instructions for selecting a first type of polygon comprises instructions configured for:
comparing perimeters of the plurality of types of polygons with a perimeter threshold value; and
selecting the first type of polygon as a polygon having a perimeter greater than the perimeter threshold value from the plurality of types of polygons.
11 . The apparatus according to claim 7 , wherein the machine readable instructions for selecting inspection areas further comprise instructions configured to perform:
covering the sampling points with masks, respectively;
calculating a proportion of a total area of the masks to an area of a design diagram that constitutes the design data; and
if the proportion is smaller than a covering threshold value, repeating said selecting a first type of polygon, said identifying polygons, said registering sampling points, and said covering sampling points with masks.
12 . The apparatus according to claim 7 , wherein if differences between vertexes of the first type of polygon and corresponding vertexes of a second polygon to be compared and translocated to superimpose the second polygon's origin on an origin of the first type of polygon are smaller than a preset value, the pattern to be compared is determined to have the same shape as that of the first type of polygon.
13 . The pattern inspection apparatus of claim 7 , wherein the machine readable instructions for said selecting a first type of polygon comprise:
comparing minimum line widths of the plural types of polygons with a line width threshold value; and
selecting the first type of polygon as a polygon having a minimum line width smaller than the line width threshold value from the plurality of types of polygons.
14 . The pattern inspection apparatus according to claim 7 , wherein the machine readable instructions for selecting a first type of polygon comprise instructions configured to:
compare the number of vertexes of each of the plurality of types of polygons with a vertex threshold value;
compare perimeters of the plurality of types of polygons with a perimeter threshold value; and
select the first type of polygon as a polygon having the number of vertexes greater than the vertex threshold value from the plurality of types of polygons and having a perimeter greater than the perimeter threshold value from the plurality of types of polygons.