Pattern measuring apparatus, and pattern measuring method and program
AssigneeHitachi High-Technologies Corporation
InventorsTakuma Shibahara, Tsuyoshi Minakawa, Michio Oikawa, Yutaka Hojo, Hitoshi Sugahara, Hiroyuki Shindo
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Abstract
The present invention provides a pattern measuring apparatus (600) that: acquires the image contour of a circuit pattern formed by transferring design data; classifies the acquired image contour into shape structures; calculates normal vectors for each shape structure; maps the shape structures to the image contour; uses at least one normal direction for each shape structure to stabilize the normal directions to the image contour; and uses the normal vectors for each shape structure to determine the position of a SEM contour.
Claims9
A pattern measuring apparatus for determining coordinates of a scanning electron microscope (SEM) contour of a circuit pattern formed by transferring design data via a photomask, comprising:
- a storage for storing data on coordinates and luminance values of pixels of an image of the circuit pattern;
- an image contour acquiring unit configured to acquire a position of an image contour of the circuit pattern by scanning across a boundary between a region without the circuit pattern and a region with the circuit pattern to obtain the luminance values of the pixels of the image and to determine a position of a pixel with a maximum luminance value as the position of the image contour;
- a shape structure classifying unit configured to classify a contour shape of the design data into one or more shape structures characterizing the contour shape of the design data;
- a normal direction calculating unit configured to calculate, for each shape structure, normal directions to an approximation line obtained by approximating the shape structure with a smooth line;
- an arranging unit configured to arrange sections on the image contour in such a positional relation with each other as to form a same shape as the contour shape of the design data so that a circumferential ratio of each of the sections to the image contour is equal to a circumferential ratio of a corresponding one of the shape structures to the design data;
- and
- a SEM-contour position acquiring unit configured to acquire the coordinates of the SEM contour by scanning across the image contour in the normal directions calculated for the shape structures corresponding to the sections arranged on the image contour to acquire luminance values of pixels in the normal directions, and to multiply maximum luminance values of the acquired luminance values by a given factor to determine coordinates of pixels with luminance values thus obtained as the coordinates of the SEM contour.
A pattern measuring method applied to a pattern measuring apparatus for determining coordinates of a SEM contour of a circuit pattern formed by transferring design data via a photomask, the pattern measuring apparatus comprising a storage for storing data on coordinates and luminance values of pixels of an image of the circuit pattern,
- the pattern measuring method comprising:
- an image contour acquiring step of acquiring a position of an image contour of the circuit pattern by scanning across a boundary between a region without the circuit pattern and a region with the circuit pattern to obtain the luminance values of the pixels of the image and determining a position of a pixel with a maximum luminance value as the position of the image contour;
- a shape structure classifying step of classifying a contour shape of the design data into one or more shape structures characterizing the contour shape of the design data;
- a normal direction calculating step of calculating, for each shape structure, normal directions to an approximation line obtained by approximating the shape structure with a smooth line;
- an arranging step of arranging sections on the image contour in such a positional relation with each other as to form a same shape as the contour shape of the design data so that a circumferential ratio of each of the sections to the image contour is equal to a circumferential ratio of a corresponding one of the shape structures to the design data;
- and
- a SEM-contour position acquiring step of acquiring the coordinates of the SEM contour by scanning across the image contour in the normal directions calculated for the shape structures corresponding to the sections arranged on the image contour to acquire luminance values of pixels in the normal directions, and multiplying maximum luminance values of the acquired luminance values by a given factor to determine coordinates of pixels with luminance values thus obtained as the coordinates of the SEM contour.
A pattern measuring apparatus for determining coordinates of a SEM contour of a circuit pattern formed by transferring design data via a photomask, comprising:
- a storage for storing data on coordinates and luminance values of pixels of an image of the circuit pattern;
- an image contour acquiring unit configured to acquire a position of an image contour of the circuit pattern by scanning across a boundary between a region without the circuit pattern and a region with the circuit pattern to obtain the luminance values of the pixels of the image and to determine a position of a pixel with a maximum luminance value as the position of the image contour;
- a simulation unit configured to perform exposure simulation to calculate a simulation image contour of the circuit pattern, overlay the simulation image contour onto the image contour, and to store into the storage a position of the simulation image contour overlaid on the image contour;
- a shape structure classifying unit configured to classify a contour shape of the design data into one or more shape structures characterizing the contour of the design data;
- a normal direction calculating unit configured to calculate, for each shape structure, normal directions to an approximation line obtained by approximating the shape structure with a smooth line;
- an arranging unit configured to arrange sections on the simulation image contour in such a positional relation with each other as to form a same shape as the contour shape of the design data so that a circumferential ratio of each of the sections to the simulation image contour is equal to a circumferential ratio of a corresponding one of the shape structures to the design data;
- and
- a SEM-contour position acquiring unit configured to acquire the coordinates of the SEM contour by scanning across the image contour in the normal directions calculated for the shape structures corresponding to the sections arranged on the simulation image contour to acquire luminance values of pixels in the normal directions, and to multiply maximum luminance values of the acquired luminance values by a given factor to determine coordinates of pixels with luminance values thus obtained as the coordinates of the SEM contour.
Dependencies are inferred from the claim text.