Method of correcting line width variation due to loading effect caused during etching of a photomask and recording medium formed according to the method
AssigneeSamsung Electronics Co., Ltd.
InventorWon-tai Ki
Life of this patent
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Abstract
A method of exposing a photomask substrate, provides an exposing method for correcting a loading effect generated when a photomask substrate is dry etched. Accordingly, a variation in line width caused by a loading effect generated due to the non-uniformity of a loading density is reduced by a method of performing correction exposure using a dose corresponding to the loading effect due to a desired pattern which is calculated from a relationship represented as the convolution of a Gaussian distribution and a loading density.
Claims15
A method of correcting for variation in line width due to a loading effect generated when the material layer on a photomask substrate is dry-etched to have a desired pattern, the method comprising:
- obtaining a loading effect range δ by dividing the substrate into meshes, and supposing the distribution of a loading effect frequency fL representing the degree of a loading effect at an arbitrary mesh on the substrate from each of other meshes to be a Gaussian distribution expressed according to the relationship f L ( r ) = k π δ 2 · exp [ - r 2 δ 2 ]
- wherein r denotes the distance between the arbitrary mesh and each of the other meshes, and k denotes a loading constant;
- calculating the loading density of the desired pattern, which is defined as a ratio of the area to be etched to the area of each mesh;
- calculating the loading effect at each of the meshes on the substrate by convolving the loading density and loading effect frequency at all of the meshes on the substrate;
- and
- correction-exposing an electron beam resist according to the loading effect calculated at each of the meshes on the substrate.
A recording medium readable by a computer that records a method of correcting a variation in line width due to a loading effect generated when the material layer on a photomask substrate is dry-etched to have a desired pattern, the recording medium comprising:
- a program module for obtaining a loading effect range δ by dividing a predetermined pattern into meshes, calculating a loading effect L for each of the meshes with respect to arbitrary loading effect range values δ and comparing the loading effect with a given line width, the loading effect L expressed as in the following relationship:
- L ( x , y ) = ∑ i , j D ( i , j ) · exp [ - ( x - i ) 2 + ( y - j ) 2 δ 2 ]
- wherein x,y denotes the coordinate of an arbitrary mesh, and D(i,j) denotes the loading density of the patterns in a mesh having a coordinate (i,j);
- a program module for calculating the loading density of the desired pattern, which is defined as a ratio of the area to be etched to the area of each mesh;
- a program module for receiving the loading effect range δ and data of the loading density of the desired patterns and calculating the loading effect L of the desired pattern loaded on each of the meshes using the above relationship for obtaining a loading effect;
- and
- a program module for calculating a correction-exposing dose for each of the meshes from the loading effect of the desired pattern.
Dependencies are inferred from the claim text.