Method for inspection of periodic grating structures on lithography masks
AssigneeInfineon Technologies AG
InventorsWolfgang Dettmann, Roderick Koehle, Martin Verbeek
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Abstract
The invention relates to a method for inspection of periodic structures on lithography masks using a microscope with adjustable illumination and an operating element for movement of a mechanical stage with the lithography mask attached to it in order to record images of the lithography mask at a computer-controlled location on the lithography mask. The position, the size and the pitch specification of the lithography mask are stored.
Claims21
A method for inspection of periodic structures on a lithography mask using a microscope with adjustable illumination and an operating element used for movement of a mechanical stage wherein the lithography mask is attached to the mechanical stage in order to record images of the lithography mask at a computer-controlled location on the lithography mask, wherein a position, a size and a pitch specification of the mask are stored, the method comprising:
- calibrating a first image of each array structure for selected locations on the lithography mask;
- calculating Fourier coefficients at a reference point of an array/diffraction grating;
- calculating a residual image from a difference between an original image of the array structure and a Fourier expansion;
- and
- forming a threshold value for the calculation of an image indicating an error.
A method for producing a lithography mask, wherein the method comprises:
- coating the lithography mask;
- developing the lithography mask;
- etching the lithography mask;
- inspecting the lithography mask, wherein the inspecting comprises calibrating a first image of each array structure for selected locations on the lithography mask, calculating Fourier coefficients at a reference point of an array/diffraction grating, calculating a residual image from a difference between an original image of the array structure and a Fourier expansion, and forming a threshold value for the calculation of an image indicating an error;
- and
- repairing the lithography mask based upon results of the inspecting.
A method of manufacturing a semiconductor device, the method comprising:
- manufacturing a lithography mask;
- inspecting the lithography mask, wherein the inspecting comprises calibrating a first image of each array structure for selected locations on the lithography mask, calculating Fourier coefficients at a reference point of an array/diffraction grating, calculating a residual image from a difference between an original image of the array structure and a Fourier expansion, and forming a threshold value for the calculation of an image indicating an error;
- forming a resist material over a semiconductor substrate;
- patterning the resist material using the lithography mask;
- and
- effecting the semiconductor substrate based on the patterning.
Dependencies are inferred from the claim text.