Three-dimensional mask model for photolithography simulation

A lithography simulation system, comprising:

• a three-dimensional mask model of a type of photolithography mask, comprising:
• a linear filtering kernel configured to be convolved with a mask layout image;
• a bilinear filtering kernel configured to be convolved with a square of a derivative of the mask layout image;
• and
• a bilinear filtering kernel configured to be convolved with a square of another derivative of the mask layout image,
• wherein the linear filtering kernel and the bilinear filtering kernels collectively represent the effects of the topography of the type of photolithography mask on light passing through a mask of that type;
• and
• a software tool adapted to use the model to simulate an image produced by a lithographic tool using the mask.

A computer-implemented method for creating a three-dimensional mask model, comprising:

• rigorously simulating the effect of light passing through a mask using three-dimensional mask topography information to produce a theoretical image;
• determining initial filtering kernels for a three-dimensional mask model using the theoretical image;
• and
• modifying the initial filtering kernels until a total difference between the theoretical image and a simulated image is minimized or below a predetermined threshold to produce final filtering kernels,
• wherein the final filtering kernels are configured to be convolved with thin-mask transmission functions to produce a near-field image and wherein the simulating, determining and modifying steps are implemented using the computer.

A computer-implemented method for creating a three-dimensional mask model, comprising:

• rigorously simulating the effect of light passing through a mask using three-dimensional mask topography information to produce a theoretical image;
• determining initial correction factors for a three-dimensional mask model using the theoretical image;
• and
• modifying the initial correction factors until a total difference between the theoretical image and a simulated image is minimized to produce final correction factors,
• wherein the final correction factors are configured to be multiplied by a Fourier transform of thin-mask transmission functions to produce a near-field image and wherein the simulating, determining and modifying steps are implemented using the computer.

A computer program product comprising a computer storage medium for storing instructions for performing:

• determining initial filtering kernels for a three-dimensional mask model using a theoretical image produced by rigorously simulating the effect of light passing through a mask using three-dimensional mask topography information;
• and
• modifying the initial filtering kernels until a total difference between the theoretical image and a simulated image is minimized or below a predetermined threshold to produce final filtering kernels,
• wherein the final filtering kernels are configured to be convolved with thin-mask transmission functions to produce a near-field image.

A computer program product comprising a computer storage medium for storing instructions for performing:

• determining initial correction factors for a three-dimensional mask model using a theoretical image produced by rigorously simulating the effect of light passing through a mask using three-dimensional mask topography information;
• and
• modifying the initial correction factors until a total difference between the theoretical image and a simulated image is minimized to produce final correction factors,
• wherein the final correction factors are configured to be multiplied by a Fourier transform of thin-mask transmission functions to produce a near-field image.