Low error-sensitivity multi-target light source-mask optimization method based on vector imaging model

Abstract

The invention provides a vector imaging model-based low-error sensitivity multi-objective light source-mask optimization method. The method comprises the processes as follows: a light source pattern and a mask pattern are initialized; F is set to be an imaging fidelity function as shown in the specification; the formula as shown in the specification is pixel values of various pixel points of an objective pattern; Z(x, y) represents the pixel vales, calculated by a vector imaging model, of the pixel points for imaging in a photoresist corresponding to the current light source pattern and mask pattern; a sensitivity penalty function of an imaging result to an error is constructed as shown in the specification; I(x, y) is the pixel values, calculated by the vector imaging model, of the pixel points of an aerial image corresponding to the current light source pattern and mask pattern; ei represents an error factor; an objective function D is constructed as weighted sum, as shown in the specification, of F and Yi, and gammai is a weight coefficient; and a light source and a mask are optimized on the basis of the optimized objective function D. The optimized light source and mask are within a certain error range through the optimized objective function; and a relatively good exposure effect can be obtained.

Description

technical field [0001] The invention relates to a low-error-sensitivity multi-target light source-mask optimization method based on a vector imaging model, and belongs to the technical fields of resolution enhancement such as integrated circuit design, manufacturing equipment, technology, microscopic imaging, and telephoto imaging. Background technique [0002] Photolithography is the core process in the VLSI manufacturing field. At present, the operating wavelength of the mainstream lithography system in the industry is 193nm. As the lithography process enters the technology node of 45-14nm and below, the critical dimension of the integrated circuit has been far smaller than the wavelength of the light source. Therefore, the vector light field effect and complex light diffraction lead to distortion, shift or resolution reduction of lithography imaging; for this reason, the lithography system must adopt resolution enhancement technology at this time to improve the quality of...

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Problems solved by technology

However, the above method has the following three shortcomings: first, this method is based on a scalar imaging model, which does not take into account the polarization effect of light, and cannot accurately describe the propagation, focusing and imaging process of light in the case of immersion lithography with a large NA; second, the method The method only targets the low-order spherical aberration caused by the topological effect of the mask, and cannot compensate other wave aberrations and other random errors; finally, the method does not control the sensitivity of the imaging results to errors, which makes the method less sensitive to extreme errors. Insufficient compensation ability

The above errors will cause changes in the intensity or phase of the imaging light wave, which will affect the imaging resolution and fidelity

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