Illumination compensation method

An illumination compensation method, comprising:

• acquiring working gaps between an imaging film stack and a mask in an exposure imaging system;
• calculating an imaging light field intensity of the photoresist layer in the imaging film stack corresponding to different working gaps;
• constructing a functional dependence of imaged pattern critical dimension in the photoresist layer of the imaging film stack on the working gap based on said imaging light field intensity critical dimension;
• calculating compensation parameters required for illumination light according to the said functional dependence of imaged pattern critical dimension on working gap;
• and
• performing illumination compensation on the exposure imaging system according to the compensation parameters,
• wherein the step of calculating the imaging light field intensity of the photoresist layer in the imaging film stack corresponding to different working gaps comprises:
• establishing an optical simulation model from the illumination light to the imaging light field in the photoresist layer, wherein the optical simulation model comprises a projection lens group simulation model modeling light propagation from the illumination light to the incident light on the upper surface of the mask, and an imaging film stack optical simulation model modeling light propagation from the on the upper surface of the mask to the imaging light field in the photoresist layer;
• and
• calculating the imaging light field intensity of the photoresist layer corresponding to varied working gaps under given mask patterns and illumination light distribution based on the optical simulation model,
• wherein the step of constructing a functional dependence of imaged pattern critical dimension in the photoresist layer of the imaging film stack on the working gap based on said imaging light field intensity comprises:
• applying a threshold to the imaging light field intensity of the photoresist layer corresponding to each working gap, to obtain the critical dimension of the imaged pattern of the photoresist layer corresponding to the working gap;
• and
• constructing the relationship between the critical dimension of the imaged pattern of the photoresist layer and the working gap based on a critical dimension of the imaged pattern corresponding to each working gap,
• wherein the step of calculating compensation parameters required for illumination light according to the said functional dependence of imaged pattern critical dimension on working gap comprises:
• according to the relationship between the original critical dimension of the imaged pattern and the working gap, and the relationship between the expected critical dimension of the imaged pattern and the working gap, calculating the critical dimension of the imaged pattern of the photoresist layer that needs to be compensated under different working gaps;
• and
• converting the critical dimension of the imaged pattern of the photoresist layer that needs to be compensated into corresponding imaging light field intensity, substituting the corresponding imaging light field intensity into the optical simulation model, and calculating compensation parameters, wherein the compensation parameters include light intensity, polarization state, and phase.