EUV Lithography Illumination Intensity Modulation for Pole Imbalance
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Solution Overview
Problem
Extreme ultraviolet (EUV) lithography systems face challenges due to optical distortions and pole imbalance caused by non-perpendicular angles of incidence, leading to undesirable shadows and reduced yield in semiconductor manufacturing.
Innovation Solution
A lithography system and method that modulates illumination intensity based on the angle of incidence to reduce optical distortion, using a combination of refractive and reflective optical components to project radiation onto a mask, and adjusts the exposure intensity profile to compensate for varying angles, ensuring uniform radiation on the workpiece.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If reflective optics are used to direct EUV radiation, then the system can handle EUV wavelengths, but optical distortion and pole imbalance occur due to non-perpendicular angles of incidence
Solution Approach 1:
The illumination system applies different illumination intensities to different regions of the mask corresponding to different angles of incidence. Areas with higher angles of incidence receive adjusted illumination to compensate for the increased path length and reduced efficiency, thereby achieving uniform pattern formation across the substrate despite the use of reflective optics
Solution Approach 2:
The system dynamically adjusts illumination parameters (intensity distribution) based on the angle of incidence at different mask regions. By changing the illumination intensity parameter as a function of position and angle, the system compensates for the non-perpendicular incidence effects and maintains manufacturing precision
2Adaptability or versatility
If the incident radiation is not completely perpendicular to the mask surface, then the system can accommodate non-planar masks, but undesirable shadows and 3D effects occur
Solution Approach 1:
The illumination system pre-compensates for the shadows and 3D effects by adjusting the illumination intensity before the radiation reaches the mask. Areas that would normally produce shadows due to non-perpendicular incidence are pre-enhanced with higher illumination intensity, thereby counteracting the shadow-forming effect and achieving uniform exposure
3Ease of operation
If a complex system of reflective optics is used, then EUV radiation can be directed and shaped, but pole imbalance and optical distortion increase
Solution Approach 1:
The system incorporates feedback mechanisms that measure the actual illumination conditions and angles of incidence at different mask regions, then adjusts the illumination intensity distribution accordingly. This closed-loop control compensates for the optical distortions introduced by the complex reflective optics system
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces pole imbalance and enhances the uniformity of radiation exposure, improving the resolution and yield of semiconductor manufacturing by minimizing optical distortions and maintaining consistent pattern formation across the substrate.
Implementation Method 1
an illuminator operable to: shape the radiation produced by the radiation source into an illumination pattern; and expose the mask by providing the radiation shaped into the illumination pattern to the mask stage
Implementation Method 2
a projection optics module operable to direct the radiation from the mask to the workpiece in order to form a pattern on the workpiece
Data Source
AI summary
A method and system for adjusting exposure intensity to reduce unwanted lithographic effects is disclosed. In some exemplary embodiments, the method of photolithography includes receiving a mask and a workpiece. An orientation of an illumination pattern relative to the mask is determined, and an intensity profile of the illumination pattern is adjusted according to the orientation. The mask is exposed to radiation according to the illumination pattern and the intensity profile. Radiation resulting from the exposing of the mask is utilized to expose the workpiece. In some such embodiments, the intensity profile includes an intensity that varies across an illuminated region of the illumination pattern.