Microlithography Exposure Apparatus Dual-State Illumination
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Solution Overview
Problem
Microlithography projection exposure apparatuses face challenges in imaging and illuminating structure-bearing masks that are larger than the available illumination field, leading to incomplete imaging and issues with shadow and projection effects due to oblique illumination, especially when the centroid direction of radiation differs significantly from perpendicular.
Innovation Solution
The apparatus operates in two states with distinct centroid direction vectors for each partial region of the mask, ensuring a scalar triple product less than 0.05, allowing for compensation of shadow and projection effects, and can rotate the mask by 180° between exposures to maintain consistent illumination directions, enabling the imaging of larger masks with reduced shadow and projection distortions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the mask is larger than the illumination field, then the mask cannot be completely illuminated or imaged, but dividing the mask into partial regions increases the complexity of the exposure process
Solution Approach 1:
The mask is divided into multiple partial regions that are individually illuminated and imaged. Each partial region is exposed separately through multiple exposure steps, allowing the complete mask to be processed even though it exceeds the illumination field size. This segmentation approach enables handling of large masks by breaking them into manageable sections.
Solution Approach 2:
The exposure process is performed periodically in multiple steps, with each step illuminating a different partial region of the mask. The mask or illumination system is repositioned between exposures to cover different areas, creating a periodic sequence of exposure actions that collectively illuminate the entire mask surface.
2Area of stationary object
If oblique illumination is used to illuminate the mask, then the illumination can reach larger areas, but shadow and projection effects increase when the centroid direction differs significantly from perpendicular
Solution Approach 1:
The illumination characteristics are optimized locally for each partial region. By dividing the mask into smaller partial regions, the illumination can be more precisely controlled for each region, reducing the angle of incidence and minimizing shadow effects while still achieving complete coverage of the entire mask through multiple exposures.
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 configuration allows for the complete imaging of larger masks with minimal shadow and projection effects, improving the production of microelectronic components by ensuring uniform illumination and reducing mechanical complexity in the exposure process.
Implementation Method 1
a projection optical unit for imaging the mask onto a substrate (the wafer)
Implementation Method 2
The exposure of the photosensitive layer and further chemical processes give rise to a microelectronic component
Data Source
AI summary
A microlithography projection exposure apparatus for producing microelectronic components has at least two operating states. The microlithography projection exposure apparatus includes a reflective mask in an object plane. In the first operating state, a first partial region of the mask is illuminated by a first radiation, which has an assigned first centroid direction having a first centroid direction vector at each point of the first partial region. In the second operating state, a second partial region of the mask is illuminated by a second radiation, which has an assigned second centroid direction having a second centroid direction vector at each point of the second partial region. The first and the second partial region have a common overlap region. Furthermore, the microlithography projection exposure apparatus can be configured in such a way that at each point of at least one partial region of the overlap region the scalar triple product of the normalized first centroid direction vector, the normalized second centroid direction vector and a normalized vector that is perpendicular to the mask is less than 0.05.