Monolithic Prism-Mask for Angled Lithographic Patterning
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Solution Overview
Problem
Traditional photolithography systems struggle to create patterned features that are not perpendicular to the substrate, as they require complex alignment and suffer from misalignment errors, refractive index differences, and high light reflection, limiting the achievable tilt angle to around 25°, making it difficult to produce angled patterns accurately.
Innovation Solution
The use of a monolithic prism-mask system that integrates a masked layer directly on a prism, eliminating the need for separate masks and optical gels, allowing actinic radiation to pass through without alignment errors and reducing reflections, enabling the formation of angled features like tilted vias and lines without misalignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a separate mask and optical gel system is used for angled patterning, then the ability to form non-perpendicular features is improved, but alignment precision deteriorates due to misalignment between mask and substrate
Solution Approach 1:
The patent combines the mask and optical gel into a single integrated component called a prism-mask. The mask patterns are directly formed on the prism structure itself, eliminating the need for separate mask and optical gel components. This integration ensures that the mask and optical elements are perfectly aligned as a single unit, resolving the alignment precision problem while maintaining the ability to form angled features through the prism's optical properties
2Ease of operation
If traditional photolithography with vertical projection is used, then alignment simplicity is improved, but the ability to form non-perpendicular features deteriorates
Solution Approach 1:
The prism-mask serves multiple functions simultaneously: it acts as both the masking element that defines pattern geometry and the optical element that redirects light at angled trajectories. This multi-functionality allows the system to maintain simple vertical projection alignment while forming non-perpendicular features through the prism's light-bending capability, thus achieving both alignment simplicity and angled patterning versatility
3Use of energy by moving object
If optical gel is used between mask and substrate, then light transmission is improved, but light reflection increases
Solution Approach 1:
The patent extracts and eliminates the optical gel from the system by integrating its light-transmitting function directly into the prism-mask structure. The mask patterns are formed on the prism surface itself, removing the need for a separate optical gel layer. This extraction eliminates the additional interfaces that cause light reflection while maintaining light transmission through the prism material, thereby reducing harmful reflections while preserving light transmission
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 solution effectively eliminates overlay errors and increases the practical limit of tilt angles, allowing for more precise and accurate non-perpendicular patterning, reducing light reflection, and simplifying the manufacturing process by integrating the mask and prism as a single object.
Implementation Method 1
the prism includes a first surface that is substantially parallel to the surface of the stage... allowing actinic radiation to pass through without alignment errors
Data Source
AI summary
Embodiments disclosed herein include a lithographic patterning system and methods of using such a system to form a microelectronic device. The lithographic patterning system includes an actinic radiation source, a stage having a surface for supporting a substrate with a resist layer, and a prism with a first surface over the stage, where the first surface has a masked layer and is substantially parallel to the surface of the stage. The prism may have a second surface that is substantially parallel to the first surface. The first and second surfaces are flat surfaces. The prism is a monolithic prism-mask, where an optical path passes through the system and exits the first surface of the prism through the mask layer. The system may include a layer disposed between the mask and resist layers. The mask layer of the prism may pattern the resist layer without an isolated mask layer.