Phase Shift Mask Lithography for Sub-Micron Conductive Patterns
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Solution Overview
Problem
Current manufacturing methods for integrated fan-out packages face challenges in achieving high packing densities and small feature sizes due to limitations in lithography tools with low numerical aperture (NA), which result in low image contrast and limited pitch resolution, making it difficult to produce sub-micron scale conductive lines and patterns.
Innovation Solution
The use of a phase shift mask and adjustments to the constant k1 in the Rayleigh formula, or a double exposure method, in conjunction with I-line lithography with low NA, enhances image contrast and optical resolution, allowing for the formation of sub-micron scale redistribution conductive patterns and structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional I-line lithography with low numerical aperture (NA) is used, then wide depth of focus is maintained, but image contrast and pitch resolution are limited, preventing sub-micron critical dimensions
Solution Approach 1:
A phase shift mask is introduced as an intermediary component between the light source and photoresist. The mask includes phase shift regions that modify the phase of incident light, creating constructive and destructive interference patterns that enhance image contrast and enable sub-micron resolution while maintaining compatibility with low NA optical systems
Solution Approach 2:
The optical parameters of the lithography system are modified by introducing phase shift regions with specific thicknesses and refractive indices. These parameter changes alter the phase of light waves, transforming the illumination pattern to achieve higher contrast and resolution without changing the numerical aperture
2Manufacturing precision
If conventional I-line lithography with low numerical aperture (NA) is used, then existing tool capabilities are maintained, but pitch resolution is limited, preventing formation of sub-micron patterns
Solution Approach 1:
The phase shift mask serves as an intermediary that enhances pitch resolution by manipulating light phase. This allows existing low NA tools to achieve higher resolution without requiring tool upgrades, while the added complexity is confined to the mask design rather than the entire lithography system
Solution Approach 2:
The mask is segmented into different regions with distinct phase shift properties. By dividing the mask into phase shift regions and non-phase shift regions, the system achieves enhanced resolution through localized phase manipulation without requiring complete system redesign
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 improves lithography performance, maintains wide depth of focus, and achieves sub-micron critical dimensions, exceeding the capabilities of conventional I-line exposure tools, enabling the production of compact and high-density redistribution circuit structures.
Implementation Method 1
The use of a phase shift mask and adjustments to the constant k1 in the Rayleigh formula
Implementation Method 2
enhances image contrast and optical resolution
Implementation Method 3
The first photoresist material is exposed through a phase shift mask to an I-line wavelength within an I-line stepper
Data Source
AI summary
A first photoresist material is formed. The first photoresist material is exposed through a phase shift mask. The first photoresist material is developed to form a first photoresist layer, wherein the first photoresist layer comprises a plurality of first photoresist patterns and a plurality of first openings between the plurality of first photoresist patterns. A first conductive material is formed in the plurality of first openings. A second photoresist layer is formed over the first conductive material, wherein the second photoresist layer comprises at least one second opening. A second conductive material is formed in the at least one second opening. The first photoresist layer and the second photoresist layer are removed, to form a plurality of first conductive patterns and at least one second conductive pattern. A dielectric layer is formed, wherein the at least one second conductive pattern is disposed in the dielectric layer.