PSPI RDL Patterning for Fine Features Without Laser Damage
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Solution Overview
Problem
Existing methods for forming redistribution layers (RDL) in semiconductor devices, such as laser patterning, are costly and risk damaging underlying components, making it challenging to achieve the high component density required for smaller, more efficient devices.
Innovation Solution
The use of photosensitive polyimide (PSPI) for RDL patterning, which involves spin-coating PSPI over the semiconductor package, irradiating it through a mask to create a pattern, and then developing and removing the PSPI to expose conductive vias, allowing for the formation of a conductive layer and subsequent RDL formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If laser patterning is used to form small features for high component density, then manufacturing precision is improved, but device complexity and cost increase due to expensive equipment requirements
Solution Approach 1:
The patent replaces the mechanical laser beam focusing system with a photolithography-based PSPI patterning system. Instead of using complex laser optics to achieve small features, the invention uses spin-coating of PSPI followed by photolithographic exposure and development, which achieves comparable or better patterning resolution with simpler, more cost-effective equipment.
2Manufacturing precision
If laser patterning is used to minimize beam diameter for small features, then manufacturing precision is improved, but reliability deteriorates due to risk of damaging underlying components
Solution Approach 1:
The patent introduces PSPI as an intermediary material layer between the patterning process and the underlying semiconductor components. The PSPI layer receives the photolithographic pattern and is removed after transferring the pattern to the conductive layer, preventing direct interaction between the patterning process and sensitive underlying components, thus eliminating damage risks while maintaining patterning precision.
3Productivity
If RDL size is reduced to accommodate high component density, then productivity is improved through smaller device footprint, but manufacturing precision requirements increase
Solution Approach 1:
The patent changes the material parameter from traditional photoresist to photosensitive polyimide (PSPI), which has superior properties for high-precision patterning. The PSPI material enables accurate pattern formation at smaller RDL dimensions, supporting higher component density while maintaining the manufacturing precision needed for small feature sizes.
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 method enables improved patterning resolution and accuracy, allowing for the creation of smaller features and higher component densities without damaging underlying components, thus facilitating the production of smaller, more efficient semiconductor devices.
Implementation Method 1
a photosensitive polyimide (PSPI) layer is formed over the first package layer. The PSPI layer is irradiated through a mask
Data Source
AI summary
A semiconductor device is formed by providing a semiconductor package including a shielding layer and forming a slot in the shielding layer using a laser. The laser is turned on and exposed to the shielding layer with a center of the laser disposed over a first point of the shielding layer. The laser is moved in a loop while the laser remains on and exposed to the shielding layer. Exposure of the laser to the shielding layer is stopped when the center of the laser is disposed over a second point of the shielding layer. A distance between the first point and the second point is approximately equal to a radius of the laser.