Polyimide Precursor Drying With Descending Pressure and Heated Gas
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Solution Overview
Problem
Conventional methods for drying polyimide precursors in semiconductor manufacturing are slow, prone to void formation, discoloration, and solvent retention, which can lead to defects in integrated circuit fabrication, and require separate steps for drying and outgassing of plastic molding compounds, increasing processing time.
Innovation Solution
A process utilizing sequential descending pressure operations interspersed with evacuation and heated gas flushing to efficiently dry and imidize polyimide precursors, while simultaneously outgassing plastic molding compounds, reducing voids, discoloration, and solvent retention, and achieving a low oxygen environment for improved substrate processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional heating techniques are used to cure polyimide, then the polyimide layer can be cured, but the curing process takes several hours and causes non-uniform curing with void formation
Solution Approach 1:
The patent changes the physical parameters of the curing environment by applying reduced pressure (vacuum) during the curing process. This parameter change allows solvent removal at lower temperatures and prevents void formation, achieving uniform curing in significantly reduced time compared to conventional atmospheric pressure heating.
Solution Approach 2:
The patent utilizes phase transition of the solvent from liquid to vapor under reduced pressure conditions. By controlling the pressure parameter, the solvent evaporates at lower temperatures, enabling complete solvent removal and uniform curing without the prolonged heating time required by conventional methods.
2Manufacturing precision
If conventional furnace curing is used, then polyimide can be cured, but the outer surface cures faster than center portions causing voids and inferior mechanical properties
Solution Approach 1:
The patent applies reduced pressure as a controlling parameter throughout the curing process. This uniform pressure field ensures simultaneous solvent removal from all regions of the polyimide layer, eliminating the surface-to-center curing gradient that causes voids and mechanical property degradation in conventional furnace curing.
Solution Approach 2:
The patent extracts the solvent from the polyimide layer by applying vacuum pressure. This extraction process removes the harmful solvent that would otherwise cause non-uniform curing, void formation, and degraded mechanical properties, resulting in uniformly cured polyimide with superior mechanical characteristics.
3Reliability
If separate steps are used for drying polyimide precursor and outgassing plastic molding compounds, then each process can be completed, but processing time increases
Solution Approach 1:
The patent merges the drying of polyimide precursor and the outgassing of plastic molding compounds into a single integrated process step. By applying reduced pressure simultaneously to both materials, the patent achieves complete solvent removal from polyimide and complete outgassing of molding compounds in one operation, doubling the processing throughput compared to sequential separate steps.
Solution Approach 2:
The reduced pressure processing system serves multiple functions simultaneously: it dries polyimide precursors by removing solvent, outgasses plastic molding compounds by removing trapped gases, and prevents void formation in both materials. This multi-functionality eliminates the need for separate processing steps and significantly increases manufacturing productivity.
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 process significantly reduces processing time, minimizes defects, and enhances the quality of polyimide layers, allowing for faster and more reliable semiconductor fabrication with fewer steps, and maintains a low oxygen environment for subsequent processing.
Implementation Method 1
A polyimide precursor may be applied to a substrate, and then dried to prepare for imidization of the polymer. A goal of the drying process is to remove the solvent from the polymer
Implementation Method 2
The process uses a sequential set of descending pressure operations that allow for time efficient processing of wafers. The set of descending pressure operations are interspersed with evacuation processes using heated gasses
Implementation Method 3
The set of descending pressure operations are interspersed with evacuation processes using heated gasses, which combine heating and byproduct evacuation
Implementation Method 4
A polyimide precursor may be applied to a substrate, and then dried to prepare for imidization of the polymer
Data Source
AI summary
A process for the drying, and subsequent imidization, of polyimide precursors which minimizes or eliminates voids and which minimizes or eliminates discoloration. The process uses a sequential set of descending pressure operations that allow for time efficient processing of wafers. The set of descending pressure operations are interspersed with evacuation processes using heated gasses, which combine heating and byproduct evacuation. The process results in layers with reduced or eliminated voiding, discoloration, and solvent retention.