Redistribution Layer Formation via Micro-Imprint Lithography
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Solution Overview
Problem
Conventional wafer level packaging methods for semiconductor devices are limited by costly and time-consuming photolithography and etch processes, which restrict the formation of reconstituted substrates and redistribution layers, leading to misalignment issues and reduced I/O connections due to equipment intensity and high manufacturing costs.
Innovation Solution
The implementation of micro-imprint lithography (MIL) processes, involving the deposition of polymers like polyimide, imprinting patterns using heated stamps, and subsequent thermal curing, enables the formation of redistribution layers with fewer process operations, higher aspect ratios, and improved alignment, reducing manufacturing costs and increasing I/O connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional photolithography and etch processes are used to form redistribution layers, then alignment precision can be maintained, but manufacturing cost increases and productivity decreases
Solution Approach 1:
The patent replaces the optical-based photolithography system with a mechanical imprinting system. A stamp or mold is physically pressed into the polymer material to directly transfer the pattern, eliminating the need for optical exposure and chemical development processes. This mechanical substitution maintains pattern precision while dramatically reducing process time and equipment complexity.
Solution Approach 2:
The patent changes the physical state and properties of the polymer material through temperature control. The polymer is heated to become soft and pliable during imprinting, allowing easy pattern transfer, then cooled to solidify and maintain the formed structure. This parameter change enables the same material to facilitate both precise pattern formation and structural stability.
2Manufacturing precision
If conventional photolithography and etch processes are used to form redistribution layers, then manufacturing precision can be maintained, but manufacturing cost increases
Solution Approach 1:
The patent replaces the optical-based photolithography system with a mechanical imprinting system. A stamp or mold is physically pressed into the polymer material to directly transfer the pattern, eliminating the need for optical exposure and chemical development processes. This mechanical substitution maintains pattern precision while dramatically reducing process time and equipment complexity.
Solution Approach 2:
The patent employs a stamp or mold that can be reused multiple times to create patterns. This single patterning tool serves many devices simultaneously, replacing the expensive and equipment-intensive photolithography system. The stamp approach is particularly cost-effective for high-volume production where the same pattern is replicated across numerous devices.
3Reliability
If conventional photolithography processes are used, then process reliability can be maintained, but process complexity increases
Solution Approach 1:
The patent combines multiple separate process steps into a single imprinting operation. The pattern transfer, material deposition, and structure formation are all accomplished in one mechanical pressing action rather than through sequential photolithography, etching, and deposition steps. This merging reduces process complexity while maintaining reliability through fewer process transitions.
Solution Approach 2:
The patent extracts and removes the complex chemical processing steps (photoresist coating, optical exposure, chemical development, and etching) from the manufacturing process. By using direct mechanical imprinting on polymer materials, the process eliminates multiple chemical baths and processing stages, significantly simplifying the overall manufacturing workflow while maintaining pattern fidelity.
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
Micro-imprint lithography significantly reduces manufacturing costs, increases throughput, and allows for the formation of higher aspect ratio interconnects and denser redistribution layers, enhancing device performance and yield by eliminating voids and misalignment issues, while using non-photosensitive polyimides for superior mechanical and electrical properties.
Implementation Method 1
heating the polymer to between about 120° C. and about 150° C.
Implementation Method 2
heating the polymer to between about 120° C. and about 150° C., imprinting a pattern into the polymer to form a plurality of openings therein
Implementation Method 3
heating the polymer to between about 250° C. and about 400° C. after imprinting the pattern
Data Source
AI summary
Embodiments of the present disclosure generally describe methods of forming one or more device terminal redistribution layers using imprint lithography. The methods disclosed herein enable the formation of high aspect ratio interconnect structures at lower costs than conventional photolithography and etch processes. Further, the processes and methods described herein desirably remove, reduce, and/or substantially eliminate voids in the surrounding polymer layer formed during the polymer deposition process or subsequent thereto.