Laser Resist Removal for IC Packaging
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Solution Overview
Problem
Current methodologies for removing resist materials from integrated circuit (IC) package components require hazardous chemicals and cause damage to silicon-based components, necessitating the development of a non-chemical method for efficient resist removal.
Innovation Solution
The use of laser energy to ablate and degrade resist materials, allowing for dry removal without damaging other package components, through controlled irradiation and subsequent fluid separation of the resist layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wet chemical processes are used to remove photoresist, then resist removal is achieved, but damage to silicon-based components occurs and hazardous chemicals are required
Solution Approach 1:
The patent replaces wet chemical processes with a laser-based system that uses light energy to remove photoresist. The laser system employs optical fields and mechanical vibration (ultrasonic assistance) to achieve resist removal without chemical damage to underlying components, directly substituting chemical action with physical energy fields.
Solution Approach 2:
The patent utilizes controlled laser parameters (wavelength, pulse duration, energy density) to selectively remove photoresist while preserving underlying components. By adjusting these parameters, the system achieves precise control over the removal process, enabling effective resist removal without the harmful effects of chemical processes.
2Productivity
If conventional chemical removal methods are used, then resist is removed, but hazardous chemicals and damage to components are involved
Solution Approach 1:
The patent replaces chemical-based resist removal with a laser-based system that uses optical energy and mechanical vibration. This substitution eliminates hazardous chemical waste while maintaining high removal efficiency, as the laser system can rapidly process large areas of photoresist through non-contact energy delivery.
Solution Approach 2:
The laser system induces phase transitions in the photoresist material, transforming it from solid to vaporized or carbonized state through controlled heating. This phase change enables complete removal of resist material without requiring chemical solvents, thereby eliminating hazardous chemical waste while maintaining high productivity.
3Object-affected harmful factors
If laser energy is used to remove resist, then chemical-free processing is achieved, but controlled irradiation parameters are required
Solution Approach 1:
The patent introduces ultrasonic vibration as an intermediary mechanism that enhances laser effectiveness. The mechanical vibration assists the laser energy in breaking down photoresist bonds and facilitating material removal, thereby reducing the complexity of laser parameter control while maintaining chemical-free processing.
Solution Approach 2:
The laser system employs pulsed or periodic irradiation rather than continuous exposure. This periodic action allows controlled energy delivery that prevents overheating and damage to underlying components while effectively removing photoresist, simplifying the control requirements compared to continuous high-power irradiation.
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 clean and efficient removal of resist materials from IC package components with reduced risk of damage, using laser-induced cracking and delamination to facilitate dry processing and minimize chemical usage.
Implementation Method 1
exposing a portion of a solder resist layer disposed on a die to a laser light configured to induce crack formation in the portion of the solder resist layer
Implementation Method 2
The solder resist layer and the wafer assembly may have different coefficients of thermal expansion (CTEs). In various embodiments, the laser light may be configured to induce crack formation between the exposed portion of the solder resist layer and the die
Implementation Method 3
applying a flow of fluid to the exposed portion of the solder resist layer to separate the exposed portion of the solder resist layer from the die at the interface
Data Source
AI summary
Embodiments of the present disclosure are directed to laser removal of resist material from integrated circuit (IC) packaging components, as well as package assemblies and systems incorporating such material and removal methods. A resist layer may be applied to one or more components of a package assembly. The resist layer may be subsequently removed by applying laser radiation and a flow of fluid to the resist layer. The laser radiation may cause cracking, delamination, and/or polymer chain scission, and the flow of fluid may enhance mechanical separation of the resist material from the package assembly components.