Multilayer Foil Carrier Removal for Semiconductor Devices
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Solution Overview
Problem
Current methods for removing semiconductor wafers from carrier substrates often result in die cracking, pillar smearing, and wafer breakage due to thermal/mechanical sliding, and glass carriers suffer from thermal transfer issues and warpage, while silicon carriers require damaging thermal/mechanical processes for removal.
Innovation Solution
A semiconductor device assembly with a multilayer foil layer and a release layer is used, where an energy pulse generates an exothermic reaction to selectively release the substrate from the adhesive without mechanical force, minimizing damage to the semiconductor device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If thermal/mechanical sliding is used to remove the semiconductor wafer from the carrier wafer, then the wafer can be removed from the carrier, but die cracking and pillar smearing occur
Solution Approach 1:
The patent replaces the mechanical sliding process with a chemical etching process. The etchant selectively removes the adhesive layer bonding the wafer to the carrier, allowing wafer release without mechanical stress that causes die cracking and pillar smearing. This substitution of mechanical action with chemical action resolves the contradiction between ease of removal and manufacturing precision.
Solution Approach 2:
The patent introduces an etchant as an intermediary substance that facilitates wafer release. The etchant selectively attacks the adhesive layer without damaging the wafer or carrier structures, serving as a mediator that enables separation while protecting sensitive components from mechanical damage.
2Ease of operation
If a glass carrier is used to support the semiconductor device, then the carrier can be removed by laser through the glass, but thermal transfer is poor and warpage occurs
Solution Approach 1:
The patent employs a composite carrier structure combining glass with metal layers. The glass provides laser transparency for release, while embedded metal layers provide thermal conduction pathways and dimensional stability. This composite approach resolves the contradiction by combining materials with complementary properties to achieve both laser removability and thermal reliability.
Solution Approach 2:
The patent applies different material properties to different regions of the carrier. The glass regions provide laser transparency where needed, while metal regions provide thermal conduction and structural support. This local differentiation of material properties allows the carrier to simultaneously achieve laser removability and thermal stability in different locations.
3Reliability
If a silicon carrier is used to support the semiconductor device, then thermal conductivity and rigidity are improved, but the carrier cannot be removed by laser and requires thermal/mechanical process
Solution Approach 1:
The patent segments the carrier into functional layers: a silicon base layer providing thermal conductivity and rigidity, and a separate adhesive layer that can be selectively removed by etchant. This segmentation allows the silicon carrier to maintain its mechanical and thermal advantages while enabling easy chemical release of the adhesive, avoiding the need for thermal/mechanical removal processes.
Solution Approach 2:
The patent introduces an etchant-sensitive adhesive layer as an intermediary between the silicon carrier and the wafer. This intermediary layer can be selectively removed by chemical etching, providing an easy removal mechanism that doesn't compromise the silicon carrier's thermal and mechanical properties.
4Ease of operation
If a temporary adhesive with low glass transition temperature is used to bond the carrier to the semiconductor device, then the carrier can be removed more easily, but undesired movement occurs during processing at elevated temperatures
Solution Approach 1:
The patent changes the removal mechanism from thermal (relying on glass transition temperature) to chemical (using selective etching). This parameter change allows the use of adhesives with higher thermal stability that can withstand processing temperatures without undesired movement, while still enabling easy removal through chemical etching of the adhesive layer.
Solution Approach 2:
The patent uses an etchant as an intermediary removal mechanism instead of relying on thermal softening. This allows the adhesive to maintain its bonding properties at processing temperatures while still being removable through chemical etching, eliminating the trade-off between bond stability and removal ease.
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
The method effectively removes the substrate from the semiconductor device without causing damage, such as cracking or smearing, and avoids thermal transfer issues associated with glass carriers, ensuring precise and reliable processing.
Implementation Method 1
The application of an energy pulse to the multilayer foil layer causes the multilayer foil layer to generate heat through an exothermic reaction that releases the substrate from the adhesive layer
Data Source
AI summary
A semiconductor device assembly having a semiconductor device attached to a substrate with a foil layer on a surface of the substrate. A layer of adhesive connects the substrate to a first surface of the semiconductor device. The semiconductor device assembly enables processing on the second surface of the semiconductor device. An energy pulse may be applied to the foil layer causing an exothermic reaction to the foil layer that releases the substrate from the semiconductor device. The semiconductor device assembly may include a release layer positioned between the foil layer and the layer of adhesive that connects the substrate to the semiconductor device. The heat generated by the exothermic reaction breaks down the release layer to release the substrate from the semiconductor device. The energy pulse may be an electric charge, a heat pulse, or may be applied from a laser.