Two-Layer Temporary Adhesive for Wafer Processing
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Solution Overview
Problem
Existing temporary adhesive layers in semiconductor wafer processing are inadequate for forming a uniform bond on heavily stepped substrates, fail to withstand TSV forming and interconnect steps, and are difficult to remove, limiting productivity and wafer thinning capabilities.
Innovation Solution
A two-layer temporary adhesive system comprising a thermoplastic organopolysiloxane as the first bond layer and a thermosetting modified siloxane polymer as the second bond layer, allowing for a strong, uniform bond and easy release of wafers from supports during processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a single-layer organic resin protective tape is used, then the wafer is protected from breakage during grinding, but the tape lacks sufficient strength and heat resistance for TSV forming and interconnect steps
Solution Approach 1:
The adhesive layer is divided into two distinct layers: a first adhesive layer (organopolysiloxane) providing heat resistance and strength for TSV/interconnect processes, and a second adhesive layer (modified siloxane polymer) providing protection during grinding. This segmentation allows each layer to specialize in specific functions, resolving the contradiction between heat resistance and grinding protection.
Solution Approach 2:
The invention uses a composite adhesive structure combining two different polymer materials with complementary properties. The organopolysiloxane provides high-temperature stability while the modified siloxane polymer provides mechanical protection, creating a composite system that satisfies both heat resistance and grinding protection requirements simultaneously.
2Ease of operation
If a light-absorbing adhesive composition is used for removal, then the adhesive layer can be decomposed by high intensity light, but expensive laser equipment and longer treatment time are required
Solution Approach 1:
The invention changes the chemical composition parameters of the adhesive layers to enable removal by conventional chemical means rather than requiring high-intensity light decomposition. The specific polymer compositions are selected to be removable by standard semiconductor processing chemicals, eliminating the need for expensive laser equipment and reducing treatment time.
3Device complexity
If a heat-melting hydrocarbon compound adhesive is used, then the bonding and release process is simple and controlled only by heat, but the adhesive becomes unstable at high temperatures exceeding 200°C
Solution Approach 1:
The adhesive system is segmented into two layers with different thermal characteristics. The first layer (organopolysiloxane) is designed to withstand high temperatures up to 200°C and above, while the second layer (modified siloxane polymer) provides the heat-melting release mechanism at lower temperatures. This segmentation allows the system to benefit from both heat resistance and simple thermal release.
Solution Approach 2:
Different regions of the adhesive system have different thermal properties tailored to specific functions. The first adhesive layer has high-temperature stability for withstanding processing steps, while the second adhesive layer has lower melting point for easy release. This local differentiation of thermal properties resolves the contradiction between heat resistance and simple thermal release.
4Strength
If a silicone adhesive composition is used for temporary bonding, then the substrate can be bonded to support with addition reaction curable adhesive, but removal requires very long immersion in etching solution
Solution Approach 1:
The adhesive system is divided into two removable layers. The first layer (organopolysiloxane) provides strong bonding that can be removed by conventional chemical means, and the second layer (modified siloxane polymer) provides additional bonding with faster removal characteristics. This segmentation enables strong bonding during processing while significantly reducing removal time compared to single-layer silicone adhesives.
Solution Approach 2:
The adhesive layers are designed as temporary, disposable bonding agents that provide sufficient strength during the bonding and processing stages but are easily removed afterward. The two-layer structure allows for controlled removal without requiring prolonged immersion in etching solutions, making the process more efficient and cost-effective.
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 solution enables the formation of a uniform thin wafer with high heat resistance, facilitating efficient TSV and interconnect formation while allowing for easy removal at room temperature, enhancing productivity and handling of fragile wafers.
Implementation Method 1
a first temporary bond layer (A) of thermoplastic organopolysiloxane having a high degree of polymerization which is releasably bonded to the front surface of the wafer
Implementation Method 2
a second temporary bond layer (B) of thermosetting modified siloxane polymer which is laid contiguous to the first temporary bond layer and releasably bonded to the support
Data Source
AI summary
A laminate comprising a support, a temporary adhesive layer, and a wafer having a circuit-forming front surface and a back surface to be processed allows for processing the wafer. The temporary adhesive layer consists of a first temporary bond layer (A) of thermoplastic organosiloxane polymer which is releasably bonded to the front surface of the wafer and a second temporary bond layer (B) of thermosetting modified siloxane polymer which is laid contiguous to the first temporary bond layer and releasably bonded to the support.