Tri-Layer Siloxane Adhesive for Stepped Wafer Processing
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Solution Overview
Problem
Existing temporary adhesive layers for wafer processing are inadequate in forming a uniform thickness on heavily stepped substrates, failing to provide a complete bond and are not easily removable, which hampers the manufacturing of thin wafers with TSV and bump interconnect structures.
Innovation Solution
A tri-layer temporary bonding arrangement consisting of a thermoplastic siloxane bond-free polymer, a thermoplastic organopolysiloxane polymer, and a thermosetting modified siloxane polymer is used, with the peripheral region of the intermediate layer removed to ensure direct contact between the outer layers, facilitating a stable bond and easy removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a single-layer organic resin protective tape is used, then the wafer is protected during grinding, but the tape lacks sufficient strength and heat resistance for TSV forming and back surface processing
Solution Approach 1:
The patent employs a composite adhesive layer structure consisting of a first adhesive layer (siloxane-modified polymer) and a second adhesive layer (different polymer material) with distinct thicknesses and properties. This composite structure combines the heat resistance and bonding strength of siloxane-modified polymers with the protective characteristics of other polymer materials, achieving both high strength/heat resistance and reliable protective capability during various processing steps including TSV forming and back surface processing.
2Manufacturing precision
If existing temporary adhesive layers are used, then bonding is achieved, but uniform thickness cannot be formed on heavily stepped substrates
Solution Approach 1:
The patent applies local quality by creating a composite adhesive layer where the first adhesive layer (with higher viscosity and heat resistance) is positioned at the bottom near the support, while the second adhesive layer (with different properties) is positioned at the top near the wafer. This spatial differentiation of material properties allows the lower layer to fill gaps and steps effectively while the upper layer provides uniform bonding characteristics, achieving both uniform thickness on stepped substrates and broad adaptability.
3Ease of operation
If existing temporary adhesive layers are used, then bonding is established, but easy removal is not achieved
Solution Approach 1:
The patent utilizes parameter changes by selecting adhesive materials with specific glass transition temperatures (Tg) and bonding characteristics. The first adhesive layer uses siloxane-modified polymer with controlled Tg to provide strong bonding during processing, while the second adhesive layer is formulated with different thermal and chemical properties that enable easy removal after processing. This parameter differentiation between layers allows the system to exhibit strong bonding during use and easy removal afterward, resolving the contradiction between bond durability and ease of removal.
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 allows for the formation of a uniform adhesive layer on stepped substrates, enabling the manufacture of thin wafers with improved heat resistance and ease of removal, enhancing productivity and handling of fragile wafers.
Implementation Method 1
a third temporary bond layer of thermosetting polymer comprising a modified siloxane polymer based layer
Implementation Method 2
a second temporary bond layer of thermoplastic organopolysiloxane having a high degree of polymerization
Data Source
Figure 1
AI summary
A wafer processing laminate is provided comprising a support (3), a temporary adhesive layer (2), and a wafer (1). The temporary adhesive layer (2) has a trilayer structure consisting of a first temporary bond layer (A) of thermoplastic siloxane bond-free polymer, a second temporary bond layer (B) of thermoplastic siloxane polymer, and a third temporary bond layer (C) of thermosetting modified siloxane polymer. In a peripheral region, the second layer (B) is removed so that the first layer (A) is in close contact with the third layer (C).