Polyimide Adhesive Composition for Low-Temperature Wafer Bonding
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional adhesives used in wafer processing face issues such as poor thermal tolerance, residue formation, and substrate deformation due to thermal expansion coefficient mismatches, leading to device damage.
Innovation Solution
A polyimide adhesive composed of specific diamines and dianhydrides, with controlled weight percentages, providing a glass transition temperature range of 180° C. to 245° C. and low UV light transmittance, allowing bonding at lower temperatures and enabling laser-induced separation without residue.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If acrylic-based adhesives are used for temporary wafer protection, then the adhesive provides ease of application and initial bonding, but the adhesive exhibits poor thermal tolerance (≤150° C.) and leaves residue on electrode sidewalls
Solution Approach 1:
The patent changes the chemical composition parameters of the adhesive by incorporating polyimide as the base material and adding specific plasticizers (phthalate esters, cycloaliphatic hydrocarbons, or esters) in controlled amounts (0.1-10 wt%). This parameter modification enables the adhesive to maintain flexibility and bonding capability while achieving thermal stability up to 300°C and above, resolving the contradiction between ease of application and thermal tolerance.
Solution Approach 2:
The patent creates a composite adhesive material by combining polyimide with plasticizers and optional additives. The polyimide provides the thermal backbone while the plasticizer components contribute flexibility and processability. This composite approach allows the adhesive to simultaneously achieve high thermal tolerance, ease of application, and clean release without residue formation on electrode sidewalls.
2Temperature
If polyamic-acid-based adhesives are used, then the adhesive can form a polyimide film with high temperature resistance, but the high process temperatures (above 300° C.) cause substrate bending, deformation, cracking, and delamination due to thermal expansion coefficient differences
Solution Approach 1:
The patent modifies the processing parameters by enabling adhesive curing at lower temperatures (200-280°C) through the use of pre-formed polyimide with plasticizers. This eliminates the need for high-temperature processing (>300°C) required by conventional polyamic-acid methods, thereby preventing substrate bending, deformation, and cracking while still achieving the desired temperature resistance in the final adhesive layer.
Solution Approach 2:
The patent introduces plasticizers as intermediary substances that facilitate low-temperature processing. These plasticizers act as mediators between the polyimide matrix and the substrate, enabling the adhesive to achieve proper bonding and curing at temperatures that do not cause excessive thermal stress or substrate damage, thus maintaining manufacturing precision while achieving temperature resistance.
3Strength
If conventional adhesives are used, then the adhesive provides initial bonding capability, but the adhesive shows significant stress due to thermal expansion coefficient differences between the adhesive and substrate, leading to device damage
Solution Approach 1:
The patent changes the thermal and mechanical parameters of the adhesive by incorporating plasticizers into the polyimide matrix. This modification adjusts the thermal expansion coefficient of the adhesive to be more compatible with common substrates like silicon and glass, reducing thermal stress during temperature cycling. The adhesive maintains strong bonding capability while improving reliability by preventing device damage from thermal mismatch stress.
Solution Approach 2:
The patent creates a composite adhesive system where polyimide provides thermal stability and the plasticizer components provide flexibility and stress relief. This composite structure allows the adhesive to accommodate thermal expansion differences between the adhesive layer and substrate, maintaining bonding strength while protecting device integrity during thermal processing and operation.
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 adhesive ensures stable substrate bonding at lower temperatures, preventing warping and residue formation, facilitating efficient separation of electronic elements during processing.
Implementation Method 1
polyamic acid material is coated onto a substrate and then subjected to high temperatures (above 300° C.) to close the polyamic acid ring and form a polyimide film
Implementation Method 2
enabling laser-induced separation without residue
Data Source
AI summary
An adhesive and multilayer structure are provided. The adhesive includes a polyimide, wherein the polyimide is a reaction product of a reactant (a) and a reactant (b). The reactant (a) is a first diamine or the reactant (a) includes of a first diamine and a second diamine, and the reactant (b) includes of a first dianhydride and a second dianhydride. The first diamine is a diphenyl-ether-moiety-containing diamine, the first dianhydride is a diphenyl-ether-moiety-containing dianhydride, the second diamine is not a diphenyl-ether-moiety-containing diamine, and the second dianhydride is not a diphenyl-ether-moiety-containing dianhydride. The total weight percentage of the first diamine and the first dianhydride is 55 wt % to 94 wt %, based on the total weight of the reactant (a) and the reactant (b).