Spin-on Adhesive for Thin Substrate Handling
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Solution Overview
Problem
The challenge in the semiconductor industry is to effectively thin substrates for integrated circuits (ICs) to reduce size and increase efficiency, while maintaining control and handling during processing, especially for substrates thinner than 300 μm, where mechanical attachment becomes difficult due to geometric limitations and the need for precise thermal expansion matching between materials.
Innovation Solution
A novel composition comprising a hydrocarbon resin and rubber dispersed in a solvent system is used as a protective coating or adhesive, providing a solution for substrate thinning by forming a durable, chemically resistant film that allows for efficient handling and processing of thin substrates, including the use of a carrier wafer for further thinning and post-processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If substrate thickness is reduced to less than 300 μm to enable IC miniaturization, then manufacturing cost and processing time are reduced, but mechanical control and handling of the substrate become difficult
Solution Approach 1:
A carrier substrate is introduced as an intermediary platform to support thin substrates during processing. The carrier substrate has a thickness of 100-500 μm and provides mechanical strength while allowing the thin substrate (less than 300 μm) to be handled and processed effectively. This mediator resolves the contradiction by enabling fast processing of thin substrates while maintaining ease of handling through the carrier support.
Solution Approach 2:
The system uses a composite structure combining the thin substrate with a carrier substrate of matching thermal expansion properties. This composite approach allows the thin substrate to benefit from rapid processing while the carrier provides mechanical robustness for handling, thus resolving the contradiction between processing speed and ease of operation.
2Volume of moving object
If substrate thickness is reduced to less than 100 μm to minimize IC footprint, then transmission line thickness is reduced and capacitance decreases, but mechanical attachment and control become impossible
Solution Approach 1:
The carrier substrate serves as a mediator that enables mechanical attachment and handling of ultra-thin substrates (less than 100 μm). The carrier provides the necessary mechanical strength for attachment while the thin substrate maintains its miniaturized form factor, thus resolving the contradiction between small IC size and ease of attachment.
Solution Approach 2:
Different parts of the system have different thicknesses optimized for their specific functions: the substrate is made ultra-thin (less than 100 μm) for miniaturization where size matters, while the carrier substrate has a greater thickness (100-500 μm) for mechanical support where strength is needed. This local differentiation resolves the contradiction between small volume and ease of operation.
3Strength
If carrier substrate thickness is increased to improve mechanical strength, then handling becomes easier, but thermal expansion mismatch with the substrate increases
Solution Approach 1:
The thickness of the carrier substrate is optimized to a specific range (100-500 μm) that balances mechanical strength with thermal expansion compatibility. This parameter optimization allows the carrier to provide sufficient strength for handling thin substrates while maintaining thermal expansion matching to prevent stress and delamination, thus resolving the contradiction between strength and thermal stability.
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 composition enables efficient thinning of substrates to less than 100 μm, with low outgassing and resistance to acids and bases, facilitating subsequent processing steps like photolithography and metallization, while being easily removable for reuse, thus improving IC miniaturization and reducing costs.
Implementation Method 1
The cured or dried composition is also acid- and base-resistant. That is, a cured or dried layer of the composition having a thickness of 15 μm can be submerged in an acid (e.g., 49% hydrofluoric acid) or base (e.g., 30% ammonium hydroxide, 20-40% potassium hydroxide) for at least 45 minutes without the acid or base removing, etching, or otherwise damaging the layer.
Implementation Method 2
A novel composition comprising a hydrocarbon resin and rubber dispersed in a solvent system is used as a protective coating or adhesive, providing a solution for substrate thinning by forming a durable, chemically resistant film that allows for efficient handling and processing of thin substrates, including the use of a carrier wafer for further thinning and post-processing.
Implementation Method 3
The cured or dried composition can be removed using the original solvent that was part of the composition prior to curing or drying as well as using non-polar solvents such as xylene, benzene, limonene, and any other solvent described above as acceptable for use as part of the inventive compositions. The layer will begin to soften within a few minutes of being placed in the dissolving solvent, and will be completely dissolved (at least about 98%, preferably at least about 99%, and more preferably about 100%) after two hours of immersion in a dissolving solvent having a temperature of 130° C.
Data Source
AI summary
New compositions for use as protective coatings and/or adhesives are provided. The compositions comprise a hydrocarbon resin (e.g., terpene rosin) and a rubber (e.g., EPDM) dispersed or dissolved in a solvent system. The solvent system is preferably a single-solvent system, and the compositions are preferably free of surfactants, dyes, and chromophores. The compositions can be cured or dried to form layers or films that are chemically and thermally resistant, but that can be readily dissolved and removed at the appropriate stage in the fabrication process.