Wafer Back-Grinding Adhesive Film for Bump Fillability and Clean Peeling
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Solution Overview
Problem
Existing adhesive films for wafer back grinding fail to adequately protect semiconductor wafers with bump structures during grinding, leading to damage, uneven stress distribution, and residue issues due to voids and insufficient energy penetration, which affects chip quality.
Innovation Solution
An adhesive film with a specific layer structure comprising a substrate, buffer, intermediate support, and adhesive layer, where the intermediate support layer has a thickness exceeding 5% of the total and moduli ratios are optimized to enhance bump fillability and support strength, ensuring even energy penetration and residue-free peeling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional adhesive film is used for wafer back grinding, then the wafer front surface is protected during grinding, but voids form between the adhesive film and the bump structure causing uneven stress distribution and wafer damage
Solution Approach 1:
The adhesive layer is designed with specific material properties (storage modulus range) that enable it to locally adapt to the bump structure. The adhesive layer's lower storage modulus compared to the intermediate support layer allows it to flow into and fill the voids around bumps, creating uniform stress distribution across the wafer surface during grinding.
Solution Approach 2:
The adhesive film employs a composite structure with multiple layers having different mechanical properties. The intermediate support layer has higher storage modulus than the adhesive layer, creating a gradient structure that combines the benefits of structural support with adaptive filling capability, resolving the contradiction between protection reliability and stress uniformity.
2Ease of manufacture
If the adhesive film structure is simplified, then manufacturing cost is reduced, but support strength between adhesive layer and buffer layer becomes insufficient causing cracks and damage
Solution Approach 1:
The adhesive film is segmented into distinct functional layers: a substrate layer, a buffer layer, an intermediate support layer, and an adhesive layer. This segmentation allows each layer to be optimized for its specific function while maintaining overall manufacturing efficiency. The intermediate support layer specifically provides the needed support strength between the adhesive and buffer layers.
Solution Approach 2:
The invention controls the storage modulus parameter of each layer to achieve the desired balance. The intermediate support layer has a storage modulus higher than both the adhesive layer and buffer layer, creating optimal mechanical support. This parameter optimization enables sufficient inter-layer strength without excessive structural complexity.
3Ease of operation
If energy is radiated to remove the adhesive film after grinding, then the adhesive film can be peeled away, but shaded regions from voids prevent sufficient energy penetration leaving residue
Solution Approach 1:
The adhesive film structure is designed to prevent the formation of problematic voids in the first place. The adhesive layer's ability to fill bumps and the intermediate support layer's structural integrity eliminate shaded regions before energy removal occurs. This preliminary structural optimization ensures complete energy penetration and residue-free removal without requiring additional corrective measures.
4Reliability
If the intermediate support layer thickness is increased, then bump fillability and support strength are improved, but the overall adhesive film thickness increases affecting processability
Solution Approach 1:
The invention optimizes the thickness parameter of the intermediate support layer to exceed 5% of the total adhesive film thickness. This parameter control ensures sufficient bump fillability and support strength while maintaining reasonable overall thickness for efficient wafer processing. The thickness ratio specification balances structural performance with manufacturing productivity.
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 film effectively prevents wafer damage, crack formation, and adhesive residue, improving processability and chip quality by maximizing bump fillability and support strength during the grinding process.
Implementation Method 1
at 25° C., a storage modulus of the adhesive layer is less than a storage modulus of the intermediate support layer
Implementation Method 2
an adhesive film for wafer back grinding, the adhesive film comprising a substrate layer, a buffer layer disposed on the substrate layer, an intermediate support layer disposed on the buffer layer, and an adhesive layer disposed on the intermediate support layer
Data Source
AI summary
Embodiments of the present invention provide adhesive films that can be used to protect a surface of a semiconductor wafer during a wafer back grinding step, also known as wafer lapping, wafer thinning, backlap, or backfinish, as part of a process to form an electronic device, and methods of use thereof. More specifically, the present disclosure relates to an adhesive film for wafer back grinding that maximizes permeation (embeddability) of an adhesive layer of the adhesive film among device components/surface features that can form at least one bump on the device forming surface of the wafer, has an excellent wafer surface protection effect (buffering effect) during the back grinding step and reduces or eliminates the problem of adhesive residue that can be left on the wafer surface after the step of peeling the adhesive film from the wafer surface following the wafer back grinding. The subject adhesive films exhibit excellent processability.