Si Interposer Plasma Cleaning for NCF Adhesion in Flip Chip
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Solution Overview
Problem
In semiconductor device manufacturing using flip chip coupling, the prefabrication method with Non-Conductive Film (NCF) faces issues with adhesiveness between the substrate and NCF, leading to peeling and contamination during the baking process, especially with fine pitch bumps, which affects the quality and reliability of the device.
Innovation Solution
The method involves plasma-cleaning the surfaces of the chip support substrates and applying an insulative adhesive (NCF) before mounting the semiconductor chip, followed by reflow heating to ensure electrical coupling and improved adhesiveness, reducing contamination and peeling risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the prefabrication method with NCF is employed, then the manufacturing process can be simplified and productivity improved, but the adhesiveness between substrate and NCF deteriorates due to contamination during baking, causing peeling and reliability issues
Solution Approach 1:
The patent applies preliminary plasma cleaning to the substrate surface before applying the NCF adhesive. This preliminary action removes organic contaminants that would otherwise prevent proper adhesion during subsequent baking processes, ensuring the substrate surface is ready to bond with the NCF from the start of the manufacturing process.
Solution Approach 2:
The patent changes the physical-chemical state of the substrate surface by applying plasma treatment, which modifies surface energy and removes contamination. This parameter change in surface condition enables the NCF to achieve proper adhesiveness during baking without peeling, resolving the reliability issue while maintaining the productivity benefits of the prefabrication method.
2Strength
If the substrate is subjected to heat treatment during baking, then the NCF can be activated and bonded, but chemical substances are emitted and attach to the substrate, generating stains and deteriorating quality
Solution Approach 1:
Plasma cleaning is performed as a preliminary step before NCF application and baking. This removes the substrate surface of contaminants beforehand, preventing the staining issue that would otherwise occur during the necessary heat treatment and baking processes.
Solution Approach 2:
The patent uses plasma treatment to convert a potentially harmful process (heat treatment that causes contamination) into a beneficial outcome. By pre-cleaning the surface with plasma, the subsequent baking process can proceed without generating stains, as the surface is already in an optimal state for bonding without contamination.
3Adaptability or versatility
If the pitch between bumps is reduced to fine pitch, then the device functionality is improved, but the gap between chip and substrate becomes narrow, making resin infiltration difficult and the retrofitting method unsuitable
Solution Approach 1:
The NCF is applied to the substrate surface in advance, before the chip is mounted. This preliminary action allows the adhesive to be positioned and prepared on the substrate, ensuring proper placement even when the gap between chip and substrate is very narrow due to fine pitch bumps.
Solution Approach 2:
Instead of applying the adhesive after chip mounting (retrofitting method), the patent inverts the sequence by applying the NCF to the substrate first (prefabrication method). This inversion allows the adhesive to be properly positioned on the substrate surface, making the process suitable for fine pitch applications where post-mounting adhesive application would be difficult.
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 approach enhances the reliability and quality of semiconductor devices by improving adhesiveness and reducing contamination, allowing for efficient production with shorter tact times and lower manufacturing costs.
Implementation Method 1
plasma-cleaning an upper surface of a chip support substrate
Implementation Method 2
heating the chip support substrate mounted with the semiconductor chip and the insulative adhesive by reflow
Data Source
AI summary
A method for manufacturing a semiconductor device includes the steps of mounting a Si interposer over a printed wiring substrate, plasma-cleaning an upper surface of the Si interposer, disposing an NCF over the upper surface of the Si interposer, and mounting a semiconductor chip over the upper surface of the Si interposer through the NCF. Also, the method includes the step of electrically coupling each of plural electrodes of a second substrate and each of plural electrode pads of the semiconductor chip with each other through plural bump electrodes by reflow, and the surface of the Si interposer is plasma-cleaned before attaching the NCF to the Si interposer.