Wafer Level Chip Packaging Contamination Control
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Solution Overview
Problem
Existing wafer level packaging methods face contamination issues with semiconductor chips due to adhesive residue from films used in chip transfer processes, leading to decreased product yield and electrical properties.
Innovation Solution
A wafer level chip packaging method involving a carrier with a bonding layer and a dielectric layer, where semiconductor chips are attached face-down to the dielectric layer, packaged via injection molding, and the bonding layer is separated to form a redistribution layer and micro bumps, avoiding direct bonding and contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a film is used to transfer semiconductor chips in existing fan-out chip packaging technology, then chip transfer is enabled, but adhesive residue contaminates the semiconductor chip surface
Solution Approach 1:
A release film is introduced as an intermediary between the adhesive film and the semiconductor chip. The adhesive film bonds to the release film instead of directly to the chip, allowing the release film to be removed afterward and take the adhesive residue with it, leaving the chip surface clean.
Solution Approach 2:
The bonding function is segmented into two separate films: an adhesive film for bonding and a release film for protection and removal. This segmentation allows the adhesive residue to remain on the release film rather than contaminating the chip surface.
2Object-affected harmful factors
If redistribution layer is fabricated on silicon supporting substrate, then chip contamination by adhesive is prevented, but alignment accuracy requirements become extremely high
Solution Approach 1:
The release film is applied to the chip surface before the adhesive film is applied to the release film. This preliminary action protects the chip surface from adhesive contamination while allowing standard alignment tolerances to be used during subsequent bonding operations.
3Productivity
If multiple process steps are added for wafer level packaging, then packaging efficiency is improved, but process complexity increases
Solution Approach 1:
The release film application is merged with the existing adhesive film application process. Both films are applied in sequence during the same bonding operation, allowing the release film to serve dual purposes of protection and contamination prevention without requiring separate processing steps.
Data Source
AI summary
A wafer level chip packaging method, comprising: 1) providing a carrier and forming a bonding layer on a surface of the carrier; 2) forming a dielectric layer on a surface of the bonding layer; 3) attaching each of semiconductor chips, with its front face facing down, to a surface of the dielectric layer; 4) packaging each of the semiconductor chips by using an injection molding process; 5) separating the bonding layer and the dielectric layer to remove the carrier and the bonding layer; 6) forming a redistribution layer for the semiconductor chips based on the dielectric layer; and 7) performing a reballing reflow process on the redistribution layer to form micro bumps. As a result, contamination in the semiconductor chips from the packaging process is greatly controlled, thereby improving the rate of finished products and the electrical property of the semiconductor chips.