Semiconductor Die Singulation for Burr-Free Chip-on-Plastic Packaging
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Solution Overview
Problem
The existing methods for semiconductor die fabrication, particularly those using laser grooving, often result in conductive residues such as silicon debris or grooving burrs, which can cause undesired shorting issues during chip-on-plastic packaging, especially between display panel substrates and driver chips.
Innovation Solution
A fabrication method that incorporates plasma etching using oxygen and fluorine gases to remove the conductive residues generated by laser grooving, ensuring the interlayer insulating film thickness in the seal-ring region is less than in the semiconductor die region, thereby preventing shorting and improving the packaging process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If laser grooving is used to separate semiconductor dies, then cutting precision is improved, but conductive residues such as silicon debris or grooving burrs are generated causing shorting issues
Solution Approach 1:
The laser grooving process is divided into multiple passes with varying parameters. The first pass creates an initial groove, and subsequent passes complete the separation while minimizing residue generation through optimized pulse duration and power settings.
Solution Approach 2:
Laser processing parameters such as pulse duration, power, and frequency are dynamically adjusted during grooving. Lower pulse energies and shorter durations are used in final passes to vaporize material cleanly without generating excessive burrs or conductive residues.
2Ease of manufacture
If mechanical sawing is used to form individual semiconductor dies, then manufacturing simplicity is maintained, but cracking defects occur especially in low dielectric constant films
Solution Approach 1:
Laser grooving is performed as a preliminary step before mechanical sawing. This pre-cutting creates a controlled separation path that guides the mechanical blade, reducing stress concentration and preventing cracking in sensitive low dielectric constant films during the subsequent sawing process.
Solution Approach 2:
The laser-grooved channel acts as an intermediary structure between the intact wafer and fully separated dies. It provides a predetermined fracture path that reduces the mechanical stress required for separation, protecting vulnerable film layers from cracking.
3Productivity
If conductive residues are present on the silicon substrate, then packaging process continues, but electrical shorting occurs between display panel substrate and driver chip
Solution Approach 1:
Conductive residues such as silicon debris and grooving burrs are actively removed from the wafer surface through controlled laser vaporization and plasma cleaning processes. This extraction of harmful conductive materials prevents subsequent electrical shorting between the display panel substrate and driver chip during packaging.
Solution Approach 2:
The laser grooving process, which initially creates conductive residues as a harmful byproduct, is optimized to also vaporize and eject these residues during the cutting process. The same laser energy that separates the dies also cleans the cutting surface, converting the residue-generation mechanism into a self-cleaning process.
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 method effectively removes grooving burrs and debris, reducing the risk of electrical shorting and enhancing the reliability of chip-on-plastic packaging by ensuring a clean interface between the semiconductor die and the display panel substrate.
Implementation Method 1
exposing a semiconductor substrate of the wafer by removing the interlayer insulating film, using a laser light source
Implementation Method 2
plasma etching the wafer on which the laser grooving is performed
Data Source
AI summary
A semiconductor chip packaging method includes forming a bump on a wafer, forming a coating film covering the bump, laser grooving the wafer, plasma etching the wafer on which the laser grooving is performed, exposing the bump by removing the coating film covering the bump, fabricating a semiconductor die by performing mechanical sawing of the wafer, and packaging the semiconductor die.