Semiconductor Chip Sidewall Hydrophobic Structure
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Solution Overview
Problem
Solder creepage during semiconductor chip attachment to carriers leads to contamination and degradation of the chip's sidewalls due to adhesion forces, as conventional die attach processes have narrow and fluctuating process windows, failing to effectively inhibit solder migration.
Innovation Solution
The semiconductor chip features sidewalls with a defined hydrophobic surface structure and a protective layer to prevent solder creepage, comprising a Bosch deep reactive-ion etching process for forming corrugated surfaces and a diffusion barrier to inhibit solder migration and contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional die attach processes are used with optimized process windows, then the amount of solder and force applied are minimized, but solder creepage still occurs due to narrow and fluctuating process parameters
Solution Approach 1:
The patent changes the physical-chemical parameters of the sidewall surface by forming a hydrophobic coating layer and creating micropatterned structures (such as pillars or grooves) on the sidewalls. This modifies the surface energy and wettability characteristics, preventing solder from adhering to and creeping up the sidewalls during the attachment process, thereby resolving the solder creepage issue without requiring strict process parameter optimization
2Strength
If soldering processes are used to attach semiconductor chips to carriers, then chips are securely bonded, but solder material creeps up the sidewalls causing contamination and degradation
Solution Approach 1:
The patent applies local quality modification by treating only the sidewall regions with hydrophobic coating and micropatterned structures, while leaving the bonding surfaces (front and back surfaces of the chip) unchanged. This localized treatment prevents solder creepage on the sidewalls without affecting the bonding strength at the contact surfaces, thus resolving the contradiction between strong bonding and contamination prevention
3Force
If force is applied to press chips onto liquid solder material, then secure attachment is achieved, but solder is squeezed out and travels up the sidewalls
Solution Approach 1:
The patent converts the harmful adhesion forces that cause solder to creep up the sidewalls into a beneficial hydrophobic effect. By applying hydrophobic coating and micropatterned structures, the sidewalls actively repel the solder material, transforming the previously harmful surface properties into a protective mechanism that prevents solder migration even under applied force
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 hydrophobic surface structure and protective layer significantly reduce solder creepage and contamination, enhancing the reliability and longevity of semiconductor chips by preventing solder migration and protecting the chip's active regions.
Implementation Method 1
at least a portion of each sidewall having a defined surface structure with hydrophobic characteristics to inhibit travel of a bonding material along the sidewalls
Implementation Method 2
Chemicals from the solder material (e.g. metals, flux agents) can diffuse into and contaminate the bulk semiconductor material on the chip sidewalls
Data Source
AI summary
A semiconductor chip includes a body having a frontside, a backside opposite the frontside, and sidewalls extending between the backside and frontside, at least a portion of each sidewall having a defined surface structure with hydrophobic characteristics to inhibit travel of a bonding material along the sidewalls during attachment of the semiconductor chip to a carrier with the bonding material.