TSV Sidewall Smoothing via XeF2 and XeH2 Chemical Cleaning
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Solution Overview
Problem
Conventional methods for forming through-silicon via (TSV) openings in 3D integrated circuits result in scallop-like roughened sidewalls due to silicon particles and debris from laser ablation, impairing the step coverage of liner or barrier/seed layers and damaging electrical characteristics.
Innovation Solution
A method involving laser drilling to create TSV openings, followed by removal of recasts on sidewalls using a halogen-containing chemical like xenon difluoride (XeF2) and subsequent cleaning with a xenon dihydride (XeH2) to smooth the sidewalls and remove residuals, enhancing the step coverage of conductive structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If laser ablation is used to form TSV openings, then the openings can be created through the silicon substrate, but silicon particles and debris cause scallop-like roughened sidewalls that impair step coverage
Solution Approach 1:
A liner layer is deposited on the sidewalls of the TSV openings before the etching process to prevent silicon particles and debris from adhering to the sidewalls during laser ablation, thereby maintaining sidewall smoothness while enabling efficient opening formation
Solution Approach 2:
The patent utilizes the laser ablation process that creates roughened sidewalls as a known phenomenon, and converts the harmful effect by introducing a liner layer that prevents debris adhesion, thereby transforming the rough sidewall condition into an opportunity for controlled liner deposition that ultimately improves step coverage
2Ease of manufacture
If conventional etching is used to form TSV openings, then material removal can be achieved, but recasts form on sidewalls that damage electrical characteristics
Solution Approach 1:
A liner layer is deposited on the sidewalls before the etching process to prevent recast material from forming and adhering to the sidewalls during material removal, thereby maintaining electrical characteristics while enabling effective TSV opening formation
Solution Approach 2:
The liner layer acts as an intermediary barrier between the etching process and the sidewalls, preventing direct contact between recast material and the sidewall surface, thereby protecting electrical characteristics while allowing conventional etching to proceed
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 method effectively smooths sidewalls, improving the step coverage and electrical characteristics of conductive structures within TSV openings, thereby enhancing the performance of 3D integrated circuits.
Implementation Method 1
uses a laser ablation to remove silicon material of a silicon substrate, forming the TSV opening
Implementation Method 2
removal of recasts on sidewalls using a halogen-containing chemical like xenon difluoride (XeF2)
Implementation Method 3
subsequent cleaning with a xenon dihydride (XeH2) to smooth the sidewalls and remove residuals
Data Source
AI summary
A method includes forming an opening in a substrate, and the opening completely extends through the substrate. A recast material is formed on sidewalls of the substrate exposed by the opening. A first chemical is applied in the opening to remove the recast material, wherein a residue of the first chemical remains on portions of the sidewalls after the applying of the first chemical. Moreover, A second chemical is applied in the opening to remove the residue of the first chemical, and the second chemical is different from the first chemical.