Wafer Edge Cleaning with Gas Barrier and Rotating Brush
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Solution Overview
Problem
Current wafer cleaning techniques fail to effectively remove unwanted residual materials from the edge and bevel regions of wafers, leading to defects and reduced yield in integrated circuit devices due to particle flaking and line collapses.
Innovation Solution
A wafer cleaning apparatus and process utilizing a rotating cleaning brush with a liquid stream and gas stream to scrub and rinse the edge and bevel regions, preventing liquid from reaching sensitive areas and enhancing cleaning efficiency with adjustable nozzles and rotating speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If standard cleaning techniques are used, then the wafer surface is cleaned, but particles on the edge of the wafer are difficult to remove
Solution Approach 1:
The cleaning system is segmented into multiple independent components: a rotating brush for mechanical scrubbing, a liquid stream nozzle for chemical cleaning, and a gas stream nozzle for drying. Each component targets specific regions (edge, bevel, or work piece region) independently, allowing optimized cleaning of the edge region without compromising other areas.
Solution Approach 2:
Different cleaning mechanisms are applied to different regions of the wafer: the rotating brush with liquid stream targets the edge and bevel regions for intensive mechanical and chemical cleaning, while the gas stream is directed at the work piece region for gentle drying. This localized approach ensures effective particle removal from edges without affecting the integrity of circuit features.
2Productivity
If liquid stream is used to clean the wafer edge, then cleaning efficiency is improved, but liquid may reach sensitive areas causing line collapses
Solution Approach 1:
The liquid stream delivery system is segmented and spatially separated from the gas stream delivery system. The liquid stream nozzle is positioned to target only the edge and bevel regions, while the gas stream nozzle is positioned to protect the work piece region. This segmentation prevents liquid from reaching sensitive areas while maintaining cleaning efficiency in target zones.
Solution Approach 2:
The gas stream acts as an intermediary protective barrier between the liquid stream cleaning process and the sensitive work piece region. The gas stream flows over the work piece region to prevent liquid droplets from reaching and damaging circuit features, while still allowing the liquid stream to effectively clean the edge regions.
3Productivity
If the wafer is rotated at high speed, then cleaning coverage is improved, but particles may flake off to the work piece region
Solution Approach 1:
The gas stream is activated before and during the high-speed rotation phase to create a protective airflow barrier. This preliminary action prevents particles that become dislodged during high-speed cleaning from migrating to the work piece region, as the gas stream captures and removes them before they can contaminate sensitive areas.
Solution Approach 2:
The high-speed rotation, which initially causes particles to flake off, is converted into a benefit by the gas stream system. The centrifugal force from rotation effectively distributes cleaning action across the entire edge region, while the gas stream captures the resulting particles and prevents their migration, transforming the harmful particle migration into an effective cleaning mechanism.
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 solution achieves thorough cleaning of the wafer edges and bevel regions, preventing line collapses and device defects while reducing costs by minimizing liquid usage and protecting the integrity of integrated circuits.
Implementation Method 1
a first nozzle is configured to deliver a first liquid stream on the cleaning brush
Implementation Method 2
rinsing and contacting the edge of the wafer with the cleaning brush
Implementation Method 3
a second nozzle is configured to deliver a second gas stream over the front side of the wafer to blow drops of liquid off the wafer
Implementation Method 4
contacting the edge of the wafer with the cleaning brush
Implementation Method 5
scrub and rinse the edge and bevel regions
Data Source
AI summary
A process and apparatus for cleaning a wafer, the wafer having a front side and a back side, are provided. The process begins with placing the wafer on a platform, and a first gas stream delivering in a direction from a center to an edge of the front side of the wafer. The first gas stream prevents liquid drops entering a work piece region on the front side of the wafer and protects the integrity of the integrated circuits. A cleaning brush is rinsed by a first liquid stream and contacting the edge of the wafer for cleaning the wafer. The cleaning brush scrubs unwanted residual materials from the edge of the wafer, and the first liquid stream flushes the cleaning brush to recover the cleaning ability.