Wafer Edge Cleaning With Gas Clusters in Vacuum Processing
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Solution Overview
Problem
The peripheral portion of semiconductor wafers experiences acute silicon irregularities and unwanted particle deposition during etching processes, which are difficult to remove using conventional plasma cleaning due to anisotropic plasma properties, leading to contamination and damage to the device area.
Innovation Solution
A substrate cleaning apparatus that uses nozzle units to eject gas clusters with higher pressure than the processing chamber, forming aggregates of atoms and/or molecules to remove unnecessary substances from the peripheral portion of the substrate without affecting the effective area, utilizing a vacuum processing system with a moving mechanism to precisely target and clean the peripheral region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If plasma cleaning is used to remove acute silicon irregularities, then cleaning is performed, but the cleaning is ineffective due to anisotropic property of plasma
Solution Approach 1:
The invention changes the physical state and properties of the cleaning medium from plasma to gas clusters. By using gas clusters instead of plasma, the anisotropic limitation is overcome while maintaining cleaning capability. The gas clusters are generated by adiabatic expansion of cleaning gas, creating a different interaction mechanism with the silicon surface that effectively removes acute irregularities.
2Manufacturing precision
If brush cleaning is used to scrape off protrusions, then mechanical removal is achieved, but the protrusions cannot be scraped off
Solution Approach 1:
The invention replaces the mechanical brush cleaning system with a gas cluster-based cleaning system. The gas clusters, generated through adiabatic expansion, provide the necessary mechanical impact to remove protrusions without requiring physical contact from brushes, thereby achieving effective removal while simplifying the cleaning mechanism.
3Manufacturing precision
If CMP is used to remove protrusions, then the protrusions are removed, but the wafer surface may be contaminated
Solution Approach 1:
The invention replaces CMP mechanical polishing with gas cluster cleaning. The gas clusters remove protrusions through controlled impact and chemical interaction without the mechanical contact that causes contamination in CMP processes. This substitution eliminates the contamination issue while maintaining the ability to remove acute silicon irregularities.
4Manufacturing precision
If dry cleaning with plasma is performed, then cleaning is achieved, but cleaning gas needs to be changed depending on materials and device area is damaged
Solution Approach 1:
The gas cluster cleaning system provides a universal cleaning mechanism that can handle multiple materials and deposit types without requiring changes in cleaning gas. The gas clusters effectively remove various contaminants including organic deposits, inorganic materials, and acute silicon irregularities through a single cleaning process, eliminating the complexity of selecting and switching between different cleaning gases.
5Manufacturing precision
If wet etching is performed to remove deposits, then deposit removal is achieved, but re-adhesion of removed deposit occurs
Solution Approach 1:
The invention replaces wet etching with gas cluster cleaning. The gas clusters remove deposits through physical impact and chemical interaction without leaving residues that could re-adhere. The cleaning process effectively eliminates deposits from the peripheral portion and prevents re-adhesion, avoiding the problems associated with wet etching.
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
Effectively removes needle-shaped protrusions and deposits from the wafer's peripheral area through physical and chemical action of gas clusters, preventing re-adhesion and minimizing contamination, while maintaining the integrity of the device area.
Implementation Method 1
the nozzle unit discharges a cleaning gas having a pressure higher than that in the processing chamber so that the cleaning gas is adiabatically expanded to form aggregates of atoms and/or molecules
Data Source
AI summary
A substrate cleaning apparatus includes a supporting unit, provided in a processing chamber having a gas exhaust port, for supporting a substrate; one or more nozzle units, each for ejecting gas clusters to a peripheral portion of the substrate supported by the supporting unit to remove unnecessary substances from the peripheral portion; and a moving mechanism for changing relative positions of the supporting unit and the nozzle unit during ejecting the gas clusters. Each nozzle unit discharges a cleaning gas having a pressure higher than that in the processing chamber so that the cleaning gas is adiabatically expanded to form aggregates of atoms and/or molecules.