Semiconductor Wafer Edge Roll-off Reduction via Oxide Film
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Solution Overview
Problem
The existing methods for manufacturing semiconductor wafers suffer from edge roll-off due to over-polishing during mirror polishing of the chamfered portion, which is exacerbated by the formation and removal of resin protection films, leading to increased costs and technical difficulties in precise film formation and removal.
Innovation Solution
Forming an oxide film with an angstrom-order thickness on the entire surface of the semiconductor wafer after chamfered portion mirror polishing, using chemical cleaning with a mixture of ammonia water and oxygenated water, and repeating spin cleaning with ozone water and hydrogen fluoride water, to ensure uniform coverage and prevent varying polishing rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a resin protection film is formed on the front and back surfaces to prevent over-polishing during chamfered portion mirror polishing, then edge roll-off is prevented, but manufacturing cost increases due to additional film formation and cleaning steps
Solution Approach 1:
The invention replaces the resin protection film with a water-soluble polymer coating that can be easily removed by rinsing with water. This disposable-like approach uses a cheap, easily removable protective layer that serves its purpose during polishing and then is simply washed away, eliminating the need for complex cleaning processes and reducing manufacturing costs while maintaining precision.
Solution Approach 2:
The invention changes the chemical properties of the protective coating from resin-based to water-soluble polymer-based. This parameter change in the coating material's solubility enables easy removal by water rinsing instead of requiring complex cleaning processes, thereby reducing process complexity while maintaining the protective function during polishing.
2Manufacturing precision
If a resin protection film is formed precisely only on the front and back surfaces, then over-polishing is prevented, but the formation process becomes technically difficult
Solution Approach 1:
The water-soluble polymer coating serves multiple functions: it protects the front and back surfaces during chamfered portion polishing, provides easy water-soluble removal, and can be applied uniformly across the entire wafer surface including the chamfered portion. This multi-functionality simplifies the manufacturing process while achieving the desired precision.
Solution Approach 2:
The coating is designed as a temporary, easily removable protective layer that is applied broadly and then simply rinsed away with water. This approach eliminates the need for precise, complex film formation processes while maintaining protection where needed, making the manufacturing process much easier.
3Manufacturing precision
If resin protection film is used, then over-polishing is suppressed, but cleaning to remove the resin is problematic as removed resin may stick to the surface again and the film may not be fully removed
Solution Approach 1:
The invention changes the chemical parameter of the protective coating from resin-based to water-soluble polymer-based. This fundamental parameter change in solubility ensures complete and reliable removal by water rinsing, eliminating the sticking and incomplete removal problems associated with resin films. The water-soluble coating dissolves completely without leaving residues that could re-adhere to the surface.
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 approach improves the flatness of the outer peripheral portion of the semiconductor wafer by maintaining a consistent polishing rate across the surface, reducing edge roll-off and enhancing surface roughness.
Implementation Method 1
a cleaning solution (SC-1) containing ammonia water and hydrogen peroxide is used
Implementation Method 2
an oxide film with an angstrom-order thickness is necessarily formed on the entire surface of the cleaned semiconductor wafer
Implementation Method 3
a polishing solution for rough polishing and a polishing solution for mirror finish polishing are usually different in abrasive grain size
Data Source
AI summary
A method of manufacturing a semiconductor wafer includes: rough-polishing front and back surfaces of the semiconductor wafer; mirror-polishing a chamfered portion of the rough-polished semiconductor wafer; performing mirror finish polishing on the front surface or both the front and back surfaces of the semiconductor wafer having the mirror-polished chamfered portion; and forming an oxide film on an entire surface of the semiconductor wafer after the mirror-polishing of the chamfered portion and before the mirror finish polishing.