Substrate Cleaning Back Surface Support Segmentation
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Solution Overview
Problem
Existing substrate cleaning technologies face challenges in effectively cleaning the back surface of semiconductor wafers without reversing the substrate, which can lead to wafer edge damage and contamination, and require additional space for wafer reversers, hindering the compactness of photolithography systems.
Innovation Solution
A substrate cleaning apparatus that supports the substrate from its back surface, using multiple supporting portions to clean and dry the back surface without reversing it, eliminating the need for a wafer reverser and preventing edge damage by ensuring comprehensive cleaning without mechanical edge holding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a wafer reverser is placed in the photolithography system to clean the back surface, then the back surface can be cleaned, but the system size increases due to additional space requirements
Solution Approach 1:
The cleaning apparatus is integrated into the photolithography system by utilizing the existing wafer transfer mechanism. The back surface cleaning function is merged with the wafer handling process, eliminating the need for a separate wafer reverser and reducing system size while maintaining cleaning effectiveness
Solution Approach 2:
The wafer transfer mechanism serves dual purposes: transferring wafers between process steps and enabling back surface cleaning. By making the cleaning apparatus compatible with the existing wafer handling infrastructure, the system achieves multi-functionality without increasing overall size
2Reliability
If the wafer is held at its edge by a mechanical chuck to clean the back surface, then cleaning can be performed, but the wafer edge may be damaged and the resist layer may be compromised
Solution Approach 1:
The cleaning apparatus uses a support table that contacts only the back surface of the wafer away from the edges, leaving the wafer edges and resist layer untouched. The cleaning elements are positioned to locally clean the back surface without affecting the sensitive front surface structures
Solution Approach 2:
A support table acts as an intermediary between the wafer and the cleaning mechanism. The support table provides stable backing for the wafer during cleaning while preventing direct mechanical contact between the chuck and wafer edges, thereby protecting the resist layer from damage
3Volume of stationary object
If the brush is disposed below the wafer to eliminate the reverser, then system size is reduced, but the wafer cannot be entirely cleaned since it is supported from below
Solution Approach 1:
The cleaning process is divided into multiple zones: the support table provides backing in the center area while allowing cleaning elements to access the back surface from below and the edges from the sides. This segmentation enables complete cleaning coverage without requiring wafer reversal
Solution Approach 2:
The cleaning approach transitions from a single-direction brush contact to multi-dimensional cleaning: the support table enables cleaning from below while side-mounted cleaning elements address the peripheral areas, achieving complete coverage through spatial arrangement rather than wafer reversal
Data Source
AI summary
A disclosed substrate cleaning apparatus for cleaning a back surface of a substrate includes a first substrate supporting portion configured to support the substrate at a first area of a back surface of the substrate, the back surface facing down; a second substrate supporting portion configured to support the substrate at a second area of the back surface of the substrate, the second area being separated from the first area; a cleaning liquid supplying portion configured to supply cleaning liquid to the back surface of the substrate; a drying portion configured to dry the second area of the back surface of the substrate; and a cleaning portion configured to clean a third area of the back surface of the substrate when the substrate is supported by the first substrate supporting portion, the third area including the second area, and a fourth area of the back surface of the substrate when the substrate is supported by the second substrate supporting portion, the fourth area excluding the second area of the back surface.