Wafer Transfer Stability After Peripheral Reinforcing Portion Removal
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Solution Overview
Problem
Thinned semiconductor wafers are difficult to handle due to reduced rigidity, leading to cracking and instability during processing, especially when transferring from a peripheral reinforcing portion removal process to chip division, as conventional methods lack reliable damage-free transfer solutions.
Innovation Solution
A processing method and apparatus that involves removing the projection of the peripheral reinforcing portion while holding the wafer on a table, applying a holding tape supported by a frame, and transferring the wafer with the frame to ensure stable handling and prevent damage during the transfer to the next process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the wafer is thinned to reduce semiconductor wafer thickness, then compactness and thinness of electronic apparatus are improved, but rigidity of the semiconductor wafer is decreased making it difficult to handle and prone to cracking
Solution Approach 1:
The invention applies local quality by creating a peripheral reinforcing portion with greater thickness only at the peripheral region of the wafer, while maintaining thin thickness in the central device region. This localized thickness variation provides enhanced rigidity at the periphery for handling stability without compromising the overall thinness requirement for compact electronic apparatus.
2Strength
If a protective tape is applied to provide rigidity to the thinned wafer, then rigidity is improved, but heat-resistance is insufficient requiring lower processing temperature and more time-consuming processing
Solution Approach 1:
The peripheral reinforcing portion provides localized rigidity enhancement without requiring protective tape. The inherent structural rigidity from the thicker peripheral region allows the wafer to withstand processing temperatures without the thermal limitations imposed by protective tape, enabling higher temperature processing and reduced processing time.
3Ease of operation
If the peripheral reinforcing portion is removed to allow stable holding on chuck table, then ease of operation is improved, but rigidity is reduced making damage more likely during transfer
Solution Approach 1:
The invention applies dynamics by making the holding table surface conformable to match the recessed rear surface shape of the wafer with peripheral reinforcing portion. This dynamic adaptation of the holding surface allows stable vacuum holding of wafers with non-planar rear surfaces, eliminating the need to remove the peripheral reinforcing portion while maintaining both holdability and rigidity.
4Ease of manufacture
If the wafer is held on holding table with rear surface exposed for peripheral reinforcing portion removal, then accessibility for processing is improved, but stable holding becomes difficult when peripheral reinforcing portion is present
Solution Approach 1:
The holding table surface is designed to be conformable, allowing it to adapt its shape to match the recessed rear surface of the wafer with peripheral reinforcing portion. This dynamic conformability maintains full contact between the holding table and wafer rear surface, providing stable vacuum holding while preserving complete accessibility of the rear surface for peripheral reinforcing portion removal processing.
Data Source
AI summary
A processing method for a wafer includes: preparing a wafer which has a device region having plural devices formed on a surface of the wafer; and a peripheral reinforcing portion which is integrally formed around the device region and has a projection projecting outwardly on a rear surface of the wafer. The processing method further includes: removing at least the projection of the peripheral reinforcing portion of the wafer; and transferring the wafer after the removing. In the removing, while the wafer is held on a holding table such that the rear surface of the wafer is exposed and the surface of the wafer closely contacts the holding table, at least the projection of the peripheral reinforcing portion is removed. After the removing of at least the projection, while the wafer is held on the holding table, a holding tape is applied to the rear surface of the wafer and the holding tape is supported by a frame. In the transferring, the wafer having the holding tape applied thereon is separated together with the frame from the holding table and is transferred together with the frame.