Wafer Thinning via Ring Reinforcement and Tape Protection
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Solution Overview
Problem
Thinly ground semiconductor wafers are prone to cracking during processing and division due to the impact of cutting blades, degrading device quality and making handling difficult.
Innovation Solution
A wafer processing method involving a protection tape to support the device area, forming a separation groove between the device and redundant areas, and grinding the rear surface to create a circular recessed portion with a ring-like reinforcing portion, allowing for safe thinning and handling of the device area without cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the wafer rear surface is ground thinly to achieve weight saving and downsizing, then the wafer thickness is reduced to approximately 50 μm, but the wafer becomes prone to breaking during conveyance and processing
Solution Approach 1:
The wafer is divided into a device area and an outer circumferential redundant area, with the latter forming a ring-like reinforcing portion that provides structural support while allowing the device area to be thinly ground for weight reduction
Solution Approach 2:
Different regions of the wafer are given different thicknesses: the device area is ground to approximately 50 μm for weight saving, while the outer circumferential redundant area is left thicker to form a reinforcing portion that provides mechanical strength and prevents breaking during handling
2Ease of manufacture
If a cutting blade is positioned at the boundary portion between the ring-like reinforcing portion and the device area to remove the reinforcing portion, then the wafer can be divided into individual devices, but the device area is cracked by the impact of the cutting blade
Solution Approach 1:
A protection tape is applied to the front surface of the wafer to act as an intermediary layer that absorbs and distributes the impact force of the cutting blade during separation, preventing direct transmission of impact to the device area and avoiding cracks
Solution Approach 2:
The protection tape is applied in advance before the cutting process, and the ring-like reinforcing portion is separated first while the device area remains protected by the tape, allowing subsequent removal of the reinforcing portion without risking damage to the thinly ground device area
Data Source
AI summary
A wafer processing method of processing a wafer having on a front surface a device area where a plurality of devices are formed by being sectioned by predetermined dividing lines, and an outer circumferential redundant area surrounding the device area, includes the steps of: sticking a protection tape to the front surface of the wafer; holding a protection tape side of the wafer by a rotatable chuck table, positioning a cutting blade on a rear surface of the wafer, and rotating the chuck table to cut a boundary portion between the device area and the outer circumferential redundant area to form a separation groove; grinding only the rear surface of the wafer corresponding to the device area to form a circular recessed portion to leave the ring-like outer circumferential redundant area as a ring-like reinforcing portion, the wafer being such that the device area and the ring-like outer circumferential redundant area are united by the protection tape; and conveying the wafer supported by the ring-like reinforcing portion via the protection tape.