Semiconductor Wafer Ring Cutting Prevents Triangular Chipping
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Solution Overview
Problem
The TAIKO process for thinning semiconductor wafers leads to triangular chipping and cracking during ring cutting of the outer periphery, which reduces manufacturing yield and introduces defects in the remaining wafers.
Innovation Solution
A method involving a semiconductor wafer with a pattern prohibiting region and a dummy region, where the protective film covering conductive patterns is positioned such that the distance from the outer periphery to the protective film is greater than to the conductive patterns, and the ring cutting is performed between the inner peripheral end of the edge portion and the pattern prohibiting region, avoiding the generation of gaps that could damage the dicing blade.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the TAIKO process is used to thin the semiconductor wafer by grinding only the inner portion, then warpage is reduced and wafer strength is maintained, but triangular chipping occurs in the outer periphery during ring cutting which triggers cracks
Solution Approach 1:
The patent applies preliminary action by forming a protective film on the top surface of the semiconductor wafer before the ring cutting process. This protective film is positioned to extend beyond the conductive pattern edges, creating a buffer zone that prevents the dicing blade from directly contacting and chipping the wafer edge during cutting. The protective film is prepared in advance to anticipate and prevent the harmful chipping effect.
Solution Approach 2:
The protective film serves as an intermediary between the dicing blade and the semiconductor wafer edge. During ring cutting, the protective film absorbs the mechanical stress and contact from the dicing blade, preventing direct interaction between the blade and the wafer edge that would cause triangular chipping. This intermediary layer protects the wafer while allowing the cutting process to proceed.
2Loss of substance
If the protective film is positioned close to the conductive pattern to minimize material, then manufacturing cost is reduced, but gaps form during cutting that damage the dicing blade and cause chipping
Solution Approach 1:
The patent applies local quality by positioning the protective film with different extents in different regions. The protective film extends beyond the conductive pattern edges in the outer peripheral region where cutting occurs, providing enhanced protection. In the inner device region, the protective film coverage can be minimized. This localized differentiation optimizes both protection and material usage.
Solution Approach 2:
The protective film is positioned in advance with a predetermined extension beyond the conductive pattern edges, anticipating the cutting path of the dicing blade. This preliminary positioning ensures that when cutting occurs, the protective film is already in place to prevent gap formation and blade damage, eliminating the need for reactive measures during the cutting process.
3Ease of manufacture
If ring cutting is performed to remove the edge portion, then the outer peripheral excessive region is removed, but triangular chipping occurs at the cut surface which triggers cracks in the remaining wafer
Solution Approach 1:
The protective film acts as an intermediary that interfaces between the dicing blade and the wafer during ring cutting. By positioning the protective film to extend beyond the conductive pattern edges, it absorbs the mechanical interaction during cutting, preventing triangular chipping at the cut surface. This maintains high manufacturing precision while allowing the ring cutting process to proceed easily.
Solution Approach 2:
The protective film provides beforehand cushioning by being positioned to extend beyond the conductive pattern edges before cutting occurs. This creates a cushioning layer that absorbs the impact and stress of the dicing blade during ring cutting, preventing triangular chipping and crack initiation at the cut surface. The cushioning effect is prepared in advance to mitigate the harmful effects of cutting.
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 prevents triangular chipping and cracking in the semiconductor wafers, enhancing manufacturing yield by ensuring precise cutting and reducing damage to the dicing blade, thereby improving the reliability of the semiconductor device production process.
Implementation Method 1
a semiconductor substrate forming the semiconductor wafer is ground from the rear surface thereof to thin the semiconductor substrate inner than the edge portion
Data Source
AI summary
A semiconductor wafer provided with a pseudo chip between a product chip and a pattern prohibiting region is prepared. With the edge portion of the semiconductor wafer left, the bottom surface of the inner semiconductor substrate is ground, and then, the semiconductor wafer is cut in a ring shape to remove the edge portion. Here, in the pseudo chip, a protective film covering the conductive pattern is formed on the top surface of the semiconductor substrate and the end surface of the protective film facing the pattern prohibiting region is positioned on the conductive pattern. Further, in plan view, the inner peripheral end of the edge portion is positioned in the pattern prohibiting region, and the pattern prohibiting region between the inner peripheral end of the edge portion and the pseudo chip is cut in a ring shape.