Wafer Thinning Groove Profile to Prevent Edge Scrap Buildup
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Solution Overview
Problem
During the grinding of semiconductor wafers with chamfered portions, the outer peripheral portion of the trimmed wafer breaks, leading to scrap accumulation in the processing chamber, which hinders the discharge of processing water.
Innovation Solution
A processing method involving the formation of an annular groove on the wafer's surface, with a groove bottom that gradually approaches the back surface as it moves toward the outer peripheral edge, allowing for the removal of the remaining portion during grinding without generating scrap.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If edge trimming is performed to prevent edge chipping, then edge chipping is prevented, but scrap is generated and accumulates in the drain port
Solution Approach 1:
The chamfered portion is divided into multiple segments by forming grooves at predetermined intervals along the outer peripheral edge. This segmentation allows the chamfered portion to be removed in smaller pieces rather than as a single large scrap, preventing accumulation in the drain port while still preventing edge chipping.
Solution Approach 2:
The harmful chamfered portion that causes edge chipping is extracted and removed through groove formation and subsequent grinding. By taking out the chamfered portion in segmented form, the harmful effect is eliminated while the removed material is discharged as small particles rather than accumulating as scrap.
2Object-generated harmful factors
If a mechanism to crush scrap is added to suppress scrap accumulation, then scrap accumulation is suppressed, but device complexity increases
Solution Approach 1:
Instead of adding a mechanism to crush scrap, the invention converts the harmful chamfered portion into a beneficial feature by using it as a guide for groove formation. The chamfered portion is transformed from a problem source into a structural element that facilitates the removal process, eliminating scrap accumulation without additional complexity.
Solution Approach 2:
The processing method uses the existing chamfered portion and standard grinding equipment to achieve scrap suppression. The groove formation and grinding process automatically removes material in a controlled manner, with water flow naturally carrying away the removed particles, requiring no additional self-service mechanisms.
3Object-generated harmful factors
If the annular groove is formed with varying groove bottom position, then scrap generation is suppressed, but manufacturing precision requirements increase
Solution Approach 1:
The groove bottom position is varied locally according to the specific requirements of different wafer regions. The groove depth and position are adjusted based on the local chamfered portion characteristics, allowing optimal material removal while maintaining overall manufacturing feasibility without requiring uniform high precision throughout.
Solution Approach 2:
The groove formation parameters (depth, position, width) are changed along the outer peripheral edge to optimize scrap suppression. By varying these parameters progressively rather than maintaining fixed values, the method achieves effective chamfered portion removal while accommodating normal manufacturing tolerances.
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 method effectively suppresses the generation of scrap material during the grinding process, maintaining efficient processing water discharge without the need for a special processing device mechanism.
Implementation Method 1
bringing a grinding stone into contact with the second surface of the wafer and moving the grinding stone in the thickness direction of the wafer to grind the second surface side of the wafer
Data Source
AI summary
A processing method is for thinning a wafer formed with a chamfered portion on an outer periphery, and includes: forming an annular groove from the first surface side of the wafer along an outer peripheral edge of the wafer to a predetermined thickness and forming a remaining portion below the annular groove, the annular groove being formed so that a distance between a groove bottom and the second surface side of the wafer decreases from a center side of the wafer toward the outer peripheral edge side and a position of the groove bottom in a thickness direction of the wafer varies in a width direction; and bringing a grinding stone into contact with the second surface and moving the grinding stone in the thickness direction to grind the second surface side while crushing and removing the remaining portion, so as to thin the wafer to the predetermined thickness.