Wafer Grinding Layout for Intersecting Multi-Stage Grind Marks
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Solution Overview
Problem
Grinding apparatuses with three or more grinding mechanisms face difficulties in aligning marks produced by different mechanisms to extend across each other, leading to suboptimal grinding results.
Innovation Solution
A grinding apparatus with at least four chuck tables and three grinding mechanisms, where each mechanism is positioned to ensure that subsequent marks extend across previously ground marks, utilizing annular arrays of grindstones and rotatable turntables to achieve precise alignment and self-dressing of grindstones.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a grinding apparatus includes three or more grinding mechanisms, then the productivity is improved, but the manufacturing precision deteriorates because it is difficult to align marks from different mechanisms
Solution Approach 1:
The patent introduces a turntable dimension that rotates about a central axis, adding a rotational degree of freedom to the system. This allows multiple chuck tables to be positioned at different angular locations, enabling each grinding mechanism to create marks at specific angular positions that can be made to intersect on the wafer surface, thereby achieving mark alignment across multiple grinding mechanisms.
Solution Approach 2:
The patent employs asymmetric positioning of grinding mechanisms relative to the turntable, with each mechanism positioned at a specific angular offset. The first grinding mechanism is positioned at a reference angle, the second at a different angle, and the third at yet another angle, creating an asymmetric arrangement that enables their ground marks to intersect at controlled locations on the wafer, solving the alignment problem.
2Productivity
If multiple grinding mechanisms are used to increase productivity, then the device complexity increases, but the ease of operation deteriorates due to difficulty in positioning chuck tables
Solution Approach 1:
The turntable serves multiple functions: it holds multiple chuck tables, rotates to position them under different grinding mechanisms, and enables sequential processing of multiple wafers. This multi-functional design consolidates what would otherwise require separate positioning mechanisms for each chuck table, simplifying operation while maintaining high productivity.
Solution Approach 2:
The chuck tables are pre-positioned on the turntable at specific angular locations before the grinding process begins. This preliminary arrangement allows the control system to simply rotate the turntable to predetermined angles to bring each chuck table under the appropriate grinding mechanism, eliminating complex real-time positioning calculations and improving ease of operation.
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
The apparatus produces high-quality wafers with small thickness variations and high flexural strength by ensuring marks intersect correctly, and the self-dressing mechanism maintains and enhances the grinding capability of the grindstones.
Implementation Method 1
a first grinding mechanism for grinding the wafer held on the holding surface of one of the chuck tables by keeping lower surfaces of first grindstones arranged in an annular array in contact with a radial area of the wafer
Data Source
AI summary
A grinding apparatus includes a first grinding mechanism, a second grinding mechanism, and a third grinding mechanism for grinding wafers held on respective chuck tables. The first grinding mechanism and the second grinding mechanism are positioned with respect to the chuck tables such that a second ground mark produced on a wafer by second grindstones of the second grinding mechanism as it grinds the wafer extends across a first ground mark produced on the wafer by first grindstones of the first grinding mechanism as it grinds the wafer. The second grinding mechanism and the third grinding mechanism are positioned with respect to the chuck tables such that a third ground mark produced on the wafer by third grindstones of the third grinding mechanism as it grinds the wafer extends across the second ground mark produced on the wafer by the second grindstones.