Chuck Table Holder Surface Grinding for Wafer Flatness
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Solution Overview
Problem
The formation of a ring-shaped concavity on the outer periphery of a porous member during self-grinding of a chuck table leads to a slight convexity on the wafer, causing uneven grinding and potential damage.
Innovation Solution
A method involving two distinct grinding processes with different angles and grinding stones is employed to separate the grinding of the frame and porous member, preventing the formation of a ring-shaped concavity by adjusting the relative inclination between the chuck table and spindle axes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If self-grinding is performed on the chuck table with a single grinding process, then the grinding operation is simple and quick, but a ring-shaped concavity is formed on the porous member causing convexity on the wafer
Solution Approach 1:
The single grinding process is divided into two distinct grinding processes: a first grinding process that grinds the frame at a first angle, and a second grinding process that grinds the porous member at a second angle. This segmentation prevents the ring-shaped concavity by treating different materials with different grinding parameters, thereby maintaining surface flatness while preserving overall grinding efficiency.
Solution Approach 2:
The grinding angle between the spindle axis and chuck table axis is dynamically adjusted between the two grinding processes. The tilt-adjusting assembly changes the relative angle from the first angle to the second angle, allowing optimal grinding conditions for each material type (frame vs. porous member) and preventing differential grinding that causes concavity.
2Device complexity
If the porous member and frame are ground simultaneously at the same angle, then the grinding process is simple, but the porous member grinds ahead causing ring-shaped concavity
Solution Approach 1:
Different grinding angles are applied to different regions of the chuck table based on material properties. The frame is ground at a first angle while the porous member is ground at a second angle. This localized quality adjustment ensures each material is ground at its optimal angle, preventing the porous member from grinding ahead and forming concavity, while maintaining overall process simplicity.
3Ease of manufacture
If a single grinding angle is used for both frame and porous member, then the setup is simple and quick, but convexity is formed on the wafer outer periphery
Solution Approach 1:
The grinding system dynamically adjusts the spindle angle between the two grinding processes. The tilt-adjusting assembly enables quick angle changes from the first angle to the second angle, maintaining ease of manufacture through automated adjustment while achieving the precision required to prevent wafer convexity by grinding each material at its optimal angle.
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
Prevents the formation of convexities on the wafer, ensuring even thickness and reducing unevenness, thereby avoiding damage and improving grinding quality.
Implementation Method 1
grinding an upper surface of the chuck table with the grinding stone rotated along with the spindle
Data Source
AI summary
A method for forming a holder surface of a chuck table by rotating a spindle, to which an annular grinding stone is attached, and grinding an upper surface of the chuck table with the grinding stone rotated along with the spindle. The chuck table includes a porous member and a frame having a dense body in an annular shape. The method includes a first grinding process including tilting an axis of the chuck table with respect to an axis of the spindle relatively at a predetermined first angle and grinding an entire upper surface of the frame with the grinding stone, and a second grinding process including tilting the axis of the chuck table with respect to the axis of the spindle relatively at a second angle, which is smaller than the first angle, and grinding an entire upper surface of the porous member with the grinding stone.