Chuck Table Segmentation for Wafer Thickness Uniformity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional grinding apparatuses experience minute thickness variations (2-3 μm) in wafers due to non-uniformity in the shape of the frame body of the chuck table between the holding surface and the ground surface, which becomes problematic for thin wafers.
Innovation Solution
A processing apparatus with a chuck table mechanism that includes a porous plate with a suction surface and a frame body, where the frame body is securely fixed to a table base with independent suction holes for the frame body and wafer, ensuring the entire area of the frame body is grounded, matching the shape of the holding surface with the ground surface of the wafer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the frame body of the chuck table is used for both holding the wafer and as the grinding surface, then the structure is simplified, but the shape uniformity between the holding surface and ground surface cannot be maintained, causing thickness variations
Solution Approach 1:
The chuck table is divided into two separate components: a porous plate serving as the holding surface and a frame body serving as the support structure. This segmentation allows each component to be optimized independently - the porous plate can be precisely ground to match the wafer's holding surface while the frame body provides structural support, eliminating the shape non-uniformity problem that occurred when a single frame body served both functions.
Solution Approach 2:
The porous plate acts as an intermediary component between the frame body and the wafer. It transfers the suction force from the frame body to the wafer while maintaining a precisely controlled holding surface geometry. This intermediary allows the frame body to be optimized for structural purposes while the porous plate ensures precise wafer holding geometry, resolving the contradiction between structural simplicity and precision.
2Manufacturing precision
If the chuck table is securely fixed to the table base during grinding, then the shape uniformity between holding surface and ground surface is improved, but the suction force transmission to the wafer may be affected
Solution Approach 1:
The separation of the porous plate from the frame body creates independent functional zones. The frame body can be securely fixed to the table base during grinding operations to ensure shape uniformity, while the porous plate remains free to transmit suction forces to the wafer. This segmentation resolves the conflict between needing secure fixation for precision and maintaining suction force transmission reliability.
Solution Approach 2:
Different parts of the chuck table structure have different fixation requirements. The frame body requires secure fixation to the table base for maintaining geometric precision during grinding, while the porous plate requires minimal interference to maintain its suction functionality. The local quality principle allows each region to have the appropriate degree of fixation - the frame body is firmly fixed while the porous plate maintains its operational flexibility for reliable wafer holding.
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 configuration reduces thickness variations in the wafer by ensuring the grinding wheel processes the wafer and the chuck table's holding surface in a synchronized manner, maintaining uniformity across the wafer's surface.
Implementation Method 1
a porous plate having a suction surface that sucks the wafer
Implementation Method 2
a processing unit having, in a rotatable manner, a grinding wheel that grinds the wafer held by the holding unit
Implementation Method 3
a processing liquid supply unit that supplies a processing liquid to the wafer
Data Source
AI summary
A processing apparatus includes a chuck table mechanism including a chuck table configured to hold the wafer and a table base configured to support the chuck table in a detachable manner. The chuck table includes a porous plate having a suction surface that sucks the wafer, a frame body surrounding surfaces of the porous plate other than the suction surface of the porous plate, a wafer suction hole formed in the frame body and configured to transmit a suction force to the suction surface of the porous plate, and a bolt hole formed in the frame body and configured to fix the frame body to the table base.