Grinding Apparatus Height Gauge Placement
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Solution Overview
Problem
Conventional grinding apparatuses face challenges in accurately measuring wafer thickness due to thermal deformation and arm length issues, leading to compromised measurement accuracy.
Innovation Solution
The grinding apparatus incorporates a chuck table, a grinding unit with a spindle and annular grindstone, a grinding feeding mechanism, and height gauges disposed on the side plate of the holder within the grinding unit, allowing for precise measurement of wafer thickness by positioning measurement points near the processing region and enabling simultaneous movement of gauges with the grindstone.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the arm is lengthened to measure height at a position close to the processing region, then the measurement position can be closer to the processing region, but thermal deformation of the arm makes it difficult to accurately measure the thickness
Solution Approach 1:
The height gauges are extracted from the arm structure and relocated to the grinding unit. Specifically, the first height gauge is mounted on the holder and the second height gauge is mounted on the grinding unit, separating the measurement function from the positioning arm to eliminate thermal deformation effects on measurement accuracy
Solution Approach 2:
The holder and grinding unit serve as intermediary structures that carry the height gauges close to the processing region without being subject to the same thermal deformation issues as the arm. These intermediaries provide stable mounting positions for accurate measurement
2Object-affected harmful factors
If the arm is made short to avoid thermal deformation, then thermal deformation is reduced, but the height gauges cannot be positioned close to the processing region
Solution Approach 1:
The measurement system is segmented into two independent parts: the grinding unit (which moves close to the processing region) and the height gauges (mounted on stable structures). This segmentation allows the grinding unit to approach the wafer while the height gauges remain on thermally stable mounting positions
Solution Approach 2:
The holder acts as an intermediary that carries the first height gauge close to the processing region without being part of the thermally affected arm structure, enabling accurate measurement positioning
3Measurement precision
If the height gauges are positioned close to the processing region, then fine variations in wafer thickness can be accurately measured, but the gauges interfere with the processing region
Solution Approach 1:
The system is divided into functionally independent segments: the grinding unit with grindstone for processing, and the height gauges for measurement. This segmentation allows each component to perform its function without interfering with the other, even when positioned close to the processing region
Solution Approach 2:
The height gauges are positioned in a different spatial dimension relative to the grinding process. The first height gauge measures from the holder structure while the second height gauge measures from the grinding unit, utilizing vertical and horizontal spacing to avoid interference with the grindstone-wafer contact region
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 allows for accurate measurement of wafer thickness immediately after grinding starts, recognizes fine variations, and enhances maintenance operability by separating gauges from the wafer when not in use.
Implementation Method 1
a first height gauge that measures a height of the holding surface; a second height gauge that measures a height of an upper surface of the wafer held on the holding surface
Implementation Method 2
a calculation section that calculates a difference between the height of the holding surface measured by the first height gauge and the height of the upper surface of the wafer measured by the second height gauge, as a thickness of the wafer
Implementation Method 3
a grinding unit that has a spindle unit in which a spindle with an annular grindstone mounted to a tip thereof is rotatably supported and that grinds the wafer by use of the grindstone
Data Source
AI summary
A grinding apparatus includes a chuck table that holds a wafer on a holding surface; a grinding unit that has a spindle unit in which a spindle with an annular grindstone mounted to a tip thereof is rotatably supported and that grinds the wafer by use of the grindstone; a grinding feeding mechanism that puts the grinding unit into grinding feeding in a grinding feeding direction perpendicular to the holding surface; a first height gauge that measures the height of the holding surface; a second height gauge that measures the height of an upper surface of the wafer; and a calculation section that calculates the difference between the height of the holding surface and the height of the upper surface of the wafer, as the thickness of the wafer. In the grinding apparatus, the first height gauge and the second height gauge are disposed in the grinding unit.