Quartz Sensor Holder for Double-Side Polishing Thermal Stability
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Solution Overview
Problem
Conventional double-side polishing apparatuses face challenges in achieving precise wafer thickness due to thermal expansion of sensor holders, leading to deviations in sensor position and polishing accuracy.
Innovation Solution
The use of a quartz sensor holder with a low linear expansion coefficient, combined with water cooling, to inhibit thermal expansion and maintain accurate sensor position, ensuring precise wafer thickness detection and reduced deviations from target thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a metal sensor holder is used to hold the sensor, then the sensor can be securely mounted, but thermal expansion occurs during polishing causing sensor position deviation
Solution Approach 1:
The patent changes the material parameter of the sensor holder from metal to quartz, which has a dramatically lower thermal expansion coefficient. This parameter change eliminates thermal expansion during polishing, maintaining sensor position accuracy while still providing secure mounting capability.
Solution Approach 2:
The patent uses quartz as the sensor holder material, which can be considered a composite or engineered material solution. Quartz provides both the mechanical strength needed for secure sensor mounting and the thermal stability required to prevent expansion during the polishing process.
2Object-affected harmful factors
If the sensor holder is made smaller than the through-hole to avoid contact, then direct contact with the turn table is prevented, but heat conduction from the turn table still affects the sensor holder
Solution Approach 1:
The patent changes the thermal parameter of the sensor holder material from metal to quartz. This parameter change fundamentally alters the heat conduction characteristics, reducing heat transfer from the turn table and maintaining sensor position stability even when in contact through the through-hole.
3Productivity
If polishing time is calculated based on previous batch polishing speed, then the process is simple and fast, but actual polishing rate varies causing thickness deviation from target
Solution Approach 1:
The patent implements a feedback mechanism by using a sensor to continuously measure the actual wafer thickness during polishing. This real-time feedback allows the system to monitor and adjust the polishing process, ensuring the final thickness matches the target specification while maintaining efficient production.
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 approach significantly reduces sensor position deviations and improves polishing precision, allowing for accurate detection and achievement of target wafer thickness, as demonstrated by reduced differences in experimental results.
Implementation Method 1
heat generated during polishing is transferred from the upper turn table to the sensor holder, the sensor holder is expanded and contracted
Implementation Method 2
heat generated during polishing is transferred from the upper turn table to the sensor holder
Data Source
AI summary
A double-side polishing apparatus including at least: upper and lower turn tables each having a polishing pad attached thereto; a carrier having a holding hole formed therein for holding a wafer between the upper and lower turn tables; a sensor for detecting a thickness of the wafer during polishing, the sensor being disposed in a through-hole provided at the upper turn table in a direction of an upper-turn-table rotation axis; and a sensor holder for holding the sensor, wherein a material of the sensor holder is quartz. As a result, there is provided a double-side polishing apparatus that can polish a wafer while the difference from the target wafer thickness is reduced by surely inhibiting deformation of the sensor holder due to the influence of heat generated during the polishing of the wafer.