Rotary Joint Vibration Control Using Spherical Plain Bearings
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Solution Overview
Problem
The existing polishing apparatuses for semiconductor wafers experience torsional vibration and abnormal sounds at the engagement part between the cooling water pipe and the polishing table, leading to potential fatigue failure and leakage due to sliding wear, which compromises the stability and efficiency of the polishing process.
Innovation Solution
A polishing apparatus with a rotary joint fixed to the polishing table or top ring, equipped with a rotation-prevention mechanism using a link mechanism comprising spherical plain bearings, which absorbs or lessens stick-slip vibrations and prevents rotation, thereby increasing the natural frequency of the rotary joint and reducing resonance with peripheral parts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a rotary joint is used to supply cooling water into the polishing table, then the cooling water can be delivered into the interior of the rotating polishing table, but torsional vibration is generated in the rotary joint and abnormal sound is generated at the engagement part between the cooling water pipe and the polishing table
Solution Approach 1:
A rotation-prevention mechanism is introduced as an intermediary component between the rotary joint and the polishing table. This mechanism includes a link mechanism with spherical plain bearings that act as mediators to absorb vibrations and prevent direct transmission of abnormal sounds while still allowing the cooling water supply function to operate.
Solution Approach 2:
The spherical plain bearings in the link mechanism provide beforehand cushioning by absorbing torsional vibrations and stick-slip phenomena before they can cause damage to the rotary joint or cooling water pipe. This preventive cushioning reduces the risk of fatigue failure and sliding wear.
2Device complexity
If the rotary joint is connected directly to the polishing table, then the structure is simple, but the natural frequency of the rotary joint resonates with peripheral parts causing torsional vibration
Solution Approach 1:
The connection between the rotary joint and the polishing table is segmented into multiple components: the rotary joint itself, the link mechanism, and the spherical plain bearings. This segmentation creates distinct functional elements that can be optimized independently, allowing the link mechanism to act as a vibration-isolating layer between the rotary joint and the polishing table.
Solution Approach 2:
The invention utilizes mechanical vibration principles by introducing the spherical plain bearings which can undergo micro-rotational movements to absorb and dissipate torsional vibrations. This vibration absorption mechanism shifts the natural frequency of the rotary joint assembly away from the resonant frequency of peripheral parts, eliminating the resonance condition.
3Stability of the object's composition
If the cooling water pipe is fixed to the polishing table, then the connection is stable, but sliding wear occurs at the engagement part leading to pipe damage and leakage
Solution Approach 1:
The spherical plain bearings serve as intermediary elements between the cooling water pipe and the polishing table. These bearings provide a stable connection that allows for micro-movements, preventing direct sliding contact and wear between the pipe and the polishing table while maintaining connection stability.
Solution Approach 2:
The connection system is made dynamic by allowing the spherical plain bearings to undergo micro-rotational movements. This dynamic capability enables the connection to adapt to thermal expansion, vibration, and other movements, preventing rigid sliding wear while maintaining stable connection throughout the operational life of the pipe.
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 ensures stable operation without torsional vibration and abnormal sounds, preventing pipe wear and maintaining consistent polishing performance by decoupling the rotary joint from the rotating members and enhancing the natural frequency difference with other parts.
Implementation Method 1
torsional vibration is generated in the rotary joint or an abnormal sound is generated at an engagement part between the cooling water pipe and the polishing table
Implementation Method 2
a rotation-prevention mechanism which connects the rotary joint with an apparatus frame to prevent the rotary joint from being rotated; wherein the rotation-prevention mechanism comprises a link mechanism having at least one spherical plain bearing
Implementation Method 3
a fluid passage for heat exchange medium is provided in the interior of the polishing table and cooling water serving as the heat exchange medium is flowed in the fluid passage to exchange heat between the heat exchange medium and the polishing table
Implementation Method 4
thermal deformation of the polishing table due to frictional heat during polishing is prevented
Implementation Method 5
a polishing liquid containing abrasive particles, such as silica (SiO2), ceria (CeO2) or the like, therein is supplied onto a polishing surface of a polishing pad, a substrate such as a semiconductor wafer is brought into sliding contact with the polishing surface and polished
Data Source
AI summary
A polishing apparatus which can continue stable operation of the apparatus without generating torsional vibration in a rotary joint and without generating an abnormal sound at an engagement part between a cooling water pipe and a polishing table is disclosed. The polishing apparatus includes a rotary joint fixed to a rotating part of the polishing table or a rotating part of the top ring to supply a fluid into the polishing table or the top ring and discharge the fluid from the polishing table or the top ring, and a rotation-prevention mechanism which connects the rotary joint with an apparatus frame to prevent the rotary joint from being rotated. The rotation-prevention mechanism includes a link mechanism having at least one spherical plain bearing.