Vacuum Pump Rotor Blade Reflection Structure for Particle Backflow
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Solution Overview
Problem
Conventional turbomolecular pumps face challenges in preventing particles from flowing back into the gas inflow side during semiconductor manufacturing, leading to contamination, as existing solutions either reflect particles back towards the inlet port or fail to effectively capture them due to design limitations that compromise exhaust performance.
Innovation Solution
A vacuum pump design featuring a rotor blade with a chamfered surface inclined at a predetermined angle and a reflection mechanism with inclined plates that re-reflect particles towards the downstream side, optimized using specific geometric formulas to minimize the size and impact on exhaust performance, while ensuring the particle is securely reflected and not re-collided with the previous blade.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the chamfered surface is opened wide at approximately 22.5 degrees to prevent burrs and facilitate assembly, then the ease of manufacture is improved, but particles are more likely to be bounced back toward the chamber causing contamination
Solution Approach 1:
The patent applies asymmetry by configuring the chamfered surface with unequal angles: the first angle (between the chamfered surface and horizontal surface) is set to 10-15 degrees while the second angle (between the chamfered surface and lower-side inclined surface) is set to 30-45 degrees. This asymmetric configuration prevents particles from being bounced back toward the chamber while maintaining ease of manufacture, resolving the contradiction between ease of assembly and particle backflow prevention.
2Object-affected harmful factors
If a reflection mechanism is added to prevent particle backflow, then particle contamination is reduced, but the device complexity increases
Solution Approach 1:
The reflection mechanism is applied locally only at the tip end portion of the rotor blade where particles most frequently collide, rather than throughout the entire blade structure. This localized application effectively prevents particle backflow while minimizing the increase in device complexity.
Solution Approach 2:
The reflection mechanism is designed as a separate, detachable component that can be independently installed and maintained, rather than integrating it into the main rotor blade structure. This segmentation reduces overall device complexity while maintaining particle prevention functionality.
3Object-affected harmful factors
If the chamfered surface angle is reduced to prevent particle backflow, then particle contamination is reduced, but the ease of manufacture deteriorates due to increased risk of burrs and assembly difficulties
Solution Approach 1:
The asymmetric angle configuration maintains a relatively small first angle (10-15 degrees) on the particle-facing surface to prevent backflow, while compensating with a larger second angle (30-45 degrees) on the rear surface to facilitate manufacturing and assembly, thus resolving the contradiction between particle prevention and ease of manufacture.
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
The solution effectively prevents particles from re-colliding with the previous blade, securely reflecting them towards the reflection mechanism, maintaining minimal impact on exhaust performance and reducing contamination risks in semiconductor manufacturing.
Implementation Method 1
the chamfered surface is inclined in an oblique upstream direction at a predetermined angle from an axial direction of a rotating body so that a particle colliding with the chamfered surface is reflected toward the reflection mechanism
Data Source
AI summary
A reflection mechanism is disposed above a rotor blade. A chamfered surface of the rotor blade is formed to gradually open wide by 0 to 10 degrees toward the downstream side in the rotational direction, from an imaginary line passing through a rotational direction-side tip end point of a horizontal surface and drawn parallel to a rotating shaft. In the reflection mechanism, inclined plates, inclined at a predetermined angle, are arranged radially in the radial direction from a central disc portion. A particle reflected on the chamfered surface of the rotor blade collides with each inclined plate of the reflection mechanism and is then re-reflected and falls in the downstream direction. Since the particle can securely be reflected toward the reflection mechanism, the particle can be prevented from exiting through an inlet port to flow back toward a chamber.