Turbomolecular Pump Mesh Particle Trap
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Solution Overview
Problem
Existing turbomolecular pumps fail to effectively trap recoil particles, leading to reduced semiconductor production yield due to reverse flow of particles into the vacuum chamber, and previous solutions like small chambers or capture members result in significant reduction of evacuation speed.
Innovation Solution
A turbomolecular pump design featuring a cylindrical mesh structure made of interlaced fine wires, combined with a circular disk and plate-shaped mesh structures, effectively captures recoil particles without significantly reducing evacuation speed by preventing their return to the vacuum chamber.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a small chamber or capture member (rubber, sponge, cotton, felt) is provided to capture particles, then particle trapping is improved, but sufficient trapping cannot be achieved and device complexity increases
Solution Approach 1:
The patent employs a mesh structure made of interlaced wires forming a porous configuration. This mesh structure is disposed between the inlet opening and the rotor, allowing it to capture recoil particles through its porous geometry while maintaining a relatively simple overall structure compared to solid capture members.
Solution Approach 2:
The patent introduces a circular disk positioned close to the rotor on the inlet opening side, arranged to oppose a surface on the rotor more radially inward than the root portion of rotating blades. This adds a dimensional element that redirects particles toward the mesh structure, enhancing trapping effectiveness without significantly increasing complexity.
2Reliability
If a circular plate shaped capture member is provided near the inlet opening, then particle capture is improved, but evacuation speed is significantly reduced
Solution Approach 1:
The mesh structure's porous nature allows gas molecules to pass through while intercepting particles. The interlaced wire configuration provides sufficient particle capture without forming a solid barrier that would impede gas flow and reduce evacuation speed.
Solution Approach 2:
The mesh structure provides partial coverage rather than a complete solid barrier, allowing gas flow to proceed while particles are captured where the mesh intercepts them. This partial action maintains evacuation performance while achieving sufficient particle capture.
Data Source
AI summary
A turbomolecular pump includes: a rotor (30) formed with rotating blades (32) in a plurality of stages, and rotating at high speed; a plurality of fixed blades (33) arranged along axial direction of the pump so as to alternate with respect to the rotating blades (32); a pump housing (34) containing the rotating blades (32) and the fixed blades (33), and formed with an inlet opening (21a); a circular disk (150), provided close to the inlet opening of the rotor (30), and arranged so as to oppose a surface of the rotor (30) radially inward than a root portion of the rotating blades; and a cylindrical mesh structure (153a, 153b), disposed between the inlet opening (21a) and the rotor (30), and made by interlacing fine wires. Particles that strike the rotor and bounce off are captured internally in the mesh structure (153a, 153b).