Turbo-molecular pump stator temperature control
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Solution Overview
Problem
Turbo-molecular pumps in semiconductor manufacturing face challenges with rotor blade temperature exceeding allowable limits due to high gas discharge, leading to premature contact between moving and stationary blades, and reaction product accumulation on screw stators, which can cause rotor stator sticking and reduced pump life.
Innovation Solution
A turbo-molecular pump design incorporating a cooling spacer with a heat transfer ring and base cooling passage, along with a heat insulation member and a controller to regulate the temperature of the stator and prevent reaction product accumulation, using a heat-resistant section to suppress heat transfer between rotor blades and spacers, and a heat source to maintain the auxiliary ring at a temperature higher than the sublimation temperature of reaction products.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the pump case is cooled to cool stationary blades, then the stationary blades are cooled, but the cooling capacity is insufficient when gas flow amount increases
Solution Approach 1:
The cooling system is segmented into multiple independent cooling water passages: a first cooling water passage for cooling the pump case and stationary blades, a second cooling water passage for cooling the base, and a third cooling water passage for cooling the screw stator. This segmentation allows each passage to be optimized for its specific cooling target, enabling sufficient cooling capacity even when gas flow amount increases and heat generation rises.
2Object-affected harmful factors
If the base temperature is regulated high to prevent reaction product accumulation on screw stator, then reaction product accumulation on screw stator is prevented, but heat flows to pump case inhibiting cooling of stationary blades
Solution Approach 1:
The cooling system is divided into separate cooling water passages: the first cooling water passage cools the pump case and stationary blades, while the second cooling water passage cools the base. This segmentation allows independent temperature control of each component, enabling the base to be maintained at a high temperature to prevent reaction product accumulation while the pump case and stationary blades are cooled separately.
Solution Approach 2:
Heat insulation members are introduced as intermediaries between the base and the pump case/stationary blades. These heat insulation members block the unwanted heat flow from the high-temperature base to the stationary blades, allowing the base to be heated for reaction product prevention while the stationary blades remain cool for efficient operation.
3Temperature
If the cooling temperature is lowered to cool stationary blades, then stationary blades are cooled, but reaction product accumulates on spacer inner side
Solution Approach 1:
The cooling system is segmented into multiple independent passages that can be controlled separately. The first cooling water passage cools the pump case and stationary blades, while the third cooling water passage specifically cools the screw stator. This allows the screw stator to be maintained at a temperature that prevents reaction product accumulation, while the stationary blades are cooled independently.
Solution Approach 2:
Different temperature conditions are applied to different locations: the screw stator is maintained at a higher temperature to prevent reaction product accumulation, while the stationary blades are cooled to lower temperatures for efficient operation. This local quality differentiation resolves the contradiction between cooling requirements and reaction product prevention.
4Temperature
If cooling water passage is provided on outer peripheral surface of pump case, then pump case is cooled, but heat from base flows to pump case reducing cooling effectiveness
Solution Approach 1:
Heat insulation members are introduced as intermediaries between the base and the pump case. These heat insulation members block the unwanted heat flow from the base to the pump case, allowing the first cooling water passage to effectively cool the pump case without being counteracted by heat influx from the base.
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 design effectively cools the spacers and regulates the stator temperature, preventing reaction product accumulation and reducing the risk of blade contact, thereby increasing the exhaust flow amount and extending pump life by maintaining the rotor at a lower temperature and preventing reaction product accumulation on the spacers.
Implementation Method 1
a first cooling water passage which cools rotor blades by cooling a pump case
Implementation Method 2
released into cooling water in a cooling pipe provided in the base
Implementation Method 3
a device for regulating the temperature of a screw stator (a heater and a second cooling water passage)
Implementation Method 4
heat insulation members arranged between the base and the pump case
Data Source
AI summary
A turbo-molecular pump comprises: a rotor having a plurality of stages of rotor blades and a cylindrical section; a plurality of stages of stationary blades alternately arranged with respect to the rotor blades; a stator arranged with a gap from the cylindrical section, the stator together with the cylindrical section constituting a screw groove pump section; a plurality of spacers stacked on a base, the spacers including at least one cooling spacer having a cooling section; a heater heating the stator; a temperature regulation section controlling the heater to regulate the temperature of the stator so as to be a reaction product accumulation prevention temperature; and an auxiliary ring for reaction product accumulation prevention at least a part of which is located in a space between the spacer facing a bottom step rotor blade, and the bottom step rotor blade.