Cryopump Thermal Shield Segmentation for Cooling Time
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Solution Overview
Problem
Conventional cryopumps face inefficiencies in cooling down time due to materials with high heat capacity, such as copper, and thermal conductivity issues with aluminum, leading to suboptimal vacuum formation in semiconductor manufacturing.
Innovation Solution
A cryopump with a thermal shield divided into multiple members, where the first member has higher thermal conductivity and the second member has lower heat capacity, optimizing thermal paths and reducing cooling down time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the first condensing panel is made of copper to improve thermal conductivity, then heat transfer efficiency is improved, but heat capacity increases leading to longer cooling down time
Solution Approach 1:
The thermal shield is divided into multiple members (first thermal shield member and second thermal shield member) with different materials. The first member uses copper for high thermal conductivity, while the second member uses aluminum for low heat capacity, thereby segmenting the thermal management functions to simultaneously achieve efficient heat transfer and rapid cooling.
Solution Approach 2:
Different regions of the thermal shield are assigned different material properties: the first thermal shield member positioned where high thermal conductivity is needed is made of copper, while the second member where lower heat capacity is beneficial is made of aluminum. This local differentiation optimizes both heat transfer efficiency and cooling speed in respective zones.
2Loss of time
If the first condensing panel is made of aluminum to reduce heat capacity, then cooling down time is reduced, but thermal conductivity decreases leading to poor temperature distribution
Solution Approach 1:
The thermal shield is segmented into multiple members with different materials. The first member uses copper for high thermal conductivity, while the second member uses aluminum for low heat capacity and rapid cooling, thereby distributing different material properties to different segments to overcome the limitations of using a single material.
Solution Approach 2:
The thermal shield employs a composite structure combining copper and aluminum members. This composite approach leverages the high thermal conductivity of copper and the low heat capacity of aluminum, achieving both efficient heat transfer and rapid cooling down that neither material could achieve alone.
3Ease of manufacture
If a single material is used for the first condensing panel to simplify manufacturing, then manufacturing complexity is reduced, but both thermal conductivity and cooling down time performance cannot be optimized simultaneously
Solution Approach 1:
Instead of using a single material for the entire thermal shield, the invention segments it into multiple members with different materials (copper and aluminum). This segmentation allows each member to be optimized for specific thermal properties while maintaining manufacturing feasibility through modular construction.
Solution Approach 2:
The thermal shield uses a composite structure of copper and aluminum members, combining the advantages of both materials. The copper member provides high thermal conductivity for efficient heat transfer, while the aluminum member provides low heat capacity for rapid cooling, together achieving superior vacuum formation efficiency.
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 enhances the efficiency of gas condensation and absorption, achieving a desirable vacuum state with reduced cooling down time and improved thermal management.
Implementation Method 1
The cryopump absorbs and condenses gas in the vacuum chamber on a cryogenic surface so that the vacuum state is formed
Implementation Method 2
activated carbon 59 is adhered to a part of the cryopanel 58. The activated carbon 59 absorbs gas such as hydrogen or helium
Implementation Method 3
the first member forms a thermal path between the first condensing panel and the cryocooler; the first member is made of a material having a thermal conductivity higher than a thermal conductivity of a material of the second member
Data Source
AI summary
A cryopump includes a thermal shield where a first condensing panel is provided; and a cryocooler connected to the thermal shield; wherein the thermal shield is divided into a plurality of members including a first member and a second member; the first member forms a thermal path between the first condensing panel and the cryocooler; the second member does not form the thermal path; the first member is made of a material having a thermal conductivity higher than a thermal conductivity of a material of the second member; and a material, having a heat capacity smaller than a heat capacity of the first member in a case where the heat capacity of the first member and the heat capacity of the second member are compared with each other under the conditions of the same volumes, is used as the material of the second member.