Multilayer Sample Stage Thermal Uniformity in Plasma Processing
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Solution Overview
Problem
Conventional plasma processing apparatuses face challenges in achieving uniform temperature control and processing accuracy due to non-uniform heat transfer distributions caused by internal structural features, such as refrigerant flow paths and power supply paths, leading to deviations in wafer temperature and reduced processing yield.
Innovation Solution
A plasma processing apparatus with a multilayer sample stage structure, featuring a lower layer of high thermal conductivity material for the refrigerant flow path and an upper layer of lower thermal conductivity, along with insulating bosses in through-holes to enhance heat transfer and reduce thermal expansion differences, ensuring uniform heat distribution and improved temperature control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a refrigerant flow path is disposed inside a metallic base material to control wafer temperature, then temperature control capability is improved, but non-uniform heat transfer distribution occurs due to internal structure influences
Solution Approach 1:
The patent applies local quality by creating a multilayer base material structure where different regions have different thermal conductivities. The lower layer has high thermal conductivity for overall heat distribution, while the upper layer has low thermal conductivity to prevent localized heat loss. This spatial variation in material properties ensures uniform heat transfer distribution across the wafer surface, resolving the non-uniformity caused by the refrigerant flow path structure.
2Ease of operation
If through-holes are created for lift pins to move the wafer, then wafer mobility is improved, but heat transfer non-uniformity worsens due to structural interruptions
Solution Approach 1:
The patent introduces insulating bosses as intermediary components that fill the through-holes created for lift pins. These bosses serve as thermal mediators that maintain the thermal field uniformity by preventing excessive heat loss through the pin holes, while still allowing mechanical passage for wafer movement. This resolves the contradiction between wafer mobility and heat transfer uniformity.
3Device complexity
If a single-layer base material is used for simplicity, then device complexity is reduced, but temperature control precision deteriorates due to thermal expansion differences
Solution Approach 1:
The patent employs composite materials by constructing the base material as a multilayer structure with different thermal conductivities. The lower layer uses high thermal conductivity material for efficient heat distribution, while the upper layer uses low thermal conductivity material to prevent localized heat loss. This composite structure enables precise temperature control and reduces thermal expansion differences, improving temperature control accuracy despite increased structural complexity.
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 suppresses non-uniformity in heat transfer and temperature distribution across the wafer, enhancing processing accuracy and yield by optimizing heat management and thermal resistance within the sample stage.
Implementation Method 1
a lower layer which is made of a material having a relatively high thermal conductivity and has a refrigerant flow path through which a refrigerant for cooling the base material flows
Implementation Method 2
an upper layer which is made of a material having a relatively low thermal conductivity and is connected to the lower layer above the lower layer
Implementation Method 3
a refrigerant flow path through which a refrigerant for cooling the base material flows
Data Source
AI summary
A plasma processing apparatus including: a processing chamber; a sample stage; a vacuum exhaust unit; and a plasma generation unit, the sample stage includes: a first metallic base material having a refrigerant flow path formed therein; a second metallic base material disposed above the first metallic base material and has a lower thermal conductivity than the first metallic base material; and a plurality of lift pins vertically moving the object to be processed with respect to the sample stage. A plurality of through-holes through which the plurality of the lift pins passes is formed in the first and the second metallic base material, and a boss, which electrically insulates the lift pin from the first and the second metallic base material and is formed using an insulating member having a higher thermal conductivity than the second metallic base material, is inserted into each of the plurality of through-holes.