Electrostatic Chuck Focus Ring Temperature Uniformity
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Solution Overview
Problem
In plasma etching processing apparatuses, temperature differences between the focus ring and the silicon wafer lead to non-uniform etching results, and existing temperature control methods struggle to maintain stable temperatures, causing uneven etching characteristics and deposit formation on the focus ring.
Innovation Solution
An electrostatic chuck apparatus with an annular focus ring section, a ceramic plate, a non-magnetic heater section, and an electrode to supply electricity to the heater, which maintains constant temperature of the focus ring, stabilizes the outer periphery of the silicon wafer, and prevents deposits by accurate temperature adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a focus ring is added to equalize etching characteristics, then etching uniformity is improved, but temperature difference between center and periphery is generated
Solution Approach 1:
The focus ring is designed with non-uniform thickness to create different thermal capacities in different regions. The varying thickness allows the ring to store and release heat at different rates across its circumference, compensating for the temperature difference between the wafer center and periphery during plasma processing.
Solution Approach 2:
The invention changes the physical parameter of the focus ring by varying its thickness. This parameter change enables the focus ring to have different thermal masses in different locations, which directly addresses the temperature uniformity issue during etching operations.
2Stability of the object's composition
If temperature control is attempted during plasma irradiation, then temperature stability is improved, but temperature rising rate difference between focus ring and wafer causes control difficulty
Solution Approach 1:
The focus ring is pre-heated before plasma irradiation begins. This preliminary heating action ensures that the focus ring reaches an appropriate temperature ahead of time, reducing the temperature differential that develops during plasma processing and simplifying the temperature control requirements.
Solution Approach 2:
The focus ring maintains continuous heat storage and release functionality throughout the plasma processing cycle. Its thermal mass continuously compensates for temperature variations, providing ongoing temperature stabilization without requiring complex active control mechanisms.
3Object-generated harmful factors
If focus ring temperature is not controlled, then deposits form on the focus ring, but etching uniformity cannot be maintained
Solution Approach 1:
By changing the temperature parameter of the focus ring through controlled heating, the ring's surface conditions are optimized to prevent deposit formation. The elevated temperature reduces adhesion of deposited materials while maintaining the thermal compensation function for etching uniformity.
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 ensures uniform etching characteristics across the silicon wafer's plane, stabilizes the temperature of the focus ring, and prevents deposits from forming on the focus ring, thereby enhancing the yield and quality of semiconductor devices.
Implementation Method 1
a heater section which is provided between the ceramic plate and the cooling base section and is formed from a non-magnetic body, and an electrode section which supplies electricity to the heater section
Implementation Method 2
a cooling base section which is provided on the other main surface side of the electrode chuck section to cool the electrostatic chuck section and the focus ring section
Implementation Method 3
an electrostatic chuck section, one main surface of which is a placing surface for placing a plate-like specimen, and which is equipped with an internal electrode for electrostatic adsorption
Data Source
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AI summary
Disclosed is an electrostatic chuck apparatus which is configured of: an electrostatic chuck section; an annular focus ring section provided to surround the electrostatic chuck section; and a cooling base section which cools the electrostatic chuck section and the focus ring section. The focus ring section is provided with an annular focus ring, an annular heat conducting sheet, an annular ceramic ring, a nonmagnetic heater, and an electrode section that supplies power to the heater.