Plasma Chamber Coating Suppresses Fine Particle Generation
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Solution Overview
Problem
In plasma processing, fine particles generated during etching with halogen-containing gases and oxygen can cause killer defects, leading to short-circuits and hindered processes, particularly for patterns with line widths of 20 nm or less, resulting in decreased productivity and increased demand for particle reduction.
Innovation Solution
A plasma processing apparatus with a depressurizable chamber, coated with a fluorinated compound such as yttrium fluoride (YF3) on inner surfaces exposed to plasma, which suppresses fine particle generation by forming a stable Y—O—F layer with a thickness of 20 nm or less, preventing friction and oxidation, and reducing particle size below 20 nm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thermal-sprayed film of yttrium oxide Y2O3 is used as a plasma-resistant member, then the inner surfaces are protected from plasma etching, but the yttrium oxide is consumed by reaction with CF-based gas, generating fine particles
Solution Approach 1:
The invention changes the chemical composition parameter of the plasma-resistant member from yttrium oxide (Y2O3) to yttrium fluoride (YF3). This parameter change fundamentally alters the chemical reactivity with CF-based gases, preventing the consumption reaction that generates fine particles while maintaining plasma resistance
Solution Approach 2:
The invention accepts that the plasma-resistant member will be consumed during processing, but uses a material (yttrium fluoride) that consumes without generating harmful fine particles. The consumed material is replaced periodically, transforming the problem from harmful particle generation to a simple material replacement issue
2Manufacturing precision
If the line width is reduced to 20 nm or less for fine processing, then the processing precision is improved, but fine particles cause killer defects leading to short-circuits and process failures
Solution Approach 1:
The invention converts the potentially harmful interaction between plasma and chamber walls into a beneficial outcome by using yttrium fluoride that reacts with CF-based gas to form a stable Y-O-F layer. This layer prevents the generation of harmful fine particles while allowing the plasma processing to proceed effectively
Solution Approach 2:
The Y-O-F layer formed on the yttrium fluoride surface acts as an inert barrier that prevents further harmful reactions between the plasma and chamber walls. This stable layer creates a controlled environment that prevents fine particle generation even during extended processing
3Reliability
If yttrium fluoride YF3 is coated on inner surfaces to prevent consumption by CF-based gas, then plasma resistance is maintained, but fine particles of about 60 nm or less are still generated causing killer defects
Solution Approach 1:
The invention creates a composite structure where yttrium fluoride serves as the base material and reacts with plasma to form a Y-O-F surface layer. This composite system combines the plasma resistance of yttrium fluoride with the stability of the Y-O-F layer, preventing fine particle generation
Solution Approach 2:
The yttrium fluoride coating is applied in advance to the chamber surfaces before plasma processing begins. This preliminary coating reacts with the CF-based gas to form the protective Y-O-F layer, preventing fine particle generation from the outset rather than addressing it after particles are formed
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 stabilizes the plasma processing environment, reducing fine particle generation to nearly zero, preventing killer defects and maintaining etching rates, while ensuring the plasma processing apparatus can handle high volumes of wafers without increased particle contamination.
Implementation Method 1
inner surfaces of the processing chamber which are exposed to the plasma are coated with a fluorinated compound
Implementation Method 2
forming a stable Y—O—F layer
Implementation Method 3
a high frequency power supply for applying a high frequency power for generating plasma
Implementation Method 4
generating a plasma of a gas by applying a high frequency power and performing a plasma processing on a target object to be processed by an action of the plasma
Data Source
AI summary
A plasma processing apparatus includes a processing chamber; a lower electrode serving as a mounting table for mounting thereon a target object; and an upper electrode or an antenna electrode provided to be opposite to the lower electrode. The apparatus further includes a gas supply source for introducing a gas including a halogen-containing gas and an oxygen gas into the processing chamber and a high frequency power supply for applying a high frequency power for generating plasma to at least one of the upper electrode, the antenna electrode, or the lower electrode. Among inner surfaces of the processing chamber which are exposed to the plasma, at least a part of or all of the surfaces between a mounting position of the target object and the upper electrode, or the antenna electrode; or at least a part of or all of the surfaces of the upper electrode or the antenna electrode are coated with a fluorinated compound.