Boron Nitride Wafer Support Structure for Plasma Corrosion Resistance
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Solution Overview
Problem
Conventional wafer supports made from fine ceramics like silicon nitride and aluminum nitride are difficult to process and prone to particle generation when exposed to corrosive gases or plasma atmospheres in semiconductor manufacturing, leading to faults in the manufacturing process.
Innovation Solution
A wafer support is designed with a base material comprising machinable ceramic, specifically boron nitride, a protective layer less corrodible by plasma, and a conductive member. The base material has a multilayer structure with varying boron nitride content to optimize thermal expansion coefficients and reduce particle generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fine ceramics like silicon nitride and aluminum nitride are used for wafer support, then the wafer support can be used in semiconductor manufacturing processes, but particles are easily generated from the surface when exposed to corrosive gas or plasma atmosphere
Solution Approach 1:
The patent uses a composite material structure consisting of a fine ceramic layer (silicon nitride or aluminum nitride) on top of a machinable ceramic base (boron nitride). This composite structure combines the low particle generation property of fine ceramics with the ease of processing of machinable ceramics, resolving the contradiction between reliability and ease of manufacture.
Solution Approach 2:
The wafer support is segmented into two distinct layers: a fine ceramic surface layer for low particle generation and a machinable ceramic base layer for ease of processing. This segmentation allows each layer to perform its optimal function, with the fine ceramic layer providing reliability and the machinable ceramic layer providing manufacturability.
2Ease of manufacture
If machinable ceramic is used as base material for wafer support, then the processability is improved, but particles are easily generated when exposed to corrosive gas or plasma atmosphere
Solution Approach 1:
The patent creates a composite material where a fine ceramic layer (high particle generation resistance) is formed on a machinable ceramic base (high processability). This composite structure allows the wafer support to be easily manufactured while the fine ceramic surface layer prevents particle generation during plasma exposure.
Solution Approach 2:
Different regions of the wafer support have different material properties: the surface layer uses fine ceramic for low particle generation, while the base layer uses machinable ceramic for ease of processing. This local quality differentiation resolves the contradiction by assigning appropriate materials to specific functional regions.
3Reliability
If a protective layer is added to reduce particle generation, then the corrosion resistance to plasma is improved, but the device structure becomes more complex
Solution Approach 1:
The protective layer and the base material are merged into a integrated two-layer structure where the fine ceramic layer serves as both the functional surface and the protective layer. This merging reduces overall structural complexity while providing corrosion resistance and low particle generation properties.
Solution Approach 2:
The patent uses a composite material approach where the fine ceramic layer naturally serves as the protective layer against plasma corrosion. This composite structure provides both protection and simplicity, as the protective function is achieved through the material selection rather than adding separate complex protective mechanisms.
Data Source
AI summary
A wafer support includes a base material including at least boron nitride as a machinable ceramic, a protective layer covering a surface of the base material, and a conductive member placed at least partially inside the base material. The base material includes a first layer and a second layer between the first layer and the protective layer. The protective layer includes a material that is less corrodible by plasma than the base material. The following formula is satisfied: 5≤W1−W2≤35 where the proportion of boron nitride contained in the first layer is represented by W1 [mass %] and the proportion of boron nitride contained in the second layer is represented by W2 [mass %].