Plasma Oxidation for Spacer Profile and CD Uniformity
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Solution Overview
Problem
In semiconductor wafer processing, achieving uniformity and control of spacer profiles and critical dimensions (CD) is challenging due to variations in etch and implantation mask performance, particularly with non-silicon oxide spacer layers.
Innovation Solution
A method involving a plasma oxidation treatment to form a silicon oxide coating on spacer layers, followed by an anisotropic etch that selectively etches horizontal surfaces while protecting sidewall surfaces, ensuring uniformity and control through the use of a plasma processing chamber with controlled plasma and etch gases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If non-silicon oxide spacer layers are used for etch or implantation masks, then process flexibility and material compatibility are improved, but profile uniformity and critical dimension (CD) control deteriorate
Solution Approach 1:
A silicon oxide coating is deposited as an intermediary layer on the non-silicon oxide spacer layer. This coating serves as a mediator that provides uniform etch characteristics and CD control while allowing the underlying non-silicon oxide material to maintain its beneficial properties for mask performance and process flexibility.
Solution Approach 2:
The silicon oxide coating is applied in advance before the etch process. This preliminary action prepares the spacer layer surface with uniform properties that ensure consistent etch rates and profile control, preventing CD variations before they occur during the main etch process.
2Ease of manufacture
If conventional etching methods are used on non-silicon oxide spacer layers, then process simplicity is maintained, but profile uniformity and sidewall protection deteriorate
Solution Approach 1:
The etch process is made selective to different regions of the spacer structure. The silicon oxide coating provides different etch resistance on horizontal surfaces versus sidewall surfaces, enabling uniform horizontal etching while protecting sidewalls. This local quality differentiation achieves profile uniformity without significantly complicating the overall process.
3Manufacturing precision
If isotropic etching is used on spacer layers, then etch uniformity across the substrate is improved, but sidewall profile control and anisotropy deteriorate
Solution Approach 1:
The silicon oxide coating creates local quality differences that enable anisotropic etching behavior. The coating thickness or composition varies to provide protection on sidewalls while allowing uniform etching on horizontal surfaces, achieving both etch uniformity and sidewall profile control simultaneously.
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 approach enhances the uniformity and reliability of spacer profiles, improving device yield and reliability by protecting sidewall surfaces and allowing precise control of spacer dimensions, thereby addressing the challenges of non-silicon oxide spacer layers.
Implementation Method 1
A plasma oxidation treatment is provided to form a silicon oxide coating over the spacer layer, wherein the silicon oxide coating provides a horizontal coating on the horizontal surfaces and sidewall coatings on the sidewall surfaces of the spacer layer
Implementation Method 2
comprising providing an oxygen plasma and providing at least one of sputtering silicon to form silicon oxide with the oxygen plasma or transforming silicon of the spacer layer into silicon oxide
Implementation Method 3
An anisotropic main etch that selectively etches horizontal surfaces of the spacer layer and silicon oxide coating with respect to sidewall surfaces of the spacer layer and the sidewall coatings of the silicon oxide coating is provided
Data Source
AI summary
An apparatus for forming spacers is provided. A plasma processing chamber is provided, comprising a chamber wall, a substrate support, a pressure regulator, an antenna, a bias electrode, a gas inlet, and a gas outlet. A gas source comprises an oxygen gas source and an anisotropic etch gas source. A controller comprises a processor and computer readable media. The computer readable media comprises computer readable code for placing a substrate of the plurality of substrates in a plasma etch chamber, computer readable code for providing a plasma oxidation treatment to form a silicon oxide coating over the spacer layer, computer readable code for sputtering silicon to form silicon oxide with the oxygen plasma, computer readable code for providing an anisotropic main etch, computer readable code for etching the spacer layer, computer readable code for removing the substrate from the plasma etch chamber after etching the spacer layer.