Plasma Etching Selectivity for Block Copolymer Line Edge Roughness
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Solution Overview
Problem
Current etching techniques for semiconductor devices face challenges in achieving selective removal of one material while retaining another, particularly with block copolymer layers like polystyrene-b-poly(methyl methacrylate), resulting in unacceptable line edge roughness and line width roughness, which are critical for higher density pattern integration.
Innovation Solution
A method of plasma etching using a specific etchant gas mixture comprising oxygen and sulfur-containing gases, along with controlled operating variables, to selectively remove layers and achieve target line edge roughness and line width roughness within specified ranges, utilizing a plasma etch system with a radical distribution control device and active temperature control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching techniques are used to remove one material from block copolymer layers, then material removal is achieved, but line edge roughness and line width roughness increase to unacceptable levels
Solution Approach 1:
The patent changes the chemical parameters of the etching process by using a dual chemistries approach with oxygen-based etchant for PMMA removal and sulfur-based etchant for polystyrene removal. This parameter change enables selective etching with reduced roughness by matching the chemical etchant to the specific polymer material, achieving better manufacturing precision without compromising pattern integrity
Solution Approach 2:
The patent introduces an intermediary layer or intermediate etching step that facilitates selective removal. The oxygen-based etchant acts as an intermediary that selectively attacks PMMA first, creating a controlled removal process that prevents direct aggressive etching of the polystyrene, thereby reducing line edge roughness and maintaining pattern integrity
2Reliability
If etching selectivity is increased to remove one material while retaining another, then material selectivity improves, but line edge roughness and line width roughness worsen
Solution Approach 1:
The patent achieves high etch selectivity through parameter changes by adjusting the chemical composition of the etchant environment. By controlling the presence of oxygen and sulfur compounds in the etching atmosphere, the process achieves selective removal of PMMA versus polystyrene while maintaining smooth line edges, thus improving both selectivity and manufacturing precision simultaneously
Solution Approach 2:
The patent employs periodic action through a multi-stage etching process where different chemistries are applied in sequence. The oxygen-based etching phase selectively removes PMMA, followed by a sulfur-based phase that removes polystyrene. This periodic application of different etching chemistries achieves high selectivity while controlling roughness development at each stage
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 method significantly improves etch selectivity and reduces line edge roughness and line width roughness, enabling the achievement of higher density patterns and integration objectives by optimizing the etchant gas ratios and flow rates.
Implementation Method 1
A method of plasma etching using a specific etchant gas mixture comprising oxygen and sulfur-containing gases
Implementation Method 2
performing a first etch process to selectively remove the second material and the neutral layer using a first etchant gas mixture
Data Source
AI summary
Provided is a method of plasma etching on a substrate using an etchant gas mixture to meet integration objectives, the method comprising: disposing a substrate having a structure pattern layer, a neutral layer, and an underlying layer, the structure pattern layer comprising a first material and a second material and the underlying layer comprising a silicon anti-reflective (SiARC) layer, a spin-on carbon hardmask (CHM) layer, an oxide layer, and a target layer; performing an first etch process to selectively remove the second material and the neutral layer using a first etchant gas mixture to form a first pattern; performing an second etch process to selectively remove the SiARC layer to form a second pattern; performing an third etch process to selectively remove the CHM layer to form a third pattern; concurrently controlling selected two or more operating variables wherein the first etchant gas include oxygen and sulfur-containing gases.