Reshaping Spacer Profiles for Etch Uniformity in SAMP
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Solution Overview
Problem
Self-aligned multiple patterning processes, such as self-aligned double patterning, face issues with asymmetric spacer profiles post-mandrel pull, leading to degraded etch uniformity and pitch walking due to uneven etching of underlying layers, causing line edge roughness and line width roughness.
Innovation Solution
Reshaping spacer profiles by depositing additional spacer material using directional deposition processes like oblique physical vapor deposition to form symmetric spacers, which improves etch uniformity during pattern transfer by ensuring uniform delivery of etch particles across the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If spacers are formed using conventional mandrel pull processes, then spacer formation is achieved, but asymmetric spacer profiles are created leading to degraded etch uniformity
Solution Approach 1:
The patent applies preliminary action by performing a planarization process on the spacer material layer before the mandrel pull process. This pre-flattening of the spacer tops ensures that when cores are removed, the spacers maintain uniform heights and symmetric profiles, preventing the asymmetric shape formation that degrades etch uniformity in conventional processes
Solution Approach 2:
The patent changes the physical state and geometry parameters of the spacer material layer through planarization. By modifying the surface topology from asymmetric to planar/symmetric before core removal, the spacer profile parameter is fundamentally changed to ensure uniform etching performance in subsequent processes
2Ease of manufacture
If asymmetric spacers are used in pattern transfer, then spacer formation is simplified, but gouging differences and pitch walking occur in underlying layers
Solution Approach 1:
The planarization process is performed as a preliminary action before mandrel pull to prevent asymmetric spacer formation. This pre-flattening step maintains ease of manufacture while eliminating the gouging uniformity problems that would otherwise occur during pattern transfer
Solution Approach 2:
The planarization process applies preliminary anti-action by counteracting the tendency toward asymmetric spacer formation before it can occur. By flattening the spacer material layer in advance, the process prevents the development of profile asymmetries that would cause gouging differences and pitch walking during subsequent etching
3Device complexity
If conventional spacer formation is used, then process steps are minimized, but line edge roughness and line width roughness increase
Solution Approach 1:
The planarization process is integrated as a preliminary step that prepares the spacer material layer for uniform spacer formation. This pre-treatment reduces line edge and line width roughness by ensuring symmetric spacer profiles, thereby improving manufacturing precision without significantly increasing overall process complexity
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 reshaped symmetric spacers achieve target levels of etch uniformity and reduced gouging, addressing the degradation in etch profiles and line edge roughness issues associated with prior asymmetric spacer shapes.
Implementation Method 1
depositing additional spacer material using directional deposition processes like oblique physical vapor deposition
Implementation Method 2
The mandrel pull process is often performed by a plasma etch process such as a reactive ion etch (RIE) process
Data Source
AI summary
Embodiments are described herein to reshape spacer profiles to improve spacer uniformity and thereby improve etch uniformity during pattern transfer associated with self-aligned multiple-patterning (SAMP) processes. For disclosed embodiments, cores are formed on a material layer for a substrate of a microelectronic workpiece. A spacer material layer is then formed over the cores. Symmetric spacers are then formed adjacent the cores by reshaping the spacer material layer using one or more directional deposition processes to deposit additional spacer material and using one or more etch process steps. For one example embodiment, one or more oblique physical vapor deposition (PVD) processes are used to deposit the additional spacer material for the spacer profile reshaping. This reshaping of the spacer profiles allows for symmetric spacers to be formed thereby improving etch uniformity during subsequent pattern transfer processes.