Substrate Patterning via Conformal Spacer Planarization
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Solution Overview
Problem
Conventional lithographic techniques struggle to produce features with critical dimensions below 20 nm due to poor resolution and rough surfaces, limiting pitch reduction and feature density.
Innovation Solution
A method involving double patterning techniques with conformal films and chemical-mechanical polishing (CMP) to quadruple feature density, providing high uniformity and fidelity by depositing a conformal film on substrates, etching it anisotropically, and using CMP to planarize the substrate, resulting in atomically flat spacers that can be uniformly etched and transferred.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional lithographic techniques are used to pattern features, then the process is simple and direct, but the resolution is poor and surfaces are rough for features below 20 nm
Solution Approach 1:
The patent applies segmentation by dividing the patterning process into multiple discrete steps (mandrel formation, conformal film deposition, anisotropic etching, fill material deposition, planarization) rather than attempting to achieve the final pattern in a single lithographic exposure. This multi-step segmentation enables resolution below the optical diffraction limit while maintaining surface smoothness through controlled material deposition and removal.
Solution Approach 2:
The patent transitions from two-dimensional planar patterning to three-dimensional structured patterning by forming vertical sidewalls through conformal film deposition on mandrels, followed by anisotropic etching. This dimensional transition creates atomically flat spacer surfaces that can be uniformly etched and transferred, achieving high resolution that cannot be obtained through conventional planar lithography alone.
2Quantity of substance
If pitch reduction techniques are applied to increase feature density, then feature density increases, but uniformity and fidelity of features deteriorate
Solution Approach 1:
The patent employs self-service through self-aligned spacer formation where the conformal film automatically deposits uniform thickness on all mandrel sidewalls, and the subsequent anisotropic etching self-aligns to create equally spaced features. This self-aligned mechanism inherently maintains feature uniformity and fidelity while achieving pitch reduction, eliminating the need for additional alignment steps that would compromise precision.
Solution Approach 2:
The patent utilizes parameter changes by controlling the deposition thickness of the conformal film to precisely define the final feature pitch, rather than relying on lithographic exposure parameters. By adjusting the conformal film thickness parameter, the pitch can be reduced while maintaining uniformity, as the thickness is controlled by atomic layer deposition processes that provide atomic-level precision.
3Quantity of substance
If multiple patterning steps are used to achieve high feature density, then pitch is reduced, but the process complexity and number of steps increase
Solution Approach 1:
The patent merges multiple functions into integrated process steps: the conformal film deposition simultaneously creates sidewall spacers and defines the pitch for subsequent features, while the anisotropic etching step transfers the spacer pattern to the underlying layer. This merging of functions reduces the total number of discrete patterning steps compared to conventional multi-patterning approaches that require separate alignment and exposure steps for each pattern layer.
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 significantly improves feature size reduction, achieving high-resolution features with increased density and uniformity, enabling the creation of compact and uniform arrays without compromising feature resolution.
Implementation Method 1
A conformal film is deposited on exposed surfaces of the target layer and on exposed surfaces of the structures such that sidewall depositions result on vertical surfaces of the structures
Implementation Method 2
A conformal film is deposited on exposed surfaces of the target layer and on exposed surfaces of the structures such that sidewall depositions result on vertical surfaces of the structures
Implementation Method 3
The conformal film is etched such that the conformal film is at least removed from portions of target layer surfaces at locations between sidewall depositions of the conformal film
Implementation Method 4
The substrate is planarized by removing conformal film material, upper material layer, and fill material above a top surface of the planarization stop material layer such that a planar surface is formed at the top surface of the planarization stop material layer
Data Source
AI summary
Techniques disclosed herein include increasing pattern density for creating high-resolution contact openings, slots, trenches, and other features. A conformal spacer is applied on a bi-layer or tri-layer mandrel (multi-layer) or other relief feature. The conformal spacer thus wraps around the mandrels and is also deposited on an underlying layer. A fill material is deposited to fill gaps or spaces between sidewall spacers. A CMP planarization step then removes substrate stack material down to a material interface of the bi-layer or tri-layer mandrel, with a middle or lower material of the mandrel being a CMP-stop material. This technique essentially cuts off or removes rounded features such as upper portions of sidewall spacers, thereby providing a spacer material with a planar top surface that can be uniformly etched and transferred to underlying layers.