Ion-Implanted Anti-Reflective Coating for Lithography
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Solution Overview
Problem
The semiconductor industry faces challenges in reflectivity control during lithography processes, particularly with complex structures like FinFETs, where traditional anti-reflective coating (ARC) methods struggle to maintain resolution and critical dimension accuracy due to radiation reflection issues.
Innovation Solution
A method involving ion implantation to form an ARC layer by depositing a material layer over a substrate, implanting ions of multiple species, and annealing to create a gradient refractive index layer that provides high absorbance and low reflectivity, offering better control over refractive indexes and etching resistance compared to traditional multi-deposition methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional multi-deposition methods are used to form ARC layers, then the refractive index can be controlled, but the fabrication time is long and the etching resistance is insufficient
Solution Approach 1:
The patent changes the fundamental parameter of ARC formation from multi-layer deposition to single-layer ion implantation. By implanting carbon ions into a silicon oxide layer at controlled doses (e.g., 1×10^16 to 1×10^18 ions/cm²) and energies, the refractive index is tuned from 1.46 to 2.0 in a single process step, eliminating the need for multiple depositions and reducing fabrication time significantly
Solution Approach 2:
The patent replaces the mechanical/chemical deposition process with ion implantation followed by thermal annealing. The ion implantation process physically embeds carbon atoms into the silicon oxide lattice, and subsequent annealing (e.g., 900-1100°C for 30-120 seconds) diffuses the carbon to achieve uniform distribution and desired refractive index, providing both speed and precision
2Manufacturing precision
If traditional multi-deposition methods are used to form ARC layers, then the refractive index can be controlled, but the etching resistance is poor
Solution Approach 1:
The patent creates a composite material system by implanting carbon ions into silicon oxide to form carbon-rich regions within the dielectric matrix. This composite structure (carbon-doped silicon oxide) provides both the desired optical properties (refractive index 1.46-2.0) and enhanced etching resistance, as the carbon-rich regions are more resistant to standard etchants compared to pure silicon oxide or organic ARC materials
Solution Approach 2:
By controlling the carbon ion dose and energy parameters, the patent optimizes the carbon concentration and distribution within the ARC layer. Higher doses (e.g., 1×10^18 ions/cm²) create more carbon-rich regions with better etching resistance, while still maintaining the desired refractive index through controlled diffusion during annealing
3Device complexity
If radiation reflection is not controlled, then the process is simpler, but the resist pattern resolution and critical dimension accuracy deteriorate
Solution Approach 1:
The patent extracts the reflection control function from the resist layer itself and places it in a dedicated ARC layer formed by ion implantation. This separate ARC layer absorbs or scatters reflected radiation before it can interfere with the resist pattern formation, thereby protecting the pattern resolution and critical dimension accuracy while keeping the resist formulation and exposure process relatively simple
4Productivity
If ion implantation is used to form ARC layers, then the fabrication time is reduced and etching resistance is improved, but the process complexity increases
Solution Approach 1:
The patent merges multiple functions into a single ion implantation process: forming the ARC layer, controlling the refractive index, and providing etching resistance all in one step. The subsequent annealing process serves dual purposes of activating the implanted carbon and achieving uniform distribution. This consolidation reduces the total number of process steps compared to traditional multi-deposition methods, even though ion implantation itself is a sophisticated process
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 enables the creation of ARC layers with fine-tuned refractive indexes and improved etching resistance, enhancing the accuracy of resist patterns and critical dimensions in semiconductor fabrication, while reducing fabrication time and improving reflectivity control.
Implementation Method 1
implanting ions of two or more species into the material layer
Implementation Method 2
annealing the material layer so that the ions diffuse to appropriate depths
Implementation Method 3
use the ARC layer to absorb the radiation during exposure
Data Source
AI summary
A method for lithography patterning includes depositing a target layer over a substrate, the target layer including an inorganic material; implanting ions into the target layer, resulting in an ion-implanted target layer; forming a photoresist layer directly over the ion-implanted target layer; and exposing the photoresist layer to radiation in a photolithography process. The ion-implanted target layer reduces reflection of the radiation back to the photoresist layer during the photolithography process.