Selective Dry Etch Silicon Nitride Spacer Fabrication
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Traditional silicon nitride spacer fabrication processes damage the sidewall surface during dry etching, affecting device performance and yield due to the inability to selectively deposit films with different properties on top, bottom, and sidewalls of 3D structures.
Innovation Solution
A method involving spatial atomic layer deposition (ALD) and plasma treatment is used to form silicon nitride films with different properties on the top and bottom relative to the sidewall, followed by high-intensity plasma dry etching using a slotted plasma assembly to selectively remove the top and bottom films, allowing for conformal deposition and selective etching without damaging the sidewalls.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional conformal SiN film deposition followed by directional plasma dry etching is used, then the top and bottom layers can be removed while keeping the sidewall film as a spacer, but the sidewall surface is damaged and film properties change, affecting device performance and yield
Solution Approach 1:
The patent applies local quality by creating different film properties at different locations on the substrate. Specifically, the silicon nitride film on the sidewalls is deposited with different characteristics (e.g., different deposition conditions, thickness, or composition) compared to the film on the top and bottom surfaces. This allows the sidewall film to resist damage during dry etching while the top and bottom films are selectively removed, solving the contradiction between ease of manufacture and prevention of sidewall damage.
2Productivity
If directional plasma dry etching is applied to remove top and bottom SiN layers, then the spacer structure is formed, but the sidewall film properties are altered and device yield decreases
Solution Approach 1:
The patent employs parameter changes by modifying deposition parameters (such as temperature, pressure, gas flow rates, or precursor ratios) to create silicon nitride films with different properties on sidewalls versus top/bottom surfaces. These parameter changes result in films with different etch resistance, stress, or composition, enabling selective removal of top and bottom layers during dry etching while preserving sidewall integrity, thus maintaining both productivity and device reliability.
3Loss of time
If conventional dry etch process is used to create spacers, then the process is simple and fast, but it cannot selectively preserve sidewall film integrity
Solution Approach 1:
The patent applies preliminary action by depositing the silicon nitride film with location-specific properties before the dry etching step. The deposition process is configured to create different film characteristics on sidewalls compared to top and bottom surfaces in advance. This preliminary differentiation enables the subsequent simple and fast dry etch process to selectively remove top and bottom films while preserving sidewall films, achieving both time efficiency and manufacturing precision.
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 formation of silicon nitride films with enhanced wet etch rates on the top and bottom while preserving the sidewall, improving device performance and yield by maintaining the integrity of the sidewall spacer.
Implementation Method 1
The deposition cycle comprises sequential exposure to a silicon precursor and a nitrogen containing reactant to form a silicon nitride film on the top, bottom and sidewalls of the at least one feature
Implementation Method 2
The treatment environment comprises a plasma having a high ion concentration. The modified silicon nitride film is dry etched using a high intensity plasma generated in a plasma assembly
Implementation Method 3
The modified silicon nitride film is dry etched using a high intensity plasma generated in a plasma assembly with a blocker plate including at least one slot and spaced from the substrate
Data Source
AI summary
Methods for forming a spacer comprising depositing a film on the top, bottom and sidewalls of a feature and treating the film to change a property of the film on the top and bottom of the feature. Selectively dry etching the film from the top and bottom of the feature relative to the film on the sidewalls of the feature using a high intensity plasma.