Silicon Nitride Patterning for Uniform Sacrificial Feature Etching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Traditional photoresist techniques for forming patterns on substrates are inadequate for small feature sizes, leading to anisotropic etch processes that result in patterned structures leaning, causing unwanted variations in subsequent etching and pattern transfer.
Innovation Solution
A method involving the deposition of a silicon nitride layer using a cyclical process with nitrogen and hydrogen reactants and plasma power, followed by isotropic chemical etching to facilitate uniform removal of sacrificial features, controlling etch profiles through manipulation of reactant flowrate, pressure, and plasma power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional photoresist techniques are used for patterning, then the process is simple and straightforward, but the technique cannot form patterns of desired size as device size decreases
Solution Approach 1:
The patent applies segmentation by dividing the patterning process into multiple stages: first forming initial photoresist patterns, then using spacer deposition and removal to create additional patterns. This multi-step approach enables formation of smaller features beyond the resolution limit of single-step photolithography, directly addressing the contradiction between achieving smaller pattern sizes and maintaining process simplicity.
2Productivity
If anisotropic etch processes are used to remove patterned features, then the etching is efficient and directional, but the patterned structures lean causing unwanted variation in subsequent etching
Solution Approach 1:
The patent employs periodic action through cyclical deposition and removal steps. The spacer material is deposited in cycles, and sacrificial features are removed in a controlled periodic manner. This periodic process allows the isotropic chemical etch to uniformly remove sacrificial material while the deposited spacer maintains vertical walls, preventing the leaning problem associated with continuous anisotropic etching and improving pattern uniformity.
3Manufacturing precision
If multiple patterning techniques are used to form smaller features, then the pattern resolution is improved, but the process complexity and number of steps increase
Solution Approach 1:
The patent merges multiple functions into a single integrated process flow. The spacer deposition step simultaneously serves as both a pattern definition step and a protective layer for subsequent etching. The cyclical deposition and removal process combines spacer formation, sacrificial material removal, and pattern transfer in an integrated sequence, reducing the total number of discrete process steps compared to traditional multiple patterning approaches.
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 more precise and uniform pattern transfer, allowing for the formation of smaller, higher-pitched etch patterns and improving device manufacturing reliability.
Implementation Method 1
providing a plasma power to form a plasma within the reaction chamber for a plasma pulse period
Implementation Method 2
At least a portion or a section of the sacrificial features can be isotopically removed during the step of depositing a layer comprising silicon nitride using a chemical reactant, such as a hydrogen reactant
Implementation Method 3
The step of depositing a layer comprising silicon nitride can include a cyclical process that includes providing a nitrogen reactant to the reaction chamber, providing a hydrogen reactant to the reaction chamber
Implementation Method 4
providing a plasma power to form a plasma within the reaction chamber for a plasma pulse period
Implementation Method 5
the method can further comprise a step of using reactive ion etching to remove a portion of the layer comprising silicon nitride
Data Source
AI summary
Methods of forming patterned structures suitable for a multiple patterning process are disclosed. Exemplary methods include forming a silicon nitride layer overlying the substrate by providing a silicon precursor to the reaction chamber for a silicon precursor pulse period, providing a nitrogen reactant to the reaction chamber, providing a hydrogen reactant to the reaction chamber, and providing a plasma power to form a plasma within the reaction chamber for a plasma pulse period. An etch profile of sacrificial features on the substrate can be controlled by controlling an amount of hydrogen provided to the reaction chamber and/or using other process parameters.