Selective Passivation Deposition for High-Aspect-Ratio Etching
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Solution Overview
Problem
Existing semiconductor manufacturing processes using low-temperature ALD for sidewall protection struggle with forming high aspect ratio features due to uniform deposition limitations.
Innovation Solution
A method involving targeted deposition cycles, where a precursor is deposited and then cured using a combination of curing and modification gases to form a plasma, allowing for selective curing and modification of the precursor layers to achieve nonconformal deposition tailored for high aspect ratio features.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If low-temperature ALD is used for sidewall protection, then uniform deposition is achieved, but high aspect ratio features cannot be formed effectively
Solution Approach 1:
The patent applies local quality by introducing a modification gas during the curing step that selectively modifies the precursor layer only in certain regions. The modification gas (e.g., fluorocarbon) reacts with the precursor to create regions with different etch selectivity, allowing the sidewalls of high aspect ratio features to be protected while enabling effective etching in other areas. This spatially selective modification resolves the contradiction between uniform deposition and high aspect ratio feature formation.
Solution Approach 2:
The patent changes the chemical composition and reactivity parameters of the deposited layer by introducing a modification gas during curing. This parameter change transforms the precursor layer from a uniformly curable state to a differentially modified state, where certain regions have altered etch resistance. This enables the process to handle high aspect ratio features that require non-uniform etch protection profiles.
2Manufacturing precision
If uniform deposition is used, then consistent layer thickness is achieved, but selective passivation for different feature regions is not possible
Solution Approach 1:
The patent applies preliminary action by depositing a uniform precursor layer first, then selectively modifying it during the curing step. The precursor layer is uniformly deposited across all surfaces, ensuring consistent initial thickness. Subsequently, the modification gas is introduced to selectively alter specific regions before the etching process begins. This two-step approach allows both uniform deposition and selective passivation to be achieved sequentially.
Solution Approach 2:
The curing process is segmented into two distinct functional steps: (1) uniform precursor deposition, and (2) selective modification. This segmentation allows the first step to ensure uniform layer formation while the second step introduces spatial selectivity through the modification gas. The separation of these functions resolves the contradiction between uniformity and selectivity.
3Reliability
If standard ALD curing is used, then complete curing of precursor is achieved, but selective control over different portions of the layer is lost
Solution Approach 1:
The curing process uses periodic action by introducing the modification gas for a specific duration during the curing cycle, then purging it. This periodic introduction allows selective modification to occur at controlled intervals during the curing process, maintaining overall curing completeness while enabling spatial selectivity. The modification gas is introduced periodically rather than continuously, providing operational control.
Solution Approach 2:
The modification gas is applied in a partial manner rather than uniformly across all regions. By controlling the modification gas flow and exposure time, only specific portions of the precursor layer receive the modification treatment, while other regions undergo complete curing. This partial action enables selective passivation while maintaining reliability in cured regions.
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 high aspect ratio features by selectively controlling the thickness of deposited layers, allowing for efficient etching and improved feature shape, while maintaining the benefits of ALD uniformity.
Implementation Method 1
forming a plasma from the curing gas and modification gas, and exposing the layer of precursor to the plasma providing a targeted curing
Implementation Method 2
targeted curing the layer of precursor, comprising flowing a curing gas, flowing a modification gas, forming a plasma from the curing gas and modification gas, and exposing the layer of precursor to the plasma
Data Source
AI summary
A method for patterning a stack having a mask with a plurality of mask features is provided. A targeted deposition is provided, wherein the targeted deposition comprises a plurality of cycles, wherein each cycle comprises flowing a precursor to deposit a layer of precursor and targeted curing the layer of precursor, comprising flowing a curing gas, flowing a modification gas, forming a plasma from the curing gas and modification gas, and exposing the layer of precursor to the plasma providing a targeted curing, wherein plasma from the curing gas cures first portions of the layer of precursor and plasma from the modification gas modifies second portions of the layer of precursor, wherein the modification of the second portion reduces curing of the layer of precursor of the second portions of the layer of precursor. The stack is etched through the targeted deposition.