Stimuli-Responsive Polymer Film Removal for HAR Gap Release
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Solution Overview
Problem
The fabrication of semiconductor devices with high aspect ratio structures faces challenges due to capillary forces generated during drying in wet processes, leading to feature collapse and stiction, which severely degrades device yield.
Innovation Solution
A method involving the controlled degradation of stimulus-responsive polymers (SRPs) using sequential exposure to reactants that form acids or bases, allowing precise removal of SRP from high aspect ratio gaps, thereby preventing feature collapse and stiction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If wet processes are used for etching and cleaning high aspect ratio structures, then material removal and cleaning are achieved, but capillary forces during drying cause feature collapse and stiction
Solution Approach 1:
A stimulus-responsive polymer (SRP) layer is introduced as an intermediary sacrificial material between the HAR features. This SRP layer is deposited to fill the gaps between features and provides mechanical support during drying. The SRP is then selectively removed through controlled degradation using reactants (acid or base), allowing the HAR features to be released without collapse while maintaining structural integrity throughout the process.
Solution Approach 2:
The invention changes the chemical parameters of the SRP layer by exposing it to reactants that alter its chemical composition. The SRP is degraded through controlled chemical reactions where reactants diffuse into the polymer matrix, breaking down the polymer chains into smaller fragments that can be removed. This parameter change allows selective removal of the SRP while preserving the HAR feature structures.
2Productivity
If higher temperatures are used to remove SRP, then removal speed increases, but non-volatile residues are formed that contaminate the device
Solution Approach 1:
Instead of changing temperature to accelerate SRP removal, the invention changes the chemical parameters by using reactants that degrade the polymer at lower temperatures. The controlled chemical degradation breaks down the SRP into volatile fragments that can be removed without forming non-volatile residues, maintaining device cleanliness while achieving efficient removal rates.
Solution Approach 2:
The invention replaces thermal degradation (heat-based removal) with chemical degradation (reactant-based removal). This substitution allows the SRP to be broken down at lower temperatures through controlled chemical reactions, avoiding the formation of carbonaceous residues that would otherwise require high temperatures to volatilize.
3Quantity of substance
If uniform degradation of SRP is applied, then complete removal is achieved, but HAR features may collapse due to loss of structural support
Solution Approach 1:
The invention applies partial degradation to the SRP layer by controlling the diffusion depth of reactants. Only a portion of the SRP is degraded and removed in each cycle, leaving sufficient SRP material intact to continue providing mechanical support to the HAR features. This partial action approach is repeated in multiple cycles, gradually removing the SRP while maintaining structural support throughout the process.
Solution Approach 2:
The SRP removal process is segmented into multiple discrete cycles rather than a single uniform degradation step. Each cycle involves controlled exposure to reactants for a specific duration, followed by removal of the degraded portion. This segmentation allows precise control over the degradation depth and timing, ensuring that structural support is maintained until the final removal cycle.
4Quantity of substance
If longer exposure time to reactants is used, then SRP degradation is more complete, but diffusion depth increases causing unwanted removal
Solution Approach 1:
The invention uses periodic exposure to reactants with controlled timing and duration. Each exposure cycle is interrupted by purging the chamber, creating a periodic pattern of degradation and removal. This periodic action allows precise control over the cumulative diffusion depth and degradation completeness, as the reactant exposure is reset between cycles rather than being continuous.
Solution Approach 2:
The invention performs preliminary controlled degradation in incremental steps rather than attempting complete removal in a single step. Each cycle degrades a controlled portion of the SRP, and the process is repeated until complete removal is achieved. This preliminary action approach allows monitoring and adjustment of degradation depth, preventing unwanted over-removal while ensuring complete degradation eventually.
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 method enables the controlled removal of SRPs at lower temperatures without forming non-volatile residues, reducing the risk of feature collapse and improving device yield by modulating the depth of SRP degradation and removal.
Implementation Method 1
pulsing a first reactant to the chamber such that the first reactant diffuses into the gap on to a depth less than Ttotal
Implementation Method 2
reacting the first reactant and the second reactant to form a compound that degrades the SRP
Implementation Method 3
removing the degraded SRP
Data Source
AI summary
Removing a stimuli responsive polymer (SRP) from a substrate includes controlled degradation. In certain embodiments of the methods described herein, removing SRPs includes exposure to two reactants that react to form an acid or base that can trigger the degradation of the SRP. The exposure occurs sequentially to provide more precise top down control. In some embodiments, the methods involve diffusing a compound, or a reactant that reacts to form a compound, only to a top portion of the SRP. The top portion is then degraded and removed, leaving film the remaining SRP intact. The exposure and removal cycles are repeated.