Freeze-Less Bilayer Polymer Patterning for Overburden Removal
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Solution Overview
Problem
Existing methods for removing overburden material in semiconductor fabrication are inefficient and can alter the dimensions of underlying structures, especially when using soft materials that cannot withstand etch or chemical mechanical polish processes.
Innovation Solution
A bilayer polymer system is used, where a first polymer forms below the surface and a second polymer forms above, allowing the second polymer to be easily removed with a developer without affecting the first, utilizing surface energy differences and self-segregation properties to facilitate overburden removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If etch or chemical mechanical polish processes are used to remove overburden material, then overburden removal is achieved, but the underlying soft material structures are damaged or dimensions are altered
Solution Approach 1:
The overcoat polymer is segmented into two distinct films with different solubility properties. The first film (lower layer) remains insoluble to protect underlying structures, while the second film (upper layer) is soluble to enable easy overburden removal. This segmentation allows selective removal of overburden material without damaging the underlying soft material structures.
Solution Approach 2:
Different regions of the overcoat polymer are given different local qualities through the bilayer system. The first film has insoluble properties for structural protection, while the second film has soluble properties for easy removal. This local differentiation enables precise control over which material is removed and which is retained during processing.
2Reliability
If a single polymer overcoat is used, then process simplicity is maintained, but selective removal of overburden without affecting underlying structures is not achieved
Solution Approach 1:
The single polymer system is divided into two distinct polymer films with different solubility characteristics. This segmentation enables the first film to protect underlying structures while the second film allows for selective overburden removal, achieving reliable selective solubility despite the increased structural complexity of using a bilayer system.
Solution Approach 2:
The overcoat polymer is formulated as a composite material consisting of two different polymers with complementary properties. This composite bilayer system combines the protective qualities of an insoluble polymer with the removable qualities of a soluble polymer, achieving reliable selective solubility for overburden removal while maintaining controlled process complexity.
3Manufacturing precision
If additional processing steps are added to protect underlying structures during overburden removal, then structural integrity is maintained, but fabrication throughput is reduced
Solution Approach 1:
The bilayer polymer system is prepared in advance with differentiated solubility properties before the overburden removal step. The first film is pre-configured to be insoluble for protection, while the second film is pre-configured to be soluble for easy removal. This preliminary configuration eliminates the need for additional protective processing steps during overburden removal, maintaining structural integrity while preserving fabrication throughput.
Solution Approach 2:
The bilayer polymer system provides self-service protection during overburden removal. The insoluble first film automatically protects underlying structures without requiring external protective measures, while the soluble second film automatically allows for easy overburden removal. This self-service mechanism maintains structural integrity and enables high throughput without additional processing steps.
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 efficient removal of overburden material while maintaining the integrity of underlying structures, improving across-wafer uniformity and reducing the need for additional processing steps, thus enhancing the precision and throughput of semiconductor fabrication.
Implementation Method 1
surface energy differences found in some fluorinated polymers or polymers with long chain alkyl functionality that promotes surface or top layer segregation in a bilayer polymer system
Implementation Method 2
the polymer mixture being configured to self-segregate relative to gravity such that a first film and a second film are formed from the polymer mixture
Implementation Method 3
activating the second solubility-shifting agent and diffusing the second solubility-shifting agent a predetermined diffusion length from the relief structures into the first film
Implementation Method 4
activating the first solubility-shifting agent using a pattern of actinic radiation
Data Source
AI summary
Techniques herein include methods of patterning a substrate using surface energy differences found in some fluorinated polymers or polymers with long chain alkyl functionality that promotes surface or top layer segregation in a bilayer polymer system to facilitate overburden removal when the polymer mixture is deposited over a relief pattern. The method allows for fast removal of the overburden to expose the anti-spacer region which, after acid diffusion and subsequent deprotection, is also soluble in a developer. Incorporating the highly developer-soluble polymer at the top of the top layer removes the need for the remaining polymer to have a specific dissolution rate in developer.