Gap Fill Integration Using Flowable and HDP Oxide Films
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Solution Overview
Problem
Existing semiconductor processing techniques face difficulties in filling high aspect ratio gaps with insulating material due to limitations in deposition processes, particularly in narrow width features with aspect ratios greater than 6:1, leading to void formation and structural issues such as top hat reduction and clipping.
Innovation Solution
The use of flowable oxide films and high density plasma chemical vapor deposition (HDP) oxide films, where flowable oxide films can act as a sacrificial layer or for bottom-up gap fill, combined with HDP oxide films to ensure complete and void-free filling of gaps, while minimizing top hat formation and structural damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If existing deposition processes are used to fill high aspect ratio gaps, then the gaps can be filled with insulating material, but voids form and filling becomes incomplete
Solution Approach 1:
The gap filling process is divided into multiple sequential deposition steps using different materials (flowable oxide, HDP oxide) with distinct properties. Each material segment performs a specific function: flowable oxide fills the bottom portion and provides a sacrificial layer, while HDP oxide completes the fill and forms the final insulating structure. This segmentation allows each material to optimize its deposition characteristics for its specific role, ensuring complete void-free filling of high aspect ratio gaps.
Solution Approach 2:
The invention changes the physical and chemical parameters of the deposition process by alternating between flowable oxide deposition (which occurs at lower temperatures with different flow characteristics) and HDP oxide deposition (which occurs at higher temperatures with different density and adhesion properties). These parameter changes enable control over the filling mechanism, preventing void formation while maintaining complete gap fill.
2Manufacturing precision
If deposition processes are used for narrow width features with high aspect ratios, then filling can be attempted, but top hat reduction and clipping of structures occur
Solution Approach 1:
The flowable oxide layer serves as an intermediary sacrificial material that is deposited first to fill the gap. This intermediary layer protects the underlying structures during subsequent HDP oxide deposition, preventing direct contact between the HDP process and sensitive structures that would cause clipping. The flowable oxide can be selectively removed later, having served its protective function.
Solution Approach 2:
The flowable oxide deposition is performed as a preliminary action before HDP oxide deposition. This preliminary fill establishes a protective foundation and reduces the aspect ratio that subsequent materials must navigate, preventing top hat reduction and clipping of defining structures during the main filling operation.
3Ease of manufacture
If single material deposition is used for gap fill, then the process is simpler, but void-free filling of high aspect ratio features is difficult
Solution Approach 1:
The invention uses a composite deposition approach combining two different oxide materials (flowable oxide and HDP oxide) with complementary properties. The flowable oxide provides excellent conformal coverage and fills the bottom of high aspect ratio gaps, while HDP oxide provides dense, void-free completion of the fill. This composite material strategy achieves superior void-free filling compared to single material approaches, despite increased process 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 provides improved gap fill efficiency, reduces voids, and prevents clipping of structures, enabling more precise and reliable filling of high aspect ratio features, even in advanced semiconductor geometries.
Implementation Method 1
flowable oxide films... may be used as a sacrificial layer and/or as a material for bottom up gap fill
Implementation Method 2
high density plasma chemical vapor deposition oxide (HDP oxide) films
Implementation Method 3
high density plasma chemical vapor deposition oxide (HDP oxide) films
Data Source
AI summary
Novel gap fill schemes involving depositing both flowable oxide films and high density plasma chemical vapor deposition oxide (HDP oxide) films are provided. According to various embodiments, the flowable oxide films may be used as a sacrificial layer and/or as a material for bottom up gap fill. In certain embodiments, the top surface of the filled gap is an HDP oxide film. The resulting filled gap may be filled only with HDP oxide film or a combination of HDP oxide and flowable oxide films. The methods provide improved top hat reduction and avoid clipping of the structures defining the gaps.