Density Gradient-Free Dielectric Gap Fill
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Solution Overview
Problem
Conventional dielectric gap fill methods for high aspect ratio and narrow width features in semiconductor processing face challenges such as void formation, overhangs, and top-hats, leading to incomplete filling and device failure, especially at technology nodes below 65 nm.
Innovation Solution
A multi-cycle process involving the deposition of a flowable film followed by a solidification and/or anneal process to uniformly densify the film, with each deposition operation limited to a critical thickness to prevent density gradients and ensure seamless, void-free filling of gaps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If high-density plasma chemical vapor deposition (HDP CVD) is used for directional bottom-up gap fill, then deposition directionality is improved, but overhang formation and pinch-off occur at the entry region
Solution Approach 1:
The patent employs periodic alternation between HDP CVD deposition steps and spin-on-glass (SOG) coating steps. The HDP CVD provides directional bottom-up fill during deposition periods, while the SOG steps periodically remove overhangs and reset the entry region geometry. This periodic cycling resolves the contradiction by intermittently correcting the shape defects caused by directional deposition.
Solution Approach 2:
The patent extracts and removes the harmful overhang structures formed during HDP CVD deposition through spin-on-glass coating and subsequent etch steps. By taking out the problematic overhang material that causes pinch-off, the process maintains deposition directionality while preventing gap fill defects.
2Manufacturing precision
If in-situ plasma etch steps are used to remove overhangs and top-hats, then gap openness is improved, but process complexity and additional process steps increase
Solution Approach 1:
The patent changes the material parameter by using spin-on-glass coating instead of plasma etching to remove overhangs. The SOG process uses different chemical parameters (liquid precursor deposition followed by thermal curing) rather than plasma-based physical/chemical etching. This parameter change achieves gap openness improvement while reducing process complexity.
Solution Approach 2:
The patent uses a disposable spin-on-glass layer that is deposited, cured, and then selectively removed to clean up overhangs. This temporary material serves its purpose of defining and cleaning the gap entry region, then is discarded, replacing more complex in-situ plasma etch processes.
3Quantity of substance
If multiple deposition cycles are used to fill high aspect ratio gaps, then fill completeness is improved, but overhang formation and pinch-off occur in each cycle
Solution Approach 1:
The patent implements periodic cycles combining HDP CVD deposition with intermediate spin-on-glass overhang removal steps. Each deposition cycle builds dielectric material quantity, while the periodic SOG intervention prevents overhang accumulation and pinch-off, maintaining fill uniformity across multiple cycles.
Solution Approach 2:
The patent performs preliminary spin-on-glass coating to define the gap entry region geometry before each HDP CVD deposition cycle. This preliminary action prevents overhang formation from occurring in the first place by establishing a clean, controlled starting geometry for each deposition step.
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
The method achieves seamless and void-free dielectric gap fill in high aspect ratio, narrow width features, improving the reliability of semiconductor devices by preventing pinching off and ensuring uniform density across the filled gaps.
Implementation Method 1
chemical vapor deposition processes for forming dielectric layers
Implementation Method 2
followed by a solidification and/or anneal process that uniformly densifies the just-formed film
Data Source
AI summary
Multi-cycle methods result in dense, seamless and void-free dielectric gap fill are provided. The methods involve forming liquid or flowable films that partially fill a gap, followed by a solidification and/or anneal process that uniformly densifies the just-formed film. The thickness of the layer formed is such that the subsequent anneal process creates a film that does not have a density gradient. The process is then repeated as necessary to wholly or partially fill or line the gap as desired. The methods of this invention may be used to line or fill high aspect ratio gaps, including gaps having aspect ratios greater than about 6:1 with widths less than about 0.13 μm.