Dielectric Fin Capping to Prevent GAA Gate Contact Shorting
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Solution Overview
Problem
The increasing aspect ratio of dielectric fins in gate-all-around (GAA) transistors leads to seam formation and bridging risks between source/drain contact and metal gate, causing device failure.
Innovation Solution
A dielectric cap is formed within the top gap of the seam and the height of the dielectric fin is reduced to prevent shorting between source/drain contact and the metal gate, while maintaining the integrity of the dielectric fin structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the aspect ratio of dielectric fins is increased to improve integration density, then more components can be integrated into a given area, but seam formation and bridging risks between source/drain contact and metal gate occur, causing device failure
Solution Approach 1:
A dielectric cap is formed over the dielectric fin at a first stage of fabrication, before the high-aspect-ratio problems occur. This preliminary protective structure prevents seam formation and bridging during subsequent etching processes, allowing the dielectric fin to achieve high aspect ratio without compromising device reliability
Solution Approach 2:
The dielectric cap acts as a protective cushion that prevents harmful effects (seam formation and bridging) before they can occur. By placing this protective layer beforehand, the patent eliminates the risk of device failure that would otherwise result from the high aspect ratio of the dielectric fin
2Strength
If the height of the dielectric fin is increased to maintain structural integrity, then the dielectric fin can support higher aspect ratios, but seam enlargement during etching processes occurs, leading to shorting risks
Solution Approach 1:
The dielectric cap serves as an intermediary protective structure between the etching process and the dielectric fin. It mediates the interaction by absorbing or preventing the harmful effects of etching on the dielectric fin, thereby maintaining both the structural integrity and manufacturing precision of the fin structure
Solution Approach 2:
The dielectric cap is formed in advance before etching operations, preliminarily protecting the dielectric fin from seam enlargement. This preliminary action ensures that subsequent etching processes do not compromise the precision of the dielectric fin structure
Data Source
AI summary
A method of forming a semiconductor device includes etching trenches in a substrate to form semiconductor fins, filling a first one of the trenches with a dielectric fin, forming an insulation material in a second one of the trenches, performing a first recessing process to recess the insulation material and form a gap on a top of the dielectric fin, filling the gap with a dielectric cap, and forming a gate stack across the semiconductor fins and the dielectric fin.