Single-Sided Sidewall Gate FinFET for DRAM Access
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Solution Overview
Problem
The challenge in producing arrays of vertical double-gate FinFET devices for semiconductor DRAM applications lies in maintaining suitable performance characteristics as word line spacing shrinks, leading to electrical coupling issues in high-speed DRAM applications.
Innovation Solution
A single-sided access device with an active fin structure, including a source region, drain region, insulating layer, trench isolation structure, single-sided sidewall gate electrode, and a gate protrusion laterally extended from the sidewall gate electrode, embedded between the source and drain regions, is developed to improve device control and access drive current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If vertical double-gate FinFET devices are used to improve device control, then access drive current is improved, but electrical coupling effects occur due to shrinking word line spacing
Solution Approach 1:
The patent transitions from a symmetric double-gate FinFET structure to an asymmetric single-sided sidewall gate electrode configuration. The gate electrode is positioned only on one side of the active fin structure, creating an asymmetric field effect that provides sufficient device control without the electrical coupling problems associated with dual gates in closely spaced word lines.
Solution Approach 2:
The patent extracts or removes one of the two gate electrodes from the double-gate configuration, retaining only a single-sided sidewall gate electrode. This extraction eliminates the electrical coupling effect between adjacent word lines while preserving the essential field effect control needed for device operation.
2Area of stationary object
If word line spacing is shrunk to reduce memory cell area, then device density is improved, but electrical coupling effect increases
Solution Approach 1:
By using an asymmetric single-sided gate configuration instead of symmetric double-gate structures, the patent enables closer word line spacing without electrical coupling interference. The asymmetric field distribution allows for reduced spacing while maintaining device performance and avoiding harmful coupling effects.
3Power
If single-sided sidewall gate electrode is used to reduce electrical coupling, then access drive current is improved, but device complexity changes
Solution Approach 1:
The patent simplifies the device structure by extracting or removing one gate electrode from the double-gate configuration, resulting in a single-sided sidewall gate structure. This reduction in structural complexity simultaneously improves access drive current by eliminating electrical coupling effects while maintaining sufficient field effect control.
Data Source
AI summary
The present invention provides a single-sided access device including an active fin structure comprising a source region and a drain region; an insulating layer interposed between the source region and the drain region; a trench isolation structure disposed at one side of the active fin structure; a single-sided sidewall gate electrode disposed on the other side of the active fin structure opposite to the trench isolation structure so that the active fin structure is sandwiched by trench isolation structure and the single-sided sidewall gate electrode; and a gate protrusion laterally and electrically extended from the single-sided sidewall gate electrode and embedded between the source region and the drain region under the insulating layer.