Dummy Gate Trench Isolation for Semiconductor Device Density
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Solution Overview
Problem
As semiconductor devices downscale, forming fine patterns by photolithography and dry etching becomes challenging, leading to reduced active region areas and increased contact resistance due to insufficient isolation between adjacent active regions.
Innovation Solution
Incorporating a dummy gate trench and electrode between transistors, which functions as an element isolation region, allowing for the use of line-and-space patterns that are easier to resolve photolithographically, thereby maintaining active region sizes and reducing contact resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the distance between two adjacent active regions is made narrower to increase device density, then productivity is improved, but manufacturing precision deteriorates because photolithography and dry etching cannot form fine patterns satisfactorily
Solution Approach 1:
The patent introduces a dummy gate trench and dummy gate electrode as an intermediary structure between adjacent active regions. This dummy gate structure serves as a mediator that enables proper isolation without requiring extremely narrow spacing between active regions, thus resolving the contradiction between device density and pattern formation precision.
Solution Approach 2:
The patent segments the gate structure into functional gates and dummy gates. The dummy gate trench and electrode are introduced as separate elements specifically for isolation purposes, allowing the active regions to be properly separated while maintaining reasonable spacing for photolithography and dry etching processes.
2Productivity
If the active region area is reduced to increase device density, then productivity is improved, but contact resistance increases due to reduced diffusion layer area
Solution Approach 1:
The dummy gate structure acts as an intermediary isolation element that prevents direct adjacency of diffusion layers from different transistors. This allows each diffusion layer to maintain sufficient area for low contact resistance while still achieving high device density through compact layout enabled by the dummy gate isolation.
3Manufacturing precision
If photolithography and dry etching are used to form fine patterns, then manufacturing precision is improved, but device complexity increases due to the need for additional isolation structures
Solution Approach 1:
The patent merges the isolation function with the gate structure by using the dummy gate trench and electrode. Instead of adding separate isolation structures, the dummy gate elements are integrated into the existing gate formation process, combining multiple functions into unified structures and reducing overall device complexity.
Solution Approach 2:
The dummy gate structure serves multiple functions: it provides electrical isolation between adjacent transistors, maintains proper spacing for fabrication processes, and can be formed using the same materials and processes as functional gates. This multi-functionality reduces the need for additional specialized isolation structures.
Data Source
AI summary
A semiconductor device includes a first gate trench, a second gate trench, and a dummy gate trench provided in an active region extending in an X direction; and a first gate electrode, a second gate electrode, and a dummy gate electrode extending in a Y direction crossing the active region, at least a part of which are buried in the first gate trench, the second gate trench, and the dummy gate trench, respectively. The dummy gate electrode arranged between second and third diffusion layers isolates and separates a transistor constituted by the first gate electrode and first and second diffusion layers provided on both sides of the first gate electrode, respectively, from a transistor constituted by the second gate electrode and third and fourth diffusion layers provided on both sides of the second gate electrode, respectively.