Semiconductor Well Layout With Dummy Diffusions for Leakage Control
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Solution Overview
Problem
Improperly designed dummy structures in semiconductor devices can cause device leakages and adversely impact performance due to through-well leakage issues.
Innovation Solution
The semiconductor device incorporates dummy structures with a conductive region and a doped region of complementary conductive type to the well region, which increases the injection barrier for free carriers, reducing through-well leakage. Alternatively, dummy diffusion regions are completely covered by dummy portions to prevent the formation of conductive regions and subsequent free carrier generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If dummy structures are added to increase process window and reduce process variations, then manufacturing precision is improved, but device leakage increases due to through-well leakage
Solution Approach 1:
An isolation structure (dielectric material) is introduced as an intermediary between the dummy structures and the semiconductor substrate. This isolation structure prevents direct electrical connection between the dummy structures and the substrate, thereby blocking the leakage path while allowing the dummy structures to continue providing their beneficial mechanical and process uniformity effects.
Solution Approach 2:
The dummy structures are segmented into multiple isolated units by the isolation structure. Each dummy structure is electrically isolated from the substrate and from other dummy structures, preventing the formation of continuous leakage paths while maintaining the individual beneficial effects of each dummy structure.
2Manufacturing precision
If dummy structures are placed adjacent to junctions to improve process window, then manufacturing precision is improved, but through-well leakage increases
Solution Approach 1:
The isolation structure acts as a mediator placed between the dummy structures and the substrate, allowing the dummy structures to be positioned adjacent to junctions for process window improvement while the isolation structure blocks the harmful leakage current path.
Solution Approach 2:
The isolation structure is selectively placed only in specific locations where dummy structures are adjacent to junctions, providing localized leakage prevention without affecting the overall process window benefits. The isolation structure's properties (dielectric material) are specifically chosen to provide electrical isolation while maintaining mechanical compatibility.
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 proposed solution effectively reduces through-well leakage by increasing the injection barrier for free carriers, thereby improving device performance and allowing for higher layout density and smaller chip sizes without significant increases in leakage current.
Implementation Method 1
The doped region may increase the injection barrier for the free carriers (such as holes) formed in the conductive region to be injected into the well region, so that the through-well leakage may be reduced
Implementation Method 2
the dummy structures may respectively have a dummy diffusion region and a dummy portion disposed on the dummy diffusion region and completely covering the dummy diffusion region, such that none of any conductive region (for example, a metal silicide region) may be formed in the dummy diffusion region
Data Source
AI summary
A semiconductor structure includes a substrate comprising a first well region of a first conductive type, a second well region of a second conductive type, and a junction between the first well region and the second well region, wherein the first conductive type and the second conductive type are complementary. An isolation structure is formed in the substrate to define a plurality of first dummy diffusions and second dummy diffusions and at least a first active region in the first well region, wherein the first dummy diffusions are adjacent to the junction, the first dummy diffusions are between the second dummy diffusions and the first active region, and wherein the second dummy diffusions respectively comprise a metal silicide portion. A plurality of first dummy gates are disposed on the first dummy diffusions and completely cover the first dummy diffusions, respectively.