Transistor Contact Layout for Lower Gate Parasitic Capacitance
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Solution Overview
Problem
Conventional transistor designs in memory devices experience parasitic capacitance issues due to the close proximity of contacts to the gate, which can lead to inefficiencies in current flow and increased resistance, affecting the performance of memory devices like DRAM.
Innovation Solution
The design incorporates multiple contacts in the source/drain regions positioned beyond the boundaries of the gate, with a metallic silicide region extending between them, reducing parasitic capacitance and providing a more conductive path, thereby enhancing current flow and reducing resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If contacts are positioned close to the gate, then the device area is reduced, but parasitic capacitance increases and current flow efficiency decreases
Solution Approach 1:
The contact structure is segmented into multiple parts: a first contact portion positioned away from the gate to minimize parasitic capacitance, and a second contact portion extending toward the gate to maintain compact area. This segmentation allows each portion to serve different functions - the first portion reduces harmful capacitance while the second portion maintains electrical connection efficiency.
Solution Approach 2:
The contact structure transitions from a conventional planar arrangement to a three-dimensional configuration with vertical extensions. The contact portions extend in the vertical dimension beneath the gate, allowing the contacts to be positioned away from the gate in the horizontal plane while still maintaining electrical connection, thus reducing parasitic capacitance without significantly increasing device area.
2Area of stationary object
If contacts are positioned close to the gate, then the device area is reduced, but resistance increases and current flow efficiency decreases
Solution Approach 1:
The contact structure is divided into functional segments where the first contact portion provides a low-resistance connection point away from the gate, and the second contact portion serves as an extension toward the gate. This segmentation allows optimization of current flow paths while maintaining compact device geometry.
Solution Approach 2:
The second contact portion acts as an intermediary element that bridges the gap between the first contact portion (positioned away from the gate) and the gate structure. This intermediary extension maintains electrical continuity and current flow efficiency while allowing the primary contact to be positioned in a location that minimizes parasitic effects.
3Object-generated harmful factors
If contacts are positioned away from the gate boundaries, then parasitic capacitance is reduced, but the conductive path length increases
Solution Approach 1:
The contact structure utilizes the vertical dimension by extending contact portions beneath the gate structure. This three-dimensional arrangement allows the contacts to be positioned away from the gate in the horizontal plane (reducing parasitic capacitance) while maintaining a short effective electrical path through the vertical extension, thus avoiding significant increases in conductive path length.
Data Source
AI summary
A variety of applications can include apparatus having one or more transistors with a contact arrangement to significantly mitigate a parasitic capacitance between one or more contacts to an active area of the transistor and a gate of the transistor. One or more contact arrangements can include a contact to an active area in a position beyond a boundary of an end of the gate along a first direction, where the gate is structured along the first direction. One or more other contact arrangements can include two contacts to an active area in positions beyond boundaries of two opposite ends of the gate along a first direction. Arrangements can include a metal silicide region coupling two contacts to each other in an active region with the two contacts in positions beyond boundaries of two opposite ends of the gate along a first direction.