Semiconductor Contact Plug Structure for Low-Capacitance Scaling
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Solution Overview
Problem
As semiconductor devices scale down, there is a need to decrease capacitance and ensure electrical stability between contacts while maintaining performance and reliability, which existing multi-gate transistors struggle to achieve effectively.
Innovation Solution
A semiconductor device design that includes a lower and upper conductive pattern with a plug pattern connected between them, featuring a molybdenum and tungsten structure for improved contact reliability and stability, along with a gate structure with a capping pattern and source/drain contacts that enhance electrical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multi-gate transistor scaling is implemented to increase device density, then device density and current control capability are improved, but capacitance between contacts increases and electrical stability deteriorates
Solution Approach 1:
The contact structure is segmented into multiple functional layers: a lower conductive pattern, an upper conductive pattern, and a plug pattern connecting them. The plug pattern itself is segmented into a barrier pattern and a metal pattern filling the recess. This segmentation allows each layer to perform its specific function optimally while maintaining overall electrical stability despite device scaling.
Solution Approach 2:
The contact structure uses composite materials with different properties: the barrier pattern (first conductive material) provides adhesion and diffusion barrier functions, while the metal pattern (second conductive material) provides low resistance. This composite approach allows the contact to simultaneously achieve low capacitance through optimized geometry and high electrical stability through material properties.
2Length of moving object
If contact size is reduced to maintain pitch scaling, then device pitch is improved, but capacitance between contacts increases and electrical stability worsens
Solution Approach 1:
The contact structure transitions from a simple planar contact to a three-dimensional vertical stack with lower and upper conductive patterns connected by a plug pattern. This dimensional change allows the contact to maintain small pitch in the plane while achieving sufficient capacitance control and electrical stability through the vertical architecture.
Solution Approach 2:
Different regions of the contact structure have different material properties and functions: the barrier pattern provides adhesion and diffusion barrier at the interface, the metal pattern provides low resistance conduction, and the gate capping pattern provides local electrostatic control. This local quality optimization allows the contact to maintain electrical stability despite reduced pitch.
3Reliability
If gate length is increased to improve current control, then current control capability is improved, but device scaling is limited
Solution Approach 1:
The transistor structure transitions to a multi-gate configuration where the gate wraps around the channel in three dimensions. This allows the gate to control the channel from multiple directions, achieving superior current control without increasing the planar gate length, thus enabling continued device scaling.
Solution Approach 2:
The gate structure is nested around the channel region, with the gate capping pattern disposed on the gate electrode that surrounds the active pattern. This nested configuration allows the gate to control the channel from multiple sides simultaneously, improving current control capability while maintaining compact device dimensions for scaling.
Data Source
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AI summary
There is provided a semiconductor device capable of capable of improving element performance and reliability. A semiconductor device includes a lower conductive pattern disposed on a substrate, an upper conductive pattern disposed on the lower conductive pattern, and a first plug pattern disposed between the lower conductive pattern and the upper conductive pattern and connected to the lower conductive pattern and the upper conductive pattern. The first plug pattern includes a first barrier pattern that defines a first plug recess and a first plug metal pattern that fills the first plug recess, and the first plug metal pattern includes a first molybdenum pattern and a first tungsten pattern disposed on the first molybdenum pattern.