3D Memory Contact Plug Structure for Reliable Conductive Stacking
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Solution Overview
Problem
Current semiconductor devices face challenges in achieving high data storage capacity and reliability, particularly in three-dimensional memory cell arrangements, which affect mass productivity and efficiency.
Innovation Solution
The semiconductor device incorporates a unique structure with stacked gate electrodes, channel structures, contact plugs, and support structures, featuring sequentially stacked portions with varying widths and conductive layers, including a barrier layer and conductive layers with voids, to enhance connectivity and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If memory cells are arranged three-dimensionally to increase data storage capacity, then storage capacity is improved, but manufacturing complexity and reliability are worsened
Solution Approach 1:
The contact plug is divided into multiple conductive layers (first conductive layer, second conductive layer, third conductive layer) with different materials and functions. Each layer serves a specific purpose: the first conductive layer provides low resistance, the second conductive layer acts as a barrier layer to prevent diffusion, and the third conductive layer provides mechanical support. This segmentation allows each layer to be optimized for its specific function, improving overall reliability while maintaining the three-dimensional structure.
Solution Approach 2:
The contact plug employs a composite structure with multiple materials including tungsten, copper, and cobalt arranged in specific layers. The first conductive layer uses tungsten for low resistance, the second conductive layer uses copper or cobalt as a barrier, and the third conductive layer provides structural support. This composite material approach allows the contact plug to simultaneously achieve electrical conductivity, diffusion barrier properties, and mechanical strength, thereby improving reliability in three-dimensional memory devices.
2Quantity of substance
If memory cells are arranged three-dimensionally to increase data storage capacity, then storage capacity is improved, but manufacturing complexity is worsened
Solution Approach 1:
The contact plug is divided into multiple conductive layers (first conductive layer, second conductive layer, third conductive layer) with different materials and functions. Each layer serves a specific purpose: the first conductive layer provides low resistance, the second conductive layer acts as a barrier layer to prevent diffusion, and the third conductive layer provides mechanical support. This segmentation allows each layer to be optimized for its specific function, improving overall reliability while maintaining the three-dimensional structure.
Solution Approach 2:
Different regions of the contact plug have different material compositions and properties tailored to local requirements. The upper portion (first conductive layer) is optimized for electrical conductivity, the middle portion (second conductive layer) is optimized for diffusion barrier properties, and the lower portion (third conductive layer) is optimized for mechanical support. This local quality approach reduces overall structural complexity by assigning specific functions to specific regions.
3Ease of manufacture
If contact plugs have uniform width throughout, then manufacturing is simplified, but electrical performance and reliability are worsened
Solution Approach 1:
The contact plug employs an asymmetric width profile where the first conductive layer has a wider width at its upper surface than its lower surface, and the second conductive layer has a wider width at its upper surface than its lower surface. This asymmetric design allows the contact plug to provide both electrical connectivity and mechanical support while preventing diffusion. The varying width compensates for manufacturing tolerances and ensures reliable performance.
Solution Approach 2:
Different regions of the contact plug have different material compositions and properties tailored to local requirements. The upper portion (first conductive layer) is optimized for electrical conductivity, the middle portion (second conductive layer) is optimized for diffusion barrier properties, and the lower portion (third conductive layer) is optimized for mechanical support. This local quality approach reduces overall structural complexity by assigning specific functions to specific regions.
Data Source
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Figure 2B
AI summary
A semiconductor device includes: a substrate; a conductive layer; and a contact plug connected to the conductive layer. The contact plug includes a first portion; and a second portion, sequentially stacked, wherein a width of an upper surface of the first portion is wider than a width of a lower surface of the second portion. The contact plug includes: a barrier layer; a first conductive layer on the barrier layer; and a second conductive layer on the first conductive layer. The second conductive layer comprises voids. The barrier layer, the first conductive layer, and the second conductive layer extend continuously in the first and second portions. The barrier layer has a first thickness, the second conductive layer has a second thickness, equal to or greater than the first thickness, and the first conductive layer has a third thickness, equal to or greater than the second thickness.