Germanium Contact Structure for Low-Resistance Semiconductor Scaling
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Solution Overview
Problem
The scaling down of semiconductor devices poses challenges in achieving improved quality, yield, performance, and reliability while reducing complexity, particularly due to issues related to contact resistance.
Innovation Solution
A contact structure is designed with an intervening conductive layer, a bottom conductive layer made of germanium or silicon germanium, a conductive capping layer, and a top conductive layer, which reduces contact resistance and enhances semiconductor device performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If conventional contact structures are used in scaled-down semiconductor devices, then device dimensions are reduced, but contact resistance increases and performance deteriorates
Solution Approach 1:
The contact structure employs a composite material system consisting of a germanium-based bottom conductive layer, a conductive capping layer, and a top conductive layer. The germanium layer serves as a diffusion barrier and provides low resistance, while the capping layer prevents germanium oxidation. This composite structure resolves the contradiction by maintaining low contact resistance despite reduced device dimensions.
Solution Approach 2:
The patent applies local quality by creating distinct layers with specific functions at different locations within the contact structure. The bottom germanium layer is optimized for electrical conductivity and diffusion blocking, the capping layer is optimized for oxidation prevention, and the top layer provides mechanical support and additional conductivity. This localized optimization allows the contact structure to perform reliably at scaled dimensions.
2Reliability
If germanium is used in the bottom conductive layer, then contact resistance is reduced, but manufacturing complexity increases due to additional process steps
Solution Approach 1:
The germanium layer is formed as a preliminary step before depositing the conductive capping layer. This preliminary action ensures that the germanium diffusion barrier is in place before subsequent layers are added, preventing contamination and oxidation during the manufacturing process. The method integrates this additional step into the existing contact formation workflow.
Solution Approach 2:
The conductive capping layer acts as an intermediary between the germanium bottom layer and the top conductive layer. This intermediary layer protects the germanium from oxidation and provides a stable interface for subsequent processing steps, thereby managing the complexity introduced by using germanium while maintaining its beneficial electrical properties.
3Reliability
If multiple conductive layers are stacked, then contact performance is improved, but structural complexity increases
Solution Approach 1:
The contact structure is segmented into three distinct functional layers: a bottom germanium conductive layer for low resistance and diffusion blocking, a conductive capping layer for oxidation prevention, and a top conductive layer for mechanical support and additional conductivity. This segmentation allows each layer to be optimized for its specific function while collectively improving contact performance.
Solution Approach 2:
Each layer in the stacked structure serves multiple functions. The germanium layer provides both electrical conductivity and diffusion barrier properties. The capping layer provides both oxidation protection and a stable interface for subsequent layers. The top layer provides both mechanical support and additional electrical pathways. This multi-functionality reduces the need for additional specialized components, managing structural complexity.
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 use of a germanium-based bottom conductive layer in the contact structure effectively reduces resistance, thereby improving the performance of semiconductor devices.
Implementation Method 1
The bottom conductive layer includes germanium or silicon germanium... the resistance of the contact structure may be reduced by employing the bottom conductive layer formed of germanium
Implementation Method 2
performing an implantation process using p-type dopants or n-type dopants to the bottom conductive layer
Implementation Method 3
performing an annealing process to form an intervening conductive layer between the impurity region and the bottom conductive layer
Data Source
AI summary
The present application discloses a contact structure, a semiconductor device, and a method for fabricating the semiconductor device. The semiconductor device includes a substrate; an impurity region positioned in the substrate; an intervening conductive layer positioned on the impurity region; a bottom conductive layer positioned on the bottom conductive layer; a conductive capping layer positioned on the bottom conductive layer; a top conductive layer positioned on the conductive capping layer. The intervening conductive layer, the bottom conductive layer, the conductive capping layer, and the top conductive layer configure a contact structure. The bottom conductive layer includes germanium or silicon germanium. The bottom conductive layer includes n-type dopants or p-type dopants.