Cobalt Contact Silicide Etch-Stop for Stable Semiconductor Contacts
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Solution Overview
Problem
The use of cobalt as a conductive material in semiconductor devices is challenging due to its reactivity with oxygen, moisture, and acid, making it difficult to stabilize and maintain its effectiveness.
Innovation Solution
Forming a silicide layer, such as Co silicide, on the surface of cobalt-based metal layers to act as a passivation layer, preventing oxidation and damage, and also serving as an etch stop layer during via formation, while being formed in the same vacuum chamber as other layers to prevent current leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cobalt is used as a conductive material, then electrical conductivity is improved, but stability against oxidation and chemical reactions deteriorates
Solution Approach 1:
A silicide layer is introduced as an intermediary between the cobalt conductive material and the external environment. This silicide layer acts as a protective barrier that prevents direct contact between cobalt and harmful substances like oxygen, moisture, and acid, thereby maintaining cobalt's stability while preserving its electrical conductivity properties.
Solution Approach 2:
The patent employs a composite structure consisting of cobalt combined with silicon to form cobalt silicide. This composite material combines the high electrical conductivity of cobalt with the oxidation resistance and chemical stability of silicide, creating a material that exhibits both desired electrical properties and enhanced environmental stability.
2Reliability
If cobalt is used in semiconductor devices, then electrical performance is improved, but ease of manufacture deteriorates due to stabilization difficulties
Solution Approach 1:
The silicide layer is formed on the cobalt surface before the cobalt is exposed to the external environment or subsequent manufacturing steps. This preliminary protective action ensures that cobalt is pre-stabilized against oxidation and chemical reactions, making the overall manufacturing process easier and more reliable.
Solution Approach 2:
The silicide layer serves as an intermediary that simplifies manufacturing by providing a stable, predictable interface between the cobalt and the external environment. This intermediary layer eliminates the need for complex stabilization procedures and ensures consistent electrical performance throughout the manufacturing process.
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 silicide layer effectively protects cobalt from oxidation and damage, enhances the stability of the conductive layers, and prevents current leakage, thereby improving the reliability and performance of semiconductor devices.
Implementation Method 1
Forming a silicide layer, such as Co silicide, on the surface of cobalt-based metal layers to act as a passivation layer, preventing oxidation and damage
Implementation Method 2
serving as an etch stop layer during via formation
Data Source
AI summary
A semiconductor device includes a source/drain region, a source/drain silicide layer formed on the source/drain region, and a first contact disposed over the source/drain silicide layer. The first contact includes a first metal layer, an upper surface of the first metal layer is at least covered by a silicide layer, and the silicide layer includes a same metal element as the first metal layer.