Metal Cap Hydrogen Barrier for Semiconductor Annealing
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Solution Overview
Problem
Hydrogen absorption or incorporation into active layers of logic or memory devices can lead to drastic changes in properties, resulting in deleterious effects on device performance, necessitating methods to control hydrogen adsorption by underlying materials in semiconductor devices.
Innovation Solution
The method involves depositing a metal layer, such as copper, titanium, or tantalum, on a substrate, followed by depositing a metal cap layer, comprising materials like ruthenium, iridium, or gold, to minimize hydrogen adsorption and improve electrical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metal layer (copper, titanium, or tantalum) is deposited on a substrate, then electrical conductivity is improved, but hydrogen absorption occurs leading to degraded device performance
Solution Approach 1:
A metal cap layer is introduced as an intermediary between the hydrogen-absorbing metal layer and the environment. This cap layer (comprising ruthenium, iridium, rhodium, palladium, silver, osmium, platinum, or gold) acts as a barrier that prevents hydrogen from reaching and being absorbed by the underlying metal layer, thereby eliminating the harmful effect while preserving the electrical conductivity function.
Solution Approach 2:
A thin film metal cap layer is deposited over the metal layer to create a protective barrier. This thin film approach provides effective hydrogen blocking while maintaining the overall device structure and electrical performance, as the cap layer is sufficiently thin to not interfere with underlying device functionality but thick enough to prevent hydrogen penetration.
2Reliability
If the metal layer is made thicker to improve conductivity, then electrical properties improve, but hydrogen incorporation increases leading to more defects
Solution Approach 1:
The metal cap layer serves as a protective intermediary that decouples the relationship between metal layer thickness and hydrogen incorporation. This allows the metal layer to be optimized for electrical conductivity without concern for hydrogen absorption, as the cap layer blocks hydrogen regardless of the underlying metal layer thickness.
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 implementation of a metal cap layer effectively reduces hydrogen incorporation into the underlying metal, leading to improved electrical properties and reduced defects in semiconductor devices.
Implementation Method 1
Metal cap on the metal, the metal cap comprising one or more of ruthenium (Ru), iridium (Ir), rhodium (Rh), palladium (Pd), silver (Ag), osmium (Os), platinum (Pt), or gold (Au)
Data Source
AI summary
A method of forming an electronic device is disclosed. The method comprises forming depositing a metal on a substrate, the metal comprising one or more of copper (Cu), titanium (Ti), or tantalum (Ta). A metal cap is deposited on the metal. The metal cap comprises one or more of molybdenum (Mo), ruthenium (Ru), iridium (Ir), rhodium (Rh), palladium (Pd), silver (Ag), osmium (Os), platinum (Pt), or gold (Au). The substrate is then exposed to an anneal process, e.g., a hydrogen high-pressure anneal. The formation of the metal cap on the metal minimizes parasitic adsorption of hydrogen by the underlying metal.