Strontium Ruthenium Oxide Interface for Ru Electrodes
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Solution Overview
Problem
In integrated circuit fabrication, the interface between ruthenium electrodes and strontium titanium oxide dielectrics tends to form nonstoichiometric ruthenium oxide, leading to high surface roughness, stress, and undesirable dielectric properties, which are problematic for smaller, more efficient devices like DRAM capacitors.
Innovation Solution
The formation of a strontium ruthenium oxide interface using atomic layer deposition (ALD) with a two-stage oxidation process, where water is used initially to passivate the ruthenium and ozone is used subsequently to enhance deposition rates while minimizing surface roughness, followed by annealing to achieve a perovskite crystalline structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If STO is grown directly on ruthenium, then the capacitor structure is formed, but the ruthenium oxidizes to form nonstoichiometric ruthenium oxide with high surface roughness, high stress, and low work function
Solution Approach 1:
A strontium ruthenium oxide (SRO) interface layer is introduced between the ruthenium electrode and the STO dielectric. This intermediary layer prevents direct oxidation of ruthenium, maintains surface smoothness, reduces stress, and improves the work function for better dielectric properties.
2Reliability
If SRO is used as an interface between ruthenium and STO, then dielectric properties improve, but the fabrication process becomes more complex
Solution Approach 1:
The oxidation state and composition of the ruthenium oxide interface are controlled by adjusting processing parameters such as oxygen partial pressure, temperature, and exposure time during fabrication. This allows optimization of the interface properties to achieve desired dielectric performance while managing process 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
This approach results in improved dielectric properties with reduced surface roughness and stress, facilitating better charge storage and switching performance in smaller capacitors.
Implementation Method 1
water is used initially to passivate the ruthenium
Implementation Method 2
ozone is used subsequently to enhance deposition rates while minimizing surface roughness
Implementation Method 3
followed by annealing to achieve a perovskite crystalline structure
Data Source
AI summary
Strontium ruthenium oxide provides an effective interface between a ruthenium conductor and a strontium titanium oxide dielectric. Formation of the strontium ruthenium oxide includes the use of atomic layer deposition to form strontium oxide and subsequent annealing of the strontium oxide to form the strontium ruthenium oxide. A first atomic layer deposition of strontium oxide is preformed using water as an oxygen source, followed by a subsequent atomic layer deposition of strontium oxide using ozone as an oxygen source.