Capacitor Dielectric Phase Transformation via RuO2 Annealing
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Solution Overview
Problem
The challenge in forming capacitors is to achieve high storage capacitance without exposing substrates to high temperatures, which can damage other circuitry components, especially when depositing dielectric metal oxide layers require high temperature annealing above 500°C to achieve desired high-k phases.
Innovation Solution
The method involves depositing a dielectric metal oxide layer with a thickness no greater than 75 Angstroms and a RuO2 layer in direct physical contact, followed by annealing at temperatures below 500°C to transform the dielectric metal oxide into a higher-k crystalline phase, significantly reducing the time and temperature required for achieving the highest-k state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high temperature annealing above 500°C is applied to achieve desired high-k phases in dielectric metal oxide layers, then the dielectric constant is improved, but other circuitry components are damaged
Solution Approach 1:
The patent changes the thickness parameter of the dielectric metal oxide layer to 75 Angstroms or less, which fundamentally alters the thermal behavior during annealing. This parameter change enables the formation of high-k phases at lower temperatures (below 500°C) because thinner layers achieve the necessary crystalline transformation more efficiently, thus resolving the contradiction between achieving high dielectric constant and preventing substrate damage
Solution Approach 2:
The patent employs a composite structure consisting of a thin dielectric metal oxide layer (75 Å or less) combined with a RuO2 layer. This composite material system works synergistically where the RuO2 layer facilitates the phase transformation of the metal oxide at lower temperatures, enabling high-k phase formation without requiring damaging high-temperature annealing, thus resolving the contradiction between dielectric constant improvement and substrate protection
2Object-affected harmful factors
If dielectric metal oxide layers are deposited at and below 75 Angstroms, then substrate exposure to high temperature is reduced, but additional RuO2 layer and specific annealing process are required
Solution Approach 1:
The RuO2 layer serves multiple functions: it acts as a barrier layer preventing interdiffusion, facilitates low-temperature phase transformation of the dielectric metal oxide to high-k phase, and can serve as part of the capacitor electrode structure. This multi-functionality justifies the additional layer complexity by eliminating the need for high-temperature processing and potential damage to other circuitry
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 allows for the fabrication of capacitors with high-k dielectrics without exposing the substrate to high temperatures, enabling efficient transformation of dielectric metal oxides like ZrO2 to the tetragonal phase at lower temperatures, thus preserving the integrity of other circuitry components.
Implementation Method 1
annealing at temperatures below 500°C to transform the dielectric metal oxide into a higher-k crystalline phase
Implementation Method 2
followed by annealing at temperatures below 500°C to transform the dielectric metal oxide
Implementation Method 3
depositing a dielectric metal oxide layer with a thickness no greater than 75 Angstroms
Data Source
AI summary
A method of forming a capacitor includes depositing a dielectric metal oxide layer of a first phase to a thickness no greater than 75 Angstroms over an inner conductive capacitor electrode material. The first phase dielectric metal oxide layer has a k of at least 15. Conductive RuO2 is deposited over and into physical contact with the dielectric metal oxide layer. Then, the RuO2 and the dielectric metal oxide layer are annealed at a temperature below 500° C. The RuO2 in physical contact with the dielectric metal oxide during the annealing facilitates a change of the dielectric metal oxide layer from the first phase to a second crystalline phase having a higher k than the first phase. The annealed dielectric metal oxide layer is incorporated into a capacitor dielectric region of a capacitor construction. Other implementations are disclosed.