TiN Capacitor Electrodes in Polysilicon Support
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Solution Overview
Problem
The increasing density of integrated circuits poses a challenge in maintaining high storage capacitance with decreasing capacitor area, as deep capacitor electrodes are prone to toppling during etching and dielectric layer deposition, requiring effective bracing structures to prevent structural instability.
Innovation Solution
The method involves forming capacitors with TiN electrodes within a polysilicon support material, using a sulfur and fluorine-containing etching chemistry for selective dry isotropic etching to expose sidewalls, followed by anisotropic etching through intermediate and inner materials to create stable capacitor structures, and forming a dielectric layer over the electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If capacitor area is decreased to increase integrated circuit density, then circuit density is improved, but storage capacitance decreases
Solution Approach 1:
The patent transitions from planar capacitor structures to three-dimensional structures by forming deep openings (trenches) in the substrate and filling them with electrode material. This vertical dimensionality allows increased capacitance per unit area, resolving the contradiction between reduced area and maintained storage capacitance.
2Quantity of substance
If capacitor electrodes are made taller to increase capacitance, then storage capacitance is improved, but structural stability deteriorates due to toppling during etching and deposition
Solution Approach 1:
The patent forms a mandrel structure and coating layer before depositing the electrode material. This preliminary structure provides mechanical support during the electrode formation process, preventing toppling of tall electrodes during etching and deposition operations.
Solution Approach 2:
The patent introduces a mandrel and coating layer as intermediary structures that provide mechanical support during electrode formation. These intermediary elements prevent direct contact between the electrode and the etching environment, stabilizing the electrode structure during processing.
3Quantity of substance
If deep openings are etched to form capacitor electrodes, then storage capacitance is improved, but etching difficulty increases
Solution Approach 1:
The patent forms a mandrel structure and coating layer before etching the deep openings. This preliminary structure serves as a protective mask and structural support during the etching process, making deep opening formation more manageable and precise.
Solution Approach 2:
The mandrel and coating layer act as intermediary protective structures during the etching process. They mediate between the etching chemistry and the substrate, enabling precise control of the etching process and reducing the difficulty of forming deep openings.
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 ensures the stability and increased capacitance of capacitors by preventing toppling and allowing full exposure of sidewall surfaces, enhancing storage capacity while maintaining structural integrity.
Implementation Method 1
The polysilicon-comprising support material is dry isotropically etched selectively relative to the TiN-comprising first capacitor electrodes using a sulfur and fluorine-containing etching chemistry
Implementation Method 2
followed by anisotropic etching through intermediate and inner materials to create stable capacitor structures
Data Source
AI summary
A method of forming capacitors includes providing first capacitor electrodes within support material. The first capacitor electrodes contain TiN and the support material contains polysilicon. The polysilicon-containing support material is dry isotropically etched selectively relative to the TiN-containing first capacitor electrodes using a sulfur and fluorine-containing etching chemistry. A capacitor dielectric is formed over sidewalls of the first capacitor electrodes and a second capacitor electrode is formed over the capacitor dielectric. Additional methods are disclosed.