Capacitor Electrode Formation Using Sacrificial Bridging Material
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The challenge in forming capacitors for integrated circuits is the difficulty in etching high aspect ratio capacitor electrode openings within insulative materials, particularly due to the formation of native oxides and the etching of doped silicon dioxide, which can widen openings and complicate the removal of polysilicon plugging materials, leading to issues like capacitor toppling and reduced capacitance.
Innovation Solution
The method involves forming bridging material across and within the capacitor electrode openings, using a composition with a higher melting point than the covering material, and employing chemical mechanical polishing or etching to remove the bridging material, followed by etching through the covering material to form capacitor electrodes, ensuring stability and precise dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If capacitor electrode openings are etched within insulative material to high aspect ratios, then capacitor density increases, but etching difficulty increases and openings may widen due to native oxide formation
Solution Approach 1:
The patent applies preliminary action by depositing a sacrificial bridging material across the capacitor electrode openings before the electrode formation process. This bridging material serves multiple preliminary functions: it prevents opening widening during subsequent etching steps, provides structural support for tall electrodes, and can be selectively removed later. The bridging material is deposited at a stage that allows it to prevent harmful effects before they occur during the etching process.
Solution Approach 2:
The sacrificial bridging material acts as an intermediary element between the capacitor electrode openings and the etching process. It mediates the etching operation by providing a protective barrier that prevents the etchant from widening the openings, while still allowing the etching to proceed to form the electrodes. The bridging material can be selectively removed after serving its protective function, leaving the precisely-formed electrodes intact.
2Ease of manufacture
If polysilicon plugging material is used to fill openings, then electrode formation is enabled, but native oxide forms on surfaces that is difficult to remove and widens openings
Solution Approach 1:
The patent employs a sacrificial bridging material that is intentionally designed to be temporary and easily removable. This bridging material serves its purpose during the critical electrode formation and protection phases, then can be selectively removed using standard etching or CMP processes. The bridging material is essentially a disposable protective element that enables precise electrode formation without the long-term complications of permanent polysilicon plugs.
Solution Approach 2:
The patent changes material parameters by selecting a bridging material with specific properties: it should be removable by etching or CMP processes that do not affect the finished electrodes. The bridging material is chosen to have appropriate melting point, etch selectivity, and mechanical properties to provide support during processing. By carefully selecting materials with different etch rates and removal characteristics, the process enables precise dimension control.
3Quantity of substance
If capacitor electrodes are made tall to increase capacitance, then storage capacitance increases, but electrodes become unstable and may topple during processing
Solution Approach 1:
The patent applies beforehand cushioning by depositing the sacrificial bridging material across the openings before the tall capacitor electrodes are formed. This bridging material provides structural support and stabilization during the electrode formation process and subsequent handling, preventing toppling of the tall, narrow electrodes. The bridging material acts as a temporary support structure that is removed after the electrodes are securely in place.
Solution Approach 2:
The bridging material serves as an intermediary support structure between the substrate and the tall capacitor electrodes. It provides mechanical stability during processing without interfering with the final electrode function. The bridging material mediates the structural requirements by providing temporary support that enables the formation of tall, high-capacitance electrodes that would otherwise be too unstable to form or handle.
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 formation of stable capacitor electrodes with increased surface area, reducing the risk of toppling and enhancing capacitance while maintaining precise control over the etching process, thus addressing the challenges of high aspect ratio etching and material removal.
Implementation Method 1
employing chemical mechanical polishing or etching to remove the bridging material
Implementation Method 2
followed by etching through the covering material to form capacitor electrodes
Data Source
AI summary
A method of forming a capacitor includes providing material having an opening therein over a node location on a substrate. A shield is provided within and across the opening, with a void being received within the opening above the shield and a void being received within the opening below the shield. The shield is etched through within the opening. After the etching, a first capacitor electrode is formed within the opening in electrical connection with the node location. A capacitor dielectric and a second capacitor electrode are formed operatively adjacent the first capacitor electrode.