Vertical Memory Channel Formation Without Oxide Etch Damage
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Solution Overview
Problem
Conventional methods of forming semiconductor devices using oxide semiconductor materials for channels in vertical access devices expose these materials to etch chemistries that negatively impact current flow, limiting device performance.
Innovation Solution
A method involving the formation of a first barrier structure impermeable to hydrogen, followed by the creation of linear conductive and sacrificial structures, and subsequent selective removal of these structures to form channel structures using a damascene process, which avoids exposure to harmful etch chemistries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching methods are used to form oxide semiconductor channel structures, then the channel structures can be formed, but the oxide semiconductor material is exposed to harmful etch chemistries that negatively impact current flow and device performance
Solution Approach 1:
A sacrificial structure made of silicon nitride is introduced as an intermediary element. This sacrificial structure serves as a placeholder during fabrication that protects the oxide semiconductor material from direct exposure to harmful etch chemistries. The sacrificial structure is later removed through selective etching, leaving a clean channel structure without contamination from aggressive etchants.
Solution Approach 2:
The sacrificial structure is formed in advance before the oxide semiconductor material is deposited. This preliminary action establishes a protective framework that prevents harmful etch chemistries from contacting the oxide semiconductor during subsequent processing steps, thereby preserving the material's electrical properties.
2Reliability
If oxide semiconductor materials are used for channels in vertical access devices, then larger band gaps and improved electrical properties are achieved, but conventional formation methods expose the material to harmful etch chemistries that reduce off-state current performance
Solution Approach 1:
The silicon nitride sacrificial structure acts as a protective intermediary barrier between the oxide semiconductor material and harmful etch chemistries. It allows the oxide semiconductor to be formed and processed without direct exposure to damaging chemicals, preserving its large band gap properties and low off-state current characteristics.
Solution Approach 2:
The harmful etch chemistry exposure is extracted or removed from the fabrication process by using the sacrificial structure approach. Instead of directly etching the oxide semiconductor, the sacrificial structure is etched selectively, taking out the harmful exposure step while maintaining the necessary channel formation.
3Reliability
If the damascene process with sacrificial structures is used to form channels, then exposure to harmful etch chemistries is avoided, but the manufacturing process becomes more complex
Solution Approach 1:
The channel formation process is segmented into distinct stages: forming the sacrificial structure, depositing oxide semiconductor over it, selectively removing the sacrificial structure, and forming the final channel. This segmentation allows each step to be optimized independently, with the sacrificial structure removal being selectively performed only where needed, managing complexity through structured division of the fabrication process.
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 enhances the electrical properties of semiconductor devices by reducing off-state current and improving reliability and durability, while maintaining high on-current and faster switching speeds.
Implementation Method 1
a first barrier structure substantially impermeable to hydrogen
Data Source
AI summary
A method of forming a device comprises forming sacrificial pillar structures over conductive structures overlying a barrier structure substantially impermeable to hydrogen. The sacrificial pillar structures are separated from one another by trenches linearly extending in a first lateral direction orthogonal to a second lateral direction in which the conductive structures linearly extend. Gate electrodes are formed within the trenches and laterally adjacent sidewalls of the sacrificial pillar structures. The sacrificial pillar structures are removed to form openings between the gate electrodes. Dielectric liner structures are formed within the openings and laterally adjacent sidewalls of the gate electrodes. Channel structures are formed within the openings after forming the dielectric liner structures. The channel structures comprise a semiconductive material having a band gap larger than that of polycrystalline silicon. Conductive contacts are formed on the channel structures. A device, a memory device, and an electronic system are also described.