Oxide RRAM Electroforming via PECVD-Induced Filament Formation
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Solution Overview
Problem
The challenge in manufacturing semiconductor integrated circuits is the high forming voltage required for oxide resistive random-access memory (RRAM) devices, which exceeds the capabilities of single metal-oxide-semiconductor field-effect-transistors (MOSFETs, especially as device dimensions scale down, leading to increased footprint when multiple MOSFETs are stacked to supply the necessary voltage.
Innovation Solution
A semiconductor structure and method involving a resistive random-access memory (RRAM) device with a hydrogen-containing oxide layer, a carbon-hydrogen containing silicon-nitride capping layer formed through plasma-enhanced chemical-vapor-deposition (PECVD), and a via contact to facilitate filament formation, allowing for controlled electroforming without excessive voltage requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If oxide RRAM device size is reduced to sub-um dimension, then memory density is improved, but forming voltage becomes excessively high
Solution Approach 1:
The patent changes the chemical composition parameters of the oxide layer by introducing hydrogen atoms at controlled concentrations (10^19 to 10^21 atoms/cm³). This modifies the electrical properties of the oxide layer, reducing the forming voltage from >2V to below 2V while maintaining sub-um device dimensions. The hydrogen content acts as a parameter that tunes the electroforming characteristics.
Solution Approach 2:
Hydrogen atoms serve as an intermediary species that mediates the electroforming process. The hydrogen-containing oxide layer facilitates filament formation by modifying the local chemical environment, enabling controlled breakdown at lower voltages. The hydrogen acts as a catalyst or mediator in the filament formation mechanism.
2Power
If multiple MOSFETs are stacked to support high forming voltage, then forming voltage capability is improved, but device footprint increases significantly
Solution Approach 1:
By changing the oxide layer composition to include hydrogen, the patent reduces the forming voltage requirement, allowing single-MOSFET implementation. This eliminates the need for multi-MOSFET stacking and consequently reduces the device footprint while maintaining sufficient forming voltage capability.
Solution Approach 2:
The patent extracts the voltage multiplication function from the device structure itself (by removing the need for multiple MOSFETs in series) and replaces it with a material property modification (hydrogen-containing oxide layer). This separates the voltage support function from the structural complexity, enabling compact design.
3Reliability
If conventional electroforming is used in sub-um RRAM, then device functionality is achieved, but process control becomes difficult due to high voltage requirements
Solution Approach 1:
The patent performs preliminary action by pre-introducing hydrogen into the oxide layer during deposition or through subsequent treatment. This prepares the oxide layer in advance with the appropriate chemical composition, so that during electroforming, filament formation occurs at lower voltages with better process control. The hydrogen pre-loading enables more predictable and controllable breakdown.
Solution Approach 2:
By controlling the hydrogen concentration parameter in the oxide layer (10^19 to 10^21 atoms/cm³), the patent optimizes the electroforming characteristics. This parameter control enables reliable device functionality while improving ease of manufacture through better process window and reduced voltage stress during forming.
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 enables efficient electroforming of RRAM devices at reduced voltages, maintaining device performance while minimizing footprint, thus addressing the scalability and voltage limitations of existing technologies.
Implementation Method 1
forming a capping layer on top of the first metal layer through a plasma-enhanced chemical-vapor-deposition (PECVD) process
Implementation Method 2
causing formation of one or more filaments in the oxide layer during the PECVD process of forming the capping layer
Data Source
AI summary
Embodiments of present invention provide a method of forming a resistive random-access memory (RRAM). The method includes forming a dielectric layer on top of a supporting structure, wherein the dielectric layer has a bottom electrode embedded therein; forming an oxide layer on top of the bottom electrode; treating the oxide layer in a plasma environment; forming a top electrode on top of the oxide layer; forming a first interlevel-dielectric (ILD) layer on top of the top electrode; forming a via contact and a first metal layer in the first ILD layer, wherein the first metal layer is in contact with the top electrode through the via contact; forming a capping layer on top of the first metal layer through a plasma-enhanced deposition process; and causing formation of one or more filaments in the oxide layer during the plasma-enhanced deposition process. A structure of the RRAM is also provided.