RRAM Bottom Electrode Protruded Step for Forming Voltage Control
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Solution Overview
Problem
Conventional RRAM devices face challenges such as high forming voltage, which can damage transistors and result in random filament formation, leading to a large distribution of low resistance values that are difficult to reset, and the need for multiple photomasks increases manufacturing costs.
Innovation Solution
The RRAM structure incorporates a bottom electrode with a protruded step portion that localizes the electric field during the forming process, reducing the forming voltage and using fewer photomasks by forming a self-aligned conductive path, thereby controlling filament formation and reducing manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional RRAM forming process is used, then filament formation occurs, but forming voltage is too high causing transistor damage and random filament formation
Solution Approach 1:
The bottom electrode is designed with a protruded step portion that creates a localized region of higher electric field concentration. This local structural modification ensures that the forming process occurs at a specific location with reduced voltage requirements, preventing transistor damage while achieving reliable filament formation.
Solution Approach 2:
The protruded step portion is pre-formed on the bottom electrode before the RRAM stack assembly. This preliminary structural preparation creates a predetermined electric field concentration zone that guides the filament formation process, eliminating random filament locations and reducing the forming voltage required.
2Ease of manufacture
If conventional RRAM structure is used, then manufacturing process is simple, but multiple photomasks are required increasing manufacturing costs
Solution Approach 1:
The protruded step portion on the bottom electrode serves a dual function: it concentrates the electric field during forming and simultaneously defines the filament formation location. This self-aligned approach eliminates the need for additional photomasks to pattern the filament region, reducing manufacturing costs while maintaining precise filament placement.
3Manufacturing precision
If conventional RRAM forming process is used, then filament forms, but filament location is random leading to large distribution of low resistance values
Solution Approach 1:
The protruded step portion creates a localized electric field maximum at a specific position on the bottom electrode. This local field concentration ensures that filaments form consistently at the same location, reducing the distribution of low resistance values and making reset operations more predictable and easier to control.
4Object-affected harmful factors
If protruded step portion is added to bottom electrode, then forming voltage is reduced and filament location is controlled, but device structure becomes more complex
Solution Approach 1:
The protruded step portion integrates multiple functions into a single structural feature: it serves as both the electrode contact and the electric field concentration element. This merging of functions achieves voltage reduction and filament control without requiring separate additional components, thereby limiting the increase in overall device complexity.
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 reduces the forming voltage by up to 20% and ensures more localized low resistance values, making the RRAM devices more viable and cost-effective while minimizing transistor damage and improving manufacturing efficiency.
Implementation Method 1
The RRAM structure incorporates a bottom electrode with a protruded step portion that localizes the electric field during the forming process, reducing the forming voltage
Implementation Method 2
RRAM devices operate under the principle that a dielectric, which is normally insulating, can be made to conduct through a filament or conduction path formed after the application of a sufficiently high voltage in a 'soft breakdown' of the dielectric
Data Source
AI summary
The present disclosure provides resistive random access memory (RRAM) structures and methods of making the same. The RRAM structures include a bottom electrode having protruded step portion that allows formation of a self-aligned conductive path with a top electrode during operation. The protruded step portion may have an inclination angle of about 30 degrees to 150 degrees. Multiple RRAM structures may be formed by etching through a RRAM stack.