Bottom Electrode Contacts for Phase Change Memory
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Solution Overview
Problem
Phase change memory devices require high RESET currents due to large contact areas between the cell and bottom electrode, limiting scalability and increasing cell size, which impedes low-cost large-scale integration and competition with other non-volatile memory technologies.
Innovation Solution
The development of novel bottom electrode contact structures and processes that reduce the effective contact area between the phase change cell and bottom electrodes using ultra-small contact areas, achieved through specific fabrication techniques such as conformal layer deposition and spacer etching, allowing for reduced SET and RESET current requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If large contact area between cell and bottom electrode is used, then reliable electrical connection is achieved, but RESET current requirement increases and cell size increases
Solution Approach 1:
The patent applies local quality by creating a non-uniform contact area between the bottom electrode and phase change cell. The contact area is locally reduced at specific regions while maintaining adequate connection in other areas, achieving both low RESET current and reliable electrical connection through spatially differentiated contact characteristics
2Reliability
If large contact area between cell and bottom electrode is used, then reliable electrical connection is achieved, but cell size increases limiting scalability
Solution Approach 1:
The patent implements local quality by creating a bottom electrode contact structure where the contact area is locally minimized at critical regions. This selective local reduction allows the cell to achieve reliable electrical connection with significantly reduced overall contact area, enabling smaller cell size and improved scalability
Solution Approach 2:
The patent applies dimensionality change by transitioning from a planar contact interface to a three-dimensional contact structure. The bottom electrode contact structure extends in multiple dimensions, creating effective electrical connection through vertical and lateral pathways rather than relying solely on large planar contact area
3Ease of manufacture
If conventional fabrication processes are used, then manufacturing simplicity is maintained, but ultra-small contact area less than 100 nm2 cannot be achieved
Solution Approach 1:
The patent applies preliminary action by pre-forming the bottom electrode contact structure with controlled dimensions before subsequent fabrication steps. The contact area is established in advance through specific deposition and etching sequences, enabling precise control of the final contact area while maintaining compatibility with conventional fabrication processes
Solution Approach 2:
The patent implements parameter changes by modifying fabrication process parameters such as deposition thickness, etch selectivity, and pattern dimensions to achieve the target ultra-small contact area. These parameter adjustments enable precise control of contact area down to less than 100 nm2 while using standard fabrication equipment and processes
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 significantly reduces the contact area to less than 100 nm2, enabling smaller phase change memory devices, improved data density, and potential for future scaling down, making phase change memory more competitive with other non-volatile memory technologies.
Implementation Method 1
Subsequently the molten cell material is rapidly cooled down by thermal conduction through surrounding material and is quenched into a solid state that retains the disorder inherent in the molten state
Implementation Method 2
The phase change is accomplished by Joule heating the cell material with a set or rest programming current pulse
Data Source
AI summary
Bottom electrode contact structures for a semiconductor assembly and a method for forming same are described. An exemplary semiconductor device comprises electrode contact structures in a phase change memory device. The phase change memory device comprising a phase change cell is made up of a bottom electrode contact structure comprising a phase change material liner connecting between a conductive top electrode and a conductive bottom electrode where the resulting ultra-small contacts are determined by the intersection of the sidewall bottom electrode and the phase change liner.