Carbon or Nitrogen Doped Diode for Nonvolatile Memory Leakage Reduction
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Solution Overview
Problem
Existing nonvolatile memory arrays face challenges in achieving multi-state or rewriteable cells with low leakage current, as conventional solutions like floating gate and SONOS memory cells are complex and difficult to fabricate at small dimensions, and polysilicon resistors used in memory arrays suffer from undesired leakage through unselected cells.
Innovation Solution
A two-terminal memory cell is formed using a doped semiconductor diode, where the diode is doped with carbon or nitrogen to reduce reverse leakage current, allowing for three or more stable resistivity states and enabling one-time-programmable or rewriteable memory cells with reduced power consumption and increased bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional floating gate or SONOS memory cells are used, then multi-state or rewriteable memory functionality is achieved, but the device complexity and fabrication difficulty increase significantly
Solution Approach 1:
The patent extracts the memory storage function from complex three-terminal devices (floating gate/SONOS) and implements it in a simplified two-terminal diode structure. By removing unnecessary components and using a diode with carbon or nitrogen doping, the invention achieves multi-state functionality with reduced device complexity and easier fabrication at small dimensions.
Solution Approach 2:
The patent changes the material parameters of the diode by doping it with carbon or nitrogen, which fundamentally alters the electrical characteristics to enable multi-state operation. This parameter change allows the simple two-terminal structure to achieve functionality previously requiring complex three-terminal devices, resolving the contradiction between versatility and complexity.
2Ease of operation
If polysilicon resistors are used in memory arrays, then memory cell functionality is achieved, but reverse leakage current increases and power efficiency deteriorates
Solution Approach 1:
The patent changes the material composition of the diode by incorporating carbon or nitrogen dopants, which fundamentally alters the reverse leakage characteristics. This parameter change reduces reverse leakage current by up to four times compared to conventional polysilicon resistors, improving power efficiency while maintaining memory cell functionality.
Solution Approach 2:
The patent uses composite material approach by doping the diode with carbon or nitrogen in addition to the base semiconductor material. This composite structure creates a material with superior electrical properties, specifically lower reverse leakage current, while maintaining the required memory storage functionality.
3Ease of manufacture
If conventional memory cells are used without doping, then fabrication is simpler, but reverse leakage current is higher and power efficiency is lower
Solution Approach 1:
The patent introduces carbon or nitrogen doping as a parameter change during the diode fabrication process. This doping step, while adding a process element, uses standard semiconductor manufacturing techniques and achieves significant reduction in reverse leakage current, improving power efficiency without substantially complicating 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
The doped diode reduces reverse leakage current by up to four times, improving the power efficiency and bandwidth of memory operations while maintaining the ability to switch between multiple resistivity states, thus enhancing the performance of nonvolatile memory arrays.
Implementation Method 1
the diode is doped with carbon or nitrogen to reduce reverse leakage current
Data Source
Figure 1~2
Figure 3~4
Figure 5a
AI summary
A nonvolatile memory device includes at least one nonvolatile memory cell which comprises a silicon, germanium or silicon-germanium diode (2) which is doped with at least one of carbon or nitrogen in a concentration greater than an unavoidable impurity level concentration. The carbon and/or nitrogen is introduced for example into the intrinsic region (6) of a p-i-n diode (4,6,8).