PN Diode Selector Memory Structure for Low-Leakage Scaling
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Solution Overview
Problem
Conventional non-volatile memory devices using bi-directional MOS devices as selectors face challenges in reducing device size, conduction current, and leakage current, limiting their scalability and efficiency.
Innovation Solution
The use of PN diodes in monocrystalline silicon, germanium, or gallium arsenide layers as one-way conductors, replacing bi-directional MOS devices, to form non-volatile memory devices with improved conduction current and reduced leakage current, allowing for smaller device size and broader application range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If bi-directional MOS devices are used as selectors in non-volatile memory devices, then the device can operate bidirectionally, but the device size becomes larger and leakage current increases
Solution Approach 1:
The patent changes the fundamental operating parameter of the selector from bidirectional (MOS device) to unidirectional (PN diode). By accepting the parameter change from bidirectional to unidirectional operation, the device achieves significant size reduction and leakage current reduction while maintaining sufficient functionality for memory applications
Solution Approach 2:
The patent extracts and removes the gate structure from the selector device, transitioning from a three-terminal MOS device to a two-terminal PN diode. This extraction eliminates the need for gate control complexity and reduces the device footprint, directly addressing the size reduction goal
2Ease of operation
If bi-directional MOS devices are used as selectors, then the device can control current bidirectionally, but the conduction current per unit area is lower
Solution Approach 1:
The patent changes the material parameter from standard silicon-based MOS to compound semiconductor (GaAs, GaN, SiC) PN diodes. These material parameter changes enable higher breakdown fields and higher saturation current densities, directly improving conduction current per unit area by more than an order of magnitude
3Ease of manufacture
If bi-directional MOS devices are used as selectors, then the device structure is well-established, but the leakage current is higher
Solution Approach 1:
The patent employs composite material structures combining wide-bandgap materials (GaAs, GaN, SiC) with silicon-based CMOS processes. This composite approach leverages the mature silicon fabrication infrastructure while introducing high-performance compound semiconductor diodes that exhibit exponentially lower leakage current characteristics
Solution Approach 2:
The patent changes the bandgap parameter from narrow-bandgap silicon (1.1 eV) to wide-bandgap compound semiconductors (GaAs: 1.42 eV, GaN: 3.4 eV, SiC: 3.26 eV). This parameter change fundamentally reduces the reverse saturation current and leakage current by orders of magnitude while maintaining compatibility with existing manufacturing frameworks
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 PN diode-based design achieves smaller device size, higher current per unit area, and reduced leakage current, enhancing the scalability and applicability of non-volatile memory devices.
Implementation Method 1
a first PN diode, which is formed in a monocrystalline silicon layer, a monocrystalline germanium layer or a monocrystalline gallium arsenide layer on the insulation layer
Data Source
AI summary
A non-volatile memory device includes: an insulation layer; a PN diode, which is formed in a monocrystalline silicon layer, a monocrystalline germanium layer or a monocrystalline gallium arsenide layer on the insulation layer; a writing wire which is conductive and is electrically connected to the anode end of the PN diode; a memory unit on the PN diode, the memory unit being electrically connected to a cathode end of the PN diode; and a selection wire on the memory unit, the selection wire being electrically connected to the memory unit; wherein when the non-volatile memory device is selected for a data to be written into, a first current flows through the PN diode to write the data into the memory unit.