PRAM Program-Suspend-Read Operation Method
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Solution Overview
Problem
Current non-volatile memory technologies, such as flash memory, face challenges with slow write times and low endurance, prompting the need for alternative solutions like Phase-Change Random Access Memory (PRAM) that can perform program-suspend-read operations without compromising endurance or power consumption.
Innovation Solution
A method for operating PRAM devices that allows for efficient program-suspend-read operations by suspending the programming of unit program blocks during read requests and resuming after the read operation is completed, ensuring that the sequence of program pulses is paused and resumed accordingly, without requiring significant additional power or affecting the device's endurance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If program-suspend-read operation is implemented in flash memory, then read operations can be performed without delaying write operations, but endurance deteriorates due to accumulation of program pulses
Solution Approach 1:
The patent changes the fundamental parameters of the memory cell by replacing flash memory architecture with PRAM architecture, utilizing phase-change material properties (crystalline/amorphous states) instead of charge trapping mechanisms. This enables the memory to withstand significantly higher program pulse counts (10^13 vs 10^5) while maintaining the ability to perform suspend and resume operations without endurance degradation.
Solution Approach 2:
The patent utilizes phase transitions of chalcogenide alloy material between crystalline and amorphous states to represent binary data. The material can be reset to amorphous state by heating above melting point and rapidly cooled, or set to crystalline state by heating below melting point and slowly cooled. This phase-change mechanism allows for high-endurance repeated programming operations that flash memory cannot achieve.
2Reliability
If conventional flash memory write operations are performed, then data can be stored, but write times are significantly slower compared to other memory types
Solution Approach 1:
The patent changes the physical mechanism of data storage from charge trapping (flash memory) to phase-state transformation (PRAM). By controlling heating temperature and cooling rate, the phase-change material can be rapidly switched between states, achieving write times under 100ns compared to flash memory's microsecond-scale write times, while maintaining non-volatile storage capability.
3Speed
If PRAM devices perform program operations continuously, then write speed is maintained, but power consumption increases
Solution Approach 1:
The patent implements periodic action by suspending program pulse generation during read operations and resuming after reads complete. The program-suspend-read operation allows the system to interleave read and write operations efficiently, maintaining high write speed when programming is active while reducing power consumption during suspend periods when no program pulses are generated.
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 PRAM devices to perform read operations without delaying write operations, maintaining high endurance and low power consumption, thus improving overall system performance and efficiency.
Implementation Method 1
A phase-change memory element includes a phase-change material sandwiched between a top electrode and a bottom electrode contact
Implementation Method 2
the phase-change material of the PRAM is reset to an amorphous state by joule heating of the material in excess of its melting point temperature
Data Source
Figure 1A~1B
Figure 2~3
Figure 4~5
AI summary
A method of performing a program-suspend-read operation in a PRAM device comprises programming a write block comprising N unit program blocks in response to a program operation request, and suspending the program operation after programming M unit program blocks, where M is less than N, in response to a read operation request. The method further comprises executing the requested read operation, and then resuming the programming of the write data block and programming (N-M) remaining unit program blocks.