Phase Change Memory RESET Pulse Tail Seed Formation
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Solution Overview
Problem
The write speed of phase change memory (PCM) is limited by the long time required for the SET process, which slows down data writing and increases thermal stress.
Innovation Solution
A RESET pulse with a tail is applied to the phase change material, forming seeds that accelerate the SET process by shortening the crystallization time, allowing for a higher write data rate and reduced thermal stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a long pulse is used in the SET program to ensure complete crystallization, then the phase change material can be fully crystallized, but the write speed of the PCM will be lowered
Solution Approach 1:
The RESET pulse with tail creates nucleation sites (seeds) in advance before the SET pulse is applied. These pre-formed seeds provide ready-made crystallization centers that eliminate the need for lengthy crystallization processes, thereby resolving the contradiction between complete crystallization and fast write speed.
Solution Approach 2:
The invention changes the temporal parameters of the pulse sequence by introducing a tail portion to the RESET pulse, which extends the RESET duration to enable seed formation. This parameter modification allows the SET process to be accelerated through the presence of seeds, simultaneously achieving reliable crystallization and high write speed.
2Reliability
If a long SET process is used to ensure complete crystallization, then the phase change material can be fully crystallized, but thermal stress accumulates in the system
Solution Approach 1:
By forming seeds during the extended RESET pulse tail, the crystallization process is prepared in advance. When the SET pulse is applied, the pre-formed seeds enable rapid and uniform crystallization, significantly reducing the required SET duration and thereby minimizing thermal stress accumulation while ensuring complete crystallization.
Solution Approach 2:
The presence of seeds created by the RESET pulse tail allows the SET process to skip the lengthy nucleation phase and rush directly into the crystallization phase. This eliminates the need for prolonged heating, thereby reducing thermal stress while maintaining crystallization completeness.
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 method speeds up the SET process, enhancing write data rate and endurance while reducing thermal stress by forming seeds with the tailored RESET pulse, allowing for a shorter SET process duration.
Implementation Method 1
a higher voltage is applied into the phase change material for heating it above the melting temperature (Tm)
Implementation Method 2
These materials have at least two solid phases, including for example a generally amorphous solid phase and a generally crystalline solid phase
Implementation Method 3
a plurality of seeds are formed in the phase change material
Data Source
AI summary
An operation method of phase change memory (PCM) is provided. The operation method includes applying a RESET pulse to a phase change material of the PCM, wherein the RESET pulse has a profile with a first tail such that a plurality of seeds are formed in the phase change material. Due to the design of the RESET pulse in the operation method, it can speed up the crystal process.