A Circuit Simulation Model of 1S1R for 3D Phase-Change Memory

doi:10.16183/j.cnki.jsjtu.2021.522

Abstract

Abstract:

The 1S1R storage unit of 3D phase-change memory is composed of ovonic threshold switch selector (OTS) in series with the phase change memory (PCM) device. In order to solve the problems of the current OTS and PCM circuit simulation models, such as not able to accurately simulate the electrical and physical characteristics of devices, and not suitable for confined PCM, a 1S1R spice model based on Verilog-A is proposed. The model simulates the electrical characteristics of OTS and the changes of current, temperature, melting proportion, crystallization proportion and amorphous proportion in the crystallization, melting and quenching of the PCM. The model has a good convergence and fast simulation speed. The simulation results are consistent with the actual test results of the device. Compared with the traditional model, the simulation and integration of confined PCM melting process, crystal nonlinearity, melting resistivity stability and subthreshold nonlinearity, and bidirectional switching characteristics of OTS are realized. The relationship between OTS subthreshold nonlinear parameter and read voltage window is analyzed. It is found that the read window reaches its maximum when OTS threshold current is approximately equal to PCM threshold current. The results of DC simulation of 1S1R cell and transient simulation of array are displayed, providing the basis for circuit design and simulation of 3D phase-change memory.

Key words: phase change memory (PCM), circuit simulation model, ovonic threshold switch selector, Verilog-A

CLC Number:

TN432

ZHANG Guangming, LEI Yu, CHEN Houpeng, YU Qiuyao, SONG Zhitang. A Circuit Simulation Model of 1S1R for 3D Phase-Change Memory[J]. Journal of Shanghai Jiao Tong University, 2022, 56(12): 1649-1657.

Figures/Tables 12

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References 25

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参数	取值
阈值电压,U_th/V	3
保持电压,U_hold/V	0.5
关断零偏压阻值,R_OFF/GΩ	40
导通阻值,R_ON/kΩ	40
亚阈值电压常数,U_OFF/V	0.3

参数	取值
器件高度,l/nm	50
底面半径,r/nm	10
结晶温度,T_c/K	473
熔融温度,T_m/K	900
阈值电压,U_th/V	1
晶态热导率,k/(W·m^-1·K^-1)	1.5
比热容,c/(J·m^-3·K^-1)	1.24×10⁶
熔融温度扩散系数,σ_m/K	10
熔融时间常数,τ_m/ns	1
晶态电阻率,ρ_c/(Ω·m)	2×10^-4
非晶态电阻率,ρ_a/(Ω·m)	1
非晶态非线性参数,U_0a/V	0.12
晶态非线性参数,U_0c/V	0.037

来源	OTS亚阈值非线性	PCM结构	PCM熔融过程	PCM晶态非线性	熔融电阻率稳定	直流仿真结果	阵列仿真结果
文献[9]	无	mushroom	有	无	无	无	无
文献[10]		mushroom	无	无		有	有
文献[11]	有	confine	无	无		无	无
文献[13]		mushroom	有	有	无	有	有
本文	有	confine	有	有	有	有	有