Subject: Fwd: PhD Orals - Yuan Zhang, June 10, 2009, 9am, Packard 101
From: James W Conway <toecutter4ranger@gmail.com>
Date: Fri, 5 Jun 2009 08:26:44 -0700
Fri, 5 Jun 2009 08:26:44 -0700

This will be a great defense
Please support your Raith champion by attending this session next week.

James Conway
Chase your Dreams...


Begin forwarded message:

> From: "Yuan Zhang" <zhangy@stanford.edu>
> Date: June 4, 2009 11:20:40 AM PDT
> To: <cis-building@cis.stanford.edu>, "'Lab'" <labmembers@snf.stanford.edu 
> >
> Subject: PhD Orals - Yuan Zhang, June 10, 2009, 9am, Packard 101
>

>
>
>
>
> Nanoscale Phase Change Memory: Device Structure and Materials  
> Characterization
>
>
>
> PhD Oral Examination
>
> Speaker: Yuan Zhang, Department of Electrical Engineering, Stanford  
> University
>
> PhD Advisor: Prof. H.-S. Philip Wong
>
>
>
> Time: 9am (refreshments served at 8:45am)
>
> Date: Wednesday, June 10, 2009
>
> Location: Packard 101
>
>
>
> Abstract:
>
>
>
> Modern digital system requires the capability of storing and  
> retrieving large amounts of information at very high speed. Non- 
> volatile solid state memories retains information when the power is  
> turned off and is now the mainstream data storage device for many  
> applications including personal electronics such as iPOD, mobile  
> phones, and netbooks. The market for non-volatile memory (NVM)  
> technology has grown substantially in recent years. However, Flash  
> memory, the dominant NVM technology, is facing fundamental scaling  
> challenges. In view of this, research in various new memory  
> technologies have been explored and accelerated. Among these  
> exploratory memory technologies, phase change memory (PCM) is one of  
> the most promising candidates, given its simple structure, good  
> scalability, high speed, and long endurance.
>
>
>
> This talk consists of two parts.  In the first part, germanium  
> nanowire diode was implemented as selection device for PCM array.  
> Unidirectional programming and reading for PCM cell requires a  
> selection device in a memory array structure to enable large array  
> sizes. Having a diode selection device can not only reduce the read  
> disturbance and leakage power, but also have the potential to  
> further increase the array density, by three-dimensional stacking of  
> cross-point memory layers. Germanium nanowire pn junction diode is a  
> good candidate for selection device because it has good scalability,  
> requires low processing temperature and has high conductivity. We  
> demonstrated a phase change memory cell structure utilizing in-situ  
> doped crystalline germanium nanowire diode integrated with a phase  
> change memory cell. The vertical nanowire diode served as the bottom  
> electrode and the memory cell selection device. Electrical  
> measurement showed low reset current and rectifying programming  
> behavior. This method provides a possible path toward high-density,  
> 3D cross-point memory arrays.
>
>
>
> In the second part of the talk, we addressed the scalability for  
> both phase change materials and phase change memory devices. Phase  
> transition properties of commonly used phase change materials for  
> both thin blanket films and nanodot samples were studied using x-ray  
> diffraction, and size dependence of the phase change properties was  
> observed. We employed self-assembly diblock copolymer patterning to  
> fabricate sub-20nm phase change nanodots.  This diblock copolymer  
> patterning technique was additionally utilized to fabricate devices  
> with small contact areas to lower the reset programming current.  
> Reduced reset current was achieved compared to a conventional  
> structure. The device can be further scaled by patterning a single  
> self-assembled contact hole in each cell to demonstrate device  
> scalability below 20 nm.
>
>
>
>
>
> -- 
> EE students mailing list
> ee-students@lists.stanford.edu
> https://mailman.stanford.edu/mailman/listinfo/ee-students



This will be a great defense
Please support your Raith champion by attending this session next week.

James Conway 
Chase your Dreams...


Begin forwarded message:

From: "Yuan Zhang" <zhangy@stanford.edu>
Date: June 4, 2009 11:20:40 AM PDT
To: <cis-building@cis.stanford.edu>, "'Lab'" <labmembers@snf.stanford.edu>
Subject: PhD Orals - Yuan Zhang, June 10, 2009, 9am, Packard 101

 

 

Nanoscale Phase Change Memory: Device Structure and Materials Characterization

 

PhD Oral Examination

Speaker: Yuan Zhang, Department of Electrical Engineering, Stanford University

PhD Advisor: Prof. H.-S. Philip Wong

 

Time: 9am (refreshments served at 8:45am)

Date: Wednesday, June 10, 2009

Location: Packard 101

 

Abstract:

 

Modern digital system requires the capability of storing and retrieving large amounts of information at very high speed. Non-volatile solid state memories retains information when the power is turned off and is now the mainstream data storage device for many applications including personal electronics such as iPOD, mobile phones, and netbooks. The market for non-volatile memory (NVM) technology has grown substantially in recent years. However, Flash memory, the dominant NVM technology, is facing fundamental scaling challenges. In view of this, research in various new memory technologies have been explored and accelerated. Among these exploratory memory technologies, phase change memory (PCM) is one of the most promising candidates, given its simple structure, good scalability, high speed, and long endurance.

 

This talk consists of two parts.  In the first part, germanium nanowire diode was implemented as selection device for PCM array. Unidirectional programming and reading for PCM cell requires a selection device in a memory array structure to enable large array sizes. Having a diode selection device can not only reduce the read disturbance and leakage power, but also have the potential to further increase the array density, by three-dimensional stacking of cross-point memory layers. Germanium nanowire pn junction diode is a good candidate for selection device because it has good scalability, requires low processing temperature and has high conductivity. We demonstrated a phase change memory cell structure utilizing in-situ doped crystalline germanium nanowire diode integrated with a phase change memory cell. The vertical nanowire diode served as the bottom electrode and the memory cell selection device. Electrical measurement showed low reset current and rectifying programming behavior. This method provides a possible path toward high-density, 3D cross-point memory arrays.

 

In the second part of the talk, we addressed the scalability for both phase change materials and phase change memory devices. Phase transition properties of commonly used phase change materials for both thin blanket films and nanodot samples were studied using x-ray diffraction, and size dependence of the phase change properties was observed. We employed self-assembly diblock copolymer patterning to fabricate sub-20nm phase change nanodots.  This diblock copolymer patterning technique was additionally utilized to fabricate devices with small contact areas to lower the reset programming current. Reduced reset current was achieved compared to a conventional structure. The device can be further scaled by patterning a single self-assembled contact hole in each cell to demonstrate device scalability below 20 nm.

 

 

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