4D-S Ltd August 20th 2013

Private and Confidential

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Abstract

4DS Confidential

4DS has developed a robust ReRAM material system, MOHJO™: High cycle life Low power dissipation Good data retention Reduced manufacturing time and cost Solves “WL drop” problem

MOHJO™ is implemented as a back end process atop standard CMOS flow MOHJO™ has a low current reset state that enables large blocks of

memory to be erased enabling a number of interesting applications MOHJO™ can be particularly useful in SSD where it can result in a

100x reduction of energy consumption.

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Technology – Key Attributes

LOW COST

• Produced using +1 to 4 mask steps when combined with standard CMOS process (as compared to +16 to 20 mask steps for FLASH) for the memory core.

• Scalable and repeatable proprietary wafer process for mass production.

LOW POWER

• Low voltage operation and low current, making it attractive for a variety of applications

LOW TEMPERATURE

• The memory is formed in the back end metal layers with a proprietary low temperature process.

HIGH SPEED • Fast Read/Write

SCALABILITY • Tested at 30nm, projected down to

10nm and below.

EXISTING FAB EQUIPMENT / PROCESSES

• Simple integration into fabs, process steps utilizes established fabrication equipment and processes.

• Proprietary process is implementable as customized module on existing fabrication tools.

DENSITY

• High density 4F2 with diode/6F2 with transistor

LONG CYCLE LIFE

• 10^9

RELIABILITY • 10 year data retention

CMOS COMPATIBLE

• Process is CMOS compatible.

4DS’ MOHJOTM memory is high speed, non-volatile, low power, low cost and is able to be produced using existing semiconductor manufacturing equipment

Metal Oxide Heterojunction Operation (MOHJOTM)

Reset -Oxidation Low R state High R state Metal oxide-1 Low Gibbs Free Energy

Metal Oxide-2 Higher Gibbs Free Energy

Hetero-junction

Set - Reduction

R1>>R2 R1~ R2

Oxygen Vacancy

Depleted

“1” “0”

Regeneration of oxygen vacancies

Oxygen vacancy

oxygen

Oxygen-Vacancy

recombination

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Technology – Relative Comparison 4DS’ MOHJOTM memory compares very favourably to the best characteristics of competing solutions

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Flash STT PCM MOJHO Density (F2) 1-4 20-60 4-16 4/(# layers) Energy per bit (pJ)

100 0.1-2.5 2-2.5 0.2-3

Read Time (ns) 100000 10-35 10-50 10-50 Write Time (ns) 100000 10-90 50-500 10-50 Endurance 10^4 10^15 10^9 10^9

Retention Years Years Years Years

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Table ERD9 Target Device and System Specifications for SCM

Parameter Benchmark [A] Target MOHJOTM

HDD [B] NAND flash [C] DRAM Memory-type SCM

Storage-type SCM

Read/Write latency 3-5 ms ~100µs (block erase ~1 ms) <100 ns <100 ns 1-10µs 10ns to 50ns

Endurance (cycles) unlimited 104-105 unlimited >109 >106 >109

Retention >10 years ~10 years 64 ms >5 days ~10 years ~10 years

ON power (W/GB) ~0.04 ~0.01-0.04 0.4 <0.4 <0.04 <0.04

Areal density ~ 1011 bit/cm2 ~ 1010 bit/cm2 ~ 109bit/cm2 ~ 1010 bit/cm2 ~ 1010 bit/cm2 ~ 1010 bit/cm2

Cost ($/GB) 0.1 2 10 <10 <3-4 <1 Notes for Table ERD9:

[A] The benchmark numbers are representative values, which may have significant variations in specific products

[B] Enterprise class [C] Single-level cell (SLC) The International Technology Roadmap for Semiconductors, 2011 Edition (latest)

Technology – Relative Positioning

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Asymmetrical Hysteresis

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1.0E-12

1.0E-11

1.0E-10

1.0E-09

1.0E-08

1.0E-07

1.0E-06

1.0E-05

1.0E-04-6 -5 -4 -3 -2 -1 0 1 2 3 4

Cu

rre

nt

(A)

Voltage (V)

Reset1

Resetread2

Reset3

Resetread3

Reset4

Resetread4

RESET Operation SET and Read Operation

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Advantages of Asymmetrical Hysteresis

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Extremely low power operation on the reset side Low power operation enables a bulk or block erase feature; which in

Flash memory type applications would provide a drop in, higher performance replacement using current flash controllers. Low power bulk erase is also a highly desirable feature in security

applications where the data may need to be wiped out quickly. Of note the bulk erase is a feature and not a requirement as in many

current nonvolatile memories. Both the Set and Reset operations can be performed on a byte by byte basis.

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Typical Cycling Data

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1.00E-10

1.00E-09

1.00E-08

1.00E-07

1.00E-06

1E+00 1E+01 1E+02 1E+03 1E+04 1E+05 1E+06

Curre

nt (A)

Number of Cycles

SET Current

RESET Current

• The cycling for this type of memory is very stable, with good results up to 10^9 using dumb cycling. With a smart algorithm including verify and field modification much higher endurance is expected.

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Typical Read Disturb Data

4DS Confidential

2.00E-08

2.00E-07

10000000 100000000 1E+09 1E+10 1E+11 1E+12

Cu

rre

nt

(A)

Number of Read Cycles

Worst Case Read Disturb

Read Current

• The graph shows the disturb of the reset condition, due to the asymmetrical hysteresis of this material the read is always done in the set direction so the worst case disturb would be of reset data.

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ReRAM Cache SSD Storage

HOST

STORAGE SYSTEM

Memory Controller

10TB

1GB

Technology – Possible Implementations 4DS’ speed and power advantages means that it is positioned to replace Cache (Main Memory) and/or embedded memory such as in the memory controller in the short term, and SSD Flash in the longer term

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Case 1

Case 2

Case 3

Implementation 1: Cache/Working memory

DRAM/ReRAM Hybrid Cache

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ReRAM

ReRAM WRITE QUEUE ReRAM memory

array

Graphics borrowed from Qureshi HPAC 2009

Implementation 1a: Working Memory 4DS ReRAM performance is comparable to high end DRAM DRAM MOJHOTM

1.Int. Voltage: < -1V and 2v ~2V 2.Endurance: > 1015 Write cycles 1012

3.Scalability: < ~20 nm Better, stackable 4.W/E time: < 50ns 50ns 5.Retention: > mS Years One limitation often brought up is the 1015 write requirement for

working memory (DRAM) applications. An important difference with RRAM though is that the read is nondestructive so a write back is not required. This significantly reduces write requirement

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Implementation 2: SSD File Storage Utilizing ReRAM to replace FLASH in SSD file storage 4DS ReRAM performance exceeds high end flash Flash MOJHOTM

1.Voltage: < 15V Better 2.Endurance: > 104 W/E cycles Better 3.Scalability: < ~18 nm, 3D stackable Comparable 4.W/E time: < 100 µs Better 5.Retention: > 10 years Comparable In spite of the excellent potential, this transistion will take a while due

to the billons invested in Flash infrastructure

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4DS MOHJOTM Embedded Memory Lower cost and higher performance than embedded flash and the updating capability

that OTP memories lack

Optimizes processor speed and reduces power consumption of electronic devices.

High Security applications

The memory would be implemented in a 1T/1R configuration for embedded applications instead of 1D/1R to reduce the design complexity on the smaller embedded memories.

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Processor

ReRAM

Pgrm I/O

Controllers Cell Phones Medical Instruments Embedded Apps

High Security in Embedded Configuration One of the major advantages of embedding memory is improved

security due to the elimination of external and easily accessible bus lines. Once the memory is embedded the next level of security is

determined by how easily a hacker can determine what is inside the memory. The 4DS MOHJOTM memory is very secure. Very low power and high speed makes thermal detection extremely difficult. No visible difference between 1’s and 0’s in de-processing

No physical links or other features.

Extremely low voltage contrast in the array due to very low read cell currents. Fast bulk erase feature allows memory to be cleared quickly so that the

information won’t fall into unfriendly hands.

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4DS MOHJO™ WL DROP The figure below illustrates a scaling problem with RRAMs built into arrays. Each

selected RRAM on the word line draws a DC current causing a voltage drop across the word line resistance. During program (set) or erase (reset) operations the voltage drops degrading the PE operation

of the cells farther from the driver. Similarly during the read operation the voltage drops will degrade the cell current reducing the

margin between states.

One common method to overcome this issue is to use shorter word lines decreasing array efficiency due to the need to duplicate driver stages. Many filamentary based RRAMs exacerbate the problem with their relatively

high “ON” currents which cause large IR drops. 4DS MOHJO currents are orders of magnitude lower than typical filamentary

memories allowing much greater array efficiency.

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WL (R)

RRAM WL Model

WL (R) WL (R) WL (R)

RRAM (I) RRAM (I) RRAM (I) RRAM (I) RRAM (I)

WL Driver

Conclusion 4DS MOHJO delivers robust performance and solves issues dogging

current and proposed future memories such as endurance, retention, array efficiency and the need for secure memories. These capabilities allow MOHJOTM to be useful in a variety of

applications If you are looking for low cost, high performance secure memories

then the 4DS MOHJOTM memory is the one to use.

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