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The One-, One- (1T1C) Dynamic Random Access Memory (DRAM), and its Impact on Society

R. Jacob Baker Department of Electrical and Boise State University 1910 University Dr., ET 201 Boise, ID 83725 [email protected]

Abstract – Memory development, in particular dynamic random access memory (DRAM), has been the greatest driving force in the advancement of -state technology for development over the last 40 years. The origin of DRAM circuits and technology can be traced to Dr. Dennard’s Patent (Number 3,387,286) granted on June 4, 1968. This truly visionary , using a single transistor and capacitor (the 1T1C), is one of the most manufactured devices in the history of mankind. This talk will review the impact of his invention and discuss the brilliance of Dr. Dennard for conceiving the invention of the 1T1C cell prior to the maturity of metal oxide (MOS) technology and in the face of critics that may have likely asked “why in the world would we want a memory, DRAM, that forgets its’ contents!?”

Baker 1 Let’s Step Back in Time

‰ What are the following (hint: they were found in your local supermarket in the 50s, 60s, and early 70s)

Photos taken from ebay.com

Baker 2 Semiconductor-based were still new during this period of time

‰ Does anyone remember the birth of the transistor ? ‰ Below is seen the 2-transistor Furtura (ca. 1955) 9 Note the output is via an earphone 9 Also note the schematic (not many, if any, products today come with a schematic)

Photos taken from ebay.com Baker 3 Evolution of the Transistor Radio

‰ These were a big deal both because they were portable (something not practically possible with tube ) and because they used a new technology (solid-state devices that didn’t wear out)

Photos taken from ebay.com Baker 4 Growing Complexity

‰ Note the use of bipolar junction technology to replace vacuum tubes

Photo taken from ebay.com Baker 5 What was going on with memory storage during this time?

‰ Dominated by the magnetic core memory seen below ‰ During the 1960s solid-state memory was developed based on the BJT 9 Ultimately wasn’t successful (compared to MOS-based memory)

1 mm

Image from wikipedia.org

Baker 6 So why is Dr. Dennard’s invention such a big deal?

‰ During the excitement of bipolar technology replacing vacuum tubes in most electronic devices he filed an invention disclosure on July 14, 1967 that 9 Used metal-oxide-semiconductor (MOS) technology 9 Proposed a memory, the one-transistor, one-capacitor (1T1C cell), that forgets its contents! ‰ Why is using MOS technology such a big deal over bipolar? 9 MOS technology is scalable! 9 Another significant contribution from Dr. Dennard’s is scaling theory. ‰ Why is a memory that forgets its contents such a big deal? 9 It’s small! 9 It’s fast!

Baker 7 Dennard’s Scaling Theory*

‰ Predicted that MOS devices would continue to shrink in size (scale) over time 9 Higher density 9 Faster 9 Low power ‰ Also discussed how interconnect would scale 9 RC times of the lines don’t scale but as distances shrink delays drop

* Dennard, R.H.; Gaensslen, F.H.; Rideout, V.L.; Bassous, E., and LeBlanc, A.R., “Design of ion-implanted MOSFET's with very small physical dimensions,” IEEE Journal of Solid-State Circuits, 9, Issue 5, Oct 1974, pp. 256 - 268

Baker 8 Scaling Theory

‰ Scaling from Dennard’s 9 Device and Circuit Scaling 9 Interconnect Scaling 9 Scale parameter is about 1.4 (1/κ = 0.7)

Baker 9 The One-Transistor, One-Capacitor (1T1C) Dynamic Random Access Memory (DRAM) cell

‰ The array is formed with word (row) and column () lines

Baker 10 Folded and Open Arrays

‰ The open array

Baker 11 Folded and Open Arrays

‰ The folded array

Baker 12 The Folded Array

Baker 13 Further Reduction in Cell Size

‰ Sharing the bitline contact

Baker 14 Mbit Pair: Folded Array

Baker 15 Folded Array Cell Size

Baker 16 Open Array: 6F2

Baker 17 Array

Baker 18 The 1T1C DRAM Cell

ACT

Row 1 1-transistor, 1-capacitor (1T1C) DRAM Cell

Row 2

EQ

VDD/2

NLAT

Col 1

I/O I/O

Baker 19 SEM Photo of a Modern DRAM Array

Baker 20 How is DRAM used today?

Workstations Personal Digital Assistants Units - 1.69M Units – 8.9M DRAM – 5,741MB/unit average DRAM - 65MB average DRAM Revenue - $1,164M DRAM Revenue - $698M Source: iSuppli Source: iSuppli

PC Servers, Enterprise Units – 0.91M DRAM – 24,581MB Notebook DRAM Revenue - $2,684M Source: iSuppli Units - 51M Desktop Computers DRAM – 510MB Units – 150M DRAM Revenue - $3,105M DRAM – 560MB Source: iSuppli DRAM Revenue - $10,048M Source: iSuppli

Memory Upgrades Printers Units – 87M Units - 112M DRAM – 295MB DRAM – 35MB DRAM Revenue - $3,060M DRAM Revenue - $156M Source: iSuppli Source: iSuppli

Baker 21 and Networking Market

Cellular Phones Set­Top Boxes Cable Modems Units - 740M Units – 62M Units – 15.7M DRAM – 5MB DRAM – 56MB DRAM – 8MB – 87MB Flash – 2MB

DSL Modems Cellular Base Stations Units – 55M Units - 0.35M DRAM – 8MB DRAM - 256MB Flash –2MB Flash – 5112MB

LAN Low­End to Mid­Range Routers Units – 113.5M Units – 1.5M DRAM – 15MB DRAM – 406MB

Sources: iSuppli, Gartner, Portelligent, Instat

Baker 22 DRAM Demand by End-Use Application

100% Industrial Automotive

Consumer Mobile Communications 80% PC Graphics Wired Other Communications Processing* 60% Upgrade Modules Entry­ Level Servers (x86)

40% Mobile/Notebooks

20% Megabits of Total Percent Desktop PC

0% 2004 2005 2006 2007 2008 2009

*Other Data Processing includes mainframe servers, enterprise servers, workstations, handheld PCs, storage cards, printers, and internet appliances

Baker 23 Worldwide DRAM Shipments by Type

100% 5 1 1Gb 2Gb DDR3 2 Mb DDR2 90% D 1Gb DDR3 D R 80%

70% 128Mb 512 Mb DDR2 RDRAM 60% 512Mb 256Mb DDR DDR3 50% 2 56 M 40% b SD 128 Mb DDR 30% 64Mb DDR 1 20% 28 M b S Percent of Total Megabytes Produced Megabytes Total of Percent 64Mb EDO DR 64M 10% b SD RAM 16Mb SDRAM FP/EDO 0% 2002 2003 2004 2005 2006 2007 2008 2009

Baker 24 100% DRAM Technology Trends

90%

80%

70%

60%

50% DDR3 DDR2 40%

Units DDR SDRAM 30%

20%

10%

0% 2002 2003 2004 2005 2006 2007 2008 2009 2010

Baker 25 DRAM Density Trends

100%

90%

80% 4 Gb

70% 2 Gb 1 Gb 60% 512 Mb 50%

Units 256 Mb 128 Mb 40% 64 Mb 30% 16 Mb 20%

10%

0% 2002 2003 2004 2005 2006 2007 2008 2009 2010

Source: IDC, Isuppli, Gartner, IC Insights Q106

Baker 26 Historical PC Market Growth

60,000,000 35% 30% 50,000,000 25% 20% 40,000,000 15% 30,000,000 10% 5% 20,000,000 0% Units in Millions in Units -5% 10,000,000 Growth over Year Year -10% 0 -15% 1Q95 3Q95 1Q96 3Q96 1Q97 3Q97 1Q98 3Q98 1Q99 3Q99 1Q00 3Q00 1Q01 3Q01 1Q02 3Q02 1Q03 3Q03 1Q04 3Q04 1Q05 3Q05E Grand Total Grand Total

Baker 27 Price per Bit Cycles

100,000.00 Historically Price per Bit has 1975 1977 declined by an average of 9% 10,000.00 1974 every quarter 1979 1976 (1974-2005) 1981 1978 1983 1,000.00 1980 1985 1982 1987 1984 1989 100.00 1991 1993 1986 1988 1995 1990 1994 10.00 1992 1997

1996 1999 1.00 Price per Bit (Milicents) per Price 1998 2001 2000 2003 2005 0.10 2002 2004 0.01 1 100 10,000

12 Cumulative Bit Volume (10 ) 1,000,000 100,000,000

Source: Gartner, 05/05

Baker 28 Americas DRAM Unit Shipments by Density

2,000.0

1,800.0

1,600.0 1Gb 1,400.0

1,200.0 512Mb

1,000.0 64Mb Millions of Units 800.0 256Mb

600.0 128Mb 400.0

200.0

2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010

1Mbit 4Mbit 16Mbit 64Mbit 128Mbit 256Mbit 512Mbit 1Gbit 2Gbit 4Gbit 8Gbit

Baker 29 256Mb Equivalent Unit DRAM Shipments

256Mb Equivalent Units Shipped (K Units)

700,000 Total 256Mb EU 100% 12/12 Growth 90% 600,000 80% 500,000 70% 60% 400,000 50% 300,000 40%

200,000 30% 20% 100,000 10% 0 0% Jul-98 Jul-99 Jul-00 Jul-01 Jul-02 Jul-03 Jul-04 Jan-99 Jan-00 Jan-01 Jan-02 Jan-03 Jan-04 Jan-05 Apr-98 Oct-98 Apr-99 Oct-99 Apr-00 Oct-00 Apr-01 Oct-01 Apr-02 Oct-02 Apr-03 Oct-03 Apr-04 Oct-04 Apr-05

Baker 30 DRAM Applications with the Highest Unit Growth Rates

(CAGR 2004 – 2008)

Entry-Level PC Servers

Internet Appliances

Mobile PCs

Wireless LAN Client Access

Wireless LAN Access Point/Bridge

SAN Switches

MP3 player

Flash Storage Cards

Digital TVs

DVD Video Recorder

0% 10% 20% 30% 40% 50% 60%

Baker 31 Fastest Growing DRAM Consumption

Enterprise Servers (CAGR 2004 – 2009) Upgrade Module

Handheld Computers

Mobile PCs

Deskbound PCs

Entry-Level PC Servers

Workstations

Internet Appliances

Remote Access RAC & RAS

Mobile Handsets

0% 20% 40% 60% 80% 100%

Baker 32 Summary Overview

‰ DRAM chips are found in virtually every computer in use today. Looking at the simplicity of the 1T1C cell one might wonder about the significance of this invention by modern day standards. However, if it is remembered that this idea was conceived back in the 1960s before MOS technology had matured enough for production or the idea that circuits could be “dynamic” (only operating correctly for a short period of time) the significance of the invention becomes clear. What is usually not mentioned when talking about Dr. Dennard’s contributions to the 1T1C is his contributions of seeing this idea to product (the true test for any practical electrical engineer). The MOS process development (and the concerns for defects and reliability which have a drastic effect on the dynamic operation of MOS circuits) and supporting circuitry are also extremely important contributions that Dr. Dennard made while at IBM. In summary, Dr. Dennard cut the path for modern DRAM memory chip developments.

Baker 33