Transcript Flash_Memory_Kawamoto_120303_Histroy_PP_Presentaion

The IEEE History Committee
March 3, 2012
THE HISTORY OF DEVELOPMENTS
OF FLASH MEMORY
Hiro Kawamoto
Structures of Non-Volatile Memory
1967-1971
•
•
•
•
•
1967
USE of FIELD-EFFECT TRANSISTOR
FLOATING GATE for CHARGE STORAGE
WRITE by TUNNELING
ERASE by TUNNELING
• D. Kahng and S. M. Sze, “A floating gate and its application to
memory devices,” Bell Syst. Tech. J., (46) p.1288 (1967) [Ref:
Flash Memory Kahng and Sze paper]
• What was new: More recent innovations are directed toward
obtaining controlled charging sites in the gate insulation itself to
allow charge-storage. The first application of this concept was
realized by the use of a floating gate, wherein charge
communication with the underlying Si bulk for both electrical write-in
and electrical erase was obtained by a tunneling.” The non-volatile
memory fabricated by them was a forerunner of current flash
memory, which contained all the key components: a floating gate
buried in a field-effect transistor, the Fowler-Nordheim tunneling for
both writing and erasing, and a
1970-1971
•
•
•
•
•
•
•
•
•
•
•
•
1970
WRITE by AVALNCHE EFFECT
ERASE by ULTRA-VIOLET RADAITION
COMMERCIAL EPROM PRODUCT
June 19, 1970 applied, May 2, 1972 Patent 3,660,819, Dov Frohman-entchkowsky,
“FLOATING GATE TRANSISTOR AND METHOD FOR CHARGING AND
DISCHARGING SAME” [Flash Memory Frohman patent EPROM]
What was new: Frohman of Intel achieved the write-in by an avalanche effect and
the erase by applying ultra-violet light.
In 1971, Intel offered the first commercial product named EPROM (Electrically
Programmable Read Only Memory). [Re3f: Flash Memory Frohman Intel1702 of
1971 Intel Museum Exhibit]
1971
ERASE by AVANNCHE EFFECT
Yasuo Tarui, Yutaka Hayashi, and Kiyoko Nagai of ELECTROTECHNICAL
LABORATORY in Tsukuba, Japan, ”Proposal of Electrically Reprogrammable,
Nonvolatile Semiconductor Memory” Proc. 3rd Conf. on Solid State Devices, Tokyo,
p.155 (1971) [Flash Memory Tarui paper]
What was new: The first attempt to use avalanche effect for erasing, thus do both
write-in and erase electrically, not by UV radiation.
1977-1982
•
•
•
1977 EEPROM PROTOTYPE
1982 COMMERCIAL PRODUCT
Filed: Feb. 22, 1977: Sep 26, 1978 US Pat. 4,115,914, Eli Harai “ELECTRICALLY ERASABLE NONVOLATILE SEMICONDUCTOR MEMORY” [Flash Memory Harari patent]
•
(Quote from the SCV's Nomination): 1967: Harari (of Hughes) invents the first practical Floating Gate
EEPROM, an electrically-erasable floating gate device using a thin gate oxide at a range of 100 Å, and which
included the use of Fowler-Nordheim tunneling for both write and erase operations. Importantly, the
practicality of this Floating Gate EEPROM resulted from (1) the fact that this thin SiO2 was sufficiently thick
(approx. 70-100 Ã…) to indefinitely store a floating gate charge for data storage, and (2) the use of polysilicon
floating gates which were widely adopted in EPROM devices.
In 1982 Hughes offered a Hughes3108 commercial EEPROM product.
(Quote from Wikipedia)
In 1988, SanDisk Corporation (NASDAQ: SNDK) was founded by Dr. Eli Harari and Sanjay Mehrotra. It
subsequently commercially offered EEPROM. [Flash Memory Harari San Disk 1988 Wikipidia]
•
•
•
•
•
•
What was new: no new development nor event
(Kawamoto’s Comments):
Above statements in the Nomination are substantially incorrect. (1) Harari’s patent was not filed in 1976, it
was filed in 1977. (2) Harari did not “invent” the first practical Floating Gate EEPROM, an electricallyerasable floating gate device which included the use of Fowler-Nordheim tunneling for both write and erase
operations. Rather, as shown in the the 1967 Section above, this basic structure was “invented” by Kahng and
Sze back in 1967. (3) Nothing new about the use of thin silicon dioxide. There were a lot of research going on
silicon dioxide in late 1960s and early 1970s; just to mention a few, started fom M.A. Atalla of Bell Lab (1960),
E.H.Snow of Fairchild (1965), and even Andy Grove’s 1967 text book “Physics and Technology of
Semiconductor Devices;” then the Director of Fairchild Research Lab. The use of silicon dioxide in silicon
devices had already been a subject of Nobel Prize (J.S.Kilby). Nothing new about the use of polysilicon for
the floating gate. As the Nominator says, it was already widely been used in non-volatile memories in 1970s.
(4) Harari ‘s device was not “the first practical” EEPROM; because it did not become a commercial offered
product right after his work in 1977. In 1979 Harari left Hughes, and in 1982 remaining engineers offered a
Hughes3108 commercial product [Flash Memory Harari Hughes3108].
1978-1980
• 1980
• COMMERCIALLY OFFERED EEPROM
• -Dec 15, 1978 applied, May 13, 1980, US Patent 4,230,158, Dov FrohmanBentchkowsky, Jerry Mar, George Perlegos, William S. Johnson of Intel,
"Electrically programmable and erasable MOS floating memory device
employing tunneling and method of fabricating same" [Flash Memory
Frohman patent EEPROM]
• -In 1980 Intel introduces an industry first Electrically Programmable Read
Only Memory Intel 2816 [Flash Memory Frohman Intel 2816, Intel Museum
Exhibit]
• What was new: The first commercially offered EEPROM
• Frohman-Bentchkowsky, et al. improved the method of erasing by using the
Fowler-Nordheim tunneling effect for injecting holes to the floating gate, thus
does not deteriorate the insulator layer while erasing. Though the basic
structure had been firstly proposed by Kahng and Sze back in 1967, this was
the first commercial product that realized the proposal.
1981-1987
1981
FLASH ERASING
Nov 13, 1981 applied, Masuoka of Toshiba, US
Patent,531,203 [Flash Memory Matsuoka patent Flash}
What was new: The idea of easing in a flash motion was
proposed.
Masuoka, et al. of Toshiba proposed an erasing in one
shot a large number of bits, rather than erasing bit-by-bit. This
substantially reduced the silicon area required for memory chip
thus significantly contributed to the reduction of price of EEPROM.
1984
NAMING of FLASH MEMORY
Their 1984 IEDM paper coined the name “flash memory.” The name was created
because the erasure of a large number of bits in one shot reminded them the flash
of camera. [Flash Memory Matsuoka paper 1984 IEDM]
1987
COMMERCIALLY OFFERED FLASH MEMORY
What was new: In 1987, Toshiba commercially offered the first flash memory
product. [Flash Memory Masuoka Press Release Toshiba]
1987-1991
• 1987
• USE of NAND FORMAT
• Matsuoka, et al. of Toshiba
proposed to use NAND circuit for
EEPROM. This further reduced
the silicon area required for a
memory chip. [Flash Memory
Matsuoka paper 1987 IEDM]
• 1991
• COMMERCIALLY OFFERED
NAND MEMORY
• Toshiba offered the first
commercial NAND type flash
memory product. [Flash Memory
Matsuoka NAND Press Release]
Flash Memory World-Wide Shipment
IHS iSuppli
NAND flash shipment by company
IHS iSuppli
NOR flash shipment by company
IHS iSuppli