US20010006474A1 - FeRAM configuration - Google Patents
FeRAM configuration Download PDFInfo
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- US20010006474A1 US20010006474A1 US09/756,085 US75608501A US2001006474A1 US 20010006474 A1 US20010006474 A1 US 20010006474A1 US 75608501 A US75608501 A US 75608501A US 2001006474 A1 US2001006474 A1 US 2001006474A1
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- 239000003990 capacitor Substances 0.000 claims abstract description 72
- 239000000463 material Substances 0.000 claims description 14
- 229910052751 metal Inorganic materials 0.000 claims description 6
- 239000002184 metal Substances 0.000 claims description 6
- 229910052741 iridium Inorganic materials 0.000 claims description 3
- 229910052763 palladium Inorganic materials 0.000 claims description 3
- 229910052697 platinum Inorganic materials 0.000 claims description 3
- 229910052707 ruthenium Inorganic materials 0.000 claims description 3
- 229910052737 gold Inorganic materials 0.000 claims description 2
- 229910052703 rhodium Inorganic materials 0.000 claims description 2
- 210000000352 storage cell Anatomy 0.000 abstract 1
- 230000010287 polarization Effects 0.000 description 7
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 6
- 239000003989 dielectric material Substances 0.000 description 6
- 238000000034 method Methods 0.000 description 3
- 235000012239 silicon dioxide Nutrition 0.000 description 3
- 239000000377 silicon dioxide Substances 0.000 description 3
- 229910052782 aluminium Inorganic materials 0.000 description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 2
- 239000010955 niobium Substances 0.000 description 2
- 229910021420 polycrystalline silicon Inorganic materials 0.000 description 2
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229910052758 niobium Inorganic materials 0.000 description 1
- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium atom Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 1
- 229910052721 tungsten Inorganic materials 0.000 description 1
- 239000010937 tungsten Substances 0.000 description 1
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Classifications
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10B—ELECTRONIC MEMORY DEVICES
- H10B53/00—Ferroelectric RAM [FeRAM] devices comprising ferroelectric memory capacitors
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11C—STATIC STORES
- G11C11/00—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor
- G11C11/21—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using electric elements
- G11C11/22—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using electric elements using ferroelectric elements
Definitions
- the present invention relates to an FeRAM (ferroelectric random access memory) configuration having a multiplicity of memory cells, each of which has a selection transistor and a capacitor device with a ferroelectric dielectric.
- FeRAM ferroelectric random access memory
- the capacitor device includes at least two capacitors whose coercive voltages differ from one another.
- a FeRAM configuration having a plurality of memory cells.
- Each one of the plurality of memory cells includes: a selection transistor; a capacitor device including at least two capacitors; and a common storage node connection connecting the at least two capacitors to the selection transistor.
- Each one of the at least two capacitors has a coercive voltage differing from others of the at least two capacitors, and each one of the at least two capacitors includes a ferroelectric dielectric.
- the invention thus takes a completely different path from the prior art: instead of making a FeRAM memory cell with a selection transistor and a (storage) capacitor to be as small as possible by specific technological measures, as would intrinsically be expected, a plurality of capacitors are assigned to each selection transistor. If a memory cell has, for example, one selection transistor and two capacitors, then it can store two bits. Compared with a conventional memory cell including a selection transistor and a capacitor with which one bit can be stored, the space requirement for storing a bit is thus practically halved since the novel memory cell takes up hardly any more area than the existing memory cell.
- the FeRAM configuration according to the invention first exploits the fact that the coercive voltage of a capacitor depends on the material of the dielectric and also on the layer thickness thereof. By appropriately selecting the material and/or the layer thickness, it is then possible to assign to a selection transistor, capacitors having different coercive voltages.
- the capacitors are provided in parallel with one another, so that information can be written serially to these capacitors independently of one another or can be read serially from these capacitors independently of one another.
- a memory cell having one selection transistor and two capacitors C 1 and C 2 shall be considered for this purpose.
- the capacitor C 1 shall have a coercive voltage VC 1 and the capacitor C 2 a coercive voltage VC 2 , where VC 1 ⁇ VC 2 , which can be achieved by an appropriately choosing the material for the dielectrics and/or different layer thicknesses for the dielectrics.
- the ferroelectric dielectric of the capacitor C 2 is not already subjected to polarization reversal to a large extent when a voltage of less than VC 2 is applied. Small polarization losses are acceptable, however, since the capacitor C 2 can only be influenced through two switching operations (writing and reading) by the capacitor C 1 . It shall be emphasized that if this precondition is fulfilled well, it is also possible to provide more than two capacitors with a “staggered” coercive voltage VC in a memory cell in order to store more than two bits per selection transistor.
- Preferred dielectrics for the capacitors are SrBi 2 Ta 2 O 9 (SBT) SrBi 2 (Ta 1-x Nb x ) 2 O 9 (SBTN) or other SBT derivatives, PbZr 1-x Ti x O 3 (PZT) or PbZr 1-x Ti x La y O 3 .
- Suitable layer thicknesses of the dielectric are about 30-250 nm, preferably approximately 180 nm.
- Pt, Ir, Ru, Pd or oxides thereof or LaSrCoO x or LaSnO x can be used for the electrodes of the capacitors.
- the capacitors may have a common connection (“plug”) with, if appropriate, common storage nodes.
- plug common connection
- the storage node or nodes may also be connected to the selection transistor via a metal clip.
- FIG. 1 shows a schematic sectional illustration of a first exemplary embodiment of the invention with a common storage node
- FIG. 2 shows a schematic sectional illustration of a second exemplary embodiment of the invention with separate storage nodes and separate common plates
- FIG. 3 shows a schematic sectional illustration of a third exemplary embodiment of the invention with a metal clip between a common storage node of the capacitors and the selection transistor.
- FIG. 1 there is diagrammatically shown a silicon semiconductor body 1 , in which there is provided a selection transistor with source 2 and drain 3 .
- a word line WL is guided between the source 2 and the drain 3 in an insulating layer (not shown) and is made, for example, of silicon dioxide.
- Drain 3 is connected via a common plug 4 made, for example, of metal, such as e.g. tungsten or aluminum, or doped polycrystalline silicon to a storage node 5 of two stacked capacitors C 1 , C 2 .
- the first stacked capacitor C 1 includes a first common plate 8 , a first dielectric 6 and the storage node 5
- the second stacked capacitor C 2 includes a second common plate 9 , a second dielectric 7 and the storage node 5 .
- the plates 8 , 9 can be connected to one another.
- the dielectrics 6 , 7 are chosen or configured in such a way that the coercive voltage VC 1 of the capacitor C 1 differs from the coercive voltage VC 2 of the capacitor C 2 . As was explained in the introduction, this can be achieved by means of different layer thicknesses and/or different materials of the dielectrics 6 , 7 . Suitable materials are e.g. SBT, SBTN, PZT and PLZT, while an expedient layer thickness range is 30-250 nm, preferably about 180 nm. It goes without saying, however, that other layer thicknesses are also possible.
- SBT and SBTN have coercive voltages VC of 0.65 V (SBT) and 1 V (SBTN).
- Suitable materials for the capacitor electrodes are Pt, Pd, Rh, Au, Ir, Ru, oxides thereof, LaSrCoO x and LaSuO x .
- Another possible variant is one in which a common plate (such as the storage node 5 ) is provided in the “center” of the stack and two storage nodes (corresponding to the plates 8 , 9 ) are connected to the plug 4 .
- a common plate such as the storage node 5
- two storage nodes corresponding to the plates 8 , 9
- FIG. 2 shows an exemplary embodiment in which the two capacitors C 1 , C 2 have different storage nodes 11 , 12 , which are connected to the plug 4 , and also have plates 8 , 9 .
- the capacitors are isolated from one another by an insulating layer (not specifically illustrated) made, for example, of silicon dioxide.
- FIG. 3 shows an exemplary embodiment in which a common storage node 5 is connected to drain 3 via a metal clip made of a plug 16 (for example made of doped polycrystalline silicon or aluminum) .
- a contact 12 made of the same material as contact 13 ) to a bit line 14 is additionally illustrated here.
- the capacitors C 1 , C 2 of this exemplary embodiment can also be modified in the manner explained above for the variant with regard to FIG. 1 and for the exemplary embodiment of FIG. 2.
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- Computer Hardware Design (AREA)
- Semiconductor Memories (AREA)
- Dram (AREA)
Abstract
Description
- CROSS-REFERENCE TO RELATED APPLICATION:
- This is a continuation of copending International Application PCT/DE U.S. Pat. No. 99/01905, filed Jul. 1, 1999, which designated the United States.
- 1. Field of the Invention:
- The present invention relates to an FeRAM (ferroelectric random access memory) configuration having a multiplicity of memory cells, each of which has a selection transistor and a capacitor device with a ferroelectric dielectric.
- As is known, in FeRAM configurations information is stored by polarization in the ferroelectric dielectric of the capacitors of memory cells. This exploits the fact that ferroelectric dielectrics have a hysteresis, so that with the presence of voltage “zero” information can be permanently stored in accordance with the two polarization states that are present.
- In order to switch the polarization and thus also the information from one state to the other state, a certain minimum voltage, the so-called coercive voltage Vc, must be applied to the capacitor.
- 2. Summary of the Invention:
- It is accordingly an object of the invention to provide a FeRAM configuration with the smallest possible space requirement per memory cell, and in which the least possible space is required for storing a bit.
- In the case of an FeRAM configuration of the type mentioned in the introduction, this object is achieved according to the invention by virtue of the fact that the capacitor device includes at least two capacitors whose coercive voltages differ from one another.
- With the foregoing and other objects in view there is provided, in accordance with the invention a FeRAM configuration having a plurality of memory cells. Each one of the plurality of memory cells includes: a selection transistor; a capacitor device including at least two capacitors; and a common storage node connection connecting the at least two capacitors to the selection transistor. Each one of the at least two capacitors has a coercive voltage differing from others of the at least two capacitors, and each one of the at least two capacitors includes a ferroelectric dielectric.
- The invention thus takes a completely different path from the prior art: instead of making a FeRAM memory cell with a selection transistor and a (storage) capacitor to be as small as possible by specific technological measures, as would intrinsically be expected, a plurality of capacitors are assigned to each selection transistor. If a memory cell has, for example, one selection transistor and two capacitors, then it can store two bits. Compared with a conventional memory cell including a selection transistor and a capacitor with which one bit can be stored, the space requirement for storing a bit is thus practically halved since the novel memory cell takes up hardly any more area than the existing memory cell.
- The FeRAM configuration according to the invention first exploits the fact that the coercive voltage of a capacitor depends on the material of the dielectric and also on the layer thickness thereof. By appropriately selecting the material and/or the layer thickness, it is then possible to assign to a selection transistor, capacitors having different coercive voltages. The capacitors are provided in parallel with one another, so that information can be written serially to these capacitors independently of one another or can be read serially from these capacitors independently of one another.
- For a more detailed explanation, a memory cell having one selection transistor and two capacitors C1 and C2 shall be considered for this purpose. In this case, the capacitor C1 shall have a coercive voltage VC1 and the capacitor C2 a coercive voltage VC2, where VC1<VC2, which can be achieved by an appropriately choosing the material for the dielectrics and/or different layer thicknesses for the dielectrics.
- In the course of writing information, first information is written to the capacitor C2 with a high voltage U, which is greater than VC2. During this writing operation, information possibly still present in the capacitor C1 is also destroyed. A lower voltage, lying between VC1 and VC2 is subsequently applied to the memory cell. Through this lower voltage, information is written to the capacitor C1, while the capacitor C2, however, is no longer switched. As a result, different information can be stored in the two capacitors C1 and C2.
- When information is read from this memory cell, the procedure is reversed: first a low voltage, lying between VC1 and VC2, is applied to the memory cell. Through this low voltage, the capacitor C1 is switched, so that its polarization current can be measured and hence the stored polarization direction can be determined. A high voltage U, which is greater than VC2, is subsequently applied. As a result, the information is read from the capacitor C2 in a corresponding manner. The information can then readily be written back to the capacitors in accordance with the above procedure.
- Although the FeRAM configuration according to the invention is slower than existing configurations due to the serial reading and writing, this disadvantage can nonetheless be accepted in many applications if a particularly small space requirement is sought.
- In order to reinforce the above example, it is important in the case of the FeRAM configuration according to the invention that the ferroelectric dielectric of the capacitor C2 is not already subjected to polarization reversal to a large extent when a voltage of less than VC2 is applied. Small polarization losses are acceptable, however, since the capacitor C2 can only be influenced through two switching operations (writing and reading) by the capacitor C1. It shall be emphasized that if this precondition is fulfilled well, it is also possible to provide more than two capacitors with a “staggered” coercive voltage VC in a memory cell in order to store more than two bits per selection transistor.
- Preferred dielectrics for the capacitors are SrBi2Ta2O9 (SBT) SrBi2(Ta1-xNbx)2O9(SBTN) or other SBT derivatives, PbZr1-xTixO3 (PZT) or PbZr1-xTixLayO3. Suitable layer thicknesses of the dielectric are about 30-250 nm, preferably approximately 180 nm. Pt, Ir, Ru, Pd or oxides thereof or LaSrCoOx or LaSnOx can be used for the electrodes of the capacitors.
- The capacitors may have a common connection (“plug”) with, if appropriate, common storage nodes. However, it is also possible for the capacitors to have different storage nodes and different common plates and to be isolated from one another by an intermediate insulating layer made, for example, of silicon dioxide. The storage node or nodes may also be connected to the selection transistor via a metal clip.
- Other features which are considered as characteristic for the invention are set forth in the appended claims.
- Although the invention is illustrated and described herein as embodied in a FeRAM configuration, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
- The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.
- FIG. 1 shows a schematic sectional illustration of a first exemplary embodiment of the invention with a common storage node;
- FIG. 2 shows a schematic sectional illustration of a second exemplary embodiment of the invention with separate storage nodes and separate common plates; and
- FIG. 3 shows a schematic sectional illustration of a third exemplary embodiment of the invention with a metal clip between a common storage node of the capacitors and the selection transistor.
- In the figures of the drawing, mutually corresponding parts are each provided with the same reference symbols. Moreover, insulating layers are not shown in order to improve the clarity. Referring now to the figures of the drawing in detail and first, particularly, to FIG. 1 thereof, there is diagrammatically shown a
silicon semiconductor body 1, in which there is provided a selection transistor withsource 2 anddrain 3. A word line WL is guided between thesource 2 and thedrain 3 in an insulating layer (not shown) and is made, for example, of silicon dioxide.Drain 3 is connected via acommon plug 4 made, for example, of metal, such as e.g. tungsten or aluminum, or doped polycrystalline silicon to astorage node 5 of two stacked capacitors C1, C2. The first stacked capacitor C1 includes a firstcommon plate 8, a first dielectric 6 and thestorage node 5, and the second stacked capacitor C2 includes a second common plate 9, a second dielectric 7 and thestorage node 5. Theplates 8, 9 can be connected to one another. - The
dielectrics dielectrics - By way of example, given a voltage of 3 V and a layer thickness of 180 nm, SBT and SBTN (with a niobium proportion of 28%) have coercive voltages VC of 0.65 V (SBT) and 1 V (SBTN).
- Suitable materials for the capacitor electrodes, that is to say the
common plates 8, 9, and thestorage node 5 are Pt, Pd, Rh, Au, Ir, Ru, oxides thereof, LaSrCoOx and LaSuOx. - Another possible variant is one in which a common plate (such as the storage node5) is provided in the “center” of the stack and two storage nodes (corresponding to the
plates 8, 9) are connected to theplug 4. - The specified materials apply to all the exemplary embodiments.
- FIG. 2 shows an exemplary embodiment in which the two capacitors C1, C2 have
different storage nodes 11, 12, which are connected to theplug 4, and also haveplates 8, 9. In this case, the capacitors are isolated from one another by an insulating layer (not specifically illustrated) made, for example, of silicon dioxide. - FIG. 3 shows an exemplary embodiment in which a
common storage node 5 is connected to drain 3 via a metal clip made of a plug 16 (for example made of doped polycrystalline silicon or aluminum) . A contact 12 (made of the same material as contact 13) to abit line 14 is additionally illustrated here. The capacitors C1, C2 of this exemplary embodiment can also be modified in the manner explained above for the variant with regard to FIG. 1 and for the exemplary embodiment of FIG. 2.
Claims (12)
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE19830569.9 | 1998-07-08 | ||
DE19830569A DE19830569C1 (en) | 1998-07-08 | 1998-07-08 | Fe-RAM arrangement having number of storage cells |
PCT/DE1999/001905 WO2000003395A1 (en) | 1998-07-08 | 1999-07-01 | Ferroelectric ram arrangement |
Related Parent Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/DE1999/001905 Continuation WO2000003395A1 (en) | 1998-07-08 | 1999-07-01 | Ferroelectric ram arrangement |
Publications (2)
Publication Number | Publication Date |
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US20010006474A1 true US20010006474A1 (en) | 2001-07-05 |
US6438019B2 US6438019B2 (en) | 2002-08-20 |
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Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US09/756,085 Expired - Fee Related US6438019B2 (en) | 1998-07-08 | 2001-01-08 | Ferroelectric random access memory (FeRAM) having storage capacitors with different coercive voltages |
Country Status (8)
Country | Link |
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US (1) | US6438019B2 (en) |
EP (1) | EP1095377B1 (en) |
JP (1) | JP2002520842A (en) |
KR (1) | KR100629025B1 (en) |
CN (1) | CN1153218C (en) |
DE (2) | DE19830569C1 (en) |
TW (1) | TW426995B (en) |
WO (1) | WO2000003395A1 (en) |
Families Citing this family (26)
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DE10010288C1 (en) | 2000-02-25 | 2001-09-20 | Infineon Technologies Ag | Ferroelectric capacitor device manufacturing method - has ferroelectric layer of varying thickness applied to electrode structure with different height levels |
JP2001298162A (en) * | 2000-04-12 | 2001-10-26 | Sony Corp | Nonvolatile semiconductor memory device |
KR100389032B1 (en) * | 2000-11-21 | 2003-06-25 | 삼성전자주식회사 | Ferroelectric memory device and method for forming the same |
WO2002075780A2 (en) | 2001-03-21 | 2002-09-26 | Koninklijke Philips Electronics N.V. | Electronic device having dielectric material of high dielectric constant |
TW571403B (en) * | 2001-06-22 | 2004-01-11 | Matsushita Electric Ind Co Ltd | Semiconductor device and the driving method |
DE10131625B4 (en) * | 2001-06-29 | 2006-06-14 | Infineon Technologies Ag | Method for producing a FeRAM memory |
US6714435B1 (en) * | 2002-09-19 | 2004-03-30 | Cova Technologies, Inc. | Ferroelectric transistor for storing two data bits |
US6888736B2 (en) * | 2002-09-19 | 2005-05-03 | Cova Technologies, Inc. | Ferroelectric transistor for storing two data bits |
KR100583090B1 (en) * | 2003-05-30 | 2006-05-23 | 주식회사 하이닉스반도체 | Manufacturing method of capacitor of the ferroelectric register |
JP3961994B2 (en) * | 2003-07-28 | 2007-08-22 | 株式会社東芝 | Semiconductor memory device |
JP2005190565A (en) * | 2003-12-25 | 2005-07-14 | Seiko Epson Corp | Ferroelectric memory device, electronic equipment and driving method |
US7196924B2 (en) * | 2004-04-06 | 2007-03-27 | Macronix International Co., Ltd. | Method of multi-level cell FeRAM |
JP4088975B2 (en) * | 2004-07-14 | 2008-05-21 | セイコーエプソン株式会社 | Ferroelectric memory device and electronic device |
JP2006108291A (en) * | 2004-10-04 | 2006-04-20 | Seiko Epson Corp | Ferroelectric capacitor and its manufacturing method, and ferroelectric memory device |
JP2008066603A (en) * | 2006-09-08 | 2008-03-21 | Toshiba Corp | Semiconductor memory device and its manufacturing method |
US7936597B2 (en) * | 2008-03-25 | 2011-05-03 | Seagate Technology Llc | Multilevel magnetic storage device |
US8098520B2 (en) * | 2008-04-25 | 2012-01-17 | Seagate Technology Llc | Storage device including a memory cell having multiple memory layers |
US7916513B2 (en) * | 2008-11-05 | 2011-03-29 | Seagate Technology Llc | Non-destructive read back for ferroelectric data storage device |
WO2013065493A1 (en) * | 2011-11-04 | 2013-05-10 | 株式会社村田製作所 | Impact detection and recording device |
US9219225B2 (en) * | 2013-10-31 | 2015-12-22 | Micron Technology, Inc. | Multi-bit ferroelectric memory device and methods of forming the same |
DE102015015854B4 (en) * | 2015-12-03 | 2021-01-28 | Namlab Ggmbh | Integrated circuit with a ferroelectric memory cell and use of the integrated circuit |
DE102016012071A1 (en) | 2016-10-10 | 2018-04-12 | Kai-Uwe Demasius | Matrix with capacitive control device |
WO2018069359A1 (en) | 2016-10-10 | 2018-04-19 | Demasius Kai Uwe | Capacitive matrix arrangement and method for actuation thereof |
CN108550576B (en) * | 2018-04-18 | 2020-09-11 | 湘潭大学 | Nonvolatile ferroelectric random access memory and preparation process |
CN111211135B (en) * | 2020-01-16 | 2022-08-05 | 华中科技大学 | Modulation method of asymmetric ferroelectric tunneling junction multi-value storage unit |
CN116195378A (en) * | 2020-11-04 | 2023-05-30 | 华为技术有限公司 | Ferroelectric memory and memory device |
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DE4041271C2 (en) * | 1989-12-25 | 1998-10-08 | Toshiba Kawasaki Kk | Semiconductor device with a ferroelectric capacitor |
DE4118847A1 (en) * | 1990-06-08 | 1991-12-12 | Toshiba Kawasaki Kk | Semiconductor DRAM with matrix of cells coupled to driver leads - has read=out amplifiers connected and selectable by column address |
US5291436A (en) * | 1991-07-25 | 1994-03-01 | Rohm Co., Ltd. | Ferroelectric memory with multiple-value storage states |
US5189594A (en) * | 1991-09-20 | 1993-02-23 | Rohm Co., Ltd. | Capacitor in a semiconductor integrated circuit and non-volatile memory using same |
JPH07122661A (en) * | 1993-10-27 | 1995-05-12 | Olympus Optical Co Ltd | Ferroelectric memory device |
JPH0722595A (en) * | 1993-06-22 | 1995-01-24 | Mitsubishi Electric Corp | Semiconductor device and manufacture thereof |
US5572459A (en) * | 1994-09-16 | 1996-11-05 | Ramtron International Corporation | Voltage reference for a ferroelectric 1T/1C based memory |
JPH08180673A (en) * | 1994-12-27 | 1996-07-12 | Nec Corp | Ferroelectric memory cell and access device therefor |
KR100326586B1 (en) * | 1995-09-21 | 2002-07-22 | 삼성전자 주식회사 | Method for preventing polarization inversion phenomenon of ferroelectric capacitor |
TW322578B (en) * | 1996-03-18 | 1997-12-11 | Matsushita Electron Co Ltd | |
JPH1093030A (en) * | 1996-09-17 | 1998-04-10 | Toshiba Corp | Ferroelectric nonvolatile memory |
-
1998
- 1998-07-08 DE DE19830569A patent/DE19830569C1/en not_active Expired - Fee Related
-
1999
- 1999-06-30 TW TW088111053A patent/TW426995B/en not_active IP Right Cessation
- 1999-07-01 EP EP99942725A patent/EP1095377B1/en not_active Expired - Lifetime
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2001
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TW426995B (en) | 2001-03-21 |
DE59905479D1 (en) | 2003-06-12 |
JP2002520842A (en) | 2002-07-09 |
KR100629025B1 (en) | 2006-09-26 |
US6438019B2 (en) | 2002-08-20 |
CN1316086A (en) | 2001-10-03 |
EP1095377A1 (en) | 2001-05-02 |
WO2000003395A1 (en) | 2000-01-20 |
KR20010053429A (en) | 2001-06-25 |
DE19830569C1 (en) | 1999-11-18 |
EP1095377B1 (en) | 2003-05-07 |
CN1153218C (en) | 2004-06-09 |
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