Data storage device and refreshing method for use with such device

Information

  • Patent Grant
  • 7342842
  • Patent Number
    7,342,842
  • Date Filed
    Friday, January 5, 2007
    17 years ago
  • Date Issued
    Tuesday, March 11, 2008
    16 years ago
Abstract
A data storage device such as a DRAM memory having a plurality of data storage cells 10 is disclosed. Each data storage cell 10 has a physical parameter which varies with time and represents one of two binary logic states. A selection circuit 16, writing circuits 18 and a refreshing circuit 22 apply input signals to the data storage cells to reverse the variation of the physical parameter with time of at least those cells representing one of the binary logic states by causing a different variation in the physical parameter of cells in one of said states than in the other.
Description
TECHNICAL FIELD OF THE INVENTION

The present invention relates to a data storage device, and relates particularly, but not exclusively, to a semiconductor memory device. The invention also relates to a method of refreshing a data storage device.


BACKGROUND OF THE INVENTION

DRAM (Dynamic Random Access Memory) devices are known in which an array of charge storage cells is provided, each storage cell consisting of a single transistor and a single capacitor. As is well known, each storage cell stores a single binary data bit according to whether the associated capacitor is charged (data state “1”) or discharged (data state “0”). It is also well known that the charge stored in the charged capacitors decays with time, and that it is therefore necessary to rewrite the data to the charged storage cells by periodically recharging the capacitors. A conventional DRAM arrangement of this type is shown in FIG. 1. The DRAM device shown in FIG. 1 is provided with m columns and n rows. A data storage cell 10 consisting of a single transistor and a single capacitor is located at each intersection of a row and a column.


For each data storage cell, the source of the associated transistor is connected to one terminal of a capacitor, the other terminal of which is connected to a ground terminal or a given reference voltage (not shown), the gates of the transistors of each row are connected together by a respective conductive track 12, and the drains of the transistors of each column are connected together by a respective conductive track 14. Each of the conductive tracks 12 is connected to a selection circuit 16 for sequentially scanning the conductive tracks 12 of the memory device, and the conductive tracks 14 are each connected to respective writing circuits 18i and reading circuits 20i, where i varies from 1 to m.


In order to refresh the charge states of the data storage cells 10 to counteract the effect of the charge stored in each capacitor decaying with time, the selection circuit 16 scans lines 1 to n by sequentially applying a signal to each conductive track 12 to successively switch on the transistors of all of the data storage cells 10 connected to the conductive track 12 being addressed. This in turn enables the reading circuits 20i to determine the charge state of the associated capacitor by determining the current flowing through each transistor. In response to the determination of the charge state of each capacitor determined by the associated reading circuit 20i, the associated writing circuit 18i causes the capacitor to be recharged or not, depending on its previous charge state.


Prior art DRAM devices of the type shown in FIG. 1 suffer from the drawback that modern memory devices have capacities typically of the order of 1 Gb, such devices typically comprising 1048576 lines. The refreshing process typically requires 10 to 50 ns for each line, as a result of which the refreshing process for a 1 Gb device typically requires 10 to 50 ms. Since the refreshing process must typically be carried out about 10 times per second, the time necessary for the refreshing process is of the same order of magnitude as that remaining for the data reading and writing operations. This results in the time required for refreshing limiting the capacity of the memory devices and requiring that special steps be taken to reduce leakage currents.


Preferred embodiments of the present invention seek to overcome the above disadvantages of the prior art.


SUMMARY OF THE INVENTION

According to an aspect of the present invention, there is provided a data storage device comprising:


a plurality of data storage cells, each said cell having a physical parameter in use which varies with time and has one of two data representing states, each said data representing state representing a respective binary logic state; and


refreshing means for applying input signals to each said data storage cell to at least partially reverse variation of said physical parameter with time of at least those data storage cells in a predetermined one of said states, wherein said input signals cause a different variation in said physical parameter in cells in one of said data representing states than the variation caused in cells in the other of said data representing states.


Data refreshing means are provided to at least partially reverse the variation of said physical parameter with time by means of input signals causing a different variation in said physical parameter in cells in one of said data representing states than the variation caused in cells in the other of said data representing states. This provides the advantage that each data storage cell can be re-written without the need to read the state of each cell in order to enable the re-write operation to proceed. In addition, the write signal can be input to all data storage cells simultaneously, thus significantly increasing the speed of the refreshing operation compared with prior art devices.


In a preferred embodiment, said at least partial reversal of said physical parameter occurs to a greater extent for said cells in said predetermined one of said data representing states than in the other of said states, and said input signals are applied sufficiently frequently in use that said states remain distinguishable from each other.


The device may further comprise writing means for applying input signals to each said data storage cell to adjust said physical parameter of said cell to select the binary logic state represented by each said data storage cell.


The device may further comprise reading means for determining the data representing state of each said data storage cell.


Said input signals may at least partially reverse variation of said physical parameter for cells in each of said data representing states.


The data storage device may be a semiconductor device.


In a preferred embodiment, at least some of said data storage cells each comprise a respective field effect transistor having a first threshold voltage when in said first state and a second threshold voltage when in said second state.


In a preferred embodiment, at least one said field effect transistor comprises a respective source, a respective drain, a respective body arranged between the corresponding said source and said drain and adapted to retain an electrical charge generated in said body representing one or the other of two binary data states, and at least one respective gate adjacent the corresponding said body, wherein said refreshing means is adapted to apply voltage signals between at least one said gate and said drain of each said cell lying between said first and second threshold voltages.


Said refreshing means may be adapted to also apply signals to at least partially reverse the variation of said physical parameter in the other of said data representing states.


Said refreshing means is preferably adapted to apply signals partially reversing the variation of said charge in the other of said data representing states by means of recombination of charge carriers with charge carriers of opposite polarity.


The device may be a memory device.


According to another aspect of the present invention, there is provided a method of refreshing data in a data storage device comprising a plurality of data storage cells, each said cell having a physical parameter in use which varies with time and has one of two data representing states, each said data representing state representing a respective binary logic state, the method comprising applying input signals to each said data storage cell to at least partially reverse variation of said physical parameter with time of at least those data storage cells in a predetermined one of said states, wherein said input signals cause a different variation in said physical parameter in cells in one of said data representing states than the variation caused in cells in the other of said data representing states.


Said input signals may cause said at least partial reversal of said physical parameter occurs to a greater extent for said cells in said predetermined one of said data representing states than in the other of said states.


The method may further comprise the step of applying signals to at least partially reverse the variation of said physical parameter in the other of said data representing states.


The step of applying signals to at least partially reverse the variation of said physical parameter in the other of said data representing states preferably causes recombination of charge carriers with charge carriers of opposite polarity.


Said input signals may at least partially reverse variation of said physical parameter for cells in each of said data representing states.





BRIEF DESCRIPTION OF THE DRAWINGS

A preferred embodiment of the invention will now be described, by way of example only and not in any limitative sense, with reference to the accompanying drawings, in which:



FIG. 1 is a schematic representation of a prior art DRAM memory device;



FIG. 2 is a schematic representation, corresponding to FIG. 1, of a DRAM device embodying the present invention;



FIG. 3 shows a pulse pattern to be applied to the gates and drains of the transistors of the device of FIG. 2 during a refresh operation; and



FIG. 4 shows the variation of charge with time in the body of each transistor of the device of FIG. 2 in each of the two charge states.



FIG. 5 is a representation of a prior art memory cell.





DETAILED DESCRIPTION

Referring to FIG. 2, in which parts common to the device of FIG. 1 are denoted by like reference numerals, a DRAM device has an array of m columns and n lines of memory cells 10, each of which comprises an NMOS SOI (silicon on insulator) field effect transistor, as described in greater detail in European patent application number 01810587.4 (which corresponds, at least in part, to U.S. Pat. No. 6,969,662). As described in greater detail in that document, it is possible to generate a charge in the body of such a transistor by the application of predetermined voltage pulses between the gate and drain and between the source and drain of the transistor. (See, for example. FIG. 5). In particular, a positive charge is generated and stored in the body of an NMOS transistor by means of the application of a voltage between the source and drain of the transistor when in its conductive state, the voltage difference between the source and drain generating electron-hole pairs by impact ionisation. The electrons are then removed to the source or drain, and the holes are stored in the body of the transistor. The positive charge can be removed by forward biasing the body-drain junction.


In the DRAM device of FIG. 2, the source of each transistor is connected to a ground terminal, the gates of the transistors of each line are connected to a conductive track 12, and the drains of the transistors of each column are connected to a conductive track 14. As in the device of FIG. 1, the conductive tracks 12 are all connected to a selection circuit 16, and a writing circuit 18i and reading circuit 20i is connected to each conducting track 14. A refreshing circuit 22 is also provided, the refreshing circuit 22 being connected to each of the conductive tracks 12 via the selection circuit, and to each of the conductive tracks 14 via the corresponding writing circuits 18i.


European patent application no. 01810587.4 describes how data can be written to the individual memory cells 10 of the DRAM device of FIG. 2, and how the charge state, representing the binary data state, of each memory cell 10 can be determined. The “zero” and “one” binary states of each stored bit are represented by the presence or absence of a net electric charge of a predetermined polarity in the body of the transistor. In order to refresh the data written to the memory cells 10, the refreshing circuit 22 causes the selection circuit 16 and writing circuit 18i to apply pulse I1 to all of the lines, and pulse I2, as shown in FIG. 3, to all of the columns.


Pulse I1 beginning at time t1 and ending at time t2 is applied to the gates of all of the transistors for a duration of some nanoseconds, and comprises a pulse of +0.6V applied to the gates, and +1.2V applied to the drains of the transistors. Pulse I2, which begins at time t3 and ends at time t4, also having a duration of some nanoseconds, consists of the application of a pulse of −2V to the gates alone. The times t2 and t3 may be coincident.


Referring now to FIG. 4, which shows in detail how the charge C stored in the transistor body of each memory cell 10 varies with time for each charge state (representing binary “0” and binary “1” states respectively), the line between the two curves indicates charge level Cn towards which both charge levels tend if no refreshing operation is carried out. It will be appreciated that the two charge levels chosen to represent the respective data states must be sufficiently far apart as to remain distinguishable from each other throughout the range of allowed variation of charge of each level.


The cells 10 initially have a net positive charge represented by holes stored in the body of the transistor (representing state “1”) or a much lower negative or substantially zero charge (representing state “0”), i.e. the two charged states being higher than or lower than charge level Cn respectively. Without a refresh operation, the difference between these two charge levels decays generally logarithmically with time.


As disclosed in more detail in earlier European patent application no. 01810587.4, the electrical properties of the SOI MOSFET transistors of each data storage cell 10 vary according to the amount of charge stored in the body of the respective transistor. In particular, the threshold voltage of transistors in the higher charge state is lower than that of the transistors in the lower charge state.


When pulse I1 is applied at time t1, the voltage applied to the gates is arranged to be between the respective threshold voltages of the transistors in the higher and lower charge states. As a result, the transistor in the higher charge state is switched to its conductive state, i.e. a conductive channel between the source and drain forms in the body of the transistor in the vicinity of the gate, and a current can flow in the channel between the source and the drain at the interface of the body and the insulating layer adjacent the gate. This current flowing in the channel creates electron and hole pairs in the vicinity of the drain by impact ionisation, the holes being stored in the body, while the electrons are removed by the drain. In this way, the positive charge stored in the body of the transistors in the higher charge state increases by an amount Δ1, while the charge of the transistors in the lower charge state increases by a much smaller amount Δ2, since no conductive channel is formed in the transistors of lower charge state. Δ1 is generally 2 to 3 orders of magnitude greater than Δ2. It is found that electrons are trapped in structural defects in the body at its interface with the insulating film between the body and the gate generally to the same extent, regardless of whether the transistors are in the higher or lower charge state.


At time t3, which is shown in FIG. 4 for the sake of clarity as being coincident with time t2, the second pulse I2 begins and causes the charge in the transistors of both charge states to be reduced. The pulse I2 consists of a voltage of −2V applied to the gates, which attracts holes stored in the body of each transistor to the corresponding interface of the body and dielectric film, with the result that the holes recombine with electrons trapped in structural defects at the interface, reducing the net positive charge stored in the body. As can be seen from FIG. 4, in this way, the charge in the higher state is reduced back to its initial level, and the charge in the lower state is restored to its previous level. The charge in the transistor in the upper state is reduced by Δ4, and is reduced by Δ3 in the transistor in the lower state, Δ4 and Δ3 being approximately equal to each other.


It can therefore be seen that because pulse I1 has a much more significant effect on transistors in the higher state than in the lower state, this pulse can be applied to all of the memory cells 10 simultaneously, with the effect that the “1” states are refreshed, without the transistors in the “0” state being converted to the “1” state and without the necessity of reading the charge state of each memory cell 10. This permits a refresh process to be made by whole memory blocks allowing, for example in the case of a 1 Gigabit memory, a refresh process approximately 1000 times faster than in the prior art. It is also possible to use transistors having technical characteristics less difficult to achieve than in the prior art, in particular, transistors having a lower charge retention time, for which the cost is consequently lower.


It will be appreciated by persons skilled in the art that the above embodiment has been described by way of example only, and not in any limitative sense, and that various alterations and modifications are possible without departure from the scope of the invention as defined by the appended claims. In particular, the order of application of pulses I1 and I2 can be reversed, and the above process described with reference to NMOS transistors can also be applied to PMOS transistors, the polarity of the voltages applied to the gates in that case being reversed. Also, JFET type transistors can be used as well as MOSFET type transistors. Furthermore, as well as being applicable to DRAM memory type devices, it will be appreciated by persons skilled in the art that the refreshing process can be applied to other types of data storage device, such as optical imaging devices and memory devices other than DRAM memories.

Claims
  • 1. A memory cell array comprising: a plurality of memory cells, including a first memory cell and a second memory cell, wherein each memory cell of the plurality of memory cells includes an associated transistor having a source region, a drain region, an electrically floating body region disposed therebetween, and a gate disposed over the electrically floating body region, and wherein each memory cell further includes a charge in the body region of the associated transistor which varies with time and a first data state representative of a first charge provided in the body region of the associated transistor, anda second data state representative of a second charge in the body region of the associated transistor; andcircuitry, coupled to the plurality of memory cells, to sequentially apply first and second electrical signals to first and second memory cells wherein: the first electrical signals are simultaneously applied to the first and second memory cells wherein, in response to the first electrical signals, (i) the first memory cell, which is in the first data state, is refreshed and (ii) the second memory cell, which is in the second data state, maintains the second data state; andthe second electrical signals are simultaneously applied to the first and second memory cells wherein, in response to the second electrical signals, (i) the first memory cell, which is in the first data state, maintains the first data state and (ii) the second memory cell, which is in the second data state, is refreshed.
  • 2. The memory cell array of claim 1 wherein, in response to the first electrical signals, the first memory cell is refreshed by increasing the number of majority carriers in the body region of the associated transistor.
  • 3. The memory cell array of claim 1 wherein the conductivity of memory cells in the first state is higher than the conductivity of memory cells in the second state.
  • 4. The memory cell array of claim 1 wherein, in response to the first electrical signals: the first memory cell includes a conductive channel in the body region of the associated transistor and between the source region and the drain region of the associated transistor; andthe second memory cell does not include a conductive channel in the body region of the associated transistor and between the source region and the drain region of the associated transistor.
  • 5. The memory cell array of claim 1 wherein, in response to the second electrical signals, the second memory cell is refreshed by reducing the number of majority carriers in the body region of the associated transistor.
  • 6. The memory cell array of claim 1 wherein the circuitry includes a refreshing circuit, a selection circuit and a writing circuit.
  • 7. The memory cell array of claim 1 wherein the second electrical signals include (1) a second gate signal applied: (i) to the gate of the transistor associated with the first memory cell and (ii) to the gate of the transistor associated with the second memory cell, and (2) a second drain signal applied: (i) to the drain region of the transistor associated with the first memory cell and (ii) to the drain region of the transistor associated with the second memory cell.
  • 8. The memory cell array of claim 1 wherein the first electrical signals include (1) a first gate signal applied: (i) to the gate of the transistor associated with the first memory cell and (ii) to the gate of the transistor associated with the second memory cell, and (2) a first drain signal applied: (i) to the drain region of the transistor associated with the first memory cell and (ii) to the drain region of the transistor associated with the second memory cell.
  • 9. A memory cell array comprising: a plurality of memory cells, each memory cell including an associated transistor having a source region, a drain region, a body region disposed therebetween, and a gate disposed over the body region and separated therefrom by a dielectric, wherein each memory cell (i) further includes a charge which is representative of a data state wherein the charge varies with time and (ii) is reversibly programmed in a first data state and/or a second data state; andcircuitry, coupled to the plurality of memory cells, to sequentially apply first and second electrical signals to the plurality of memory cells, wherein: the first electrical signals are simultaneously applied to the plurality of memory cells wherein, in response to the first electrical signals, (i) memory cells that are in the first data state are refreshed and (ii) memory cells that are in the second data state maintain the second data state; andthe second electrical signals are simultaneously applied to the plurality of memory cells wherein, in response to the second electrical signals, (i) memory cells that are in the second data state are refreshed and (ii) memory cells that are in the first data state maintain the first data state.
  • 10. The memory cell array of claim 9 wherein the circuitry includes a refreshing circuit, a selection circuit and a writing circuit.
  • 11. The memory cell array of claim 9 wherein, in response to the first electrical signals, each memory cell that is in the first data state is refreshed by increasing the charge in the body region of the associated transistor.
  • 12. The memory cell array of claim 9 wherein, in response to the first electrical signals: the transistor of each memory cell in the first data state includes a conductive channel, in the body region, between the source region and the drain region; andthe transistor of each memory cell in the second data state does not include a conductive channel, in the body region, between the source region and the drain region.
  • 13. The memory cell array of claim 9 wherein the conductivity of memory cells in the first state is higher than the conductivity of memory cells in the second state.
  • 14. The memory cell array of claim 9 wherein, in response to the second electrical signals, each memory cell that is in the second data state is refreshed by reducing the charge in the body region of the associated transistor.
  • 15. The memory cell array of claim 9 wherein the first electrical signals include (1) a first gate signal applied to the gate of the associated transistor of each memory cell of the plurality of memory cells and (2) a first drain signal applied to the drain region of the associated transistor of each memory cell of the plurality of memory cells.
  • 16. The memory cell array of claim 9 wherein the second electrical signals include (1) a second gate signal applied: (i) to the gate of the associated transistor of each memory cell of the plurality of memory cells and (ii) to the gate of the associated transistor of each memory cell of the plurality of memory cells, and (2) a second drain signal applied: (i) to the drain region of the associated transistor of each memory cell of the plurality of memory cells and (ii) to the drain region of the associated transistor of each memory cell of the plurality of memory cells.
  • 17. A memory cell array comprising: a plurality of memory cells arranged in a matrix form, each memory cell consisting essentially of an associated transistor comprising a source region, a drain region, a body region disposed therebetween, and a gate disposed over the body region and separated therefrom by a dielectric, wherein each memory cell is in (i) a first data state, or (ii) a second data state; andcircuitry, coupled to the plurality of memory cells, to apply first and second electrical signals to the plurality of memory cells, wherein: the first electrical signals are simultaneously applied to the plurality of memory cells wherein, in response to the first electrical signals, (i) memory cells that are in the first data state are refreshed and (ii) memory cells that are in the second data state maintain the second data state; andthe second electrical signals are simultaneously applied to the plurality of memory cells wherein, in response to the second electrical signals, (i) memory cells that are in the second data state are refreshed and (ii) memory cells that are in the first data state maintain the first data state.
  • 18. The memory cell array of claim 17 wherein the circuitry includes a refreshing circuit, a selection circuit and a writing circuit.
  • 19. The memory cell array of claim 17 wherein, in response to the first electrical signals, each memory cell that is in the first data state is refreshed by increasing the number of majority carriers in the body region of the associated transistor.
  • 20. The memory cell array of claim 17 wherein, in response to the first electrical signals: the transistor of each memory cell in the first data state includes a conductive channel, in the body region, between the source region and the drain region; andthe transistor of each memory cell in the second data state does not include a conductive channel, in the body region, between the source region and the drain region.
Priority Claims (2)
Number Date Country Kind
02405314 Apr 2002 EP regional
02077116 May 2002 EP regional
Parent Case Info

This application is a divisional application of application Ser. No. 11/048,387, filed Feb. 1, 2005 (now U.S. Pat. No. 7,170,807, which is a divisional application of application Ser. No. 10/487,162, filed Feb. 17, 2004 (now U.S. Pat. No. 6,982,918), which is the National Stage of International Application No. PCT/EP03/02747, filed Mar. 17, 2003, which claims priority to European Patent Application Ser. No. 02077116, filed May 29, 2002, and European Patent Application Ser. No. 02405314, filed Apr. 18, 2002.

US Referenced Citations (138)
Number Name Date Kind
3439214 Kabell Apr 1969 A
3997799 Baker Dec 1976 A
4032947 Kesel et al. Jun 1977 A
4250569 Sasaki et al. Feb 1981 A
4262340 Sasaki et al. Apr 1981 A
4298962 Hamano et al. Nov 1981 A
4371955 Sasaki Feb 1983 A
4527181 Sasaki Jul 1985 A
4630089 Sasaki et al. Dec 1986 A
4791610 Takemae Dec 1988 A
4979014 Hieda et al. Dec 1990 A
5144390 Matloubian Sep 1992 A
5164805 Lee Nov 1992 A
5258635 Nitayama et al. Nov 1993 A
5388068 Ghoshal et al. Feb 1995 A
5446299 Acovic et al. Aug 1995 A
5448513 Hu et al. Sep 1995 A
5466625 Hsieh et al. Nov 1995 A
5489792 Hu et al. Feb 1996 A
5528062 Hsieh et al. Jun 1996 A
5568356 Schwartz Oct 1996 A
5593912 Rajeevakumar Jan 1997 A
5606188 Bronner et al. Feb 1997 A
5608250 Kalnitsky Mar 1997 A
5627092 Alsmeier et al. May 1997 A
5631186 Park et al. May 1997 A
5696718 Hartmann Dec 1997 A
5740099 Tanigawa Apr 1998 A
5778243 Aipperspach et al. Jul 1998 A
5780906 Wu et al. Jul 1998 A
5784311 Assaderaghi et al. Jul 1998 A
5811283 Sun Sep 1998 A
5847411 Morii Dec 1998 A
5877978 Morishita et al. Mar 1999 A
5886376 Acovic et al. Mar 1999 A
5886385 Arisumi et al. Mar 1999 A
5897351 Forbes Apr 1999 A
5929479 Oyama Jul 1999 A
5930648 Yang Jul 1999 A
5936265 Koga Aug 1999 A
5939745 Park et al. Aug 1999 A
5943258 Houston et al. Aug 1999 A
5943581 Lu et al. Aug 1999 A
5960265 Acovic et al. Sep 1999 A
5968840 Park et al. Oct 1999 A
5977578 Tang Nov 1999 A
5982003 Hu et al. Nov 1999 A
6018172 Hidaka et al. Jan 2000 A
6081443 Morishita Jun 2000 A
6096598 Furukawa et al. Aug 2000 A
6097056 Hsu et al. Aug 2000 A
6111778 MacDonald et al. Aug 2000 A
6121077 Hu et al. Sep 2000 A
6157216 Lattimore et al. Dec 2000 A
6171923 Chi et al. Jan 2001 B1
6177300 Houston et al. Jan 2001 B1
6177708 Kuang et al. Jan 2001 B1
6214694 Leobandung et al. Apr 2001 B1
6225158 Furukawa et al. May 2001 B1
6245613 Hsu et al. Jun 2001 B1
6252281 Yamamoto et al. Jun 2001 B1
6292424 Ohsawa Sep 2001 B1
6297090 Kim Oct 2001 B1
6300649 Hu et al. Oct 2001 B1
6320227 Lee et al. Nov 2001 B1
6333532 Davari et al. Dec 2001 B1
6350653 Adkisson et al. Feb 2002 B1
6351426 Ohsawa Feb 2002 B1
6359802 Lu et al. Mar 2002 B1
6384445 Hidaka et al. May 2002 B1
6391658 Gates et al. May 2002 B1
6403435 Kang et al. Jun 2002 B1
6421269 Somasekhar et al. Jul 2002 B1
6424011 Assaderaghi et al. Jul 2002 B1
6424016 Houston Jul 2002 B1
6429477 Mandelman et al. Aug 2002 B1
6440872 Mandelman et al. Aug 2002 B1
6441435 Chan Aug 2002 B1
6441436 Wu et al. Aug 2002 B1
6466511 Fujita et al. Oct 2002 B2
6479862 King et al. Nov 2002 B1
6492211 Divakaruni et al. Dec 2002 B1
6518105 Yang et al. Feb 2003 B1
6531754 Nagano et al. Mar 2003 B1
6538916 Ohsawa Mar 2003 B2
6544837 Divakaruni et al. Apr 2003 B1
6548848 Horiguchi et al. Apr 2003 B2
6549450 Hsu et al. Apr 2003 B1
6552398 Hsu et al. Apr 2003 B2
6556477 Hsu et al. Apr 2003 B2
6566177 Radens et al. May 2003 B1
6567330 Fujita et al. May 2003 B2
6590258 Divakauni et al. Jul 2003 B2
6590259 Adkisson et al. Jul 2003 B2
6617651 Ohsawa Sep 2003 B2
6621725 Ohsawa Sep 2003 B2
6632723 Watanabe et al. Oct 2003 B2
6650565 Ohsawa Nov 2003 B1
6661042 Hsu Dec 2003 B2
6714436 Burnett et al. Mar 2004 B1
6721222 Somasekhar et al. Apr 2004 B2
6771546 Ikehashi et al. Aug 2004 B2
6861689 Burnett Mar 2005 B2
6913964 Hsu Jul 2005 B2
20010055859 Yamada et al. Dec 2001 A1
20020030214 Horiguchi Mar 2002 A1
20020034855 Horiguchi et al. Mar 2002 A1
20020036322 Divakauni et al. Mar 2002 A1
20020051378 Ohsawa May 2002 A1
20020064913 Adkisson et al. May 2002 A1
20020070411 Vermandel et al. Jun 2002 A1
20020072155 Liu et al. Jun 2002 A1
20020076880 Yamada et al. Jun 2002 A1
20020086463 Houston et al. Jul 2002 A1
20020089038 Ning Jul 2002 A1
20020098643 Kawanaka et al. Jul 2002 A1
20020110018 Ohsawa Aug 2002 A1
20020114191 Iwata et al. Aug 2002 A1
20020130341 Horiguchi et al. Sep 2002 A1
20020160581 Watanabe et al. Oct 2002 A1
20020180069 Houston Dec 2002 A1
20030003608 Arikado et al. Jan 2003 A1
20030015757 Ohsawa Jan 2003 A1
20030035324 Fujita et al. Feb 2003 A1
20030057487 Yamada et al. Mar 2003 A1
20030057490 Nagano et al. Mar 2003 A1
20030102497 Fried et al. Jun 2003 A1
20030112859 Ohsawa Jun 2003 A1
20030123279 Aipperspach et al. Jul 2003 A1
20030146488 Nagano et al. Aug 2003 A1
20030151112 Yamada et al. Aug 2003 A1
20030168677 Hsu Sep 2003 A1
20030213994 Hayashi et al. Nov 2003 A1
20040041206 Bhattacharyya Mar 2004 A1
20040041208 Bhattacharyya Mar 2004 A1
20040042268 Bhattacharyya Mar 2004 A1
20040108532 Forbes Jun 2004 A1
20050141262 Yamada et al. Jun 2005 A1
Foreign Referenced Citations (93)
Number Date Country
0 030 856 Jun 1981 EP
0 350 057 Jan 1990 EP
0 354 348 Feb 1990 EP
0 202 515 Mar 1991 EP
0 207 619 Aug 1991 EP
0 175 378 Nov 1991 EP
0 253 631 Apr 1992 EP
0 513 923 Nov 1992 EP
0 300 157 May 1993 EP
0 564 204 Oct 1993 EP
0 579 566 Jan 1994 EP
0 362 961 Feb 1994 EP
0 599 506 Jun 1994 EP
0 359 551 Dec 1994 EP
0 366 882 May 1995 EP
0 465 961 Aug 1995 EP
0 694 977 Jan 1996 EP
0 333 426 Jul 1996 EP
0 727 820 Aug 1996 EP
0 739 097 Oct 1996 EP
0 245 515 Apr 1997 EP
0 788 165 Aug 1997 EP
0 801 427 Oct 1997 EP
0 510 607 Feb 1998 EP
0 537 677 Aug 1998 EP
0 858 109 Aug 1998 EP
0 860 878 Aug 1998 EP
0 869 511 Oct 1998 EP
0 878 804 Nov 1998 EP
0 920 059 Jun 1999 EP
0 924 766 Jun 1999 EP
0 642 173 Jul 1999 EP
0 727 822 Aug 1999 EP
0 933 820 Aug 1999 EP
0 951 072 Oct 1999 EP
0 971 360 Jan 2000 EP
0 980 101 Feb 2000 EP
0 601 590 Apr 2000 EP
0 993 037 Apr 2000 EP
0 836 194 May 2000 EP
0 599 388 Aug 2000 EP
0 689 252 Aug 2000 EP
0 606 758 Sep 2000 EP
0 682 370 Sep 2000 EP
1 073 121 Jan 2001 EP
0 726 601 Sep 2001 EP
0 731 972 Nov 2001 EP
1 162 663 Dec 2001 EP
1 162 744 Dec 2001 EP
1 179 850 Feb 2002 EP
1 180 799 Feb 2002 EP
1 191 596 Mar 2002 EP
1 204 146 May 2002 EP
1 204 147 May 2002 EP
1 209 747 May 2002 EP
0 744 772 Aug 2002 EP
1 233 454 Aug 2002 EP
0 725 402 Sep 2002 EP
1 237 193 Sep 2002 EP
1 241 708 Sep 2002 EP
1 253 634 Oct 2002 EP
0 844 671 Nov 2002 EP
1 280 205 Jan 2003 EP
1 288 955 Mar 2003 EP
2 197 494 Mar 1974 FR
1 414 228 Nov 1975 GB
62-272561 Nov 1987 JP
02-294076 Feb 1991 JP
3-171768 Jul 1991 JP
8-213624 Aug 1996 JP
8-274277 Oct 1996 JP
9-046688 Feb 1997 JP
9-82912 Mar 1997 JP
10-242470 Sep 1998 JP
11-87649 Mar 1999 JP
2000-247735 Aug 2000 JP
2000-274221 Sep 2000 JP
2000-389106 Dec 2000 JP
2001-180633 Jun 2001 JP
2002-009081 Jan 2002 JP
2002-94027 Mar 2002 JP
2002-176154 Jun 2002 JP
2002-246571 Aug 2002 JP
2002-329795 Nov 2002 JP
2002-343886 Nov 2002 JP
2002-353080 Dec 2002 JP
2003-31693 Jan 2003 JP
2003-86712 Mar 2003 JP
2003-100641 Apr 2003 JP
2003-100900 Apr 2003 JP
2003-132682 May 2003 JP
2003-203967 Jul 2003 JP
2003-243528 Aug 2003 JP
Related Publications (1)
Number Date Country
20070109896 A1 May 2007 US
Divisions (2)
Number Date Country
Parent 11048387 Feb 2005 US
Child 11649945 US
Parent 10487162 US
Child 11048387 US