U.S. patent application number 14/094595 was filed with the patent office on 2015-06-04 for three-dimensional flash nor memory system with configurable pins.
This patent application is currently assigned to Silicon Storage Technology, Inc.. The applicant listed for this patent is Silicon Storage Technology, Inc.. Invention is credited to Hung Quoc Nguyen, Mark Reiten, Hieu Van Tran.
Application Number | 20150155039 14/094595 |
Document ID | / |
Family ID | 52001074 |
Filed Date | 2015-06-04 |
United States Patent
Application |
20150155039 |
Kind Code |
A1 |
Tran; Hieu Van ; et
al. |
June 4, 2015 |
Three-Dimensional Flash NOR Memory System With Configurable
Pins
Abstract
A three-dimensional NOR flash memory system is disclosed. The
system optionally comprises configurable standard pins, a
configurable output buffer, and a configurable input buffer.
Inventors: |
Tran; Hieu Van; (San Jose,
CA) ; Nguyen; Hung Quoc; (Fremont, CA) ;
Reiten; Mark; (Millbrae, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Silicon Storage Technology, Inc. |
San Jose |
CA |
US |
|
|
Assignee: |
Silicon Storage Technology,
Inc.
San Jose
CA
|
Family ID: |
52001074 |
Appl. No.: |
14/094595 |
Filed: |
December 2, 2013 |
Current U.S.
Class: |
365/185.18 |
Current CPC
Class: |
H01L 24/13 20130101;
H01L 2924/1435 20130101; H01L 2225/06517 20130101; H01L 2924/15311
20130101; H01L 2924/1434 20130101; H01L 2924/157 20130101; H01L
25/0652 20130101; H01L 25/18 20130101; H01L 2224/16145 20130101;
G11C 7/1045 20130101; G11C 2207/105 20130101; G11C 16/08 20130101;
H01L 2225/06541 20130101; H01L 25/0657 20130101; H01L 24/14
20130101; H01L 2224/14181 20130101; G11C 16/04 20130101; H01L
2225/06513 20130101; G11C 7/1057 20130101; H01L 2224/16225
20130101; H01L 24/16 20130101; H01L 2924/1431 20130101; H01L
2924/1438 20130101; H01L 2924/1432 20130101 |
International
Class: |
G11C 16/08 20060101
G11C016/08 |
Claims
1. A three-dimensional memory system, comprising: a plurality of
standard pins coupled to a logic circuit; the logic circuit
comprising a control block; a memory array; the plurality of pins
configurable by the control block to perform a function chosen from
a plurality of functions, wherein one of the plurality of functions
is accessing the array.
2. The system of claim 1, wherein one of the functions is providing
a standard serial memory interface to the array.
3. The system of claim 1, wherein one of the functions is providing
a non-standard serial memory interface to the array.
4. The system of claim 1, wherein one of the functions is providing
a standard parallel interface to the array.
5. The system of claim 1, wherein one of the functions is providing
a non-standard parallel interface to the array.
6. The system of claim 1, wherein one of the functions is providing
a miled serial and parallel interface to the array.
7. The system of claim 1, wherein one of the functions is providing
a testing function.
8. The system of claim 1, wherein one of the functions is providing
access to internal signals of the memory system.
9. The system of claim 1, wherein the control block is controlled
by a control pin.
10. The system of claim 1, wherein the control block is controlled
by a controller.
11. The system of claim 1, wherein at least one pin is coupled to
the logic circuit through a TSV.
12. The system of claim 1, wherein at least one pin is coupled to
the logic circuit through a microbump.
13. The system of claim 1, wherein at least one pin is coupled to
the logic circuit through a bondwire.
14. The system of claim 1, wherein the array is a SuperFlash
array.
15. The system of claim 1, wherein the standard pin is a serial SPI
or SQI pin.
16. The system of claim 1, wherein the standard pin is a parallel
MPF pin.
17. The system of claim 1, wherein the interface pin is
deconfigured without ESD or with a smaller ESD structure.
18. The system of claim 1, wherein the output pin is configured
optimizing for 3D smaller load performance.
19. The system of claim 1, wherein the input pin is configured
optimizing for 3D performance.
20. The system of claim 1 further comprising data bandwidth that is
more than the standard NOR memory I/O bandwidth.
21. The system of claim 1 further comprising a microcontroller.
22. A three-dimensional memory system, comprising: a plurality of
pins coupled to a logic circuit; the logic circuit comprising a
control block; a memory array; and the plurality of pins
configurable by the control block to perform a first function or a
second function, wherein the first function is providing addresses
to the memory array and the second function is accessing internal
signals of the memory system.
23. The system of claim 22, wherein the internal signals comprise
internal address signals.
24. The system of claim 22, wherein the internal signals comprise
internal input-output signals.
25. The system of claim 22, wherein the internal signals comprise
internal control signals.
26. The system of claim 22, wherein the control block is controlled
by a control pin.
27. The system of claim 22, wherein the control block is controlled
by a controller.
28. The system of claim 22, wherein at least one pin is coupled to
the logic circuit through a TSV.
29. The system of claim 22, wherein the array is a SuperFlash
array.
30. The system of claim 22, wherein the standard pin is a serial
SPI or SQI pin.
31. The system of claim 22, wherein the standard pin is a parallel
MPF pin.
32. The system of claim 22, wherein the interface pin is
deconfigured without ESD or with a smaller ESD structure.
33. The system of claim 22, wherein the output pin is configured
optimizing for 3D smaller load performance.
34. The system of claim 22, wherein the input pin is configured
optimizing for 3D performance.
35. The system of claim 22 further comprising I/O data bandwidth
that is more than the standard NOR memory I/O bandwidth.
36. The system of claim 22 further comprising a
microcontroller.
37. A memory system, comprising: a plurality of pins coupled to a
logic circuit; the logic circuit comprising a control block; and a
memory array; wherein the plurality of pins are configurable by the
control block to perform a first function or a second function,
wherein the first function is providing a serial interface to the
memory array and the second function is providing a parallel
interface to the memory array.
38. The system of claim 37, wherein the memory array is a two
dimensional memory array.
39. The system of claim 37, wherein the memory array is a three
dimensional memory array.
40. The system of claim 37, wherein the serial interface is a
standard interface.
41. The system of claim 37, wherein the serial interface is a
non-standard interface.
42. The system of claim 37, wherein the parallel interface is a
standard interface.
43. The system of claim 37, wherein the parallel interface is a
non-standard interface.
44. The system of claim 38, wherein the control block is controlled
by a control pin.
45. The system of claim 38, wherein the control block is controlled
by a controller.
46. The system of claim 37, wherein at least one pin is coupled to
the logic circuit through a TSV.
47. The system of claim 37, wherein the array is a SuperFlash
array.
48. The system of claim 37, wherein the standard pin is a serial
SPI or SQI pin.
49. The system of claim 37, wherein the standard pin is a parallel
MPF pin.
50. The system of claim 37, wherein the interface pin is configured
without standard ESD or with a smaller non-standard ESD
structure.
51. The system of claim 37, wherein the output pin is configured
optimizing for smaller non-standard load performance.
52. The system of claim 37, wherein the input pin is configured
optimizing for non-standard NOR memory interface performance.
53. The system of claim 37 further comprising I/O data bandwidth
that is more than the standard NOR memory I/O bandwidth.
54. The memory system of claim 37 further comprising a
microcontroller.
55. A three-dimensional memory system, comprising: a plurality of
standard memory pins coupled to a logic circuit; a memory array;
the plurality of pins configurable to perform a function chosen
from a plurality of functions, wherein one of the plurality of
functions is accessing the array.
56. The system of claim 55, wherein one of the functions is
providing a standard serial memory interface to the array.
57. The system of claim 55 wherein one of the functions is
providing a non-standard serial memory interface to the array.
58. The system of claim 55, wherein one of the functions is
providing a standard parallel memory interface to the array.
59. The system of claim 55, wherein one of the functions is
providing a non-standard parallel memory interface to the
array.
60. The system of claim 55, wherein one of the functions is
providing a mixed serial and parallel memory interface to the
array.
61. The system of claim 55, wherein one of the functions is
providing a testing function.
62. The system of claim 55, wherein one of the functions is
providing access to internal signals of the memory system.
63. The system of claim 55, wherein at least one pin is coupled to
the logic circuit through a TSV.
64. The system of claim 55, wherein at least one pin is coupled to
the logic circuit through a microbump.
65. The system of claim 55, wherein at least one pin is coupled to
the logic circuit through a bondwire.
66. The system of claim 55, wherein the array is a SuperFlash
array.
67. The system of claim 55, wherein the standard pin is a serial
SPI or SQI pin.
68. The system of claim 55, wherein the standard pin is a parallel
MPF pin.
69. The system of claim 55, wherein the interface pin is
deconfigured without ESD or with a smaller ESD structure.
70. The system of claim 55, wherein the output pin is configured
optimizing for 3D smaller load performance.
71. The system of claim 55, wherein the input pin is configured
optimizing for 3D performance.
72. The system of claim 55 further comprising I/O data bandwidth
that is more than the standard NOR memory I/O bandwidth.
73. The system of claim 55 further comprising a microcontroller.
Description
TECHNICAL FIELD
[0001] A three-dimensional (3D) NOR flash memory system with
configurable pins suitable for 3D memory system is disclosed.
BACKGROUND OF THE INVENTION
[0002] Flash memory cells using a floating gate to store charges
thereon and memory arrays of such non-volatile memory cells formed
in a semiconductor substrate are well known in the art. Typically,
such floating gate memory cells have been of the split gate type,
or stacked gate type.
[0003] One prior art non-volatile memory cell 10 is shown in FIG.
1. The split gate SuperFlash (SF) memory cell 10 comprises a
semiconductor substrate 4 of a first conductivity type, such as P
type. The substrate 1 has a surface on which there is formed a
first region 2 (also known as the source line SL) of a second
conductivity type, such as N type. A second region 3 (also known as
the drain line) also of a second conductivity type, such as N type,
is formed on the surface of the substrate 1. Between the first
region 2 and the second region 3 is a channel region 4. A bit line
(BL) 9 is connected to the second region 3. A word line (WL) 8
(also referred to as the select gate) is positioned above a first
portion of the channel region 4 and is insulated therefrom. The
word line 8 has little or no overlap with the second region 3. A
floating gate (FG) 5 is over another portion of the channel region
4. The floating gate 5 is insulated therefrom, and is adjacent to
the word line 8. The floating gate 5 is also adjacent to the first
region 2. A coupling gate (CG) 7 (also known as control gate) is
over the floating gate 5 and is insulated therefrom. An erase gate
(EG) 6 is over the first region 2 and is adjacent to the floating
gate 5 and the coupling gate 7 and is insulated therefrom. The
erase gate 6 is also insulated from the first region 2.
[0004] One exemplary operation for erase and program of prior art
non-volatile memory cell 10 is as follows. The cell 10 is erased,
through a Fowler-Nordheim tunneling mechanism, by applying a high
voltage on the erase gate EG 6 with other terminals equal to zero
volt. Electrons tunnel from the floating gate FG 5 into the erase
gate EG 6 causing the floating gate FG 5 to be positively charged,
turning on the cell 10 in a read condition. The resulting cell
erased state is known as `1` state. The cell 10 is programmed,
through a source side hot electron programming mechanism, by
applying a high voltage on the coupling gate CG 7, a high voltage
on the source line SL 2, a medium voltage on the erase gate EG 6,
and a programming current on the bit line BL 9. A portion of
electrons flowing across the gap between the word line WL 8 and the
floating gate FG 5 acquire enough energy to inject into the
floating gate FG 5 causing the floating gate FG 5 to be negatively
charged, turning off the cell 10 in read condition. The resulting
cell programmed state is known as `0` state.
[0005] The cell 10 can be inhibited in programming (if, for
instance, another cell in its row is to be programmed but cell 10
is to not be programmed) by applying an inhibit voltage on the bit
line BL 9. The cell 10 is more particularly described in U.S. Pat.
No. 7,868,375, whose disclosure is incorporated herein by reference
in its entirety.
[0006] Also known in other areas of art are three-dimensional
integrated circuit structures. One approach is to stack two or more
separately packaged integrated circuit chips and to combine their
leads in a manner that allows coordinated management of the chips.
Another approach is to stack two or more dies within a single
package.
[0007] However, to date, the prior art has not included
three-dimensional structures involving flash memory.
SUMMARY OF THE INVENTION
[0008] The aforementioned needs are addressed through multiple
embodiments involving three-dimensional arrangements of flash
memory arrays and associated circuitry. The embodiments provide
efficiencies in physical space utilization, manufacturing
complexity, power usage, thermal characteristics, and cost.
[0009] In one embodiment, configurable pins are provided for use
with the three-dimensional flash memory device.
[0010] In another embodiment, a configurable output buffer is
provided for use with the three-dimensional flash memory
device.
[0011] In another embodiment, a configurable output buffer is
provided for use with the three-dimensional flash memory
device.
[0012] In another embodiment, a configurable input buffer is
provided for use with the three-dimensional flash memory
device.
[0013] In another embodiment, flash memory device is a serial NOR
product type such as the SuperFlash Serial SPI SST25VF016B or
Serial Quad I/O SST26VF064B or other serial NOR product types. In
an embodiment flash memory device is a SuperFlash parallel NOR
product type such as the Parallel MPF SST38VF640xB or other
parallel NOR product types.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is a cross-sectional view of a prior art non-volatile
memory cell to which the present invention can be applied.
[0015] FIG. 2 depicts a prior art, two-dimensional flash memory
system layout.
[0016] FIG. 3 depicts a first die within a three-dimensional flash
memory system embodiment.
[0017] FIG. 4 depicts a second die within a three-dimensional flash
memory system embodiment.
[0018] FIG. 5 depicts a first die within another three-dimensional
flash memory system embodiment.
[0019] FIG. 6 depicts a second die within a three-dimensional flash
memory system embodiment.
[0020] FIG. 7. depicts an optional peripheral flash control die
that can be used in a three-dimensional flash memory system
embodiment.
[0021] FIG. 8 depicts an embodiment of supplemental circuitry for
use with dies containing flash memory arrays.
[0022] FIG. 9 depicts an embodiment of control circuitry.
[0023] FIG. 10 depicts a sensing system that can be used in a
three-dimensional flash memory system embodiment.
[0024] FIG. 11 depicts a TSV design that can be used in a
three-dimensional flash memory system embodiment.
[0025] FIG. 12 depicts a sensing circuit design that can be used in
a three-dimensional flash memory system embodiment.
[0026] FIG. 13 depicts a source follower TSV buffer circuit design
that can be used in a three-dimensional flash memory system
embodiment.
[0027] FIG. 14 depicts a high voltage circuit design that can be
used in a three-dimensional flash memory system embodiment.
[0028] FIG. 15 depicts a flash memory sector architecture that can
be used in a three-dimensional flash memory system embodiment.
[0029] FIG. 16 depicts an EEPROM emulator memory sector
architecture that can be used in a three-dimensional flash memory
system embodiment.
[0030] FIG. 17 depicts another embodiment of a three-dimensional
flash memory system.
[0031] FIG. 18 depicts another embodiment of a three-dimensional
flash memory system.
[0032] FIG. 19 depicts another embodiment of a three-dimensional
flash memory system.
[0033] FIG. 20 depicts an embodiment of a high voltage supply
within a three-dimensional flash memory system.
[0034] FIG. 21 depicts configurable pins used in a
three-dimensional flash memory system.
[0035] FIG. 22 depicts a configurable output buffer used in a
three-dimensional flash memory system.
[0036] FIG. 23 depicts a configurable output buffer used in a
three-dimensional flash memory system.
[0037] FIG. 24 depicts a configurable input buffer used in a
three-dimensional flash memory system
[0038] FIG. 25 depicts an output stage of a three-dimensional flash
memory system.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0039] FIG. 2 depicts a typical prior art architecture for a
two-dimensional prior art flash memory system. Die 12 comprises:
memory array 15 and memory array 20 for storing data, the memory
array optionally utilizing memory cell 10 as in FIG. 1; pad 35 and
pad 80 for enabling electrical communication between the other
components of die 12 and, typically, wire bonds (not shown) that in
turn connect to pins (not shown) or package bumps that are used to
access the integrated circuit from outside of the packaged chip;
high voltage circuit 75 used to provide positive and negative
voltage supplies for the system; control logic 70 for providing
various control functions, such as redundancy and built-in
self-testing; analog logic 65; sensing circuits 60 and 61 used to
read data from memory array 15 and memory array 20, respectively;
row decoder circuit 45 and row decoder circuit 46 used to access
the row in memory array 15 and memory array 20, respectively, to be
read from or written to; column decoder 55 and column decoder 56
used to access the column in memory array 15 and memory array 20,
respectively, to be read from or written to; charge pump circuit 50
and charge pump circuit 51, used to provide increased voltages for
read and write operations for memory array 15 and memory array 20,
respectively; high voltage driver circuit 30 shared by memory array
15 and memory array 20 for read and write operations; high voltage
driver circuit 25 used by memory array 15 during read and write
operations and high voltage driver circuit 26 used by memory array
20 during read and write operations; and bitline inhibit voltage
circuit 40 and bitline inhibit voltage circuit 41 used to un-select
bitlines that are not intended to be programmed during a write
operation for memory array 15 and memory array 20, respectively.
These functional blocks are understood by those of ordinary skill
in the art, and the block layout shown in FIG. 2 is known in the
prior art. Notably, this prior art design is two-dimensional.
[0040] FIG. 3 depicts a first die in a three-dimensional flash
memory system embodiment. Die 100 comprises many of the same
components previously shown in FIG. 2. Structures that are common
to two or more figures discussed herein have been given the same
last two digits in the component numbering. For example, array 115
in FIG. 3 corresponds to array 15 in FIG. 2. For efficiency's sake,
the description of FIG. 3 will focus on components that have not
yet been described.
[0041] Die 100 comprises TSV (through-silicon via) 185 and TSV 195
and testpad block TPAD 135. TSVs are known structures in the prior
art. A TSV is an electrical connection that passes through a
silicon wafer or die and connects circuits that reside in different
dies or layers within an integrated circuit package. TSV 185
comprises a plurality of conductors 186a1 . . . 186ai. TSV 195
comprises a plurality of conductors 196a1 . . . 196ak. Conductors
186a1 . . . 186ai and conductors 196a1 . . . 196ak are surrounded
by non-conductive material, such as plastic molding.
[0042] The TSV 185 and 195 are strategically placed away from the
flash arrays 115 and 120 by a predetermined distance (e.g., 30
.mu.m) to avoid interference or other problems such as mechanical
stress from TSV processing that could affect the flash arrays 115
and 120. This TSV placement strategy is applied for the other
embodiments discussed herein that utilize TSVs. Conductors 186a1 .
. . 186ai and conductors 196a1 . . . 196ak typically each has tens
of milliohms of resistance and 50-120 femto-farads of
capacitance.
[0043] The testpad block TPAD 135 includes probe pads (e.g., pad
openings for a tester to electrically access the wafer) and 3D
die-interface test circuits and are used by a tester to test die
100 to see if it is a good die. Such testing can include a TSV
connectivity test, which involves testing the TSV prior to 3D
stacking. This testing can be performed as part of a pre-bonding
test. The JTAG design for a test standard (Joint Test Action Group,
also known as IEEE 1149.1 Standard Test Access Port and
Boundary-Scan Architecture) test method can be employed through the
TPAD 135 for testing. The TSV 185 and 195 (and similarly, other
TSVs described in other embodiments) can also be used for testing
to identify good dies from bad dies during manufacturing. In this
instance, multiple TSV conductors can be tested at one time by one
tool of approximately 40-50 .mu.m in size by a tester.
[0044] With reference still to FIG. 3, optionally die 115 can be a
primary memory array and die 120 a redundant memory array.
[0045] FIG. 4 depicts a second die in the three-dimensional flash
memory system embodiment to be used in conjunction with die 100
shown in FIG. 3. Die 200 comprises many of the same components
previously shown in FIG. 2. Again, for efficiency's sake, the
description of FIG. 4 will focus on components that have not yet
been described.
[0046] Die 200 comprises TSV 185 and TSV shown previously in FIG.
3, as well as TPAD 235. TSV 185 and TSV 195 enable certain elements
in die 100 and die 200 to be electrically connected to one another,
via conductors 186a1 . . . 186ai and conductors 196a1 . . . 196ak.
The testpad TPAD 235 is used by a tester to test to determine if
die 200 is a good die before 3D stacking, as described previously
for testpad TPAD 135 with reference to FIG. 3.
[0047] Optionally, die 215 can be a primary memory array and die
220 a redundant memory array.
[0048] Because die 200 and die 100 are located in close proximity
to each other and can communicate via TSV 185 and TSV 195, die 200
is able to share certain circuit blocks with die 100. Specifically,
die 200 is configured to use charge pump circuits 150 and 151,
analog circuit 165, control logic 170, and high voltage circuit 175
within die 100, through TSV 185 and TSV 195. Die 200 therefore does
not need to contain its own versions of those blocks. This results
in efficiency in terms of physical space, manufacturing complexity,
and thermal performance. Optionally, die 100 can be considered the
"master" flash die and die 200 can be considered the "slave" flash
die.
[0049] FIG. 5 depicts a first die in another embodiment of a
three-dimensional flash memory system, and FIG. 6 depicts a second
die in that embodiment. Die 300 shown in FIG. 5 is similar to die
100 shown in FIG. 3, except that die 300 does not have a charge
pump circuit or high voltage circuit. Die 400 shown in FIG. 6 is
similar to die 200 shown in FIG. 4 except that die 400 does not
have a sensing circuit. Die 300 and die 400 are coupled via TSV 385
and TSV 386. TSV 385 comprises conductors 386a1 . . . 386ai, and
TSV 386 comprises conductors 396a1 . . . 396ai. Optionally, die 315
can be a primary memory array and die 320 a redundant memory array,
and/or die 415 can be a primary memory array and die 420 a
redundant memory array. Testpads TPAD 335 and 435 are used by a
tester to determine if die 300 and die 400 are good dies before 3D
stacking.
[0050] FIG. 7 depicts an optional peripheral flash control die for
use with any of the embodiments discussed herein. Die 500 contains
circuitry for assisting other dies in performing the functions of a
flash memory system. Die 500 includes TSV 585, TSV 595 and test pad
TPAD 535. TSV 585 comprises conductors 586a1 . . . 586ai, and TSV
386 comprises conductors 596a1 . . . 596ak. Die 500 comprises
analog logic 565, control logic 570 and high voltage circuit 545.
Die 500 can be used in conjunction with die 200, die 300, and/or
die 400 to provide circuit blocks for use with those dies that are
not physically present within those dies. This is enabled through
TSV 585 and TSV 586. One of ordinary skill in the art will
understand that, although numbered differently, TSV 585 and TSV 586
can be the same TSVs described previously with reference to other
dies. The testpad TPAD 535 is used by a tester to test die 500 to
see if it is a good die before 3D stacking.
[0051] FIG. 8 depicts a charge pump die for use with any of the
embodiments discussed herein. Die 601 contains charge pump
circuitry 602 to generate the voltages needed for other dies in
performing flash memory erase/program/read operations. Die 601
includes TSV 695. TSV 695 comprises conductors 696a1 . . . 696ak.
Die 601 can be used in conjunction with other dies through TSV 695.
One of ordinary skill in the art will understand that, although
numbered differently, TSV 695 can be the same TSVs described
previously with reference to other dies. Testpad TPAD 635 is used
by a tester to determine if die 601 is a good die before 3D
stacking.
[0052] Analog circuits 165, 365, and 565 shown in FIGS. 3, 5, and 7
can provide a multitude of functionality within the memory system,
including the following: transistor trimming during the
manufacturing process, temperature sensing for the trimming
process, timers, oscillators, and voltage supplies.
[0053] Sensing circuits 160, 260, and 360 shown in FIGS. 3, 4, and
5 can comprise numerous components used in the sensing operation,
including a sense amplifier, transistor trimming circuits
(utilizing the trimming information generated by the transistor
trimming process performed by analog circuits 165, 365, and/or 565)
temperature sensors, reference circuits, and a reference memory
array. Optionally, a die can include fewer than all of these
categories of circuits. For example, a die might include only a
sense amplifier.
[0054] FIG. 9 depicts an optional embodiment for control logic 170,
370, and 570, shown as logic block 600. Logic block 600 optionally
comprises powerup recall controller 610, First Die Redundancy
Circuit 620, Second Die Redundancy Circuit 630, Redundancy
Controller 640, Redundancy Comparator 650, EEPROM Emulator 660,
Sector Size M Emulator 670 and Sector Size N Emulator 680.
[0055] Powerup recall controller 610 manages the startup of the
flash memory system, including performing the built-in self-test
functionality. It also fetches the configuration data for
transistor trimming that was generated during the manufacturing
process.
[0056] First Die Control Circuit 620 stores a list of memory cells
in the arrays located in a first die that are determined during
power up or operation to be faulty or subject to error. First Die
Control Circuit 620 stores this information in non-volatile memory.
First Die Control Circuit 620 also stored transistor trimming data
generated during the manufacturing and testing phase. Upon power
up, powerup recall controller 610 will retrieve the list of bad
memory cells from First Die Control Circuit 620, and Redundancy
Controller 640 thereafter will map the bad storage cells to
addresses for redundant (and good) cells, so that all accesses to
the bad cells will instead be directed to good cells.
[0057] First Die Control Circuit 620 also stores trimming data for
a first die that was generated during the manufacturing or testing
process. Transistor trimming techniques to compensate for
manufacturing variability in integrated circuits are known in the
art.
[0058] First Die Control Circuit 620 also performs built-in
self-tests. One type of test is disclosed in U.S. application Ser.
No. 10/213,243, U.S. Pat. No. 6,788,595, "Embedded Recall Apparatus
and Method in Nonvolatile Memory" (the "'595 patent") assigned to a
common assignee, which is hereby incorporated by reference. The
'595 patent discloses the storage of a pattern of predetermined
bits in a memory array and in a register. During the startup
process, the bits from the memory array are compared to the bits in
the register. This process is repeated until a set number of
"passes" or "failures" occurs. The purpose of this test is to
validate different portions of the memory array. If any failures
are identified, then the relevant cells can be added to the list of
"bad" cells.
[0059] Second Die Control Circuit 630 performs the same function as
First Die Redundancy Circuit 620 but for a second die. One of
ordinary skill in the art will understand that a Control Circuit
such as First Die Control Circuit 620 and Second Die Control
Circuit 630 can be used for each additional die in the memory
system.
[0060] Redundancy controller 640, already discussed above, maps bad
storage cells to addresses for good storage cells, so that the bad
storage cells are no longer used during normal operation.
Redundancy comparator 640 compares in real time incoming address
versus bad addresses stored to determine if addressed storage cells
needs to be replaced. Optionally, redundancy controller 640 and
redundancy comparator 650 can be shared by more than one die.
[0061] EE Emulator Controller 660 enables the memory system to
emulate an EEPROM. For example, EEPROMs typically utilize memory of
a certain sector size of a small number of bytes, such as 8 bytes
(or 16, 32, 64 bytes) per sector. A physical flash memory array
will contain thousands of rows and columns. EE Emulator controller
660 can divide an array into groups of 8 or 64 bytes (or whatever
the desired sector size is) and can assign sector numbers to each
set of 8 or 64 bytes. Thereafter, EE emulator controller 660 can
receive commands intended for an EEPROM and can perform read or
write operations to the flash array by translating the EEPROM
sector identifiers into row and column numbers that can be used
with an array within a die. In this manner, the system emulates the
operation of an EEPROM.
[0062] Sector Size N Controller 670 enables the memory system to
operate on sectors of size N bytes. Sector Size N Controller 660
can divide an array into sets of N bytes and can assign sector
numbers to each set of N bytes. Thereafter, Sector Size N
Controller 670 can receive commands intended for one or more
sectors of size N bytes, and the system can perform read or write
operations accordingly by translating the sector identifiers into
row and column numbers that can be used with an array within a
die.
[0063] Sector Size M Controller 680 enables the memory system to
operate on sectors of size M bytes. Sector Size M Controller 680
can divide an array into sets of M bytes and can assign sector
numbers to each set of M bytes. Thereafter, Sector Size M
Controller 680 can receive commands intended for one or more
sectors of size M bytes, and the system can perform read or write
operations accordingly by translating the sector identifiers into
row and column numbers that can be used with an array within a
die.
[0064] One of ordinary skill in the art will appreciate that
numerous sector size controllers can be utilized to emulate sectors
of various sizes.
[0065] One advantage of the disclosed embodiments is the ability to
handle read and write requests to sectors of different sizes. For
example, one array can be dedicated to handling read and write
requests to sectors with a size of 2K bytes per sector, and another
array can be dedicated to handling read and write requests to
sectors with a size of 4K bytes per sector. This will allow a
single flash memory system to emulate multiple types of legacy
memory systems, such as RAM, ROM, EEROM, EEPROM, EPROM, hard disk
drives, and other devices.
[0066] Another advantage of the disclosed embodiments is that
different dies can be fabricated using different processes. For
example, die 100 can be fabricated using a first semiconductor
process, such as 40 nm, and die 200 can be fabricated using a
second semiconductor process, such as 65 nm. Because die 500 does
not contain any memory arrays, it optionally can be fabricated
using a semiconductor process optimized for analog logic, such as
130 nm.
[0067] FIG. 10 depicts a sensing system 1100 that can be used in
the three-dimensional flash memory system embodiments described
herein. The sensing system 1100 comprises SF (SuperFlash split gate
technology, such as the memory cell as described in FIG. 1)
Embedded Reference Array 1110, Reference Readout Circuit 1120, Read
Margin Trim Circuit 1130, Temperature Sensor 1140, Sense Amplifier
1150, and Sense Amplifier 1160. In one embodiment, Sense Amplifier
1160 is implemented on die 200 and 300, and the rest of circuit
blocks shown in FIG. 10 are implemented on die 100.
[0068] The SF Embedded Reference Array 1110 provides the reference
cell needed to generate reference levels to be compared against the
data level (generated from a data memory cell). The reference level
is generated by the Reference Readout Circuit 1120. The comparison
is done by the Sense Amplifier 1150, and its output signal is DOUT
1152. The Read Margin Trim Circuit 1130 is used to adjust the
reference level to different levels needed to ensure data memory
cell integrity against PVT (process, voltage, and temperature)
variations and stress conditions. The Temperature Sensor 1140 is
needed to compensate for temperature gradient for different dies in
the vertical die stacking in the three-dimensional flash memory
system. Because the circuit blocks 1110, 1120, 1130, 1140 are
manufactured on one master die (e.g., die 100), less overhead and
power is needed for the three-dimensional flash memory operation.
This sensing architecture saves power and area without sacrificing
performance.
[0069] FIG. 11 depicts a TSV shield design 1200 for critical
signals to minimize noise impact. The 1200 TSV shield design
includes TSV 1296a for critical signals such for routing read
signal paths such as for signal 1122 IREF and signal 1152 DOUTx in
FIG. 10 or for signals such as for output of the sensing 160 in
FIG. 4 or the signal of block 455 in FIG. 6. Other critical signals
include address lines, clocks, and control signals. The TSV 1296b
serves as shielding signal lines for the TSV 1296a to minimize
cross talk from other signals to the TSV 1296a as well as prevent
noise projected from the TSV 1296a to other TSV.
[0070] FIG. 12 depicts a sensing circuit 1250 that can be used in
the three-dimensional flash memory system embodiment. The sensing
circuit 1250 includes load (pullup) PMOS transistor 1252, a
cascoding native NMOS transistor 1254 (with a threshold voltage
.about.0V), a bitline bias NMOS transistor 1256, and a bitline bias
current source 1260. Alternatively the load PMOS transistor 1252
can be replaced with a current source, a native NMOS transistor, or
a resistor. Alternatively instead of the current source 1260 and
the NMOS transistor 1256, a bias voltage on the gate of the NMOS
transistor 1254 can be used to determine the bias voltage on the
bit line BLIO 1258. Bit line BLIO 1258 (source of NMOS 1254)
couples to a memory cells through a y-decoder and a memory array
(similar to ymux 255 and array 215 in FIG. 4, for example). A
sensed node SOUT 1262 couples to a differential amplifier 1266. A
reference SREF 1264 couples to another terminal of the differential
amplifier 1266. A senseamp output SAOUT 1268 is output of
differential amplifier 1266. As partitioned, the sensing circuit
1250 is used to drive a TSV parasitic capacitor 1259 (which comes
from a TSV used to connect a die to next die in the 3D stack)
through the cascoding transistor 1254. Such arrangement minimizes
the sensing speed penalty since the sensed node SOUT 1262 does not
see the TSV parasitic capacitor 1259 directly.
[0071] FIG. 13 depicts a source follower TSV buffer circuit 1350
that can be used in the three-dimensional flash memory system
embodiments. The source follower TSV buffer 1350 is used to drive a
TSV connection. The TSV buffer includes a native (threshold voltage
.about.0V) NMOS transistor 1352 and a current source 1354. The
circuit 1350 is used in one embodiment at the output of the sensing
circuit 260 (FIG. 3), the sensing circuit 360 (FIG. 4), the ymux
circuit 455 (FIG. 6) to drive a TSV across the die stack. The
circuit 1350 can also be used for other analog signals such as
bandgap reference voltage.
[0072] FIG. 14 depicts an analog high voltage (HV) system 1300 that
can be used in the three-dimensional flash memory system
embodiment. The analog HV system 1300 includes a bandgap reference
block 1310, a timer block 1320, a high voltage generation HVGEN
1330, a HV trimming HV TRIM 1340, and a temperate sensing block
TEMPSEN 1350. The TEMPSEN 1350 is used to compensate the
temperature gradient of the 3D die stack by adjusting the high
voltage depending on each die temperature. The HV TRIM 1340 is used
to trim the high voltage levels to compensate the process variation
of each die in the stack.
[0073] The analog HV system 1300 also includes analog HV level
wordline driver 1360a-d for VWLRD/VWLP/VWLE/VWLSTS (wordline
read/program,/erase/stress) respectively. The analog HV system 1300
also includes analog HV level control gate driver 1365a-d for
VCGRD/VCGP/VCGE/VCGSTS (control gate read/program,/erase/stress)
respectively. The analog HV system 1300 also includes analog HV
level erase gate driver 1370a-d for VEGRD/VEGP/VEGE/VEGSTS (erase
gate read/program,/erase/stress) respectively. The analog HV system
1300 also includes analog HV level source line driver 1375a-d for
VSLRD/VSLP/VSLE/VSLSTS (source line read/program,/erase/stress)
respectively. The analog HV system 1300 also includes analog HV
level driver 1390 for muxing the input level VINRD/VINP/VINE/VINSTS
(input line read/program,/erase/stress) respectively. The analog HV
system 1300 also includes analog HV level driver 1380 for muxing
the input level VSLRD/VSLP/VSLE/VSLSTS (input line
read/program,/erase/stress) respectively to input of a source line
supply circuit 1385 VSLSUP.
[0074] In one embodiment, circuit blocks 1310-1350 are implemented
on a master SF die 100 (FIG. 3) or on a peripheral flash control
die 500 (FIG. 7). In another embodiment, circuit blocks
1360a-d/1365a-d/1370a-d/1375a-d are implemented on a master flash
die such as die 100 (FIG. 3) or on a peripheral flash control die
500 (FIG. 7). In another embodiment, circuit blocks 1380/1385/1390
are implemented on a slave flash die such as die 300 (FIG. 5).
[0075] FIG. 15 depicts an flash memory sector architecture 1400
that can be used in the three-dimensional flash memory system
embodiment. The sector architecture 1400 includes multiple memory
cells 1410 that is arranged into bitlines (columns) and rows. The
memory cell 1410 is as the memory cell 10 in FIG. 1. The sector
architecture includes a flash sector 1420 that includes 8 wordlines
WL0-7 1430-1437, 2K bitlines 0-2047 1470-1 to 1470-N, one CG line
1440a (connecting all CG terminal of all memory cells 1410 in
sector 1420), one SL line 1460a (connecting all SL terminal of all
memory cells 1410 in sector 1420), one EG line 1450a (connecting
all EG terminal of all memory cells 1410 in sector 1420). As such
there are 2K bytes of memory cells 1410 in the sector 1420.
Different number of bytes per sector can be implemented by using
more or less number of wordline and more or less number of bitlines
such as 8 wordlines and 4K bitlines (4K bytes per sector). Multiple
of sector 1420 can be arranged horizontally with all wordlines
shared horizontally across. Multiples of sectors 1420 can be tiled
vertically to increase the array density with all bitlines shared
vertically.
[0076] FIG. 16 depicts an EE emulator sector architecture 1500 that
can be used in the three-dimensional flash memory system
embodiment. The sector architecture 1400 includes multiple memory
cells 1510 that is arranged into bitlines (columns) and rows. The
memory cell 1510 is as the memory cell 10 in FIG. 1. The EE
emulator sector architecture includes a flash EE emulator sector
1515 that includes 2 wordlines WL0-1 1530-1531, 256 bitlines 0-255
1570-1 to 1570-N, one CG line 1540a (connecting all CG terminal of
all memory cells 1410 in sector 1515), one SL line 1560a
(connecting all SL terminal of all memory cells 1410 in sector
1515), one EG line 1550a (connecting all EG terminal of all memory
cells 1510 in sector 1420). As such there are 64 bytes of memory
cells 1510 in the EE emulator sector 1515. Smaller number of bytes
per EE emulator sector can be implemented by using less number of
wordline and less number of bitlines, such as 1 wordline and 64
bitlines (8 bytes per EE emulator sector). The flash EE emulator
sector 1515 is tiled vertically to make up a plane array 1520 with
all bitlines shared vertically. The plane array 1520 is tiled
horizontally to make multiples of it will all wordlines are shared
horizontally.
[0077] Another embodiment is shown in FIG. 17. Integrated circuit
700 comprises a plurality of dies. In this example, integrated
circuit 700 comprises die 710, die 720, die 730, die 740, and die
750. Die 710 is mounted on substrate 760 using flipchip connections
780. The substrate 760 connects to package bumps 790, which can be
used by devices outside of integrated circuit 700 to access
integrated circuit 700. TSV 785 connects different dies together. A
first subset of TSV 785 connects die 710, die 720, die 740, and die
750 together, and a second subset of TSV 785 connects due 710, die
720, and die 730 together. Within TSV 785 are microbumps 770 used
to connect to dies. Die 730 and die 740 are located within the same
"level" or dimension within integrated circuit 700.
[0078] In one example based on this embodiment, the die 710 is a
MCU (microcontroller) die, CPU (Central Processing Unit) die, or a
GPU (Graphics Processing Unit) die, die 720 is a master flash die,
die 740 is a slave flash die, die 750 is a RAM die, and die 730 is
peripheral flash control die or a charge pump die.
[0079] Another advantage of the disclosed embodiments is that
different dies can be fabricated using different processes. For
example, die 710 can be fabricated using a first semiconductor
process, such as 14 nm, and die 720/740 can be fabricated using a
second semiconductor process, such as 40 nm. Because die 730 does
not contain any memory arrays, it optionally can be fabricated
using a semiconductor process optimized for analog logic, such as
65 nm.
[0080] Another embodiment is shown in FIG. 18. Integrated circuit
800 comprises a plurality of dies. In this example, integrated
circuit 800 comprises die 810, die 820, die 830, die 840, and die
850. Die 850 is mounted on substrate 860 using flipchip connections
880. The substrate 860 connects to package bumps 890, which can be
used by devices outside of integrated circuit 800 to access
integrated circuit 800. A subset of TSV 885 connects die 810, die
830, die 840, and die 850 together, and a second subset of TSV 885
connects die 810 and die 820 together. Within TSV 885 are
microbumps 870 used to connect to dies.
[0081] In one example based on this embodiment, die 810 is a master
flash die, die 830/840/850 are slave flash dies, and die 820 is
peripheral flash control die or a charge pump die.
[0082] Another embodiment is shown in FIG. 19. Integrated circuit
900 comprises a plurality of dies. In this example, integrated
circuit 900 comprises die 910, die 920, die 930, die 940, die 950,
and die 960. Die 910 and 950 are mounted on substrate 970 using
flipchip connections 990. The die 910 and 950 are connected
together through a silicon interposer 980. The substrate 970
connects to package bumps 995, which can be used by devices outside
of integrated circuit 900 to access integrated circuit 900. A first
subset of TSV 985 connects die 910, die 920, die 930, and die 940
together, and a second subset of TSV 985 connects die 950 and die
960 together. Within TSV 985 are microbumps 970 to connect to
dies.
[0083] In one exampled based on this embodiment, he die 910 is a
master flash die, die 920/930/940 are slave flash dies, and die
950/960 are peripheral flash control dies.
[0084] An embodiment of a force-sense high voltage supply is shown
in FIG. 20. Integrated circuit 1000 comprises a plurality of dies.
In this example, integrated circuit 1000 comprises die 1010, die
1020, through die 1030 (with any number of dies contained between
die 1020 and die 1030) (with other optional dies not shown between
die 1020 and die 1030). Die 1010 contains high voltage supply 1011
which delivers (forces) the high voltage output to the die 1010,
1020, or 1030. TSV 1085 connects die 1010, die 1020, and die 1030.
High voltage supply 1011 connects to die 1020 and die 1030 through
TSV 1085. Device 1021, which optionally can comprise a switch, is
used to control the provision of power from high voltage supply
1011 to die 1020 by enabling the high voltage output at the die
1020 to be fed back to the input of the high voltage supply 1011 on
the die 1010 (meaning the high voltage 1011 senses the voltage on
the high voltage out on the die 1020 through the switch 1021 so as
to deliver the correct voltage at the die 1020).
[0085] Similarly, high voltage supply 1011 connects to die 1030
through TSV 1085. Device 1031, which optionally can comprise a
switch, is used to control the provision of power from high voltage
supply 1011 to die 1030 by enabling the high voltage output at the
die 1030 to be fed back to the input of the high voltage supply
1011 on the die 1010 (meaning the high voltage 1011 senses the
voltage on the high voltage out on the die 1030 through the switch
1031 so as to deliver the correct voltage at the die 1030).
[0086] The high voltage supply 1011 can be used, for example, as
power for supply terminal SL 2 of memory cell 10 shown in FIG. 1
and used in arrays 115/120/215/220/315/330/415/420. Alternatively,
it can supply power for all terminals WL 8, CG 7, EG 6, BL 9, SL 2,
and substrate 1 of the memory cell 10 in FIG. 1 and used in memory
arrays 115/120/215/220/315/330/415/420.
[0087] One embodiment containing integrated circuits 700, 800,
and/or 900 is method of concurrent operation. For example, the
control circuit on master die 720/810/910 can enable the concurrent
operation of different flash dies, such as die 720
reading/programming/erasing while other flash die 740 is
programming/reading/programming, respectively, or vice-versa.
[0088] Another embodiment containing integrated circuits 700, 800,
and/or 900 is a method of IO width configuration, where the system
determines how many IO bits can be supplied by a die in a read or
program operation. For example, the control circuit on master die
720/810/910 can change the width of IO in a read or program
operation of different flash dies, such as by expanding the IO
width by combining IO widths of individual dies.
[0089] Another embodiment containing integrated circuits 700, 800,
and/or 900 is method of adaptive temperature sensor configuration.
For example, a temperature profile can be stored for each flash die
to compensate for the temperature gradient for the die stack for
specific operation since different systems result in different
power consumptions, hence causing different temperature
gradient.
[0090] Another embodiment containing integrated circuits 700, 800,
and/or 900 is a method of TSV self test. For example, at initial
configuration, a built in TSV self test connectivity engine is used
to identify a defective TSV and to determine whether it needs
repair by using a Redundant TSV or should be discarded. The self
test can involve forcing a voltage on a TSV connection and deciding
if the TSV is bad, such as by determining if the resulting current
is smaller than a predetermined number. The self test also can
involve forcing a current through a TSV connection and concluding
that the TSV is bad if the resulting voltage is greater than a
predetermined number.
[0091] A method of manufacturing a 3D flash memory device, such as
one based on the embodiments described herein, will now be
described. The 3D flash process formation starts with individual
die process. Thereafter, dies are stacked either using die-to-wafer
or wafer-to-wafer stacking schemes.
[0092] For die-to-wafer stacking, each die can be tested using KGD
(Known Good Die) method to eliminate bad dies. The TSV processing
can be done by VIA first (before CMOS), VIA Middle (after CMOS and
before BEOL back-end-of-line), or VIA Last (after BEOL) testing.
TSV formation is processed by a via etching step, which creates an
(TSV) opening on the wafer. A thin liner (e.g. silicon dioxide 1000
A) is then formed on the side of the opening. Then a metallization
step (e.g., Tungsten or Cu) is formed to fill the hole. A
dielectric glue layer (e.g. 1 u thick) is deposited on top of the
die after BEOL. TSV back end processing includes thinning, backside
metal formation, micro bump, passivation, dicing.
[0093] Die-to-wafer stacking uses a temporary adhesive bonding.
Each top wafer is typically thinned down to 40-75 um depending on
aspect ratio and TSV diameter, for example for TSV diameter of Sum
and aspect ratio of 10, a 50 um thick wafer is required. The top
diced dies are stacked face up on a regular thickness bottom die
through micro-bump and the whole die stack then attaches to a
package substrate through flipchip bump (C4-bump).
[0094] For wafer-to-wafer bonding, the dies must have a common
size, and hence, offers less flexibility in 3D die integration. The
TSV process and wafer stacking process are similar as described
above. The 3D stack yield in this case would be limited by the
lowest yield wafer. Wafer-to-wafer stacking typically can use
global wafer alignment for bonding, and hence, has higher alignment
tolerance and also higher throughput (since all die stacking occurs
in parallel).
[0095] FIG. 21 depicts configurable pins of memory device 1660 that
can be implemented in the 3D memory system as described above. The
memory device 1660 is a version of the SuperFlash Serial SPI,
SuperFlash Serial SQI, SuperFlash Parallel MTP, or SuperFlash
Parallel MPF device. These devices are accessed by a standard NOR
memory pin interface such as JEDEC standard pin assignment and
memory interface. The standard parallel NOR interface pins include
CE# (Chip Enable), OE# (Output Enable), WE# (Write Enable), WP#
(Write Protect), RST# (Reset), RY/BY# (Ready Busy), DQ15-DQ0 (Data
Input Output, IO pads), AN-A0 (Address Pins), VDD (Power Supply),
VSS (Ground). The standard serial SPI interface pins include SCK
(Serial Clock), SI (Serial Data Input), SO (Serial Data Output),
CE# (Chip Enable), WR# (Write Protect), HOLD# (Hold), VDD (Power
Supply), VDD (Ground). The standard serial SQI interface pins
include SCK (Serial Clock), SI (Serial Data Input), SIO[3:0]
(Serial Data Quad Input Output), CE# (Chip Enable), WR# (Write
Protect), HOLD# (Hold), VDD (Power Supply), VDD (Ground).
[0096] A set of pins 1625 and control pin 1626 are accessible
outside of the package of memory device 1660. The set of pins 1625
is coupled to logic circuit 1628 through interface 1627. Interface
1627 optionally comprises pads and wire bonds as known in the prior
art or can comprise TSVs as described previously. Logic circuit
1628 comprises control block 1620. Control block 1620 is coupled to
control pin 1626 and controller 1640. Control pin 1626 and
controller 1640 each can configure logic circuit 1628 to determine
the function of the set of pins 1625. Memory device 1660 further
comprises memory array 1650. Memory array 1650 can be either a two
dimensional memory array or a three dimensional memory array.
[0097] In one embodiment, memory array 1650 is a two dimensional
memory array. If control pin 1626 or the output of controller 1640
is set to "0," the set of pins 1625 can be configured by logic
circuit 1628 to operate as a serial interface to the memory device.
If control pin 1626 or the output of controller 1640 is set to "1,"
the set of pins 1625 can be configured by logic circuit 1628 to
operate as a parallel interface to the memory device.
[0098] In another embodiment, memory array 1650 is a two
dimensional memory array. If control pin 1626 or the output of
controller 1640 is set to "0," the set of pins 1625 could be
configured by logic circuit 1628 to perform the function of normal
I/O pins that can access memory array 1650. However, if control pin
1626 or the output of controller 1640 is set to "1," the set of
pins 1625 can be configured by logic circuit 1628 to perform the
function of providing access to internal signals 1645 of the memory
device, such as internal address signals, internal I/O data,
internal control signals, internal current bias signals, testmode
control signals, SuperFlash control signals, etc. Such signals were
not accessible to pins in the prior art.
[0099] In another embodiment, memory array 1650 is a two
dimensional memory array. If control pin 1626 or the output of
controller 1640 is set to "0," the set of pins 1625 could be
configured by logic circuit 1628 to perform the function of normal
I/O pins that can access memory array 1650. However, if control pin
1626 or the output of controller 1640 is set to "1," the set of
pins 1625 can be used for testing purposes.
[0100] In another embodiment, the set of pins 1625 is configured to
be accessed as non-standard NOR memory pins.
[0101] In another embodiment, the set of pins 1625 is configured to
be a mix of serial and parallel NOR memory interface. One
embodiment of a mixed serial and parallel NOR memory interface is
one with serial input command and parallel output read.
[0102] In another embodiment, memory array 1650 is a
three-dimensional memory array. If control pin 1636 or the output
of controller 1640 is set to "0," the set of pins 1625 could be
configured by logic circuit 1628 to perform the function of I/O
pins for memory array 1650. However, if control pin 1636 or the
output of controller 1640 is set to "1," the set of pins 1625 can
be configured by logic circuit 1628 to perform the function of
providing access to internal signals 1645 of the memory device,
such as internal address signals, internal I/O data, internal
control signals, internal current bias signals, testmode control
signals, SuperFlash control signals, etc.
[0103] In another embodiment, memory array 1650 is a three
dimensional memory array. If control pin 1626 or the output of
controller 1640 is set to "0," the set of pins 1625 can be
configured by logic circuit 1628 to operate as a serial interface
to memory array 1650. If control pin 1626 or the output of
controller 1640 is set to "1," the set of pins 1625 can be
configured by logic circuit 1628 to operate as a parallel interface
to memory array 1650.
[0104] FIG. 22 depicts a configurable output buffer 1700. The
configurable output buffer 1700 is part of an output circuit of the
DQ parallel pin or SO or SIO serial pin. The output buffer is
typically specified to drive an output load of 30 pF or 100 pF for
a standard NOR memory device. Configurable output buffer 1700
comprises predriver 1710 coupled to slew rate controller 1720 and
predriver 1711 coupled to slew rate controller 1721. Slew rate
controller 1720 is coupled to the gate of PMOS transistor 1730, and
slew rate controller is coupled to the gate of NMOS transistor
1731. Transistor 1730 and transistor 1731 together form an output
driver 1760 that provides output 1740. Slew rate controller 1720
and slew rate controller 1731 together control the slew rate of
output driver 1760. Output driver 1760 is coupled to voltage source
1750. The voltage source 1750 can be connected to a different
voltage source for the 3D memory system which is non-standard
(i.e., different than voltage source for the standard NOR memory
device). Transistor 1730 and transistor 1731 optionally are
trimmable through known techniques. Slew rate controller 1720 and
slew rate controller 1721 themselves are configurable by controller
1140 (not shown). Thus, transistor 1730 and transistor 1731 can be
configured to optimize performance for a two dimensional or three
dimensional memory device. Further the transistors 1730 and 1731
together with the slew rate controller 1720 and 1721 can be
configured to optimize performance for a two dimensional or three
dimensional memory device such as driving a lesser output load,
e.g., 0.2-2 pF, as compared to an output load of a standard NOR
memory device, e.g. 30-100 pF. Furthermore, with a very small
output load, slew rate controller 1720 and 1721 can be disabled,
i.e., no slew rate control is needed.
[0105] FIG. 23 depicts a deconfigurable output buffer 1800. The
deconfigurable output buffer 1800 is part of an output circuit of
the DQ parallel pin or SO or SIO serial pin. Deconfigureable output
buffer 1800 comprises predriver 1810 coupled to slew rate
controller 1820 and predriver 1811 coupled to slew rate controller
1821. Slew rate controller 1820 is coupled to the gate of PMOS
transistor 1830, and slew rate controller is 1821 is coupled to the
gate of NMOS transistor 1831. Transistor 1830 and transistor 1831
together form an output driver 1860. The output of output driver
1860 is provided to multiplexer 1850, which is controlled by
control signal 1851. Another input to multiplexer 1850 is the
output of predriver 1810. Slew rate controller 1820 and slew rate
controller 1821 together control the slew rate of output driver
1860. Transistor 1830 and transistor 1831 optionally are trimmable
through known techniques. Slew rate controller 1820 and slew rate
controller 1821 themselves are configurable by controller 1140 (not
shown). Thus, transistor 1830 and transistor 1831 can be configured
to optimize performance for a two dimensional or three dimensional
memory device such as for driving a much smaller output load (e.g.,
0.2-2 pF) instead of 30-100 pF for a standard NOR memory device. In
addition, slew rate controller 1820 is enabled by enable signal
1822, and slew rate controller 1822 is enabled by enable signal
1823. Optionally, enable signal 1822 can turn off slew rate
controller 1820, and enable signal 1823 can turn off slew rate
controller 1821. In such a situation, control signal 1851 can
control multiplexer 1850 to output the signal received from
predriver 1810. This effectively will cause the input to predriver
1810 to bypass output driver 1860. This is particularly desirable
if standard memory product ESD protection is not required (such as
JEDEC ESD standard, e.g. 2 KV HBM or 200V MM), as output driver
1860 also serves as ESD protection. ESD protection device incurs a
capacitance output load. In another embodiment a smaller
non-standard ESD structure is configured for a 3D system. Bypassing
output driver 1860 will increase the speed of the system.
[0106] FIG. 24 depicts configurable input buffer 1900. In one
embodiment, the input buffer 1800 is part of an input circuit of
the control pin (such as CE#, WE#, etc), the address pins (AN-A0),
the DQ parallel pin or SI or SIO serial pin. Input buffer 1900
comprises predriver 1904 coupled to predriver 1905, which are
powered by voltage source 1906, coupled to switch 1908 controlled
by control signal 1912. Input buffer 1900 further comprises switch
1907 controlled by control signal 1913. The input to predriver 1904
is input 1901, and the input to switch 1907 is input 1902. In this
embodiment, input 1901 is an input to a standard pin and input 1902
is an input to a TSV of the type described previously. Switch 1908
and 1907 are coupled to the gate of transistor 1909 and the gate of
transistor 1910. Transistor 1909 and transistor 1910 together form
input driver 1920. The output of input driver 1920 is input signal
1911. If input 1901 is active, switch 1908 is enabled and switch
1907 is disabled. Input 1901 will flow through input driver 1920.
If input 1902 is active, switch 1908 is disabled and switch 1907 is
enabled. Input 1902 bypasses predriver 1904 and predriver 1905,
which results in a faster system. Input 1902 requires less
conditioning than input 1901 because the three dimensional system
described herein operates at the same operating voltage as the core
of the memory system. The input and output signals from the memory
array therefore do not require driving a load as in the prior art
two dimensional systems.
[0107] FIG. 25 depicts an output configuration of a memory system
2000 that comprises standard pins and 3D memory system pins (such
as TSVs, microbump, bondwire, etc) of the type described
previously. Memory system 2000 comprises sense amplifiers 2010,
buffers 2020, data multiplexers 2030, pads 2040, and pads 2050. In
this example, pads 2040 and pads 2050 can be connected to any type
of output pin known in the art, such as bumps and balls.
[0108] If data is being read from a two dimensional array, the data
is sensed by sense amplifier 2010, provided to buffers 2020 and
multiplexers 2030 and finally to pads 2040. However, if data is
being read from a three dimensional array, the data is sensed by
sense amplifier 2010, provided to buffers 2020, and then provided
straight to pads 2050. This results in a faster system and takes
advantage of the fact that data read from a three dimensional array
does not require driving as in the prior art two dimensional
arrays. Further the number of the input-output drivers (meaning I/O
data bandwidth) such as of a standard NOR memory device is a
typical 16 for standard parallel NOR memory device and one or 4 for
a standard serial NOR memory device, hence available I/O data
bandwidth for a standard NOR memory device is depending on this
fixed number of input-output I/O drivers. For the 3D memory system,
the memory system 2000 can be configured to provide more than the
fixed number of standard NOR memory device. As the embodiment shown
in the memory system 2000, 64 input-output I/O drivers are
provided. This enhances the I/O data bandwidth of the 3D memory
system. Another embodiment can provide more than 64 input-output
I/O data bandwidth such as 128 to 2K at the expense of the
complexity of the memory system 2000.
[0109] 2D or 2.5D or other 3D flash memory system such as
Multi-Chip-Module, SiP System-In-Package, PoP Package-on-package,
and Multi Chip Packaging using a combination of bond-wire, flip
chip, soldier ball and other die bonding and die connecting
techniques are applicable to the described herein inventions.
[0110] References to the present invention herein are not intended
to limit the scope of any claim or claim term, but instead merely
make reference to one or more features that may be covered by one
or more of the claims. Materials, processes and numerical examples
described above are exemplary only, and should not be deemed to
limit the claims. It should be noted that, as used herein, the
terms "over" and "on" both inclusively include "directly on" (no
intermediate materials, elements or space disposed there between)
and "indirectly on" (intermediate materials, elements or space
disposed there between). Likewise, the term "adjacent" includes
"directly adjacent" (no intermediate materials, elements or space
disposed there between) and "indirectly adjacent" (intermediate
materials, elements or space disposed there between). For example,
forming an element "over a substrate" can include forming the
element directly on the substrate with no intermediate
materials/elements there between, as well as forming the element
indirectly on the substrate with one or more intermediate
materials/elements there between. The invention described herein
applies to other non-volatile memory, such as stacked floating
gate, ReRAM (Resistive RAM), MRAM (magnoresistive random access
memory), FeRAM (Ferroelectric RAM), ROM, and other known memory
devices.
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