CN1790543B - Method for generating magnetic RAM reference signal - Google Patents
Method for generating magnetic RAM reference signal Download PDFInfo
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- CN1790543B CN1790543B CN 200410081514 CN200410081514A CN1790543B CN 1790543 B CN1790543 B CN 1790543B CN 200410081514 CN200410081514 CN 200410081514 CN 200410081514 A CN200410081514 A CN 200410081514A CN 1790543 B CN1790543 B CN 1790543B
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- storage unit
- size
- magnetosphere
- mram
- word line
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Abstract
The invention discloses a generation method of MRAM reference signal, which is characterized by the following: utilizing the extra current to generate the magnet; changing the separation angle of two magnetic layer magnetization directions; regarding the middle state as the reference signal; utilizing the separation angle to affirm the variation rule; reading the information in the MRAM storing unit. The invention improves the reading speed, which doesn't reduce the storing density.
Description
Technical field
The invention belongs to microelectronics and solid-state electronic techniques field, it is particularly related to the magnetic RAM technology.
Background technology
Magnetic RAM is a kind of novel storer based on giant magnetoresistance (" Giant MagnetoResistance; GMR ") effect, have non-volatile, zero access, high capacity, low-power consumption, radioresistance, advantage such as anti-interference, can be widely used in various solid-state memories and chip system, being expected to becomes desirable " general-purpose storage ", has vast potential for future development.
MRAM is made up of the magnetoresistance effect memory cell array of spin valve structure, counterfeit spin valve structure or magnetic tunnel junction structure.The generation scheme of existing known MRAM reference signal has two kinds: a kind of is outside memory cell, makes reference resistance specially in order to produce reference signal; Another kind is to utilize memory cell itself to produce reference signal.Preceding a kind of design proposal can be carried out read operation fast, but higher to technological requirement, in same memory cell block, if manufacturing tolerance is big, then the resistance of each memory cell of whole memory cell block has remarkable difference, thereby makes the read operation failure; Owing to the influence of manufacturing tolerance, each memory cell block all must be made reference resistance separately in addition, has reduced the integrated level of device, has promptly reduced the storage density of MRAM.A kind of design proposal in back utilizes memory cell itself to produce reference signal, need carry out read-write operation repeatedly to memory cell during read procedure, greatly reduce storer and read speed, another shortcoming of this design proposal is that its read procedure is that a kind of destructiveness is read simultaneously.
More than two kinds of design proposals contradiction each other on storage density and time for reading, obtain high reading speed and will sacrifice storage density, vice versa.Therefore finding a kind of more rational reference signal generation scheme is the key point that obtains high storage density and high reading speed.
Summary of the invention
The production method that the purpose of this invention is to provide a kind of magnetic RAM MRAM reference signal utilizes method of the present invention can realize reading fast of canned data among the MRAM, and it has the advantage that reads and do not reduce storage density at a high speed.
In order to describe content of the present invention easily, at first make term definition:
Magnetic RAM (Magnetic Random Access Memory is called for short MRAM) is meant and utilizes magnetic material as random access memory that especially, indication magnetic RAM MRAM of the present invention is meant and utilizes magnetoresistance effect to be used as random access memory.
Figure 1 shows that the basic structure of any one storage unit among the existing MRAM.
Any one storage unit shown in Fig. 1 is the magnetoresistance effect of spin valve structure, counterfeit spin valve structure or magnetic tunnel junction structure, and its basic structure comprises: magnetosphere 1, middle layer (or insulation course) 2 and magnetosphere 3.
Magnetosphere 1 in the storage unit is the information recording layer of this unit, generally is the soft magnetic metal membraneous material, as NiFe, CoFe etc.
Magnetosphere 3 in the storage unit is another magnetospheres in this unit, generally is the soft magnetic metal membraneous material, and its coercive force generally coercive force than magnetosphere 1 is big.
The basic structure of any one storage unit among the MRAM is by magnetosphere 1, and middle layer 2 and magnetosphere 3 constitute.Its shape can be shapes such as rectangle, corner cut rectangle, ellipse.
MRAM is made up of by certain structure a plurality of above-mentioned storage unit, and its typical basic structure as shown in Figure 2.Its neutrality line is meant the plain conductor that any one storage unit top is attached thereto, and word line is meant the plain conductor of any one storage unit below.Any one storage unit all links to each other with a metal-oxide-semiconductor.Fig. 3 is the sectional view of a basic unit of storage 8 arbitrarily among the MRAM.
Storage unit 8 is any one storage unit in the MRAM structure among Fig. 2.The magnetosphere 3 of storage unit 8 links to each other with the drain electrode of a metal-oxide-semiconductor 7 arbitrarily.
Fig. 2 neutrality line 4 is meant the plain conductor that links to each other with the magnetosphere 1 of any storage unit 8.
Word line 5 among Fig. 2 and Fig. 1 is meant and is positioned at storage unit 8 belows, is used for the plain conductor of storage unit read-write operation.8 insulation of word line 5 and storage unit.
Control line 6 is meant with the grid level of metal-oxide-semiconductor 7 and links to each other, is used to control the plain conductor of metal-oxide-semiconductor 7 conductings and shutoff.
In the mram cell structure of Fig. 2, bit line extends along the row of memory cell, and word line extends along the row of memory cell, places memory cell on the point of crossing of bit line and word line.
The invention provides a kind of production method of magnetic RAM MRAM reference signal, it is to adopt following step (workflow is as shown in Figure 4):
Step 1: in MRAM, select a storage unit 8 arbitrarily, as shown in Figure 2;
Step 2: making alive V on the control line 6 of the metal-oxide-semiconductor 7 that links to each other with the storage unit 8 (below abbreviation storage unit 8) selected in the step 1
B, V
BSize be the cut-in voltage of used metal-oxide-semiconductor 7;
Step 3: with bit line 4 that the magnetosphere 1 of storage unit 8 links to each other in galvanization I
D, I
DSize depend on the material of magnetosphere 1, middle layer 2 and magnetosphere 3 of size, storage unit 8 of storage unit 8 and the thickness of each layer film; For the storage unit of Spin Valve or counterfeit spin valve structure, I
DSize is the mA magnitude, for the storage unit of tunnel junction structure, I
DSize is 10
-1The mA magnitude;
Step 4: the voltage V that measures and preserve storage unit 8 two ends this moment
Data
Step 5: galvanization I in the word line 5 below storage unit 8
W, I
WSize depend on the material of magnetosphere 1, middle layer 2 and magnetosphere 3 of size, storage unit of storage unit and the thickness of each layer film, also depend on the distance of any storage unit and word line 5.Especially, the electric current I in the word line 5
WSize can not be greater than particular current I
S, I
SBe meant that reverse needed size of current takes place the magnetospheric direction of magnetization that makes in the word line in the storage unit 8;
Step 6: the voltage V that measures and preserve storage unit 8 two ends this moment
Ref
Step 7: comparative voltage V
DataAnd V
RefSize, if V
Data＞V
Ref, then the logical value of canned data is " 1 " (or " 0 ") in the storage unit 8; Otherwise, if V
Data＜V
Ref, then the logical value of canned data is " 0 " (or " 1 ") in the storage unit 8;
Step 8: cancel the electric current I in the bit line 4
D, the electric current I in the word line 5
W, cancel the voltage V on the control line 6
B
Through after the above step, just can realize reading to any storage element 8 stored informations of step 1 selection; As a same reason, adopt above-mentioned steps, can read the canned data of other any one storage unit among the MRAM, thereby realize reading all cell stores information among the MRAM.
Need explanation: in step 7, work as V
Data＞V
RefThe time, if the logical value of canned data is " 1 ", then V in the storage unit 8
Data＜V
RefThe time storage unit 8 in the logical value of canned data be " 0 "; Otherwise, work as V
Data＞V
RefThe time, if the logical value of canned data is " 0 ", then V in the storage unit 8
Data＜V
RefThe time storage unit 8 in the logical value of canned data be " 1 ".
Principle of work of the present invention:
Theory shows, there are the Changing Pattern of determining in the resistance of memory cell and memory cell two magnetosphere direction of magnetization angles, utilize this Changing Pattern, the present invention has designed and a kind ofly can improve the reference signal that storage density significantly do not reduce reading speed again and produce scheme.
When memory cell two magnetospheric direction of magnetization angles are 0 when spending, this storage unit is in most low-resistance attitude R
Min, presentation logic value " 0 " (or " 1 "), when memory cell two magnetospheric direction of magnetization angles are 180 when spending, this unit is in maximum resistance attitude Rmax, presentation logic value " 1 " (or " 0 ").According to theoretical analysis, there are following relation in memory cell resistance R and its two magnetospheric direction of magnetization angle theta: R=(R
Max-R
Min) sin (θ/2)+R
MinUtilize this Changing Pattern, galvanization I in word line
w, the magnetic field of generation makes the direction of magnetization of the magnetosphere 1 of memory cell rotate θ angle (45＞θ＞0), and at this moment memory cell resistance becomes R=(Rmax-R
Min) sin (θ/2)+R
MinIf storage unit just is initially located in " 1 " (or " 0 ") attitude, promptly cell resistance is Rmax, and R＜Rmax is then arranged, otherwise if storage unit just is initially located in " 0 " (or " 1 ") attitude, promptly cell resistance is R
Min, R＞R is then arranged
MinThereby can pass through comparison resistance R and R
Max, R
MinThe size logical value of coming the determine memory unit.In the time of relatively, galvanization I on storage unit at first
D, this moment, the voltage signal of unit was V
Data, galvanization I in word line then
w, the magnetic field of generation makes the direction of magnetization of the magnetosphere 1 of memory cell rotate θ angle (45＞θ＞0), and this moment, the voltage signal of unit was V
RefCompare V
DataAnd V
Ref, if V
Date＜V
Ref, then unit records infologic value is " 0 " (or " 1 "), if V
Date＞V
Ref, then unit records infologic value is " 1 " (or " 0 ").
Core of the present invention is: produce magnetic field by impressed current, the angle that changes storage unit two magnetosphere direction of magnetization obtains intermediate state, and with the voltage signal of this intermediate state as the reference signal, utilize the angle of two magnetosphere direction of magnetization in the resistance value of information memory cell among the MRAM and the storage unit to have the Changing Pattern of determining, realize reading of location information among the MRAM.
Beneficial effect of the present invention:
Compare with first kind of design proposal in the background technology, the present invention has utilized memory cell self to produce reference signal, although so because technology and Effect of Environmental, cause different in the mram memory spare, resistive memory cell different or same resistive memory cell may change in time, the MRAM device still can produce the reference signal that can be used for comparison, thereby reduced requirement, improved the reliability of device, and can greatly improve device stores density technology.
Compare with second kind of design proposal in the background technology, the magnetic field that the present invention's galvanization in word line produces just allow storage unit wherein one deck magnetosphere direction of magnetization rotate a very little angle, and it is not enough so that its direction of magnetization is reverse, after the current vanishes in the word line, because the effect of magnetic anisotropy, direction of magnetization can automatically restore to virgin state, thereby this design proposal does not change original information in the memory cell.Thereby this design proposal improved the reading speed of data, and its read procedure is that non-destructive is read.
Description of drawings:
Fig. 1 is the basic structure synoptic diagram of any one storage unit among the MRAM
Wherein, the 1st, magnetosphere; The 2nd, the middle layer; The 3rd, magnetosphere.
Fig. 2 is the basic structure synoptic diagram of MRAM.
Wherein, the 4th, bit line; The 5th, word line; The 6th, control line; The 7th, metal-oxide-semiconductor; The 8th, any one storage unit.
Fig. 3 is the schematic cross-section of any one storage unit 8 in the basic structure of MRAM
Wherein, the 1st, magnetosphere; The 2nd, the middle layer; The 3rd, magnetosphere; The 4th, bit line; The 5th, word line; The 6th, control line; The 7th, metal-oxide-semiconductor.
Fig. 4 is the read operation process flow diagram of any one storage unit 8 of MRAM among the present invention.
Embodiment:
In order to be described in more detail method of the present invention, illustrate below.
The magnetosphere 1 of storage unit is selected the NiFe material for use, and this layer film thickness is 15nm, middle layer 2 AlOx material, and this layer film thickness is 1.5nm, magnetosphere 3 NiFeCo material, this layer film thickness is 30nm.Storage unit is elected ellipse as, and length breadth ratio is 4, and major axis is 40nm, and minor axis is 10nm.
In the MRAM structure, the word line 5 below the storage unit 8 is 130nm apart from storage unit 8 arbitrarily.When at this moment any storage unit 8 being carried out read operation, the electric current I in the bit line 4
DCan be taken as 0.1mA, electric current I in the word line 5
W=5mA.Impressed voltage V on the control line 6 of the metal-oxide-semiconductor 7 that links to each other with storage unit
a=2V.
Can read institute's canned data logical value in any storage unit 8 according to above-mentioned flow process.
Claims (1)
1. the production method of a magnetic RAM MRAM reference signal is characterized in that it is a step below adopting:
Step 1: in MRAM, select a storage unit (8) arbitrarily;
Step 2: the control line (6) at the metal-oxide-semiconductor (7) that links to each other with the storage unit (8) of selection in the step 1 is gone up making alive V
B, V
BSize be the cut-in voltage of used metal-oxide-semiconductor (7);
Step 3: with bit line (4) that the magnetosphere (1) of storage unit (8) links to each other in galvanization I
D, I
DSize depend on the size of storage unit (8), magnetosphere (1), middle layer (2) and the material of magnetosphere (3) and the thickness of each layer film of storage unit (8); For the storage unit of Spin Valve or counterfeit spin valve structure, I
DSize is the mA magnitude, for the storage unit of tunnel junction structure, I
DSize is 10
-1The mA magnitude;
Step 4: the voltage V that measures and preserve storage unit (8) two ends this moment
Data
Step 5: galvanization I in the word line (5) below storage unit (8)
W, I
WSize depend on the size of storage unit, the magnetosphere of storage unit (1), middle layer (2) and the material of magnetosphere (3) and the thickness of each layer film, also depend on the distance of any storage unit and word line (5); Electric current I in the word line (5)
WSize can not be greater than particular current I
S, I
SBe meant that reverse needed size of current takes place the magnetospheric direction of magnetization that makes in the word line in the storage unit (8);
Step 6: the voltage V that measures and preserve storage unit (8) two ends this moment
Ref
Step 7: comparative voltage V
DataAnd V
RefSize, if V
Data＞V
Ref, then the logical value of canned data is " 1 " or " 0 " in the storage unit (8); Otherwise, if V
Data＜V
Ref, then the logical value of canned data is " 0 " or " 1 " in the storage unit (8);
Step 8: cancel the electric current I in the bit line (4)
D, the electric current I in the word line (5)
W, cancel the voltage V on the control line (6)
B
Through after the above step, just can realize reading to any storage unit (8) stored information of step 1 selection; As a same reason, adopt above-mentioned steps, can read the canned data of other any one storage unit among the MRAM, thereby realize reading all cell stores information among the MRAM.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 200410081514 CN1790543B (en) | 2004-12-17 | 2004-12-17 | Method for generating magnetic RAM reference signal |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 200410081514 CN1790543B (en) | 2004-12-17 | 2004-12-17 | Method for generating magnetic RAM reference signal |
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| Publication Number | Publication Date |
|---|---|
| CN1790543A CN1790543A (en) | 2006-06-21 |
| CN1790543B true CN1790543B (en) | 2010-05-05 |
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|---|---|---|---|
| CN 200410081514 Expired - Fee Related CN1790543B (en) | 2004-12-17 | 2004-12-17 | Method for generating magnetic RAM reference signal |
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| CN112349321B (en) * | 2019-08-06 | 2024-03-12 | 上海磁宇信息科技有限公司 | Magnetic random access memory chip architecture using common reference voltage |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1182271A (en) * | 1996-10-24 | 1998-05-20 | 日本电气株式会社 | Semiconductor memory device and method of reading datain semiconductor momory device |
| CN1254929A (en) * | 1998-11-19 | 2000-05-31 | 因芬尼昂技术股份公司 | Magnetic storage |
| US6385111B2 (en) * | 2000-06-20 | 2002-05-07 | Hewlett-Packard Company | Reference signal generation for magnetic random access memory devices |
| US20040246761A1 (en) * | 2003-03-27 | 2004-12-09 | Toshiyuki Nishihara | Data reading method, data writing method, and semiconductor memory device |
-
2004
- 2004-12-17 CN CN 200410081514 patent/CN1790543B/en not_active Expired - Fee Related
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1182271A (en) * | 1996-10-24 | 1998-05-20 | 日本电气株式会社 | Semiconductor memory device and method of reading datain semiconductor momory device |
| CN1254929A (en) * | 1998-11-19 | 2000-05-31 | 因芬尼昂技术股份公司 | Magnetic storage |
| US6385111B2 (en) * | 2000-06-20 | 2002-05-07 | Hewlett-Packard Company | Reference signal generation for magnetic random access memory devices |
| US20040246761A1 (en) * | 2003-03-27 | 2004-12-09 | Toshiyuki Nishihara | Data reading method, data writing method, and semiconductor memory device |
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