Magnetic random access memory array and semiconductor device

Abstract

The present invention provides a magnetic random access memory array and a semiconductor device. Under the premise of occupying the same substrate area, through the layout of multiple active areas extending along the third direction and multiple word lines extending along the second direction, the substrate area space can be effectively utilized to achieve a smaller characteristic size of the memory cell and a higher storage density, and the chip cost is lower. Furthermore, a unit area of ​​4F can be achieved. 2 (F is the characteristic size) of the densely packed storage array to improve storage density and device integration.

Description

Technical Field

[0001] The present invention relates to the field of memory technology, and in particular to a magnetic random access memory array and a semiconductor device. Background Art

[0002] Magnetic Random Access Memory (MRAM) is a new memory and storage technology that can read and write randomly as fast as SRAM / DRAM, and can also retain data permanently after power failure like Flash memory. Each MRAM storage cell consists of a magnetic tunnel junction and a MOS tube, or two magnetic tunnel junctions and two MOS tubes. Each storage cell needs to be connected to three wires: the gate of the MOS tube is connected to the word line of the chip, which is responsible for turning on or off the unit; one pole of the MOS tube (source or drain) is connected to the source line, and the other pole of the MOS tube (drain or source) is connected to one pole of the magnetic tunnel junction, and the other pole of the magnetic tunnel junction is connected to the bit line.

[0003] As MRAM technology continues to advance, how to further reduce the size of MRAM storage cells to increase the density of MRAM has become one of the technical issues that technicians in this field need to solve urgently. Summary of the invention

[0004] An object of the present invention is to provide a magnetic random access memory array and a semiconductor device having a reduced memory cell area and an increased memory density.

[0005] In order to solve the above technical problems, the present invention provides a magnetic random access memory array, comprising:

[0006] A semiconductor substrate, wherein a plurality of active regions are arranged in a strip shape along a first direction and a second direction, each of the active regions extends along a third direction, the second direction is perpendicular to the first direction, and the third direction intersects both the first direction and the second direction;

[0007] A plurality of word lines are arranged on the semiconductor substrate along a first direction, and each of the word lines extends along a second direction and straddles a plurality of the active regions, and each of the word lines divides the corresponding active region into a source region and a drain region;

[0008] A plurality of source lines, each source line is formed through the first metal layer and connected to a corresponding source region;

[0009] A plurality of magnetic tunnel junctions, each of which has a bottom connected to a corresponding drain region through a corresponding second metal layer and a top connected to a third metal layer, wherein the third metal layer is used to form a corresponding bit line.

[0010] Optionally, each of the active regions and the word line disposed above the active region forms a corresponding MOS transistor, and the corresponding MOS transistor formed at the active region and the corresponding magnetic tunnel junction above the drain region form a storage unit.

[0011] Optionally, each of the storage units has at least one MOS tube.

[0012] Optionally, the source region and drain region of the MOS tube of each storage unit other than the storage unit on the array boundary of the magnetic random access memory array are shared with the surrounding adjacent storage units, and the area of ​​each storage unit is 4F. 2 , where F is the feature size.

[0013] Optionally, each of the drain regions is connected to the second metal layer at the bottom of the magnetic tunnel junction through a drain contact plug located above the drain region, and each of the source regions is connected to the source line through a source contact plug located above the source region; the drain contact plugs and the source contact plugs are arranged in rows and columns into a plug array.

[0014] Optionally, the row direction of the plug array is the first direction, the column direction of the plug array is the second direction, and a row of source contact plugs is sandwiched between two rows of drain contact plugs.

[0015] Optionally, the bit line and the source line are arranged in parallel, or the bit line and the source line are arranged to intersect in different planes.

[0016] Optionally, the bit line intersects the word line perpendicularly and in a different plane, or the bit line intersects the word line in a different plane and is not perpendicular.

[0017] Optionally, an angle between the first direction and the third direction includes but is not limited to 45 degrees.

[0018] Based on the same inventive concept, the present invention also provides a semiconductor device, including the magnetic random access memory array described in the present invention.

[0019] Compared with the prior art, the magnetic random access memory array and the semiconductor device having the magnetic random access memory array of the present invention have the following beneficial effects:

[0020] 1. Under the premise of occupying the same substrate area, through the layout of multiple active areas extending along the first direction and multiple word lines extending along the second direction, the substrate area space can be effectively utilized to achieve a smaller feature size of the memory cell and a higher storage density, and the chip cost is lower.

[0021] 2. The unit area can be 4F 2(F is the characteristic size) of the densely packed storage array to improve storage density and device integration.

[0022] 3. The source line and the bit line can be made perpendicular to the word line and the projections of the source line and the bit line do not overlap, thereby increasing the distance between two adjacent bit lines or two source lines, reducing the difficulty of making the source line, the bit line, the drain contact plug and the source contact plug, and then reducing the interference between adjacent storage cells and improving device performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the layout structure of a magnetic random access memory array according to a specific embodiment of the present invention (structures such as bit lines BL and source lines SL are omitted);

[0024] Figure 2 It is a schematic diagram of the layout of source lines and bit lines of a magnetic random access memory array according to a specific embodiment of the present invention;

[0025] Figure 3 is along Figure 2 A schematic diagram of a cross-sectional structure of the XX' line in the magnetic random access memory array shown (structures such as the interlayer dielectric layer are omitted, and the source line and the bit line are parallel and do not overlap in the vertical direction);

[0026] Figure 4 is along Figure 2 Another schematic diagram of the cross-sectional structure of the XX' line in the magnetic random access memory array shown (structures such as the interlayer dielectric layer are omitted, and the source line and the bit line overlap in the vertical direction and may intersect in different planes);

[0027] Figure 5 It is another schematic diagram of the layout of source lines and bit lines of a magnetic random access memory array according to a specific embodiment of the present invention. DETAILED DESCRIPTION

[0028] The technical solution proposed by the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. According to the following description, the advantages and features of the present invention will become clearer. It should be noted that the accompanying drawings are all in a very simplified form and use non-precise proportions, which are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention. The meaning of "and / or" in this article is to choose one or both.

[0029] Please refer to Figures 1 to 3 An embodiment of the present invention provides a magnetic random access memory array, including a semiconductor substrate 100, a plurality of word lines WL, a plurality of source lines SL, a plurality of magnetic tunnel junctions 106, and a plurality of bit lines BL.

[0030] The semiconductor substrate 100 may be a silicon substrate, a germanium substrate, a silicon-germanium substrate, a silicon-on-insulator (SOI) substrate, a germanium-on-insulator (GOI) substrate, etc. Impurities may be implanted into the semiconductor substrate 100 to form an active region 101, and the impurities may include n-type impurities such as phosphorus and arsenic, or p-type impurities such as boron and gallium. The interval between adjacent active regions 101 is a field region (not shown), and the field region may be formed by a shallow trench isolation (STI) process or a local field oxidation isolation (LOCOS) process.

[0031] In this embodiment, a plurality of active regions 101 are formed in the semiconductor substrate 100, and all active regions 101 are in strip shape and can be arranged along a first direction and a second direction perpendicular to each other, and the length of the active region 101 extends along a third direction, the third direction intersects with both the first direction and the second direction, and the angle between the third direction and the first direction includes but is not limited to 45 degrees, that is, it can be 45 degrees or not. All active regions 101 are arranged in an array, wherein each active region 101 can extend continuously in the third direction to the entire third direction length of the corresponding semiconductor substrate 100, or can be disconnected in certain areas, thereby forming a plurality of active region 101 blocks aligned in the first direction and the second direction.

[0032] A plurality of word lines WL are arranged along a first direction and formed on the semiconductor substrate 100, and each word line WL extends along a second direction and is arranged across a plurality of active regions 101, wherein the second direction is perpendicular to the first direction. Each word line WL divides the corresponding active region 101 into a source region 101a and a drain region 101b. Each active region 101 and the corresponding word line WL arranged above the active region 101 form a corresponding MOS transistor, that is, the word line WL serves as the gate of the MOS transistor, the active regions 101 on both sides of the word line WL are the source region 101a and the drain region 101b of the MOS transistor respectively, and the active region 101 covered by the word line WL is the channel region of the MOS transistor. The material of the word line WL may be polysilicon or metal gate material, and there is a gate dielectric layer (not shown) between the word line WL and the semiconductor substrate 100, and a sidewall (SideWall or Spacer, not shown) may also be formed on the sidewall of the word line WL. The line width of the word line WL may be equal to or smaller than the column pitch of the plug array formed by the source contact plug and the drain contact plug to avoid the word line WL overlapping with other active regions 101 to cause interference between memory cells and affect device performance.

[0033] A plurality of source lines SL are formed through the first metal layer 103 and connected to corresponding source regions 101 a through corresponding source contact plugs 102 .

[0034] The bottom of each magnetic tunnel junction (MTJ) 106 is connected to the corresponding drain region 101b through the corresponding second metal layer 105 and the drain contact plug 104 under the second metal layer 105, and the top of each magnetic tunnel junction 106 is connected to the third metal layer 107, and the third metal layer 107 is used to form the corresponding bit line BL. Among them, the MTJ 106 is only formed on the drain region of the MOS transistor connected to the bit line BL, and the MOS transistor formed at each active area 101 and the magnetic tunnel junction 106 above the active area 101 form a storage unit cell (such as Figure 1 As shown in the dotted box in the figure, the area of ​​each storage unit cell is 2F*2F=4F 2 The source contact plug 102, the drain contact plug 104, the first metal layer 103, the second metal layer 105, and the third metal layer 107 may all include metal and / or metal nitride. All the source contact plugs 102 and the drain contact plugs 104 are arranged in rows and columns into a plug array, the row direction of the plug array is a first direction perpendicular to the second direction, and the column direction of the plug array is the second direction, so that the magnetic tunnel junctions 106 are arranged into a corresponding array according to the layout of the plug array.

[0035] The magnetic tunnel junction 106 may include a barrier layer (not shown), a pinning layer, a lower ferromagnetic layer, an antiferromagnetic coupling spacer layer, and an upper ferromagnetic layer, etc., which are sequentially formed on the second metal layer 105. The barrier layer may reduce or avoid abnormal growth of metal in the pinning layer, the lower ferromagnetic layer, the ferromagnetic coupling spacer layer, and the upper ferromagnetic layer, etc. The barrier layer may include an amorphous metal or metal nitride, such as tantalum, tantalum nitride, titanium, titanium nitride, etc. The pinning layer may include, for example, FeMn, IrMn, PtMn, MnO, MnS, MnTe, MnF2, FeF2, FeCl2, FeO, CoCl2, CoO, NiCl2, NiO, Cr, etc. The lower ferromagnetic layer and the upper ferromagnetic layer may include, for example, Fe, Ni, Co, etc. The antiferromagnetic coupling spacer layer may include, for example, Ru, Ir, Rh, etc. The lower ferromagnetic layer may have a fixed or "pinned" magnetic orientation, while the upper ferromagnetic layer has a variable or "free" magnetic orientation and may be switched between two or more different magnetic polarities, each representing a different data state, such as a different binary state. However, in other embodiments, the MTJ 106 may be "flipped" vertically so that the lower ferromagnetic layer has a "free" magnetic orientation and the upper ferromagnetic layer has a "fixed" magnetic orientation.

[0036] Please refer to Figure 3In this embodiment, the bit line BL and the source line SL are arranged in parallel, and the metal layers where the bit line BL and the source line SL are located do not overlap at all. The bit line BL contacts the drain region 101b through the magnetic tunnel junction 106, the second metal layer 105 and the drain contact plug 104 in sequence, and the source line SL contacts the source region 101a through the source contact plug 102. All the drain contact plugs 104 and the source contact plugs 102 are arranged in a plug array along the first direction and the second direction, please refer to Figure 1 and Figure 2 , in a top-view angle, the row direction of the plug array is the first direction, the column direction of the plug array is the second direction, the drain contact plugs 104 of two adjacent rows are aligned, the drain contact plugs 104 of two adjacent columns are aligned, the source contact plugs 102 of two adjacent rows are aligned, the source contact plugs 102 of two adjacent columns are aligned, and a row of source contact plugs 102 is sandwiched between the drain contact plugs 104 of two adjacent rows. And the bit line BL intersects and is perpendicular to the word line WL in different planes (that is, the projection of the bit line BL and the word line WL on the surface of the semiconductor substrate 100 intersects and is perpendicular). At this time, in this embodiment, two adjacent storage cells can share the bit line BL and the source line SL. Figure 3 The structure of source line SL and bit line BL shown in the figure can reduce the interference between adjacent memory cells and improve the device performance. On the other hand, it can relatively increase the distance between two adjacent contact plugs on two adjacent bit lines BL, reduce the difficulty of making contact plugs, avoid problems such as bridging, and improve the device performance. At this time, the intersection connection part of each word line WL and each bit line BL corresponds to a memory cell. Each memory cell is a 1 transistor (T) 1 magnetic tunnel junction (MTJ) structure, or a 2 transistor (T) 2 magnetic tunnel junction (MTJ) structure. The area of ​​each memory cell is 2F*2F=4F. 2 Wherein F is a characteristic dimension, and the length of each storage unit cell in a direction perpendicular to the second direction is 2F, and the length in the second direction is 2F.

[0037] In addition, adjacent word lines WL, adjacent bit lines BL, adjacent source lines SL, adjacent magnetic tunnel junctions 106, adjacent contact plugs, word line WL and bit line BL, word line WL and source line SL, word line WL and magnetic tunnel junction 106, source line SL and magnetic tunnel junction 106, source line SL and bit line, and second metal layers 105 of adjacent memory cell cells are all insulated and isolated by corresponding insulating dielectric layers (not shown).

[0038] It should also be noted that in the technical solution of the present invention, the layout of the bit lines BL and the source lines SL is not limited to the top view angle. Figure 2 The layout structure shown in the figure is not limited to the cross-sectional view. Figure 3 The layout structure shown can be any other suitable layout. For example, please refer to Figure 4 As shown, in other embodiments of the present invention, the bit line BL and the source line SL may also be arranged to intersect with each other in different planes, the metal layers where the bit line BL and the source line SL are located partially overlap, the bit line BL sequentially contacts the metal layer 103' of the metal layer 103 where the source line SL is located through the magnetic tunnel junction 106, the second metal layer 105 and the drain contact plug 104', the metal layer 103' contacts the drain region 101b through the drain contact plug 104, and the source line SL contacts the source region 101a through the source contact plug 102. The bit line BL is also perpendicular to the word line WL. For another example, please refer to Figure 5 In other embodiments of the present invention, the bit line BL and the source line SL are arranged in parallel, and the bit line BL intersects the word line WL in different planes but is not perpendicular (that is, the projection of the bit line BL and the word line WL on the surface of the semiconductor substrate 100 intersects and the angle is not 90 degrees), and optionally, the bit line BL and the source line SL are arranged along the third direction. In this case, the memory cells in two adjacent rows share the same bit line BL and / or the same source line SL.

[0039] Please refer to Figures 1 to 5 Based on the same inventive concept, an embodiment of the present invention further provides a semiconductor device, comprising the above-mentioned magnetic random access memory array, wherein the structures of the bit lines BL and the source lines SL of the magnetic random access memory array can be as follows: Figure 3 or Figure 4 The semiconductor device may be a memory, a sensitive amplifier, a magnetic sensor, a storage-computing integrated chip, etc.

[0040] In summary, the magnetic random access memory array and the semiconductor device having the magnetic random access memory array of the present invention can effectively utilize the substrate area space under the premise of occupying the same substrate area through the layout of multiple active areas extending along the third direction and multiple word lines extending along the second direction, thereby achieving a smaller characteristic size of the memory cell and a higher storage density, and a lower chip cost. Furthermore, a unit area of ​​4F can be achieved. 2 (F is the characteristic size) of the densely packed storage array to improve storage density and device integration.

[0041] The above description is only a description of the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention. Any changes or modifications made by a person skilled in the art in the field of the present invention based on the above disclosure shall fall within the scope of protection of the claims.

Claims

1. A magnetic random access memory array, characterized in that: include: A semiconductor substrate, wherein a plurality of active regions are arranged in a strip shape along a first direction and a second direction, each of the active regions extends along a third direction, the second direction is perpendicular to the first direction, and the third direction intersects both the first direction and the second direction; A plurality of word lines are arranged on the semiconductor substrate along a first direction, and each of the word lines extends along a second direction and straddles a plurality of the active regions, each of the word lines divides the corresponding active region into a source region and a drain region, and each of the active regions and the word line disposed above the active region form a corresponding MOS tube; A plurality of source lines, each of the source lines is formed through the first metal layer and connected to a corresponding source region; A plurality of magnetic tunnel junctions, each of which is connected to the corresponding drain region at the bottom through the corresponding second metal layer and connected to the third metal layer at the top, and the third metal layer is used to form a corresponding bit line; Wherein, each of the active regions extends continuously in the third direction and crosses over at least two of the word lines.

2. The magnetic random access memory array according to claim 1, characterized in that: The corresponding MOS tube formed at the active area and the corresponding magnetic tunnel junction above the drain area form a storage unit.

3. The magnetic random access memory array as claimed in claim 2, characterized in that: Each of the storage units has at least one MOS tube.

4. The magnetic random access memory array as claimed in claim 3, characterized in that: The source region and drain region of the MOS tube of each memory cell except the memory cells on the array boundary of the magnetic random memory array are shared with the surrounding adjacent memory cells, and the area of ​​each memory cell is 4F. 2 , where F is the feature size.

5. The magnetic random access memory array according to claim 1, characterized in that: Each of the drain regions is connected to the second metal layer at the bottom of the magnetic tunnel junction through a drain contact plug located above the drain region, and each of the source regions is connected to the source line through a source contact plug located above the source region; the drain contact plugs and the source contact plugs are arranged in rows and columns to form a plug array.

6. The magnetic random access memory array as claimed in claim 5, characterized in that: The row direction of the plug array is the first direction, the column direction of the plug array is the second direction, and a row of source contact plugs is sandwiched between two rows of drain contact plugs.

7. The magnetic random access memory array according to claim 1, characterized in that: The bit line and the source line are arranged in parallel, or the bit line and the source line are arranged to intersect in different planes.

8. The magnetic random access memory array according to claim 1 or 7, characterized in that: The bit line intersects the word line perpendicularly and in a different plane, or the bit line intersects the word line in a different plane and is not perpendicular.

9. The magnetic random access memory array according to claim 1, characterized in that: The angle between the first direction and the third direction includes but is not limited to 45 degrees.

10. A semiconductor device, characterized in that: The invention comprises the magnetic random access memory array as claimed in any one of claims 1 to 9.

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