Patent Description:
Magnetoresistive random access memory (MRAM) is a type of memory device containing an array of MRAM cells that store data using resistance values instead of electronic charges. Each MRAM cell includes a magnetic tunnel junction (MTJ) unit whose resistance can be adjusted to represent a logic state "<NUM>" or "<NUM>.

Conventionally, the magnetic tunnel junction (MTJ) unit is comprised of a fixed magnetic layer, a free magnetic layer, and a tunnel layer disposed there between. The resistance of the magnetic tunnel junction (MTJ) unit can be adjusted by changing a direction of a magnetic moment of the free magnetic layer with respect to that of the fixed magnetic layer. When the magnetic moment of the free magnetic layer is parallel to that of the fixed magnetic layer, the resistance of the magnetic tunnel junction (MTJ) unit is low, whereas when the magnetic moment of the free magnetic layer is anti-parallel to that of the fixed magnetic layer, the resistance of the magnetic tunnel junction (MTJ) unit is high. The magnetic tunnel junction (MTJ) unit is coupled between top and bottom electrodes, and an electric current flowing through the magnetic tunnel junction (MTJ) from one electrode to another can be detected to determine the resistance, and therefore the logic state of the magnetic tunnel junction (MTJ).

<CIT> (<CIT>), relates to a magnetic memory and manufacturing thereof. <NUM> to <NUM> show an embodiment where a contact plug is provided between two adjacent MTJs arranged in a first direction. The contact plug may be rectangular in a top view.

<CIT> (<CIT>), relates to a structure and a method for a magnetic memory device with proximity writing.

<CIT> (<CIT>), relates to MRAM integration techniques for technology.

<CIT> (<CIT>), relates to a resistance change type memory and a manufacturing method thereof.

<CIT> (<CIT>), relates to a semiconductor memory device.

<CIT> (<CIT>), relates to a magnetic memory and a manufacturing method thereof.

<CIT> (<CIT>), relates to a contact for non-volatile memory and a method thereof. The document teaches to orient the long axis of the contact perpendicular to an axis along which adjacent memory cells are spaced apart from each other.

<CIT> (<CIT>), relates to a method for designing a layout of a semiconductor.

<CIT> (<CIT>), relates to semiconductor devices and methods of fabricating the same.

The present invention provides a magnetic tunnel junction (MTJ) device as defined in claim <NUM>, which includes a metal interconnection having a long shape at a top view between two magnetic tunnel junction elements, thereby enlarging the distance between the metal interconnection and the magnetic tunnel junction elements, while maintaining the contact area at an interface of the metal interconnection. This can avoid short circuit as well as keep low contact resistance.

<FIG> schematically depicts a cross-sectional view of a magnetic tunnel junction (MTJ) device according to an embodiment of the present invention. As shown in <FIG>, a dielectric layer <NUM> is formed on a substrate (not shown), wherein the dielectric layer <NUM> may be an oxide layer, which may be an inter-metal dielectric layer, but it is not limited thereto. The dielectric layer <NUM> is depicted only in a magnetoresistive random access memory area in this embodiment, and magnetoresistive random access memory cells are in the magnetoresistive random access memory area. Furthermore, the dielectric layer <NUM> may be formed in other not depicted areas such as logic areas and alignment mark areas etc. A plurality of metal lines 112a/112b/112c/112d are formed in the dielectric layer <NUM> to connect to above magnetic tunnel junction (MTJ) devices and metal interconnections. The four metal lines 112a/112b/112c/112d are depicted in the diagrams, but the number of the metal lines 112a/112b/112c/112d is not restricted thereto. The metal lines 112a/112b/112c/112d may include copper, and a barrier layer (not shown) may surround each of the metal lines 112a/112b/112c/112d, wherein the barrier layer may be a tantalum nitride layer, but it is not limited thereto.

A cap layer <NUM> and a first dielectric layer <NUM> are sequentially formed on the dielectric layer <NUM>, and contact plugs <NUM> are in the first dielectric layer <NUM> and the cap layer <NUM> and connect to the metal lines 112a/112c. The cap layer <NUM> may be a carbon containing nitride layer, while the first dielectric layer <NUM> may be an oxide layer, but it is not limited thereto. Methods of forming the cap layer <NUM> and the first dielectric layer <NUM> may include the following steps. A cap layer (not shown) and a first dielectric layer (not shown) may blanketly cover the dielectric layer <NUM>, the cap layer and the first dielectric layer are patterned to form recesses (not shown) in the cap layer <NUM> and the first dielectric layer <NUM> and expose the metal lines 112a/112c, and then the contact plugs <NUM> fill up the recesses, wherein each of the contact plugs <NUM> may include a barrier layer <NUM> and a metal <NUM>. Methods of forming the barrier layers <NUM> and the metals <NUM> fill up the recesses may include: forming a barrier layer (not shown) conformally covering the recesses and the first dielectric layer <NUM>, a metal (not shown) filling up the recesses, removing the metal and the barrier layer exceeding from the recesses by a planarization process to form the barrier layers <NUM> and the metals <NUM>, wherein the barrier layers <NUM> surround the metals <NUM>. The barrier layers <NUM> may be titanium layers, titanium nitride layers or titanium/titanium nitride layers, and the metals <NUM> may be tungsten, but it is not limited thereto.

A second dielectric layer <NUM> is formed on the first dielectric layer <NUM>, and magnetic tunnel junction elements <NUM> are formed in the second dielectric layer <NUM>. More precisely, a seeding layer (not shown), a magnetic tunneling junction layer (not shown) and a top electrode layer (not shown) are deposited to cover the contact plugs <NUM> and the first dielectric layer <NUM>. Then, the top electrode layer, the magnetic tunneling junction layer and the seeding layer are patterned to form the magnetic tunnel junction elements <NUM>. Each of the magnetic tunnel junction elements <NUM> may include a seeding layer <NUM>, a magnetic tunneling junction <NUM> and a top electrode <NUM>. The seeding layer <NUM> may be a tantalum nitride layer, and the magnetic tunneling junction <NUM> may include multilayers, which may be composed by an insulating layer sandwiched by two ferromagnetic material layers, called magnetic tunnel junction (MTJ). The resistance of the magnetic tunnel junction (MTJ) unit can be adjusted by changing a direction of a magnetic moment of the free magnetic layer (one of the ferromagnetic material layer) with respect to that of the fixed magnetic layer (the other of the ferromagnetic material layer). When the magnetic moment of the free magnetic layer is parallel to that of the fixed magnetic layer, the resistance of the magnetic tunnel junction (MTJ) unit is low, whereas when the magnetic moment of the free magnetic layer is anti-parallel to that of the fixed magnetic layer, the resistance of the magnetic tunnel junction (MTJ) unit is high. The top electrode <NUM> may be a metal such as tungsten.

Thereafter, a cap layer (not shown) and a second dielectric layer (not shown) may blanketly cover the magnetic tunnel junction elements <NUM> and the first dielectric layer <NUM>, and then the second dielectric layer and the cap layer may be planarized to form a cap layer <NUM> covering the first dielectric layer <NUM> and sidewalls of the magnetic tunnel junction elements <NUM>, and the second dielectric layer <NUM> covering the cap layer <NUM> but exposing the top electrodes <NUM> of the magnetic tunnel junction elements <NUM>. The cap layer <NUM> may be a nitride layer while the second dielectric layer <NUM> may be an oxide layer, but it is not limited thereto.

A dual damascene process may be performed to form metal interconnections <NUM> in the second dielectric layer <NUM> between the magnetic tunnel junction elements <NUM>, and directly contacting the metal lines 112b/112d. Each of the metal interconnections <NUM> includes a contact plug part <NUM> and a metal part <NUM> stacked from bottom to top. In this embodiment, the contact plug part <NUM> and the metal part <NUM> have tapered sidewalls broadening smoothly from bottom to top. In other embodiments, as shown in <FIG>, each of the metal interconnections 160a includes a contact plug part 162a and a metal part 164a stacked from bottom to top, and the contact plug part 162a and the metal part 164a may have a curved connecting part, depending upon practical requirements.

A cap layer <NUM> and a third dielectric layer <NUM> are formed on the dielectric layer <NUM>, the magnetic tunnel junction elements <NUM> and the metal interconnections <NUM>, and metal interconnections <NUM>/<NUM>/<NUM>/<NUM> are formed in the third dielectric layer <NUM> and the cap layer <NUM>, wherein the metal interconnections <NUM>/<NUM> directly contact the magnetic tunnel junction elements <NUM> while the metal interconnections <NUM>/<NUM> directly contact the metal interconnections <NUM>. More precisely, a cap layer (not shown) and a third dielectric layer (not shown) may blanketly cover the dielectric layer <NUM>, the magnetic tunnel junction elements <NUM> and the metal interconnections <NUM>; the third dielectric layer and the cap layer are patterned to form recesses and expose the magnetic tunnel junction elements <NUM> and the metal interconnections <NUM>; and then, the metal interconnections <NUM>/<NUM>/<NUM>/<NUM> fill into the recesses.

By doing this, a magnetic tunnel junction (MTJ) device <NUM> of <FIG> or a magnetic tunnel junction (MTJ) device <NUM> of <FIG> can be carried out by said processing steps. Top views of the magnetic tunnel junction (MTJ) devices <NUM>/<NUM> of the present invention are presented as follows. <FIG> schematically depicts a top view of a magnetic tunnel junction (MTJ) device according to an embodiment of the present invention. This embodiment can not only correspond to a structure having the cross-sectional view of <FIG>, but also correspond to a structure having the cross-sectional view of <FIG>. As shown in <FIG>, the magnetic tunnel junction elements <NUM> are arranged side by side at a first direction X1, and the metal interconnections <NUM> are located between the magnetic tunnel junction elements <NUM>. The contact plug parts <NUM> of the metal interconnections <NUM> have long shapes S1 at a top view, and each of the long shapes S1 has a length L1 at a second direction X2 larger than a width W1 at the first direction X1, wherein the second direction X2 is orthogonal to the first direction X1. Thereby, the contact plug parts <NUM> have oval at the top view. The metal parts <NUM> have rectangular shapes and the magnetic tunnel junction elements <NUM> may have rectangular shapes, oval shapes, circular shapes or etc at the top view, depending upon practical requirements.

In this case, the contact plug parts <NUM> have oval shapes at the top view, the metal parts <NUM> have rectangular shapes at the top view, and the magnetic tunnel junction elements <NUM> have circular shapes at the top view, wherein the whole contact plug parts <NUM> are in the metal parts <NUM> at the top view. Since each of the contact plug parts <NUM> has the length L1 at the second direction X2 larger than the width W1 at the first direction X1, a distance between each of the contact plug parts <NUM> and the adjacent magnetic tunnel junction elements <NUM> can be increased to avoid short circuit. Meanwhile, the surface area of the contact plug parts <NUM> can be preserved to keep low contact resistance.

Each of the contact plug parts <NUM> has an oval shape and each of the metal parts <NUM> has a rectangular shape at the top view individually, to not only increase the distance between each of the contact plug parts <NUM> and the adjacent magnetic tunnel junction elements <NUM> but also maintain the surface area of the contact plug parts <NUM>. In another case that does not form part of the present invention, as shown in <FIG>, the contact plug parts <NUM> and the metal parts <NUM> are both rectangular shapes at the top view, the magnetic tunnel junction elements 150b are square shapes at the top view, and the whole contact plug parts <NUM> are in the metal parts <NUM> at the top view. Since each of the contact plug parts 162b has a length L2 at a second direction X3 larger than a width W1 at a first direction X4, a distance d2 between each of the contact plug parts 162b and the adjacent magnetic tunnel junction elements 150b can be increased to avoid short circuit. Meanwhile, the surface area of the contact plug parts 162b can be preserved to keep low contact resistance.

Preferably, the ratio of the length L2 of each of the contact plug parts 162b and the width W2 of each of the contact plug parts 162b is <NUM>-<NUM>. In an embodiment, as the magnetic tunnel junction elements 150b have square shapes and a length L3 of a side of the square shapes at the top view is <NUM>, the length L2 of each of the contact plug parts 162b is at a range of <NUM>-<NUM> while the width W2 of each of the contact plug parts 162b is <NUM>, but it is not limited thereto. Still preferably, each of the metal parts 164b corresponding to the contact plug parts 162b has a long shape S2 at the top view, and a length L4 of the long shape S2 at the second direction X4 is larger than a width W3 at the first direction X4, for forming each of the contact plug parts 162b and the corresponding metal parts 164b stacked from bottom to top easily. The long shape S2 may be a rectangular shape, an oval shape or others. In a preferred embodiment, the ratio of the length L4 of each of the metal parts 164b and the width W3 of each of the metal parts 164b is <NUM>-<NUM>. In this case, the length L4 of each of the metal parts 164b may be at a range of <NUM>-<NUM> while the width W3 of each of the metal parts 164b is <NUM>, but it is not limited thereto. By doing this, the device applied the present invention can be formed by nowadays processes easily.

In the embodiment of <FIG>, each of the contact plug parts <NUM> and the corresponding metal parts <NUM> have tapered sidewalls broaden smoothly from bottom to top, therefore purposes of the present invention can be achieved by just restricting layouts of the metal interconnections <NUM>. To give an example that does not form part of the present invention, as the top view of this embodiment is the top view of <FIG>, each of the metal interconnections 160b have a long shape S at the top view, and a length L of the long shape S at the second direction X3 is larger than a width W at the first direction X4. The long shape S may be a rectangular shape, an oval shape or others.

Above all, the contact plug parts of the metal interconnections between the magnetic tunnel junction elements have long shapes at the top view. Besides, lengths of the long shapes at a direction orthogonal to a direction that the magnetic tunnel junction elements arranged side by side are larger than widths of the long shapes at the direction the magnetic tunnel junction elements arranged side by side. Thus, the distance between the contact plug parts and the adjacent magnetic tunnel junction elements can be increased to avoid short circuit while the surface area of the contact plug parts can be preserved to keep low contact resistance.

Moreover, an embodiment of a magnetic tunnel junction (MTJ) device not forming part of the present invention is presented as follows. <FIG> schematically depicts a cross-sectional view of a magnetic tunnel junction (MTJ) device according to this embodiment not forming part of the present invention. As shown in <FIG>, the difference between a magnetic tunnel junction (MTJ) device <NUM> and the magnetic tunnel junction (MTJ) device of <FIG> is in the following. The metal interconnection 360a may include a contact plug part 362a and a metal part 364a stacked from bottom to top, and the metal interconnection 360b may include a contact plug part 362b and a metal part 364b stacked from bottom to top. The metal interconnections 360a/360b may be formed by dual damascene processes, and the contact plug parts 362a/362b and the metal parts 364a/364b may have different or common sizes, but it is not restricted thereto. Methods of forming the magnetic tunnel junction (MTJ) device <NUM> of this embodiment are similar to the methods of forming the magnetic tunnel junction (MTJ) device <NUM> of <FIG> and the methods of forming the magnetic tunnel junction (MTJ) device <NUM> of <FIG>, and thus are not described herein.

An embodiment of layouts of the magnetic tunnel junction (MTJ) device <NUM> is presented as follows. <FIG> schematically depicts a top view of a magnetic tunnel junction (MTJ) device according to an embodiment not forming part of the present invention. As shown in FG. <NUM>, the whole contact plug parts 362b overlap the metal parts 364b at a top view, and a minimum distance d3 between an edge E1 of the contact plug parts 362b and an edge E2 of the corresponding metal parts 364b at a first direction X5 is equal to or larger than <NUM>/<NUM> of a length L5 of the corresponding metal parts 362b at the first direction X5. Please refer to <FIG> as well as <FIG>, an edge E3 of the contact plug part 362a is trimmed to an edge E4 of the metal part 364a, and the contact plug part 362b of the metal interconnection 360b is shifted to make the minimum distance d3 between the edge E1 of the contact plug part 362b and the edge E2 of the metal part 364b at the first direction X5 be equal to or larger than <NUM>/<NUM> of the length L5 of the corresponding metal parts 364b at the first direction X5. Therefore, a distance d4 between each of the contact plug parts 362b and the adjacent magnetic tunnel junction elements <NUM> can be increased to avoid short circuit while the surface area of the contact plug parts can be preserved to keep low contact resistance.

Preferably, the contact plug parts 362b and the metal parts 364b are both rectangular shapes at the top view, or the contact plug parts 362b have square shapes at the top view while the metal parts 364b have rectangular shapes at the top view, for forming these structures easily. The magnetic tunnel junction elements <NUM> may have circular shapes at the top view, but it is not restricted thereto. The metal parts 364b and the magnetic tunnel junction elements <NUM> may have rectangular shapes, square shapes, circular shapes, oval shapes, or other shapes at the top view individually. In one case, the length L5 of each of the metal parts 364b may be <NUM> at the first direction X5, and the minimum distance between the edge E1 of each of the contact plug parts 362b and the edge E2 of the corresponding metal parts 364b at the first direction X5 is <NUM>. Preferably, a length L6 of a side of the contact plug parts 362b is <NUM> at the top view, but it is not limited thereto.

To summarize, the present invention provides a magnetic tunnel junction (MTJ) device according to claim <NUM>, which includes two magnetic tunnel junction elements arranged side by side at a first direction, and a metal interconnection disposed between the two magnetic tunnel junction elements. In this way, the distance between the contact plug part and the adjust magnetic tunnel junction elements can be enlarged to avoid short circuit, and the surface area of the contact plug part can also be maintained to keep low contact resistance.

In a preferred embodiment, the ratio of the length of the long shape and the width of the long shape is <NUM>-<NUM>. For instance, the length of the contact plug part is at a range of <NUM>-<NUM> while the width of the contact plug part is <NUM>. The ratio of the length of the corresponding metal part and the width of the corresponding metal part is <NUM>-<NUM>. For instance, a length of the corresponding metal part is at a range of <NUM>-<NUM> while the width of the corresponding metal part is <NUM>.

Claim 1:
A magnetic tunnel junction (MTJ) device (<NUM>, <NUM>), comprising:
two magnetic tunnel junction elements (<NUM>) arranged side by side at a first direction (X1) in a dielectric layer (<NUM>) and connected to first metal lines (112a, 112c); and
a metal interconnection (<NUM>, 160a) disposed between the two magnetic tunnel junction elements (<NUM>) in the dielectric layer (<NUM>) and directly contacting a second metal line (112b, 112d), wherein the metal interconnection (<NUM>, 160a) comprises a contact plug part (<NUM>, 162a) and a metal part (<NUM>, 164a) stacked from bottom to top, the contact plug part (<NUM>, 162a) has a first long shape (S1) at a top view, and the first long shape has a length (L1) at a second direction (X2) larger than a width (W1) at the first direction (X1), wherein the second direction (X2) is orthogonal to the first direction (X1), wherein the metal part (<NUM>, 164a) has a second long shape (S2) at the top view, and the second long shape (S2) has a length (L4) at the second direction larger than a width (W3) at the first direction, and the first long shape (S1) has an oval shape while the second long shape (S2) has a rectangular shape, wherein an extension of a line passing through the width (W1) of the contact plug part (<NUM>, 162a) along the first direction (X1) passes through the two magnetic tunnel junction elements (<NUM>).