201135728 L vV 34175twf.doc/n 六、發明說明： 【發明所屬之技術領域】 本發明是有關於一種磁性隨機存取記憶體，且特別是 有關於一種具垂直磁化量之自旋傳輸力矩磁性隨機存取記 憶體 ° 【先前技術】 磁性隨機存取記憶體(magnetic random access memory， MRAM)之基本架構是由一固定層（pinnecj iayer)、一穿隧 阻障層（barrier layer)、一 自由層（free layer)所組成。 藉由改變自由層之磁矩方向相對於固定層之磁矩方向為平 行或反平行時’磁阻分別為低電阻態與高電阻態來儲存資 訊。 傳統磁性隨機存取記憶體以導線通入電流產生之磁 場執行寫入動作，例如已經量產之Standalone MRAM。對 於磁場翻轉（fleld-switching)的MRAM，其寫入線所產生 之磁場易對鄰近位元產生干擾造成誤寫入，且隨元件尺寸 憂小’所需之翻轉場變大’不利微縮。因此在65nm技術 節點以下之MRAM，使用自旋傳輸力矩（STT，Spin transfer torque)的機制，利用自旋極化電子與局部磁矩之角動量 寸值機制翻轉元件之自由層磁矩方向，以執行寫入動作。 STT寫入電流與元件尺寸成正比，適合微縮，但當元件尺 寸縮小時，自由層中所儲存的磁能（Kuv)也隨之變小， 易受溫度所產生隨機熱擾動場干擾，影響元件之熱穩定 201135728 “ 乂" v v〇9TW 34175tw£doc/n 性。雖然選擇飽合磁化量高的材料或增加自由層厚度可提 高元件之熱穩定性，但如此一來翻轉所需之電流亦隨之增 加。因此降低翻轉電流㈣簡適#的熱穩定性為發展 STT-MRAM最重要的議題。 磁性隨機存取記憶體的依材料特性可區分為水平式 (IMA，inplane magnetization anis〇tropy )與垂直式（pMA， perpendicular magnetization anis〇tr〇py)二種。圖 i 繪示傳 • 統水平式磁性隨機存取記憶體的結構剖面示意圖。參閱圖 1，水平式磁性隨機存取記憶體結構包括一磁性固定層 100,具有固定磁化方向102,不受外部施加的磁場所改 ’艾，其磁化方向當作參考之用。在固定層1〇〇上有一穿隧 絕緣層104。一磁性自由層106在穿隧絕緣層1〇4上。磁 性自由層106具有可以切換的磁化方向1〇8。磁性自由層 106的磁化方肖1〇8可以藉由外部施加磁場或通入電流自 由改變成與磁化方向102平行或是反平行。藉由量取磁性 自由層106與固定層1〇〇之間由於平行或是反平行所產生 磁阻的差異來判定磁性自由層1〇6所儲存的位元資料。 圖2A-2B繪示垂直式MRAm結構剖面示意圖。參閱 圖2A，垂直式MRAM的結構基本上是由磁性固定層11〇、 穿隧絕緣層112與磁性自由層114疊置所構成。磁性固定 層110的磁化方向120是固定方向，且垂直於其水平面。 磁性自由層114的磁化方向122亦可藉由外部磁場或通入 電流自由切換於二個方向，但垂直於水平面。 然而，若就圖1的水平式的MRAM結構，若直接以 34I75twf.doc/n 201135728 元件如圖=代水平磁化材料，而構成垂直式磁性磁阻 C /N、「ZP的，構時’由於許多垂直材料，如C〇/Pt、 i〇ilH d、等多層膜的序化方向為面心立方f.c.c· 此以Mg〇作為穿魏緣層112時，無法在介 面：成局磁阻變化率(MR rati〇)所需之體心立方匕“ (，2)序化方向。較低的磁阻變化率會限制元件之操作速 又:此，需要加入一適當的極化增5金（polarization Γ2 ΓΓΓ!)插人層介於垂直式㈣與MgG魏絕緣層 、曰θΐ/、Mg〇介面形成高磁阻變化率所需之序化方 向以提同垂直式磁性磁阻元件的磁阻變化率。參閱圖 =’另-種垂直式MRAM結構，以圖2A的結構為基礎， “加插入層116、118介於垂直式材料磁性層與MgO的穿 隧絕，層112之間。此插入層116、118 一般為c〇FeB等 具有局極化率（pGlarizatiGn)且可在Mg〇介面形成⑽） 序化方向之材料，這些材料雖然屬於水平式材料，但利用 兩者間的強輕合作用力，垂直式材料可強迫水平式材料插 入層之磁矩立起為垂直磁化方向。 垂直式磁性材料之異向性能量大，因此在尺寸微縮到 十分微小時仍可保有足夠之熱穩定性。例如硬碟碟片所使 用之垂直式磁性材料，其晶粒（grain)大小僅有十數打瓜， 但其熱穩定性係數（KuV/kBT)仍可大於60。因此使用具 垂直磁矩方向材料之垂直式MRAM被認為是尺寸進一^ 微縮時深具潛力的關鍵技術。然而由於垂直磁性材料之阻 尼常數（damping constant) —般來說較水平磁性材料大， 201135728 ς j i77v^09TW 34175twf.doc/n 因此以STT翻轉垂直材料自由層時，其翻轉所需之臨界電 流密度（critical current density，JC)均大於水平式材料。 若能進一步降低翻轉垂直式材料磁之臨界電流密度，將有 助於垂直式MRAM之量產應用。 【發明内容】 本發明提供一種垂直式磁性隨機存取記憶體，可以降 低翻轉自由層磁矩方向所需之臨界電流密度，以降低寫入 電流。 _ 本發明提出一種磁性隨機存取記憶體具有垂直磁矩 方向。磁性隨機存取記憶體包括一第一磁性層，一第二磁 ϋ 層 第一極化增強層（polarization enchancement layer)，一第二極化增強層，一穿隧阻障層，一間隔層及 一自由輔助層（free assisting layer)。第一磁性層與第一 極化增強層組成固定層，有垂直的一第一磁矩方向且有一 第一垂直磁化異向性。第二磁性層與第二極化增強層組成 自由層，有垂直的一第二磁矩方向且有一第二垂直磁化異 向性。第一極化增強層形成於第一磁性層與穿隧阻障層之 間’第二極化增強層形成於第二磁性層與穿隧阻障層之 間，穿隧阻障層形成於該第一極化增強層與該第二極化增 強層之間。間隔層形成於該第一磁性層上。自由輔助層在 該間隔層上’具有一水平磁化異向性，其中該間隔層與該 穿隧阻障層是在該自由層的相對兩側。 為讓本發明之上述特徵和優點能更明顯易懂，下文特 201135728 ιοί 別卿 rw 34175twf.doc/n 舉實施例，並配合所附圖式作詳細說明如下。 【實施方式】 本案提出一種磁性隨機存取記憶體結構，有利於降低 操作電流密度。以下舉一些實施例來描述本發明，但是本 發明不限於所舉的實施例，且實施例之間有可以適當結合。 圖3繪示本發明一實施例，為使用於磁性隨機存取記 憶體元件150之結構剖面示意圖。磁性隨機存取記憶體元 件150可與電晶體（is〇iati〇n transistor)及其它所需之線 路（configurations)(未繪示）形成磁性隨機存取記憶體 之記憶單元（memory cell)。於圖3中，元件150之結構 包含一磁矩方向垂直於膜面之自由層212, 一磁矩方向垂 直於膜面之固定層204，一穿隧阻障層206形成於自由層 212與固定層204之間。自由層212包含一第二磁性層208 以及一第二極化增強層210。第二極化增強層210與穿隧 阻障層206接觸。固定層204包含一第一磁性層2〇〇及一 第一極化增強層202。第一極化增強層202與穿隧阻障層 206接觸。 第一磁性層200擁有一第一垂直磁化異向性，第二磁 性層208擁有一第二垂直磁化異向性。其中第一垂直磁化 異向性大於第二垂直磁化異向性。在—般操作下，固定層 2〇4磁矩方向為垂直膜面，且不受寫人電流影響，自由層 212磁矩方向則隨寫入電流2丨8之極性而形成與固定層2 〇 4 磁矩方向平行或反平行之方向，伽罐齡取記憶體元 201135728 r^i^uu09TW 34175twf.doc/n 件150之電阻態為低或尚，分別記錄邏輯「〇」或邏輯「1」。 又，一間隔層214形成於磁性自由層2〇8上。一自」由 輔助層216形成於自由層m上。也就是間隔層214是形 成於自由輔助層216與自由層212之間。間隔層214與自 由層212之接觸面為自由層212與穿隧阻障層2〇6接觸面 之另一側。自由辅助層216具有一水平磁化異向性。調整 間隔層為適當之厚度，可使自由輔助層216與自由層212 • 之間除靜磁場（static magnetic field)外並無狀艮丫輕合 作用等的其它層間搞合作用力（interkyer exchaiJe coupling) ^自由輔助層216的磁矩方向在水平的方向可 以自由變化。又，基於實際製造的材料特性，自由輔助層 216的磁矩方向於未通入電流時如箭頭所示與自由辅助層 的水平表面可以相夾有容許的一小角度。磁矩方向於通入 電流時則受來自自由層之自旋傳輸力矩影響而不限於在此 角度下旋轉變化。 以下以圖4說明間隔層214與翻轉辅助層216作用機 制。圖4中僅簡單繪示自.由層212，間隔層214與自去翻 轉層216,省略穿隧阻障層206與固定層204。其中箭頭代 表初始磁矩方向，今欲通入一極化電流使圖4中之自由層 212之磁矩方向由繪示之（〇,〇，1)翻轉為（〇,〇，·ι)。本案 使用藉由發明人於論文「Reduction in critical current density for spin torque transfer switching with composite free layer」（Appl. Phys. Letts. 93, 092504 (2008))所使用之模 擬程式，驗證本案提出的結構所達到的效果，由 201135728 r^iyyuuu^rW 34175twf.doc/n201135728 L vV 34175twf.doc/n VI. Description of the Invention: [Technical Field] The present invention relates to a magnetic random access memory, and more particularly to a magnetic transmission randomness of a spin transfer torque having a perpendicular magnetization amount Access memory ° [Prior Art] The basic structure of magnetic random access memory (MRAM) is composed of a pinned layer, a tunnel barrier layer, and a free layer. (free layer) composed. By changing the direction of the magnetic moment of the free layer to be parallel or anti-parallel with respect to the direction of the magnetic moment of the fixed layer, the magnetic resistance is stored in a low resistance state and a high resistance state, respectively. Conventional magnetic random access memories perform write operations on a magnetic field generated by a wire current, such as a Standalone MRAM that has been mass-produced. For a fleur-switching MRAM, the magnetic field generated by the write line tends to cause interference to adjacent bits, causing erroneous writing, and the size of the device is small, and the required flip field becomes large, which is disadvantageously reduced. Therefore, in the MRAM below the 65nm technology node, using the mechanism of spin transfer torque (STT), the angular momentum of the spin-polarized electrons and the local magnetic moment is used to flip the free-layer magnetic moment direction of the component. Perform a write action. The STT write current is proportional to the component size and is suitable for miniaturization. However, when the component size is reduced, the magnetic energy (Kuv) stored in the free layer is also reduced, which is susceptible to random thermal disturbance field generated by temperature, which affects the component. Thermal stability 201135728 “ 乂" vv〇9TW 34175tw£doc/n. Although choosing a material with a high amount of magnetization or increasing the thickness of the free layer can improve the thermal stability of the component, the current required for the flipping is also Therefore, the thermal stability of the inverted current (4) is suitable for the development of STT-MRAM. The material properties of magnetic random access memory can be divided into horizontal (IMA, inplane magnetization anis〇tropy) and Vertical (pMA, perpendicular magnetization anis〇tr〇py). Figure i shows a schematic cross-sectional view of a horizontal magnetic random access memory. Referring to Figure 1, the horizontal magnetic random access memory structure includes A magnetic pinned layer 100 having a fixed magnetization direction 102 is not affected by an externally applied magnetic field, and its magnetization direction is used as a reference. On the pinned layer 1 A tunneling insulating layer 104. A magnetic free layer 106 is on the tunneling insulating layer 1 〇 4. The magnetic free layer 106 has a switchable magnetization direction 1 〇 8. The magnetization of the magnetic free layer 106 can be made by The externally applied magnetic field or the incoming current is freely changed to be parallel or anti-parallel to the magnetization direction 102. The difference between the magnetic resistance of the magnetic free layer 106 and the fixed layer 1 由于 due to parallel or anti-parallel is determined. 2A-2B is a schematic cross-sectional view of a vertical MRAm structure. Referring to FIG. 2A, the structure of the vertical MRAM is basically composed of a magnetic pinned layer 11 and a tunneling insulating layer 112. The magnetization direction 120 of the magnetic pinned layer 110 is fixed and perpendicular to its horizontal plane. The magnetization direction 122 of the magnetic free layer 114 can also be switched to two by an external magnetic field or a current. Direction, but perpendicular to the horizontal plane. However, if the horizontal MRAM structure of Figure 1 is directly magnetized with 34I75twf.doc/n 201135728, the vertical magnetic reluctance C / N, "ZP, structure time" is due to many vertical materials, such as C〇/Pt, i〇ilH d, etc. The ordering direction of the multilayer film is face-centered cubic fcc. When Mg is used as the weft-edge layer 112, it cannot be Interface: Body-centered cubic 所需 required for the rate of change of the magnetoresistance (MR rati〇) (, 2) Sequencing direction. A lower rate of change in magnetoresistance limits the operating speed of the component: this requires the addition of a proper polarization of 52 ΓΓΓ! to insert the layer between the vertical (4) and MgG Wei insulation, 曰θΐ/ The Mg〇 interface forms a sequence direction required for a high magnetoresistance change rate to improve the magnetoresistance change rate of the vertical magnetic reluctance element. Referring to Figure = 'another type of vertical MRAM structure, based on the structure of Figure 2A, "the interposer layers 116, 118 are interposed between the vertical material magnetic layer and the tunneling of MgO, layer 112. This interposer 116 118 is generally a material having a local polarizability (pGlarizatiGn) such as c〇FeB and which can form (10) in the Mg〇 interface. Although these materials are horizontal materials, they utilize strong and light cooperation between the two, The vertical material can force the magnetic moment of the horizontal material insertion layer to rise to the direction of perpendicular magnetization. The vertical magnetic material has a large anisotropy energy, so it can maintain sufficient thermal stability when the size is reduced to a very small size. For example, hard The vertical magnetic material used in the disc has a grain size of only a dozen dozen melons, but its thermal stability coefficient (KuV/kBT) can still be greater than 60. Therefore, the material with a perpendicular magnetic moment direction is used. Vertical MRAM is considered to be a key technology with a potential for size reduction. However, since the damping constant of a perpendicular magnetic material is generally larger than that of a horizontal magnetic material, 201135728 ς j i77v^09TW 34 175twf.doc/n Therefore, when STT flips the vertical material free layer, the critical current density (JC) required for its flipping is greater than that of the horizontal material. If the critical current density of the inverted vertical material magnetic material can be further reduced, SUMMARY OF THE INVENTION The present invention provides a vertical magnetic random access memory that can reduce the critical current density required to reverse the direction of the magnetic moment of the free layer to reduce the write current. The present invention provides a magnetic random access memory having a direction of a perpendicular magnetic moment. The magnetic random access memory includes a first magnetic layer, a second polarization layer, and a polarization enchance layer. a polarization enhancement layer, a tunnel barrier layer, a spacer layer and a free assisting layer. The first magnetic layer and the first polarization enhancement layer form a fixed layer, and a vertical first magnetic moment a direction and a first perpendicular magnetization anisotropy. The second magnetic layer and the second polarization enhancement layer form a free layer having a second magnetic moment direction and a first Vertical magnetization anisotropy. The first polarization enhancement layer is formed between the first magnetic layer and the tunnel barrier layer. The second polarization enhancement layer is formed between the second magnetic layer and the tunnel barrier layer. a barrier layer is formed between the first polarization enhancement layer and the second polarization enhancement layer. A spacer layer is formed on the first magnetic layer. The free auxiliary layer has a horizontal magnetization anisotropy on the spacer layer Wherein the spacer layer and the tunneling barrier layer are on opposite sides of the free layer. To enable the above features and advantages of the present invention to be more apparent, the following is a description of the following: 201135728 ιοί 别卿 rw 34175twf.doc/n The embodiments are described in detail below in conjunction with the drawings. [Embodiment] The present invention proposes a magnetic random access memory structure, which is advantageous for reducing the operating current density. The invention is described below by some examples, but the invention is not limited to the examples, and the embodiments may be combined as appropriate. 3 is a cross-sectional view showing the structure of a magnetic random access memory device 150 according to an embodiment of the present invention. The magnetic random access memory device 150 can form a memory cell of the magnetic random access memory with a transistor and other required configurations (not shown). In FIG. 3, the structure of the component 150 includes a free layer 212 whose magnetic moment direction is perpendicular to the film surface, a magnetic moment direction perpendicular to the fixed layer 204 of the film surface, and a tunneling barrier layer 206 formed on the free layer 212 and fixed. Between layers 204. The free layer 212 includes a second magnetic layer 208 and a second polarization enhancing layer 210. The second polarization enhancing layer 210 is in contact with the tunneling barrier layer 206. The pinned layer 204 includes a first magnetic layer 2A and a first polarization enhancing layer 202. The first polarization enhancing layer 202 is in contact with the tunneling barrier layer 206. The first magnetic layer 200 has a first perpendicular magnetization anisotropy and the second magnetic layer 208 has a second perpendicular magnetization anisotropy. Wherein the first perpendicular magnetization anisotropy is greater than the second perpendicular magnetization anisotropy. Under normal operation, the direction of the magnetic layer of the fixed layer 2〇4 is a vertical film surface, and is not affected by the write current. The direction of the magnetic moment of the free layer 212 is formed with the polarity of the write current 2丨8 and the fixed layer 2 4 The direction of the magnetic moment is parallel or anti-parallel. The gamma age is taken as the memory element 201135728 r^i^uu09TW 34175twf.doc/n 150 The resistance state is low or not, and the logical "〇" or logic "1" is recorded respectively. . Further, a spacer layer 214 is formed on the magnetic free layer 2〇8. The first self is formed on the free layer m by the auxiliary layer 216. That is, the spacer layer 214 is formed between the free auxiliary layer 216 and the free layer 212. The contact surface of the spacer layer 214 and the free layer 212 is the other side of the contact surface of the free layer 212 and the tunnel barrier layer 2〇6. The free auxiliary layer 216 has a horizontal magnetization anisotropy. Adjusting the spacer layer to a suitable thickness allows the free layer between the free auxiliary layer 216 and the free layer 212 to be separated from the static magnetic field (interkyer exchaiJe coupling) The direction of the magnetic moment of the free auxiliary layer 216 can be freely changed in the horizontal direction. Further, based on the material properties actually produced, the direction of the magnetic moment of the free auxiliary layer 216 may be a small angle allowed with the horizontal surface of the free auxiliary layer as indicated by the arrow when the current is not supplied. The direction of the magnetic moment is affected by the spin transmission torque from the free layer when the current is applied, and is not limited to the rotational change at this angle. The action of the spacer layer 214 and the flip assist layer 216 will be described below with reference to FIG. In Fig. 4, only the layer 212, the spacer layer 214 and the self-turning layer 216 are simply illustrated, and the tunnel barrier layer 206 and the pinned layer 204 are omitted. Wherein the arrow represents the direction of the initial magnetic moment, and today a polarization current is required to cause the direction of the magnetic moment of the free layer 212 in Fig. 4 to be inverted from (绘, 〇, 1) to (〇, 〇, · ι). In this case, the inventor used the simulation program used in the paper "Reduction in critical current density for spin torque transfer switching with composite free layer" (Appl. Phys. Letts. 93, 092504 (2008)) to verify the structure proposed in this case. The effect achieved by 201135728 r^iyyuuu^rW 34175twf.doc/n
Landau-Lifshitz-Gilbert (LLG)方程式： (1) ^· = -γτηχ(κ^+Κτ)+αηιχ~ + τ 〇t dt 其中/¾為磁性層磁矩單位向量（reduced magnetization )，y 為磁旋比常數（gyromagnetic constant)，為包含單軸 異向性場（uniaxial anisotropy field )，去磁場 (demagnetization field)，磁偶極場（dipole field) ?，層間 父換搞合％ ( interlayer exchange coupling field )之等效場； A為隨機熱擾動場，其機率分布為μ = 0， σ =知❿所<心(1 + α2)之高斯常態分布，其中心為波茲曼常 數’Τ為溫度’V為體積，Ms為飽和磁化量（saturation magnetization)’ Δτ 為熱擾動之時間間隔（perturbation time interval) ° 其中自旋傳輸力矩（spin transfer torque) f可 (2) ，.^ τ ~T~T7~rwx wx p 2eMsd y 其中e為電子電何（eiectr〇n charge )，j為電流密度（current density ) ’ η為自旋傳輸力矩之效率（Spin torque efficiency ) ’ a 為約化蒲朗克常數（reduced pianck conStant) ’ d為薄膜厚度（film thickness)，》為極化電 流之單位向量。 201135728 rji^uU〇9TW 34175twf.doc/n 自旋傳輸力矩之大小與A與6相對的夾角有關。當其 夾角正為〇或冗時，根據(2)式計算所得的力矩為〇。 模擬中首先給定一電流密度為J。之極化電流，模擬僅 有單一自由層212,而無自由輔助層216存在時，自由層 磁矩進動（precession)的情形。結果發現在此一電流密度 Λ下，自由層212之磁矩並無法於所给定之電流脈衝 (current pulse)長度（10ns)下成功翻轉，如圖5所示，Landau-Lifshitz-Gilbert (LLG) equation: (1) ^· = -γτηχ(κ^+Κτ)+αηιχ~ + τ 〇t dt where /3⁄4 is the magnetic layer unit vector (reduced magnetization), y is magnetic The gyromagnetic constant is a uniaxial anisotropy field, a demagnetization field, a dipole field, and an interlayer exchange coupling field. Equivalent field of A; A is a random thermal perturbation field, the probability distribution is μ = 0, σ = knowing the position of the Gaussian normal distribution of the heart (1 + α2), the center of which is the Boltzmann constant 'Τ is the temperature 'V is the volume, Ms is the saturation magnetization' Δτ is the perturbation time interval ° where the spin transfer torque f can be (2) , .^ τ ~T~ T7~rwx wx p 2eMsd y where e is the electron ecectr〇n charge, j is the current density ' η is the spin torque efficiency ' a is the approximated Planck Constant (reduced pianck conStant) ' d is the film thickness," is the unit vector of the polarized current. 201135728 rji^uU〇9TW 34175twf.doc/n The magnitude of the spin transmission torque is related to the angle between A and 6. When the angle is positive or redundant, the calculated torque according to equation (2) is 〇. A current density of J is first given in the simulation. The polarization current simulates the case where there is only a single free layer 212, and when the free auxiliary layer 216 is absent, the free layer magnetic moment is precession. It was found that at this current density ,, the magnetic moment of the free layer 212 cannot be successfully flipped under the given current pulse length (10 ns), as shown in Fig. 5.
磁矩方向雖因極化電流所提供之自旋傳輸力矩而偏離z 軸，但在電流關掉後即因其畚直異向性而回到(〇,〇，1)之平 衡方向。然模擬中若加入一自由輔助層216，並使一間隔 層214於自由層212與自由輔助層216之間使兩者間除靜 磁％外無其它層間搞合作用力時，則同樣之電流密度7 下’即可成功將自由層212之磁矩方向由⑴灿翻^為。 (0,0，-1) ’如圖6所示。顯示自由輔助層216降低了自由芦 212翻轉所需之臨界電流密度。要注意的是，自由^ 216之磁矩方向在無電流時’為靜磁場與本身去磁場之^ 衡位置’在通入電流時，則因磁矩與電流之交互作 = 生自由進動（precession)。模擬結果 (AFM ^ antiferromagnetic layer) ,鐵磁層 W之磁矩方向岐時，則無法達到所欲降低翻轉^層 W Xct LU、Ru、pd、pd、AiAlthough the direction of the magnetic moment deviates from the z-axis due to the spin transmission torque provided by the polarization current, it returns to the equilibrium direction of (〇, 〇, 1) due to its straight anisotropy after the current is turned off. However, if a free auxiliary layer 216 is added in the simulation, and a spacer layer 214 is used between the free layer 212 and the free auxiliary layer 216 to eliminate the magnetostatic % therebetween, the same current density is obtained. 7 'Next' can successfully turn the direction of the magnetic moment of the free layer 212 from (1). (0,0,-1) ' is shown in Fig. 6. The display of the free auxiliary layer 216 reduces the critical current density required for the free reed 212 to flip. It should be noted that the direction of the magnetic moment of the free ^ 216 is 'the position of the static magnetic field and the self-de-magnetic field when there is no current'. When the current is applied, the interaction between the magnetic moment and the current is freely precessive ( Precession). When the magnetic resonance direction of the ferromagnetic layer W is 模拟, the desired flipping layer W Xct LU, Ru, pd, pd, Ai cannot be achieved.
Au、Ag或含上述金屬之組合或其合金，並厚产 20人，使自由層與自由輔助層之間之層間交換^作 201135728 r ^ i yywvy fW 34175twf.d〇c/n (interlayer exchange coupling)微弱可忽略者，例如交換 耦合常數J (exchange coupling constant)之絕對值小於 0.001mJ/m2，但是實際設計的範圍也可以依所要達到的^ 弱程度而變化，以產生前述自由輔助層的輔助翻轉作用。 合適之間隔層214的一個實施例例如為50 A之Cu。自由 輔助層216例如含Co、Fe、Ni之金屬或合金，如NiFe、Au, Ag or a combination of the above metals or alloys thereof, and a thickness of 20 persons, so that the interlayer exchange between the free layer and the free auxiliary layer is made 2011L. The weakly negligible, for example, the absolute value of the exchange coupling constant J is less than 0.001 mJ/m2, but the actual design range can also vary depending on the degree of weakness to be achieved to produce the aforementioned auxiliary auxiliary layer. Flip effect. One embodiment of a suitable spacer layer 214 is, for example, 50 A of Cu. The free auxiliary layer 216 is, for example, a metal or alloy containing Co, Fe, Ni, such as NiFe,
CoFeB、CoFe、Co、Ni、Fe等，其厚度小於50 A。合適 之自由輔助層216例如20 A之NiFe。 ^ 本案可以於使用具垂直異向性自由層之自旋傳輪力 矩磁性隨機取記憶體元件中，旨提供一具水平異向性之磁 性層，以輔助元件中之垂直異向性自由層進行翻轉，降低 翻轉所需之臨界電流m水平異向性之磁性層與 垂直異向性自由層插人—間隔層，使兩者間僅有微弱或^ 有輕合作力’使树翻制冑種界電雜低但不影響 元件之熱穩定性或元件之磁阻。 又於一實施方式，磁性自由層208的垂直磁化異向 ===小於磁性固定層200的垂直磁化異向性。又或是於 一實施方式，其自由層212的厚度是小於固定層204的厚 度，其代表磁性自由層208比磁性固定層200薄，因此在 ==磁性自由層細時，其操作電流不會翻轉磁性固定層 ^以下描述圖3中的固定層204與自由層212的進一步 詳細結構。圖8繪示本發明一實施例，磁性隨機存取記憶 體結構的剖面示意圖。參關8，其結構與圖3相似，而 12 201135728 P51990009TW 34175twf.doc/n 固定層204與自由層212的較詳細結構。 磁性隨機存取記憶體元件150的結構中，固定層204 的磁性固定層200例如是PMA參考層。第一極化增強層 202例如是磁性層狀多層膜。第二極化增強層21〇例如也 是磁性層狀多層膜。磁性自由層208例如是PMA自由層。 第一極化增強層202的層狀多層膜結構例如是由鐵磁 與非磁交錯疊置的層狀多層膜，接觸設置在磁性固定層 • 200上，其磁化方向會耦合成一致。穿隧阻障層206接觸 設置於第一極化增強層202上。第二極化增強層210的層 狀多層膜接觸設置在穿隧阻障層206上，其磁化方向與 磁性自由層208的磁化方向耦合成一致。磁性自由層208 是PMA自由層，接觸設置於層狀多層膜結構的第二極化 增強層210上，有一第二磁化方向垂直於磁性自由層，可 以被切換成與第一磁化方向平形或反平行。 在圖8的一實施例中’二個極化增強層2〇2、21〇的 _ 磁性層狀多層膜結構當作插入層，其中穿隨阻障層206例 如是MgO的水年材料。對於單一個磁性層狀多層膜結構， 以第一極化增強層202為例，其例如是由鐵磁與非磁交錯 疊置的層狀多層膜。圖9-10繪示本發明一實施例，極化 增強層的結構示意圖。 參閱圖9，對於磁性層狀多層膜的結構，在其最外層 的兩層是鐵磁層（FM)202a、202c，而在這兩層的鐵磁層 202a、202c之間，取決於疊層數量以鐵磁材料與非磁材料 交錯疊置。對於以三層的磁性層狀多層膜的結構而言，在 13 201135728 34175twf.doc/n 兩層的鐵磁層廳、耻之㈣有細 就較佳性能而言，與穿驗障層寫接:鐵磁声 2〇2a的材料仍以CoFeB的材料為主，盆厚如曰 埃的範圍，其中較佳的是1〇_15 圍二丨在5-20 的材料例如是Ta、RU、Cr、A1、M的二圍。非磁性膜薦 m Mg、Cu、Ti 成 Pt。非成 性膜雇的厚度例如是在⑽埃的範圍/ 0.5-3埃的範圍。與磁性固定層2 八平住的疋CoFeB, CoFe, Co, Ni, Fe, etc., having a thickness of less than 50 A. A suitable free auxiliary layer 216 is, for example, 20 A of NiFe. ^ This case can be used in a magnetic random random access memory element with a vertical anisotropic free layer to provide a horizontally anisotropic magnetic layer to assist the vertical anisotropic free layer in the component. Flip, reduce the critical current required for flipping m. The horizontally anisotropic magnetic layer and the vertical anisotropic free layer are inserted into the spacer layer, so that there is only weak or ^ light cooperation between the two. The boundary is low but does not affect the thermal stability of the component or the magnetic resistance of the component. In still another embodiment, the perpendicular magnetization anisotropy of the magnetic free layer 208 === is smaller than the perpendicular magnetization anisotropy of the magnetic pinned layer 200. Or in an embodiment, the thickness of the free layer 212 is smaller than the thickness of the fixed layer 204, which means that the magnetic free layer 208 is thinner than the magnetic fixed layer 200, so when the == magnetic free layer is thin, the operating current is not Flipping the Magnetic Fixing Layer A further detailed structure of the fixed layer 204 and the free layer 212 in FIG. 3 will be described below. FIG. 8 is a cross-sectional view showing the structure of a magnetic random access memory according to an embodiment of the present invention. Reference 8, the structure of which is similar to that of Fig. 3, and 12 201135728 P51990009TW 34175twf.doc/n The more detailed structure of the fixed layer 204 and the free layer 212. In the structure of the magnetic random access memory element 150, the magnetic pinned layer 200 of the pinned layer 204 is, for example, a PMA reference layer. The first polarization enhancing layer 202 is, for example, a magnetic layered multilayer film. The second polarization enhancing layer 21 is, for example, also a magnetic layered multilayer film. The magnetic free layer 208 is, for example, a PMA free layer. The layered multilayer film structure of the first polarization enhancing layer 202 is, for example, a layered multilayer film in which ferromagnetic and non-magnetic interleaving are superposed, and the contact is disposed on the magnetic pinned layer 200, and the magnetization directions thereof are coupled to be uniform. The tunneling barrier layer 206 is placed in contact with the first polarization enhancing layer 202. The layered multilayer film contact of the second polarization enhancing layer 210 is disposed on the tunneling barrier layer 206, and its magnetization direction is coupled with the magnetization direction of the magnetic free layer 208. The magnetic free layer 208 is a PMA free layer which is disposed on the second polarization enhancing layer 210 of the layered multilayer film structure, and has a second magnetization direction perpendicular to the magnetic free layer, which can be switched to be flat or inverted with the first magnetization direction. parallel. In an embodiment of Fig. 8, the magnetic layered multilayer film structure of the two polarization enhancing layers 2?2, 21? is regarded as an interposer, wherein the barrier layer 206 is, for example, a water year material of MgO. For a single magnetic layered multilayer film structure, the first polarization enhancing layer 202 is exemplified, for example, a layered multilayer film in which ferromagnetic and non-magnetic interleaving are stacked. 9-10 are schematic diagrams showing the structure of a polarization enhancement layer according to an embodiment of the invention. Referring to Figure 9, for the structure of the magnetic layered multilayer film, the two layers on the outermost layer are ferromagnetic layers (FM) 202a, 202c, and between the two layers of ferromagnetic layers 202a, 202c, depending on the lamination The number is interleaved with ferromagnetic material and non-magnetic material. For the structure of the three-layer magnetic layered multilayer film, in the 13 201135728 34175twf.doc/n two-layer ferromagnetic layer hall, shame (four) has finer and better performance, and writes with the inspection barrier layer The material of the ferromagnetic sound 2〇2a is still mainly composed of CoFeB, and the thickness of the pot is as large as the range of 曰 ,. Among them, 1〇_15 is preferred. The material of the bismuth at 5-20 is, for example, Ta, RU, Cr. , A1, M's measurements. The non-magnetic film recommends m Mg, Cu, and Ti to form Pt. The thickness of the non-synthetic film employed is, for example, in the range of (10) angstroms / 0.5-3 angstroms.疋 with the magnetic fixed layer 2
β ^ ^ t 疋層200接觸的鐵磁層202c的 材枓例如疋含c。的鐵磁材料，其更例如是c。、c〇Fe、 ⑽犯的材料，然而鐵磁層202c的材料也可以其他相同效 果的鐵磁材料，例如Fe、Ni、或NiFe。_層施c的厚 度例如是1-6埃，其更例如是3_5埃。 至於第二極化增強層21〇的層狀多層膜結構，立也是 如圖9的結構，但是鐵磁層202c與磁性自由層2〇8接觸， 鐵磁層206a與穿隧阻障層206接觸。也就是說，二 增強層2〇2、21〇的層狀多層膜結構例如是對稱^隨 層 206。The material of the ferromagnetic layer 202c that the β ^ ^ t layer 200 contacts, for example, contains c. A ferromagnetic material, which is more, for example, c. , c〇Fe, (10) materials, however, the material of the ferromagnetic layer 202c may also be other ferromagnetic materials of the same effect, such as Fe, Ni, or NiFe. The thickness of the layer c is, for example, 1-6 angstroms, which is more, for example, 3 _5 angstroms. As for the layered multilayer film structure of the second polarization enhancing layer 21A, the structure is also as shown in FIG. 9, but the ferromagnetic layer 202c is in contact with the magnetic free layer 2〇8, and the ferromagnetic layer 206a is in contact with the tunneling barrier layer 206. . That is to say, the layered multilayer film structure of the two reinforcing layers 2 〇 2, 21 例如 is, for example, a symmetrical layer 206.
又’磁性層狀多層膜層數不限於三層結構，而可以更 多。參閱圖10，其磁性層狀多層膜例如是五層的結構，由 二層鐵磁層202a、202c、202e與二層非磁性膜2〇2b、202d 交錯疊置所構成。其中，鐵磁層202a與穿隧阻障層2〇6 接觸’鐵磁層202e與磁性固定層200接觸。 雖然本發明已以實施例揭露如上，然其並非用以限定 本發明’任何所屬技術領域中具有通常知識者，在不脫離 本發明之精神和範圍内，當可作些許之更動與潤韩，故本 14 201135728 ^5iyyuu09TW 34175twf.doc/n 發明之保護麵當視後社㈣專利範圍所界定者為準。 【圖式簡單說明】 ，1繪稍統水平式雜_錄記㈣的結構剖面 示意圖。 圖2A_2B繪示垂直式MRAM結構剖面示意圖。 圖3繪示本發明-實施例，性隨機存取記憶體結構的 剖面示意圖。 圖4綠不本發明-實施例，圖3的結構就操作機制可 以間化成翻轉輔助層對自由層的翻轉效果的探討。 圖5繪不依據本發明一實施例，沒有翻轉輔助層時， 自由層的磁化向量的翻轉狀態。 圖6繪示依據本發明一實施例，有翻轉辅助層但作用 強度為零時’自由層的磁化向量的翻轉狀態。 圖7繪示依據本發明一實施例，有翻轉輔助層但作用 強度強時，自由層的磁化向量的翻轉狀態。 圖8繪示本發明一實施例’性隨機存取記憶體結構的 剖面示意圖。 圖9-10繪示本發明一實施例，極化增強層的結構示 意圖。 【主要元件符號說明】 100 :磁性固定層 102 :磁矩方向 15 rw 34175twf.doc/n 201135728 z j \.-7y\j\j\jy 104:穿隧絕緣層 106 :磁性自由層 108 :磁矩方向 110 :磁性固定層 112:穿隧絕緣層 114 :磁性自由層 116、118 :插入層 120、122 :磁矩方向 150:磁性隨機存取記憶體元件 200:第一磁性層 202:第一極化增強層 202a、202c、202e :鐵磁層 202b、202d :非磁性膜 204:固定層 206:穿隧阻障層 208:第二磁性層 210 :第二極化增強層 212 :自由層 214:間隔層 216 :自由辅助層 218 :施加電流 16Further, the number of layers of the magnetic layered multilayer film is not limited to a three-layer structure, but may be more. Referring to Fig. 10, the magnetic layered multilayer film is, for example, a five-layer structure in which two layers of ferromagnetic layers 202a, 202c, and 202e are alternately stacked with two layers of non-magnetic films 2?2b and 202d. The ferromagnetic layer 202a is in contact with the tunneling barrier layer 2〇6. The ferromagnetic layer 202e is in contact with the magnetic pinned layer 200. The present invention has been disclosed in the above embodiments, and it is not intended to limit the invention to those skilled in the art, and it is possible to make some changes and invigoration without departing from the spirit and scope of the invention. Therefore, this article 14 201135728 ^5iyyuu09TW 34175twf.doc / n The protective surface of the invention is subject to the definition of patent scope (4). [Simple description of the diagram], 1 is a schematic diagram of the structural section of the horizontally-type horizontal _record (4). 2A-2B are schematic cross-sectional views showing a vertical MRAM structure. 3 is a cross-sectional view showing the structure of a random access memory of the present invention. Fig. 4 is not the present invention - the embodiment, the structure of Fig. 3 can be interposed into a flipping auxiliary layer to the effect of the flipping effect of the free layer. Figure 5 depicts the inverted state of the magnetization vector of the free layer when the auxiliary layer is not flipped, in accordance with an embodiment of the present invention. Figure 6 is a diagram showing the inverted state of the magnetization vector of the free layer when the auxiliary layer is flipped but the applied intensity is zero, in accordance with an embodiment of the present invention. FIG. 7 illustrates a flipped state of a magnetization vector of a free layer when there is a flipping auxiliary layer but the intensity is strong, according to an embodiment of the invention. FIG. 8 is a cross-sectional view showing the structure of a random access memory according to an embodiment of the present invention. 9-10 illustrate the structure of a polarization enhancing layer in accordance with an embodiment of the present invention. [Main component symbol description] 100: Magnetic pinned layer 102: Magnetic moment direction 15 rw 34175twf.doc/n 201135728 zj \.-7y\j\j\jy 104: Tunneling insulating layer 106: Magnetic free layer 108: Magnetic moment Direction 110: magnetic pinned layer 112: tunneling insulating layer 114: magnetic free layer 116, 118: interposer layer 120, 122: magnetic moment direction 150: magnetic random access memory element 200: first magnetic layer 202: first pole Enhancement layer 202a, 202c, 202e: ferromagnetic layer 202b, 202d: non-magnetic film 204: fixed layer 206: tunneling barrier layer 208: second magnetic layer 210: second polarization enhancing layer 212: free layer 214: Spacer layer 216: free auxiliary layer 218: current application 16