A method for fabricating tunneling magnetoresistance and magnetic random access memory.

Abstract

This invention discloses a method for preparing a tunneling magnetoresistive (TMG) resistor, comprising: constructing a bottom hierarchical structure of the TMG resistor; controlling the particle adsorption time in the chamber according to the required RA value; constructing a non-magnetic layer above the bottom hierarchical structure in the chamber after adsorption is completed; and constructing a top hierarchical structure above the non-magnetic layer. The method optimizes the particle purity and vacuum level in the chamber by pre-cleaning the chamber with particles before constructing the non-magnetic layer, and achieves precise control over the durability and data reading function of the TMG resistor structure without negatively impacting it by matching the adsorption time with the RA value of the TMG resistor.

Description

Technical Field

[0001] This invention relates to the field of magnetic electronic devices, and particularly to the field of tunneling magnetoresistance. Background Technology

[0002] With the continuous upgrading of the hardware and software performance of electronic devices, the market has placed higher demands on the storage density and speed of memory. Currently, electronic devices using 28nm and below process technologies commonly employ magnetic random access memory (MRAM). The key to MRAM fabrication lies in the resistance control of its core structure, the magnetic tunnel junction (MTJ). Existing methods for controlling the resistance of the MMT typically involve changing the thickness of its MgO (magnesium oxide) tunneling barrier layer or altering the size of the MMT during the etching process. However, changing the thickness of the MgO tunneling barrier layer risks weakening its durability during read / write operations, while changing the size of the MMT during the etching process can negatively impact data retention.

[0003] Therefore, it is particularly important to find a way to precisely control the RA (Resistance Area) value without changing the persistence of the MgO tunneling barrier layer during the read and write process and weakening the data retention function of the magnetic random access memory. Summary of the Invention

[0004] This invention provides a novel method for preparing a tunneling magnetoresistive junction, which can accurately adjust its resistance value without compromising the durability and data retention capability of the magnetic tunnel junction.

[0005] To address the above problems, the first aspect of this invention proposes a novel method for preparing a tunneling resistor, comprising the steps of:

[0006] S1: Construct the bottom-level structure of the tunneling magnetoresistance;

[0007] S2: Control the particle adsorption time in the chamber according to the required RA value;

[0008] S3: In the chamber where adsorption has been completed, construct a non-magnetic layer above the bottom hierarchical structure;

[0009] S4: Construct a top-level structure on top of the non-magnetic layer.

[0010] In some embodiments, the tunneling magnetoresistance includes a top-pinned structure or a bottom-pinned structure.

[0011] In some embodiments, the method further includes removing the formal target material from the chamber before controlling the chamber particle adsorption time.

[0012] In some embodiments, the method involves pre-sputtering the cavity interior with a target material identical to the non-magnetic layer.

[0013] In some embodiments, the method involves first inserting a dummy wafer for pre-sputtering.

[0014] In some embodiments, the method involves constructing the layers using a sputtering process.

[0015] In some embodiments, the method further includes filling the chamber with a low-pressure inert gas during chamber particle adsorption.

[0016] In some embodiments, when the thickness of the non-magnetic layer obtained is the same, the sputtering time and the RA value of the tunneling magnetoresistance have a continuous correspondence.

[0017] A second aspect of this application also provides a method for fabricating a magnetic random access memory, wherein the tunneling magnetoresistance of the magnetic tunnel junction in the magnetic random access memory is prepared by means of the method described in any of the above embodiments.

[0018] In some embodiments, the chamber baffle is in an open state during the S1 operation, allowing it to adsorb particles throughout the chamber.

[0019] In some embodiments, the Ta adsorption time and system RA value in the S1 operation process exhibit a continuous and one-to-one matching relationship.

[0020] In some embodiments, the target material used in the pre-sputtering process of the S1 operation is consistent with the non-magnetic layer material (MgO, but not limited to MgO).

[0021] The embodiments of the present invention provide a method for preparing a tunneling magnetoresistance. Before building the non-magnetic layer, ion adsorption cleaning is performed inside the chamber to optimize the particle purity and vacuum level in the chamber environment. Furthermore, by matching the Ta adsorption time with the RA value of the tunneling magnetoresistance, precise control is achieved to ensure that the durability of the tunneling resistor structure and the data reading function are not negatively affected. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application.

[0023] Figure 1 This is a tunneling magnetoresistance structure according to an embodiment of the present invention;

[0024] Figure 2 This is a flowchart illustrating the implementation of a top-pinning structure according to an embodiment of the present invention;

[0025] Figure 3 This is a flowchart illustrating the implementation of a bottom stud structure according to an embodiment of the present invention;

[0026] Figure 4 This is a graph showing the relationship between Ta adsorption time and RA according to an embodiment of the present invention.

[0027] Figure 5 This is a graph showing the relationship between different MgO pre-sputtering times and RA according to an embodiment of the present invention. Detailed Implementation

[0028] To make the inventive objectives, features, and advantages of this application more apparent and understandable, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0029] Those skilled in the art will understand that the terms "first," "second," etc., in this application are only used to distinguish different devices, modules, or parameters, and do not represent any specific technical meaning, nor do they indicate any necessary logical order between them.

[0030] like Figure 1 As shown, tunneling magnetoresistive structures mainly fall into two categories: bottom-pinned structures and top-pinned structures. The bottom-pinned structure, from bottom to top, consists of a substrate layer, seed layer, pinned layer, antiferromagnetic coupling layer, fixed layer, non-magnetic layer, free layer, and capping layer. The top-pinned structure, also from bottom to top, consists of a substrate layer, seed layer, free layer, non-magnetic layer, fixed layer, antiferromagnetic coupling layer, pinned layer, and capping layer. In MRAM devices, the most important parameters are magnetoresistivity (MR) and resistive area (RA). In practical applications, it is generally desirable to maintain a large MR value (greater than 100%) and to have precisely controllable RA to meet different application requirements. In the prior art, the material, thickness and process of the non-magnetic layer directly determine the RA value in the MTJ. In some known structures, when the non-magnetic layer material is MgO, the thickness of the non-magnetic layer has an exponential relationship with RA. However, as mentioned in the background section, changing the MgO thickness will change the durability of the MgO tunneling barrier layer during the read and write process to a certain extent, which is not an ideal way to control the RA value.

[0031] In one embodiment of this application, in order to achieve precise control of the RA value, the concentration of chamber particles (such as tantalum Ta) is controlled by controlling the adsorption time of the chamber particles before constructing the non-magnetic layer. This achieves control over the vacuum level and, consequently, control over the sputtering quality of the non-magnetic layer film. As a result, the RA value of the system tunneling magnetoresistance can be precisely controlled (i.e., the final RA value shows a correspondence with the adsorption time). Thus, without changing the MgO tunneling barrier layer or the MTJ size, the RA value can be freely and precisely controlled as needed to obtain an MTJ structure with idealized performance.

[0032] In one embodiment of this application, a method for preparing a tunneling resistor is provided, comprising the steps of:

[0033] Construct the bottom-level structure of the tunneling magnetoresistance;

[0034] Control the particle adsorption time in the chamber according to the required RA value;

[0035] In the chamber where adsorption is complete, a non-magnetic layer is constructed above the bottom hierarchical structure;

[0036] A top-level structure is constructed on top of the non-magnetic layer.

[0037] Depending on the type of tunneling magnetoresistance, the bottom-level structure and the top-level structure differ to some extent. A typical structure can be found in [reference needed]. Figure 1 Examples of midsole pinning and top pinning structures. The technical solution of this application mainly involves precisely controlling the adsorption time of chamber particles according to the correspondence between the RA value and the adsorption time of chamber particles before constructing the non-magnetic layer, thereby preparing a tunneling magnetoresistance with a precisely controllable RA value.

[0038] In a preferred embodiment of this application, the relationship between Ta adsorption time and RA value is as follows: Figure 4 As shown in the figure, RA increases monotonically with increasing Ta adsorption time until saturation; specifically, there is a clear and continuous correlation between Ta adsorption time and RA value, with the RA value reaching a maximum of 2.0*10. 4 Ωμm 2 This is because while Ta adsorbs residual particles in the adsorption chamber, it also adsorbs itself onto the surface of the MgO target, essentially doping MgO with Ta, thus causing a change in RA. From Figure 4 It can also be seen that the preparation method of this application has almost no effect on the MR (it is kept relatively stably above 120%). Therefore, the technical solution of this application can obtain an ideal MR value and an RA value prepared on demand while maintaining the thickness of the non-magnetic layer, thus ensuring the stability of MTJ.

[0039] Preferably, such as Figure 2 As shown, in one embodiment of this application, taking a top-pinned structure as an example, the method for preparing the tunneling resistor specifically includes the following steps:

[0040] S201, the seed layer and free layer of the tunneling resistor are sequentially constructed on the substrate.

[0041] The growth and construction of the seed layer and free layer are typically achieved using the relatively mature sputtering process. Sputtering is a process that uses particles (particles or neutral atoms / molecules) of a certain energy to bombard a solid surface, causing atoms or molecules near the solid surface to gain sufficient energy and eventually escape from the solid surface. Sputtering can only be performed under certain vacuum conditions. While sputtering is the preferred method for the growth and construction of the seed layer and free layer, it is not a limiting factor; other methods are also applicable. The materials used for the seed layer and free layer have been extensively studied in existing technologies. For example, tantalum (Ta) is commonly used for the seed layer, while magnetic composite materials are generally used for the free layer. This application does not limit the specific materials used for each layer in its embodiments.

[0042] Optional seed layer and free layer sputtering processes include, but are not limited to, two-stage sputtering, three-stage sputtering or four-stage sputtering, magnetron sputtering, target sputtering, radio frequency sputtering, bias sputtering, asymmetric AC radio frequency sputtering, ion beam sputtering and reactive sputtering.

[0043] S202, Clean the chamber. This step mainly involves removing the target material from the chamber. The target material is usually the elemental material from which the non-magnetic layer to be constructed is formed. The purpose of cleaning the chamber is to prevent sputtering particles from contaminating the target material during the adsorption process, thereby ensuring that the sputtering quality of the non-magnetic layer film can be effectively controlled.

[0044] Optionally, the formal target material is composed of MgO.

[0045] Optionally, the formal target material can be manually picked up and removed from the chamber.

[0046] Optionally, the formal target material can be automatically removed from the chamber by a dedicated pickup device.

[0047] Optionally, the formal target material may not be added before building the non-magnetic layer; it can be added after the chamber particles have been adsorbed.

[0048] S203 controls the adsorption time of particles (Ta adsorption) in the chamber according to the required RA value.

[0049] In the embodiments of this application, the relationship between Ta adsorption time and RA value is as follows: Figure 4As shown, based on the one-to-one correspondence between the two, the corresponding Ta adsorption time can be calculated according to the required RA value, enabling on-demand device fabrication. The cavity particle adsorption process employs magnetron sputtering, a type of physical vapor deposition. General sputtering methods can be used to prepare various materials such as metals, semiconductors, and insulators, and have advantages such as simple equipment, easy control, large coating area, and strong adhesion. Here, the cavity particle adsorption preferably utilizes the sputtering deposition process within magnetron sputtering. Sputtering deposition involves bombarding a target surface with energetic particles in a vacuum (the target material is Ta, but not limited to Ta; the particles' adhesion after bombardment is sufficient to adsorb environmental particles), causing the ejected particles to deposit on the substrate. Typically, low-pressure inert gas glow discharge is used to generate incident ions. Since the sputtered atoms are ejected after exchanging energy with positive ions with energies of tens of electron volts, the high energy of the sputtered atoms is beneficial for improving the diffusion ability of atoms during deposition, increasing the density of the deposited structure, and resulting in strong adhesion between the fabricated film and the substrate.

[0050] Optionally, before Ta adsorption, the partitions between the chambers can be opened to connect the chambers and ensure that the adsorption and cleaning effect is fully transferred inside the chambers.

[0051] Optionally, during Ta adsorption, the adsorption methods that can be selected include, but are not limited to, two-stage sputtering, three-stage or four-stage sputtering, magnetron sputtering, target sputtering, radio frequency sputtering, bias sputtering, asymmetric AC radio frequency sputtering, ion beam sputtering, and reactive sputtering.

[0052] Optionally, during the Ta adsorption process, the filling gas in the internal environment can be a low-pressure inert gas.

[0053] Optionally, after Ta adsorption is complete, in order to remove excess sputtered Ta particles during the adsorption process and prevent the non-magnetic target material from being affected by Ta particle contamination during the sputtering of the non-magnetic layer, the chamber can be pre-sputtered before the formal target material is transferred in. The pre-sputtering target material can usually be the same element as the non-magnetic layer construction material, and MgO is selected here (but not limited to MgO). The pre-sputtering method is consistent with the formal sputtering method, covering but not limited to the methods mentioned above.

[0054] S204: The formal target material is moved into the chamber to construct the non-magnetic layer. After adsorption in the chamber is complete, the formal target material is moved into the chamber to prepare for sputtering of the non-magnetic layer.

[0055] S205, continue sputtering other layers. After the non-magnetic film layer has been sputtered and grown, sputtering continues upwards according to the specific layer structure requirements. Figure 2The preferred embodiment is illustrated using a top pinning structure as an example. After the preparation of the non-magnetic layer is completed, the fixing layer, antiferromagnetic coupling layer, pinning layer and cover layer are prepared in sequence.

[0056] Optionally, the sputtering method can be selected according to the actual situation, including but not limited to two-stage sputtering, three-stage or four-stage sputtering, magnetron sputtering, target sputtering, radio frequency sputtering, bias sputtering, asymmetric AC radio frequency sputtering, ion beam sputtering and reactive sputtering.

[0057] In embodiments of the present invention, the chamber particle adsorption uses Ta adsorption. Metallic Ta has extremely high corrosion resistance, and after sputtering, the atomic surface of Ta has extremely high adsorption capacity, making it suitable as a target material in the sputtering process to adsorb residual particles in the chamber and achieve the purpose of cleaning the chamber. According to Figure 4 As shown, the tunneling magnetoresistance (RA) value changes with the Ta adsorption time, and the two have a one-to-one matching relationship, thereby achieving the purpose of controlling the tunneling magnetoresistance (RA) value by controlling the Ta adsorption time. In the embodiments of this application, regardless of the change in adsorption time, the tunneling magnetoresistance (MR) value is between 120% and 130% and does not change significantly. From the perspective of magnetic random access memory (RAM) fabrication and application, it can be seen that when the MR value of the tunneling magnetoresistance remains greater than 100%, it can meet the current application requirements. Therefore, it can be seen that the tunneling magnetoresistance state is stable and meets the requirements during the adsorption process.

[0058] In another preferred embodiment of this application, in order to further ensure the cleanliness of the intramolecular molecules in the chamber, especially to prevent the presence of Ta particles during the adsorption process of the chamber particles, the chamber particle adsorption process in this embodiment of the invention also includes a pre-sputtering process after adsorption.

[0059] Figure 3 A preferred embodiment, taking a bottom-pinned structure as an example, describes a method for preparing a tunneling resistor. First, a bottom-level structure below the non-magnetic layer is prepared on a substrate, including a seed layer, a pinned layer, an antiferromagnetic coupling layer, and a fixing layer. Then, the target material of the final wafer is removed from the chamber, and the chamber is cleaned by Ta adsorption. In this preferred embodiment, after Ta particle adsorption is completed and before replacing the final non-magnetic layer target, a pre-sputtering treatment is performed inside the chamber. The same target material as the non-magnetic layer is selected, here MgO is used as an example (but not limited to MgO). A dummy wafer is first moved in for pre-sputtering. Pre-sputtering the MgO target removes Ta adsorption to a certain extent and cleans the target surface. Then, the final wafer is moved in to continue sputtering the various layers (free layer and capping layer) of the top-level structure. After the overall film stack is sputtered, an annealing operation is performed, followed by device fabrication and testing. Figure 5As shown, there is a one-to-one correspondence between MgO pre-sputtering time and RA value. As the MgO pre-sputtering time increases, the RA value decreases monotonically. This method allows for further control of the device's RA value, resulting in a wider range of selectable RA values ​​and higher control precision and greater freedom. Furthermore, from... Figure 5 It can also be seen that the tunneling magnetoresistance MR value is between 120% and 130% during the process and does not fluctuate significantly, thus indicating that the tunneling magnetoresistance is stable during the process.

[0060] This invention provides a method for preparing a tunneling magnetoresistive (MR) layer. Before sputtering the non-magnetic layer, a Ta sputtering adsorption pretreatment is performed inside the chamber. Particles inside the chamber are adsorbed onto the surface of the sputtered Ta particles and discharged. Based on the Ta adsorption time and the change in the system's RA value, after the pretreatment, the actual non-magnetic layer target material is introduced for sputtering. This process reduces the mixing degree of excess particles inside the chamber, achieving a cleaner chamber and lowering the vacuum level, thereby improving the quality of thin film sputtering. Because the pretreatment process does not change the thickness of the non-magnetic layer or the size of the magnetic tunnel junction, and because the Ta adsorption time and the RA value of the tunneling magnetoresistive (MR) have a one-to-one correspondence, the RA value of the tunneling magnetoresistive (MR) can be precisely controlled by controlling the Ta adsorption time. Furthermore, the MR value remains stable throughout the process, ensuring that the adjustment process has no negative impact on the durability of the tunneling magnetoresistive structure and the data reading function.

[0061] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing tunneling magnetoresistance, characterized in that, The method includes: Construct the bottom-level structure of the tunneling magnetoresistance; Control the particle adsorption time in the chamber according to the required RA value; In the chamber where adsorption is complete, a non-magnetic layer is constructed above the bottom hierarchical structure; A top-level structure is constructed on top of the non-magnetic layer; The cavity interior was pre-sputtered using the same target material as the non-magnetic layer. When the thickness of the non-magnetic layer is the same, the adsorption time of the chamber particles has a continuous relationship with the value of the tunneling magnetoresistance RA, and the adsorption of the chamber particles adopts Ta adsorption.

2. The method according to claim 1, characterized in that, The tunneling magnetoresistance includes a bottom-pinned structure or a top-pinned structure.

3. The method according to claim 1, characterized in that, The method further includes: Before controlling the particle adsorption time in the chamber, the actual target material is removed from the chamber; After adsorption is complete, the formal target material is moved into the chamber.

4. The method according to claim 1, characterized in that, In the method, a dummy wafer is first moved in to perform the pre-sputtering operation.

5. The method according to claim 1, characterized in that, In the method described, each layer is constructed using a sputtering process.

6. The method according to claim 1, characterized in that, The method further includes: During chamber particle adsorption, the chamber is filled with a low-pressure inert gas.

7. The method according to claim 1, characterized in that, In the method, when the thickness of the non-magnetic layer is the same, the pre-sputtering time and the tunneling magnetoresistance RA value have a continuous correspondence.

8. A method for fabricating a magnetic random access memory, characterized in that, The tunneling magnetoresistance of the magnetic tunnel junction in the magnetic random access memory is prepared using the method described in any one of claims 1-7.

Images