Method for performing MRAM (Magnetic Random Access Memory) detection by utilizing Polar-MOKE technology

Abstract

The invention relates to a method for detecting an MRAM (Magnetic Random Access Memory) by utilizing a Polar-MOKE technology, and belongs to the technical field of memory detection. The method comprises the following steps: (1) preparing a sample and arranging an experimental device; (2) placing a sample; (3) initial calibration; (4) setting a polarization direction; (5) measuring a signal; (6) changing a magnetic field; (7) recording a measurement result; and (8) data analysis. According to the invention, the Polar-MOKE technology is combined with the MRAM structure, so that the rapid and accurate detection of the magnetic state of the MTJ can be realized, the problems of a traditional method are avoided, a more stable and reliable MRAM detection result can be provided, and the integration performance is good.

Description

TECHNICAL FIELD

[0001] The application relates to a method for MRAM detection by using a Polar-MOKE technology and belongs to the technical field of memory detection. BACKGROUND

[0002] A magnetoresistive random access memory (MRAM) is a new type of non-volatile memory technology, which has the advantages of high-speed reading and writing, low power consumption, no wear and tear, etc. It is widely researched and applied in the field of memory. The core of MRAM is a magnetic random access memory unit (MTJ), which is composed of an insulating layer between two layers of magnetic materials.

[0003] In the existing MRAM detection method, common techniques include resistance detection, capacitance detection and magnetic detection, etc. However, these methods have some problems and limitations, for example, the resistance detection method needs an external current source, which increases the circuit complexity and power consumption, the capacitance detection method is affected by various noise sources, making the detection result not stable and reliable, and the magnetic detection method needs special magnetic force microscopes and other equipment, which is high in cost and not easy to realize integration.

[0004] Therefore, a new MRAM detection method is needed to overcome the above problems and limitations and improve the accuracy and reliability of detection.

[0005] In recent years, the Polar-MOKE (Polar Magneto-Optical Kerr Effect) technology has been widely used in the field of magnetic material research. The Polar-MOKE technology uses a laser beam to irradiate the surface of a magnetic material and analyzes the magnetic information of the material by detecting the polarization state of the reflected light. This technology has the advantages of non-contact, high sensitivity and high resolution. SUMMARY

[0006] In view of the shortcomings of the prior art, the application provides a method for MRAM detection by using the Polar-MOKE technology. The Polar-MOKE technology is combined with the MRAM structure to realize fast and accurate detection of the magnetic state of the MTJ, avoiding the problems of traditional methods, providing more stable and reliable MRAM detection results, and having good integration performance.

[0007] The technical scheme of the application is as follows:

[0008] A method for MRAM detection by using the Polar-MOKE technology, the steps are as follows:

[0009] (1) Prepare the sample: select the sample to be measured and ensure that the surface of the sample is clean and flat to obtain accurate measurement results;

[0010] Set up the experimental device;

[0011] (2) Sample placement;

[0012] (3) Initial calibration;

[0013] (4) Setting polarization direction;

[0014] (5) Measuring signal;

[0015] (6) Changing magnetic field;

[0016] (7) Recording measurement results;

[0017] (8) Data analysis.

[0018] According to the present application, in step (1), the experimental device is set up as follows: a Polar-MOKE measurement system is built, which includes a sample stage, a light source, a rotating polarizer, an optical system, and a magnetic field device arranged in sequence along the optical path, wherein:

[0019] Light source: a polarized light source such as a laser or LED is used to generate a light beam with a known polarization direction;

[0020] Rotating polarizer: the polarization direction of the light is adjusted by rotating the polarizer;

[0021] Optical system: including lenses, polarizing plates, and optical detectors, used to control and detect the properties of the light;

[0022] Magnetic field device: an external magnetic field is applied by an electromagnetic coil or permanent magnet system to control the magnetization state of the sample;

[0023] Sample stage: for placing the sample.

[0024] According to the present application, in step (2), the sample is placed on the sample stage in the measurement system, ensuring that the sample is perpendicular to the optical path to obtain the best measurement results.

[0025] According to the present application, in step (3), the initial calibration includes calibrating the optical path, rotating the polarizer, and the reference sample, and performing initial calibration to ensure the stability and accuracy of the measurement system.

[0026] According to the present application, in step (4), the polarization direction is set by rotating the polarizer so that the polarization direction of the light is perpendicular to the magnetization direction of the sample to maximize the change in the reflection characteristics of the light.

[0027] According to the present application, in step (5), the measurement signal is obtained by turning on the light source, the light beam irradiates the sample surface, and the reflected light is collected by the optical system, and the intensity and polarization state of the reflected light are measured by the optical detector.

[0028] According to the application, preferably, in step (6), the magnetic field is changed by changing the magnetic field of the sample through the magnetic field device, including the direction or strength of the magnetic field.

[0029] According to the application, preferably, in step (7), the measurement results are recorded by recording the measurement results under each magnetic field, including the intensity and polarization state of the reflected light, which reflects the changes in the magnetization of the sample.

[0030] According to the application, preferably, in step (8), data analysis is performed by analyzing the measurement data under different magnetic fields to determine the magnetization state and characteristics of the sample.

[0031] The detection principle is as follows: the laser beam passes through the polarizer and irradiates the surface of the MTJ, and then the reflected light is detected by the optical detector, which can measure and record the changes in the polarization state of the light, thereby obtaining the magnetic information of the MTJ.

[0032] The advantages of the application are as follows:

[0033] 1. In the traditional MRAM method, such as resistance detection, an external current source is needed to measure the resistance change of the magnetic material, so as to determine the magnetic state. However, this method increases the complexity of the circuit and requires additional power consumption. The present application realizes non-contact detection by using the Polar-MOKE technology, avoids the use of external current source, and thus reduces the complexity of the circuit and power consumption.

[0034] 2. The existing capacitance detection method has problems of stability and reliability in MRAM detection, and is disturbed by various noise sources, resulting in a decrease in the reliability of the detection results. The present application uses the Polar-MOKE technology to analyze the polarization state of the reflected light, which can realize fast and accurate detection of the magnetic state of the MTJ, and provide more stable and reliable MRAM detection results.

[0035] 3. The traditional magnetic detection method usually needs special and expensive equipment, such as a magnetic force microscope, which increases the cost of equipment and is not easy to realize integration. In contrast, the present application uses the Polar-MOKE technology, which has the characteristics of non-contact, high sensitivity and high resolution, and can realize integration in the conventional MRAM manufacturing process, thereby reducing the cost of equipment and improving the integration performance. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 is a schematic diagram of the magnetic field injection of the application;

[0037] Figure 2 is a comparison chart of the detection effect of the application and the existing detection method, wherein, Figure 2 (a) is a detection effect chart of the existing detection method,Figure 2 (b) is the detection effect diagram of the present application;

[0038] Figure 3 (b) is the detection effect diagram of the present application; Figure 3 (a) is the spectral response diagram of the magneto-optical detection, Figure 3 (b) is the spectral response diagram of the optical detection of the present application, in which the black and red curves represent the spectral responses of two structures with opposite spins, the solid curve represents +B magnetization, and the dashed curve represents -B magnetization. As can be seen from the spectral response, the former is more advantageous, with a yield improvement of about 78% and a detection efficiency improvement of 44%. DETAILED DESCRIPTION

[0039] The present application will be further described below by way of examples and in conjunction with the accompanying drawings, but is not limited thereto.

[0040] Example 1:

[0041] This embodiment provides a method for MRAM detection using Polar-MOKE technology, the steps are as follows:

[0042] (1) Prepare the sample: select the sample to be measured and ensure that the surface of the sample is clean and flat to obtain accurate measurement results;

[0043] Set up the experimental device and build a Polar-MOKE measurement system, which includes a sample stage, a light source, a rotating polarizer, an optical system and a magnetic field device arranged in sequence along the optical path, wherein:

[0044] Light source: use a polarized light source such as a laser or LED to generate a light beam with a known polarization direction;

[0045] Rotating polarizer: adjust the polarization direction of the light by rotating the polarizer;

[0046] Optical system: including lenses, polarizing plates and optical detectors, for controlling and detecting the properties of light;

[0047] Magnetic field device: apply an external magnetic field through an electromagnetic coil or permanent magnet system to control the magnetization state of the sample;

[0048] Sample stage: for placing the sample.

[0049] (2) Place the sample, place the sample to be measured on the sample stage in the measurement system, and ensure that the sample is perpendicular to the optical path to obtain the best measurement results.

[0050] (3) Initial calibration, including calibration of the optical path, rotating polarizer and reference sample, initial calibration is carried out to ensure the stability and accuracy of the measurement system.

[0051] (4) Set the polarization direction, by rotating the polarizer, make the polarization direction of light perpendicular to the magnetization direction of the sample, to maximize the change of the reflection characteristics of light.

[0052] (5) Measure the signal, turn on the light source, the light beam irradiates to the sample surface, and the reflected light is collected through the optical system, the intensity and polarization state of the reflected light are measured by the optical detector.

[0053] (6) Change the magnetic field, change the magnetic field of the sample through the magnetic field device, including the direction or strength of the magnetic field.

[0054] (7) Record the measurement results, record the measurement results under each magnetic field, including the intensity and polarization state of the reflected light, which reflects the changes of the magnetization of the sample.

[0055] (8) Data analysis, according to the measurement results, compare the measurement data under different magnetic fields, determine the magnetization state and characteristics of the sample.

[0056] Improvements and technical advantages:

[0057] Non-contact detection: Compared with the traditional resistance detection method, the embodiment realizes non-contact detection by using Polar-MOKE technology. This non-contact method avoids the use of external current source, reduces the complexity and power consumption of the circuit, and reduces the interference to the MTJ structure, improves the detection accuracy and reliability.

[0058] High sensitivity and high resolution: Polar-MOKE technology has high sensitivity and high resolution. By analyzing the polarization state of reflected light, the rapid and accurate detection of MTJ magnetic state can be realized. The advantages of high sensitivity and high resolution make the embodiment capable of detecting small magnetization changes, improving the stability and reliability of the detection results.

[0059] Low cost and integration performance: Compared with traditional magnetic detection methods, the embodiment uses Polar-MOKE technology with low cost and good integration performance. Polar-MOKE technology can be integrated in the conventional MRAM manufacturing process, avoiding the use of expensive special equipment, reducing equipment cost, and facilitating mass production.

[0060] Therefore, the method of using Polar-MOKE technology for MRAM detection has the advantages of high precision, non-contact, rapid, low power consumption, low cost, reliability and stability, which makes the embodiment an effective technical means, helps to improve the manufacturing quality and performance of MRAM, and promotes its wide application in the field of memory.

Claims

1. A method for MRAM detection using Polar-MOKE technique, characterized in that, The steps are as follows: (1) Prepare the sample and set up the experimental apparatus; (2) Place the sample; (3) Initial calibration; (4) Set the polarization direction; (5) Measure the signal; (6) Change the magnetic field; (7) Record the measurement results; (8) Data analysis.

2. The method for MRAM detection using Polar-MOKE technique as claimed in claim 1 wherein, In step (1), the experimental apparatus is set up: a Polar-MOKE measurement system is built, which includes a sample stage, a light source, a rotating polarizer, an optical system, and a magnetic field device in sequence along the optical path. Among them: Light source: Use a polarized light source to generate a light beam with a known polarization direction; Rotating polarizer: Adjust the polarization direction of the light by rotating the polarizer; Optical system: Includes lenses, polarizing plates, and optical detectors to control and detect the properties of light; Magnetic field device: Apply an external magnetic field through an electromagnetic coil or permanent magnet system to control the magnetization state of the sample; Sample stage: for placing the sample.

3. The method for MRAM detection using Polar-MOKE technique as claimed in claim 2 wherein, In step (2), the sample is placed: the sample to be measured is placed on the sample stage in the measurement system, ensuring that the sample is perpendicular to the optical path.

4. The method for MRAM detection using Polar-MOKE technique as claimed in claim 3, wherein, In step (3), the initial calibration includes calibrating the optical path, rotating the polarizer, and the reference sample.

5. The method for MRAM detection using Polar-MOKE technique as claimed in claim 4 wherein, In step (4), the polarization direction is set: through the rotating polarizer, the polarization direction of the light is perpendicular to the magnetization direction of the sample.

6. The method for MRAM detection using Polar-MOKE technique as claimed in claim 5 wherein, In step (5), the signal is measured: turn on the light source, the light beam shines on the sample surface, and the reflected light is collected through the optical system, and the intensity and polarization state of the reflected light are measured using the optical detector.

7. The method for MRAM detection using Polar-MOKE technique as claimed in claim 6 wherein, In step (6), the magnetic field is changed: the magnetic field of the sample is changed by the magnetic field device, including the direction or strength of the magnetic field.

8. The method for MRAM detection using Polar-MOKE technique as claimed in claim 7, wherein, In step (7), the measurement results are recorded: record the measurement results under each magnetic field, including the intensity and polarization state of the reflected light.

9. The method for MRAM detection using Polar-MOKE technology according to claim 8, wherein: In step (8), data analysis: analyze the data according to the measurement results, compare the measurement data under different magnetic fields, and determine the magnetization state and characteristics of the sample.

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