Preparation method of iron-cobalt film

Abstract

The invention discloses a preparation method of an iron-cobalt film, and relates to an electronic material technology, in particular to a film material preparation technology. The method comprises the following steps: step 1, cleaning a Si (100) substrate, a Co target material and a Fe target material; 2, co-sputtering a Fe target material and a Co target material by using an ultrahigh vacuum magnetron sputtering coating process, and depositing a FeCo film on the surface of the substrate; the method is characterized in that in the second step, direct current sputtering is adopted for both the Co target and the Fe target, and the material ratio of the FeCo film is controlled according to the following formula: R = a * (0.677 * S-0. 044), where 0.93 lt; a < lt >; 1.07). Wherein R = Fe atom ratio / Co atom ratio (mol ratio), and S = Fe target sputtering power / Co target sputtering power. By adopting the technology provided by the invention, the ratio of iron to cobalt in the iron-cobalt film can be accurately predicted, regulated and controlled according to the sputtering power of the iron-cobalt double targets.

Description

Technical Field

[0001] The present invention relates to electronic material technology, in particular to thin film material preparation technology. Background Art

[0002] As electronic communication systems develop towards higher frequencies, miniaturization, and integration, new requirements are being placed on the supporting materials of related electronic components. FeCo-based soft magnetic films not only exhibit in-plane uniaxial anisotropy—breaking the Snoek limit and thus achieving higher cutoff frequencies, making them more suitable for applications in high-frequency ranges above GHz—but also facilitate compatibility with standard processes for related on-chip integrated systems such as microwave integrated circuits (MICs) and microelectromechanical systems (MEMS).

[0003] Fe-based materials have high saturation magnetization, so they can obtain high initial permeability; Co-based materials have relatively low saturation magnetization, but high anisotropy field, and their cutoff frequency reaches the GHz band. (1-x) Co x (at.%)-based alloys offer the advantages of both. Literature reports that when x = 0.35, their saturation magnetization reaches its maximum; when x = 0.5, their magnetocrystalline anisotropy constant K1 approaches zero, resulting in the highest initial permeability. By adjusting the ratio of these two, the film's resonant frequency and microwave permeability can be adjusted.

[0004] However, current research on Fe-Co thin films primarily focuses on their preparation and properties, with less research on the compositional ratio of Fe-Co thin films. Typically, studies directly explore the film preparation process using a target material with a fixed Fe-Co ratio, or roughly change the compositional ratio of the Fe-Co thin film by attaching varying numbers of Fe sheets to the Co target during sputtering. Therefore, further exploration of a Fe-Co thin film preparation method that can accurately control the Fe-Co ratio is crucial. Summary of the Invention

[0005] The present invention addresses the problem of prior art in obtaining an accurate iron-cobalt ratio in iron-cobalt thin films. By proposing a method for preparing iron-cobalt thin films with controllable composition ratios, the present invention addresses the problem of prior art in obtaining an accurate iron-cobalt ratio in iron-cobalt thin films. This simple and convenient method allows the composition of the iron-cobalt thin films to be predicted, and the sputtering power to be adjusted based on the desired composition of the iron-cobalt thin films.

[0006] The technical solution adopted by the present invention to solve the technical problem is that the preparation method of the iron-cobalt thin film comprises the following steps:

[0007] Step 1: Cleaning the Si(100) substrate, Co target and Fe target;

[0008] Step 2: Using an ultra-high vacuum magnetron sputtering coating process, Fe target and Co target are co-sputtered to deposit an FeCo film on the substrate surface;

[0009] It is characterized in that, in the step 2, both the Co target and the Fe target are sputtered by DC, and the material ratio of the FeCo film is controlled by the following formula:

[0010] R = a × (0.677 × S - 0.044), where 0.93 <a<1.07。

[0011] Wherein, R=Fe atomic ratio / Co atomic ratio (mol ratio), S=Fe target sputtering power / Co target sputtering power.

[0012] Furthermore, in step 2, the magnetron sputtering conditions are as follows: the sputtering temperature is 18-25°C, the working gas is Ar gas, the working pressure is 3-7 mTorr, and the background vacuum is 3×10 -5 Pa~7×10 -5 Pa.

[0013] The step 1 is: using acetone, anhydrous ethanol and deionized water to clean the substrate in sequence, and blowing it dry with an N2 air gun; the substrate is a Si (100) substrate with a thickness of 500 nm.

[0014] The Fe target sputtering power and the Co target sputtering power are both in the range of 10W to 200W.

[0015] The present invention provides a method for preparing an iron-cobalt thin film with an arbitrarily adjustable composition ratio. By using a simple and convenient method, the iron-cobalt ratio in the iron-cobalt thin film can be accurately predicted and regulated according to the sputtering power of an iron-cobalt dual target. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is the EDS test result diagram of step 3 in Example 1;

[0017] Figure 2 This is the EDS test result diagram of step 4 in Example 1;

[0018] Figure 3 This is the EDS test result diagram of step 4 in Example 2;

[0019] Figure 4 This is the EDS test result diagram of step 4 in Example 3;

[0020] Figure 5 This is the EDS test result diagram of step 4 in Example 4;

[0021] Figure 6 Schematic diagram of the functional relationship between R (Fe atom ratio / Co atom ratio) and S (Fe target sputtering power / Co target sputtering power). DETAILED DESCRIPTION

[0022] In the present invention, the range represented by the symbol "~" includes the endpoint values. For example, "18 to 25°C" includes 18°C ​​and 25°C.

[0023] Example 1

[0024] This embodiment includes the following steps:

[0025] Step 1: Clean the substrate with acetone, anhydrous ethanol, and deionized water in sequence, and blow dry with an N2 air gun; the substrate is a 500 nm thick Si(100) substrate.

[0026] Step 2: Co target and Fe target are co-sputtered by magnetron sputtering process, and FeCo thin film is deposited on the substrate surface; the magnetron sputtering conditions are: sputtering temperature is room temperature, working gas is Ar gas, working pressure is 5mTorr, background vacuum is 5×10 -5 Pa, sputtering time is 15min, target-substrate distance is 120mm, sample stage speed is 10rpm; Co target adopts DC sputtering, Fe target adopts DC sputtering; Co target power is 20W, Fe target power is 20W.

[0027] Step 3: Perform EDS test on the FeCo film obtained in step 2:

[0028] Through EDS testing, the Fe content in step 2 was obtained to be 0.37, the Co content was 0.63, and the iron-cobalt atomic ratio was 0.37:0.63≈0.587.

[0029] From the data of Example 1, it can be seen that R (Fe atomic ratio / Co atomic ratio)=0.587, and S (Fe target sputtering power / Co target sputtering power)=20 / 20=1.

[0030] Example 2

[0031] The difference between this embodiment and embodiment 1 lies in step 2. In this embodiment, the sputtering power P of the Fe target is 10W, and the sputtering power of the Co target is fixed at 20W.

[0032] EDS test: Fe content is 0.23, Co content is 0.77, and the iron-cobalt atomic ratio is 0.23 / 0.77≈0.299.

[0033] From the data of Example 2, it can be seen that R (Fe atomic ratio / Co atomic ratio) = 0.299, S (Fe target sputtering power / Co target sputtering power) = 10 / 20 = 0.5.

[0034] Example 3

[0035] The difference between this embodiment and embodiment 1 lies in step 2. In this embodiment, the sputtering power P of the Fe target is 30W, and the sputtering power of the Co target is fixed at 20W.

[0036] EDS test: Fe content is 0.51, Co content is 0.49, and the iron-cobalt atomic ratio is 0.51 / 0.49≈1.041;

[0037] From the data of Example 3, it can be seen that R (Fe atomic ratio / Co atomic ratio) = 1.041, and S (Fe target sputtering power / Co target sputtering power) = 30 / 20 = 1.5.

[0038] Example 4

[0039] The difference between this embodiment and embodiment 1 lies in step 2. In this embodiment, the sputtering power P of the Fe target is 55W, and the sputtering power of the Co target is fixed at 20W.

[0040] EDS test: Fe content is 0.64, Co content is 0.36, and the iron-cobalt atomic ratio is 0.64 / 0.36≈1.778;

[0041] From the data of Example 4, it can be seen that R (Fe atomic ratio / Co atomic ratio) = 1.778, and S (Fe target sputtering power / Co target sputtering power) = 55 / 20 = 2.75.

[0042] Example 5

[0043] The difference between this embodiment and embodiment 1 lies in step 2. In this embodiment, the sputtering power P of the Fe target is 100W, and the sputtering power of the Co target is fixed at 20W.

[0044] EDS test: Fe content is 0.77, Co content is 0.23, and the iron-cobalt atomic ratio is 0.77 / 0.23=3.348;

[0045] From the data of Example 5, it can be seen that R (Fe atomic ratio / Co atomic ratio) = 3.348, and S (Fe target sputtering power / Co target sputtering power) = 100 / 20 = 5.

[0046] The data of each embodiment are as follows Figure 6 As shown, it can be seen that it obeys the following distribution:

[0047] R = a × (0.677 × S - 0.044), where 0.93 <a<1.07。

[0048] In summary, the present invention provides a method for preparing an iron-cobalt thin film with a controllable composition ratio. This method addresses the prior art issue of being unable to accurately determine the iron-cobalt content ratio in the iron-cobalt thin film. By utilizing simple and convenient EDS test results and theoretical calculation formulas, the composition of the iron-cobalt thin film can be predicted. The sputtering power can also be adjusted based on the desired composition of the desired iron-cobalt thin film, with an error rate of less than 8.7%. This invention thus enables a method for adjusting the composition of iron-cobalt binary alloy thin films to any desired value, significantly reducing experimental time and costs while maintaining high accuracy.

Claims

1. A method for preparing an iron-cobalt thin film, comprising the following steps: Step 1: Cleaning the Si(100) substrate, Co target and Fe target; Step 2: Using an ultra-high vacuum magnetron sputtering coating process, Fe target and Co target are co-sputtered to deposit an FeCo film on the substrate surface; It is characterized by: In the step 2, both the Co target and the Fe target are sputtered by DC, and the material ratio of the FeCo film is controlled by the following formula: R = a × (0.677 × S - 0.044), where 0.93 <a<1.07。 Wherein, R=Fe atom ratio / Co atom ratio, S=Fe target sputtering power / Co target sputtering power.

2. The method for preparing an iron-cobalt thin film according to claim 1, wherein: In the step 2, the magnetron sputtering conditions are as follows: the sputtering temperature is 18-25°C, the working gas is Ar gas, the working pressure is 3-7 mTorr, and the background vacuum is 3×10 -5 Pa~7×10 -5 Pa.

3. The method for preparing an iron-cobalt thin film according to claim 1, wherein: The step 1 is: using acetone, anhydrous ethanol and deionized water to clean the substrate in sequence, and blowing it dry with an N2 air gun; the substrate is a Si (100) substrate with a thickness of 500 nm.

4. The method for preparing an iron-cobalt thin film according to claim 1, wherein: In the step 2, the sputtering time is 15 min, the target-substrate distance is 120 mm, and the sample stage rotation speed is 10 rpm.

5. The method for preparing an iron-cobalt thin film according to claim 1, wherein: The Fe target sputtering power and the Co target sputtering power are both in the range of 10W to 200W.

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