CN103276356A - A Method of Improving Thermal Stability of Cu3N Thin Film - Google Patents

Abstract

The invention discloses a method for improving heat stability of a Cu3N thin film. The method comprises the following steps of: 1, sequentially carrying out ultrasonic-cleaning on an Si(100) substrate for depositing a sample by cleanser essence, acetone, anhydrous alcohol and deionized water for 15 minutes for later use; 2, placing a doped material on a Cu target, and then, placing the substrate on a sample stand which is parallel to the surface of the target and 50-60mm away from the surface of the target; 3, ensuring that the target is not grounded; 4, carrying out corrosion of HF (Hydrofluoric acid) with the concentration of 1% on the Si(100) substrate for 1-2 minutes, washing with plasma water after HF acid treatment, and then airing and placing the substrate on the sample stand; 5, closing a vacuum chamber and vacuumizing; and 6, introducing pure nitrogen to the vacuum chamber and co-sputtering the target and the doped material in the conditions of low temperature and low power. The heat stability of the Cu3N thin film is improved by co-sputtering the target and the doped material.

Description

A Method of Improving Thermal Stability of Cu3N Thin Film

technical field

The invention belongs to the field of semiconductor thin film preparation, in particular to a method for improving the thermal stability of Cu ₃ N thin film.

Background technique

Cuprous nitride (Cu ₃ N) semiconductor material with reverse ReO ₃ structure and low decomposition temperature has very bright application prospects in optical information storage and large-scale integrated circuits ^[1-3] . Recently, it has been reported that this material can also be used in spintronic devices, solar cells, fuel cells, magnetic tunnel junctions and other fields ^[1,4-9] , so this system has attracted wide attention internationally. How to increase the thermal decomposition temperature of Cu ₃ N to a suitable temperature to make it better used is one of the focuses in the current Cu ₃ N research field.

There are two ways to increase the thermal _{decomposition temperature. First, change the growth conditions to grow high-quality, ideal stoichiometric Cu 3 N films ;} Inorganic matrix materials, the extra atoms (Ni, Cu, Zn, Pd, Ag, and Cd) occupy the body center position of the cubic anti-ReO ₃ unit cell, so the energy band structure of Cu ₃ N can be modified by doping to realize Cu ₃ N thermal stability, even electrical, optical and other characteristics can be adjusted in a large range. For the former, the technology of growing Cu ₃ N thin films with ideal stoichiometric ratio is relatively mature. For the doping of Cu ₃ N, there have been some experimental reports, but the doping of Cu ₃ N thin films is _a complicated process. Where do the dopant atoms are doped? How do the types of atoms affect the physical properties of Cu ₃ N thin films, and how do the properties of doped thin films depend on the content of doping elements, etc. need to be further studied.

references:

[1] Asano M, Umeda K and Tasaki A 1990 Jpn. J. Appl. Phys. 29 1985

[2] Maruyama T and Morishita T 1996 Appl Phys. Lett. 69 890

[3] Nosaka T, Yoshitake M, Okamoto A, Ogawa S and Nakayama Y 2001 Appl. Surf. Sci. 169 358

[4] Maya L 1993 Mater. Res. Soc. Symp. Proc 282 203

[5] Maya L 1993 J. Vac. Sci. Technol. A11 604

[6] Cremer R, Witthaut M, Neuschutz D, Trappe C, Laurenzis M, Winkle O and Kurz H 2000 Mikrochim. Acta 133 299

[7] Navio C, Alvarez J, Capitan M J, Camarero J and Miranda R 2009 Appl. Phys. Lett. 94 263112

[8] Navio C, Capitan M J, Alvarez J, Yndurain F and R. Miranda 2007 Phys Rev B 76 085105

[9] Borsa D M, Grachev S, Presura C and Boerma D O 2002 Appl. Phys. Lett. 80 1823

Contents of the invention

The technical solution adopted by the present invention to solve its technical problems specifically comprises the steps:

Step 1. The Si (100) substrate used for depositing samples is cleaned successively with detergent, acetone, absolute alcohol and deionized water for 15 minutes each ultrasonically, and set aside.

Step 2. Place the doped material on the Cu target, then place the substrate on the sample holder, which is parallel to the target surface and 50-60 mm apart. the

Step 3. Check whether the target is grounded, and if it is grounded, replace it to ensure that the target is not grounded. the

Step 4. The Si (100) substrate needs to be etched with 1% concentration of HF acid for 1-2 minutes. After the HF acid treatment, it is rinsed with plasma water, then dried and placed on the sample holder. the

Step 5. Close the vacuum chamber and pump the vacuum. the

Step 6. When the background pressure in the vacuum chamber is lower than 6×10 ^-6 mbar, feed pure nitrogen gas (99.99%) into the vacuum chamber, and co-sputter the target and dopant material under the condition of low temperature and low power, by changing The coverage area and location of the dopant material on the target, and Cu ₃ NM _x films with different composition ratios were synthesized on the substrate.

Step 7. The prepared Cu ₃ NM _x film needs to be tested for the electrical characteristics of the thermal decomposition products to ensure that the thermal decomposition products are good conductors.

The materials for co-sputtering are In and Ti. the

In the present invention, the thermal stability of the Cu ₃ N film is improved by co-sputtering the doping material and the target material, and the co-sputtering is carried out under the conditions of low temperature, low pressure and low power, and the co-sputtering material can be In, Ti, etc. .

In doping is chosen mainly because InN has a relatively high decomposition temperature ~ 873K. It can be imagined that if Cu ₃ N is doped with In, the resulting film may have some novel properties in terms of structure, electricity, optics, etc. characteristics, and can maintain semiconductor characteristics while reasonably increasing the decomposition temperature. In this way, the thin film can not only withstand the ambient temperature of most electronic devices, maintain the stability at high temperature, but also allow the use of localized heating mode (electron beam/laser beam fast scanning) with a lower cost and less distortion to the existing device structure. The temperature causing damage results in a micro-nano metal structure with good conductivity.

Choose Ti doping, the advantage of Ti doping is that the melting point of titanium nitride is very high, which makes

Ti-doped Cu ₃ N films may have a higher decomposition temperature, and because titanium nitrides are good conductors, even if there is a separate phase of titanium nitrides in the composite film, it will not affect the metal of the decomposition products. Conductivity and high reflectivity. Therefore, if the cuprous nitride film doped with a small amount of titanium still maintains semiconducting properties, it may still be used for optical information storage and integrated circuits.

The beneficial effects of the present invention are as follows:

The method makes up for the deficiencies of the prior art and improves the thermal stability of the Cu ₃ N thin film.

Description of drawings

Figure 1 XRD spectrum of the Cu _x In _y N film, corresponding to the In content of the sample is 8.2at.%: (a) as-received sample, (b) annealed at 330°C, (c) annealed at 360°C;

Figure 2 XRD spectra of films with a titanium content of 2.2at.% at different temperatures: (a) as-received sample, (b) annealed at 350°C, (c) annealed at 400°C, (d) annealed at 450°C, (e) at 500°C ℃ annealing.

Detailed ways

The present invention will be further described below in conjunction with drawings and embodiments. the

As shown in Figure 1 and Figure 2, a method for improving the thermal stability of a Cu ₃ N thin film specifically includes the following steps:

Step 1. The Si (100) substrate used for depositing samples was cleaned sequentially with detergent, acetone, absolute alcohol and deionized water for 15 minutes, and then set aside.

Step 2. Place the doped material on the Cu target, and then place the substrate on the sample holder, which is parallel to the target surface and 55 mm apart. the

Step 3. When the background pressure in the vacuum chamber is lower than 6×10 ^-6 mbar, feed pure nitrogen gas (99.99%) with a flow rate of 7 sccm into the vacuum chamber to co-sputter the target and the dopant material, by changing the doping The coverage area and coverage position of the material on the target, and Cu ₃ NM _x films with different composition ratios were synthesized on the substrate.

The materials for co-sputtering are In and Ti.

In the present invention, the thermal stability of the Cu ₃ N film is improved by co-sputtering the doping material and the target material, and the co-sputtering is carried out under the conditions of low temperature, low pressure and low power, and the co-sputtering material can be In, Ti, etc. .

The thermal stability of the Cu ₃ M _x N thin films was annealed at different temperatures for 20 minutes under the protection of N ₂ gas, and then the relevant physical properties were measured and analyzed. If there is a metallic copper peak in the XRD spectrum of the annealed sample, the sample is considered to start to decompose, and the decomposition temperature is the corresponding annealing temperature at this time. It can be clearly seen from Fig. 1 that the decomposition temperature of the sample with an In content of 8.2 at.% and a dominant Cu ₃ N phase is 360 °C.

Example 1

CuN films with different In dopings were prepared on Si (100) substrates by radio frequency magnetron sputtering. First, the substrate used for depositing samples was ultrasonically cleaned with detergent, acetone, absolute alcohol, and deionized water for 15 minutes in sequence, and then the substrate was placed on a sample holder parallel to the target surface and 55 mm away from it. When the background pressure in the vacuum chamber is lower than 6× ^10-6 mbar, pure nitrogen gas (99.99%) with a flow rate of 7 sccm is introduced into the chamber, and the pure Cu target (99.99%) and the high-purity In on it are co-sputtered. (99.999%) particles, by changing the coverage area and location of In on the target, Cu _x In _y N films with different composition ratios are synthesized on the substrate. The working pressure was controlled at 7×10 ^-3 mbar, and the pre-sputtering and film deposition processes were maintained for 30 minutes respectively. During the deposition process, the substrate temperature was controlled at ~333K, and the RF input power was 60 W.

The thermal stability of the Cu _x In _y N thin film was annealed at different temperatures for 20 minutes under the protection of N ₂ gas, and then the relevant physical properties were measured and analyzed. If there is a metallic copper peak in the XRD spectrum of the annealed sample, the sample is considered to start to decompose, and the decomposition temperature is the corresponding annealing temperature at this time. It can be clearly seen from Fig. 1 that the decomposition temperature of the sample with an In content of 8.2 at.% and a Cu ₃ N phase dominance is 360 °C, compared with the decomposition temperature of 300 °C for a pure Cu ₃ N film, the thermal Stability has been slightly improved.

Example 2

Copper nitride films with different Ti doping were prepared on Si (100) substrates by radio frequency magnetron sputtering. The conditions are the same as the implementation case (1).

The doped Cu ₃ N film with a Ti content of 2.2at.% was selected for thermal stability research. Under the protection of nitrogen, the sample was annealed for 20 minutes. Figure 2 shows the XRD spectrum of the sample after annealing at different temperatures. It can be seen from the figure that the Cu (111) diffraction peak appeared after the film was annealed at 400 ° C, but The (100) diffraction peak of Cu ₃ N in the film is still dominant until after annealing at 500℃. The above results show that the thermal stability of the Ti-doped cuprous nitride film is improved, the decomposition rate of the film is slowed down, and the decomposition temperature of the Cu ₃ N film is increased to ~500.

Claims (1)

1. a method for improving Cu ₃ N thin film thermal stability, is characterized in that comprising the steps: Step 1. The Si (100) substrate used for depositing the sample is cleaned successively with detergent, acetone, absolute alcohol and deionized water for 15 minutes, and set aside; Step 2. Place the doped material on the Cu target, then place the substrate on the sample holder, the sample holder is parallel to the target surface and 50-60 mm apart; Step 3. Check whether the target is grounded, and if it is grounded, replace it to ensure that the target is not grounded; Step 4. Corrode the Si (100) substrate with 1% concentration of HF acid for 1-2 minutes. After the HF acid treatment, rinse it with plasma water, then dry it and place it on the sample holder. Step 5. Close the vacuum chamber and vacuumize; Step 6. When the background pressure in the vacuum chamber is lower than 6×10 ^-6 mbar, feed pure nitrogen gas (99.99%) into the vacuum chamber, and co-sputter the target and dopant material under the condition of low temperature and low power, by changing Covering area and position of dopant material on the target, and Cu ₃ NM _x films with different composition ratios synthesized on the substrate; The co-sputtered material is In, Ti; Step 7. The prepared Cu ₃ NM _x film needs to be tested for the electrical characteristics of the thermal decomposition products to ensure that the thermal decomposition products are good conductors.

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