CN101285173A - Double-target radio frequency magnetron cosputtering method of Mg<x>Zn<1-x>O film - Google Patents

Abstract

The invention discloses a method for preparing Mg _x Zn _1-x O thin films by double-target radio frequency magnetron co-sputtering, which belongs to the technical field of photoelectric functional material manufacturing. The known technology needs to make Mg _x Zn _1-x O ceramic targets corresponding to the value of x according to the different Mg _x Zn _1-x O thin films to be prepared. The production workload is large, and the targets may not be completely consumed, resulting in Waste, the stoichiometric ratio of the prepared Mg _x Zn _1-x O thin film deviates from the stoichiometric ratio of the Mg _x Zn _1-x O ceramic target. The present invention adopts the double-target co-sputtering preparation method, that is, the ZnO ceramic target and the MgO ceramic target are respectively fixed on the two sputtering targets, sputtering power is provided respectively, and Mg _x Zn is grown on the substrate at the same time. _1-x O film. The invention can be applied to prepare Mg _x Zn _1-x O thin film of semiconductor photoelectric functional material with functions of ultraviolet detection, visible and ultraviolet light emission.

Description

Preparation method of MgxZn1-xO thin film by double-target RF magnetron co-sputtering

technical field

The invention relates to a method for preparing a Mg _x Zn _1-x O thin film of semiconductor photoelectric functional material with wide bandgap and wide component of II-VI family, and belongs to the technical field of photoelectric functional material manufacturing.

Background technique

Zn²⁺的离子半径为

由于它们离子半径相近，可以相互取代形成Mg_xZn_1-xO固溶合金薄膜，两者取代对晶格常数影响较小。但是，ZnO和MgO的结构不同，使得Mg_xZn_1-xO随着Mg含量的不同呈现两种不同的结构，当Mg含量较小时呈现ZnO的六方纤锌矿结构，当Mg含量较大时呈现MgO的面心立方岩盐结构。另外，ZnO和MgO的禁带宽度不同，室温下ZnO的禁带宽度约为3.3eV，MgO的禁带宽度约为7.8eV，从而Mg_xZn_1-xO的禁带宽度理论上在3.3eV和7.8eV之间可以连续调节，且禁带宽度随Mg含量的增大逐渐增大，从而可实现Mg_xZn_1-xO从紫外到可见不同波长的光响应。因此，Mg_xZn_1-xO薄膜成为一种具有紫外探测、可见及紫外光发射作用的半导体光电功能材料。Mg _x Zn _1-x O thin film is a wide direct bandgap semiconductor photoelectric functional material. The ionic radius of Mg ²⁺ is

The ionic radius of Zn ²⁺ is

Because their ionic radii are similar, they can replace each other to form Mg _x Zn _1-x O solid solution alloy thin films, and the substitution of the two has little effect on the lattice constant. However, the structures of ZnO and MgO are different, so that Mg _x Zn _1-x O presents two different structures with different Mg content. When the Mg content is small, it presents the hexagonal wurtzite structure of ZnO. When the Mg content is large, it presents the hexagonal wurtzite structure of ZnO. It presents the face-centered cubic rock-salt structure of MgO. In addition, the band gaps of ZnO and MgO are different. At room temperature, the band gap of ZnO is about 3.3eV, and that of MgO is about 7.8eV. Therefore, the band gap of Mg _x Zn _1-x O is theoretically 3.3eV and 7.8eV can be continuously adjusted, and the forbidden band width gradually increases with the increase of Mg content, so that the photoresponse of Mg _x Zn _1-x O from ultraviolet to visible wavelengths can be realized. Therefore, the Mg _x Zn _1-x O thin film becomes a semiconductor optoelectronic functional material with ultraviolet detection, visible and ultraviolet light emission.

The radio frequency magnetron sputtering preparation method of Mg _x Zn _1-x O thin film is a known technology related to the present invention, an article is published in the 9th phase of the 54th volume of China's "Acta Physica" entitled "Radio Frequency Magnetron Structure and Optical Properties of _{MgxZn1 -} xO Thin Films Grown by Sputtering" discloses a scheme. The preparation process is carried out in the vacuum chamber of the radio frequency magnetron sputtering apparatus. The vacuum is evacuated to 2×10 ^-3 Pa by two stages of mechanical pump and molecular pump. The target material is Mg _x Zn _1-x O ceramics, 0≤x≤0.3, which is made of ZnO powder and MgO powder with a purity of 99.99% through mixing, grinding, forging and sintering. Several sputtering targets, such as four, are set in the vacuum chamber, and the target material is fixed on the sputtering targets, and the sputtering power of each sputtering target can be controlled separately. The target material x on each sputtering target is different, such as x=0, x=0.16, x=0.23, x=0.30. The argon gas and oxygen gas with a purity of 99.999% and a pressure of 1Pa passed into the vacuum chamber are mixed in the vacuum chamber as sputtering gas. The RF power frequency is 13.56MHz. A sapphire substrate is used, and the substrate temperature is 80°C. The distance between the substrate and the sputtering target is 5 cm. The sputtering power is 200w, and the sputtering time is 30min. According to the different x of the prepared Mg _x Zn _1-x O thin film, Mg _x Zn _1-x O ceramic targets are prepared respectively. During the sputtering process, only one sputtering target with the corresponding value of x works, as Single target single sputtering preparation method.

Contents of the invention

The known technology needs to make Mg _x Zn _1-x O ceramic targets corresponding to the value of x according to the different Mg _x Zn _1-x O films to be prepared. The disadvantage is that the workload of making targets is large, and , after preparing a Mg _x Zn _1-x O thin film, the target material used may not be completely consumed, resulting in waste. In addition, although it should be impossible in theory, in practice, the stoichiometric ratio of the prepared Mg _x Zn _1-x O film deviates from the stoichiometric ratio of the Mg _x Zn _1-x O ceramic target, and it is difficult to obtain the desired required optoelectronic functional materials. In order to reduce the workload of target production, improve the utilization rate of the target, and prepare the product consistent with the desired product, we invented a method for the preparation of Mg _x Zn _1-x O thin films by double-target RF magnetron co-sputtering.

The present invention is achieved in this way, in the vacuum chamber of the radio frequency magnetron sputtering apparatus, by providing sputtering power, the sputtering gas sputters the target material fixed on the sputtering target, and _grows Mg _x Zn on the substrate _-x O thin film is characterized in that it is prepared by double-target co-sputtering, that is, the ZnO ceramic target and the MgO ceramic target are respectively fixed on the two sputtering targets, sputtering power is provided respectively, and sputtering is performed separately at the same time. Mg _x Zn _1-x O thin films were grown on the substrate.

The target materials adopted in the method of the present invention are ZnO ceramics and MgO ceramics respectively, which are respectively fixed on two sputtering targets, sputtering power is provided respectively, sputtering at the same time, and Mg _x Zn _1-x O thin films are grown on the same substrate , according to the different Mg _x Zn _1-x O films to be prepared, the sputtering power on the two sputtering targets can be determined. The sputtering power is different, and the quantity of sputtered ZnO and MgO is also different. Therefore, by Control the sputtering power, you can control the ratio of Zn ²⁺ and Mg ²⁺ in the Mg _x Zn _1-x O film, that is, the value of x, the sputtering power is continuously adjusted from 0 to 300w, and the value of x is from 0 to 1 Continuous regulation. Therefore, it is only necessary to make two kinds of targets, ZnO ceramics and MgO ceramics, and it is not necessary to make Mg _x Zn _1-x O ceramic targets according to the required Mg _x Zn _1-x O films. Therefore, the workload of target production obviously decrease. At the same time, these two targets are used regardless of the value of x to prepare the Mg _x Zn _1-x O thin film. When one of them is consumed due to the large amount of sputtering, it is only necessary to fix the other same target. Yes, therefore, the targets can be fully used. Furthermore, since the ratio of Zn ²⁺ and Mg ²⁺ in the prepared Mg _x Zn _1-x O film can be controlled by controlling the sputtering power, instead of letting the sputtering and growth proceed freely, the prepared Mg _x Zn 1-x O film Zn _1-x O thin films are closer to the desired results. Moreover, by adopting the method of the present invention, Mg _x Zn _1-x O thin films with wide composition can be obtained, and as the value of x ranges from 0 to 1, the prepared thin films are from ZnO to MgO through Mg _x Zn _1-x O.

Description of drawings

Fig. 1 is a flow chart of the preparation method of the Mg _x Zn _1-x O thin film of the present invention by double-target radio frequency magnetron co-sputtering, and this figure is also used as a summary drawing. Fig. 2 is a SEM (high resolution scanning electron microscope) image of a Mg _x Zn _1-x O thin film prepared by the method of the present invention.

Detailed ways

The method of the present invention will be described in detail below. In the vacuum chamber of the radio frequency magnetron sputtering apparatus, by providing sputtering power, the sputtering gas sputters the target fixed on the sputtering target, and grows Mg _x Zn _1-x O thin film on the substrate. A dual-target co-sputtering preparation method is adopted, that is, the ZnO ceramic target and the MgO ceramic target are respectively fixed on the two sputtering targets, sputtering power is provided separately, and sputtering is performed simultaneously. The specific steps are shown in Figure 1. Select ZnO and MgO raw materials with a purity greater than 99.99%. Place them in different ball mill jars in the ball mill, fully ball mill and granulate; then press the tablets in 2-inch abrasive tools respectively, with a pressure of 40Mpa, for 5min, and a thickness of 10mm; after sintering, grinding, polishing, and surface cleaning, The required ZnO ceramic target and MgO ceramic target are produced. Then, the ZnO ceramic target and the MgO ceramic target were respectively fixed on the sputtering target 1 and the sputtering target 2 in the vacuum chamber. The substrate is made of ZnO ceramics or MgO ceramics. As a photoelectric functional material, Mg _x Zn _1-x O film requires good orientation of the film, so the lattice between the substrate and the film is required to match, while ZnO ceramics or MgO ceramics and Mg _x Zn _1- The lattice of the _x O film is consistent, and choosing ZnO ceramics or MgO ceramics as the substrate can reduce the lattice mismatch between the film and the substrate. After cleaning, the substrate is placed on the sample stage in the vacuum chamber. Evacuate the vacuum chamber and maintain a vacuum degree of 5×10 ^-4 Pa. Argon and oxygen with a purity of 4N are introduced into the vacuum chamber at a pressure of 0.5 Pa, and the mixed gas formed in the vacuum chamber is the sputtering gas. During the sputtering process, according to the Mg _x Zn _1-x O film to be prepared, determine the x value in the range of 0≤x≤1, and control the sputtering power of sputtering target 1 and sputtering target 2 respectively according to the x value. A certain power value between 0 ~ 300w. The substrate temperature is controlled at a certain temperature between 20 and 600°C. After sputtering for 25-135 minutes, the film grows to a certain value within the range of 0.1-100 nm in film thickness. Anneal the prepared Mg _x Zn _1-x O film at a certain temperature within the range of 200-500°C for a certain time within the range of 6-12 hours to reduce the internal stress and defects in the film and further improve the crystal lattice of the film and tends to be consistent with the substrate.

A specific example is now given to illustrate the method of the present invention. Select ZnO and MgO raw materials with a purity greater than 99.99%. Place them in different ball mill jars in the ball mill, fully ball mill and granulate; then press the tablets in 2-inch abrasive tools respectively, with a pressure of 40Mpa, for 5min, and a thickness of 10mm; after sintering, grinding, polishing, and surface cleaning, Make the required ZnO ceramic target and MgO ceramic target. Then, the ZnO ceramic target and the MgO ceramic target were respectively fixed on the sputtering target 1 and the sputtering target 2 in the vacuum chamber. The substrate is another ZnO ceramic with a size of 20×20mm ² , which is cleaned after grinding and polishing. The cleaning process is as follows: ultrasonic cleaning with water containing detergent for 10 minutes; three times of cleaning with ethanol; repeated cleaning with deionized water for several times; drying in a drying oven. Place the substrate on the sample stage in the vacuum chamber. Evacuate the vacuum chamber and maintain a vacuum degree of 5×10 ^-4 Pa. Argon and oxygen with a purity of 4N are introduced into the vacuum chamber at a pressure of 0.5 Pa, and the mixed gas formed in the vacuum chamber is the sputtering gas. It is determined that x=0.5, and during the sputtering process, the sputtering powers of the sputtering target 1 and the sputtering target 2 are respectively controlled to 150w and 200w according to the value of x. The substrate temperature was controlled at 100°C and the rotation rate was 40%. After sputtering for 30 min, the film grows to a film thickness of 40 nm. The prepared Mg _0.5 Zn _0.5 O thin film was annealed at 300° C. for 6 hours. The prepared Mg _0.5 Zn _0.5 O film has uniform particle size distribution, as shown in FIG. 2 .

Claims (4)

1. A method for preparing a Mg _x Zn _1-x O thin film by double-target radio-frequency magnetron co-sputtering. In the vacuum chamber of a radio-frequency magnetron sputtering apparatus, by providing sputtering power, the sputtering gas is sputtered and fixed on the The target on the sputtering target grows a Mg _x Zn _1-x O thin film on the substrate, which is characterized in that it adopts a double-target co-sputtering preparation method, that is, the ZnO ceramic target and the MgO ceramic targets are provided with sputtering power respectively, and sputtered separately at the same time to grow Mg _x Zn _1-x O thin films on the substrate. 2. The preparation method of double-target radio-frequency magnetron co-sputtering according to claim 1, characterized in that ZnO ceramics or MgO ceramics are selected as the substrate. 3. The preparation method of double-target RF magnetron co-sputtering according to claim 1, characterized in that, in the sputtering process, according to the required Mg _x Zn _1-x O thin film, in the range of 0≤x≤1 The x value is determined, and the sputtering power of the sputtering target 1 and the sputtering target 2 are respectively controlled at a certain power value between 0 and 300w according to the x value. 4. The preparation method of double-target RF magnetron co-sputtering according to claim 1, characterized in that, the substrate temperature is controlled at a certain temperature between 20-600°C; the sputtering is 25-135min; the film grows to a film The thickness is a certain value within the range of 0.1 to 100 nm.

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