CN113088902A

CN113088902A - Process method for preparing single-phase high manganese silicon film under raw material oxidation condition

Info

Publication number: CN113088902A
Application number: CN202110390892.0A
Authority: CN
Inventors: 张晋敏; 潘王衡; 谢泉; 肖清泉; 王勤; 冯磊; 谢杰
Original assignee: Guizhou University
Current assignee: Guizhou University
Priority date: 2021-04-12
Filing date: 2021-04-12
Publication date: 2021-07-09
Anticipated expiration: 2041-04-12
Also published as: CN113088902B

Abstract

The invention discloses a process method for preparing a single-phase high manganese-silicon film under the condition of raw material oxidation, which comprises the following steps: mn target material containing MnO is used as raw material, a film is prepared on a Si substrate by a magnetron sputtering method, and a three-layer structure sample of the Si substrate, the Si film and the Mn film containing oxide is formed, and then high-temperature annealing is carried out under a vacuum condition. Based on the process method, by controlling the sputtering time of the Si film middle layer in the three-layer structure of the Si substrate, the Si film and the Mn film containing oxides, MnO with large content ratio can be completely eliminated, the high manganese silicon film material with a single phase is obtained, the requirements of the obtained high manganese silicon film on raw materials, storage and process conditions are obviously reduced, the preparation of the high manganese silicon film is simpler, the industrial production cost is reduced, and the production efficiency is improved.

Description

Process method for preparing single-phase high manganese silicon film under raw material oxidation condition

Technical Field

The invention relates to a process method for preparing a single-phase high manganese-silicon film under the condition of raw material oxidation, belonging to the technical field of high manganese-silicon semiconductor preparation processes.

Background

The high manganese silicon is an environment-friendly semiconductor material, has multiple advantages, has great application potential in the thermoelectric and photoelectric fields, and can be used for constructing practical devices such as infrared detectors, photoelectric relays, photodiodes, photoresistors and the like; the common preparation process of the high manganese silicon film is to plate a layer of manganese film on a silicon substrate by means of magnetron sputtering and the like, and then to carry out high-temperature heat treatment under the vacuum condition, so as to prepare the high manganese silicon film;

magnetron sputtering is a common way to prepare uniform thin films, and the basic principle is as follows: bombarding the surface of the target material by using high-energy ions, so that substances on the surface of the target material are sputtered, and limiting the movement direction of particles by a magnetic field to finally attach to the surface of the substrate; the method needs to use a magnetron sputtering target material, wherein the manganese metal target material is mainly used; mn (manganese) is an active metal and is easily oxidized in air, and under the condition of common equipment, the raw materials cannot be prevented from contacting with air, so that the reaction raw materials contain manganese oxide, and under the condition of short-term oxidation, the oxide is mainly MnO; the equipment integrated with the glove box has high cost, the occupied area can be further improved, and the time required for vacuumizing can be obviously increased due to the increase of the volume of the vacuum cavity;

the difficulty of Mn purification is high, and the process difficulty is further increased when the Mn is prepared into the target material for magnetron sputtering. Compared with various targets on the market, the purity of other metals is 4N (99.99%), the highest purity of Mn available in domestic markets is only 3N5 (99.95%), most manufacturers can only provide products with the purity of 3N (99.9%) or less, and products produced by a large number of manufacturers are accompanied by oxide due to process and storage problems and mainly comprise MnO;

when MnO exists in the raw materials, a large amount of MnO exists in the product prepared by using the conventional high manganese silicon preparation process, so that the purity of the product is obviously influenced, and the performance of a semiconductor device constructed by the material is further influenced;

therefore, under the conditions that the purity of the raw materials is difficult to meet the requirement and the process has strict requirements on instrument conditions, how to solve the problem of MnO in the process of preparing high manganese silicon is very important.

Disclosure of Invention

In order to solve the technical problems, the invention provides a process method for preparing a single-phase high manganese silicon film under the condition of raw material oxidation.

The invention is realized by the following technical scheme.

The invention provides a process method for preparing a single-phase high manganese silicon film under the condition of raw material oxidation, which comprises the following steps:

mounting a cleaned Si substrate on a sample rack of a high-vacuum magnetron sputtering system for fixing, and respectively mounting a Si target and a Mn target on a radio-frequency sputtering target position and a direct-current sputtering target position in an instrument as substrates for coating;

step two, filling Ar gas medium: vacuumizing the cavity of the high-vacuum magnetron sputtering system when the background vacuum degree is better than 5 multiplied by 10^-4After Pa, continuously introducing high-purity Ar gas with the gas flow of 40sccm from the vent hole to ensure that the air pressure in the cavity reaches 2.0Pa and keeps stable;

depositing a Si film on the Si substrate: removing a target baffle plate blocked on the Si target, starting a radio frequency sputtering power supply of the target, sputtering and glowing the Si target after the radio frequency sputtering power supply is successfully matched with the radio frequency, removing a sample baffle plate for blocking the Si substrate after pre-sputtering for a period of time, depositing Si simple substance sputtered from the Si target on the Si substrate to form a Si film, operating the sample baffle plate to block the Si substrate plated with the Si film after film coating is finished, closing the radio frequency sputtering power supply of the Si target, and then moving the target baffle plate of the Si target to block the Si target;

step four, depositing a Mn film on the Si substrate plated with the Si film: moving a target baffle for blocking the Mn target material away and starting a direct current sputtering power supply of the target position, sputtering the Mn target material to glow, moving a sample baffle for blocking the Si substrate away after pre-sputtering for a period of time so that substances on the Mn target material are deposited on the surface of the Si film to form a Mn film, forming a three-layer structure sample of the Si substrate, the Si film and the Mn film containing oxides, blocking the sample by the sample baffle after sputtering is finished, then closing the direct current sputtering power supply, and blocking the Mn target material by the target baffle of the Mn target position;

step five, annealing: placing the three-layer structure sample obtained by the steps in a vacuum annealing furnace, and pumping until the background vacuum degree is superior to 5 multiplied by 10^-4And after Pa, starting a heating power supply to heat the three-layer structure sample, heating to 700 ℃, keeping the temperature constant for a period of time, cooling to the normal temperature along with the furnace, removing MnO contained in the Mn film, and obtaining the single-phase high manganese silicon film.

In the first step, the purity of the Si target is 5N or more; mn targets are nominally 3N and above pure, but there is a significant amount of native oxide MnO.

In the third step, the radio frequency sputtering power is 80W, the deposition time of the Si film is 35min, and the parameters need to be adjusted when the sputtering parameters of the Mn film and the MnO content are changed.

In the fourth step, since the Mn target contains oxide MnO, MnO which may be contained in the Mn thin film obtained by sputtering using the target is also present.

In the fourth step, the direct current sputtering power is 110W, and the deposition time of the Mn thin film is 5 min.

In the fourth step, a sample of a three-layer structure of "Si substrate-Si thin film-Mn thin film containing oxide" was formed by adding a Si thin film as an intermediate layer between the two-layer structure of "Si substrate-Mn thin film containing oxide".

In the fifth step, the three-layer structure sample of the Si substrate-Si film-Mn film containing oxide is heated at the heating rate of 12 ℃/min, the temperature is kept for 4h after the sample is heated to 700 ℃, then the heating is stopped, and the sample is cooled to the normal temperature along with the furnace under the vacuum condition.

The invention has the following beneficial effects:

(1) the requirements for raw materials and experimental instruments are not strict any more. In the original situation, the raw material needs to be discarded once being oxidized, and the discarded raw material can be used for preparing a single original target product, namely high manganese silicon.

(2) The prior art always considers that the high manganese silicon is obtained by the reaction between a simple substance Mn and a simple substance Si, and the basic physical idea of the scheme is that MnO can react with Si to generate the high manganese silicon, so that a new reaction path is added to the preparation process of the high manganese silicon.

(3) The consideration of this parameter of the distribution density of Si atoms is increased. The reaction rate and the number of Si atoms used for reaction can be regulated and controlled by changing the thickness of the Si film intermediate layer in the three-layer structure of the Si substrate, the Si film and the Mn film containing the oxide.

Drawings

FIG. 1 is an XRD pattern of the material produced without the addition of an intermediate layer of Si;

FIG. 2 is an XRD pattern of the material obtained in the examples herein;

FIG. 3 is an XRD pattern of the material obtained by controlling the sputtering time of different Si intermediate layers.

Detailed Description

To more clearly describe the technical solution of the present invention, the embodiment is further specifically described with reference to the accompanying drawings, but the scope of the claimed invention is not limited to the description.

The invention relates to a process method for preparing a single-phase high manganese silicon film under the condition of raw material oxidation, which comprises the following steps:

step one, mounting a substrate and a target material: sequentially ultrasonically cleaning a high-resistance Si substrate sample with a crystal orientation of <100> in acetone, absolute ethyl alcohol and deionized water for 20min respectively to remove surface impurities, mounting the cleaned Si substrate on a sample rack of a high-vacuum magnetron sputtering system for fixing as a substrate for coating, and respectively mounting a Si target and a Mn target on a radio-frequency sputtering target and a direct-current sputtering target in an instrument; the Si target has a purity of 5N or more; mn targets are nominally 3N and above pure, but there is a significant amount of native oxide MnO;

step two, filling Ar gas medium: vacuumizing the cavity of the high-vacuum magnetron sputtering system until the background vacuum degree reaches at least 5 multiplied by 10^-4After Pa, continuously introducing high-purity Ar gas with the gas flow of 40sccm from the vent hole to ensure that the air pressure in the cavity reaches 2.0Pa and keeps stable;

depositing a Si film on the Si substrate: removing a target baffle plate blocked on the Si target, starting a radio frequency sputtering power supply of the target position, sputtering and glowing the Si target after the radio frequency sputtering power supply is successfully matched in radio frequency, moving a sample baffle plate for blocking the Si substrate sample after pre-sputtering for 30min, so that Si atoms sputtered from the Si target deposit on the Si substrate to form a Si film, wherein the sputtering power is 80w, the film coating time is 35min, operating the sample baffle plate to block the Si substrate plated with the Si film after the film coating is finished, closing the radio frequency sputtering power supply of the Si target position, and then moving the target baffle plate of the Si target position to block the Si target;

step four, depositing a Mn film on the Si substrate plated with the Si film: removing a target baffle for blocking the Mn target material, starting a direct-current sputtering power supply of a high-vacuum magnetron sputtering system, sputtering the Mn target material to glow, removing a sample baffle for blocking the Si substrate after pre-sputtering for 30min, so that atoms on the Mn target material are deposited on the surface of the Si film to form the Mn film, wherein the sputtering power is 110w, the sputtering time is 5min, and because the Mn target material contains oxide MnO, the Mn film obtained by sputtering the Mn target material also contains MnO in the same proportion as the MnO, so that a three-layer structure sample of 'Si substrate-Si film-Mn film containing oxide' is formed, after the sputtering is finished, blocking the sample by using the sample baffle, then closing the direct-current sputtering power supply, and blocking the Mn target material by using the target baffle of Mn target position;

step five, annealing: pumping the cavity to background vacuum degree superior to 5 × 10^-4After Pa, starting an in-situ heating power supply of the high-vacuum magnetron sputtering system, heating a three-layer structure sample of a Si substrate, a Si film and an oxide-containing Mn film by using a heating plate arranged in a sample rack, wherein the heating rate is 12 ℃/min, the temperature is kept constant for 4h after the temperature is raised to 700 ℃, and then the vacuum condition is kept to ensure that the sample is subjected to vacuum treatmentWhen the temperature is cooled to normal temperature along with the furnace, MnO contained in the Mn film can be removed, and a single-phase high manganese silicon film is obtained, as shown in figure 2.

In the invention, the basic principle of solving the problem of raw material oxidation by adding the Si intermediate layer is that MnO reacts with Si, and high manganese silicon can be obtained by reaction under the process condition. In addition, the distribution density of Si atoms also has a significant influence on the reaction process. It can be noted that the original reaction object of the Mn thin film is the Si substrate, and the material composition of the Si intermediate layer introduced in the present invention is substantially the same as that of the Si substrate, and is a Si simple substance. The main difference is that the density of the Si intermediate layer is different from that of the Si substrate: the Si intermediate layer obtained by magnetron sputtering has low density, and the Si substrate is prepared by smelting, and the density of the Si intermediate layer is obviously higher than that of the Si intermediate layer. This results in a lower density of the Si intermediate layer, a loose atomic distribution, and a greater tendency to interpenetrate with the Mn film, which is equivalent to a reaction between the mixture of Si and Mn; the Si substrate has high density and too tight atomic distribution, so that the Si substrate is difficult to mutually permeate with the Mn film, and the reaction mainly occurs at the junction of the Mn film and the Si substrate. Since the resulting material is relatively stable, further reaction is difficult and the product accumulates at the interface. Further, since the Si atom density of the Si substrate is high, the density of the generated substance is also high. A high-density spacer layer is formed at the interface, which hinders the reaction between the Mn thin film and the Si substrate.

By the method of adding the Si intermediate layer, the reaction at the interface of the Si substrate and the surface thin film can be relatively moderated. The Mn film firstly permeates and reacts with the Si intermediate layer, the Si substrate provides enough Si atoms for the film when the Si atoms are insufficient, and the influence of the Si substrate is reduced along with the increase of the thickness of the Si intermediate layer. By changing the thickness of the Si intermediate layer, the reaction rate and the number of Si atoms used for the reaction can be regulated.

In the third step, preferably, the radio frequency sputtering power of the high vacuum magnetron sputtering system is 80W, the deposition time of the Si film is 35min, and as can be seen from fig. 3, when the deposition time is more than 0 and less than or equal to 25min, the MnO peak gradually decreases, the MnO content in the high manganese silicon decreases, and the high manganese silicon content increases; when the deposition time is 35min, the MnO peak almost completely disappears, and the MnO content in the high manganese silicon is lowest; when the deposition time reaches 45min, the MnO peak is increased again, and the MnO content in the high manganese silicon is increased. This indicates that the sputtering time of the Si interlayer is not as long as possible but there is a proper value, which is 35min in this embodiment. When the sputtering parameters of the Mn film and the MnO content are changed, the sputtering parameters of the Si intermediate layer need to be adjusted.

Figure 1 is an XRD pattern of the material prepared without the addition of an Si interlayer.

As is clear from FIG. 1, when the Si intermediate layer is not added, Mn can be obtained if the Mn target material as the raw material is not oxidized₂₇Si₄₇Single phase product, Mn₂₇Si₄₇Is a typical phase of high manganese silicon; when the Mn target material contains oxide MnO, the product can contain remarkable MnO, and the peak value of the MnO is even more than that of the target product Mn₂₇Si₄₇Yet high, and therefore, oxidation of the feedstock can significantly affect the purity of the product.

Figure 2 is an XRD pattern of the material obtained by an example of the inventive technique herein.

The raw materials and the process were the same as those in the case of the Mn target material containing the oxide MnO in fig. 1 except that the Si intermediate layer was added, and the results obtained by this example are shown in fig. 2, compared with the results in fig. 1 when the raw material was oxidized. It can be seen that a single phase of high manganese silicon can be obtained by this example, and MnO is almost completely eliminated, which proves that this scheme can well perform the function of eliminating oxides and the product is unique.

To further demonstrate the effect of adding the Si interlayer, XRD patterns of the obtained materials were compared with each other with sputtering time of the Si interlayer as a variable, and the results are shown in fig. 3. It can be seen that the MnO peak is obviously reduced after the Si intermediate layer is added, the main peak of the high manganese silicon is obviously increased, preferred orientation is presented, when the sputtering deposition time of the Si intermediate layer reaches 35min, the MnO peak almost completely disappears, and simultaneously, the peak values of all peak positions of the high manganese silicon are uniformly distributed and are consistent with the standard map. However, when the sputtering time of the Si intermediate layer was further increased to 45min, the MnO peak reappeared and the peak values of the high manganese silicon were reduced.

Claims

1. A process method for preparing a single-phase high manganese silicon film under the condition of raw material oxidation is characterized by comprising the following steps:

step five, annealing: will be obtained through the stepsThe obtained three-layer structure sample is placed in a vacuum annealing furnace and is pumped until the background vacuum degree is superior to 5 multiplied by 10^-4And after Pa, starting a heating power supply to heat the three-layer structure sample, heating to 700 ℃, keeping the temperature constant for a period of time, cooling to the normal temperature along with the furnace, removing MnO contained in the Mn film, and obtaining the single-phase high manganese silicon film.

2. The process for preparing single-phase high-manganese silicon thin film under raw material oxidation condition as claimed in claim 1, characterized in that: in the first step, the purity of the Si target is 5N or more; mn targets are nominally 3N and above pure, but there is a significant amount of native oxide MnO.

3. The process for preparing single-phase high-manganese silicon thin film under raw material oxidation condition as claimed in claim 1, characterized in that: in the third step, the radio frequency sputtering power is 80W, and the deposition time of the Si film is 35 min.

4. The process for preparing single-phase high-manganese silicon thin film under raw material oxidation condition as claimed in claim 1, characterized in that: in the fourth step, since the Mn target contains oxide MnO, the Mn thin film sputtered using the target also contains MnO present therein.

5. The process for preparing single-phase high-manganese silicon thin film under raw material oxidation condition as claimed in claim 1, characterized in that: in the fourth step, the direct current sputtering power is 110W, and the deposition time of the Mn thin film is 5 min.

6. The process for preparing single-phase high-manganese silicon thin film under raw material oxidation condition as claimed in claim 1, characterized in that: in the fourth step, a sample of a three-layer structure of "Si substrate-Si thin film-Mn thin film containing oxide" was formed by adding a Si thin film as an intermediate layer between the two-layer structure of "Si substrate-Mn thin film containing oxide".

7. The process for preparing single-phase high-manganese silicon thin film under raw material oxidation condition as claimed in claim 1, characterized in that: in the fifth step, the three-layer structure sample of the Si substrate-Si film-Mn film containing oxide is heated at the heating rate of 12 ℃/min, the temperature is kept for 4h after the sample is heated to 700 ℃, then the heating is stopped, and the sample is cooled to the normal temperature along with the furnace under the vacuum condition.