CN113013250B - Field effect transistor and preparation method thereof - Google Patents

Abstract

The invention discloses a field effect transistor and a preparation method thereof, belonging to the field of microelectronic devices. The field effect transistor includes a substrate, a gate electrode, a metal-insulating layer dielectric, an active layer and source/drain electrodes, the gate electrode is located on the substrate, the metal-insulating layer dielectric is located on the gate electrode, and the active layer is located on the metal On the insulating layer dielectric, the source/drain electrodes are located on the active layer, the metal-insulating layer dielectric structure adopts a sandwich structure of aluminum oxide/titanium/alumina, and the thickness of the aluminum oxide film is 10-100 nanometers respectively , the titanium film is a metal titanium film or a titanium oxide film, and the thickness of the titanium film is 10-100 nanometers. The present invention proposes a novel high-k dielectric material for microelectronic devices. The metal-insulating layer hybrid dielectric is prepared by magnetron sputtering and atomic layer deposition processes, with simple steps, low cost and practical application potential.

Description

Field-effect transistor and method of making the same

technical field

The invention belongs to the field of integrated circuit micro-nano electronic devices, in particular to a field effect transistor and a preparation method thereof.

Background technique

Integrated circuits are the cornerstone of modern information technology and have played a very important role in all walks of life. The demand for integrated circuits in my country is very huge, and the annual import volume in 2020 is as high as 351.5 billion US dollars. Recently, my country has increased investment in the integrated circuit industry, related technologies have made great progress, and innovation capabilities have continued to improve. However, there are still problems such as insufficient technical level and low-end products as a whole.

Micro-nano electronic devices are the basis of integrated circuits, among which the most representative device is metal oxide semiconductor field-effect transistor (MOSFET). In order to better reduce the leakage current of MOSFET devices and thereby improve the circuit integration, an important research direction is to enhance the control ability of the MOSFET gate dielectric on the channel carriers, that is, the gate control ability. There are two main technical paths to enhance the gate control capability: (1) use high-k dielectric materials to replace _SiO2 dielectric; (2) use three-dimensional structures to increase the gate control area of MOSFET devices, such as fin field-effect transistors (fin field-effect transistors) transistor, FinFET). The combination of the above two technical routes can further improve the gate control capability of the MOSFET. In addition, devices such as nanosheet transistors, nanowire transistors, and negative capacitance transistors proposed in recent years can be regarded as extensions of the above two technical routes. However, in terms of integrated circuit manufacturing process, my country has few core patents on the above-mentioned technologies. Therefore, the proposal and research and development of original technologies for gate dielectric materials and structures have very important research value, and are of great significance to the development of integrated circuit technology in my country.

The widely used high-k dielectric materials are usually transition metal oxides, such as hafnium oxide (HfO ₂ ), zirconium oxide (ZrO ₂ ), titanium oxide (TiO ₂ ), and the like. Among them, hafnium oxide dielectric technology is highly mature, and Intel's 45nm process has commercialized this technology. The dielectric constant of titanium oxide (k=80-110) is much higher than that of hafnium oxide (k=20-25) and zirconium oxide (k=20-30). However, the dielectric constant is inversely related to the width of the bandgap, and a reduction in the width of the bandgap can degrade device reliability. Oxygen defects and grain boundaries are formed during the preparation of titanium oxide dielectrics, which seriously affect the device performance, which is manifested as a decrease in carrier mobility. In addition, the poor quality of the high-k dielectric/Si active layer interface compared to the _SiO2 dielectric/Si active layer interface can also adversely affect device performance. Therefore, innovative research on titanium-based gate dielectric materials and structures and related patent applications are of great value to the future development of my country's integrated circuits.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a field effect transistor and a preparation method thereof. The invention adopts a metal-insulating layer mixed dielectric with a novel sandwich structure, and the metal-insulating layer mixed dielectric adopts the structure of aluminum oxide/titanium/alumina.

The technical solution of the present invention is,

The invention provides a field effect transistor, which is characterized by comprising a substrate, a gate electrode, a metal-insulating layer dielectric, an active layer and source/drain electrodes, the gate electrode is located on the substrate, and the metal-insulating layer dielectric is located on the gate Above the electrode, the active layer is located on the metal-insulating layer dielectric, the source/drain electrodes are located on the active layer, the metal-insulating layer dielectric structure adopts a sandwich structure of aluminum oxide/titanium/alumina, and the oxide The thickness of the aluminum film is respectively 10-100 nanometers, the titanium film is a metal titanium film or a titanium oxide film, and the thickness of the titanium film is 10-100 nanometers.

The gate electrode is a combination of one or more of metals such as Al, Ti, and Mo, or a combination of one or more of conductive thin films such as ITO and AZO, and the thickness of the gate electrode is 100-500 nanometers. .

The thickness of the metal-insulating layer hybrid dielectric is 30-300 nanometers.

The active layer is zinc oxide or doped zinc oxide thin film, and the thickness of the active layer is 10-100 nanometers. For doped zinc oxide, the doping elements are metal elements such as aluminum, tin, molybdenum, and titanium, inorganic non-metallic elements such as silicon, carbon, and phosphorus, or one or a combination of rare earth elements such as lanthanum and erbium. The content of the doping element in the doped zinc oxide film is: 0.1%-20% of the doping element.

The source/drain electrode is a combination of one or more of metals such as Al, Ti, and Mo, or a combination of one or more of conductive thin films such as ITO and AZO, and the thickness of the source/drain electrode is 100 mm. -500 nm.

At the same time, the present invention provides a preparation method of a field effect transistor. Specific steps are as follows:

(1) The substrate is placed in acetone, ethanol, and deionized water for ultrasonic cleaning;

(2) A magnetron sputtering process is used to deposit a gate electrode on the surface of the substrate;

(3) using magnetron sputtering process and atomic layer electrode process to deposit metal-insulating layer dielectric on the gate electrode;

(4) using atomic layer deposition process or magnetron sputtering process to deposit an active layer on the metal-insulating layer dielectric;

(5) using magnetron sputtering process to deposit source/drain electrodes on the active layer;

(6) An annealing process is used to optimize the treatment of the field effect transistor.

Wherein, the specific preparation process of the metal-insulating layer dielectric in step (3) includes the following steps:

(a) the substrate is fixed in the reaction chamber of the atomic layer deposition equipment;

(b) pumping the air pressure at the back of the reaction chamber to 50-100 Pa;

(c) feed nitrogen into the reaction chamber, and the reaction temperature is set to 100-200°C;

(d) feeding the reaction source into the reaction chamber, and starting to deposit the bottom insulating layer, the reaction source is trimethyl aluminum and deionized water (H ₂ O);

(e) After the deposition of the insulating layer (bottom layer) of the aluminum oxide film is completed, the atomic layer deposition equipment is closed;

(f) fixing the substrate with the insulating layer on the surface to the magnetron sputtering equipment tray;

(g) The air pressure at the back of the cavity of the magnetron sputtering equipment is pumped to 1×10 ^-4 -9×10 ^-4 Pa;

(h) Pour oxygen and argon into the magnetron sputtering equipment cavity, adjust the air pressure control valve, and set the cavity air pressure to 1 Pa;

(i) Turn on the tray rotation button, and set the rotation speed to 10-15 rpm;

(j) turn on the power supply, pre-sputter for 2-5 minutes, and the sputtering target used in the magnetron sputtering process is a titanium metal target;

(1) Rotate the magnetron sputtering target baffle plate to formally sputter for 20-30 minutes;

(m) After the deposition of the titanium film is completed, turn off the radio frequency power supply and turn off the instrument;

(n) Repeat steps (a)-(e) to deposit another aluminum oxide thin film insulating layer (top layer).

Advantages of the present invention:

(1) The present invention proposes a new type of high-k dielectric material for microelectronic devices, which is highly original and provides technical support for the development of integrated circuits in my country. (2) The metal-insulating layer hybrid dielectric prepared by the present invention is prepared by magnetron sputtering and atomic layer deposition, with simple steps and low cost. (3) The field effect transistor of the present invention has excellent performance and has practical application potential.

Description of drawings

1 is a schematic structural diagram of a field effect transistor prepared by the present invention;

2 is a schematic structural diagram of the metal-insulating layer hybrid dielectric of the present invention;

Fig. 3 is the electric current-voltage characteristic of the field effect transistor prepared by the present invention;

1-substrate; 2-gate electrode; 3-metal-insulating layer dielectric; 4-active layer; 5-source/drain electrode; 6-alumina film; 7-titanium film.

Detailed ways

The present invention will be further described by examples below in conjunction with the accompanying drawings. It should be noted that the purpose of publishing the embodiments is to help further understanding of the present invention, but those skilled in the art can understand that various replacements and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. possible. Therefore, the present invention should not be limited to the contents disclosed in the embodiments, and the scope of protection of the present invention shall be subject to the scope defined by the claims.

The field effect transistor of the present invention shown in FIG. 1 includes a substrate, a gate electrode, a metal-insulating layer dielectric, an active layer and a source/drain electrode, the gate electrode is located on the substrate, and the metal-insulating layer dielectric is located on the gate electrode. , the active layer is located on the metal-insulating layer dielectric, and the source/drain electrodes are located on the active layer.

In the metal-insulating layer hybrid dielectric structure shown in FIG. 2, the titanium film is located between two aluminum oxide films in a sandwich structure. The thickness of the aluminum oxide film is respectively 10-100 nanometers, the titanium film is a metal titanium film or a titanium oxide film, and the thickness of the titanium film is 10-100 nanometers.

The active layer of the field effect transistor of the present invention takes zinc oxide as an example, and the specific preparation process includes the following steps:

(1) The glass substrate was sequentially placed in acetone, ethanol and deionized water for ultrasonic cleaning, and the cleaning time was 5 minutes.

(2) The magnetron sputtering process deposits a metal aluminum film on the glass substrate, and the thickness of the aluminum film is 100 nm; the aluminum gate electrode pattern is formed by photolithography and etching process.

(3) depositing a metal-insulating layer hybrid dielectric on the gate electrode; using photolithography and etching processes to form a metal-insulating layer hybrid dielectric pattern.

(4) The magnetron sputtering process deposits a zinc oxide film on the metal-insulating layer mixed dielectric, and the zinc oxide film has a thickness of 30 nm; photolithography and etching processes are used to form the zinc oxide active layer pattern.

(5) Magnetron sputtering process depositing a metal aluminum film on the zinc oxide active layer, the thickness of the aluminum film being 100 nm; using photolithography and etching processes to form aluminum source/drain electrode patterns.

(6) An annealing furnace is used to optimize the transistor, the annealing temperature is 300° C., the annealing time is 1 hour, and the annealing atmosphere is vacuum.

Wherein, the specific steps of the metal-insulating layer hybrid dielectric proposed by the present invention are:

(1) Fix the glass substrate in the reaction chamber of the atomic layer deposition equipment.

(2) The air pressure at the back of the reaction chamber of the atomic layer deposition equipment was pumped to 70 Pa.

(3) Nitrogen gas was introduced into the reaction chamber of the atomic layer deposition equipment, and the reaction temperature was set to 150°C.

(4) The reaction chamber of the atomic layer deposition equipment is connected to the reaction source, and the deposition of the aluminum oxide film begins. The reaction sources used were trimethylaluminum and deionized water ( _H2O ). During the reaction, the number of cycles of trimethylaluminum and deionized water (H ₂ O) was 50 times.

(5) After the deposition of the insulating layer (bottom) of the aluminum oxide film is completed, the atomic layer deposition equipment is closed.

(6) Fix the substrate with the insulating layer (bottom) on the surface of the magnetron sputtering equipment tray.

(7) The air pressure at the back of the chamber of the magnetron sputtering equipment was pumped to 5 × 10 ^-4 Pa.

(8) The cavity of the magnetron sputtering equipment is fed with oxygen and argon, and the flow ratio of oxygen and argon is 10:90. Adjust the air pressure control valve to set the chamber air pressure to 1 Pa.

(9) Turn on the tray rotation button, and set the rotation speed to 15 rpm.

(10) Turn on the power and pre-sputter for 2 minutes. The sputtering target used in the magnetron sputtering process is a metallic titanium target.

(11) Rotate the magnetron sputtering target baffle plate, and formally sputter for 30 minutes.

(12) After the deposition of the titanium film is completed, turn off the RF power supply and turn off the instrument.

(13) Repeat steps (1)-(5) to deposit an aluminum oxide thin film insulating layer (top).

The current-voltage characteristics of the field effect transistor prepared by the present invention are shown in FIG. 3 , the device shows good transfer characteristics, and the field effect mobility is >25cm ² V ^-1 s ^-1 .

Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art, without departing from the scope of the technical solution of the present invention, can make many possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above, or modify it into an equivalent implementation of equivalent changes. example. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solutions of the present invention still fall within the protection scope of the technical solutions of the present invention.

Claims (8)

1. a field effect transistor, is characterized in that, comprises substrate, gate electrode, metal-insulating layer dielectric, active layer and source/drain electrode, gate electrode is positioned on the substrate, and metal-insulating layer dielectric is positioned at gate electrode Above, the active layer is located on the metal-insulating layer dielectric, the source/drain electrodes are located on the active layer, the metal-insulating layer dielectric structure adopts a sandwich structure of aluminum oxide/titanium/alumina, and the aluminum oxide The thickness of the film is 10-100 nanometers respectively, the titanium film is a metal titanium film or a titanium oxide film, and the thickness of the titanium film is 10-100 nanometers. 2. field effect transistor as claimed in claim 1 is characterized in that, described gate electrode is the combination of one or more in Al, Ti, Mo metal, or one in transparent conductive film ITO, AZO conductive film One or more combinations, the thickness of the gate electrode is 100-500 nanometers. 3 . The field effect transistor according to claim 1 , wherein the active layer is a zinc oxide or doped zinc oxide film, and the thickness of the active layer is 10-100 nanometers. 4 . 4 . The field effect transistor according to claim 3 , wherein the doped zinc oxide is composed of aluminum, tin, molybdenum, titanium metal elements, silicon, carbon, phosphorus inorganic non-metallic elements, or lanthanum. 5 . , one or a combination of erbium rare earth elements. 5 . The field effect transistor according to claim 4 , wherein the content of the doping element in the doped zinc oxide film is: 0.1%-20% of the doping element. 6 . 6. field effect transistor as claimed in claim 1 is characterized in that, source/drain electrode is the combination of one or more in Al, Ti, Mo metal, or a kind of in transparent conductive film ITO, AZO conductive film or a combination of more than one, the thickness of the source/drain electrodes is 100-500 nanometers. 7. The preparation method of field effect transistor as claimed in claim 1, its steps are as follows: (1) The substrate is placed in acetone, ethanol, and deionized water for ultrasonic cleaning; (2) A magnetron sputtering process is used to deposit a gate electrode on the surface of the substrate; (3) using magnetron sputtering process and atomic layer electrode process to deposit metal-insulating layer mixed dielectric on the gate electrode; (4) using atomic layer deposition process or magnetron sputtering process to deposit an active layer on the metal-insulating layer mixed dielectric; (5) using magnetron sputtering process to deposit source/drain electrodes on the active layer; (6) An annealing process is used to optimize the treatment of the field effect transistor. 8. preparation method as claimed in claim 7 is characterized in that, step (3) concrete steps comprise: (a) the substrate is fixed in the reaction chamber of the atomic layer deposition equipment; (b) pumping the air pressure at the back of the reaction chamber to 50-100 Pa; (c) feed nitrogen into the reaction chamber, and the reaction temperature is set to 100-200°C; (d) feeding the reaction source into the reaction chamber, and starting to deposit the bottom insulating layer, the reaction source is trimethyl aluminum and deionized water (H ₂ O); (e) After the deposition of the insulating layer of the aluminum oxide film is completed, the atomic layer deposition equipment is closed; (f) fixing the substrate with the insulating layer on the surface to the magnetron sputtering equipment tray; (g) The air pressure at the back of the cavity of the magnetron sputtering equipment is pumped to 1×10 ^-4 -9×10 ^-4 Pa; (h) Pour oxygen and argon into the magnetron sputtering equipment cavity, adjust the air pressure control valve, and set the cavity air pressure to 1 Pa; (i) Turn on the tray rotation button, and set the rotation speed to 10-15 rpm; (j) turn on the power supply, pre-sputter for 2-5 minutes, and the sputtering target used in the magnetron sputtering process is a titanium metal target; (1) Rotate the magnetron sputtering target baffle plate to formally sputter for 20-30 minutes; (m) After the deposition of the titanium film is completed, turn off the radio frequency power supply and turn off the instrument; (n) Repeat steps (a)-(e) to deposit another aluminum oxide thin film insulating layer.

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