CN100420033C - Field effect transistor and method of manufacturing the same - Google Patents

Abstract

A field effect transistor, which includes a semiconductor layer of a first conductivity type; a source region of a second conductivity type and a drain region of a second conductivity type are respectively formed on the semiconductor layer, the source region and the drain The electrode regions are separated by a certain distance; an insulating oxide layer is formed on the above-mentioned semiconductor layer, and is located between the above-mentioned source region and the drain region; a source electrode, a drain electrode and a gate electrode are respectively formed on the above-mentioned source region . The drain region and the insulating oxide layer, wherein the semiconductor layer is a semiconducting carbon nanotube layer.

Description

Field effect transistor and method of manufacturing the same

【Technical field】

The invention relates to a field effect transistor, in particular to a carbon nanotube-based field effect transistor and a manufacturing method thereof.

【Background technique】

Since the birth of the first IC (Integrated Circuit), the R&D and manufacturing of microprocessor products based on silicon devices has been developing at a rapid rate of doubling the number of transistors every 18 months under Moore's Law. By 2002, microprocessors contained 76 million transistors and were capable of very powerful functions. However, the scientific community generally believes that Moore's Law will not be valid forever, 50 nanometers is the limit of modern semiconductor technology, and Intel's latest technology is 0.13 microns, that is, the silicon limit will be reached within 10 to 15 years.

The basis of silicon devices is a crystal composed of silicon atoms. The discontinuous energy levels of silicon atoms in the crystal constitute the energy band, and the electrons in the semiconductor move in the energy band. The energy band is much larger than the energy of the energy level of the silicon atom, and it will cause electrons to escape from the specific energy level of the atom. If the size of the transistors on a silicon chip is very small, the escape of electrons due to the energy band can cause severe leakage between adjacent transistors, making the electronic switch unable to "turn off". In addition, the small size of the transistor will also cause great difficulties in heat dissipation. These physical challenges will make increasing the integration of silicon devices increasingly expensive.

Since Ijima discovered carbon nanotubes in 1991 (see Nature, 1991, 354, 56 for details), in 1998, IBM and NEC successfully used a semiconducting carbon nanotube to make a field effect transistor (see Applied Physics Letters for details) , 1998, 73, 2447), which opened the prelude to replace silicon devices with carbon devices. The transistor based on a carbon nanotube exhibits good electrical performance. When the gate voltage changes, the conductance between the source and the drain changes by 100,000 times. Due to the very small size of carbon nanotubes, it is predicted that if devices made of carbon nanotubes are used, the density of transistors can be 60,000 times higher than that of the most advanced 0.13 micron silicon devices.

However, the above-mentioned field effect transistor prepared with a single carbon nanotube requires a special preparation process, such as using an atomic force microscope (AFM, Atom Force Microscope) for processing, and the preparation cost is very high, which is only suitable for the experimental stage and is not suitable for large-scale applications. mass production.

Therefore, it is very necessary to provide a field effect transistor with simple preparation method, low cost and good thermal performance.

【Content of invention】

In order to solve the technical problems of the prior art, the object of the present invention is to provide a field effect transistor with simple preparation method, low cost and good thermal performance.

Another object of the present invention is to provide a method for preparing such a field effect transistor.

To achieve the purpose of the present invention, the present invention provides a field effect transistor, which includes a semiconductor layer of a first conductivity type; a source region of a second conductivity type and a drain region of a second conductivity type are respectively formed on the above-mentioned A semiconductor layer, the source region and the drain region are at a certain distance; an insulating oxide layer is formed on the semiconductor layer and is located between the source region and the drain region; a source electrode, a drain electrode and a The gate electrodes are respectively formed on the source region, the drain region and the insulating oxide layer, wherein the semiconductor layer is a semiconducting carbon nanotube layer.

The diameter of the carbon nanotube in the carbon nanotube layer of the present invention is 2-10 nanometers, the height is 20-500 nanometers, and the material of the insulating oxide layer is silicon dioxide.

To achieve another object of the present invention, the present invention also provides a method for preparing such a field effect transistor, comprising the following steps:

providing a semiconducting carbon nanotube layer substrate of a first conductivity type;

Forming a source region and a drain region of the second conductivity type on the above-mentioned carbon nanotube layer substrate, the source region and the drain region are separated by a certain distance;

forming an insulating oxide layer on the carbon nanotube substrate between the source region and the drain region;

Metal electrodes are respectively disposed on the source region, the drain region and the insulating oxide layer.

Compared with the prior art, the field effect transistor of the present invention has the following advantages: First, the carbon nanotube layer is directly used to replace the silicon substrate of the traditional field effect transistor, which can be combined with the traditional silicon process technology, and is suitable for large-scale production applications ; Second, carbon nanotubes themselves have extremely high thermal conductivity, reaching 400-1000Watt/mK, so they can effectively dissipate the heat generated by the operation of transistors quickly, thereby solving the problem of heat dissipation when the integration level increases; Third, due to the use of carbon nanotubes as the substrate, its nanoscale processing can make the current silicon device 0.13 micron process smaller, such as below 60 nanometers, so the size of each transistor will become smaller, and because carbon atoms It is more stable than silicon atoms, and can realize the switching function of transistors with less electron movement, thereby reducing the generation of heat in the system.

【Description of drawings】

FIG. 1 is a schematic diagram of a field effect transistor of the present invention.

Fig. 2 is a schematic diagram of a method for preparing a field effect transistor of the present invention.

【Detailed ways】

The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

Please refer to Fig. 1, the present invention provides a kind of field effect transistor 11, and it comprises a P-type carbon nanotube layer 12 substrates; An N-type doping region is as source region 13 and an N-type doping region is as drain region 14 are respectively formed on the above-mentioned P-type carbon nanotube layer 12, the source region 13 and the drain region 14 are separated by a certain distance; an insulating oxide layer 15 is formed on the above-mentioned P-type carbon nanotube layer 12, and is located in the above-mentioned source region 13 and the drain region 14 ; a source electrode 131 , a drain electrode 141 and a gate electrode 151 are respectively formed on the source region 13 , the drain region 14 and the insulating oxide layer 15 . Wherein, the insulating oxide layer 15 in this embodiment is a silicon dioxide layer, and the metal electrodes are selected from aluminum, gold or copper electrodes.

The present invention further provides a method for preparing a field effect transistor 11, which comprises the following steps:

Step 10 is to provide a p-type carbon nanotube layer substrate;

Step 20 is to dope the P-type carbon nanotube layer substrate at a certain distance by ion implantation to form N-type source region and drain region, wherein phosphorus ions are used for doping in this embodiment;

Step 30 is to form an insulating oxide layer on the carbon nanotube layer substrate, between the source region and the drain region;

Step 40 is disposing metal electrodes on the source region, the drain region and the insulating oxide layer to form the source electrode, the drain electrode and the gate electrode of the field effect transistor respectively.

The forming method of the carbon nanotube layer substrate of the present invention comprises the following steps:

providing a substrate, the substrate material can be selected from carbon, glass or silicon;

Deposit a catalyst layer on the substrate, the thickness of the catalyst layer is 5-30 nanometers, the method of deposition of the catalyst layer can be vacuum thermal evaporation volatilization method or electron beam evaporation method. The material of the catalyst can be iron, cobalt, nickel, platinum, palladium or its alloys. In this embodiment, iron is selected as the catalyst material, and the thickness of its deposition is 10 nanometers;

The substrate with the catalyst layer is placed in the air, and annealed to oxidize and shrink the catalyst layer into nanoscale catalyst particles. After the annealing is completed, place the substrate with the catalyst particles in the reaction chamber (not shown in the figure), pass through the carbon source gas acetylene and the protective gas argon, and use the low-temperature thermal chemical vapor deposition method to grow carbon nanometers on the catalyst particles. tubes to form a carbon nanotube film. The carbon source gas can also be other carbon-containing gases, such as ethylene, benzene, carbon monoxide, etc. Among them, when benzene is used as the carbon source gas, the protective gas should be hydrogen, and when carbon monoxide is used as the carbon source gas, the catalyst should be iron pentacarbonyl Fe(CO) ₅ . The diameter of the carbon nanotube produced by the invention is 2-10 nanometers, the height is 20-500 nanometers, and the growth temperature of the low-temperature chemical vapor deposition method is 550-600 degrees Celsius.

The field effect transistor 11 of the present embodiment is a P-channel metal oxide semiconductor field-effect transistor, and those skilled in the art should understand that the N-channel metal oxide semiconductor field effect transistor can be formed by performing P-type doping on the N-type carbon nanotube layer substrate. Oxide Semiconductor Field Effect Transistor. Similarly, other field effect transistors such as junction field effect transistors and insulated gate field effect transistors can be formed by replacing the silicon substrate of traditional transistors with semiconductor carbon nanotube layers.

The field effect transistor of the present invention has the following advantages: first, the silicon substrate of the traditional field effect transistor is directly replaced by the carbon nanotube layer, which can be combined with the traditional silicon process technology, and is suitable for large-scale production and application; It has a very high thermal conductivity, reaching 400-1000Watt/mK, so it can effectively dissipate the heat generated by the operation of the transistor quickly, thereby solving the problem of heat dissipation when the integration level increases; third, due to the use of carbon nanotubes As a substrate, its nanoscale processing can make the current 0.13 micron process of silicon devices smaller, such as below 60 nanometers, so the size of each transistor becomes smaller, and because carbon atoms themselves are more stable than silicon atoms, they can The switching function of the transistor is realized with less electron movement, thereby reducing the generation of heat in the system.

Claims (6)

1. A method for preparing a field effect transistor, comprising the following steps: A substrate is provided, a catalyst layer is deposited on the substrate, carbon source gas is passed through, and a carbon nanotube layer is formed by a low-temperature thermal chemical vapor deposition method, as a substrate of a semiconducting carbon nanotube layer of the first conductivity type; Forming a source region and a drain region of the second conductivity type on the above-mentioned carbon nanotube layer substrate, the source region and the drain region are separated by a certain distance; forming an insulating oxide layer on the carbon nanotube layer substrate, between the source region and the drain region; Metal electrodes are respectively disposed on the source region, the drain region and the insulating oxide layer. 2. The preparation method of field effect transistor as claimed in claim 1, is characterized in that this substrate material is selected from carbon, glass or silicon. 3. the preparation method of field effect transistor as claimed in claim 1 is characterized in that this carbon source gas is selected from acetylene, ethylene, benzene or carbon monoxide. 4. the preparation method of field effect transistor as claimed in claim 1 is characterized in that this catalyst material is selected from iron, cobalt, nickel, platinum, palladium or its alloy. 5. The method for preparing a field effect transistor as claimed in claim 1, characterized in that the growth temperature of the low-temperature chemical vapor deposition method is 550-600 degrees Celsius. 6. The method for preparing a field effect transistor according to claim 1, wherein the source region and the drain region are formed by ion implantation.

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