阅读说明：本技术 一种高频半导体薄膜场效应管及其制备方法 (High-frequency semiconductor thin film field effect transistor and preparation method thereof ) 是由 王一鸣 梁广大 宋爱民 辛倩 于 2018-06-29 设计创作，主要内容包括：本发明的高频半导体薄膜场效应管,包括衬底、半导体层、栅介质层、源极、漏极和栅极,栅介质层与栅极之间设置有耐栅极刻蚀液腐蚀的阻隔层。本发明的薄膜场效应管的制备方法包括：a).制备半导体层；b).制备栅介质层；c).沉积阻隔层；d).制备铝薄膜；e).定义器件范围；f).旋涂光刻胶；g).刻蚀沟道；h).刻蚀氧化铝薄膜；i).制备源、漏电极；j).剥离处理。本发明的高频半导体薄膜场效应管及制备方法,使用线宽极限为2～3微米的紫外光刻方法,可获得亚微米尺寸长度的沟道,极大降低了制作成本,源、漏极与栅极之间的间隔极窄,没有寄生电容,有效提高了半导体薄膜场效应管的高频截止频率。(The high-frequency semiconductor thin film field effect transistor comprises a substrate, a semiconductor layer, a gate dielectric layer, a source electrode, a drain electrode and a grid electrode, wherein a barrier layer which is resistant to corrosion of grid electrode etching liquid is arranged between the gate dielectric layer and the grid electrode. The preparation method of the thin film field effect transistor comprises the following steps: a) preparing a semiconductor layer; b) preparing a gate dielectric layer; c) depositing a barrier layer; d) preparing an aluminum film; e) defining a device range; f) spin-coating a photoresist; g) etching the channel; h) etching the aluminum oxide film; i) preparing a source electrode and a drain electrode; j) stripping treatment. According to the high-frequency semiconductor thin film field effect transistor and the preparation method, the channel with the submicron size length can be obtained by using the ultraviolet photoetching method with the line width limit of 2-3 micrometers, the manufacturing cost is greatly reduced, the interval between the source electrode, the drain electrode and the grid electrode is extremely narrow, parasitic capacitance does not exist, and the high-frequency cut-off frequency of the semiconductor thin film field effect transistor is effectively improved.)

1. A high-frequency semiconductor thin film field effect transistor comprises a substrate (1), a semiconductor layer (2), a gate dielectric layer (3), a source electrode (5), a drain electrode (6) and a grid electrode (7), wherein the substrate is made of insulating materials, the semiconductor layer is arranged on the substrate, the gate dielectric layer is arranged in the center of the semiconductor layer, the grid electrode is positioned above the gate dielectric layer, and the source electrode and the drain electrode are respectively arranged on the semiconductor layer at two sides of the gate dielectric layer; the method is characterized in that: and a barrier layer (4) which is resistant to corrosion of grid etching liquid is arranged between the grid dielectric layer and the grid.

2. The high-frequency semiconductor thin film field effect transistor and the method of manufacturing the same according to claim 1, wherein: the group interlayer is made of hafnium oxide (HfO)₂。

3. The high-frequency semiconductor thin film field effect transistor and the method of manufacturing the same according to claim 1 or 2, wherein: the semiconductor layer (2) is made of InSe selenide, and the gate dielectric layer (3) is made of Al oxide₂O₃。

4. A preparation method of a high-frequency semiconductor thin film field effect transistor is characterized by comprising the following steps:

a) preparing a semiconductor layer, and preparing a semiconductor film on an insulating substrate (1) as a semiconductor layer (2);

b) preparing a gate dielectric layer, and depositing a layer of aluminum oxide Al on the surface of the semiconductor layer by adopting Atomic Layer Deposition (ALD)₂O₃The thin film is used as a gate dielectric layer (3);

c) depositing a barrier layer on Al using atomic layer deposition ALD₂O₃Depositing a layer of hafnium oxide HfO on the surface of the film₂；

d) Preparing an aluminum thin film, and then oxidizing the hafnium HfO₂Preparing an aluminum film on the surface of the group interlayer;

e) defining the range of the device, defining the range of the device by a photoetching method, and etching the aluminum film outside the range of the device by using an aluminum etching solution to avoid interconnection short circuit between the devices;

f) spin-coating a photoresist;

g) etching a channel, namely exposing the channel position of the device at first, etching and removing the aluminum film on the channel position by using an aluminum etching liquid after developing, and forming an inward concave shape on the aluminum film under the photoresist due to the fact that the aluminum film is etched and transversely etched by the etching liquid;

h) etching the aluminum oxide film, etching the aluminum oxide film by adopting plasma, and only etching the aluminum oxide film in the channel under the protection action of the photoresist to expose the semiconductor film in the channel;

i) preparing a source electrode and a drain electrode, and depositing a layer of metal film by adopting Atomic Layer Deposition (ALD) to form the source electrode and the drain electrode;

j) stripping treatment, namely removing the photoresist and the metal film attached to the photoresist by adopting a stripping method to form the semiconductor film field effect transistor to be prepared.

5. The method for manufacturing a high-frequency semiconductor thin film field effect transistor according to claim 4, wherein: the material of the semiconductor layer prepared in the step a) is indium selenide InSe, and the material of the aluminum oxide Al prepared in the step b)₂O₃The thickness of the film is 20 to 40nm, and the hafnium oxide HfO deposited in the step c)₂The thickness of the barrier layer is 2-3nm, and the aluminum film prepared in the step d)The thickness is 80-120 nm, and aluminum etching liquid with the temperature of 40 ℃ is used for etching for 60 seconds in the step e) and the step g).

6. The method for manufacturing a high-frequency semiconductor thin film field effect transistor according to claim 4, wherein: in the step a), a semiconductor layer is arranged on a substrate, and a patterned semiconductor material film or a two-dimensional material sheet prepared by a mechanical stripping method is adopted; when a two-dimensional material sheet is produced by a mechanical peeling method, steps a) to c) are carried out by: the two-dimensional material indium selenide InSe film is oppositely torn for a plurality of times through an adhesive tape, then is transferred to a clean silicon dioxide glass substrate, then is immediately placed in an atomic layer deposition equipment cavity, an aluminum oxide film with the thickness of 30nm is deposited, and then hafnium oxide HfO with the thickness of 2-3nm is deposited₂A film.

Technical Field

The invention relates to a high-frequency semiconductor thin film field effect transistor and a preparation method thereof, in particular to a high-frequency semiconductor thin film field effect transistor and a preparation method thereof.

Background

In recent years, with the development of thin film field effect transistors of new semiconductors, such as oxide amorphous silicon, polycrystalline silicon, zinc oxide, indium gallium zinc oxide, and thin film field effect transistors of two-dimensional materials graphene, transition metal chalcogenide, and iii vi group compound. The frequency characteristics of devices are attracting increasing attention as important indicators of high-speed electronic circuits. By principle exploration, process design and material selection, the manufacture of thin film semiconductor field effect transistors with higher cut-off frequency is a practical requirement for future logic and analog electronic circuit applications.

The cut-off frequency of a semiconductor thin film field effect transistor is influenced by a plurality of factors, and the calculation formula is as follows:f _T= g _m/(2π(C _g+C _p)) ≈μ(V _g -V _th )/(2πL(L+L _ov ))，whereinf _TIs the frequency of the cut-off frequency,C _gis a capacitance of the gate electrode,C _pis a parasitic capacitance that is a function of,μis the mobility of the field effect and is,Lis the length of the channel or channels,L _ovis the overlap length of the gate and the source and drain. According to the calculation formula, the cut-off frequency of the device can be improved by reducing the parasitic capacitance of the device. Research proves that when the field effect mobility (transconductance) of the semiconductor thin film is increased, the channel length is reduced and the parasitic capacitance is reduced, the cut-off frequency is improved, so that the semiconductor thin film field effect transistor has good high-frequency characteristics. However, in the process of manufacturing a semiconductor thin film field effect transistor, the submicron size is usually realized by an electron beam exposure process, and the electron beam exposure is difficult to realize for a quartz substrate (high frequency loss is lower than that of a high resistance substrate) which is completely non-conductive.

Disclosure of Invention

The invention provides a high-frequency semiconductor thin film field effect transistor and a preparation method thereof in order to overcome the defects of the technical problems.

The high-frequency semiconductor thin film field effect transistor comprises a substrate, a semiconductor layer, a gate dielectric layer, a source electrode, a drain electrode and a grid electrode, wherein the substrate is made of insulating materials; the method is characterized in that: and a barrier layer which is resistant to corrosion of grid etching liquid is arranged between the grid dielectric layer and the grid.

In the high-frequency semiconductor thin film field effect transistor, the material of the group interlayer is hafnium oxide (HfO)₂。

According to the high-frequency semiconductor thin film field effect transistor, the semiconductor layer is made of InSe selenide, and the gate dielectric layer is made of Al oxide₂O₃。

The preparation method of the high-frequency semiconductor thin film field effect transistor is characterized by comprising the following steps of:

a) preparing a semiconductor layer, and preparing a semiconductor film on an insulating substrate (1) as a semiconductor layer (2); b) preparing a gate dielectric layer, and depositing a layer of aluminum oxide Al on the surface of the semiconductor layer by adopting Atomic Layer Deposition (ALD)₂O₃The thin film is used as a gate dielectric layer (3); c) depositing a barrier layer on Al using atomic layer deposition ALD₂O₃Depositing a layer of hafnium oxide HfO on the surface of the film₂(ii) a d) Preparing an aluminum thin film, and then oxidizing the hafnium HfO₂Preparing an aluminum film on the surface of the group interlayer; e) defining the range of the device, defining the range of the device by a photoetching method, and etching the aluminum film outside the range of the device by using an aluminum etching solution to avoid interconnection short circuit between the devices; f) spin-coating a photoresist; g) etching a channel, namely exposing the channel position of the device at first, etching and removing the aluminum film on the channel position by using an aluminum etching liquid after developing, and forming an inward concave shape on the aluminum film under the photoresist due to the fact that the aluminum film is etched and transversely etched by the etching liquid; h) etching the alumina film by plasma etchingThe film is etched only on the alumina film in the channel under the protection of the photoresist, so that the semiconductor film in the channel is exposed; i) preparing a source electrode and a drain electrode, and depositing a layer of metal film by adopting Atomic Layer Deposition (ALD) to form the source electrode and the drain electrode; j) stripping treatment, namely removing the photoresist and the metal film attached to the photoresist by adopting a stripping method to form the semiconductor film field effect transistor to be prepared.

According to the preparation method of the high-frequency semiconductor thin film field effect transistor, the material of the semiconductor layer prepared in the step a) is indium selenide InSe, and the material of the aluminum oxide Al prepared in the step b)₂O₃The thickness of the film is 20 to 40nm, and the hafnium oxide HfO deposited in the step c)₂The thickness of the blocking layer is 2-3nm, the thickness of the aluminum film prepared in the step d) is 80-120 nm, and aluminum etching liquid with the temperature of 40 ℃ is used for etching for 60 seconds in the step e) and the step g).

The invention relates to a preparation method of a high-frequency semiconductor thin film field effect transistor, which comprises the following steps that in the step a), a semiconductor layer is arranged on a substrate, and a patterned semiconductor material thin film or a two-dimensional material sheet prepared by a mechanical stripping method is adopted; when a two-dimensional material sheet is produced by a mechanical peeling method, steps a) to c) are carried out by: the two-dimensional material indium selenide InSe film is oppositely torn for a plurality of times through an adhesive tape, then is transferred to a clean silicon dioxide glass substrate, then is immediately placed in an atomic layer deposition equipment cavity, an aluminum oxide film with the thickness of 30nm is deposited, and then hafnium oxide HfO with the thickness of 2-3nm is deposited₂A film.

The invention has the beneficial effects that: the high-frequency semiconductor thin film field effect transistor consists of a substrate, a semiconductor layer, a gate dielectric layer, a source electrode, a drain electrode, a grid electrode and a group interlayer, wherein Al is arranged on the substrate₂O₃Hafnium oxide (HfO) is arranged between the gate dielectric layer and the gate₂The interlayer is formed, and the hafnium oxide film can effectively prevent the etching liquid from corroding the aluminum oxide after the aluminum film is etched, so that the speed of next step gas dry etching of the aluminum oxide is more accurately controlled, over-etching of a semiconductor layer in the dry etching process is avoided, and the performance of the obtained high-frequency semiconductor film field effect transistor is ensured.

According to the inventionIn the process of etching a channel, the aluminum etching liquid has the capability of etching longitudinally and transversely, so that the lower part of the photoresist is in an inwards concave shape, and Al in the channel is etched₂O₃After the gate dielectric layer is deposited, in the process of depositing the source electrode and the drain electrode, the transverse intervals among the formed source electrode, the drain electrode and the grid electrode are extremely narrow (about 100 nm), and the grid electrode, the drain electrode and the source electrode are not overlapped completely, so that the formed semiconductor thin film field effect transistor has no parasitic capacitance, the high-frequency cut-off frequency of the semiconductor thin film field effect transistor is effectively improved, and the semiconductor thin film field effect transistor is more suitable for being applied in higher-frequency occasions.

Meanwhile, the aluminum oxide film formed by atomic layer deposition is coated on the semiconductor film, so that the semiconductor film is isolated from chemical substances and air in the subsequent process, and meanwhile, the aluminum oxide film can be used as a dielectric layer for top gate regulation and control. The preparation method of the high-frequency semiconductor thin film field effect transistor realizes the use of an ultraviolet lithography method with the line width limit of 2-3 microns, can obtain a channel with the length of submicron dimension, avoids the exposure step of completing submicron patterns by electron beam exposure equipment in the traditional process, and effectively reduces the manufacturing cost.

Drawings

FIG. 1 is a schematic structural diagram of a high frequency semiconductor thin film field effect transistor according to the present invention;

FIG. 2 is a schematic diagram of a semiconductor layer formed during the process of forming a thin film field effect transistor according to the present invention;

FIG. 3 shows Al is prepared in the process of preparing the thin film field effect transistor of the present invention₂O₃A schematic view of a thin film;

FIG. 4 shows deposition of HfO during the process of manufacturing the thin film FET of the present invention₂A schematic diagram of (a);

FIG. 5 is a schematic diagram of an aluminum film during the fabrication of a thin film FET according to the present invention;

FIG. 6 is a schematic view of spin-on photoresist during the fabrication of a TFT according to the present invention;

FIG. 7 is a schematic diagram of a trench etched during the fabrication of a TFT according to the present invention;

FIG. 8 is a schematic diagram of etching an alumina film during the fabrication of a thin film FET in accordance with the present invention;

FIG. 9 is a schematic diagram of the source and drain electrodes during the fabrication of the thin film FET according to the present invention;

FIG. 10 is a schematic view of a peeling process in the process of manufacturing a thin film transistor according to the present invention.

In the figure: the structure comprises a substrate 1, a semiconductor layer 2, a gate dielectric layer 3, a barrier layer 4, a source electrode 5, a drain electrode 6 and a grid electrode 7.

Detailed Description

The invention is further described with reference to the following figures and examples.

As shown in fig. 1, a schematic structural diagram of a high-frequency semiconductor thin film field effect transistor of the present invention is provided, which includes a substrate 1, a semiconductor layer 2, a gate dielectric layer 3, a source electrode 5, a barrier layer 4, a drain electrode 6 and a gate electrode 7, wherein the substrate 1 is made of an insulating material, the semiconductor layer 2 is disposed on the substrate, the gate dielectric layer 3 is disposed in the center of the semiconductor layer 3, the gate electrode 7 is located above the gate dielectric layer 3, and the source electrode 5 and the drain electrode 6 are respectively disposed on the semiconductor layer 2 at two sides of the gate dielectric layer; a barrier layer 4 which is resistant to corrosion of grid etching liquid is arranged between the grid dielectric layer 3 and the grid 7, the semiconductor layer 2 is made of indium selenide InSe, and the grid dielectric layer 3 is made of aluminum oxide Al₂O₃. The material of the group interlayer is hafnium oxide (HfO)₂. The hafnium oxide film can effectively prevent the etching liquid from corroding the aluminum oxide after the aluminum film is etched, so that the speed of next step gas dry etching of the aluminum oxide is more accurately controlled, the influence on a gate dielectric layer in the dry etching process is avoided, and the performance of the obtained high-frequency semiconductor film field effect transistor is ensured.

As shown in FIGS. 1 to 10, the preparation of the semiconductor layer and the preparation of Al in the thin film field effect transistor of the present invention are sequentially illustrated₂O₃Film, deposited HfO₂The preparation method of the high-frequency semiconductor thin film field effect transistor is realized by the following steps:

a) preparing a semiconductor layer, and preparing a semiconductor film on an insulating substrate to serve as the semiconductor layer;

b) preparing a gate dielectric layer, and depositing a layer of aluminum oxide Al on the surface of the semiconductor layer by adopting Atomic Layer Deposition (ALD)₂O₃The film is used as a gate dielectric layer;

c) depositing a barrier layer on Al using atomic layer deposition ALD₂O₃Depositing a layer of hafnium oxide HfO on the surface of the film₂；

d) Preparing an aluminum thin film, and then oxidizing the hafnium HfO₂Preparing an aluminum film on the surface of the group interlayer;

e) defining the range of the device, defining the range of the device by a photoetching method, and etching the aluminum film outside the range of the device by using an aluminum etching solution to avoid interconnection short circuit between the devices;

f) spin-coating a photoresist;

g) etching a channel, namely exposing the channel position of the device at first, etching and removing the aluminum film on the channel position by using an aluminum etching liquid after developing, and forming an inward concave shape on the aluminum film under the photoresist due to the fact that the aluminum film is etched and transversely etched by the etching liquid;

h) etching the aluminum oxide film, etching the aluminum oxide film by adopting plasma, and only etching the aluminum oxide film in the channel under the protection action of the photoresist to expose the semiconductor film in the channel;

i) preparing a source electrode and a drain electrode, and depositing a layer of metal film by adopting Atomic Layer Deposition (ALD) to form the source electrode and the drain electrode;

j) stripping treatment, namely removing the photoresist and the metal film attached to the photoresist by adopting a stripping method to form the semiconductor film field effect transistor to be prepared.

Wherein the material of the semiconductor layer prepared in the step a) is indium selenide InSe, and the material of the aluminum oxide Al prepared in the step b)₂O₃The thickness of the film is 20 to 40nm, and the hafnium oxide HfO deposited in the step c)₂The thickness of the barrier layer is 2-3nm, the thickness of the aluminum film prepared in the step d) is 80-120 nm, and aluminum etching liquid with the temperature of 40 ℃ is used for etching in the step e) and the step g)For 60 seconds.

In the step a), a semiconductor layer is arranged on a substrate, and a patterned semiconductor material film or a two-dimensional material sheet prepared by a mechanical stripping method is adopted; when a two-dimensional material sheet is produced by a mechanical peeling method, steps a) to c) are carried out by: the two-dimensional material indium selenide InSe film is oppositely torn for a plurality of times through an adhesive tape, then is transferred to a clean silicon dioxide glass substrate, then is immediately placed in an atomic layer deposition equipment cavity, an aluminum oxide film with the thickness of 30nm is deposited, and then hafnium oxide HfO with the thickness of 2-3nm is deposited₂A film.

The preparation method of the high-frequency semiconductor film field effect transistor can select a two-dimensional material sheet prepared by a mechanical stripping method or a patterned semiconductor material film, and after the semiconductor film is prepared, a conformal and compact alumina film can be obtained by using an atomic layer deposition mode, so that the influence of water molecules, oxygen molecules and the like in the air and the influence of chemical solvents such as photoresist, developing solution, acetone, ethanol and the like which are possibly contacted in the photoetching process can be effectively isolated. Meanwhile, the aluminum oxide film serving as a dielectric layer can provide a better semiconductor dielectric layer interface, reduce interface defect states and improve the field effect mobility of the field effect transistor.

According to the preparation method of the high-frequency semiconductor thin-film field effect transistor, aluminum etching liquid (the proportion of the aluminum etching liquid is phosphoric acid, nitric acid, glacial acetic acid and water = 80: 5: 5: 10) at 40 ℃ is utilized to perform wet etching on aluminum, and the characteristics of longitudinal etching and transverse etching are achieved. Ultraviolet lithography is limited to line widths (positive resist non-exposed regions) of 2-3 microns, and is shortened to dimensions within 2 microns or even sub-microns by etching. Typically submicron dimensions are required to be achieved with electron beam exposure processes, which are difficult to achieve for fully non-conductive quartz substrate (lower high frequency losses than high resistance substrates) processes. Meanwhile, due to the fact that the mode is self-alignment instead of manual alignment, microscopic defects with uneven electrode edges can be completely conformal, uniform intervals (underlaps) of a grid electrode, a source electrode and a drain electrode are formed through etching, and the size can be controlled to be about 100 nm.

According to the preparation method of the high-frequency semiconductor film field effect transistor, the etching speed of the aluminum etching liquid to the hafnium oxide film is much slower than that of the aluminum oxide film. The hafnium oxide film on the surface layer can effectively prevent the etching liquid from corroding the aluminum oxide after the aluminum film is etched. The speed of the next step of gas dry etching of the alumina is more accurately controlled, and the dry etching speed is not influenced. By the process design method, due to the fact that overlapping of the grid electrode, the source electrode and the drain electrode caused by alignment errors does not exist, parasitic capacitance can be reduced to the greatest extent, and frequency characteristics of the device are improved.

The specific steps for preparing the high-frequency semiconductor thin-film field effect transistor by taking a two-dimensional material InSe as a semiconductor material are given as follows:

1. a two-dimensional material InSe (indium selenide) thin film was torn several times through a tape and transferred onto a clean quartz (silica) glass substrate. It is immediately placed in the atomic layer deposition equipment cavity. Depositing 30nm aluminum oxide film at 150 deg.C, and depositing 2-3nm hafnium oxide (HfO)₂) A film.

2. Since the alumina film does not affect the microscopic observation of the piece of InSe film, the position of the piece of InSe film on the substrate is registered.

3. And placing the substrate in a thermal evaporation table cavity, and winding an aluminum wire on an electrified tungsten wire to be used as an evaporation source. The vacuum degree of the cavity reaches 8 x 10^-6Torr. Heating tungsten filament by current to melt aluminum filament, evaporating and depositing on the substrate at 2 angstrom/s speed, and co-depositing 100nm aluminum film.

4. Taking the substrate out of the cavity, spin-coating positive adhesive AR 5350, and baking for 3 minutes at 110 ℃ on a hot plate. And designing a layout on the maskless ultraviolet lithography equipment, and exposing the position of the aluminum film between the device layouts. Development was carried out for 25 seconds. And etching by using 40 ℃ aluminum etching liquid for 60 seconds to remove the aluminum film between the devices so as to prevent interconnection short circuit between the devices.

5. Spin coating positive glue AR 5350 again, baking for 3 minutes at 110 ℃ on a hot plate. And exposing the position of the source and drain electrodes, wherein the gate length of the layout design is 3 microns. Post exposure development for 25 seconds. And etching by using 40 ℃ aluminum etching liquid for 60 seconds to etch the aluminum at the position of the source and drain electrodes. Because the wet etching has etching in both the longitudinal direction and the transverse direction, an inwards concave 'undercut' shape can be formed under the photoresist layer.

6. The alumina film was etched using a reactive plasma etching apparatus ICP.

7. And (3) evaporating 25nm Ti/75 nm Au by using an electron beam evaporation device, wherein the evaporated titanium gold film is blocked by the photoresist to form a source-drain electrode due to the shape of the undercut formed before. Taking out the sample, placing the sample in acetone for soaking for one hour, dissolving the photoresist and stripping the titanium metal film. The undercut shape is very favorable for the lift-off process at the sidewalls. And an extremely narrow interval 'underlay' of about 100nm is formed between the aluminum gate electrode and the source and drain electrodes. Since there is no overlap between the gate electrode and the source and drain electrodes at all, there is no parasitic capacitance.