JP3032827B1 - Manufacturing method of semiconductor thin film - Google Patents

Abstract

Kind Code: A1 From a precursor formed by a sol-gel method or a spray pyrolysis method, a semiconductor thin film whose optical and electrical properties are controlled by a simple means and without adding an element. It is intended to be manufactured. SOLUTION: After a transition metal chalcogenide-containing gel thin film is formed on a substrate, an active ray having an energy higher than the band gap of the transition metal chalcogenide is used in producing a semiconductor thin film by irradiating the thin film with an active ray. The semiconductor thin film is manufactured by controlling the optical and electrical properties of the semiconductor thin film to be generated by changing the energy density of the active ray.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a semiconductor thin film, and more specifically, to a method for controlling optical and electric properties controlled by a sol-gel method on a substrate such as glass, ceramics, plastics or single crystal. The present invention relates to a method for forming a semiconductor thin film having physical properties.

[0002]

2. Description of the Related Art Heretofore, as a method of producing a semiconductor thin film by a sol-gel method, for example, a zinc oxide thin film has been coated with a 2-methoxyethanol solution of zinc acetate containing monoethanolamine or diethanolamine on a glass substrate. Thereafter, a method of obtaining a crystallized zinc oxide thin film by heat treatment at 200 to 800 ° C. is known. In this case, ZnO obtained by an additive or a sintering temperature is known.
It is also known that the crystallinity and c-axis orientation of the material change [see Journal of the Ceramic Society,
Of Japan (J. Ceramic. Soc. Of
Jap. ) ", Vol. 104 (No. 4), 296-30
0 (1996)].

Further, when forming a ZnO thin film using a sol-gel method, if the ZnO crystal film obtained by firing in air is further fired in a nitrogen atmosphere, the sheet resistivity is reduced. "Journal of Materials Science (J. Mater. Sci.)", Vol. 29, No. 409
9-4103 (1994)], and when forming a ZnO thin film using a spray pyrolysis method, a precursor film deposited on a substrate is fired in an oxygen atmosphere or a reducing atmosphere composed of nitrogen and hydrogen. Then, the resulting ZnO thin film becomes an orange or green thin film due to oxygen excess or oxygen shortage [“Journal of Applied Physics (J. Appl. Phys.), 8th.
4, 2287-2294 (1998)].

In addition, when a precursor film of indium oxide (In ₂ O ₃ ) obtained by a sol-gel method is irradiated with an ultraviolet laser at room temperature, a crystallized indium oxide film can be obtained [see Journal of -Sol-Gel Science and Technology (J. Sol-Gel S
ci. Technol. ) ", Vol. 13, Nos. 991-9
P. 94 (1998)] or crystallize indium oxide by irradiation with ultraviolet light at room temperature to form an indium oxide thin film on a substrate having low heat resistance, and to reduce the etching rate between the light irradiation part and the non-irradiation part. Making use of the difference to obtain a patterned indium oxide thin film.
No. 157855) is also known. However, it has not been known to control the optical and electrical properties of a semiconductor by changing the crystallinity and composition by these methods.

[0005] On the other hand, recently, the problem of industrial waste disposal regarding electric appliances and the like has been socially highlighted.
In order to solve this problem, the presence of various dopants added for improving performance is a major obstacle. In other words, in order to recycle products and parts made of this dopant-containing material, many steps must be added to remove them, and time and cost burdens are not increased. I can't. Therefore, there is a demand for a method of adding multifunctionality by a physical method using a compound composed of a small number of elements or a compound containing no harmful elements as a material.

[0006]

SUMMARY OF THE INVENTION In view of such circumstances, the present invention has been made from a precursor formed by a sol-gel method or a spray pyrolysis method by simple means and without adding elements. It is intended to produce a semiconductor thin film having controlled optical and electrical properties.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted various studies on controlling the optical and electrical properties of a semiconductor to be produced when producing a semiconductor thin film from the precursor, and as a result, It has been found that the object can be achieved by using an actinic ray having energy higher than the band gap of the body and by changing the energy density of the actinic ray, and the present invention has been accomplished based on this finding.

That is, according to the present invention, when a transition metal chalcogenide-containing gel thin film is formed on a substrate and then irradiated with an actinic ray to produce a semiconductor thin film, the band gap of the transition metal chalcogenide is higher than that of the transition metal chalcogenide. A method of manufacturing a semiconductor thin film, comprising: irradiating an active ray having energy to perform electronic excitation; and changing an energy density of the active ray at this time to control optical and electrical properties of a generated semiconductor thin film. Is provided. here,
Transition metal chalcogenide means a compound of a transition metal and a chalcogen, ie, an oxygen group element such as oxygen, sulfur, selenium, and tellurium.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION As a substrate on which a semiconductor thin film is provided in the method of the present invention, any substrate can be selected from substrates conventionally used for forming a semiconductor thin film. Examples of such a substrate include a glass substrate such as Pyrex glass or quartz glass, a single crystal substrate, a ceramic substrate, a semiconductor substrate such as silicon or GaAs, and a plastic substrate.

In the present invention, the transition metal constituting the transition metal chalcogenide is 3d, 4d, 5d in terms of electronic structure.
And an element having an atomic structure in which an increase in electrons is observed in the electron shell of 6d.
This includes n to 39, from Y at 39 to Cd at 48, La from 57 to Hg at 80, and actinoid elements. Among them, particularly preferred are Ti, V, Cr, M
n, Fe, Co, Ni, Cu, Zn, Zr, Mo, A
g, Cd, Ta, W, Ir, Eu and Sm. In addition, although a typical chalcogenide of these transition metals is an oxide, in the method of the present invention, corresponding sulfides, selenides and tellurides can be used as well as oxides of these metals. .

The transition metal chalcogenide in the method of the present invention may be used alone or in combination of two or more, and is not particularly limited as long as it is finally crystallized to form a semiconductor. The transition metal chalcogenide further includes Li, Na, K, B, Al, Ga, In,
Metals other than transition metals, such as N, P, As, and halogen, and nonmetals can also be contained. Semiconductor obtained by the method of the present invention, for example, when using zinc oxide as a transition metal chalcogenide,

Embedded image (Provided that 0 ≦ x <1).

To manufacture the semiconductor thin film of the present invention, first, a gel film made of a transition metal chalcogenide is formed on a desired substrate by, for example, a sol-gel method. The gel film has a thickness of usually 5 to 500 nm, preferably 20 to 300 nm, after irradiation with a coating solution containing a metal salt, a metal alkoxide, an organometallic complex, or the like, formed on a substrate by spin coating or the like. After coating so as to fall within the range, it can be formed by heat treatment at about 150 to 350 ° C. In addition, when a desired thickness cannot be obtained by one coating and drying treatment, the coating and drying treatment can be repeated plural times. Also, 300n
When a film thicker than m is desired, the irradiation with light may be repeated several times after preparing the above gel film.

Next, when the gel film thus formed is irradiated with light having an energy higher than its band gap to be electronically excited, the gel film has the effect of crystallization and the ejection of atoms. Thus, a desired semiconductor thin film is formed. At this time, as a light source of irradiation light having energy higher than the band gap of the gel film, for example, a high-pressure mercury lamp, a low-pressure mercury lamp, ArF, KrF, Xe
Excimer lasers such as F and XeCl, YAG lasers, and the like are included.

In the method of the present invention, the optical and electrical properties of the semiconductor thin film can be controlled by changing the energy density and irradiation time of the light to be irradiated. However, even if the light of the same energy density is irradiated for the same time,
The optical and electrical properties of the obtained semiconductor thin film differ depending on the thickness and the coordination structure of the gel film. Therefore, when using laser light, it is important to control the energy density and irradiation time of irradiation light, including the frequency, according to the thickness and coordination structure of the gel film. In this manner, a semiconductor thin film having controlled optical properties (e.g., ultraviolet-visible absorption spectrum, emission spectrum by fluorescence spectroscopy) and electrical properties (e.g., electrical resistivity) can be manufactured.

By using the method of the present invention, a patterned semiconductor thin film can be manufactured. In this case, a gel film made of a precursor of the semiconductor thin film is formed in the same manner as described above, A patterned light having an energy higher than the band gap is applied to the gel film.
By irradiating and electronically exciting in the same manner as described above, a semiconductor thin film having a patterned portion controlled to desired optical and electrical properties can be obtained.

[0016]

According to the present invention, the optical and electrical properties which are formed on a substrate of glass, single crystal, ceramics, plastic, etc. and are useful as a phosphor thin film, a thin film laser, a transparent conductive film, etc. are controlled. Was done

Embedded image A semiconductor thin film such as (0 ≦ X <1) or a patterned semiconductor thin film can be easily obtained.

[0017]

EXAMPLES Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Example 1 A coating solution consisting of a 2-methoxyethanol solution containing zinc acetate and monoethanolamine at a concentration of 0.6 mol / liter was prepared. 30mm square size,
The above coating liquid was applied on a quartz glass substrate having a thickness of 1 mm by spin coating, and then dried at 473K. These coating and drying operations were repeated once, three and six times to form gel films having different thicknesses. After the laser irradiation (energy density: 100 mJ / cm ² ) shown below, the thickness of the gel film thus formed was 3 in accordance with the number of coats 1, 3 and 6 respectively.
5, 95 and 190 nm. The actual film thickness of a gel film or a laser light irradiation film having different laser light irradiation conditions is slightly different from these film thicknesses. X-ray diffraction measurement of the three types of gel films having different film thicknesses described above revealed that all of the precursors were in an amorphous phase. FIG. 1 is a diagram showing an ultraviolet-visible absorption spectrum of each gel film having a different film thickness and a quartz glass substrate. This figure 1
From the results shown in the above, the precursor zinc oxide was about 380 nm
It was confirmed that light having the following wavelengths could be absorbed. Also,
The spectrum is similar to the absorption spectrum of ZnO crystal having a stoichiometric composition described in many documents, so that irradiation with light having a wavelength of 380 nm or less causes the precursor zinc oxide to undergo electronic excitation. It is estimated that it will be.

Next, each gel film was irradiated with KrF excimer laser light (wavelength 248 nm, pulse width 22 ns) five times at 1 Hz at a substrate heating temperature of 473 K in the air. In addition, the energy density of the laser light is 50 to
Irradiation was performed in a range of 170 mJ / cm ² . The irradiation surface had a size of about 12 mm × 8 mm and was irradiated to a position near the center of each substrate.

FIG. 2 is an X-ray diffraction pattern of a gel film having a thickness of 95 nm and a film obtained by irradiating the gel film with a laser beam having an energy density of 50 to 170 mJ / cm ² . From the results shown in FIG. 2, it was confirmed that zinc oxide was crystallized by irradiation with a laser beam having an energy density of 100 mJ / cm ² or more, and a laser having an energy density of 100 mJ / cm ² and 130 mJ / cm ² . When irradiated with light, the crystallinity of zinc oxide is low and c-axis orientation is weak, whereas when irradiated with laser light having a high energy density of 150 mJ / cm ² or more, the crystallinity of zinc oxide is high and c-axis orientation is high. Is also getting stronger. That is, it was confirmed that the crystallinity and c-axis orientation of zinc oxide can be controlled in accordance with the energy density of the irradiation light.

FIG. 3 shows that a gel film having a thickness of 95 nm and 190 nm has an energy density of 100 mJ / cm ² [FIG.
(A)] and 150 mJ / cm ² [FIG. 3 (b)] are X-ray diffraction pattern diagrams of the film obtained by irradiating the laser beam. As shown in FIG. 3A, 100 mJ / cm
It was suggested that there was no significant difference in the crystallinity and orientation of zinc oxide depending on the film thickness in the laser light irradiation film of No. ² . However, as shown in FIG. 3B, 150 mJ / cm ²
In the laser light irradiation film of (1), the 95 nm thin film has higher zinc oxide crystallinity and stronger c-axis orientation. That is, it was confirmed that the crystallinity and c-axis orientation of zinc oxide change depending on the thickness of the film when irradiated with light having a high energy density.

FIG. 4 is a graph showing the relationship between the energy density and the c-axis lattice constant when a 95-nm thick gel film is irradiated with laser light. Note that the c-axis lattice constant is (0
FIG. 4 also shows the results of the c-axis lattice constant of the heat-treated film and the zinc oxide powder reagent obtained in Comparative Example 1, which were obtained from the precise X-ray diffraction measurement results of the diffraction line peak of (02). This figure 4
According to the results shown in (1), the normal heat-treated film is larger than the c-axis lattice constant of the zinc oxide powder. In contrast, the laser irradiation film has a smaller c-axis lattice constant than a normal heat-treated film, and decreases with an increase in energy density. The c-axis lattice constant is small. This decrease in the c-axis lattice constant is considered to be due to oxygen vacancies present in the crystallized zinc oxide crystal. This consideration is supported by the results of the fluorescence characteristics and the electrical resistivity described later.
Therefore, it is suggested that in the film irradiated with the laser light, the amount of oxygen vacancies increases with an increase in energy density. That is, depending on the energy density of the irradiated light,
It was confirmed that the composition of zinc oxide could be controlled.

[0023] Figure 5, ultraviolet different thicknesses of the gel film to an energy density of 100 mJ / cm ² and 150 mJ / cm ² of a film obtained by irradiating a laser beam - visible absorption spectrum. In the figure, the thin line and the thick line are 100
mJ / cm ^2, representing the film irradiated with laser light of 150 mJ / cm ^2. As shown in FIG. 5, 100 mJ / c
The laser light irradiation film at m ² shows a spectrum similar to that of the gel film. In addition, 150 mJ / c with a thickness of 190 nm
The laser light irradiation film at m ² also has a spectrum similar to that of a 100 mJ / cm ² laser light irradiation film or a gel film. This suggests that these films have a direct transition band structure, similar to ZnO crystals having a stoichiometric composition. On the other hand, it was suggested that the laser light irradiation films having a film thickness of 35 nm and 95 nm at 150 mJ / cm ² had an indirect transition type band structure. Such a difference in the band structure also affects the result of fluorescence spectrometry shown in FIG. 6 described later. From the results shown in FIG.
When a thin film is irradiated with high energy density light, it changes to an indirect transition type band structure that is different from the band structure of other obtained laser light irradiation films and stoichiometric ZnO crystals. It was confirmed that. According to the present invention,
It was confirmed that the optical properties can be controlled by controlling the film thickness of the precursor and the energy density of the light to be irradiated.

FIG. 6 shows the emission spectrum of a film obtained by irradiating a 95 nm-thick gel film with laser beams having different energy densities by fluorescence spectroscopy. The fluorescence spectroscopy was performed with excitation light having a wavelength of 325 nm. FIG. 6 shows that the intensity and peak wavelength of the emission spectrum vary depending on the energy density of the irradiated laser light. The weakest emission intensity of the laser light irradiation film at 150 mJ / cm ² is derived from having an indirect transition type band structure as shown in FIG. The peak wavelength is 50 mJ / cm ² , 100 mJ / cm ² , 150 mJ / cm ² .
Laser irradiation at J / cm ² , 600n each
m, 510 nm and 540 nm, so 50 mJ
/ Cm ² laser light irradiation film is yellow, 100mJ / c
Green light emission was observed in the laser light irradiation films at m ² and 150 mJ / cm ² . The difference between the peak wavelengths of light emission is described in "Journal of Applied Physics (J. Appl. Phys.)", Vol. 84, pp. 2287-2294 (1998). This is probably because it depends on the composition of the obtained zinc oxide thin film. From the results shown in FIG. 6, it was confirmed that the optical properties of the semiconductor thin film can be controlled by controlling the energy density of the irradiation light according to the present invention.

Example 2 A coating solution was prepared in the same manner as in Example 1, applied to a 30 mm square size quartz glass substrate having a thickness of 1 mm by spin coating, and then dried at 573K. Processed. This coating and drying operation was repeated six times to form a gel film having a thickness of about 110 nm. As a result of detecting residual organic matter in the obtained gel film by infrared spectroscopy, it was found that almost no organic matter remained. On the other hand, in the gel film obtained in Example 1, residual acetate base was observed. That is, it was suggested that the gel film obtained in Example 2 and the gel film obtained in Example 1 had a difference in the coordination structure centered on zinc. As in Example 1, the gel film obtained in Example 2
At a substrate heating temperature of 73 K, a KrF excimer laser beam was irradiated 5 times at 1 Hz. In addition, the energy density of the laser beam was changed in the range of 50 to 170 mJ / cm ² . FIG. 7 shows a gel film and an energy density of 50 to 1 in the gel film.
It is an X-ray diffraction pattern figure of the film | membrane obtained by irradiating 70 mJ / cm < ² > laser light. From the results shown in FIG. 7, it was confirmed that zinc oxide was crystallized by irradiation with a laser beam having an energy density of 100 mJ / cm ² or more, as in Example 1 (FIG. 2). However, when irradiated with a laser beam having an energy density of 100 mJ / cm ^{2 or} 130 mJ / cm ² , the crystallinity of zinc oxide is lower and the c-axis orientation is weaker than in Example 1. That is, it was confirmed that the crystallinity and c-axis orientation of zinc oxide could be controlled according to the coordination structure of the gel film.

Example 3 A coating solution was prepared in the same manner as in Example 1, applied on a quartz glass substrate having a size of 30 mm square and a thickness of 1 mm by spin coating, and then dried at 423 K. Processed. The operation of the coating treatment and the drying treatment was repeated three times to form a gel film having a thickness of about 100 nm. Except that the substrate heating temperature was 423K in the obtained gel film,
The KrF excimer laser light was applied for 1H in the same manner as in Example 1.
Irradiated 5 times at z. In addition, the energy density of the laser beam was changed in the range of 50 to 170 mJ / cm ² . FIG.
4 is a graph showing the electrical resistivity of a gel film and a film obtained by irradiating the gel film with laser beams having different energy densities. The electric resistivity was determined by measuring the sheet resistance by the four-point needle method. In addition, 5MΩ which is the measurement limit of the measuring device
The electrical resistivity of a sample having a high sheet resistance of // or more was tentatively plotted at 300 Ω · cm. From the results shown in FIG. 8, with an increase of the energy density of the laser beam, the electrical resistivity is reduced, at least three orders of magnitude or more electrical resistivity in laser light irradiation at 150 mJ / cm ² and 170 mJ / cm ² Could be lowered. It has been confirmed that the electrical resistivity of zinc oxide can be controlled in accordance with the energy density of the irradiation light.

Example 4 In the same manner as in Example 1, the coating treatment and the drying treatment were repeated three times to form a zinc oxide gel film having a thickness of about 95 nm. This gel film is exposed to 473K
A KrF excimer laser beam having an energy density of 50 mJ / cm ² at a substrate heating temperature of 5 times or 360 at 1 Hz.
Irradiated 0 times. In addition, 3600 irradiation experiments were performed at 5 Hz. FIG. 9 shows the X-ray diffraction pattern of the film irradiated with the laser light 5 times and 3600 times at 1 Hz and the film irradiated 3600 times at 5 Hz on the gel film. As shown in FIG. 9, with laser light (1 Hz) having an energy density of 50 mJ / cm ² , zinc oxide crystals were not observed after five irradiations, but crystallized by 3,600 long irradiations. . Further, the frequency of the laser light is set to 1H
By increasing from z to 5 Hz, the crystallinity and c
Axial orientation increased. That is, it was confirmed that the crystallinity and c-axis orientation of zinc oxide can be controlled according to the irradiation time and frequency of the laser light.

Example 5 In the same manner as in Example 1, coating and drying were repeated three times to form a zinc oxide gel film having a thickness of about 95 nm. 50 mJ / cm is applied to one obtained gel film.
Separate portions were irradiated with KrF excimer laser light having energy densities of ² and 100 mJ / cm ² at an irradiation surface size of 12 mm × 8 mm. As a result of examining the crystallinity and c-axis lattice constant (estimating the amount of oxygen vacancy) of each of the portions irradiated with laser beams having different energy densities by X-ray diffraction measurement, the laser beams having the corresponding energy densities in Example 1 were obtained. Results similar to those of the irradiated film were obtained. In addition, UV-visible spectrum, emission spectrum by fluorescence spectroscopy, and measurement results of sheet resistivity were almost the same. These results confirm that the patterned portions on the same substrate have the desired crystallinity and composition, so that a semiconductor thin film having various controlled optical and electrical properties can be manufactured. Was done.

Comparative Example 1 In the same manner as in Example 1, the coating treatment and the drying treatment were repeated three times to form a zinc oxide gel film having a thickness of about 95 nm. The gel film was fired in an electric furnace at a temperature of 773K for one hour in air.

Comparative Example 2 In the same manner as in Example 3, the coating treatment and the drying treatment were repeated three times to form a zinc oxide gel film having a thickness of about 100 nm. This gel membrane was subjected to 673K, 773K and 8
Each was fired for 1 hour in air in an electric furnace at a temperature of 73K. Each of the obtained fired films had a high sheet resistivity of 5 MΩ / □ or more.

[Brief description of the drawings]

FIG. 1 is an ultraviolet-visible absorption spectrum of a zinc oxide gel film obtained in Example 1 and a quartz glass substrate.

FIG. 2 shows a gel film (thickness: 95 nm) obtained in Example 1.
And an X-ray diffraction pattern of a film obtained by irradiating the gel film with laser beams having different energy densities.

FIG. 3 shows gel films having different thicknesses obtained in Example 1.
Energy density of 100 mJ / cm ² (a) and 150
An X-ray diffraction pattern of a film obtained by irradiating a laser beam of mJ / cm ² (b).

FIG. 4 is a graph showing the relationship between the energy density and the c-axis lattice constant when a 95-nm-thick gel film obtained in Example 1 is irradiated with laser light.

FIG. 5 shows different thicknesses of the gel films obtained in Example 1.
Energy density of 100 mJ / cm ² and 150 mJ / c
Ultraviolet-visible absorption spectrum of a film obtained by irradiating m ² laser light.

FIG. 6 shows an emission spectrum of a film obtained by irradiating a 95 nm-thick gel film obtained in Example 1 with laser beams having different energy densities by fluorescence spectroscopy.

FIG. 7 is an X-ray diffraction pattern of a gel film obtained in Example 2 and a film obtained by irradiating the gel film with laser beams having different energy densities.

FIG. 8 is a graph showing the electric resistivity of a gel film obtained in Example 3 and a film obtained by irradiating the gel film with laser beams having different energy densities.

FIG. 9 is an X-ray diffraction pattern of a film obtained by irradiating the gel film obtained in Example 4 with laser beams having different frequencies at different times.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 21/36 H01L 21/208

Claims (3)

(57) [Claims] 1. A method of manufacturing a semiconductor thin film by forming a transition metal chalcogenide-containing gel thin film on a substrate and then irradiating the thin film with an actinic ray to form a semiconductor thin film having an energy higher than the band gap of the transition metal chalcogenide. A method for producing a semiconductor thin film, comprising: irradiating a line to perform electronic excitation; and changing an energy density of an active ray at this time to control optical and electrical properties of a generated semiconductor thin film. 2. The method of claim 1, wherein the transition metal chalcogenide is Ti, V, C
r, Mn, Fe, Co, Ni, Cu, Zn, Zr, M
2. The method according to claim 1, comprising at least one selected from the group consisting of o, Ag, Cd, Ta, W, Ir, Eu and Sm, and at least one selected from O, S, Se and Te. The method for producing a semiconductor thin film according to the above. 3. The method of claim 1, wherein the transition metal chalcogenide is Li, Na,
3. The method for producing a semiconductor thin film according to claim 1, comprising at least one selected from the group consisting of K, B, Al, Ga, In, N, P, As and halogen.