JPH05347108A - Transparent conductive film and its manufacture - Google Patents

Abstract

PURPOSE:To manufacture a transparent electrode having low resistivity at a low cost by radiating a laser light to a mixed gas made from a compound of Al and Sn in a specific divided pressure ratio and educing a transparent conductive film in which Al is doped into SnO2. CONSTITUTION:A mixed gas made from Al(CH3)3, Sn(CH3)4 and N2O as a row material for a transparent conductive film is enclosed in the reaction case 10 and the divided pressure of a compound of Al and Sn is adjusted to 0.1 to 0.7. A KrF eximer laser light L1 is radiated to the row material when a substrate 18 is at 250 degree centigrade. A SnO2 film 19 in a conduction of a circuit pattern in which Al is doped is educed on the substrate 18. The light transmittivity of the educed film 19 is 80% when the divided pressure ratio of Sn(CH3)4 to N2O is 1:5 and 100% when the divided pressure ratio is 1:20. The resistivity of the film turns to the minimum value when the divided pressure ratio of Al(CH3)3 to Sn(CH3)4 is 0.45. Thus, a transparent electrode having a low resistivity is manufactured at a low cost by mixing a very little amount of Al into SnO2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transparent conductive film which constitutes a transparent electrode in a liquid crystal display, a solar cell, a light receiving element and the like, and a manufacturing method thereof.

[0002]

2. Description of the Related Art SnO has long been used as a conductive film of this type.
₂ (tin dioxide) was known. However, although SnO ₂ is chemically stable, it has a relatively high resistance value. Therefore, in recent years, In, which is chemically unstable but has a low resistance value,
₂ O ₃ (indium oxide) and ITO (indium titanium oxide) are the mainstream.

[0003]

However, In ₂ O ₃ and IT
O is the raw material In (indium) and Ti (titanium)
However, there is a problem in that the conductive film itself is also expensive. The present invention has been made in view of the above-mentioned problems of the prior art, and an object thereof is to provide an inexpensive transparent conductive film having low resistivity and a method for manufacturing the same.

[0004]

In order to achieve the above object, in the transparent conductive film according to claim 1, SnO ₂ which is a constituent of the transparent conductive film is doped with Al. Is. In the method for producing a transparent conductive film according to claim 2, the partial pressure ratio of the Al compound and the Sn compound, which are raw materials of the transparent conductive film, is 0.1 to 0.7, preferably about 0.45. By irradiating the raw material gas adjusted to the above with a laser beam, the transparent conductive film in which SnO ₂ is doped with Al is projected onto the substrate.

According to a third aspect of the present invention, in the method according to the second aspect, Sn (CH ₃ ) _{4 is used} as a raw material for the transparent conductive film.
Or Sn (C ₂ H ₅ ) ₄ , Al (CH ₃ ) ₃ or Al (C ₂ H
₅ ) A mixed gas of ₃ and N ₂ O or O ₂ is used, the substrate temperature is 200 to 400 ° C., and the wavelength range is 150 to 400 nm.
The mixed gas is irradiated with the laser light.

[0006]

In the transparent conductive film having a structure in which SnO ₂ is doped with Al, as shown in FIG. 4, which shows the resistivity of the conductive film extruded in the method of this embodiment, the resistivity is as low as 0.45 Ωcm. Which is significantly lower than the resistivity of the In ₂ O ₃ film and the SnO ₂ film not doped with Al.

[0007]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 shows an embodiment of an apparatus for carrying out the method according to the invention. In this drawing, reference numeral 10 is provided with a heater 11 inside, and a window 12 for entering a laser beam is provided above.
In the reaction container provided with, a gas inlet 13 for supplying the raw material gas into the reaction container 10 is provided on the side surface of the reaction container 10. Above the window 12, there is a condenser lens 14,
The mask 16 on which the electrode circuit pattern is formed as a light-transmitting portion is arranged in the vertical direction, and the KrF excimer laser light (wavelength 2
(49 nm) L ₁ is irradiated. A glass substrate 18 is placed on the heater 11,
The mask 16 is irradiated with the rF excimer laser light L _1.
The electrode circuit pattern formed on the substrate 18 forms an image on the substrate 18. That is, on the surface of the substrate 18, only the region corresponding to the electrode circuit pattern shape of the mask 16 is irradiated with the laser light L ₁ , and only the laser light irradiation region on the substrate surface is in the excited state. Therefore, the raw material gas in the container 10 is photodecomposed at the condensing point P, and the radicals generated thereby are recombined on the substrate in the excited state to form the film 19.
Breaks out.

FIG. 2 shows another embodiment of the device for carrying out the method according to the invention. A window 12A for entering a laser beam is also provided on the side surface of the reaction vessel 10, and an ArF excimer laser beam (wavelength 193n is introduced into the reaction vessel 10 through the window 12A.
m) L ₂ is above substrate 18 in reaction vessel 10
It is designed to be irradiated in parallel with. Reference numeral 14A is a condenser lens for condensing the laser light L ₂ from the side above the substrate 18 to increase the energy density of the laser light. In the second embodiment, the ArF excimer laser light L ₂ incident parallel to the substrate 18 imparts energy for photodecomposing the source gas, and the KrF excimer laser light L ₁ incident perpendicularly to the substrate 18 is a radical. Is activated, and the interface of the substrate 18 is excited, so that there is an effect that the film deposition rate onto the substrate 18 is increased. In FIG. 2, the laser light L ₂ radiated from the side is described as ArF excimer laser light, but KrF excimer laser light may be used instead of ArF excimer laser light.

Experimental Example 1 Using the apparatus shown in FIG. 1, 3 Torr of Al (CH ₃ ) ₃ , 7 Tor was placed in the reaction vessel 10.
A raw material gas (total pressure 20 Torr) composed of Sn (CH ₃ ) ₄ of 10 r and N ₂ O of 10 Torr is charged, and the substrate temperature is set to 2
At 50 ° C., the energy of the KrF excimer laser beam L ₁ is 100 mJ, and the laser pulse repetition rate is 20 pp.
When laser irradiation was performed for 15 minutes, the substrate 18
A SnO ₂ film in the form of a circuit pattern doped with Al was projected on the top. This membrane is shown in a drawing-substitute photograph (FIG. 8) taken by the inventor. Then, when the light transmittance of the film that was projected was examined, as shown in FIG.
When the partial pressure ratio of n (CH ₃ ) ₄ and N ₂ O was 1: 5, the transmittance was 80%, but when the partial pressure ratio was 1:20, it was about 100%. It was also found that the light transmittance increased as the partial pressure of N ₂ O increased.

Next, when the resistivity of the film was measured, the result as shown in FIG. 4 was obtained. That is, as shown in FIG. 4, when the partial pressure ratio of Al (CH ₃ ) ₃ and Sn (CH ₃ ) ₄ is about 0.45, the minimum resistivity is 0.45 Ωcm,
The resistivity increased when the voltage division ratio was changed to either large or small. By the way, in “Thin Film Handbook (Ohmsha), Japan Society for the Promotion of Science, 1983”, the resistivity of the In ₂ O ₃ film formed by vacuum deposition is 2.8 Ωcm, and the resistivity of the In ₂ O ₃ film formed by the CVD method. Is 3 Ωcm, and the resistivity of the SnO ₂ film (not containing Al) formed by the CVD method is 72
The data shows that the resistivity of the SnO ₂ film (not containing Al) formed by the spray method is 10.6 Ωcm, and the resistivity obtained in this experimental example is 0.45 Ωcm.
The low value indicates that the resistivity is improved by one digit or more as compared with the conventional In ₂ O ₃ film and SnO ₂ film.

As can be seen from the line A in FIG. 5, the resistivity of the film is about 6 Ωcm when the partial pressure ratio of N ₂ O and Sn (CH ₃ ) ₄ is 5: 1 and the partial pressure ratio is 20: 1. In case of, 15Ωcm
Became. It can be seen that the resistivity decreases as the partial pressure of N ₂ O decreases. The line B in the figure indicates a substrate temperature of 300.
The resistivity characteristic is shown when the same experiment is performed at a temperature of ℃, and the resistivity is as low as 5 Ωcm when the partial pressure ratio is 5: 1. Furthermore, from FIG. 5, N ₂ O and Sn (CH ₃ ) ₄
It can be seen that the partial pressure ratio and the resistivity of are changing linearly.

FIG. 6 is a diagram showing the distribution dependence of the composition ratio of the film. The composition ratio of Sn and O ₂ changes at the boundary of the partial pressure ratio of the source gas of 10: 1. This is presumably because when the partial pressure of N ₂ O is low, the supply of excited coordination atoms is insufficient, and Sn that is not bonded to O ₂ exists in the film. When the substrate temperature is 300 ° C., Sn / O ₂ is closer to 1.0 than when the substrate temperature is 250 ° C., so that the number of dangling bonds is reduced and the film has good weather resistance. I understand. The partial pressure ratio of N ₂ O and Sn (CH ₃ ) ₄ is 1: 5.
In the case of, the line width and film thickness of the circuit pattern film were, as shown in FIG. 7, a line width of 50 μm and a film thickness of 1300Å.

[Experimental Example 2] Using the apparatus shown in FIG. 2, under the same conditions as in Experimental Example 1, Kr was measured from the vertical direction of the substrate 18.
When the F excimer laser light L ₁ was irradiated and the ArF excimer laser light L ₂ was irradiated from the side, the Al-doped SnO ₂ film protruding on the substrate 18 had a protruding speed in the case of Experimental Example 1. It became five times. That is, it was confirmed that the manufacturing time of the transparent conductive film can be shortened.

[0014]

As is apparent from the above description, according to the present invention, a small amount of Al is mixed into SnO _{2 which} can be produced from an inexpensive metal compound, so that expensive In ₂ O _{3 can be obtained.}
Since it has a lower resistivity than ITO or ITO, it is possible to provide a transparent electrode having a low resistivity at a low cost.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a first embodiment of an apparatus for carrying out the method of the present invention.

FIG. 2 is a schematic diagram of a second embodiment of the apparatus for carrying out the method of the invention.

FIG. 3 is a diagram showing the light transmittance of a transparent conductive film.

FIG. 4 is a diagram showing the relationship between the partial pressure ratio of Al (CH ₃ ) ₃ and Sn (CH ₃ ) ₄ and the film resistivity.

FIG. 5 is a graph showing the relationship between the partial pressure ratio of N ₂ O and Sn (CH ₃ ) ₄ and the film resistivity.

FIG. 6 is a diagram showing the relationship between the partial pressure ratio of N ₂ O and Sn (CH ₃ ) ₄ and the composition ratio of Sn / O ₂ .

FIG. 7 is a diagram showing a line width and a film thickness of a protruding conductive film.

FIG. 8 is a drawing-substitute photograph showing an enlarged view of a film formed in Experimental Example 1.

[Explanation of symbols]

10 ArF excimer laser light parallel to irradiate the reaction vessel 11 KrF excimer laser beam L ₂ substrate is irradiated perpendicularly to the window 13 feed gas inlet 16 mask 18 the substrate L ₁ substrate heater 12,12A laser beam for incidence

[Procedure amendment]

[Submission date] October 29, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] Figure 8

[Correction method] Change

[Correction content]

FIG. 8 is a photograph as a substitute for a drawing showing an enlarged fine pattern formed on a substrate.

Claims (3)

[Claims] 1. A transparent conductive film, characterized in that SnO ₂ is doped with Al. 2. A source gas adjusted to have a partial pressure ratio of an Al compound and a Sn compound, which are raw materials of a transparent conductive film, of 0.1 to 0.7, preferably about 0.45, is irradiated with laser light. A method for producing a transparent conductive film, which comprises irradiating and causing a transparent conductive film in which SnO ₂ is doped with Al to be projected onto a substrate. 3. The material of the transparent conductive film is Sn (CH).
₃ ) ₄ or Sn (C ₂ H ₅ ) ₄ , Al (CH ₃ ) ₃ or Al
Using a mixed gas of (C ₂ H ₅ ) ₃ and N ₂ O or O ₂ ,
The substrate temperature is 200 to 400 ° C., and the wavelength range is 150.
The method for producing a transparent conductive film according to claim 2, wherein the mixed gas is irradiated with a laser beam of ˜400 nm.