JPH0759747B2 - Method for producing transparent conductive film - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing an In—Sn—O-based transparent conductive film.

(Prior Art) Conventionally, an In-Sn-O-based transparent conductive film (hereinafter referred to as an ITO film)
Is produced by a sputtering method, a vapor deposition method, a CVD method, or the like. Of these, the case of using the In-Sn alloy target by sputtering, but there is a case of using an oxide target obtained by mixing the SnO ₂ to an In ₂ O _3, in each case, the sputtering such as Ar during sputtering O _{2 in} an inert gas for performing
By mixing gas and adjusting the mixed amount, the O composition of the ITO film formed on the substrate is controlled to obtain good conductivity and transmittance.

(Problems to be solved by the invention) When an ITO film is manufactured by a sputtering method, if the substrate can be manufactured at a relatively low temperature of room temperature to 200 ° C., the ITO film is formed on a substrate such as a synthetic resin having low heat resistance It is possible because it is preferable. However, at such a low temperature, the ITO film tends to be an amorphous film or a film in which amorphous is mixed in the crystal, and the electric conductor is trapped in the dangling bond generated in the film at the time of energization, and the electric conductivity is generated. There is an inconvenience that the property deteriorates.

An object of the present invention is to improve the conductivity of an ITO film formed at a substrate temperature of room temperature to 200 ° C.

(Means for Solving the Problems) In the present invention, in a method of forming an In—Sn—O-based transparent conductive film on a substrate at room temperature to 200 ° C. by a sputtering method, O ₂ and H ₂ are added in a sputtering gas. The above problem is solved by mixing a mixed gas of O 2.

(Operation) A substrate heated to room temperature to 200 ° C in the sputter chamber and, for example, I
An n-Sn alloy target is provided, sputtering is performed by introducing a sputtering gas such as Ar gas, and an ITO film is formed on the substrate. In this sputtering method, the ITO film formed is in the state of amorphous or a mixture of crystalline and amorphous as described above, and the conductivity is poor. Therefore, in order to improve it, in the present invention. As for the sputtering, a mixed gas of H ₂ O gas and O ₂ gas was mixed in the sputtering gas to carry out the sputtering. When a mixed gas of the H ₂ O gas and O ₂ gas is mixed in the sputtering gas,
H atoms are taken into the amorphous ITO film formed on the substrate, and dangling bonds of atoms such as In, Sn, and O are compensated. Therefore, when electricity is applied to the ITO film, the number of electrons trapped in the dangling bonds is reduced, and the mobility and density of the electroconductor are increased, so that the conductivity is improved. When the substrate temperature is higher than 200 ° C., the ITO film is completely crystallized and H atoms are not taken in, so that the effect of introducing the mixed gas of H ₂ O gas and O ₂ gas is lost.

_{(Example) 10Wt% In 2 O 3 -SnO} 2 oxide target SnO ₂ is mixed to prepare a sputtering chamber and creating a sample of the ITO film by DC magnetron sputtering onto a substrate. Argon gas pressure during sputtering is 2 × 10 ^-3 Torr, ITO film thickness is 1500
The film forming rate was set to 900Å / min. The above conditions are the most typical method of manufacturing an ITO film which has been conventionally performed.

With the above conditions kept constant, O ₂ gas, H ₂ O gas, and a mixed gas of H ₂ O gas and O ₂ gas were mixed in Ar gas at various partial pressures to form a substrate at room temperature (20 ° C). Films were formed and the resistivity of each film was measured.

When mixing a mixed gas of H ₂ O gas and O ₂ gas, the partial pressure of H ₂ O gas is set to _two pressures of 1 × 10 ⁻⁵ Torr and 2 × 10 ⁻⁵ Torr, and the partial pressure of O ₂ gas is set. Was changed. IT obtained by this
The resistivity of the O film was as shown in the first figure. Since the type of gas are different, the gas pressure is different resistivity is minimized, the smallest resistivity values towards the mixed gas of the H ₂ O gas and the H ₂ O gas and O ₂ gas is O ₂ gas The value is smaller than the case. Although ITO film of less resistivity than be mixed only the H ₂ O gas in the sputtering gas only O ₂ gas is obtained, for example, in the case of ITO film for a liquid crystal display element, H ₂ in the film If O remains, H ₂ O acts as an oxidant due to heating when the liquid crystal is sealed, which causes a disadvantage that the resistivity of the ITO film increases. Therefore, it is preferable that the amount of H ₂ O gas mixed in the sputter gas is small, and from FIG. 1 as well, the mixed gas of O ₂ and H ₂ O is smaller than that of H ₂ O gas alone. It is preferable to use a mixed gas of O ₂ and H ₂ O because the same resistivity can be obtained with the amount of ₂ O gas mixed.

Next, in order to see how much H ₂ O gas needs to be introduced, the H ₂ O gas partial pressure was changed to form an ITO film on the substrate and the resistivity was measured. The results are shown in FIG. Resistivity values shown in the figure, O ₂ in each of the H ₂ O gas partial pressure
The minimum value (indicated by an arrow in FIG. 1) when the gas partial pressure is changed is shown. As you can see from this figure, H ₂ O introduced
The gas has the effect of lowering the resistivity even with a small amount of 5 × 10 ^-6 Torr, and the resistance becomes constant at 2 × 10 ^-5 Torr or more.

FIG. 3 shows the effect of substrate temperature on resistivity. Also in this case, the minimum resistivity at each substrate temperature is obtained and shown. As can be seen from the figure, the base coating temperature is room temperature to 200 ° C.
Then, the resistivity is improved when the mixed gas mixed with the H ₂ O gas is introduced than when the O ₂ gas is introduced. However, at a temperature higher than 200 ° C, the effect is the same as when only O ₂ gas is introduced, and there is no effect.

Although the In ₂ O ₃ —SnO ₂ oxide target was used as the target, the same effect can be obtained by using the In—Sn alloy target.

(Effects of the Invention) As described above, according to the present invention, in the method of forming an In-Sn-O-based transparent conductive film on a substrate at room temperature to 200 ° C by a sputtering method, O ₂ gas and since to mix with the gas by mixing the deposition of the H ₂ O gas, the H atom is incorporated into the in the film, an in, Sn, dangling bonds of atoms of O and the like is compensated, good conductivity There is an effect such as that a good ITO film can be obtained.

[Brief description of drawings]

FIG. 1 is a diagram showing the relationship between the kind of gas mixed in the sputter gas and the gas partial pressure, and FIG. 2 is a diagram showing the relationship between the H ₂ O gas partial pressure and the resistivity. FIG. 3 is a diagram showing the relationship between substrate temperature and resistivity.

Claims (1)

[Claims] 1. A method of forming an In-Sn-O-based transparent conductive film on a substrate at room temperature to 200 ° C. by a sputtering method, wherein a mixed gas of O ₂ and H ₂ O is mixed in the sputtering gas. A method for producing a transparent conductive film, comprising: