CN100415930C - A kind of preparation method of amorphous transparent conductive oxide thin film - Google Patents

Abstract

The invention relates to a method for preparing an amorphous molybdenum-doped indium oxide (IMO) transparent conductive oxide film by using a reactive DC magnetron sputtering method at a substrate temperature of 0-30°C. The invention uses ordinary glass as the substrate, utilizes molybdenum-indium-doped metal mosaic target, and adopts reactive direct current magnetron sputtering technology at the substrate temperature of 0-30°C, under proper working pressure, oxygen partial pressure, sputtering current and sputtering voltage IMO thin films with amorphous structure were prepared under the conditions. The prepared film has excellent photoelectric properties such as low resistivity, high transmittance and high carrier mobility. The thin film obtained by the method of the invention has good application prospects in the field of new photoelectric devices.

Description

A kind of preparation method of amorphous transparent conductive oxide thin film

technical field

The invention belongs to the technical field of transparent conductive oxide films, and in particular relates to a method for preparing amorphous molybdenum-doped indium oxide (IMO) transparent conductive oxide films by using a reactive DC magnetron sputtering method.

Background technique

Transparent conductive oxide (TCO) thin film is a highly degenerate semiconductor material, which is widely used in the field of optoelectronic devices such as flat panel displays and solar cells due to its unique combination of transparency and conductivity. The most representative materials are In ₂ O ₃ :Sn(ITO), SnO ₂ :F and ZnO:Al(AZO) films. TCO thin film materials generally have a high carrier concentration, the Fermi level ( _EF ) is above the conduction band level ( _EC ), and the resistivity can be as low as 10 ^-4 Ω·cm; and it has a wide band gap (>3eV), so that the film has high transmittance (>80%) in the range of visible light and near-infrared light.

TCO thin films are usually prepared at a relatively high substrate temperature (300-400° C.) in order to obtain high conductivity and high transmittance. However, this substrate temperature condition limits the application of TCO thin films in the field of new organic optoelectronic devices, such as ultra-light liquid crystal displays using thermosensitive flexible polymer substrates, heterojunction solar cells, and high-efficiency electron- Hole injection as an anode connection material for organic light-emitting diodes. During the fabrication of these devices, high-temperature film-forming conditions will largely degrade the performance of the devices. Therefore, how to prepare TCO films at a lower substrate temperature and maintain good optoelectronic properties is of great significance to meet the development needs of a wider optoelectronic device industry.

Therefore, the preparation of amorphous IMO transparent conductive oxide thin films with high valence difference at room temperature is a research goal with great application value, and there is no report of this type of research structure.

Contents of the invention

The object of the present invention is to propose a method for preparing an amorphous IMO transparent conductive oxide film with industrial productivity and good process stability at room temperature.

The method for preparing the amorphous IMO transparent conductive oxide thin film proposed by the present invention uses the DC magnetron sputtering method in the prior art to prepare the amorphous IMO transparent conductive oxide thin film. The preparation of the present invention is under the condition that the temperature of the substrate is 0-30°C, the molybdenum-indium-doped metal mosaic target is used as the target material, and the common glass is used as the substrate, and the Ar ion beam is irradiated on the target material through the reactive DC magnetron sputtering method. , the target is sputtered, the sputtering current is 100-150mA, the sputtering voltage is 400-500V, the working pressure in the reaction chamber is (2.5-4.5)×10 ^-1 Pa, and the partial pressure percentage of O ₂ reaction gas is P (O ₂ )[=PO ₂ /(PO ₂ +PAr)] is 8.0-18.0% and the sputtering time is 1-15 minutes to form a molybdenum-doped indium oxide transparent conductive oxide film with an amorphous structure. The substrate temperature of the present invention is in the range of 0-30°C.

The better preparation conditions of the present invention are as follows:

In the present invention, the substrate temperature is 15-25°C.

In the present invention, the partial pressure percentage of the O ₂ reaction gas is 10-16.0%.

In the present invention, during reactive direct current magnetron sputtering coating, the sputtering conditions are: sputtering current 120-140mA, sputtering voltage 400-450V, and sputtering time 3-10 minutes.

In the present invention, _O2 and Ar gas are passed into the reaction chamber through a variable gas conduction valve, and the variable gas conduction valve is the prior art for direct current magnetron sputtering coating to pass into the gas.

The thickness of the amorphous transparent conductive oxide film prepared by the method of the invention is 60-250nm, and the film thickness can be controlled by controlling the sputtering time as required.

The mosaic target of the present invention is prepared as follows:

Place the calculated and weighed metal indium strip with a weight of 448 grams and a purity of 99.99% on a red copper circular plate surrounded by stainless steel strips, put it in a vacuum chamber, and place it in a vacuum environment of 3×10 ^-3 Pa at 200°C The indium bar is melted into a round target of indium metal with a diameter of 51 mm and a thickness of 3 mm at a temperature of 1mm, length 3mm; molybdenum wire with a diameter of 1mm, a length of 3mm, and a purity of 99.99% is embedded in the small hole to form an indium-molybdenum metal mosaic target with a ratio of molybdenum/indium atoms of 2.1at%.

Since the sputtered particles generated in the sputtering target are confined within the discharge ring during the magnetron sputtering process, the doped Mo must be embedded in the discharge ring, and the ratio of Mo to metal In must be in accordance with the discharge ring. Metal In in the ring is used as a reference. The inner radius of the discharge ring is 1.3cm, and the outer radius is 1.7cm. Therefore, 6 holes with a diameter of 1mm are drilled in the discharge ring, and molybdenum wires are embedded in them. In this way, the molybdenum doping amount of the target can be calculated as follows:

Indium density p _In =7.31g/cm ³ molecular weight M _In =114.82

Molybdenum density ρ _Mo =10.22g/cm ³ molecular weight M _Mo =95.94

Discharge ring area: S ₁ = π(1.7 ² -1.3 ² ) = 3.77cm ²

Cross-sectional area of a single molybdenum wire: S ₂ =π×0.05 ² =0.00785cm ²

The atomic ratio of molybdenum and indium is thus calculated:

Atomic Number of Indium: $N_{\mathrm{In}}={\mathrm{no}}_{\mathrm{In}}\&times;N_0=\frac{m_{\mathrm{In}}}{m_{\mathrm{In}}}\&times;N_0=\frac{{\mathrm{<figure-callout\; id="1"\; label="S"\; filenames="C20051002595700071.png,C20051002595700072.png"\; state="\{\{state\}\}">S</figure-callout>}}_1\&times;d\&times;{\mathrm{\&rho;}}_{\mathrm{In}}}{m_{\mathrm{In}}}\&times;N_0=0.240d{N}_0$

The atomic number of a single molybdenum wire:

${\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; Mo</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; \&times;</span>{\mathrm{<span\; class="notranslate">\; no</span>}}_{\mathrm{<span\; class="notranslate">\; Mo</span>}}<span\; class="notranslate">\; \&times;</span>{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; \&times;</span>\frac{{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; Mo</span>}}}{{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; Mo</span>}}}<span\; class="notranslate">\; \&times;</span>{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; \&times;</span>\frac{{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="S"\; filenames="C20051002595700072.png"\; state="\{\{state\}\}">S</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; d</span>}<span\; class="notranslate">\; \&times;</span>{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; Mo</span>}}}{{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; Mo</span>}}}<span\; class="notranslate">\; \&times;</span>{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0.836</span>}<span\; class="notranslate">\; \&times;</span>{\mathrm{<span\; class="notranslate">\; 10</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 3</span>}}\mathrm{<span\; class="notranslate">\; d</span>}{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}$

Atomic numbers of 6 molybdenum wires:

${\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; Mo</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 6</span>}<span\; class="notranslate">\; \&times;</span>{\mathrm{<span\; class="notranslate">\; no</span>}}_{\mathrm{<span\; class="notranslate">\; Mo</span>}}<span\; class="notranslate">\; \&times;</span>{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 6</span>}<span\; class="notranslate">\; \&times;</span>\frac{{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; Mo</span>}}}{{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; Mo</span>}}}<span\; class="notranslate">\; \&times;</span>{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 6</span>}<span\; class="notranslate">\; \&times;</span>\frac{{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="S"\; filenames="C20051002595700072.png"\; state="\{\{state\}\}">S</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; d</span>}<span\; class="notranslate">\; \&times;</span>{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; Mo</span>}}}{{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; Mo</span>}}}<span\; class="notranslate">\; \&times;</span>{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 5.017</span>}<span\; class="notranslate">\; \&times;</span>{\mathrm{<span\; class="notranslate">\; 10</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 3</span>}}\mathrm{<span\; class="notranslate">\; d</span>}{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}$

Where N ₀ is Avogadro's constant, and d is the thickness of the mosaic target.

so, $\frac{N_{\mathrm{Mo}}}{N_{\mathrm{In}}}=0.0209=2.1\%$ (6 aluminum wires).

The experimental results show that the IMO film prepared on the glass surface by reactive DC magnetron sputtering at room temperature has the characteristics of low resistivity, high optical transparency in the visible light range and high carrier mobility, which is comparable to that of ITO products. performance. The method of the invention has industrial production prospects and good process stability, and is a new method for preparing the IMO transparent conductive oxide film at room temperature to ensure the excellent performance of the device made of the film.

Description of drawings

Fig. 1 is the x-ray diffraction spectrum of the amorphous IMO thin film prepared by the method of the present invention.

Figure 2 is a graph showing the influence of different oxygen partial pressure percentages on the resistivity and carrier concentration of IMO films.

Fig. 3 is the transmission spectrum at 300-900nm of IMO films prepared with different oxygen partial pressure percentages P(O ₂ ).

Detailed ways

Concrete implementation steps of the present invention are as follows:

Example 1, preparation of molybdenum-doped indium oxide target: In metal with a purity of 99.99% is melted into a target, and 2 wt% of molybdenum wire with the same purity of 99.99% is uniformly and symmetrically embedded. The target diameter is 51mm and the thickness is 2.5mm . The substrate is a common glass slide, which has been washed by pure water, alcohol and acetone ultrasonic waves for 15 minutes each.

Substrate temperature: 15°C.

The distance between the target and the substrate was fixed at 35mm.

Before film deposition, the reaction chamber is evacuated to below 2×10 ^-3 Pa, and then O ₂ and Ar gas are passed into the reaction chamber through a variable gas conduction valve. The working pressure in the reaction chamber is 2.5×10 ^-1 Pa, the sputtering current is 100mA, the sputtering voltage is 400V, and the percentage content of O ₂ reaction gas is controlled P(O ₂ )[=PO ₂ /(PO ₂ +PAr) ] is 8.0%. The films were prepared on ordinary glass slides.

The sputtering time is 3 minutes, and the film thickness is 80 nm.

Example 2, at a substrate temperature of 25°C, an amorphous IMO thin film was prepared in the same manner as in Example 1 under the following conditions: the sputtering current was 150mA, the sputtering voltage was 500V, and the _O2 and Ar gas are passed into the O ₂ reaction chamber and the percentage content P(O ₂ ) of the partial pressure of the O ₂ gas is controlled to be 18.0%. The sputtering time is 8 minutes, and the film thickness is 160 nm.

The thickness d of the film was measured with a surface profiler (Kosaka ET3000 type), and the sheet resistance R _□ of the sample was measured with a four-probe instrument (BD-90 type), so as to calculate the resistivity ρ of the film. At room temperature, the Hall effect of the thin film was measured using a Hall tester (Bio-Rad Microscience HL5500Hall system), so as to obtain the carrier mobility and carrier concentration of the thin film. X-ray diffractometer (XRD) (Rigaku D/max-rB type, Cu Kα ray source) was used to analyze the crystal structure of the film; the surface of the film could be analyzed by atomic force microscope (AFM) (Park Scientific Instrument, AutoProbe CP, USA) shape.

Claims (6)

1. the preparation method of a non-crystal transparent conductive oxide film is characterized in that at substrate temperature being to utilize the reaction direct current magnetron sputtering process to prepare film under the 0-30 ℃ of condition, and concrete preparation condition is as follows:

(1) substrate temperature is 0-30 ℃;

(2) molybdenum indium metal mosaic target is mixed in employing, promptly evenly inlays the molybdenum silk in the aperture in the magnetron sputtering area on indium metal circle target, and molybdenum/phosphide atom is than being 2.1at%;

(3) the magnetically controlled DC sputtering electric current is 100～150mA, and sputtering voltage is 400-500V, and sputtering time is 1-15 minute;

(4) with O ₂Making operating pressure with Ar gas feeding reaction chamber is 2.5 * 10 ^-1Pa-4.5 * 10 ^-1Pa, control O ₂The dividing potential drop percentage composition of reactant gases is 8.0～18.0%.

2. the preparation method of non-crystal transparent conductive oxide film according to claim 1 is characterized in that substrate temperature is 15-25 ℃.

3. the preparation method of non-crystal transparent conductive oxide film according to claim 1 is characterized in that O ₂The dividing potential drop percentage composition of reactant gases is 10-16.0%.

4. the preparation method of non-crystal transparent conductive oxide film according to claim 1, when it is characterized in that reacting the magnetically controlled DC sputtering plated film, sputtering condition is: sputtering current 120～140mA, sputtering voltage 400-450V, sputtering time 3-10 minute.

5. the preparation method of non-crystal transparent conductive oxide film according to claim 1 is characterized in that by variable conductance valve O ₂Feed reaction chamber with Ar gas.

6. preparation method according to claim 1 is characterized in that the non-crystal transparent conductive oxide film thickness that this method makes is 60-250nm.

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