Conductive silver alloy for ultrathin transparent film and conductive silver alloy sputtering target material thereof

Abstract

The invention discloses a conductive silver alloy for an ultrathin transparent film and a conductive silver alloy sputtering target material thereof. The conductive silver alloy contains 2-15 mol% of elements for promoting nucleation of a silver film, and the balance of Ag and inevitable impurities. The element for promoting the nucleation of the silver film is any one of Mg, Al, Cu, Zn, Sn and Mn. The conductive silver alloy sputtering target material is prepared by smelting, pouring, rolling, machining and magnetron sputtering deposition of the conductive silver alloy. According to the technical scheme, silver is alloyed by promoting nucleation elements Mg, Al, Cu, Zn, Sn or Mn of the silver film, and the conductivity and visible light transmittance of the silver film are remarkably improved under the condition that the thickness is smaller than 10 nm.

Description

1. Technical field:

[0001] The invention belongs to the technical field of metal materials, and in particular relates to a conductive silver alloy for an ultra-thin transparent film and a conductive silver alloy sputtering target material thereof. 2. Background technology:

[0002] At present, touch screens mainly use indium tin oxide (ITO) as a transparent conductive material. However, the brittleness of ITO can easily cause the impedance of curved or flexible touch screens to increase rapidly, resulting in poor stability; the low conductivity of ITO can also cause the sensitivity of medium and large touch screens to decrease. At the same time, due to its own brittleness and too low work function (it is difficult to form a good ohmic contact in organic semiconductor devices), traditional ITO oxide transparent conductive films can no longer meet the needs of flexible electronic devices. Therefore, finding alternative materials for oxide transparent conductive films is an urgent need for the development of the semiconductor display industry.

[0003] Silver film has good flexibility and low resistivity. When the film thickness is less than a certain value, it has a high optical transmittance in the visible light range, making it an ideal transparent conductive material. Usually, under the condition of continuous film, the visible light transmittance of silver film increases as its thickness decreases. However, when the thickness of the silver film is less than 10nm, it will present a discontinuous cluster state, resulting in a higher resistivity; the discontinuity of the film will also cause its transmittance to drop significantly at specific wavelengths. Therefore, under the condition of a thickness of less than 10nm, improving the conductivity and visible light transmittance of transparent silver films is the key to their widespread application. 3. Summary of the invention:

[0004] The technical problem to be solved by the present invention is: in view of the shortcomings of high resistivity and low transmittance of silver thin film under the condition of thickness less than 10nm, the present invention provides a conductive silver alloy for ultra-thin transparent film and a conductive silver alloy sputtering target thereof. The technical solution of the present invention alloys silver by promoting the nucleation elements Mg, Al, Cu, Zn, Sn or Mn of the silver thin film, and significantly improves the conductive performance and visible light transmittance of the silver thin film under the condition of thickness less than 10nm.

[0005] In order to solve the above problems, the technical solution adopted by the present invention is:

[0006] The invention provides a conductive silver alloy for ultra-thin transparent film. The conductive silver alloy contains 2-15% molar percentage of elements promoting silver film nucleation, and the remainder is Ag and inevitable impurities.

[0007] According to the above-mentioned conductive silver alloy for ultra-thin transparent film, the element promoting the nucleation of silver thin film is any one of Mg, Al, Cu, Zn, Sn and Mn (preferably Mg and Mn).

[0008] In addition, a conductive silver alloy sputtering target material for ultra-thin transparent film is provided, wherein the conductive silver alloy sputtering target material is prepared by melting, pouring, rolling, machining and magnetron sputtering deposition of the above conductive silver alloy.

[0009] According to the above-mentioned conductive silver alloy sputtering target for ultra-thin transparent film, the preparation method of the conductive silver alloy sputtering target is:

[0010] a. Weighing each single raw material according to the element composition ratio of the above conductive silver alloy, then loading each single raw material into a graphite or quartz crucible in an induction melting furnace, melting and pouring under vacuum or argon atmosphere to obtain a conductive silver alloy ingot;

[0011] b. rolling the conductive silver alloy ingot obtained in step a at room temperature, and then heat treating it under vacuum or argon protection to obtain a conductive silver alloy slab with fine grains;

[0012] c. machining the conductive silver alloy slab obtained in step b to obtain a conductive silver alloy sputtering target;

[0013] d. The conductive silver alloy sputtering target obtained in step c is subjected to magnetron sputtering deposition to obtain an ultra-thin transparent conductive silver alloy film, wherein the thickness of the obtained ultra-thin transparent conductive silver alloy film is ≤10 nm.

[0014] According to the above-mentioned conductive silver alloy sputtering target for ultra-thin transparent film, the temperatures of melting and pouring in step a are both 900-1100°C.

[0015] According to the above-mentioned conductive silver alloy sputtering target for ultra-thin transparent film, the rolling in step b is cross rolling, the rolling passes are 3 to 15, and the deformation amount of each pass is 5 to 25%.

[0016] According to the above-mentioned conductive silver alloy sputtering target for ultra-thin transparent film, the heat treatment temperature in step b is 300-600°C.

[0017] The positive beneficial effects of the present invention are:

[0018] 1. The technical solution of the present invention alloys silver with silver nucleation elements Mg, Al, Cu, Zn, Sn or Mn, which promotes the silver film nucleation, and significantly improves the continuity of the silver film under the condition of a thickness of less than 10nm, thereby improving the conductivity and visible light transmittance of the ultra-thin transparent silver film.

[0019] 2. The technical solution of the present invention melts and casts silver alloy under vacuum or argon atmosphere, prepares silver alloy target blank by cross-rolling technology at room temperature, and performs heat treatment under vacuum or argon protection conditions, which can not only avoid the problems of oxygen increase during silver alloy casting in air atmosphere and oxygen increase during thermal deformation, but also effectively improve the organizational uniformity of the silver alloy target and the quality of the sputtering deposited film, thereby improving the conductivity and visible light transmittance of the ultra-thin transparent silver film.

[0020] 3. The sheet resistance of the ultra-thin transparent silver film prepared by the technical solution of the present invention is ≤100Ω / sq, the transmittance at a wavelength of 450nm is ≥75%, and the transmittance at a wavelength of 550nm is ≥65%, showing excellent electrical conductivity and visible light transmittance. 4. Description of the drawings:

[0021] Figure 1 Microscopic morphology of the ultra-thin silver and silver alloy films prepared in Comparative Example 1, Example 2 and Example 4 of the present invention;

[0022] Depend on Figure 1 It can be seen that the ultra-thin silver alloy films prepared in Examples 2 and 4 of the present invention have fine and uniform grains and good continuity, and the film quality is significantly better than the ultra-thin silver film prepared in Comparative Example 1.

[0023] Figure 2 The sheet resistance of the ultra-thin silver and silver alloy films prepared in Comparative Example 1, Example 2, Example 4 and Example 6 of the present invention;

[0024] Depend on Figure 2 It can be seen that the square resistance of the ultra-thin silver alloy films prepared in Examples 2, 4 and 6 of the present invention is 125Ω / sq, 75Ω / sq and 79Ω / sq, which are significantly lower than 540Ω / sq of the ultra-thin silver film prepared in Comparative Example 1, showing excellent conductive properties.

[0025] Figure 3 The transmittance of the silver alloy thin films prepared in Comparative Example 1, Example 2, Example 4 and Example 6 of the present invention;

[0026] Depend on Figure 3 It can be seen that the transmittance of the ultrathin silver alloy films prepared in Examples 2, 4 and 6 of the present invention in the visible light range is significantly higher than that of the ultrathin silver film prepared in Comparative Example 1, showing excellent light transmittance performance; the transmittance of the ultrathin silver alloy films prepared in Examples 2, 4 and 6 at a wavelength of 450nm is 75.4%, 75.9% and 73.1%, which is significantly higher than 63.8% of the ultrathin silver film prepared in Comparative Example 1; the transmittance of the ultrathin silver alloy film prepared in Example 6 at a wavelength of 550nm is 67.4%, which is significantly higher than 57.1% of the ultrathin silver film prepared in Comparative Example 1. V. Specific implementation methods:

[0027] The present invention is further described below in conjunction with embodiments, but the protection scope of the technical solution of the present invention is not limited thereto.

[0028] Comparative Example 1:

[0029] A method for preparing an ultra-thin silver film, the detailed steps are as follows:

[0030] a. Weigh the silver raw material, then put it into a graphite crucible in an induction melting furnace, heat it to 1050° C. in an argon atmosphere for melting, and then pour it at this temperature to obtain a silver ingot;

[0031] b. The silver ingot obtained in step a is cross-rolled for 5 times at room temperature with a deformation of 20% per pass, and then heat-treated at 500° C. under argon protection to obtain a silver slab;

[0032] c. machining the silver slab obtained in step b to obtain a silver sputtering target;

[0033] d. The silver sputtering target obtained in step c is subjected to magnetron sputtering deposition to obtain a silver film with a thickness of 6 nm.

[0034] Embodiment 1:

[0035] The conductive silver alloy used for the ultra-thin transparent film of the present invention is expressed in terms of molar percentage, wherein the content of the silver alloy is 2% Mg, and the remainder is Ag and inevitable impurities.

[0036] Embodiment 2:

[0037] The conductive silver alloy sputtering target for ultra-thin transparent film is prepared by using the conductive silver alloy described in Example 1 of the present invention. The detailed steps are as follows:

[0038] a. Weighing Ag and Mg single-substance raw materials according to the element composition ratio of the conductive silver alloy described in Example 1, and then loading them into a graphite crucible in an induction melting furnace, heating them to 1050° C. for melting under an argon atmosphere, and then pouring them at the same temperature after melting to obtain a conductive silver alloy ingot;

[0039] b. The conductive silver alloy ingot obtained in step a is cross-rolled for 5 times at room temperature with a deformation of 20% per pass, and then heat-treated at 500° C. under argon protection to obtain a conductive silver alloy slab;

[0040] c. machining the conductive silver alloy slab obtained in step b to obtain a conductive silver alloy sputtering target;

[0041] d. The conductive silver alloy sputtering target obtained in step c is subjected to magnetron sputtering deposition to obtain an ultra-thin transparent conductive silver alloy film with a thickness of 6 nm.

[0042] Embodiment 3:

[0043] The conductive silver alloy used for the ultra-thin transparent film of the present invention is expressed in terms of molar percentage, wherein the content of Mn in the silver alloy is 2%, and the remainder is Ag and inevitable impurities.

[0044] Embodiment 4:

[0045] The conductive silver alloy sputtering target for ultra-thin transparent film is prepared by using the conductive silver alloy described in Example 3 of the present invention. The detailed steps are as follows:

[0046] a. Weigh Ag and Mn single-substance raw materials according to the element composition ratio of the conductive silver alloy described in Example 3, then load them into a graphite crucible in an induction melting furnace, heat them to 1050° C. in an argon atmosphere for melting, and then cast them at this temperature after melting to obtain a conductive silver alloy ingot;

[0047] b. The conductive silver alloy ingot obtained in step a is cross-rolled for 5 times at room temperature with a deformation of 20% per pass, and then heat-treated at 500° C. under argon protection to obtain a conductive silver alloy slab;

[0048] c. machining the conductive silver alloy slab obtained in step b to obtain a conductive silver alloy sputtering target;

[0049] d. The conductive silver alloy sputtering target obtained in step c is subjected to magnetron sputtering deposition to obtain an ultra-thin transparent conductive silver alloy film with a thickness of 6 nm.

[0050] Embodiment 5:

[0051] The conductive silver alloy used for the ultra-thin transparent film of the present invention is expressed in terms of molar percentage, wherein the content of Mn in the silver alloy is 8%, and the remainder is Ag and inevitable impurities.

[0052] Embodiment 6:

[0053] The conductive silver alloy sputtering target for ultra-thin transparent film is prepared by using the conductive silver alloy described in Example 5 of the present invention. The detailed steps are as follows:

[0054] a. Weigh Ag and Mn single-substance raw materials according to the element composition ratio of the conductive silver alloy described in Example 5, and then load them into a graphite crucible in an induction melting furnace, heat them to 1050° C. in an argon atmosphere for melting, and then cast them at this temperature after melting to obtain a conductive silver alloy ingot;

[0055] b. The conductive silver alloy ingot obtained in step a is cross-rolled for 5 times at room temperature with a deformation of 20% per pass, and then heat-treated at 500° C. under argon protection to obtain a conductive silver alloy slab;

[0056] c. machining the conductive silver alloy slab obtained in step b to obtain a conductive silver alloy sputtering target;

[0057] d. The conductive silver alloy sputtering target obtained in step c is subjected to magnetron sputtering deposition to obtain an ultra-thin transparent conductive silver alloy film with a thickness of 6 nm.

[0058] Embodiment 7:

[0059] The conductive silver alloy used for the ultra-thin transparent film of the present invention is expressed in terms of molar percentage, wherein the content of Mg in the silver alloy is 10%, and the remainder is Ag and inevitable impurities.

[0060] Embodiment 8:

[0061] The conductive silver alloy sputtering target for ultra-thin transparent film is prepared by using the conductive silver alloy described in Example 7 of the present invention. The detailed steps are as follows:

[0062] a. Weighing Ag and Mg single-substance raw materials according to the element composition ratio of the conductive silver alloy described in Example 7, and then loading them into a graphite crucible in an induction melting furnace, heating them to 1100° C. for melting under an argon atmosphere, and then pouring them at the same temperature after melting to obtain a conductive silver alloy ingot;

[0063] b. The conductive silver alloy ingot obtained in step a is cross-rolled for 6 times at room temperature with a deformation of 16% per pass, and then heat-treated at 500° C. under argon protection to obtain a conductive silver alloy slab;

[0064] c. machining the conductive silver alloy slab obtained in step b to obtain a conductive silver alloy sputtering target;

[0065] d. The conductive silver alloy sputtering target obtained in step c is subjected to magnetron sputtering deposition to obtain an ultra-thin transparent conductive silver alloy film with a thickness of 5 nm.

[0066] Embodiment 9:

[0067] The conductive silver alloy used for the ultra-thin transparent film of the present invention is expressed in terms of molar percentage, wherein the content of Cu in the silver alloy is 12%, and the remainder is Ag and inevitable impurities.

[0068] Embodiment 10:

[0069] The conductive silver alloy sputtering target for ultra-thin transparent film is prepared by using the conductive silver alloy described in Example 9 of the present invention. The detailed steps are as follows:

[0070] a. Weighing Ag and Cu single-substance raw materials according to the element composition ratio of the conductive silver alloy described in Example 9, and then loading them into a graphite crucible in an induction melting furnace, heating them to 1100° C. for melting under an argon atmosphere, and then pouring them at the same temperature after melting to obtain a conductive silver alloy ingot;

[0071] b. The conductive silver alloy ingot obtained in step a is cross-rolled for 4 times at room temperature with a deformation of 25% per pass, and then heat-treated at 520° C. under argon protection to obtain a conductive silver alloy slab;

[0072] c. machining the conductive silver alloy slab obtained in step b to obtain a conductive silver alloy sputtering target;

[0073] d. The conductive silver alloy sputtering target obtained in step c is subjected to magnetron sputtering deposition to obtain an ultra-thin transparent conductive silver alloy film with a thickness of 7 nm.

[0074] The present invention adopts a four-point probe method to test the square resistance of the ultra-thin transparent conductive silver alloy film prepared in the above embodiment of the present invention. The four metal probes of the tester are arranged in a straight line. When a certain pressure is pressed on the alloy film, a current I passes between the first and fourth probes, and a potential difference V is generated between the second and third probes. The square resistance is obtained from the ratio of current to voltage.

[0075] The present invention uses an ultraviolet-visible spectrophotometer to test the transmittance of the ultrathin transparent conductive silver alloy film prepared in the above embodiment. After the wavelength range is selected, two blank glass sheets are respectively placed at the reference position and the measurement position for baseline correction, and then a glass sheet with a silver alloy film sputtered on the surface is placed at the measurement position to measure the transmittance at different wavelengths.

Claims

1. A conductive silver alloy for ultra-thin transparent film, characterized in that: The conductive silver alloy contains 2-15% of elements promoting the nucleation of the silver film in molar percentage, and the remainder is Ag and inevitable impurities.

2. The conductive silver alloy for ultra-thin transparent film according to claim 1, characterized in that: The element promoting the nucleation of the silver film is any one of Mg, Al, Cu, Zn, Sn and Mn.

3. A conductive silver alloy sputtering target for ultra-thin transparent films, characterized in that: The conductive silver alloy sputtering target is prepared by melting, pouring, rolling, machining and magnetron sputtering deposition of the conductive silver alloy described in claim 1.

4. The conductive silver alloy sputtering target for ultra-thin transparent film according to claim 3, characterized in that: The preparation method of the conductive silver alloy sputtering target is: a. Weighing each single substance raw material according to the element composition ratio of the conductive silver alloy according to claim 1, and then loading each single substance raw material into a graphite or quartz crucible in an induction melting furnace, melting and pouring under vacuum or argon atmosphere to obtain a conductive silver alloy ingot; b. rolling the conductive silver alloy ingot obtained in step a at room temperature, and then heat treating it under vacuum or argon protection to obtain a conductive silver alloy slab with fine grains; c. machining the conductive silver alloy slab obtained in step b to obtain a conductive silver alloy sputtering target; d. The conductive silver alloy sputtering target obtained in step c is subjected to magnetron sputtering deposition to obtain an ultra-thin transparent conductive silver alloy film, wherein the thickness of the obtained ultra-thin transparent conductive silver alloy film is ≤10 nm.

5. The conductive silver alloy sputtering target for ultra-thin transparent film according to claim 4, characterized in that: The temperatures for smelting and pouring in step a are both 900-1100°C.

6. The conductive silver alloy sputtering target for ultra-thin transparent film according to claim 4, characterized in that: The rolling in step b is cross rolling, the rolling passes are 3 to 15, and the deformation amount per pass is 5 to 25%.

7. The conductive silver alloy sputtering target for ultra-thin transparent film according to claim 4, characterized in that: The heat treatment temperature in step b is 300-600°C.

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