KR20040055604A - Ag ALLOY THIN FILM, SPUTTERING TARGET, AND METHOD FOR PRODUCING Ag ALLOY THIN FILM - Google Patents

Abstract

PURPOSE: To provide an Ag-alloy thin film having high reflectance and superior adhesiveness to a substrate and superior corrosion resistance as well, and to provide a sputtering target and a method for producing the Ag-alloy thin film. CONSTITUTION: The Ag alloy thin film comprises Ag as a main component, 0.1 to 4.0 atom.% of Au and 0.1 to 2.5 atom.% of Sn, wherein the Ag alloy thin film further comprises 0.1 to 3.0 atom.% of oxygen. The sputtering target comprises Ag as a main component, 0.1 to 4.0 atom.% of Au and 0.1 to 2.5 atom.% of Sn, wherein the sputtering target further comprises 0.1 to 3.0 atom.% of oxygen. The method for producing the Ag-alloy thin film comprises the steps of employing an Ag alloy sputtering target, supplying an Ar gas as a sputtering gas and at least one or more of oxygen contained gases selected from O2, H2O and H2+O2 as an additive gas, and sputtering the target to manufacture the Ag alloy film containing Ag as a main component, 0.1 to 4.0 atom.% of Au and 0.1 to 2.5 atom.% of Sn and additionally containing 0.1 to 3.0 atom.% of oxygen, wherein the oxygen contained gases are supplied only during the initial stage of film forming by the sputter, and wherein a primer layer is formed by depositing the Ag alloy thin film on a metal oxide film in such a way that the Ag alloy thin film is produced by sputtering the sputtering target with or without supplying of the additive gas.

Description

Silver alloy thin film, sputtering target and silver alloy thin film manufacturing method {Ag ALLOY THIN FILM, SPUTTERING TARGET, AND METHOD FOR PRODUCING Ag ALLOY THIN FILM}

The present invention relates to an Ag alloy thin film, a sputtering target, and an Ag alloy thin film manufacturing method used for a reflective film of a flat panel display (FPD) such as an LCD or an organic LED.

Conventionally, Al and its alloys (such as Al-Nd system) are used as the reflective film in the display device. However, since a decrease in reflectance occurs in the short wavelength side in the visible light region, and chemical resistance and heat resistance are poor, a protective film is required. There was a flaw.

Attempts have been made to use Ag thin films for this reason. Since the Ag thin film is inferior in corrosion resistance, discoloration occurs due to sulfur components and chlorine in the atmosphere, causing a decrease in reflectance. Moreover, since adhesiveness with a board | substrate is also inferior, film peeling and a pinhole generate | occur | produce well. Therefore, an upper protective film and a base adhesion layer are needed. As a method of improving the corrosion resistance of this Ag thin film, the use of AgPd alloy, AgPdCu alloy, etc. is proposed (for example, patent document 1 [Unexamined-Japanese-Patent No. 2000-109943 (patent claims, etc.)], and patent document 2 [East 2000]). -285517 (claims, etc.). However, the adhesion between these alloys and the substrate was insufficient, and an adhesion layer such as a metal oxide was required.

An object of the present invention is to solve the problems of the prior art, to provide a Ag alloy thin film having a high reflectance, excellent adhesion to the substrate, and also excellent corrosion resistance, while producing a sputtering target and Ag alloy thin film suitable for manufacturing the alloy thin film To provide a way.

1 is a schematic configuration diagram of an inline sputtering apparatus used in an embodiment of the present invention.

* Explanation of symbols on the main parts of the drawing

1: first sputter chamber 2: second sputter chamber

3: 3rd sputter chamber 1a, 2a, 3a: cathode electrode

1b, 2b, 3b: targets 1c, 2c, 3c: power

1d, 2d, 3d: gas introduction system 4, 5: gate valve

6: substrate conveyance tray 7: substrate

Means to solve the problem

MEANS TO SOLVE THE PROBLEM The present inventors discovered that addition of Au and Sn is effective in order to remove the corrosion resistance and adhesiveness which the pure Ag thin film had, and to implement | achieve a high reflection characteristic, and completed this invention.

Invention of Claim 1 consists of Ag alloy which has Ag as a main component, and contains Au as a 2nd element and Sn as a 3rd element, Au content is 0.1-4.0at%, Sn content is 0.1-2.5at% It is an Ag alloy thin film characterized in that. This Ag alloy thin film has a reflectance of 90% or more in the visible light region (wavelength of 400 to 700 nm) and is excellent in corrosion resistance and adhesion to a glass substrate or the like. Outside this range, the Ag alloy thin film cannot satisfy all of reflectance, corrosion resistance, and adhesion. In this thin film, mainly Au is added for corrosion resistance and Sn is mainly used for adhesion.

According to the second aspect of the invention, in the thin film, 0.1 to 3.0 at% of oxygen is further contained as the fourth element. The film containing oxygen in this range is excellent in adhesiveness with a board | substrate.

The invention according to claim 3 is characterized in that the thin film is made of a laminated thin film obtained by laminating the Ag alloy thin film and a metal oxide film.

Invention of Claim 4 consists of Ag alloy which has Ag as a main component, and contains Au as a 2nd element and Sn as a 3rd element, Au content is 0.1-4.0at%, Sn content is 0.1-2.5at% It is an Ag alloy sputtering target characterized by the above-mentioned. By sputtering using a target having a composition having an Au content of 0.1 to 4.0 at% and a Sn content of 0.1 to 2.5 at%, the reflectance is 90% or more in the visible light region (wavelength 400 to 700 nm), and corrosion resistance and adhesion to a glass substrate and the like. This excellent Ag alloy thin film is obtained. Outside this range, Ag alloy thin films satisfying all of the reflectance, corrosion resistance, and adhesion cannot be obtained.

The invention according to claim 5 is a sputtering apparatus using the Ag alloy sputtering target as a target and using at least one oxygen-containing gas selected from Ar ₂ as a sputtering gas and O ₂ , H ₂ O and H ₂ + O ₂ as an additional gas. Ag alloy thin film comprising Ag as a main component and producing an Ag alloy thin film having an Au content of 0.1 to 4.0 at%, a Sn content of 0.1 to 2.5 at%, and an oxygen content of 0.1 to 3.0 at%. It is a manufacturing method. In particular, even in the case of film formation having a low substrate temperature (substrate temperature of 100 ° C. or less), it is an effective means for obtaining an Ag alloy thin film excellent in adhesion to the substrate.

According to the sixth aspect of the present invention, in the method for producing an alloy thin film, an oxygen-containing gas is supplied only at the initial stage of film formation by sputtering.

According to the seventh aspect of the present invention, in the method for producing an alloy thin film, an Ag alloy thin film is laminated on a metal oxide film as a base layer, provided that an Ag alloy thin film is sputtered with or without supplying an additive gas during sputtering. It is a Ag alloy thin film manufacturing method which has a laminated structure characterized by manufacturing. As the thin film having such a laminated structure, there is, for example, a laminated structure of an Ag alloy thin film and a metal oxide thin film selected from tin oxide doped with ITO, IZO, antimony oxide, zinc oxide-aluminum oxide, titanium oxide or the like. When a thin film is used for the anode electrode of an organic LED, since it is necessary for adjustment of the work function with a hole transport layer, it is an effective means to obtain the reflective electrode film excellent in hole injection efficiency. In addition, in the case of using a base layer of a metal oxide thin film, and does not require the use of _{O 2, H 2 O, H} 2 + O 2 gas as the added gas could provide the excellent Ag alloy thin film adhesion to the substrate.

In addition, Ag alloy target of the present invention because it contains Sn, by using a small amount of additive gas of the _{O 2, H 2 O, H} 2 + O 2, the SnO ₂ component is produced in the film. Since this SnO ₂ component becomes a binder with the substrate, it is possible to easily provide an Ag alloy thin film having excellent adhesion. As a board | substrate, a plastic film etc. other than glass and silicon are also effective.

By using the Ag alloy target described above, it is possible to provide an Ag alloy thin film having excellent corrosion resistance and adhesion and high reflectance. In this specification, although the use as a reflecting film is described mainly, since the specific resistance of the obtained Ag alloy thin film is 9 microohm-cm or less, it can be used also as a wiring film.

Example

Next, the Example and the comparative example of this invention are demonstrated, referring drawings. The schematic structure of the inline sputtering apparatus used by the Example and the comparative example in FIG. 1 is shown typically.

This sputtering apparatus is provided with the 1st, 2nd, 3rd sputter chambers 1, 2, and 3. As shown in FIG. Each sputter chamber is partitioned by the gate valves 4 and 5, respectively. The sputter chambers 1, 2, and 3 are configured to be individually connected to a vacuum exhaust system, and cathode electrodes 1a, 2a, and 3a each having a magnetic circuit are disposed in each sputter chamber, and the cathode Targets 1b, 2b and 3b are mounted on the electrodes, respectively. Each of the targets 1b, 2b, and 3b is made of a metal oxide (ITO, etc.), Ag alloy, or the like, and is configured to apply a DC bias from the power sources 1c, 2c, and 3c. As these targets, what consists of metal of the predetermined ratio suitably selected according to the composition of the target Ag alloy thin film is used. In addition, the gas introduction systems 1d, 2d, and 3d are connected to the sputter chambers 1, 2, and 3, respectively, so that the introduction of O ₂ , H ₂ O, H _2, etc. in addition to Ar is possible in each sputter chamber. . In the figure, 6 is a substrate conveyance tray or a substrate support, and 7 is a substrate.

(Example 1)

As a target 1b of the first sputtering chamber 1, a target containing Ag as a main component and 3.1at% (1.7wt%) Au and 2.2at% (2.0wt%) Sn added thereto, and the second sputtering chamber 2 Ag as a main component (2b), a target containing 1.8at% (1.0wt%) Au and 1.3at% (1.2wt%) Sn, and a target 3b of the third sputtering chamber 3 As a main component, Ag and a target containing 0.91 at% (0.5 wt%) of Au and 0.55 at% (0.5 wt%) of Sn were set in each sputter chamber.

Next to the first sputter chamber 1, there is an injection chamber (not shown) provided with a vacuum exhaust system, and the substrate 7 can be conveyed to the first sputter chamber. Ar gas 200SCCM and oxygen gas 0.5SCCM (O ₂ partial pressure 2.67 × 10 ⁻³ Pa) were introduced into the first sputter chamber 1, and DC power 500W (power density 1W / cm 2) was introduced into the target 1b. The sputter pressure was about 0.667 Pa. From the injection chamber, the substrate conveyance tray 6 holding the cleaned glass substrate (Corning 1737; 7) is transferred to the first sputtering chamber 1 at a 20 cm / min conveying speed and passed through film formation at room temperature and 200 캜. It was. Discharge was complete | finished when the tray 6 passed the target 1b, and the tray was returned to the injection chamber. An Ag alloy film 1-1 having a thickness of 150 nm was prepared on the substrate 7.

In the second sputtering chamber 2 and the third sputtering chamber 3, the same operations as described above were carried out to produce Ag alloy films 1-2 and Ag alloy films 1-3 having a film thickness of 150 nm on the respective substrates.

In this embodiment, the film formation method in the in-line type is described, but it can also be produced in a batch type or sheet type film forming apparatus in which a substrate is fixed.

The reflectance, adhesiveness, corrosion resistance, resistance value, and etching characteristics of the obtained Ag alloy films 1-1 to 1-3 were examined. The reflectance was measured using a spectrophotometer in the visible light region (wavelength 400-800 nm) with reference to the Si substrate. Adhesion is cut into the film with a cutter so that the adhesiveness becomes 25 masses (5 × 5) of the size of 5 mm according to the cross-cutting method, and the number of the non-peeled masses in the 25 masses is checked in the checkerboard scale test by a tape (24M manufactured by 3M). It was investigated and evaluated. Corrosion resistance evaluation was performed by leaving the board | substrate with which the Ag alloy film was formed in 5% NaCl solution for 96 hours, and observing corrosion state visually. The resistance value was measured by the four probe type resistance meter (Lorestar made by Mitsubishi Chemical). Etching characteristics were evaluated by forming a 0.2 mm Line & Space pattern in a conventional photoresist process and etching using a mixed solution of phosphoric acid: nitric acid: water = 4: 1: 5 to 10 as the etching solution. For comparison, an APC (Ag-0.9 wt% Pd-1.0 wt% Cu) film was also prepared and subjected to the same evaluation. The obtained results are shown in Table 1.

Measurement Item Ag Alloy Film Film formation temperature (℃) Film thickness R (%) 480 nm (Ref: Si) Adhesion Corrosion resistance ρ (μΩcm) Etching characteristics M / glas M / I / glas APC (Ag-0.9Pd-1.0Cu) Room temperature 1500 235 3/25 25/25 ○ 4.6 ○ 200 1500 225 7/25 25/25 ○ 4.1 ○ Ag alloy film 1-1 (Ag-1.7Au-2.0Sn) Room temperature 1500 232 25/25 25/25 ○ 8.3 ○ 200 1500 226 25/25 25/25 ○ 5.5 ○ Ag alloy film 1-2 (Ag-1.0Au-1.2Sn) Room temperature 1500 239 25/25 25/25 ○ 7.0 ○ 200 1500 230 25/25 25/25 ○ 5.5 ○ Ag alloy film 1-3 (Ag-0.5Au-0.5Sn) Room temperature 1500 242 20/25 25/25 ○ 4.6 ○ 200 1500 235 25/25 25/25 ○ 4.3 ○

In Table 1, the reflectance R (%) describes the value at 480 nm, and in adhesion, M is an Ag alloy film, and I is an ITO film of the underlying layer in the following Example 4.

As can be seen from Table 1, any Ag alloy film had a reflectance equivalent to or higher than that of APC. Ag alloy films 1-3 with the least Au and Sn addition amounts showed the highest reflectance. It is expected that the content of the additive exhibits an effect.

About adhesiveness, all of Ag alloy thin films 1-1 to 1-3 were excellent in adhesiveness with a glass substrate in comparison with APC. This is presumably because Sn element ₂ contained in the target reacts with the O ₂ gas added in the sputter to form SnO ₂ .

As a result of performing Auger analysis on the Ag alloy film obtained in the same manner as above by the room temperature film formation only by changing only the Ag alloy films 1-1 to 1-3 and the oxygen gas introduction amount obtained by the room temperature film formation, The oxygen content in the obtained Ag alloy film is as shown in Table 2.

Target composition Oxygen gas introduction amount (Pa) Oxygen Content in the Film (at%) Ag-1.7Au-2.0Sn 2.67 × 10 ^-3 1.33 × 10 ^-2 6.65 × 10 ^-2 2.67 × 10 ^{-3 (Note)} 0.7 to 1.00.8 to 1.52.0 to 3.00.1 to 0.8 Ag-1.0Au-1.2Sn 2.67 × 10 ^-3 1.13 × 10 ^-2 6.65 × 10 ^-2 0.5 to 0.80.7 to 1.21.5 to 2.0 Ag-0.5Au-0.5Sn 2.67 × 10 ^-3 1.33 × 10 ^-2 6.65 × 10 ^-2 0.1 to 0.50.5 to 1.01.2 to 1.8 Note) When oxygen is introduced only at the beginning of film formation, the film thickness of the initial layer is less than 300Å

As can be seen from Table 2, the oxygen content in the Ag alloy film obtained under the film forming conditions of the present invention also varied depending on the amount of added oxygen at the time of film formation, but was about 0.1 to 3.0 at%.

In particular, since adhesion to the glass substrate is important to control at the interface, even in a method of producing an Ag alloy film by introducing oxygen gas only at the beginning of film formation, the film composition contains about 0.1 to 1.0 at% of oxygen only in the initial layer. The film | membrane which fully satisfy | fills adhesiveness was obtained.

As for corrosion resistance, even after immersion in Ag alloy films 1-1 to 1-3 for 5 hours in 5% NaCl solution, the appearance was not changed and good corrosion resistance was shown. As a result of performing a corrosion resistance test with respect to pure silver for comparison, the glossiness of the surface disappeared after 24 hours, and corrosion resistance was inadequate.

Regarding the specific resistance, the Ag alloy film 1-1 having a large amount of Sn is 8.3 µΩcm in the case of room temperature film formation, and the alloy film in other cases has a lower specific resistance. Therefore, these alloy films can be sufficiently used as wiring films. Level was confirmed.

The etching characteristics of the Ag alloy films 1-1 to 1-3 had an etching rate of about 100 nm / min and a good patterning shape was obtained. Since it can respond also to a resist process, it turned out that it is a film excellent also in alkali resistance and organic solvent resistance.

(Example 2)

Instead of the additive gas of Example 1, H ₂ O (H ₂ O gas partial pressure 2.67 × 10 ⁻³ Pa) was introduced, except for the additive gas, the Ag alloy films 2-1, 2-2, 2 were prepared in the same manner as in Example 1. -3 was prepared. As a result of investigating the physical properties of the obtained thin film in the same manner as in Example 1, it was confirmed that the film was excellent in reflectance, adhesion, corrosion resistance, specific resistance, and etching processability.

(Example 3)

Instead of the additive gas of Example 1, H ₂ + O ₂ gas was used, and other than the additive gas, Ag alloy thin films 3-1, 3-2, and 3-3 were manufactured by the method according to Example 1. For the H ₂ gas introduced as a 3% H ₂ containing Ar gas, O ₂ gas was introduced to a partial pressure 2.67 × 10 ^-3 Pa for O ₂ gas. As a result of investigating the physical properties of the obtained thin film in the same manner as in Example 1, it was confirmed that the film was excellent in reflectance, adhesion, corrosion resistance, specific resistance, and etching processability.

(Example 4)

An ITO (In ₂ O ₃ + 10wt% SnO ₂ ) target as the targets 1b and 3b of the first sputtering chamber 1 and the third sputtering chamber 3 of FIG. 1, and the second sputtering chamber 2 Ag alloy target containing Ag as a main component (2b), and added 0.91 at% (0.5 wt%) of Au and 0.55 at% (0.5 wt%) of Sn was set. According to the method described in Example 1, a laminated structure film of an ITO film (15 nm) / Ag alloy film 1-3 (150 nm) / ITO film (15 nm) was formed on the glass substrate 7 without using an additive gas. Prepared. About the obtained laminated structure film, the reflectance was measured by the method similar to Example 1. The reflectance of the obtained thin film was 235% (Si reference), and the high reflectance was the same as in the case of the Ag alloy film alone. Adhesiveness and corrosion resistance were also favorable similarly to the case of Example 1. Moreover, when the surface smoothness of the obtained film | membrane was investigated by AFM, it was excellent in Rmax = 7.0 nm and Ra = 0.7 nm. The thin film obtained in this example is particularly effective when used as an anode electrode of an organic LED.

Moreover, the laminated structure film | membrane of APC film | membrane / ITO film | membrane and Ag alloy film 1-1 to 1-3 / ITO film | membrane was produced by the same method to the above, and the adhesiveness of these films was measured. The results are shown in Table 1. Any film was excellent in adhesiveness.

In the methods described in Examples 1 to 4, the film formed on the substrate at room temperature and substrate heating (200 ° C.) was explained. Also in the case of after annealing, the same high reflective film was obtained. That is, good results were obtained at room temperature to 350 ° C.

(Comparative Example 1)

Ag as a main component 1b of the first sputtering chamber 1 of FIG. 1 and a target containing 3.1at% (1.7wt%) of Au, Ag as the target 2b of the second sputtering chamber 2 Is a main component, and a target containing 1.8at% (1.0wt%) of Au and a target (3b) of the third sputtering chamber (3) are Ag, and 0.91at% (0.5wt%) of Au is added. The targets were each set, and a film was formed under the same conditions as in Example 1 to prepare an Ag alloy film 1500 Å on a glass substrate. The amount of oxygen gas introduced was changed to ⁰ Pa, 2.67 × 10 ⁻³ Pa, and 6.65 × 10 ⁻² Pa to form a film.

As a result of investigating the properties of the obtained Ag alloy films in the same manner as in Example 1, the reflectance, corrosion resistance and etching characteristics were good, but the adhesion was insufficient even if the oxygen introduction amount was increased as shown in Table 3.

Target composition Oxygen gas introduction amount (Pa) Adhesiveness (large glass substrate) Ag-3.1at% (1.7wt%) Au 02.67 × 10 ^-3 6.65 × 10 ^-2 0/250/250/25 Ag-1.8at% (1.0wt%) Au 02.67 × 10 ^-3 6.65 × 10 ^-2 0/250/250/25 Ag-0.91at% (0.5wt%) Au 02.67 × 10 ^-3 6.65 × 10 ^-2 0/250/250/25

(Comparative Example 2)

Ag as the main component 1b of the first sputtering chamber 1 of FIG. 1, and a target containing 2.2at% (2.0 wt%) of Sn, Ag as the target 2b of the second sputtering chamber 2 The main component of which is 1.3at% (1.2wt%) of Sn added, the target of the third sputtering chamber (3) (3b) Ag as the main component and 0.55at% (0.5wt%) of Sn added The targets were each set, and a film was formed under the same conditions as in Example 1 to prepare an Ag alloy film 1500 Å on a glass substrate. The amount of oxygen gas introduced was changed to ⁰ Pa, 2.67 × 10 ⁻³ Pa, and 6.65 × 10 ⁻² Pa to form a film.

As a result of investigating the properties of the obtained Ag alloy films in the same manner as in Example 1, the reflectance, the adhesion and the etching characteristics were good, but the corrosion resistance was insufficient as shown in Table 4 below.

Target composition Oxygen gas introduction amount (Pa) Corrosion resistance (5% NaCl immersion test) Ag-2.2at% (2.0wt%) Sn 02.67 × 10 ^-3 6.65 × 10 ^-2 No surface gloss after 24 hours No surface gloss after 30 hours No surface gloss after 30 hours Ag-1.3at% (1.2wt%) Sn 02.67 × 10 ^-3 6.65 × 10 ^-2 No surface gloss after 24 hours No surface gloss after 24 hours No surface gloss after 24 hours Ag-0.55at% (0.5wt%) Sn 02.67 × 10 ^-3 6.65 × 10 ^-2 No surface gloss after 24 hours No surface gloss after 24 hours No surface gloss after 24 hours

According to the present invention, by using the Ag alloy target of the above-described specific composition, it is possible to provide an Ag alloy film having excellent adhesion to a glass substrate and the like, excellent corrosion resistance and etching processability, and high reflectance.

Since the resistance value of Ag alloy film is sufficiently low, a thin film can also be used as an electrode film and a wiring film.

Claims (7)

An Ag alloy thin film comprising Ag as a main component and containing Au and Sn, wherein the Au content is 0.1 to 4.0 at% and the Sn content is 0.1 to 2.5 at%. The Ag alloy thin film according to claim 1, further comprising 0.1 to 3.0 at% of oxygen. The Ag alloy thin film according to claim 1 or 2, which is made of a laminated thin film obtained by laminating an Ag alloy thin film and a metal oxide film. An Ag alloy sputtering target composed of an Ag alloy containing Ag as the main component and containing Au and Sn, wherein the Au content is 0.1 to 4.0 at% and the Sn content is 0.1 to 2.5 at%. Using the Ag alloy sputtering target according to claim 4 as a sputtering target, sputtering using Ar gas as a sputtering gas and at least one oxygen-containing gas selected from O ₂ , H ₂ O and H ₂ + O ₂ as an additive gas, Ag alloy thin film manufacturing method characterized by producing Ag alloy thin film containing Ag as the main component, 0.1 to 4.0 at% Au, 0.1 to 2.5 at% Sn, and 0.1 to 3.0 at% oxygen. . The Ag alloy thin film manufacturing method according to claim 5, wherein the oxygen-containing gas is supplied only at the initial stage of film formation by sputtering. The laminated structure according to claim 5, wherein the Ag alloy thin film is laminated on the metal oxide film serving as the base layer, except that the Ag alloy thin film is manufactured by sputtering with or without supplying an additive gas during sputtering. Ag alloy thin film manufacturing method having.