KR20240002225A - Nickel-copper-titanium alloy composition, tie-coat layer, metallization and stretchable substrate therefrom - Google Patents

Abstract

The present invention relates to a nickel-copper-titanium (Ni-Cu-Ti) alloy composition, a tie coat layer including the alloy composition, a wiring layer including the tie coat layer, and a stretchable substrate including the wiring layer.

Description

Nickel-copper-titanium alloy composition, tie coat layer, wiring layer and flexible substrate formed therefrom

The present invention provides a nickel-copper-titanium (Ni-Cu-Ti) alloy composition, a tie coat layer including the alloy composition, a metal wiring layer including the tie coat layer, and a stretchable substrate including the metal wiring layer. and electronic devices and displays containing the same.

Stretchable displays or stretchable electronic devices use a substrate with flexibility and elasticity (in the present invention, it is called a stretchable substrate), and a polymer substrate is used as the substrate. When forming copper wiring on such a flexible substrate, a bonding layer called a tiecoat layer is required for the purpose of establishing a strong bond between the wiring and the substrate. In particular, in display devices, pure titanium or molybdenum alloy is used as the lower layer of copper wiring on a polymer substrate (referred to as a tie coat layer in the present invention). However, these titanium and molybdenum alloys have poor stretchability and are therefore unsuitable for use as wiring for stretchable devices. Similarly, in FCCL (Flexible Copper Clad Laminate) or FPCB (Flexible Printed Circuit Board), binary alloys such as nickel-copper (Ni-Cu) and nickel-chromium (Ni-Cr) are generally used as the lower layer of copper wiring. It is being used a lot.

However, recently, flexible polymer materials such as polyimide or liquid crystal polymer are widely used as materials for electronic devices, and the nickel-copper (Ni-Cu) alloy is used as a substrate for these flexible polymer substrates. There is a problem of somewhat poor bonding strength and elongation, and the nickel-chromium (Ni-Cr) alloy has poor etching properties, causing various problems in patterning.

Additionally, there is a condition that patterning must be possible with copper, which is the low-resistance wiring on the top of the tie coat layer. Therefore, the copper subfilm tie coat layer must be a material that can be etched with a copper wet etchant.

Republic of Korea Patent Publication No. 10-1999-0026012 discloses a nickel-copper alloy composition with improved wear resistance and chemical resistance that can be applied to semiconductor components, but there are still problems with insufficient adhesion and stretchability to flexible polymer substrates, and copper There is a problem that it is difficult to pattern the wiring layer at the same time.

Accordingly, there is a continuing need for a nickel alloy composition that has excellent adhesion to a flexible polymer substrate, elongation, and etching properties when applied as a lower layer such as a tie coat layer.

Republic of Korea Patent Publication No. 10-1999-0026012

The present invention relates to a nickel-copper-titanium (Ni-Cu-Ti) alloy composition capable of forming a wiring layer with excellent adhesion to a stretchable substrate, stretchability, and etching properties, and a tie coat layer containing the alloy composition. , the purpose of the invention is to provide a wiring layer and a stretchable substrate.

In order to achieve the above purpose,

The present invention, based on the total weight of the composition, 40 to 60% by weight of nickel (Ni); 20 to 35% by weight of copper (Cu); and 10 to 30 wt% of titanium (Ti), providing a nickel-copper-titanium (Ni-Cu-Ti) alloy composition.

Additionally, the present invention provides a tie coat layer containing the alloy composition.

The tie coat layer may have a specific resistance of 300 μΩ·cm or less.

The tie coat layer may have a critical load of 6.5 mN or more.

The tie coat layer may have an etch rate of 1 nm/s or more when etched using a copper wet etchant.

Additionally, the present invention provides a wiring layer including the tie coat layer.

The wiring layer may include the tie coat layer and the metal layer.

The metal layer may be a stack of one or two or more selected from the group consisting of a copper film, an aluminum film, and a nickel-copper-titanium alloy film.

Additionally, the present invention includes a base layer; and a stretchable substrate including the wiring layer.

The base layer is one selected from the group consisting of polyimide, modified polyimide, liquid crystal polymer, polydimethylsiloxane (PDMS), and polyurethane. It may include more than just that.

According to the nickel-copper-titanium (Ni-Cu-Ti) alloy composition according to an embodiment of the present invention, nickel (Ni), copper (Cu), and titanium (Ti) are included in a certain ratio based on the total weight of the composition. By doing so, it is possible to form a wiring layer with further improved adhesion to the stretchable substrate, stretchability, and etching properties.

Additionally, the present invention can provide a stretchable substrate that can be applied to a flexible display or stretchable display.

Figure 1 is a diagram schematically showing the laminated structure of a stretchable substrate including a nickel-copper-titanium (Ni-Cu-Ti) alloy composition according to an embodiment of the present invention.
FIG. 2 is a diagram illustrating critical load measurements of a wiring layer including a nickel-copper-titanium (Ni-Cu-Ti) alloy composition according to one or more embodiments of the present invention.
Figure 3 is a graph measuring the XPS spectrum of the surface of the tie coat layer and the interface between the tie coat layer and the base layer according to Example 6 of the present invention.
Figure 4 is a diagram showing a NiCuTi/Copper double-film wiring layer in which a copper layer is laminated on a tie coat layer according to Example 1 of the present invention.

In the present invention, by including nickel (Ni), copper (Cu), and titanium (Ti) in a certain ratio based on the total weight of the composition, it is possible to form a wiring layer with improved adhesion to a stretchable substrate, stretchability, and etchability. It relates to a nickel-copper-titanium (Ni-Cu-Ti) alloy composition.

More specifically, 40 to 60% by weight of nickel (Ni) based on the total weight of the composition; Copper (Cu) 20 to 35% by weight; and 10 to 30% by weight of titanium (Ti). It relates to a nickel-copper-titanium (Ni-Cu-Ti) alloy composition.

The nickel-copper-titanium (Ni-Cu-Ti) alloy composition according to an embodiment of the present invention includes nickel (Ni), copper (Cu), and titanium (Ti).

The nickel (Ni) may be included in an amount of 40 to 60% by weight, preferably 40 to 50% by weight, and more preferably 45 to 50% by weight, based on the total weight of the composition. If nickel (Ni) is included in less than 40% by weight of the total weight of the composition, the bonding strength with the polymer substrate may be reduced, and if it is included in more than 60% by weight, the etching rate in ammonium-based etchant may be reduced.

The copper (Cu) may be included in an amount of 20 to 35% by weight, preferably 23 to 30% by weight, and more preferably 25 to 30% by weight, based on the total weight of the composition. If copper (Cu) is included in less than 20% by weight of the total weight of the composition, electrical conductivity may decrease, and if it is included in more than 35% by weight, overetching may occur in ammonium-based etchants.

The titanium (Ti) may be included in an amount of 10 to 30% by weight, preferably 20 to 25% by weight, based on the total weight of the composition. If the titanium (Ti) content is less than 10% by weight, the bonding strength with the polymer is reduced, and if it is more than 30% by weight, the etching characteristics of the copper etchant are reduced and there may be difficulties in forming wires.

Hereinafter, embodiments of the present invention will be described in more detail with reference to the drawings. However, the following drawings attached to this specification illustrate preferred embodiments of the present invention, and serve to further understand the technical idea of the present invention along with the contents of the above-described invention, so the present invention is described in such drawings. It should not be interpreted as limited to the specific details.

As used herein, "comprises" and "comprising" means the presence or addition of one or more other components, steps, operations and/or elements other than the mentioned components, steps, operations and/or elements. It is used in the sense that it does not exclude. Like reference numerals refer to like elements throughout the specification.

Figure 1 is a diagram schematically showing the laminated structure of a stretchable substrate including a nickel-copper-titanium (Ni-Cu-Ti) alloy composition according to an embodiment of the present invention.

Referring to Figure 1, the present invention includes a tie coat layer 21 containing the nickel-copper-titanium (Ni-Cu-Ti) alloy composition, and the wiring layer 20 of the present invention includes the tie coat layer ( 21) and a metal layer 22.

In addition, the present invention includes a base layer (10); And a stretchable substrate including the wiring layer 20 can be provided, and can be applied to a flexible display or stretchable display, and in the present invention, these are all referred to as stretchable substrates.

The base layer 10 is selected from the group consisting of polyimide, modified polyimide, liquid crystal polymer, polydimethylsiloxane (PDMS), and polyurethane. It may contain one or more types, and preferably may contain polyimide or modified polyimide.

The wiring layer 20 of the present invention includes a tie coat layer 21 and a metal layer 22 formed of a nickel-copper-titanium (Ni-Cu-Ti) alloy composition on the base layer 10, The tie coat layer 21 may be formed in the form of a thin film. The wiring layer 20 has a structure including a metal layer 22 on the tie coat layer 21, and each layer is formed by physical vapor deposition (PVD) such as sputtering deposition or chemical vapor deposition such as plasma, thermal energy, and atomic layer deposition. It can be formed through the (CVD) method.

The wiring layer 20 may be etched according to the purpose, for example, may be etched with one or more types of copper wet etchant (copper etchant) selected from the persulfate, hydrogen peroxide, copper chloride, and iron chloride series, preferably It may have been etched with a 10-20 wt% ammonium persulfate solution containing fluorine ions.

At this time, the metal layer 22 may have a structure in which one or two or more types selected from the group consisting of a copper film, an aluminum film, and a nickel-copper-titanium alloy film are stacked.

For example, the wiring layer 20 may be composed of only the tie coat layer and a copper film, or may be a structure in which the tie coat layer, the copper film, and the nickel-copper-titanium (Ni-Cu-Ti) alloy film are stacked. , In addition, the tie coat layer, the aluminum film, and the nickel-copper-titanium (Ni-Cu-Ti) alloy film may be stacked, and the nickel-copper-titanium (Ni-Cu-Ti) is the nickel described above. -It may contain a copper-titanium (Ni-Cu-Ti) alloy composition.

The thickness of the wiring layer 20 is not particularly limited because it can be adjusted in various ways within a range that does not deteriorate the physical properties of the nickel-copper-titanium (Ni-Cu-Ti) alloy composition according to the present invention.

Titanium (Ti) included in the tie coat layer 21 of the wiring layer 20 forms TiO ₂ at the interface with the base layer 10, and the TiO ₂ has high surface energy. In the case of the base layer 10 having reactive functional groups such as hydroxyl (-OH) and carbonyl (-C=O) groups such as polyimide, it can form a strong bond with TiO ₂ . Therefore, chemical compatibility between TiO ₂ and the base layer 10 such as polyimide improves adhesion by strengthening the interfacial bond.

TiO ₂ formed at the interface between the base layer 10 and the wiring layer 20 prevents diffusion of copper and prevents a decrease in bonding strength, and prevents moisture and oxygen contained in the base layer 10, such as polyimide, from forming in the wiring layer ( 20) to prevent penetration. This prevents deterioration or peeling of the wiring and improves the overall adhesion between the base layer 10 and the wiring layer 20.

In one or more embodiments, the tie coat layer 21 may have a specific resistance of 300 μΩ·cm or less, and more preferably 250 μΩ·cm or less. If the specific resistance of the tie coat layer 21 exceeds 300 μΩ·cm, resistance loss in the wiring structure increases, causing a decrease in wiring performance and efficiency, and the problem of deterioration of the wiring structure due to resistance loss may occur. .

In one or more embodiments, the tie coat layer 21 may have a critical load of 6.5 mN or more, and more preferably 6.5 to 9.5 mN. The critical load may be the magnitude of force measured using a nano-scratch tester at a point where the friction coefficient rapidly changes or where the residual depth changes rapidly. If the critical load of the wiring layer is less than 6.5 mN, cracks may occur in the wiring layer and the adhesion to the flexible substrate may decrease, and if it exceeds 9.5 mN, the tie may break due to excessive adhesive force when the substrate undergoes deformation such as bending, stretching, or bending. There is a problem that the internal stress of the coat layer increases, which increases brittleness and may cause microcracks.

In one or more embodiments, when the tie coat layer 21 is etched using the copper wet etchant described above, the etching rate may be 1 nm/s or more, and more preferably 1 to 10 nm/s. It may be s. If the etch rate is less than 1 nm/s, the etch rate is low, resulting in a large difference in etch rate with the copper layer, which is unsuitable for forming a wiring layer such as a double layer.

Hereinafter, examples of the present invention will be described in detail. However, the present invention is not limited to the embodiments disclosed below and may be implemented in various different forms. The present embodiments are merely provided to ensure that the disclosure of the present invention is complete and to be understood by those skilled in the art. It is provided to fully inform those who have the scope of the invention, and the present invention is only defined by the scope of the claims.

Examples and Comparative Examples

A polyimide substrate was prepared as a base layer, and a nickel-copper-titanium (Ni-Cu-Ti) alloy composition having the composition ratio of the examples and comparative examples in Table 1 below was prepared, and sputtering method was used. A tie coat layer was formed by depositing each layer to a thickness of 200 Å on a polyimide substrate.

Ni:Cu:Ti (wt%) Example 1 45:28:27 Example 2 47:23:30 Example 3 40:35:25 Example 4 60:30:10 Example 5 50:20:30 Example 6 50:25:25 Comparative Example 1 37:30:33 Comparative Example 2 54:15:31 Comparative Example 3 65:20:15 Comparative Example 4 40:40:20 Comparative Example 5 50:45:5 Comparative Example 6 100:0:0 Comparative Example 7 25:40:35 Comparative Example 8 0:0:100

Experiment example

(1) Resistivity measurement

For the tie coat layers of Examples 1 to 6 and Comparative Examples 1 to 8, the resistivity was measured using a 4 point probe (CMT-SR1000N, Advanced Instrument Technology). The measurement results are shown in Table 2 below.

(2) Critical load measurement

For the tie coat layers of Examples 1 to 6 and Comparative Examples 1 to 8, a critical load was measured at the point where the friction coefficient rapidly increases or the residual depth changes rapidly using a nano-scratch tester (Anton Paar). ), and the measurement results are shown in Table 2 and Figure 2 below.

(3) Elongation evaluation

For the tie coat layer of the examples and comparative examples, 20 nm of the tie coat layer and 300 nm of the upper copper film were formed on a polyimide substrate of 0.5 cm * 7 cm in size, and then 3 times using a stretching system (STM-1-Touch screen, Sciencetown). % elongation was repeated 1000 times, and the presence or absence of cracks was visually observed using an optical microscope (DM750M, LEIKA), and the results are shown in Table 2 below.

<Evaluation criteria>

○: No cracks

×: crack occurrence

(4) Evaluation of bonding strength

The bonding strength was evaluated depending on whether the critical load and elongation measured in (2) and (3) above were simultaneously satisfied, and the evaluation results according to the following evaluation criteria are shown in Table 2 below.

<Evaluation criteria>

○: The critical load is 6.5 mN or more, and at the same time, no cracks are observed even when stretched repeatedly 1000 times by 3% or more based on the substrate.

×: Critical load is less than 6.5 mN, or cracks are observed upon repeated stretching of 3% or more 1000 times based on the substrate.

Additionally, XPS analysis was performed on the surface of the tie coat layer of Example 6 and the interface between the tie coat layer and the base layer using 2p XPS spectra (K-Alpha, Thermo Fisher Scientific), and the results are shown in Figure 3.

Figures 3a, 3c, and 3e show the XPS analysis results for the surface of the tie coat layer, and Figures 3b, 3d, and 3f show the XPS analysis results for the interface between the tie coat layer and the base layer.

As a result of the XPS analysis, it can be confirmed that Ti formed TiO ₂ at the interface between the tie coat layer and the base layer.

(5) Etching rate measurement

For the tie coat layers of Examples and Comparative Examples, etching was performed using a 10-20 wt% Ammonium persulfate solution containing fluorine ions at a temperature of 25°C, and the etched thickness upon treatment with the etchant was measured using a thin film thickness gauge (Alpha-step IQ). , Kla-tencor), the etch rate was calculated, and the results are shown in Table 2 below.

division resistivity
(μΩ·cm) critical load
(mN) Stretchability bonding force Etching speed
(㎚/s) Example 1 202.35 7.936 ○ ○ 1.22 Example 2 211.31 6.784 ○ ○ 1.13 Example 3 198.47 7.344 ○ ○ 1.25 Example 4 187.23 9.244 ○ ○ 1.11 Example 5 232.16 7.251 ○ ○ 1.17 Example 6 203.74 8.312 ○ ○ 1.32 Comparative Example 1 256.21 5.94 X X 0.67 Comparative Example 2 272.88 5.84 X X 0.51 Comparative Example 3 220.15 6.013 X X 0.73 Comparative Example 4 195.15 6.177 X X 0.89 Comparative Example 5 252.72 5.537 X X 2.24 Comparative Example 6 18.71 6.21 X X 0.55 Comparative Example 7 268.14 6.33 X X 0.43 Comparative Example 8 61.51 6.117 X X 0.15

Referring to Table 2, the tie coat layers of Examples 1 to 6 had a specific resistance of 300 μΩ·cm or less, and even 250 μΩ·cm or less, and a critical load of 6.5 mN or more, which is outside the scope of the present invention. It can be seen that the adhesive strength and stretchability to the polyimide substrate are excellent compared to the tie coat layer of items 8 to 8.

In addition, in the case of Examples 1 to 6 according to the present invention, the etching rate is 1 nm/s or more, making it easy to etch when forming the wiring layer, and in the case of Comparative Examples 1 to 4 and 6 to 8, the etch rate is low, so there is a difference in the etch rate with the copper layer. It was large and unsuitable for forming a wiring layer such as a double layer. In Comparative Example 5, it can be seen that overetching occurred due to the high copper content.

Therefore, the nickel-copper-titanium (Ni-Cu-Ti) alloy composition of the present invention has the advantage of forming a wiring layer with excellent adhesion to a stretchable substrate, stretchability, and etchability.

Claims (10)

With respect to the total weight of the composition,
40 to 60% by weight of nickel (Ni);
20 to 35% by weight of copper (Cu); and
A nickel-copper-titanium (Ni-Cu-Ti) alloy composition comprising 10 to 30% by weight of titanium (Ti).
A tie coat layer comprising the alloy composition of claim 1.
In claim 2,
The tie coat layer is a tie coat layer with a specific resistance of 300 μΩ·cm or less.
In claim 2,
The tie coat layer is a tie coat layer having a critical load of 6.5 mN or more.
In claim 2,
The tie coat layer is a tie coat layer having an etch rate of 1 nm/s or more when etched using a copper wet etchant.
A wiring layer comprising the tie coat layer of claim 2.
In claim 6,
The wiring layer is a wiring layer comprising the tie coat layer and the metal layer of claim 2.
In claim 6,
The metal layer is a wiring layer, characterized in that one or two or more types selected from the group consisting of a copper film, an aluminum film, and a nickel-copper-titanium alloy film are laminated.
Base layer; and
A stretchable substrate comprising the wiring layer of claim 6.
In claim 9,
The base layer is one selected from the group consisting of polyimide, modified polyimide, liquid crystal polymer, polydimethylsiloxane (PDMS), and polyurethane. A stretchable substrate containing the above.