Nano-twinned copper layer, method for manufacturing the same, and substrate comprising the same

Abstract

A nano-twinned copper layer is disclosed, wherein over 50% of a volume of the nano-twinned copper layer comprises a plurality of columnar crystal grains, the plurality of columnar crystal grains connect to each other, at least 70% of the plurality of columnar crystal grains are formed by a plurality of nano-twins stacking in an orientation of a crystal axis, and an angle included between two adjacent columnar crystal grains is greater 20° and less than or equal to 60°. In addition, a method for manufacturing the nano-twinned copper layer and a substrate comprising the same are also disclosed.

Claims

1. A nano-twinned copper layer, wherein over 50% of a volume of the nano-twinned copper layer comprises a plurality of columnar crystal grains, the plurality of columnar crystal grains connect to each other, at least 70% of the plurality of columnar crystal grains are formed by a plurality of nano-twins stacking in an orientation of a crystal axis, and an angle included between two adjacent columnar crystal grains is greater 20° and less than or equal to 60°, wherein an angle included between a direction of a longitude axis of one of the plurality of the columnar crystal grains and a thickness direction of the nano-twinned copper layer is greater than 20° but less than or equal to 60°.

2. The nano-twinned copper layer of claim 1, wherein a thickness of the nano-twinned copper layer is ranged from 0.1 μm to 500 μm.

3. The nano-twinned copper layer of claim 1, wherein each of the plurality of columnar crystal grains is formed by the plurality of nano-twins stacking in the orientation of the crystal axis.

4. The nano-twinned copper layer of claim 1, wherein lengths of the plurality of columnar crystal grains on a minor axis are respectively ranged from 0.1 μm to 50 μm.

5. The nano-twinned copper layer of claim 1, wherein thicknesses of the plurality of columnar crystal grains are respectively ranged from 0.01 μm to 500 μm.

6. A method for manufacturing a nano-twinned copper layer, comprising the following steps: providing an electrodepositing system, which comprises an anode, a cathode, a plating solution and a power supply, wherein the power supply is electrically connected to the anode and the cathode, and the anode and the cathode are immersed in the plating solution; performing electrodeposition at a first current density, which is 0.8 to 1.0 times of a limiting current density of the electrodepositing system; and performing electrodeposition at a second current density, which is 0.1 to 0.6 times of the limiting current density of the electrodepositing system, to grow a nano-twinned copper layer on a surface of the cathode, wherein over 50% of a volume of the nano-twinned copper layer comprises a plurality of columnar crystal grains, the plurality of columnar crystal grains connect to each other, at least 70% of the plurality of columnar crystal grains are formed by a plurality of nano-twins stacking in an orientation of a crystal axis, and an angle included between two adjacent columnar crystal grains is greater 20° and less than or equal to 60°, wherein an angle included between a direction of a longitude axis of one of the plurality of the columnar crystal grains and a thickness direction of the nano-twinned copper layer is greater than 20° but less than or equal to 60°.

7. The method of claim 6, wherein a time for the electrodeposition at the first current density is ranged from 1 second to 20 seconds.

8. The method of claim 6, wherein the electrodeposition is carried out by direct current electrodeposition, pulse electrodeposition, or both interchangeably.

9. The method of claim 6, wherein the cathode is a substrate with a metal layer formed thereon or a metal substrate.

10. The method of claim 9, wherein the substrate is a silicon substrate, a glass substrate, a quartz substrate, a metal substrate, a plastic substrate, a printed circuit board, a III-V group material substrate, or a laminated substrate thereof.

11. A substrate with a nano-twinned copper layer, comprising: a substrate; and a nano-twinned copper layer disposed on a surface of the substrate or embedded in the substrate, wherein over 50% of a volume of the nano-twinned copper layer comprises a plurality of columnar crystal grains, the plurality of columnar crystal grains connect to each other, at least 70% of the plurality of columnar crystal grains are formed by a plurality of nano-twins stacking in an orientation of a crystal axis, and an angle included between two adjacent columnar crystal grains is greater 20° and less than or equal to 60°, wherein an angle included between a direction of a longitude axis of one of the plurality of the columnar crystal grains and a thickness direction of the nano-twinned copper layer is greater than 20° but less than or equal to 60°.

12. The substrate of claim 11, wherein the substrate is a silicon substrate, a glass substrate, a quartz substrate, a metal substrate, a plastic substrate, a printed circuit board, a III-V group material substrate, or a laminated substrate thereof.

13. The substrate of claim 11, wherein a thickness of the nano-twinned copper layer is ranged from 0.1 μm to 500 μm.

14. The substrate of claim 11, wherein each of the plurality of columnar crystal grains is formed by the plurality of nano-twins stacking in the orientation of the crystal axis.

15. The substrate of claim 11, wherein lengths of the plurality of columnar crystal grains on a minor axis are respectively ranged from 0.1 μm to 50 μm.

16. The substrate of claim 11, wherein thicknesses of the plurality of columnar crystal grains are respectively ranged from 0.01 μm to 500 μm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic diagram showing an electrodeposition system used in the present disclosure.

(2) FIG. 2 is a plot of potential vs. current density of an electrodeposition system used in the present disclosure to measure the limiting current density of the electrodeposition system.

(3) FIG. 3 is a cross-sectional focused ion beam photo of a nano-twinned copper layer prepared in Example 1 of the present disclosure.

(4) FIG. 4 is a cross-sectional focused ion beam photo of a nano-twinned copper layer prepared in Comparative example 1 of the present disclosure.

(5) FIG. 5 is a plot of stress vs. elongation rate of nano-twinned copper layers prepared in Example 1 and Comparative example 1 of the present disclosure.

(6) FIG. 6 is a schematic diagram showing another electrodeposition system used in the present disclosure.

(7) FIG. 7 is a cross-sectional focused ion beam photo of a nano-twinned copper layer prepared in Comparative example 3 of the present disclosure.

(8) FIG. 8 is a plot of stress vs. elongation rate of nano-twinned copper layers prepared in Example 6 and Comparative example 3 of the present disclosure.

DETAILED DESCRIPTION OF EMBODIMENT

(9) Different embodiments of the present disclosure are provided in the following description. These embodiments are meant to explain the technical content of the present disclosure, but not meant to limit the scope of the present disclosure. A feature described in an embodiment may be applied to other embodiments by suitable modification, substitution, combination, or separation.

(10) It should be noted that, in the present specification, when a component is described to have an element, it means that the component may have one or more of the elements, and it does not mean that the component has only one of the element, except otherwise specified.

(11) Moreover, in the present specification, the ordinal numbers, such as “first” or “second”, are used to distinguish a plurality of elements having the same name, and it does not means that there is essentially a level, a rank, an executing order, or an manufacturing order among the elements, except otherwise specified. A “first” element and a “second” element may exist together in the same component, or alternatively, they may exist in different components, respectively. The existence of an element described by a greater ordinal number does not essentially means the existent of another element described by a smaller ordinal number.

(12) Moreover, in the present specification, the terms, such as “top”, “bottom”, “left”, “right”, “front”, “back”, or “middle”, as well as the terms, such as “on”, “above”, “under”, “below”, or “between”, are used to describe the relative positions among a plurality of elements, and the described relative positions may be interpreted to include their translation, rotation, or reflection.

(13) Moreover, in the present specification, when an element is described to be arranged “on” another element, it does not essentially mean that the elements contact the other element, except otherwise specified. Such interpretation is applied to other cases similar to the case of “on”.

(14) Moreover, in the present specification, a value may be interpreted to cover a range within ±10% of the value, and in particular, a range within ±5% of the value, except otherwise specified; a range may be interpreted to be composed of a plurality of subranges defined by a smaller endpoint, a smaller quartile, a median, a greater quartile, and a greater endpoint, except otherwise specified.

Example 1

(15) FIG. 1 is a schematic diagram showing an electrodeposition system used in the present Example 1. The electrodeposition system 1 comprised: an anode 11 and a cathode 12 immersed into a plating solution 13 and respectively electrically connected to a direct current power supply 15. Herein, the anode 11 was a phosphorous copper bulk and the cathode 12 was a titanium substrate. The plating solution 13 comprised CuSO.sub.4 (the Cu ion concentration being 30 g/L), HCl (the Cl ion concentration being 50 mg/L) and H.sub.2SO.sub.4 (100 g/L).

(16) The electrodeposition was carried out with a direct current at a current density of 20 ASD for 6 seconds, and then with a direct current at a current density of 12 ASD for 300 seconds. The nano-twinned copper was grown on the surface of the cathode 12. The cathode 12 or the plating solution 13 was stirred at about 800 rpm. In addition, the thickness of the obtained nano-twinned copper layer 14 was about 10 μm.

(17) The current density of the electrodeposition system used herein was recorded at 800 rpm by continuously increasing the applied potential to obtain the limiting current density of the used electrodeposition system. The limiting current density of the used electrodeposition system was 21.6 ASD, as shown in FIG. 2.

(18) FIG. 3 is a cross-sectional focused ion beam photo of a nano-twinned copper layer prepared in the present example. As shown in FIG. 3, in the obtained nano-twinned copper layer, over 50% of the volume of the nano-twinned copper layer comprises a plurality of columnar crystal grains, and the columnar crystal grains connect to each other. As shown in FIG. 3, the columnar crystal grains are formed by plural layered nano-twins, and the nano-twins extend to the surface of the nano-twinned copper layer. Thus, the (111) surface of the nano-twins is exposed on the surface of the nano-twinned copper layer. In the present example, all the surface of the nano-twinned copper layer is almost the (111) surface. In addition, the [111] crystal axis is an axis perpendicular to the (111) surface, and at least 70% of the columnar crystal grains are formed by the nano-twins stacking in an orientation of the [111] crystal axis. In the present example, almost all the columnar crystal grains are formed by the nano-twins stacking in the orientation of the [111] crystal axis.

(19) In particular, as shown in FIG. 3, in the present example, the angle included between two adjacent columnar crystal grains is not 0°, but is greater 20° and less than or equal to 60°. In addition, lengths of the columnar crystal grains on a minor axis are respectively ranged from 0.5 μm to 3 μm, and thicknesses of the columnar crystal grains are respectively ranged from 2 μm to 5 μm.

Comparative Example 1

(20) The process for growing the nano-twinned copper layer used herein is similar to that described in Example 1, except that the electrodeposition was directly carried out with a direct current at a current density of 12 ASD for 300 seconds.

(21) FIG. 4 is a cross-sectional focused ion beam photo of a nano-twinned copper layer prepared in the present comparative example. As shown in FIG. 3 and FIG. 4, the difference between the nano-twinned copper layers of Example 1 and Comparative example 1 is that the angle included between two adjacent columnar crystal grains is greater 20° and less than or equal to 60° in the nano-twinned copper layer of Example 1, but the angle included between two adjacent columnar crystal grains is close to 0° in the nano-twinned copper layer of Comparative example 1.

(22) Tensile Test

(23) The obtained nano-twinned copper layers were peeled off from the substrate and tested by IPC-TM-650 Test Method. The obtained nano-twinned copper layers were cut into strips with the 12.7 mm width and 150 mm length. INSTRON 4465 Tensile Testing Machine was used. Gauge length was set 50 mm, and the strain rate was set 5 nm/min.

(24) TABLE-US-00001 TABLE 1 Maximum First current Second current tensile Elongation density, time density, time strength rate Example 1 20 ASD, 12 ASD, 606 MPa 3.0% 6 sec 300 sec Comparative 12 ASD, — 611 MPa 1.2% example 1 300 sec

(25) As shown in Table 1 and FIG. 5, compared to the nano-twinned copper layer of Comparative example 1, the nano-twinned copper layer of Example 1 has increased elongation rate.

Examples 2-5 and Comparative Example 2

(26) The electrodeposition system used in Example 1 was used herein. The Cu ion concentration in the plating solution, the stirring rate and the temperature of the electrodeposition were adjusted to obtain different limiting current densities. The segmented electrodepositions with different current densities were used to obtain the nano-twinned copper layers of the present examples. The obtained nano-twinned copper layers were observed by their cross-sectional focused ion beam photos to check whether the angle included between two adjacent columnar crystal grains is greater 20° and less than or equal to 60°.

(27) TABLE-US-00002 TABLE 2 Angle included between two adjacent columnar Limiting crystal grains is First current Second current current greater 20° and density time density, time density less than 60° Example 2 20 ASD, 4 ASD, 21.6 ASD Yes 6 sec 2500 sec Example 3 24 ASD, 12 ASD, 26.4 ASD Yes 8 sec 300 sec Example 4 80 ASD, 40 ASD, 98.5 ASD Yes 3 sec 30 sec Example 5 30 ASD, 12 ASD, 32.1 ASD Yes 2 sec 300 sec Compara- 20 ASD, 12 ASD, 26.4 ASD No tive ex- 6 sec 2500 sec ample 2

Example 6 and Comparative Example 3

(28) FIG. 6 is a schematic diagram showing another electrodeposition system used in the present example and comparative example. The electrodeposition system comprised: an anode 11 and a cathode 12 immersed into a plating solution and respectively electrically connected to a direct current power supply 15. Herein, the anode 11 was a dimensional stable anode (DSA), which has a mesh structure and is formed by a Ti mesh coated with IrO.sub.2. The cathode 12 was a rotated Ti roll. During the electrodeposition, the rotation rate of the cathode 12 was 800 rpm. The used plating solution comprised CuSO.sub.4 (the Cu ion concentration being 60 g/L), HCl (the Cl ion concentration being 30 mg/L), H.sub.2SO.sub.4 (90 g/L) and lattice modification agent (2 ml/L). The temperature for electrodeposition was 50° C. The current density and time for electrodeposition are listed in the following Table 3.

(29) After electrodeposition, the nano-twinned copper was growth on the surface of the cathode 12, and the thicknesses of the obtained nano-twinned copper layers were about 12 μm. The obtained nano-twinned copper layers were peeled off and tested by the aforesaid tensile test and observed by metallographic observation. The results of the tensile test are shown in the following Table 3 and FIG. 8, and the cross-sectional focused ion beam photo of the nano-twinned copper layer prepared in Comparative example 3 is shown in FIG. 7.

(30) TABLE-US-00003 TABLE 3 First current Second current Maximum Elongation density time density, time tensile rate Example 6 60 ASD, 50 ASD, 756 MPa 4.3% 5 sec 72 sec Comparative 60 ASD, — 657 MPa 3.1% example 3 65 sec

(31) The cross-sectional focused ion beam photo of the nano-twinned copper layer prepared in Example 6 (figure not shown) indicates that the angle included between two adjacent columnar crystal grains is greater 20° and less than or equal to 60°, and the crystal grains comprise nano-twins. However, the cross-sectional focused ion beam photo of the nano-twinned copper layer prepared in Comparative example 3 (as shown in FIG. 7) indicates that the obtained crystal grains are not columnar crystal grains and do not have preferred direction even though the crystal grains comprises nano-twins. In addition, the results of the tensile test shown in Table 3 and FIG. 8 indicate that the nano-twinned copper layer of Example 6 in which the nano-twinned columnar crystal grains are highly crossed has better tensile strength and elongation rate, compared to the nano-twinned copper layer of Comparative example 3 which has non-columnar nano-twinned crystal grains without preferred direction.

(32) The nano-twinned copper layer of the present disclosure has the feature that the angle included between two adjacent columnar crystal grains is greater 20° and less than or equal to 60°. In addition, the nano-twinned copper layer of the present disclosure has improved elongation rate. Thus, the applications of the nano-twinned copper layer of the present disclosure can further be extended.

(33) Although the present disclosure has been explained in relation to its embodiment, it is to be understood that many other possible modifications and variations can be made without departing from the spirit and scope of the disclosure as hereinafter claimed.