TW593711B - Sputtered copper films containing niobium for improving electrical conductivity, thermal stability and hardness properties and method for making the same - Google Patents

Abstract

This invention is concerning with the composition, properties, and production of new copper films containing niobium by sputter deposition. This invention provides an uncomplicated process to obtain copper films with various niobium contents ranging from 0 up to about 25 atomic percent. The sputter deposition process claimed involves co-sputtering of a niobium target overlaid with a copper plate. The overlay copper target with symmetrically distributed holes is fabricated so that the niobium area fraction exposed for co-sputtering is known. With control of the niobium target area fraction, a desirable niobium content in the copper film can be attained. The copper-niobium films claimed in this invention process better hardness, thermal stability and electrical conductivity properties, when compared with those of pure copper films.

Description

593711 V. Description of the invention (l)-Because copper and copper alloys have excellent electrical conductivity, thermal conductivity, and good room temperature mechanical properties, they have been widely used, but copper and copper alloys are mechanically used at high temperatures. The properties are poor, so the temperature at which these alloy materials are used is not high, so that their good electrical conductivity and thermal conductivity cannot be effectively used, which makes the use of materials impossible to break through. In addition, in recent years, due to the excellent electrical conductivity, Make copper and then replace aluminum as the conductive layer in semiconductor components 'so' copper plating or film has added more effective use value in application; but there are still some restrictions on the use of copper conductive layer in terms of process or materials , Such as easy to form oxide film and low adhesion. Copper alloys with alloying elements have become a possible choice, however, as soon as alloying elements are added, the electrical conductivity of copper decreases. In order to solve these problems, the addition of immiscible elements should be the solution. This can be known from the relevant literature of sputtered copper films.... Such as P Chu, C H. Chung, P Y Lee, J M · Rigsbee, and JY Wang, nMicrostructure and Properties of Cu-C Pseudoalloy Films Prepared by Sputter Deposition1 'Metallurgical and Materials Transactions A, 29A, pp · 647-658, (1998) · 和 JP ·

Chu and Τ · Ν · Lin, "Deposition, Microstructure and Properties of Sputtered Copper Films Containing Insoluble Molybdenum," Journal of Applied Physics' 1, 85, 6462-6469 (1999). Zhu Jin, Zhu Minsheng " Copper plating of tantalum to improve the conductivity, high temperature stability and hardness properties of copper plating and its sputter manufacturing method (patent application number: 088 1 1 3088) Traditional copper-based metal composite materials containing immiscible elements are generally based on rapidly

Page 6 593711 V. Description of the invention (2)-Cooling metallurgy technology or manufacturing by powder metallurgy, but copper-based metal composites manufactured in this way 'if used for a long time at high temperature, due to immiscible phases Coarsening will occur, resulting in a sudden loss of mechanical properties, making the material unusable. The Sputter Deposition process is used to synthesize completely immiscible elements or compounds to produce a "Supersaturated Solid Solution", which is a feature of the sputter j synthesis technology. , And it is formed by the "atomic long atom" growth method (Atom-by-atom growth), so it does not need to be limited by traditional thermodynamics such as solid solubility and phase equilibrium, and can be easily synthesized. Materials previously considered impossible, and this method can produce metal composites with a non-equilibrium and nano-scale microstructure structure, resulting in a very unique and stable Material properties and high temperature mechanical strength. These materials such as: Copper-carbon (Cu-C) series [Jp · Chu, C · H · Chung, P · Y · Lee, J · M · Rigsbee, and J · Υ · Wang, Metallurgical and Materials A, 29A , Pp · 647-658, (1 998) ·] Zhu Jin, Zhu Minsheng "Copper plating with tantalum to improve the conductivity, high temperature stability and hardness properties of copper plating and its sputter manufacturing method" (patent application Case study · 088113088). On the other hand, there are also alloy films formed by sputtering to promote phase separation at high temperatures to promote the properties of the materials; such as: Mo-Cu sputtering films at high temperatures. Precipitation promotes the bondability of solar cell wires [G. Ramanath, HZ Xiao, LC Yang, A. Rockett and LH Allen: Journal of Applied

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Physics, 1995, Vol. 78 (4), p. 2435-2440 ·]. The material choice for this creation is the immiscible copper-niobium series, and the main purpose is to provide the composition and sputtering process of different niobium content in the copper coating, from β to niobium-containing copper coating. After the experiment, the coating has a high temperature. Stability, electrical conductivity and hardness properties of the part. In order to facilitate understanding of the techniques and results used in this creation, Father Jia provided the following # best feasible examples, with accompanying tables and accompanying drawings, where: [The niobium and copper content of this creation ^ are atomic percentages (at% )] Table 1 shows the area percentage of the niobium target and the sharp content in the bond layer obtained in the examples. 5 Table 2 shows the important parameters of the sputtering process in the examples. Figure 1 shows the layout of pure copper and target material in the sputtering process in the embodiment. Figure 2 shows a top view of a pure copper target in the sputtering process and a sharp handle with a different area in one hundred and eight ratios. Figure 3 shows the relationship between the niobium content of the copper coating, the area percentage of the niobium target, and the deposition rate of the mineral layer in the embodiment. Figure 4 shows the results of X-ray photoelectron mass spectrometer (X P S) analysis of copper coatings containing niobium in the examples of the system: copper and impurities * coexist. Figure 5 shows a graph of the Lattice parameter * Nb content in the coating after the copper-free annealing temperature is maintained for one hour in the example. Figure 6 shows a cross-section micrograph of a scanning electron microscope of a copper coating containing niobium in the example: (a) pure copper recording layer, (dagger) containing, 0.4% niobium, (c) containing 4 · 5% niobium, and (d) 25% niobium copper deposits. Fig. 7 shows a scanning electron microscope of a niobium-containing copper coating in the embodiment.

593711 V. Description of the invention (4) Microphotograph of the surface (Planar View): (a) pure copper plating, and (b) copper plating containing 25% niobium. Figure 8 shows a micrograph of a cross-section of a scanning electron microscope of a sharp-copper-containing copper coating after being held at a copper-free annealing temperature for one hour in an example. (A) 200 ° C, and (b) 400 ° C . Figure 9 shows the micrographs of a scanning electron microscope surface of a niobium-containing copper coating after being held at a copper-free annealing temperature for one hour in an example: (a) 530 ° C, and (b) 750 t. Figure 10 It is the ultra-hardness value of the copper plating layer containing niobium in the example after being held at the copper-free annealing temperature for one hour. Figure 11 shows the resistivity values of the niobium-containing copper coating in the embodiment after being held at the copper-free annealing temperature for one hour. The composition of this creation: In the embodiment, five copper-niobium compositions are used. As shown in Figure 1, the copper content is 75 ~ 100%, and the sharpness is 0 ~ 25%. I. Copper plating method containing niobium in this creation: In the example of this creation, the copper plating containing sharpness is made by the Radio Frequency ^ RF Magnetron Sputter Deposition process. First, the sputtering vacuum chamber is evacuated. To a pressure of 3 × 10-7 Torr, a high-purity argon gas (Ar) is introduced into the system, and the plating operation is performed with an energy of 100 Å. Pure copper and pure niobium are the target materials. The two targets are plated in a common sputtering method (Co-Sputt ^ ring). The configuration of the two targets is not as shown in Figure 2. According to the example of the internal area percentage of the niobium target, the niobium content required in the copper coating can be obtained (—_ 娇 —, the ratio of the pre-molded knife) and Wen Xinni 3 li (not shown in Table 1).

Page 9 593711 V. Description of the invention (5) Approximately 12 centimeters below the material, and it is known that it is divided into glass (for resistance measurement) and material / material for property detection) Dynamic c 贰The objective is to find the average thickness of the bell layer i ^ copper (for micro hardness measurement ^ ^). The substrate is rotated at a constant speed. Other important parameters of the plating process are shown in Table 2. Qualitative determination of the sharp content in the copper ore layer I order and the measurement of the amount: In this creative example, the niobium content in the copper plated strike Λ Α θ was measured by an electrical analyzer (EPMA). As shown in Figure 3. According to the relationship diagram in Figure 3, I 衲 ding points τ η ▲ μ rw — we can obtain the copper layer with the required niobium content according to different sharp area ratios. At the same time, Figure 3 also illustrates the addition of sharp drops; The deposition rate of the copper coating was confirmed, and the pure steel and niobium were co-plated at the same time. However, in order to further carefully measure the niobium was dissolved in the copper coating. (Xps) analysis results: Rui and copper exist in the mineral layer at the same time as the element. Rui is in the copper layer The impact also includes that the lattice parameter (Lattice parameter) of the copper plating layer increases with the increase of niobium (as shown in Figure 5), and these increased lattice constants will decrease to varying degrees with different annealing temperatures. In addition, sharp The effect of the copper bell layer can also be known from the change of its microstructure, as shown in Figure 6, the columnar grains of the copper coating are refined from the pure copper's ~ 30Onm to ~ 20Onm's 0.4% niobium content and ~ 100 nm 25% sharp copper ore layer, in which the microstructure observation at a higher magnification shows that each grain of the copper coating with 25% niobium content is composed of several nano-crystallites (such as (Shown in Figure 7).

Page 10 593711 V. Description of the invention (6) Particular test of properties of copper coating containing niobium: In this creative example, 'the main research is to refine the microstructure of the copper coating containing niobium and the supersaturated solution of niobium in the coating, Improve the high temperature stability and ultra-hardness of copper-bearing ore layers with hammer. As shown in Figures 8 and 9, the microstructure photos of the copper ore layer after being held at different annealing temperatures for one hour. After low temperature (200C) annealing, the microstructure and structure of the copper forging layer began to change, but At 530 ° C (~ 0.6Tm), the grains in the copper plating layer begin to grow (Growth) and coalescence, while the sharp copper plating layer still has a finer microstructure. After annealing at 75 ° C (~ 0 · 8Tm), although the grains of the copper plating have grown and the original columnar structure has disappeared, the grains of the copper plating containing niobium are still smaller than those of pure copper. There are also fewer twin crystals (as shown in Figure 9), which proves its high temperature stability. Measurement results of ultra-hardness of copper coatings containing niobium, as shown by ^ 十 =, even after high temperature annealing (75 (rc, lhr)), the obtained ultra-hardness values are still less than those of pure copper coatings (up to 2.5 Times), and before or after annealing at low temperature, the ultra-hardness value is about 3 ~ 4 times, obviously showing the copper coating containing niobium and temperature stability. The resistivity measurement results of copper coating containing niobium are shown in the figure:: : Not only = a small amount of niobium (< 2.7%) 'due to the improvement of the microstructure of the coating, the resistivity value is slightly reduced, and the resistivity value of the nearly pure copper block produced by annealing at different temperatures; and , 9 plus, the more the resistivity value decreases-the appropriate amount of niobium and U are displayed, and the value of h is further displayed (two layers ^ simultaneously have high temperature stability and low plating layer have the following originality.... According to the above, this creation Niobium-containing steel (1) The original sputtering process is clean and pollution-free. The steel and niobium target are laminated. Page 11 593711 V. Description of the invention (7) The method of common sputtering is simple. Sharp content; (2) Because copper and niobium are not compatible with each other, the ultra-hardness of the copper coating containing niobium is high and has a high value Stability; (3) As the niobium content increases, the microstructure of the copper plating layer is improved, and the lower resistivity value is a good conductive ore layer, which is suitable for the semiconductor industry and can replace the currently poorly conductive aluminum. Conductive layer. In summary, the technology and composition and properties of the niobium-containing copper coatings studied in this creation have never been seen before, which meets the requirements of novelty and innovation, and has a high value in industrial use. Applicability, and has fully met the requirements of patent applications, subject to patent applications in accordance with the law. Although this creation is based on a better example of the process and alloy composition to study the excellent properties of copper coatings containing niobium, it is not intended to limit this The creation, as compared to any study of this research, can be modified and changed according to the technical ideas of this creation to achieve equivalent purposes. Therefore, the scope of protection of this creation should include the principles of this sputtering technology to achieve high temperature Niobium-containing steel coating with stability and good electrical conductivity and hardness properties.

593711 Brief description of the drawing " " " " Table 1 shows the area percentage of the niobium target in the examples and the niobium content in the resulting copper coating. Table 2 shows the important parameters of the sputtering process in the examples. Figure 1 shows the layout of pure copper and target material in the sputtering process in the embodiment. Figure 2 shows a top view of a pure copper target and a niobium target with different area percentages in the sputtering process in the embodiment. Figure 3 shows the relationship between the niobium content of the copper plating layer, the area percentage of the niobium target, and the deposition rate of the plating layer in the embodiment. Figure 4 shows the results of X-ray photoelectron mass spectrometer (XPS) analysis of the copper coatings containing niobium in the examples shown in the example: copper and sharp coexist. Figure 5 shows a graph of the lattice constant and niobium content in the coating after the copper-free annealing temperature is maintained for one hour in the embodiment. Figure 6 shows a micrograph of a cross-section of a scanning electron microscope of a sharp copper ore layer in the example shown in the example: (a) a pure steel recording layer, (b) 0.4% sharp, (c) 4.5% Sharp, and (d) a copper bell layer containing 25% niobium. Figure 7 shows a microphotograph of a scanning electron microscope (Planar view) surface of a copper coating containing niobium in the embodiment: (a) a pure copper coating, and (b) a copper coating containing 25% niobium. Figure 8 shows a micrograph of a cross-section of a scanning electron microscope of a sharp-copper-plated coating in an example after being held at the annealing temperature of stainless steel for one hour: (a) 200 ° C, and (b) 400 ° C. Figure 9 The micrographs of the scanning electron microscope surface of the copper plating layer containing niobium in the example shown in the example after being held at the annealing temperature of stainless steel for one hour: (a) 530 ° C, and (b) 750 ° C. imra men page 13 593711 Brief description of the figure Figure 10 shows the ultra-hardness value of the niobium-containing copper coating in the example after being held at the copper-free annealing temperature for one hour. Figure 11 shows the resistivity values of the niobium-containing copper coating in the embodiment after being held at the copper-free annealing temperature for one hour.

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Claims (1)

593711 ---------- i--ZΙΙΙΞΓ 6. Scope of patent application ---------- 1. A method for producing a niobium-containing copper coating by sputtering, with a niobium content of 0.4 To 25 atomic percent, the thickness of the coating is 0.5 ~ 5 // m, and the method for producing a copper plating layer containing niobium is based on a method for preparing a copper plating layer containing niobium, including: (a) vacuum, sputtering process: sputtering power is 100W Sputtering pressure is 1 * 1 0-2 ~ 1 * 10-3 torr, (b) Lamination of pure copper and sharp dry material: adjust the niobium content in the coating by the relative ratio of the area of different pure copper and sharp sheep bar material . 2. According to the method for producing an anatase-containing layer described in item 1 of the scope of the patent application, where (a) means that the sputtering temperature is from normal temperature to 100 ° C. d · According to Φ ▲ the main method of step (b), the method of manufacturing the niobium-containing copper coating described in item 1 of the patent scope, where 29.3% and 4 refer to the area ratio of sharp dry materials in order of 4.0% , 21.3%, 9 · 9 'Thus, copper coatings with different niobium contents were obtained. Page 15