WO2023116636A1 - Twinned copper material, preparation method and use - Google Patents

Abstract

Disclosed in the present invention are a twinned copper material, a preparation method and a use. The twinned copper material has a preferential (110) crystal plane orientation; the twinned copper material comprises a twinned structure, the twinned structure comprises twinned lamellae, and the twinned lamellae are mainly distributed at an included angle of 45° with a grain growth direction; the proportion of grains having the twinned lamellae in the total number of grains of the twinned copper material is≥50%, and/or the ratio of the volume of the twinned structure to the total volume of the twinned copper material is≥50%. The twinned copper material provided by the present invention is preferential (110) crystal plane orientation annealing twinned copper, in which a high proportion of twin boundaries are stable, and compared with preferential (110) crystal plane height orientation electroplating micron twinned copper, the twinned copper material has more excellent structural thermal stability; there is no abnormal growth of grains within a common thermal treatment temperature range, and the unique property that the proportion of the twinned lamellae is not reduced but increased is showed.

Description

A kind of twinned copper material and its preparation method and application technical field

The invention relates to the technical field of production of high-performance metal materials and special alloy materials, in particular to a twinned copper material and its preparation method and application.

Background technique

Electroplated copper is the basic interconnection material of electronic circuits, responsible for signal and power transmission. The micro-nano structure and thermal stability of electroplated copper are important factors affecting the mechanical properties of materials at room temperature and high temperature. Since the manufacturing process involves multiple high-temperature processes such as resin curing and solder welding, electroplated copper inevitably undergoes grain boundary migration and grain growth under the action of recrystallization, which usually leads to a decrease in material strength.

The strength of traditional copper-based structural materials is mainly improved through solid solution strengthening, fine-grain strengthening, and processing strengthening, but the introduction of a large number of impurities or defects often leads to a sharp decrease in the ductility and electrical conductivity of the material. Twin boundary is a special kind of subgrain boundary. Lu Ke, Institute of Metal Research, Chinese Academy of Sciences, etc. found that the introduction of a high proportion of nano-twin boundaries can hinder dislocation movement just like ordinary grain boundaries, but it is an order of magnitude smaller than the latter's ability to scatter electrons. , so as to give copper a series of advantages such as ultra-high strength, non-degraded ductility and electrical conductivity (16-25μm thick copper foil, tensile strength > 1000 MPa, elongation > 13%). Since nanotwinning is about the control of the micro-nano structure of pure copper, it has important application potential in the field of high-performance electronic circuits.

Pulse or DC electroplating nano-twinned copper process refers to the direct preparation of nano-twinned layer structure with a typical high proportion perpendicular to the growth direction by electrodeposition, that is, the so-called growth twins. The generation of a high proportion of nano-twin boundaries depends on the electroplating process and the choice of additives. The formation mechanism can be summarized as transient alternating changes such as electric field application and pause (pulse electroplating) or additive adsorption and desorption (DC electroplating), which will cause electrocrystallization. During the process, the repeated stress is temporarily accumulated and released through the nucleation of twin boundaries, that is, the formation of so-called growth twins. Since the copper deposition tends to grow along the low surface energy (111) crystal plane and the stacking fault energy is low, the twin boundaries grow oriented parallel to the (111) crystal plane. Compared with ordinary grain boundaries, nano-twin boundaries have lower energy and are more stable. A high proportion of nano-twin boundaries can inhibit grain boundary migration and grain growth during heat treatment or self-annealing and recrystallization, thereby making nano-twins The structure shows thermal stability better than that of general copper structures such as nano-crystal, micro-grain and coarse-grain. It can be seen from the above that the material exhibits a highly preferred orientation of (111) crystal planes. Due to the introduction of high-density nano-twin boundaries, the material is endowed with ultra-high strength without compromising its ductility and conductivity, so it has been widely reported. .

Nowadays, the research on copper materials with a high proportion of twin boundaries (referred to as twinned copper materials) is still mainly carried out around the preferred orientation of (111) crystal planes and electroplating growth twins, and other practical ones such as (110) low A method for preparing twinned copper materials with preferred orientation of exponential crystal planes. The Chin Chen team of Taiwan Chiao Tung University reported an electroplating method for the so-called micro-twinned copper with a highly preferred orientation of (110) crystal plane (Materials 2020, 13, 1211), which is compatible with the highly preferred orientation of (111) crystal plane and small grain size. (0.8μm) and small twinned layer spacing (35 nm) in contrast to electroplated nano-twinned copper. This material also has a certain proportion of twinned layers, but the difference is that the grain size is larger (4.4 μm) and the twinned layer The spacing is wide (387 nm) and parallel to the growth direction. The structure was annealed at 250°C for 10 minutes, and obvious recrystallization occurred, the grain grew obviously, and the twinned wafer layer disappeared. Therefore, the so-called micro-twinned copper material is only shown as a counter example due to the poor thermal stability of the structure.

In summary, other practical twinned copper materials such as (110) low-index crystal plane preferred orientation and their preparation methods have not been reported. It is of great significance to study them to obtain more practical twinned copper materials.

technical problem

In view of the above-mentioned problems existing in the prior art, the object of the present invention is to provide a twinned copper material and its preparation method and application.

technical solution

For reaching above-mentioned purpose, the present invention adopts following technical scheme:

In a first aspect, the present invention provides a twinned copper material, the twinned copper material has a preferred orientation of (110) crystal plane, the twinned copper material includes a twinned structure, and the twinned structure includes a twinned wafer layer, The twinned crystal layer is mainly distributed along an angle of 45° with the grain growth direction; the grains with the twinned crystal layer account for ≥ 50% of the total grains of the twinned copper material, and/or the The ratio of the volume of the twin structure to the total volume of the twin copper material is greater than or equal to 50%.

In the present invention, "mainly" in "the twinned layer is mainly distributed along an angle of 45° with the grain growth direction" refers to more than 50% (such as 52%, 55%, 60%, 65%, 70%) , 75%, 80%, 85%, 90%, 92%, 95%, 96%, 98%, 99% or 100%, etc.) of twin wafer layers. The "included angle" refers to the acute angle between the twinned layer and the grain growth direction.

In the present invention, the proportion of grains having the twinned wafer layer in the total number of grains of the twinned copper material can be, for example, 50%, 55%, 60%, 65%, 70%, 75%, 80% %, 85%, 90%, 95%, 97%, 98% or 99%, etc.

In the present invention, the ratio of the volume of the twinned structure to the total volume of the twinned copper material can be, for example, 50%, 52%, 55%, 60%, 63%, 65%, 70%, 75%, 80% %, 85%, 88%, 90%, 95%, 97%, 98% or 99%, etc.

The twinned copper material provided by the present invention is an annealed twinned copper with preferred orientation of (110) crystal plane, in which a high proportion of twin grain boundaries exists stably. More excellent thermal stability of the structure, no abnormal grain growth in the common heat treatment temperature range of electronic materials (such as 200 ° C ~ 400 ° C), and exhibits the unique property that the proportion of twin wafer layers does not decrease but increases.

The twinned copper material of the present invention can be applied to the electroplating copper-related fields represented by the manufacturing and packaging of integrated circuits and circuit boards, and optimize the stability of the heat-treated structure of the electroplated copper material, that is, by introducing heat treatment to generate and stabilize the twin crystal structure, and inhibit the crystal structure. The abnormal growth of grains in this process and the decline of material strength.

The following are preferred technical solutions of the present invention, but not as limitations on the technical solutions provided by the present invention. Through the following preferred technical solutions, the technical objectives and beneficial effects of the present invention can be better achieved and realized.

Preferably, XRD diffraction analysis is performed on the twinned copper material, and the (220)/(111) diffraction peak intensity ratio is greater than 2, such as 3, 4, 5, 6, 7, 8, 9 or 10, etc. The higher the intensity ratio, the more crystal grains grow along the (110) crystal plane, and the 45° growth orientation of the twin layer and the grain growth direction is stronger.

Preferably, the twinned copper material is obtained by heat-treating the pre-electroplated copper material with a preferred orientation of (111) crystal plane, and the temperature of the heat treatment is ≥200°C. Exemplarily, the temperature of the heat treatment may be 200°C, 220°C, 240°C, 260°C, 300°C, 350°C, 400°C, or 450°C.

In the present invention, the pre-electroplated copper material refers to an electroplated copper material without annealing treatment.

By heat treatment of the pre-electroplated copper material, the preferred orientation of the (111) crystal plane can be transformed into the preferred orientation of the (110) crystal plane, accompanied by the formation of a high proportion of annealing twins, and the twin crystal layer is mainly sandwiched with the grain growth direction. Angle distribution of 45°, the resulting twinned copper material exhibits excellent thermal stability.

In an optional embodiment, the heat treatment is annealing. See Figure 6 for a schematic diagram of product structure changes before and after annealing.

In a second aspect, the present invention provides a method for preparing the twinned copper material as described in the first aspect, the preparation method comprising the following steps:

(1) Preparation of plating solution

The plating solution contains copper ions, sulfuric acid, chloride ions, additives and water, the additives include inhibitors and auxiliary agents, and the auxiliary agents are selected from at least one of organic sulfonates;

(2) DC electroplating

Immerse the anode and the cathode as a conductive substrate in the plating solution, and perform electroplating to obtain a pre-electroplated copper material;

(3) performing heat treatment on the pre-electroplated copper material, the temperature of the heat treatment being ≥ 200° C. to obtain the twinned copper material.

In the present invention, the heat treatment temperature is ≥200°C, such as 200°C, 225°C, 260°C, 280°C, 300°C, 320°C, 350°C, 370°C, 400°C, 450°C, 500°C, 550°C, 600°C , 650°C, 700°C or 750°C, etc.

The invention opens up a preparation method of a novel (110) crystal plane highly preferred orientation and annealing twin type twinned copper material. Different from the formation of growth twins in one step of electroplating, in the method of the present invention, the formation of annealing twins specifically includes two steps of pre-electroplating copper and annealing treatment. Specifically, using the chemical regulation of the pre-plating additive combination, the pre-electroplating copper material is expressed as A certain (111) crystal plane preferred orientation and no high proportion of growth twins perpendicular to the growth direction are formed. After heat treatment at ≥200°C (such as annealing for 1 hour), it will be transformed into a (110) crystal plane preferred orientation, accompanied by a high proportion of annealing For the formation of twins, the twinned lamellar layers are mainly distributed along an angle of 45° with the grain growth direction. There is no abnormal grain growth in the common heat treatment temperature range, thus showing excellent thermal stability.

In the method of the present invention, the additive combination of pre-plating has important influence on the structure of pre-plating material: by adding inhibitor in plating solution, can reduce deposition rate, avoid crystallization coarse and dense; By adding auxiliary agent in plating solution, It can increase the deposition rate, realize the dynamic and controllable desorption of the electric double layer inhibitor through the competition between the auxiliary agent and the inhibitor, and introduce the necessary concentration of electric crystallization defects for incubating the annealing twin boundary.

The method of the present invention replaces conventional electroplating with annealing twins to directly obtain growth twins, which can ensure the stable existence of a high proportion of twin boundaries in the heat treatment process, and opens up a new path for the preparation and application of (110) crystal plane highly preferred orientation twinned copper materials. new ideas.

Preferably, the organic sulfonate in step (1) includes at least one of polystyrene sulfonate, polyethylene sulfonate, alkyl sulfonate and alkylbenzene sulfonate.

Preferably, the molecular weight of the polystyrene sulfonate and the polyethylene sulfonate is independently 1000-100000, such as 1000, 3000, 5000, 8000, 10000, 12500, 15000, 17000, 20000, 25000, 35000 , 40000, 50000, 60000, 70000, 80000 or 100000 etc.

Preferably, the number of carbon atoms of the alkyl sulfonate and alkylbenzene sulfonate is ≥ 12, for example, the number of carbon atoms may be 12, 13, 14, 15, 16, 17 or 20, etc. It should be noted that the number of carbon atoms of the alkylsulfonate and the alkylbenzenesulfonate may be the same or different.

Preferably, the concentration of the auxiliary agent in the plating solution in step (1) is 10-500ppm, such as 10ppm, 20ppm, 30ppm, 40ppm, 50ppm, 60ppm, 70ppm, 80ppm, 100ppm, 150ppm, 200ppm, 230ppm, 260ppm, 300ppm, 350ppm, 400ppm or 500ppm etc.

Preferably, the inhibitor in step (1) is gelatin.

Preferably, the coagulation value of the gelatin is 10-300 bloom, such as 10 bloom, 20 bloom, 30 bloom, 50 bloom, 70 bloom, 80 bloom, 100 bloom, 125 bloom, 150 bloom, 180 bloom, 200 bloom, 225 bloom , 240 bloom, 260 bloom or 300 bloom, etc.

Preferably, the concentration of the inhibitor in the plating solution in step (1) is 5-200ppm, such as 5ppm, 10ppm, 20ppm, 30ppm, 40ppm, 50ppm, 60ppm, 70ppm, 80ppm, 100ppm, 120ppm, 150ppm, 180ppm or 200ppm, etc. .

Preferably, in step (1), the concentration of copper ions in the plating solution is 20-70g/L, such as 20 g/L, 30g/L, 40g/L, 50g/L, 60g/L or 70g/L wait.

In the actual preparation process, copper ions can be obtained from copper salts, for example, copper sulfate pentahydrate (CuSO ₄ ·5H ₂ O).

Preferably, in step (1), the concentration of sulfuric acid in the plating solution is 20-200g/L, such as 20g/L, 25g/L, 30g/L, 35g/L, 40g/L, 50g/L, 60g /L, 70g/L, 80g/L, 100g/L, 120g/L, 150g/L, 160g/L, 180g/L or 200g/L etc.

In the actual preparation process, sulfuric acid can be derived from concentrated sulfuric acid, for example, it can be obtained by diluting 96wt%~98wt% concentrated sulfuric acid (H ₂ SO ₄ ).

Preferably, in step (1), the concentration of chloride ions in the plating solution is 20-80 ppm, such as 20 ppm, 30 ppm, 40 ppm, 45 ppm, 50 ppm, 60 ppm, 70 ppm or 80 ppm.

In the actual preparation process, chloride ions can be derived from hydrochloric acid.

Preferably, in step (2), the anode is selected from phosphor copper anodes.

Preferably, the phosphorus content in the phosphor copper anode is 0.03-0.075wt.%, such as 0.03wt.%, 0.04wt.%, 0.05wt.%, 0.06wt.% or 0.07wt.%.

In an optional embodiment, the phosphorus copper anode is subjected to electrolytic activation treatment. The conditions of the electrolytic activation treatment are not specifically limited in the present invention. For example, in a plating solution containing only copper ions, sulfuric acid and chloride ions, 1 A/ ^dm2 constant current electrolysis for 30 min, or other electrolytic activation parameters commonly used in this field, but it is necessary to ensure that a uniform black phosphide film is formed on the surface of the material.

Preferably, in step (2), the electroplating temperature is 20-50°C, such as 20°C, 23°C, 25°C, 28°C, 30°C, 35°C, 40°C, 45°C or 50°C.

Preferably, in step (2), the electroplating is performed under constant temperature conditions.

Preferably, in step (2), the current density of the electroplating is 0.5-25A/dm ² , such as 0.5A/dm ² , 1A/dm ² , 1.5A/dm ² , 2A/dm ² , 3A/dm ² , 4A/dm ² , 5A/dm ² , 6A/dm ² , 7A/dm ² or 8A/dm ² , 8.5A/dm ² , 9A/dm ² , 10A/dm ² , 11A/dm ² , 12A/dm 2 ² , 15A/dm ² , 18A/dm ² , 20A/dm ² , 21A/dm ² , 22A/dm ² , 23A/dm ² or 25A/dm ² , etc.

Preferably, in step (2), the electroplating time is 20-1800 min, such as 20 min, 30 min, 40 min, 60 min, 80 min, 90 min, 120 min, 150 min, 180 min, 200 min, 240 min, 280 min, 300 min, 350 min, 450 min , 500min, 550min, 600min, 700min, 800min, 850min, 900min, 1000min, 11000min, 1200min, 1250min, 1300min, 1400min, 1500min, 1600min, 1700min or 1750min

Preferably, stirring is also applied to the electroplating solution during the electroplating process described in step (2).

Preferably, the agitation includes at least one of circulating jet flow, air agitation, magnetic agitation and mechanical agitation.

As a preferred technical solution of the preparation method of the present invention, the heat treatment in step (3) includes annealing treatment;

Preferably, the heat treatment in step (3) includes: heating the pre-electroplated copper material from room temperature to a heat treatment temperature in an inert atmosphere, keeping it warm for a certain period of time, and finally returning to room temperature.

In the present invention, room temperature refers to 20-25°C.

Preferably, the temperature of the heat treatment is 200-750°C, such as 200°C, 225°C, 260°C, 280°C, 300°C, 320°C, 350°C, 370°C, 400°C, 450°C, 500°C, 550°C , 600°C, 650°C, 700°C or 750°C, etc., preferably 200-400°C.

Preferably, the heating rate is 1-50°C/min, such as 1°C/min, 2°C/min, 3°C/min, 5°C/min, 8°C/min, 10°C/min, 12°C/min min, 15°C/min, 17°C/min, 20°C/min, 23°C/min, 25°C/min, 30°C/min, 33°C/min, 36°C/min, 40°C/min, 45°C/min min or 50°C/min, etc.

Preferably, the incubation time is 20-1200min, such as 20min, 30min, 40min, 60min, 80min, 90min, 120min, 150min, 180min, 200min, 240min, 280min, 300min, 350min, 450min, 500min, 550min, 600min , 700min, 800min, 850min, 900min, 1000min, 11000min or 1200min, etc.

In the present invention, the gas in the inert atmosphere includes but not limited to at least one of nitrogen, helium, argon and hydrogen.

The type of conductive substrate is not specifically limited in the present invention, for example, metal copper, titanium, tantalum, gold, tungsten, cobalt, nickel and an alloy formed by at least two of the above metals can be selected, or the above-mentioned Alloy boards, films, printed circuit boards, wafer seed layers and other materials.

The preparation method of the conductive substrate is not limited in the present invention, for example, electroplating, electroless plating, sputtering, casting and other methods can be selected for preparation.

In the present invention, the conductive substrate can be pre-treated before use. For example, for a substrate with oil stains and oxides on the surface, it can be fully degreased, pickled and washed before the substrate is used, so as to completely remove the surface oil and oxides. oxides, thereby exposing a fresh and clean substrate surface.

The degreasing process can choose 10wt% sodium hydroxide (NaOH) solution soaking and stirring or other degreasing methods commonly used in this field.

For the pickling process, immersion and agitation in 5wt% sulfuric acid (H ₂ SO ₄ ) solution or other methods commonly used in this field to remove oxides can be selected.

As a further preferred technical solution of the preparation method of the present invention, the method comprises the following steps:

(1) Preparation of plating solution

Dissolve copper salts, sulfuric acid, chlorides, inhibitors and auxiliary agents in water, and disperse them evenly to obtain a plating solution, which contains copper ions 20-70 g/L, sulfuric acid 20-200 g/L, chlorine Ion 20-80ppm, inhibitor 5-200ppm, auxiliary agent 10-500ppm and the balance of water, the inhibitor includes gelatin, and the auxiliary agent is selected from at least one of organic sulfonates;

(2) DC electroplating

Immerse the anode and the cathode as the conductive substrate in the plating solution, and plate at a constant current at a temperature of 20-50°C, with a current density of 0.5-25A/dm ² and a plating time of 20-1800min, to obtain pre-plating copper material;

(3) Heating the pre-plated copper material to ≥200° C. and maintaining it for 20-1200 min to obtain the twinned copper material.

In a third aspect, the present invention provides an application of the twinned copper material as described in the first aspect, and the twinned copper material is used in integrated circuit packaging or printed circuit board manufacturing.

Beneficial effect

Compared with the prior art, the present invention has the following beneficial effects:

(1) The twinned copper material provided by the present invention is an annealed twinned copper with preferred orientation of (110) crystal plane, in which a high proportion of twin grain boundaries exists stably, compared with the highly preferred orientation of (110) crystal plane micron twinned Copper has more excellent thermal stability of the structure. In the common heat treatment temperature range in the field of electronic materials (such as 200°C-400°C), the grains do not grow abnormally, and it shows the unique property that the proportion of twinned crystal layers does not decrease but increases.

(2) The preparation method of the present invention is based on the electroplating copper process and heat treatment technology. By controlling the combination of electroplating solution additives and applying heat treatment to the coating and other simple means, the preferred orientation of the electroplated copper crystal plane can be changed and a high proportion of annealing twins can be produced. It has the advantages of easy operation, low cost, strong practicability, and suitable for industrialization promotion. It can be applied to the electroplating copper-related fields represented by the manufacturing and packaging of integrated circuits and circuit boards, and optimize the stability of the heat-treated tissue structure of electroplated copper materials.

Description of drawings

Fig. 1 is embodiment 1 annealed twin crystal coating material cross section focused ion beam micrograph;

Fig. 2 is the surface X-ray diffraction spectrogram before and after annealing of embodiment 1 annealing twin crystal coating material;

Fig. 3 is embodiment 2 annealed twin crystal coating material cross section focused ion beam micrograph;

Fig. 4 is the micrograph of the focused ion beam microscopic appearance of the cross-section of the growth twin coating material of Comparative Example 1;

Fig. 5 is the X-ray diffraction spectrum of the coating surface when the growth twin coating material of Comparative Example 1 is not annealed.

Fig. 6 is a schematic diagram of product structure changes before and after annealing in an embodiment of the present invention.

Embodiments of the present invention

The technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and through specific implementation methods.

Example 1

This embodiment provides a twinned copper material, which is prepared by the following method, the method comprising the following steps:

(1) Plating solution preparation

Prepare the electroplating solution with the following component ratios and disperse evenly: 30 g/L of copper ions, 30 g/L of sulfuric acid, 30 ppm of chloride ions, 80 ppm of inhibitors, 300 ppm of auxiliary agents, and 250 mL of pure water; among them, the inhibitor has a condensation value of 100 Bloom's gelatin, the auxiliary agent is sodium polystyrene sulfonate with a molecular weight of 40,000.

(2) DC electroplating

a. Cathode pretreatment. The high-purity titanium plate is used as the cathode, and it undergoes the processes of alkali washing, pickling, and water washing in sequence.

b. DC plating. Immerse the titanium plate cathode and phosphorus copper anode (phosphorus content 0.05 wt.%) in the plating solution, apply 300 rpm magnetic stirring, and control the constant temperature of the plating solution at 25 °C. Then the rectifier was connected, and the plating was performed at a current density of 3 A/dm ² for 120 min.

c. Coating post-treatment. The coating is taken out from the plating solution and separated from the substrate (titanium plate), the coating is repeatedly rinsed with pure water to remove the residual plating solution, and finally the surface of the coating is dried with compressed air.

(3) Annealing treatment.

Put the coating in a tube furnace, pass in a nitrogen protective atmosphere, set the temperature in the furnace to rise from room temperature to 350 °C at 10 °C/min and keep it warm for 1 hour, then cool naturally, take out the coating, and obtain twinned copper material, and then Called the annealing twin coating material.

Figure 1 and Figure 2 show the obtained coating cross-section focused ion beam microscopic topography and surface X-ray diffraction spectrum. The thickness of the coating is 310 μm, mainly columnar grains parallel to the growth direction, and no abnormally grown grains are observed. The nano-twinned layer is at an angle of 45° to the growth direction of the coating, and the grains with the nano-twinned layer account for more than 90% of the total number of coating grains. The coating has a preferred orientation of the (220) crystal plane (ie (110) crystal plane), and the (220)/(111) diffraction peak intensity ratio is >9.

Example 2

This embodiment provides a twinned copper material, which is prepared by the following method, the method comprising the following steps:

(1) Plating solution preparation

Prepare the electroplating solution with the following composition ratio and disperse evenly: copper ion 40 g/L, sulfuric acid 40 g/L, chloride ion 40 ppm, inhibitor 100 ppm, auxiliary agent 500 ppm, pure water 250 mL; among them, the inhibitor is a condensation value of 100 Bloom's gelatin, the auxiliary agent is sodium octadecyl sulfonate.

(2) DC electroplating

a. Cathode pretreatment. The high-purity titanium plate is used as the cathode, and it undergoes the processes of alkali washing, pickling, and water washing in sequence.

b. DC plating. Immerse the titanium plate cathode and phosphorus copper anode (phosphorus content 0.05wt.%) in the plating solution, apply 300 rpm magnetic stirring, and control the constant temperature of the plating solution at 30°C. Then the rectifier was connected, and the plating was performed at a current density of 3 A/dm ² for 20 min.

c. Coating post-treatment. The coating is taken out from the plating solution and separated from the substrate (titanium plate), the coating is repeatedly rinsed with pure water to remove the residual plating solution, and finally the surface of the coating is dried with compressed air.

(3) Annealing treatment.

Put the coating in a tube furnace, pass it into a nitrogen protective atmosphere, set the temperature in the furnace to rise from room temperature to 2000 °C at 10 °C/min and keep it warm for 1 hour, then cool naturally, take out the coating, that is, obtain a twinned copper material, and Called the annealing twin coating material.

Figure 3 shows the focused ion beam microscopic topography of the obtained coating cross-section. The thickness of the coating was 15 μm, mainly columnar grains parallel to the growth direction, and no abnormally grown grains were observed. The nano-twinned layer is at an angle of 45° to the growth direction of the coating, and the grains with the nano-twinned layer account for more than 50% of the total number of coating grains.

Example 3

The difference between this example and Example 2 is that in step (3), the temperature in the furnace is set to rise from room temperature to 400° C. at 10° C./min and the temperature is maintained for 1 hour.

After testing, as the annealing temperature increases to 400°C, the preferred orientation is strengthened, the proportion of twins increases accordingly, and no abnormal growth of grains is seen, thus showing excellent thermal stability.

Comparative example 1

(1) Plating solution preparation

Prepare the electroplating solution with the following component ratios and disperse evenly: 40 g/L of copper ions, 40 g/L of sulfuric acid, 40 ppm of chloride ions, 100 ppm of inhibitors, 250 mL of pure water, and no auxiliary agent; among them, the inhibitor is a condensation value of 100 Bloom's gelatin.

(2) DC electroplating

a. Cathode pretreatment. The high-purity titanium plate is used as the cathode, and it undergoes the processes of alkali washing, pickling, and water washing in sequence.

b. DC plating. Immerse the titanium plate cathode and phosphorus copper anode (phosphorus content 0.05wt.%) in the plating solution, apply 300 rpm magnetic stirring, and control the constant temperature of the plating solution at 30°C. Then the rectifier was connected, and the plating was performed at a current density of 3 A/dm ² for 30 min.

c. Coating post-treatment. The coating is taken out from the plating solution and separated from the substrate, the coating is rinsed repeatedly with pure water to remove the residual plating solution, and finally the surface of the coating is dried with compressed air to obtain a growth twin coating.

The difference between this comparative example and Example 2 is that there is no auxiliary agent in the plating solution, and no annealing treatment is performed.

Figure 4 and Figure 5 show the obtained coating section focused ion beam microscopic topography and surface X-ray diffraction spectrum. The thickness of the coating is 18 μm, mainly columnar grains parallel to the growth direction. The high-density growth twinned layer is perpendicular to the growth direction of the coating, and the grains with the high-density nano-twinned layer account for more than 70% of the total number of coating grains.

In summary, the twinned copper material provided by the present invention is an annealed twinned copper with preferred orientation of (110) crystal plane, in which a high proportion of twin grain boundaries exists stably, compared with micron twinned crystals plated with highly preferred orientation of (110) crystal plane Copper has better structural thermal stability, no abnormal grain growth in the common heat treatment temperature range, and shows the unique property that the proportion of twinned lamellar layers does not decrease but increases.

The method of the present invention has the advantages of easy operation, low cost, strong practicability, and suitability for industrialization promotion, and can be applied to the electroplating copper-related field represented by the manufacture and packaging of integrated circuits and circuit boards, and optimizes the stability of the heat treatment tissue structure of electroplated copper materials sex.

The applicant declares that the present invention illustrates the detailed methods of the present invention through the above-mentioned examples, but the present invention is not limited to the above-mentioned detailed methods, that is, it does not mean that the present invention must rely on the above-mentioned detailed methods to be implemented. Those skilled in the art should understand that any improvement of the present invention, the equivalent replacement of each raw material of the product of the present invention, the addition of auxiliary components, the selection of specific methods, etc., all fall within the scope of protection and disclosure of the present invention.

Claims (10)

1. A twinned copper material, characterized in that the twinned copper material has a preferred orientation of (110) crystal planes, the twinned copper material includes a twinned structure, the twinned structure includes a twinned wafer layer, and the twinned The wafer layer is mainly distributed along an angle of 45° with the grain growth direction; the grains with the twinned wafer layer account for ≥ 50% of the total grains of the twinned copper material, and/or the twinned The ratio of the volume of the tissue to the total volume of the twinned copper material is ≥50%.
2. The twinned copper material according to claim 1, wherein the twinned copper material is subjected to XRD diffraction analysis, and the (220)/(111) diffraction peak intensity ratio is greater than 2.
3. The twinned copper material according to claim 1 or 2, characterized in that the twinned copper material is obtained by heat-treating a pre-electroplated copper material with a preferred orientation of (111) crystal plane, and the temperature of the heat treatment is ≥200 ℃.
4. A preparation method of the twinned copper material according to any one of claims 1-3, characterized in that the preparation method comprises the following steps:

   (1) Preparation of plating solution

   The plating solution contains copper ions, sulfuric acid, chloride ions, additives and water, the additives include inhibitors and auxiliary agents, and the auxiliary agents are selected from at least one of organic sulfonates;

   (2) DC electroplating

   Immerse the anode and the cathode as a conductive substrate in the plating solution, and perform electroplating to obtain a pre-electroplated copper material;

   (3) performing heat treatment on the pre-electroplated copper material, the temperature of the heat treatment being ≥ 200° C. to obtain the twinned copper material.
5. The preparation method according to claim 4, characterized in that the organic sulfonate in step (1) includes polystyrene sulfonate, polyethylene sulfonate, alkyl sulfonate and alkylbenzene sulfonate at least one of;

   Preferably, the molecular weights of the polystyrene sulfonate and the polyethylene sulfonate are independently 1,000-100,000;

   Preferably, the number of carbon atoms of the alkyl sulfonate and alkylbenzene sulfonate is ≥ 12;

   Preferably, the concentration of the auxiliary agent in the plating solution in step (1) is 10-500ppm;

   Preferably, the inhibitor in step (1) is gelatin;

   Preferably, the coagulation value of the gelatin is 10-300 bloom;

   Preferably, the concentration of the inhibitor in the plating solution in step (1) is 5-200ppm.
6. The preparation method according to claim 4 or 5, characterized in that, in step (1), the concentration of copper ions in the plating solution is 20-70g/L;

   Preferably, in step (1), the concentration of sulfuric acid in the plating solution is 20-200g/L;

   Preferably, in step (1), the concentration of chloride ions in the plating solution is 20-80ppm.
7. The preparation method according to any one of claims 4-6, characterized in that, in step (2), the anode is selected from phosphor copper anodes;

   Preferably, the phosphorus content in the phosphor copper anode is 0.03-0.075 wt.%;

   Preferably, in step (2), the temperature of the electroplating is 20-50°C;

   Preferably, in step (2), the electroplating is carried out under constant temperature conditions;

   Preferably, in step (2), the current density of the electroplating is 0.5-25 A/dm ² ;

   Preferably, in step (2), the electroplating time is 20-1800min;

   Preferably, stirring is also applied to the electroplating solution during the electroplating process in step (2);

   Preferably, the agitation includes at least one of circulating jet flow, air agitation, magnetic agitation and mechanical agitation.
8. The preparation method according to any one of claims 4-7, characterized in that the heat treatment in step (3) includes annealing treatment;

   Preferably, the heat treatment in step (3) includes: heating the pre-electroplated copper material from room temperature to the heat treatment temperature in an inert atmosphere, keeping it warm for a certain period of time, and finally returning to room temperature;

   Preferably, the heat treatment temperature is 200-750°C, preferably 200-400°C;

   Preferably, the heating rate is 1-50°C/min;

   Preferably, the incubation time is 20-1200min.
9. The preparation method according to any one of claims 4-8, characterized in that the method comprises the following steps:

   (1) Preparation of plating solution

   Dissolve copper salts, sulfuric acid, chlorides, inhibitors and auxiliary agents in water, and disperse them evenly to obtain a plating solution, which contains copper ions 20-70 g/L, sulfuric acid 20-200 g/L, chlorine Ion 20-80ppm, inhibitor 5-200ppm, auxiliary agent 10-500ppm and the balance of water, the inhibitor includes gelatin, and the auxiliary agent is selected from at least one of organic sulfonates;

   (2) DC electroplating

   The anode and the cathode as the conductive substrate are immersed in the plating solution, and at a temperature of 20-50°C, they are plated with a constant current, the current density is 0.5-25 A/dm ² , and the time of plating is 20-1800min. electroplated copper material;

   (3) Heating the pre-plated copper material to ≥200° C. and maintaining it for 20-1200 min to obtain the twinned copper material.
10. A use of the twinned copper material according to any one of claims 1-3, wherein the twinned copper material is used in electronic circuit interconnection scenarios, and the electronic circuit interconnection scenarios include integrated circuit packaging or printed circuit board manufacturing.