Annular high-purity copper phosphorus anode for integrated circuit and preparation method of annular high-purity copper phosphorus anode

Abstract

The invention relates to the technical field of electroplating equipment, in particular to an annular high-purity copper phosphorus anode for an integrated circuit and a preparation method of the annular high-purity copper phosphorus anode. The preparation method comprises the following steps: firstly, smelting to prepare a copper-phosphorus cast ingot, then carrying out homogenization heat treatment on the cast ingot, then carrying out reverse extrusion deformation to obtain a tube blank, then carrying out low-temperature stress relief annealing treatment on the tube blank, and finally, cutting, machining and forming, cleaning, drying and packaging the tube blank to obtain the annular high-purity copper-phosphorus anode. According to the preparation method disclosed by the invention, the grain size and the component uniformity are controlled by carrying out homogenization treatment, adjusting the extrusion temperature and the extrusion ratio and carrying out low-temperature annealing treatment on a cast ingot, and meanwhile, a plurality of copper-phosphorus target blanks can be obtained at one time by cutting a copper-phosphorus alloy pipe; by means of the preparation method, it can be guaranteed that crystal grains are evenly distributed, segregation of the P element is avoided, residual stress of the material is eliminated, deformation and cracking of follow-up machining blanks are prevented, meanwhile, the technological process can be remarkably shortened, the production efficiency is improved, and the production cost is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of electroplating, and in particular to a ring-shaped high-purity copper-phosphorus anode for integrated circuits and a preparation method thereof. Background Art

[0002] In recent years, the global production capacity of 28nm and below advanced process integrated circuits has accounted for an increasingly larger proportion of the total chip manufacturing capacity. The reduction in feature size has made ultra-high purity copper and its alloys become increasingly important interconnect materials in the manufacturing process. They are used for interconnection of components within the chip in front-end wafer manufacturing and for high-density packaging and integrated interconnection between chips in back-end advanced packaging. The interconnection process is achieved using PVD sputtering or ECP electroplating processes. Ultra-high purity copper and its alloy targets and anodes and other interconnect materials have been increasingly widely used in the field of high-end integrated circuits due to their advantages in low resistivity, high resistance to electromigration, lower cost, higher wiring density and narrower wiring width. The market demand continues to grow, and they have become the main raw materials for the preparation of various electronic components in integrated circuits today. Among them, ultra-high purity copper and its alloy targets are mainly used in magnetron sputtering. The interconnection thin film materials prepared by them have the advantages of high purity, excellent conductivity and good aspect ratio coverage. The copper-phosphorus anode is mainly used in electroplating, which can achieve low-temperature and high-efficiency deposition and is used to fill through-hole interconnect structures. The P element in the copper-phosphorus anode can react with Cu + Forming a black film can accelerate the Cu + Oxidation reduces Cu + The accumulation of copper anode can reduce the shedding of small crystals from the anode, prevent the copper anode from dissolving too quickly, improve the utilization rate of the anode, and make the components more stable to a certain extent.

[0003] At present, copper-phosphorus anodes are mainly prepared by multiple plastic deformation processing and heat treatment methods. For example, Chinese patent CN102517621B discloses a method for preparing a copper-phosphorus alloy anode, which comprises the following steps: heating a copper-phosphorus ingot and then forging it, repeatedly heating and forging it for three rounds, cooling it, and then performing a second heat treatment, and then cold rolling and a third heat treatment on the blank, and finally machining the blank to obtain a copper-phosphorus anode. The copper-phosphorus anode prepared by this method can meet the requirements of electroplating, but the production process is complicated, the degree of automation is low, and there are disadvantages such as a long processing cycle, low production efficiency, and high cost. Summary of the invention

[0004] Based on the problems existing in the prior art, the present invention provides a ring-shaped high-purity copper-phosphorus anode for integrated circuits and a preparation method thereof. The specific technical scheme is as follows: A method for preparing a ring-shaped high-purity copper-phosphorus anode for integrated circuits comprises the following steps: Step 1: obtaining a copper-phosphorus melt by smelting, and performing static mold casting on the copper-phosphorus melt under a vacuum state to obtain a cylindrical ingot; Step 2: performing homogenization heat treatment on the cylindrical ingot at a temperature of 600-700° C. for 6-8 hours to obtain a homogenized ingot; Step 3: performing reverse extrusion deformation on the homogenized ingot, wherein the material temperature during the extrusion deformation process is 550-700° C. and is lower than the homogenization heat treatment temperature, the extrusion speed is 6-8 mm / s, and the extrusion ratio is 1.5-4.5, to obtain a high-purity copper phosphorus tube blank; Step 4: annealing the high-purity copper phosphorus tube blank at a temperature of 200-300° C. for a time of 1-2 h; Step 5: Cut the high-purity copper-phosphorus tube billet annealed in step 4, and then machine it using a high-precision CNC machine tool to obtain a ring-shaped high-purity copper-phosphorus anode for integrated circuits, wherein the processing accuracy of the high-precision CNC machine tool is ±0.01mm.

[0005] Furthermore, in step 1, vacuum induction melting or magnetic levitation melting is used to obtain the copper-phosphorus melt.

[0006] Furthermore, in step 1, the pouring temperature of the static mold pouring is 1100-1200° C., and the pouring time is 4-5 min.

[0007] Furthermore, the cylindrical ingot obtained in step 1 has a purity of 99.9%-99.999%, a P content of 400-650 ppm, and a diameter of 150-200 mm.

[0008] Furthermore, the furnace temperature fluctuation during the homogenization heat treatment in step 2 does not exceed ±5°C.

[0009] Furthermore, the wall thickness of the high-purity copper-phosphorus tube blank obtained in step 3 is 10-40 mm.

[0010] Furthermore, the cutting method in step 5 is high-speed sand wire cutting, and the cutting accuracy is 0.2 mm.

[0011] Furthermore, in step 5, a high-precision CNC machine tool is used to process the outer diameter, inner diameter, upper surface and lower surface of the high-purity copper phosphorus tube blank to obtain an annular finished product, wherein the inner diameter of the annular finished product is 220-270 mm, the outer diameter is 270-300 mm, the wall thickness is 10-40 mm, and the height is 30-40 mm.

[0012] Furthermore, the integrated circuit obtained in step 5 is further cleaned, vacuum dried and plastic-sealed using the annular high-purity copper-phosphorus anode.

[0013] A ring-shaped high-purity copper-phosphorus anode for integrated circuits prepared according to the preparation method has a grain size of 100-300 μm.

[0014] The beneficial effects of the present invention are: (1) The present invention provides a method for preparing a ring-shaped high-purity copper-phosphorus anode for integrated circuits. Compared with the traditional preparation method of a single target blank by multiple plastic deformation + heat treatment, the method of the present invention directly prepares a copper-phosphorus alloy tube through a one-time hot extrusion molding technology, and obtains multiple copper-phosphorus tube blanks at one time through sand wire cutting, which solves the shortcomings of the traditional preparation method such as complicated production procedures, long processing cycle, low production efficiency and high cost, and can improve production efficiency by more than 50%.

[0015] (2) The present invention provides a method for preparing a ring-shaped high-purity copper-phosphorus anode for integrated circuits, wherein the preparation of the high-purity copper-phosphorus ingot involves a vacuum induction melting method or a magnetic levitation melting method, combined with a static mold casting method under a vacuum state, by controlling the pouring temperature and time, and controlling the pouring speed, so as to obtain a cylindrical ingot with a smooth surface, uniform composition distribution, and no internal defects, and the yield rate can reach more than 95%.

[0016] (3) The present invention provides a method for preparing a ring-shaped high-purity copper-phosphorus anode for integrated circuits. First, a homogenization heat treatment is performed to make the internal chemical composition of the copper-phosphorus ingot more uniform, reduce the segregation of the P element, and improve the quality stability of the electroplated film of the product. Subsequently, the grain size is controlled by adjusting the extrusion temperature and the extrusion ratio to obtain uniform and fine equiaxed grains with an average grain size of ≤250μm, thereby avoiding the stratification of the internal structure of the copper-phosphorus alloy and improving the uniformity of the electroplated film of the product. Finally, after a low-temperature annealing process, the annealing temperature is ensured to be lower than the recrystallization temperature of the copper-phosphorus alloy, the residual stress is eliminated, the deformation and cracking of the subsequent processed blank is prevented, and the recrystallization and growth of the internal structure of the copper-phosphorus alloy are prevented. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The embodiments of the present invention are further described below with reference to the accompanying drawings, in which: Figure 1 The present invention is a flow chart for preparing a ring-shaped high-purity copper-phosphorus anode for integrated circuits; Figure 2 50X microstructure diagram of the copper phosphorus anode blank in Example 1 of the present invention; Figure 3 50X microstructure diagram of the copper phosphorus anode blank in Example 2 of the present invention; Figure 4 This is a 50X microstructure image of the copper phosphorus anode blank in Example 3 of the present invention. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below through specific embodiments in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0019] Example 1 The manufacturing process of a high-purity annular copper-phosphorus anode with a purity of 4N5, a P content of 525ppm and a size of Φ (297-270) * 38mm mainly includes the following steps: (1) Preparation of high-purity copper-phosphorus ingots: High-purity copper-phosphorus ingots were obtained by vacuum induction melting and static mold casting. The casting temperature of static mold casting was 1100°C and the casting time was 5 min. In the early stage of casting, a uniform and large-flow casting rate of 38 kg / min was maintained. After 2.5 minutes, the flow rate was reduced to 26 kg / min and the casting was slow. After melting, the ingot had a diameter of 200 mm and a length of 580 mm.

[0020] (2) Homogenization heat treatment: The ingot is subjected to homogenization heat treatment. After the furnace temperature reaches the set temperature, the smelted ingot, i.e., the cylindrical ingot, is added to the heating furnace. The heating temperature is 700±5°C. The timing starts after the temperature is returned to normal. The heating time is 6.5h±10min. The temperature fluctuation at each location of the heat treatment furnace does not exceed ±5°C. Homogenization heat treatment at this temperature makes the internal chemical composition of the copper-phosphorus ingot more uniform and reduces the segregation of the P element.

[0021] (3) Preparation of high-purity copper-phosphorus alloy pipes: The ingot was extruded and deformed using a 3000T reverse extruder. The extrusion temperature was controlled at 680±10°C, the extrusion speed was 7 mm / s, and the extrusion ratio was 2.1. After extrusion, the outer diameter of the copper-phosphorus pipe was 300 mm and the wall thickness was 17 mm.

[0022] (4) Stress relief annealing: Immediately perform non-vacuum heat treatment on the copper-phosphorus tube after hot extrusion, put it into the furnace when it reaches the temperature, and when the temperature is returned to the furnace, the heating temperature is 230±10℃, the heating time is 1.5h±10min, and the temperature fluctuation of each part of the heat treatment furnace does not exceed ±5℃. The heat treatment temperature is lower than the recrystallization temperature of the copper-phosphorus alloy. While eliminating residual stress and preventing deformation and cracking of the subsequent processed blank, it also prevents the internal structure of the copper-phosphorus alloy from recrystallizing and growing.

[0023] (5) Preparation of high-purity copper-phosphorus target blanks and machining, forming, cleaning, drying and packaging of copper-phosphorus anodes: The copper-phosphorus alloy tube is cut into single copper-phosphorus target blanks with a height of 38±1 mm by high-speed sand wire cutting. After cutting a single alloy tube, the number of target blanks is 28. Subsequently, the tube blank is processed by a CNC milling machine to obtain a ring-shaped copper-phosphorus anode product. The surface of the finished anode is cleaned to remove dirt, and then placed in a vacuum oven for drying. After cooling, a vacuum bag is used to vacuum seal it to prevent anodization.

[0024] Metallographic analysis: The metallographic analysis of the samples taken from the above blanks finally revealed a grain size of 170 μm. Figure 2 . Example 2

[0025] The manufacturing process of a high-purity annular copper-phosphorus anode with a purity of 4N, a P content of 450ppm, and a size of Φ (285-265) * 35mm mainly includes the following steps: (1) Preparation of high-purity copper-phosphorus ingots: High-purity copper-phosphorus ingots were obtained by vacuum induction melting and static mold casting. The casting temperature of static mold casting was 1150°C and the casting time was 5 min. In the early stage of casting, a uniform and large flow rate of 40 kg / min was maintained. After 3 minutes, the flow rate was reduced to 20 kg / min and the casting was slow. After melting, the ingot had a diameter of 200 mm and a length of 580 mm.

[0026] (2) Homogenization heat treatment: The ingot is subjected to homogenization heat treatment. After the furnace temperature reaches the set temperature, the smelted ingot, i.e. the cylindrical ingot, is added into the heating furnace. The heating temperature is 680±10℃. The timing starts after the temperature returns to normal. The heating time is 7h±10min. The temperature fluctuation at each location of the heat treatment furnace does not exceed ±5℃.

[0027] (3) Preparation of high-purity copper-phosphorus alloy pipes: The ingot was extruded and deformed using a 3000T reverse extruder. The extrusion temperature was controlled at 630±10°C, the extrusion speed was 6 mm / s, and the extrusion ratio was 2.8. After extrusion, the outer diameter of the copper-phosphorus pipe was 288 mm and the wall thickness was 13 mm.

[0028] (4) Stress relief annealing: Immediately perform non-vacuum heat treatment on the copper-phosphorus tube after hot extrusion, put it into the furnace when it reaches the temperature, and time the return to temperature. The heating temperature is 280±10℃, the heating time is 1.2h±10min, and the temperature fluctuation of each part of the heat treatment furnace does not exceed ±5℃.

[0029] (5) Preparation of high-purity copper-phosphorus target blanks and machining, forming, cleaning, drying and packaging of copper-phosphorus anodes: The copper-phosphorus alloy tube is cut into a single copper-phosphorus target blank with a height of 39±1 mm by high-speed sand wire cutting. The number of target blanks after cutting a single alloy tube is 40. The tube blank is then processed by a CNC milling machine to obtain a ring-shaped copper-phosphorus anode product. The surface of the finished anode is cleaned to remove dirt, and then placed in a vacuum oven for drying. After cooling, it is vacuum-sealed using a vacuum bag to prevent anodization.

[0030] Metallographic analysis: The metallographic analysis of the samples taken from the above blanks finally revealed a grain size of 120 μm. Figure 3 . Example 3

[0031] The manufacturing process of a high-purity annular copper-phosphorus anode with a purity of 3N5, a P content of 600ppm and a size of Φ (276-240) * 30mm mainly includes the following steps: (1) Preparation of high-purity copper-phosphorus ingots: High-purity copper-phosphorus ingots were obtained by vacuum induction melting and static mold casting. The casting temperature of static mold casting was 1200°C and the casting time was 4 min. In the early stage of casting, a uniform and large flow rate of 40 kg / min was maintained. After 2.5 min, the flow rate was reduced to 20 kg / min and the casting was slow. After melting, the ingot had a diameter of 180 mm and a length of 580 mm.

[0032] (2) Homogenization heat treatment: The ingot is subjected to homogenization heat treatment. After the furnace temperature reaches the set temperature, the smelted ingot, i.e. the cylindrical ingot, is added into the heating furnace. The heating temperature is 650±10℃. The timing starts after the temperature returns to normal. The heating time is 7.5h±10min. The temperature fluctuation at each location of the heat treatment furnace does not exceed ±5℃.

[0033] (3) Preparation of high-purity copper-phosphorus alloy pipes: The ingot was extruded and deformed using a 3000T reverse extruder. The extrusion temperature was controlled at 630±10°C, the extrusion speed was 8mm / s, and the extrusion ratio was 1.5. After extrusion, the outer diameter of the copper-phosphorus pipe was 279mm and the wall thickness was 21mm.

[0034] (4) Stress relief annealing: Immediately perform non-vacuum heat treatment on the copper-phosphorus tube after hot extrusion, put it into the furnace when it reaches the temperature, and time the return to temperature. The heating temperature is 290±10℃, the heating time is 1.2h±10min, and the temperature fluctuation of each part of the heat treatment furnace does not exceed ±5℃.

[0035] (5) Preparation of high-purity copper-phosphorus target blanks and machining, forming, cleaning, drying and packaging of copper-phosphorus anodes: The copper-phosphorus alloy tube is cut into a single copper-phosphorus target blank with a height of 35±1mm by high-speed sand wire cutting, and then the target blank is cut into 1 / 4 ring target blanks by water cutting. After cutting a single alloy tube, the number of target blanks is 24*4=96. Subsequently, the tube blank is processed by a CNC milling machine to obtain a 1 / 4 ring copper-phosphorus anode product. The surface of the finished anode is cleaned to remove dirt, and then placed in a vacuum oven for drying. After cooling, a vacuum bag is used to vacuum seal it to prevent anodization.

[0036] Metallographic analysis: The metallographic analysis of the samples taken from the above blanks finally revealed a grain size of 250 μm. Figure 4 .

[0037] Some exemplary embodiments of the present invention are described above. It can be understood that the above embodiments are only used to explain the present invention and do not constitute a limitation on the protection scope of the present invention. The features in these embodiments can be recombined in a suitable manner, and the scheme obtained thereby is still within the protection scope required by the present invention. Based on the above embodiments, all other embodiments obtained by those skilled in the art without making creative work, that is, all modifications, equivalent substitutions and improvements made within the spirit and principles of this application, fall within the protection scope required by the present invention.

Claims

1. A method for preparing a ring-shaped high-purity copper-phosphorus anode for integrated circuits, characterized in that: The following steps are involved: Step 1: obtaining a copper-phosphorus melt by smelting, and performing static mold casting on the copper-phosphorus melt under a vacuum state to obtain a cylindrical ingot; Step 2: performing homogenization heat treatment on the cylindrical ingot at a temperature of 600-700° C. for 6-8 hours to obtain a homogenized ingot; Step 3: performing reverse extrusion deformation on the homogenized ingot, wherein the material temperature during the extrusion deformation process is 550-700° C. and is lower than the homogenization heat treatment temperature, the extrusion speed is 6-8 mm / s, and the extrusion ratio is 1.5-4.5, to obtain a high-purity copper phosphorus tube blank; Step 4: annealing the high-purity copper phosphorus tube blank at a temperature of 200-300° C. for a time of 1-2 h; Step 5: Cut the high-purity copper-phosphorus tube billet annealed in step 4, and then machine it using a high-precision CNC machine tool to obtain a ring-shaped high-purity copper-phosphorus anode for integrated circuits, wherein the processing accuracy of the high-precision CNC machine tool is ±0.01mm.

2. The method for preparing a ring-shaped high-purity copper-phosphorus anode for integrated circuits according to claim 1, characterized in that: In step 1, vacuum induction melting or magnetic levitation melting is used to obtain a copper-phosphorus melt.

3. The method for preparing a ring-shaped high-purity copper-phosphorus anode for integrated circuits according to claim 1, characterized in that: The pouring temperature of static mold pouring in step 1 is 1100-1200° C., and the pouring time is 4-5 minutes.

4. The method for preparing a ring-shaped high-purity copper-phosphorus anode for integrated circuits according to claim 1, characterized in that: The cylindrical ingot obtained in step 1 has a purity of 99.9%-99.999%, a P content of 400-650 ppm, and a diameter of 150-200 mm.

5. The method for preparing a ring-shaped high-purity copper-phosphorus anode for integrated circuits according to claim 1, characterized in that: The furnace temperature fluctuation during the homogenization heat treatment in step 2 does not exceed ±5°C.

6. The method for preparing a ring-shaped high-purity copper-phosphorus anode for integrated circuits according to claim 1, characterized in that: The high-purity copper-phosphorus tube blank obtained in step 3 has a tube wall thickness of 10-40 mm.

7. The method for preparing a ring-shaped high-purity copper-phosphorus anode for integrated circuits according to claim 1, characterized in that: The cutting method in step 5 is high-speed abrasive wire cutting, and the cutting accuracy is 0.2mm.

8. The method for preparing a ring-shaped high-purity copper-phosphorus anode for integrated circuits according to claim 1, characterized in that: In step 5, a high-precision CNC machine tool is used to process the outer diameter, inner diameter, upper surface and lower surface of the high-purity copper phosphorus tube blank to obtain an annular finished product, wherein the inner diameter of the annular finished product is 220-270 mm, the outer diameter is 270-300 mm, the wall thickness is 10-40 mm, and the height is 30-40 mm.

9. The method for preparing a ring-shaped high-purity copper-phosphorus anode for integrated circuits according to claim 1, characterized in that: The integrated circuit obtained in step 5 is further cleaned, vacuum dried and plastic-sealed using a ring-shaped high-purity copper-phosphorus anode.

10. A ring-shaped high-purity copper-phosphorus anode for integrated circuits prepared by the preparation method according to any one of claims 1 to 9, characterized in that: Its grain size is 100-300μm.

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