Copper focusing ring for target sputtering as well as preparation method and application of copper focusing ring

Abstract

The invention provides a copper focusing ring for target sputtering as well as a preparation method and application of the copper focusing ring. The preparation method of the copper focusing ring for target sputtering comprises the following steps that a copper bar is rolled into a ring shape through a rolling machine, and then first welding is conducted at an annular connector; carrying out turning processing on the copper ring after the first welding, and then carrying out first polishing processing; performing hole milling on the outer surface of the copper ring subjected to the first polishing treatment, and performing second welding on a hole obtained by hole milling and a hole connecting piece; and carrying out second polishing treatment on the copper ring after the second welding to obtain the copper focusing ring for target sputtering. According to the preparation method provided by the invention, the roughness and the bonding force of the surface of the copper focusing ring are regulated and controlled through polishing treatment after welding each time, so that in the subsequent copper target sputtering process, the uniformity of a coating film on a wafer is improved, copper materials are prevented from being accumulated and falling off, and the wafer cannot be damaged by crashing.

Description

Technical Field

[0001] The invention belongs to the technical field of semiconductor target sputtering and relates to a copper focusing ring for target sputtering and a preparation method and application thereof. Background Art

[0002] In the process of semiconductor chip manufacturing, physical vapor deposition (PVD) sputtering is an indispensable process. Its principle is to use the glow discharge effect to bombard the target material with charged particles, so that the atoms or molecules on the target surface gain a certain amount of kinetic energy, so that they escape from the surface and deposit on the substrate. Since the direction of the charged particles bombarding the target is uncertain, the directionality of the target atoms escaping from the target surface is uncertain, that is, the target atoms will leave the target surface from all angles.

[0003] In the actual sputtering process, high-energy particles bombard the target surface from all directions, and the target atoms escaping from the target surface will be deposited on the substrate in a straight line from all directions, so the uniformity of the film deposited on the substrate cannot be guaranteed. To solve this problem, a focusing ring is usually placed between the target and the substrate to change the magnetic field so that the target is sputtered onto the substrate in a concentrated manner, and the rough surface of the focusing ring is used to absorb impurity particles to achieve the purpose of filling deep holes at a vertical angle and improve the sputtering quality.

[0004] For example, CN103692151A provides a method for manufacturing a titanium focusing ring, including: hot forging, cold rolling, and a first heat treatment, a rolling and a second heat treatment step. Among them, after the titanium focusing ring blank is subjected to hot forging and cold rolling, in the subsequent two heat treatment steps, it is only necessary to place the titanium focusing ring blank in an ordinary heat treatment furnace (non-vacuum treatment furnace), and perform two heat treatments successively under specific conditions, and after the heat treatment process, cooperate with a specific cooling process and a mechanical processing process, so as to obtain a titanium focusing ring with fine micro grains and uniform structure. CN104561912A discloses a method for manufacturing a titanium focusing ring, including: providing a high-purity titanium ingot; processing the high-purity titanium ingot to form a titanium bar; flattening the titanium bar; cutting the titanium bar to form a titanium plate strip; heat treating the titanium bar or the titanium plate strip; processing the titanium plate strip to form a titanium focusing ring. The above-mentioned focusing rings are all titanium focusing rings, and the titanium focusing rings need to be provided with surface patterns during the preparation process, which will increase the preparation process.

[0005] The high-purity copper target sputtering process uses a copper ring to participate in the sputtering. The copper ring focuses the coil during use, forms a magnetic field, affects the flight trajectory of atoms, and finally deposits the required thin film on the substrate surface. The copper ring does not need to be patterned during use.

[0006] Therefore, how to obtain a copper focusing ring that can improve the uniformity of film coating on a wafer after sputtering of a Cu target is a technical problem that needs to be solved urgently. Summary of the invention

[0007] The purpose of the present invention is to provide a copper focusing ring for target sputtering and a preparation method and application thereof. The preparation method provided by the present invention adjusts the surface roughness and adhesion of the copper focusing ring through polishing treatment after each welding, thereby improving the uniformity of the coating on the wafer in the subsequent copper target sputtering process, and preventing the accumulation and falling of copper materials, so as not to damage the wafer.

[0008] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0009] In a first aspect, the present invention provides a method for preparing a copper focusing ring for target sputtering, the method for preparing a copper focusing ring for target sputtering comprising the following steps:

[0010] The copper strip is rolled into a ring shape by a rolling machine, and then the first welding is performed at the ring interface;

[0011] The copper ring after the first welding is subjected to a turning process, and then subjected to a first polishing process;

[0012] Milling a hole on the outer surface of the copper ring after the first polishing treatment, and performing a second welding on the hole obtained by the milling and the hole connector;

[0013] The copper ring after the second welding is subjected to a second polishing treatment to obtain the copper focusing ring for target sputtering.

[0014] The hole connector in the present invention should fit the hole obtained by milling, and the height should be consistent with the hole depth; and the number of holes obtained by milling in the present invention can be adaptively adjusted according to the length of the copper focusing ring, for example, it can be an odd number, such as 5 or 7.

[0015] The preparation method provided by the present invention adjusts the roughness and adhesion of the copper focusing ring surface through polishing treatment after each welding, so that in the subsequent copper target sputtering process, a magnetic field is formed by the focusing coil formed by the copper focusing ring so that the atoms splashed during the copper target sputtering process are uniformly attached to the wafer, thereby improving the uniformity of the coating on the wafer. Due to the high temperature, the surface of the copper ring has strong adhesion and the copper ring has the ability to attach excess atoms to the surface of the ring, and copper material will not accumulate and fall to damage the wafer.

[0016] In the present invention, if polishing is not performed after each welding, the product will cause rust. As a preferred technical solution of the present invention, the preparation of the copper strip includes:

[0017] The copper ingot is forged and rolled to obtain the copper bar.

[0018] The copper ingot provided by the present invention is a high-purity copper ingot. The purity of the high-purity copper ingot is based on the copper content requirement in the copper focusing ring (for example, the copper content in the provided high-purity copper ingot is not less than 99.99%), and its forging and rolling processes are all conventional technical means, which may specifically include hot forging the copper ingot, water cooling, cold rolling to a predetermined thickness, and processing it into a prefabricated copper bar.

[0019] As a preferred technical solution of the present invention, the roughness of the surface of the copper ring after the first polishing treatment is ≤0.8 mm, for example, 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm or 0.8 mm.

[0020] In the present invention, if the roughness of the surface of the copper ring is too high after the first polishing treatment, it is not conducive to the appearance of the product.

[0021] As a preferred technical solution of the present invention, the hole obtained by milling is a non-through hole.

[0022] As a preferred technical solution of the present invention, the hole depth obtained by milling is 1.2 to 1.5 mm, for example, 1.2 mm, 1.25 mm, 1.3 mm, 1.35 mm, 1.4 mm, 1.45 mm or 1.5 mm, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0023] In the present invention, if the hole depth obtained after milling is too shallow, it is not conducive to welding with the connecting piece, and if it is too deep, it will cause breakdown during the welding process.

[0024] As a preferred technical solution of the present invention, before the second welding, the copper ring and the hole connector after the first polishing treatment are cleaned independently.

[0025] Preferably, the second welding method comprises electron beam welding.

[0026] As a preferred technical solution of the present invention, the surface roughness of the copper ring after the second polishing treatment is ≤0.8mm, for example, 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm or 0.8mm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0027] As a preferred technical solution of the present invention, the second polishing process includes sequentially performing sanding polishing and scouring pad polishing.

[0028] As a preferred technical solution of the present invention, the scouring pad includes a 1200# scouring pad.

[0029] As a preferred technical solution of the present invention, after the second polishing treatment, a cleaning treatment is performed again.

[0030] As a preferred technical solution of the present invention, the thickness of the copper focusing ring for target sputtering is 2.95-3.43 mm, for example, 2.95 mm, 3 mm, 3.05 mm, 3.1 mm, 3.15 mm, 3.2 mm, 3.25 mm, 3.3 mm, 3.35 mm, 3.4 mm or 3.43 mm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0031] The thickness of the copper focusing ring finally prepared by the present invention does not need to be too thick, as too thick will affect the installation. The thickness of the copper focusing ring can be further adjusted by adjusting the depth of the hole obtained after milling, so that it can better adapt to the client station.

[0032] As a preferred technical solution of the present invention, the preparation method comprises the following steps:

[0033] The copper ingot is forged and rolled to obtain a copper bar, the copper bar is rolled into a ring shape by a rolling machine, and then a first welding is performed at the ring interface;

[0034] The copper ring after the first welding is subjected to a turning process, and then subjected to a first polishing process, wherein the surface roughness of the copper ring after the first polishing process is ≤0.8 mm;

[0035] Milling a hole on the outer surface of the copper ring after the first polishing treatment, and performing a second welding with the hole connector by electron beam welding of the non-through hole with a hole depth of 1.2 to 1.5 mm obtained by the milling;

[0036] The copper ring after the second welding is subjected to a second polishing treatment, the second polishing treatment comprising sanding polishing and scouring pad polishing in sequence, the surface roughness of the copper ring after the second polishing treatment is ≤0.8 mm, and it is cleaned again to obtain a copper focusing ring for target sputtering with a thickness of 2.95 to 3.43 mm.

[0037] In a second aspect, the present invention provides a copper focusing ring for target sputtering, wherein the copper focusing ring for target sputtering is prepared by the method for preparing a copper focusing ring for target sputtering as described in the first aspect.

[0038] In a third aspect, the present invention further provides an application of the copper focusing ring for target sputtering as described in the second aspect, wherein the application includes using the copper focusing ring for target sputtering in combination with a target material to perform target sputtering.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] The preparation method provided by the present invention adjusts the roughness and adhesion of the copper focusing ring surface through polishing treatment after each welding, so that in the subsequent copper target sputtering process, a magnetic field is formed by the focusing coil formed by the copper focusing ring so that the atoms splashed during the copper target sputtering process are uniformly attached to the wafer, thereby improving the uniformity of the coating on the wafer. Due to the high temperature, the surface of the copper ring has strong adhesion and the copper ring has the ability to attach excess atoms to the surface of the ring, and copper material will not accumulate and fall to damage the wafer. DETAILED DESCRIPTION

[0041] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0042] Example 1

[0043] This embodiment provides a method for preparing a copper focusing ring for target sputtering, the preparation method comprising the following steps:

[0044] (1) hot forging a high-purity copper ingot (the copper content of the high-purity copper ingot is not less than 99.99%), water cooling the ingot, and cold rolling the ingot to a predetermined thickness to form a prefabricated copper bar;

[0045] The copper strip is rolled into a ring shape by a rolling machine, and then the first welding is performed at the ring interface (forming a closed loop structure);

[0046] (2) The copper ring after the first welding is turned by a special fixture (the inner circle, outer circle and end face of the copper ring), and then the surface of the copper ring is polished (sand polished). The roughness of the surface of the copper ring after the first polishing is 0.8 mm;

[0047] (3) The copper ring after the first polishing treatment is cut off by a CNC machining center, and a hole is milled on the outer surface of the ring to obtain a non-through hole with a depth of 1.5 mm. The ring and the hole connector (Cu knob) are degreased and cleaned, and then a second welding is performed by electron beam welding (the height of the hole connector is equal to the hole depth, and the diameter of the hole connector corresponds to the hole diameter);

[0048] (4) The copper ring after the second welding is subjected to a second polishing treatment, the second polishing treatment comprising sanding polishing and scouring pad polishing in sequence, the surface roughness of the copper ring after the second polishing treatment is 0.8 mm, and the copper ring is cleaned again to obtain a copper focusing ring for target sputtering with a thickness of 3.43 mm.

[0049] Example 2

[0050] This embodiment provides a method for preparing a copper focusing ring for target sputtering, the preparation method comprising the following steps:

[0051] (1) hot forging a high-purity copper ingot (the copper content of the high-purity copper ingot is not less than 99.99%), water cooling the ingot, and cold rolling the ingot to a predetermined thickness to form a prefabricated copper bar;

[0052] The copper strip is rolled into a ring shape by a rolling machine, and then the first welding is performed at the ring interface (forming a closed loop structure);

[0053] (2) The copper ring after the first welding is turned by a special fixture (the inner circle, outer circle and end face of the copper ring), and then the surface of the copper ring is polished (sand polished). The roughness of the surface of the copper ring after the first polishing is 0.5 mm;

[0054] (2) The copper ring after the first polishing treatment is cut off by a CNC machining center, and a hole is milled on the outer surface of the ring to obtain a non-through hole with a depth of 1.2 mm. The ring and the hole connector (Cu knob) are degreased and cleaned, and then a second welding is performed by electron beam welding (the height of the hole connector is equal to the hole depth, and the diameter of the hole connector corresponds to the hole diameter);

[0055] (3) The copper ring after the second welding is subjected to a second polishing treatment, which includes sanding polishing and scouring pad polishing in sequence. The surface roughness of the copper ring after the second polishing treatment is 0.5 mm. The copper ring is cleaned again to obtain a copper focusing ring for target sputtering with a thickness of 2.95 mm.

[0056] Example 3

[0057] This embodiment provides a method for preparing a copper focusing ring for target sputtering, the preparation method comprising the following steps:

[0058] (1) hot forging a high-purity copper ingot (the copper content of the high-purity copper ingot is not less than 99.99%), water cooling the ingot, and cold rolling the ingot to a predetermined thickness to form a prefabricated copper bar;

[0059] The copper strip is rolled into a ring shape by a rolling machine, and then the first welding is performed at the ring interface (forming a closed loop structure);

[0060] (2) The copper ring after the first welding is turned by a special fixture (the inner circle, outer circle and end face of the copper ring), and then the surface of the copper ring is polished (sand polished). The roughness of the surface of the copper ring after the first polishing is 0.6 mm;

[0061] (2) The copper ring after the first polishing treatment is cut off by a CNC machining center, and a hole is milled on the outer surface of the ring to obtain a non-through hole with a depth of 1.27 mm. The ring and the hole connector (Cu knob) are degreased and cleaned, and then a second welding is performed by electron beam welding (the height of the hole connector is equal to the hole depth, and the diameter of the hole connector corresponds to the hole diameter);

[0062] (3) The copper ring after the second welding is subjected to a second polishing treatment, which includes sanding polishing and scouring pad polishing in sequence. The surface roughness of the copper ring after the second polishing treatment is 0.6 mm. The copper ring is cleaned again to obtain a copper focusing ring for target sputtering with a thickness of 3.18 mm.

[0063] Example 4

[0064] The difference between this embodiment and embodiment 1 is that the roughness of the surface of the copper ring after the second polishing treatment in step (4) of this embodiment is 1 mm.

[0065] The rest of the preparation process and parameters were the same as those in Example 1.

[0066] Example 5

[0067] The difference between this embodiment and embodiment 1 is that the hole depth obtained after milling in step (3) of this embodiment is 2 mm.

[0068] The rest of the preparation process and parameters were the same as those in Example 1.

[0069] Example 6

[0070] The difference between this embodiment and embodiment 1 is that the thickness of the copper focusing ring finally obtained in step (4) of this embodiment is 4 mm.

[0071] The rest of the preparation process and parameters were the same as those in Example 1.

[0072] Comparative Example 1

[0073] The difference between this comparative example and Example 1 is that this comparative example does not perform the first polishing treatment in step (2) and does not perform the second polishing treatment in step (4).

[0074] The rest of the preparation process and parameters were the same as those in Example 1.

[0075] Comparative Example 2

[0076] The difference between this comparative example and Example 1 is that this comparative example does not perform the second polishing treatment in step (4).

[0077] The rest of the preparation process and parameters were the same as those in Example 1.

[0078] In summary, the preparation method provided by the present invention regulates the roughness and adhesion of the copper focusing ring surface through polishing treatment after each welding, so that in the subsequent copper target sputtering process, the focusing coil formed by the copper focusing ring forms a magnetic field so that the atoms splashed during the copper target sputtering process are evenly attached to the wafer, thereby improving the uniformity of the coating on the wafer. Due to the high temperature, the surface of the copper ring has strong adhesion and the copper ring has the ability to attach excess atoms to the surface of the ring, and copper material will not accumulate and fall and damage the wafer.

[0079] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing a copper focusing ring for target sputtering, characterized in that: The method for preparing the copper focusing ring for target sputtering comprises the following steps: The copper strip is rolled into a ring shape by a rolling machine, and then the first welding is performed at the ring interface; The copper ring after the first welding is subjected to a turning process, and then subjected to a first polishing process; Milling a hole on the outer surface of the copper ring after the first polishing treatment, and performing a second welding on the hole obtained by the milling and the hole connector; The copper ring after the second welding is subjected to a second polishing treatment to obtain the copper focusing ring for target sputtering.

2. The method for preparing a copper focusing ring for target sputtering according to claim 1, characterized in that: The preparation of the copper strip comprises: The copper ingot is forged and rolled to obtain the copper bar.

3. The method for preparing a copper focusing ring for target sputtering according to claim 1 or 2, characterized in that: The surface roughness of the copper ring after the first polishing treatment is ≤0.8 mm.

4. The method for preparing a copper focusing ring for target sputtering according to any one of claims 1 to 3, characterized in that: The hole obtained by the milling is a non-through hole; Preferably, the hole depth obtained by milling is 1.2-1.5 mm.

5. The method for preparing a copper focusing ring for target sputtering according to any one of claims 1 to 4, characterized in that: Before the second welding, the copper ring and the hole connector after the first polishing treatment are cleaned independently; Preferably, the second welding method comprises electron beam welding.

6. The method for preparing a copper focusing ring for target sputtering according to any one of claims 1 to 5, characterized in that: The surface roughness of the copper ring after the second polishing treatment is ≤0.8 mm; Preferably, the second polishing process comprises sequentially performing sanding polishing and scouring pad polishing; Preferably, the scouring pad comprises a 1200# scouring pad; Preferably, after the second polishing process, a cleaning process is performed again.

7. The method for preparing a copper focusing ring for target sputtering according to any one of claims 1 to 6, characterized in that: The thickness of the copper focusing ring for target sputtering is 2.95-3.43 mm.

8. The method for preparing a copper focusing ring for target sputtering according to any one of claims 1 to 7, characterized in that: The preparation method comprises the following steps: The copper ingot is forged and rolled to obtain a copper bar, the copper bar is rolled into a ring shape by a rolling machine, and then a first welding is performed at the ring interface; The copper ring after the first welding is subjected to a turning process, and then subjected to a first polishing process, wherein the surface roughness of the copper ring after the first polishing process is ≤0.8 mm; Milling a hole on the outer surface of the copper ring after the first polishing treatment, and performing a second welding with the hole connector by electron beam welding of the non-through hole with a hole depth of 1.2 to 1.5 mm obtained by the milling; The copper ring after the second welding is subjected to a second polishing treatment, the second polishing treatment comprising sanding polishing and scouring pad polishing in sequence, the surface roughness of the copper ring after the second polishing treatment is ≤0.8 mm, and it is cleaned again to obtain a copper focusing ring for target sputtering with a thickness of 2.95 to 3.43 mm.

9. A copper focusing ring for target sputtering, characterized in that: The copper focusing ring for target sputtering is prepared by the method for preparing the copper focusing ring for target sputtering as described in any one of claims 1 to 8.

10. An application of the copper focusing ring for target sputtering as claimed in claim 9, characterized in that: The application includes using a copper focusing ring for target sputtering in combination with a target material to perform target sputtering.