阅读说明：本技术 一种提高靶材镀膜均匀性的方法 (Method for improving coating uniformity of target material ) 是由 姚力军 潘杰 边逸军 王学泽 龚润泽 于 2020-05-11 设计创作，主要内容包括：本发明涉及一种提高靶材镀膜均匀性的方法,所述方法包括：将焊接完成的靶材依次进行整平、车削及抛光处理。本发明中,通过靶材加工工艺的改进达到去除表面应力层的目的,改善靶材在溅射初期过程中存在的镀膜均匀性不良问题,同时也提高了其在集成电路制造中阻挡Cu互连线的Cu原子扩散到其他介质层的能力,提高器件的性能和寿命；表面应力层会影响靶材的整体溅射寿命；此外,一旦表面应力层太厚,需要消耗更多的能耗利用Ar离子去轰击靶材表面将其去除,造成了材料的浪费。(The invention relates to a method for improving the coating uniformity of a target, which comprises the following steps: and (4) sequentially carrying out leveling, turning and polishing treatment on the welded target. According to the invention, the purpose of removing the surface stress layer is achieved through the improvement of the target processing technology, the problem of poor coating uniformity of the target in the initial sputtering process is solved, the capability of preventing Cu atoms of a Cu interconnection line from diffusing to other dielectric layers in the integrated circuit manufacturing process is improved, the performance of a device is improved, and the service life of the device is prolonged; the surface stress layer can affect the overall sputtering life of the target; in addition, once the surface stress layer is too thick, more energy consumption is required to bombard the surface of the target with Ar ions to remove the stress layer, which results in material waste.)

1. A method for improving the coating uniformity of a target material is characterized by comprising the following steps: and (4) sequentially carrying out leveling, turning and polishing treatment on the welded target.

2. The method of claim 1, wherein the flatness of the target after the flattening is < 0.1 mm.

3. The method of claim 1 or 2, wherein the turning comprises a first turning and a second turning performed in sequence.

4. The method of claim 3, wherein the first turning is completed with a margin of 0.5 to 0.8 mm;

preferably, the feed amount of the first turning is 0.5 mm;

preferably, the cutting speed of the first turning is 600-700 m/min.

5. The method according to claim 3 or 4, characterized in that the second cut is performed 10 times;

preferably, the feed per turning is 0.05-0.08 mm.

6. The method as claimed in any one of claims 3-5, characterized in that the cutting speed of the second turning is 350-400 m/min.

7. The method of any of claims 1-6, wherein the polishing comprises a sequence of sandpaper polishing and scouring pad polishing.

8. The method of claim 7, wherein the scouring pad in the scouring pad finishing is 800# scouring pad.

9. The method according to any of claims 1 to 8, wherein the surface roughness Ra of the target after completion of the polishing is < 0.5 μm.

10. The method of any one of claims 1-9, wherein the method comprises: carrying out leveling, turning and polishing treatment on the welded target material in sequence;

wherein, the flatness of the target material after the leveling is finished is less than 0.1 mm; the turning comprises a first turning and a second turning which are sequentially carried out; the allowance after the first turning is finished is 0.5-0.8 mm; the feed rate of the first turning is 0.5 mm; the cutting speed of the first turning is 600-700 m/min; the second turning is performed 10 times; the feed amount of each turning is 0.05-0.08 mm; the cutting speed of the second turning is 350-400 m/min; the polishing comprises sand paper polishing and scouring pad polishing which are sequentially carried out; the scouring pad in the scouring pad polishing process is 800# scouring pad; and the surface roughness Ra of the polished target material is less than 0.5 mu m.

Technical Field

The invention relates to the field of targets, in particular to a method for improving coating uniformity of a target.

Background

Currently, a target for semiconductor sputtering is used for chip production with high integration and fine structure. Uniformity of coating thickness for chip production becomes an important consideration. With the development of integrated circuits, Cu interconnect technology is gradually replacing aluminum interconnects. Cu has the defects of easy oxidation and easy diffusion, and is easy to diffuse into a medium to influence the performance of a transistor. Ta/TaN bilayer films in the interconnection film system of integrated circuits are widely used as diffusion barrier layers and adhesion layers between Cu and media in the industry due to the excellent chemical property and thermal stability. Too thin a film layer on the silicon wafer will reduce the blocking effect of the blocking layer. If the film layer is plated too thick, the resistivity of the film layer is increased, and the electrical performance of the chip is affected. For example, CN110414131A discloses a method for selecting an intermediate layer of a diffusion welding assembly of a Co target backing plate with a sandwich structure, belonging to the field of Co sputtering target manufacturing. By establishing a stress mathematical model of the diffusion welding assembly of the Co target backboard with the sandwich structure, the relation between the stress in the target, the middle layer and the backboard and the thermal expansion coefficients of the target, the backboard and the middle layer is solved. Therefore, theoretical guidance is provided for selecting the diffusion welding interlayer of the Co target backboard with the sandwich structure, the welding residual stress of the diffusion welding assembly of the Co target backboard is reduced, and the reliability of the diffusion welding assembly is improved. CN109807452A discloses an end welding method of a high-purity aluminum rotating target, which comprises the steps of welding an end welding port or a tail cover welding port in three steps, wherein the first step is spot welding, the second step is arc welding, and the third step is circumferential welding. The method can prevent the high-purity aluminum rotary target material from deforming, the coaxiality of the aluminum alloy end and the high-purity rotary target material is high, the generation of internal stress is effectively reduced, the welding effect of the interface of the aluminum alloy end and the high-purity rotary target material is good, and the air tightness of the welding interface is good.

In the existing target processing technology, because a residual stress layer exists on the surface, and the target deforms in the welding process, the residual stress layer exists in the machining process. Therefore, the tantalum target has a high yield of poor coating uniformity during sputtering, which reduces the yield of chip manufacture, and even a new target must be replaced due to the severe non-uniformity of the coating thickness in the later stage of the target.

Disclosure of Invention

In view of the problems in the prior art, the present invention aims to provide a method for improving the coating uniformity of a target, which removes a residual stress layer generated on the surface of the target, improves the problem of poor coating uniformity of a film layer on a silicon wafer in a sputtering process, and improves the yield of chip manufacturing.

In order to achieve the purpose, the invention adopts the following technical scheme:

the invention provides a method for improving coating uniformity of a target, which comprises the following steps: and (4) sequentially carrying out leveling, turning and polishing treatment on the welded target.

According to the invention, the purpose of removing the surface stress layer is achieved through the improvement of the target processing technology (including the increase of leveling and polishing procedures and the adjustment of cutting conditions in mechanical processing), the problem of poor coating uniformity of the target in the initial sputtering process is solved, the capability of preventing Cu atoms of a Cu interconnection line from diffusing to other dielectric layers in the integrated circuit manufacturing process is improved, and the electrical property and the service life of a device are improved; the surface stress layer can affect the overall sputtering life of the target, and once the surface stress layer is too thick, more energy consumption is consumed to bombard the surface of the target by using Ar ions to remove the target, so that the material waste is caused.

In a preferred embodiment of the present invention, the flatness of the target after the completion of leveling is less than 0.1mm, and may be, for example, 0.09mm, 0.08mm, 0.07mm, 0.06mm, 0.05mm, 0.04mm, 0.03mm, 0.02mm, or 0.01mm, but is not limited to the above-mentioned values, and other values not mentioned in the above-mentioned range are also applicable.

As a preferred technical solution of the present invention, the turning includes a first turning and a second turning performed in sequence.

In a preferred embodiment of the present invention, the remaining length after completion of the first turning is 0.5 to 0.8mm, for example, 0.5mm, 0.55mm, 0.6mm, 0.65mm, 0.7mm, 0.75mm, or 0.8mm, but is not limited to the above-mentioned values, and other values not listed in the above range are also applicable.

Preferably, the feed amount of the first turning is 0.5 mm.

Preferably, the cutting speed of the first turning is 600-700m/min, such as 600m/min, 605m/min, 610m/min, 615m/min, 620m/min, 625m/min, 630m/min, 635m/min, 640m/min, 645m/min, 650m/min, 655m/min, 660m/min, 665m/min, 670m/min, 675m/min, 680m/min, 685m/min, 690m/min or 700m/min, but is not limited to the values listed, and other values not listed in this range are equally applicable.

As a preferred embodiment of the present invention, the second cut is performed 10 times.

Preferably, the amount of cutting feed per turning is 0.05-0.08mm, for example 0.05mm, 0.055mm, 0.06mm, 0.065mm, 0.07mm, 0.075mm or 0.08mm, but not limited to the values listed, other values not listed in this range being equally applicable.

In the invention, the cutting feed of the second turning needs to be selected according to the allowance after the first turning is finished, so that the allowance after the first turning is finished after 10 times of the second turning can be completely removed.

In a preferred embodiment of the present invention, the cutting speed of the second turning is 350-400m/min, for example, 350m/min, 355m/min, 360m/min, 365m/min, 370m/min, 375m/min, 380m/min, 385m/min, 390m/min, 395m/min, or 400m/min, but is not limited to the above-mentioned values, and other values not listed in this range are also applicable.

In a metal material, plastic deformation occurs in the vicinity of a portion in contact with a tool during cutting, and a considerable residual stress layer exists in the machined surface due to thermal influence caused by contact between the material and the tool during the plastic deformation. The magnitude and distribution of the residual stress can be different due to different cutting conditions and the material to be cut, and the invention adjusts the cutting conditions: and in the first turning, because the turning amount is large, a large stress layer exists on the machined surface. And the subsequent second cutting has small turning amount, so that the surface stress left after machining is small and only has a thin layer, and finally, the final surface stress layer is removed by adopting a polishing process.

The machining process provided by the invention adjusts the cutting conditions, the feed amount is adjusted to be small each time, the turning is divided into multiple times, and the corresponding cutting speed is low, so that the effect of removing the stress layer is well achieved.

As a preferable technical scheme of the invention, the polishing comprises sand paper polishing and scouring pad polishing which are sequentially carried out.

As a preferable technical scheme of the invention, the scouring pad in the scouring pad polishing is 800# scouring pad.

As a preferable embodiment of the present invention, the surface roughness Ra of the target after polishing is less than 0.5. mu.m, and may be, for example, 0.4. mu.m, 0.38. mu.m, 0.36. mu.m, 0.34. mu.m, 0.32. mu.m, 0.30. mu.m, 0.28. mu.m, 0.26. mu.m, 0.24. mu.m, 0.22. mu.m, 0.2. mu.m, 0.18. mu.m, 0.16. mu.m, 0.14. mu.m, 0.12. mu.m, or 0.1. mu.m, but not limited thereto, and other values not specified in the range are also applicable.

As a preferred technical solution of the present invention, the method comprises: carrying out leveling, turning and polishing treatment on the welded target material in sequence;

wherein, the flatness of the target material after the leveling is finished is less than 0.1 mm; the turning comprises a first turning and a second turning which are sequentially carried out; the allowance after the first turning is finished is 0.5 mm; the feed rate of the first turning is 0.5 mm; the cutting speed of the first turning is 600-700 m/min; the second turning is performed 10 times; the feed amount of each turning is 0.05 mm; the cutting speed of the second turning is 350-400 m/min; the polishing comprises sand paper polishing and scouring pad polishing which are sequentially carried out; the scouring pad in the scouring pad polishing process is 800# scouring pad; and the surface roughness Ra of the polished target material is less than 0.5 mu m.

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

according to the invention, the purpose of removing the surface stress layer is achieved through the improvement of the target processing technology (including the increase of leveling and polishing processes and the adjustment of cutting conditions in mechanical processing), the problem of poor coating uniformity of the target in the initial sputtering process is solved, the capability of the target in blocking Cu atoms of a Cu interconnection line from diffusing to other dielectric layers in the integrated circuit manufacturing process is improved, the performance and the service life of a device are improved, the thickness uniformity of a film is obviously improved, and the thickness uniformity of the film can be +/-0.5 nm at most.

Drawings

FIG. 1 is a photograph showing the target after finishing the processing in example 1 of the present invention

FIG. 2 is a photograph of a target after finishing processing in example 5 of the present invention;

FIG. 3 is a photograph showing the uniformity of the coating film formed on the surface of the target after the target has been processed in example 5;

FIG. 4 is a photograph of a target of comparative example 5 of the present invention after finishing processing;

FIG. 5 is a photograph showing the uniformity of the surface coating film after the target of comparative example 5 according to the present invention has been processed.

The present invention is described in further detail below. The following examples are merely illustrative of the present invention and do not represent or limit the scope of the claims, which are defined by the claims.

Detailed Description

To better illustrate the invention and to facilitate the understanding of the technical solutions thereof, typical but non-limiting examples of the invention are as follows: