阅读说明：本技术 一种超高纯Cu或超高纯Cu合金靶材的电解抛光工艺 (Electrolytic polishing process of ultra-pure Cu or ultra-pure Cu alloy target ) 是由 姚力军 边逸军 潘杰 王学泽 王少平 于 2020-07-16 设计创作，主要内容包括：本发明公开了一种超高纯Cu或超高纯Cu合金靶材的电解抛光工艺。本发明的超高纯Cu或超高纯Cu合金靶材的电解抛光工艺,包括如下步骤：1)对超高纯Cu或超高纯Cu合金靶材待分析面进行研磨；2)对经步骤1)研磨后的待分析面采用电解抛光液进行电解抛光。本发明的超高纯Cu或超高纯Cu合金靶材的电解抛光工艺,适用于芯片用超高纯Cu及Cu合金靶材的晶粒尺寸、晶向、织构等晶体学分析,特别适用于细晶、超细晶超高纯Cu或超高纯Cu合金靶材,用于指导超高纯Cu或超高纯Cu合金靶材的工艺开发。(The invention discloses an electrolytic polishing process of an ultra-pure Cu or ultra-pure Cu alloy target. The electrolytic polishing process of the ultra-pure Cu or the ultra-pure Cu alloy target material comprises the following steps: 1) grinding the surface to be analyzed of the ultra-pure Cu or the ultra-pure Cu alloy target; 2) and (2) performing electrolytic polishing on the surface to be analyzed ground in the step 1) by using an electrolytic polishing solution. The electrolytic polishing process of the ultra-pure Cu or the ultra-pure Cu alloy target is suitable for crystallography analysis of grain size, crystal orientation, texture and the like of the ultra-pure Cu and Cu alloy target for chips, is particularly suitable for fine-grain and ultra-fine-grain ultra-pure Cu or ultra-pure Cu alloy target, and is used for guiding the process development of the ultra-pure Cu or the ultra-pure Cu alloy target.)

1. An electrolytic polishing process of an ultra-pure Cu or ultra-pure Cu alloy target material is characterized by comprising the following steps:

1) grinding the surface to be analyzed of the ultra-pure Cu or the ultra-pure Cu alloy target;

2) carrying out electrolytic polishing on the surface to be analyzed ground in the step 1) by using electrolytic polishing liquid; wherein the electrolytic polishing solution is a mixture of phosphoric acid, ethanol, propanol, water and urea.

2. The electrolytic polishing process according to claim 1, wherein in step 1), the purity of the ultra-high purity Cu or the ultra-high purity Cu alloy is 99.9999% or more;

preferably, the ultra-high purity Cu alloy is an ultra-high purity CuAl alloy or an ultra-high purity CuMn alloy;

preferably, the grain size of the ultra-pure Cu or the ultra-pure Cu alloy target material is 1-20 μm.

3. The electrolytic polishing process according to claim 1 or 2, wherein in step 1), the grinding is mechanical grinding.

4. The electropolishing process of claim 3, wherein the mechanical grinding is performed using 1000# silicon carbide sandpaper.

5. The electrolytic polishing process according to any one of claims 1 to 4, wherein in the step 2), the volume ratio of phosphoric acid, ethanol, propanol, water and urea in the electrolytic polishing solution is (5-10): 1 (3-5): 0.2.

6. The electrolytic polishing process according to any one of claims 1 to 5, wherein the voltage for electrolytic polishing in step 2) is 20 to 30V.

7. The electrolytic polishing process according to any one of claims 1 to 6, wherein the electrolytic polishing time in step 2) is 10 to 30 seconds.

8. The electrolytic polishing process according to any one of claims 1 to 7, wherein in step 2), the electrolytic polishing solution for electrolytic polishing is introduced to the surface to be analyzed through a catheter.

9. The electropolishing process of claim 8, wherein the flow rate of electropolishing solution in the fluid conduit is 10-30 cc/s.

10. The electropolishing process of any of claims 1-9, wherein the electropolishing process comprises the steps of:

1) mechanically grinding the surface to be analyzed of the ultra-pure Cu or the ultra-pure Cu alloy target by using No. 1000 silicon carbide abrasive paper;

2) carrying out electrolytic polishing on the surface to be analyzed ground in the step 1) by using electrolytic polishing liquid, wherein the electrolytic polishing liquid is introduced to the surface to be analyzed through a liquid guide pipe, and the electrolytic polishing liquid is a mixture of phosphoric acid, ethanol, propanol, water and urea in a volume ratio of 5:3:1:5: 0.2; the voltage of the electrolytic polishing is 20-30V, the time of the electrolytic polishing is 10-30s, and the flow rate of the electrolytic polishing liquid in the catheter is 10-30 cc/s.

Technical Field

The invention belongs to the field of metal target material electrolytic polishing, and particularly relates to an electrolytic polishing process of an ultra-pure Cu or ultra-pure Cu alloy target material.

Background

Electron back scattering diffraction (EBSD for short) is mainly characterized by performing diffraction with spatial resolution on the order of submicron while maintaining the conventional characteristics of a scanning electron microscope. In crystallography, EBSD utilizes backscattered electrons to diffract in a lattice to form a diffraction chrysanthemum-like cell pattern which is used for determining crystallographic information such as grain size, crystal plane orientation, texture and the like.

The chip uses Cu and CuAl/CuMn alloy as seed layers, and is deposited in a pre-etched groove in a physical vapor deposition mode, and pure Cu or CuP is deposited as an interconnection line in a subsequent electroplating mode. The thickness of the seed layer is only several nm magnitude, and the requirements on the uniformity of the plated film and the coverage uniformity of the groove are extremely high. Crystallographic factors such as the grain size, the orientation, the texture and the like of the sputtering target can influence the uniformity of film formation and the coverage rate of the groove. Generally, the more concentrated the grain size distribution, the better the uniformity of the coating film; moreover, the smaller the grain size is, the more random the atom sputtering direction distribution is, and the better the coverage rate of the groove is; meanwhile, the utilization rate of the target material is higher, and the service life is prolonged. The combination energy of atoms on different crystal planes and crystal directions is different, the sputtering rate is also different, and the sputtering rate of the densely arranged planes and the densely arranged directions is the highest. The uniformity of the sputtering rate is directly affected by the specific crystal orientation and texture, so that the film forming uniformity and the groove coverage are affected. In the production of a target material, it is generally desired to obtain a texture form in which a specific crystal plane is dominant. Particularly, as the technology node is further developed to 7nm/5nm, the requirements of the process technology on the grain size, the crystal orientation distribution, the texture and the like of the target are further improved.

EBSD is used as a tool for accurately analyzing the crystallographic information of metal materials, and is gradually applied to the crystallographic analysis of ultra-pure metal targets, such as Cu, CuAl and CuMn alloys, so as to guide the improvement of the target manufacturing process and meet the requirements of higher technical nodes. However, the EBSD sample preparation technology limits the further development of the method in the field of high-purity sputtering target materials. For example, the grain size of the high-purity Cu or Cu alloy target can be thinned to 10 μm or even below 1 μm, and the defect ratio of grain boundary, dislocation and the like is too high. High density defects are in a high energy, unstable state and are very susceptible to corrosion. In the conventional electrolytic polishing process, high-density defects are preferentially corroded, so that the electrochemical corrosion of the surface to be analyzed is uneven, the noise ratio is too high, the analysis of the chrysanthemum pool zone and the subsequent analysis of the crystal orientation and the texture are influenced, and the application potential of the EBSD technology is limited.

CN102443840A discloses a metallographic structure electrolyte, a corrosion method of cobalt or cobalt alloy and a display method of the metallographic structure thereof, wherein the display method of the metallographic structure of cobalt or cobalt alloy comprises the following steps: providing a cobalt or cobalt alloy target material; polishing the cobalt or cobalt alloy target; mechanically polishing the ground cobalt or cobalt alloy target; and (3) performing electrolytic polishing on the cobalt or cobalt alloy target after mechanical polishing in metallographic structure electrolyte, wherein the metallographic structure electrolyte is a mixed solution of ethanol, n-butyl alcohol, water, nitric acid and hydrofluoric acid. The metallographic structure electrolyte prepared from ethanol, n-butyl alcohol, water, nitric acid and hydrofluoric acid has a good corrosion effect on cobalt or cobalt alloy, the crystal boundary display effect of the metallographic structure of the cobalt or cobalt alloy is improved, the potential safety hazard of the metallographic structure electrolyte is reduced, and meanwhile, raw materials are not limited by national safety control. However, the electrolytic polishing process of the invention is not suitable for the crystallographic analysis of the ultra-pure Cu or the ultra-pure Cu alloy target.

Disclosure of Invention

Aiming at the defects of the prior art, the invention aims to provide an electrolytic polishing process of an ultra-pure Cu or an ultra-pure Cu alloy target, which is suitable for crystallographic analysis of grain size, crystal orientation, texture and the like of the ultra-pure Cu and Cu alloy target for a chip, is particularly suitable for fine-grained, ultra-fine-grained ultra-pure Cu or ultra-pure Cu alloy target and is used for guiding the process development of the ultra-pure Cu or ultra-pure Cu alloy target.

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

an electrolytic polishing process of an ultra-pure Cu or ultra-pure Cu alloy target material, which comprises the following steps:

1) grinding the surface to be analyzed of the ultra-pure Cu or the ultra-pure Cu alloy target;

2) carrying out electrolytic polishing on the surface to be analyzed ground in the step 1) by using electrolytic polishing liquid; wherein the electrolytic polishing solution is a mixture of phosphoric acid, ethanol, propanol, water and urea.

An electropolishing process for ultra-pure Cu or ultra-pure Cu alloy target material is characterized by grinding to primarily remove a stress layer of a surface to be analyzed, further removing a surface stress layer through the electropolishing process, determining crystallographic information such as grain size, crystal face orientation, texture and the like for EBSD analysis of fine-grained, ultra-fine-grained Cu and Cu alloy target materials, guiding the optimization of the production process of the target material, and meeting the requirements of advanced technical nodes.

In the step 1), the purity of the ultra-pure Cu or the ultra-pure Cu alloy is 99.9999% or more. It should be noted that the purity of the ultra-pure Cu alloy is 99.9999% or more, which means that the total content of other impurity elements except for alloying elements does not exceed 0.0001%, for example, the ultra-pure copper-aluminum alloy means that the total content of other impurity elements except for copper-aluminum does not exceed 0.0001%.

Preferably, the grain size of the ultra-high pure Cu or the ultra-high pure Cu alloy target is 1 to 20 μm, for example, the grain size of the ultra-high pure Cu or the ultra-high pure Cu alloy target is 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, or 20 μm, etc.

Preferably, the ultra-high purity Cu alloy is an ultra-high purity CuAl alloy or an ultra-high purity CuMn alloy.

In the step 1), the grinding is mechanical grinding. Preferably, the ultra-pure Cu or ultra-pure Cu alloy target is placed on a rotating grinding disc for grinding.

The mechanical grinding adopts 1000# silicon carbide sand paper.

In the step 2), the volume ratio of phosphoric acid, ethanol, propanol, water and urea in the electrolytic polishing solution is (5-10): 3-5):1: (5-10):0.2, preferably 5:3:1:5: 0.2.

In step 2), the voltage of the electrolytic polishing is 20-30V, for example, the voltage of the electrolytic polishing is 20V, 21V, 22V, 23V, 24V, 25V, 26V, 27V, 28V, 29V or 30V, etc.

In step 2), the time of the electropolishing is 10-30s, for example, the time of the electropolishing is 10s, 11s, 12s, 13s, 14s, 15s, 16s, 17s, 18s, 19s, 20s, 21s, 22s, 23s, 24s, 25s, 26s, 27s, 28s, 29s or 30s, and the like.

In the step 2), the electrolytic polishing solution for electrolytic polishing is introduced to the surface to be analyzed through a liquid guide pipe.

The flow rate of the electropolishing solution in the catheter is 10-30cc/s, such as 10cc/s, 11cc/s, 12cc/s, 13cc/s, 14cc/s, 1cc/5s, 16cc/s, 17cc/s, 18cc/s, 19cc/s, 20cc/s, 21cc/s, 22cc/s, 23cc/s, 24cc/s, 25cc/s, 26cc/s, 27cc/s, 28cc/s, 29cc/s or 30 cc/s.

As a preferred scheme of the invention, the electrolytic polishing process of the ultra-pure Cu or the ultra-pure Cu alloy target comprises the following steps:

1) mechanically grinding the surface to be analyzed of the ultra-pure Cu or the ultra-pure Cu alloy target by using No. 1000 silicon carbide abrasive paper;

2) carrying out electrolytic polishing on the surface to be analyzed ground in the step 1) by using electrolytic polishing liquid, wherein the electrolytic polishing liquid is introduced to the surface to be analyzed through a liquid guide pipe, and the electrolytic polishing liquid is a mixture of phosphoric acid, ethanol, propanol, water and urea in a volume ratio of 5:3:1:5: 0.2; the voltage of the electrolytic polishing is 25V, the time of the electrolytic polishing is 20s, and the flow rate of the electrolytic polishing solution in the catheter is 20 cc/s.

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

the electrolytic polishing process of the ultra-high pure Cu or the ultra-high pure Cu alloy target material is suitable for crystallography analysis of the grain size, the crystal orientation, the texture and the like of the ultra-high Cu and Cu alloy target material for the chip, is particularly suitable for fine-grain and ultra-fine-grain ultra-high pure Cu or ultra-high pure Cu alloy target material, and is used for guiding the process development of the ultra-high pure Cu or the ultra-high pure Cu alloy target material.

Drawings

Fig. 1 is an EBSD chrysanthemum cell band analysis diagram of an analyzed surface of an ultra-high-purity Cu target after electropolishing in example 1 of the present invention;

fig. 2 is an EBSD chrysanthemum cell band analysis diagram of the surface to be analyzed of the ultra-high-purity Cu target after the electropolishing treatment in example 2 of the present invention;

FIG. 3 is an EBSD chrysanthemum pool zone analysis diagram of the to-be-analyzed surface of the ultra-pure Cu target after the comparative example electrolytic polishing treatment of the invention.

Detailed Description

The technical solution of the present invention is further explained by the following embodiments.

Unless otherwise specified, various starting materials of the present invention are commercially available or prepared according to conventional methods in the art.