JP3026225B2 - Processing method of sputtering target - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a processing method for finishing an outer surface of a sputtering target used for sputtering film formation.

(Prior art) Conventionally, as a sputtering target, a material obtained by processing a metal such as aluminum, gold, silver, cobalt, and nickel, a rare metal, or another material into a disk shape or a rectangular plate shape is used. To process the material,
A cutting process using a lathe or a milling machine is often used, and in some cases, the cutting process is performed by a grinding process using a plurality of fixed abrasive grains such as a grindstone or a polishing process using a plurality of free abrasive grains.

In such machining, generally, in order to improve the performance of cutting or the like, it is general to pour a cooling liquid between the tool and the workpiece during machining and perform machining while cooling. The coolant is lubricated not only to obtain a cooling effect, but also to reduce friction between the tool and the workpiece or to prevent a chemical or metallic reaction between the tool and the workpiece. An agent or a surfactant is added, and when processing such as cutting is performed while pouring such a cooling liquid, the workability is improved, but the cooling liquid adheres to the workpiece. If there is any deposit on the sputtering target, the deposit is also sputtered together with the target material during sputtering film formation, and a thin film having poor film quality is formed. Has been given.

In order to prevent the cooling liquid from adhering to the sputtering target, machining such as cutting is performed without using the cooling liquid.

(Problems to be Solved by the Invention) When machining such as cutting is performed without using a cooling fluid as described above, the cooling of the tool and the target material, which is the workpiece, becomes insufficient, and the tool wears quickly. The tool and the target material chemically and metallically react with each other, and as a result, the cutting performance of the tool, for example, is reduced, and the surface of the workpiece is lumped, resulting in a problem that the surface roughness becomes rough. .

Moreover, since the machining such as the cutting performed with or without the use of the cooling liquid is generally performed in the atmosphere, the moisture (moisture) in the atmosphere is adsorbed on the surface of the workpiece, and the oxidation is performed. Substances and hydroxide films are formed. This film is removed by pre-sputtering prior to sputtering film formation. However, the conventional processing has a disadvantage that the film is relatively thick and it takes time to remove the film. In particular, a target having a rough surface has a large actual target surface area and a large amount of oxides and hydroxides.
The removal time is prolonged.

The present invention solves such inconveniences and drawbacks, enables smooth processing of the surface of the workpiece, and quickly forms an extremely thin and dense oxide film on the processed surface to thereby form the inside of the target material with the lapse of time after processing. It is an object of the present invention to propose a method of processing a sputtering target which can prevent an increase in an oxide film and a hydroxide film from growing.

(Means for Solving the Problems) In the present invention, in a method of machining the outer shape of a sputtering target by machining such as cutting and polishing, a high-purity alcohol-based solvent is used as a cooling liquid during the machining. Thereby, the above object is achieved.

It is preferable to use any of high-purity ethanol, methanol, propanol, isopropanol, butanol, and isobutanol as a cooling liquid for the alcohol-based solvent.

(Operation) For example, when a disc-shaped workpiece made of pure aluminum is finished to a flat surface with a milling machine, the processing is performed while pouring, for example, high-purity ethanol as a cooling liquid into a milling portion. The workpiece and the milling mill are provided with cooling and lubrication by the cooling liquid, and a chemical and metallic reaction between the workpiece and the milling mill is prevented, thereby completing a sputtering target having a predetermined shape. The surface of the workpiece is rapidly covered with a dense oxide film by a cooling liquid of high-purity ethanol that is bathed during the processing, and the oxide film and the hydroxide film increase inside the target material over time after the processing. Progression is prevented. Therefore, the time of pre-sputtering performed prior to sputtering film formation can be reduced, and contamination of the film formation chamber with sputtered oxides and the like is reduced.

(Example) A 10 mm-thick disk-shaped pure aluminum material used for a sputtering target as a wiring material of an LSI was turned on a lathe to which a natural diamond (nose R0.2) was attached.
Cutting depth 0.03mm, cutting speed 300mm / min (r max2000
rpm), under the cutting conditions of the feeder 0.008 mm / rev, and cutting in the dry state without using a coolant in the atmosphere to obtain a sputtering target (sample 1). Thus, a sputtering target (sample 2) was obtained by cutting.

In addition to these samples, sample 3 was prepared by changing the material to A-1% Si in a dry state under the same cutting conditions, and sample 4 was cut using ethanol under the same cutting conditions. Sample 5 was cut in a dry state under the same cutting conditions with the material changed to A-1% Si-0.1% Cu, and Sample 6 was cut using ethanol under the same cutting conditions.

The surface roughness of these samples 1 to 6 was measured with a diamond stylus type surface roughness meter, and the results are as shown in Table 1.

This shows that the surface of the sputtering target cut with ethanol as a cooling liquid is clearly smoother than that of the sputtering target cut without using a cooling liquid.

Also, a dense oxide film is rapidly formed on the surface of an aluminum material cut using a cooling solution of ethanol by bathing in the cooling solution, but when the material is A6061, the oxygen content is determined by Auger analysis. The sputtering time at which the peak of became 1/2 of the surface was 0.8 min. For comparison, the material cut with a 50% aqueous solution of ethanol had a sputter time of 2.3 min at which the oxygen peak was halved from the surface, and the material cut with lathe cutting oil had an oxygen peak at the surface. Sputtering time is 2.8 min, which is halved, and the oxide layer of the sputtering target processed with high-purity ethanol is much thinner.

When pure aluminum was cut using a cooling solution of ethanol, the thickness of the oxide film on the surface was 25.3 mm. On the other hand, when pure aluminum was cut with a cooling liquid of an alcoholic solvent other than ethanol, the thickness of the oxide film was 24.9Å in the case of methanol and 14.9 in the case of 1-propanol.
20.8 °, 20.6 ° for isopropanol, 21.0 ° for n-butanol, 19.5 ° for 2-butanol, and 17.8 ° for isobutanol. Therefore, not only ethanol but also these alcohol-based solvents can be used to process a similar sputtering target having a thin oxide film. Since the oxide film is thin, an initial preform for forming a sputter film using the sputtering target can be formed. Sputtering time can be shortened and contamination of the inside of the film forming apparatus with an oxide film can be reduced.

Various metal materials other than aluminum are used for the sputtering target, but even in this case, if the processing is performed using a cooling solution of an alcohol-based solvent, the sputtering target has a smooth surface and a thin oxide film and a thin hydroxide film. Can be manufactured.

(Effect of the Invention) As described above, according to the present invention, since a cooling liquid of a high-purity alcoholic solvent is used for processing the shape of the sputtering target, a sputtering target with a smooth surface and a thin oxide film and a thin hydroxide film is used. There is an effect that it can be manufactured.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C23C 14/00-14/58 B23Q 11/10 B24B 55/02

Claims (2)

(57) [Claims] 1. A method of processing an outer shape of a sputtering target by machining such as cutting and polishing, wherein a high-purity alcohol-based solvent is used as a cooling liquid during the processing. Processing method. 2. The processing of a sputtering target according to claim 1, wherein a high-purity ethanol, methanol, propanol, isopropanol, butanol or isobutanol is used as a cooling liquid for the alcohol-based solvent. Method.