JP2009188018A - Cleaning method for film forming equipment parts - Google Patents

Abstract

[Problem] To remove deposits adhering to and deposited on the surface of a film forming apparatus part used in a film forming process of Ta, Ti, Ta-N, and Ti-N in a short time without damaging the substrate as much as possible. A cleaning method is provided.
Ta, Ti, Ta-N, Ti-N are obtained by roughening the surface of a film forming apparatus component made of aluminum, stainless steel, alumina ceramics, or the like to an arithmetic average roughness Ra of 5 microns or more. This is a method of removing the deposited film by controlling the shape of the deposited film to be granular, and then cleaning with a cleaning solution comprising sulfuric acid and hydrofluoric acid. As a roughened part surface, aluminum or titanium is used on the part surface. It is preferable to roughen the surface by providing a thermal sprayed film.
[Selection figure] None

Description

  The present invention relates to a method for cleaning a film forming apparatus part used for manufacturing a semiconductor or the like, and deposits of tantalum (Ta), titanium (Ti), tantalum nitride (Ta-N), and titanium nitride (Ti-N). The present invention provides a technique for quickly removing a deposited film from a film forming apparatus component to which the film has adhered without damaging the substrate.

  In a film forming apparatus used for manufacturing semiconductors and the like, a necessary film is formed on a device substrate such as a wafer, and is also formed on film forming apparatus parts such as a shield, a shutter, and a ceramic ring used inside the film forming apparatus. Film material adheres and accumulates. Then, as the number of device substrates processed increases, the deposited film becomes thicker, and eventually the deposited film is peeled off to generate particles. Therefore, in the film forming process, production is periodically stopped, the film forming apparatus parts are taken out, and cleaning is performed to remove the deposited film.

  Until now, nitric acid-hydrofluoric acid has been mainly used in the cleaning process of film forming apparatus parts on which Ta, Ti, Ta—N, and Ti—N are deposited. In particular, when Ta or Ta—N becomes a deposited film, it takes time to remove and the substrate is damaged. Therefore, a method has been proposed in which the nitric acid concentration is 60% or higher and the concentration is increased by 8 times or more compared to the hydrofluoric acid concentration (see, for example, Patent Document 1). Although this method reduces the damage to the substrate, it takes a long time to remove the deposited film. In the manufacture of devices, sulfuric acid-hydrogen peroxide (for example, see Patent Document 2) and sulfuric acid-hydrofluoric acid (for example, see Patent Document 3) are used as etching solutions for Ti and Ta thin films. Since the etching rate is low, it is difficult to remove a thick film.

US Pat. No. 6,902,627 JP 2000-58861 A JP-A-5-323340

  An object of the present invention is to provide a cleaning method for removing a deposited film in a short time without damaging a base material as much as possible from film forming apparatus parts used in a film forming process of Ta, Ti, Ta-N, and Ti-N. It is to provide.

  As a result of intensive studies in view of the above-described present situation, the present inventor has formed a surface of a film forming apparatus component having a roughened surface from the group consisting of tantalum, titanium, tantalum nitride, and titanium nitride. By immersing a film forming device part to which a film deposited with at least one selected deposit is attached in a cleaning liquid composed of sulfuric acid and hydrofluoric acid, sulfuric acid and hydrofluoric acid act strongly on the boundary of the particles, and the substrate It has been found that the deposited film can be removed in a short time without damaging as much as possible, and the present invention has been completed.

  The present invention is described in detail below.

  The cleaning method of the present invention is applied to a film forming apparatus part in which a film on which at least one selected from the group consisting of tantalum, titanium, tantalum nitride and titanium nitride is deposited adheres to the roughened surface of the film forming apparatus part. On the other hand, the deposited film is removed using a cleaning liquid composed of sulfuric acid and hydrofluoric acid. The present invention removes the deposited film of Ta, Ti, Ta—N or Ti—N adhering to the surface of the component, but the structure of the deposited film depends on the surface roughness of the film forming apparatus component. When the surface of the film forming apparatus component is roughened, the deposited film grows in a granular form.

  The cleaning liquid of the present invention acts strongly on the grain boundaries, and peels off the deposited film adhering to the film forming apparatus parts in powder and / or foil form, so that the deposited film components can be more effectively removed without dissolving all of the deposited film. It can be removed in a short time.

  The arithmetic average roughness Ra (specified in JIS B0601 (2001)) of the roughened surface of the film forming apparatus component is preferably 5 μm or more. Examples of the method for roughening the surface of the component include a method of grinding the surface of the base material constituting the component with a blasting process or rough abrasive grains, or a method of forming a sprayed film on the surface of the base material. However, the surface is preferably roughened by a sprayed film of aluminum or titanium. This is because sprayed films of these materials have a high effect of promoting granulation of the structure of the deposited film and withstand the residual stress of the deposited film.

  For example, an aluminum alloy, stainless steel, alumina ceramic, or the like can be suitably used as the substrate of the film forming apparatus component used in the present invention.

  When the base material of the film forming apparatus component is an aluminum alloy, the composition of the cleaning liquid is preferably 50 to 80% by weight of sulfuric acid, 1 to 20% by weight of hydrofluoric acid, and the balance is water. More preferably, the sulfuric acid concentration is 65 to 75% by weight and the concentration of hydrofluoric acid is 2 to 15% by weight. If the concentration of sulfuric acid is less than 50% by weight, the solubility of the aluminum alloy increases and wear may increase. In addition, preparation with a sulfuric acid concentration exceeding 80% by weight may be difficult. On the other hand, if the concentration of hydrofluoric acid is less than 1% by weight, the solubility of the deposited film is lowered and it takes a long time for cleaning. If the concentration of hydrofluoric acid exceeds 20% by weight, a cleaning solution is prepared. It can be difficult.

  When the base material of the film forming apparatus component is stainless steel, the composition of the cleaning liquid is preferably 10 to 70% by weight of sulfuric acid, 1 to 20% by weight of hydrofluoric acid, and the balance is water. More preferably, the sulfuric acid concentration is 15 to 40% by weight and the hydrofluoric acid concentration is 2 to 15% by weight. If the concentration of sulfuric acid is less than 10% by weight or the concentration of sulfuric acid exceeds 70% by weight, the solubility of the deposited film may be lowered and the cleaning time may be increased. Further, if the concentration of hydrofluoric acid is less than 1% by weight, the solubility of the deposited film may be lowered and the cleaning time may be prolonged. If the concentration of hydrofluoric acid exceeds 20% by weight, The solubility of the material may increase and wear due to dissolution may increase.

  In the case of a stainless steel substrate, removing the deposited film using a cleaning solution composed of sulfuric acid and hydrofluoric acid may cause the carbon contained in the stainless steel to remain on the stainless steel surface, resulting in blackening. It is preferable to perform cleaning with a cleaning liquid composed of nitric acid and hydrofluoric acid after cleaning with a cleaning liquid composed of hydrofluoric acid.

  When the substrate of the film forming apparatus component is alumina ceramic, the composition of the cleaning liquid is preferably 15 to 55% by weight of sulfuric acid, 1 to 20% by weight of hydrofluoric acid, and the balance is water. More preferably, the sulfuric acid concentration is 15 to 40% by weight, and the hydrofluoric acid concentration is 2 to 15% by weight. If the concentration of sulfuric acid is less than 15% by weight, the solubility of the deposited film may be reduced, and cleaning may take time. If the concentration of sulfuric acid exceeds 55% by weight, the grain boundary of alumina ceramic is corroded and damaged. May increase. Further, if the concentration of hydrofluoric acid is less than 1% by weight, the solubility of the deposited film may be reduced, and cleaning may take time. If the concentration of hydrofluoric acid exceeds 20% by weight, alumina ceramics may be used. There is a risk that the grain boundaries of the steel corrode and damage increases.

  The cleaning liquid temperature and the cleaning time at the time of cleaning vary depending on the kind and deposit amount of deposits present on the surface of the film forming apparatus parts. For example, the cleaning temperature is 10 to 40 ° C., and the cleaning time is 1 to 10 hours. However, those skilled in the art can easily determine this by conducting preliminary experiments as appropriate.

  The cleaning method of the present invention can reduce the damage and wear of the surface of the semiconductor manufacturing component compared to the conventional cleaning method, and can remove the deposited film in a short time.

  The present invention will be described in more detail based on examples, but the present invention is not limited to only these examples.

Example 1
A blasting material of GA # 100 was used for roughening the aluminum alloy substrate film forming apparatus parts, and the arithmetic average roughness was set to 8 μm. This film forming apparatus component was used in a film forming process by Ta / TaN PVD (Physical Vapor Deposition). The thickness of the deposited Ta / TaN film after use was 800 μm. The film forming apparatus parts after use are finely cut, and each cut piece is immersed in a cleaning solution (20 ° C.) mixed at a ratio of sulfuric acid and hydrofluoric acid as shown in Table 1, so that the deposited film can be removed and the substrate. The wear of was investigated.

  With the cleaning solution of 30 wt% sulfuric acid-4 wt% hydrofluoric acid, the deposited film could be removed in 90 minutes in the shortest time. Further, in order to investigate the wear of the aluminum alloy base material, a cut piece of the same part as the film forming apparatus part was immersed in the same solution, and the change in the base material thickness before and after the immersion was examined. The amount of change was 170 μm / h. there were. However, in the cleaning solution of 65% by weight sulfuric acid-15% by weight hydrofluoric acid, the deposited film could be removed by immersion for 5 hours. Similarly, when the wear was examined using a cut piece, no change in thickness was observed.

  Therefore, in the aluminum alloy base material, when priority is given to the wear of the base material rather than giving priority to the removal time of the Ta / TaN film, the cleaning solution of 65% by weight sulfuric acid-15% by weight hydrofluoric acid is better. There is little wear and the number of times the film forming apparatus parts are regenerated by cleaning can be increased.

比較例１
実施例1と同様にアルミニウム合金基材の成膜装置部品にＴａ／ＴａＮ膜を堆積させ、硝酸１０重量％とフッ化水素酸５重量％に調整した洗浄液に３０分浸漬した。実体顕微鏡及び目視で観察したところ、堆積膜は部分的に残存した。また、実施例１と同様に切断片を用いて損耗を調べたところ、４００μｍ厚みが減少していた。

Comparative Example 1
In the same manner as in Example 1, a Ta / TaN film was deposited on an aluminum alloy base film forming apparatus component, and immersed in a cleaning solution adjusted to 10 wt% nitric acid and 5 wt% hydrofluoric acid for 30 minutes. When observed with a stereomicroscope and visual observation, the deposited film partially remained. Moreover, when wear was investigated using the cut piece similarly to Example 1, 400 micrometers thickness was reducing.

Example 2
The surface of a stainless steel film forming apparatus component was coated with a Ti sprayed film to obtain a roughened surface having an arithmetic average roughness of 7 μm. This film forming apparatus component was used in a film forming process using Ti / TiN PVD. The thickness of the deposited Ti / TiN film after use was 600 μm. Similarly to Example 1, the film forming apparatus parts after use are finely cut, and each cut piece is immersed in a cleaning solution mixed at a ratio of sulfuric acid and hydrofluoric acid shown in Table 2 so that the deposited film can be removed. And the wear of the substrate was examined.

  With a cleaning solution of 30 wt% sulfuric acid-4 wt% hydrofluoric acid, the deposited film could be removed in 20 minutes, which was the shortest time. Further, in order to investigate the wear of the stainless steel base material, a cut piece of the same part as the film forming apparatus part was immersed in the same liquid, and when the change in the base material thickness before and after the immersion was examined, the amount of change was 2 μm (6 μm / h). )Met.

実施例３
アルミナセラミック基材の成膜装置部品にアルミニウム溶射膜を被覆し、算術平均粗さを１５μｍの粗面化した表面とした。この成膜装置部品をＴａとＴａＮのＰＶＤによる成膜工程で使用した。使用後のＴａ／ＴａＮの堆積膜の厚みは６００μｍであった。実施例１と同様に、使用後の成膜装置部品を細かく切断し、それぞれの切断片を表３に示す硫酸とフッ化水素酸の割合で混合した洗浄液に浸漬し、堆積膜が除去できる時間と基材のダメージを調べた。

Example 3
A film-forming part of an alumina ceramic substrate was coated with an aluminum sprayed film to obtain a roughened surface having an arithmetic average roughness of 15 μm. This film forming apparatus component was used in a film forming process using Ta and TaN PVD. The thickness of the deposited Ta / TaN film after use was 600 μm. Similarly to Example 1, the film forming apparatus parts after use are finely cut, and each cut piece is immersed in a cleaning solution mixed at a ratio of sulfuric acid and hydrofluoric acid shown in Table 3, so that the deposited film can be removed. And the substrate was examined for damage.

  30% by weight of sulfuric acid-4% by weight of hydrofluoric acid was the shortest time in which the deposited film could be removed in 20 minutes. Further, when the alumina ceramic substrate was immersed in the same cleaning solution for 6 hours and examined for damage, it was found to corrode 110 μm.

Claims (7)

A film forming apparatus component having a roughened surface and a film having at least one selected from the group consisting of tantalum, titanium, tantalum nitride and titanium nitride adhered to the surface of the film forming apparatus component. A method for cleaning a film forming apparatus component, wherein the deposited film is removed using a cleaning liquid comprising hydrofluoric acid and hydrofluoric acid. 2. The method of cleaning a film forming apparatus component according to claim 1, wherein the arithmetic average roughness Ra of the surface of the film forming apparatus component is 5 microns or more. 3. The method for cleaning a film forming apparatus component according to claim 1, wherein the roughened surface of the film forming apparatus component is a sprayed film of aluminum or titanium. The substrate of the film forming apparatus component is made of an aluminum alloy, and the composition of the cleaning liquid is 50 to 80% by weight of sulfuric acid, 1 to 20% by weight of hydrofluoric acid, and the balance is water. A method for cleaning a film forming apparatus component according to any one of claims 1 to 3. The base material of the film forming apparatus component is made of stainless steel, and the composition of the cleaning liquid is 10 to 70% by weight of sulfuric acid, 1 to 20% by weight of hydrofluoric acid, and the balance is water. The method for cleaning a film forming apparatus component according to claim 1. 6. The film forming apparatus according to claim 5, wherein after the deposited film is removed using a cleaning liquid composed of sulfuric acid and hydrofluoric acid, further cleaning is performed using a cleaning liquid composed of nitric acid and hydrofluoric acid. How to clean parts. The substrate of the film forming apparatus component is made of alumina, the composition of the cleaning liquid is 15 to 55% by weight of sulfuric acid, 1 to 20% by weight of hydrofluoric acid, and the balance is water. The method for cleaning a film forming apparatus component according to claim 1.