JP4981293B2 - Thermal spray coating - Google Patents

Description

  The present invention relates to a thermal spray coating containing yttrium oxide (yttria) as at least a main component.

  In the field of manufacturing semiconductors and liquid crystals, microfabrication of devices is performed by dry etching using plasma. A technique is known in which a thermal spray coating is provided on a part of a semiconductor manufacturing apparatus or a liquid crystal manufacturing apparatus that may be damaged by etching during the plasma process, thereby improving the plasma etching resistance of the part (for example, Patent Document 1). By improving the plasma etching resistance in this way, particle scattering is suppressed, and as a result, the device yield is improved.

The thermal spray coating used in such applications can be formed, for example, by plasma spraying a thermal spraying powder containing yttria granulated-sintered particles. Development aimed at improving the plasma etching resistance of thermal spray coatings against various plasmas such as high-power plasma and low-power plasma has been carried out, but the thermal spray coating that satisfies the required performance has not yet been obtained. .
JP 2002-80954 A

An object of the present invention is excellent in plasma etching resistance against plasma having a plasma power applied to a thermal spray coating of a unit area of 0.8 W / cm ² or more (hereinafter referred to as high power plasma in the present specification). It is to provide a thermal spray coating.

In order to achieve the above object, the invention described in claim 1 is a thermal spray coating containing at least yttria as a main component, and a plasma power applied to the thermal spray coating of a unit area is 0.8 W / cm ² or more. when exposed to thermal spray coating to the CF ₄ plasma, the etching rate of the thermal spray coating by CF ₄ plasma formula: Re ≦ 7.7 × ^{Pp 2.2} (however, Re is the etching rate of the thermal spray coating by CF ₄ plasma [ represents nm / min], Pp is satisfied represents.) the plasma power applied to the spray coating unit area [W / cm ^2], porosity provides der Ru sprayed coating less 12%.

The invention described in 請 Motomeko 2 provides a thermal spray coating of claim 1 film thickness of 50 to 1000 [mu] m.

Invention of Claim 3 provides the thermal spray coating of Claim 1 or 2 whose size of a crystallite is 10-50 nm.
Invention of Claim 4 provides the thermal spray coating as described in any one of Claims 1-3 whose Vickers micro hardness is 300 or more.

The invention according to claim 5, claim 1-4 ratio of the wear volume of the thermal spray coating to wear volume of carbon steel SS400 when subjected to carbon steel SS400 and thermal spray coating in the same wear test is 3 or less The thermal spray coating as described in any one of these is provided.

  ADVANTAGE OF THE INVENTION According to this invention, the thermal spray coating excellent in the plasma etching resistance with respect to high power plasma is provided.

Hereinafter, an embodiment of the present invention will be described.
The etching rate of the thermal spray coating of this embodiment by CF ₄ plasma satisfies the formula: Re ≦ 7.7 × Pp ^2.2 when the plasma output applied to the thermal spray coating of the unit area is 0.8 W / cm ² or more. It is essential to do. In the above formula, Re represents the etching rate [nm / min] of the thermal spray coating by CF ₄ plasma, and Pp represents the plasma output [W / cm ² ] given to the thermal spray coating of the unit area.

  The thermal spray coating of the present embodiment is formed by thermal spraying a thermal spraying powder and contains yttria as at least a main component. The yttria content in the thermal spray coating is preferably 90% or more, more preferably 95% or more, and most preferably 99% or more. Components other than yttria in the thermal spray coating are not particularly limited, but are preferably rare earth oxides.

  The thermal spraying powder used as the material for forming the thermal spray coating may contain yttria granulated particles, may contain yttria granulated-sintered particles, or yttria melt-pulverized particles. May be contained. Yttria granulated particles are produced by granulating yttria powder. Yttria granulation-sintered particles are produced by producing a granulated powder from a raw material powder, sintering the granulated powder, and further crushing and classifying it. Yttria melt-pulverized particles are produced by melting and classifying the raw material powder after cooling and solidification. The raw powder of yttria granulation-sintered particles and yttria melt-pulverized particles may be yttria powder, or finally yttria in the process of sintering or melting like yttria-yttrium mixed powder or yttrium powder. It may be a powder of a substance that can be converted into

  When the average particle size of the thermal spraying powder is less than 20 μm, there is a risk that a relatively fine particle may be contained in the thermal spraying powder, so that the thermal spraying powder with good fluidity cannot be obtained. Therefore, in order to improve the fluidity of the thermal spraying powder, the average particle size of the thermal spraying powder is preferably 20 μm or more. As the fluidity of the thermal spraying powder decreases, the supply of the thermal spraying powder to the thermal spraying frame tends to become unstable, resulting in a non-uniform thickness of the thermal spraying coating and poor plasma etching resistance of the thermal spraying coating. It becomes easy to become uniform.

  On the other hand, when the average particle diameter of the thermal spraying powder exceeds 60 μm, the thermal spraying powder may be sufficiently softened or hardly melted by the thermal spraying frame. As a result, there is a possibility that the deposition efficiency (spraying yield) of the thermal spraying powder is lowered and uneconomical. Therefore, in order to improve the adhesion efficiency, the average particle diameter of the thermal spraying powder is preferably 60 μm or less.

  When the powder for thermal spraying contains yttria granulated-sintered particles, if the average particle size of the primary particles constituting the yttria granulated-sintered particles is less than 0.5 μm, the plasma resistance of the thermal spray coating against high-power plasma There is a possibility that the etching property is slightly lowered. This is because, as the average particle diameter of the primary particles constituting the yttria granulated-sintered particles becomes smaller, the proportion of the interlamellar region in the thermal spray coating exhibiting a lamellar structure becomes higher. The interlamellar region contains many crystal defects, and etching of the sprayed coating by plasma proceeds preferentially from the defective portion in the sprayed coating. There is a tendency to be inferior in plasma etching resistance. Therefore, from the viewpoint of improving the plasma etching resistance of the thermal spray coating against high-power plasma, it is preferable that the average particle diameter of the primary particles constituting the yttria granulated-sintered particles is 0.5 μm or more.

  On the other hand, even when the average particle diameter of primary particles constituting the yttria granulated-sintered particles exceeds 1.5 μm, the plasma etching resistance of the sprayed coating against high-power plasma may be slightly lowered. This is because as the average particle diameter of the primary particles constituting the yttria granulation-sintered particles increases, the width of the interlamellar region in the thermal spray coating increases. As described above, the interlamellar region contains a lot of crystal defects, and etching of the sprayed coating by plasma proceeds preferentially from the defective portion in the sprayed coating, so that the sprayed coating including the interlamellar region having a large width dimension. Tends to be inferior in plasma etching resistance to high-power plasma. Therefore, from the viewpoint of improving the plasma etching resistance of the thermal spray coating against high-power plasma, it is preferable that the average particle diameter of the primary particles constituting the yttria granulated-sintered particles is 1.5 μm or less.

  The method of spraying the thermal spraying powder to form a thermal spray coating may be plasma spraying or a thermal spraying method other than plasma spraying. However, the atmospheric pressure when the thermal spraying powder is plasma sprayed is preferably atmospheric pressure. In other words, the thermal spray coating is preferably formed by spraying the thermal spray powder with atmospheric pressure plasma. When the atmospheric pressure at the time of plasma spraying is not atmospheric pressure, particularly in the case of a reduced pressure atmosphere, the plasma etching resistance of the thermal spray coating against high-power plasma may be slightly lowered. This is because, when the thermal spraying powder is subjected to low pressure plasma spraying, there is a risk that yttria in the thermal spraying powder may be reduced during thermal spraying, and as a result, lattice defects due to oxygen deficiencies are likely to be included in the thermal spray coating. This is because there is a possibility of becoming. As described above, since the etching of the sprayed coating by plasma proceeds preferentially from the defective portion in the sprayed coating, the sprayed coating formed by the low pressure plasma spraying is compared with the sprayed coating formed by the atmospheric pressure plasma spraying, There is a tendency to be inferior in plasma etching resistance to high power plasma.

  When the porosity of the thermal spray coating exceeds 15%, more specifically, when it exceeds 12%, more specifically, when the porosity exceeds 10%, the plasma etching resistance of the thermal spray coating against high-power plasma may be slightly reduced. . This is because etching of the sprayed coating by plasma proceeds preferentially from around the pores in the sprayed coating. In addition, when the porosity of the sprayed coating is in the above range, there is a possibility that through-holes are included in the sprayed coating, which may not sufficiently prevent etching damage to the substrate due to plasma. . Therefore, from the viewpoint of improving the plasma etching resistance of the thermal spray coating against high power plasma and preventing through-pores, the porosity of the thermal spray coating is preferably 15% or less, more preferably 12% or less, most preferably. 10% or less.

  On the other hand, if the porosity of the thermal spray coating is less than 1%, more specifically less than 2%, more specifically less than 3%, the thermal spray coating is too dense, and the thermal spraying is caused by residual stress in the thermal spray coating. There is a possibility that the film is easily peeled off. Therefore, the porosity of the sprayed coating is preferably 1% or more, more preferably 2% or more, and most preferably 3% or more.

  When the thickness of the thermal spray coating is less than 50 μm, more specifically, when the thickness is less than 100 μm, there is a possibility that through-holes are included in the thermal spray coating, and therefore, etching damage to the substrate due to plasma should be sufficiently prevented. There is a possibility of not being able to. Therefore, in order to prevent through pores, the thickness of the thermal spray coating is preferably 50 μm or more, more preferably 100 μm or more.

  On the other hand, when the thickness of the thermal spray coating exceeds 1000 μm, more specifically, when it exceeds 800 μm, the thermal spray coating may be easily peeled off due to residual stress in the thermal spray coating. Therefore, in order to prevent peeling of the thermal spray coating, the thickness of the thermal spray coating is preferably 1000 μm or less, and more preferably 800 μm or less.

  If the crystallite size in the thermal spray coating is less than 10 nm, and more specifically less than 15 nm, the plasma etching resistance of the thermal spray coating against high-power plasma may be slightly reduced. This is because the grain boundary density in the thermal spray coating increases as the size of the crystallites in the thermal spray coating decreases. Etching of the thermal spray coating with high-power plasma proceeds preferentially from the crystal grain boundaries, so that the thermal spray coating with a high grain boundary density tends to be inferior in plasma etching resistance against high-power plasma. Therefore, from the viewpoint of improving the plasma etching resistance of the thermal spray coating against high power plasma, the size of the crystallites in the thermal spray coating is preferably 10 nm or more, and more preferably 15 nm or more.

  On the other hand, when the size of the crystallite in the thermal spray coating exceeds 50 nm, more specifically, when the crystallite size exceeds 40 nm, the plasma etching resistance of the thermal spray coating against high-power plasma may be slightly reduced. This is because the fact that the size of the crystallites in the thermal spray coating is large means that a large amount of unmelted thermal spraying powder is mixed in the thermal spray coating. Etching of the thermal spray coating by plasma proceeds preferentially from the part of the unmelted thermal spraying powder in the thermal spray coating, so that the thermal spray coating containing a large amount of the unmelted thermal spraying powder is resistant to plasma etching against high-power plasma. There is a tendency to be inferior. Therefore, from the viewpoint of improving the plasma etching resistance of the thermal spray coating against high power plasma, the size of the crystallites in the thermal spray coating is preferably 50 nm or less, more preferably 40 nm or less.

  If the Vickers microhardness of the thermal spray coating is less than 300, and more specifically less than 350, the wear resistance of the thermal spray coating may be reduced. Therefore, in order to improve the wear resistance of the sprayed coating, the Vickers microhardness of the sprayed coating is preferably 300 or more, more preferably 350 or more.

  On the other hand, if the Vickers microhardness of the thermal spray coating exceeds 600, or more specifically, exceeds 550, the impact resistance of the thermal spray coating may be reduced. Therefore, in order to improve the impact resistance of the thermal spray coating, the Vickers micro hardness of the thermal spray coating is preferably 600 or less, more preferably 550 or less.

  When the ratio of the wear volume of the thermal spray coating to the wear volume of the carbon steel SS400 exceeds 3 when the carbon steel (rolled steel for general structure) SS400 and the thermal spray coating are subjected to the same wear test, more specifically, 2.7 If it exceeds 1, more specifically, if it exceeds 2.5, the abrasion resistance of the thermal spray coating may not be practically sufficient. Therefore, in order to ensure practically sufficient wear resistance, the ratio of the wear volume of the thermal spray coating to the wear volume of the carbon steel SS400 is preferably 3 or less, more preferably 2.7 or less, most preferably Preferably it is 2.5 or less.

You may change the said embodiment as follows.
-The sprayed coating of this embodiment may be formed by spraying the spraying material which is not a powder form instead of the thermal spraying powder.

Next, the present invention will be described more specifically with reference to examples and comparative examples.
The thermal spray coatings of Examples 1 to 11 and Comparative Examples 1 and 2 were formed by plasma spraying a powder for thermal spraying consisting of yttria granulated particles, yttria granulated-sintered particles or yttria melted-ground particles. The details of each thermal spray coating and the thermal spraying powder used when forming the thermal spray coating are as shown in Table 1. Moreover, the spraying conditions (atmospheric pressure plasma spraying conditions and reduced pressure plasma spraying conditions) when forming the sprayed coating are as shown in Table 2.

In the “etching rate Re” column of Table 1, the plasma power (Pp) applied to the thermal spray coating of the unit area is 1 W / cm ² (7.7 × Pp ^2.2 = 7.7), 2 W / cm ² ( when exposed to the thermal spray coating to the CF ₄ plasma 7.7 × ^Pp 2.2 = 35.4) or ^{3W / cm 2 (7.7 × Pp} 2.2 = 86.3), by CF ₄ plasma The result of having measured the etching rate of the thermal spray coating is shown. Specifically, first, the surface of each thermal spray coating is mirror-polished using colloidal silica having an average particle size of 0.06 μm, and a part of the surface of the thermal spray coating after polishing is masked with polyimide tape, and then the thermal spray is performed. The entire surface of the coating was plasma etched under the conditions shown in Table 3. Thereafter, the level difference between the masked portion and the unmasked portion was measured using a step measuring device “Alpha Step” manufactured by KLA-Tencor.

  In the "Porosity" column of Table 1, the results of measuring the porosity of each thermal spray coating are shown. Specifically, first, each thermal spray coating was cut along a plane orthogonal to the upper surface, and the cut surface was mirror-polished using colloidal silica having an average particle diameter of 0.06 μm. Thereafter, the porosity of the sprayed coating was measured on the cut surface using an image analysis processing apparatus “NSFJ1-A” manufactured by NSupport.

  In the “film thickness” column of Table 1, the results of measuring the thickness of each sprayed coating are shown. Specifically, first, each thermal spray coating was cut along a plane orthogonal to the upper surface, and the cut surface was mirror-polished using colloidal silica having an average particle diameter of 0.06 μm. Then, the thickness of the sprayed coating was measured on the cut surface using an optical microscope.

  The “crystallite size” column in Table 1 shows the results of measuring the crystallite size in each thermal spray coating. Specifically, the crystallite size was calculated by the Hall method from the X-ray diffraction pattern of each sprayed coating measured using an X-ray diffractometer “RINT-2000” manufactured by Rigaku Corporation.

The “Vickers hardness” column in Table 1 shows the results of measuring the Vickers microhardness of each sprayed coating.
In the “Wear ratio” column of Table 1, the result of measuring the ratio of the volume of wear of the thermal spray coating by the same reciprocating plane wear test to the volume of wear of the carbon steel SS400 by the reciprocating wheel wear test. Indicates. Specifically, in the reciprocating plane wear test, the surface of the sample was rubbed 400 times with a load of 2.00 kgf (about 19.6 N) using CP240 abrasive paper defined in JIS R6252.

The “thermal spray atmosphere” column in Table 1 shows the atmospheric pressure when plasma spraying each thermal spray powder to form a thermal spray coating.
The “type of thermal spraying powder” column in Table 1 indicates whether each thermal spraying powder is composed of yttria granulated particles, yttria granulated-sintered particles, and yttria melted-pulverized particles.

  In the “average particle diameter of thermal spraying powder” column of Table 1, yttria granulated particles of each thermal spraying powder measured using a laser diffraction / scattering particle size measuring device “LA-300” manufactured by Horiba, Ltd., The average particle diameter of yttria granulation-sintered particles or yttria melt-pulverized particles is shown.

  In the column of “average particle diameter of primary particles constituting granulated particles or granulated-sintered particles” in Table 1, Examples 1 to 6 measured using a field emission scanning electron microscope (FE-SEM) The average particle diameter of the primary particle which comprises the yttria granulated particle or yttria granulated-sintered particle of each thermal spraying powder of 8-11 and Comparative Examples 1 and 2 is shown. More specifically, 10 yttria granulated particles or yttria granulated-sintered particles are arbitrarily selected from each thermal spraying powder, and 10 selected yttria granulated particles or yttria granulated-sintered particles are selected. Each of 50 primary particles is arbitrarily selected, and the average of the fixed direction diameter (Feret diameter) measured for a total of 500 primary particles for each thermal spraying powder is shown. The constant direction diameter is the distance between two imaginary lines extending in parallel across the particle.

表１に示すように、単位面積の溶射皮膜に与えられるプラズマ出力が１Ｗ／ｃｍ^２、２Ｗ／ｃｍ^２又は３Ｗ／ｃｍ^２といういずれも高出力のＣＦ_４プラズマによるエッチングレートに関して、実施例１〜１１の溶射皮膜と比較例１，２の溶射皮膜との間には有意な差が認められた。

As shown in Table 1, plasma power applied to the spray coating unit area with respect to ^{1W / cm 2, 2W / cm} 2 or etch rate by CF ₄ plasma none of 3W / cm ² high output, Example 1 A significant difference was observed between the thermal spray coating of 11 and the thermal spray coatings of Comparative Examples 1 and 2.

Claims (5)

A thermal spray coating comprising as at least mainly of yttrium oxide, when the plasma power applied to the spray coating unit area were exposed sprayed coating to 0.8 W / cm ² or more CF ₄ plasma, by CF ₄ plasma The etching rate of the thermal spray coating is the formula: Re ≦ 7.7 × Pp ^2.2 (where Re represents the etching rate [nm / min] of the thermal spray coating by CF ₄ plasma, and Pp is given to the thermal spray coating of the unit area. plasma power represents a [W / cm ^2].) satisfied,
A thermal spray coating having a porosity of 12% or less . The thermal spray coating according to claim 1, wherein the film thickness is 50 to 1000 μm. The thermal spray coating according to claim 1 or 2 , wherein the crystallite size is 10 to 50 nm. The thermal spray coating according to any one of claims 1 to 3 , wherein the Vickers micro hardness is 300 or more. Any of claims 1-4, characterized in that the ratio is 3 or less wear volume of the thermal spray coating to wear volume of carbon steel SS400 when subjected to carbon steel SS400 and thermal spray coating in the same wear test one The thermal spray coating as described in the item.