JP2018048378A - Silicon spray deposit and production method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a minute silicon spray deposit having few pores, a small pore size, and a uniform distribution of pores, in comparison with a conventional plasma spray deposit; and to provide a production method thereof.SOLUTION: In a silicon spray deposit, a half value width of a diffraction peak at a diffraction angle 2θ=28.4±0.5° is 0.23-1.0° in an X-ray diffraction spectrum. A production method of the silicon spray deposit includes a step for thermally spraying slurry containing silicon particles having a volume-based median size (D50) of 1-10 μm by a high velocity flame spray process (HVOF).SELECTED DRAWING: None

Description

  The present invention relates to a silicon sprayed film useful as a thin film of a member used in a semiconductor manufacturing apparatus and a method for manufacturing the same.

  As means for applying a thin film to each member used in a semiconductor manufacturing apparatus, for example, plasma spraying or high-speed flame spraying (HVOF spraying) is known. Plasma spraying is mainly employed as a means for depositing a ceramic film such as alumina or yttria on the surface of a metal or ceramic sintered base material. HVOF spraying is employed as a coating means for high temperature members and as a coating means for sliding members.

In the coating on the members of the semiconductor manufacturing apparatus as described above, the silicon coating is mainly applied to the members for the plasma processing apparatus. Silicon itself reacts with a fluorine-based gas such as CF ₄ to generate low boiling point SiF ₄ , but is vaporized and exhausted out of the system. Therefore, it is said that there is an effect of suppressing contamination to the device due to generation of particulate matter. Conventionally, silicon coating is mainly performed by plasma spraying, and an example in which HVOF spraying is employed is not known. HVOF thermal spraying is mainly applied to thermal spraying of members containing metal groups (see Patent Documents 1 and 2 and Non-Patent Documents 1 and 2).

Patent Document 1 discloses a technique for forming a nickel-based alloy metal coating by HVOF thermal spraying. Patent Document 2 discloses an amorphous-phase metallic glass bulk material as a coating and a method for producing the same. A good halo pattern peculiar to the amorphous phase is recognized by HVOF thermal spraying of Fe ₄₃ Cr ₁₆ Mo ₁₆ C ₁₅ B ₁₀ gas atomized powder known as metallic glass and X-ray diffraction of the thermal spray coating. In Non-Patent Document 1, HVOF spraying has a low flame temperature and a high spray particle velocity for the purpose of application of a corrosion-resistant amorphous coating of Fe-10 mass% Cr-8 mass% P-2 mass% C alloy. It is suggested that a completely amorphous sprayed coating may be obtained by using an alloy that is low in temperature and easily amorphized by rapid solidification. However, there is no mention of amorphization of a semiconductor that is difficult to be amorphized. Non-Patent Document 2 discloses HVOF spraying of WC-Co cermet, and it is generally considered difficult to form a brittle material such as ceramics by HVOF spraying or HVAF spraying.

  The above conventional HVOF techniques are all related to HVOF thermal spraying on a member containing a metal group, there is no example of film formation of a brittle material made of a covalent bond crystal such as silicon, and the crystallinity of the HVOF thermal sprayed film. There is no example of technical disclosure. That is, conventionally, it is not recalled that HVOF spraying is employed in the silicon coating, and other means, for example, plasma spraying as described above is employed.

Japanese Patent No. 3612568 Japanese Patent No. 3946226

Fumitaka Otsubo, 2 others, “Hydrochloric acid resistance of high-speed flame sprayed Fe-Cr-Mo-8P-2C alloy amorphous sprayed coating”, Journal of the Japan Welding Society, 2001, Vol. 19, No. 1, p. 54-59 Seiji Kuroda, “New Trend of High-Speed Flame (HVOF) Thermal Spray”, 2006, Journal of the Japan Welding Society, Vol. 75, No. 8, p.627-631

However, in plasma spraying, the volume of the melt is large and the temperature gradually decreases even after the substrate is deposited, so the crystallinity is relatively good, and the surface of the deposit during cooling is surface active (
(Surface energy) does not increase. For this reason, reaction (bonding and sintering) with the adhering material around the adjacent material hardly occurs, and pores are easily generated between the adjacent materials. At the same time, since the volume of the melt is large in plasma spraying, a large space is taken in when it adheres to the substrate, which tends to become large pores after cooling. Summarizing the above plasma spraying, when silicon is sprayed by plasma spraying, the crystallinity of the film is high, resulting in a decrease in sinterability (reactivity) during film formation, which hinders sintering with adjacent particles. There was a tendency for pores to be inherent and to have a high porosity. In order to form a dense silicon film for a semiconductor process, a thermal spray process in which the surface activity (surface energy) is increased so as to increase the sinterability at the time of film formation is required. Further, there is a demand for a sprayed film of a brittle material made of a covalent bond crystal such as silicon, which is a structure having a small porosity and a small pore diameter, as a member for a semiconductor device.

  The present invention has been made in view of the above-described conventional problems, and its purpose is denser, fewer pores, smaller average pore diameter, and smaller pores than conventional plasma sprayed silicon sprayed films. An object is to provide a silicon sprayed film having a uniform distribution and a method for manufacturing the same.

  The silicon sprayed film of the present invention is characterized in that, in an X-ray diffraction spectrum, the half-value width of a diffraction peak at a diffraction angle 2θ = 28.4 ± 0.5 ° is 0.23 to 1.0 °. In the silicon sprayed film of the present invention, the half width is wider than that of the silicon sprayed film formed by plasma spraying. Therefore, the silicon sprayed film of the present invention is smaller in crystallinity than the silicon sprayed film formed by plasma spraying, and the reason is a sprayed film that is dense, has few pores, and has a small pore diameter, as will be described later. Specifically, the silicon sprayed film of the present invention is preferably a silicon sprayed film having a porosity of 2% or less and an average pore diameter of 1 μm or less. Such a sprayed film is used in a semiconductor manufacturing apparatus. It is useful as a thin film for members.

The silicon sprayed film manufacturing method of the present invention has a volume-based median diameter (D50) of 1 to 10 μm.
The method includes spraying a slurry containing m silicon particles by high-speed flame spraying (HVOF). In the method for producing a silicon sprayed film according to the present invention, silicon is sprayed by HVOF spraying, but HVOF spraying has the following characteristics as compared with plasma spraying. That is, (1) since the volume of the silicon particle melt can be reduced, the sinterability (reactivity) of the particles adhering to the substrate is increased. (2) When the melt of silicon particles adheres to the substrate, it is cooled rapidly, so that the crystallinity of the deposited silicon is lower than that of the starting material. As a result, the interfacial activity (surface energy) of the adhered particles is increased, the sinterability is improved, the pores are few, and the pore size is small. (3) Since silicon is covalently bonded by sp ³ hybrid orbitals, a large amount of energy is required to break the covalent bond. However, in HVOF thermal spraying, heat can be efficiently given by the amount of oxygen and fuel.
Accordingly, it is possible to manufacture a silicon sprayed film that is denser, has fewer pores, has a smaller pore diameter, and has a uniform pore distribution compared to a silicon sprayed film by plasma spraying.

FIG. 1A is an X-ray diffraction spectrum of a silicon sprayed film by plasma spraying and a silicon sprayed film by HVOF spraying, and FIG. 1B is an enlarged view of a diffraction peak near 28.4 ± 0.5 °. The SEM photograph which shows the cross section of the silicon sprayed film (2A) of Example 4, and the silicon sprayed film (2B) of the comparative example 3. FIG. The SEM photograph which shows the surface of the silicon sprayed film (3A) of Example 4, and the silicon sprayed film (3B) of the comparative example 3. FIG.

<Silicon sprayed film>
The silicon sprayed film of the present invention is characterized in that, in an X-ray diffraction spectrum, the half-value width of a diffraction peak at a diffraction angle 2θ = 28.4 ± 0.5 ° is 0.23 to 1.0 °. Further, when the diffraction peak at the diffraction angle is expressed not by a half-value width but by a width of a diffraction angle 2θ corresponding to an intensity value of 1/10 of the diffraction peak (hereinafter referred to as “1/10 intensity value width”), 6 to 2.0 °. The silicon sprayed film of the present invention can be formed by HVOF spraying, and is characterized by the half width as described above. FIG. 1 shows X-ray diffraction spectra of a silicon sprayed film by plasma spraying and a silicon sprayed film by HVOF spraying. As shown in FIG. 1, the silicon sprayed film by HVOF spraying is more preferable than the silicon sprayed film by plasma spraying. However, the half-value width and the 1/10 intensity value width of the diffraction peak at the diffraction angle 2θ = 28.4 ± 0.5 ° are wide. That is, the silicon sprayed film formed by HVOF spraying has lower crystallinity than the silicon sprayed film formed by plasma spraying. This is presumably because, as described above, according to HVOF thermal spraying, when the melt of silicon particles adheres to the base material, it is rapidly cooled, so that the crystallinity of the deposited silicon is lower than that of the starting material. Since the silicon sprayed film according to the present invention is a silicon sprayed film formed by HVOF spraying, silicon is denser, has fewer pores, has a smaller pore diameter, and has a more uniform distribution of pores than a silicon sprayed film formed by plasma spraying. It is a sprayed film.

The silicon sprayed film of the present invention can have a porosity of 2% or less and an average pore diameter of 1 μm or less, and can be a film suitable as a thin film of a member of a semiconductor manufacturing apparatus. Further, the surface roughness Ra of the silicon sprayed film of the present invention can be 1 to 3 μm.
Here, the porosity, the average pore diameter, and the pore distribution are numerical values obtained by measurement by SEM observation of the cross section.
Moreover, as thickness of the silicon sprayed film of this invention, it can be set as 50-2000 micrometers.

<Method for producing silicon sprayed film>
The method for producing a silicon spray film of the present invention includes a step of spraying a slurry containing silicon particles having a volume-based median diameter (D50) of 1 to 10 μm by a high-speed flame spraying method (HVOF).

In the method for producing a silicon sprayed film of the present invention, since the volume of the sprayed particles (melt) is smaller than that in the case of plasma spraying, the volume is reduced when the melt adheres to the substrate and is cooled. Is small, the temperature of the melt rapidly decreases, and the melt partially becomes amorphous. Therefore, the surface energy of the deposit during cooling becomes high. This is because the chemically reacting bond is partially broken by amorphization. And it reacts with the adjoining surroundings (bond,
Sintering) easily occurs, reaction and sintering proceed with adjacent substances, and pores are less likely to be generated.

Further, in HVOF spraying, the volume of particles (melt) is small, so it is difficult to tackle space when the melt adheres. Therefore, the pore diameter becomes small.
On the other hand, in plasma spraying, since the volume of the sprayed particles (melt) is large, the space is taken in when it adheres to the substrate, but the size varies greatly and the positions where pores exist after cooling are likely to vary. . In contrast, in HVOF spraying, the volume of sprayed particles (melt) is small, so it is difficult to work on the space when the melt adheres, and the variation in the positions where the pores are present is relatively more than in the case of plasma spraying. Get smaller.

  As described above, in the method for producing a silicon sprayed film of the present invention, it is possible to obtain a sprayed film that is denser, has a smaller pore diameter, and has a uniform pore distribution than the conventional plasma sprayed film, and is suitable for a member for a semiconductor manufacturing apparatus. A silicon sprayed film can be provided.

The volume-based median diameter (D50) of the slurry containing silicon particles is 1 to 10 μm, but if it is less than 1 μm, the melted particles tend to agglomerate, and the deposit becomes a lump aggregate structure. The sprayed film cannot be formed without adhering. The median diameter (D50) is preferably 1 to 10 μm, and more preferably 3 to 8 μm.
Here, in the present invention, the “median diameter (D50)” can be measured from the volume-based particle diameter by a conventional method such as a laser diffraction / scattering method. In addition, the magnification at the time of evaluation of an average pore diameter and a porosity shall be 500-3000.

Examples of the solvent used for preparing the slurry containing silicon particles include water, alcohols such as ethanol, methanol, and IPA, other organic solvents, petroleum, kerosene, and the like.
Further, for the purpose of improving the dispersibility of the primary particles, a ceramic dispersant and an antifoaming agent mainly composed of a higher alcohol may be added to the slurry.

  There is no restriction | limiting in particular as an HVOF thermal spraying apparatus, A commercially available thing can be used. The fuel to be used is not limited, and liquid fuel such as petroleum and kerosene, or gaseous fuel such as propane, propylene, acetylene, and hydrogen can be used. In addition, a so-called HVAF (High Velocity Air-Fuel) spraying apparatus using air instead of oxygen can also be used.

  As conditions for HVOF spraying, the spraying distance (distance from the nozzle tip of the HVOF spraying apparatus to the base material) can be set, for example, between 50 and 170 mm, and preferably 50 to 130 mm. In addition, the combustion pressure can be set at 0.2 to 1.0 MPa. More preferably, it is 0.4 MPa or more.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples.

[Examples 1-6, Comparative Examples 1-2]
In each of the examples and comparative examples, IPA was used as a solvent, and a silicon particle-containing slurry was prepared so that the volume-based median diameter (D50) of the silicon particles was a numerical value described in Table 1. Next, using the HVOF thermal spraying apparatus using petroleum as a fuel, the prepared silicon particle-containing slurry was HVOF sprayed on a base material (aluminum alloy (A6061)) to form a silicon sprayed film. At this time, in each of the examples and comparative examples, the spraying distance was set to the distance shown in Table 1. The conditions for HVOF spraying are as follows.
Oxygen flow rate: 520 L / min
Oil flow rate: 220 mL / min

[Comparative Example 3]
Using a plasma spraying apparatus (Aeroplasma, APS-7100), silicon was sprayed on the base material to form a silicon sprayed film.

An X-ray diffraction spectrum was measured on the obtained silicon sprayed film using a fluorescent X-ray analyzer (manufactured by Nippon Philips Co., Ltd., PW-1480) under the following conditions.
X-ray light source: Cu-Kα ray (wavelength: 1.54060 mm)
Scan step: 0.02 °
Scanning axis: 2θ
Scanning range: 10-80 °

  In each of Examples 1 to 6, the half width of the diffraction peak at a diffraction angle 2θ = 28.4 ± 0.5 ° was in the range of 0.23 to 1.0 °. The 1/10 intensity value width at a diffraction angle 2θ = 28.4 ± 0.5 ° was 0.6 to 2.0 °. In Comparative Example 3, the half width was 0.22 °. The 1/10 intensity value width at a diffraction angle 2θ = 28.4 ± 0.5 ° was 0.5 °. In Comparative Examples 1 and 2, no X-ray diffraction spectrum was measured because no silicon sprayed film was formed.

(Evaluation)
The sinterability of the silicon sprayed film obtained in each example and comparative example was evaluated according to the following evaluation criteria. Further, the average pore diameter, porosity, and surface roughness Ra of the sprayed surface of the silicon sprayed film obtained in each of the examples and comparative examples were measured as follows. The measurement results are shown in Table 1.
(1) Sinterability When the obtained silicon sprayed film is visually observed, a case where massive agglomeration is observed is “excessive sinterability”, a case where massive agglomeration is not significantly recognized and the porosity is 2% or less. When “sinterability was high” and adhesion of the melt was not observed, it was defined as “no adhesion”.
(2) Average pore diameter From the SEM photograph of the cross section of the formed silicon sprayed film, the diameter of the pores (the distance between the largest intersections of straight lines passing through the pores) was measured at 10 to 30 locations, and the average value was evaluated. .
(3) Porosity The SEM photograph of the cross section of the formed silicon sprayed film was subjected to image processing to binarize the pores, and the area was calculated. 10 to 30 spots were measured per visual field, and the average value was evaluated.
(4) Distribution of pores It was evaluated whether the pores were uniform or non-uniform by SEM photographs of the cross section of the formed silicon sprayed film.
(5) Surface roughness Ra
The surface roughness after thermal spraying was measured with a stylus type surface roughness meter. (Conforms to JIS B0601)

  The SEM photograph of each cross section of the silicon sprayed film of Example 4 and Comparative Example 3 is shown in FIG. Moreover, the SEM photograph of the surface of the silicon sprayed film of Example 4 and Comparative Example 3 is shown in FIG.

From Table 1, in Examples 1-6, the silicon sprayed film whose porosity is 2% or less and whose average pore diameter is 1 micrometer or less was obtained. On the other hand, Comparative Examples 1 and 2 having a large volume-based median diameter (D50) of silicon particles could not even form a sprayed film. Further, in Comparative Example 3 in which the sprayed film was formed by plasma spraying, both the average pore diameter and the porosity were large, and a dense sprayed film was not obtained.
On the other hand, FIG. 2 shows that the silicon sprayed film of the present invention has a lower porosity than the plasma sprayed film, and FIG. 3 shows that the silicon sprayed film of the present invention has a smaller surface roughness Ra than the plasma sprayed film. I understand.

Claims (3)

  In the X-ray diffraction spectrum, a half-width of a diffraction peak at a diffraction angle 2θ = 28.4 ± 0.5 ° is 0.23 to 1.0 °, a silicon sprayed film.   2. The silicon sprayed film according to claim 1, wherein the porosity is 2% or less and the average pore diameter is 1 μm or less.   A method for producing a silicon sprayed film, comprising a step of spraying a slurry containing silicon particles having a volume-based median diameter (D50) of 1 to 10 μm by a high-speed flame spraying method (HVOF).