JP7562482B2 - Semiconductor manufacturing components and their manufacturing method - Google Patents

Description

The present invention relates to semiconductor manufacturing components and their manufacturing methods, and more particularly to semiconductor manufacturing components suitable for focus rings used in plasma processing equipment, and their manufacturing methods.

In a semiconductor device manufacturing process, a plasma processing apparatus such as a plasma etching apparatus or a plasma CVD apparatus is used to perform processing such as etching on a substrate to be processed. In this case, in order to make the plasma processing of the substrate to be processed uniform, a focus ring is disposed as a semiconductor manufacturing component so as to surround the periphery of the substrate to be processed.
This focus ring is provided on the outside of the substrate to be processed. For example, by placing the substrate to be processed on its inner periphery, a so-called pseudo substrate to be processed (pseudo wafer) is formed around the substrate to be processed, thereby achieving uniform plasma processing of the substrate to be processed (the wafer).

The focus ring is generally made of silicon and is formed into a ring shape with an outer diameter larger than the substrate being processed. Specifically, the focus ring is manufactured, for example, by cutting a disk-shaped member from a single crystal silicon ingot and then removing the center portion of the disk-shaped member to produce a ring-shaped focus ring.

Incidentally, as described above, focus rings have conventionally been manufactured by processing a silicon ingot into a ring shape, but boron carbide (B ₄ C) is expected to become a material with a longer life in the future.
Boron carbide has excellent corrosion resistance because it does not easily react with oxygen-free fluorine-based and chlorine-based corrosive gases or oxygen-free plasma. Even if it reacts with fluorine or chlorine, a reactant with high vapor pressure is generated, so that it is released outside the system as a gas without generating particles.

Patent Document 1 states that it is desirable for boron carbide to be made of a sintered body with a relative density of 98% or more. This is because if the boron carbide has a low density and a large number of pores, the contact area with corrosive gases and plasma increases accordingly, and wear is accelerated. Therefore, it is preferable for the boron carbide to have a relative density of 98% or more, particularly 99% or more, and furthermore, an open porosity of 0.2 or less.
It is considered necessary for the material to be a dense body having a density of less than 50%.

According to Patent Document 1, as the diameter of silicon wafers increases, manufacturing equipment and components themselves also become larger, and therefore, in order to maintain the durability of the components, it is desirable for them to have a flexural strength of 300 MPa or more.
According to the manufacturing method disclosed in Patent Document 1, for example, boron carbide powder having an average particle size of 20 μm or less is filled into a mold or formed into a desired shape, and then hot pressed in a non-oxidizing atmosphere at 2100 to 2300° C. to obtain a boron carbide powder.

Patent Document 1 also shows that by adding a sintering aid such as C (carbon), SiC, or _{Si3N4 ,} sintering can be performed at a lower temperature in a non-oxidizing atmosphere or in a vacuum, and further that the green body or sintered body can be heat-treated in an inert atmosphere of 1000 atmospheres or more by hot isostatic sintering to further densify it.

Japanese Patent Application Publication No. 11-102900

In recent dry etching techniques, oxygen plasma etching, Ar plasma etching, or fluorine-based plasma etching, etc., are used, and very high-frequency power is also used.

For example, before performing anisotropic processing on a substrate using dry etching technology, a resist pattern is generally formed using lithography technology. A 193 nm ArF immersion device has a resolution of 38 nm, but multi-patterning technology has exceeded this resolution limit to realize patterns of 10 to 7 nm.

A common method for double patterning is the sidewall process, which utilizes the residue on the pattern sidewalls formed after dry etching. Specifically, an amorphous carbon layer, a SiON layer, an anti-reflective film layer, and a resist pattern are formed by ArF immersion exposure on the SiN film on which the final line pattern is to be formed.

The resist pattern is then shrunk by isotropic etching using oxygen plasma, and the anti-reflective film, SiON film, and amorphous carbon layer are dry etched in that order to form a carbon pattern. When an ALD (atomic layer deposition) film is deposited on the carbon pattern and then dry etching is performed, sidewalls remain on the side walls of the carbon pattern as etching residues, and when the carbon is removed, only the sidewalls remain. Using these sidewalls as a mask, the SiN film is dry etched, and when the mask is removed, an extremely fine line pattern is formed.

In addition, it is necessary to process very deep holes for DRAM capacitors and 3D NAND memory holes. In order to form these high aspect ratio microholes, a highly accurate anisotropic shape and a high selectivity to the mask and the underlayer film are required.
For this purpose, a fluorocarbon-based gas is used as the etchant gas, and a technique is adopted in which a polymer film is deposited as a sidewall protective film on the sidewalls of the holes in the _SiO2 film and the mask using CFx radicals, while ions such as CFx ⁺ and Ar ⁺ are drawn vertically into the holes in the _SiO2 film using an RF bias to perform vertical etching.

Furthermore, if the hole becomes too deep, the reaction products cannot be exhausted properly and may accumulate at the bottom of the hole, causing the etch to stop. In such cases, a method known as " _O2 flush" is used to remove the reaction products by oxygen plasma etching.

In order to increase the etching rate of the _SiO2 film, it is necessary to increase the amount of ion incidence, increase the total amount of F in the radicals, and provide sufficient ion energy. To achieve this, the power of the high frequency for plasma generation, the flow rate of the fluorocarbon gas, the power of the high frequency for ion attraction, etc. are adjusted.

Thus, recent dry etching techniques use oxygen plasma etching, Ar plasma etching, or fluorine-based plasma etching, and also use very high-frequency power.

However, when the focus ring (semiconductor manufacturing component) of a plasma processing device is made of boron carbide material, it is unlikely to react with fluorine or chlorine-based corrosive gases or plasma that do not contain oxygen, but when oxygen is contained (in the case of oxygen plasma), there is an issue that the corrosion resistance is poor. In addition, boron carbide is a difficult material to process due to its hardness, and it is very difficult and costly to process the shape and surface properties to a state suitable for the substrate to be processed.

The present invention has been made to solve the above problems, and aims to provide a semiconductor manufacturing component made of boron carbide that can be easily processed into a desired shape and has excellent corrosion resistance, particularly in reactions with oxygen plasma, and a method for manufacturing the same.

The semiconductor manufacturing member of the present invention, which has been made to solve the above-mentioned problems, is characterized in that it has a silicon carbide-containing boron carbide film on at least a surface thereof, the silicon carbide content being 5 wt % or more and 18 wt % or less, with the remainder being boron carbide, and the silicon carbide-containing boron carbide film has a porosity of 3.9% or more and 5.0% or less .
Moreover , it is preferable that the film is formed on the surface of a substrate made of silicon.

In this way, at least the surface of the semiconductor manufacturing component contains 5 wt% to 18 wt% silicon carbide in boron carbide, improving corrosion resistance to oxygen plasma and Ar plasma. In addition, by reducing the porosity to 5% or less, the surface area exposed to the plasma is reduced, further reducing damage. Furthermore, when the base material of the semiconductor manufacturing component is made of silicon, the base material can be precisely machined using existing silicon manufacturing technology, and by using this as the base material, the shape and surface properties are controlled, so that it is possible to easily create shapes such as focus rings without much post-processing.

In addition, the present invention, which has been made to solve the above-mentioned problems, provides a method for manufacturing semiconductor manufacturing members, which comprises preparing a raw material containing silicon carbide and boron carbide and spraying it onto a substrate, thereby forming a sprayed coating consisting of boron carbide containing 5 wt % or more and 18 wt % or less of silicon carbide and having a porosity of 3.9% or more and 5.0% or less .
The substrate may be removed from the semiconductor manufacturing member to provide only the film.

As described above, the surface of the semiconductor manufacturing member of the present invention contains 5 wt % to 18 wt % silicon carbide in boron carbide, which improves corrosion resistance against oxygen plasma and Ar plasma. Furthermore, when the substrate of the semiconductor manufacturing member is made of silicon, existing silicon manufacturing technology can be used for the substrate itself, making it easy to create precisely machined shapes such as focus rings.

The present invention provides a semiconductor manufacturing component made of boron carbide that can be easily processed to a desired shape and has excellent corrosion resistance, particularly in reaction with oxygen plasma, and a method for manufacturing the same.

FIG. 1 is a cross-sectional view showing a schematic configuration of a member for manufacturing a semiconductor device. 2(a) and (b) show modified examples of the semiconductor manufacturing member of FIG. FIG. 3 is a graph showing the results of the embodiment of the present invention and the comparative example with respect to the amount of Ar sputtering. FIG. 4 is a graph showing the results of the oxygen plasma consumption amount for the embodiment of the present invention and the comparative example. FIG. 5 is a graph showing the results of the embodiment of the present invention and the comparative example with respect to the amount of fluorine plasma consumption.

The following describes an embodiment of the present invention with reference to Figures 1 and 2. Note that the present invention is not limited to the embodiment described below. Also, Figure 1 is a cross-sectional view that shows a schematic configuration of a semiconductor manufacturing component, and Figure 2 shows a modified example of the semiconductor manufacturing component of Figure 1, so the dimensional relationships between the elements, the ratios between the elements, etc. differ from the actual ones.

The semiconductor manufacturing member 100 shown in the figure is formed of a substrate 1 and a silicon carbide-containing boron carbide film 2 formed to cover the surface of the substrate 1.

The substrate 1 may be any material that is plasma resistant, and silicon or alumina are suitable examples. In particular, when silicon is used as the substrate 1, when forming a focus ring as the semiconductor manufacturing component 100, the shape can be easily processed using existing techniques and equipment.

The silicon carbide-containing boron carbide film 2 is formed to a thickness of, for example, 500 μm. The silicon carbide (SiC) content in the silicon carbide-containing boron carbide film 2 is 5 wt % or more and 18 wt % or less. The silicon carbide content is preferably more than 5 wt %, and more preferably, the silicon carbide content is 6 wt % or more and 10 wt % or less.
If the silicon carbide content is less than 5 wt %, the corrosion resistance effect against oxygen plasma decreases, which is undesirable.
On the other hand, when the silicon carbide content is 5 wt % or more and up to 18 wt %, the corrosion resistance against oxygen plasma is improved. When the silicon carbide content exceeds 18 wt %, no further corrosion resistance effect can be expected.

Furthermore, with respect to Ar plasma, sputtering of Ar ⁺ ions occurs due to physical corrosion, so the corrosion resistance is related to the strength of atomic bonds.
Since silicon carbide has smaller atomic bonds than boron carbide, the sputtering rate increases and the corrosion resistance decreases as the amount of boron carbide added increases. When the silicon carbide content is 18 wt% or less, the corrosion resistance increases, and when it is further reduced to less than 5 wt%, the corrosion resistance remains almost unchanged.
The silicon carbide content has almost no effect on fluorine plasma.

In addition, in the dry etching process used in semiconductor manufacturing, only a limited number of processes use a single gas plasma atmosphere, and most involve interactions in a mixed gas plasma atmosphere. Furthermore, considering advanced processes in which extremely high-frequency power is used, it is more preferable that the silicon carbide content be 6 wt% or more and 10 wt% or less to obtain a stable corrosion resistance effect.

Although the silicon carbide-containing boron carbide film 2 is preferably formed by thermal spraying, it may be formed by a CVD method by adjusting the composition ratio of boron carbide and silicon carbide, or may be formed by a PVD method.
The CVD method can easily form a high-purity film, whereas the thermal spraying method has the advantage that it can easily form a film on a variety of substrates.

In the embodiment shown in FIG. 1, the silicon carbide-containing boron carbide film 2 is formed on the surface of the substrate 1. However, as shown in FIG. 2(a), a thick silicon carbide-containing boron carbide film 2 may be formed on the upper surface of the substrate 1, and as shown in FIG. 2(b), the substrate 1 may be removed to produce a semiconductor manufacturing component 100 consisting only of the silicon carbide-containing boron carbide film 2.

Furthermore, when the silicon carbide-containing boron carbide film 2 is a thermal sprayed film, the temperature and collision speed of the raw material particles deposited on the substrate 1 during the film formation process by thermal spraying are important factors that determine the density of the coating and its adhesion to the substrate 1.
In the present invention, the temperature and impact speed of the raw material particles are not limited, but a thermal spraying method may be adopted according to the physical properties of the coating material and its application. For example, boron carbide has a high melting point of 2763°C and is oxidized in an oxygen atmosphere, so reduced pressure plasma spraying and electromagnetic acceleration plasma spraying are preferred.

In addition, silicon carbide has a sublimation temperature of 2545°C to 2730°C, which is lower than the melting point of boron carbide, 2763°C, and it usually evaporates during thermal spraying. Therefore, depending on the thermal spraying method, it may be necessary to adjust the particle size and mixing amount of silicon carbide, and the silicon carbide will have a structure dispersed as particles in the thermal sprayed film.

As described above, according to the embodiment of the present invention, a silicon carbide-containing boron carbide film 2 is formed on a substrate 1, and the boron carbide contains 5 wt % or more and 18 wt % or less of silicon carbide, more preferably 6 wt % or more and 10 wt % or less of silicon carbide, thereby improving corrosion resistance to oxygen plasma and Ar plasma.
Furthermore, when the base material 1 is made of silicon, existing manufacturing techniques can be used, and therefore, it is possible to easily shape components used in semiconductor manufacturing, such as focus rings.

The semiconductor manufacturing components and manufacturing method thereof according to the present invention will be further explained based on examples.

Example 1
In Example 1, a silicon carbide-containing boron carbide (B ₄ C) film having a thickness of 500 μm was formed on a silicon substrate by thermal spraying to prepare a sample. The silicon carbide (SiC) content in the boron carbide film after thermal spraying was set to 5 wt %. The surface after thermal spraying was mirror-finished.
The porosity of the silicon carbide-containing boron carbide film, which was observed with an optical microscope and calculated with image editing software, was 3.9%.
The sputtering rate of this sample with respect to Ar ions was measured. The measurement conditions were as follows: an Ar ion beam capable of generating high energy was used, the voltage was 3 kV, the beam current was 25 μA, and the irradiation time was 3 hours. After that, the amount of sputtering wear was measured.

Example 2
In Example 2, the content of silicon carbide in the silicon carbide-containing boron carbide film of the sample was set to 7 wt %. The other conditions were the same as those in Example 1. The porosity of the silicon carbide-containing boron carbide film was 4.1%. The sputtering rate of this sample with respect to Ar ions was measured in the same manner as in Example 1.

Example 3
In Example 3, the silicon carbide content in the silicon carbide-containing boron carbide film of the sample was set to 18 wt %. The other conditions were the same as those in Example 1. The porosity of the silicon carbide-containing boron carbide film was 5.0%. The sputtering rate of this sample with respect to Ar ions was measured in the same manner as in Example 1.

(Comparative Example 1)
In Comparative Example 1, the content of silicon carbide in the silicon carbide-containing boron carbide film of the sample was set to 0 wt %. The other conditions were the same as those in Example 1. The porosity of the boron carbide film was 3.5%. The sputtering rate of this sample with respect to Ar ions was measured in the same manner as in Example 1.

(Comparative Example 2)
In Comparative Example 2, a silicon carbide film (100%) having a thickness of 500 μm was formed on a silicon substrate by a CVD method to prepare a sample. The other conditions were the same as those in Example 1. The porosity of the silicon carbide film was 0%. The sputtering rate of this sample with respect to Ar ions was measured in the same manner as in Example 1.

(Comparative Example 3)
In Comparative Example 3, a silicon substrate having no film formed on its surface was used as a sample. The other conditions were the same as in Example 1. The sputtering rate of this sample with respect to Ar ions was measured in the same manner as in Example 1.

The graph in Fig. 3 shows the results of Examples 1, 2, and 3 and Comparative Examples 1, 2, and 3. In the graph in Fig. 3, the vertical axis represents the etching amount (μm/h).
As shown in the graph of FIG. 3, it was found that the amount of etching was suppressed by forming a silicon carbide-containing boron carbide film on the silicon surface (Comparative Example 1, Examples 1, 2, and 3).

Example 4
The etching rate for oxygen plasma was measured for a sample prepared in the same manner as in Example 1. The etching rate for oxygen plasma was measured by exposing the sample to oxygen plasma for 30 minutes under reduced pressure of 2.66 Pa, high frequency power of 800 W, _O2 = 50 sccm, and 200°C using an ICP plasma etching device. After that, the amount of wear was measured.

Example 5
The same experiment as in Example 4 was carried out on a sample prepared in the same manner as in Example 2.

Example 6
The same experiment as in Example 4 was carried out on a sample prepared in the same manner as in Example 3.

(Comparative Example 4)
The experiment of Example 4 was carried out on a sample prepared in the same manner as in Comparative Example 1.

(Comparative Example 5)
The experiment of Example 4 was carried out on a sample prepared in the same manner as in Comparative Example 2.

(Comparative Example 6)
The experiment of Example 4 was carried out on a sample prepared in the same manner as in Comparative Example 3.

The graph in Fig. 4 shows the results of Examples 4, 5, and 6 and Comparative Examples 4, 5, and 6. In the graph in Fig. 4, the vertical axis represents the etching amount (μm/h).
As shown in the graph of FIG. 4, when a boron carbide film is formed on a silicon surface, it was found that the amount of etching was suppressed by setting the silicon carbide content to 5% (Example 4), 7% (Example 5), and 18% (Example 6).

(Example 7)
The etching rate for fluorine plasma was measured for a sample prepared in the same manner as in Example 1. The etching rate for fluorine plasma was measured using an ICP plasma etching device, in which the sample was exposed to fluorine plasma for 4 hours at room temperature under a reduced pressure of 2.66 Pa, a high frequency power of 500 W/bias power of 40 W, and _CF4 = 100 sccm. After that, the amount of wear was measured.

(Example 8)
The experiment of Example 7 was carried out on a sample prepared in the same manner as in Example 2.

Example 9
The experiment of Example 7 was carried out on a sample prepared in the same manner as in Example 3.

(Comparative Example 7)
The experiment of Example 7 was carried out on a sample prepared in the same manner as in Comparative Example 1.

(Comparative Example 8)
The experiment of Example 7 was carried out on a sample prepared in the same manner as in Comparative Example 2.

(Comparative Example 9)
The experiment of Example 7 was carried out on a sample prepared in the same manner as in Comparative Example 3.

The graph in Fig. 5 shows the results of Examples 7, 8, and 9 and Comparative Examples 7, 8, and 9. In the graph in Fig. 5, the vertical axis represents the etching amount (μm/h).
As shown in the graph of FIG. 5, no difference in effectiveness was observed when a boron carbide film, a silicon carbide film, or a boron carbide film with varying silicon carbide content was formed on a silicon surface.

Example 10
A silicon production member was manufactured in the same manner as in Example 1. However, the sprayed film was made thicker to 2.0 mm, and then the silicon substrate was polished and removed. Tests equivalent to those in Examples 1, 4, and 7 were carried out, and the corrosion resistance to various plasmas was equivalent to those in Examples 1, 4, and 7.

(Comparative Example 10)
A silicon production member was manufactured in the same manner as in Example 1. However, the thickness of the sprayed film was changed to 100 μm, 200 μm, and 300 μm. As a result, at 100 μm and 200 μm, the sprayed film was slightly non-uniform with a porosity of about 10 to 20%. At 300 μm, the sprayed film was formed almost uniformly, and the porosity was 5% or less.

The results of Examples 1 to 10 above confirmed that the corrosion resistance to Ar plasma and oxygen plasma can be improved by setting the silicon carbide content in the boron carbide film to 5 wt% or more and 18 wt% or less. It was found that the effect was particularly large when the silicon carbide content in the boron carbide film was 6 wt% or more and 10 wt% or less.

REFERENCE SIGNS LIST 1 Substrate 2 Silicon carbide-containing boron carbide film 100 Semiconductor manufacturing member

Claims (4)

A semiconductor manufacturing member, comprising: a silicon carbide-containing boron carbide film on at least a surface thereof, the silicon carbide content of which is 5 wt % or more and 18 wt % or less, with the remainder being boron carbide; and the silicon carbide-containing boron carbide film having a porosity of 3.9% or more and 5.0% or less . The semiconductor manufacturing member according to claim 1, characterized in that the film is formed on a substrate, and the substrate is made of silicon. A method for manufacturing a semiconductor manufacturing member, comprising preparing a raw material containing silicon carbide and boron carbide, spraying the raw material onto a substrate, and forming a sprayed film made of boron carbide containing 5 wt% or more and 18 wt% or less of silicon carbide , and having a porosity of 3.9% or more and 5.0% or less . A method for producing a member for use in semiconductor production, comprising removing a base material from the member for use in semiconductor production according to claim 3 .

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