JP2001288527A - Aluminum alloy for plasma treating system and heater block - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aluminum alloy for a plasma treating system excellent in corrosion resistance, contamination resistance and brazing properties, and to provide a heater block. SOLUTION: In this aluminum alloy for a plasma treating system, an aluminum alloy used for one or more kinds of parts provided in a plasma treating system in which the object to be treated is subjected to prescribed treatment by plasma or active species obtained by being made into plasma in a vacuum chamber has a composition containing, by mass, 0.02 to 0.4% copper(Cu), 0.2 to 0.6% silicon(Si) and 0.45 to 0.9% magnesium(Mg), and the balance aluminum(Al) with impurity elements.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum alloy for a plasma processing apparatus which is installed in a plasma processing apparatus for performing a predetermined process on an object to be processed by an active species obtained by plasma or plasma conversion in a vacuum chamber. And a heater block.

[Prior art]

[0002] In general, a plasma CV is set in a vacuum chamber.
When performing a plasma process such as a D process or a plasma etching process, a heater block for heating and mounting an object to be processed is used. For example, Japanese Patent Application Laid-Open No. 5-1
The heater block disclosed in Japanese Patent No. 52425 includes a block main body in which a heater is cast and a surface plate joined by brazing to an upper surface side of the block main body.

The surface plate of the heater block and the block body are generally made of Al from the viewpoint of castability and corrosion resistance.
-A Mg-based alloy (JISA5000-based) is employed. In order to respond to the miniaturization of device design rules and the high density of plasma due to the recent development of technology,
It is also known that a substrate of high-purity aluminum (Al is 99.9% by mass or more) is used.

[0004]

However, in the case of performing a plasma treatment, if a heater block or the like is formed using a conventional aluminum alloy (Al alloy), the following problems exist.

[0005] That is, since the Al-Mg alloy is inferior in brazing properties, a special low-temperature brazing material has been used for brazing the surface plate and the block body. This low-temperature brazing material is disadvantageous because it leads to an increase in cost. In addition, since the Al-Mg alloy has low thermal conductivity, the surface temperature distribution of the heater block tends to be non-uniform. Further, in the case of performing the plasma treatment, Mg, which is an alloy-containing component having a high vapor pressure, evaporates, causing contamination of a workpiece (such as a wafer).

When an anodic oxide coating such as an alumite treatment is applied to an Al-Mg alloy to improve corrosion resistance, a thermal crack occurs in the coating due to a difference in thermal expansion coefficient between the base material and the coating. As a result, it was difficult to improve the corrosion resistance by the coating.

The present invention has been made in view of the above problems, and is an aluminum alloy for a plasma processing apparatus which is excellent in corrosion resistance, stain resistance and brazing properties, and excellent in heat cracking resistance of an anodized film. And a heater block formed from the aluminum alloy.

[0008]

The present invention has the following configuration to achieve the above object. That is, an aluminum alloy used for one or more types of components provided in a plasma processing apparatus that performs a predetermined process on an object to be processed by plasma or activated species obtained by turning into plasma in a vacuum chamber, 0.02 to 0.4% by mass, 0.2 to 0.6% by mass of Si, 0.4% by mass of Mg
An aluminum alloy for a plasma processing apparatus containing 5 to 0.9% by mass, other unavoidable elements, and the balance being aluminum (Al) was used.

As described above, by adjusting the contents of Cu, Si, and Mg, the precipitate (Mg ₂ Si) precipitates by aging, and the Cu becomes concentrated around the precipitate,
It is convenient as an aluminum alloy used for performing the plasma treatment.

[0010] Further, the aluminum alloy base material for the plasma processing apparatus has an anodic oxide film on the surface thereof. With such a configuration, a sufficient gap is formed at the triple point of the cell in the anodic oxide coating to reduce the difference in thermal expansion.

[0011] Further, a heater block provided in the plasma processing apparatus includes a block main body in which a heating means for heating a position on which an object to be processed is mounted is provided. 02 to 0.4% by mass,
0.2 to 0.6 mass% of Si and 0.45 to 0.1 mass% of Mg.
The heater block was formed from the aluminum alloy for a plasma processing apparatus containing 9% by mass, other unavoidable elements, and the balance being aluminum (Al).

[0012] With this configuration, when the surface plate is brazed to the heating plate of the block main body or when the surface plate is brazed to the upper surface of the block main body in which the heating element is cast-in, the cost is low. Versatile brazing material can be used,
It is also possible to prevent evaporation of Mg having a high vapor pressure, which is a pollution source.

The heater block has a structure in which a mounting plate is detachably provided at a position where the object to be processed is mounted via an engaging means.
2 to 0.4% by mass, and 0.2 to 0.6% by mass of Si,
Mg was made from the aluminum alloy for a plasma processing apparatus containing 0.45 to 0.9% by mass, other unavoidable elements, and the balance being aluminum (Al). With such a configuration, the mounting surface of the workpiece that is easily damaged can always be in an appropriate state.

The heater block is preferably provided with an anodic oxide film at a position exposed to the plasma of the plasma processing apparatus. With this configuration, it is excellent in corrosion resistance and low pollution.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view schematically showing a heater block. An aluminum alloy for a plasma processing apparatus used for plasma processing such as plasma CVD processing and plasma etching contains copper (Cu) in an amount of 0.02 to 0.02.
0.4% by mass, 0.2 to 0.6% by mass of silicon (Si), 0.45 to 0.9% by mass of magnesium (Mg), other unavoidable elements, and aluminum (A)
l).

The aluminum alloy for the plasma processing apparatus is as follows:
The content of Cu contained is in the range of 0.02 to 0.4% by mass. This is because Cu is solid solution hardened and Mg, A
In addition to forming a compound phase with 1 to precipitate and improve the strength,
It acts as a nucleus for the precipitation of other alloy elements, and has the effect of promoting precipitation hardening. When Cu is within a predetermined range, Cu concentrates around Mg ₂ Si, and thus has an effect of improving the heat crack resistance of the alumite coating (anodized coating). If the Cu content is less than 0.02% by mass, thermal cracking occurs when an alumite coating (anodized coating) is formed. If the Cu content exceeds 0.4% by mass, the solidus temperature decreases, the difference from the liquidus temperature of the brazing material decreases, and the aluminum alloy also melts, making brazing difficult. Become.

And aluminum for a plasma processing apparatus.
The alloy has a Si content in the range of 0.2 to 0.6% by mass.
are doing. Si, together with Mg, by artificial aging at high temperature
Mg _TwoPrecipitates as Si to improve the strength. Si
If the content is less than 0.2% by mass, the required strength can be obtained.
Absent. When the content of Si exceeds 0.6% by mass,
The phase line temperature decreases and the difference from the liquidus temperature of the brazing material is small.
And the aluminum alloy also melts, making brazing difficult.
It becomes difficult.

The aluminum alloy for a plasma processing apparatus has a Mg content of 0.45 to 0.9% by mass. Mg is Mg ₂ with Si by high temperature artificial aging.
Precipitates as Si to improve the strength. If the Mg content is less than 0.45% by mass, the required strength cannot be obtained. On the other hand, when the content of Mg exceeds 0.9% by mass, the solidus temperature decreases, the difference from the liquidus temperature of the brazing material decreases, and the aluminum alloy also melts, making brazing difficult. At the same time, the evaporation of Mg contaminates an object to be processed (such as a wafer) in the plasma processing apparatus. In particular, since Mg is a metal element, it causes a malfunction of an integrated circuit formed on a Si wafer.
By setting the content in the alloy component to 0.45 to 0.9% by mass, the amount of Mg gas in the released gas could be reduced.

It is essential that the aluminum alloy for a plasma processing apparatus used in the present invention contains a predetermined amount of copper, silicon, and magnesium as described above, but does not impair the objects and effects of the present invention. Other elements such as iron (Fe) may be included in the range. That is, the production of the aluminum alloy for the plasma processing apparatus used in the present invention is based on the aluminum alloy number 6000, and iron is mixed to some extent (for example, 0.2% by mass or less) as an unavoidable element. Therefore, the “unavoidable element” in the present invention is interpreted as including an element which does not impair the purpose and effect of the present invention, regardless of the amount.

The aluminum alloy for the plasma processing apparatus is formed into an appropriate shape by subjecting an aluminum alloy material obtained by appropriate plastic working such as rolling, forging, or extrusion to a solution treatment and an aging treatment. It may be manufactured by machining. Further, after the aluminum alloy material is formed into a predetermined shape, a solution treatment and an aging treatment may be performed.

The conditions of the solution treatment and the aging treatment include, for example, solution treatment 515 to 515 which is a normal T6 treatment.
550 ° C, water cooling, aging 170 ° C x 8h (hour), 1
Perform 55-165 ° C. × 18 h.

The aluminum alloy for the plasma processing apparatus is preferably used after forming an anodic oxide film such as an alumite film on the surface thereof. As a method of forming the anodic oxide film, the composition, concentration, and electrolysis conditions (voltage, current density, current-voltage waveform) of the electrolytic solution may be appropriately selected and performed. As for the anodizing solution, the electrolytic treatment is performed using a solution containing at least one element selected from C, S, N, P, and B.

As the anodizing solution, for example, it is effective to use an aqueous solution containing at least one selected from oxalic acid, formic acid, sulfamic acid, phosphorous acid, boric acid, nitric acid or a compound thereof, phthalic acid or a compound thereof. It is. The thickness of the anodic oxide film is not particularly limited, but may be in the range of 0.
Suitably, it is about 1 to 200 μm, preferably about 0.5 to 70 μm, and more preferably about 1 to 50 μm.

An aluminum alloy for a plasma processing apparatus having an anodized film formed thereon is suitable for various uses used in a high-temperature corrosive atmosphere, and is particularly suitable for forming a corrosive gas, plasma, or plasma under a high-temperature environment. It is preferably used as a vacuum chamber of a plasma processing apparatus used in semiconductor manufacturing equipment and a component provided therein, such as a heater block. used.

Next, an example in which the aluminum alloy for a plasma processing apparatus is used for a heater block is shown in FIG.
This will be described with reference to FIG. FIG. 1 is a schematic diagram showing a cross section of the heater block 1. As shown in FIG. 1, a heater block 1 installed in a plasma processing apparatus A includes a mounting plate 2 on which a workpiece W such as a wafer to be processed is mounted, and an engaging means A surface plate 3 that is detachably supported by using a fastening screw 8 as a base, and a block body 4 that supports a peripheral position on a lower surface of the surface plate 3.

The block body 4 includes a cover body 5 attached to the lower surface of the surface plate 3 so as to support the peripheral side, and a heating plate 6 provided in contact with the lower surface of the surface plate 3.
And a heating element (heating means (heater)) 7 provided inside the heating plate 6 for heating the work W. The surface plate 3 and the cover 5 are joined by welding such as electron beam, TIG, and MIG, and the surface plate 3 and the heating plate 6 are joined by brazing.

The brazing material used for the heater block 1 is as follows:
It is preferable that the member does not easily evaporate even in the environment where the plasma processing is performed and does not adversely affect the workpiece to be processed. For example, the member is made of JIS, alloy number 4045 of Z3263.

As described above, the heater block 1 is formed by forming an anodic oxide film on the above-mentioned aluminum alloy for a plasma processing apparatus, and can use a versatile brazing material which has little influence on contamination of the work W. Therefore, even when the workpiece W is used in a state where the plasma processing is performed, the workpiece W can be uniformly heated, and the influence of contamination on the workpiece can be minimized.

Here, the configuration of the heater block 1 is composed of the mounting plate 2, the surface plate 3, the cover main body 5, and the heating plate 6, but the following configuration may be adopted. That is, the heater block includes a block body in which the cover body and the heating plate are integrally formed, a surface plate, and a mounting plate. In addition, the cover body, the heating plate and the surface plate are integrally formed with a block body and a mounting plate. Furthermore, the block body in which the heating means for heating the position on which the workpiece is mounted is provided as a heater block (the top surface of the block body is not positioned on the surface plate without using the surface plate and the mounting plate). The configuration of the heater block is not particularly limited, such as a configuration in which a heating plate also serves as the mounting plate.

The engaging means may be provided detachably by screwing the mounting plate to the surface plate.
In particular, the configuration is not limited. Furthermore, the thickness and shape of each member are not particularly limited as long as the objects and effects of the present invention are achieved. Further, even when the heater block has a different configuration as described above, the anodic oxide coating is provided at a position where each heater (surface plate, block body, etc.) is exposed to plasma when used in the plasma processing apparatus. Is provided.

[0031]

EXAMPLES Next, examples using aluminum alloys having the compositions shown in Table 1 will be described. It should be noted that the embodiments described here are merely examples, and the present invention is not limited to the embodiments.

The aluminum alloy is melted and cast into a disc-shaped block main body having a thickness of φ260 × 50 mm by die casting.
A test piece having a plate shape of × 25 × 5 mm was cut out. Then, the cut test piece was subjected to a soaking heat treatment at 540 ° C. for 4 hours, and then, as shown in Table 2, the brazing state, the surface temperature difference measurement, the amount of released gas, the state of the alumite coating after heating and the material A test was conducted to evaluate the proof stress of the steel.

[0033]

【table 1】

[0034]

[Table 2]

As for the evaluation method of the brazing state, the brazing material is made using alloy number 4045 of JIS, Z3263.
The brazing was performed at a solidus temperature of each material of −15 ° C. Then, the bonded surface after brazing was subjected to ultrasonic flaw detection, and a portion where the echo intensity was 80% or more of the strength of a plate having the same thickness was defined as a non-bonded portion. Furthermore, the case where the area ratio of the unbonded portion to the entire bonding area is 20% or less is indicated by “○”, and the case where the area ratio is larger than 20% is indicated by “×”. When the brazing state in Table 1 is x, the heat conduction from the block body to the surface plate becomes uneven, and the Si wafer (work W, FIG.
) Becomes uneven, and uniform processing cannot be performed on the Si wafer.

As a method for measuring the surface temperature difference, a thickness of 25 m
m using a block body (see FIG. 1)
In a static atmosphere at 3 ° C., a current is supplied to an internal heater so that the temperature of a thermocouple provided at a depth of 5 mm from the surface of the block body becomes 450 ° C., and the surface temperature of the block body at that time is measured by a contact type. It was measured with a thermometer.

The difference between the highest temperature and the lowest temperature on the surface of the block body is defined as the surface temperature difference. When the temperature difference becomes large, the temperature distribution of the Si wafer (work W, see FIG. 1) becomes non-uniform, and the process (coating) applied to the Si wafer cannot be obtained uniformly. Therefore, here, the uniform S
The temperature difference was set to 5 ° C. or less as a standard for obtaining the processing of the i-wafer.

The amount of released gas was determined by heating a sample cut out of the heater block in a vacuum and measuring the amount of released gas. The measurement of the released gas amount was performed by an ionization vacuum gauge specified in JISZ8752. The gas components include Mg, water vapor, and the like. If the amount of released gas is large, the Si wafer (work W, see FIG. 1) will be contaminated. In order not to contaminate the Si wafer, 6.5 ×
It was set to 10 ⁻⁵ Pa · m · s ⁻¹ or less. Note that the Mg component in the released gas was determined by a mass spectrometer.

The anodized alumite film after the heating was prepared by subjecting a test piece cut out of the block body to an alumite treatment and heating in the air at 500 ° C. for 1 hour, and then observing the surface of the test piece at 100 magnifications using an optical microscope.な い indicates that no cracks were observed, and X indicates that cracks were observed. If the test piece has cracks, actually heat the heater block and use it.
Cracks may occur in the alumite coating, and corrosion may occur starting from the cracks.

Regarding the proof stress, a test specimen for a tensile test was cut out from the block body after brazing, and the tensile test was performed on the test specimen. If the proof stress is 100 MPa or less, the strength may be insufficient during use by heating, and the material may be deformed by its own weight.

As shown in Table 1, the material code AB of the embodiment
CD is composed of Cu (0.02 to 0.4% by mass), Si
(0.2 to 0.6% by mass) and Mg (0.45 to 0.9%).
Mass%) within the specified range, and in the material symbols E to K of the comparative examples, the contents of Cu, Si, and Mg are set so that at least one of them departs from the specified value. .

As can be seen from the examples in Table 2, Cu, S
When i and Mg were within the range of the present invention, values exceeding the set values were shown in all the evaluation items.

On the other hand, as can be seen from the comparative example,
Cu content is low (E) or high (F)
In this case, the evaluation of the alumite coating after heating and the evaluation of the brazing property become insufficient. On the other hand, if the contents of Si and Mg are too large (G) or too small (H), the evaluation of brazing properties and the evaluation of proof stress become insufficient. Furthermore, Mg
When the content of (I) is large, the evaluation of brazing properties and proof stress is insufficient, and when it is small (J), the proof stress is insufficient. In the case of an Al-Mg alloy (K), all of the brazing properties, the surface temperature difference, the amount of released gas, and the evaluation of the alumite film after heating are insufficient. If Cu, Si, and Mg are out of the specified range,
Inconsistent evaluation is found in at least one of the evaluation items.

[0044]

The present invention has the following advantages because of the construction described above. (1) When an aluminum alloy for a plasma processing apparatus is used in an environment where plasma processing is performed, it is convenient for forming an anodic oxide film, and even when brazing work is performed, Suitable general-purpose products can be used. Therefore, it is possible to use an aluminum alloy that does not adversely affect a processing object even in an environment such as a plasma processing.

(2) Even when the aluminum alloy for a plasma processing apparatus has a structure having an anodic oxide film, it is kept in a uniform heating state, and the anodic oxide film has excellent heat cracking resistance and gas corrosion resistance. Can also be suitably used.

(3) A general-purpose brazing material suitable for a plasma processing environment can be used for the heater block even when necessary portions are brazed.
Even in a plasma environment, it is possible to minimize the adverse effect of the constituent aluminum alloy on the object to be processed.

(4) When an anodic oxide film is formed on the surface of the aluminum alloy used for the heater block, the heater block is excellent in heat cracking resistance and gas corrosion resistance, and is preferably used in a plasma environment. Can be used.

(5) By mounting and dismounting the mounting plate on the surface plate of the heater block via the engaging means,
Since the mounting plate that is damaged can be replaced and used, the heater block is excellent in maintainability and the service life of the entire heater block can be extended. Furthermore, even when the mounting block is provided, the heater block has excellent heat cracking resistance and gas corrosion resistance by forming an anodic oxide film, and is preferably used in a plasma environment. Can be.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a cross-sectional shape of a heater block according to the present invention.

[Explanation of symbols]

 A Plasma processing apparatus 1 Heater block 2 Mounting plate 3 Surface plate 4 Block body 5 Cover body 6 Heating plate 7 Heating body 8 Fastening screw (engaging means)

Claims (6)

[Claims] 1. An aluminum alloy used as one or more components provided in a plasma processing apparatus for performing a predetermined process on an object to be processed by plasma or an active species obtained by turning into plasma in a vacuum chamber. 0.02 to 0.4% by mass of copper (Cu) and silicon (S
i) 0.2 to 0.6% by mass, magnesium (Mg)
, 0.45 to 0.9% by mass, other unavoidable elements, and the balance aluminum (Al). 2. The aluminum alloy for a plasma processing apparatus according to claim 1, further comprising an anodic oxide film on a surface of the base material of the aluminum alloy for a plasma processing apparatus. 3. A heater block provided in the plasma processing apparatus, comprising: a block main body in which a heating unit for heating a position on which an object to be processed is mounted is provided; wherein the block main body is made of copper (Cu). 0.02 to 0.4% by mass and silicon (Si) 0.2 to 0.6% by mass,
A heater block comprising the aluminum alloy for a plasma processing apparatus containing magnesium (Mg) in an amount of 0.45 to 0.9% by mass, other unavoidable elements, and the balance being aluminum (Al). 4. The heater block according to claim 3, wherein an anodic oxide film is provided on a surface of the block body at a position exposed to plasma by the plasma processing apparatus. 5. A mounting plate is detachably provided on the block main body at a position where the object to be processed is mounted via an engaging means, and the mounting plate is made of copper (Cu) of 0.02 to 0. 0.4 mass%
And the plasma containing 0.2 to 0.6% by mass of silicon (Si), 0.45 to 0.9% by mass of magnesium (Mg), other unavoidable elements, and the balance being aluminum (Al). The heater block according to claim 3, wherein the heater block is formed from an aluminum alloy for a processing apparatus. 6. The heater block according to claim 5, wherein the mounting plate is provided with an anodic oxide film at a position exposed to plasma by the plasma processing apparatus.