JP3843645B2 - Reduced pressure heat treatment equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a reduced-pressure heat treatment apparatus that depressurizes the inside of a container provided with a glass window and heat-treats an object to be treated housed through the glass window, and more particularly to the structure of the glass window and the mounting structure thereof.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, in semiconductor manufacturing apparatuses such as plasma processing apparatuses and wafer heat treatment apparatuses, various types of reduced pressure heat treatment apparatuses that perform heat treatment in a reduced pressure atmosphere are used. In these reduced-pressure heat treatment apparatuses, for example, a highly transparent glass window for use in, for example, monitoring plasma emission or measuring the wafer substrate temperature is provided on the wall surface of the metal chamber.
[0003]
FIG. 3 shows an example of the basic configuration of this type of conventional low-pressure heat treatment apparatus, in which (a) is a longitudinal sectional view of the processing vessel, and (b) is an enlarged view of part B shown in (a). .
In FIG. 3A, reference numeral 1 denotes a metal cylindrical chamber having an upper opening. A disc-shaped glass window 2 made of disc-shaped transparent glass is airtightly arranged on the open surface of the chamber 1 so that a sealed container can be formed. On the other hand, an exhaust port 6 and a gas introduction port 5 are provided on the side wall of the chamber 1, and the inside is exhausted by an exhaust pump provided outside via the exhaust port 6, and a desired one is obtained via the gas introduction port 5. By introducing this gas, the inside of the chamber 1 can be made a reduced pressure atmosphere of the desired gas.
[0004]
In addition, a disc-shaped work table 4 that can move in the vertical direction and rotate in a horizontal plane is provided inside the chamber 1, and a workpiece to be processed (not shown) is loaded on the work table 4. Is done. A heating means 7 is installed above the glass window 2, and the work loaded on the work table 4 through the glass window 2 is heated by the heating means 7. As the heating means 7, for example, an infrared lamp heater or an induction coil for generating plasma is used.
[0005]
Further, as shown in FIG. 3B, in order to improve the airtightness between the chamber 1 and the disk-shaped glass window 2, the flange portion 1b of the chamber 1 includes a vacuum O-ring 21 and A flat set ring 22 made of heat-resistant resin is provided, and a flat pressure ring 24 formed of the same material as the set ring 22 is provided on the outer periphery of the upper part of the disk-shaped glass window 2. Is provided. A metal clamping ring 23 disposed on the outer peripheral portion of the upper portion of the disk-shaped glass window 2 via a pressure ring 24 is tightened to the flange portion 1b of the chamber 1 by a plurality of presser bolts 25 disposed on the outer peripheral portion. Then, the vacuum O-ring 21 is compressed, and the disk-shaped glass window 2 and the metal chamber 1 are brought into airtight contact with each other, so that the inside of the chamber 1 is kept airtight and a reduced pressure atmosphere can be created. It becomes.
[0006]
The disk-shaped glass window 2 is heated by heat radiation, heat transfer, and heat conduction from the heating means 7 in addition to the pressure received when the reduced pressure atmosphere is formed, and becomes a high temperature of, for example, 500 ° C. or higher. For this reason, a cooling water groove 8 is provided over the entire circumference of the flange portion 1b of the metal chamber 1, and the flange portion 1b is cooled by flowing cooling water through the cooling water groove 8 to provide a vacuum O-ring. The temperature rise of 21 is suppressed and deterioration is suppressed.
[0007]
In addition to the disk-shaped glass window 2 of the above-described configuration example, the glass window used in the reduced pressure heat treatment apparatus has a flat outer periphery as already filed in Japanese Patent Application No. 9-37478. In some cases, a dome-shaped glass window having a central portion protruding outward is used.
[0008]
[Problems to be solved by the invention]
By the way, in the above-described conventional configuration, the outer peripheral portion of the disk-shaped glass window 2 is cooled by the cooling water flowing in the cooling water groove 8 and is kept at a low temperature of, for example, 150 ° C. or less. Since a temperature difference is generated between the central portion which is at a high temperature of 500 ° C. or more, that is, in the radial direction, a thermal stress is generated inside the disc-shaped glass window 2 due to a difference in thermal expansion.
[0009]
Conventional vacuum heat treatment apparatuses are usually used for processing workpieces that do not require large-area processing, and the outer size of the chamber 1 is relatively small, and the aperture size of the disc-shaped glass window 2 can be small. Even if thermal stress is generated inside the disc-shaped glass window 2 due to the difference in thermal expansion, sufficient strength can be obtained by simply pressing the disc-shaped glass window 2 with the above-described clamping ring 23. Damage to the window 2 could be prevented. However, in recent years, considering mass productivity, there has been a strong demand for increasing the processing capacity by increasing the area of an object, and performing high-speed heat treatment and heat treatment with high uniformity. There is also a need to increase the diameter of the disk-shaped glass window.
[0010]
As in the case of the above-described reduced pressure heat treatment apparatus, in the case of a configuration that ensures the hermeticity between the glass window and the chamber by pressing the outer peripheral edge of the glass window in the vertical direction, against the elongation due to the thermal expansion of the glass window. Since the resisting force is only the frictional force generated between the O-ring in contact with the glass window and the heat-resistant pressure ring, the following problems occur when a large-diameter glass window is used. A point arises.
[0011]
(1) Since the glass window is made of a material having a low thermal conductivity, the temperature difference in the radial direction increases as the diameter of the glass window increases, and tensile stress is applied in the circumferential direction in the vicinity of the outer periphery of the glass window. On the other hand, the glass window component material has a small tensile strength of about 1/20 as compared with the compressive strength, so there is a risk of the glass window being damaged by the tensile stress in the circumferential direction.
[0012]
(2) When the diameter of the disk-shaped glass window is increased, the load due to the vacuum pressure applied to the disk-shaped glass window increases in proportion to the square of the diameter (D _W ). The thickness (H) needs to be a plate thickness that can sufficiently withstand the tensile stress caused by this load, and the ratio of the diameter (D _W ) to the plate thickness (H) must be about 10-15. Therefore, for example, in a glass window having a diameter of 1000 mm, it is necessary to make the plate thickness at least 70 mm, and the weight becomes about 120 kg.
[0013]
Furthermore, in the case of processing by forming plasma in the chamber container, the glass window is heated from the inner surface and naturally cooled on the outer surface in contact with the outside air. Then, a big temperature difference arises also in the thickness direction. Furthermore, the temperature difference in the radial direction is combined by the cooling water described above, and the conditions for the tensile stress of the glass window become more severe.
[0014]
In the case of a so-called dome-shaped glass window that protrudes in the center compared to the flange surface at the end, the distance between the heating means and the work table is separated, so the object on the work table with a large area is separated. It is difficult to heat-treat the work uniformly.
[0015]
The present invention has been made in view of the above points, and its purpose is to solve the above-described problems, reduce the stress applied to the large-diameter glass window, and avoid the risk of breakage. Another object of the present invention is to provide a highly safe reduced pressure heat treatment apparatus.
[0016]
[Means for Solving the Problems]
In order to achieve the above object, in the present invention,
An opening provided on one surface of the chamber containing the work table is hermetically covered with a glass window made of, for example, transparent quartz glass with a vacuum O-ring interposed on the flange surface, and the inside is kept in a reduced pressure state. In a reduced-pressure heat treatment apparatus that heats the object loaded on the work table by a heating means such as an infrared lamp heater or a high-frequency induction coil arranged outside the glass window,
(1) Pressurizing means for pressurizing the side surface of the glass window having a circular shape from the outside, for example, the flange surface of the chamber, the glass window, the outer surface and the side surface of the side edge of the glass window, A fixing flange having a substantially Z-shaped cross section coupled to the flange surface, a first pressurizing O-ring disposed between the flange surface of the chamber and the glass window, the flange surface of the chamber and the fixing flange; A second pressurizing O-ring disposed between the glass window and the third pressurizing O-ring disposed between the glass window and the fixing flange is provided through the fixing flange in an airtight manner. The compressed air is supplied from the introduced port, and a pressurizing means for pressurizing the side surface of the glass window from the outside is provided.
[0017]
(2) Further, the third pressurization O-ring is provided inside the opening in the radial direction as compared with the first pressurization O-ring.
(3) Further, an injection groove for injecting a volatile organic solvent from the outside or supplying compressed air between the vacuum O-ring and the first pressure O-ring arranged on the flange surface is a chamber. To prepare for.
[0018]
(4) Further, the glass window is formed in an integrated shape of a thin spherical central portion projecting outward from the chamber and a thick flange portion annularly arranged outside the glass window. To do.
[0019]
As described above, when the diameter of the glass window of this type of reduced pressure heat treatment apparatus is increased, a tensile stress is applied in the circumferential direction in the vicinity of the outer periphery of the glass window due to a temperature difference in the radial direction, as shown in FIG. Although there was a risk of breakage in the configuration, as described in (1) above, if a pressure means for pressurizing the side surface of the glass window from the outside is provided and the compression pressure from the side surface is applied to the glass window, the glass window The tensile stress in the circumferential direction applied to the vicinity of the outer periphery is relieved, and breakage due to the tensile stress can be avoided.
[0020]
As in (2) above, if the relationship between the position (diameter D1) of the first pressure O-ring and the position (diameter D3) of the third pressure O-ring is D3 <D1, the glass window (diameter the distance between the end and the two pressurizing O-ring D _W) is (since D _w -D3)> become (D _w -D1), the space formed airtight as described above in (1) When compressed air is introduced, not only is the air compressed from the side, but also a pressure is applied to push the glass window toward the chamber, so that the airtightness can be more reliably maintained.
[0021]
Further, if the O-ring is heated by heat conduction and may be difficult to remove due to close contact with the glass window as described in (3) above, a volatile organic substance is externally introduced through the injection groove. If the solvent is injected, the O-ring is easily detached, so that the maintenance is simplified and the operation efficiency is improved.
[0022]
Further, if the shape of the central portion of the glass window is a partial spherical shape having a large diameter as described in (4) above, the required thickness can be reduced, so that the glass window can be reduced in weight without extremely reducing the strength. be able to. In addition, in the case of an apparatus in which the glass window is heated from the inside, the temperature difference in the thickness direction can be reduced by reducing the thickness of the central portion, so that the internal stress of the glass window is reduced. .
[0023]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to FIGS. Of the components shown in FIG. 1 and FIG. 2, components having the same functions as those of the conventional component shown in FIG.
<Example 1>
1A and 1B are explanatory views showing a basic configuration of Embodiment 1 of the reduced pressure heat treatment apparatus of the present invention, wherein FIG. 1A is a longitudinal sectional view of a processing container, and FIG. 1B is an enlarged view of a portion A shown in FIG. It is.
[0024]
As shown in FIG. 1 (a), the basic structure of the reduced-pressure heat treatment apparatus of this configuration is the same as the basic structure of the conventional example shown in FIG. 3, but the structure of the portion A indicated by a dotted circle, That is, the attachment structure of the disc-shaped glass window 2 to the chamber 1 is different.
[0025]
In the configuration of the present embodiment, as seen in FIG. 1B, a disc-shaped glass window 2 is provided on the inner peripheral side of the flange portion 1a of the opening provided in the upper portion of the cylindrical chamber 1. A setting seat surface for setting and a fixing seat surface to which a fixing flange for fixing the disc-shaped glass window 2 is connected to the outer peripheral side are provided. Among these, on the inner set side seating surface, in order from the inside to the outside, the vacuum O-ring 9, the heat-resistant first support ring 10 formed in a flat shape, the first pressurizing O A ring 11 and a set ring 12 for positioning the disk-shaped glass window 2 made of the same material as the first support ring 10 are arranged in order. Further, the fixing seat surface on the outer peripheral side fixes a fixing flange 3 having a substantially Z-shaped cross section provided to pressurize and support the outer peripheral end portion of the disc-shaped glass window 2 from the upper surface to the flange portion 1a. It is a surface to be fixed, and is fixed by a plurality of fixing bolts 16 that are uniformly arranged over the entire circumference on the outer peripheral side of the fixing seat surface. A second pressurizing O-ring 13 is disposed on the inner peripheral side of the fixing seat surface. The position between the upper edge of the outer peripheral portion of the disk-shaped glass window 2 and the surface of the fixing flange 3 that pressurizes and supports the disk-shaped glass window 2 is relatively greater than the position where the first pressure O-ring 11 is disposed. A third pressurizing O-ring 14 is disposed on the inner side, and a flat spacer ring 15 formed of the same material as that of the first support ring 10 is disposed on the outer side. The spacer ring 15, together with the first support ring 10 and the set ring 12, plays a role of preventing direct contact between the disc-shaped glass window 2 and the metal flange portion 1 a or the fixed flange 3. With the above configuration, the flange portion 1a, the fixed flange 3, the disc-shaped glass window 2, the first pressurizing O-ring 11, the second pressurizing O-ring 13, and the third pressurizing O-ring 14 are used to form a circle. A sealed space is formed in contact with the side surface of the flat glass window 2. On the other hand, a pressurization port 17 communicating with the sealed space is provided on the side surface of the fixed flange 3, and compressed air is supplied through the pressurization port 17.
[0026]
Therefore, during the heat treatment operation, even when the disk-shaped glass window 2 is heated to a high temperature and is subjected to tensile stress at the outer periphery due to a temperature difference in the radial direction, The compressed air introduced through the pressurizing port 17 applies a uniform compressive force over the entire circumference, so that the stress associated with the temperature difference is relaxed, and the disc-shaped glass window 2 functions safely without being damaged. .
[0027]
Although not shown in FIG. 1, a supply port communicating between the vacuum O-ring 9 and the first pressurization O-ring 11 is provided on the set seating surface of the flange portion 1 a of the chamber 1. When the disk-shaped glass window 2 is removed after the heat treatment is completed, for example, a volatile organic solvent (such as methyl alcohol) is injected from this supply port, and then compressed air is supplied. Even when the vacuum O-ring 9 is in close contact with the disc-shaped glass window 2, the vacuum O-ring 9 can be easily detached, so that maintenance can be performed in a short time. Therefore, it is particularly effective for maintenance of an apparatus provided with a large-diameter disk-type glass window 2.
[0028]
In this embodiment, an infrared lamp heater is used as the heating means 7, but a high-frequency induction coil can be used as the heating means 7 to generate plasma and use this to process the object to be processed.
<Example 2>
FIG. 2 is an explanatory view showing the basic configuration of Embodiment 2 of the reduced-pressure heat treatment apparatus of the present invention, (a) is a longitudinal sectional view of a processing container, (b) is a glass window incorporated in (a). It is an enlarged view.
[0029]
The difference between the configuration of the present embodiment and the configuration of the first embodiment shown in FIG. 1 lies in the configuration of the glass window. In the first embodiment, the large-diameter disk-type glass window 2 was used. In this embodiment, a spherical glass window 18 having a shape of a partial spherical shell with a central portion protruding outward is used.
[0030]
As shown in FIG. 2 (b), the spherical glass window 18 includes a central spherical shell portion and an outer flange 18a that is fixed to the flange portion 1a of the chamber 1 by pressing with a fixing flange. It is comprised as a connection body. If the diameter of the opening of the chamber 1 is the same as that of the apparatus shown in FIG. 1, the thickness (H) of the outer flange 18a at the end is the same as the thickness of the disc-shaped glass window 2 of FIG. The width may be about 1/2 to 1/5 of the difference between the diameter (D _w ) of the spherical glass window 18 and the inner diameter (D) of the chamber 1. Further, the inner surface of the central portion of the spherical glass window 18 is disposed at a position higher than the surface fixed to the flange portion 1a of the chamber 1 by a height S, and this position and the outer flange 18a are connected to the inner diameter (D of the chamber). ) Are connected by a spherical surface with a radius of curvature (R1) more than twice. On the other hand, the outer surface of the central portion is disposed at a height not exceeding the height of the outer flange 18a, and this position and the outer flange 18a have a curvature radius (R2) larger than the curvature radius (R1) of the inner surface. They are connected by spherical surfaces, and the thickness (t1) of the central portion is configured to be at least 1/2 or more of the thickness (H) of the outer flange 18a. The curved glass window 17 is formed so that the thickness (t1) of the center portion is equal to or less than the thickness (t2) at the position where the outer flange 18a and the spherical surface intersect in order to prevent damage due to stress concentration. It is preferable to do this.
[0031]
Since the spherical glass window 18 of this configuration does not protrude from the end portion, it does not affect the installation position of the heating means disposed on the outside, and is the same as the disk type glass window 2 of the first embodiment. In addition, the object to be processed on the work table can be heated. Further, in this configuration, since the thickness can be reduced by making the spherical shape strong against pressure from the outside, the weight can be reduced and it is particularly effective when performing maintenance. Moreover, since the thickness is reduced, the temperature difference in the plate thickness direction is reduced, and the generated thermal stress can be suppressed.
[0032]
【The invention's effect】
As described above, according to the present invention, the following effects can be obtained.
(1) Since the compressive force acts on the side surface of the glass window arranged in the flange portion of the chamber, the tensile stress generated in the outer peripheral portion of the glass window is relieved by the temperature difference caused by the heat treatment. Even in an apparatus having a large-diameter glass window and capable of large-area heat treatment, the risk of breakage is avoided, and a highly safe reduced-pressure heat treatment apparatus is obtained.
[0033]
(2) Moreover, if said glass window is comprised in a partial spherical shape, compared with a disk-shaped glass window, the plate | board thickness of the center part of the glass window heated can be made thinner than a disk shape. Therefore, the temperature difference in the plate thickness direction can be reduced, and the thermal stress is relaxed. In addition, since the weight is reduced, handling of the glass window is simplified and maintenance is facilitated.
[Brief description of the drawings]
BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is an explanatory view showing a basic configuration of Embodiment 1 of a reduced-pressure heat treatment apparatus of the present invention, where (a) is a longitudinal sectional view of a processing vessel, and (b) is an enlarged view of a portion A shown in (a). FIGS. 2A and 2B are explanatory views showing a basic configuration of Embodiment 2 of the reduced-pressure heat treatment apparatus of the present invention, wherein FIG. 2A is a longitudinal sectional view of a processing vessel, and FIG. 2B is a view of a glass window incorporated in FIG. FIG. 3 is an explanatory view showing an example of the basic configuration of this type of conventional low pressure heat treatment apparatus, wherein (a) is a longitudinal sectional view of the processing vessel, and (b) is an enlarged view of part B shown in (a). Figure [Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Chamber 1a Flange part 2 Disc-shaped glass window 3 Fixed flange 4 Worktable 5 Gas inlet 6 Exhaust port 7 Heating means 8 Cooling water groove 9 Vacuum O ring 10 Support ring 11 First pressurization O ring 12 Set ring 13 Second O-ring for pressurization 14 Third O-ring 15 Spacer ring 16 Fixing bolt 17 Pressurization port 18 Spherical glass window 18a Outer flange

Claims (6)

An opening provided on one surface of the chamber containing the work table is hermetically covered with a glass window with a vacuum O-ring interposed on the flange surface, and the interior is kept in a reduced pressure state, and the substrate loaded on the work table is covered. In a reduced-pressure heat treatment apparatus that heat-treats a processed object by a heating means arranged outside the glass window,
Pressurizing means for pressurizing the side surface of the glass window from the outside is provided,
The pressurizing means has a substantially Z-shaped cross section that covers the flange surface in the chamber, the glass window, the outer surface and the side surface of the side edge of the glass window, and is joined to the flange surface of the opening by a fixing bolt. A fixing flange, and a first pressurizing O-ring disposed between the flange surface of the chamber and the glass window; a second pressurizing O-ring disposed between the flange surface of the chamber and the fixing flange; Compressed air supplied from an introduction port provided penetrating the fixed flange in a space formed hermetically by a third pressurizing O-ring disposed between the glass window and the fixed flange,
The third pressurizing O-ring is provided on the inner side in the radial direction of the opening compared to the first pressurizing O-ring.
A reduced-pressure heat treatment apparatus. The chamber is provided with a groove for injecting a volatile organic solvent from the outside or supplying compressed air between the vacuum O-ring and the first pressure O-ring arranged on the flange surface. The reduced-pressure heat treatment apparatus according to claim 1. The reduced-pressure heat treatment apparatus according to claim 1 or 2, wherein the glass window is formed in a disk shape. The glass window is formed in an integral shape with a thin spherical central portion projecting outward from the chamber and a thick flange portion annularly arranged on the outside thereof. The reduced-pressure heat treatment apparatus according to claim 1 or 2. The reduced-pressure heat treatment apparatus according to any one of claims 1 to 4, wherein the glass window is made of transparent quartz glass. The reduced-pressure heat treatment apparatus according to any one of claims 1 to 5, wherein the heating unit is an infrared lamp heater or a high-frequency induction coil.

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