JP3119708B2 - Heat treatment apparatus and heat treatment method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a heat treatment apparatus and a heat treatment method.

[0002]

2. Description of the Related Art For example, in a process of manufacturing a semiconductor device, various processes for heat-treating a semiconductor wafer are included. Such steps include, for example, oxidation diffusion processing, reduced pressure oxidation diffusion processing, CVD processing, and the like. For example, in an example of a vertical batch processing type heat treatment apparatus used for oxidative diffusion processing of a semiconductor wafer, a processing container in which a plurality of semiconductor wafers to be processed are disposed, and a processing container disposed around the processing container. A heat source and a heat insulating material arranged outside the heat source so as to surround the processing container are provided.

[0003] A wafer holder is used to arrange a plurality of semiconductor wafers in parallel in a processing container. The wafer holder is moved into the processing container via the lower opening of the processing container every time heat treatment is performed. You. A sealed chamber is provided below the lower opening of the processing container, and an elevating mechanism for the wafer holder is arranged in the sealed chamber. The elevating mechanism raises the wafer holder from the inside of the sealed chamber to the inside of the processing chamber, and lowers the wafer holder from the inside of the processing chamber to the inside of the sealed chamber. When the wafer holder is raised or lowered, the inside of the processing chamber communicates with the sealed chamber, so that the inside of the sealed chamber needs to be evacuated to a predetermined degree of vacuum.

[0004]

However, in the above-described heat treatment apparatus, the elevating mechanism of the wafer holder is disposed in the sealed chamber, and when the wafer holder is raised or lowered, the inside of the sealed chamber and the inside of the processing container communicate. Because of this structure, heavy metals such as nickel (Ni), copper (Cu), iron (Fe), aluminum (Al), etc., or impurities contained in grease or oil become particles from the elevating mechanism, resulting in a semiconductor. There was a problem of damaging the wafer. Further, since it is necessary to exhaust the inside of the sealed chamber, a large-capacity exhaust device is required, and there is a problem that the device becomes large.

An object of the present invention is to provide a heat treatment apparatus capable of performing a heat treatment without damaging an object to be processed by an impurity from an elevating mechanism. A second object of the present invention is to provide a heat treatment apparatus capable of reducing the volume of a space to be evacuated and reducing the size of the exhaust device. A third object of the present invention is to provide a heat treatment method capable of performing a heat treatment without damaging an object to be processed by impurities from an elevating mechanism.

[0006]

In order to achieve the above object, a heat treatment apparatus according to the present invention moves a workpiece holder holding a workpiece to a predetermined position in a processing vessel by an elevating mechanism. In the heat treatment apparatus for performing heat treatment, the elevating mechanism is disposed in an external atmosphere, and the object-to-be-processed holder is cut off from the external atmosphere by a stretchable bellows-shaped tube, so that the same atmosphere as the inside of the processing container is provided. It has been placed in,
The bellows-shaped pipe has a double pipe structure including an inner pipe and an outer pipe.
The gap between the inner tube and the outer tube is filled with gas,
A gas sensor for detecting gas is provided .

The heat treatment method according to the present invention is directed to a heat treatment method for performing heat treatment by moving a workpiece holder holding a workpiece to a predetermined position in a processing vessel by an elevating mechanism. Placed in an atmosphere, and the object-to-be-processed holding member is cut off from the external atmosphere by a bellows-shaped tube having a double-tube structure consisting of an inner tube and an outer tube, which is stretchable and the same as the inside of the processing container placed in the atmosphere, the gas filled in the gap between the inner tube and the outer tube in the bellows-shaped tube, when the pressure in the processing chamber and P _1, control the pressure P ₂ of the gap as follows And heat treatment. During movement of the object: P ₁ ≦ P ₂ <atmospheric pressure During heat treatment of the object: P ₁ > P ₂

[0008]

The lifting mechanism is arranged in an external atmosphere, and the workpiece holder is shielded from the external atmosphere by an elastic bellows-like tube and is placed in the same atmosphere as the processing chamber. No damage is caused by impurities from the lifting mechanism. Since the lifting mechanism is not hermetically closed, the volume of the entire device can be reduced, and the volume of the space to be evacuated is reduced, so that the exhaust device can be downsized. By forming the bellows-shaped tube into a double tube structure including an inner tube and an outer tube, a sealed structure can be maintained even when the inner tube is broken. The gas in the gap between the inner pipe and the outer pipe in the bellows-shaped pipe having a double pipe structure is filled with a gas, and a gas sensor for detecting the gas is provided. Can be properly adjusted.

Further, according to the heat treatment method of the present invention, the object to be processed can be smoothly heat-treated without being damaged by impurities from the lifting / lowering mechanism, and the gap in the bellows-like pipe having a double pipe structure can be formed. the pressure P _2, the relationship between the pressure P ₁ in the processing container, during the movement of the workpiece, since the P ₁ ≦ P ₂ <atmospheric pressure, pinholes in the inner tube of the bellows-shaped tube When this occurs, gas leakage in the processing container can be prevented, and during the heat treatment of the object to be processed, since P ₁ > P ₂ , a pinhole is generated in the inner tube of the bellows-shaped tube. Sometimes, there is no possibility that the gas in the gap between the inner tube and the outer tube enters the processing vessel, and it is possible to prevent the gas from being adversely affected on the object to be processed.

[0010]

Embodiments of the present invention will be described below. Although the following embodiment is an example in which a semiconductor wafer is used as an object to be processed, the present invention is not limited to a semiconductor wafer, and other objects to be processed such as an LCD can be used. .

Embodiment 1 FIG. 1 is a schematic sectional view of a heat treatment apparatus according to the present embodiment, and FIG. 2 is an enlarged schematic sectional view showing a main part. 1 is a semiconductor wafer as an object to be processed, 2 is a processing container, 3 is a wafer holder as an object to be processed, 4 is an elevating mechanism, 5 is a bellows-shaped tube, 6 is a heat source, and 7 is a heat insulating material. , 81 is a gas introduction pipe, 82 is a gas exhaust pipe, 91 is a lid member, 92 is a gate valve, 93 is a pre-processing chamber, 94 and 9
Reference numeral 5 denotes a vacuum spare chamber, reference numerals 96 and 97 denote semiconductor wafer transfer means, and reference numeral 98 denotes a gas exhaust pipe.

The bellows-shaped tube 5 has a double tube structure including an inner tube 51 and an outer tube 52. The inner tube 51 is preferably made of a material having excellent heat resistance, durability, stain resistance, corrosion resistance, and seal resistance, such as silicon carbide (SiC) and Teflon. The outer tube 52 is preferably made of a material having excellent durability and heat resistance, such as stainless steel (SUS). The outer tube 52 plays a role as protection, for example, when the inner tube 51 is broken before being replaced after long-term use for one to two years. One end of the bellows-shaped tube 5 is air-tightly connected to the lower wall 93A of the pre-processing chamber 93, and the other end is air-tightly connected to a drive arm 43 of the lifting mechanism 4 described later. Numeral 93B is a through hole provided in the lower wall 93A of the preliminary processing chamber 93, and the preliminary processing chamber 93 and the bellows-shaped tube 5 communicate with each other through the through hole 93B.

The length of the bellows-like tube 5 is
Is determined in consideration of the ascending and descending distance of, for example, 300 to
It is about 600 mm. Further, the inner diameter of the inner tube 51 is determined in consideration of the outer diameter of the wafer holder 3, for example, 50 to 6.
It is about 0 mm. The distance of the gap 53 between the inner pipe 51 and the outer pipe 52 is, for example, about 10 to 20 mm.

The gap 53 is preferably filled with a gas which does not adversely affect the process vessel 2 even if it enters the processing vessel 2, for example, an inert gas such as nitrogen (N ₂ ) or argon (Ar). Further, as shown in FIG. 2, a gas sensor 54 for detecting the pressure in the gap 53 is provided. The gas sensor 54 may be a sensor that directly detects the pressure in the gap 53, or may be a sensor that detects a gas leak such as a processing gas. For example, a PPM sensor can be used. 55, 56 are gas introduction / exhaust pipes, 57, 58
Is a gas flow passage. The pressure in the processing vessel 1 and the gap 53
The pressure is controlled in synchronization with the internal pressure.

The processing container 2 can be formed of, for example, quartz (SiO ₂ ). The processing container 2 has a cylindrical shape having an opening at the lower end.
Further, the semiconductor wafer 1 is separated from the heat source 6 and the heat insulating material 7 to separate the atmosphere of the semiconductor wafer 1 from the outside.

The wafer holder 3 is preferably made of a material having excellent heat resistance and low contamination, such as high-purity silicon carbide (SiC). In particular, high-purity silicon carbide (SiC) has better heat resistance than quartz (SiO ₂ ) and can sufficiently withstand a high temperature of about 1200 ° C., so that it is suitable as a material for an oxidation diffusion processing apparatus. It is.

The wafer holder 3 is quickly moved closer to the heat source 6 by the elevating mechanism 4, and is quickly moved backward after the heat treatment. The configuration of the lifting mechanism 4 is not particularly limited, but in a specific example, for example, the motor 4
1, a drive shaft 42, and a drive arm 43. The motor 41 is connected to the drive shaft 42, and the drive shaft 42 is provided with a screw. Is screwed to one end. As shown in FIG. 2, the drive arm 43 is configured such that an upper plate 43A and a lower plate 43B are airtightly connected via an O-ring 43C. The other end of the wafer holder 3 is airtightly connected to the lower plate 43B of the drive arm 43 via the O-ring 31. 4
4 is a fixing member, and 32 is a fastener such as a bolt. When the motor 41 rotates the drive shaft 42, the drive arm 43 moves up or down by the action of the screw provided on the drive shaft 42, and the wafer holder 3 rises or falls with the movement of the drive arm 43. Moving. Therefore, the motor 4
By controlling the rotation of 1 by the control circuit, the rising speed or the falling speed of the wafer holder 3 can be appropriately adjusted. The moving distance of the wafer holder 3 is, for example, 300 to
About 600 mm, and the moving speed is 50 to 200 mm /
It is preferable that the speed be rapid for at least sec.

During the heat treatment of the semiconductor wafer 1, it is preferable that the semiconductor wafer 1 be rotated about its center by a rotating mechanism (not shown). This rotation mechanism can be constituted by, for example, a motor.

The heat source 6 is provided on the processing surface 11 of the semiconductor wafer 1.
And is fixedly arranged on the upper inner wall of the heat insulating material 7. The heat source 6 is, for example, molybdenum disilicide (Mo).
It can be constituted by arranging resistance heating elements such as a wire of Kanthal (trade name) which is an alloy wire of Si ₂ ), iron (Fe), chromium (Cr) and aluminum (Al) in a plane. For example, molybdenum disilicide (MoSi ₂ ) can be used as a single wire, and Kanthal wire can be used as a coil. In particular, molybdenum disilicide (M
Since oSi ₂ ) can sufficiently withstand a high temperature of about 1800 ° C., it is suitable as a material for an oxidation diffusion processing apparatus.

The heat generating surface of the heat source 6 is
It is preferable that the shape is the same as that of the processing surface 11, that is, a circular shape, and that the outer diameter is at least twice the outer diameter of the semiconductor wafer 1. According to the heat source 6 that satisfies such conditions, the temperature difference between the central portion and the peripheral portion of the semiconductor wafer 1 can be sufficiently reduced, and the entire processing surface 11 of the semiconductor wafer 1 can be uniformly heated. For heat treatment. Further, it is preferable that the heat generating surface of the heat generating source 6 is arranged in parallel with the semiconductor wafer 1. Further, the heat generating surface of the heat source 6 may be a uniform flat surface as a whole, or a peripheral portion may be curved in a direction approaching the semiconductor wafer 1.

The temperature of the heat source 6 is preferably 100 to 300 ° C. higher than the maximum use temperature of the semiconductor wafer 1.
The heat source 6 is driven by a heating control unit (not shown). The temperature control is performed by arranging a temperature sensor (not shown) such as a thermocouple at an appropriate position of the heat source 6 and applying a detection signal therefrom. Can be based on

Further, a planar heat equalizing member (not shown) may be arranged between the heat source 6 and the semiconductor wafer 1. This heat equalizing member eliminates the heat generation unevenness when the heat source 6 has heat generation unevenness and sufficiently controls the radiant heat toward the semiconductor wafer 1 in the vertical direction. The heat equalizing member is made of a low-contamination material such as, for example, high-purity silicon carbide (SiC), and the heat generating source 6 is completely isolated from the processing space by the heat equalizing member. Even in the case of being made of a material containing a heavy metal that causes contamination, the contamination by the heavy metal can be effectively prevented. This heat equalizing member is disposed so as to face the processing surface 11 of the semiconductor wafer 1, and its outer diameter is preferably at least twice the outer diameter of the semiconductor wafer 1 as in the case of the heat source 6.

The heat insulating material 7 is made of, for example, alumina ceramics. The inner diameter of the heat insulating material 7 is preferably determined in consideration of the temperature of the semiconductor wafer 1. For example, when the semiconductor wafer 1 is 8 inches, the inner diameter is about twice as large as 400 to 50.
About 0 mmφ is preferable.

In the pre-processing chamber 93, the semiconductor wafer 1 is loaded and unloaded. That is, the heat-treated semiconductor wafer 1 is transferred to the wafer holder 3 by the transfer means 96 or 97.
Is transferred to a storage container (not shown) arranged outside via a vacuum preliminary chamber 94 or 95, and then another semiconductor wafer 1 to be processed next is transferred to the transfer means 96 or 97.
Is set in the wafer holder 3 from a storage container (not shown) via the pre-vacuum chamber 94 or 95.

According to this embodiment, the following operational effects can be obtained. (1) Since the elevating mechanism 4 is arranged in an external atmosphere, and the wafer holder 3 is cut off from the external atmosphere by an elastic bellows-like tube 5, the wafer holder 3 is placed in the same atmosphere as the processing chamber 2.
The semiconductor wafer 1 is prevented from being damaged by impurities from the elevating mechanism 4, and a smooth heat treatment can be performed. (2) Since the elevating mechanism 4 is placed in an external atmosphere and is not sealed, the volume of the entire apparatus can be reduced, and the apparatus can be a small space. (3) Since the lifting mechanism 4 is placed in an external atmosphere and is not sealed, the volume of the space to be evacuated is reduced, so that the exhaust device can be reduced in size, and the device as a whole can be reduced in size. (4) By forming the bellows-like tube 5 into a double tube structure including the inner tube 51 and the outer tube 52, a sealed structure can be maintained even when the inner tube 51 is broken, and a smooth heat treatment can be performed. Can be achieved. (5) The gap 53 between the inner pipe 51 and the outer pipe 52 in the bellows-shaped pipe 5 having a double pipe structure is filled with a gas, and a gas sensor 54 for detecting the gas is provided. The pressure in the gap 53 at the time of expansion and contraction can be appropriately adjusted, and as a result, the pressure in the processing vessel 2 can be well balanced with the atmospheric pressure, and the inner pipe 51 and the outer pipe can be adjusted. Excessive force is prevented from acting on 52, and shortening of the service life of tube 5 is prevented.

[Embodiment 2] In this embodiment, a heat treatment method of the present invention will be described. In the heat treatment method of the present embodiment, the heat treatment is performed as follows using, for example, the heat treatment apparatus shown in FIG. When the wafer holder 3 holding the semiconductor wafer 1 to be processed is moved to a predetermined position in the processing chamber 2 by the elevating mechanism 4 to perform the heat treatment, the elevating mechanism 4 is arranged in an external atmosphere, and Wafer holder 3
Is cut off from the external atmosphere by an elastic bellows-like tube 5 having a double-tube structure composed of an inner tube 51 and an outer tube 52, and is placed in the same atmosphere as the inside of the processing vessel 2, and the bellows-like tube 5 the gas was filled into the gap 53 between the inner tube 51 and outer tube 52 in, when the pressure in the processing container 2 and P _1, heat treatment of the pressure P ₂ of the gap 53 is controlled as follows. During the movement of the semiconductor wafer: P ₁ ≦ P ₂ <atmospheric semiconductor wafer during heat treatment: P _1> specific values of P ₂ P ₁ and P ₂ is determined according to the kind of heat treatment. Hereinafter, specific examples for each heat treatment will be described.

[Oxidation Diffusion Processing] During the heat treatment of the semiconductor wafer 1, the pressure P ₁ in the processing chamber ₂ is, for example, about atmospheric pressure ± 50 mmH ₂ O, and the pressure P _{2 in} the gap 53 at this time is, for example, P ₁ −1.0 to P ₁ -20 mmH ₂ O. When the semiconductor wafer 1 is moved up and down,
The pressure P ₁ in the processing vessel 2 is, for example, atmospheric pressure ± 10 mmH
And about ₂ O, the pressure P ₂ of the gap 53 at this time is, for example, P ₁ ~P ₁ + 10mmH ₂ O about.

[Depressurized Oxidation Diffusion Treatment] Before the heat treatment, the inside of the processing vessel 2 is first reduced to a pressure of, for example, 10 ⁻³ Torr in order to remove moisture in the processing vessel 2. Next, during the heat treatment of the semiconductor wafer 1, the pressure P ₁ in the processing chamber 2 is set.
Is, for example, about atmospheric pressure ± 50 mmH ₂ O. The pressure P ₂ of the gap 53 at this time is for example P ₁ -1.0~P ₁ -
And 20mmH ₂ O about. Further, at the time of lifting of the semiconductor wafer 1, the pressure P ₁ in the processing container 2, for example, the atmospheric pressure ± 10 mm H ₂ O of about, the pressure P ₂ of the gap 53 at this time is for example P ₁ to P ₁ + 10 mm H ₂ O Degree.

[Depressurized CVD process] Before the heat treatment, the inside of the processing chamber 2 is first depressurized to, for example, 10 ^-3 Torr. Next, during the heat treatment of the semiconductor wafer 1, the processing vessel 2
The internal pressure P1 is, for example, a reduced pressure of about _{1 to 10} Torr. The pressure P ₂ of the gap 53 at this time is for example 10 to 2
It is about 0 Torr. Further, when the semiconductor wafer 1 is moved up and down, the pressure P ₁ in the processing chamber 2 is, for example, 10 ^−2.
And about to 10 ^-3 Torr, the pressure P ₂ of the gap 53 at this time is, for example, 10 ^-1 to 10 ^-2 Torr or so.

According to this embodiment, the following effects can be obtained. After the semiconductor wafer 1 without damaging due to impurities from the lifting mechanism 4 can be smoothly heat treatment, the double pipe structure the pressure P ₂ of the gap 53 in the bellows-shaped tube 5, in the processing container 2 in the relationship between the pressure P _1,
At the time of movement of the semiconductor wafer 1, since P ₁ ≦ P ₂ <atmospheric pressure, it is possible to prevent gas leakage in the processing chamber 2 when a pinhole is formed in the inner tube 51 of the bellows-shaped tube 5. it can. In addition, since P ₁ > P ₂ during the heat treatment of the semiconductor wafer 1, when a pinhole is formed in the inner tube 51 of the bellows-like tube 5, a gap 53 between the inner tube 51 and the outer tube 52 is formed. There is no possibility that the gas enters the processing chamber 1, and it is possible to prevent the semiconductor wafer 1 from being adversely affected.

Although the present invention has been described based on the embodiments, the heat treatment apparatus and the heat treatment method of the present invention can be applied to any of a normal pressure process, a reduced pressure process, and a vacuum process. In addition, oxidation treatment, diffusion treatment, CVD
It can be applied to various heat treatments such as treatment and annealing. Further, the object to be processed is not limited to a semiconductor wafer, and may be another object to be processed such as an LCD (Liquid Crystal Display).

[0032]

As described above, according to the present invention, the following effects can be obtained. (1) According to the heat treatment apparatus of the first aspect, the heat treatment can be performed without damaging the object to be processed by impurities from the elevating mechanism. Further, the volume of the space to be evacuated can be reduced, and the exhaust device can be downsized. Furthermore, a snake
The inner tube is broken because the belly tube has a double tube structure
Sealing structure can be maintained even if
Fill the gas into the gap with the tube and provide a gas sensor
Therefore, the pressure in the gap during the expansion and contraction of the bellows-like tube can be appropriately adjusted. (2) According to the heat treatment method of the second aspect, the object to be processed can be smoothly heat-treated without causing damage from impurities from the elevating mechanism. Further, when the object to be processed is moved, gas leakage in the processing container can be prevented when a pinhole occurs in the inner tube of the bellows-shaped tube. further,
During the heat treatment of the object to be processed, when a pinhole is formed in the inner tube of the bellows-shaped tube, there is no danger that gas in the gap between the inner tube and the outer tube will enter the processing container, and It is possible to prevent adverse effects.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a heat treatment apparatus according to an embodiment of the present invention.

FIG. 2 is an enlarged schematic cross-sectional view showing a main part of a heat treatment apparatus according to an embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Semiconductor wafer 11 Processing surface 2 Processing container 3 Wafer holder 31 O-ring 32 Fastener 4 Lifting mechanism 41 Motor 42 Drive shaft 43 Drive arm 43A Upper plate 43B Lower plate 43C O-ring 44 Fixing member 5 Inside of bellows-like tube 51 Pipe 52 Outer pipe 53 Gap 54 Gas sensor 55 Gas introduction / exhaust pipe 56 Gas introduction / exhaust pipe 57 Gas flow path 58 Gas flow path 6 Heat source 7 Insulation material 81 Gas introduction pipe 82 Gas exhaust pipe 91 Cover member 92 Gate valve 93 Processing spare chamber 93A Lower wall of processing preliminary chamber 93B Through-hole 94,95 Vacuum preliminary chamber 96,97 Transfer means for semiconductor wafer 98 Gas exhaust pipe

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 21/205 H01L 21/22-21/24 H01L 21/31 H01L 21/365 H01L 21/38-21 / 40 H01L 21/469 H01L 21/86

Claims (2)

(57) [Claims] 1. A heat treatment apparatus for performing heat treatment by moving an object holder holding an object to be processed to a predetermined position in a processing container by an elevating mechanism, wherein the elevating mechanism is arranged in an external atmosphere, and The object-to-be-processed holder is placed in the same atmosphere as the inside of the processing container while being shielded from an external atmosphere by an elastic bellows-shaped tube, and the bellows-shaped tube is made of an inner tube and an outer tube. With a double-pipe structure
The gap between the inner tube and the outer tube is filled with gas,
A heat treatment apparatus comprising a gas sensor for detecting gas . 2. A heat treatment method for performing a heat treatment by moving an object holder holding an object to be processed to a predetermined position in a processing vessel by an elevating mechanism, wherein the elevating mechanism is disposed in an external atmosphere; The workpiece holder is placed in the same atmosphere as the inside of the processing container while being shielded from the external atmosphere by a bellows-like tubular body having a double-tube structure composed of an inner tube and an outer tube, which is stretchable. the gas was filled in the gap between the inner and outer tubes in the tube, when the pressure in the processing chamber and P _1, characterized in that heat treatment of the pressure P ₂ of the gap is controlled in the following manner Heat treatment method. During movement of the object: P ₁ ≦ P ₂ <atmospheric pressure During heat treatment of the object: P ₁ > P ₂