JPH05206047A - Heat treatment apparatus - Google Patents

Abstract

PURPOSE:To prevent an abrupt temperature change in a reaction tube from occurring when an object to be treated is brought in and out by the inner thickness of the part of the exit and entrance of the reaction tube in a heat treatment apparatus which is provided with the cylindrical reaction tube having the exit and entrance part on one end, and a heat source arranged to surround this reaction tube. CONSTITUTION:A covering member 5 is open when a semiconductor wafer W ascends and descends. At this juncture, the heat in a reaction tube 1 escapes to the outside. However, the thickness of the reaction tube 1 is made gradually grater from its upper part to the lower part of its exit and entrance portion. In this way, the heat capacity of the exit and entrance portion becomes great, thus controlling the temperature drop to be small in the exit and entrance portion even if the heat in the reaction tube 1 escapes when the covering member 5 is opened. Therefore, the semiconductor wafer W can be thermally treated stably in accordance with a predetermined correct temperature gradient, thus improving the uniformity of the temperature of the inner surface. Hence, it is possible to provide a stable heat treatment for an object to be treated.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a heat treatment apparatus.

[0002]

2. Description of the Related Art For example, in the manufacture of semiconductor devices, a semiconductor wafer is subjected to oxidation diffusion processing, CVD processing and the like. Especially recently, 0.4 μm to 0.2 μm
As the design rules of semiconductor devices have become finer and the diameter of semiconductor wafers has increased from 8 inches to 12 inches, rapid thermal processing equipment has been developed to support such ultra-thin film forming technology for large areas. Development is an urgent issue.

Specifically, in the process processing of a semiconductor wafer, it is an essential condition to reduce the thermal budget (thermal history). For example, a doping process of 50 to 100 Å, a gate oxide film or a capacitor insulating film In forming a thin film, rapid thermal processing, that is, thermal processing in a short time is essential. Further, for example, in order to reduce the resistance by making the PN junction as shallow as 0.1 μm or less and enable the formation of the junction on the surface of an arbitrary shape, it is necessary to prevent the film deterioration and the occurrence of crystal defects at the time of the junction. However, rapid thermal processing is required because the active region of the PN junction is narrow.

In addition, for example, in the formation of a LOCOS oxide film, the compressive stress of the adjacent LOCOS oxide film expands due to a synergistic effect due to the thermal cycle, and the reliability of surface potential fluctuation, leak current, breakdown voltage, etc. is likely to decrease. However, in order to prevent this, it is necessary to reduce the thermal cycle by rapid thermal processing. Further, for example, when a capacitor insulating film is formed using a high dielectric material, metal film formation and doping that enable film formation of metal oxide (Ta ₂ O _5, etc.), polyimide (passivation film), etc. It has become necessary to develop a system that can handle complex processes.

In the present situation where the diameter of the semiconductor wafer is increasing from 8 inches to 12 inches, the temperature difference between the central portion and the peripheral portion of the semiconductor wafer can be made small and uniform rapid thermal processing can be performed. It is necessary to reduce slips, distortions, and warps that are likely to occur on a wafer so as to avoid inconvenience in manufacturing semiconductor devices.

[0006]

In a conventional vertical single-wafer heat treatment apparatus, a cylindrical reaction tube having an inlet / outlet at one end and in which an object to be treated is arranged, and the reaction tube is surrounded. The semiconductor wafer is moved from the inlet / outlet to the processing space of the reaction tube, and heat treatment is performed by the heating source in a state where the inlet / outlet of the reaction tube is closed by the lid member. However, at the inlet / outlet side of the reaction tube,
To open the lid member when loading and unloading semiconductor wafers,
There is a problem that heat inside the reaction tube easily escapes, which causes a large decrease in temperature at the inlet / outlet side portion of the reaction tube, resulting in poor uniformity of in-plane temperature during movement of the semiconductor wafer.

On the other hand, it is possible to control the temperature of the inlet / outlet side portion of the reaction tube so as not to drop by the heating source.
When the lid member is opened, the temperature of the inlet / outlet side of the reaction tube drops sharply.Therefore, temperature control by the heating source causes the temperature of the inlet / outlet side of the reaction tube to rise above the prescribed appropriate temperature, and sufficient control is required. There was a problem that is difficult. An object of the present invention is to provide a heat treatment apparatus capable of preventing a rapid temperature change in the reaction tube when the object to be treated is taken in and out from the inlet and outlet of the reaction tube, and capable of stably heat treating the object to be treated. The purpose is to

[0008]

In order to achieve the above object, the heat treatment apparatus of the present invention comprises a cylindrical reaction tube having an inlet / outlet at one end and in which an object to be treated is arranged, and this reaction tube. In a heat treatment apparatus provided with a heating source arranged so as to surround it, the thickness of the inlet / outlet side portion of the reaction tube is increased. Further, in a heat treatment apparatus comprising a tubular reaction tube having an inlet / outlet at one end and in which an object to be treated is arranged, and a heating source arranged so as to surround the reaction tube, the inlet / outlet of the reaction tube The heat storage member is arranged in the side portion.

[0009]

Since the wall thickness of the inlet / outlet side portion of the reaction tube is increased, the heat capacity of the inlet / outlet side portion is increased.
When the object to be treated is taken in and out from the inlet / outlet of the reaction tube, a rapid temperature change in the reaction tube is prevented, and the object to be treated can be stably heat-treated. Further, instead of changing the wall thickness of the reaction tube itself, by disposing the heat storage member at the inlet / outlet side portion of the reaction tube, the same effect as described above is exhibited.

[0010]

EXAMPLES Examples of the present invention will be described below. Although the following embodiments are examples in which a semiconductor wafer is used as the object to be processed, the present invention is not limited to the semiconductor wafer, and other objects to be processed such as LCD may be used. it can.

[Embodiment 1] In this embodiment, a case of forming an oxidation / diffusion device for a semiconductor wafer will be described. Figure 1
FIG. 3 is a schematic view of a heat treatment apparatus according to this embodiment. W is a semiconductor wafer as an object to be processed, 1 is a reaction tube, 2 is a wafer holder, 3 is a heating source, 4 is a heat insulating material, 5 is a lid member, 6 is moving means, 71 is a gas introduction tube, and 72 is a gas. It is a discharge pipe.

The reaction tube 1 is made of a highly heat-resistant material, for example, high-purity quartz (SiO ₂ ) or the like, and has a cylindrical shape having an entrance / exit 11 at the lower end and a semiconductor wafer W disposed inside. ing. The wall thickness of the reaction tube 1 gradually increases from the upper portion to the lower inlet / outlet side portion. For example, the upper wall 1A has a thickness of about 2.5 mm, the intermediate wall 1B has a thickness of about 3.5 mm, and the lower wall 1C has a thickness of 5.0 mm.
It is a degree. In this way, since the wall thickness is large toward the inlet / outlet side portion, the heat capacity of the inlet / outlet side portion of the reaction tube 1 increases, and a rapid temperature change in the inlet / outlet side portion of the reaction tube 1 is prevented when the lid member 5 is opened. To be done.

The heating source 3 has a cylindrical shape, and the reaction tube 1
Are arranged so as to surround the outer periphery of the. This heating source 3
Consists of three heating elements 3A, 3B, 3C,
The temperature can be controlled separately. The heating source 3 is, for example, molybdenum disilicide (MoSi ₂ ),
It can be constituted by a resistance heating element such as Kanthal (trade name) wire which is an alloy wire of iron (Fe), chromium (Cr) and aluminum (Al). For example, molybdenum disilicide (MoSi ₂ ) can be used as a single wire and Kanthal wire can be used as a coil. In particular,
Since molybdenum disilicide (MoSi ₂ ) can sufficiently withstand a high temperature of about 1800 ° C., it is suitable as a material for an oxidation diffusion treatment device.

The wafer holder 2 is for holding the semiconductor wafer W, and is made of, for example, high-purity silicon carbide (Si).
It is preferable to use a material such as C) having excellent heat resistance and little pollution. In particular, high-purity silicon carbide (SiC) has better heat resistance than quartz (SiO ₂ ), and can withstand a high temperature of about 1200 ° C. sufficiently, so it is suitable as a material for an oxidation diffusion treatment device. Is.

The moving means 6 raises the wafer holder 2 holding the semiconductor wafer W into the reaction tube 1 when heat-treating the semiconductor wafer W, and moves the wafer holder 2 out of the reaction tube 1 when the heat treatment is completed. It is to lower it. When the heat treatment is performed, the semiconductor wafer W held by the wafer holder 2 is rapidly moved to the processing space above the reaction tube 1 by the moving means 6, and after the heat treatment, the semiconductor wafer W is moved to the wafer holder 2 by the moving means 6. The held semiconductor wafer W is rapidly lowered to the outside of the reaction tube 1. The movement distance of the wafer holder 2 is, for example, about 300 to 600 mm, and it is preferable that the movement speed is as rapid as 50 mm / sec or more. The configuration of the moving unit 6 is not particularly limited, but in FIG. 1, the moving unit 6 includes a motor 61, a drive shaft 62, and a drive arm 63. The motor 61 is connected to a drive shaft 62, and the drive shaft 62 is provided with a screw, and is screwed to one end of the drive arm 63 via the screw. Motor 61
When the drive shaft 62 rotates, the drive arm 63 moves up or down by the action of the screw provided on the drive shaft 62, and the wafer holder 2 moves up or down as the drive arm 63 moves. ..

During the heat treatment of the semiconductor wafer W, the rotating mechanism 6
It is preferable that the semiconductor wafer W is rotationally moved about the center thereof by 4. This rotating mechanism can be constituted by, for example, a motor.

The heat insulating material 4 is made of alumina ceramics, for example, and is arranged so as to surround the heat source 3.

A gas introduction pipe 71 and a gas discharge pipe 72 are connected to the reaction pipe 1, and the process gas is introduced and exhausted by these. During the oxidative diffusion process, a process gas is introduced into the reaction tube 1 from the gas introduction pipe 71, and the temperature in the processing space of the reaction tube 1 is changed to a predetermined temperature, for example, 950 to 950 by the radiant heat from the heating source 3.
The temperature is controlled to 1200 ° C. When the semiconductor wafer W is moved up and down, the temperature of the inlet / outlet side portion of the reaction tube 1 is controlled to be 200 to 300 ° C. by the radiant heat from the heating source 3.

The lid member 5 is for closing the inlet / outlet 11 of the reaction tube 1 during the oxidation diffusion process to maintain airtightness,
The semiconductor wafer W is opened each time it is taken in and out of the reaction tube 1.

According to the heat treatment apparatus of this embodiment, the lid member 5 is opened when the semiconductor wafer W is moved up and down, so that the heat in the reaction tube 1 escapes to the outside. However, since the wall thickness of the reaction tube 1 gradually increases from the upper portion to the lower inlet / outlet side portion, the heat capacity of the inlet / outlet side portion is large, and the heat inside the reaction tube 1 when the lid member 5 is opened. Even if there is an escape, the temperature drop at the inlet / outlet side portion is suppressed to a small level, the semiconductor wafer W can be stably heat-treated in accordance with a predetermined appropriate temperature gradient, and the in-plane temperature uniformity is improved.

[Embodiment 2] FIG. 2 is a schematic view of a heat treatment apparatus according to the present embodiment, which is an embodiment in the case where an oxidation / diffusion apparatus for a semiconductor wafer is constructed as in Embodiment 1. This example is the same as Example 1 except that the wall thickness of the reaction tube 1 is not increased steplessly as in Example 1 but is increased in three steps. As described above, the wall thickness of the reaction tube 1 may be increased stepwise, and in this case, the same operational effect as that of the first embodiment is exhibited. In this embodiment, the wall thickness is increased in three steps, but the number of steps is not particularly limited and may be any number.

[Embodiment 3] FIG. 3 is a schematic view of a heat treatment apparatus according to the present embodiment, which is an embodiment in the case where an oxidation / diffusion apparatus for a semiconductor wafer is constructed as in Embodiment 1. The present embodiment is the same as the first embodiment except that a heating source 31 is also provided above the reaction tube 1 and a soaking member 33 is provided between the heating source 31 and the reaction tube 1. The heating source 31 is fixedly arranged on the upper inner wall of the heat insulating material 4 so as to face the processing surface of the semiconductor wafer W located in the processing space in the reaction tube 1. The heating source 31 has a planar form, and is, for example, Kanthal (trade name) which is an alloy wire of molybdenum disilicide (MoSi ₂ ), iron (Fe), chromium (Cr), and aluminum (Al). It can be configured by arranging resistance heating elements such as wires 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,
Since molybdenum disilicide (MoSi ₂ ) can sufficiently withstand a high temperature of about 1800 ° C., it is suitable as a material for an oxidation diffusion treatment device.

The heating surface of the heating source 31 preferably has the same shape as the processing surface of the semiconductor wafer W, that is, a circular shape. Further, the outer diameter of the heating source 31 is preferably twice or more the outer diameter of the semiconductor wafer W. The heating surface of the heating source 31 is preferably arranged parallel to the semiconductor wafer W. The heat generation surface of the heat source 31 may be a flat surface as a whole, or the peripheral portion may be curved in a direction approaching the semiconductor wafer W.

The heat equalizing member 33 directs the radiant heat from the heating source 31 perpendicularly to the processing surface of the semiconductor wafer W. It is preferable that the heat equalizing member 33 is made of a material with less pollution such as high-purity silicon carbide (SiC). Further, the heat equalizing member 33 also plays a role of effectively preventing contamination by the heavy metal when the heating source 31 is made of a material containing a heavy metal that causes contamination.

According to the heat treatment apparatus of this embodiment, the radiant heat from the upper heating source 31 is absorbed by the semiconductor wafer W and contributes to the heat treatment, and in particular, the in-plane temperature uniformity during the heat treatment of the semiconductor wafer W is improved. Exerts the effect of enhancing. Further, when the semiconductor wafer W is below the reaction tube 1, the radiant heat from the upper heating source 31 also hits the inlet / outlet side portion of the reaction tube 1 and is heated by the semiconductor wafer W.
Is raised and positioned in the processing space above the reaction tube 1, the radiant heat from the upper heating source 31 is almost absorbed by the semiconductor wafer W, and hardly reaches the inlet / outlet side portion of the reaction tube 1. The temperature at the entrance / exit side tends to decrease. However, since the thickness of the inlet / outlet side portion of the reaction tube 1 is large and the heat capacity is increased, the temperature decrease is suppressed to a small level,
Therefore, there is no risk of overheating when the inlet / outlet side portion is over-controlled by the heating element 3C.

[Embodiment 4] FIG. 4 is a schematic view of a heat treatment apparatus according to the present embodiment, which is an embodiment in the case of configuring an oxidation / diffusion apparatus for a semiconductor wafer as in Embodiment 1. In this embodiment, except that the wafer holder 2 is also provided with the heating source 32,
The configuration is the same as that of the third embodiment. The heating source 32 preheats the wafer holder 2 when the wafer holder 2 is raised, and after the reaction tube 1 is closed by the lid member 5 until the temperature inside the reaction tube 1 becomes stable. Play a role in shortening the time.

[Embodiment 5] FIG. 5 is a schematic view of a heat treatment apparatus according to this embodiment, which is an embodiment in the case of configuring a CVD apparatus for semiconductor wafers. In this embodiment, the structure of the gas introduction pipe and the gas discharge pipe in the embodiment of FIG.
The structure is the same as that of the first embodiment except that the inner tube and the manifold are provided so as to be changed to fit the apparatus. 8
1A and 81B are gas introduction pipes, 82 is a gas discharge pipe, 83 is an inner pipe, and 84 is a manifold. The thickness of the reaction tube 1 is
It gradually increases from the upper part to the lower entrance side part. Further, the wall thickness of the inner pipe 83 gradually increases from the upper portion to the lower inlet / outlet side portion.
In CVD, the temperature of the semiconductor wafer W is 400 to 800 ° C. during the heat treatment, that is, in the processing space, and when the temperature is raised or lowered.
That is, it is 100 to 200 ° C. in the entrance side portion.
According to this embodiment, the same operational effects as those of the first embodiment are exhibited.

[Embodiment 6] FIG. 6 is a schematic view of a heat treatment apparatus according to the present embodiment, which is an embodiment in the case of forming an oxidation / diffusion device for a semiconductor wafer, and is an embodiment corresponding to claim 2. is there. In this embodiment, the wall thickness of the reaction tube 1 is made uniform, and, for example, high-purity quartz (SiO ₂ ) is provided at the inlet / outlet side portion of the reaction tube 1.
The structure is the same as that of the first embodiment except that the heat storage member 9 made of As described above, even if the thickness of the reaction tube 1 is uniform, by adding the heat storage member 9 to the inlet / outlet side portion of the reaction tube 1, it is possible to suppress the temperature change in the inlet / outlet side portion of the reaction tube 1 to be small. it can.

Although the present invention has been described above based on the embodiments, the heat treatment apparatus of the present invention can be applied to any of a normal pressure process, a reduced pressure process and a vacuum process. Further, it can be applied to various heat treatments such as annealing in addition to oxidation diffusion and CVD. The object to be processed is not limited to the semiconductor wafer, and may be another planar object such as an LCD.

[0030]

EFFECTS OF THE INVENTION According to the heat treatment apparatus of the present invention, it is possible to prevent a rapid temperature change in the reaction tube when the object to be treated is taken in and out of the inlet and outlet of the reaction tube, and to heat treat the object to be treated stably. be able to.

[Brief description of drawings]

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

FIG. 2 is a schematic sectional view of a heat treatment apparatus according to a second embodiment of the present invention.

FIG. 3 is a schematic sectional view of a heat treatment apparatus according to a third embodiment of the present invention.

FIG. 4 is a schematic sectional view of a heat treatment apparatus according to a fourth embodiment of the present invention.

FIG. 5 is a schematic sectional view of a heat treatment apparatus according to a fifth embodiment of the present invention.

FIG. 6 is a schematic sectional view of a heat treatment apparatus according to Example 6 of the present invention.

[Explanation of symbols]

W semiconductor wafer 1 reaction tube 11 entrance / exit 1A upper wall 1B intermediate wall 1C lower wall 2 wafer holder 3 heating source 3A, 3B, 3C heating element 31 heating source 32 heating source 33 heat equalizing member 4 heat insulating material 5 lid member 6 moving means 61 motor 62 drive shaft 63 drive arm 64 rotation mechanism 71 gas introduction pipe 72 gas discharge pipe 81A, 81B
Gas introduction pipe 82 Gas discharge pipe 83 Inner pipe 84 Manifold

Claims (2)

[Claims] 1. A heat treatment apparatus comprising a tubular reaction tube having an inlet and outlet at one end and in which an object to be treated is arranged, and a heating source arranged so as to surround the reaction tube. A heat treatment apparatus characterized in that the wall thickness of the inlet / outlet side of the pipe is increased. 2. A heat treatment apparatus comprising a cylindrical reaction tube having an inlet / outlet at one end and in which an object to be treated is arranged, and a heating source arranged so as to surround the reaction tube. A heat treatment apparatus, wherein a heat storage member is arranged at a portion on the inlet / outlet side of the pipe.