JP2883157B2 - Vertical heat treatment equipment for substrates - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention performs various heat treatments such as oxidation, annealing, CVD (chemical vapor deposition), and diffusion on various substrates such as semiconductor substrates and ceramic substrates. The present invention relates to a vertical heat treatment apparatus for a substrate.

<Prior Art> In this type of vertical heat treatment apparatus for a substrate, when outside air enters the furnace core tube when the substrate boat is inserted into or removed from the furnace core tube or when the substrate boat is extracted, the substrate holding the substrate is held. When the heat treatment is performed by inserting the boat into the furnace core tube, for example, it becomes impossible to control the amount of supplied oxygen, or promote the growth of a natural oxide film on the substrate held by the substrate boat, or There has been a problem that impurities such as carbon dioxide gas adhere to the substrate and adversely affect oxidation and CVD processes.

Therefore, conventionally, the following configuration has been adopted in order to prevent outside air from entering the furnace core tube.

A. First Conventional Example An annular exhaust port surrounding the opening is provided horizontally outside the opening for inserting and removing the substrate boat, an inert gas such as N ₂ gas is introduced into the furnace core tube, and flows out from the opening. Along with the inert gas, outside air that is going to enter the furnace core tube is exhausted from the annular exhaust port.

B. Second Conventional Example Although it is a horizontal type, as disclosed in Japanese Patent Application Laid-Open No. 61-288415, a tube is formed at an open end of a reaction tube in and out of a substrate boat from all directions perpendicular to the tube axis. An inert gas is blown toward the axis to form an air curtain, and the air curtain partitions the inside and outside of the reaction tube, thereby preventing outside air from entering the inside of the reaction tube.

<Problems to be solved by the invention> However, both of the first and second conventional examples have the following disadvantages.

a. Disadvantages of the first conventional example The inert gas introduced into the furnace core tube is blown out at high speed in and around the furnace core of the furnace core tube, but the pressure decreases near the inner peripheral surface of the furnace core tube. As a result, there is a drawback that the air becomes negative pressure and the outside air enters the furnace core tube.

In addition, if the suction from the annular exhaust port is not uniform over the entire circumference of the annular exhaust port, the air pressure partially decreases near the relatively weakly sucked portion of the exhaust port, and the pressure inside the furnace core tube is reduced. There is a drawback that an airflow is generated such that outside air flows into the furnace core tube and the outside air enters the furnace core tube.

b. Disadvantages of the second conventional example There is a disadvantage that the blown-in inert gases collide with each other on the tube axis side of the reaction tube to generate a complicated three-dimensional flow and take in outside air into the reaction tube. In addition, there is a disadvantage that the air curtain disappears when entering and exiting the substrate boat, so that outside air easily flows in.

The present invention has been made in view of such a situation, and the outside air is provided in any of a state where the substrate boat is inserted into and removed from the furnace core tube and a state where the substrate boat is removed from the furnace core tube. An object of the present invention is to prevent entry into a furnace core tube.

<Means for Solving the Problems> In order to achieve the above-described object, the present invention provides a vertical heat treatment apparatus for performing heat treatment on a substrate, which is installed such that a tube axis direction is directed up and down. A furnace inlet tube provided with a gas introduction hole for supplying gas at the upper end side, an opening at the lower end side, heating means provided around the furnace core tube, and the furnace through an opening of the furnace core tube. A substrate boat that can be inserted into and removed from the core tube and holds the substrate, and in a state where the substrate boat is in the furnace core tube, is mounted on an upper end of the substrate boat and has an inner peripheral surface of the furnace core tube. A gas flow regulating member that regulates a gas flow so that a gas supplied from the gas introduction hole into the furnace core tube flows down in the annular gap, and the substrate boat includes the substrate boat. In a state outside the furnace core tube, the opening of the furnace core tube A stopper for supporting the gas flow regulating member at a position.

<Operation> When the substrate boat is inserted into and removed from the furnace core tube, the gas flow restricting member is moved up and down together with the substrate boat with the gas flow restricting member placed on the upper end of the substrate boat, and the gas introduced into the furnace core tube is subjected to gas flow restriction. It flows down in an annular gap formed between the member and the inner peripheral surface of the furnace core tube. In the annular gap, the gas flows down in a uniform downward flow over the entire circumference of the furnace core tube. Then, even below the gas flow regulating member, the gas flows down the gap formed between the substrate boat or the substrate and the inner peripheral surface of the furnace core tube while maintaining such a uniform flow in the circumferential direction.

Therefore, there is no occurrence of an airflow in which outside air flows upward so as to pass upward through the gap between the substrate boat or the substrate and the inner peripheral surface of the furnace core tube.

In addition, there is no airflow on the tube axis side than the gap between the substrate boat or the substrate and the inner peripheral surface of the furnace core tube, and the substrate or the substrate boat may block airflow in the vertical direction. There is no flow of outside air that passes through the tube shaft side and flows into the furnace core tube.

As described above, when the substrate boat is inserted into or removed from the furnace core tube, an airflow such that outside air flows into the furnace core tube does not occur.

Further, when the substrate boat is completely extracted from the furnace core tube, the gas flow regulating member is supported by the stopper,
The gas is located at the opening position at the lower end of the furnace core tube, and at this position, the gas flowing down in the furnace core tube passes through an annular gap formed between the gas flow regulating member and the inner peripheral surface of the furnace core tube. In the annular gap, the gas flows down as a uniform downward flow over the entire circumference of the furnace core tube as described above, and there is no flow of outside air passing upward through the gap. Therefore, even when the substrate boat is completely extracted from the furnace core tube, an airflow such that outside air flows into the furnace core tube does not occur.

<Example> Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

First Embodiment FIG. 1 is a longitudinal sectional view of a first embodiment of a vertical heat treatment apparatus for a substrate, and a furnace formed of a quartz material having infrared transmittance so that a tube axis direction is directed up and down. Core tube body
1a is provided, and a gas introduction hole 2 for supplying a N ₂ gas or a reactive gas as a purge gas is provided at an upper end side of the furnace core tube main body 1a in the tube axis core direction. The diameter of the inner peripheral surface of the core tube main body 1a is the same as that of the core tube main body 1a, and a metal inner cylinder 1b is additionally provided. The furnace core tube main body 1a and the inner cylinder 1b correspond to the “furnace core tube” in the configuration of the present invention, and hereinafter, the furnace core tube main body 1a and the inner cylinder 1b
Are generally referred to as a furnace core tube 1.

The substrate boat 3 holding the substrates W is inserted into and removed from the opening 4 at the lower end of the inner cylinder 1b into the furnace core tube 1 and out of the furnace core tube 1. This corresponds to the “opening of the furnace core tube” in the configuration of the present invention.

A purge gas supply unit (not shown) and a reactive gas supply unit (not shown) are connected to the gas introduction hole 2 so as to be selectively connected to each other.

Around the furnace core tube main body 1a, a heating means 5 comprising a first heater 5a, a second heater 5b, and a third heater 5c, which are short in the axial direction of the tube, is provided.

An annular exhaust pipe 7 having an exhaust port 6 is provided around the inner cylinder 1b.
A scavenger 8 formed of
Is inserted into and removed from the furnace core tube main body 1a, and when the substrate boat 3 is pulled out of the furnace core tube main body 1a in an empty state, it is introduced into the furnace core tube main body 1a through the gas introduction hole 2 and flows out from the opening 4. The outside air around the opening 4 is exhausted to an exhaust port 6 together with a purge gas composed of an inert gas such as N ₂ gas.

Further, an exhaust pipe 9 is provided so as to penetrate the exhaust pipe 7 and open inside the inner pipe 1b, and the substrate boat 3 holding the substrate W is provided.
Is inserted into the furnace core tube 1, and the reaction gas such as pure oxygen is discharged from the gas introduction hole 2 while the opening 4 is covered with the furnace port cap 10, and is discharged from the exhaust pipe 9. Have been.

Exhaust means (not shown) is connected to the exhaust port 6 and the exhaust pipe 9.

The substrate boat 3 is formed by integrally providing quartz plate bodies 3a and 3b on both ends in the longitudinal direction of three transparent support columns 3c made of quartz for substrate support and provided at intervals in the circumferential direction. It is configured.

Each of the pillars 3c is formed with a substrate insertion groove (not shown) at a minute pitch in the longitudinal direction, and is configured so that a required outer edge of the substrate W can be inserted and supported at three points.

On one (lower side in the drawing) plate body 3a side, a heat insulating support member 13 in which heat insulating plates 12 are attached to columns 11 is provided.

In the figure, reference numeral 14 denotes an elevating support arm. The elevating support arm 14 is driven up and down to hold the furnace port cap 10, and the substrate boat 3 supported on the furnace port cap 10 is raised and lowered to form a furnace core tube. 1.

As shown in a partially cutaway front view of a main part of FIG. 1 and FIG. 2 and a perspective view of a main part of FIG. 3, gas from a gas introduction hole 2 is introduced into a furnace core tube 1. A cap-shaped gas flow regulating member 15 that diffuses radially from the center of the core tube 1 to the inner peripheral surface side
On the other hand, a stopper 16 for receiving and supporting the gas flow regulating member 15 in a state where the substrate boat 3 is pulled out at a predetermined interval in the circumferential direction on the inner peripheral surface of the inner cylinder 1b constituting the furnace core tube 1. … Is attached.

The gas flow restricting member 15 is formed of a material that is not affected by the reaction gas, such as quartz.

On the plate 3b on the upper side of the substrate boat 3, auxiliary pillars 3d protrude separately from the three pillars 3c penetrating the plate 3b, and when the substrate boat 3 is inserted into and removed from the furnace core tube 1. In addition, at the time of heat treatment, the gas flow restricting member 15 can be stably supported by the columns 3c... And the auxiliary columns 3d.

With the above configuration, when the substrate boat 3 is inserted into and removed from the furnace core tube 1, the purge gas is caused to collide with the upper surface of the gas flow regulating member 15 by supplying the purge gas from the gas introduction hole 2. Radially diffuses into the inner peripheral surface of the
The gas flows toward the opening 4 through an annular gap formed between the outer periphery of the gas flow regulating member 15 and each of the substrates W held on the substrate boat 3 and the inner peripheral surface of the furnace core tube 1. It can be discharged to the outside and discharged through the scavenger 8 without taking in outside air.

On the other hand, when the substrate boat 3 is pulled out of the furnace core tube 1, the gas flow regulating member 15 is received and supported by the stoppers 16. It collides with the central portion and diffuses toward the inner peripheral surface side of the furnace core tube 1, and at the opening 4 side through an annular gap formed between the outer peripheral surface of the gas flow regulating member 15 and the inner peripheral surface of the inner cylinder 1 b. It can be flushed, drained out of the opening 4 and discharged through the scavenger 8.
At this time, the gas flow regulating member 15 covers most of the opening 4 at a position close to the opening 4, and the furnace is located between the outer peripheral surface of the gas flow regulating member 15 and the inner peripheral surface of the inner cylinder 7 b of the exhaust cylinder 7. A purge gas that forms a narrow annular gap communicating the inner space of the core tube 1 with the outside and collides with the center of the upper surface of the gas flow regulating member 15 radially flows toward the inner peripheral surface side of the furnace core tube 1. The purge gas flows into the annular gap, and in this annular gap, the purge gas flows down as a uniform downward flow over the entire circumference of the furnace core tube 1. Does not occur. Therefore, even when the substrate boat 3 is completely extracted from the furnace core tube 1, an airflow that flows into the furnace core tube 1 does not occur.

Second Embodiment FIG. 4 is a partially cutaway perspective view showing a gas flow regulating member of a second embodiment, in which a gas flow regulating member 15 is formed of a flat plate.

Third Embodiment FIG. 5 is a partially cutaway perspective view showing a gas flow restricting member according to a third embodiment, in which a gas flow restricting member 15 is formed of a circular box whose top and bottom are covered.

Fourth Embodiment FIG. 6 is a partially cutaway perspective view showing a gas flow restricting member of a fourth embodiment, in which a gas flow restricting member 15 is a circular flat plate 15a.
And a cylinder 15b having a smaller outer diameter than the flat plate 15a.

Fifth Embodiment FIG. 7 is a partially cutaway perspective view showing a gas flow regulating member according to a fifth embodiment. The upper surface of the gas flow regulating member 15 against which the purge gas collides has a smooth curved surface F1 protruding toward the center. The purge gas colliding with the upper surface of the gas flow regulating member 15 is configured to be diffused toward the inner peripheral surface side of the furnace core tube 1 and flow easily.

Sixth Embodiment FIG. 8 is a partially cutaway perspective view showing a gas flow regulating member according to a sixth embodiment. The upper surface of the gas flow regulating member 15 against which the purge gas collides is a flat surface F2 at the center, and The purge gas, which is formed in a truncated cone shape including a curved surface F3 protruding toward the flat surface F2 and colliding with the upper surface of the gas flow regulating member 15, is supplied to the furnace core tube 1.
Is configured to be easily diffused toward the inner peripheral surface side of the device.

Seventh Embodiment FIG. 9 is a longitudinal sectional view of another embodiment of the substrate heat treatment apparatus. The furnace core tube main body 1a in the first embodiment is replaced by an outer furnace core tube body 20a and an inner furnace core tube described later. In the seventh embodiment, the outer furnace core tube body 20a, the inner furnace core tube body 20b, and the inner cylinder 1b are referred to as "furnace tube" in the seventh embodiment.
Is equivalent to

The outer furnace core tube main body 20a is a quartz cylindrical body having a gas inlet 22 formed at a required lower portion of a cylindrical surface and an upper end closed in a dome shape. The inner furnace core tube body 20b is a quartz cylindrical body. The gas introduced from the gas inlet port 22 into the gap between the outer furnace core tube body 20a and the inner furnace core tube body 20b rises in the gap, and is in the dome portion at the upper end of the outer furnace core tube body 20a. To change the flow downward and flow down in the inner furnace core tube body 20b in which the substrate is accommodated.

In the first embodiment, a purge gas is supplied from the gas introduction hole 2 in an empty state in which the substrate boat 3 has been extracted from the furnace core tube 1, and the oxygen concentration in the tube axis direction in the furnace core tube 1 is measured. The axis is the oxygen concentration (ppm), and the vertical axis is the length of the furnace core tube 1 in the tube axis direction, that is, the furnace length (mm).
When the distribution of oxygen concentration in the furnace core direction of the furnace core tube 1 was graphed, the result indicated by A in the graph of FIG. 10 was obtained.

The oxygen concentration in the atmosphere was 2 × 10
⁵ is ppm, according to the first embodiment of the present invention, the oxygen concentration is very low over the open end of core tube within 1, core tube 1
It was clear that the invasion of outside air into the air was successfully prevented.

<Effects of the Invention> As described above, according to the vertical heat treatment apparatus for a substrate of the present invention, when inserting and removing the substrate boat, the gas flow regulating member is placed on the upper end of the substrate boat, The gas introduced into the furnace core tube flows down through the annular gap formed between the gas flow regulating member and the inner peripheral surface of the furnace core tube as a uniform downward flow over the entire circumference in the circumferential direction. Even below the flow restricting member, while maintaining such a uniform flow in the circumferential direction, it flows down in the annular gap formed between the substrate boat or the substrate and the inner peripheral surface of the furnace core tube. Therefore, there is no occurrence of an airflow in which outside air flows upward so as to pass upward through the gap between the substrate boat or the substrate and the inner peripheral surface of the furnace core tube.

Further, when the substrate boat is completely extracted from the furnace core tube, the gas flow regulating member is supported by the stopper,
At the opening position of the lower end of the furnace core tube, the gas flowing down the furnace core tube at this position passes through an annular gap formed between the gas flow regulating member and the inner peripheral surface of the furnace core tube in the circumferential direction. It flows down as a uniform downward flow over the entire circumference, and does not generate a flow of outside air that passes upward through this gap. Therefore, even when the substrate boat is completely extracted from the furnace core tube, an airflow such that outside air flows into the furnace core tube does not occur.

Therefore, intake of outside air into the furnace core tube can be avoided,
At the time of heat treatment, the oxidation and CVD processes can be performed favorably by properly controlling the oxygen supply amount, so that the quality can be improved and the product yield can be increased.

[Brief description of the drawings]

The drawings show an embodiment of a vertical heat treatment apparatus for a substrate according to the present invention. FIG. 1 is a longitudinal sectional view of the first embodiment, FIG. 2 is a partially cutaway front view of a main part, and FIG. FIG. 4 is a perspective view of the part, and FIG.
FIG. 5 is a partially cutaway perspective view of the third embodiment, FIG. 6 is a partially cutaway perspective view of the fourth embodiment, FIG.
FIG. 8 is a partially cutaway perspective view of the fifth embodiment, FIG. 8 is a partially cutaway perspective view of the sixth embodiment, FIG. 9 is a longitudinal sectional view of the seventh embodiment, and FIG. It is a graph which shows the distribution of the oxygen concentration in the tube axis direction in an example. DESCRIPTION OF SYMBOLS 1 ... Furnace core tube 2 ... Gas introduction hole 3 ... Substrate boat 4 ... Opening 6 ... Exhaust port 15 ... Gas flow regulating member 16 ... Stopper 22 ... Gas introduction port W ... Substrate

Claims (1)

(57) [Claims] 1. A vertical heat treatment apparatus for a substrate for performing heat treatment on a substrate, wherein a gas introduction hole for supplying gas is provided at an upper end side, and a gas introduction hole is provided at a lower end side. A furnace core tube having an opening, heating means provided around the furnace core tube, a substrate boat that is insertable into and removable from the furnace core tube through the opening of the furnace core tube, and that holds a substrate; In a state where the substrate boat is in the furnace core tube, the substrate boat is placed on the upper end of the substrate boat and forms an annular gap with the inner peripheral surface of the furnace core tube. A gas flow regulating member that regulates a gas flow so that the gas supplied to the annular gap flows down, and in a state in which the substrate boat is outside the furnace core tube, A stopper for supporting the gas flow regulating member, and Vertical heat treatment device substrate, wherein was e.